STUDY DESIGN: Resident’s case problem. BACKGROUND: A 56-year-old man was referred to physical therapy for analysis of unusual gait, first noticed 3 years previously when running. Prior to this evaluation, the patient had seen multiple orthopaedic, sports medicine, and neurological specialists while undergoing repeated and extensive testing. Ten months of testing and treatment, including conservative and surgical management, did not provide an explanation for the gait abnormality or result in improvement of the patient’s condition. DIAGNOSIS: The patient’s physical examination was relatively unremarkable, considering the severity of the gait abnormality. Distinct abnormalities were apparent with computerized gait analysis and dynamic electromyography, and, when combined with the physical examination findings, led to a suspicion of the task-specific disorder of runner’s dystonia. The patient was referred to a neurologist specializing in movement-related disorders, with a final confirmed diagnosis of primary task-specific dystonia with first onset during running (ie, runner’s dystonia). DISCUSSION: Idiopathic, task-specific dystonia of the lower extremity is documented as a very rare occurrence, yet increasing trends in running participation may result in a higher incidence of this condition. Improved awareness of runner’s dystonia in the present case might have enhanced the clinical decision-making process and resulted in more timely and effective treatment solutions. Clinical examination findings, including computerized gait analysis and electromyography, in conjunction with imaging, blood, and genetic testing, can aid in the diagnosis of runner’s dystonia. LEVEL OF EVIDENCE: Differential diagnosis, level 4.

J Orthop Sports Phys Ther 2012;42(8):688-697, Epub 20 April 2012. doi:10.2519/jospt.2012.3892

KEY WORDS: differential diagnosis, electromyography, gait analysis, runner’s dystonia

STUDY DESIGN: A case-control study, with single observation. OBJECTIVES: To compare the onset timing and activation of the vastus medialis oblique (VMO) and vastus lateralis (VL) between subjects with and without patellofemoral pain syndrome (PFPS) at various step heights. BACKGROUND: It has been theorized that delayed or reduced VMO activity relative to the VL contributes to lateral patellar tracking and PFPS. However, conflicting evidence exists in the literature regarding this proposed mechanism. The lack of agreement among studies may be attributed to inconsistent knee flexion angles used in previous studies. METHODS AND MEASURES: Twenty subjects with PFPS (mean ± SD age, 29.5 ± 10 yrs) and 20 control subjeccts (mean ± SD age, 25.4 ± 3.1 yrs) ascended 5 different step heights, while knee kinematics and quadriceps EMG data were collected. Knee flexion angle at foot-step contact, VMO-VL onset timing, and VMO/VL activation ratios were analyzed between groups and step heights using 2-factor analyses of variance (ANOVAs) with repeated measures (α = .05). RESULTS: Individuals with PFPS demonstrated 4.7° (P = .038) more knee flexion at foot-step contact than control subjects. Despite greater knee flexion with increased step height (P‹.001), no differences in onset timing or activation magnitude ratio were present between groups or across step heights. However, individuals with PFPS displayed a significantly increased activation duration ratio compared to the control group (P = .043). CONCLUSION: Quadriceps onset timing and activation magnitude during stair ascent was similar between individuals with and without PFPS, regardless of step height. Thus, the results of this study are in agreement with evidence indicating no difference in VMO-VL timing and VMO/VL activation magnitude ratio between individuals with and without PFPS.

J Orthop Sports Phys Ther. 2007;37(5):239-244; published online 15 March 2007. doi:10.2519/jospt.2007.2421

KEY WORDS: activation ratio, anterior knee pain, EMG, onset delay, stair climbing