Nishino Tomofumi, Mishima Hajime, Miyakawa Syumpei, Kawamura Haruo, Ochiai Naoyuki
Department of Orthopaedic Surgery, Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.
J Orthop Sci. 2008 Nov;13(6):498-503. doi: 10.1007/s00776-008-1272-0. Epub 2008 Dec 17.
Tapered femoral stems have been shown to produce less thigh pain and stress shielding than other cement-less stem designs. The purpose of this study was to examine the performance of this type of femoral stem in Japanese patients.
A series of 40 total hip arthroplasties with a Synergy tapered femoral component were performed in 33 patients between March 1999 and February 2001 at our institution. Three hips (in three patients) were lost to follow-up, so 37 hips in 30 patients were followed for an average of 70 months. The patients' average age at the time of surgery was 59 years (range 43-80 years). Clinical evaluation included the Japanese Orthopaedic Association (JOA) Hip Score and the incidence of thigh pain. Preoperative radiographic examination included the cortical index and Dorr's bone type. Postoperative radiographic examination included evaluation of biological fixation, spot welds, cortical hypertrophy, and stress shielding.
The average JOA Hip Score improved significantly from 35 preoperatively to 91 postoperatively. No patient suffered thigh pain. All femoral components were classified as bony stable. Spot welds and cortical hypertrophy were commonly found in the middle to the distal portion of the component. Severe (third and fourth degree) stress shielding was observed in 24.3% of the cases. A low cortical index, a Dorr type C femur, and a large stem size were associated with severe stress shielding.
The midterm clinical results with the Synergy femoral component were satisfactory for Japanese patients. Although severe stress shielding was frequently observed in patients with poor bone quality, stem stability was not affected. Extent of grit blasting and stem length may be factors causing severe stress shielding in Japanese patients with poor bone quality. In conclusion, poor bone quality is a less favorable indication for the cementless tapered stem.
与其他非骨水泥型股骨柄设计相比，锥形股骨柄已被证明可减少大腿疼痛和应力遮挡。本研究的目的是检查这种类型的股骨柄在日本患者中的性能。
1999年3月至2001年2月期间，在我们机构对33例患者进行了一系列40例使用Synergy锥形股骨组件的全髋关节置换术。3例患者的3髋失访，因此对30例患者的37髋进行了平均70个月的随访。患者手术时的平均年龄为59岁（范围43 - 80岁）。临床评估包括日本骨科协会（JOA）髋关节评分和大腿疼痛的发生率。术前影像学检查包括皮质指数和多尔氏骨型。术后影像学检查包括生物固定、点焊、皮质肥大和应力遮挡的评估。
JOA髋关节评分平均从术前的35分显著提高到术后的91分。没有患者出现大腿疼痛。所有股骨组件均被分类为骨稳定。点焊和皮质肥大常见于组件的中至远端部分。24.3%的病例观察到严重（三级和四级）应力遮挡。低皮质指数、多尔氏C型股骨和大的柄尺寸与严重应力遮挡相关。
Synergy股骨组件的中期临床结果对日本患者来说是令人满意的。尽管在骨质量差的患者中经常观察到严重的应力遮挡，但柄的稳定性未受影响。喷砂程度和柄的长度可能是导致骨质量差的日本患者出现严重应力遮挡的因素。总之，对于非骨水泥锥形柄而言，骨质量差是一个不太有利的指征。
