Treatment Options for Combined ACL and Medial Collateral Ligament Injuries

Anterior cruciate ligament, or ACL, tears combined with medial collateral ligament, or MCL, injuries are common combined ligament injuries in sports twisting injuries, skiing, ball sports, and traffic trauma.

There is no single fixed treatment plan for everyone. MCL injury grade, tear location, remaining valgus instability, sport demand, and ACL surgery timing can all change the plan.

Mild to moderate MCL injuries and complete MCL ruptures may require very different strategies.

The ACL lies in the center of the knee and mainly limits anterior tibial translation and some rotational instability. The MCL lies on the medial side and is a key restraint against valgus opening.

MCL integrity is important for medial stability in both extension and flexion.

When both ligaments are injured, patients may have pain, swelling, limited motion, and a giving-way feeling while walking or turning. Compared with isolated ACL injury, the knee also has medial laxity and valgus-rotational instability.

Persistent medial instability can increase load on an ACL graft. If MCL function is insufficient, ACL reconstruction alone may not fully restore anterior-posterior, valgus, and rotational stability.

MCL injuries are commonly graded I, II, and III.

Grade I is a mild sprain with preserved continuity. Grade II is a partial tear with reduced stability but some function. Grade III means complete rupture, with obvious medial joint opening during valgus stress testing.

For combined ACL injury with grade I or II MCL injury, the usual direction is bracing and rehabilitation first, allowing the MCL to heal, then deciding on ACL reconstruction according to ACL-related instability.

The German Knee Society consensus similarly recommends nonoperative MCL treatment for combined ACL with grade I or II MCL injuries.

Grade III MCL injury is more complex. Whether the complete tear is at the femoral attachment, midsubstance, or tibial attachment, whether there is displacement, and whether valgus instability remains after rehabilitation all affect repair or reconstruction decisions.

The MCL differs from the ACL in that it has better healing potential. For partial tears, bracing, valgus stress control, and progressive rehabilitation can give the ligament a chance to heal.

For grade I and II injuries, treatment often includes a knee brace, gradual restoration of range of motion, quadriceps and hamstring training, and weight-bearing progression based on stability.

Some grade III injuries can also be observed initially. A 2024 systematic review and meta-analysis included 18 studies and 1534 patients with combined ACL-MCL injuries and compared ACL reconstruction with nonoperative MCL care, MCL repair, and MCL reconstruction.

Final functional scores, range of motion, and quadriceps strength did not show one MCL strategy with clear superiority for all patients.

Lower-grade MCL injuries can be observed during rehabilitation, and if obvious valgus or anteromedial rotational laxity remains, combined ACL and MCL treatment can be considered.

Complete femoral avulsion, complete midsubstance rupture, and complete tibial avulsion may all enter the surgical decision range. Obvious bony avulsion may require refixation.

A special tibial-sided pattern is the Stener-like lesion. In this injury, the distal MCL is displaced and separated by pes anserinus or other tissues, making the ligament end unable to return to its normal position and reducing the chance of natural healing, so early repair is often favored.

If after about 6 weeks of bracing and rehabilitation the knee still has obvious valgus laxity in extension or at 20 to 30 degrees of flexion, or persistent medial instability during walking or sport, conservative care alone may be insufficient.

One common strategy is to treat the MCL first, wait for pain, swelling, and range of motion to improve, and perform ACL reconstruction after MCL stability recovers. This can reduce postoperative stiffness risk and helps determine whether MCL surgery is truly needed.

Recent treatment discussions also focus on acute management. A 2024 systematic review of 821 acute complete ACL-MCL injuries compared multiple treatment combinations.

Acute ACL reconstruction combined with nonoperative MCL care, repair, or reconstruction can all achieve good valgus stability in selected patients. Current data cannot identify one timing strategy for everyone.

The physician must also consider swelling, range of motion, MCL tear location, meniscus or cartilage injury, and the need for rapid return to high-level sport.

Repair is mainly suitable for acute injuries with good tissue quality and ends that can be refixed. A femoral avulsion can be repaired with suture anchors; some tibial avulsions can be treated similarly.

Reconstruction uses a tendon graft to restore MCL function and is more often used for chronic medial instability, poor tissue quality, obvious laxity after old injury, or failed previous repair.

Systematic reviews suggest both repair and reconstruction can improve scores, but repair has shown relatively higher rates of postoperative knee stiffness and failure in some data, so the method should match injury morphology and tissue condition.

All-arthroscopic MCL repair is now available for selected combined ACL-MCL injuries suitable for repair.

In 64 patients with ACL injury and femoral-sided MCL injury, all underwent ACL autograft reconstruction; 32 had arthroscopic MCL repair and 32 had open MCL repair. Knee stability at 6, 12, and 24 months was not significantly different.

Complications within 6 months occurred in 2 arthroscopic cases versus 8 open cases, or 6.25% versus 25%. The arthroscopic group also had higher Lysholm and IKDC scores at several time points.

Arthroscopy can reduce a larger medial incision and locate the femoral MCL attachment under visualization. Open repair provides direct exposure and can be useful for complex injuries. All-arthroscopic repair requires experience, because the medial working space is limited and the technique is demanding.

One rehabilitation goal is to protect the healing MCL while avoiding stiffness from prolonged immobilization.

When the MCL is treated nonoperatively, bracing is often used for about 6 weeks, but range-of-motion and weight-bearing plans vary. There is still no uniform standard for the best restriction angle or loading timeline.

A common approach is early protected motion and muscle training, with gradual flexion increase according to stability.

In the 64 patients who underwent ACL reconstruction and MCL repair, a brace kept the knee in extension immediately after surgery. On day 1, quadriceps isometrics, straight-leg raises, and ankle pumps began; motion progressed to 0 to 90 degrees within 4 weeks, then to 90 to 120 degrees from 4 to 8 weeks, aiming for near-normal range by about 3 months.

A patient’s plan may change according to MCL tear location, repair type, meniscus treatment, and ACL graft type.