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British Medical Books Health Issues Computerized Tomography

Current recommendations

  • athletically active = non-operative RX of MCL + delayed repair of ACL
  • best results = non-op. Rx of MCL + delayed repair of ACL with autogenous central 1/3 patella tendon

    aim of treatment

    • stable knee
    • fully functional joint
    • minimal post-op stiffness
    • minimal laxity of MCL

Anatomy of ACL

  • from postero-medial aspect of lateral femoral condyle to tibial plateau anteriorly in interspinous area
  • 38 mm long, 1 cm wide
  • nerve supply from tibial N

Function

  • restrain anterior displacement of tibia - primary
  • 2° restraint to varus & valgus movement

Diagnosis of injury

  • result of direct contact (usually) or non-contact situations

ACL injury


History

  • deceleration + ER or abD
  • feels pop - aware that injury is serious
  • felt knee shift, swelling within 1-2 hours (haemarthros)
    • if no swelling -> capsule ruptured
  • able to continue playing

Examination

  • swelling
  • tenderness
  • instability - may need MUA
  • local soft tissue injury

Tests

Lachman

  • accurate for unilateral anterior or posterior instability

anterior drawer test

  • with foot ER - for antero-medial instability
  • with foot IR - antero-lateral

pivot shift test (MacIntosh)

  • antero-lateral instability
  • knee extended, valgus stress, foot IR -> tibia subluxes anteriorly in extension
  • slowly flex knee -> tibia (lateral plateau) subluxed forward until 20-40° flexion when ITB slips over lateral femoral condyle & reduces tibia

MCL injury

  • MCL = primary medial stabilizer with knee in 30° of flexion
    • therefore must test in 30° of flexion
    • compare with normal knee
  • with knee extended - stability from posterior capsule, ACL, PCL, posterior oblique ligaments
  • diagnosed & graded by clinical examination
  • site of tenderness usually = site of tear
  • ligamentous injuries -> clinical diagnosis
  • MRI -> for MCL or PCL (extra-articular)
  • scope best to confirm ACL injury, MRI 60-90%

Diff.Dg.

  • osteo-chondral #s
  • dislocated patella
  • peripheral meniscal tear

grading

  • depends on laxity & end point with valgus stress

uniplanar instability

  • anterior
  • posterior
  • medial
  • lateral
    • grade 0 = no laxity, firm end point
    • grade 1+ = some (< 0.5 cm) laxity & firm end point
    • grade 2+ = > 1 cm opening with endpoint
    • grade 3+ = complete disruption & no detectable end point
  • a large effusion implies intact capsule
  • large effusion not often seen with grade 3 injuries

associated meniscal injuries

  • O’Donoghue’s triad = MCL + ACL + medial meniscus injury
    • rare in athletic patients
  • lateral meniscus injury more common with a grade II MCL + ACL injury
  • grade III MCL + ACL injury - rarely has other intra-articular injuries
    • mechanism: distraction rather than compressive
  • lateral meniscal tears - usually middle 1/3 radial or posterior 1/3 peripheral tears
  • medial meniscal injuries are usually posterior 1/3 peripheral tears
  • meniscal tears treated at the time of ACL repair
  • repair rather than excision possible

ACL injuries & treatment

  • dg. made on arthroscopic examination

    Partial tear

    • non-operative if < 50% diameter
    • rehabilitation
    • high risk of complete tear
    • if surgery indicated → reconstruct

    Complete isolated ACL tear

    Complete isolated ACL tear

    • if small fragment or in-substance tear → reconstruction

    Complete tear with meniscus injury

    • repair meniscus at time of reconstruction

    Complete ACL tear with collateral lig. injuries

    • conservative Rx. for collateral ligaments
    • ACL reconstruction after full rehab

    Dislocated knee

    • repair all

Treatment of the MCL & timing of ACL repair

  • 2 most important changes in management
    • non-op Rx of MCL
    • delayed surgical Rx of ACL
  • based on 3 factors:
    • meniscus can be Rx at time of ACL repair
    • non-op Rx of MCL successful & predictable - regardless of grade of tear
    • < post-op. complications at reconstruction of ACL (arthrofibrosis) is delayed, if ROM is restored, < inflammation
  • results with this protocol -> stable knee with good function
  • repair of MCL not necessary in these combined injuries
  • repair of MCL + ACL results in more stiffness than ACL repair only
    • no benefit in surgery of MCL alone or in combination with an ACL injury
    • torn MCL heal well provided no further episodes of giving way allowed before ACL reconstructed

Rehabilitation

    Stage 1

    • pain relief

    Stage 2

    • ROM exercises

    Stage 3

    • muscle strengthening
  • Rx of isolated ACL + combined injuries is the same
  • delay reconstruction for 4 to 8 weeks or until
    • pain & inflammation has subsided
    • swelling subsided
    • ROM fully restored - including full hyperextension & normal gait
    • MCL has healed
    • quadriceps strength approximately equal on both sides

    aims of Rx in combined injuries (grade II MCL)

    • ROM, decrease swelling
    • protect knee with PWB, crutches & brace
    • physio

    combined injuries with grade III MCL injuries

    • same but more protection of the knee

    location of MCL tear important

    proximal (femur) or mid-substance

    • no laxity, but risk of stiffness
    • immobilization for 1-2 weeks & then restore ROM in hinged brace

    tibial tears

    • tendency to valgus laxity
    • 2-4 weeks immobilization in hinged brace fixed at 30° flexion, then ROM physio

treatment of ACL

  • surgery to MCL leads to high incidence of arthrofibrosis
  • reconstruction of ACL depends on:
    • level of activity
    • “unfixable”
    • pre-op. rehabilitation

athletically active & those with high demands

  • repair of ACL after full rehabilitation
  • if full rehab › 8 weeks, continue with rehab before surgery

low demand

  • non-op Rx & ROM rehabilitation
  • danger of an unstable knee -> meniscal injury

children

  • conservative Rx - good results in 60% only
  • surgical Rx indicated

reconstruction of ACL

  • best with bone-patella tendon-bone autograft
  • other options
    • semi-tendinosus/gracilis graft
    • bone- PT-bone allograft
    • prosthetic ligaments (Gortex, Dacron)

technique

  • harvesting graft
  • preparation of graft
  • notchplasty
  • drilling tibial tunnel & femur
  • passing & fixing graft
  • check for impingement

complications

  • RSD
  • infection
  • chr. effusion
  • loss of fixation
  • patella # or tendon rupture

allografts

  • small risk of HIV etc.
  • laxity & late failure

prosthetic grafts

  • inferior outcome

ACL injuries in children

Incidence

  • very uncommon injury in children with open physis
  • occurs much less commonly in children than adults (~1.5% of all ACL ruptures)
  • distal femoral & proximal tibial physeal fractures commonly associated with ACL injuries
  • Increasing incidence related to increased participation in vigorous sports, increased incidence of multiple trauma, increased awareness among physicians

Anatomy

  • ligaments are stronger than physis
  • in children, collagen fibers of ACL are continuous with perichondrium of epiphyseal cartilage
  • in adults, ligament inserts directly into bone by way of Sharpey’s fibers
  • ligamentous laxity may offer some protection to children (decreases as approach skeletal maturity)
  • physeal fractures/anterior tibial spine avulsions more common than ACL injury

Mechanism

  • hyperextension, direct blow, sudden twisting in open field
  • in younger children, injury associated with multi-trauma (5/9 struck by motor vehicle)
  • as with tibial eminence fracture, bicycle accidents are relatively common cause
  • adolescents are more likely to sustain during contact sports or sports where cutting maneuvers while running

Physical Examination

  • effusion
  • diffuse tenderness
  • decreased ROM
  • anterior drawer, Lachman, pivot shift
  • instrumented knee laxity testing (kt-1000) - compare to other side because degree of inherent laxity

Imaging

X-ray

  • look for physeal fracture; osteochondral fracture; hypoplastic intercondylar notch and small tibial spine - congenital absence of cruciate ligaments

MRI

  • 97% accurate compared to arthroscopy in diagnosing ACL tears (ages 14-69, average age 33)
  • less accurate in diagnosing tears in children

Conservative Treatment

  • no better in children than adults
    • Kannus, et al : 8 year f/u. Children with complete ACL tears had poor results with chronic instability, continuous symptoms, post-traumatic osteoarthritis
    • McCarroll and Shelbourne : 40 patients less than 14 years. old with midsubstance tears. Most patients that were treated conservatively (bracing, rehab, activity modification) were unable to return to sports. All experienced recurrent episodes of giving way, effusions, pain.

Operative Treatment

    Why operate?

    • high incidence of meniscal injury in ACL-deficient knee
    • protect repaired meniscus
    • prevent Degenerative Joint Disease

Repair does not work

Concern about reconstruction is injury to growth plate & resultant growth arrest

intraarticular vs. extraarticular procedure

  • greater potential risk of growth arrest with intraarticular so some prefer extraarticular in younger patients

    good results with early reconstruction

    • McCarroll and Shelbourne
    • Lipscomb and Anderson
    • Parker and Drez