Letters to the Editor-in-Chief of the JOSPT as follows:

• Clinical Prediction Rules in Physical Therapy: Coming of Age? J Orthop Sports Phys Ther 2009;39(3):231-232. doi:10.2519/jospt.2009.0201
• Frontal Plane Measurements During a Single-Leg Squat Test in Individuals With Patellofemoral Pain Syndrome and Authors' Response, J Orthop Sports Phys Ther 2009;39(3):233-234. doi:10.2519/jospt.2009.0202
• Management of Patients With Patellofemoral Pain Syndrome Using a Multimodal Approach: A Case Series and Authors' Response, J Orthop Sports Phys Ther 2009;39(3):234-237. doi:10.2519/jospt.2009.0203

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, published online 11 July 2008. doi:10.2519/jospt.2008.2706

KEY WORDS: anterior knee pain, kinematics, knee, patella, 2-dimensional analysis

Study Design: Cross-sectional. Objectives: To determine if females with anterior knee pain are more likely to demonstrate hip abduction or external rotation weakness than a similar, asymptomatic, age-matched control group. Background: Diminished hip strength has been implicated as being contributory to lower-extremity malalignment and patellofemoral pain. The identification of reliable and consistent patterns of weakness in this population may help health care professionals establish a more effective treatment plan. Methods and Measures: Hip abduction and external rotation isometric strength measurements were recorded for the injured side of 15 female subjects with patellofemoral joint pain (mean ± SD age, 15.7 ± 2.7 years; age range, 12-21 years). These were compared with strength measurements from the corresponding hip of 15 age-matched female control subjects (mean ± SD age, 15.7 ± 2.7 years; age range, 12-21 years). All strength measurements were made using hand-held dynamometers. Results: Subjects with patellofemoral pain demonstrated 26% less hip abduction strength (P<.001) and 36% less hip external rotation strength (P<.001) than similar age-matched controls. Conclusions: The results indicate that young women with patellofemoral pain are more likely to demonstrate weakness in hip abduction as well as external rotation than age-matched women who are not symptomatic.

J Orthop Sports Phys Ther. 2003;33(11):671-676.
 

Key Words: anterior knee pain, hip abduction, hip external rotation, knee, patella

Study Design: Randomized clinical trial. Objectives: To investigate the clinical efficacy of the addition of the Protonics system to a standard exercise-based patellofemoral rehabilitation protocol. Background: The Protonics system has been suggested as an intervention for patients with patellofemoral pain syndrome (PFPS). However, the effects of this system have not been compared to the effects associated with traditional exercise-based rehabilitation alone. Methods and Measures: Seventeen of 34 females (mean age, 28 years; range, 13-55 years) diagnosed with PFPS were randomly assigned to wear the Protonics system while participating in a conventional exercise-based rehabilitation program. Functional and patient-reported outcome measures were evaluated, including Kujala score and the lateral step-up test. In addition, measurements of hip internal and external rotation, hip extension, and iliotibial band muscle length were compared between groups. Results: Patients in both groups demonstrated improvement in Kujala score (P<.001), performance on the lateral step-up test (P<.001), and pain during the step-up test (P<.001) at the conclusion of the study. However, there was no difference between groups with respect to improvement in Kujala score (P = .33), step-up test performance (P = .47), or pain during the step-up test (P = .24). Patients using the Protonics system demonstrated greater gain in passive hip extension (P = .023) and increased hip external rotation motion (P = .017) at discharge versus patients treated with exercise alone. However, there was no difference in iliotibial band flexibility (P = .80) or hip internal rotation motion (P = .09) between groups. A greater proportion of patients in the Protonics group reported no pain with step-up testing at each 2-week interval. However, the 2.2 fewer visits required by patients in the Protonics group to meet discharge criteria did not achieve statistical significance (P = .08). Conclusions: Patients using the Protonics system demonstrated a shift in available hip rotation and increased passive hip extension flexibility. However, these changes were not outside the bounds of potential measurement error and did not translate into significant functional differences from a similar group treated with exercise alone. The economic implications of an average 2.2-visit decrease in treatment sessions per patient using the Protonics system are uncertain.

J Orthop Sports Phys Ther. 2005;35(4):210-219. doi:10.2519/jospt.2005.1566

Key Words: anterior knee pain, hip rotation, Kujala score, therapeutic exercise