Purpose

The purpose of this study is to analyse the change in knee alignment after customised individually made (CIM) bicompartmental knee arthroplasty (BKA) and the subsequent consequences for patellar tracking.

Methods

Medical records of 23 patients who received 26 CIM BKA (ConforMIS iDuo G2) at our clinic between November 2015 and July 2018 were reviewed. The objective part of the Knee Society Score (KSS), the hip–knee–ankle angle (HKA), the tibial mechanical angle (TMA) and femoral mechanical angle (FMA) were recorded preoperative and four months postoperative. Leg alignment was classified as neutral (HKA = 180° ± 3°), varus (HKA < 177°) or valgus (HKA > 183°). Furthermore, patellar tracking was determined on skyline view radiographs and adverse events were recorded. Implant survival rate was determined with the Kaplan–Meier method. Patient-reported outcome measures (PROMs) were pain, satisfaction, overall improvement and if the patient would undergo the surgery again.

Results

The mean KSS improved from 61 points preoperative [standard deviation (SD) 14] to 90 points postoperative (SD 7, p < 0.001). The mean change for HKA was 6.3° (SD 3.5), for TMA 1.5° (SD 1.2) and for FMA 3.8° (SD 2.3). Postoperative leg alignment was neutral in 13 CIM BKA (50%), varus in two (8%) and valgus in 11 (42%) and patella tracking was central in 19 CIM BKA (73%) and lateral in seven (27%), respectively. Adverse events occurred in five CIM BKA: three patients required a patella resurfacing and one patient with bilateral CIM BKA needed a revision to a total knee arthroplasty. Implant survival rate was 92.3% at a follow-up of 3.2 years (SD 0.8).

PROMs for CIM BKA without revision surgery were available at a mean follow-up of 3.2 years (SD 0.8). Mean pain with level walking decreased to 0.8 points (SD 1.4, p < 0.001) and mean pain with stairs or inclines to 1.6 points (SD 1.3, p < 0.001). Patient satisfaction was very satisfied or satisfied (78%), neutral (17%) or unsatisfied (4%). Overall improvement was much better or considerably better for 91% of all patients; 87% would undergo the surgery again.

Conclusion

A relevant change of the leg axis away from the treated femorotibial compartment due to overstuffing was observed. Although, neutral leg alignment was not restored in every case, clinical and patient-reported outcomes improved significantly. Further studies with long-term clinical and patient-reported outcomes are required to evaluate whether patients with bicompartmental knee osteoarthritis benefit from CIM BKA.

Level of evidence

IV, case series.

中文翻译：

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定制的双室膝关节置换术后由于过度填充导致的腿部对齐的相关变化。

目的

本研究的目的是分析定制个性化 (CIM) 双室膝关节置换术 (BKA) 后膝关节对线的变化以及随后对髌骨跟踪的影响。

方法

回顾了 2015 年 11 月至 2018 年 7 月在我们诊所接受 26 CIM BKA (ConforMIS iDuo G2) 的 23 名患者的医疗记录。术前和术后4个月记录膝关节协会评分（KSS）、髋-膝-踝角（HKA）、胫骨机械角（TMA）和股骨机械角（FMA）的客观部分。腿对齐分为中立（HKA = 180°±3°）、内翻（HKA < 177°）或外翻（HKA > 183°）。此外，在天际线视图 X 光片上确定了髌骨跟踪，并记录了不良事件。种植体存活率采用 Kaplan-Meier 法测定。患者报告的结果测量 (PROM) 是疼痛、满意度、整体改善以及患者是否会再次接受手术。

结果

平均 KSS 从术前 61 分 [标准差 (SD) 14] 提高到术后 90 分 (SD 7, p  < 0.001)。HKA 的平均变化为 6.3° (SD 3.5)、TMA 为 1.5° (SD 1.2) 和 FMA 为 3.8° (SD 2.3)。13 例 CIM BKA (50%) 术后腿对线中立，2 例内翻 (8%) 和 11 例 (42%) 外翻，19 例 CIM BKA (73%) 髌骨轨迹位于中央，7 例 (27%) 位于外侧， 分别。5 例 CIM BKA 发生不良事件：3 例患者需要进行髌骨表面置换，1 例双侧 CIM BKA 患者需要翻修进行全膝关节置换术。在 3.2 年的随访中，种植体存活率为 92.3% (SD 0.8)。

平均随访 3.2 年 (SD 0.8)，可获得未经翻修手术的 CIM BKA 的 PROM。水平行走的平均疼痛降至 0.8 分（SD 1.4，p  < 0.001），楼梯或倾斜的平均疼痛降至 1.6 分（SD 1.3，p  < 0.001）。患者满意度非常满意或满意（78%）、中性（17%）或不满意（4%）。91% 的所有患者的总体改善要好得多或相当好；87% 将再次接受手术。

结论

观察到由于过度填充导致的腿轴远离治疗股胫骨室的相关变化。尽管并非在所有病例中都恢复了中立腿对齐，但临床和患者报告的结果显着改善。需要进一步研究长期临床和患者报告的结果，以评估双室膝骨关节炎患者是否受益于 CIM BKA。

证据水平

四、案例系列。