Outcome differences between conversion to THA for traumatic ONFH after failed internal fixation and primary THA for nontraumatic ONFH in patients under 55: a retrospective case-control study.
Level 4 - case-series / case-control
Retrospective case-control study
PubMed 42026614 · doi:10.1186/s12891-026-09844-4
What was done
A retrospective comparative study evaluated 292 patients aged 18 to 55 years who underwent total hip arthroplasty (THA) between January 2013 and August 2022. The study compared 146 patients undergoing conversion THA (CTHA) for secondary osteonecrosis of the femoral head (ONFH) after failed internal fixation of femoral neck fractures with 146 patients undergoing primary THA for nontraumatic ONFH. Outcomes evaluated over a mean follow-up of 5.5 years included perioperative metrics (operative time, blood loss), complication rates, radiographic cup positioning (acetabular anteversion and abduction angles), Harris Hip Scores, and implant survival rates.
What was found
The conversion group experienced a significantly higher rate of intraoperative periprosthetic fractures compared to the primary THA group (5.5% vs. 0.7%, P = 0.039) and had a 6.8% positive bacterial culture rate from routine postoperative secretion testing. CTHA also required longer operative times (1.3 ± 0.47 vs. 1.0 ± 0.24 hours, P < 0.001) and had greater blood loss (143.2 ± 135.2 vs. 112.7 ± 41.1 mL, P = 0.007). However, mid-term functional and radiographic outcomes were equivalent: there were no statistically significant differences in final Harris Hip Scores (90.4 ± 4.5 vs. 89.7 ± 3.6, P = 0.134), implant survival rates (> 93% for both, P = 0.607), acetabular anteversion (P = 0.255), or abduction angles (P = 0.948).
Why it matters
Patients under 55 requiring conversion THA after failed internal fixation face increased technical surgical hazards—including higher intraoperative fracture rates and occult infection risks—but achieve mid-term implant survival and functional recovery comparable to primary THA.
Limits
The study relies on a retrospective observational design with inherent potential for confounding and selection bias. Follow-up averaged 5.5 years, precluding assessment of long-term component survival beyond 10 years. Specific details regarding original fixation hardware, exact surgical approach, and management of culture-positive cases are omitted from the abstract.
Cited by
- supports Disruption of blood supply following a femoral neck fracture leads to avascular necrosis necessitating a total hip replacement.