Meniscus Repair vs Meniscectomy

The decision between meniscal repair and meniscectomy is one of the most consequential in knee surgery. The menisci — C-shaped fibrocartilaginous structures composed predominantly of type I collagen — perform critical biomechanical functions in the knee: load transmission (transmitting 50–70% of the load in the medial compartment and 70–85% in the lateral compartment), shock absorption, joint stability, proprioception, and joint lubrication. Loss of meniscal tissue — whether from injury or surgical excision — predictably accelerates articular cartilage degeneration and osteoarthritis. The principle of `meniscal preservation` (repair where possible, excision of the minimum necessary tissue) has become the dominant paradigm in contemporary knee surgery.

• Meniscal vascular supply — the basis for repair vs excision decisions: the peripheral meniscal blood supply (from the geniculate arteries via the perimeniscal capillary plexus) supplies the outer 25–30% of the meniscus — the `red-red zone`; the inner 75% is avascular, receiving nutrition by diffusion from synovial fluid — the `white-white zone`; the junction between vascularised and avascular zones is the `red-white zone`; tears in the red-red and red-white zones have the potential to heal after repair (blood supply supports healing); tears in the white-white zone have no healing potential and cannot be reliably repaired — partial meniscectomy (excision of the unstable fragment) is the standard treatment for irreparable tears
• Biomechanical consequences of meniscectomy: total meniscectomy increases peak tibiofemoral contact stress by 2–3× (Fairbank changes — joint space narrowing, osteophyte formation, tibial plateau flattening); partial meniscectomy increases contact stress proportional to the amount of tissue removed; even 10% of meniscal tissue loss measurably increases contact pressure; total medial meniscectomy increases medial compartment contact stress by approximately 40%; total lateral meniscectomy increases lateral compartment contact stress by approximately 300–500% (the lateral meniscus carries a greater proportion of the lateral compartment load — more devastating consequences from lateral meniscectomy than medial)

• Ideal repair candidates: acute tear (<6–8 weeks — before degeneration and retraction of the tear edges); peripheral tear in the red-red or red-white zone (<5 mm from the meniscocapsular junction); vertical longitudinal tear >10 mm in length (smaller tears may heal without repair); tear that is reducible and stable (bucket-handle tears must be reduced back to their anatomical position before repair); young patient (<40 years — better healing biology); concurrent ACL reconstruction is the strongest positive predictor of meniscal repair success — the haemarthrosis from ACL reconstruction stimulates healing by bathing the repair site in growth factors; ACL-deficient knee with irreparable meniscus should have the ACL reconstructed to protect the remaining meniscus
• Factors favouring meniscectomy: chronic degenerative tear (horizontal/cleavage tear in middle-aged/elderly patients); white-white zone tear (avascular — no healing potential); irreparable complex tear; stable small (<10 mm) peripheral tears that may heal spontaneously (can be left alone without any procedure — `meniscal abrasion` to stimulate healing); patient with established OA and degenerative tear (meniscectomy has very limited benefit in this group — the landmark METEOR and FINISH trials showed no benefit of arthroscopic meniscectomy over physiotherapy for degenerative meniscal tears in middle-aged patients with OA)
• The METEOR trial (Katz et al., NEJM 2013) and FINISH trial (Sihvonen et al., NEJM 2013): two landmark RCTs that fundamentally changed the management of degenerative meniscal tears; METEOR compared arthroscopic partial meniscectomy vs physical therapy for meniscal tears and mild-to-moderate OA in patients >45 years — no significant difference in function at 6–12 months; FINISH compared arthroscopic partial meniscectomy vs sham surgery (skin incision only) for degenerative meniscal tears in patients without OA — no significant difference in outcomes; these trials established that arthroscopic partial meniscectomy for degenerative meniscal tears in middle-aged patients provides no meaningful benefit over conservative management or sham surgery; current NICE guidelines and BASK guidance recommend against routine arthroscopic partial meniscectomy for degenerative meniscal tears in patients with OA features

• Inside-out repair: sutures are passed from inside the knee joint outward through the meniscus and retrieved through a posterior incision; the gold standard technique providing superior suture control and pull-out strength; requires a posterior incision (medial or lateral) to retrieve sutures — neurovascular risks (saphenous nerve medially; common peroneal nerve laterally); vertical mattress sutures placed every 3–5 mm along the tear; most widely used for peripheral tears
• Outside-in repair: sutures are passed from outside the knee inward through cannulae and retrieved arthroscopically; used for anterior horn tears where inside-out access is difficult; technically simpler for anterior tears but less anatomical for posterior horn repairs
• All-inside repair (meniscal repair devices): proprietary implant-based systems (Fast-Fix, RapidLoc, Meniscal Cinch); a preloaded anchor with attached suture is deployed through an arthroscopic cannula; no separate posterior incision required; technically simpler; suitable for posterior horn tears; devices include a suture passed through the meniscal tear and anchors on both sides with a self-tensioning slip knot; risk of device-related complications (chondral abrasion from prominent implant); the simplest and most widely used modern technique
• Trephination and rasping: the tear edges are abraded (rasped) and the perimeniscal synovium is trephinated (perforated with a needle or awl) to create a vascular channel between the peripheral vascularity and the repair site; promotes fibrovascular ingrowth and enhances healing at the repair site; performed before suture placement at all repair sites

• Meniscal repair success rates: overall clinical success rates 70–85%; peripheral red-red zone tears in young patients with concurrent ACL reconstruction have the highest success rates (~85–90%); avascular zone repairs have lower success (40–60%); re-tear rates 15–25%; a failed repair requiring partial meniscectomy still produces better outcomes than primary meniscectomy in most studies — `repair first` approach justified even with moderate risk of failure; MRI is unreliable for assessing repair healing (high signal on MRI does not necessarily mean failure — `ligamentisation` process produces signal changes in healed repairs)
• Long-term consequences of meniscectomy: Fairbank (1948) originally described the radiographic changes seen after total meniscectomy — ridging of the femoral condyle, flattening of the femoral articular surface, and joint space narrowing; modern long-term follow-up studies (10–20 years) confirm that partial meniscectomy significantly increases the risk of medial and lateral compartment OA compared to intact meniscus; the amount of meniscus removed correlates directly with OA progression rate; total meniscectomy results in OA changes in virtually all patients by 20 years
• Meniscal allograft transplantation (MAT): for patients who have undergone total or near-total meniscectomy and develop pain in the affected compartment before established OA (<Outerbridge Grade IV chondral change); the allograft is sized to match the tibial plateau dimensions; attached using bone plugs or a bone trough technique; indicated in young patients (<50 years) with symptomatic compartment pain, minimal OA, and previous meniscectomy; MAT delays or prevents progression to compartment OA and avoids or delays TKA

• Meniscal zones: red-red (outer 25–30%, vascularised) → repair possible; red-white (junction) → repair possible; white-white (inner, avascular) → excision only; blood supply from perimeniscal capillary plexus via geniculate arteries
• Biomechanics: medial meniscus transmits 50–70% of medial compartment load; lateral transmits 70–85% of lateral compartment load; lateral meniscectomy more devastating (300–500% contact stress increase vs 40% for medial total meniscectomy)
• Ideal repair: acute (<6–8 weeks); peripheral red-red or red-white zone; vertical longitudinal tear >10 mm; reducible; young patient (<40); concurrent ACL reconstruction (strongest positive predictor of repair healing)
• Bucket-handle tear: displaced vertical longitudinal; medial > lateral; knee locking/inability to extend; double PCL sign on MRI; reduce first then repair urgently
• Root tear: posterior medial most common; functional meniscectomy (hoop stress lost + meniscal extrusion); middle-aged women; transtibial pull-through repair; prevents rapid OA progression
• METEOR trial (NEJM 2013): meniscectomy = physiotherapy for degenerative tears with mild-to-moderate OA ≥45 years; FINISH trial (NEJM 2013): meniscectomy = sham surgery for degenerative tears without OA; arthroscopic partial meniscectomy NOT recommended for degenerative tears in patients with OA features
• Inside-out repair: gold standard; vertical mattress sutures; posterior incision required (saphenous nerve risk medially, peroneal nerve laterally); best for posterior horn tears
• All-inside devices (Fast-Fix etc.): no posterior incision; all arthroscopic; posterior horn; risk of chondral abrasion from device prominence; most widely used modern technique
• Repair success: 70–85% clinical success; 85–90% for peripheral tears + concurrent ACL reconstruction; 15–25% re-tear rate; `repair first` — failed repair → meniscectomy still better than primary meniscectomy in most studies
• MAT: total/near-total meniscectomy + symptomatic compartment pain + age <50 + minimal OA (<Outerbridge IV); bone plug or trough technique; delays/prevents OA and TKA