Use of a Multiaxial Surgical Support Arm for Hip Joint Distraction in the Fixation of Acetabulum Fractures Through a Kocher-Langenbach Approach: A Technical Note

Acetabular fractures most commonly occur after high-energy trauma in young adults and can lead to substantial long-term morbidity. The goals of acetabulum open reduction internal fixation (ORIF) are restoration of hip joint congruity and stability with anatomic reduction of the weight-bearing dome.1,2 Marginal and dome impaction injuries represent severe forms of articular damage and are particularly prone to early arthritis if not disimpacted and anatomically reduced.3 Lack of restoration of the joint surface and lack of removal of loose debris from the hip joint can lead to significant complications, such as advancement of arthritic changes.1–5 Through a Kocher-Langenbeck (KL) approach, intraoperative distraction of the hip joint increases the working space between the femoral head and the acetabular articular surface, which facilitates removal of incarcerated fragments and can reduce protrusio when present.5 However, sustained manual traction is labor-intensive and difficult to maintain during intra-articular debridement and reconstruction. Compared with manual traction, a locked mechanical construct maintains distraction during disimpaction and plate application without fatigue or loss of force. Several methods have been described to obtain intraoperative traction and joint distraction during acetabular ORIF. Traction tables and simple intraoperative traction devices can provide sustained longitudinal traction but may be costly or unavailable in some centers, and can limit access to the posterior column.5 Often, surgeons may be limited by the number of available assistants to help with distraction. This surgical technique paper describes the use of a common surgical support arm to provide hip joint distraction during acetabular ORIF in the KL approach. This technique provides distraction of the hip joint without additional surgical assistants, which may provide significant benefit for acetabular surgeons. TECHNIQUE This technique is used to distract the hip joint during the KL surgical approach. The patient is placed in the lateral decubitus position on a radiolucent table with a bean bag or similar radiolucent support, with the surgical side up. The surgical support arm (Trimano, Arthrex Inc., Naples, FL) is mounted on the radiolucent table rail, anterior to the patient at the level of the knee joint. The surgical support arm and patient are draped in a sterile fashion. A KL approach is performed. The posterior wall and/or column fracture are exposed. Under fluoroscopic guidance, a starting point is selected on the lateral cortex of the proximal femur at the level of the vastus ridge using a 5.0 mm Schanz pin, aiming 20 to 30 degrees cephalad in the coronal plane, centered along the axis of the femoral neck. The Schanz pin is advanced toward the center of the femoral head, and placement is confirmed on the anteroposterior and lateral views. Care is taken to avoid intra-articular overpenetration, excessive varus or valgus angulation, and repeated attempts at insertion. A universal T-handle instrument is attached to the Schanz pin. Sterile rope is then tied from the support arm to the T-handle. Figure 1 shows the femoral attachment to the surgical arm.Figure 1: Visualization of the surgical field demonstrating the 5.0 mm Schanz pin inserted through the lateral femur, which is attached to the universal T-handle and sterile rope.The support arm is then pulled superiorly in line with the femur to create distraction and allow for visualization of the hip joint, and is then locked in place. Figure 2 shows the complete support arm setup. Whether through direct visualization or fluoroscopic imaging, lateralization of the femoral head can then be confirmed.Figure 2: Complete set-up of the surgical support arm with attachment to the femoral side for distraction of the hip joint. The surgical support arm is currently on the anterior side of the patient, to remain out of the working posterior aspect of the surgical field.With distraction maintained by the locked support arm, incarcerated intra-articular fragments are removed, and any protrusio deformity is reduced. Distraction can be subtly adjusted during these maneuvers by small changes in the support arm height or angle, without relying on manual traction. Intermittent partial release of distraction may be helpful while applying clamps or inserting screws, after which the support arm can be relocked to maintain joint space as needed. When distraction is no longer needed, the support arm is lowered to release distraction and restore the limb to neutral alignment. Expected Outcomes There are multiple advantages of this technique. The principal advantages of the current technique are its reliance on operating room equipment available at most hospitals and surgery centers, elimination of the need for a traction table or dedicated distractor, and reduction of the demand for manual traction by assistants. All is beneficial to both the community and the academic surgeon. This technique allows for fine adjustment and maintenance of distraction while articular work and definitive fixation are performed. This allows for excellent visualization of the articular surface. Although described here for a KL approach, this technique could theoretically be applied to other acetabular approaches and patient positions. Complications Currently, there have been no complications with this technique; however, theoretical disadvantages or complications may exist. Potential disadvantages include the need to place Schanz pins in the femoral neck and the risk of contamination of the operative field during device setup. CONCLUSION Use of a surgical support arm attached to a femoral neck Schanz pin provides a practical, reproducible method for controlled hip joint distraction during acetabular fracture fixation through a KL approach. This construct uses equipment readily available in many operating rooms. This technique may be especially helpful to community surgeons performing acetabular ORIF cases or to hospitals with limited strong assistants.