Comparison of Patellar Mobility in Female Adults With and Without Patellofemoral Pain

STUDY DESIGN: Case control study and repeated measurements. OBJECTIVE: To compare the patellar mobility of female adult subjects with and without patellofemoral pain (PFP). BACKGROUND: Although abnormal patellar mobility is believed to be one of the causes of PFP, there is currently no published evidence to support this contention. In part this lack of evidence is because a reliable clinical measurement method to measure patellar mobility and objective criteria to define abnormal patellar mobility have not been established. METHODS AND MEASURES: The study comprised 22 females with PFP (PFP group) and 22 females who had no knee pain (control group) who were matched to the subjects with PFP based on age, height, and body mass index. Patellar mobility was measured objectively using a specially designed apparatus. Measurements of lateral and medial patellar displacement, patellar mobility balance (lateral minus medial patellar displacement), lateral patellar mobility index (LPMI: lateral patellar displacement/ patellar width), and medial patellar mobility index (MPMI: medial patellar displacement/ patellar width) were used. RESULTS: Lateral and medial patellar mobility values were not significantly different between the individuals in the PFP and control groups. When normal patellar mobility was arbitrarily defined as the average ± 2SD based on the data from the control group, normal lateral patellar displacement was within a range of 7.2 to 17.6 mm and normal medial patellar displacement was within a range of 6.8 to 14.0 mm. The intraclass correlation coefficient for intratester and intertester reliability of lateral and medial patellar displacement measurements varied from 0.80 to 0.97. CONCLUSION: Although these were no significant differences in patellar mobility between females with and without PFP, these measurements give reference information about normal patellar mobility for this group.

J Orthop Sports Phys Ther., Epub 12 March 2008, doi:10.2519/jospt.2008.2585

KEY WORDS: knee, patella, patellofemoral joint, reliability

The authors compare the patellar mobility of female adult subjects with and without patellofemoral pain (PFP).