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Imaging for patellar instability?


  • 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)‚Äč
  • 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¬†¬†
  • 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



You are concerned about patellar tendon rupture.  Give 4 ways to assess patellar height

  • Blumensatts line should be inferior to patella
  • Insall-Salvati method
    • ‚Äčlength 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


Treatment options for patellar instability?


  • 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
  • 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¬†
  • 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
  • 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
      • Caton-dechamps
      • Apprehension at 30 deg of flexion
      • Grade A trochlear dysplasia
    • indications
      • recurrent instability¬†(>2)
  • 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)
  • 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



Complications associated with patellar instability

  • 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¬†


Where is Schottle's point

  • 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


Ideal situation and indications for MPFL repair

  • Ideal situation
    • TT-TG
    • Caton-dechamps
    • 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



    Types of muscle contractions

    • Isotonic¬†
      • Force remains constant through range of motion¬†
      • improves motor performance
      • Biceps curls using free weights
    • Isometric¬†
      • Constant muscle length and tension that is proportional to the external load
      • Causes muscle hypertrophy
      • Pushing against an immovable object
    • Concentric¬†
      • Shortened muscle and tension that is proportional to the external load
      • Biceps curl with elbow flexing
    • Eccentric
      • Force remains constant as muscle lengthens.
      • Most efficient method of strengthening¬†muscle¬†
      • Biceps curl with elbow extending¬†
    • Isokinetic¬†
      • Muscle contracts at a constant velocity or constant external load. ¬† ¬† ¬†
      • ¬†often used to objectively evaluate muscle strength during injury rehabilitation.
      • Require special machines (e.g, Cybex).
    • Plyometric
      • Rapid eccentric-concentric shortening
      • Good training for sports the require power
      • Box jumps
    • Open chain¬†
      • Distal end of extremity moves freely
      • Seated leg extensions and curls
    • Closed chain¬†
      • Distal end of extremity is fixed
      • Squats with planted foot


    How does dynamic exercise training improve cardiac output?

    increasing stroke volume


    Changes that occue during aerobic training

    • contractile muscle adapts by increasing energy efficiency
      • increases in mitochondrial size, number, and density
      • increases in enzymes involved in Krebs cycle, fatty acid processing, and respiratory chain
      • over time, increased use of fatty acids > glycogen
      • over time, oxidative capacity of Type I, IIA, and IIB fibers increase
      • percentage of more highly oxygenated IIA fibers increases
    • Aerobic Threshold: level of effort at which anaerobic energy pathways become significant energy producer
    • Anaerobic (lactate) Threshold: level of effort at which lactate production > lactate removal


    How does is strength training assoicated with strength gains?

    • 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


    how does weight traing change muscle composition

    • Effects on muscles
      • increased¬†cross-sectional area
      • increased strength
      • increased mitochondria
      • increased capillary density
      • thickened connective tissue
    • Adult strength gains are associated with¬†muscle hypertrophy
    • Adolescent strength gains occur more from¬†increased muscle firing efficiency¬†and coordination


    What are 4 kinds of muscle injury?

    • Muscles soreness
      • caused by¬†edema and inflammation¬†in the connective tissue
        • leads to increased intramuscular pressure
        • occurs primarily in Type IIB fibers
      • worse with unaccustomed eccentric exercise
      • often with delayed onset: Delayed-Onset Muscle Soreness (DOMS)¬†
        • peaks at 24-72 hours
      • elevated CK levels seen in serum
    • Muscles strain
      • occurs commonly at¬†myotendinous junction¬†(off during¬†eccentric contraction¬†which produces highest forces in skeletal muscle)
      • pathoanatomy in inflammation followed by fibrosis
    • Muscle contusion
      • non-penetrating blunt injury
      • leads to hematoma and inflammation
      • extracellular connective tissue forms within 2 days, peaks between 5-21 days
      • healing characterized by late scar formation, variable muscle regeneration
      • myositis ossificans (bone formation within the muscle tissue)¬†
        • most apparent 4 weeks post-injury
    • Muscle laceration (complete tear)
      • typically occur near myotendinous junction
      • characterized by abnormal muscle countour
      • fragments heal by dense connective scar tissue
        • this process is mediated by myofibroblasts
        • TGF-Beta stimulates differentiation and proliferation of myofibroblasts¬†
      • regeneration and renervation: unpredictable and likely incomplete


    Treatment of muscle injury

    • Goals of treatment
      • decrease inflammation
      • increase local blood flow
      • increase tissue compliance
    • Modalities include
      • cryo or heat treatments
      • massage
      • ultrasound
      • electrical stimulation
      • Iontophoresis¬†
        • use of an electrical current to drive charged molecules of medicine through the skin to the deep tissues
        • medications including steroids, local anesthetics, salicylates, and non-steroidal anti-inflammatory drugs


    Approach to chondral defect in the knee

    • 2-4 = mosaiplasty
    • >4 = allograft
      • not enough donor to fill in the defect
      • becomes too irregular
    • HTO
      • If it‚Äôs more degenerative
      • Or to augment any procedure
      • Always look at your alignment
    • ACI
      • Not used in Canada
      • Cost ‚Äď 25K
      • Similar outcomes to microfracture
    • Allograft
      • Fresh, matched
      • Preserved, not frozen
      • Needs to be implanted with-in 21 days
      • 15K


    Risk factors for patellar instability


    • 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


    Pertient physical exam findings of patellar instablity


    • 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
      • lateral translation of medial border of patella to lateral edge of trochlear groove is considered "2" quadrants and is considered abnormal amount of translation
    • 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


    Technique for MPFL Repair

    • 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


    Differential diagnosis for painful cartilage lesion in the knee

    • Secondary osteonecrosis
      • ‚Äčolder 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 condyle 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


    What is the outerbridge classification

    Grade 0: Normal cartilage
    I: Softening and swelling
    II: Partial thickness defect, fissures  III: Fissures down to subchondral bone, diameter > 1.5cm
    IV: Exposed subchondral bone


    Factors that will affect your decision making in articular cartilage defect


    • 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



    Surgical options to address cartilage lesions in the knee


    • 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
      • Boney (unloading or alignment)
        • High tibial osteotomy
        • Tibial tubercle osteotomy
    • ORIF
      • ‚Äčacute injury
      • sufficient osseous portion
    • Microfracture
      • can do retrograde if articular surface is intact
      • single procedure
      • does not address bone loss
      • Best results
        • contained
        • acute
    • Moscaoplasty
      • ‚Äčlimited by irregular surface and harvest
      • medial and lateral NWB trochlea
      • cost effective, single stage
      • requires 3 month NWB
    • ACI
      • ‚Äč2 stage, expensive
      • requires contained defect
      • comparable to microfracture
    • Allograft
      • ‚Äčlarge, uncontained defect
      • lots of processing, expensive, but works¬†

    For older patients can consider UKA, TKA


    What are two patellar unloading procedures

    • 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


    technique for allochondral graft for the knee

    • 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)¬†


    Options for cartilage regeneration

    • 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 ‚Üí 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
      • TGFő≤ & BMPs used to induce chondrogenesis
      • bone marrow stem cells (BMSC) have been used in some studies with promising results


    What are the main factors stimulating cartilage growth

    TGFő≤ family, including BMP-2 & BMP-7

    chondrogenic differentiation

    stimulating production of cartilage ECM


    FGF, IGF-1, PDGF, and, of course, PRP!


    What predisposes females to ACL tears

    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


    Anatomy of the ACL


    • 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)



    Injuries associated with ACL tear

    • 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


    what degree of slope is at risk for ACL tear

    >12 deg


    What are key factors to include in an acl prevention program

    • 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)¬†


    Compare options for ACL grafts

    • 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


    Etiology of graft failure in ACL recon


    • 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
    • Biological
      • Failed ligamentization - avascularity, immunogenicity (more with allograft)
    • Arthrofibrosis
    • Infection
    • Traumatic
    • Early - overaggressive rehab


    Etiology of tunnel widening in ACL recon

    • 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


    Approach to revision ACL surgery


    • 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
    • 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



    Options for graft fixation in revision ACL

    • 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


    Complications other than graft rupture in ACL recon

    • Missed combined injury
      • in combined ACL and PLC injuries, failure to treat the PLC will lead to failure of ACL reconstruction
    • Cyclops lesion
      • fibroproliferative tissue blocks extension
      • "click" heard at terminal extension
    • Septic Arthritis
      • Staph aureus most common
      • presentation
        • pain, swelling, erythema, and increased WBC at 2-14 days postop
        • perform immediate joint aspiration with gram stain and cultures
      • treatment
        • immediate arthrocopic I&D
        • often can retain graft with multiple I&Ds and abx (6 weeks minimum)
    • Loss of motion
      • preop
        • be sure patient has regained full ROM before you operate ("pre-hab")
        • wait until swelling (inflammatory phase) has gone down to reduce incidence of arthrofibrosis
      • operative
        • proper tunnel placement is critical to have full range of motion
      • postop prevention
        • aggressive cryotherapy (ice)
      • treatment
        • > 12 weeks than treat with lysis of adhesions / manipulation under anesthesia
    • Patella Tendon Rupture
    • will see patella alta on lateral radiograph
    • RSD (complex regional pain syndrome)
    • Patella fracture (most fx occur 8-12 weeks postop)
    • Hardware failure
    • Tunnel osteolysis (treat with observation)
    • Late arthritis (related to meniscal integrity)
    • Local nerve irritation (saphenous nerve)¬†


    2 mechnisms for injury of PCL

    direct blow to proximal tibia with flexed knee (dashboard injury)

    noncontact hyperflexion with plantar-flexed foot 


    What is the biomechanical result of PCL deficient knee

    • PCL deficiency leads to increased contact pressures in the¬†patellofemoral¬†and¬†medial compartments¬†of the knee due to varus alignment¬†
    • whether¬†¬†late patellar and MFC chondrosis¬†will develop remains controversial


    What is the anatomy of the PCL

    • 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


    Physical exam of the PCL

    • Look - varus hitch or alignment, effusion acutely
    • Feel
    • Move¬† - assess locked knee
    • Rule out other associated injuries
    • posterior drawer test
    • quadriceps active test
    • reverse pivot shift
      • Can get a positive dial when the PLC is also injured
    • Will never get a positive dial alone at 90 deg


     treatment of PCL

    • protected weight bearing
      • indicated in isolated¬†Grade I and II¬†injuries
      • follow with¬†quadriceps rehabilitation¬†¬†¬†
      • can return to sports within ~4 weeks
    • extension brace for 2-4 weeks
      • indicated in isolated¬†Grade III¬†injuries
      • followed by quadriceps rehab
      • may choose surgery if bony avulsion or a young athlete -¬†always fix a boney avulsion
    • ‚ÄčRepair if multi-lig


    Compared transtibial vs inlay technique for PCL

    • Arthroscopic repair ¬†- transtibial technique
      • transtibial from front to back via arthroscopy
      • risk of popliteal vessels
      • fix graft in flexion¬† with risk of "killer curve"
        • Sawing and stretching causes risk of graft failure
        • "windsheild wiper effect" of sawing the graft on the tibia
    • Open (tibial Inlay)
      • used for ORIF of bony avulsion
      • uses posterior-medial approach between¬†medial head of gastroc¬†and¬†semimembranosis
      • Can do this mostly arthroscopically or with a small medial incision to see the graft¬†
      • Will inlay a bone graft
        • Achilles allograft
        • BTB
      • biomechanic studies show less graft attrition and failure because there is no killer curve
    • Femoral tunnels should be in AL location (PM leads to overtensioning)
    • Slightly anterior tunnel has more constrained knee
    • Inside out technique is better with more reliable tunnels


    What are the medial structures of the knee

    • Layer I
      • sartorius and fascia
    • gracilis, semitendinosis, and saphenous nerve run between layer 1 and 2
    • Layer 2
      • semimembranosus, superficial MCL, posterior oblique ligament
    • Layer 3
      • deep MCL, capsule


    What is the order of strength of the ligaments of the knee

    MCL - 4500

    PCL - 2200

    ACL - 1100

    LCL - 750


    Anatomy of the MCL

    • 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.
    • strength
      • 4000 N (valgus)


    MCL physical exam

    • valgus opening
    • Axial load to find neutrality
      • 30¬į degees only - isolated MCL
      • 0¬į and 30¬į degees - combined MCL and ACL or PCL
    • Classification - make sure you differentiate acute and chronic (there is a second classification system that is based on whether there is an endpoint, don't get the two confused when looking at literature)
      • Grade I: 0-5 mm opening (microscopic)
      • Grade II: 6-10 mm opening (partial)
      • Grade III: 11-15 mm opening (complete)


    Treatment of isolated MCL tear

    • treat in hinged knee brace for 6-8 weeks
      • only knee ligament injury the body can heal independently
      • proximal ruptures have better healing potential than distal ruptures
    • rehabilitation
      • early ROM and functional rehab (immediate quads) in athletes
      • return to play depends on discomfort and residual instability
        • Grade I: 2 weeks
        • Grade II: 3 weeks
        • Grade III: full extension for 2 weeks followed by 6 to 8 weeks of total rehab (must ensure it is isolated MCL)
    • medications
      • ibuprofen shown to not be deleterious to MCL healing
      • new studies have shown that platelet-derived growth factor (PDGF) improves healing


    What are the structures of the PLC

    • Static structure - is what you will reconstruct during injury
      • LCL
        • Attaches 8mm behind the most anterior fibula
      • Politeus tendon with popliteofigular ligament
        • Inserts 18.5mm distal, anterior and underneath LCL on the tibia
      • Popliteofibular ligament
      • Lateral capsule
      • Arcuate ligament
      • Fabellofibular ligament
    • Dynamic
      • Biceps femoris (inserts posterior to LCL on fibula)
      • Popliteus
      • Iliotibial tract


    What are the layers of the lateral knee

    • Layer I
      • Iliotibial tract, biceps
      • common peroneal nerve lies between layer I and II
    • Layer 2
      • patellar retinaculum, patellofemoral ligament
    • Layer 3
      • superficial: LCL, fabellofibular ligament
      • lateral geniculate artery runs between deep and superficial layer
      • deep: arcuate ligament, coronary ligament, popliteus tendon, popliteofibular ligament, capsule


    What is the schneck classification of knee dislocation

    KD I

    Multiligamentous injury with involvement of ACL or PCL

    KD II

    Injury to ACL and PCL only (2 ligaments)

    KD III

    Injury to ACL, PCL, and PMC or PLC (3 ligaments)

    KD IV

    Injury to ACL, PCL, PMC, and PLC (4 ligaments)

    KD V

    Multiligamentous injury with periarticular fracture


    Describe knee dislocation basd on direction


    • anterior
      • most common type of dislocation (30-50%)
      • due to hyperextension injury
      • usually involves tear of PCL
      • arterial injury is generally an intimal tear due to traction
    • posterior
      • 2nd most common type (25%)
      • due to axial load to flexed knee (dashboard injury)
      • highest rate of complete tear of¬†popliteal artery
    • lateral
      • 13% of knee dislocations
      • due to valgus force
      • usually involves tears of both ACL and PCL
      • highest rate of peroneal nerve injury
    • medial
      • varus force
      • usually disrupted PLC and PCL
      • rotational
    • posterolateral is most common rotational dislocation
      • usually irreducible
      • see with the dimple sign - button hole of medial femoral condyle through the medial capsule


    Indications for an HTO

    medial compartment arthrosis

    knee instability

    medial compartment overload following meniscectomy

    osteochondral lesions requiring resurfacing procedures 


    contraindications to HTO

    • General
      • inflammatory arthritis
      • obese patient BMI>35
      • flexion contracture >15 degrees
      • knee flexion
      • procedure will need >20 degrees of correction
      • patellofemoral arthritis
      • ligament instability
      • varus thrust during gait
    • Specific
      • narrow lateral compartment cartilage space with stress radiographs
      • loss of lateral meniscus
      • lateral tibial subluxation >1cm
      • medial compartment bone loss >2-3mm
      • varus deformity >10 degrees


    Compare lateral wedge and medial opening wedge HTO, what are other options


    • 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
      • ‚ÄčIf >20 deg of alignemnt required to avoid changing joint height
        • traumatic
        • blounts
      • above the tibial tubercle
    • Callus Distraction - TSF



    What are the uses for HTO in an unstable knee


    • Subacute ACL plus coronal malalignment (varus thrust) or sagittal malalignment (increased tibial slope)
      • HTO plus ACL reconstruction (one stage)

    • Chronic ACL with varus alignment
      • HTO or ACL reconstruction or both (according to age and activity level)

    • Chronic ACL plus medial compartment arthrosis or varus malalignment or varus thrust
      • HTO plus ACL reconstruction (one stage) or HTO only and, if residual instability, delayed ACL reconstruction (two stages)

    • Chronic posterolateral instability/laxity (PCL + PLC ¬Ī ACL) with symptomatic varus hyperextension thrust
      • HTO only but, if residual instability, delayed PCL reconstruction (two stages)¬†


    Complications of an HTO

    • Recurrence of deformity
      • 60% failure rate after 3 years when
        • failure to overcorrect
        • patients are overweight
    • Loss of posterior slope
    • Patella baja¬†
      • refers to a shortened patellar tendon which decreases the distance of the patellar tendon from the inferior joint line
        • can be caused by raising tibiofemoral joint line in opening wedge osteotomies
        • can be caused by¬†retropatellar scarring and tendon contracture
        • can cause bony impingement of patella on tibia
    • Compartment syndrome
    • Peroneal nerve palsy
      • more common in lateral opening wedge osteotomy
    • Malunion or nonunion


    Risk factors for stress fractures

    • Intrinsic factors
      • metabolic state
      • menstrual patterns
      • level of fitness
      • muscle endurance
      • anatomic alignment
      • microscopic bone structure
      • bone vascularity
    • Extrinsic factors
      • training regimen
      • dietary habits
      • equipment (eg, footwear, playing surface)


    Non-operative treament of stress fractures

    • Multi-disciplinary approach
      • Full work-up for nutrition, depression, metablic etc
    • Rest, immoblization
    • Replace deficient Vit D or Ca PRN
    • Bisophosphanates
    • Pulsile Teraperitide (Forteo)
      • Can't be used in patients at risk of cancer (risk of osteosarc)
    • Pulsed US
    • Extra-corpeal shock wave therapy


    High risk areas for stress fractures and associated treatment

    • Proximal tibia - dreaded black line
      • Non-operative treatment can return to sport 12 months later
      • IM nail doesn't heal fracture but helps return to sport
      • Anterior tension band can improve return to sport
        • Better biomechanics
        • Doesn't disrupt extensor mech
    • Naviular (due to blood supply and biomechanics)
      • Gold standard is non-op with NWB until it heals
        • Aggressive is necessary
      • Some elite athletes may opt for ORIF
    • Proximal 5th MT
      • NWB 6-8 weeks except elite athletes
    • Great toe sesamoids
      • Tibial is larger and more likely to develop stress fracture
        • Also more commonly bipartate
      • NWB followed by MT offloader
      • Can consider foot realignment surgery
      • Surgical options may be considered
        • Bone graft
        • ORIF
        • Excision with repair of FHB
    • Medial malleolus
      • NWB
      • ORIF if complete # line seen


    Options for imaging of stress fractures

    Initial XR will be normal (can repeat films later)
    MRI is best
    Bone scan also useful
    US can look for edema around the bone
    CT not as sensitive as MRI


    Prognostic factors associated with OCD


    • younger age is better
    • Better with no dissection
      • Clinical exam/XR is not good at predicting dissection
      • MRI - fluid behind lesion
    • Sclerosis on XR = poor response to drilling
    • >2 cm have a worse prognosis
    • Lesions in an atypical location have a worse prognosis
      • medial is better than lateral



    Indications for surgical treatment of pediatric OCD

    near growth completion
    severe symptoms and failed nonoperative managment
    Loose fragments

    Don't operative if physes open and asymptomatic


    Options for treament of a ACL with open growth plates

    • Extra-articular
      • IT band over the top
    • Transphyseal
    • Partial physeal
      • tibia or femur
      • less risk to tibia
    • All epiphyseal


    Risk factors to damage growth plate in pediatric ACL

    hardware across the physis

    large tunnels (‚Č•12 mm)

    lateral extra-articular tenodesis

    dissection in proximity to the perichondrial ring of LaCroix

    suturing near the tibial tubercle


    Transphyseal ACL.  How to reduce risk of growth arrest

    • verticle tunnels
    • small tunnels
    • good technique - no necrosis
    • no hardware in physis


    What is the true regarding the treatment of OCD of the knee (AAOS recommendations)

    • Stable lesions in a skeletally immature patient should not be treated surgically
    • Unstable lesions should be treated
      • reduce pain
      • reduce OA - this is only theoretical
    • Should be give PT
    • Nothing to show that OATS or ACI are any better than microfracture
      • microfracture should be first line of treatment
    • Outcomes of microfracture
      • Age
      • Duration of symptoms
      • Lesion size
      • Body mass index
      • Preoperative activity level >4 (Tegner)
      • Previous surgery (microfracture)
      • Repair cartilage volume >66%
        • MRI results of defect fill



    Appropriate imaging for PLC injury


    • 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



    Treatment of a PLC injury

    • Nonoperative¬†
      • Most Grade 1/2 injuries with mild instability can be treated non-op
      • Grade 2 are more controversial in the literature
      • immobilize knee in full extension for 2 ¬†weeks
      • Then NWB with hinged brace for 2-4 weeks
      • followed by progressive functional rehabilitation focusing on quad strengthening with¬†return to sports in 8-12 weeks
    • Repair vs recon is ongoing debate
      • Agreeable that either is better done early
      • PLC repair¬†- Acute injury
        • LCL injuries do not heal well and usually need to be reconstructed
        • may need to¬†augment PLC repair with¬†free graft
        • avulsion fx of fibular head can be treated with screws or suture anchors
      • PLC reconstruction
        • ‚ÄčFavoured method
        • still better to do it in
    • Full examination under anaesthesia
      • Determine ligaments that need to be repaired
      • Varus = LCL
      • just rotation = PFL (often chronically LCL is intact)
    • Diagnostic scope
    • trans-tibial double-bundle reconstruction (Laprode)
    • Consider HTO for realignment
    • postop
      • 4 weeks of postop cast controls leg ER better than knee brace
    • outcomes
      • operative treatment has improved outcomes compared to nonoperative treatment
      • repair has higher failure rate than reconstruction
      • improved outcomes with early treatment


    Describe the labprade technique for PLC reconstruction

    • 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
      • ‚Äčother 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)
      • ‚Äčtwo 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
    • postop
      • 4 weeks of postop cast controls leg ER better than knee brace


    Management of an acute knee dislocation

    • ATLS, rule out other injuries
    • assess neurovascular status
      • peroneal injury more common with posterolateral dislocation
      • ABI
      • otherwise monitor closely
  • Reduce urgently in emeg under sedation, splint and reassess vascular status
    • don't forget to check ligaments under anesthesia
    • dimpling sign = medial condyle buttonholed threw the medial capsule; unlikley to be able to reduce it closed
  • If there is a vascular injury
    • call vascular
    • take to OR and prep both legs for possible need for saphenous vein graft
    • Assessment under anesthesia
    • Ex-fix if they repair it
    • Repair the MCL and PLC and release the peroneal nerve if you need to
  • Timing of surgery
    • take of Ex-fix if you put one on after 2 weeks, then operate at 3 weeks
    • can do a scope
    • usually try to get ROM with PT, NWB, then reconstruction at 2-3 weeks
  • Diagnostic Scope
    • Assess cartilage
    • Debride vs repair meniscus
  • Dual hockey stick incisions have less necrosis than midline approach
  • Graft selection -¬†usually allograft
  • ACL and PCL repair (transtibial is safer for dislocated knee) ** Want to do this arthroscopically, but may not be able to with a severe MCL
    • PCL tibial tunnel - 4cm distal to joint, 2 cm medial to tubercle
      • 1.8mm guide wire
      • 1 cm below the joint line posteriorly 50 deg
    • ACL tibial tunnel
      • 2 cm proximal to PCL, 47 deg to exit at tibial footprint (anterior horn lateral meniscus)
    • Tunnels are drilled at 9mm and expanded to 11mm
    • ACL femoral tunnel - 6mm anterior to posterior cortex
      • 25-30mm, then dilated to 10mm
    • PCL femoral¬†tunnel (should be drilled arthroscopically as opposed to outside in)
      • 25-30mm, 10mm drill then dilated to 11mm
    • Pass the PCL and secure with interference screw or endobutton to femur
    • Pass the ACL and secure to femur
  • Repair the PLC or LCL in slight ER or valgus force
    • For Varus laxity and LCL tears
    • Lateral hockey stick between gerdy's and fibula, extending up to lateral epicondyle
    • Identify peroneal nerve proximally behind biceps, release anterior fascia bands
      • tag it if it's ruptured for plastics
    • Lag screw any boney avulsions
    • ‚ÄčLaprade reconstruction of PLC if repair wasn't possible
      • Drill tunnels in proxiaml fibula and tibia¬†
  • MCL (repaired in 30 deg of flexion) - if you haven't done it yet
    • Medial hockey stick, open sartorius
    • Repair intrasubstance tears with nonabsorbable suture
    • Repair insertional or capular tears with suture anchor
  • Fix the PCL in flexion
  • Fix the ACL in extension - don't cycle to load the grafts
  • 71

    Treatment of peroneal nerve injury associated with knee dislocation

    • Imaging
      • XR - look for associated avulsions that could indicate ligament injury or reduced dislocation
      • MRI
        • Can help to look at associated injuries, integrity of nerve or associated hematoma
      • U/S can help determine if nerve is intact and help assess hematoma
      • EMG
        • Baseline at 6 weeks
        • Repeat at 3 months for signs of improvement
    • poor results with acute, subacute, and delayed (>3 months) nerve exploration
    • Management
      • Involve peripheral nerve surgeon
      • Neurolysis and tendon transfers are mainstay of treatment
      • PT and AFO
      • Spontaneous recover is
      • Serial clinical exam with EMG
    • Neurolysis if there is an acute indication for ligamentous repair
    • Direct end to end repair
      • If there is no continuity, zone of injury is small
      • Best performed at 3-6 months, no later than 12 months
    • Intercalary nerve graft
      • If there is no clinical or electrical signs of improvement after 3 months (even if neurolysis was performed)
      • Usually 4 cm, longer than 6 cm has poor outcomes
      • Sural nerve most commonly used
      • Neuroma, hematoma, wound complications
    • Vascularized sural nerve graft if >13cm, less than 6 months
      • Can use allograft, results are poor with high risk of infection
    • PTT transfer is the gold standard for CPN injury with associated equinovarus
      • Can be done in conjunction with nerve transfer
      • Improved ROM compared to AFO alone when done early


    Physical exam for meniscal tears

    • Look - effusion, quads atrophy
    • Look at alignment of knee
    • Feel - joint line tenderness
    • In the context of ACL tears can be confounded by bone bruising and ligamentous injury
    • Palpate for cysts
    • Move - evaluate for locked knee
    • Assess stability of all ligaments
    • McMurray's test
      • Flex the knee and place a hand on medial side of knee, externally rotate the leg and bring the knee into extension.
      • A palpable pop or click is a positive test and can correlate with a medial meniscus tear.
    • Apley grid test
      • Done in prone, push down on a flex knee and rotate to grind the meniscus
    • Squat test
    • Thessaly test
      • Standing on one leg, rotate the knee to grind the meniscus


    Indications for meniscal repair

    • peripheral in the red-red/white region
      • rim width is the distance from the tear to the peripheral meniscocapsular junction (blood supply).
      • rim width correlates with the ability of a meniscal repair to heal (lower rim width has better blood supply)
    • vertical and longitudinal tear
    • 1-4 cm in length
    • acute repair combined with ACL reconstruction
    • Displaceable tear
    • Active patient


    Options for technique for meniscal repair

    • Always assess alignment and stability of the knee pre-op
    • inside-out technique (gold standard)
      • medial approach to capsule
        • expose capsule by incising the sartorius fascia, retracting the pes tendons and semimembranosus posteriorly, and developing the plane between the medial gastrocnemius and capsule.
        • The saphenous nerve travels out of the adductor canal to the anteromedial portion of the knee, it is anterior to semiT with the knee in extension, and runs just superifical to the sartorius fascia
          • Place the knee at 90 deg to bring nerve posterior
        • Place knee at 20 deg for fixation; sutures placed 3mm apart, vertical mattresses
          • Don't forget to rasp to prepare the bed
      • lateral approach to capsule
        • expose capsule by developing plane between the the iliotibial band and biceps tendon interval, then retract lateral head of gastrocnemius posteriorly.
        • Place knee at 90 for repair
    • all-inside technique (suture devices with plastic or bioabsorbale anchors)
      • most common
      • many complications (breaking, chondral injury)
      • Meniscal Cinch (Arthrex)
      • Meniscal Viper
      • Arrow
    • outside-in repair (useful for anterior horn tears)
    • open repair uncommon except in trauma, knee dislocations
      • vertical mattress sutures are strongest because they capture circumferential fibers
      • 2-3mm apart
      • healing is enhanced by rasping
    • risks
      • saphenous nerve and vein (medial approach)
      • peroneal nerve (lateral approach)
      • popliteal vessels
    • Post-op
      • 6 weeks
        • Zimmer with WBAT or PWB no zimmer
        • Restricted to 90 deg of motion
      • 4 months
        • No deep sqats for rehab


    Indications for meniscal transplantation

    • Almost total meniscectomy
    • Under 55 with persistant pain
    • Patients who are asymptomatic is controversial
    • Stable, well aligned knee
    • minimal OA
    • Low BMI (not mentioned always)


    technique for meniscal transplant

    • 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
    • Rehab
      • Begin when swelling is down
      • Back to work in 2 weeks
      • 2-3 months before full activity


    Indications and techniques to fix a mensical root tear

    • >3mm excursion of the posterior horn of the meniscus = root tear
    • Associated with OA
    • Should be fixed to prevent OA
      • Active patient
      • Outerbridge
      • Normal alignment
    • Options for fixation
      • Transtibial pullout
        • 5mm tunnel
        • Cortical button
      • Suture anchor
        • Posteromedial portal
    • Post-op
      • PWB in zimmer
      • Progress WB at 8 weeks