Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA.
Department of Orthopedic Surgery, New York University Langone Health, New York, New York, USA.
Am J Sports Med. 2021 Oct;49(12):3395-3403. doi: 10.1177/03635465211033601. Epub 2021 Aug 23.
Hemiarthroplasty using a polyvinyl alcohol (PVA) hydrogel synthetic implant has been suggested as a good alternative to arthrodesis for the treatment of hallux rigidus. However, failure rates as high as 20% have been recorded.
To characterize the pathological processes in bone, cartilage, and the synovial membrane after PVA hemiarthroplasty in an ovine model with 6 months of follow-up.
Controlled laboratory study.
A unilateral osteochondral defect (8-mm diameter × 10-mm depth) was made in the medial femoral condyle in 6 sheep. Animals were randomized to receive a PVA implant (n = 4) or to have an empty defect (n = 2) and were monitored for 6 months. Patellofemoral radiographs were obtained at monthly intervals, and quantitative computed tomography was performed at the end of the study. After death, the joints were macroscopically evaluated and scored. Osteochondral and synovial membrane histological findings were assessed using modified Osteoarthritis Research Society International (OARSI) and aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL) scoring systems. Immunohistochemistry using Iba1 was performed to evaluate activated macrophage infiltration.
Overall, 2 sheep with PVA implants were euthanized at 1 and 5 months because of uncontrollable pain and lameness (failed implants). Quantitative computed tomography showed that sheep with failed implants had 2.1-fold more osteolysis than those with successful implants. The sheep with failed implants had osteoarthritis with extensive glycosaminoglycan loss and cartilage fibrillation of the condyle and opposing tibial surface on histological examination. A foreign body reaction with severe chronic lymphoplasmacytic and granulomatous inflammation with giant cells was detected surrounding the implant. The synovial membrane ALVAL score was 9 of 19 and 14 of 19 in failed implants with synovial hyperplasia and lymphoplasmacytic and macrophage infiltration. In contrast, the synovial membrane in successful implants and empty defects was normal (ALVAL score = 0/19). Immunolabeling for Iba1 in failed implants confirmed extensive and dense macrophage infiltration within the condyle and synovial membrane, with the highest immunoreactive score (9/9).
PVA hydrogel implants had a 50% failure rate with uncontrollable pain, severe osteolysis, inflammation, and foreign body reactions.
The failure rate and pathological characteristics of the PVA implants suggest that their use should not be continued in human patients without further in vivo safety studies.
对于拇僵硬，使用聚乙烯醇（PVA）水凝胶合成植入物的半关节成形术已被认为是关节融合术的良好替代方法。然而，记录的失败率高达 20%。
在羊模型中，通过 6 个月的随访，描述 PVA 半关节成形术后骨、软骨和滑膜的病理过程。
对照实验室研究。
在 6 只羊的内侧股骨髁中制作单侧骨软骨缺损（8 毫米直径×10 毫米深度）。动物随机接受 PVA 植入物（n=4）或有空缺（n=2），并监测 6 个月。每月获取髌股射线照相，研究结束时进行定量计算机断层扫描。死后，对关节进行宏观评估和评分。使用改良的骨关节炎研究协会国际（OARSI）和无菌淋巴细胞为主的血管炎相关病变（ALVAL）评分系统评估骨软骨和滑膜膜的组织学发现。使用 Iba1 进行免疫组织化学染色，以评估激活的巨噬细胞浸润。
总体而言，2 只接受 PVA 植入物的绵羊因无法控制的疼痛和跛行（植入物失败）在 1 个月和 5 个月时被安乐死。定量计算机断层扫描显示，植入物失败的绵羊的骨溶解程度是植入物成功的绵羊的 2.1 倍。植入物失败的绵羊的关节炎伴有广泛的糖胺聚糖丢失和髁和对侧胫骨表面的软骨纤维化。在植入物周围检测到严重的慢性淋巴浆细胞和肉芽肿性炎症伴巨细胞的异物反应。滑膜膜的 ALVAL 评分为 9/19 和 14/19（滑膜增生和淋巴浆细胞和巨噬细胞浸润）。相比之下，植入物成功和空缺陷的滑膜膜正常（ALVAL 评分为 0/19）。植入物失败的 Iba1 免疫标记证实了髁和滑膜膜内广泛而密集的巨噬细胞浸润，其免疫反应性评分最高（9/9）。
PVA 水凝胶植入物的失败率为 50%，伴有无法控制的疼痛、严重的骨溶解、炎症和异物反应。
PVA 植入物的失败率和病理特征表明，在没有进一步体内安全性研究的情况下，不应在人类患者中继续使用它们。
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