COMPARISON OF PROPHYLACTIC IN-SITU SCREW FIXATION VERSUS OBSERVATION OF THE ASYMPTOMATIC CONTRALATERAL HIP IN SLIPPED CAPITAL FEMORAL EPIPHYSIS (SCFE)

Abstract

BACKGROUND: Prophylactic fixation of the asymptomatic, radiographically-normal contralateral hip after unilateral (SCFE) is controversial. Children with unilateral SCFE whose contralateral hip is observed are at risk for having a contralateral slip and associated complications such as avascular necrosis (AVN). On the other hand, prophylactic pinning may be an unnecessary surgery that may also result in substantial complications. A comparison of the two treatment options has not been performed. This study seeks to compare the outcomes and nature of complications of patients whose contralateral hip was observed with those whose hip underwent prophylactic in-situ screw fixation. METHODS: We retrospectively reviewed 197 patients treated for a unilateral SCFE over 20 years between the 1997 and 2017 at two hospitals. Medical records and x-rays were reviewed, and variables of interest included age, sex, body mass index (BMI), Modified Oxford Bone Age Score (MOBA) at presentation, length of operation, estimated blood loss (EBL), and length of hospitalization. Additionally, postoperative complications/outcomes such as reoperation in the unaffected hip, pain in the unaffected hip, AVN, chondrolysis, infection. abnormal gait (limp), reslipped epiphysis (growth off of the implanted screw), degenerative joint disease, and development of a limb length discrepancy were recorded. RESULTS: Of the 197 total patients (mean age 11.8) treated for unilateral SCFE, 100 (51%) received prophylactic fixation of their unaffected, contralateral hip and 97 (49%) were observed. Average follow up was 24.5 months. A statistically significant difference was found between groups for age, MOBA Score, EBL, and operative time. No difference was found between groups for BMI, BMI %ile, and length of hospitalization. The unilateral group was older (p<0.001) and had a greater MOBA Score (p=0.006) compared to the prophylactic group (Table 1). Patients in the prophylactic group had greater EBL during surgery (p=0.004) and longer operative time (p<0.001) compared to the unilateral group. In those patients whose contralateral hip was observed, 19% developed a contralateral SCFE which required later in-situ fixation. Amongst those, 2/19 (10%) developed AVN or chondrolysis of the contralateral hip (2% overall). For the contralateral hip, 17/97 (17%) developed hip pain, 10/97 (10%) developed a leg length difference and 24/97 (24%) developed a limp. In those patients who had prophylactic fixation, for the contralateral hip 2/100 (2%) developed AVN, (3/100) 3% required reoperation, 1/100 (1%) developed an infection, 10/100 (10%) developed contralateral hip pain, 4/100 (4%) developed a LLD, and 26/100 (26%) developed a limp. CONCLUSIONS: Surgeons and patients should be able to compare outcomes when deciding whether or not to prophylactically fix the asymptomatic contralateral hip in SCFE. For patients with unilateral SCFE, there are similar rates of AVN (2%) of the asymptomatic contralateral hip whether the hip is prophylactically pinned or observed. Between the two treatment options, there are similar outcomes for length of hospital stay, EBL, rate of infection and development of a limp. There is a higher rate of a LLD and the need for another operation in patients whose contralateral asymptomatic hip is observed, rather than prophylactically pinned. Table 1. Unilateral and Prophylactic Descriptive Statistics Unilateral (n=97) Prophylactic (n=100) P Sex Male 61 65 - Female 36 35 - Age (years) 12.4 11.3 <0.001* BMI 27.9 28.4 0.57 BMI Percentile 92.6% 93.5% 0.08 Modified Oxford Bone Age Score 20.6 19.6 0.006* Operative Time (minutes) 48.6 86.5 <0.001* Estimated Blood Loss (mL) 8.6 13.2 0.004* Length of Hospitalization (days) 1.0 1.1 0.28 Length of Follow-up (months) 27.7 21.3 - *Statistically significant difference between unilateral and prophylactic groups (p<0.05)