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Combined Posterior Cruciate Ligament and Superficial Medial Collateral Ligament Knee Reconstruction: Avoiding Tunnel Convergence

Combined posterior cruciate ligament (PCL) and medial collateral ligament (MCL) injuries represent a complex pathology that requires a thorough clinical and radiographic examination to diagnose and identify all injured structures. Anatomic reconstruction of the injured ligaments is recommended, including double-bundle PCL reconstruction and superficial MCL augmentation. In the setting of this complex reconstruction, several technical aspects require consideration and preoperative planning, including the risk of femoral tunnel convergence on the medial aspect of the femoral condyle. This article details our technique for combined anatomic double-bundle PCL reconstruction and superficial MCL augmentation to avoid tunnel convergence. Level I (knee); level II (PCL).

A natomic double-bundle posterior cruciate ligament reconstruction (PCLR) has been shown to better restore anatomy and knee kinematics 1 as well as improve objective measures of posterior translation and International Knee Documentation Committee scores [2][3][4] in comparison to single-bundle reconstruction. Superficial medial collateral ligament augmentation using semitendinosus and gracilis autograft has been reported to restore near-native stability to the medial side of the knee. 5,6 Techniques for isolated double-bundle PCLR 7 and superficial medial collateral ligament (sMCL) augmentation 8 have previously been described.
Femoral and tibial tunnel convergence is a risk of multiple concurrent ligament reconstructions. The tunnel location for anatomic reconstruction has been defined, 6,9,10 as have the optimal intertunnel relationships to avoid convergence (Fig 1). 11,12 The purpose of this article is to describe our technique for combined anatomic double-bundle PCL reconstruction and superficial MCL augmentation to avoid tunnel convergence.

Surgical Technique
Details of the technique are shown in Video 1. Pearls and pitfalls of the technique and advantages and  Tables 1 and 2, respectively. Details of the surgical technique for both isolated double-bundle PCLR 13 and superficial MCL augmentation 8 can be found in individual technique articles; however, salient points regarding combined reconstruction and avoiding tunnel convergence are summarized below.

Objective Diagnosis
Combined PCL and MCL knee injuries should be diagnosed through accurate physical examination and imaging methods (standard and stress radiographs and magnetic resonance imaging).

Indications and Contraindications
Surgical management of acute PCL and sMCL injuries is indicated when there are multiligament injuries or a knee dislocation involving these structures. 14 Regarding chronic PCL injury, indications include functional limitations resulting from the PCL tear (e.g., difficulty with deceleration, incline descent, or stairs) and PCL stress radiographic laxity >8 mm in a symptomatic patient. 15 Regarding chronic grade III MCL injuries, surgery is indicated when functional rotatory or side-to-side instability persists despite conservative therapy, including bracing and a rehabilitation program for at least 6 weeks after injury.

Patient Positioning and Anesthesia
The patient is placed in the supine position on the operating table. After induction of general anesthesia, a bilateral knee examination is performed to evaluate for any concurrent ligamentous instability and to assess knee range of motion. A well-padded thigh tourniquet is placed on the operative leg, which is placed into a leg holder (Mizuho OSI, Union City, CA). The contralateral knee is placed into an abduction stirrup (Birkova Products, Gothenburg, NE), and the foot of the operating table is lowered, allowing the surgeon to freely manipulate the knee as needed.

Graft Preparation
For the double-bundle PCLR technique, Achilles tendon and anterior tibialis allografts are prepared in the fashion previously described. 13

Surgical Approach
A skin incision is made on the anteromedial aspect of the knee between the adductor tubercle and medial aspect of the patella, extending w7 to 8 cm distal to the joint line, which also facilitates creation of the PCL tibial tunnel. Semitendinosus and gracilis tendons are identified, and an open-ended hamstring stripper (Smith & Nephew, Andover, MA) is used to detach them proximally. Two double-loaded suture anchors (Mitek, Westwood, MA) are then used to fix the tendons to the tibia w6 to 7 cm distal to the joint line in the location of the sMCL remnant. The tendons are passed proximally, and the sMCL femoral insertion is identified (Fig 2).

Avoiding Tunnel Convergence
After the sMCL femoral insertion is identified, sharp dissection is performed to bone to clear the area of soft tissue. An eyelet pin is placed at this point with an aiming guide (Arthrex), aiming 40 anteriorly and 40 proximally to avoid tunnel convergence and the trochlea. A 7-mm tunnel is then over-reamed (Reamer; Arthrex) to a depth of 35 mm to create a socket, and a passing suture is placed through the tunnel. The tendons are marked at the femoral insertion and whipstitched 30 mm proximal, and the excess lengths of the tendons are cut. An anteromedial incision will facilitate easier PCL tunnel drilling. When drilling the sMCL tunnel, aiming at 0 in the axial and coronal plane risks convergence with the ALB and PMB tunnels. When drilling the sMCL tunnel, aim 20 to 40 anteriorly and 40 proximally to avoid tunnel convergence. The PCL grafts should be tensioned and fixed on the tibia before proceeding with sMCL femoral fixation.

PCL Reconstruction
Attention is turned to PCL reconstruction. Routine arthroscopy is performed through anterolateral and anteromedial portals. Arthroscopic landmarks are used to identify the anatomic attachment sites of the PCL bundles (Fig 3). 9 After the ALB and PMB tunnels are reamed and passing sutures are placed, a posteromedial portal is made for identification and debridement of the PCL tibial attachment. A guide pin is drilled, entering the anteromedial aspect of the tibia w6 cm distal to the joint line and centered between the anterior tibial crest and the medial tibial border. Care is taken to avoid the semitendinosus and gracilis tendons and sMCL suture anchors. Pin placement is checked with intraoperative fluoroscopy, 9 and the tibial tunnel is reamed, followed by passing a large smoother (Gore Smoother Crucial Tool; Smith & Nephew) through the tibial tunnel and pulling it out the anteromedial arthroscopic portal. The posteromedial bundle (PMB) and anterolateral bundle (ALB) grafts are passed and fixed in the femur and pulled through the tibial tunnel with the smoother. The ALB is fixed with the knee flexed to 90 and in neutral rotation and secured with a fully threaded, bicortical 6.5 Â 40-mm cannulated cancellous screw (Arthrex) and an 18-mm spiked washer (Arthrex). 1 The PMB is then secured to the tibia with the knee in full extension with the same size screw and washer that were used for ALB fixation (Fig 4).

sMCL Augmentation
Attention is turned back to sMCL augmentation. The whipstitched tendon grafts are pulled through the femoral tunnel with the passing suture, and traction is maintained on the graft. The knee is positioned at 20 of flexion with neutral rotation, and a gentle varus force is applied. A 7 Â 25-mm bioabsorbable screw (Arthrex) is used to fix the graft in place. To reproduce the proximal tibial attachment of the sMCL, a doubleloaded suture anchor (Mitek) is placed 12 mm distal to the joint line, and the sutures are tied to the grafts with the knee positioned at 20 of flexion and neutral rotation.
Once fixation is complete, the knee is flexed to determine the "safe zone" range of movement that can be initiated during the early postoperative period. It is important that the sMCL graft is able to be fully flexed

Postoperative Protocol
After the procedure, the patient is to remain nonweightbearing for 6 weeks on crutches. Physical therapy begins on postoperative day 1 with a focus on pain control, reducing edema, and knee motion. The patient is placed into a knee immobilizer for w3 to 5 days and then is transitioned into a dynamic PCL brace (PCL Rebound brace; Ossur Americas, Foothill Ranch, CA). Knee range of motion is limited from 0 to 90 for the first 2 weeks and is performed only in the prone position to avoid excessive tension on the PCL reconstruction grafts. Weightbearing is initiated at 6 weeks postoperatively along with low-resistance cycling on a stationary bike. Once patients can tolerate 20 minutes of walking with a nonantalgic gait pattern, a periodized strength program, which focuses on the sequential development of muscular endurance, strength, and power, is commenced. Knee flexion during weightbearing exercise is limited to 70 until 16 weeks postoperatively to avoid excessive PCLR graft strain, and then progressed without limitation. Open-chain isolated hamstring contractions are also avoided for the first 16 weeks after surgery. At 6 months postoperatively, patients are allowed to discontinue the dynamic PCL brace for routine daily use if the side-toside difference in kneeling PCL stress radiographs is <2 mm. Patients may begin a gradual return to activity progression, with full clearance determined after passing a functional sports test and repeat kneeling PCL and valgus stress radiographs at 12 months postoperatively.

Discussion
Combined PCL and sMCL injuries represent a complex pathology, and special consideration should be given to the technical aspects of combined ligament reconstruction. Tunnel convergence in multiple ligament knee reconstruction can compromise graft integrity and fixation and lead to reconstruction failure. Moatshe et al. 11 showed the optimal tunnel relationships during multiple ligament knee reconstructions to avoid tunnel convergence. During medial knee reconstruction, tunnel collision occurred between the sMCL and anterolateral bundle (16 of 21, 76%) and posteromedial bundle (19 of 21, 90%) of the PCL when the sMCL was oriented at neutral (0 ) in both the axial and coronal planes. Aiming the sMCL tunnel 20 to 40 anteriorly and 40 proximally avoided tunnel convergence in 18 of 21 (86%) of patients (Fig 3). Camarda et al. 16 also reported that tunnel convergence could be avoided by aiming the sMCL tunnel 40 proximally.
Good results have been reported with both isolated double-bundle PCLR 13 and sMCL augmentation. 6 However, there are no studies assessing the outcome of combined PCL reconstruction and sMCL augmentation. We encourage other groups to test the validity of this technique with regard to avoiding tunnel convergence and to assess for long-term patient outcomes.