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Increased joint stress and malalignment are etiologic factors in osteoarthritis. Static tibiofemoral frontal plane malalignment is associated with patellofemoral osteoarthritis (PFOA). Patellofemoral joint stress is increased by activities such as sit-to-stand (STS); this stress may be even greater if dynamic frontal plane tibiofemoral malalignment occurs. If hip muscle or quadriceps weakness is present in persons with PFOA, aberrant tibiofemoral frontal plane movement may occur, with increased patellofemoral stress. No studies have investigated frontal plane tibiofemoral and hip kinematics during STS in persons with PFOA or the relationship of hip muscle and quadriceps strength to these motions. Eight PFOA and seven control subjects performed STS from a stool during three-dimensional motion capture. Hip muscle and quadriceps strength were measured as peak isometric force. The PFOA group demonstrated increased peak tibial abduction angles during STS, and decreased hip abductor, hip extensor, and quadriceps peak force versus controls. A moderate inverse relationship between peak tibial abduction angle and peak hip abductor force was present. No difference between groups was found for peak hip adduction angle or peak hip external rotator force. Dynamic tibiofemoral malalignment and proximal lower extremity weakness may cause increased patellofemoral stress and may contribute to PFOA incidence or progression.
Lisa T. Hoglund (Corresponding Author) is with the Department of Physical Therapy, Samson College of Health Sciences, University of the Sciences, Philadelphia, PA. Howard J. Hillstrom is with the Leon Root, MD, Motion Analysis Laboratory, Hospital for Special Surgery, New York, NY. Ann E. Barr-Gillespie is with the College of Health Professions, Pacific University, Hillsboro, OR. Margery A. Lockard is with the Health Sciences and Health Administration Department, Drexel University, Philadelphia, PA. Mary F. Barbe is with the Department of Anatomy and Cell Biology, School of Medicine, Temple University, Philadelphia, PA. Jinsup Song is with the Gait Study Center, School of Podiatric Medicine, Temple University, Philadelphia, PA.