Stifle Flashcards
Tx options for upward fixation of the patella (UFP)
- Conservative - exercise (hills etc) to develop quadriceps musculature, IA chondroprotection etc
- Injection of counter irritants eg 2% iodine in almond oil andethanolamine oleate
- Medial patella ligament desmoplasty (splitting) - particularly the proximal 1/3 of the ligament
- Medial patella ligament desmotomy
Outcome of MPL desmoplasty (splitting)
Good px; 17 of 24 (71%) horses returned to work; 3 of 17 (18%) returned at a higher level, 12 of 17 (71%) at same and 2 at lower level Complications: minimal - tx failure (need desmotomy) - recurrence of UFP seen in upt 33%
Outcome of MPL desmotomy
Variable reports in the literature, 1 reports states 94% success rate but may be assoc. w. high complication rate
Complications of MPL desmotomy
1) femoropatellar joint instability leading to OA,
2) Fragmentation of the apex of the patella
3) distal patellar fibrillation and/or subchondral lysis
4) Femoropatellar synovitis; persistent effusion
5) Medial patellar ligament fibrosis or enthesiopathy
6) Persistent low grade lameness
5 meniscal ligaments
Cranial ligament of the medial meniscus
Cranial ligament of lateral meniscus
Caudal ligament of medial meniscus
Caudal ligament of lateral meniscus
Meniscofemoral ligament of the lateral meniscus
Recumbency and limb position for ASY
Dorsal recumbency
Extension for FPj (cannon roughly vertical)
90° flexion for the femorotibial joints
Cranial cruciate origin and insertion
Origin: caudolateral intercondylar fossa (10 o’clock position in the intercondylar fossa on CC rad
Insertion: Axial aspect of the MICET
Caudal cruciate origin and insertion
Origin: craniomedial intercondylar fossa
Insertion: caudomedial border of the medial tibil condyle
Remember named as per cr/cau insertions on the tibia
Collateral ligament origins and insertions
Medial and lateral femoral epicondyles
Medial inserts on medial tibial condyle extending into metaphyseal region
Lateral inserts on fibular head
Long extensor origin
Extensor fossa of the lateral femoral condyle
Lateral extensor origin
Proximal tibia/head of fibula and lateral collateral insertion
Popliteal tendon origin and insertion
Origin: Just distal to lat collateral ligament on the lateral epicondyle of the femur
Insertion: ?medial tibia
intra-articular and divides the caudal pouch of the lateral femorotibial joint into proximal and distal compartments within its synovial diverticulum.
Most common site of FPj OCD
Lateral trochlear ridge - proximal 1/3
Most common patella fracture configuration
Medial parasagittal
Typically occur while the joint is in partial flexion e.g. when jumping over a fixed obstacle hunting or eventing. Patella is fixed against the trochlea in flexion so direct trauma causes contact with the more prominent medial trochlear ridge, hence fracture is medial of midline
Standard tx for medial parasagittal patella fractures and size limitations
Fragments lass than 1/3 of the size of the patella are best tx with ASY removal
Need to dissect free from medial patella lig, medial femoropatella lig and parts of the vastus medialis tendon
Indications for internal fixation of patella fractures and recommended screw size in adults
Rarely performed
Indications incl. transverse fractures and sagittal fractures exceeding 1/3 the size of the patella
5.5mm cortex screws are recommended in adult horses
Method of fixation of transverse patella fractures
Combination of lag screw fixation and cranial tension band with 1.25mm diameter cerclage wire, or screws plus cranial plate
The complete disruption of the quadriceps apparatus is a typical feature of transverse, but not sagittal or parasagittal patellar fractures. Tension band or cranial plate therefore required to oppose the loading in tension that these fractures are subjected to
Grades of congenital patella luxation (from Fubini and Ducharmme)
I - intermittent luxation. Can be manually luxated in full stifle extension but readily returns to normal position once released
II - intermittent luxation. Can be manually luxated in full stifle extension, and does NOT readily return to normal position when released
III - Permanent luxation. (permanent crouched posture). Patella can be manually repositioned but reluxates once released
IV - Permanent luxation - can’t be manually repositioned. Trochlear groove is flat and LTR deformed
Ddx for patella luxation (F&D)
- Femoral nerve deficits (difficult calving)
- Distal femoral fracture
- Patella fracture
- Femoropatella ligament ruptures (traumatic)
Tx for patella luxations (F&D)
Grades I and II - conservative - can be productive
Grade III - lateral patella release, medial imbrication +/- trochleoplasty
Grade IV - lateral patella release, medial imbrication & trochleoplasty +/- tibial tuberosity repositioning (light/young animals)
Techniques for sx management of congenital (or traumatic) lateral patella luxation
What is the expected athletic prognosis?
2 main techniques have been described
(i) fascial release with imbrication
(ii) reconstructive surgery with or without release and imbrication techniques
Reconstructive techniques such as trochlear sulcoplasty, are typically reserved for cases where there is an underlying congenital trochlear hypoplasia contributing to the patellar luxation. In cases of traumatic patellar luxation with no underlying congenital trochlear hypoplasia, trochlear sulcoplasty is likely unnecessary, and increases the risk of post-operative complications
Typically, the prognosis for return to athletic function following surgical repair of patellar luxation is guarded to poor
According to Frazer et al 2019 vet surg, what happens to compressive, tensile and shear stress with addition of a 2cm3 void in the MFC
Compressive stress incr by 25%
Shear stress incr. by 50%
Tensile stress incr by 200%
What effect does an MFC void have on the stresses in the meniscus (Frazer 2019 Vet Surg)
Increases compressive and shear stress by upto 30%. May help to explain the relationship between MFC lesions and medial meniscus damage
Return to intended use following stifle ASY in Western performance horses (QH) reported by McCoy et al (VS 2019)
What were negative prognostic factors (4)
40% return to intended use
Less chance of return to intended use in older horses, increased duration AND severity of lameness, partial thickness cartilage lesions
No IA or systemic PO therapies had a demonstrable beneficial effect on outcome
According to the finite element model of Frazer et al (VS 2019) which screw position is most beneficial for stimulating new bone formation WRT MFC cysts
PDO - proximodistal oblique screw in lag
Orients the compressive stresses across the SBC thus promoting new bone formation.
Increasing screw compression, load and cyces (steps) per day (steps) likely increases the rate of new bone formation, therefore hand walking exercise should be provided from 2 weeks PO
Quadriceps femoris anatomy
4 heads
1) The rectus femoris (RF) origonates on the pelvis (long head)
2) Vastus lateralis (VL) - originates proximally on the lateral aspect of the femur, at the base of the great trochanter. It is covered proximally by the tensor fascia latae and gluteus superficialis muscles and by the fascia latae itself on the rest of the muscle body. The distal part of the VL fuses with the RF muscle
3) Vastus medialis (VM) - originating on the medial aspect of the femur close to the femoral neck. It is connected caudally to the sartorius and adductor muscles
4) Vastus intermedius (VI) - covering the cranial and adjacent aspects of the femur, between the VM and VL muscle. It is separated in two parallel parts: a lateral and a medial, which end with the corresponding vastus muscles
All insert on the base of the patella
Overall tx approach for MFC SCL (CAT EVE 2019 O’Brien)
- APPROACH SUMMARY: arthroscopic intralesional corticosteroid injection appears to be the initial treatment of choice in most cases. This procedure enables thorough joint inspection and treatment of co-existing injuries, confirmation of accurate injection, and a rapid return to function.
- Should this treatment fail, lag screwing appears to be the most suitable second line treatment. Since older animals (>3) may respond more poorly to SCL treatment, delays should be avoided.
- Arthroscopic SCL debridement with chondrocyte and IGF-1 implantation is more costly and technically challenging and offers similar success rate to other treatments, so therefore does not seem to be justified for most cases.
- Conservative treatment (rest +/- intralesional corticosteroid injection under ultrasonographic guidance) may be appropriate where there are economic constraints, a rapid return to work is not expected, and lameness is not uncontrollably severe
What radiographic view of the stifle should be included if cruciate ligament injury is suspected? (Adrich 2019 VCOT) and why?
Caudo-45°medial craniolateral oblique
Highlights the origin of the cranial cruciate ligament on the caudoaxial aspect of the lateral femoral condyle within the intercondylar fossa
Proposed radiographic grading of medial femoral condyle lesions (0-4)
Grade 0 - normal
Grade 1 - flattening of the MFC
Grade 2 - subchonral bone sclerosis +/- defects in the subchondral bone that don’t extend all the way through the SCB plate
Grade 3 - SCB defects that extend all the way through the SCB plate. Can be wide and shallow lucencies
Grade 4 - well defined round or oval radiolucent area in the middle of the MFC that extends to and communicates with the MFT joint
Reported sensitivity and specificity of scintigraphy for stifle disorders?
Graham et al 2015 VRU reported sensitivity of 20.8-29.2% (varied w different radiologists) and specificity was 84.5-88.3%.
Ie high false negatives and low false positives
Label the diagram
a - parapatella fibrocartilage
b - medial patella ligament
c - medial collateral ligament
d - tibial tuberosity
e - cut stump of biceps femoris
f - middle patella lig
g - lateral patella lig
h - lateral collateral
i & k - medial & lateral tibial condyles
Label the diagram
a - FPJ
b - middle patella lig
c - medial patella lig
d - cut end of lateral patella lig
e - long digital extensor mm
f - lateral femoropatella ligament
g - popliteus mm
h - lateral tibial condyle
i - lateral extensor mm
