Department of Orthopedics, Teaching Block, All India Institute of Medical Sciences (AIIMS), New Delhi, India.
Department of Community Ophthalmology, All India Institute of Medical Sciences (AIIMS), New Delhi, India.
Clin Orthop Surg. 2021 Dec;13(4):491-498. doi: 10.4055/cios20166. Epub 2021 Apr 29.
Anteromedial osteoarthritis is a recognized indication for unicompartmental knee arthroplasty (UKA). Favorable postoperative outcomes largely depend on proper patient selection, correct implant positioning, and limb alignment. Computer navigation has a proven value over conventional systems in reducing mechanical errors in total knee arthroplasty (TKA). However, the lack of strong evidence impedes the universal use of computer navigation technology in UKA. Therefore, this study was proposed to investigate the accuracy of component positioning and limb alignment in computer navigated UKA and to observe the role of navigation in proper patient selection.
A total of 50 knees (38 patients) underwent computer navigated UKA between 2016 and 2018. All operations were performed by the senior surgeon using the same navigation system and implant type. The navigation system was used as a tool to aid patient selection: knees with preoperative residual varus > 5° on valgus stress and hyperextension > 10° were switched to navigated TKA. We measured the accuracy of component placement in sagittal and coronal planes on postoperative radiographs. Functional outcomes were also evaluated at the final follow-up (a minimum of 16 months).
Nine patients had tibia vara and 14 patients had preoperative hyperextension deformity. We observed coronal outliers for the tibial component in 12% knees and for the femoral component in 10% knees. We also observed sagittal outliers for the tibial component in 14% knees and for the femoral component in 6% knees. There was a significant improvement in the functional score at the final follow-up. On multiple linear regression, no difference was found in functional scores of knees with or without tibia vara ( = 0.16) and with or without hyperextension ( = 0.25).
Our study further validates the role of computer navigation in desirable implant positioning and limb alignment. We encourage use of computer-assisted navigation as a tool for patient selection, as it allows intraoperative dynamic goniometry and provides real-time kinematic behavior of the knee to obviate pitfalls such as significant residual varus angulation and hyperextension that predispose early failure of UKA.
前内侧骨关节炎是单髁膝关节置换术（UKA）的公认适应证。术后良好的结果在很大程度上取决于患者的选择、正确的植入物定位和肢体对线。计算机导航在减少全膝关节置换术（TKA）中的机械误差方面具有经证实的价值。然而，缺乏强有力的证据阻碍了计算机导航技术在 UKA 中的普遍应用。因此，本研究旨在探讨计算机导航 UKA 中组件定位和肢体对线的准确性，并观察导航在正确的患者选择中的作用。
2016 年至 2018 年期间，共有 50 个膝关节（38 例）接受了计算机导航 UKA。所有手术均由同一位资深外科医生使用相同的导航系统和植入物类型完成。导航系统用作辅助患者选择的工具：术前在外翻应力下残留内翻>5°和过伸>10°的膝关节改为导航 TKA。我们在术后 X 光片上测量矢状面和冠状面组件放置的准确性。在最后一次随访时（至少 16 个月）还评估了功能结果。
9 例患者有胫骨内翻，14 例患者有术前过伸畸形。我们观察到 12%的膝关节胫骨组件有冠状面外差，10%的膝关节股骨组件有冠状面外差。我们还观察到 14%的膝关节胫骨组件和 6%的膝关节股骨组件有矢状面外差。在最后一次随访时，功能评分有显著改善。在多元线性回归中，胫骨内翻和无胫骨内翻的膝关节（=0.16）和有过伸和无过伸的膝关节（=0.25）在功能评分方面没有差异。
我们的研究进一步验证了计算机导航在理想的植入物定位和肢体对线中的作用。我们鼓励使用计算机辅助导航作为患者选择的工具，因为它允许术中动态测角，并提供膝关节的实时运动学行为，以避免出现导致 UKA 早期失败的显著残留内翻角度和过伸等陷阱。
