Beverlie L Ting1, Marilyn Heng, Mark S Vrahas, Edward K Rodriguez, Mitchel B Harris, Michael J Weaver. 1. *Department of Orthopedic Surgery, Harvard Medical School Orthopedic Trauma Initiative, Brigham and Women's Hospital, Boston, MA; †Department of Orthopaedic Surgery, Harvard Medical School Orthopedic Trauma Initiative, Massachusetts General Hospital, Boston, MA; and ‡Department of Orthopedics, Harvard Medical School Orthopedic Trauma Initiative, Beth Israel Deaconess Medical Center, Boston, MA.
Abstract
OBJECTIVES: Avascular necrosis (AVN) of the femoral head is a devastating complication following fixation of femoral neck fractures in younger adults. In this study, we investigate the prognostic utility of disuse osteopenia. DESIGN: Retrospective study. SETTING: Three academic Level 1 trauma centers. PATIENTS: One hundred twenty patients younger than 60 years treated for a femoral neck fracture. INTERVENTION: N/A. MAIN OUTCOME MEASURES: The presence of sclerosis or osteopenia, compared to the contralateral femoral head, was measured 6 weeks from injury both subjectively and using a novel radiographic measure, the relative density ratio (RDR). The outcome measure was radiographic development of AVN. RESULTS: The presence of relative sclerosis was associated with AVN and overall treatment failure. Patients with subjective relative sclerosis had a 12.6 (95% confidence interval, 2.9-61.3; P < 0.001) times higher odds of developing AVN. Multiple logistic regression showed that for every 0.10 increase in the RDR, there was a 5.2 increase in the odds (95% confidence interval, 2.1-26.9; P = 0.009) of developing AVN. Patients with an RDR of ≥1.2 have an 80% probability of AVN, whereas those with an RDR ≤0.8 have a <1% probability of developing AVN. CONCLUSIONS: Disuse osteopenia detected on 6-week radiographs is a favorable prognostic sign following fixation of femoral neck fractures. Patients who have relative sclerosis of the femoral head at 6-week follow-up are at a higher risk of developing AVN. LEVEL OF EVIDENCE: Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.
OBJECTIVES:Avascular necrosis (AVN) of the femoral head is a devastating complication following fixation of femoral neck fractures in younger adults. In this study, we investigate the prognostic utility of disuse osteopenia. DESIGN: Retrospective study. SETTING: Three academic Level 1 trauma centers. PATIENTS: One hundred twenty patients younger than 60 years treated for a femoral neck fracture. INTERVENTION: N/A. MAIN OUTCOME MEASURES: The presence of sclerosis or osteopenia, compared to the contralateral femoral head, was measured 6 weeks from injury both subjectively and using a novel radiographic measure, the relative density ratio (RDR). The outcome measure was radiographic development of AVN. RESULTS: The presence of relative sclerosis was associated with AVN and overall treatment failure. Patients with subjective relative sclerosis had a 12.6 (95% confidence interval, 2.9-61.3; P < 0.001) times higher odds of developing AVN. Multiple logistic regression showed that for every 0.10 increase in the RDR, there was a 5.2 increase in the odds (95% confidence interval, 2.1-26.9; P = 0.009) of developing AVN. Patients with an RDR of ≥1.2 have an 80% probability of AVN, whereas those with an RDR ≤0.8 have a <1% probability of developing AVN. CONCLUSIONS:Disuse osteopenia detected on 6-week radiographs is a favorable prognostic sign following fixation of femoral neck fractures. Patients who have relative sclerosis of the femoral head at 6-week follow-up are at a higher risk of developing AVN. LEVEL OF EVIDENCE: Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.