Meniscal Repair - All-Inside and Inside-Out Techniques

Indication. A symptomatic, repairable meniscal tear in a patient who will comply with a protected 4-6 month rehabilitation — most often a vertical-longitudinal or bucket-handle tear in the vascular periphery of a young, active knee. The final decision is made intra-operatively at arthroscopy, because tissue quality and reducibility cannot be assessed on MRI alone. Repair versus meniscectomy. Repair preserves the meniscus and protects the joint: meniscectomy increases OA risk 5-10 times at 10-20 years (tibiofemoral contact pressure rises more than 50% medially and more than 200% laterally). The trade-off is a longer, restricted rehabilitation and a 10-20% failure risk — but a failed repair can still be converted to meniscectomy with outcomes similar to a primary meniscectomy, so attempting repair does not burn a bridge. What makes a tear repairable — assess four factors:

Technique choice — all-inside versus inside-out. All-inside is the default for most tears; inside-out is reserved for the far posterior horn and revision:

Contraindications. Absolute: white-white zone, degenerative complex tear, an unreducible tear, active infection. Relative: age greater than 50 with low demand, a chronic tear beyond 12 months with poor tissue, a radial mid-substance tear, a previous failed repair, or a patient unable to comply with the extended rehabilitation. Consent specifically for a 10-20% failure rate (which may need later meniscectomy), saphenous nerve injury in 1-5% with inside-out (permanent numbness), implant irritation in 2-5% with all-inside, infection, stiffness, and the 4-6 month protected rehabilitation. Setup. Supine with a lateral post or thigh-high leg holder so the knee can be flexed over the table edge for valgus or varus stress. General or regional anaesthesia, thigh tourniquet, prophylactic antibiotic. Establish the standard anterolateral viewing and anteromedial working portals.

The goal is to preserve the meniscus by apposing vascular, abraded tear edges under stable fixation — choosing all-inside for most tears and inside-out only when access demands it. The exposure is the arthroscopic portal setup (and, for inside-out, the posteromedial safety incision), laid out as the first steps below.

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Rehabilitation | Phase | Timing | Protection | Therapy | |-------|--------|------------|---------| | 1 | 0-2 weeks | WBAT with crutches; brace 0-90 degrees if a large posterior-horn tear | Quad sets, ankle pumps, SLR, prone hangs for full extension | | 2 | 2-6 weeks | Full weight-bearing; continue restriction if posterior-horn tear | Stationary cycling, closed-chain 0-60 degrees, pool work | | 3 | 6-12 weeks | No brace; full ROM restored | Single-leg work, proprioception, light sport-specific drills | | 4 | 3-6 months | Avoid deep flexion, squatting and pivoting until 4-6 months | Running at 3-4 months, agility, return-to-sport testing | Weight-bearing is allowed as tolerated from the start (meniscal stress comes mainly from flexion, not axial loading) and is full by about 2 weeks. ROM is individualised — traditional protocols restrict a large posterior-horn tear to 0-90 degrees for 4-6 weeks on biomechanical grounds, while modern unrestricted protocols report equivalent healing in RCTs. All patients avoid deep flexion, squatting and pivoting until 4-6 months. Most return to non-contact sport from 4 months and to full sport by 4-6 months (versus 6-12 weeks for meniscectomy), provided strength and hop testing are greater than 85% of the other side and there is no effusion. Overall 10-20% of repairs fail, most within the first year; a failed repair can still be managed with meniscectomy with outcomes similar to a primary meniscectomy, so attempting repair does not burn a bridge. Complications

Epidemiology and why repair matters. Meniscal injury is among the commonest knee problems in active adults, and meniscal preservation is now first-line whenever a tear is repairable — the 2019 ESSKA consensus states that long-term clinical and radiological outcomes are worse after partial meniscectomy than after repair. The meniscus transmits 50-70% of the knee's contact load; removing it raises tibiofemoral contact pressure by more than 50% medially and more than 200% laterally, driving a 5-10 fold increase in OA at 10-20 years. Lateral meniscectomy is biomechanically worse than medial. Vascularity and the vascular zones. Only the vascular periphery of the meniscus reliably heals. Arnoczky and Warren mapped a perimeniscal capillary plexus (from the medial, lateral and middle genicular arteries) that penetrates only the peripheral 10-25% of the meniscus — the anatomic basis for the zones — and identified the popliteal hiatus as a relatively avascular watershed. This is the classification that drives repair selection:

Tear patterns and healing biology. Vertical-longitudinal and bucket-handle tears (aligned with the circumferential collagen) heal best (80-90%); radial mid-substance and complex degenerative tears (perpendicular to collagen, or macerated) do not (less than 40%) and are managed by meniscectomy. Healing unfolds over 3-6 months — an inflammatory phase (0-4 weeks), a proliferative phase (4-12 weeks) and a remodelling phase (3-6 months), with full maturation by 6-12 months; a repaired meniscus regains about 60-80% of native strength by 6 months. Most failures (70-80%) occur within the first year. The ACL effect. Concurrent ACL reconstruction is the single strongest predictor of healing, lifting rates from 60-70% isolated to 80-90%. Blood and growth factors (BMPs, TGF-beta, PDGF) released from femoral and tibial tunnel drilling reach the tear via haemarthrosis and synovial circulation. About 40-50% of ACL injuries have an associated meniscal tear (the medial posterior horn is commonest), which is why both menisci are examined at every ACL reconstruction. Key evidence. The 2019 ESSKA consensus frames meniscal management around preservation and does not support routine biologic augmentation. Grant's systematic review of isolated tears found equivalent clinical failure (17% inside-out versus 19% all-inside), with nerve irritation far higher inside-out (9% versus 2%). The MOON 6-year cohort (Westermann) reported a 14% failure rate for repair-with-ACL with sustained function. Nepple's meta-analysis set realistic long-term expectations — about one in four repairs fails by 5 years, but most endure, and the failure rate was similar across medial and lateral and ACL-intact versus ACL-reconstructed subgroups. Arnoczky and Warren's foundational cadaver study mapped the perimeniscal capillary plexus to the peripheral 10-25%, the anatomic basis for the vascular zones.