One of the most fundamental requirements of many statistical analysis procedures is that each data point must represent an independent observation. However, researchers in the field of musculoskeletal therapy are often faced with the dilemma of how to manage measurements obtained from both limbs of the same participant. In this situation, do we have a sample size of 30 participants, or 60 limbs? Similar problems are encountered in podiatry, where it is not uncommon for researchers to measure both feet, and ophthalmology, where measurements are frequently performed on both eyes. Failing to address the conceptual and statistical issues associated with paired data is common in musculoskeletal research and has the potential to seriously distort research findings.

J Orthop Sports Phys Ther. 2005; 35(8):477-478. doi:10.2519/jospt.2005.0108

Key Words: paired data, research, statistics

Study Design: Single-occasion, repeated-measures design. Objective: To determine the magnitude of hip abductor muscle activation during 6 rehabilitation exercises. Background: Many researchers have reported that hip strengthening, especially of the hip abductors, is an important component of a lower extremity rehabilitation program. Clinicians employ non–weight-bearing and weight-bearing exercise to strengthen the hip musculature; however, researchers have not examined relative differences in muscle activation during commonly used exercises. Information regarding these differences may provide clinicians with a scientific rationale needed for exercise prescription. Methods and Measures: Sixteen healthy subjects (mean ± SD age, 27 ± 5 years; range, 18-42 years; mean ± SD height, 1.7 ± 0.2 m; mean ± SD body mass, 76 ± 15 kg) volunteered for this study. Bipolar surface electrodes were applied to the right gluteus medius muscle. We measured muscle activation as subjects performed 3 non–weight-bearing (sidelying right hip abduction and standing right hip abduction with the hip at 0° and 20° of flexion) and 3 weight-bearing (left-sided pelvic drop and weight-bearing left hip abduction with the hips at 0° and 20° of flexion) exercises. Data were expressed as a percent of maximum voluntary isometric contraction of the right gluteus medius. Differences in muscle activation across exercises were determined using a 1-way analysis of variance with repeated measures, followed by a sequentially rejective Bonferroni post hoc analysis to identify differences between exercises. Results: The weight-bearing exercises demonstrated significantly greater EMG amplitudes (P<.001) than all non–weight-bearing exercises except non–weight-bearing sidelying hip abduction. Conclusion: The weight-bearing exercises and non–weight-bearing sidelying hip abduction exercise resulted in greater muscle activation because of the greater external torque applied to the hip abductor musculature. Although the non–weight-bearing standing hip abduction exercises required the least activation, they may benefit patients who cannot safely perform the weight-bearing or sidelying hip abduction exercises. Clinicians may use results from this study when designing hip rehabilitation programs.

J Orthop Sports Phys Ther. 2005;35(8):487-494. doi:10.2519/jospt.2005.2066

Key Words: gluteus medius, strengthening exercises, surface EMG

The metacarpophalangeal (MCP) joints bestow important strength to the longitudinal and transverse arch systems of the hand. In addition, these joints guide active movements of the fingers in 2 degrees of freedom, while allowing sufficient laxity for passive accessory motions. Both stability and mobility functions are attained in the healthy hand by a complex interaction among the muscles and the joints’ periarticular connective tissues. Rheumatoid arthritis (RA) often causes destruction of the MCP joints’ connective tissues, which leads to weakness of the tissues and an imbalance of active and passive forces, and subsequently, instability, pain, and deformity.

The 2 most common deformities of the MCP joints associated with RA and instability are palmar subluxation and ulnar ‘‘drift.’’ Therapists and physicians often collaborate to treat these conditions through a combination of surgical and nonsurgical interventions. Two of the more conservative nonsurgical interventions typically involve a combination of splinting and education on joint protection. Additional nonsurgical treatment may include the judicious use of exercise and methods for relieving pain and reducing inflammation. Surgical intervention is often indicated when the more conservative treatments fail to arrest the progression of the pain or deformity. Regardless of the specific approach, effective intervention for instability of the MCP joint requires that the clinician possess a sound knowledge of the anatomy and the pathomechanical influences that predispose or cause the instability.

This clinical commentary is intended to provide this information, as well as offer treatment guidelines based on our clinical experience. Whenever possible, research will be cited to support clinical interventions. This paper is especially geared to the therapist who may not currently specialize in the treatment of instability of the MCP joint but may require basic information on this important topic.

J Orthop Sports Phys Ther. 2005;35(8):502-520. doi:10.2519/jospt.2005.1863

Key Words: fingers, hand deformity, patient education, splinting

Study Design: Two-factor mixed-design study, with factors including group (control and noncoper) and task (sidestep, crossover, and straight). Objectives: To compare the knee and hip joint angles and moments of control subjects and subjects with an anterior cruciate ligament (ACL) deficient knee classified as noncopers, during a sidestep, crossover, and straight-ahead task. Background: Subjects with ACL deficiency primarily note difficulty with cutting tasks as opposed to straight-ahead tasks. Yet, previous studies have primarily focused on straight-ahead tasks. Methods and Measures: Fifteen subjects with ACL deficiency classified as noncopers, based on the number of giving-way episodes (>1) and global question of knee function (<60%), were included in this study. These subjects (10 male, 5 female; age range, 18-49 years) were compared to a healthy control group (7 male, 7 female; age range, 19-47 years). Position data collected at 60 Hz were combined with anthropometric and ground reaction force data collected at 420 Hz to estimate 3-dimensional knee and hip joint angles and moments. All subjects performed 3 tasks including a step and 45° sidestep cut, step and 45° crossover cut, and step and proceed straight. Two-way mixed-model ANOVAs were used to compare peak angle and moment variables between 10% to 30% of stance. Results: The ACL-deficient noncoper group had 1.8° to 5.7° less knee flexion angle compared to the control group across tasks (P<.043). The ACL-deficient noncoper group used 22% to 27% lower knee extensor moment during weight acceptance compared to the control group (P<.001). The sagittal plane hip extensor moments were 34% to 39% higher in the ACL-deficient noncoper group compared to the control group (P<.025). Hip frontal (P<.037) and transverse plane (P<.04) moments also distinguished the ACL-deficient noncoper from the control group. Conclusions: This study suggests that individuals who do not cope well after ACL injury rely on a hip control strategy during cutting tasks.

J Orthop Sports Phys Ther. 2005;35(8):531-540. doi:10.2519/jospt.2005.1763

Key Words: ACL, biomechanics, knee stability