Clinicians can be confident that a 2-point change on the NPRS represents clinically meaningful change that exceeds the bounds of measurement error.

Study Design: Case control design. Objectives: To investigate whether differences exist in lower extremity muscle strength and soft tissue length between patients with patellofemoral pain syndrome (PFPS) and age-and gendermatched control subjects. Background: Based on our clinical experience and emerging data, impairments such as muscular weakness surrounding the hip and limited flexibility of key lower extremity muscles may be important impairments to consider in the conservative management of PFPS. Methods and Measures: Thirty patients with PFPS and 30 age-and gender-matched controls without PFPS (17 females and 13 males in each group) participated in the study. Data were collected during 1 testing session by an examiner not blinded to group assignment. Demographic, health history, physical activity levels, and pain and function were assessed using patientcompleted measures. Physical examination measures included assessment of hip external rotation strength, hip abduction strength, length of the iliotibial band/tensor fascia lata complex, gastrocnemius length, soleus length, and quadriceps and hamstrings muscles length. Results:Patients with PFPS demonstrated significantly less flexibility of the gastrocnemius, soleus, quadriceps, and hamstrings compared to healthy control subjects. No differences existed in flexibility of the iliotibial band/tensor fascia lata complex and strength of the hip external rotators and abductors. Multivariate stepwise discriminant analysis identified gastrocnemius length, hip abduction strength, and soleus length as being able to distinguish between patients with PFPS and healthy individuals without PFPS. Conclusion: This study suggests that further research is warranted regarding the association of these impairments of muscle strength and soft tissue length in patients with PFPS. J Orthop Sports Phys Ther 2005;35:793-801.

Objective. To report the prevalence and relationship of self-reported knee instability to physical function in a sample of subjects with knee osteoarthritis (OA), and to discuss the implications of these observations for rehabilitation. Methods. Subjects were 105 individuals (80 females) with knee OA who rated their knee instability severity on a 6-point numeric scale in response to the query "To what degree does giving way, buckling, or shifting of the knee affect your level of daily activity?" A principal component analysis was used to combine The Western Ontario and McMaster Universities pain, stiffness, and physical function subscale scores, and the Timed Get Up and Go Test score into a principal component score for physical function (PCPF). Other variables that could affect the PCPF such as age, sex, years with knee OA, radiographic severity of knee OA, knee pain, knee motion, and quadriceps strength were also recorded. The prevalence of self-reported knee instability was determined by calculating the proportion of subjects who reported each severity level of knee instability. Hierarchical regression analysis was performed to determine if the level of self-reported knee instability could predict the PCPF, even after accounting for the effects of the other variables. Results. Sixty-three percent of the subjects reported knee instability during activities of daily living, and 44% reported that instability affects their ability to function. The severity of self-reported knee instability was associated with the PCPF (eta 2 ‫؍‬ 0.40, P < 0.001), and after controlling for all other independent variables, significantly increased the prediction of the PCPF (r 2 ‫؍‬ 0.56, r 2 change ‫؍‬ 0.05; P < 0.001). Conclusion.The results indicate that a substantial proportion of individuals with knee OA report episodes of knee instability during activities of daily living, and instability affects physical function beyond that which can be explained by contributions from other impairments such as knee pain, range of motion, and quadriceps strength. Knee instability is a problem that should be specifically addressed in rehabilitation programs and may require interventions beyond those that address pain, joint motion, and muscular strength, to maximize the effectiveness of rehabilitation for individuals with knee OA.

Study Design Randomized clinical trial. Objectives To compare the effects of functional stabilization training (FST) versus standard training on knee pain and function, lower-limb and trunk kinematics, trunk muscle endurance, and eccentric hip and knee muscle strength in women with patellofemoral pain. Background A combination of hip- and knee-strengthening exercise may be more beneficial than quadriceps strengthening alone to improve pain and function in individuals with patellofemoral pain. However, there is limited evidence of the effectiveness of these exercise programs on the biomechanics of the lower extremity. Methods Thirty-one women were randomized to either the FST group or standard-training group. Patients attended a baseline assessment session, followed by an 8-week intervention, and were reassessed at the end of the intervention and at 3 months after the intervention. Assessment measures were a 10-cm visual analog scale for pain, the Lower Extremity Functional Scale, and the single-leg triple-hop test. A global rating of change scale was used to measure perceived improvement. Kinematics were assessed during the single-leg squat. Outcome measures also included trunk endurance and eccentric hip and knee muscle strength assessment. Results The patients in the FST group had less pain at the 3-month follow-up and greater global improvement and physical function at the end of the intervention compared to those in the standard-training group. Lesser ipsilateral trunk inclination, pelvis contralateral depression, hip adduction, and knee abduction, along with greater pelvis anteversion and hip flexion movement excursions during the single-leg squat, were only observed in the FST group after the intervention. Only those in the FST group had greater eccentric hip abductor and knee flexor strength, as well as greater endurance of the anterior, posterior, and lateral trunk muscles, after training. Conclusion An intervention program consisting of hip muscle strengthening and lower-limb and trunk movement control exercises was more beneficial in improving pain, physical function, kinematics, and muscle strength compared to a program of quadriceps-strengthening exercises alone. Level of Evidence Therapy, level 2b-. J Orthop Sports Phys Ther 2014;44(4):240–251. Epub 25 February 2014. doi:10.2519/jospt.2014.4940

Background: The reliability and measurement error of several impairment measures used during the clinical examination of patients with patellofemoral pain syndrome (PFPS) has not been established. The purpose was to determine the inter-tester reliability and measurement error of measures of impairments associated with PFPS in patients with PFPS.