The normal value of alpha angle is controversial. The aim of this study was to compare the alpha angle in asymptomatic volunteers versus patients who had undergone surgery for symptomatic cam-type femoroacetabular impingement (FAI) and determine a diagnostic cut-off value for symptomatic cam impingement. This is a diagnostic test study. Cases were defined as those patients who had undergone surgery for symptomatic cam or mixed type FAI. Controls were defined as asymptomatic volunteers, with no history of hip pain who had undergone a computed tomography (CT) scan of the abdomen and pelvis for a non-joint or bone-related reason. In both groups, the alpha angle was measured in an oblique axial CT reconstruction of the femoral neck. A logistic regression model was first estimated and a receiver operating characteristics (ROC) curve was then calculated. The diagnostic cut-off value selected was the one that maximizes sensitivity and specificity. Data were analysed from 38 consecutive cases of cam or mixed FAI and 101 controls. The average alpha angle was 67°(±12°) among cases and 48°°(±5°) among controls. An odds ratio of 1.28 [1.18–1.39] was obtained. A ROC curve of 0.96 [0.93–0.99] was calculated, and using an alpha angle of 57° as the diagnostic cut-off value, provided a sensitivity of 92% and a specificity of 95%. If a patient complains of hip pain and an alpha angle of 57° is found in CT, strongly suggest that cam impingement is causing the pain.

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Objective: The purpose of the study was to evaluate early clinical and radiological results with a novel minimally invasive surgery (MIS) technique for Lapidus arthrodesis using intramedullary nail. Methods: Retrospective review of patients with hallux valgus surgery during an 18-month period. Patients with a procedure other than MIS Lapidus nail fixation were excluded. We describe surgical technique with a percutaneous joint preparation and fixation with an intramedullary nail through a MIS approach. Demographic variables, early complications and radiographic parameters were measured. Results: Ten feet in 8 patients with severe HV underwent a Lapidus procedure performed with a minimal invasive technique using intramedullary nail for fixation. No soft tissue complications and 1 patient required screw removal after bone healing. Mean HVA decreased from 31,4 degrees (range 17 to 47) SD (±9,3) to 10,3 degrees (range, -8,8 to 31,5) SD (±8,4), mean IMA decreased from 17,91 degrees (range, -17 to 20) SD (±0,9) to 5,46 degrees (range, –7,3 to 15.3) SD (±2,9) and mean DMAA decreased from 20,36 (range, 10-40) SD (±8,4) to 7,67 (range, -5 to 30) SD (±8,0). Conclusion: Intramedullary nail for Lapidus arthrodesis with minimally invasive technique showed satisfactory radiographic correction and minimal complications, but further follow up is needed to analyze clinical-radiographic results. Level of Evidence IV; Therapeutic Study; Case Series.

Level of Evidence: Level V.