Arthroscopic Treatment of Slipped Capital Femoral Epiphysis Screw Impingement and Concomitant Hip Pathology

Abstract

Impingement caused by screws used for stabilization of slipped capital femoral epiphysis can be treated arthroscopically. Although troublesome screws have traditionally been removed by open techniques, arthroscopic removal can successfully be achieved. In addition to affording the patient the benefits of minimally invasive surgery, surgeons also have the ability to arthroscopically address any concomitant hip pathology responsible for pain, including femoroacetabular impingement and labral tears.

Slipped capital femoral epiphysis (SCFE) is the most common form of hip pathology in adolescents, with consequential changes in anatomy predisposing the hip to further pathologic processes.^1-4 Both the deformity of the proximal femur and the hardware used to repair this defect can result in femoroacetabular impingement, causing prolonged pain and disability.^3-6 To our knowledge, there have been no studies describing the role of hip arthroscopy as an option to treat iatrogenic impingement in previously surgically corrected SCFE hips.

Surgical Technique

Patients may be given a lumbar plexus sciatic regional block to achieve regional anesthesia and are then brought to the operating room, where general anesthesia with complete paralysis is induced. Each patient was placed in the modified supine position on a fracture table (OrthoVision; Steris, Mentor, OH). Under fluoroscopic guidance, the operative hip was carefully and gently distracted, prepared, and draped according to standard protocol. Two primary working portals, anterolateral and modified anterior, were used. A 70° arthroscope was placed in the anterolateral portal, and dynamic assessment of the femoroacetabular articulation of the hip was conducted. Each pathologic hip showed abutment between the rim of the acetabulum and the SCFE screw (Figs 1 and 2). A hexagonal screwdriver (Smith & Nephew, Andover, MA) was then placed in the anterolateral portal. The screw (as well as the washer when applicable) was subsequently removed under direct visualization with the hip out of traction and positioned in 40° to 50° of flexion. Each screw was advanced one-quarter to one-half turn before removal. In one case a Nitinol guidewire (Smith & Nephew) was threaded through the cannulated portion of the screw to assist with removal. In one patient bony overgrowth over the screw head was visualized and required removal with a 5.5-mm burr, pituitary rongeur, and arthroscopic angulated elevator (Smith & Nephew) before screw removal. Fluoroscopy was used after screw removal to confirm that there was no evidence of retained hardware. Continued abutment of the head-neck junction with the acetabular rim was then addressed using an arthroscopic shaver and arthroscopic burr to achieve a gentle tapered femoroplasty without step-off or notching. The surgical technique is demonstrated in Video 1. Additional forms of pathology were also identified and subsequently addressed. Labral tears were repaired by the Iberian suture technique.⁸ If dynamic examination showed continued conflict between the acetabulum and femoral head, then additional decompression was performed along the acetabulum and femoral head-neck junction.

Fig 1.

(A) Anteroposterior and (B) lateral intraoperative radiographs of a left hip. Screw prominence is best demonstrated on the lateral radiograph (arrow) with decreased anterior femoral head-neck offset, possible screw cam formation, and cephalad retrograde acetabular morphology.

Fig 2.

(A) Preoperative and (B) intraoperative radiographs of a right hip showing early arthritis with the saber tooth sign⁷ (ST) and screw abutment against the acetabulum (arrow).

Postoperative rehabilitation was individualized based on the additional arthroscopic procedures performed, with protected weight bearing for all patients for 2 weeks to 8 weeks based on the treatment of concomitant pathology.

Discussion

Impingement resulting from surgical fixation of SCFE was recognized as early as 1936 and until recently has been treated by open procedures.⁹ As hip arthroscopy has gained popularity over the past few decades, the indications for arthroscopic treatment of hip pathology have grown exponentially, including treatment of pathology associated with the pediatric hip.⁵ Stabilization with in situ single-screw fixation is currently the recommended treatment for SCFE to prevent slippage progression.^1,6 Stabilization alone, however, may not relieve symptoms completely. Femoroacetabular impingement can be due to the deformity of the proximal femur associated with SCFE but may also develop as a consequence of the treatment.^1,4,6 Goodwin et al.⁶ showed that the head of the screw could abut with the acetabular rim in the case of an 11-year-old girl and 2 cadaveric hips. They proposed screw placement lateral to the intertrochanteric line as opposed to perpendicular to the physis as a potential method to reduce the risk of ensuing impingement, but they recognized that this is not always possible.

Leunig et al.³ presented 3 cases in which they performed simultaneous correction of both the capital alignment and its associated impingement. They performed in situ fixation of the SCFE followed by immediate arthroscopic osteoplasty to eliminate the prominence of the anterior metaphysis and reshape the femoral head-neck junction. Although all 3 patients had positive outcomes, Leunig et al. recognized that the arthroscopic correction of deformity is technically difficult. Consequently, they recommended that the procedure should only be performed by an experienced hip arthroscopist and not necessarily by the surgeon performing the pinning, which may not always be feasible. Furthermore, although immediate osteoplasty may correct the associated anatomic pathologic impingement, thereby eliminating the need for additional femoroplasty, it cannot address the potential iatrogenic impingement caused by a prominent screw head. Traditionally, these problematic screws have been removed by open techniques; however, we believe that the described arthroscopic technique yields better clinical outcomes because it allows offending hardware removal in a minimally invasive manner. The specific advantages and disadvantages of arthroscopic screw removal are detailed in Table 1. Further studies are required to determine its long-term efficacy regarding patient return to function and development of osteoarthritis.

Table 1.

Advantages and Disadvantages of Arthroscopic Removal of SCFE Screws

Advantages	Disadvantages
Ability to address concomitant hip pathology	Risks of hip distraction
Direct visualization	Screw breakage
Minimize need for intraoperative fluoroscopy	Failure of removal
Dynamic examination	Learning curve of arthroscopy

Supplementary Data

Video 1

Technique for arthroscopic treatment of SCFE screw impingement and concomitant hip pathology, showing screw removal, labral repair, and femoroacetabular decompression.