Goldstein Wayne M, Gordon Alexander, Branson Jill J
University of Illinois at Chicago and the Illinois Bone and Joint Institute, Morton Grove, Ill, USA.
Orthopedics. 2005 Sep;28(9 Suppl):s1037-40. doi: 10.3928/0147-7447-20050902-06.
Postoperative leg length inequality after total hip arthroplasty frequently leads to medical liability issues because no standard exists regarding the acceptable disparity. Modular stems allow control of offset, independent sizing of the distal femoral anatomy, as well as proximal medullary sizing. The authors compared the restoration of leg length in two cohort protocols. In the 2001 cohort, tapered stems were exclusively used, giving priority to fit and fill of the medullary canal. In the 2004 cohort, porous-tapered stems, or an S-ROM modular stem (DePuy Orthopaedics Inc., Warsaw, Ind) when needed, were used based on preoperative templating to restore the center of femoral head rotation. Prior to and after surgery, length from center measurements were taken (center of rotation of the femoral head to the top of the lesser trochanter) and the vertical vector to compare the difference in actual leg length. In the 2001 cohort, the mean increase of length from center was 9 mm (7 mm leg length). In the 2004 cohort, 25% of the hips were inappropriate for tapered stems. S-ROMs were used because a tapered stem would lengthen the leg. In the standard offset tapered stem, the mean increase of length from center was 6 mm (4 mm leg length). In the high offset tapered stem, the mean increase of length from center was 7 mm (5 mm leg length). In the S-ROM stem with varying offsets, the mean increase of length from center was 6 mm (4 mm leg length). Only the S-ROM consistently avoids overlengthening in the majority of patients.
全髋关节置换术后下肢长度不等常常引发医疗责任问题，因为对于可接受的差异尚无标准。模块化股骨柄能够控制偏心距、独立确定股骨远端解剖结构的尺寸以及近端髓腔的尺寸。作者在两个队列方案中比较了下肢长度的恢复情况。在2001年的队列中，仅使用了锥形股骨柄，优先考虑髓腔的适配和填充。在2004年的队列中，根据术前模板使用多孔锥形股骨柄，必要时使用S-ROM模块化股骨柄（迪普伊骨科公司，印第安纳州华沙）以恢复股骨头旋转中心。手术前后，测量了中心长度（股骨头旋转中心至小转子顶部）和垂直向量，以比较实际下肢长度的差异。在2001年的队列中，中心长度的平均增加为9毫米（下肢长度增加7毫米）。在2004年的队列中，25%的髋关节不适合使用锥形股骨柄。使用S-ROM是因为锥形股骨柄会使下肢变长。在标准偏心距锥形股骨柄中，中心长度的平均增加为6毫米（下肢长度增加4毫米）。在高偏心距锥形股骨柄中，中心长度的平均增加为7毫米（下肢长度增加5毫米）。在具有不同偏心距的S-ROM股骨柄中，中心长度的平均增加为6毫米（下肢长度增加4毫米）。只有S-ROM在大多数患者中始终能避免下肢过度延长。
