STUDY DESIGN: Controlled laboratory study using a cross-sectional, single testing session. OBJECTIVE: To determine the association between frontal plane knee excursion during a drop land task and measures of hip strength, and ankle and hip range of motion. BACKGROUND: Assessment of frontal plane knee excursion during a drop land task has been advocated as a means to screen for potentially injurious lower extremity movement patterns. Accordingly, an understanding of the physical characteristics associated with the magnitude of frontal plane knee excursion could assist clinicians in developing interventions and prevention strategies to minimize injury risk. METHODS AND MEASURES: Thirty-nine female high school soccer players (mean ± SD age, 15.5 ± 1.0 years; height, 162.2 ± 5.3 cm; body mass, 56.8 ± 6.7 kg) participated. Isometric hip muscle strength as well as ankle and hip range of motion measurements were obtained using standard clinical procedures and a handheld dynamometer. Frontal plane knee excursion was assessed using a 6-camera motion analysis system during a drop land task. Using 3-dimensional coordinate data, maximum frontal plane knee excursion was defined as the difference between the distances of right and left lateral knee markers at initial contact and maximum knee flexion during the deceleration phase of landing. Independent variables found to be significantly correlated with frontal plane knee excursion were then entered into a stepwise multiple regression procedure to determine the best set of predictors of this motion. RESULTS: Hip external rotation range of motion and ankle dorsiflexion range of motion were found to be negatively correlated with frontal plane knee excursion (r=-0.40, P=.005 and r=-0.27, P=.05, respectively). Together they accounted for 27% of the variance in frontal plane knee excursion (r=0.52, P=.03). No relationships between measures of hip strength and frontal plane knee excursion were found. CONCLUSIONS: Frontal plane knee excursion during a drop land task was partially attributed to available range of motion at the hip and ankle. These results suggest that range of motion of the joints proximal and distal to the knee should be considered when evaluating individuals who present with excessive frontal plane knee excursion during this task. Given that the relationship between range of motion and frontal plane knee excursion was small, other factors, including learned motor patterns, should be considered.

J Orthop Sports Phys Ther. 2008; 38(11):661-667; Epub 22 August 2008. doi:10.2519/jospt.2008.2695

KEY WORDS: knee injuries, kinematics, lower extremity, range of motion, strength

STUDY DESIGN: Case control study. 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 sample was comprised of 22 females with PFP (PFP group) and 22 females who had no knee pain (control group), matched by age, height, and body mass index to the subjects with PFP. 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 (lateral patellar displacement divided by patellar width), and medial patellar mobility index (medial patellar displacement divided by 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 mobility ± 2 SDs, 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 there 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. LEVEL OF EVIDENCE: Diagnosis, level 5.

J Orthop Sports Phys Ther. 2008;38(7):396-402, published online 12 March 2008. doi:10.2519/jospt.2008.2585

KEY WORDS: knee, patella, patellofemoral joint, reliability

At the time this study was conducted, there were no financial conflicts of interest with any of the authors. Subsequently, a version of the device described in this manuscript was manufactured and marketed by Matsumoto Prosthetics and Orthotics Manufacturing Co, LTD, located in Nagoya, Japan. Mr. Ota has a financial interest with this arrangement and acknowledges a potential conflict of interest.

Study Design: Repeated-measures, within-subject design.
Objective: To assess the concurrent criterion-related validity and reliability of a clinical device to quantify lateral patellar displacement.
Background: Excessive lateral displacement of the patella is an impairment that is widely associated with patellofemoral pain and/or pathology. Currently, no valid or reliable clinical method to assess lateral patellar displacement has been described in the literature.
Methods and Measures: A total of 26 individuals (14 asymptomatic and 12 symptomatic; mean ± SD age, 27 ± 4 years) participated in the validity portion of this study, while an additional 10 asymptomatic volunteers (mean ± SD age, 28 ± 5 years) participated in the reliability portion. Lateral displacement of the patella was assessed using a custom-designed patellofemoral arthrometer (PFA) and was compared to actual position of the patella as determined by magnetic resonance imaging (MRI). Both PFA and MRI measurements of lateral patellar displacement were made with the knee extended and the quadriceps contracted. The intraclass correlation coefficient (ICC) was used to assess the level of agreement between the PFA and MRI measurements, as well as the intrarater and interrater reliability of the PFA measurements.
Results: The ICC assessing the level of agreement between the MRI and PFA measures of lateral patellar displacement was good (0.86). Excellent intratester (ICC, 0.96 and 0.97) and intertester reliability (ICC, 0.92) were demonstrated.
Conclusion: Our results suggest that reasonable estimations of lateral patellar displacement can be obtained using the PFA.

J Orthop Sports Phys Ther. 2006;36(9):645-652. doi:10.2519/jospt.2006.2263

Key Words: knee, magnetic resonance imaging, patellar tracking, patellofemoral  joint