Background

The aim of the study was to compare the bone mineral density changes between unmatched patients undergoing total hip arthroplasty receiving uncemented and cemented type of implants. Previous studies have used DEXA or a two dimensional analysis to estimate the bone quality following total joint replacement, whereas this study presents the changes in three dimensions.

Methods

Fifty subjects both male and females receiving both cemented and uncemented type of implant were recruited. Two CT scans were taken of each subject, the first at 24 h post surgery and the second one 1 year after surgery. The scans were calibrated using a phantom converting the Hounsfield units to bone mineral density values in g/cm³. The two scans were registered together using anatomical landmarks and resliced to compare the two femurs in the identical frame of reference. The bone density gain and loss was calculated by comparing density values between the two sets of scans.

Findings

The results showed that most of the bone loss was located around the Lesser Trochanter and some bone density gain at the distal tip of the implant. The three dimensional density changes occur differently between individuals and the study showed no correlation of bone loss with age.

Interpretation

The bone loss occurred mostly at the proximal femur, which is in agreement with previously presented studies. By carrying out three dimensional analysis on the bone gain and loss on the femur, it is possible to identify the patients that are showing high degree of bone loss.

中文翻译：

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在原发性全髋关节置换患者中，股骨在一年中的三维骨矿物质密度变化。

背景

该研究的目的是比较接受全骨和骨水泥型植入物的全髋关节置换术的不匹配患者之间骨矿物质密度的变化。先前的研究已经使用DEXA或二维分析来估计全关节置换后的骨质量，而本研究则提出了三个维度的变化。

方法

招募了五十名同时接受骨水泥和非骨水泥类型植入物的男性和女性受试者。对每位受试者进行两次CT扫描，第一次是在术后24小时，第二次是在术后1年。使用幻像将扫描进行校准，该幻像将Hounsfield单位转换为以g / cm ^3为单位的骨矿物质密度值。使用解剖学界标将这两次扫描记录在一起，并进行切片以比较同一参考系中的两个股骨。通过比较两组扫描之间的密度值来计算骨密度的增加和减少。

发现

结果表明，大部分骨丢失位于小转子周围，并且在植入物的远端有一些骨密度增加。个体之间的三维密度变化发生的方式不同，研究表明骨丢失与年龄没有相关性。

解释

骨丢失主要发生在股骨近端，这与先前提出的研究一致。通过对股骨的骨量增加和减少进行三维分析，可以识别出骨量高的患者。