Evaluating the physical examination and diagnostic workup for occult Neck Of Femur fractures in a district general hospital.

BACKGROUND: Occult Neck of Femur (NOF) fractures are radiographically elusive injuries. Undiagnosed, they lead to delayed treatment, displacement, and increased morbidity. While MRI is the gold standard for detection, CT is frequently used when MRI is unavailable. Physical examination manoeuvres, specifically the hip log-roll (HR) and straight leg raise (SLR), are often employed to guide decisions regarding cross-sectional imaging. This study explores the utility of these physical examinations in guiding the workup for occult NOF fractures.

METHODS: A prospective service evaluation was performed at a 400-bed UK district general hospital (Jan 2023-Apr 2025). An electronic data-capture form integrated into CT/MRI requests identified 133 imaging requests ordered for suspected occult NOF fractures (120 CT and 14 MRI). Fifteen requests were cancelled (12 CT and 1 MRI out of a total 146 requests in 143 patients), and 14 CT Investigations related to suspected periprosthetic fracture were excluded from the primary native-hip analysis. Clinician-recorded results for HR, SLR, axial loading, and heel-percussion tests were compared against CT and MRI outcomes. Sensitivity, specificity, predictive values, and area under the ROC curve (AUC) were calculated for each test. A 4-point risk score (age > 70, female gender, positive HR, positive SLR) was evaluated for its discriminatory power.

RESULTS: CT confirmed 38 occult NOF fractures, with 4 further cases confirmed on MRI (including one initially missed on CT) and 3 on initial radiographic re-assessment. ). HR and SLR were performed in more than 95% of patients, demonstrating high sensitivities of 0.96 and 0.91, respectively, but low specificities (<0.35). Axial loading and heel percussion showed lower sensitivities (0.68 and 0.64). Combined HR + SLR yielded a fair AUC (0.68), which improved to 0.72 when age and gender were incorporated into the risk score.

CONCLUSIONS: In this setting, CT detected 97% of occult NOF fractures, missing only one micro-trabecular injury subsequently detected on MRI. The hip log roll and straight leg raise tests demonstrated high sensitivity but limited specificity, with improved performance when combined with demographic factors. These findings suggest that clinical examination manoeuvres are most useful for ruling out, rather than confirming, occult NOF fractures. Importantly, they reinforce the role of careful bedside physical examination in guiding appropriate imaging, particularly in an era of increasing reliance on radiological investigations.