Sports Knee Flashcards
1
Q
Imaging for patellar instability?
A
-
Anatomy
- Passive stability
- medial patellofemoral ligament (MPFL) is primary restraint in first 20 degrees of knee flexion
- usually avulses from medial epicondyle of femur
- patellar-femoral bony structures account for stability in deeper knee flexion
- Dynamic stability
- vastus medialis (attaches to MPFL)
- Passive stability
-
Radiographs - AP, lateral, skyline, oblique
- rule out fracture or loose body
- medial patellar facet (most common)
- lateral femoral condyle (usually occurs when patella is reduced)
- AP views
- best to evaluate overall lower extremity alignment and version
- lateral views
- best to assess for trochlear dysplasia
- Trochlea >145 = dysplasia
- Crossover sign = dysplasia = trochlea crrosses the supracondylar prominence
- Evaluate for patellar height (patella alta vs baja)
- Blumensatts line should be inferior to patella
- Insall-Salvati method
- Blackburne-Peel method
- Caton-Deschamps
- Plateau-Patella Angle (20-30 deg)
- axial views
- best assess for lateral patellar tilt
- lateral patellofemoral angle
- rule out fracture or loose body
-
MRI
- help further rule out suspected loose bodies
- osteochondral lesion and/or bone bruising
- medial patellar facet (most common)
- lateral femoral condyle
- tear of MPFL
- tear usually at medial femoral epicondyle
- CT
- TT-TG > 20 shows excessive varus
- Torsional assessment
- Assess trochlear anatomy
- TT-TG > 20 shows excessive varus
2
Q
You are concerned about patellar tendon rupture. Give 4 ways to assess patellar height
A
- Blumensatts line should be inferior to patella
-
Insall-Salvati method
- length patella/length tendon = 1
-
Blackburne-Peel method
- length articular surface/distance from line drawn parallel to tibial plateau = 0.8
-
Caton-Deschamps
- length articular surface/distance to tibial plateau = 1.0
-
Plateau-Patella Angle (20-30 deg)
- line drawn along tibial plateau, then line drawn from posterior plateau to inferior patella
3
Q
How does is strength training assoicated with strength gains?
A
- typically high-load, low-repetition activities
- results in increased cross-sectional area of muscle due to muscle hypertrophy
- hyperplasia (increased number of fibers) less likely
- results in increased motor unit recruitment +/- improved synchronization of muscule activity
- maximal force production is proportional to muscle physiologic cross-sectional area
4
Q
Treatment options for patellar instability?
A
-
NSAIDS, activity modification, and physical therapy
-
indications
- mainstay of treatment for first time patellar dislocation
- without any loose bodies or intraarticular damage
- habitual dislocator
-
techniques
- short-term immobilization for comfort followed by 6 weeks of controlled motion
- emphasis on strengthening
- closed chain short arc quadriceps exercises
- VMO strengthening
- core strengthening of hip abductors, gluteals, and abdominals
- patellar stabilizing sleeve or “J” brace
- consider knee aspiration for tense effusion
- positive fat globules indicates fracture
-
indications
-
Operatvie Approach
- Address all deformities (Osseous, static, dynamic)
- Options for Osseus
- Dysplasia - groove deepening
- TT-TG or patella alta - tibia osteotomy
- Static
- MPFL reconstruction
- Not all need to be addressed; sometimes an osteotomy with MPFL reconstruction will comprensatate for trochlear dysplasa
-
arthroscopic debridement vs ORIF
- indications
- displaced osteochondral fractures or loose bodies
- chronic patellofemoral instability
- techniques
- arthroscopic vs open
- indications
-
MPFL repair
- indications
- acute first time dislocation
- techniques
- direct repair when surgery can be done within first few days
- no clinical studies support this over nonoperative treatment
- indications
-
MPFL reconstruction with autograft vs allograft
- Has good outcomes and can improve stability even with associated boney abnormalities, however the ideal situation is below
- TT-TG <20
- Caton-dechamps < 1.2
- Apprehension at 30 deg of flexion
- Grade A trochlear dysplasia
- indications
- recurrent instability (>2)
- Has good outcomes and can improve stability even with associated boney abnormalities, however the ideal situation is below
-
medial tibial tubercle transfer
- Indications
- may be used in addition to MPFL or in isolation for significant malignment
- TT-TG >20mm on CT
- Techniques
- anteromedialized displacement of osteotomy and fixation
- correct TT-TG to 10-15mm (never less than 10mm)
- Indications
-
lateral release
- islolated release no longer indicated for instability
- only indicated if there is excessive lateral tilt or tighness after medialization
- To help offload the patella in times of painful PF syndrome refractory to PT
- technique
- arthroscopic
-
trochleoplasty
- Poor outcomes with high rates of OA and limited improvement in pain (despite some reports of improved outcomes)
- Indications
- rarely addressed (in the USA) even if trochlear dysplasia present
- may consider in severe or revision cases
- May consider if there is no other pathology
- *Contra-indicated if there is evidence of arthritis
- Often patients will get increased pain post-op, even though risk of dislocation is dramatically reduced
- techniques
- arthroscopic or open trochlear deepening procedure
-
osteochondral defect repair
- indications
- large osteochondral loose body
- techniques
- primary repair vs allograft depending on size
- indications
5
Q
Complications associated with patellar instability
A
-
Recurrent dislocation
- redislocation rates of 15-44% have directed interest more towards surgical treatment
-
Medial patellar dislocation and medial patellofemoral arthritis
- almost exclusively iatrogenic as a result of prior patellar stabilization surgery
6
Q
Where is Schottle’s point
A
- 1 mm anterior to the posterior cortex extension line
- 2.5 mm distal to the posterior origin of the medial femoral condyle
- proximal to the level of the posterior point of the Blumensaat line
- on a lateral radiograph with both posterior condyles projected in the same plane
7
Q
Ideal situation and indications for MPFL repair
A
-
Ideal situation
- TT-TG <20
- Caton-dechamps < 1.2
- Apprehension at 30 deg of flexion
- Grade A trochlear dysplasia
-
indications
- recurrent instability (>2)
Doesn’t mean that it can’t be done with boney abnormalities, but it just makes it less likely to suceed
8
Q
Approach to chondral defect in the knee
A
- <2 = drilling
- 2-4 = mosaiplasty
- >4 = allograft
- not enough donor to fill in the defect
- becomes too irregular
- HTO
- If it’s more degenerative
- Or to augment any procedure
- Always look at your alignment
- ACI
- Not used in Canada
- Cost – 25K
- Similar outcomes to microfracture
- Allograft
- Fresh, matched
- Preserved, not frozen
- Needs to be implanted with-in 21 days
- 15K
9
Q
Risk factors for patellar instability
A
- ligamentous laxity (Ehlers-Danlos syndrome)
- dysplastic vastus medialis oblique (VMO) muscle
- lateral displacement of patella
- patella alta
- causes patella to not articulate with sulcus, losing its constraint effects
- trochlear dysplasia
- excessive lateral patellar tilt (measured in extension)
- lateral femoral condyle hypoplasia
- increased quadriceps angle (Q angle)
- average for women 15 degrees
- average for men 10 degrees
- previous patellar instability event
- “miserable malalignment syndrome”
- femoral anteversion
- genu valgum
- external tibial torsion / pronated feet
10
Q
Pertient physical exam findings of patellar instablity
A
- large hemarthrosis
- absence of swelling supports ligamentous laxity and habitual dislocation mechanism
- medial sided tenderness (over MPFL)
- increase in passive patellar translation
- measured in quadrants of translation (midline of patella is considered “0”), and also should be compared to contralateral side
- normal motion is <2 quadrants of patellar translation
- lateral translation of medial border of patella to lateral edge of trochlear groove is considered “2” quadrants and is considered abnormal amount of translation
- <1cm at 30 deg of flexion
- patellar apprehension
- increased Q angle
- J sign
- excessive lateral translation in extension which “pops” into groove as the patella engages the trochlea early in flexion
- associated with patella alta
11
Q
Technique for MPFL Repair
A
- Diagnostic arthroscopy
- ST is harvested
- the graft is prepare with sutures at both ends
- Superomedial patella is exposed, two drill holes are made
- femoral origin can be reliably found radiographically (Schottle point)
- check isometry of the graft
- Drill your hole
- Secure the graft with an interference screw in the femur
- Be careful not to overtension the graft if there is trochlear dysplasia
- Controversial where to tighten the graft
- pull the graft threw the drill holes in the patella and sutured onto themselves
12
Q
Differential diagnosis for painful cartilage lesion in the knee
A
-
Secondary osteonecrosis
- older woman
- think risk of AVN
-
Spontaneous osteonecrsis of the knee
- middle age female
- releived by arthroscopy
-
Osteochondritis dissecans (OCD)
- more commonly found at _lateral aspect of medial femoral condyl_e of 15 to 20-year-old males
-
Transient osteoporosis
- more common in young to middle-aged men
- multiple joint involvement found in 40% of patients (transient migratory osteoporosis)
-
Occult fractures and bone bruises
- associated with trauma, weak bones, or overuse
13
Q
What is the outerbridge classification
A
Grade 0: Normal cartilage
I: Softening and swelling
II: Partial thickness defect, fissures < 1.5cm diameter
III: Fissures down to subchondral bone, diameter > 1.5cm
IV: Exposed subchondral bone
14
Q
Factors that will affect your decision making in articular cartilage defect
A
-
patient factors
- age
- skeletal maturity
- low vs. high demand activities
- ability to tolerate extended rehabilitation
-
defect factors
- size of defect
- location
- contained vs. uncontained
- presence or absence of subchondral bone involvement
15
Q
Surgical options to address cartilage lesions in the knee
A
-
Address concominant injuries
- Soft tissue
- Meniscus
- Meniscetomy is a relative contraindication to cartilage salvage procedures
- Young patients may warrant a meniscal transplant
- Cruciate deficiency
- MFPL or patellar stabilization
- Meniscus
- Boney (unloading or alignment)
- High tibial osteotomy
- Tibial tubercle osteotomy
- Soft tissue
-
ORIF
- acute injury
- sufficient osseous portion
-
Microfracture <2X2
- can do retrograde if articular surface is intact
- single procedure
- does not address bone loss
- Best results
- <2X2cm
- contained
- acute
-
Moscaoplasty <2X2
- limited by irregular surface and harvest
- medial and lateral NWB trochlea
- cost effective, single stage
- requires 3 month NWB
-
ACI
- 2 stage, expensive
- requires contained defect
- comparable to microfracture
-
Allograft
- large, uncontained defect
- lots of processing, expensive, but works
For older patients can consider UKA, TKA
16
Q
What are two patellar unloading procedures
A
-
Maquet (tibia tubercle anteriorization)
- indicated only for distal pole lesions
- only elevate 1 cm or else risk of skin necrosis
- contraindications
- superior patellar arthrosis (scope before you perform the surgery)
-
Fulkerson alignment surgery (tibia tubercle anteriorization and medialization)
- indications (controversial)
- lateral and distal pole lesions
- increased Q angle
- contraindications
- superior medial patellar arthrosis (scope before you perform the surgery)
- skeletal immaturity
- indications (controversial)
17
Q
technique for allochondral graft for the knee
A
-
overview
- goal is to replace cartilage defect with live chondrocytes in mature matrix along with underlying bone
- fresh, refrigerated grafts are used which retain chondrocyte viability
- Max 28 days
- may be performed as a bulk graft (fixed with screws) or shell (dowels) grafts
-
technique
- match the size and radius of curvature of articular cartilage with donor tissue - based on the plain AP
- MRI can be used but will underestimate the size of the lesion
- Small subvastus can be used vs more extended medial or lateral parapatellar for improved exposure
- a recipient socket is drilled at the site of the defect
- an osteochondral dowel of the appropriate size is cored out of the donor
- Thinner is better to reduce amount of implanted bone
- the dowel is press-fit into place
-
Clinical pearls
- Lots of irrigation to reduce thermal injury
- Light impaction of the graft so you don’t injury the condrocytes
-
benefits
- include ability to address larger defects, can correct significant bone loss, useful in revision of other techniques
-
limitations
- limited availability and high cost of donor tissue
- live allograft tissue carries potential risk of infection
-
Post-op
- Avoid shear or compressive stress for 6 weeks
- Limited WB
- Full ROM
- Brace is controversial
- 6-12 weeks
- ADL, progress strength
- 3 months
- Strength, core, proprioceptive with gradual return to sports
- Avoid impact activities (6-12months)
18
Q
Options for cartilage regeneration
A
-
Chondrocytes
- ACI: autologous chondrocyte implantation
- chondrocytes harvested from non-wt bearing surface & expanded ex-vivo
- in separate procedure, periosteal flap harvested and sewn over defect; chondrocytes in collagen suspension are squirted underneath & sealed with fibrin
- problem → does not regenerate hyaline cartilage
-
Pluripotent Stem Cells
- embryonic stem cells (ESC) & induced pluripotent stem cells (iPSC)
- may lead to the development of tumor; teratoma formation in vivo is well recognized
- no current studies underway
-
Mesenchymal Stem Cells
- ability to differentiate along various cell lineages, including chondrocytes, adipocytes, osteoblasts, and myocytes
- ideal option for cartilage regeneration because they represent a readily available and accessible supply of cells, and they have the capacity for considerable expansion and differentiation
- TGFβ & BMPs used to induce chondrogenesis
- bone marrow stem cells (BMSC) have been used in some studies with promising results
19
Q
What are the main factors stimulating cartilage growth
A
TGFβ family, including BMP-2 & BMP-7
chondrogenic differentiation
stimulating production of cartilage ECM
Others:
FGF, IGF-1, PDGF, and, of course, PRP!
20
Q
What predisposes females to ACL tears
A
Neuromuscluar, quads dominant
Landing biomechanics - higher valgus, more extension (see below)
Smaller notches
Smaller ligaments
Hormone levels (arises at puberty, poor understanding)
Valgus leg alignment
Higher tibial slope
21
Q
Anatomy of the ACL
A
- 85% of anterior stability
- 1100N to tear
- 90% type 1 collagen
- Secondary restraint to rotation
- Anatomy
- 33X11mm
- LFC
- Anterior to PCL, at level of anterior horn of lateral meniscus
- Bundles
- Anteromedial - isometric
- Posteriolateral - tight in extension, contributes to rotational stability
- Blood supply - middle geniculate artery
- Innervation - posterior articular nerve (from tibial nerve)
22
Q
Injuries associated with ACL tear
A
- Often associated with a meniscal tear
- lateral meniscal tears in up to 50% of acute ACL tears
- Bone bruising (50%)
- LFC in sulcus terminalis
- Posterior tib plateau
- Chronic ACL deficient knees associated with
- chondral injuries
- complex unrepairable meniscal tears
- medial meniscal tears
- relation with arthritis is controversial
23
Q
what degree of slope is at risk for ACL tear
A
>12 deg
24
Q
What are key factors to include in an acl prevention program
A
- 30 min, 3 times/wk for approximately 8 wk
- Preseason implementation for neuromuscular adaptation
- Perform as a warm-up to avoid neuromuscular fatigue
- Maintenance recommended to avoid deconditioning, which can occur at 2 to 8 wk
- Must include neuromuscular and proprioceptive training, plyometrics, agility drills, func-tional balance, and core strengthening
- Low cost and easy to implement
- Identify at-risk players who need more intensive intervention (eg, drop vertical test)
- Encourage compliance (eg, varied workouts, correlate training with improved sport/ muscular performance, risk awareness education/training)
25
Q
Compare options for ACL grafts
A
-
BTB
- Gold standard
- Bone to bone - better incorperation and sooner return to play
- Secured with Interference screws, endobutton
- Anterior knee pain, patellar fracture
-
Hamstring
- Smaller incision, less knee pain
- Less strength, but high load to failure
- Decreased peak flexion strength
- Residual hamstring rupture
- Note - posterior harvest allows you to see the tendon cross-connections more easily so you don’t get diverted
-
Allograft
- Good in revision
- Takes longer to incorperate
- Disease transmission
- Increased risk of re-ruputre
- Processing - rad to kill HIV, freezing is better but no antiviral
- Reduces strength of the graft
26
Q
Etiology of graft failure in ACL recon
A
-
surgical technical error is the most common cause of ACL failure
- improper tunnel placement causes failure in 70%
- vertical femoral tunnel will cause continued rotational instability and positive pivot shift
- Anterior tunnel placement is tight in flexion (but tightened in flexion will lead to failure)
- Inadequate notchplasty
- Inadequate tensioning - difficult to quantify
- Should cycle the knee
- tension in extension or will be tight or unable to get extension
- inadequate fixation
- can be caused by graft-screw divergence >30 degrees
- improper tunnel placement causes failure in 70%
-
Biological
- Failed ligamentization - avascularity, immunogenicity (more with allograft)
- Arthrofibrosis
- Infection
- Traumatic
- Early - overaggressive rehab
27
Q
Etiology of tunnel widening in ACL recon
A
- Graft position and fixation method can lead to motion of the graft with-in the tunnel
- Graft sterilization (ethylene oxide)
- inflammation around graft
- Bio absorbable screws
- allograft
- Synovial fluid propagation
28
Q
Approach to revision ACL surgery
A
-
Approach
- Arthroscopic versus 2 incision
-
use high strength grafts (quad tendon, hamstring, allograft)
- Synthetic and reharvest are not recommended
- Contralateral patella has at times been used, or in same knee if wasn’t used before
- Especially with widened tunnels
- Achilles tendon allograft
- Can be fashioned with a bone plug the size of the tunnel deficiet
- Decision with patient
-
Bone grafting (tunnel dilation, decreased bone stock, staged prn)
- Graft removal, tunnel curettage, bone graft
-
Options
- Stage with bone grafting of tunnels if necessary (then come back 6-12 weeks)
- >100% of the original tunnel
- Over the top technique (sling around the lateral femoral condyle)
- Divergent tunnel
- Double interference screws
- Matchstick technique, allograft bone plug
- Stage with bone grafting of tunnels if necessary (then come back 6-12 weeks)
- Redo notchplasty (often overgrowth from first procedure, may be cause of failure)
- use dual fixation (suspension + interference screws)
-
Correct instability
- Posterolateral rotatory instability
-
Correct alignment
- Varus limb may have developed in chronic situation
- Helps to protect the graft
- conservative rehab
33
Q
What is the anatomy of the PCL
A
-
Gross anatomy
- PCL extends from MFC to tibial sulcus
- 38mm x 13mm in size
- anterolateral is tight in flexion - primary component of the PCL
- posteromedial is tight in extension
- variable meniscofemoral ligaments (Humphrey, Wrisberg) originate from the posterior horn of the lateral meniscus and insert into the substance of the PCL
-
Blood supply
- supplied by middle geniculate artery
-
Biomechanics
- strength is 2500 N (posterior)
- The PCL is not isometric
- The PM bundle is horizontal in flexion and vertical in extension
- The AL bundle is vertical in flexion and horizontal in extension
39
Q
Anatomy of the MCL
A
-
origin
- medial femoral epicondyle
-
insertion
- long strip on tibia
-
two components
-
superficial portion (tibial collateral ligament)
- contributes 57% and 78% of medial stability at 5 degrees and 25 degrees of knee flexion, respectively
- lies just deep to gracilis and semitendinosus
- originates from medial femoral epicondyle just below adductor tubercle and inserts into periosteum of proximal tibia (deep to pes anserinus)
-
deep portion (medial capsular ligament)
- attaches to medial meniscus (coronary ligament)
- the deep MCL and posteromedial capsule act as secondary restraints at full knee extension.
-
superficial portion (tibial collateral ligament)
- strength
- 4000 N (valgus)
48
Q
Compare lateral wedge and medial opening wedge HTO, what are other options
A
-
lateral closing wedge technique
- Falling out of favour due to bone loss and issues with TF joint
- wedge of bone removed with tibia via an anterolateral approach
- has advantages but really no differences in outcomes compared to opening wedge
- more inherent stability allows for faster rehab and weight bearing
- no required bone grafting
- easier to control slope
-
medial opening wedge technique
- Use a bovie cord from the femoral head to the center of the plafond to assess your mechnical joint line (62.5 % of plateau)
- Size podoo or locking plate
- Bone graft > 1cm
- Specific complications
- Popliteal artery injury
-
advantages
- maintaining posterior slope
- avoids proximal tibiofibular joint
- avoids peroneal nerve in anterior compartment
-
Dome Osteotomy
-
If >20 deg of alignemnt required to avoid changing joint height
- traumatic
- blounts
- above the tibial tubercle
-
If >20 deg of alignemnt required to avoid changing joint height
- Callus Distraction - TSF
61
Q
Appropriate imaging for PLC injury
A
-
Radiographs - AP, lateral and don’t forget full length views!
- may see avulsion fx of the fibula or femoral condyle
- Arcuate sign - fibular head fracture
- Segond - need to repair capsule when you have this
- stress radiography can be done but MRI is diagnostic study of choice
- Kneeling XR can show how much posterior translation there is on the tibia
- Full length standing views to assess alignment - varus malalignment when unrecognized is a common form of failure
-
MRI
- look for injury to the LCL, popliteus, and biceps tendon
- in acute injury may see bone brusing of medial femoral condyle and medial tibial plateau
- 2mm coronal oblique cuts can help you look at the popliteus and LCL
63
Q
Describe the labprade technique for PLC reconstruction
A
-
Don’t forget
- rule out vascular or peroneal nerve injury
- full length standing films, clinical, or CT for alignment
-
Full examination under anaesthesia
- Determine ligaments that need to be repaired
- Varus = LCL
- just rotation = PFL (often chronically LCL is intact)
-
Diagnostic scope
- other injuries
- drive through sign
- Then make a hockey stick incision for the PLC
- Incision in line with IT band, expose structures underneath
- identify, protect the peroneal nerve, decompress as needed
- Arthrotomy can be performed to repair the meniscofemoral or meniscotibial ligaments
-
techniques
- options
- direct repair
- two seperate grafts
- split achilles tendon graft
- goal is to reconstuct LCL and the popliteofibular ligament using a free tendon graft (semitendinosus or achilles)
- grafts are prepared and tubularized
- trans-tibial double-bundle reconstruction (Laprode)
- two allograft tendons
- one branch is fixed to the fibular head with a bone tunnel and tranosseous sutures to reconstruct the LCL
- second graft is brought through the posterior tibia to reconstuct the popliteofibular ligament
- 1cm anterior and distal compared to LCL
- options
-
postop
- 4 weeks of postop cast controls leg ER better than knee brace
70
Q
technique for meniscal transplant
A
-
technique
- If doing in conjunction with an ACL
- Drill your tunnels and prepare the graft (use PTB)
- Then drill the tunnels or bone bridge and secure the meniscus
- Then pass the graft
- bone to bone healing with plugs (medial) at each horn or a bridge between horns (lateral)
- Keyhole technique becoming popular
- peripheral sutures
- If doing in conjunction with an ACL
- Rehab
- Begin when swelling is down
- Back to work in 2 weeks
- 2-3 months before full activity
71
Q
Indications and techniques to fix a mensical root tear
A
- >3mm excursion of the posterior horn of the meniscus = root tear
- Associated with OA
-
Should be fixed to prevent OA
- <50
- Active patient
- Outerbridge <3
- Normal alignment
-
Options for fixation
- Transtibial pullout
- 5mm tunnel
- Cortical button
- Suture anchor
- Posteromedial portal
- Transtibial pullout
-
Post-op
- PWB in zimmer
- Progress WB at 8 weeks
