STUDY DESIGN: Cross-sectional experimental laboratory study. OBJECTIVE: To examine differences in running mechanics between runners who had previously sustained iliotibial band syndrome (ITBS) and runners with no knee-related running injuries. BACKGROUND: ITBS is the second leading cause of knee pain in runners and the most common cause of lateral knee pain. Despite its prevalence, few biomechanical studies have been conducted to better understand its aetiology. Because the iliotibial band has both femoral and tibial attachments, it is possible that atypical hip and foot mechanics could result in the development of ITBS. METHODS: The running mechanics of 35 females who had previously sustained ITBS were compared to 35 healthy age-matched and running distance-matched healthy females. Comparisons of hip, knee, and ankle 3-dimensional kinematics and internal moments during the stance phase of running gait were measured. RESULTS: The ITBS group exhibited significantly greater peak rearfoot invertor moment, peak knee internal rotation angle, and peak hip adduction angle compared to controls. No significant differences in peak rearfoot eversion angle, peak knee flexion angle, peak knee external rotator moment, or peak hip abductor moments were observed between groups. CONCLUSION: Females with a previous history of ITBS demonstrate a kinematic profile that is suggestive of increased stress on the iliotibial band. These results were generally similar to those reported for a prospective study conducted within the same laboratory environment.

J Orthop Sports Phys Ther 2010;40(2):52-58. Epub 31 December 2009. doi:10.2519/jospt.2010.3028

KEY WORDS: ankle, biomechanics, foot, running

SYNOPSIS: The 21 muscles that cross the hip provide both triplanar movement and stability between the femur and acetabulum. The primary intent of this clinical commentary is to review and discuss the current understanding of the specific actions of the hip muscles. Analysis of their actions is based primarily on the spatial orientation of the muscles relative to the axes of rotation at the hip. The discussion of muscle actions is organized according to the 3 cardinal planes of motion. Actions are considered from both femoral-on-pelvic and pelvic-on-femoral perspectives, with particular attention to the role of coactivation of trunk muscles. Additional attention is paid to the biomechanical variables that alter the effectiveness, force, and torque of a given muscle action. The role of certain muscles in generating compression force at the hip is also presented. Throughout the commentary, the kinesiology of the muscles of the hip are considered primarily from normal but also pathological perspectives, supplemented with several clinically relevant scenarios. This overview should serve as a foundation for understanding the assessment and treatment of musculoskeletal impairments that involve not only the hip, but also the adjacent low back and knee regions.

J Orthop Sports Phys Ther 2010;40(2):82-94, Epub 14 January 2010. doi:10.2519/jospt.2010.3025

KEY WORDS: adductor magnus, biomechanics, gluteus maximus, gluteus medius, hip

SYNOPSIS: During the last decade, there has been a growing body of literature suggesting that proximal factors may play a contributory role with respect to knee injuries. A review of the biomechanical and clinical studies in this area indicated that impaired muscular control of the hip, pelvis, and trunk can affect tibiofemoral and patellofemoral joint kinematics and kinetics in multiple planes. In particular, there is evidence that motion impairments at the hip may underlie injuries such as anterior cruciate ligament tears, iliotibial band syndrome, and patellofemoral joint pain. In addition, the literature suggests that females may be more disposed to proximal influences than males. Based on the evidence presented as part of this clinical commentary, it can be argued that interventions which address proximal impairments may be beneficial for patients who present with various knee conditions. More specifically, a biomechanical argument can be made for the incorporation of pelvis and trunk stability, as well as dynamic hip joint control, into the design of knee rehabilitation programs. LEVEL OF EVIDENCE: Aetiology/therapy, level 5.

J Orthop Sports Phys Ther 2010;40(2):42-51. doi:10.2519/jospt.2010.3337

KEY WORDS: ACL, iliotibial band syndrome, patella, patellofemoral pain syndrome

SYNOPSIS: The organization of fibers within a muscle (architecture) defines the performance capacity of that muscle. In the current commentary, basic architectural terms are reviewed in the context of the major hip muscles and then specific illustrative examples relevant to lower extremity rehabilitation are presented. These data demonstrate the architectural and functional specialization of the hip muscles, and highlight the importance of muscle physiology and joint mechanics when evaluating and treating musculoskeletal disorders.

J Orthop Sports Phys Ther 2010;40(2):95-102. doi:10.2519/jospt.2010.3302

KEY WORDS: exercise, gluteus maximus, gluteus medius, hip, rehabilitation

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

The patient was a 22-year-old male who developed right mid-thigh pain after increasing his running mileage in a short period. Anterior-posterior and lateral radiographs of the femur were completed and interpreted as normal, and the patient was diagnosed with a muscle strain. Three months later the patient was seen by a sports medicine physician because of persistent right mid-thigh pain with running. Repeat radiographs revealed periosteal thickening of the medial cortex of the right femur consisten with a stress reaction and subtle irregular calcifications in the central diaphysis of the femur. The patient was diagnosed with a femoral shaft stress fracture and referred for magnetic resonance imaging, which revealed a lobular lesion occupying the marrow space of the femoral diaphysis that measure approximately 6.5 cm in the craniocaudal dimension. The patient was diagnosed with an echondroma of the distal femoral shaft. After pursuing a non-surgical course of care, the patient opted for surgical intervention based on continued pain and a desire to return to athletic activities.

J Orthop Sports Phys Ther 2010;40(2):121. doi:10.2519/jospt.2010.0403

KEY WORDS: femur, magnetic resonance imaging, radiographs

A selection of important abstracts of articles published in other journals.

J Orthop Sports Phys Ther 2010;40(2):123-128.