Reconstruction of the Medial Collateral Ligament Complex With a Flat Allograft Semitendinosus Tendon

The aim of this Technical Note is to reconstruct the medial collateral ligament complex with the superior medial collateral ligament and posterior oblique ligament as anatomically as possible. An allograft or contralateral semitendinosus autograft is used for anatomic reconstruction of the superior medial collateral ligament and posterior oblique ligament. After bony fixation, the tendon bundles are sutured to the remnants of the medial collateral ligament complex. Thus, the tubular grafts are pulled apart to form a flat shape that resembles that of the normal medial ligaments.

T he medial collateral ligament complex is an impor- tant passive stabilizer of the knee joint and primarily stabilizes the knee against valgus stress. 1-32][3] Anatomically, the medial collateral ligament complex consists of the superior medial collateral ligament (sMCL), deep medial collateral ligament, posterior oblique ligament (POL), and posterior medial capsule (Fig 1). 2 The different parts of the medial collateral ligament complex have different functions stabilizing the joint against valgus stress as well as against anterior and posterior translation. 4n third-degree chronic instability, if there is insufficient residual tissue for suture or augmentation, reconstruction of the medial collateral ligament complex with a tendon graft is recommended. 5,68][9] However, these surgical techniques do not take into account that the structures of the medial collateral ligament complex do not have a tubular shape but a flat one. 7ver the past years, our working group has also further developed our medial reconstruction technique, 9 which takes the flat shape of the structure of the posteromedial complex into account.The aim of this article is to present this surgical method.

Surgical Technique (With Video Illustration)
Indications for reconstruction of the posteromedial structures are listed in Table 1.Table 2 shows the preoperative diagnostic measures, and the surgical instruments needed are listed in Table 3. Figure 2 shows a typical valgus stress radiograph with a medial joint opening of 12 mm.Video 1 shows the technique described to follow.

Patient Positioning
The operation is performed with the patient in the supine position and begins with an examination of the knee joint stability under anaesthesia (Lachman, pivot shift, drawer test, dial test, varus and valgus stress in full extension and 20 ).Then a tourniquet is applied, and the injured leg is draped in the usual sterile manner.Placing the leg in a movable, motorized leg holder facilitates the operation (Maquet GmbH, Rastatt, Germany).

Diagnostic Arthroscopy
A diagnostic arthroscopy using standard anterolateral and anteromedial portals is performed to diagnose and treat accompanying intra-articular injury.Typically, the "drive-through" sign can be seen in the case of high-grade medial instability (Fig 3).The position of the meniscus can provide useful information about the location of the medial ligament damage to decide where to place an additional plication of the residual medial ligamentous tissue.In the case of associated anterior or posterior instability, simultaneous arthroscopic anterior cruciate ligament or posterior cruciate ligament reconstruction can be performed. 4,10

Open Reconstruction of the Medial Collateral Ligament Complex
If no allograft is available or if the patient decides against the use of an allograft, a semitendinosus tendon must be harvested on the contralateral side.The harvesting technique has been described previously. 11,12or this medial reconstruction technique, an approximately 10-to 15-cm-long skin incision from the medial epicondyle to the level of the tibial tuberosity is needed (Fig 4).
After exposure of the medial collateral ligament complex, 2 guidewires are placed at the tibial insertions of the sMCL and POL and a third guidewire is placed between the femoral sMCL and POL insertion (Fig 5).The tibial sMCL insertion is located approximately 6 to 7 cm below the joint space in the middle of the tibial metaphysis covered by the hamstring tendons.To place the guidewire, a short incision is made between the semitendinosus and gracilis tendons.The tibial POL insertion is located proximal to the insertion of the semimembranosus tendon.The landmark for the femoral sMCL insertion is the medial epicondyle. 7The femoral insertion of the POL is 11 mm posterior to the medial epicondyle. 7Therefore, the common femoral tunnel for the sMCL and POL bundle is created just behind the medial epicondyle.
A fluoroscope is used to control the guidewire positions in 2 planes (Figs 6 and 7).In order to mark the entry of the guidewire into the cortical bone in the lateral plane, cannulated drills are advanced down to the bone.The position of the insertions of the sMCL and POL in the lateral plane is determined according to Athwal et al. 13

(Fig 6).
After guidewire placement, the tendon graft is prepared (Figs 8 and 9).First, the graft is shortened to a length of approximately 24 to 26 cm according to the distances measured between the guidewires.Both ends         After graft preparation, a cannulated 4.5-mm drill is used to drill the 3 tunnels.Then, blind tunnels are drilled to a length of approximately 30 mm with another drill with a larger diameter according to the diameter of the graft (Figs 10 and 11).After the tunnels are complete, the graft loop is pulled into the femoral bone tunnel by using an eyelet wire with a suture loop.Extracortical fixation is performed with a button (Fig 12).After successful fixation, cyclic traction is applied to the graft to condition the construct.
Then, the POL and the sMCL strands are pulled into the corresponding tibial bone tunnels.After the knee joint is cycled several times while pulling on both graft strands with maximal manual force, the reinforcement threads are tied over the lateral cortical bone bridge in approximately 20 flexion (Figs 12 and 13).After fixation, the peripheries of both graft strands are connected to each other and to the residual tissue with absorbable sutures (e.g., polydioxanone, gauge 2-0).Thus, the tubular grafts are pulled apart to form a flat shape (Figs 14 and 15).
Postoperatively, the patient is mobilized with partial weight-bearing (approximately 10 kg) on the operated leg for 6 weeks.A movable knee brace (e.g., The drawing shows a projection of a radiographic lateral view of the knee joint, in which the position of the insertions of superior medial collateral ligament (sMCL; orange), deep medial collateral ligament (dMCL; blue), and posterior oblique ligament (POL; green) are marked according to Athwal et al. 13 The common femoral tunnel (FT) lies on the extension of the posterior femoral cortex (a) just below a perpendicular line (b) that passes through the end of the Blumensaat line (B).The tibial sMCL tunnel (TTsMCL) lies on the bisecting line (c) of the proximal tibia approximately 6 to 7 cm below the tibial joint line (d).The tibial POL tunnel (TTPOL) lies in the posterior quadrant (4) about 1 cm below the tibial joint line (d). 1, 2, 3, 4 quadrants below the tibial joint line.Genu Arexa; Otto Bock Health Care, Duderstadt, Germany) is applied for 8 weeks (movement 0-5-90 for 2 weeks and 0-0-120 for another 4 weeks, then free).

Discussion
In recent expert consensus statements, there was agreement that for chronic posteromedial laxity, anatomic reconstruction of the sMCL and POL is recommended. 5,6In 2009, Lind presented a 2-bundle technique for the reconstruction of both structures. 8he ipsilateral semitendinosus tendon is detached from the muscle, the tibial insertion remains intact, the tendon loop is anchored in a femoral tunnel at the medial epicondyle and the free end is anchored as a POL graft below the posterior tibial plateau.
Lind et al. 8 reported in their retrospective case series approximately 98% normal or nearly normal medial stability (International Knee Documentation Committee grade A or B).This technique can therefore be considered the gold standard and most widely accepted medial reconstruction technique today.
Due to the reconstruction of the 2 biomechanically important structures sMCL and POL, this technique is commonly referred to as an anatomical technique. 4owever, 2 important anatomical features of the posteromedial complex are not considered here.First, the semitendinosus insertion is more anterior than the distal sMCL insertion, and second, the ligamentous structures of the posteromedial complex do not have a round tubular structure but are flat in shape. 1,2,7,15,16Another functional disadvantage of this technique is the use of the ipsilateral semitendinosus tendon, since the medial flexors also make an important contribution to stabilization against valgus stress. 17 In the technique presented here, an allograft or free tendon graft of the contralateral side is used to spare the ipsilateral flexors.However, care was also taken to ensure that the surgical technique is not too complicated from a surgical point of view (Table 4).With the  tibial bone tunnels, care is taken to ensure that these are in the natural insertion area of the sMCL and POL.Due to the anatomical proximity of the sMCL and POL insertion, a common tunnel is created femorally.A biomechanical study has shown that this 2-bundle technique can restore both valgus and posterior stability. 9rom our point of view, the use of a flat graft also has several advantages.Due to the wider arrangement of the fibers, the normal tension behaviour is more likely The peripheries of both graft strands are connected to each other and to the residual tissue with absorbable sutures (e.g., polydioxanone, gauge 2-0).Thus, the tubular grafts are pulled apart to form a flat shape.
to be imitated and the ligamentization of the graft seems to be improved, since there is more contact with the remnants of the posteromedial complex.We believe that by suturing the graft onto the remnants, the graft integrates into the existing structures of the posteromedial complex, optimizing their biomechanical function as well.Further biomechanical and animal studies are needed to prove this hypothesis.

Fig 2 .
Fig 2. Typical valgus stress radiograph with a medial joint opening of 12 mm.

Fig 4 .Fig 5 .
Fig 4. Skin incision from the medial epicondyle to the level of the tibial tuberosity.Right knee of a patient in supine position.(ME, medial epicondyle; P, patella; TT, tibial tuberosity.) e4

Fig 6 .
Fig 6.The drawing shows a projection of a radiographic lateral view of the knee joint, in which the position of the insertions of superior medial collateral ligament (sMCL; orange), deep medial collateral ligament (dMCL; blue), and posterior oblique ligament (POL; green) are marked according to Athwal et al.13The common femoral tunnel (FT) lies on the extension of the posterior femoral cortex (a) just below a perpendicular line (b) that passes through the end of the Blumensaat line (B).The tibial sMCL tunnel (TTsMCL) lies on the bisecting line (c) of the proximal tibia approximately 6 to 7 cm below the tibial joint line (d).The tibial POL tunnel (TTPOL) lies in the posterior quadrant (4) about 1 cm below the tibial joint line (d). 1, 2, 3, 4 quadrants below the tibial joint line.

Fig 7 .Fig 8 .
Fig 7. Anteroposterior (a) and lateral (b) fluoroscopic images to control the guidewire position.Drills advanced onto the cortex mark the entry of the guidewires into the bone.a: Extension of the posterior femoral cortex, b: perpendicular to a line passing through the end of the intercondylar line, c bisector of the tibia, d: joint line, 1, 2, 3, 4 quadrants below the tibial joint line.(FT, femoral tunnel; POL, posterior oblique ligament; sMCL, superior medial collateral ligament; TTPOL, tibial POL tunnel; TTsMCL, tibial sMCL tunnel.)

Fig 12 .
Fig 12. Pulling the graft into the bone tunnels.a) First, the graft loop is pulled into the femoral bone tunnel by using an eyelet wire with a suture loop (a) and extracortical fixation is performed with a button (b).After successful fixation cyclic traction is applied (c) to the graft to seat the anchor on the femoral cortex and condition the graft construct.b) Pulling the POL and the sMCL strand into the corresponding tibial bone tunnels and cyclic movement of the knee joint while pulling on both graft strands.Then the threads of the graft ends are tied over the lateral cortical bone bridge in approximately 20 flexion.

Fig 15 .
Fig 15.This drawing (a) and intraoperative photo (b) show the 2 flat graft strands after suturing to each other and to the residual tissue of the posteromedial complex.Right knee of a patient in supine position.(AT, adductor tubercle; G, gracilis tendon; ME, medial epicondyle; P, patella; POL, posterior oblique ligament; SE, semimembranosus tendon; sMCL, superior medial collateral ligament; ST, semitendinosus tendon; TT, tibial tuberosity.)

Table 1 .
Indications for Medial Collateral Ligament Reconstruction IndicationsSymptomatic chronic isolated medial instability (valgus stress test þþ or þþþ in extension without endpoint) Symptomatic chronic high-grade combined medial instability with injury of the anterior and/or posterior cruciate ligament

Table 2 .
Preoperative Diagnostics Diagnostics Clinical examination with Lachman test, pivot shift, valgus and varus stress in 0 and 20 , posterior drawer, dial test Magnetic resonance imaging Valgus stress radiographs (ipsi-and contralateral) Posterior stress radiographs to determine the amount of associated posterior instability Long leg radiographs to determine the leg axis

Table 3 .
Equipment Required for Medial Collateral Ligament Reconstruction