發展並整合三維動態X光及立體攝影術以探討功能性動作時軟組織移動誤差對膝關節力學變數之影響

Abstract

精確量測功能性動作時，活體之正常或人工置換膝關節之剛體運動與關節表面相對運動將有助於許多臨床醫療與研究。在動作分析領域中，應用立體攝影術拍攝皮膚點標記業已廣泛用於測量功能性動作時，膝關節三維運動。然而，該測量方法易受到人體軟組織移動誤差之影響，所測得之結果無法代表骨骼運動。現存的關節運動量測方法不論在精度上或實驗驗證上皆有其限制。因此，本研究之目的在於：發展基於實體模型之二維對三維定位方法(WEMS)，以單平面動態X光非侵入式測量功能性動作時，自然與人工膝關節之精確三維運動；應用該方法並整合立體攝影術以評估正常受試者功能性動作時，軟組織移動誤差之大小與模式；評估軟組織移動誤差對正常受試者上樓梯動作時，所量測得之膝關節動力學參數之影響；評估軟組織移動誤差對人工膝關節受試者坐到站動作時，所量測得之膝關節動力學參數之影響；以及利用全面最佳化方法(GOM)補償正常、前十字韌帶缺損與人工關節置換受試者走路、坐到站與上樓梯動作時，軟組織移動誤差對膝關節運動結果之影響。研究成果確立了WEMS法測量自然與人工膝關節試體三維運動之精確度。藉由整合動態X光與動作分析系統，測得軟組織移動誤差對利用皮膚點標記測量正常與人工關節受試者分別在上樓梯與坐到站動作時，膝關節運動結果與骨骼運動有顯著差異。更進一步運用全面最佳化方法補償軟組織移動誤差，確認補償後殘餘誤差之均方根的平均值在所有功能性動作與所有種類受試者中，膝關節移動誤差約在3-6 mm範圍，膝關節角度誤差約在3˚。本研究結果確認了全面最佳化可有效補償皮膚移動誤差對動作分析結果之影響，此結論將有助於人體動作領域之基礎研究與臨床應用。

Accurate measurement of the three-dimensional (3D) rigid body and surface kinematics of the natural and implanted knee is essential for many clinical applications. Skin marker-based stereophotogrammetry has been widely used in the in vivo, non-invasive measurement of 3D joint kinematics. However, the measured poses of body segments are subject to errors called soft tissue artifacts (STA). Existing techniques are limited either in their accuracy or lack of more realistic experimental evaluation of the measurement errors. The purposes of the study were to develop a volumetric model-based 2D-to-3D registration method, called the weighted edge-matching score (WEMS) method, for measuring accurate natural and implanted knee kinematics with single-plane fluoroscopy; to assess the 3D movement of skin markers relative to the underlying bones in normal subjects during functional activities; to access the effects of STA on the calculated joint variables at the knee in normal subjects during stair-ascent (SA); to quantify the STA and their effects on the calculated variables of the knee in patients with total knee replacements (TKR) during sit-to-stand (STS); and to validate the performance and effectiveness of global optimization method (GOM) with an appropriate kinematic model for compensating the STA for in vivo knee kinematics of normal, anterior cruciate ligament deficient (ACLD) and TKR subjects during functional activities. The precision of the WEMS method has been determined experimentally with cadaver knee and TKR. With the help of integrated 3D fluoroscopy method and stereophotogrammetry, considerable STA of normal and TKR subjects, during SA and STS respectively, were found and which led to significant differences of measured biomechanical variables of the knee. Compensating the effects of STA with GOM showed that the mean values of root mean squared error (RMSE) over all functional activities of all kinds of subjects were in the order of 3-6 mm for measurement of knee joint translations and about 3˚ for knee joint rotations. These findings suggested that GOM would be helpful for compensating STA in human motion analysis for basic research and clinical applications.