STUDY DESIGN: Controlled laboratory study. OBJECTIVES: To measure superior/inferior translation and external rotation of the humerus relative to the scapula during scapular plane abduction using 3-D/2-D model image registration techniques. BACKGROUND: Kinematic changes in the glenohumeral joint, including excessive superior translation of the humeral head and inadequate external rotation of the humerus, are believed to be a possible cause of shoulder impingement. Although many researchers have analyzed glenohumeral kinematics with various methods, few articles have assessed dynamic in vivo glenohumeral motion. METHODS: Twelve healthy males with a mean age of 32 years (range, 27-36 years) were enrolled in this study. Fluoroscopic images of the dominant shoulder during scapular plane elevation were taken, and computed tomography-derived 3-D bone models were matched with the silhouette of the bones in the fluoroscopic images using 3-D/2-D model image registration techniques. The kinematics of the humerus relative to the scapula were determined using Euler angles. RESULTS: On average, there was 2.1 mm of initial humeral translation in the superior direction from the starting position to 105° of humeral elevation. Subsequently, an average of 0.9 mm of translation in the inferior direction occurred between 105° and maximum arm elevation. The average amount of external rotation of the humerus was 14° from the starting position to 60° of humeral elevation. The humerus then rotated internally an average 9° by the time the shoulder reached maximum elevation. These changes in superior/inferior translation and external/internal rotation were statistically significant (P<.001 and P = .001, respectively), based on 1-way repeated-measures analysis of variance. CONCLUSION: The observed glenohumeral translations and rotations characterize healthy shoulder function and serve as a preliminary foundation for quantifying pathomechanics in the presence of glenohumeral joint disorders.

J Orthop Sports Phys Ther 2012;42(2):96-104, Epub 25 October 2011. doi:10.2519/jospt.2012.3584

KEY WORDS: 3-D/2-D registration, arthrokinematics, computed tomography, imaging, impingement

The convex-concave rules purportedly help describe the roll-and-slide relationships that naturally occur between moving articular surfaces. There are 2 components of this rule, depending on whether the convex or concave articular member of the joint is considered the moving segment. As a teacher of kinesiology and a physical therapist, I have always respected these rules, primarily because of their ability to assist with the mental imaging of joint motion. Recently, I have been perplexed by questions from experienced physical therapists as to why the convex-concave rules are still being taught in college or continuing education venues, when research has shown that they are flawed. Perhaps I am so hopelessly infatuated with, and blinded by, the educational charm and utility of the convex-concave rules that I fail to realize they are flawed. Are they? I don’t think so, which is the topic of this editorial.

J Orthop Sports Phys Ther 2012;42(2):53-55. doi:10.2519/jospt.2012.0103

KEY WORDS: arthrology, articular surfaces, kinesiology, morphology

STUDY DESIGN: Systematic review. OBJECTIVES: To systematically outline the risk factors for patellofemoral pain syndrome (PFPS). BACKGROUND: PFPS is the most commonly diagnosed condition in young individuals with knee complaints. High incidence among athletes suggests a possibility of prevention. The first step toward prevention is identification of possible risk factors. METHODS: Prospective studies that included 20 or more patients with PFPS and examined at least 1 possible risk factor for PFPS were included. An assessment list was applied to evaluate the quality of the studies. A meta-analysis was conducted using a random-effects model. Significant differences were based on calculated mean differences, with matching 95% confidence intervals (CIs). For dichotomous data, odds ratios or relative risks were calculated. RESULTS: Of the 3845 potentially relevant articles, 7 were included in this review. These studies examined a total of 135 variables, and pooling was possible for 13 potential risk factors. The pooled data showed that knee extension peak torques were significantly lower in the PFPS group than in controls. Mean differences in torque, with negative differences reflecting lower means in the PFPS group, were as follows: (a) standardized relative to body weight at 60°/s, –0.24 Nm (95% CI: –0.39, –0.09); (b) standardized relative to body weight at 240°/s, –0.11 Nm (95% CI: –0.17, –0.05); (c) standardized relative to body mass index at 60°/s, –0.84 Nm (95% CI: –1.23, –0.44); (d) standardized relative to body mass index at 240°/s, –0.32 Nm (95% CI: –0.52, –0.12); (e) nonstandardized in a concentric mode at 60°/s, –17.54 Nm (95% CI: –25.53, –9.54); (f) nonstandardized in a concentric mode at 240°/s, –7.72 Nm (95% CI: –12.67, –2.77). CONCLUSION: Weaker knee extension strength, expressed by peak torque, appears to be a risk factor for PFPS, based on meta-analyses of pooled results from multiple studies. Because several other risk factors for PFPS were described only in single studies, these additional risk factors, as well as those with conflicting evidence, need to be confirmed in future studies. LEVEL OF EVIDENCE: Prognosis, level 1a–.

J Orthop Sports Phys Ther 2012;42(2):81-94, Epub 25 October 2011. doi:10.2519/jospt.2012.3803

KEY WORDS: knee extension, knee flexion, literature review, meta-analysis, torque

STUDY DESIGN: Controlled laboratory study, longitudinal. OBJECTIVES: To investigate the effects of frequency and self-control of feedback on physiotherapy students learning lumbar spinal mobilization. BACKGROUND: Posterior-to-anterior mobilization is included in most physiotherapy curricula. However, force application varies between therapists and the optimal feedback for learning is unknown. METHODS: Sixty-two physiotherapy students were randomized to 3 feedback groups: constant (100% of practice trials), intermittent (33%), and self-controlled (varied according to student choice) feedback. Students performed 12 practice trials of grade II posterior-to-anterior mobilization to the third lumbar vertebra while receiving real-time feedback. The differences between students’ force parameters (mean peak force [N], force amplitude [N], and oscillation frequency [Hz]) and those of a physiotherapist expert were compared between groups posttest and at a follow-up of 5 to 7 days using analysis of covariance. Students completed a survey regarding their perceptions of feedback. RESULTS: Students in the self-controlled group applied mean peak force (mean difference between student and expert, 6.7 N; 95% confidence interval [CI]: 4.4, 9.0) and force amplitude (6.3 N; 95% CI: 4.2, 8.4) that more closely matched the expert’s than those applied by the constant group (13.7 N; 95% CI: 8.7, 18.6; P = .021, and 13.1 N; 95% CI: 8.9, 17.4; P = .028) at posttest, with similar results at follow-up for force amplitude only (self-controlled, 9.5 N; 95% CI: 5.8, 18.1; constant, 21.0 N; 95% CI: 13.3, 28.7; P = .018). There were no other significant differences. All students reported a better understanding of manual force application, but feedback preferences varied. CONCLUSION: Self-controlled feedback appears to be more beneficial than constant feedback for students learning to apply forces during lumbar mobilization.

J Orthop Sports Phys Ther 2012;42(2):114-124, Epub 25 October 2011. doi:10.2519/jospt.2012.3691

KEY WORDS: motor skills, musculoskeletal manipulations, physical therapy techniques, spinal manipulation, students

STUDY DESIGN: Case report. BACKGROUND: Rehabilitation that includes progressive quadriceps strengthening after total knee arthroplasty (TKA) leads to superior outcomes. Though patients with TKA show marked functional improvement after outpatient physical therapy, they continue to adopt movement asymmetries characterized by reduced knee excursion on the operated limb and excessive loading on the contralateral limb. The purpose of this case report was to describe the functional and biomechanical improvements in a patient who, after TKA, participated in a novel physical therapy protocol that included retraining of symmetrical movement patterns. CASE DESCRIPTION: A 57-year-old female with unilateral knee osteoarthritis was evaluated prior to TKA and at 3 and 10 weeks after surgery. Postoperative rehabilitation included progressive quadriceps strengthening and movement retraining that consisted of visual, verbal, and tactile feedback to promote symmetrical weight bearing during strengthening exercises and functional activities. Outcomes were compared to a historical cohort of patients with TKA. OUTCOMES: Prior to TKA, the patient scored below average on all functional measures and walked with knee biomechanics that were abnormal and asymmetrical. After symmetry retraining, her knee motion and moments were restored to normal levels. The patient also walked with greater magnitude and more symmetrical knee excursion compared to a cohort of similar patients. DISCUSSION: This case report describes the use of a novel rehabilitation protocol intended to improve walking biomechanics and functional outcomes after TKA. Restoration of symmetrical movement patterns could improve long-term outcomes of TKA. Further research is needed to evaluate the effectiveness and implementation of similar rehabilitation strategies in a wide range of patients after TKA. LEVEL OF EVIDENCE: Therapy, level 4.

J Orthop Sports Phys Ther 2012;42(2):135-144. doi:10.2519/jospt.2012.3773

KEY WORDS: motion analysis, osteoarthritis, physical therapy, rehabilitation, total knee replacement

Letters to the Editor-in-Chief of JOSPT as follows:

• "Including a Single Study Multiple Times in a Meta-analysis" and Authors' Response
• "Foot Strike Patterns in Runners" and Authors' Response