Common, mostly in matches, and mostly in the tackleStrong evidence
Across 37 studies (10,093 players, nearly all men), shoulder injuries ran at 11.02 per 1,000 match hours against 0.20 per 1,000 training hours, and cost 57 days on average: "Shoulder injuries in rugby occur far more often in matches than in training, result in prolonged time loss, and are most sustained in tackling". In the English Premiership, "A mean of 241 player-days per club per season were lost to shoulder injuries". In English community clubs, "A total of 254 time-loss shoulder injuries were reported, an overall incidence of 2.2 per 1 000 h (95% CI: 1.9 to 2.4), and a mean injury severity of 9.5 weeks missed (95% CI: 8.2 to 10.8)" (h is hours, CI the confidence interval), most in back-row forwards.
In Irish schoolboys aged 17 to 19, "The tackle accounted for the majority (81%) of shoulder injuries". In elite women, the shoulder was the commonest upper limb injury site, and in rugby league "the shoulder has now been reported to be the most common injury site". These studies count injuries that cost playing time; knocks that cost none aren't counted, and no study gave the share of minor shoulder injuries. Many players carry niggles: in 86 uninjured players mid-season, "55% of players reported a level of RSS dysfunction despite being uninjured" (RSS is the Rugby Shoulder Score).
Sources 1, 2, 3, 4, 5, 6, 7
How it happens: the tackler, the try-scorer and the direct blowEmerging evidence
In 24 elite players referred to a shoulder surgeon, video showed three patterns: "These are the 'Try-Scorer', characterised by hyperflexion of the outstretched arm such as when scoring a try; the 'Tackler', extension of the abducted arm behind the player while tackling; and the 'Direct Impact', a direct blow to the arm or shoulder when held by the side in neutral or slight adduction". In plain words: the arm reaching forward to score, the arm forced back while tackling, and a blow with the arm at the side. "The injury occurred during a tackle in 17 (71%), ruck or maul in 3 (12.5%), open play in 3 (12.5%) and scrum in 1 (4%)".
In Super Rugby, "Direct impact to the shoulder, either through player-to-player contact or contact with the ground, is the main cause of shoulder injury". Our rugby page adds arm tackles with the arm stretched out, and a lowered head in front of the ball carrier, as the risky tackles. Video case series show how injuries happen, not why one player is hurt and another isn't.
Sources 8, 9
The AC joint: the commonest, and usually a sprainEmerging evidence
In the Premiership, "The most common match injury was acromioclavicular joint injury (32%); the most severe was shoulder dislocation and instability (mean severity, 81 days absent), which also caused the greatest proportion of absence (42%) and had the highest rate of recurrence (62%)". The American Academy of Orthopaedic Surgeons (AAOS): "The most common cause of a separation of the AC joint is a fall directly onto the shoulder", and "Good pain-free function often returns even with a very large bump".
In US military cadets, where "The intercollegiate sports of men's rugby, wrestling, and hockey had the highest incidence rate of AC joint injury", "The majority of the AC joint injuries were low-grade (145 sprains, 89%) injuries, with 17 high-grade injuries", and "The average time lost to injury for low-grade sprains was 10.4 days compared with high-grade injuries at 63.7 days". In an older survey, "In a random sample of 105 first class rugby players, 45% gave a history of injury of the acromioclavicular joint", and "All continued to play at the highest level". A broken collarbone can look the same, as the warning signs say.
Sources 2, 10, 11, 12
Dislocation and instability: young men often dislocate againStrong evidence
The AAOS: "Usually, a dislocation from an injury is very painful and obvious", while a partial dislocation (subluxation) "can be harder to detect". In 252 people aged 15 to 35 treated in a sling, "instability developed in 55.7% of the shoulders within the first two years after the primary dislocation and increased to 66.8% by the fifth year", and "There is substantial variation in the risk of instability, with younger males having the highest risk and females having a much lower risk".
Across 10 studies, "Recurrent instability following a first-time traumatic anterior shoulder dislocation was 39%", much higher in people aged 40 or under, in men and in people with loose joints. In Japanese school players, "During the season, 54.3% of the shoulders with at least one episode of shoulder dislocation had reinjury". In the Premiership, dislocation and instability cost 81 days on average and recurred most.
Sources 13, 14, 15, 16, 2
Labral tears, the rotator cuff and stingersEmerging evidence
In professional players whose shoulder pain didn't settle with rehabilitation, "A superior labrum anterior to posterior (SLAP) lesion was evident at arthroscopy in 72 of the 87 cases (83%), while rotator cuff tears were evident in 43% of cases (n = 37)", and "in 30% of the cases, no definite injury could be recalled". These are selected players with lasting problems, not all players. "Rotator cuff injury is uncommon in contact sports and there is little published literature on the treatment of rotator cuff tears in rugby players"; in the video series, the try-scoring fall caused 5 of the 6 cuff tears.
The AAOS: "Burners and stingers are injuries that occur when nerves in the neck and shoulder are stretched or compressed (squeezed together) after an impact", and "In most cases, burners and stingers are temporary, and symptoms quickly go away". In 569 young Japanese players, 20.9% had at least one in a season, and "Although nearly 80% of the players experienced only minimal (0-1 day) time loss injuries, neurological deficits sometimes last beyond 1 month". Severe nerve injuries are rare: a national nerve injury unit described 13 from tackles, in which "The pattern of nerve lesion was related to the posture of the neck and the forequarter at the moment of impact". Most stinger evidence comes from American football.
Sources 17, 18, 8, 19, 20, 21, 22
When a scan or test mattersEmerging evidence
For a stinger, the AAOS says "Imaging tests, such as X-rays, magnetic resonance imaging (MRI) scans, and nerve studies are not usually needed" unless symptoms last or there are warning signs. After a dislocation, the NHS: "You will usually have an X-ray to check your shoulder is dislocated", and "You may be offered a scan to check if your shoulder has been damaged". The AAOS: "An X-ray is necessary to determine if there is a bone injury", while "an MRI is rarely required at the time of the dislocation". Across 8 emergency department studies, "The prevalence of concomitant fracture was 17.5%": about 1 in 6 dislocated shoulders also had a broken bone.
An AC joint injury is graded on X-ray. MRI scans of sore professional shoulders often show several findings, "and many have two or more abnormalities", so a scan answers a question the examination raises.
Sources 19, 23, 13, 24, 10, 25
What usually happensEmerging evidence
Shoulder pain in general: the NHS says "You usually need to do these things for 2 weeks before shoulder pain starts to ease" and "It can take 6 months or longer to recover from shoulder pain". AC joint: low-grade sprains cost about 10 days and high-grade injuries about 2 months in cadets, and across sports about 91% returned to sport after an AC joint injury, 88% at their previous level. Stingers cost 2.9 days on average, most none.
Dislocation: the NHS says "It usually takes 6 to 12 weeks to recover from a dislocated shoulder. It may take up to 16 weeks to fully return to playing some sports"; in the Premiership it cost 81 days on average. After stabilisation surgery, "Ninety-two percent of patients were able to return to rugby, 88% at their preinjury level of play" in 130 Argentinian players, and pooled return times were about 6 months; these figures come from cohorts and case series, not trials. Later in life, 14% of 146 retired professionals had clinical shoulder arthritis, and each shoulder operation doubled the odds. No one can promise a date.
Sources 26, 11, 27, 23, 2, 28, 1, 20, 29
When it isn't rugby: the causes the warning signs cover
Some shoulder pain has causes rugby didn't create, or needs more than a plan, and the warning signs follow the pages behind them. A shoulder that looks out of place, or a bump at the top with fast swelling after a fall, follows the NHS shoulder pain, dislocated shoulder and broken collarbone pages. Shoulder or arm pain with chest pain can be a heart attack, pain that comes and goes with effort can be angina, fainting or chest pain on the pitch needs a 999 call, and an arm that suddenly can't be lifted can be a stroke, as the NHS heart attack, angina, chest pain, fainting and stroke pages say. A hot, swollen shoulder can be a joint infection, as the NHS septic arthritis page says, and UK care pathways for shoulder pain and instability, with a primary care review, say a rotator cuff tear caused by an injury needs urgent referral.
After a collision, the UK grassroots concussion guidelines, World Rugby and the Gaelic Athletic Association (GAA) agree that only trained healthcare professionals should move a player with a suspected neck injury; symptoms in both arms or the legs, weakness that lasts and repeat stingers follow the stingers studies and reviews behind our stingers guide. Pressure on the spinal cord and a neck injury follow the NHS cervical spondylosis page, NHS inform's neck pages and NICE's spinal injury guideline (NICE is the National Institute for Health and Care Excellence), and a nerve from the neck the NHS neck pain page. A cuff tear not clearly better by 12 weeks follows a cohort of people with cuff tears, and an AC joint that is slow to settle follows two NHS trust leaflets.
Sources 26, 23, 30, 63, 64, 65, 66, 67, 31, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 32, 33, 86, 87, 88, 89
