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Utility of the Frontal Plane Projection Angle in Females With Patellofemoral Pain

2008; American Physical Therapy Association; Volume: 38; Issue: 10 Linguagem: Inglês

10.2519/jospt.2008.2706

1938-1344

John D. Willson, Irene S. Davis,

Sports Performance and Training

Study Design Case-control study of females with patellofemoral pain syndrome (PFPS) and a control group. Objectives Three different approaches were used to examine the utility of a 2-dimensional (2-D) frontal plane projection angle (FPPA) measure of knee alignment. First, we measured the FPPA association with respect to 3-dimensional (3-D) lower extremity joint rotations during single-leg squats. Second, we determined the correlation of the FPPA during single-leg squats with hip and knee joint rotations during running and single-leg jumping. Third, we compared the FPPA between females with and without PFPS. Background PFPS is associated with altered lower extremity kinematics during weight- bearing activities that decrease retropatellar contact area and increase retropatellar stress. An objective and simple procedure to quantify altered kinematics during weight-bearing activities may help clinicians identify individuals who may likely benefit from interventions to improve lower extremity kinematics. Methods and Measures Twenty females with PFPS and 20 healthy female controls performed single-leg squats, running, and repetitive single-leg jumps, while 3-D lower extremity kinematics were recorded. The FPPA was recorded by a digital camera during single-leg stance and single-leg squats. Correlation coefficients were used to quantify the association between the FPPA and transverse and frontal plane hip and knee angles for all activities. Independent t tests were used to compare FPPA values between groups. Results FPPA values representing medial displacement of the knee during single-leg squats were associated with increased hip adduction (r = 0.32 to 0.38, P<.044) and knee external rotation (r = 0.48 to 0.55, P<.001) across activities. FPPA values for the PFPS group reveal greater medial displacement of the knee compared with those of the control group during single-leg squats (P = .012). Conclusion The association between the FPPA and lower extremity kinematics that are associated with PFPS suggest that the FPPA during single-leg squats may be a useful clinical measure. However, these methods should not be used to quantify 3-D joint rotations. Level of Evidence Level 5. J Orthop Sports Phys Ther 2008;38(10):606–615. doi:10.2519/jospt.2008.2706