· primary medial stabiliser is MCL
· primary medial stabiliser at 30o flexion
· secondary medial stabiliser in extension
· secondary medial stabilisers are
· ACL
· medial capsule with deep medial ligament
· posterior oblique ligament
· tertiary medial stabiliser is PCL
· MCL usually tears at femoral end
· stiffness more likely at femoral end
· laxity more likely at tibial end
· most common with combined MCL and LCL injury
· lateral meniscus more commonly injured (3:1)
· tested in extension and in 30o flexion
· I+ laxity in flexion
· indicates mild sprain of MCL (up to 1/3 torn)
· usually no laxity in extension
· 2+ laxity in flexion
· indicates moderate sprain of MCL (1/3 to 2/3 torn)
· usually no laxity in extension
· 3+ laxity in flexion
· indicates complete disruption of MCL
· usually laxity in extension
· indicates disruption of secondary restraints
· ACL laxity demonstrated by positive Lachmann’s test
· posterior oblique ligament instability demonstrated by positive anterior drawer in external rotation
· PCL laxity demonstrated by positive posterior sag
· direct blow to lateral knee or twisting injury
· feeling of ripping
· swelling usually delayed
· extra-articular
· discreet tenderness at femoral or tibial insertion of MCL
· laxity as above
· pain on stressing with Grade 1 and 2 injuries
· usually normal in acute injury
· may be calcification of femoral insertion of MCL
· Pellegrini-Stieda lesion
· stress films may be useful
· MRI usually not required
· nonoperative treatment
· see after injury and treat as below
· reassess at 2 wks for
· locked meniscal tear
· ACL injury
· arthroscopy indicated for meniscal tear
· unlock meniscus
· if no ACL injury, suture meniscus
· if ACL injury, do not suture at time
· return at 6-12 wks for meniscal suture and ACL reconstruction
· control pain and inflammation
· analgesics
· ice and elevation
· splint only in first few days if required
· weight-bearing
· as tolerated
· often need crutches early
· range-of-movement exercises
· started early
· aim to regain full flexion and extension
· muscle-strengthening exercises
· started once full ROM achieved
· quadriceps and hamstring strengthening
· resumption of activities
· once strengthening progressed
· as above plus brace for 2-4 wks
· use knee immobiliser brace to
· protect against valgus stress
· prevent full extension
· regimen is
· 15o - 90o for 2 weeks
· 0o - 90o for 2 weeks if still painful
· as above except
· brace for 4-6 wks
· add 30o to 60o for 2 weeks initially
· prevention of extension addresses injury to posterior oblique ligament
· treat MCL injury nonoperatively as above
· will reliably heal
· delayed ACL injury if indicated
· delay decreases postoperative complications
· meniscus should be preserved if possible
· immediate intervention not required
Locked knee
· only indication for immediate intervention is locked knee
· usually noted at early (2 week) reassessment
· early arthroscopy should be performed
· if ACL intact, meniscus should be sutured at the time if possible
· if ACL ruptured, meniscus should be reduced only
· should return at 12 wks for meniscal suture and ACL reconstruction
Features of tear
· arthroscopy should be performed if symptoms and signs of meniscal injury
· should be delayed until patient has recovered from MCL injury
· tears should be sutured if possible
· should be combined with ACL reconstruction if ACL ruptured
ACL reconstruction
· tear may be found at time of reconstruction
· should be sutured if possible
· primary lateral stabiliser is LCL
· primary lateral stabiliser at 30o flexion
· secondary lateral stabiliser in extension
· secondary lateral stabilisers are
· ITB
· popliteus and arcuate ligament
· ACL
· tertiary medial stabiliser is PCL
· tested in extension and in 30o flexion
· somewhat theoretical because practically impossible to tear LCL in isolation
· usually associated posterolateral corner injury
· I+ laxity in flexion
· indicates mild sprain of LCL (up to 1/3 torn)
· usually no laxity in extension
· 2+ laxity in flexion
· indicates moderate sprain of LCL (1/3 to 2/3 torn)
· usually no laxity in extension
· 3+ laxity in flexion
· indicates complete disruption of LCL
· usually laxity in extension
· indicates disruption of secondary restraints
· ACL laxity demonstrated by positive Lachmann’s test
· posterolateral corner instability demonstrated by positive anterior drawer in internal rotation
· other tests for posterolateral corner instability
· varus knee
· hyperextension and external rotation of tibia when feet lifted by toes
· increased external rotation of foot with knee at 90o
· twisting injury or direct blow to medial side of knee
· often hyperextension injury
· feeling of ripping
· swelling usually delayed
· extra-articular
· discreet tenderness on lateral side of knee
· laxity as above
· pain on stressing with Grade 1 and 2 injuries
· may be dysfunction of peroneal nerve
· usually normal
· may be bony avulsion of head of fibula or Gerdy’s tubercle
· stress films may be useful
· nonoperative treatment for LCL
· as for Grade 1 MCL
Early
· some evidence to suggest early repair beneficial
· if diagnosis in doubt
· EUA and arthroscopy
· repair of posterolateral corner
· reattachment with drillholes through tibia
· brace and rehabilitation
Late
· may repair posterolateral structures at time of ACL reconstruction
· if externally rotates > 15o
· LCL and arcuate ligament identified and bone block from femur raised and advanced proximally with knee in internal rotation
· if knee in varus with lateral thrust in stance phase, valgus proximal tibial osteotomy required