STUDY DESIGN: Prospective cohort study. OBJECTIVES: To characterize knee cartilage change in individuals with knee osteoarthritis (KOA) who have completed a therapeutic exercise program. BACKGROUND: While therapeutic exercise is frequently used successfully to improve pain and function in individuals with KOA, no studies have reported the volume of cartilage change or individual factors that may impact volume of cartilage change in those completing an exercise program for KOA. METHODS: Thirteen individuals with KOA underwent magnetic resonance imaging to quantify cartilage volume change in the weight-bearing regions of the medial and lateral femoral condyles and the entire surface of the tibial plateaus from baseline to 1-year follow-up. Body structure and function measures were taken for body mass index, knee axis alignment, knee motion, and knee strength. Activity limitations and activity levels were also measured prior to the therapeutic exercise program, using the Western Ontario and McMaster Universities Osteoarthritis Index and the Physical Activity Scale for the Elderly. At 6 months from baseline, follow-up clinical measurements of knee strength and motion were performed. At 1 year from baseline, imaging of the knee cartilage and knee alignment were performed, and participants completed the Western Ontario and McMaster Universities Osteoarthritis Index and Physical Activity Scale for the Elderly. RESULTS: The central region of the medial femoral condyle (cMF) had a median volume of cartilage loss of 3.8%. The other 3 knee tibiofemoral articular surfaces had minimal median cartilage volume change. Individuals were dichotomized into progressors (n = 6) and nonprogressors (n = 7), based on the standard error of measurement of cartilage volume change for the cMF. Progressors were younger, had a larger body mass index, had a higher Kellgren-Lawrence grade in the medial compartment of the knee, and had a greater increase in knee varus alignment from baseline to 1-year follow-up. The progressors also had frontal plane hip and knee kinetics during baseline gait analysis that potentially increased medial knee joint loading. CONCLUSION: The loss of cMF cartilage volume was highly variable and the median loss of cartilage was within the range previously reported. Seven of the 13 individuals did not have cMF cartilage volume loss greater than the standard error of measurement. Change in cartilage volume of the cMF may be influenced to a greater extent by personal factors than by completion of a therapeutic exercise program. Additional research is needed to decipher the interactions among therapeutic exercise and personal characteristics that impact knee cartilage loss.

J Orthop Sports Phys Ther 2011;41(10):708-722, Epub September 2011. doi:10.2519/jospt.2011.3633

KEY WORDS: arthritis, biomechanics, magnetic resonance imaging, MRI

STUDY DESIGN: Case report. OBJECTIVE: To highlight the effects of an intervention program consisting of strengthening and neuromuscular reeducation of the gluteus maximus in an elite triathlete with exercise-associated muscle cramping (EAMC). BACKGROUND: Researchers have described 2 theories concerning the etiology of EAMC: (1) muscle fatigue and (2) electrolyte deficit. As such, interventions for EAMC typically consist of stretching/strengthening of the involved muscle and/or supplements to restore electrolyte imbalances. CASE DESCRIPTION: The patient was a 42-year-old male triathlete with a primary complaint of recurrent cramping of his right hamstring muscle, which prevented him from completing races at his desired pace. Strength testing revealed gluteus maximus muscle weakness bilaterally. Electromyographic (EMG) analysis (surface electrodes, 1560 Hz) revealed that the right hamstrings were being activated excessively during terminal swing and the first half of the stance phase (48.1% maximum voluntary isometric contraction [MVIC]). OUTCOMES: Following the intervention, the patient was able to complete 3 triathlons without hamstring cramping. Strength testing revealed that the right hip extension strength improved from 35.6 to 54.7 kg, and activation of the hamstrings during terminal swing and the first half of the stance phase decreased to 36.4% of MVIC. DISCUSSION: A program of gluteus maximus strengthening and neuromuscular training eliminated EAMC of the hamstrings in this patient. Given that the hamstrings and gluteus maximus work as agonists to decelerate the thigh during terminal swing phase and control hip flexion during loading response of running, we postulate that strengthening of the gluteus maximus decreased the relative effort required by the hamstrings, thus reducing EAMC. The results of the EMG evaluation that was performed as part of this case report provides support for this hypothesis. LEVEL OF EVIDENCE: Therapy, level 4.

J Orthop Sports Phys Ther 2010;40(2):112-119, Epub 31 December 2009. doi:10.2519/jospt.2010.3110

KEY WORDS: hip, lower extremity, muscle cramping, running

STUDY DESIGN: Case report. OBJECTIVE: To describe an alternative treatment approach for piriformis syndrome using a hip muscle strengthening program with movement reeducation. BACKGROUND: Interventions for piriformis syndrome typically consist of stretching and/or soft tissue massage to the piriformis muscle. The premise underlying this approach is that a shortening or ìspasmî of the piriformis is responsible for the compression placed upon the sciatic nerve. CASE DESCRIPTION: The patient was a 30-year-old male with right buttock and posterior thigh pain for 2 years. Clinical findings upon examination included reproduction of symptoms with palpation and stretching of the piriformis. Movement analysis during a single-limb step-down revealed excessive hip adduction and internal rotation, which reproduced his symptoms. Strength assessment revealed weakness of the right hip abductor and external rotator muscles. The patientís treatment was limited to hip-strengthening exercises and movement reeducation to correct the excessive hip adduction and internal rotation during functional tasks. OUTCOMES: Following the intervention, the patient reported 0/10 pain with all activities. The initial Lower Extremity Functional Scale questionnaire score of 65/80 improved to 80/80. Lower extremity kinematics for peak hip adduction and internal rotation improved from 15.9° and 12.8° to 5.8° and 5.9°, respectively, during a step-down task. DISCUSSION: This case highlights an alternative view of the pathomechanics of piriformis syndrome (overstretching as opposed to overshortening) and illustrates the need for functional movement analysis as part of the examination of these patients. LEVEL OF EVIDENCE: Therapy, level 4.

J Orthop Sports Phys Ther 2010;40(2):103-111, Epub 31 December 2009. doi:10.2519/jospt.2010.3108

KEY WORDS: biomechanics, gluteus, hip pain, radiculopathy, sciatica

STUDY DESIGN: Experimental laboratory study. OBJECTIVES: To examine how a change in trunk position influences the kinematics, kinetics, and muscle activity of the lead lower extremity during the forward lunge exercise. BACKGROUND: Altering the position of the trunk during the forward lunge exercise is thought to affect the muscular actions of the lead lower extremity. However, no studies have compared the biomechanical differences between the traditional forward lunge and its variations. METHODS AND MEASURES: Ten healthy adults (5 males, 5 females; mean age ± SD, 26.7 ± 3.2 years) participated. Lower extremity kinematics, kinetics, and surface electromyographic (EMG) data were obtained while subjects performed 3 lunge exercises: normal lunge with the trunk erect (NL), lunge with the trunk forward (LTF), and lunge with trunk extension (LTE). A 1-way analysis of variance with repeated measures was used to compare lower extremity kinematics, joint impulse (area under the moment-time curve), and normalized EMG (highest 1-second window of activity for selected lower extremity muscles) among the 3 lunge conditions. RESULTS: During the LTF condition, significant increases were noted in peak hip flexion angle, hip extensor and ankle plantar flexor impulse, as well as gluteus maximus and biceps femoris EMG (P<.015) when compared to the NL condition. During the LTE condition, a significant increase was noted in peak ankle dorsiflexion and a significant decrease was noted in peak hip flexion angle (P<.015) compared to the NL condition. CONCLUSIONS: Performing a lunge with the trunk forward increased the hip extensor impulse and the recruitment of the hip extensors. In contrast, performing a forward lunge with the trunk extended did not alter joint impulse or activation of the lower extremity musculature. LEVEL OF EVIDENCE: Therapy, level 5.

J Orthop Sports Phys Ther. 2008;38(7):403-409, published online 15 April 2008. doi:10.2519/jospt.2008.2634

KEY WORDS: biomechanics, EMG, impulse, weight bearing