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, Takatsuki General Hospital, Osaka, Japan.
Arch Orthop Trauma Surg. 2022 Dec;142(12):4087-4093. doi: 10.1007/s00402-021-04308-x. Epub 2022 Jan 23.
Changes in bone mineral density (BMD) around the fully hydroxyapatite (HA)-coated compaction broached and triple-tapered stem, namely, Polarstem, after total hip arthroplasty (THA) are currently unknown. Therefore, the aims of this study were to investigate clinical outcomes of Polarstem, mainly postoperative temporal changes in BMD around the stem for 2 years, and to compare them with those of HA-coated and non-HA-coated tapered-wedge stems.
This retrospective cohort study enrolled 100 consecutive patients who underwent THA using Polarstem (n = 38), HA-coated Anthology (n = 31), and non-HA-coated Anthology (n = 31). BMD was evaluated using dual-energy X-ray absorptiometry in seven regions according to the Gruen zones. Postoperatively, BMD around the stem was assessed within 2 months (baseline BMD) and at 6, 12, and 24 months. A change in BMD was defined as the value calculated by dividing each postoperative BMD value at 6, 12, and 24 months by the baseline BMD value. Changes in BMD and radiographic parameters such as stress shielding and spot welds were compared among the three stems.
The incidence rate of stress shielding in the Polarstem group was significantly lower than those in the other two groups (p = 0.007). The change in BMD in Zone 7 of Polarstem was significantly more than that of the other two groups at 12 and 24 months postoperatively (p = 0.030 and p = 0.009, respectively).
Polarstem, a fully HA-coated compaction broached and triple-tapered stem, maintained BMD around the femoral calcar until 2 years postoperatively and could reduce the risk of stress shielding compared with tapered-wedge stems.
全羟基磷灰石（HA）涂层压配扩孔和三锥形柄，即 Polarstem，在全髋关节置换（THA）后周围骨矿物质密度（BMD）的变化目前尚不清楚。因此，本研究的目的是研究 Polarstem 的临床结果，主要是术后 2 年内柄周围 BMD 的时间变化，并将其与 HA 涂层和非 HA 涂层锥形楔柄进行比较。
这项回顾性队列研究纳入了 100 例连续接受 Polarstem（n=38）、HA 涂层 Anthology（n=31）和非 HA 涂层 Anthology（n=31）THA 的患者。使用双能 X 射线吸收法（DXA）根据 Gruen 区评估 7 个区域的 BMD。术后 2 个月内（基线 BMD）和 6、12 和 24 个月时评估柄周围的 BMD。BMD 的变化定义为将术后每个 6、12 和 24 个月的 BMD 值除以基线 BMD 值计算得出的值。比较了三种柄的 BMD 变化和影像学参数（如应力遮挡和点焊）。
Polarstem 组的应力遮挡发生率明显低于其他两组（p=0.007）。术后 12 和 24 个月时，Polarstem 组的 Zone 7 区 BMD 变化明显大于其他两组（p=0.030 和 p=0.009）。
全 HA 涂层压配扩孔和三锥形柄 Polarstem 可维持股骨距周围的 BMD 直至术后 2 年，与锥形楔柄相比可降低应力遮挡的风险。
