Treatment Outcomes at Skeletal Maturity After Physeal-sparing Procedures for Early-onset Slipped Capital Femoral Epiphysis Using a Long Screw With a Short-threaded Tip.

Background: Physeal-sparing procedures are preferred for treating early-onset slipped capital femoral epiphysis (SCFE), reducing limb-length discrepancy (LLD), and femoroacetabular impingement (FAI). This study aimed to investigate the treatment outcomes after physeal-sparing procedures for early-onset SCFE.

Methods: We reviewed medical and radiographic records of SCFE patients from 1992 to 2022. Patients under 11 years old and followed up to skeletal maturity were included. Physeal-sparing procedures using a long screw with a short-threaded tip were performed in patients with mild to moderate slips since 2008. Patients were dichotomized into physeal-sparing and traditional in situ fixation (ISF) groups. Radiographic and clinical outcomes were comparatively analyzed between the groups.

Results: Fifteen patients underwent physeal-sparing procedures, whereas 12 patients underwent traditional ISF. There was no further slippage in either group. During follow-up, slip angle was significantly decreased in the physeal-sparing group compared with the traditional ISF group (22.0 vs. 8.8 deg, respectively, P<0.01). LLD of>20 mm did not occur in the physeal-sparing group, but was observed in the traditional ISF group (P<0.01). Femoral neck length (FNL), articulo-trochanteric distance (ATD), α angle, and femoral head-neck offset of the physeal-sparing side were comparable to the unaffected healthy side (P=0.08, P=0.25, P=0.14, P=0.13), but differences were seen in healthy versus traditional ISF sides (P<0.01, P<0.01, P<0.01, and P<0.01, respectively). In addition, consistent growth was observed in the physeal-sparing side, but premature physeal arrest developed in the traditional ISF side. Six physeal-sparing patients required screw change procedures as the proximal femur outgrew the screw. The physeal-sparing group scored higher modified Harris Hip Score points than the traditional ISF group (89.5 vs. 85.3, respectively).

Conclusions: Using a long screw with a short-threaded tip can stabilize the proximal femoral physis. It may also allow the continual growth and remodeling of the proximal femur in the treatment of early-onset SCFE.

Level Of Evidence: Level III.