Context: Clinicians require portable, valid, and cost-effective methods to monitor knee joint-position-sense (JPS) ability. Objective: To examine the criterion-related validity of image-capture JPS measures against an isokinetic-dynamometer (IKD) procedure. Design: Random crossover design providing a comparison of knee JPS measures from image capture and IKD procedures. Participants: 10 healthy participants, 5 female, age 28.0 ± 13.29 y, mass 60.3 ± 9.02 kg, height 1.65 ± 0.07 m, and 5 male, 29.6 ± 10.74 y, mass 73.6 ± 5.86 kg, height 1.75 ± 0.07 m. Main Outcome Measures: The dependent variables were absolute error scores (AES) provided by 2 knee directions (flexion and extension). The independent variables were the method (image capture and IKD). Results: There was no significant difference between clinical and IKD AED into knee-extension data (P = .263, r = 0.55). There was a significant difference between clinical and IKD AES into knee-flexion data (P = .016, r =.70). Conclusions: Analysis of photographic images to assess JPS measurements using knee flexion is valid against IKD techniques. However, photo-analysis measurements provided a lower error score using knee-extension data and thus may provide an optimal environment to produce maximal knee JPS acuity. Therefore, clinicians do not need expensive equipment to collect representative JPS ability.
Nicola Relph and Lee Herrington
Nicola Relph and Lee Herrington
Context: Knee joint-position sense (JPS) plays a critical role in controlled and stable joint movement. Poor ability to sense position of the knee can therefore increase risk of injury. There is no agreed consensus on JPS measurement techniques and a lack of reliability statistics on methods. Objective: To identify the most reliable knee JPS measurement technique using image capture. Design: Interexaminer, intraexaminer, and test-retest reliability of knee JPS measurements. Setting: Biomechanics laboratory. Participants: 10 asymptomatic participants. Interventions: None. Main Outcome Measures: Relative and absolute error scores of knee JPS in 3 conditions (sitting, prone, active) through 3 ranges of movement (10-30°, 30-60°, 60-90°), into 2 directions (flexion and extension) using both legs (dominant and nondominant) collected during 15 trials and repeated 7 d after the first data collection. Results: Statistical analysis by intraclass correlations revealed excellent interexaminer reliability between researchers (.98) and intraexaminer reliability within 1 researcher (.96). Test-retest reliability was highest in the sitting condition from a starting angle of 0°, target angle through 60-90° of flexion, using the dominant leg and absolute-error-score variables (ICC = .92). However, it was noted smallest detectable differences were a high percentage of mean values for all measures. Conclusions: The most reliable JPS measurement for asymptomatic participants has been identified. Practitioners should use this protocol when collecting JPS data during prescreening sessions. However, generalizability of findings to a class/group of clients exhibiting knee pathologies should be done with caution.
Nicola Relph and Katie Small
Multi-day running events are increasingly popular, however, research on these events is lacking and fails to consider the dynamic nature of musculoskeletal physiology. Twenty-three athletes completing a 10-day marathon event participated in the study. Proprioception, dynamic balance, knee valgus, and flexibility were assessed the day before the event and after one, five, and nine consecutive marathons. There were significant reductions in these measurements across the event and reductions were more apparent in the nondominant side. Each runner suffered, on average, 4.2 injuries. Runners performed significantly worse in musculoskeletal measurements, particularly on the nondominant side, as the competition progressed. Therefore, athletic trainers should design appropriate between-day recovery strategies during events based on within-event data collection.
Charlie Bowen, Kristian Weaver, Nicola Relph and Matt Greig
Context: Training exposure has been associated with injury epidemiology in elite youth soccer, where lower-limb musculoskeletal screening is commonly used to highlight injury risk. However, there has been little consideration of the relationship between lower-limb screening and the loading response to soccer activities. Objective: To quantify the efficacy of using screening tests to predict the loading elicited in soccer-specific activities and to develop a hierarchical ordering of musculoskeletal screening tests to identify test redundancy and inform practice. Design: Correlational. Setting: Professional soccer club academy. Participants: A total of 21 elite male soccer players aged 15.7 (0.9) years. Intervention: Players completed a battery of 5 screening tests (knee to wall, hip internal rotation, adductor squeeze, single-leg hop, and anterior reach) and a 25-minute standardized soccer session with a Global Positioning System unit placed at C7 to collect multiplanar PlayerLoad data. Main Outcome Measures: Baseline data on each screening test, along with uniaxial PlayerLoad in the mediolateral, anteroposterior, and vertical planes. Results: Stepwise hierarchical modeling of the screening tests revealed that dominant leg knee-to-wall distance was the most prevalent and powerful predictor of multiplanar PlayerLoad, accounting for up to 42% of variation in uniaxial loading. The adductor squeeze test was the least powerful predictor of PlayerLoad. Of note, one player who incurred a knee injury within 3 weeks of testing had shown a 20% reduction in knee-to-wall distance compared with peers, and elicited 23% greater PlayerLoad, supporting the hierarchical model. Conclusions: There was some evidence of redundancy in the screening battery, with implications for clinical choice. Hierarchical ordering and a concurrent case study highlight dominant leg knee-to-wall distance as the primary predictor of multiaxial loading in soccer. This has implications for the design and interpretation of screening data in elite youth soccer.