Mechanisms of traumatic injury to the shoulder girdle in the Australian Football League

Validity of Video-Based Analysis for Analyzing Shoulder Injuries in the National Basketball Association

Background

Shoulder injuries are very common in athletes playing in the National Basketball Association (NBA). With increasing injury video uploads available online, we may be able to identify and systematically describe the mechanism of these injuries in these athletes.

Purpose

To (1) determine the validity of video-based analysis to evaluate mechanisms of shoulder injuries in NBA players during the 2010-2020 seasons and (2) report on commonly sustained injuries, circumstances associated with injury, and number of games missed owing to injury.

Study Design

Cross-sectional study; Level of evidence, 3.

Methods

An injury report data set was queried for shoulder injuries among NBA players between the 2010-2011 season and the 2019-2020 season, and results were cross-referenced using YouTube.com to identify high-quality videos of the injuries. Out of 532 shoulder injuries in this time frame, video evidence from 39 (7.3%) were evaluated for mechanism of injury and other corresponding situational data. From the remaining shoulder injuries, a randomly selected control cohort of 50 injuries occurring in the same interval was assessed for descriptive injury data, incidence of recurrence, necessity for surgery, and number of games missed, to compare with corresponding data from injuries in the videographic evidence cohort.

Results

In the videographic evidence cohort, the most common mechanism of injury was lateral contact to the shoulder (41%; P < .001), which was associated with an injury to the acromioclavicular joint (30.8%; P < .001). Injuries occurred more often when the team was on offense (58.9%; P < .001) versus defense. Players who required surgery missed 33 more games on average than players who did not require surgery (P < .001). For the injured players, a 33% incidence of reinjury was identified in the 12 months after their initial injury. As compared with the control cohort, no significant differences were noted in injury laterality, recurrence rates, necessity for surgical management, time in the season, or number of games missed.

Conclusion

Despite its low yield of 7.3%, video-based analysis may be a useful tool to determine the mechanism of shoulder injuries in the NBA, given the similarities of injury characteristics as compared with the control group.

Glenoid Track Width Is Smaller Under Dynamic Conditions: An In Vivo Dual-Fluoroscopy Imaging Study

BACKGROUND

The glenoid track concept has been widely used to assess the risk of instability due to bipolar bone loss. The glenoid track width was commonly used as 83% of the glenoid width to determine if a lesion was on-track or off-track. However, the value was obtained under static conditions, and it may not be able to reflect the actual mechanism of traumatic dislocation during motion.

PURPOSE

To compare the glenoid track width under dynamic and static conditions using a dual-fluoroscopic imaging system.

STUDY DESIGN

Controlled laboratory study.

METHODS

In total, 40 shoulders of 20 healthy volunteers were examined for both dynamic and static tests within a dual-fluoroscopic imaging system at 5 different arm positions: 30°, 60°, 90°, 120°, and 150° of abduction, keeping the shoulder at 90° of external rotation. The participants performed a fast horizontal arm backswing for dynamic tests while keeping their arm in maximum horizontal extension for static tests. Computed tomography scans were used to create 3-dimensional models of the humerus and scapula for 2-dimensional to 3-dimensional image registration. Magnetic resonance imaging scans were obtained to delineate the medial margin of the rotator cuff insertion. The glenoid track width was measured as the distance from the anterior rim of the glenoid to the medial margin of the rotator cuff insertion and compared between static and dynamic conditions.

RESULTS

The mean glenoid track widths at 30°, 60°, 90°, 120°, and 150° of abduction were significantly smaller under dynamic conditions (88%, 81%, 72%, 69%, and 68% of the glenoid width) than those under static conditions (101%, 92%, 84%, 78%, and 77% of the glenoid width) (all P < .001). The glenoid track width significantly decreased with the increasing abduction angles in the range of 30° to 120° under static conditions (all P < .003) and 30° to 90° under dynamic conditions (all P < .001).

CONCLUSION

A smaller dynamic-based value should be considered for the glenoid track width when distinguishing on-track/off-track lesions. Clinical evidence is needed to establish the superiority of the dynamic-based value over the static-based value as an indicator for augmentation procedures.

CLINICAL RELEVANCE

Some off-track lesions might be misclassified as on-track lesions when the original commonly used static-based value of 83% is used as the glenoid track width.

Video Analysis of Pectoralis Major Injuries in Professional Australian Football Players

Background:

There is little evidence regarding the mechanisms of pectoralis major (PM) injury and player outcomes in Australian Football League (AFL) players.

Purposes/Hypothesis:

The study aims were to investigate (1) the mechanisms of PM muscle injury in elite AFL players via video analysis and (2) the player profile, method of management, and clinical outcomes of the PM injuries sustained. We hypothesized that the majority of PM tears would occur in outer-range PM positions (hyperextension of the glenohumeral joint).

Study Design:

Case series; Level of evidence, 4.

Methods:

We analyzed video of the precipitating event for traumatic PM injuries during AFL competition or training over a 20-year period (2002-2021). The footage was analyzed by 4 experienced assessors, and the following were evaluated: mechanism of injury, injury variables (arm position, initial contact point, visual awareness, and use of taping), player characteristics (age at the time of injury, hand dominance, and history of injury), injury profile (location and size of tear), method of management (operative vs nonoperative), patient outcomes (time to return to full senior training/match play), and complication rates.

Results:

The mean ± standard deviation age of the players was 26.5 ± 3.1 years (range, 21-32 years). Overall, 22 PM injuries were identified in the AFL injury database for a rate of 1.1 per year; 16 of these injuries had accompanying video footage. We identified 3 mechanisms for PM injury: horizontal hyperextension (62.5%), hyperflexion-abduction (25.0%), and horizontal adduction (sustained tackling; 12.5%). The most common site of the tear was the insertion point of the sternocostal head (91.0%). Twenty players (91.0%) required surgical repair, with 75% undergoing surgery within 1 week (range, 0-26 weeks). The mean return to competition for the surgical repair group was 11.1 weeks (range, 8-15 weeks). The rerupture rate was 5.0% (1 repair; <4 weeks postoperatively in 2004).

Conclusion:

PM tears in elite male AFL players were due to 1 of 3 distinct mechanisms: horizontal hyperextension, hyperflexion-abduction, and horizontal adduction (sustained tackling). Players returned to play on average 11 weeks after injury. Knowledge regarding mechanisms of injury, player profile, and return-to-sport timelines is important for appropriate medical management and provides potential areas to target for prevention of PM injuries.

Pre-season screening of the upper body and trunk in Australian football players: A prospective study

OBJECTIVE

To determine whether screening tests of upper body, trunk region, and of whole-body function could prospectively identify community AFL players who sustain in-season shoulder/head/neck injuries. Additionally, to present screening test reference values.

DESIGN

Prospective cohort; SETTING: Community sport; PARTICIPANTS: 142 male community AFL players (range 15-37 years).

MAIN OUTCOME MEASURES

(i) isometric shoulder external and internal rotation (ER/IR) strength; (ii) upper body combined elevation functional ROM; (iii/iv) whole-body functional jump ROM; (v) static thoracic spine angle; (vi) cervical joint proprioception, and (vii) trunk muscle size and function. Results were compared among players with (n = 21) and without (n = 121) an in-season shoulder, head, or neck injury. ROC analysis and odds ratios were used to determine the predictive values.

RESULTS

Two screening tests predicted an in-season shoulder, head, or neck injury; dominant and non-dominant isometric ER strength (AUC 0.629, 95%CI 0.51-0.74; optimal cut point 182 N and AUC 0.619, 95%CI 0.50-0.74; optimal cut point 184 N, respectively). The adjusted odds ratio for the strongest predictor: dominant ER muscle strength was 6.02 (95%CI 1.8-19.9).

CONCLUSION

Greater ER strength was associated with in-season shoulder/head/neck injuries in community AFL players; however, further research is required to determine the clinical significance of this finding.