Medial Approach to the Knee (Collateral Ligament and Meniscus)

What it exposes. The medial approach to the knee gives direct, layered access to the medial collateral ligament complex (superficial and deep MCL), the posteromedial corner with the posterior oblique ligament, and the medial meniscus, with safe control of the saphenous nerve and the popliteal neurovascular bundle. It is the workhorse exposure for medial-sided ligament reconstruction, posteromedial corner repair and open medial meniscal work. Primary indications: - Acute and chronic medial collateral ligament injury requiring repair (femoral or tibial avulsion) or reconstruction

• Posteromedial corner injury with anteromedial rotatory instability, often in combined ACL and medial-sided injuries
• Medial meniscal repair using an open inside-out technique, and open medial meniscectomy when arthroscopic access is inadequate
• Open medial retinacular and medial patellofemoral ligament repair or reconstruction for patellar instability (related procedure: MPFL reconstruction)
• Open reduction and internal fixation of medial femoral condyle and medial tibial plateau fractures
• Removal of medial joint loose bodies, drainage of septic arthritis, and excision of a symptomatic semimembranosus bursa Clinical decision-making - when this approach is needed. The medial collateral ligament complex, the posteromedial corner and the medial meniscus are not reliably reached through a purely anterior arthroscopic setup. Test valgus laxity at thirty degrees of flexion to isolate the MCL complex (sMCL and POL), and at full extension to assess the posterior oblique ligament and posteromedial corner - laxity in extension signals a more severe posteromedial injury. Most isolated grade I and II MCL injuries heal non-operatively in a hinged brace; operate for a bony avulsion, a grade III injury combined with ACL or other ligament injury, chronic symptomatic valgus laxity after a rehabilitation programme, a reparable medial meniscus needing open access, or a posteromedial corner injury with anteromedial rotatory instability.

Imaging that drives approach selection. Weight-bearing AP and lateral films assess joint space and alignment, and valgus stress radiographs compare side-to-side opening when chronic laxity is suspected - look for a bony avulsion at the medial epicondyle or a Pellegrini-Stieda lesion of chronic MCL injury. MRI is essential for planning: coronal sequences localise the superficial MCL injury to its femoral origin, mid-substance or tibial insertion (femoral and tibial bony avulsions are amenable to direct repair, mid-substance or chronic injuries usually need reconstruction); axial and sagittal sequences assess the posterior oblique ligament and semimembranosus expansion; and reparable red-zone posterior horn tears and associated chondral injury are mapped to decide open versus arthroscopic meniscal repair. Contraindications: - Active infection or compromised soft-tissue envelope over the planned incision (open wounds, blistering, severe contusion)

• Significant medial skin scarring from previous surgery that would risk skin flap necrosis
• Over-extension into the adductor canal in a patient with peripheral vascular disease where the saphenous vein and femoral vessels are critical
• Most isolated grade I and II MCL injuries, which are managed non-operatively and do not require surgical exposure Approach variants - selecting the right medial incision:

Alternative and complementary approaches: - Arthroscopic inside-out or all-inside meniscal repair for posterior horn tears that do not need open access

• Anteromedial approach to the tibia for medial plateau fractures that are predominantly distal to the joint line
• Lateral approach for combined posterolateral corner injury in a multiligament knee
• Medial parapatellar arthrotomy alone when only intra-articular work is required without posteromedial exposure

Work down through the three Warren and Marshall layers along a curvilinear incision over the adductor tubercle and medial epicondyle, protecting the saphenous nerve and great saphenous vein between layers one and two, then develop the posteromedial interval to reach the capsule and posterior horn of the medial meniscus.

Structures at risk, by layer

Saphenous nerve injury management. If a branch is transected unexpectedly, consider burying the stump in soft tissue to reduce neuroma formation, document the finding and counsel the patient about the expected sensory deficit. Most deficits are sensory and well tolerated, but a symptomatic neuroma may require later excision and stump burial. Extensile options. - Proximal - extend along the medial femur toward the adductor canal to reach the medial femoral condyle and supracondylar region; the saphenous nerve becomes the saphenous branch of the femoral nerve proximally and the superficial femoral vessels lie deep, so protect the nerve and avoid entering the adductor canal unless required.

• Distal - continue along the posteromedial border of the tibia, deep to or behind the pes anserinus, to reach the medial tibial plateau and proximal shaft; mobilise the pes tendons to expose the tibial insertion of the superficial MCL.
• Anterior - extend into a medial parapatellar arthrotomy, splitting the extensor mechanism, for full intra-articular exposure (arthroplasty or extensive open joint work); this increases the risk to the infrapatellar branch.
• Posterior - rarely required; a formal posterior or popliteal approach is used when direct neurovascular access is needed.
• Combined - for multiligament knee injuries, combine with an arthroscopic ACL or PCL reconstruction, a lateral approach for posterolateral corner reconstruction, and a lateral or anterolateral approach for lateral-sided work. Closure (repair the layers in reverse). - Repair the deep layers - close layer three (the capsule and deep MCL) with absorbable sutures, preserving the medial meniscus; if the superficial MCL was incised or mobilised, repair it anatomically with strong absorbable sutures or reattach it to its bony insertion with suture anchors, tensioning the repair at thirty degrees of knee flexion in slight valgus.
• Restore the posteromedial corner - plicate or repair the posterior oblique ligament with the knee in extension to twenty degrees of flexion to restore posteromedial tension without over-constraining flexion.
• Reapproximate the superficial layers - reattach the pes anserinus and sartorius fascia if mobilised; close layer one with absorbable suture, then close the subcutaneous tissue meticulously and the skin with sutures or staples; consider a drain if dissection was extensive.
• Immobilisation - apply a hinged knee brace locked in extension for MCL or posteromedial work, or a simple compressive dressing for isolated meniscal repair; confirm reduction and fixation on intraoperative imaging if hardware was placed. Complications. | Complication | Prevention | Management | |--------------|------------|------------| | Saphenous nerve injury | Identify between layers one and two; gentle handling | Bury stump, counsel patient, consider later neuroma excision | | Great saphenous vein injury | Identify and protect; ligate only branches | Direct pressure, repair or ligation as appropriate | | Iatrogenic MCL laxity | Plan any arthrotomy; repair layer two anatomically | Revise tensioning, augment with reconstruction if needed | | Popliteal vessel injury | Stay anterior to the medial head of gastrocnemius | Direct pressure, vascular surgery assistance, repair | | Complication | Incidence | Prevention | Treatment | |--------------|-----------|------------|-----------| | Saphenous sensory deficit | Variable, commonest morbidity | Meticulous nerve identification | Observation, neuroma excision if symptomatic | | Stiffness and arthrofibrosis | Moderate risk after medial repair | Early range of motion, appropriate tensioning | Physiotherapy, manipulation under anaesthesia | | Infection | Low | Prophylactic antibiotics, meticulous closure | Irrigation and debridement, antibiotics | | Residual valgus laxity | Depends on injury grade | Anatomic repair or reconstruction, correct tensioning | Brace, revision reconstruction | | DVT or PE | Low to moderate | Chemoprophylaxis, early mobilisation | Anticoagulation |

Post-operative care and rehabilitation. - Immediate - neurovascular check documenting medial leg and infrapatellar sensation compared with the pre-operative baseline; hinged brace locked in extension for medial ligament work, compressive dressing for isolated meniscal repair; elevate and ice.

• Weight bearing - weeks zero to two touch weight bearing in a brace for ligament repair or reconstruction; weeks two to six progressive partial weight bearing with increasing range of motion; weeks six to twelve full weight bearing, wean the brace, advance strengthening.
• Rehabilitation phases - phase one (weeks zero to six) protected weight bearing, passive range of motion zero to ninety degrees, quadriceps isometrics and patellar mobilisation; phase two (weeks six to twelve) full weight bearing, closed-chain strengthening, stationary cycling, proprioception; phase three (months three to nine) sport-specific drills and plyometrics, return to contact sport typically six to nine months after MCL reconstruction pending stability testing.
• Follow-up - two weeks wound check and suture removal; six weeks clinical laxity assessment and radiographs if hardware placed; three months functional assessment; six to twelve months return-to-sport assessment for ligament reconstruction.
• DVT prophylaxis - LMWH or aspirin per institutional protocol until mobile, with mechanical prophylaxis while inpatient. Outcomes. Good prognostic factors are anatomic repair or reconstruction with correct graft tensioning, early protected range of motion, an isolated or single-plane medial injury, and addressed associated cruciate and meniscal pathology. Poor prognostic factors are a combined multiligament or knee dislocation injury, chronic laxity with secondary capsular attenuation, associated meniscal and chondral damage, and stiffness from delayed mobilisation. Unaddressed posteromedial corner injury in a chronic ACL-deficient knee drives anteromedial rotatory instability and may accelerate medial compartment osteoarthritis, and preservation or repair of the medial meniscus protects the compartment long-term. The single most important determinant of a good outcome is anatomic restoration of both the superficial MCL and the posterior oblique ligament combined with early protected motion - missed posteromedial corner injury is a common cause of failure after ACL reconstruction.

• MCL repair - direct suture-anchor reinsertion of a femoral or tibial bony or ligamentous avulsion, tensioned at thirty degrees of flexion.
• MCL reconstruction - anatomic reconstruction of the superficial MCL, often combined with a posterior oblique ligament plication or reconstruction, using autograft or allograft.
• Posteromedial corner repair - advancement and plication of the posterior oblique ligament onto the adductor tubercle, or a formal POL reconstruction for chronic anteromedial rotatory instability.
• Medial meniscal repair - open inside-out repair of posterior horn tears with suture retrieval through the posteromedial capsulotomy, the knee flexed sixty to ninety degrees to relax the posterior structures.
• Open medial meniscectomy - partial excision of irreparable tears when arthroscopic access is inadequate.
• Medial retinacular and MPFL work - repair or reconstruction of the medial patellofemoral ligament for patellar instability.
• Fracture fixation - ORIF of medial femoral condyle and medial tibial plateau fractures through appropriate extensions.
• Miscellaneous - removal of loose bodies, drainage for septic arthritis, and excision of a symptomatic semimembranosus bursa.

Key principle. Reconstruct or repair the posterior oblique ligament and superficial MCL anatomically, restore valgus stability through the arc of motion, and tension the repair with the knee flexed at thirty degrees in slight valgus to avoid over-constraining the joint.

The medial approach to the knee exposes the medial collateral ligament complex, the posteromedial corner and the medial meniscus through a layered dissection defined by the three Warren and Marshall layers. The patient is positioned supine with a bump under the ipsilateral hip and the knee flexed (figure-of-four) to bring the medial side anteriorly. The incision is a curvilinear cut centred over the adductor tubercle and medial femoral epicondyle. There is no single true internervous plane: the posteromedial interval lies between semimembranosus and the medial head of gastrocnemius, both supplied by the tibial nerve. The saphenous nerve is the critical at-risk structure together with the great saphenous vein, both running between layers one and two.

Guidelines, Registries and Global Practice Management of medial-sided knee injuries is convergent across examination systems (advanced orthopaedic practice and advanced orthopaedic practice, DNB and MS, MRCS, SICOT). The three-layer anatomical concept of Warren and Marshall and the recognition of the posterior oblique ligament as the key posteromedial stabiliser are near-universal. Most isolated grade I and II medial collateral ligament injuries are managed non-operatively in a hinged brace worldwide, while operative repair or reconstruction is reserved for bony avulsions, combined injuries with ACL and posteromedial corner involvement, and chronic symptomatic valgus laxity. Side-by-side principles (where guidance converges): | Body | Position on medial-sided knee injury |

|------|--------------------------------------| | AAOS | Most isolated MCL injuries are treated non-operatively; surgery is considered for grade III injuries combined with cruciate or posteromedial corner injury, bony avulsion, or chronic symptomatic laxity | | AO Foundation | Anatomic restoration of the superficial MCL and posterior oblique ligament, with graft tensioning at approximately thirty degrees of flexion, for operative reconstruction | | International consensus (multiligament) | Address the posteromedial corner when reconstructing the ACL in multiligament injuries to prevent anteromedial rotatory instability and protect the ACL graft | Population and registry evidence: - Medial collateral ligament injury is the commonest knee ligament injury, with a high incidence in contact sport, although population incidence varies widely by sport and reporting.

• Long-term follow-up of meniscal preservation shows that retaining or repairing the medial meniscus reduces the risk of medial compartment osteoarthritis compared with meniscectomy. Global practice variation: In high-resource settings, anatomic MCL and posteromedial corner reconstruction with autograft or allograft and arthroscopic inside-out or all-inside meniscal repair are standard. In resource-limited settings, the same layered principles are applied with primary repair of repairable tissue, suture-anchor fixation, and brace-based management of most injuries, with reconstruction reserved for selected chronic cases. Consent (globally applicable): discuss saphenous nerve injury and possible neuroma (the commonest approach-related morbidity), infection, stiffness and arthrofibrosis, residual or recurrent valgus laxity, and the risk of deep venous thrombosis.