Bennett D B, Hill J C, Dennison J, O'Brien S, Mantel J L, Isaac G H, Beverland D E
Orthopaedic Outcome Assessment Unit, Musgrave Park Hospital, Stockman's Lane, Belfast BT9 7JB, Northern Ireland. E-mail address for J.C. Hill:
DePuy Synthes Joint Reconstruction, White Rose Office Park, Millshaw Park Lane, Leeds LS11 0BG, United Kingdom.
J Bone Joint Surg Am. 2014 Dec 17;96(24):2062-9. doi: 10.2106/JBJS.M.01542.
Attempts to improve proximal load transfer and minimize stress shielding have included reducing the stiffness of femoral stems and using alternative stem materials, including carbon fiber composites. An uncemented implant (SR71) composed of a carbon-fiber-composite distal section and a porous-coated titanium-alloy proximal section, designed to improve proximal load transfer and provide good fixation, was clinically evaluated in a prospective randomized study.
Sixty patients were enrolled and randomized to receive either the SR71 stem or an all-metal stem (Stability). All patients received a cemented all-polyethylene acetabular component and a 28-mm metal femoral head. All uncemented stems were implanted by the same surgeon. Patients were followed for up to ten years with repeated assessments of bone mineral density, radiographs, Harris hip scores (HHS), and visual analog scale (VAS) pain scores.
Ten years postoperatively, nineteen patients who had been treated with the SR71 stem and not lost to follow-up showed a significantly greater increase in proximal bone mineral density (Gruen zones 1 [p = 0.003] and 7 [p = 0.0007]) from baseline than did the twenty-two who had been treated with the Stability stem and not lost to follow-up. In contrast, the Stability group showed a significantly greater increase in distal bone mineral density (Gruen zones 2 [p = 0.0004], 3 [p = 0.0001], and 5 [p = 0.0035]) compared with the SR71 group. Radiographs demonstrated one case of progressive migration of an acetabular component used with an SR71 stem and one case of bone resorption in Gruen zones 7 and 14 in a patient treated with a Stability stem. There was no significant difference between the SR71 and Stability stems in terms of changes in the total HHS, HHS for pain, HHS for range of motion, or VAS pain scores ten years postoperatively relative to preoperative levels. There was one reported revision of an SR71 femoral stem at the ten-year review.
The investigational SR71 implant provided increased proximal bone density and reduced distal bone density. The implant showed promising results at the time of early follow-up, and the clinical outcomes were similar to those of an all-metal stem at the time of a ten-year follow-up.
为改善近端负荷传递并尽量减少应力遮挡，人们采取了多种措施，包括降低股骨干的刚度以及使用包括碳纤维复合材料在内的其他替代骨干材料。一种非骨水泥型植入物（SR71），由碳纤维复合材料远端部分和多孔涂层钛合金近端部分组成，旨在改善近端负荷传递并提供良好的固定效果，在一项前瞻性随机研究中进行了临床评估。
招募了60名患者并随机分为两组，分别接受SR71骨干或全金属骨干（Stability）。所有患者均接受骨水泥固定的全聚乙烯髋臼组件和28毫米金属股骨头。所有非骨水泥型骨干均由同一位外科医生植入。对患者进行了长达十年的随访，期间反复评估骨密度、X线片、Harris髋关节评分（HHS）和视觉模拟量表（VAS）疼痛评分。
术后十年，19名接受SR71骨干治疗且未失访的患者，与22名接受Stability骨干治疗且未失访的患者相比，其近端骨密度（Gruen分区1[p = 0.003]和7[p = 0.0007]）较基线水平有显著更大的增加。相比之下，与SR71组相比，Stability组远端骨密度（Gruen分区2[p = 0.0004]、3[p = 0.0001]和5[p = 0.0035]）有显著更大的增加。X线片显示，使用SR71骨干的患者中有1例髋臼组件出现进行性移位，使用Stability骨干治疗的1例患者在Gruen分区7和14出现骨吸收。术后十年，SR71骨干和Stability骨干在总HHS、疼痛HHS、活动范围HHS或VAS疼痛评分相对于术前水平的变化方面无显著差异。在十年评估时有1例报告的SR71股骨干翻修。
研究性的SR71植入物可增加近端骨密度并降低远端骨密度。该植入物在早期随访时显示出有前景的结果，在十年随访时临床结果与全金属骨干相似。
