Dowd J E, Sychterz C J, Young A M, Engh C A
Orthopaedic Associates of Virginia, Norfolk 23502, USA.
J Bone Joint Surg Am. 2000 Aug;82(8):1102-7. doi: 10.2106/00004623-200008000-00006.
We examined the relationship between long-term femoral-head-penetration patterns and osteolysis in a ten-year follow-up study of a well controlled patient population. The purposes of this study were to characterize the linearity of long-term head-penetration patterns over time, to describe the relationship between ten-year true wear rates and osteolysis, and to determine whether the occurrence of osteolysis at ten years could be predicted by penetration data obtained prior to five years.
Temporal femoral-head-penetration patterns were examined at a minimum of ten years after forty-eight primary total hip arthroplasties. The arthroplasties were performed with the use of an Arthropor acetabular cup (Joint Medical Products) and a thirty-two-millimeter-diameter cobalt-chromium femoral head (DePuy). Using a computer-assisted radiographic technique, we evaluated two-dimensional head penetration on serial annual radiographs. Linear regression analysis modeled penetration-versus-time data as a line for each patient. The slope of the regression line indicated the true wear rate for each patient. In a subgroup of thirty-four hips for which three annual radiographs had been made less than five years after the arthroplasty, we compared early head-penetration patterns with the later occurrence of osteolysis.
For all forty-eight hips, the true wear rate averaged 0.18 millimeter per year (range, 0.01 to 0.44 millimeter per year) and temporal head-penetration patterns tended to be linear (mean r2 = 0.91 +/- 0.16). Osteolysis at ten years was strongly associated with increasing true wear rates (p < 0.001). Osteolysis did not develop in any of the nine hips with a true wear rate of less than 0.1 millimeter per year. However, osteolysis developed in nine (43 percent) of twenty-one hips with a rate between 0.1 and less than 0.2 millimeter per year, in eight of ten hips with a rate between 0.2 and 0.3 millimeter per year, and in all eight hips with a rate of greater than 0.3 millimeter per year. Evaluation of early true wear rates as a predictor of late osteolysis showed a similar relationship.
This study demonstrates that true wear rates tend to be constant and that increased true wear is significantly associated with osteolysis at ten years after the operation. A similar relationship was also found at the early follow-up interval, indicating that early true wear rates (determined from serial radiographs) might enable orthopaedists to predict if patients are at risk for the development of osteolysis.
On the basis of these findings, we use temporal femoral-head-penetration data in our practice to evaluate polyethylene inserts in asymptomatic patients, to estimate the time to component wear-through, and to adjust the frequency of follow-up evaluations for monitoring the development of osteolytic lesions in at-risk patients.
在一项对病情控制良好的患者群体进行的十年随访研究中，我们研究了长期股骨头穿透模式与骨溶解之间的关系。本研究的目的是描述长期股骨头穿透模式随时间的线性特征，描述十年真实磨损率与骨溶解之间的关系，并确定能否通过五年前获得的穿透数据预测十年时骨溶解的发生情况。
在四十八例初次全髋关节置换术后至少十年时检查股骨头穿透的时间模式。使用Arthropor髋臼杯（联合医疗产品公司）和直径32毫米的钴铬合金股骨头（迪普伊公司）进行关节置换。我们采用计算机辅助放射技术，在每年的系列X线片上评估二维股骨头穿透情况。线性回归分析将每位患者的穿透-时间数据模拟为一条直线。回归线的斜率表明每位患者的真实磨损率。在一个亚组中，对三十四例在关节置换术后五年内拍摄了三张年度X线片的髋关节，我们比较了早期股骨头穿透模式与后期骨溶解的发生情况。
对于所有四十八例髋关节，真实磨损率平均为每年0.18毫米（范围为每年0.01至0.44毫米），股骨头穿透的时间模式倾向于呈线性（平均r2 = 0.91±0.16）。十年时的骨溶解与真实磨损率增加密切相关（p < 0.001）。真实磨损率低于每年0.1毫米的九个髋关节中，无一例发生骨溶解。然而，真实磨损率在每年0.1至低于0.2毫米之间的二十一例髋关节中有九例（43%）发生了骨溶解，在每年0.2至0.3毫米之间的十例髋关节中有八例发生了骨溶解，在每年大于0.3毫米的所有八例髋关节中均发生了骨溶解。将早期真实磨损率作为晚期骨溶解的预测指标进行评估，显示出类似的关系。
本研究表明，真实磨损率往往是恒定的，真实磨损增加与术后十年的骨溶解显著相关。在早期随访期间也发现了类似的关系，这表明早期真实磨损率（根据系列X线片确定）可能使骨科医生能够预测患者是否有发生骨溶解的风险。
基于这些发现，我们在临床实践中利用股骨头穿透时间数据来评估无症状患者的聚乙烯内衬，估计部件磨损殆尽的时间，并调整随访评估的频率，以监测有风险患者溶骨性病变的发展。
