Tibial-Sling Triangular Medial Collateral Ligament Reconstruction With Posterior Oblique Ligament Limb

Video Transcript

Medial collateral ligament (MCL) injuries are a common sports-related occurrence. These injuries can occur in isolation or combined with other ligament tears, such as of the cruciate ligaments.^4,10 While most medial-sided knee injuries can be managed conservatively, high-grade injuries of the posteromedial corner, specifically injuries with medial joint gapping in extension or grade 3 MCL tears, have been reported to have less than optimal outcomes with conservative approaches, resulting in residual valgus and rotational instability. Persistent medial instability also has been shown to add strain to cruciate ligament grafts, increasing the risk of failure.^6,9

While there are multiple surgical options for MCL laxity, there is substantial agreement in the present literature regarding chronic medial and posteromedial laxity, as reflected in a recent expert consensus statement on posteromedial injuries, where 100% of the polled experts agreed that treatment should employ a technique that aims to reproduce the native anatomy of both key medial-sided structures—namely the superficial medial collateral ligament (sMCL) and posterior oblique ligament (POL). ²

A recent technique by Canuto et al ¹ describes a triangular-shaped sMCL reconstruction using a semitendinosus or gracilis graft in a tibial sling at the distal insertion of the MCL. Despite many advantages, this technique does not reproduce the anatomy of the posteromedial knee in its entirety.

In this article, we aim to describe a modified Canuto tibial-sling triangular MCL reconstruction with a POL limb to address grade 3 posteromedial instability.

Our patient was a 33-year-old man, who sustained a motocross injury. He presented to our office with complaints of persistent knee pain and instability, despite a 4-week treatment of non-weightbearing with crutches and an immobilizer knee brace. Physical examination revealed a neutral alignment and no restrictions in range of motion, but a grade 2 posterior drawer test, and grade 2 reverse Lachman test, as well as grade 2 valgus opening in both full extension and 30° of flexion. Preoperative magnetic resonance imaging revealed a complete posterior cruciate ligament (PCL) tear, as well as a complete mid-substance MCL tear, extending all the way through the posteromedial aspect of the knee, as seen in the most posterior coronal cuts. Our planned treatment combined a PCL reconstruction and our modified Canuto technique for anatomic posteromedial reconstruction.

The PCL was reconstructed with a single-bundle remnant-preservation technique, using an Achilles tendon allograft. We advocate a lateral approach for creating the tibial tunnel, which has been shown to minimize the risk of damaging the popliteal artery, as described by Franciozi et al. ³

The original anatomic triangular tibial-sling MCL reconstruction technique by Canuto takes place with the patient in standard supine positioning, under general or spinal anesthesia. A semitendinosus autograft is harvested from the injured or contralateral knee and is then whipstitched on both ends and measured.

When performing isolated MCL reconstruction with the Canuto technique, it can be performed percutaneously, with a 3-cm longitudinal anteromedial incision centered at 6 cm from the medial joint line. Following superficial dissection, 2 convergent perpendicular 6-mm tunnels are drilled to create our tibial sling for the graft.

A passing suture can be shuttled with the use of a Hewson-like suture passer, or even easily using the back end of a needle with polyester suture. The prepared semitendinosus graft is then passed through the tibial sling, without the need for any implant fixation. The graft is directed proximally, along the second Warren-Marshall layer of the knee.

A small incision centered over the medial epicondyle is performed for the creation of the femoral tunnel. A guidewire is used to determine the preliminary site of the tunnel aperture, 5 mm posterior and 3 mm proximal to the apex of the medial epicondyle. The chosen positioning is then tested for the isometry of the construct, with cycles of knee flexion and extension, and adjusted if needed until no displacement is observed. The MCL reconstruction is fixed at the femur with a 7-mm bioabsorbable interference screw at 30° of flexion and neutral rotation, under manual varus stress.

We propose, however, a modified Canuto anatomic MCL + POL reconstruction, which was performed in the presented case example. When reconstructing both posteromedial structures, an open medial approach is needed. As in the original technique, a semitendinosus graft is passed in a tibial sling for the sMCL graft, which is fixed to the femur as previously described. Here, however, that same single femoral tunnel will be shared by the 2 strands of the semitendinosus graft and a limb of gracilis autograft to reproduce the POL.

The POL tibial tunnel is centered at the insertion of the direct arm of the semimembranosus tendon on the posteromedial aspect of the proximal tibia and aimed anteriorly. The gracilis graft is then passed through the tunnel aided by a passing suture, and the POL limb of the reconstruction is fixed with a second interference screw in extension under varus stress at the anterior tibial cortex.

Postoperative anteroposterior and lateral radiographs demonstrate tunnel placement of the single-bundle PCL reconstruction in yellow, with the sMCL graft in blue, and POL graft in orange.

Postoperative physical examination demonstrates the restored valgus stability in extension and 30° of knee flexion.

Technical pearls to keep in mind are maintaining a minimum 1.5-cm distance between the converging tibial-sling tunnels to avoid tibial cortex blowout, always testing femoral tunnel positioning until the isometric point is achieved, and reinforcing the graft at its interface with the femoral tunnel aperture to avoid tissue damage during fixation.

Postoperative rehabilitation is approached in a stepwise fashion, with an initial emphasis on early quadriceps activation, 6 weeks of partial weightbearing, and assisted-active knee flexion limited to 90°. Running progression should be started at least 12 weeks postoperatively, and return to sport is possible at 6 to 9 months depending on the procedures performed concomitantly.

Operative treatment of medial-sided injuries has been widely studied in recent decades. A recent systematic review demonstrates improved patient-reported outcomes following both MCL repair and MCL reconstruction. ⁸ The authors found, however, that MCL repair largely results in higher rates of not only knee stiffness, but also a higher 2-year failure rate, suggesting that reconstructions are advantageous. ⁸

Multiple reconstruction techniques, both with allografts and autografts, have been described for the medial knee. Of note, LaPrade and Wijdicks ⁵ described a technique for anatomic reconstruction using 2 free independent allografts, while the Danish anatomic reconstruction described by Lind et al ⁷ uses hamstring autografts in a triangle-shaped configuration with a common femoral insertion for the sMCL and POL.

More recently, Canuto et al ¹ described an anatomic technique for sMCL reconstruction using a semitendinosus or gracilis graft in a tibial sling and fixed at its anatomic femoral insertion. Advantages of the technique include a 2-strand sMCL construct, which provides increased cross-sectional area to the graft.^6,9 Drilling a single femoral tunnel decreases the risk of tunnel convergence during multiligament reconstructions. The most significant benefit potentially lies is the nonuse of implants to fix on the tibial side of the construct, which reduces surgical time and procedural costs, especially in multiligament knee surgery or in areas with limited financial resources and access to allografts.

Our modified technique, adding a POL anatomic limb, aims to maximize valgus and internal rotation stability in extension, addressing the biggest shortcoming of the Canuto tibial-sling MCL reconstruction technique, while maintaining its substantial advantages.

In summary, we present an anatomic modified MCL and POL reconstruction with hamstring autografts that is simultaneously cost-saving and anatomic-based.