Suture Fixation of Tibial Eminence Fractures: Optimizing Postoperative Knee Range of Motion and Stability

Introduction

Tibial eminence fractures (TEFs) are common in pediatric patients, accounting for approximately 2%-5% of all pediatric knee injuries. ^, These fractures typically occur between the ages of 8-14 years old due to relative weakness of pediatric subchondral epiphyseal bone. ^, Fracture of the tibial eminence is considered functionally equivalent to a rupture of the anterior cruciate ligament (ACL), in which the incomplete ossification of the tibial eminence causes the bone to fail rather than the ligament. Surgical fixation of displaced TEFs is thus indicated to restore stability to the knee.

Current treatment recommendations include surgical fixation for displaced TEFs followed by early rehabilitation. Various technique options have been described for fixation of TEF’s. Pediatric bone has different biomechanical properties than adult human bone, which may influence the success of various TEF fixation methods. Two of the most popular techniques involve arthroscopically-assisted reduction with either screw or suture fixation. A recent study suggested that suture fixation is equivalent to screw fixation in terms of biomechanical properties when the fixation methods were tested in human pediatric knees. A recent meta-analysis comparing repair using one screw versus repair with one high-tensile strength suture suggests that single high-tensile strength suture fixation may be biomechanically superior to single screw fixation. Another recent study found no difference between 2-screw and 2-suture fixation for TEFs.

Amidst all the evidence, it appears that the two fixation methods have similar biomechanics and clinical outcomes with a slight trend towards suture fixation over screw fixation of TEFs. Screw fixation provides a direct reduction of the TEF while suture fixation tensions the ACL itself with an indirect reduction of the fracture. Screw fixation may not be possible with thin bony or chondral fragments or with comminution of the fracture fragment. The senior author prefers suture fixation for the treatment of TEFs due to the versatility of the operative technique.

The workup of a TEF patient should begin with an anteroposterior and lateral radiograph. ( Fig. 1 ). Recently, a multicenter study corrobated prior studies that range from 40-68% of concomittant injuries including meniscal tears/entrapment and partial ACL tears (Shimberg [Tibial Spine Fractures: How Much are we missing] AJSM 2020). A pre-operative MRI is often utilized ( Fig. 2 ) to help look for these concomittant injuries and potentially influence operative or non-operative care.

Technique

The knee is prepped and draped for a standard arthroscopy. A standard anterolateral portal is established. Hemarthrosis and any hematoma is evacuated from the knee by cycling fluid through the cannula several times until the fluid becomes clear and visualization improves. A diagnostic arthroscopy is then performed, and an anteromedial portal is established under direct visualization close to the patellar tendon. Accessory portals can be utilized, the senior author prefers and uses a trans-patellar tendon portal in most cases. Any other intra-articular pathology is addressed using standard methods.

The tibial eminence fracture and fracture bed are identified within the intercondylar notch ( Fig. 3 A), with careful attention to any interposed intermeniscal ligament or medial meniscus. If there is interposed tissue, a probe can be utilized to pull the tissue out from between the fracture. Alternatively, outside-in traction sutures may be looped around the ligament or meniscus to allow for retraction of these structures prior to reduction of the fragment. A combination of curettes and shavers are then used to remove any fibrinous tissue or hematoma in the fracture bed ( Fig. 3 B). Often the authors remove some of the tibial bony bed to enable slight over-reduction of the fracture fragment may help to appropriately re-tension the ACL. The fracture fragment can then be held in place with an appropriately sized K-wire to obtain an initial reduction. The K-wire is inserted either percutaneously or through an accessory portal proximal to the anteromedial portal and as close to the patella as possible. It is aimed towards the middle of the fracture fragment, perpendicular to the plane of the fracture if possible. The intermeniscal ligament or meniscus is then allowed to return to its native position over the fragment. Occasionally, a K-wire may not be necessary to maintain the reduction ( Fig. 3 C).

An incision is then made over the anteromedial proximal tibia about 1 cm medial to the tibial tubercle and generally proximal to the pes anserinus. The periosteum of the proximal tibia is incised as the tunnels for suture passage for TEF fixation exit here. An ACL guide is used to identify the exit points on the tibial plateau on the medial and lateral borders of the TEF in the coronal plane and about the middle of the ACL in the sagittal plane. The guide is set to 55° on the medial side and 50° on the lateral side, allowing for differing tunnel trajectories with about a 1 cm bone bridge between the tunnels. The 2.4 mm guide pin is drilled on the lateral side first and the position confirmed arthroscopically. A Hewson suture retriever (Smith & Nephew, Warsaw, IN) is placed next to the 2.4 mm guide pin, and while the guide pin is slowly removed, the suture passer is placed into the bone tunnel ( Fig. 4 A). This step is repeated on the medial side. The loops from the suture passer should be visible on both sides of the TEF.