股骨近端假体周围骨折锁定加压接骨板的设计

The design of a locking compression plate for periprosthetic proximal femur fractures

目的探索适用于国人全髋关节置换术(THA)术后股骨近端假体周围骨折(PPFF)内固定的锁定加压接骨板(LCP)的设计。方法(1)回顾性分析2012年9月—2013年12月南京中医药大学附属常州市中医医院骨科收治首次行THA治疗的90例患者的影像学资料。在90例患者术后髋关节侧位X线片上测量股骨假体近端1/2假体柄后边缘与股骨后方外皮质、远端1/2股骨假体柄前边缘与股骨前方外皮质的最小和最大垂直距离。(2)选取20具股骨标本,测量股骨标本长度和周径。将20具股骨标本植入股骨假体,建立股骨假体模型;对其中5具标本模型进行宝石能谱CT扫描和三维重建,测量股骨假体近端1/2假体柄后边缘与后方股骨外皮质、远端1/2假体柄前边缘与前方股骨外皮质间垂直距离,测量股骨假体近端1/2和远端1/2垂直距离>6mm的股骨长度,测量股骨中段侧方的弧度。(3)依据90例患者和5具股骨假体模型的测量数据设计并数字化定制LCP。采用定制LCP固定5具股骨假体模型,通过大体和影像学观察LCP近段锁定螺钉与假体的关系,调整可能与假体接触的锁定螺钉的角度;再采用调整后的LCP固定10具股骨假体模型,观察LCP近段锁定螺钉与假体的关系,确定LCP的设计方案。结果(1)90例患者术后髋关节侧位X线片测量结果:股骨假体近端1/2假体柄后边缘与股骨后方外皮质的垂直距离,最小(11.26±3.58)mm,最大(17.97±6.94)mm;远端1/2假体柄前边缘与股骨前方外皮质之间的垂直距离,最小(9.18±2.32)mm,最大(14.22±3.10)mm。(2)20具股骨标本的股骨长度为(41.67±0.24)cm,周径为(9.19±0.74)cm。股骨假体模型CT测量结果:假体近端1/2假体柄后边缘与股骨后方外皮质的垂直距离为(12.36±3.24)mm;假体远端1/2假体柄前边缘和股骨前方外皮质的垂直距离为(8.14±1.21)mm。假体近、远端1/2与股骨外皮质垂直距离>6mm的股骨长度分别为(69.20±4.53)mm和(57.31±3.82)mm。(3)LCP设计方案:LCP与假体近端1/2对应的部分设计3枚向后内成一定角度的锁定螺钉,对应3个锁定孔,分布于LCP中轴线偏后,向后内方向;与假体远端1/2对应的部分设计3枚向前内成一定角度的锁定螺钉,对应的3个锁定孔,分布于LCP中轴线偏前,向前内方向。采用设计、定制LCP固定股骨假体模型,LCP与股骨侧方弧度一致,锁定螺钉在股骨假体的后方或前方均实现双层皮质固定,角度合适。结论根据国人资料设计、定制LCP,在股骨假体模型上获得有效的固定空间,为THA后PPFF的处理提供可行方案,但临床应用效果有待进一步验证。

Objective To design a locking compression plate (LCP) for fixation of periprosthetic proximal femur fractures(PPFF) in Chinese. Methods (1)The imaging data of 90 patients that had primary total hip arthroplasty (THA) in Department of Orthopaedics, the Traditional Chinese Medicine of Changzhou, the Affiliated Hospital of Nanjing University of Chinese Medicine from September 2012 to December 2013 were retrospectively analyzed. The vertical distance between the edge of femur prosthesis and anterior or posterior femoral outer cortex was measured on the postoperative lateral X-rays films of hip of all cases. (2)Twenty cadaver femoral specimens were selected and their length and circumference were measured. Next to it, these specimens were implanted with femoral prosthesis stem, established the cadaveric femoral prosthesis model. Then 5 femoral prosthesis models underwent gemstone CT spectral scan and three-dimensional reconstruction. The vertical distance between the edge of femoral prosthesis stem and anterior or posterior femoral outer cortex and the length of femur for the vertical distance greater than 6 mm between the femoral prosthesis stem and femoral outer cortex were measured. The sagittal curve of femur was also assessed. (3)The LCP was digital customized according to the measured data of 90 patients and 5 femoral prosthesis models. After that, they were used to fix 5 cadaveric femur prosthesis models, and the relation of the locking screws on the LCP and the femoral prosthesis stem were observed by general view and image. The angle of locking screw which maybe contacted the femoral prosthesis was adjusted again. Then the improved LCP were used for fixing 10 cadaveric femur prosthesis models, the relation between the locking screws and the femoral prosthesis stem was evaluated. Finally, the design of the LCP was determined. Results (1)The measured data from the postoperative lateral X-rays films of hip of 90 cases were shown as follows: the average minimum and maximum vertical distance were (11.26±3.58)mm and (17.97±6.94)mm between the proximal half of the prosthesis and the outer posterior cortex of the femur, and they were (9.18±2.32)mm and (14.22±3.10)mm between the distal half of the prosthesis stem and the outer anterior femoral cortex respectively. (2)The average length and circumference of 20 cadaver femoral specimens were (41.67±0.24)cm and(9.19±0.74)cm respectively. The measured data from gemstone CT of femoral prosthesis models were showed as below: the average vertical distance between the proximal half of the prosthesis and the outer posterior cortex of the femur was (12.36±3.24) mm, and it was (8.14±1.21 )mm between the distal half of the prosthesis stem and the outer anterior femoral cortex. The length of femur was (69.20 ± 4.53)mm corresponding with the vertical distance over 6mm between proximal half prosthesis and femoral cortex, and that was (57.31±3.82)mm between distal half prosthesis and femur cortex. (3)The length of the LCP corresponding to proximal half femur prosthesis was designed with 3 locking holes which can be angulated in a specific angle in posterior of the prosthesis stem, and the length corresponding to distal half femur prosthesis was designed with 3 locking holes that can be angulated in a specific angle in anterior of the prosthesis stem. The curve of LCP was consistent with the curve of the femur. All locking screws achieved double cortical fixation by appropriate angle posterior or anterior the femoral prosthesis. Conclusions Although the LCP designed according to the anatomical data of Chinese femur can obtain adequate fixed space for femoral prosthesis models, and provide a new solution for treatment of PPFF, it still needs further clinical verification.