Research Review By Dr. Brynne Stainsby©

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Background Information:

1. managing injury risk;
2. managing and progressing load;
3. rehabilitation; and
4. RTS with respect to shoulder injuries.

Summary:

• Risk Factors: Results are conflicting, however, some modifiable risk factors have been proposed, including reduced range of motion (ROM), rotational strength imbalance, muscle weakness, changes in load, player position, professional/amateur status, previous history of shoulder pain and psychosocial factors (3-6). It should be noted that the role of load is highly debated but may be considered important with overuse injuries and with impact (5-7). Potential risk factors should be discussed in a shared decision-making framework to determine whether mitigation strategies are warranted (8).
• Screening: There is a lack of evidence for predictive screening. Approximately half of the Delphi group recommended screening for scapular dyskinesis to help clinicians identify and address pre-existing issues to support RTS after shoulder injury, while the other half was against it. No tests were identified to support pre- or post-injury screens and as such, the experts present at the in-person meeting suggested a generic musculoskeletal screen including ROM, strength and any other sport-specific measurements.
• Exercise Programs: Injury prevention programs have a low risk of harm, are minimally invasive, easy to implement and may have preventive potential for all athletes. The Delphi group agreed that all athletes should receive injury prevention exercise programs. Primary prevention (pre-injury) should begin in youth athletes due to the high prevalence and persistence of shoulder problems in adolescent and elite athletes (9, 10). Secondary prevention (post-injury) exercise programs may begin immediately post-injury or may become a focus later in recovery.
• Implementing Exercise Programs: Although the evidence of exercise program effectiveness remains elusive, the Delphi group concurred that risk reduction can be achieved when the exercise programs are performed at least twice weekly. They also agreed that effective programs must support adherence, the education of coaches and athletes, and improve the attitude/self-efficacy of athletes towards participating in injury prevention programs (11-17).

• The balance between capacity and load appears to play an important role in injury risk management, rehabilitation, RTS and performance.
• Shoulder-specific loads vary with number of throws, playing position, type of training and intensity of training. It appears that high overall shoulder-specific load exposure of more than 16 hours per week (18) and large weekly increases in training (i.e. greater than 60% increase compared with the average of the previous four weeks) are associated with increased shoulder injury rate (10, 18).
• Recommendations based on total sporting exposure hours do not account for variations in internal load (i.e. physiological or psychological stress placed on the athlete during training or competition) – playing time or distance covered should not be the sole measure of load (19, 20).
• Experts at the in-person meeting suggested that asking athletes to rate their exertion following training/competition may be a potential option to capture internal load. It is unclear how well shoulder specific rate of perceived exertion (RPE) represents the psychophysiological construct of perceived exertion (fatigue, heaviness, discomfort) (21), although RPE has been strongly correlated to summated heart rate zone measures in youth soccer, rugby, and field hockey athletes (22). Shoulder-specific RPE could also be combined with other training-related factors (for example, number of collisions/impacts) (23). Although the literature is unclear, monitoring RPE may help to identify athletes who are challenged to maintain high levels of training by capturing subjective responses to physiological stimuli. This can be collected by coaches, clinicians, training staff or self-monitored to provide minimally invasive and low cost data.
• In a prospective study of handball athletes, players with reduced external rotation strength or scapular dyskinesis could withstand smaller increments in weekly load (training/match participation measured in hours) compared with stronger players/those without scapular dyskinesis (24). Based on these results, the experts suggested a minimum set of requirements for efficient workload monitoring for youth athletes in overhead and contact sports (including shoulder-specific RPE and repetition or collision counts), as well as for adult and professional athletes (Table 3 in the paper contains other examples). Future research is required to establish the validity and reliability of specific measures of shoulder load.

• Clinicians should consider athlete and sport-specific factors when designing a rehabilitation program for the injured athlete – a pathoanatomical diagnosis should not drive shoulder rehabilitation.
• Experts agreed that clinicians supporting athletes post-shoulder injury should aim to improve biomechanics/technique; increase intensity to challenge athletes at the limit of their capacity; build resilience; involve a multidisciplinary team in a shared decision-making process (including the coach and athlete) to support integrating rehabilitation and performance measures (8, 25).
• Clinicians should regularly test/monitor athletes throughout the rehabilitation process, using reliable and easily repeatable tests. Tools such as a handheld dynamometer, goniometer and outcome measures can be valuable for data collection, and the results should guide treatment planning and progression. If possible, aim to include the same relevant subjective and objective outcome measures that the athlete performs with the team in order to compare to pre-injury levels when possible.

1. Let irritability (pain at rest, pain at night, disability) guide the rehabilitation progress. This is a subjective measure based on the athlete’s tolerance.
2. Address clinically relevant glenohumeral ROM deficits using active exercises, rather than passive therapies.
3. Address the scapula in rehabilitation but do not screen for dyskinesis, as this may provide little to no clinical value as it is present in 53% of healthy individuals and 61% of overhead athletes (26, 27).
4. Select appropriate exercises depending on the specific injury and the phase of rehabilitation.
5. Include plyometric exercises early in the rehabilitation program to help athletes prepare for sport-specific loads
6. ”Train the Brain”: Capitalize on the brain’s plasticity to reverse the neurological changes that can occur after injury and last longer than the injury itself. Techniques such as gradual exposure to fearful movements, motor imagery and mirror neurons can be incorporated (28-30).
7. Incorporate sport-specific exercises, beginning with single-plane and progressing to complex, multiplane sport-specific exercises as soon as appropriate.

• The progression to RTS should encompass a continuum from return to participation (the athlete is active, but not yet “ready” to RTS fully), to RTS (athlete is returning, but participating below previous or “desired” level), to return to performance (returned to full/”desired” level without restrictions) (25).
• The Delphi panel outlined six domains (based on consensus) of body structure and function that affect successful RTS following shoulder injury – clinical reasoning is often complex and influenced by context beyond the control of the athlete or clinician.

1. Domain 1 – Pain: The consensus group recommended that athletes in overhead/throwing sports should be pain-free when they are expected to perform at their previous level of competition (i.e. return to performance). Contact-sport athletes should be pain-free before returning to participation or RTS.
2. Domain 2 – Active Shoulder ROM: The relevance of regaining full shoulder ROM is extremely sport-specific. It should be addressed early in the rehabilitation continuum. Following some injuries (such as surgical repair of traumatic shoulder instability), it may not be possible to achieve full, pre-injury ROM; consider the demands of the sport to guide return to competition.
3. Domain 3 – Strength, Power and Endurance: All sports with demands on the shoulder have a strength requirement, however, the specific strength, power and endurance components will vary depending on the sport and position. Clinicians should consider that most sports have multiple demands on the shoulder and be sure to account for the load in the deceleration phase of a movement. There was no consensus on the use of ER/IR ratios in contact sports, thus, it may be more appropriate to compare absolute strength measures to pre-injury tests in this population and clinicians should normalize results to body weight if performing between-athlete comparisons (29).
4. Domain 4 – Kinetic Chain: An efficient kinetic chain generates, aggregates and facilitates controlled mechanical energy transfer along the entire chain and contributes to enhanced performance (i.e. improved velocity or force). Identifying and addressing inadequate movement strategies along the length of the kinetic chain is important to the overall quality of the rehabilitation program (32).
5. Domain 5 – Psychological Readiness: The athlete must feel comfortable before progression through the RTS continuum. Prior to return to participation, there should be no apprehension with resistance training at the end range of shoulder ROM or throwing at specified intensities. Before RTS and performance, there should be no apprehension during contact and low fear of reinjury (25, 33).
6. Domain 6 – Sport-Specific: Knowing the demands of the athlete’s sport is critical to support a successful RTS. Consider the demands of the athlete’s sport and position, and compare to pre-injury baselines whenever possible.

Clinical Application & Conclusions:

Study Methods:

• This consensus statement follows principles outlined in the 2016 Bern consensus on RTS (25).
• A modified Delphi process was performed. First, two rounds of an online Delphi survey were conducted to identify areas of consensus, non-consensus (experts had mixed responses) and dissent (experts in consensus with their disagreement with a statement). Next, a smaller group of international experts who had participated in the original Delphi surveys participated in an in-person meeting to discuss and provide further guidance on topics of non-consensus.
• The intention of expert recruitment was to balance research and clinical experience, gender, nationality, and professional representation.
• The in-person meeting focused on crystallizing agreement from the Delphi survey and identifying additional areas of non-consensus to stimulate future research.
• To obtain evidence required for statement construction in the first Delphi round, a literature review was conducted. Five databases and the grey literature were searched. Articles were reviewed by consensus committee organizers, prioritizing systematic reviews, clinical practice guidelines and original research. Articles without an athletic context and papers focused solely on surgical management were excluded.
• Key themes were identified from the literature search, which then informed the statements constructed for the Delphi questionnaire. Two separate groups of questions focused on athletes in overhead/throwing sports and athletes in collision sports.
• Round 1 of the Delphi process had 54 questions focused on: risk factors/injury risk reduction; training loads; rehabilitation and management of the scapula; rotator cuff/post-dislocation shoulder/instability; sport-specific rehabilitation and progression; and RTS criteria. An 11-point scale (0-10) was used with an average rating of 7 set as the threshold for consensus.
• After analyzing feedback, additional questions were developed for Round 2, which were added to questions that failed to reach consensus in Round 1. Round 2 consisted of 25 questions.
• Given the wide variety of demands on the athletic shoulder, the authors accounted for the type of sport (above/below shoulder height; with/without throwing); reverse chain (where the upper limbs act primarily as the point of contact with the environment, such as climbing or rowing); with/without contact/collision.

Study Strengths / Weaknesses:

• Given this paper is a consensus statement, it provides a helpful overview of the available literature, as well as a structured approach to managing shoulder injuries.
• The authors emphasize the importance of frequent monitoring throughout the rehabilitation process and this paper provides many low cost/minimally invasive suggestions to monitor athletes following injury.
• A holistic approach, including neurological rehabilitation and subjective assessments of athlete’s apprehension around return to sport is recommended.
• This paper provides additional resources to support clinicians.

• The primary limitation of this paper is the lack of high-quality literature available, and as such, clinicians should approach the recommendations with some caution, pending further high quality evidence.
• Future and more specific research would be valuable to provide specific recommendations for specific sports.

Additional References:

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