The meniscus is a fibrocartilaginous structure made of predominantly Type one collagen. It optimises force transmission acting as a shock absorber in the knee, ultimately protecting the underlying cartilage.
The medial meniscus also acts as a secondary stabiliser of anterior knee translation. The outer third of the meniscus has a blood supply and is termed the ‘red zone’. Tears there have the most favourable prognosis post repair.
The clinical signs of a meniscal tear are usually a small effusion in an acute tear, joint line tenderness, and a positive MacMurray test. Knee hyperflexion usually reproduces patient symptoms.
Indications for meniscal repair
Traumatic meniscal tears in young active patients, as meniscus preservation, gives longer term cartilage protection.
Locked knee, due to a bucket handle tear of the meniscus, is considered an orthopaedic emergency. Vertical longitudinal tears in the peripheral zones of the meniscus are more likely to heal due to proximity to the meniscal blood supply.
Combined ACL injury with meniscal tears – meniscal repair protects the knee from further instability and degeneration in combination with ACL reconstruction.
Complete radial tears reaching the periphery of the meniscus should be repaired to restore ring continuity.
Lateral meniscal root tears are usually traumatic and associated with ACL tears. Trans-osseous repair of the root maintains hoop stresses in the meniscus preventing extrusion, offering some protection from degeneration.
Managing degenerative meniscal tear management in the middle aged to elderly is controversial. Evidence suggests arthroscopic debridement and non-operative treatment have similar outcomes.
Use simple analgesics and NSAIDS first, followed by a steroid injection at least six weeks after onset of symptoms. Weight bearing AP radiographs and patella skyline views should be routine to exclude significant osteoarthritis. If, after three months, the patient still complains of mechanical symptoms (e.g. clicking, catching or locking) then specialist referral and MRI can be performed for consideration of arthroscopic debridement.
Medial root tears are often degenerative. Attempt repair if less than grade one or two chondromalacia but the prognosis is generally poor. If grade three or four chondromalacia, then it’s worth trying intra-articular steroid injection and watching for six weeks. Consider arthroscopic debridement if symptomatic after that. Can ultimately lead to total knee replacement.
Rehabilitation after meniscal repair usually allows full weight bearing with a hinged knee brace and 0-90-degree range of motion for six weeks. Flexion past 90 degrees increases stresses at the repair site and can lead to failure.
If a root repair is performed, patients weight bear in extension for two weeks followed by four weeks at 0-90 degrees of flexion. Following meniscectomy, early weight bearing and full movement is encouraged, usually without crutches.
- In traumatic tears, consider meniscal preservation rather than resection.
- In degenerative tears use conservative treatment first with surgery reserved for those who don’t respond
- There is no indication for meniscectomy in the setting of advanced OA
References available on request.
Questions? Contact the editor.
Author competing interests: the author works for a group providing imaging.
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