Association Between Impairments and Function in Individuals with Patellofemoral Pain Syndrome

Purpose: To identify baseline impairments associated with physical function and to identify what changes in impairments are associated with functional outcome in patients with PFPS following a standardized physical therapy (PT) treatment at 2 and 6-month follow-ups. Subjects: 74 patients diagnosed with PFPS and referred to PT treatment. Methods: Correlational, predictive design. Baseline measurement session was performed to complete demographic questionnaires, self-reported measures, and undergo a physical exam. Impairments measured during physical exam included quadriceps strength, hip abduction strength, hip external rotation strength, hamstrings length, quadriceps length, plantar flexors length, ITB/TFL complex length, lateral retinacular length, foot pronation, Q-angle, tibial torsion, quality of movement, pain, and anxiety. Following the baseline, subjects participated in a standardized PT program. Then, measurement sessions were performed at 2 and 6-month follow-ups. Analyses: Association between baseline impairment and function used a stepwise multiple regression in which potential confounder variables (age, sex, activity level, height and weight) were forced into the model as a single block. Then, impairment measures were entered in a stepwise procedure. Function measured by the Activity of Daily Living Scale (ADLS) was the criterion variable. Association between changes in impairment and function outcome was investigated with two stepwise multiple regressions, one with the 2 and the other with the 6-month follow-up data. The criterion variable was the ADLS of the respective follow-up controlled by the baseline ADLS. First, potential confounders were forced into the model as a single block. Then, changes in impairments and baseline pain were entered in a stepwise procedure. Results and Clinical Relevance: At baseline our study indicates that after controlling the confounders, pain and tightness of lateral retinaculum predicted baseline function. Data suggested that pain may mediate the relationship between anxiety and function in patients with PFPS and the role of pain and anxiety in the prediction of function should be considered together with this population. At the 2 and 6-month follow-ups, after controlling the confounders, increased gastrocnemius length and increased quadriceps length predicted functional outcome, respectively. It seems that clinicians should specifically target impairments of soft tissue length in an attempt to improve functional outcome in patients with PFPS