THE ASSOCIATION BETWEEN PATELLA ALIGNMENT AND FEMORAL TROCHLEAR GEOMETRY

鄧祥伶/ University of Southern California/ Division of Biokinesiology

 

http://brown.edu/Conference/American_Society_of_Biomechanics/  

 

異常的髕骨位置已被認為是可能造成髕股疼痛症候群的原因之一。過去的研究顯示， 股骨滑車形狀可能影響髕骨位置。本研究的目的在於利用核磁共振影像建立髕骨位置與股骨滑車形狀的相對關係。三十六個受測者參在膝蓋彎曲0度、 20度、40度及60度，並且承重25%體重的情況下，透過1.5T核磁共振影像系統截取橫切面髕股關節影像。Pearson相關係數顯示股骨外側滑車傾斜角度和髕骨外移與外傾程度在四個膝蓋彎曲角度均有顯著的相關性。股骨滑車角度則未與任何髕骨位置在任何角度有顯著的相關性。由於股四頭肌的收縮帶動髕骨的外移與外傾。因此，外側滑車傾斜角度可能對髕骨位置扮演較重要的決定性角色。本研究結果支持股骨外側滑車傾斜角度和髕骨位置有較佳的相關性。因此，股骨外側滑車傾斜角度可做為異常髕骨位置的預測因子。

 

Altered patella alignment has been proposed as an etiologic factor associated with patellofemoral pain. Previous studies have suggested the geometry of femoral trochlea plays an important role in determining patellar kinematics. The purpose of the current study was to determine whether the depth of the trochlear groove or the height of the lateral anterior femoral condyle better correlates with lateral patella displacement and tilt as assessed using MRI.

Thirty-six females participated in this study. A 1.5T MR system was used to obtain axial plane images of the patellofemoral joint, using a fat suppressed FSPGR pulse sequence. Each subject was imaged at four knee flexion angles (0o, 20o, 40o, 60o). A nonferromagnetic loading device permitted imaging to be performed during unilateral knee extension in the supine position (25% of body weight). Measures of patellar alignment and femoral trochlear geometry were examined on the image containing the widest patella. Lateral patella displacement was quantified using the bisect offset. Lateral patella tilt was assessed using the patella tilt angle. The depth of the trochlear groove was measured using the sulcus angle. The height of the lateral anterior femoral condyle was measured using the lateral trochlear inclination angle. Pearson correlation coefficients were used to examine the association between measures of patella alignment and femoral trochlear geometry at each knee flexion angle.

Significant correlations between lateral trochlea inclination and patellar alignment were found across all flexion angles. No significant correlations were observed between the SA and measures of patellar alignment for any knee flexion angle.

The fact that the patella gets pulled laterally with quadriceps contraction (owing to the quadriceps angle), suggests that the lateral femoral is more important than the medial anterior femoral condyle in providing patella stability. In contrast, the sulcus angle takes into consideration the shape of the entire femoral trochlea (including the medial anterior femoral condyle).

The findings of this study suggest that the geometry of the lateral anterior femoral condyle is better associated with patellar alignment than the geometry of entire trochlear groove. As such, the lateral trochlear inclination angle should be used to evaluate potential structural factors that may underlie patella malalignment in persons with patellofemoral pain.