STUDY DESIGN: Controlled laboratory study. OBJECTIVES: To compare hip and knee kinematics and pain during a single-limb squat between 3 movement conditions (usual, exaggerated dynamic knee valgus, corrected dynamic knee valgus) in women with patellofemoral pain. BACKGROUND: Altered kinematics (increased hip adduction, hip medial rotation, knee abduction, and knee lateral rotation, collectively termed dynamic knee valgus) have been proposed to contribute to patellofemoral pain; however, cross-sectional study designs prevent interpreting a causal link between kinematics and pain. METHODS: The study sample included 20 women with patellofemoral pain, who demonstrated observable dynamic knee valgus. Participants performed single-limb squats under usual, exaggerated, and corrected movement conditions. Pain during each condition was assessed using a 0-to-100-mm visual analog scale. Hip and knee frontal and transverse plane angles at peak knee flexion and pain levels were compared using repeated-measures 1-way analyses of variance. Pearson correlation coefficients were used to determine within-condition associations between kinematic variables and pain. RESULTS: In the exaggerated compared to the usual condition, increases were detected in hip medial rotation (mean ± SD difference, 5.8° ± 3.2°; P<.001), knee lateral rotation (5.5° ± 4.9°, P<.001), and pain (8.5 ± 10.8 mm, P = .007). In the corrected compared to the usual condition, decreases were detected in hip adduction (mean ± SD difference, 3.5° ± 3.7°; P = .001) and knee lateral rotation (1.6° ± 2.8°, P = .06); however, average pain was not decreased (1.2 ± 14.8 mm, P = 1.0). Pain was correlated with knee lateral rotation in the usual (r = –0.47, P = .04) and exaggerated (r = –0.49, P = .03) conditions. In the corrected condition, pain was correlated with hip medial rotation (r = 0.44, P = .05) and knee adduction (r = 0.52, P = .02). CONCLUSION: Avoiding dynamic knee valgus may be an important component of rehabilitation programs in women with patellofemoral pain, as this movement pattern is associated with increased pain.

J Orthop Sports Phys Ther 2012;42(12):1017-1024, Epub 5 September 2012. doi:10.2519/jospt.2012.4231

KEY WORDS: anterior knee pain, dynamic knee valgus, hip, knee, single-limb squat

STUDY DESIGN: Case report. BACKGROUND: Selecting the most effective conservative treatment for knee pain continues to be a challenge. An understanding of the underlying movement system impairment that is thought to contribute to the knee pain may assist in determining the most effective treatment. Our case report describes the treatment and outcomes of a patient with the proposed movement system impairment (MSI) diagnosis of tibiofemoral rotation. CASE DESCRIPTION: The patient was a 50-year-old female with a 3-month history of left anteromedial knee pain. Her knee pain was aggravated with sitting, standing, and descending stairs. A standardized clinical examination was performed and the MSI diagnosis of tibiofemoral rotation was determined. The patient consistently reported an increase in pain with activities that produced abnormal motions or alignments of the lower extremity in the frontal and transverse planes. The patient was educated to modify symptom-provoking functional activities by restricting the abnormal motions and alignments of the lower extremity. Exercises were prescribed to address impairments of muscle length, muscle strength, and motor control proposed to contribute to the tibiofemoral rotation. Tape also was applied to the knee in an attempt to restrict tibiofemoral rotation. OUTCOMES: The patient reported a cessation of pain and an improvement in her functional activities that occurred with correction of her knee alignment and movement pattern. Pain intensity was 2/10 at 1 week. At 10 weeks, pain intensity was 0/10 and the patient reported no limitations in sitting, standing, or descending stairs. The patient's score on the activities of daily living scale increased from 73% at the initial visit to 86% at 10 weeks and 96% at 1 year after therapy was discontinued. DISCUSSION: This case report presented a patient with knee pain and an MSI diagnosis of tibiofemoral rotation. Diagnosis-specific treatment resulted in a cessation of the patient's pain and an improved ability to perform functional activities. LEVEL OF EVIDENCE: Therapy, level 4.

J Orthop Sports Phys Ther. 2008;38(4):203-213, published online 21 November 2007. doi:10.2519/jospt.2008.2584

KEY WORDS: classification, functional activities, rehabilitation

J Orthop Sports Phys Ther. 2007;37(9):521-528, published online 12 July 2007. doi:10.2519/jospt.2007.2589

KEY WORDS: biomechanics, knee, MRI

Objective:To determine the effects of patellar taping on knee kinetics, kinematics, and vastus lateralis muscle activity during stair ambulation in individuals with patellofemoral pain (PFP).

Background: Patellar taping is a common treatment technique for individuals with PFP. Specific data on whether patellar taping improves gait variables, however, are limited.

Methods and Measures: Ten subjects with a diagnosis of PFP were studied (5 men, 5 women). The subjects’ mean age, height, and mass were 36.5 ± 11.1 years, 173.1 ± 10.3 cm, and 70.9 ± 13.3 kg, respectively. Lower extremity kinematics, ground reaction forces, and vastus lateralis EMG were obtained simultaneously while subjects ascended and descended stairs, under taped and untaped conditions. Knee moments were calculated using inverse dynamics equations. Four 2 ×2 (tape condition x stair condition) ANOVAs for repeated measures were generated for cadence and average stance phase knee extensor moment, knee flexion angle, and EMG.

Results: On the average, a 92.6% reduction in pain was observed following the application of tape. Increases in cadence, knee flexion angles, and knee extensor moments were observed under the taped condition for both stair ascent and descent; however, no difference in average vastus lateralis EMG was found.

Conclusions: Although patellar taping resulted in decreased pain and increased knee extensor moments, knee flexion angles, and cadence during stair ambulation, the vastus lateralis EMG activity level did not change with taping. Based on data from the vastus lateralis, care must be taken if improved gait parameters indicate change in muscle recruitment.

J Orthop Sports Phys Ther. 2002; 32(1):3–10.

Key Words: biomechanics, gait, patella, physical therapy

Study Design: Case report with repeated measures. Objectives: To describe the effects of a tendo-Achilles lengthening (TAL) and total contact casting (TCC) on wound healing, motion, plantar pressure, and function in a patient with diabetes mellitus, peripheral neuropathy, neuropathic ulcer, and limited dorsiflexion range of motion (DFROM). Background: Limited DFROM has been associated with increased forefoot pressures and skin breakdown. A TAL was expected to increase DFROM and reduce forefoot pressures during walking, but the influence on muscle performance and function was unknown. Methods and Measures: The patient was a 42-year-old man with a 20-year history of type 1 diabetes (NIDDM) and a recurrent neuropathic plantar ulcer. Outcome measures were DFROM, isokinetic plantar flexor muscle peak torque, in-shoe and barefoot peak plantar pressure, physical performance test (PPT) score, and peak ankle and hip moments during walking obtained from an automated gait analysis. All tests were completed pre-TAL, 8 weeks post-TAL (after immobilization in a TCC), and 7 months post-TAL. Results: The wound healed in 40 days. The TAL resulted in a sustained increase in DFROM (0 to 18°). Plantar flexor peak torque was reduced by 21% 8 weeks after the TAL compared with the torque before surgery but recovered fully at 7 months. Seven months following TAL, in-shoe forefoot peak plantar pressure was reduced by 55%, barefoot pressure decreased by 14%, PPT score increased by 24%, peak ankle plantar flexor moment remained decreased by 30%, and the peak hip flexor moment increased by 41% during walking. Conclusion: For this patient, a TAL resulted in short-term deficits in peak plantar flexor torque, but a 7-month follow-up showed improvements in ankle DFROM, walking ability, and a decrease in forefoot in-shoe peak plantar pressure.

J Orthop Sports Phys Ther. 2000;30(2):85-90.

Key Words: dorsiflexion range of motion, peak plantar pressure, physical performance test, plantar flexor moment

Study Design: Descriptive study to compare relationships between muscle performance measures in 2 subject groups. Objectives: To determine the relationships between plantar flexor (PF) muscle stiffness, strength (concentric peak torque), and dorsiflexion (DF) range of motion (ROM) in subjects with diabetes who have peripheral neuropathy (n = 17, 10 men, 7 women; age = 58 ± 11 years) and age-matched controls (n = 17, 10 men, 7 women; age = 62 ± 6 years). Background: The relationships between muscle stiffness, strength, and joint ROM have not been clearly established. Furthermore, the effect of neuromuscular pathology on these relationships is unknown. Methods and Measures: PF stiffness and strength measurements were obtained with an isokinetic dynamometer. DF ROM was measured with a goniometer. A Pearson correlation matrix was constructed for each subject group using stiffness, strength, and ROM variables. The percent contribution of passive torque to total torque was computed at 2 joint angles. Results: In subjects with diabetes and peripheral neuropathy (DM-PN) peak concentric PF torque was positively correlated with passive torque at 5° DF (r = 0.77), Stiffness #1 (r = 0.58), and Stiffness #2 (r = 0.50). The percentage of passive PF torque at 5° DF was greater in subjects with DM-PN, compared to control subjects (29.3 ± 9.4% versus 12.6 ± 5.9%). Conclusions: The positive correlation between PF stiffness and strength, and the greater percentage of passive PF torque in subjects with DM-PN suggest that patients with decreased strength may use passive torque to maximize total torque. Therefore, treatment methods designed to decrease stiffness should be used cautiously.

J Orthop Sports Phys Ther. 2000;30(8):473-483.

Key Words: active and passive tension, ankle joint, biomechanics