Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, 7-5-1, Kusunoki-cho, Chuo-ku, Kobe, 650-0017, Japan.
Department of Orthopaedic Surgery and Joint Surgery Centre, Takatsuki General Hospital, Osaka, Japan.
Arch Orthop Trauma Surg. 2024 Aug;144(8):3857-3864. doi: 10.1007/s00402-024-05500-5. Epub 2024 Aug 29.
This study aimed to evaluate differences in the pattern of fixation with a rectangular tapered short stem (Fitmore stem) due to proximal femoral medullary cavity morphology based on periprosthetic bone mineral density (BMD) and radiological findings.
We analyzed 105 consecutive patients (Dorr type A, 18; Dorr type B, 66; Dorr type C, 21) who underwent total hip arthroplasty using a Fitmore stem. Periprosthetic BMD was measured using dual-energy X-ray absorptiometry from 1 to 24 months postoperatively and radiological analysis was performed. Clinical outcomes were evaluated using the Harris hip score (HHS) and the University of California Los Angeles (UCLA) activity score preoperatively and 24 months postoperatively.
At 24 months postoperatively, Dorr type C had significantly decreased BMD changes in Gruen zones 2, 6, and 7 compared to Dorr types A and B, and conversely, significantly increased BMD changes in zone 4 (p < 0.05). Dorr type C had significantly greater subsidence than the other types (p < 0.01) and significantly higher cortical hypertrophy in zone 3 (p < 0.01). Stress shielding was not significantly different between Dorr types. The preoperative and postoperative HHS and UCLA activity scores showed no significant differences between the Dorr types.
In Dorr type C, BMD significantly decreased in the proximal femur with a rectangular tapered short stem, suggesting that the stem was fixed at the distal part. Careful observation of this prosthesis over time is needed in patients with Dorr type C.
本研究旨在根据假体周围骨密度（BMD）和影像学发现，评估因股骨近端髓腔形态不同而导致使用矩形锥形短柄（Fitmore 柄）固定时的固定模式差异。
我们分析了 105 例连续接受 Fitmore 柄全髋关节置换术的患者（Dorr 型 A，18 例；Dorr 型 B，66 例；Dorr 型 C，21 例）。术后 1 至 24 个月，使用双能 X 线吸收法测量假体周围 BMD，并进行影像学分析。术前和术后 24 个月，采用 Harris 髋关节评分（HHS）和加利福尼亚大学洛杉矶分校（UCLA）活动评分评估临床结果。
术后 24 个月，Dorr 型 C 在 Gruen 区 2、6 和 7 的 BMD 变化明显低于 Dorr 型 A 和 B，而在区 4 的 BMD 变化明显增加（p<0.05）。Dorr 型 C 的下沉量明显大于其他类型（p<0.01），在区 3 的皮质肥厚明显更高（p<0.01）。Dorr 型之间的应力遮挡无显著差异。术前和术后 HHS 和 UCLA 活动评分在 Dorr 型之间无显著差异。
在 Dorr 型 C 中，股骨近端使用矩形锥形短柄后 BMD 明显减少，提示柄固定在远端。在 Dorr 型 C 患者中，需要随着时间的推移仔细观察这种假体。
