Yuan Brandon J, Shamaa Mohamad Tayseer, Aibinder William R, Parry Joshua A, Cross William W, Barlow Jonathan D, Sems Stephen A
Department of Orthopaedic Surgery, Mayo Clinic, Rochester, MN, USA.
Department of Orthopaedic Surgery, State University of New York Downstate Health Sciences University, New York City, NY, USA.
Eur J Orthop Surg Traumatol. 2020 Dec;30(8):1417-1420. doi: 10.1007/s00590-020-02717-z. Epub 2020 Jun 15.
Cadaveric models have demonstrated a high incidence of extraosseous "in-out-in" (IOI) posterosuperior screws after cannulated screw fixation of femoral neck fractures. The purpose of this study was to determine the incidence of IOI screws in vivo and to evaluate their association with osteonecrosis and revision surgery.
A total of 104 patients with 107 hips with a pelvis computed tomography (CT) scan after cannulated screw fixation of a femoral neck fractures were included. Screw position was evaluated on postoperative radiographs and CT scan to determine if screws were IOI or all-in. Osteonecrosis and revision surgeries were documented.
IOI posterosuperior screws were identified on CT scan in 58 (54%) hips. On postoperative AP and lateral radiographs, IOI screws were a median (interquartile range) of 10 mm (7-11 mm) and 3 mm (0-4 mm) from the cortex, respectively. The sensitivity and specificity of radiographs to detect IOI screws was 39% and 92%, respectively. The incidence of osteonecrosis and revision surgeries in hips, with and without IOI screws, was 6% versus 6% [Odds ratio (OR) 1.1, 95% confidence interval (CI) 0.2-5.3] and 10% versus 10% (OR 1.0, CI 0.3-3.1), respectively; a true clinical difference cannot be excluded due to the width of the confidence intervals.
There was a high incidence of IOI posterosuperior screws on CT scans. Postoperative radiographs had a poor sensitivity for detecting IOI screws. A larger sample size is necessary to evaluate the association of IOI screws with osteonecrosis and revision surgery.
Level III, comparative cohort study.
尸体模型显示，股骨颈骨折空心螺钉固定后，骨外“进出进”（IOI）后上方螺钉的发生率很高。本研究的目的是确定体内IOI螺钉的发生率，并评估其与骨坏死和翻修手术的相关性。
共纳入104例患者的107髋，这些患者在股骨颈骨折空心螺钉固定后均进行了骨盆计算机断层扫描（CT）。通过术后X线片和CT扫描评估螺钉位置，以确定螺钉是否为IOI型或全入骨型。记录骨坏死和翻修手术情况。
CT扫描发现58髋（54%）存在IOI后上方螺钉。在术后前后位和侧位X线片上，IOI螺钉距皮质的中位数（四分位间距）分别为10 mm（7 - 11 mm）和3 mm（0 - 4 mm）。X线片检测IOI螺钉的敏感性和特异性分别为39%和92%。有和没有IOI螺钉的髋部骨坏死和翻修手术的发生率分别为6%对6% [比值比（OR）1.1，95%置信区间（CI）0.2 - 5.3]和10%对10%（OR 1.0，CI 0.3 - 3.1）；由于置信区间较宽，不能排除真正的临床差异。
CT扫描显示IOI后上方螺钉的发生率很高。术后X线片检测IOI螺钉的敏感性较差。需要更大的样本量来评估IOI螺钉与骨坏死和翻修手术的相关性。
III级，比较队列研究。
