What is the incidence of subsequent adjacent joint injury after patellofemoral pain?

OBJECTIVE: To investigate the incidence of subsequent lumbar spine, hip, and ankle-foot injuries after a diagnosis of patellofemoral pain. DESIGN: Retrospective cohort study. SETTING: Military Health System. PARTICIPANTS: Individuals (n = 92,319) ages 17-60 diagnosed with patellofemoral pain between 2010-2011. INTERVENTIONS: Therapeutic exercise. MAIN OUTCOME MEASURES: Frequency of adjacent joint injuries in the 2-year period after initial patellofemoral pain injury, and hazard ratios (HR) with 95% confidence interval (CI) and Kaplan-Meier survival curves for risk of adjacent joint injury based on receiving therapeutic exercise for the initial injury. RESULTS: After initial patellofemoral pain diagnosis, 42,983 (46.6%) individuals sought care for an adjacent joint injury. Of these, 19,587 (21.2%) were subsequently diagnosed with a lumbar injury, 2837 (3.1%) a hip injury, and 10,166 (11.0%) an ankle-foot injury. One in five (19.5%; n = 17,966) received therapeutic exercise which reduced the risk of having a subsequent lumbar (HR = 0.78, 95% CI 0.76-0.81), hip (HR = 0.93, 95% CI 0.87-0.98) or ankle-foot (HR = 0.86, 95% CI 0.83-0.90) injury. CONCLUSION: The results suggest that a high number of individuals with patellofemoral pain will sustain an adjacent joint injury within 2 years although causal relationships cannot be determined. Receiving therapeutic exercise for the initial knee injury reduced the risk of sustaining an adjacent joint injury. This study helps provide normative data for subsequent injury rates in this population and guide development of future studies designed to understand causal factors.

Does sex affect second ACL injury risk? A systematic review with meta-analysis.

OBJECTIVE: To determine sex-based differences in risk of a second ACL injury (overall and by laterality) following primary ACL reconstruction in athletes who are attempting to return to sport. DESIGN: Systematic review with meta-analysis. DATA SOURCES: Systematic search of five databases conducted in August 2019. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Studies reporting sex-based differences in the incidence of second ACL injury in athletes attempting to return-to-sports and who were followed for at least 1 year following primary ACL reconstruction. RESULTS: Nineteen studies were included in this review, with seven studies excluded from the primary meta-analysis due to high risk of bias. The remaining 12 studies (n=1431 females, n=1513 males) underwent meta-analysis, with all 19 studies included in a sensitivity analysis. Total second ACL injury risk was 21.9% (females: 22.8%, males: 20.3%). Females were found to have 10.7% risk of an ipsilateral ACL injury and 11.8% risk of a contralateral ACL injury. Males were found to have 12.0% risk of an ipsilateral ACL injury and 8.7% risk of a contralateral ACL injury. No statistically significant differences were observed for total second ACL injury risk (risk difference=-0.6%, 95% CI -4.9 to 3.7, p=0.783, I2=41%) or contralateral ACL injury risk (risk difference=1.9%, 95% CI -0.5% to 4.4%, p=0.113, I2=15%) between sexes. Females were found to have a 3.4% absolute risk reduction in subsequent ipsilateral ACL injury risk compared with males (risk difference=-3.4%, 95% CI -6.7% to -0.02%, p=0.037, I2=35%). CONCLUSION: Both sexes have >20% increased risk of experiencing a second ACL injury. Any difference in the absolute risk of either a subsequent ipsilateral or contralateral ACL injury between sexes appears to be small. REGISTRATION: PROSPERO (CRD42020148369).

Examination of the Feasibility of a 2-Dimensional Portable Assessment of Knee Joint Stability: A Pilot Study.

Rupture of the anterior cruciate ligament (ACL) remains extremely common, with over 250,000 injuries annually. Currently, clinical tests have poor utility to accurately screen for ACL injury risk in athletes. In this study, the position of a knee marker was tracked in 2-dimensional planes to predict biomechanical variables associated with ACL injury risk. Three-dimensional kinematics and ground reaction forces were collected during bilateral, single-leg stop-jump tasks for 44 healthy male military personnel. Knee marker position data were extracted to construct 2-dimensional 95% prediction ellipses in each anatomical plane. Knee marker variables included: ellipse areas, major/minor axes lengths, orientation of ellipse axes, absolute ranges of knee position, and medial knee collapse. These variables were then used as predictor variables in stepwise multiple linear regression analyses for 7 biomechanical variables associated with ACL injury risk. Knee flexion excursion, normalized peak vertical ground reaction forces, and knee flexion angle at initial contact were the response variables that generated the highest adjusted R2 values: .71, .37, and .31, respectively. The results of this study provide initial support for the hypothesis that tracking a single marker during 2-dimensional analysis can accurately reflect the information gathered from 3-dimensional motion analysis during a task assessing knee joint stability.

Postural Stability Under Dual-Task Conditions: Development of a Post-Concussion Assessment for Lower-Extremity Injury Risk.

CONTEXT: Concussions are consequence of sports participation. Recent reports indicate there is an increased risk of lower-extremity musculoskeletal injury when returning to sport after concussion suggesting that achieving "normal" balance may not fully indicate the athlete is ready for competition. The increased risk of injury may indicate the need to refine a screening tool for clearance. OBJECTIVE: Assess the between-session reliability and the effects of adding a cognitive task to static and dynamic postural stability testing in a healthy population. SETTING: Clinical laboratory. PARTICIPANTS: Twelve healthy subjects (6 women; age 22.3 [2.9] y, height 174.4 [7.5] cm, weight 70.1 [12.7] kg) participated in this study. DESIGN: Subjects underwent static and dynamic postural stability testing with and without the addition of a cognitive task (Stroop test). Test battery was repeated 10 days later. Dynamic postural stability testing consisted of a forward jump over a hurdle with a 1-legged landing. A stability index was calculated. Static postural stability was also assessed with and without the cognitive task during single-leg balance. Variability of each ground reaction force component was averaged. MAIN OUTCOME MEASURES: Interclass correlation coefficients (ICC2,1) were computed to determine the reliability. Standard error of measure, mean standard error, mean detectable change, and 95% confidence interval were all calculated. RESULTS: Mean differences between sessions were low, with the majority of variables having moderate to excellent reliability (static .583-.877, dynamic .581-.939). The addition of the dual task did not have any significant effect on reliability of the task; however, generally, the ICC values improved (eyes open .583-.770, dual task .741-.808). CONCLUSIONS: The addition of a cognitive load to postural stability assessments had moderate to excellent reliability in a healthy population. These results provide initial evidence on the feasibility of dual-task postural stability testing when examining risk of lower-extremity musculoskeletal injury following return to sport in a concussed population.

Outcomes After Arthroscopic Rotator Interval Closure for Shoulder Instability: A Systematic Review.

PURPOSE: (1) To systematically assess the clinical outcomes of arthroscopic rotator interval closure (RIC) procedures for shoulder instability and (2) to report the different technical descriptions and surgical indications for this procedure. METHODS: Two independent reviewers searched 4 databases (PubMed, Embase, Web of Science, and Cochrane) from database inception until October 15, 2017. The inclusion criteria were studies that reported outcomes of shoulder stabilization using arthroscopic RIC as an isolated or adjunctive surgical procedure. The methodologic quality of studies was assessed with the Methodological Index for Non-Randomized Studies tool and Grading of Recommendations Assessment, Development and Evaluation system for randomized controlled trials. RESULTS: Fifteen studies met our search criteria (524 patients). Of the studies, 12 were graded Level IV evidence; 2, Level III; and 1, Level II. Six different RIC technique descriptions were reported, with 2 studies not defining the details of the procedure. The most common method of RIC was arthroscopic plication of the superior glenohumeral ligament to the middle glenohumeral ligament (8 of 15 studies). The most commonly used patient-reported outcome measure was the Rowe score, with all studies reporting a minimum postoperative score of 80 points. The rate of return to preinjury level of sport ranged from 22% to 100%, and the postoperative redislocation rate ranged from 0% to 16%. CONCLUSIONS: The indications for RIC were poorly reported, and the surgical techniques were inconsistent. Although most studies reported positive clinical results, the heterogeneity of outcome measures limited our ability to make definitive statements about which types of rotator interval capsular closure are warranted for select subgroups undergoing arthroscopic shoulder stabilization. LEVEL OF EVIDENCE: Level IV, systematic review of Level II through IV studies.

Relationship of performance on the sensory organization test to landing characteristics.

Jump landing tasks have been used to assess landing characteristics and require significant sensorimotor feedback to maintain functional joint stability (FJS) throughout the task. Postural stability (PS) also requires significant sensorimotor feedback and control and would seemingly involve similar sensory feedback pathways. However, previous literature clarifying the relationship between these two processes, maintaining FJS and PS, is limited. 80 Special Tactics Operators. PS was assessed using the Sensory Organization Test (SOT). SOT variables included: Composite, Somatosensory, Visual, Vestibular, and Preference scores. Landing characteristics were assessed using motion analysis during a double-legged (DLSJ) and single-legged (SLSJ) stop jump task. Pearson's correlation coefficients were calculated to assess the relationship between SOT scores and landing characteristics (α < .05). For the DLSJ, significant correlations were found between: Composite and peak posterior ground reaction forces (-.257), Vestibular and peak knee abduction moment (-.237), and Preference and initial contact hip flexion (-.297), peak hip flexion (-.249). For the SLSJ, significant correlations were found between: Somatosensory and peak vertical ground reaction forces (-.246); Preference and initial contact hip flexion (-.295), peak hip flexion (-.262). The results indicate that the SOT may not be a sensitive enough tool to assess sensorimotor control in a healthy, athletic population.

Postural stability deficit could predict ankle sprains: a systematic review.

PURPOSE: To perform a systematic review aimed to determine (1) if the postural stability deficit represents a risk factor for ankle sprains; (2) the most effective postural stability evaluation to predict ankle sprains and (3) eventual confounding factors that could influence postural stability and ankle sprain risk. METHODS: A systematic electronic search was performed in MEDLINE, EMBASE and CINAHL using the search terms (balance) OR (postural stability) matched with (lower limb) OR (ankle) OR (foot) and (sprain) OR (injury) on October 2 2017. All prospective studies that evaluated postural stability as risk factor for ankle sprains were included. The PRISMA Checklist guided the reporting and data abstraction. Methodological quality of all included papers was carefully assessed. RESULTS: Fifteen studies were included, evaluating 2860 individuals. Various assessment tools or instruments were used to assess postural stability. The injury incidence ranged from 10 to 34%. Postural stability deficit was recognized as risk factor for ankle sprain (OR = 1.22-10.2) in 9 cases [3 out of 3 with Star Excursion Balance Test (SEBT)]. Among the six studies that measured the center-of-gravity sway, five were able to detect worse postural stability in athletes that sustained an ankle sprain. In nine cases, the measurement of postural stability did not show any statistical relationship with ankle sprains (four out of five with examiner evaluation). In the studies that excluded patients with history of ankle sprain, postural stability was reported to be a significant risk factor in five out of six studies. CONCLUSIONS: The ultimate role of postural stability as risk factor for ankle sprains was not defined, due to the high heterogeneity of results, patient's populations, sports and methods of postural stability evaluation. Regarding assessment instruments, measurement of center-of-gravity sway could detect athletes at risk, however, standardized tools and protocols are needed to confirm this finding. The SEBT could be considered a promising tool that needs further investigation in wider samples. History of ankle sprains is an important confounding factor, since it was itself a source of postural stability impairment and a risk factor for ankle sprains. These information could guide clinicians in developing screening programs and design further prospective cohort studies comparing different evaluation tools. LEVEL OF EVIDENCE: I (systematic review of prospective prognostic studies).

The clinical and radiographic impact of center of rotation lateralization in reverse shoulder arthroplasty: a systematic review.

BACKGROUND: Reverse shoulder arthroplasty (RSA) has been widely adopted in the United States since its approval by the United States Food and Drug Administration in 2003. Advancements in metallurgy and design (including locking screws) have yielded clinically successful prostheses with a lateralized center of rotation (COR). This systematic review compared postsurgical outcomes and failure rates for lateral vs. medial COR RSA. We hypothesized that progressive lateralization of the COR results in greater ROM, improved clinical outcome scores, fewer acromial stress fractures, and less notching but a higher rate of glenoid implant baseplate failure and dislocation. METHODS: PubMed, Embase, Web of Science, CINAHL, and Cochrane databases were searched from inception through June 7, 2017, following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Eighteen articles were included after final review. Studies were stratified on whether a prosthesis with a lateral or medial COR was used. Comparisons included shoulder range of motion (ROM), functional outcome scores, and reported complications. RESULTS: RSA demonstrated significant improvements in outcome scores postsurgery regardless of prosthesis type. Overall, this study found no clear difference in outcome scores between the lateralized and medialized COR groups. The lateralized COR group displayed increased postoperative ROM. There was a higher reported incidence of scapular notching with medial COR prostheses. Otherwise, there were no clear differences in complications between the 2 groups. DISCUSSION: The data suggest no significant differences exist between groups in outcome scores. The lateralized COR prosthesis showed increased postoperative external rotation and decreased scapular notching. Additional well-constructed randomized controlled trials would allow more effective comparison of these prosthesis designs.

Gender Differences in Static and Dynamic Postural Stability of Soldiers in the Army's 101st Airborne Division (Air Assault).

CONTEXT: Postural stability is essential for injury prevention and performance. Differences between genders may affect training focus. OBJECTIVE: To examine static and dynamic postural stability in male and female soldiers. DESIGN: Descriptive laboratory study. SETTING: Biomechanics laboratory. PARTICIPANTS: 25 healthy female soldiers (26.4 ± 5.3 y) and 25 healthy male soldiers (26.4 ± 4.9 y) matched on physical demand rating and years of service from the Army's 101st Airborne Division (Air Assault). INTERVENTIONS: Each person underwent static and dynamic postural stability testing. MAIN OUTCOME MEASURES: Standard deviation of the ground reaction forces during static postural stability and the dynamic stability index for dynamic postural stability. RESULTS: Female soldiers had significantly better static postural stability than males but no differences were observed in dynamic postural stability. CONCLUSIONS: Postural stability is important for injury prevention, performance optimization, and tactical training. The differences observed in the current study may indicate the need for gender-specific training emphasis on postural stability.

Block-Periodized Training Improves Physiological and Tactically Relevant Performance in Naval Special Warfare Operators.

Human performance training and prevention strategies are necessary to promote physical readiness and mitigate musculoskeletal injuries of the Naval Special Warfare (NSW) Operator. The purpose of this study was to measure the effectiveness of 2 training programs when performed during a training evolution of Operators. A total of 85 Operators (experimental: n = 46, age: 29.4 ± 5.5 years, height: 176.7 ± 6.4 cm, mass: 86.7 ± 11.6 kg; control: n = 39, age: 29.0 ± 6.0 years, height: 177.1 ± 6.3 cm, mass: 85.7 ± 12.5 kg) participated in a trial to measure the effectiveness of these programs to improve physical, physiological, and performance characteristics. Operators in the experimental group performed a 12-week block-periodized program, whereas those in the control group performed a nonlinear periodized program. Pretesting/posttesting was performed to assess body composition, aerobic capacity/lactate threshold, muscular strength, flexibility, landing biomechanics, postural stability, and tactically relevant performance. The experimental group demonstrated a significant loss in body fat, fat mass, and body mass compared with the control group, whereas aerobic capacity increased for the both groups. The experimental group demonstrated a significant increase in posterior shoulder flexibility and ankle dorsiflexion, whereas the control group had a significant reduction in shoulder, knee, and ankle flexibility. The experimental group also improved landing strategies and balance. Both groups improved upper and lower muscular power and upper-body muscular endurance, whereas only the experimental group demonstrated significant improvements in agility and total body muscular strength. Implementation of a population-specific training program provides structured and progressive training effectively and promotes physical readiness concurrently with tactical training without overload.

Force Sense of the Knee Not Affected by Fatiguing the Knee Extensors and Flexors.

CONTEXT: Knee injuries commonly occur in later stages of competition, indicating that fatigue may influence dynamic knee stability. Force sense (FS) is a submodality of proprioception influenced by muscle mechanoreceptors, which, if negatively affected by fatigue, may result in less-effective neuromuscular control. OBJECTIVES: To determine the effects of peripheral fatigue on FS of the quadriceps and hamstrings. DESIGN: Quasi-experimental study design. PARTICIPANTS: 20 healthy and physically active women and men (age 23.4 ± 2.7 y, mass 69.5 ± 10.9 kg, height 169.7 ± 9.4 cm). INTERVENTIONS: Fatigue was induced during a protocol with 2 sets of 40 repetitions, and the last set was truncated at 90 repetitions or stopped if torque production dropped below 25% of peak torque. MAIN OUTCOME MEASURES: FS of the hamstrings and quadriceps was tested on separate days before and after 3 sets of isokinetic knee flexion and extension to fatigue by examining the ability to produce a target isometric torque (15% MVIC) with and without visual feedback (FS error). Electromyographic data of the tested musculature were collected to calculate and determine median frequency shift. T tests and Wilcoxon signed-rank tests were conducted to examine prefatigue and postfatigue FS error for flexion and extension. RESULTS: Despite verification of fatigue via torque-production decrement and shift in median frequency, no significant differences were observed in FS error for either knee flexion (pre 0.54 ± 2.28 N·m, post 0.47 ± 1.62 N·m) or extension (pre -0.28 ± 2.69 N·m, post -0.21 ± 1.78 N·m) prefatigue compared with the postfatigue condition. CONCLUSIONS: Although previous research has demonstrated that peripheral fatigue negatively affects threshold to detect passive motion (TTDPM), it did not affect FS as measured in this study. The peripheral-fatigue protocol may have a greater effect on the mechanoreceptors responsible for TTDPM than those responsible for FS. Further investigation into the effects of fatigue across various modes of proprioception is warranted.

The Effect of Target Position on the Accuracy of Cervical-Spine-Rotation Active Joint-Position Sense.

CONTEXT: The cervical spine can be divided into upper and lower units, each making a different contribution to the magnitude of rotation and proprioception. However, few studies have examined the effect of the cervical-rotation positions on proprioception. OBJECTIVE: To compare cervical-spine rotation active joint-position sense (AJPS) near midrange of motion (mid-ROM; 30°) and near end-ROM (60°). DESIGN: Cross-sectional study. SETTING: Human performance research laboratory. PARTICIPANTS: 53 military helicopter pilots (age 28.4 ± 6.2 y, height 175.3 ± 9.3 cm, weight 80.1 ± 11.8 kg). MAIN OUTCOME MEASURES: A motion-analysis system was used to record cervical-rotation kinematics. Subjects sat in a chair wearing a headband and blindfold. First, they actively rotated the head right or left to a target position (30°/60°), with real-time verbal cues provided by the tester. Subjects held the target position for 5 s and then returned to the start position. After this, they replicated the target position as closely as possible. Five trials were performed in both directions to both target positions (R30/R60/L30/L60). Order of direction/position was randomized. The difference between target and replicated positions was calculated and defined as absolute error (AE), and the mean of 5 trials was used for analyses. Wilcoxon signed-ranks tests were used to compare AJPS at the different target positions (P < .0125 with Bonferroni adjustments). RESULTS: End-ROM AEs were significantly more accurate than mid-ROM AEs (P = .001). CONCLUSION: Cervical-spine-rotation AJPS is more accurate near end-ROM than mid-ROM. Both target positions should be used to examine cervical-spine-rotation AJPS of both the upper and lower units.

Prediction of Dynamic Postural Stability During Single-Leg Jump Landings by Ankle and Knee Flexibility and Strength.

CONTEXT: Dynamic postural stability is important for injury prevention, but little is known about how lower-extremity musculoskeletal characteristics (range of motion [ROM] and strength) contribute to dynamic postural stability. Knowing which modifiable physical characteristics predict dynamic postural stability can help direct rehabilitation and injury-prevention programs. OBJECTIVE: To determine if trunk, hip, knee, and ankle flexibility and strength variables are significant predictors of dynamic postural stability during single-leg jump landings. DESIGN: Cross-sectional study. SETTING: Laboratory. PARTICIPANTS: 94 male soldiers (age 28.2 ± 6.2 y, height 176.5 ± 2.6 cm, weight 83.7 ± 26.0 kg). INTERVENTION: None. MAIN OUTCOME MEASURES: Ankle-dorsiflexion and plantar-flexion ROM were assessed with a goniometer. Trunk, hip, knee, and ankle strength were assessed with an isokinetic dynamometer or handheld dynamometer. The Dynamic Postural Stability Index (DPSI) was used to quantify postural stability. Simple linear and backward stepwise-regression analyses were used to identify which physical characteristic variables were significant predictors of DPSI. RESULTS: Simple linear-regression analysis revealed that individually, no variables were significant predictors of the DPSI. Stepwise backward-regression analysis revealed that ankle-dorsiflexion flexibility, ankle-inversion and -eversion strength, and knee-flexion and -extension strength were significant predictors of the DPSI (R2 = .19, P = .0016, adjusted R2 = .15). CONCLUSION: Ankle-dorsiflexion ROM, ankle-inversion and -eversion strength, and knee-flexion and -extension strength were identified as significant predictors of dynamic postural stability, explaining a small amount of the variance in the DPSI.

Salivary hormone response to 12-week block-periodized training in naval special warfare operators.

Naval Special Warfare (NSW) Operators are expected to maintain a high degree of physical readiness requiring continual operational training. The physiological and psychological demands associated with operational training can result in physiological consequences evidenced by hormonal alterations justifying the need for periodized training to maintain or improve physical readiness. This study examined the pattern and time course of hormone changes during 12-week block-periodized training program (BP) in NSW Operators undergoing routine training. Eighteen NSW Operators (31 ± 6 years, 86.6 ± 9.0 kg, 176.2 ± 5.9 cm, 17.5 ± 6.5% fat) participated in a 12-week BP during routine operational training. Salivary free testosterone (FT), dehydroepiandrosterone sulfate (DHEA-S), and cortisol (C) were obtained at 4 time points coincident with changes in intensity and volume. In the second block of training in which intensity and volume were increased, FT and C increased by 20.3 ± 7.4 and 20.8 ± 9.9%, respectively. Free testosterone and C returned to baseline values concomitant with the decrease in intensity and volume at the conclusion of the third block of training. No significant differences were observed in FT-to-C ratio over the course of training. DHEA-S increased 23.1 ± 11.0% following block 1, with a further increase observed following block 2 (57.0 ± 17.4%). Our data indicate training following BP produces a pattern and time course of hormone changes congruent with changes in intensity and volume suggesting BP as a potential training model for NSW Operators and other Special Forces Operators involved in operational training.

Reliability and validity of instrumented soccer equipment.

Ankle ligament sprains are the most common injury in soccer. The high rate of these injuries demonstrates a need for novel data collection methodologies. Therefore, soccer shoes and shin guards were instrumented with inertial sensors to measure ankle joint kinematics in the field. The purpose of this study was to assess test-retest reliability and concurrent criterion validity of a kinematic assessment using the instrumented soccer equipment. Twelve soccer athletes performed athletic maneuvers in the laboratory and field during 2 sessions. In the laboratory, ankle joint kinematics were simultaneously measured with the instrumented equipment and a conventional motion analysis system. Reliability was assessed using ICC and validity was assessed using correlation coefficients and RMSE. While our design criteria of good test-retest reliability was not supported (ICC > .80), sagittal plane ICCs were mostly fair to good and similar to motion analysis results; and sagittal plane data were valid (r = .90-98; RMSE < 5°). Frontal and transverse plane data were not valid (r < .562; RMSE > 3°). Our results indicate that the instrumented soccer equipment can be used to measure sagittal plane ankle joint kinematics. Biomechanical studies support the utility of sagittal plane measures for lower extremity injury prevention.

Neck proprioception, strength, flexibility, and posture in pilots with and without neck pain history.

INTRODUCTION: Neck pain (NP) is common among military helicopter pilots. Older age and more flight-hours have been associated with pilots with a history of NP. However, modifiable neuromuscular and musculoskeletal characteristics such as neck proprioception, strength, flexibility, and posture have rarely been investigated in military helicopter pilots with a history of NP. The purpose of the study was to compare demographics, flight characteristics, physical fitness information, neck proprioception, strength, flexibility, and posture between helicopter pilots with and without a history of NP. METHODS: A total of 27 Army helicopter pilots with NP in the past 12 mo (pain group) were matched based on age with pilots without a history of NP (nonpain group). All pilots had flown at least 100 h in the past 12 mo and were cleared for flight and physical training. All pilots completed a battery of laboratory testing: neck proprioception, neck and scapular muscular strength, neck active range-of-motion (ROM), forward head and shoulder posture, and pectoralis minor length. Paired t-tests or Wilcoxon tests were used to compare differences between groups. RESULTS: The pain group had significantly less cervical extension (63.7 +/- 8.5 degrees) and rotation ROM (R rotation: 67.7 +/- 8.8 degrees; L rotation: 67.4 +/- 9.0 degrees) when compared to the nonpain group (extension: 68.3 +/- 7.4 degrees; R rotation: 73.4 +/- 7.4 degrees; L rotation: 72.9 +/- 6.8 degrees). No significant differences were found for other variables. CONCLUSION: The results demonstrate less neck active ROM in pilots with a history of NP. Operating a helicopter with limited neck ROM or NP may negatively impact flight safety and force readiness. Continued research is warranted.

Relationship between tibial acceleration and proximal anterior tibia shear force across increasing jump distance.

Proximal anterior tibia shear force is a direct loading mechanism of the anterior cruciate ligament (ACL) and is a contributor to ACL strain during injury. Measurement of this force during competition may provide insight into risk factors for ACL injury. Accelerometers may be capable of measuring tibial acceleration during competition. The purpose of this study was to examine the relationship between acceleration measured by a tibia-mounted accelerometer and proximal anterior tibia shear force as measured through inverse dynamics and peak posterior ground reaction forces during two leg stop-jump tasks. Nineteen healthy male subjects performed stop-jump tasks across increasing jump distances. Correlation coefficients were calculated to determine if a relationship exists between accelerometer data and proximal anterior tibia shear force and peak posterior ground reaction force. An analysis of variance was performed to compare these variables across jump distance. Significant correlations were observed between accelerometer data and peak posterior ground reaction force, but none between accelerometer data and proximal anterior tibia shear force. All variables except peak proximal anterior tibia shear force increased significantly as jump distance increased. Overall, results of this study provide initial, positive support for the use of accelerometers as a useful tool for future injury prevention research.

Consortium for health and military performance and American College of Sports Medicine Summit: utility of functional movement assessment in identifying musculoskeletal injury risk.

Prevention of musculoskeletal injuries (MSKI) is critical in both civilian and military populations to enhance physical performance, optimize health, and minimize health care expenses. Developing a more unified approach through addressing identified movement impairments could result in improved dynamic balance, trunk stability, and functional movement quality while potentially minimizing the risk of incurring such injuries. Although the evidence supporting the utility of injury prediction and return-to-activity readiness screening tools is encouraging, considerable additional research is needed regarding improving sensitivity, specificity, and outcomes, and especially the implementation challenges and barriers in a military setting. If selected current functional movement assessments can be administered in an efficient and cost-effective manner, utilization of the existing tools may be a beneficial first step in decreasing the burden of MSKI, with a subsequent focus on secondary and tertiary prevention via further assessments on those with prior injury history.

Throwing Shoulder Adaptations Are Not Related to Shoulder Injury or Pain: A Preliminary Report.

BACKGROUND: Overhead throwing in baseball and softball athletes induces shoulder adaptations theorized to increase risk of shoulder musculoskeletal injury (MSI) and/or pain due to range of motion (ROM) deficits. HYPOTHESIS: Shoulder ROM adaptations are associated with a higher risk for developing shoulder MSI and pain. STUDY DESIGN: Prospective cohort study. LEVEL OF EVIDENCE: Level 3. METHODS: A total of 60 National Collegiate Athletic Association Division I athletes cleared for full athletic participation and free from upper extremity MSI in the last 4 weeks (age, 19.0 ± 1.2 years; weight, 82.1 ± 13.7 kg; height, 178.6 ± 11.2 cm; softball, n = 23; baseball, n = 37). Passive glenohumeral internal rotation (IR), external rotation (ER), and horizontal adduction (HA) ROM were measured with the scapula stabilized and used to categorize participants with/without external rotation gain (ERG), external rotation insufficiency (ERI), glenohumeral internal rotation deficit (GIRD), pathological GIRD, and posterior shoulder tightness (PST) before the competitive season. Groups were then compared to assess the incidence of shoulder MSI prospectively and prevalence of shoulder pain at the initial evaluation. RESULTS: Baseball and softball athletes demonstrated significantly less IR ROM in the dominant shoulder (50.6° ± 9.4°) compared with the nondominant shoulder (59.1° ± 8.6°; P < 0.01) and significantly more ER ROM (dominant, 104.6° ± 12.1°; nondominant, 97.7° ± 12.0°; P < 0.01). Incidence of shoulder MSI was 15% but was not significantly related to any shoulder adaptations. No significant relationship was found between prevalence of pain and any shoulder adaptations in the 27% of athletes with pain. CONCLUSION: Increased ER and decreased IR ROM adaptations in intercollegiate overhead throwing athletes do not appear to be correlated to risk of shoulder MSI or pain. CLINICAL RELEVANCE: The findings of this level 3 prospective study provide clinicians working with overhead athletes information regarding shoulder MSI risk and pain. It is recommended that clinicians should not use ROM adaptations exclusively to determine increased risk of shoulder MSI.