Biomechanical Evaluation of the Depth of Resection During Femoral Neck Osteoplasty for Anterior Impingement Following Slipped Capital Femoral Epiphysis

Is there a role for controlled repositioning and mini-open primary osteoplasty in the management of unstable slipped capital femoral epiphysis?

The management of unstable slipped capital femoral epiphysis is controversial with variable rates of avascular necrosis (AVN). Treatment options include in-situ stabilization, gentle/positional reduction and screw fixation and modified Dunn's procedure (MDP). We present a technique of controlled repositioning (CRP) of the epiphysis to pre-acute slip stage, screw fixation and primary osteoplasty. Between 2015 and 2020, 38 unstable slips were treated in our institution. Of these, 14 underwent successful CRP and the rest were treated with MDP. All the 14 patients who had CRP and completed 1-year follow-up were included for this study. The head-neck angle (HNA) was measured at presentation and alpha angle, head-neck offset and AVN were assessed during follow-up. The average age was 14 years (9-18) and mean follow-up was 17.7 months (12-43). The average intraoperative flexion internal rotation before osteoplasty was -18.5° (-40° to -5°) which improved to +22.1° (+15° to +30°). The average preoperative HNA was 48.7° (34.1° to 70.7°) which improved to 18.4° (1.8° to 35.7°) post-operatively. At final follow-up, the average alpha angle and head-neck offset were 46.4° (30.9° to 64.6°) and 0.22 (0.09 to 0.96), respectively. The AVN rate in the CRP group was 7.1% compared with 20.8% in the MDP group, which was not significant (P = 0.383). Two patients had screw breakage. CRP, screw fixation and mini-open primary osteoplasty is a feasible treatment option in a subgroup of patients with unstable SCFEs. The limitation with this technique is that the final decision is made intraoperatively, and hence the patient and parents need to be counselled and consented appropriately. Level of evidence: Level IV-Case series.

OSTEOTOMY AT THE BASE OF FEMORAL NECK AND OSTEOPLASTY FOR THE TREAMENT OF SCFE

ABSTRACT Objective: To compare the clinical outcomes between patients with moderate and severe slipped capital femoral epiphysis (SCFE) treated with osteotomy at the base of neck and osteoplasty and with healthy individuals. Methods: Comparative cohort with 12 patients (14 hips) with moderate and severe SCFE who underwent osteotomy at the base of neck and osteoplasty between 2007 and 2014. The mean age at surgery was 13.3 ± 2.5 years and the mean follow-up was 3.8 ± 2.2 years. We assessed the level of hip pain by the visual analog scale (VAS) and anterior impingement test (AIT); the level of function using the Harris Hip Score (HHS) and 12-Item Short Form Health Survey (SF-12), the range of motion (ROM) by goniometry and Drehmann sign, and the hip muscular strength by isokinetic and Trendelenburg sign. Results: The level of pain was slightly higher in the SCFE cohort compared with healthy hips (VAS, 0.8 ± 1.4 vs 0 ± 0, 0.007; AIT, 14% vs 0%, p = 0.06; respectively). No differences were observed between the SCFE and control cohort for the functional scores (HHS, 94 ± 7 vs 100 ± 1, p = 0.135); except for ROM, with increased internal rotation (37.3º ± 9.4º vs 28.7º ± 8.2º, p < 0.001), and strength, with decreased abduction torque (75.5 ± 36.9 Nm/Kg vs 88.5 ± 27.6 Nm/Kg, p = 0.045) in the SCFE cohort. Conclusion: The osteotomy at the base of neck and the osteoplasty restored the hip motion and muscle strength, except for the abductor strength, to near normal levels, representing a viable option for the treatment of moderate and severe SCFE. Level of Evidence III, Ambidirectional Cohort Study.

The effect of the hip impact configuration on the energy absorption provided by the femoral soft tissue during sideways falls

The femoral soft tissue (i.e., skin, muscle, fat) may play a key role in preventing hip fractures during a fall by absorbing the impact energy. We measured the femoral soft tissue deformation and associated compressive force during simulated sideways falls to estimate the energy absorbed by the soft tissue, and then examined how this was affected by the hip impact configuration and gender. Eighteen young adults (9 males and 9 females) participated in the pelvis release experiment. The pelvis was raised through a rope attached to an electromagnet on the ceiling, so the skin surface barely touches the ultrasound probe, which flush to a Plexiglas plate placed on a force plate. The electromagnet was turned off to cause a fall while the soft tissue deformation and associated compressive force were being recorded. Trials were acquired with three hip impact configurations. An outcome variable included the energy absorbed by the femoral soft tissue during a fall. The energy absorbed by the femoral soft tissue ranged from 0.03 to 3.05 J. Furthermore, the energy absorption was associated with the hip impact configuration (F = 4.69, p = 0.016). On average, the absorbed energy was 62% greater in posteriolateral than anteriolateral impact (0.92 versus 0.57 J). However, the energy absorption did not differ between male and female (F = 0.91, p = 0.36). The force-deflection behavior of the femoral soft tissue during a fall has been recorded, providing insights on the potential protective benefits of the soft tissue covering during a fall.