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The “Figure of Four” Reconstruction of the Medial Collateral Ligaments in the Setting of Anteromedial Rotatory Knee Instability Using a Single Autograft

The deep medial collateral ligament plays an important role in controlling tibial external rotation and restrain anterior translation of the medial tibial plateau. Despite being the basic lesion of anteromedial knee instability as proposed by many authors, the majority of the medial side reconstructions do not restore the anatomy and the function of the deep medial collateral ligament. In this Technical Note, we describe a technique to reconstruct both the superficial and deep medial collateral ligament in the setting of anteromedial knee instability using a single peroneus longus autograft.

A nteromedial rotatory instability (AMRI) of the knee is caused mainly by an injury to both the anterior cruciate ligament (ACL) and the medial collateral ligaments (MCLs) with both superficial medial collateral ligament (sMCL) and deep medial collateral ligament (dMCL) components usually involved, 1 resulting in a coupled anterior tibial translation and external rotation (ER) causing the medial tibial plateau to subluxate anteriorly. 2 Failure to identify AMRI during ACL reconstruction may lead to residual knee laxity with subsequent greater ACL graft in situ forces and eventually failure. 3,4 Both the sMCL and dMCL act reciprocally to restrain ER through different flexion angles. The dMCL is taught near extension, whereas the sMCL becomes more involved in deeper flexion angles. 5,6 The importance of the dMCL in controlling tibial ER and its role in AMRI was first described by Slocum and Larson,7 who found that dMCL injury caused excessive tibial ER and was the basic lesion resulting in AMRI. This findings were later confirmed by several biomechanical studies. 5,6,8 The dMCL fans out anterodistally from a point distal and posterior to the medial epicondyle (ME) and attaches to the medial tibial plateau with a broad footprint (Fig 1). This orientation makes it ideal to resist anterior translation of the medial tibial plateau. 9 Despite the importance of the dMCL, the majority of the medial side reconstructions do not restore the function of the dMCL and describe only either isolated sMCL or combined sMCL and posterior oblique ligament reconstructions. [10][11][12][13] We describe our "figure of 4" technique of sMCL and dMCL reconstruction using a single peroneus longus autograft (Fig 2). A full procedural demonstration may be found in Video 1.

Surgical Technique (With Video Illustration) Patient Positioning and Examination Under Anesthesia
The patient is positioned supine with a lateral thigh post and a footrest after induction of general anesthesia. Examination under anesthesia and fluoroscopic stress radiographs are performed to confirm preoperative diagnosis. The leg is then prepared and draped in standard fashion.

Diagnostic Arthroscopy and Concomitant Pathology
ACL reconstruction is routinely preformed first using an ipsilateral autologous quadriceps tendon graft. Meniscal and chondral lesions are addressed at this point before extraarticular reconstruction.

Graft Harvest and Preparation
The ipsilateral peroneus longus (PL) tendon is harvested, prepared, and both ends are whipstitched by no. 2 nonabsorbable suture.

Technique
An anteromedial skin incision is made starting proximally midway between the adductor tubercle and the medial border of the patella extending distally across the joint line midway between the anterior and posterior tibial borders to the level of the pes anserinus 6 to 7 cm distal to the joint line. Full-thickness skin flaps are developed, with special attention not to injure the saphenous nerve.
On the femoral side, we start by identifying the adductor magnus tendon. The tendon is followed toward its insertion point at the adductor tubercle, which serves as an important landmark to locate the ME, which is located approximately 12.6 mm distal and 8.3 mm anterior to the adductor tubercle. 14 The native sMCL envelopes and attach directly to the ME, whereas the dMCL femoral footprint is located 6 mm distal and 5 mm posterior to the ME. 9 The femoral insertion is exposed by making a longitudinal incision over the ME down to the crural fascia. For creation of the dMCL femoral socket, an eyelet pin is placed slightly distal and posterior to the ME at the femoral attachment site of the dMCL from medial to lateral aiming slightly anterior and proximal (Fig 3), then a 7 Â 25-mm socket is reamed over the guide pin and a passing suture is placed.
Attention now is directed distally to create the tibial attachment sites for both the sMCL and dMCL. To create the dMCL tibial attachment site, 2 slightly convergent tunnels are created 20 mm apart to a depth of 15 mm at the mid-third of the anteroposterior diameter of the medial tibial plateau 1 cm distal to the joint line using a 5-mm drill. Care must be taken not to break the medial tibial cortex to avoid tunnel blow out. A shuttling suture with a large curved needle is used to pass a suture loop through the tibial transosseous tunnel saved for later graft passage (Fig 4).
The tubular part of the graft (distal end of the PL tendon graft) is docked first into the dMCL femoral socket and secured with a 7 Â 25-mm bioabsorbable interference screw (Inion, Tampere, Finland) ( Fig 5). The graft is then shuttled through the convergent tibial tunnels from posterior to anterior using the passing sutures previously left in place creating the dMCL tibial footprint (Fig 6). The free end of the graft (sheet-like Artist's impression of the deep medial collateral ligament (dMCL) anatomical orientation. The dMCL fans out anterodistally as it originates from a point (B) slightly distal and posterior to the medial epicondyle (ME) and broadly attaches to the tibia nearly 1 cm distal to the joint line. 9 e1240 proximal end of the PL graft) is then brought back proximally and fixed to the ME by a thorny titanium staple (Arthrex, Naples, FL) with the knee at 20 of flexion, neutral rotation, and slight varus force being applied (Fig 7).
For sMCL tibial tunnel creation, the superior border of the pes anserinus is retracted distally, an eyelet pin is placed 6 cm distal to the joint line at the posterior border of the native sMCL and reamed creating a 7-mm tunnel (Fig 8). The graft is folded, brought back distally, and pulled into the tibial tunnel. The graft is the tensioned, cycled multiple times, and fixed using a bioabsorbable interference screw (Inion) with the knee held in 20 of flexion, neutral rotation and a varus force being applied (Fig 9). To create the proximal tibial attachment of the sMCL, the sMCL portion of the graft is sutured to dMCL portion 1 cm below the joint line at the level of the dMCL tibial tunnels. Pearls and pitfalls of this technique are summarized in Table 1.

Postoperative Protocol
The specific rehabilitation protocol is tailored according to the concomitant procedures performed along with the MCL reconstruction. The knee is kept in     extension for the first 2 weeks followed by gradual increase of the flexion range. The patient is allowed to partially bear weight while the knee is locked in extension for 6 weeks followed by progression to full weight bearing. Return to most activities by 4 to 6 months.

Discussion
Combined ACL and MCL injuries are one of the most common knee injuries. 15 Slocum and Larson 7 first described the term AMRI as an excessive valgus motion coupled with ER of the knee in which the anteromedial tibial plateau subluxate anterior to the corresponding femoral condyle. 7 Failure to identify this instability pattern during ACL reconstruction increases the risk of ACL graft failures and revisions. 3,4 Recent biomechanical studies 1,5,6 highlighted the importance of the dMCL in controlling the tibial external rotation and that it was the major restraint against ER in extension and early flexion angle, while the sMCL was dominant in deeper flexion angles besides being the major restraint against valgus forces across the whole range of motion, thus minimizing the role of the posterior oblique ligament in controlling ER. A recent anatomical study 9 described the dMCL as an oblique fanshaped structure running anterodistally from a small femoral attachment distal and posterior to the ME to a broad tibial attachment. This orientation causes the dMCL to tighten with ER, thus resisting AMRI.
The advantage of this technique (Table 2) is that it reproduces the orientation and the broad attachment of the dMCL on the tibia, thus providing better control for ER. An additional benefit of this technique is the use of a single autograft to reconstruct both components of the MCL, which may be useful in the setting of multiligament knee injuries. The use of the peroneus longus Fig 7. Right knee, the patient is lying supine with the leg extended (the patient's head is to the right side of the picture). The graft is brought back proximally and fixed to the medial epicondyle (ME) using a titanium staple (Arthrex, Naples, FL) at 20 of flexion, neutral rotation and slight varus force being applied.  autograft in knee ligament reconstruction has recently been popularized with great outcomes and negligible drawbacks. 16 In our opinion, the use of the peroneus longus carry some advantages; it provides a long graft with sufficient length to perform this technique in addition that the graft is broader than the hamstrings with a sheet-like proximal end, which better mimics the native sMCL. The main disadvantage of this technique is the need for a long graft (25 cm or more), which is not reproducible in all cases. We recommend the use of 2 separate grafts in short individuals or insufficient graft length.
In summary, our technique to reconstruct both the sMCL and dMCL using a single autograft can closely reproduce the native anatomy of the MCL and could restore normal rotational laxity in the setting of AMRI.  Creating the broad tibial footprint of the deep medial collateral ligament helps in better rotational control Use of a single autograft is helpful especially in multiligament injuries