Nakamura Yoshihide, Ohishi Hirotaka, Kishiya Masaki, Toh Satoshi
Department of Orthopaedic Surgery, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, Aomori, 036-8562, Japan.
J Orthop Sci. 2011 Jul;16(4):364-8. doi: 10.1007/s00776-011-0090-y. Epub 2011 May 13.
We developed the HPF stem to suit the Japanese femoral bone marrow canal in developmental dysplasia of the hip. This anatomical-shape cementless stem improves canal occupation by the lateral and anterior flares. We report the clinical performance of the stem and details of the change in the X-rays, especially of the femoral side.
We investigated 53 joints of total hip arthroplasty using the stem in 48 cases. The follow-up period was 8 years on average. We checked the Harris hip score (HHS) for clinical assessment. Existence of postoperative thigh pain was also investigated. For radiological assessment, the direction of stem insertion and initial fixation mode immediately after surgery were estimated. At the latest follow-up, we estimated the radiological findings of bone atrophy, spot welds, radiolucent zone, osteolysis, and sinking of the stem over 2 mm. Biological fixation was classified into four types: bone ingrowth, ingrowth suspected, suboptimum, and unstable fixation.
HHS was improved from 44 points before surgery to 92 points at the final follow-up. Light thigh pain appeared temporarily in three joints after surgery. Press-fit was achieved in femurs including total fit in 12 femurs, proximal fit in 4, middle fit in 25, and distal fit in 2. First degree stress shielding was seen in 25 femurs and second degree in 28. Forty-eight joints showed bone-ingrowth fixation, and five joints were ingrowth-suspected.
The clinical performance was excellent. Total or proximal fit was seen in only 30%. In these joints, cortical hypertrophy at the middle part of the stem and slight proximal bone atrophy appeared frequently, suggesting the stress transmission to the stem middle or distal portion, and there is a limit to the stress shielding evasion by the anatomical-shape stem.
我们研发了HPF柄以适配发育性髋关节发育不良患者的日本股骨骨髓腔。这种解剖形状的非骨水泥柄通过外侧和前方的扩口改善了髓腔填充情况。我们报告该柄的临床性能以及X线变化细节，尤其是股骨侧的情况。
我们调查了48例使用该柄进行全髋关节置换的53个关节。平均随访期为8年。我们检查Harris髋关节评分（HHS）以进行临床评估。还调查了术后大腿疼痛的情况。对于影像学评估，估计了柄的插入方向以及术后即刻的初始固定方式。在最近一次随访时，我们评估了骨萎缩、点焊、透亮区、骨溶解以及柄下沉超过2毫米的影像学表现。生物固定分为四种类型：骨长入、疑似长入、欠佳和不稳定固定。
HHS从术前的44分提高到末次随访时的92分。术后有3个关节暂时出现轻度大腿疼痛。股骨实现了压配，其中12个股骨完全匹配，4个股骨近端匹配，25个股骨中部匹配，2个股骨远端匹配。25个股骨出现一级应力遮挡，28个股骨出现二级应力遮挡。48个关节显示骨长入固定，5个关节疑似长入。
临床性能优异。仅30%的关节实现了完全或近端匹配。在这些关节中，柄中部的皮质肥厚和轻微的近端骨萎缩频繁出现，提示应力传递至柄的中部或远端，并且解剖形状的柄在规避应力遮挡方面存在局限性。
