Akhavan Sam, Matthiesen Mary M, Schulte Leah, Penoyar Tom, Kraay Matthew J, Rimnac Clare M, Goldberg Victor M
University Hospitals of Cleveland, 11100 Euclid Avenue, Hanna House 6, Cleveland, OH 44106, USA.
J Bone Joint Surg Am. 2006 Jun;88(6):1308-14. doi: 10.2106/JBJS.E.00316.
Osteolysis secondary to stress shielding in patients with a total hip arthroplasty has been attributed to greater stiffness of the prosthetic femoral stem compared with the stiffness of the femur. This concern led to the development of a composite femoral stem implant with a structural stiffness similar to that of the native femur. The stem consists of a cobalt-chromium-alloy core surrounded by polyaryletherketone and titanium mesh for bone ingrowth. The purpose of this study was to determine the intermediate-term clinical, radiographic, and histologic results of the use of this stem.
Twenty-eight patients (nineteen men and nine women) with an average age of 51.3 years underwent primary total hip arthroplasty with the Epoch stem and were followed for an average of 6.2 years. Harris hip scores were determined and radiographic studies were performed preoperatively, postoperatively, and at two-year intervals thereafter. In addition, dual x-ray absorptiometry scans were made up to two years postoperatively to evaluate osseous resorption. Two femora obtained at autopsy thirteen and forty-eight months after surgery were analyzed for bone ingrowth and ongrowth.
The Harris hip scores averaged 56 points preoperatively and improved to 97 points at the time of the last follow-up. Dual x-ray absorptiometry scans demonstrated the greatest decrease in mean bone density (27.5%) in Gruen zone 7 at two years. Radiographs demonstrated no instances of migration, and only one hip had osteolysis. All stems had stable osseous fixation. Histologic evaluation of the two femora that had been retrieved at autopsy at thirteen and forty-eight months showed the mean bone ingrowth (and standard deviation) along the entire length of the stem to be 49.62% +/- 13.04% and 73.57% +/- 8.48%, respectively, and the mean bone ongrowth to be 54.18% +/- 7.68% and 80.92% +/- 6.06%, respectively.
Intermediate-term follow-up of hips treated with the Epoch stem indicated excellent clinical success, radiographic evidence of osseous integration, and histologic findings of osseous ingrowth and ongrowth. Although the implant has been associated with excellent results in both the short and the intermediate term, longer follow-up will be necessary to assess the long-term function of the implant.
全髋关节置换患者中，应力屏蔽继发的骨质溶解被认为是由于假体股骨柄的刚度大于股骨的刚度。这种担忧促使人们研发出一种结构刚度与天然股骨相似的复合股骨柄植入物。该股骨柄由钴铬合金芯组成，周围环绕着聚芳醚酮和钛网，用于骨长入。本研究的目的是确定使用这种股骨柄的中期临床、影像学和组织学结果。
28例患者（19例男性和9例女性），平均年龄51.3岁，接受了使用Epoch股骨柄的初次全髋关节置换术，并平均随访6.2年。术前、术后及此后每两年进行Harris髋关节评分并进行影像学检查。此外，术后两年内进行双能X线吸收法扫描以评估骨质吸收情况。对术后13个月和48个月尸检获得的两根股骨进行骨长入和骨附着分析。
Harris髋关节评分术前平均为56分，最后一次随访时提高到97分。双能X线吸收法扫描显示，两年时Gruen 7区平均骨密度下降最大（27.5%）。影像学检查未发现移位情况，只有一例髋关节出现骨质溶解。所有股骨柄均有稳定的骨固定。对术后13个月和48个月尸检获得的两根股骨进行组织学评估，结果显示，沿股骨柄全长的平均骨长入（及标准差）分别为49.62%±13.04%和73.57%±8.48%，平均骨附着分别为54.18%±7.68%和80.92%±6.06%。
对使用Epoch股骨柄治疗的髋关节进行中期随访表明，临床效果极佳，有骨整合的影像学证据，以及骨长入和骨附着的组织学表现。尽管该植入物在短期和中期均取得了优异的效果，但仍需要更长时间的随访来评估其长期功能。
