The stifle joint Flashcards
1
Q
What is the attachment point of the cranial cruciate ligament on the tibia?
A
The cranial intercondyloid area
2
Q
What is the attachment of the caudal cruciate ligament on the tibia?
A
The popliteal notch
3
Q
What is the name of the groove where the long digital extensor tendon runs on the lateral proximal tibia?
A
The extensor groove (the anterolateral aspect of this groove in people is called the tubercle of gerdy)
4
Q
The lateral and medial fabellae are located in the lateral and medial heads of origin of which muscle?
A
Gastrocnemius
5
Q
What is the role of the femoropatellar joint?
A
To increase the efficiency of the extensor mechanism by increasing the moment arm of the quadriceps muscles
6
Q
Is the stifle fat pad intra or extrasynovial?
A
Extrasynovial (between the fibrous and synovial layers of the joint capsule)
7
Q
Describe the ligaments of the stifle joint
A
8
Q
What are the structures that provide primary ligamentous support to the stifle?
A
Two collateral ligaments and two cruciate ligaments.
9
Q
What are the two bands of the cranial cruciate ligament?
A
Smaller craniomedial band, and larger caudolateral.
10
Q
What is the main difference between the lateral and medial collateral ligaments of the stifle?
A
The lateral collateral ligament is separated from lateral meniscus by the popliteal tendon and is only loosely attached with the joint capsule. The medial collateral ligament blends with the medial joint capsule and is closely associated with the meniscus.
11
Q
What are the attachment points of the lateral collateral ligament of the stifle?
A
Lateral epicondyle of the femur to the head of the fibula.
12
Q
Are the cruciate ligaments intra- or extra synovial?
A
Intra articular but extra synovial because they are covered in synovium
13
Q
Are the menisci comprised of hyaline or fibrocartilage?
A
Fibrocartilage
14
Q
What ligament attaches the medial meniscus to the joint capsule and medial collateral ligament?
A
Coronary ligament (lateral meniscus lacks this attachment).
15
Q
Is the medial or lateral meniscus more firmly attached to the tibia?
A
Medial meniscus
16
Q
Which meniscal ligament may be absent in dog?
A
Caudal meniscotibial ligament of the lateral meniscus
17
Q
Compressive forces applied to the meniscus from the femur are converted into what?
A
Hoop stress (compressive forces are converted to radial forces which are resisted by the tensile forces in the circumferentially arranged collagen fibers of the menisci)
18
Q
Why is the lateral meniscus less prone to damage as compared to the medial meniscus?
A
The attachment of the lateral meniscus to the femur (meniscofemoral ligament) and close relationship with the popliteal tendon couple the motion of the lateral meniscus to that of the femur.
19
Q
Label the ligament attachment points in the following diagram.
A
20
Q
What type of collagen is predominantly found in the menisci?
A
Type 1
21
Q
What are the three structural layers of the mensci?
A
Surface layer: randomly orientated collagen fibers to create frictionless surface.
Innermost third: collagen fibers predominantly in a radial pattern to resist compression.
Outer two thirds: circumferential pattern to act in tension
22
Q
What is the role of proteoglycans in the meniscal tissue?
A
To resist compressive loads (rate of load dependent function)
23
Q
Describe the blood supply to the meniscus
A
Blood supply originates from a small reflection of the vascular layer of the synovium
24
Q
What are the roles of the cranial cruciate ligament in relation to stifle motion?
A
Limits stifle hyperextension, internal rotation and tibial thrust. Also limits stifle varus (in flexion and extension) and valgus (in flexion only).
25
What is the normal stifle passive range of motion?
Between 120-140 degrees.
Flexion: 41 degrees.
Extension: 161 degrees.
26
What is the 'screw-home' mechanism of the stifle?
During flexion the lateral collateral ligament loosens and the lateral femoral condyle displaces caudally with internal rotation of the tibia. As the stifle extends the lateral collateral tightens reversing this action.
27
What are the two bands of the cranial cruciate ligament and how do they differ in function?
Craniomedial: taut in flexion and extension.
Caudolateral: taut in extension, lax in flexion.
28
What are the functions of the caudal cruciate ligament?
Limits caudal tibial translation and internal rotation. Aids in limiting hyperextension. Also limits valgus and varus angulation in flexion.
29
How much of the load to the menisci bear across the stifle joint?
40-70%
30
How much of the radial width of the meniscus needs to remain intact for the meniscus to act as an effective functional unit?
25%
31
What are the functions of the mensici?
1. Load bearing (lowers the stress of the articular cartilage of the femur and tibia).
2. Load distribution.
3. Shock absorption (via hoop stresses).
4. Joint stability (secondary role behind the cruciate ligaments)
32
What is meniscal release?
Complete transection of the medial meniscus at the meniscotibial ligament or through the midbody of the meniscus, with the goal of eliminating the wedge effect of the caudal horn of the medial meniscus during femorotibial subluxation.
33
What is the effect of meniscal release on stifle biomechanics?
Decrease in contact area and increase in magnitude of pressure on the medial compartment. No significant difference between mid-body and release of the meniscotibial ligament.
34
What are the effects of CCLR on stifle kinematics?
1. Increased flexion of the stifle.
2. Increased extension of the hip and tarsocrural joints.
3. Cranial tibial subluxation during the stance phase. Intact meniscus may serve as a return spring during swing phase of gait following unloading of the joint.
4. Decrease in peak vertical forces and impulses.
35
What structures act to neutralize cranial tibial translation in the normal stifle joint?
1. Passive restraints: cranial cruciate ligament, caudal pole of the meniscus.
2. Active restraints: caudal thigh muscles (gastrocnemius).
36
What model of stifle instability is shown?
37
What model of stifle instability is shown?
38
What are the main differences between the Slocum and Tepic models of stifle stability?
Slocum (active model) presumes the joint reaction force is parallel to the long axis of the tibia. Tepic presumes the joint reaction force is parallel to the patellar ligament.
39
How can avulsion of the cranial cruciate ligament be surgically repaired?
1. Placement of wire around the CCL and twisted through holes in the tibia.
2. Direct fixation with k-wires or lag screw (if large enough).
+/- epiphysiodesis.
40
What is a surgical treatment that can be used to reduce the tibial plateau during growth in a young animal?
Epiphysiodesis
41
What are the proposed etiologies of degeneration of the CCL?
1. Decreased mechanical properties of the cruciate ligament with ageing.
2. Neutering/sex.
3. Obesity and/or poor physical condition that affects the protective mechanisms of contraction of the caudal thigh muscles and relaxation of the quadriceps muscle groups during stifle loading.
4. Chondroid metaplasia, lack of collagen fiber maintenance and loss of fibroblasts in the ligament.
5. Breed variations (i.e. Rottweiler ligaments less biomechanically strong than Greyhounds).
6. Antibodies in the stifle joint (not specific for stifle disease).
42
Are female or male dogs more likely to suffer cruciate ligament rupture?
Female dogs. Neutered dogs also have a higher prevalence, although age of OHE does not seem to be related.
43
What is the rate of contralateral CCLR?
22-54%. Decreased risk of contralateral rupture with increased age.
44
How can 'puppy drawer' be differentiated from pathologic drawer?
Abrupt stop after 3-5 mm.
45
If there is a partial tear of the CCL with only rupture of the craniomedial portion, is drawer present?
Only in flexion, because the caudolateral band limits drawer in extension
46
What radiographic findings might indicate an increased risk of contralateral cruciate ligament rupture?
Joint effusion and osteophytosis of the contralateral stifle. Joint effusion associated with a 13 times increase risk of contralateral cruciate ligament rupture by 1 year after diagnosis.
47
What are some imaging techniques that can be used in the diagnosis of CCLR?
1. Radiographs.
2. Stifle joint arthroscopy.
3. MRI (evidence of bone bruise may be indicative, but not specific).
4. Ultrasound for evaluation of meniscal pathology (may be difficult to visualize the caudal poles).
48
What is the frequency of meniscal tears at the time of initial surgery for CCLR?
33.2% (range of 30-80% reported in the literature)
49
What are latent and postliminary meniscal tears?
Latent: Present at the time of surgery but not detected.
Postliminary: Occurring after surgery.
50
What is the most common pattern of tearing of the medial meniscus?
Longitudinal tear between the collagen fibers, this may propagate to perpendicular tearing if stresses continue (bucket handle tear). Page 1087 for more in-depth description.
Radial tearing (particularly of the axial free edge) are more common in the lateral meniscus, but their significance is unknown.
51
Are dogs with complete or partial cruciate rupture more likely to have meniscal tearing?
Complete (9.6 times more likely).
Overweight dogs may also be more likely.
52
What is the imaging diagnosis? What is the clinical significance?
Meniscal mineralization.
The clinical significance is unknown, although seems to be associated with osteoarthritis of the medial compartment of the stifle joint.
53
What is the sensitivity and specificity of a meniscal click for meniscal injury on physical examination?
50% and 90%, overall diagnostic accuracy of 80%
54
What are potential diagnostic methods for meniscal tear diagnosis?
CT arthrography, high field MRI (may be more accurate in large dogs), ultrasonography, arthroscopy, arthrotomy
55
Does arthroscopy or arthrotomy have a higher sensitivity and specificity for meniscal tear identification?
Arthroscopy with a probe (using a probe increased the performance of both arthroscopy and arthrotomy)
56
Describe the different types of meniscal tears
57
How can a horizontal meniscal tear be diagnosed?
MRI, or probing the edge of the meniscus.
58
What is the appearance of a degenerative meniscal tear?
Pale yellow, fibrillated surface, softer texture.
59
What device might help improve meniscal exposure and meniscectomy without articular cartilage damage?
Stifle distractor.
View of the medial meniscus can also be improved by applying external rotation and valgus to the limb.
60
What approaches to the stifle can be performed for meniscal assessment +/- meniscectomy?
1. Arthroscopy.
2. Craniomedial arthrotomy
3. Caudomedial arthrotomy
4. Caudomedial arthroscopy
The meniscus is assessed through a combination of observation and probing.
61
What is the ideal flexion angle of the stifle for examination of the meniscus?
110-130 degrees.
62
What are the types of meniscectomy based on extent of resection?
Hemimeniscectomy (or segmental), total meniscectomy, partial meniscectomy
63
What are the disadvantages of total meniscectomy?
Increased OA, greater contact stress, loss of stability.
Generally performed in injuries that involve both horns (rare) or in stifle joint luxation in which the ligamentous attachments of the meniscus are disrupted and cannot be repaired.
64
What are the two types of meniscal release?
Mid-body (central, can be performed in inside-to-outside or outside-to-inside fashion), or at the meniscotibial ligament (caudal)
65
What techniques of meniscal release are depicted in the image?
Midbody meniscal release with an inside-to-outside (A) or outside-to-inside technique (B).
66
What type of meniscal release is depicted?
67
What is the outcome of dogs treated with meniscectomy or meniscal release procedures?
Excellent short term outcomes, but long-term outcomes may be worsened with more aggressive meniscal procedures.
Maintaining as much of the peripheral meniscal rim as possible may aid in distributing loads within the stifle through preservation of hoop tension.
68
What do extra-articular stabilization techniques of the stifle rely on for stability?
Periarticular fibrosis.
69
What types of extraarticular repair of the stifle are available?
1. Lateral fabellotibial suture
a. Nylon leader line.
b. TightRope
c. SwiveLock
2. Fibular head transposition.
70
What should the proximal portion of a lateral fabellotibial suture ideally be anchored on?
The fibrous origin of the gastrocnemius muscle (just proximal to the fabella).
Passing the suture around the fabella may result in placement within the femorofabellar joint.
71
During tightening of the lateral fabellotibial suture how many degrees of flexion should the stifle joint be placed in?
100 degrees
72
What are the different methods of securing/tying the lateral fabellotibial suture?
Square knot, slip with with square knots, self locking knot with square knots, tensioning device with metal crimps.
73
Why is nylon leader line preferred for lateral fabellotibial suture over regular nylon line?
It has greater load to failure, increased stiffness, and recovers resting tension to a greater degree
74
Does securing nylon leader line with a metallic crimp or square knot in a lateral fabellotibial suture result in improved biomechanical characteristics?
Metallic crimp results in lower loop elongation, higher load to failure, greater stiffness, and greater initial loop tension.
75
Describe the isometric points of the canine stifle
Isometric means that two points would remain equidistant during stifle joint range of motion. Due to the complex motion of the femur in relation to the tibia there are no true isometric points, just quasi-isometric points (see image).
F2: most caudal aspect of femoral condyle at the distal pole of the fabella.
T3: caudal to the extensor groove of the tibia.
76
Aside from nylon leader line, what other techniques can be used for lateral fabellotibial suture?
1. TightRope system using bone tunnels and Fiberwire.
2. SwiveLock system using a knotless anchor system.
77
What are some potential complications associated with lateral fabellotibial suture?
Peroneal nerve deficits, tearing of gastrocnemius, SSI (4.2%), implant and incision related complications, post liminary meniscal tears (reported in 1.9% of cases - although 15.2% when meniscal release not performed).
78
What are risk factors for increased complications with lateral fabellotibial suture?
Increased weight, young age.
79
How does fibular head transposition eliminate cranial drawer?
Cranial and distal transposition of the fibular head alters the orientation of the lateral collateral ligament
80
Why has fibular head transposition fallen out of favour?
High rate of post-liminal meniscal injury (50%), failure to restore normal gait on force plate analysis, continued rotational and cranial translational instability, progression of osteoarthrosis. Fibular fracture and tearing of the lateral collateral ligament may also occur.
81
What are the different types of materials that can be used for intra-articular CCL reconstruction?
Autografts, allografts, xenografts (typically not used due to intense inflammatory reaction), synthetic materials (prostheses, scaffolds, augmentation devices)
82
How does incorporation of intraarticular tissues used in CCL reconstruction occur?
Inflammation and graft necrosis, revascularization and cell repopulation, and graft remodeling (ligamentization).
Process typically takes 20 weeks.
Prostheses are designed to permanently replace the CCL and thus must be able to withstand all functional loads of the joint.
83
What are the benefits of an allograft over an autograft for using in intraarticular reconstruction of CCLR?
1. Absence of a donor site.
2. Quicker surgical time.
3. Less post-operative discomfort.
Main concern with use of allografts is the potential for disease transmission. Availability is also an issue.
84
What is required for success of a intra-articular reconstruction device in the repair of CCL?
Ligamentization. The process whereby inflammation results in fibroblast reinfiltration along the collagen scaffold and secretion of new collagen.
85
What surgical techniques are used most commonly in humans for repair of CCLR?
Bone-patellar ligament-bone technique, or hamstring autograft technique.
86
What is the preferred method for autograft placement in the dog with CCLR repair?
Over-the-top technique. Where a patellar ligament or fascial graft is pulled through the joint and over the side of the lateral femoral condyle, to simulate the native CCL.
87
What is the under-and-over technique for placement of intra-articular grafts in dogs?
This is performed when using the lateral fascia lata and patellar ligament from the apex of the patella (rather than procuring patellar ligament with the bone attached). The graft is first passed under the intermeniscal ligament before being passed in an over-the-top technique.
88
How is a bone-ligament-bone graft secured to the femur and tibia when used for intra-articular CCL reconstruction in the dog?
Bone tunnel in the tibia with an interference screw. Over-the-top technique on the femur with use of a bone screw and washer.
89
What device is shown for use in intra-articular reconstruction of CCLR?
Synthetic silk grafts.
90
What are the different types of synthetic grafts that may be used for intra-articular CCL reconstruction?
1. Permanent replacement (prostheses). Prone to mechanical failure.
2. Scaffolds: allow and promote tissue ingrowth (LARS, silk scaffolds with cultured progenitor ligament cells).
3. Augmentation devices: designed to protect biologic grafts during the early healing period.
91
What are potential complications associated with autograft repair of CCLR in dogs?
Difficulties in procuring the patellar graft (fractured patellar, penetration of articular surface and OA), adequate stability and anchorage of the graft, persistent instability.
92
What osteotomy techniques are available for surgical repair of CCLR?
1. CCWO
2. TPLO
3. TPLO + CCWO
4. TTA
5. TTO
93
Using CCWO what is the target post-operative TPA?
4-6 degrees
94
What are advantages of CCWO compared to TPLO?
No requirement for specialized equipment, ability to address tibial angular deformity without loss of apposition or need for additional osteotomy, ability to address patella alta, can be performed in patients with open tibial physes.
95
What are disadvantages of CCWO compared to TPLO?
Variability in postoperative TPA, patella baja, limb shortening, stifle hyperextension.
96
What osteotomy procedure for correction of CCLR is depicted?
97
Which movements of the stifle does the TPLO not neutralize?
Internal rotation and hyperextension
98
What is the TPA that has been shown to eliminate thrust following TPLO?
6.5 degrees
99
What is considered the safe distance of tibial plateau rotation in relation to the tibial tuberosity in TPLO?
Rotation to the level of the patellar attachment on the tibial tuberosity is considered safe. If beyond this combination of TPLO and CCWO should be considered
100
How does positioning of the centre of a TPLO affect long axis shift?
Unless the TPLO is centered over the proximal tibial long axis point (intercondylar tubercles) the long axis will shift with rotation. This might impact the TPA achieved and consequent biomechanical outcomes.
101
What are the D1, D2 and D3 measurements that can be used during TPLO planning?
102
When might alteration of osteotomy position be required when performing a TPLO?
Narrow proximal tibia, excessive TPA or proximal tibial growth deformity, presence of a bone tunnel from a previous surgery, small tibial size but large body weight (i.e. Bulldogs).
103
Failure to use a jig during TPLO has been associated with an increased risk of what complications?
Inaccurate osteotomy angulation, fibular fracture, and fixation failure.
104
What is the preferred technique for correction of concurrent moderate vaglus/varus or torsional deformities of the tibia with CCLR?
TPLO with CCWO.
Mild deformities can be corrected using TPLO by creating an opening wedge through sliding the distal jig arm along the distal jig pin (valus/varus). Bending the jig pin in the frontal plane can correct mild torsional deformities. These corrections occur at the expense of apposition of the tibial osteotomy.
105
Within what range of post-operative TPA following TPLO were ground reaction forces equal?
0-14 degrees
106
What are some potential benefits of TPLO over lateral fabellotibial suture?
Faster return to function, lower OA development.
107
What is a potential source of hemorrhage during TPLO?
Cranial tibial artery.
108
How can tibial tuberosity fractures following TPLO be treated?
If minimally displaced can be treated conservatively. Displaced fractures require revision.
109
How much do bilateral single session TPLOs increase the risk of tibial tuberosity fracture?
By 8.5 - 9.6 fold
110
What is rock back?
Secondary loss of reduction following TPLO suspected secondary to motion at the osteotomy site. Risk might be reduced through the use of locking implants.
111
What are some proposed risk factors for developing patellar ligament thickening post TPLO?
Increased weight, TPA<6 degrees, cranially positioned osteotomy, partial CCLR, post-operative tibial tuberosity fracture.
Cranially positioned osteotomies reduce the lever arm for the quadriceps mechanism (defined as the distance between the intercondylar tubercles and the tibial tuberosity). This increases the force required on the patellar tendon to exert the same effect.
112
What are the suggested grades for patellar thickening post-op TPLO?
Grade 1: Normal ligament to twice thickness.
Grade 2: 6-11 mm in thickness
Grade 3: >12mm in thickness
Tendenosis is grade 2 thickening with lameness, pain on palpation of the ligament, and swelling.
113
What was associated with a 7 x increased risk of proximal tibial neoplasia when performing TPLO?
Use of cast (rather than wrought) TPLO plates. Suspected secondary to implant corrosion.
114
What is the definition of an excessive TPA?
>34 degrees when using a 24 saw blade, or rotation required past the attachment point of the patellar on the tibial tuberosity
115
What combination of procedures can be used to address excessive TPA?
TPLO and CCWO (can also address varus/valgus, translational, and torsional deformities)
116
Describe the pre-operative planning process for combined TPLO and CCWO.
117
Describe the surgical procedure for combined TPLO + CCWO.
118
What combination of surgeries is depicted?
TPLO + CCWO
119
How can TPLO + various closing wedge options be combined to correct numerous angular limb deformities of the tibia?
120
What is the ideal angle of the patellar tendon following TTA?
90 degrees to the common tangent created by the opposing surfaces of the femur and tibia.
Ideally an angle of 90 degrees or less should be maintained throughout weight-bearing (i.e. from the time of first foot-strike).
121
During pre-operative planning for TTA, what needs to be ensured for positioning of radiographs?
That the stifle is extended (approximately 135 degrees), and the tibial is not in cranial translation.
122
What are some modifications of the TTA that have eliminated the use of the plate?
Modified maquet procedure, TTA rapid, TTA-2.
The biggest additional concern of these procedures over regular TTA is the fracture of the tibial bridge at the distal end of the osteotomy, as well as fractures of the diaphysis of the tibia.
123
What are the most commonly reported complications following TTA?
Postliminary meniscal tears, tibial tuberosity fractures, infection, medial patellar luxation, fracture of the tibia.
124
What are potential surgical technical errors when performing TTA?
1. Osteotomy fragment too small
2. Osteotomy cut too low (osteotomy should be at least 1cm proximal to the distal screw insertions to prevent stress riser at this level).
3. Not allowing proximal shift of the tuberosity with advancement resulting distal shifting the patella.
4. Malalignment of the tuberosity in the frontal plane resulting in MPL.
5. Orientating the plate so that the forks are too far away from the leading edge of the bone or the distal end lies caudal to the tibial shaft.
125
What are some potential contraindications for use of TTA in CCLR?
1. Low patellar attachment point. This reduces the size of implant that can be used, while buttress support of the cage is lost.
2. Excessive TPA (>30 degrees?). TTA doesn't address concurrent hyperextension of the joint seen with eTPA, and also degree of advancement required may be beyond what is feasible.
3. Concurrent angular or torsional limb deformity correction (can be used for concurrent TTT in MPL)
4. Large size (not necessarily contraindicated but may be limited by maximum size of implants (15mm cage). The cage can be advanced distally within the osteotomy to increase advancement but this increases the risk of tuberosity fracture.
126
What is the goal of the TTO?
To reduce the patellar tendon angle to 90 degrees when the stifle is in a weight bearing position (similar to the TTA).
127
What surgical technique is shown?
Tibial tuberosity osteotomy.
128
What is the most common intra-operative complication with TTO?
Fracture of the tibial tuberosity requiring tension band fixation
129
What is the most common post-operative complication with TTO?
Fracture of the tibial crest, more likely if a cortical defect is observed at the distal tuberosity on post-op rads, or in dogs older than 6 years, and in joints with larger osteotomy angles.
130
What are some proposed advantages/disadvantages of TTO?
Advantages: minimal change to the orientation of the tibiofemoral articulating surfaces, a relatively small osteotomy gap caudal to the tibial tuberosity, no loss of limb length, and proposed low technical difficulty when the appropriate instrumentation is used.
Disadvantages: variability of the postoperative patellar tendon-to-tibial plateau angle when the recommended calculations are used and additional fixation with intraoperative fractures of partial osteotomies.
131
How is the wedge angle for a TTA calculated?
WA = 0.6 x CA + 7.3 (CA = angle of correction of the patellar required to achieve 90 degrees). If WA is greater than the TPA should use TPA -5 degrees or TPA -12 degrees
132
What is tibial sag?
The loss of the prominence of the tibial tuberosity in instances of caudal cruciate ligament rupture.
During drawer testing an abrupt stop is also typically felt (as compared to CCLR when the endpoint is less distinct).
133
What are the treatment options for caudal cruciate ligament rupture?
1. Conservative management for 3-6 weeks (may be reasonable in small breed dogs and cats).
2. Surgical intervention (in instances of failed medical management or large-breed, active working dogs). Joint exploration to inspect the menisci, the cranial cruciate ligament, and the articular surfaces, followed by stabilization.
134
In instances of caudal cruciate ligament avulsion from the femoral attachment point, what treatment options are available?
Lateral stifle approach if avulsed from the femoral aspect. Caudomedial approach if avulsed from the tibial attachment.
135
What surgical treatments are described for midsubstance tears of the caudal cruciate ligament?
1. Medial and lateral joint imbrication with patellar tibial (medial) and fibula (lateral) sutures +/- fascial lata strip.
2. Desmodesis of the medial collateral ligament or tenodesis of the long digital extensor or popliteal tendon.
136
What muscles make up the quadriceps extensor mechanism?
Rectus femoris (origin on the ilium cranial to the acetabulum), vastus lateralis, medialis, intermedius (origins on the proximal femur)
137
What skeletal abnormalities are associated with medial patellar luxation?
Coxa vara, diminished angle of anteversion, distal femoral varus and genu varum, shallow trochlear groove, hypoplastic medial femoral condyle, medial displacement of the tibial tuberosity, proximal tibial varus, internal torsion of the foot despite external torsion of the distal tibia.
138
Describe the grades of MPL
139
Is MPL considered congenital?
No, it is considered developmental although the underlying abnormalities responsible for the condition are likely congenital (affected animals should not be bred).
140
What is the Q-angle?
The angle from the origin of the rectus femoris muscle, to the deepest point of the trochlear groove, to the attachment of the patellar ligament on the tibia (normal 10.5 degrees, increased with MPL)
141
How common is bilateral MPL?
50-65% of cases
142
How frequently is concurrent CCLR present in older, middle aged dogs with MPL?
15-20%. Unsure whether this represents a complication of MPL or simply a manifestation of CCL disease.
143
When should surgery be considered for MPL?
Grade 3 and 4.
Grade 2 luxation, if degree of lameness is considered significant:
1) lameness lasting 2-3 weeks or longer.
2) three or more episodes of lameness that occur in a short time-frame (e.g. over 1 month).
144
In cases of severe MPL in juvenile patients, what surgical approach should be considered?
Staged approach where:
1) soft tissue reconstruction and trochlear chondroplasty is performed initially, sparing the physes.
2) bone reconstruction techniques are employed if required once skeletal maturity is reached.
145
How can extensor realignment be achieved in cases of MPL?
TTT, derotation of the tibia, correction of femoral varus
146
What are some trochleoplasty techniques?
Trochlear sucloplasty, chrondroplasty, wedge recession, block recession
147
What can be performed during trochlear sulcoplasty to expedite formation of fibrocartilage?
Autogenous periosteal graft (fills with fibrocartilage in 4 weeks compared to 40 weeks).
148
What age of patient can trochlear chondroplasty be performed in?
Less than 6 months. Involves separation of the cartilage from the underlying subchondral bone.
149
How deep should a trochleoplasty be in relation to the patellar?
Should accommodate 50% of the depth of the patella
150
What are the two techniques for wedge trochleoplasty?
Three or four osteotomy technique.
Care must be taken to ensure the recipient bed and osteochondral wedge have the same apex angle to achieve stability. If the newly formed sulcus is distal to the patella in full extension the patella may need to be translocated distally during TTT.
151
What is the axial angulation of the initial trochlear osteotomies in a block recession trochleoplasty?
10 degrees
152
What are the proposed benefits of trochlear block compared to wedge recession?
Increased proximal patellar depth, increased patellar articular contact with the recessed proximal trochlea, recession of a larger percentage of the trochlear surface area, and greater resistance to patellar luxation in an extended position
153
How wide should a TTT be?
One-half the depth of the tibial crest (from the patellar attachment to the cranial articular margin of the tibial plateau).
154
In what direction are k-wires angled during placement for TTT?
In a caudomedial direction to avoid entry into the fossa of the cranial tibial muscle. The fibula head acts as a useful landmark (aiming just distal ensures that the joint surface is not penetrated).
155
When is repair of patellar luxation appropriate with just soft tissue reconstruction techniques?
Traumatic patellar luxation or first stage of MPL repair in juvenile patients.
156
How is release of the quadriceps mechanism performed during MPL repair?
Incision in the fascia between the caudal sartorius and vastus medialis (medially) and the biceps femoris and vastus lateralis (laterally). Attachments to the femur are then digitally debrided.
This may be required in cases of grade 3 or 4 luxation.
157
When might antirotational techniques be used for the correction of MPL?
Best used for immature animals where correction of tibial rotation may help to mitigate deformities as the animal grows (lateral fabellotibial suture, fibular head transposition).
In mature animals they are considered temporary and are unlikely to result in resolution unless combined with other techniques to address the underlying bony abnormalities.
158
Are male or female small breed dogs more likely to be affected by MPL?
Female
159
Are males or female large breed dogs more likely to be affected by MPL?
Male
160
Is patella alta or patella baja associated with the development of MPL in large breed dogs?
Patella alta.
161
What is the impact of concurrent distal femoral varus and compensatory proximal tibial valgus on correction of MPL?
Will require correction of both angular limb deformities to ensure appropriate correction of the MPL.
162
How can the double condyle sign be used to interpret for femoral angular limb deformities?
One femoral condyle more distal than the other indicates angular (varus/valgus) deformity, one femoral condyle more cranial than the other indicates torsional deformity
163
What are normal aLDFA and femoral version angles in a dog?
aLDFA range from 94-98 degrees, anteversion angles of 27 degrees.
Increased aLDFA common in large breed dogs with MPL (femoral varus).
164
When is surgical correction of femoral torsion as part of MPL considered?
If anteversion angle is <27 degrees.
165
What are surgical options for correction of distal femoral varus with MPL?
Lateral closing wedge, medial opening wedge, radial osteotomy.
Detorsional osteotomies can be performed to correct concurrent femoral torsion.
166
What are some surgical options for concurrent treatment of CCLR and MPL?
1. Lateral fabellotibial suture and TTT.
2. TPLO with CCWO or simple osteotomy with lateralization of the TTT. Can also correct tibial torsion concurrently if required.
3. TPLO with TTT
4. CWO and TTT.
5. TTA with transposition of the TT.
167
What are potential complications associated with MPL repair?
Delayed union or fixation failure at osteotomy sites, reluxation of the patella, infection, OA.
Prognosis is worse with higher grade luxation. Frequency of major complications is higher in dog weighing >20kg.
Patients treated with both TTT and trochleoplasty techniques had a lower risk of patellar reluxation and major complications.
168
Is lateral patellar luxation seen more commonly in large or small breed dogs?
Large breed dogs
169
What skeletal abnormalities are responsible for lateral patellar luxation?
Coxa valga, increased angle of anteversion (femoral torsion angle), genu valgum, distal femoral valgus, lateral condylar hypoplasia, diminished growth of the lateral trochlear ridge.
170
Is bilateral disease common in dogs with lateral patella luxation?
Yes. Affected animals typically show signs by 5-6 months of age.
171
What imaging is recommended in the work-up of patients with lateral patella luxation?
CT, due to the high prevalence of associated skeletal deformities.
Care should also be taken to assess for joint laxity secondary to stretching of the medial collateral due to chronic external rotation of the stifle joint.
172
What are the surgical treatment options for distal femoral valgus associated with LPL?
1. Lateral opening wedge.
2. Medial closing wedge
3. Radial osteotomy
+/- detorsional osteotomy if required.
The medial closing wedge with laterally applied plate fixation is preferred.
173
What structure primarily limits external rotation in the flexed stifle?
Medial collateral ligament
174
Which collateral ligament of the stifle is more frequently damaged?
Medial
175
What is a deranged stifle?
Stifle joint in which multiple ligaments, and often the menisci, are damaged.
176
What are the degrees of ligament injury?
Grade 1: minor overstretching.
Grade 2: tearing of some fibers.
Grade 3: complete tearing or avulsion.
3rd degree and some 2nd degree injuries warrant surgical treatment.
177
What does a positive valgus or varus stress test of the stifle indicate?
Valgus: if mild degree of instability likely isolated rupture of the medial collateral. If marked instability likely rupture of both the collateral and the cruciates.
Varus: if mild degree of instability likely isolated rupture of the lateral collateral. If marked instability likely rupture of both the collateral and the cruciates.
Marked external rotational instability of the stifle in flexion is indicative of medial collateral ligament rupture.
178
What might theoretically become entrapped in a stifle luxation causing compromise to the distal limb?
The popliteal artery or peroneal nerve
179
What order should repair of stabilizing structures of the stifle be performed in when treating deranged stifle?
Menisci, then collateral ligaments, then cruciates (can use transarticular pin to maintain standing angle [140 degrees of flexion] throughout repair)
180
What surgical techniques are available for repair of ruptured stifle collateral ligaments (individually or as part of deranged stifle)?
181
What techniques can be used to augment ligamentous repairs in the treatment of a deranged stifle?
Transarticular pin (small dogs and cats) or transarticular ESF (hinged or rigid)
182
What are the major complications associated with surgical repair of deranged stifles?
Arthrofibrosis and recurrent joint instability.
Despite this, surprisingly good outcomes can be achieved although some loss of range-of-motion (30-40 degrees of flexion) is expected.
183
What are the clinical signs of patella fracture or ligament rupture?
Involuntary stifle flexion during weight bearing, swelling, patella alta.
184
What are options for patellar fracture repair?
Small apical and basilar fractures: conservative management or excision
Non- or minimally displaced transverse mid-body fractures: circumferential wiring, or pin and TBW.
Displaced mid-body fractures: pin and TBW.
Comminuted: reconstruction with k-wires, pin and TBW +/- circumferential wiring and tension band wire.
Tenuous repairs can be protected using a transarticular ESF, patellar tibial suture, patellar ligament plating.
185
Describe the repair of a ruptured patellar ligament
Patella tibial suture is used to appose the ruptured ends, which are repaired using a locking-loop suture.
Augmentation of the repair can be achieved using fascia lata grafts.
The repair can then be protected using a transarticular splint, transarticular ESF, or patellar ligament plating.
186
What are the complications associated with patellar fracture repair?
Fixation failure, nonunion, fracture of the patella at the site of the implants. Prognosis varies from poor to good.
187
What is the prognosis for patellar ligament rupture?
Fair to good, although reduced stifle ROM may be seen.
188
What is the most common location for OCD in the stifle?
Medial aspect of the lateral femoral condyle (96%).
189
Which dogs are most frequently affected by OCD lesions of the stifle?
Large breed, young, male dogs
190
Where are OCD lesions most commonly seen in the dog (including the stifle)?
In order of decreasing frequency: shoulder, elbow, tarsocrural joint, stifle
191
What are the treatment options for stifle OCD?
1. Conservative management (only if incidental).
2. Surgical debridement (curettage, forage and micropicking).
3. Autogenous osteochondral grafting (osteochondral autograft transfer system - OATS)
192
What is the function of the long digital extensor?
Extension of digits II through V and flexion of the tarsocrural joint (no effect on stifle function)
193
In which patients does avulsion of the long digital extensor tendon most frequently occur?
Young large breed dogs after low grade trauma
194
What clinical sign is associated with avulsion of the long digital extensor tendon?
Ability to flex the stifle, extend the tarsus and fully flex the digits simultaneously.
195
What is the treatment for avulsion of the long digital extensor tendon?
1. Reattachment in acute cases with a lag screw and spiked washer.
2. In chronic cases resection of proliferative tissue and suturing of the tendon to the proximal soft tissues of the tibia.
Prognosis is good.
196
Luxation of the tendon of the long digital extensor typically occurs following what?
MPL or as a complication of TPLO (rarely occurs spontaneously).
Luxation typically occurs caudally and may be associated with no to marked lameness. Can confirm via palpation (may also hear an audible click).
197
What is the treatment for luxation of the tendon of origin of the long digital extensor muscle?
Bone tunnels cranial and caudal to the extensor groove with placement of a mattress suture to contain the tendon +/- deepening of the extensor groove.
198
What is the function of the gastrocnemius muscle?
Flexion of the stifle and extension of the tarsocrural joint. The distal tendon is the major component of the common calcaneal tendon.
199
What are the clinical signs associated with avulsion of the proximal origin of the gastrocnemius muscle?
Plantigrade stance, distal displacement of one or both fabellae.
200
How can avulsion of the origin of the gastrocnemius muscle be repaired?
Directly sutured around the fabella to the back of the femur if appropriate soft tissues available. Otherwise, suture can be passed around fabella and secured to the femur using bone tunnels or bone anchors.
201
What is the ideal stifle arthrodesis angle in the dog and cat?
Dog: 135-140 degrees
Cat: 120-125 degrees
202
What is the function of patients following stifle arthrodesis?
Limb function is markedly affected with circumduction of the limb and occasional knuckling.
203
How long should the bone plate be when used for stifle arthrodesis?
Should span 60-70% of both bones. Is applied to the cranial aspect.
204
What are complications associated with stifle arthrodesis?
Delayed fusion, failure of fusion, infection, fracture, OA of the hip or tarsus due to biomechanical alterations.
205
According to Gleason 2020 in Vet Surg, was the presence of a meniscal click pre-operatively associated with meniscal pathology?
Yes. Pre-operative meniscal click was 38% sensitive and 95% specific for meniscal tear morphologies (only associated with the presence of a bucket handle tear, not other morphologies).
206
According to Geier 2021 in Vet Surg, did the risk of patellar fracture increase or decrease with reductions in post-operative TPA following TPLO surgery?
Risk increased with a reduction in TPA (odds of fracture increased by 21.7% for every 1 degree decrease in TPA). Care should be taken to avoid excessive rotation during TPLO.
207
In a study by Jeong 2021 in Vet Surg, was the rate of post-liminal meniscal injury higher in TTA or TPLO operated stifles?
TTA (11/15 dogs compared to 1/15 TPLO dogs). Meniscal total gross pathology and articular cartilage damage also higher with TTA.
208
According to Katz 2021 in Vet Surg, what arthroscopic finding is predictive of the presence of a meniscal tear?
The absence of meniscal flounce
209
According to McDougall 2021 in Vet Surg, what were two risk factors for implant removal due to surgical site infection post-TPLO?
Male dogs, German Shepherds
210
In a study by Whitney 2021 in Vet Surg which of the following constructs used to secure a CBLO was the strongest?
1) Single pin
2) Countersunk compression screw
3) TBW
4) Compression screw and TBW
Compression screw and TBW
211
In a review by L Alvarez 2022 in Vet Surg, what two veterinary rehabilitation interventions can be recommended following surgery for CCLR?
Therapeutic exercise and cold compression.
212
In a study by Clough 2022 in Vet Surg, did CBLO in combination with a TTT decrease the biomechanical stability of the construct?
No, performing a TTT in combination with a CBLO did not weaken the construct failure to load.
213
According to Peycke 2022 in Vet Surg, was use of a CBLO appropriate for CCLR repair in a juvenile patient?
Yes, however complications included valgus deformity secondary to growth plate disruption in 2 dogs and recurvatum due to TP over-rotation in 1 dog.
214
In a study by Brincin 2023 in Vet Surg, the absence of which 3 factors resulted in a low likelihood of changing post-operative recommendations regardless of radiographic findings at routine post-operative MPL recheck?
Lameness, use of analgesics, history of unplanned visits prior to routine recheck.
215
What was the major and minor complication rate for a modified tibial tuberosity transposition technique as described by Cortina 2023 in Vet Surg?
Major complication rate of 4.3%, minor complication rate of 15%
216
According to Longo 2023 in Vet Surg, what angle can be used for trochleoplasty decision making in dogs with medial patellar luxation?
Femoral trochlea groove angle (<134 in small breed dogs, and <128 in medium breed dogs) can be considered a cutoff for trochleoplasty
217
According to Nagahiro 2023 in Vet Surg, how did the quadriceps to femur length differ in patients with MPL?
Patients with MPL had a shorter quadriceps muscle as compared to overall femur length (worse for grade IV luxations)
218
In a study by Banks 2024 in Vet Surg, when performing a modified CCWO for CCLR what may result in under reduction of the TPA?
Distalization of the osteotomy.
219
In a study by Knudson 2024 in Vet Surg, what was the reported sensitivity and specificity of CT arthrography for identification of a meniscal lesion?
Sensitivity 0.62-1.00, specificity 0.70-0.96.
220
In a study by Sanders 2024 in Vet Surg, what factors were associated with an increased risk of SSI for TPLO? Was there any benefit for antiseptic lavage prior to closure?
Risk factors included increasing bodyweight and bilateral TPLO. Post-operative antimicrobials had a protective effect.
No benefit to lavage prior to closure was observed.
221
In a study by Story 2024 in Vet Surg comparing the following tibial osteotomy techniques for correction of excessive tibial plateau angle, which of the techniques resulted in the greatest TPA correction accuracy, greatest tibial shortening, and greatest mechanical axis shift?
1) CBLO + CCWO
2) TPLO + CCWO
3) mCCWO
4) PTNWO (proximal tibial neutral wedge osteotomy)
Greatest accuracy: CBLO and PTNWO groups.
Greatest tibial shortening: TPLO group.
Greatest mechanical axis shift: CBLO group.
222
In a study by Stoneburner 2022 in JAVMA, what percentage of cats were reportedly clinically normal within 3 months of medical management for CCLR? Long term, what percentage of owners thought that their cats had a good to excellent outcome?
83% of cats were clinically normal within 3 months.
94% of owners reported a good to excellent outcome.
223
What was the technique described by Ericksen 2023 in JAVMA for correction of patellar alta and patella luxation in dogs >20kg? What was the overall complication rate?
Dome trochleoplasty.
Overall complication rate was 50%, predominantly pin migration and recurrent luxation of the patella.
224
In a study by MacCormick 2023 in JAVMA, did the use of a jumbo plate when performing TPLOs in patients over 50 kg result successfully stabilize TPA? What was the overall complication rate?
No - a statistically significant increase in TPA was observed over the convalescent period.
High rate of complications (46%).
225
In a study by Pacheco 2023 in JAVMA, what novel DPOI (distance between the points of CCL origin and insertion) ratio was indicative of cruciate rupture?
Greater than 1.18. DPOI ratio defined as difference between DPOI under tibial compression and conventional radiographs.
226
In a study by Hamilton 2020 in JSAP, what percentage of dogs with occult grade II medial patellar luxation ultimately developed chronic lameness or required surgery?
50%
227
In a study by Colthurst 2022 in JSAP, what was the rate of meniscal injury at the time of surgery in small and large breed dogs with CCLR? What increased the risk of meniscal injury?
37-38% rate of meniscal injury.
The rate of meniscal injury was greater in instances of increased cruciate ligament insufficiency.
228
For patients undergoing either fabellotibial suture, Tightrope or Ligafiba Isotoggle procedure for CCLR in a study by Franklin 2023 in JSAP, what 2 factors increased the risk of post-operative complications? Which procedure was associated with the lowest risk of failure?
Decreased age and increasing body weight (dogs <1 year of age and >15kg had the highest rate of complications).
Fabellotibial suture had the lowest rate of complications (28%, compared to the isometric bone tunnel techniques with a complication rate of 59%).
229
What is FiberWire composed of?
Ultra high weight molecular polyethyelene core suture
230
In a study by Schuster 2023 in JSAP, was there an increase in physical activity variables or a decrease in sedentary behaviour in dogs undergoing extracapsular stabilization of CCLR?
No - there was no change in physical activity or sedentary behaviour post-operative (although significant improvements in lameness scores, pain score and quality of life were observed).
231
In a study by Volz 2024 in JSAP, what was the effect of intra-articular platelet rich plasma or hyaluronic acid on limb function following TPLO?
No effect was observed.
232
In a study by Cappelle 2019 in VCOT, was there any difference in the short term complication between performing single session or staged bilateral TPLOs with locking implants?
No difference was observed. Increasing age was the only significant risk factor for major complications.
Compare to study by Peress 2021 in VCOT which found a complication rate of 48% for single session and 20% for the staged group (10% v. 4% major complication rate).
233
In a study by Livet 2019 in VCOT, what was the difference in outcome between dogs having a TPLO and TTA rapid procedure for CCLR?
No difference in outcome at 6-months. TTA rapid dogs seemed to have a faster immediate post-operative recovery.
234
In a study by McGregor 2019 in VCOT, was use of a SOP TPLO plate associated with improved or worsened outcomes over traditional TPLO plates for CCLR in dogs? What factors were associated with improved osteotomy union?
Slightly worse outcomes than traditionally reported (25-50% osteotomy union score at 6-8 weeks), and major complications in 7%.
Retention of the antirotational pin, and less change in post-operative TPA were associated with improved osteotomy union.
235
In a study by Puerta 2019 in VCOT, what increased the risk for tibial tuberosity fracture following TTO for CCLR in dogs?
Decreased cortical hinge width or decreased cortical hinge width to tibial width ratio.
Interestingly, all post-operative tibial tuberosity fractures were able to be managed conservatively (25/113 stifles).
236
In a study by Rossanese 2019 in VCOT, what two factors were associated with an increased risk of complications following MPL repair in dogs <20kg?
Maintenance of the distal cortical attachment of the TTT reduced implant related complications. Adding a medial release to the MPL repair increased the rate of reluxation.
Type of TTT (1 v. 2 pins +/- TBW) or trochleoplasty (block, wedge) had no impact on complications.
237
Based on a study by Allberg 2020 in VCOT, what does the following image depict?
An angular index to assess abnormal proximodistal patellar positioning (normal index reference is 42 - 56).
238
In a study by Amimoto 2020 in VCOT, at how many months post-operative was the symmetry index normalized in small breed dogs undergoing force plate analysis following TPLO?
2 months
239
In a study by Brioschi 2020 in VCOT, did block recession trochleoplasty in a cadaveric cat model result in increased contact between the patella and femoral trochlea?
No - the patella rides on the trochlear ridges and loses contact with the trochlear sulcus. Block trochleoplasty should be combined with partial parasagittal patellectomy as this increases contact (mean reduction of 40% of patella width).
240
In a study by Cox 2020 in VCOT, what two factors were associated with an increased risk of SSI in dogs undergoing fabellotibial suture for CCLR? What was the overall SSI rate?
Increasing body weight and induction with propofol were associated with increased risk of SSI.
Overall SSI rate was 17%. Patients suffering from SSI had a worse lameness at 6-week and final follow-up.
241
In a study by Fox 2020 in VCOT what was the average TPA in dogs with CCLR? What four breeds had an increased TPA compared to average? What four breeds had a decreased TPA?
The average TPA was 29 degrees.
Bichon frise, Yorkies, Doberman pinschers, and Westies had increased TPAs.
Rottweilers, Labradors, German shepherds, and Cane corsos had decreased TPAs.
242
What is the modified maquet procedure?
The modified Maquet procedure (MMP) is an adaptation of the TTA technique and uses a titanium foam wedge for cranialization of the tibial tuberosity instead of a cage.
243
In a study by Knebel 2020 in VCOT was there a significant difference observed in outcomes between the modified maquet and TPLO when used for CCLR?
No - there were no significant differences. Although at 3 months significantly more patients with TPLO had peak vertical forces within the reference range of healthy dogs, there was no difference between groups by 6 months.
244
In a study by Nagahiro 2020 in VCOT, what technique was used to reconstruct the femoropatellar joint in dogs with MPL grade 4 in instances of shortened quadriceps muscle length relative to femoral length?
Segmental femoral ostectomy (average size of resected fragment 14% of pre-operative femoral length).
245
In a study by Ocal 2020 in VCOT, what were the determined reference intervals for small, medium, large and giant breed dogs for the Insall-Salvati index? What clinical condition does a decrease in the Insall-Salvati index indicate?
IS index is measured as patellar ligament length over patellar length. Alternatively cranial patellar ligament length over patellar length can be used due to variations in identification of the caudal attachment point (see image).
Small breed: 1.04-2.16
Medium breed: 1.19-2.27
Large breed: 1.40-2.24
Giant breed: 1.71-2.23
Dogs with values exceeding these intervals have patella alta, values less than these intervals signify patella baja.
246
In a study by Shimada 2020 in VCOT, what effect did TPLO have on internal-external rotation of stifle joints?
TPLO (even with the cruciate intact) increased internal-external rotation as compared to no-TPLO. This suggests that TPLO might influence tension on the collaterals and consequently generate stifle joint laxity.
247
In a study by Terhaar 2020 in VCOT, what 2 factors placed labrador retrievers at increased risk of cruciate rupture?
Yellow coat and failure to maintain optimal BCS.
Habitual activity, neuter status and body weight did not affect the incidence.
248
In patients with proximal tibial valgus and CCLR what technique was described by Vezzoni 2020 in VCOT to address both issues simultaneously?
Modified TPLO with double cut and medial crescentic closing wedge osteotomy (TPLO/MCCWO)
249
According to Zide 2020 in VCOT, which of the following construct(s) was strongest for repair of tibial tuberosity transposition?
1) Horizontal pins
2) Vertical pins
3) HP and TBW
4) VP and TBW
No difference in strength between horizontal and vertical pins. Addition of TBW led to significantly increased strength.
250
In a study by Agnello 2021 in VCOT, what was the location of the highest modified outerbridge cartilage scores of the stifle in dogs with CCLR? Did the presence of a meniscal tear have an association with cartilage severity scores or synovitis?
Highest modified outerbridge scores (see image) were associated with the proximal femoral trochlear groove.
There was no association between medial meniscal injury and cartilage severity scores or synovitis. Higher synovitis scores, however, were significantly associated with cartilage severity scores.
251
What technique was described by Blackford-Winders 2021 in VCOT as an alternative to block trochleoplasty for the treatment of MPL?
Semi-cylindrical recession trochleoplasty
252
In a study by Hackett 2021 in VCOT, what was the difference in outcome for small dogs (<12 kg) undergoing miniature tibial tuberosity transposition and advancement (mTTTA) and extracapsular suture and tibial tuberosity transposition (ECS + TTT) for concurrent CCLR and MPL?
No difference in outcome when comparing healing and lameness scores. mTTTA may be feasible in small dogs.
253
In a study by Laube 2021 in VCOT, what were 5 risk factors for development of bilateral meniscal tears in dogs with CCLR?
Contralateral meniscal tear, increasing age, decreased body weight, breed (Rottweilers at increased risk), complete CCLR.
254
In a study by Tanegashima 2021 in VCOT, what was the attachment point of the craniolateral and caudomedial bands of the caudal cruciate ligament on the femur? During stifle ROM what was the movement of the two bands?
The craniolateral band attached to the intercondylar fossa of the femur, and the caudomedial band attached to the medial surface of the medial condyle.
During stifle range of motion the two bands twist externally.
255
In a study by Verpaalen 2021 in VCOT, which of the following construct(s) for repair of tibial tuberosity avulsion fracture afforded the greatest stiffness and load in a canine cadaveric model?
1) K-wires alone
2) Pin and TBW
3) Hybrid external skeletal fixator
Pin and TBW and hybrid ESF had similar biomechanical properties. K-wires alone were weaker.
256
In a study by Agnello 2022 in VCOT, in what percentage of stifles with CCLR was tearing of the caudal cruciate ligament detected? What type of tear was most common?
94% of stifles had caudal cruciate ligament tearing, with longitudinal tearing the most common (76%).
Severity of joint pouch synovitis was positively correlated with the degree of caudal cruciate ligament damage.
257
In a study by Arun 2022 in VCOT, what two factors increased the likelihood of requiring non-elective explant in dogs undergoing tibial tuberosity avulsion fracture repair?
Neutered dogs (19 x more likely), and increasing pin size (every 0.25mm increase made it 2.5 times more likely to require explant).
Implant migration and seroma formation were the most common reasons to require explant.
Use of a tension band also reduced the risk of requiring explant in the univariable model.
258
In a study by Cieciora 2022 in VCOT, what was the effect of osteotomy rotation during TPLO on the cross sectional area of the cranial tibial artery? Was a low or high cut theorized to increase the risk of laceration of the main cranial tibial artery or craniolateral branches?
A decrease in cross sectional area of 81% was observed with osteotomy rotation.
A high cut may theoretically have a higher chance of lacerating the main cranial tibial artery or craniolateral branches.
259
What technique was described by Cinti 2022 in VCOT for repair of OCD of the lateral femoral condyle?
The COR osteochondral autograft transfer system.
Grafts were obtained from the abaxial lateral femoral trochlear and OCD lesions repaired either in a single graft or mosaicplasty technique.
260
In a study by Eskelinen 2022 in VCOT, which of the following construct(s) was associated with the greatest load to failure when used for tibial tuberosity transposition fixation in a cadaveric study?
1) Pin and TBW
2) Plate, pin and TBW
3) Plate and pin
Either combination of plate and pin with or without TBW resulted in greater loads to failure as compared to pin and TBW alone.
261
What angle measured by Sasaki 2022 in VCOT was increased in dogs with grade III and IV MPL?
Trochlear sulcus angle. No increase was observed in dogs with grade I or II luxation.
262
In a study by Schmutterer 2022 in VCOT, what was the effect of TPLO on meniscal contact force?
Contact force on both menisci were reduced after TPLO with post-op TPA of 6 or 1 degree (although 1 degree resulted in greater reduction).
263
In a study by Carey Beer 2023 in VCOT, what skeletal abnormalities were observed in cats with medial patellar luxation?
Distal femoral valgus (decreased aLDFA), diminished angle of anteversion, tibial torsion, tibial tuberosity displacement, and decreased trochlear depth:patellar thickness ratio.
264
In a study by Dumitru 2023 in VCOT, what technique was used to correct patellar to trochlear groove mismatch in dogs undergoing trochleoplasty for MPL?
Partial parasagittal patellectomy.
Outcome was considered good to excellent in all cases.
265
Is patellar baja or alta associated with lateral patellar luxation?
Patellar baja has been associated with lateral patellar luxation. Alta with medial luxation.
Patellar baja can be theoretically created by TTA or similar procedures (TTA rapid, modified maquet). However a study by Giansetto 2023 in VCOT found no predisposition of patients to patellar luxation following the modified maquet procedure.
266
In a study by Hawbecker 2023 in VCOT, did K-wire insertion at 0 degrees or 30 degrees during experimental fixation of canine tibial tuberosity osteotomy result in greater yield, peak and failure forces?
K-wire insertion at 0 degrees resulted in a ~1.5 x increase in yield, peak and failure forces.
267
What implant system as described by Onis 2023 in VCOT is depicted?
The rapid luxation plating system (RLPS) used for tibial tuberosity transposition.
Use in this retrospective study was associated with 35% minor complication rate, 8% major. The major complication observed was reluxation. No implant related or TTT avulsion was observed.
268
Which of the following surgical methods for correction of excessive tibial plateau angle are shown (from a study by Worden 2023 in VCOT).
The TPLO/CCWO was found to have the least effect on tibial morphology, and the coCBLO the largest.
269
In a study by Alvarez 2024 in VCOT, which of the following methods to achieve interfragmentary compression during TPLO resulted in the most even distribution of high forces?
1) Kern forceps clamping the distal plate to the caudal tibia (K).
2) Use of the TPLO plate compression hole (P).
3) Pointed forceps clamping osteotomized fragment to the tibial crest (F).
4) K+P
5) K+F
6) F+P
7) K+P+F
Use of the TPLO plate compression hole and pointed forceps resulted in the most even high compression forces. Addition of kern forceps resulted in increased cranial, but reduced caudal, compression.
270
In a study by Murphy 2024 in VCOT, what was the risk of a large breed dog (>15 kg) rupturing the contralateral cruciate if the first cruciate is ruptured over 8 years of age? What 2 factors were associated with increased risk of contralateral rupture?
29% chance.
Age and breed, labradors and golden retrievers at increased risk, were significantly associated with contralateral CCLR.
271
In a study by Redolfi 2024 in VCOT, what were the 2 major complications reported following TPLO and TTT for combined CCLR and grade III or IV MPL? What proportion of dogs had complete resolution of MPL?
SSI (3/24) and recurrence of grade II MPL (1/24) were the major complications reported.
23/24 dogs had complete resolution of MPL, and 21/22 dogs were clinically sound at follow-up.
Patellar ligament thickening was the most common short-term complication observed.
272
In a study by Villatoro 2022 in VRU, was OA more severe in small and medium breed dogs with MPL or CCL? Did OA increase with age?
More severe in dogs with CCLR (heavier dogs also more affected).
OA increased with age in dogs with MPL but not CCLR.
273
According to a study by Coppola 2022 in JFMS, what ligaments were most commonly affected in traumatic injury to the feline stifle? Was medial or lateral meniscal injury more common? In what percentage of cases was the outcome good to excellent? What three factors were associated with worsened outcome?
The lateral collateral and cruciate ligaments were most commonly affected (25%).
Medial meniscus injury (66%) was more common than lateral meniscus (60%) injury.
Good to excellent outcomes were achieved in 62% of cases.
Use of a transarticular pin for immobilization, cats with medial meniscal injuries, and revision surgery was associated with a worse outcome. Post-operative immobilization had no effect on outcome and may not be required.
274
In a study by Lee 2023 in JFMS, which of the following fixation techniques showed the greatest strength for loads at displacements of 1, 2 and 3mm in a feline patellar fracture model?
1) K-wire and figure-of-eight
2) Circumferential and figure-of-eight wiring
3) Circumferential and figure-of-eight with FiberWire
Circumferential and figure-of-eight with FiberWire was the most resistant to displacement.
275
In a study by Ferrell 2019 in Vet Surg, what was the post-operative infection rate in TTAs performed for CCLR in dogs? What percentage of infected cases required implant removal? Did post-operative antimicrobials reduce the risk of infection?
5% infection rate.
39% of cases required implant removal, with 72% of these just having the plate and screws removed (cage left in situ).
Post-operative antimicrobials did not reduce the risk for infection, but did increase the risk of oxacillin resistant infection which was also associated with a requirement for implant removal.
