Using an Intraoperative Stress Examination to Direct Treatment in Posterior Femoral Head Fracture-Dislocations

OBJECTIVE: To examine the results of a treatment algorithm incorporating an examination under anesthesia (EUA) performed intraoperatively after fixation of the femoral head through a Smith-Petersen approach to determine the need for posterior wall or capsule repair. Design: Retrospective review. Setting: Two Level 1 trauma centers. Patient Selection Criteria: All acute, traumatic femoral head fractures from posterior hip dislocations treated at participating centers over a 5-year period from 2017 to 2022. Injuries were classified according to the Pipkin system. Outcome Measures and Comparisons: The primary outcome was the result of intraoperative EUA performed after femoral head fixation to determine the need for Kocher-Langenbeck exposure for posterior wall and/or capsule fixation. The secondary outcomes included rates of avascular necrosis, heterotopic bone formation, late instability, and conversion to total hip arthroplasty (THA). RESULTS:In total, 63 men and 22 women with a mean age of 32.5 (range 18-71) years were studied. Seventy-nine of 85 (92.9%) patients had a stable EUA after fixation of the femoral head through a Smith-Petersen approach. Six (6/85, 7.1%) underwent an additional Kocher-Langenbeck approach for posterior wall or capsule fixation. This included 1 Pipkin I, 1 Pipkin II, and 4 Pipkin IV injuries. Of the Pipkin IV injuries, 51/55 (92.7%) had stable EUA and did not require fixation of their posterior wall. This included seven patients with wall involvement >20%. Five patients were excluded because of planned fixation of their posterior wall based on preoperative imaging. Of patients with at least 6 months follow-up, 16 of 65 (26.4%) developed radiographic evidence of avascular necrosis and 21 of 65 (32.3%) evidence of heterotopic bone formation. Seven out of 65 (10.8%) were converted to THA over the study period. When comparing patients with a single exposure and those with additional KL exposure, it was found that they did not vary in their rate of avascular necrosis (27.1% vs. 0.0%, P = 0.3228), heterotopic ossification formation (30.5% vs. 50.0%, P = 0.3788), or conversion to THA (10.2% vs. 16.7%, P = 0.510). CONCLUSIONS:This study found residual posterior hip instability after femoral head fixation in patients with and without posterior wall fractures after posterior dislocations. The results of this study support the use of an EUA after femoral head fixation to identify residual posterior hip instability in all femoral head fractures from posterior hip dislocations, regardless of Pipkin type. Use of the Smith-Petersen exposure remains a viable surgical option and may be improved with the incorporation of an EUA after femoral head fixation. For Pipkin IV injuries with posterior wall fractures with indeterminate stability, an EUA accurately identifies residual instability. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.