대퇴 삽입물 주위 골절로 오인될 수 있는 대퇴부 영양 동맥관

Abstract

Introduction: Periprosthetic fractures caused by impact of the stem tip to the femur shaft may not be found during procedure and may be incidentally detected through postoperative plain radiographs. These fractures are difficult to distinguish with the nutrient artery canals(NACs) of the femur as the nutrient canal could be misrecognized as a fracture. We intend to analyze the radiological properties of NACs and set rules to distinguish them from true fractures.

Methods: In a retrospective radiological study on 242 cases of 215 patients with total hip replacement or bipolar hemi-arthroplasties between May 2007 and April 2012 were examined. 97 (40.1%) patients were male, 145 (60.0%) were female and their average age were 68.2 (27~95) years. We analyzed preoperative and postoperative anteroposterior and cross table lateral radiographs.

Results: 94 (39.8%) of 242 cases showed radiolucent lines compatible with NACs by preoperative anteroposterior radiographs and 122 cases (50.4%) showed NACs by preoperative cross table lateral radiographs. 63 (26.0%) of 242 cases showed NACs on both projections. The average distance between the tip of the greater trochanter and the proximal end of NAC was 161±36 mm. Most of the NACs were vertical type ranging within 10 degrees of the anatomical axis of the femur. They were mostly extending upward at the posterior cortex on cross table lateral radiographs. We could divide the NACs into two types: proximal and distal. Proximal type had a gentle angulation with an angle of 23.9±6.0° to the central line. Distal type extended upward at a steeper angle of 11.8±5.9° to the central line. One case was suspected of a fracture postoperative image and with a follow up imaging, radiolucent line diminished, leading us to assume a true fracture.

Conclusion: Along and within the NACs, true periprosthetic fractures could be missed as a normal finding. Differentiation of the fractures is crucial, because the overlooked fractures may affect the entire prognosis. NACs are mostly observed with a smoother border, sclerotic wall along the canal, and are seen at one side of the cortex. However true fractures have a sharp fracture line, involve the ipsilateral cortex and may diminish with follow-up images.

Keywords: hip arthroplasty, nutrient artery canal, periprosthetic fracture