Aims. The aim of this study was to examine the recent trend in delivery of arthroscopic subacromial decompression (ASD) in Scotland and to determine if this varies by geographical location. Methods. Scottish Morbidity Records were reviewed retrospectively between March 2014 and April 2018 to identify records for every admission to each NHS hospital. The Office of Population Censuses and Surveys (OPCS-4) surgical codes were used to identify patients undergoing primary ASD. Patients who underwent acromioclavicular joint excision (ACJE) and rotator cuff repair (RCR) were identified and grouped separately. Procedure rates were age and sex standardized against the European standard population. Results. During the study period the number of ASDs fell by 649 cases (29%) from 2,217 in the first year to 1,568 in the final year. The standardized annual procedure rate fell from 41.6 (95% confidence interval (CI) 39.9 to 43.4) to 28.9 (95% CI 27.4 to 30.3) per 100,000. The greatest reduction occurred between 2017 and 2018. The number of ACJEs rose from 41 to 188 (a 3.59-fold increase). The number of RCRs fell from 655 to 560 (-15%). In the year 2017 to 2018 there were four (28.6%) Scottish NHS board areas where the ASD rate was greater than 3 standard deviations (SDs) from the national average, and two (14.3%) NHS boards where the rate was less than 3 SDs from the national average. Conclusion. There has been a clear decline in the rate of ASD in Scotland since 2014. Over the same period there has been an increase in the rate of ACJE. The greatest decline occurred between 2017 and 2018, corresponding to the publication of epidemiological studies demonstrating a rise in ASD, and awareness of studies which questioned the benefit of ASD. This paper demonstrates the potential impact of information from epidemiological studies, referral guidelines, and well-designed large multicentre randomized controlled trials on clinical practice. Cite this article: Bone Joint J 2020;102-B(3):360–364

Background. Several orthopaedic studies have found significant correlation between pre-operative psychological status and post-operative outcomes. The majority of research has focused on patients requiring lower limb and spine surgery. Few studies have investigated the effect of psychological status on the outcome of upper limb operations. We prospectively investigated the association between pre-operative psychological status and early postoperative shoulder pain and function in patients requiring arthroscopic subacromial decompression (ASAD) for impingement syndrome. Methods. A consecutive series of patients in 2009/10 completed questionnaires 2 weeks pre-operatively and 3 and 6 weeks post-operatively that assessed psychological state, shoulder function and pain. The hospital anxiety and depression scale, the Oxford shoulder score and a pain visual analogue scale assessed psychological status, shoulder function and shoulder pain, respectively. Data was analysed using non-parametric statistical methods. Results. Thirty-one patients participated (21 women; 10 men; mean age 54.6 years; age range 21–89 years). Preoperative anxiety was significantly associated with pre-operative shoulder pain (P < 0.05). Pre-operative psychological status did not correlate with post-operative shoulder pain or function. Greater pre-operative anxiety and depression were significantly associated with post-operative psychological distress (P < 0.05). Overall shoulder pain, function and psychological state improved significantly during the study (P < 0.05) regardless of pre-operative psychological status. Conclusion. Despite pre-operative associations between anxiety and shoulder pain, there were no associations between pre-operative psychological status and post-operative outcomes. Our results from a total of 31 patients suggest there is no justification for routinely assessing psychological status in patients with ‘uncomplicated’ impingement syndromes that require ASAD. The majority of patients benefit from ASAD both physically and psychologically regardless of psychological state. Therefore abnormal pre-operative psychological status should not be a justifiable reason for delaying or denying this effective operation

Aims

The aims of this study were to compare the use of resources, costs, and quality of life outcomes associated with subacromial decompression, arthroscopy only (placebo surgery), and no treatment for subacromial pain in the United Kingdom National Health Service (NHS), and to estimate their cost-effectiveness.

Subacromial decompression was performed arthroscopically on 65 patients who were evaluated two to five years after the procedure. None had full thickness rotator cuff tears. Patients with partial thickness cuff tears were included in this study in order to allow comparison of arthroscopic acromioplasty with open acromioplasty for stage II impingement. On the UCLA shoulder rating scale, 89% of the cases in this study achieved a satisfactory result. These results compare favourably with those reported following open acromioplasty. The arthroscopic procedure is technically demanding. When properly performed in patients with appropriate indications, hospitalisation is brief, return to activities is rapid, there is little risk of deltoid muscle complications, and the results are lasting.

Arthroscopic subacromial decompression was carried out in one hundred and four consecutive patients who had stage II subacromial impingement with failed conservative treatment. The results were assessed preoperatively and at follow up using the UCLA score. After an average of 8.4 years follow up, the final results were as following; fifty-seven shoulders (55%) in excellent, twenty-five (24%) in good, sixteen (15%) in fair and six (6%) in poor. Late full thickness tears developed in 9% of patients and can be treated with an open repair of rotator cuff. Arthroscopic subacromial decompression was very effective for stage II impingement syndrome. To assess the long term results of arthroscopic subacromial decompression in stage II subacromial impingement. Arthroscopic subacromial decompression was very effective for stage II impingement. Late full thickness tears developed in 9% of patients and can be treated with an open repair of rotator cuff. This technique is a viable treatment for the condition. This is a prospective cohort study carried out in a University setting. Arthroscopic subacromial decompression was carried out in one hundred and twenty consecutive patients who had stage II subacromial impingement with failed conservative treatment. Sixteen were lost to follow up. The results were assessed preoperatively and at follow up using the UCLA score. After an average of 8.4 years follow up, the final results were fifty-seven shoulders (55%) excellent, twenty- five (24%) good, sixteen (15%) fair and six (6%) poor. All parameters – pain, function, muscle strength and motion – were improved significantly (p< 0.001). In the six poor results, two had late rotator cuff tears, three had recurrence of impingement with degenerative change and one had reflex sympathetic dystrophy. Late full thickness rotator cuff tears developed in ten shoulders after decompression. Re-operations were performed in four shoulders – three late open repairs of the rotator cuff tear resulted in good results with one poor rating. Arthroscopic subacromial decompression was very effective for stage II impingement syndrome. Late full thickness tears developed in 9% of patients and can be treated with an open repair of rotator cuff

Purpose: To review the results of simple arthroscopic subacromial decompression in patiens with impingement syndrome and rotator cuff tears without repairing the tears. Type of Study: prospective study. Material and Methods: From 1998 to 2003, 160 patients (168 shoulders) had arthroscopic subacromial decompression for impingement syndrome with a torn rotator cuff without repairing the tear of the cuff (120 males and 40 females). The average patient age was 64 years and the average follow up was 24 months. With increasing use of arthroscopy in the treatment of shoulder disorders, tears of the rotator cuff have been well described. Management of rotator cuff tears should include consideration of tear size, patient age and activity level, and tear etiology. Operative treatment of impingement syndrome in elderly less active lower demand patients with small and moderate tears involves decompression with and without repairing the cuff. We evaluated the clinical outcome of arthroscopic subacromial decompression and debridement in 160 patients ( 168 shoulders ) with impingement syndrome with small and moderate tears of the rotator cuff without repairing the cuff. Rotator cuff tears are graded arthroscopically as small (< 1 cm), moderate (> 1 cm < 3 cm ), large (> 3 cm < 5 cm ), and massive rotator cuff tears (> 5 cm ). Results: At follow up 96 patients (60%) were rated excellent or good , 56 patients (35%) were rated fair and 8 patients (5%) were rated poor. The average “Constant” score was 62 preoperative compared with 82 postoperative in the improved group (152 patients) . The 8 patients who showed no improvement had average postoperative “Constant” score of 64. Conclusions: Arthroscopic subacromial decompression without suture of the cuff in elderly less active lower demand patients with impingement syndrome with small and moderate tears of the cuff is a legitimate method of treatment for their shoulder pain and limitation of function. The main advantages were: immediate physiotherapy and return of function since there is no need for immobilization

Introduction. The purpose of this study was to assess the rate of revision subacromial decompression and identify different pathologies. Materials/Methods. We analysed the patients who underwent Revision Arthroscopic Subacromial decompression from our prospective database of shoulder patients. Between April 2003 and Dec 2010, 797 patients underwent arthroscopic subacromial decompression. Patients who underwent any other procedure i.e. biceps tenotomy, capsular release, cuff repair were excluded from the study. Of these, 37 underwent a revision subacromial decompression (Revision rate 4.6%). The indication for revision procedure was persistent pain or restricted movements not responding to physiotherapy and injections. Results. We found that 1) Patients having cuff pathology i.e. partial tear or degenerate cuff were more likely to need a revision procedure (11/37 and 92/797, p = 0.001). 2) The rate of ACJ excision done for residual pain after primary subacromial decompression was similar to the rate of ACJ excision at the time of the primary procedure (7/37 vs. 100/797, p= 0.5). 3) Presence of Calcific deposits did not have any influence on the risk of having a revision procedure (2/37 and 12/797, p= 0.1). 4) Patients found to have synovitis in the primary procedure were more likely to need revision procedure (10/37 and 81/797, p = 0.001). 5) Presence of biceps tendonitis did not significantly affect the risk of having a revision procedure after arthroscopic subacromial decompression (3 /37 and 21 /797, p = 0.5). Conclusion. Our revision rate is similar to those published in literature. In our failed cases there was a trend for patients to have an associated partial rotator cuff tear and synovitis

Arthroscopic subacromial decompression for shoulder impingement syndrome is one of the commonest procedures performed by the shoulder surgeon. Although much has been written on this procedure since Ellman published in 1985, very little work has been carried out on the rate of recovery after surgery, despite this being one of the main concerns of the patient. This prospective study describes the early functional results after this procedure and the rate of recovery seen. Sixty-eight patients underwent arthroscopic subacromial decompression for shoulder impingement syndrome between January and November 2000. All patients had suffered pain for at least six months prior to surgery, and all were diagnosed on the basis of clinical findings, radiographic evidence, and a positive response to Neer’s impingement test, i.e. abolition of pain after an injection of local anaesthetic into the subacromial space. All patients were evaluated preoperatively, at three weeks and three months post operatively using the Constant score to obtain an objective assessment of shoulder function. Surgery was carried out via an arthroscopic technique using the Dyonics power shaver with the 4.5 mm Helicut blade (Smith & Nephew). Immediate post operative physiotherapy was allowed, together with the encouragement of activities of daily living. Sixty-eight patients with a mean age of 45 years (range: 30–77 years) underwent surgery over a 10 month period. Male: female ratio was 60:40, and the lateral clavicle was affected in 33 cases, resulting in the need for an acromioclavicular joint resection to be performed arthroscopically at the same sitting. Mean preoperative Constant score was 46.5 (34–67), at three weeks 65.8 (40–86), and at three months 82.4 (50–99). Sixty-five out of 68 patients returned to full activities, including heavy manual work where necessary, by three month review. There was no correlation between the impingement grade, presence of a cuff tear, or acromioclavicular joint involvement, and a significantly poorer outcome. In particular, no patient was made worse by surgery, and at the latest review of the cohort the improvement seen has not deteriorated. Arthroscopic subacromial decompression is a reliable method of improving the functional ability of patients with subacromial impingement syndrome, with a 20 point increase in the Constant score at three weeks post surgery, rising to a 40 point increase at three months. Patients can therefore be counseled that they will make a significant functional improvement in a short time after surgery

68 patients underwent arthroscopic subacromial decompression for shoulder impingement syndrome. Patients were evaluated preoperatively, at 3 weeks and 3 months post operatively using the Constant score. Mean preoperative Constant score was 46. 5 (34–67), at 3 weeks 65. 8 (40–86), and at 3 months 82. 4 (50–99). There was no correlation between the impingement grade, presence of a cuff tear or acromioclavicular joint involvement, and a significant poorer outcome. Arthroscopic subacromial decompression is a reliable method of improving the functional ability of patients with subacromial impingement syndrome, with a 20 point increase in the Constant score at 3 weeks post surgery, rising to a 40 point increase at 3 months. Patients can therefore be counselled that they will make a significant functional improvement in a short time after surgery

The purpose of the study was to determine the prevalence of rotator cuff tears at long-term follow-up after arthroscopic subacromial decompression. Between 1991 and 1994, arthroscopic subacromial decompression was done on 42 shoulders for impingement syndrome. None exhibited signs of a rotator cuff tear. The patients were re-evaluated at a mean postoperative follow-up time of 10 years. At follow-up, the mean age of the patients was 54 years (33 to 69). The evaluation consisted of a clinical examination (including the Constant shoulder score) and an ultrasonographic examination. Only seven patients were found to have developed rotator cuff tears and only one needed a repair procedure. Their mean Constant score was 95. The mean Constant score of 34 patients was 97. One patient refused follow-up owing to a subjective poor result. There were no complications. We conclude that this is an effective intervention for impingement syndrome, protecting the rotator cuff

We compared two treatments for tears of the rotator cuff of 1 to 4 cm in size. One group of 22 patients had an arthroscopic subacromial decompression and rotator-cuff debridement; the other comparable group of 23 patients had open repair and acromioplasty. Review was at 2 to 5 years postoperatively. Both groups had similar pain relief and range of active forward flexion, with significant improvement from the preoperative condition. The open repair group scored better for function, strength and overall score, but patient satisfaction was similar in the two groups. We recommend the use of arthroscopic subacromial decompression and debridement for low-demand patients who require mainly pain relief and range of movement. Open repair is necessary if strength and functional recovery are the prime objectives

We report a prospective study of 49 patients who had arthroscopic subacromial decompression for chronic rotator-cuff impingement. All patients were assessed preoperatively and at 3, 6 and 12 months using the modified UCLA shoulder score. The dominant arm was affected in 35 patients, but only 13 recognised overuse as a cause of their shoulder pain. Before operation, the UCLA shoulder score was poor or fair in all patients. After three months only 28% of patients had satisfactory relief of symptoms but at one year 85% of patients examined had a good or excellent result. Patients with calcific tendonitis recovered more quickly: 93% reported a good result at six months. We conclude that arthroscopic subacromial decompression is an effective form of treatment, but that patients should be warned that recovery from surgery may be prolonged

Introduction. Whiplash injury following rear shunt Road traffic accident (RTA) has been associated with impingement syndrome of shoulder. However, the results of arthroscopic subacromial decompression (ASAD) for this group of patients have never been compared to the non accident group. In our study we aim to compare the results of ASAD in these patients to a group who did not sustain whiplash injury. Materials/Methods. Thirteen patients with impingement syndrome following rear shunt RTA were followed up (2004–09). After failed conservative management for at least 6 months ASAD was performed. This group was compared with a control group (not involved in an RTA) of 13 consecutive patients (age and sex matched). All patients were assessed with Oxford shoulder score preoperatively and twice post operatively (within 3 months and at one year). Results. In the RTA group all 13 patients showed improvement in their oxford score over one year. While the improvement was only Marginal (p= 0.08) at three months it was better at the end of a year (p=0.04). Comparatively in the cohort without the whiplash injury the improvement was more marked in the first three months (p=0.05) with significant improvement at the end of the year (p=0.03). The overall improvement in Oxford score was more in the cohort of patients who were not involved in a RTA as opposed to the RTA group (p= 0.05). Conclusion. The results of the study show that even though there was an improvement in shoulder scores after an arthroscopic subacromial decompression it was much slower and overall results were inferior in the RTA group as opposed to the controls and hence prognosis should be guarded when offering ASAD for patients with whiplash injury

Frozen shoulder is a recognised complication following simple arthroscopic shoulder procedures, but its exact incidence has not been reported. Our aim was to analyse a single-surgeon series of patients undergoing arthroscopic subacromial decompression (ASD; group 1) or ASD in combination with arthroscopic acromioclavicular joint (ACJ) excision (group 2), to establish the incidence of frozen shoulder post-operatively. Our secondary aim was to identify associated risk factors and to compare this cohort with a group of patients with primary frozen shoulder. We undertook a retrospective analysis of 200 consecutive procedures performed between August 2011 and November 2013. Group 1 included 96 procedures and group 2 104 procedures. Frozen shoulder was diagnosed post-operatively using the British Elbow and Shoulder Society criteria. A comparative group from the same institution involved 136 patients undergoing arthroscopic capsular release for primary idiopathic frozen shoulder. . The incidence of frozen shoulder was 5.21% in group 1 and 5.71% in group 2. Age between 46 and 60 years (p = 0.002) and a previous idiopathic contralateral frozen shoulder (p < 0.001) were statistically significant risk factors for the development of secondary frozen shoulder. Comparison of baseline characteristics against the comparator groups showed no statistically significant differences for age, gender, diabetes and previous contralateral frozen shoulder. . These results suggest that the risk of frozen shoulder following simple arthroscopic procedures is just over 5%, with no increased risk if the ACJ is also excised. Patients aged between 46 and 60 years and a previous history of frozen shoulder increase the relative risk of secondary frozen shoulder by 7.8 (95% confidence interval (CI) 2.1 to 28.3)and 18.5 (95% CI 7.4 to 46.3) respectively. Cite this article: Bone Joint J 2015; 97-B:963–6

Introduction. The conservative management of Sub-Acromial Impingement Syndrome (SAIS) of the shoulder includes both physiotherapy treatment and subacromial injection with local anaesthetic and steroids. The outcome from injection treatment has rarely been evaluated scientifically. Methods. Patients attending a designated shoulder clinic and diagnosed by an experienced shoulder surgeon as having a SAIS between January 2009 and December 2011 were considered for inclusion in the study. 67 of 86 patients screened completed the study (3 did not meet inclusion criteria; 9 declined to participate; 3 lost to follow-up; 4 developed frozen shoulder syndrome). Each patient had a pre-injection Oxford Shoulder Score (OSS) and was given one subacromial injection of 10ml 0.25% levobupivacaine(Chirocaine) + 40 mg triamcinolone(Kenalog) through the posterior route. Radiograph imaging was also assessed. Follow-up was carried out at 6 to 12 weeks post injection when OSS was repeated. A 6 month follow-up assessment to assess if the patient's improvement in functionality and absence of symptoms indicated that a subacromial decompression operation was not necessary. The percentage of patients showing improvement in OSS was calculated and the difference in OSS pre- and post-injection assessed using a Wilcoxon Signed Rank test. Results. The median OSS pre-injection was 29 (range 2–43) and post-injection was 40 (range 2–48) (p=< 0.001; z=−6.0; r=−0.5). 45/69 (71%) of patients benefited significantly from subacromial injection at 6 to 12 weeks post-injection. However only 28/53 (53%) benefited significantly from injection by 6 months post-injection. These results support the continued use of sub-acromial corticosteroid injections in the treatment of SAIS. 31% of these patients were subsequently treated with an arthroscopic subacromial decompression operation. Previous injection history had no impact on the results. Conclusions. We recommend that all patients with SAIS should be offered at least one subacromial injection before being considered for an arthroscopic subacromial decompression operation

There is concern that intra-articular electrosurgical ablation may cause thermal soft tissue damage, particularly chondrolysis, if excessive temperatures are reached. The aim of this study was to determine whether the intra-articular temperature during arthroscopic subacromial decompression using a monopolar electrosurgical ablator remains below a safe level. Data was collected prospectively from consecutive shoulder arthroscopic subacromial decompressions performed at our institution. Shoulder arthroscopy was performed using three standard portals. Evaluation of the glenohumeral joint and subacromial space was performed in a standard manner. Soft tissue resection of the subacromial bursa was performed using a monopolar electrosurgical ablator probe with continuous integral suction. Additional procedures such as acromioclavicular joint excision and rotator cuff debridement or repair were performed as appropriate. Bone resection, if required was performed using an arthroscopic burr. The temperature of the fluid within the shoulder and subacromial space was continuously monitored using a sterile digital temperature probe. The surgeon performing the procedure was blinded the collection of data. Data from thirty subacromial decompressions has been collected. 8 patients had full thickness cuff tears of which 6 were debrided, and 2 repaired arthroscopically. 13 patients had acromioclavicular joint excision. Mean operating time was 46 minutes (30–107). The infusion pressure ranged from 40 to 65 mmHg. The median volume of infused fluid was 3900 ml (1500 to 9000). The starting temperature ranged from 18.3 to 21.9. The mean maximum temperature reached was 27.6 (range 22.7 to 41.8 °C). The results suggest that the intra-articular temperature is maintained within safe levels when a monopolar electrosurgical ablator with integral suction is used to perform soft tissue subacromial decompression

The purpose of this study is the evaluate the net promotor score of arthroscopic subacromial decompression and rotator cuff repair. The Friends and Family Test, a variant of the Net Promoter Score, was adapted for the National Health Service to evaluate overall patient satisfaction and how likely patients are to recommend an intervention. It ranges from −100 to 100. Positive scores indicate good performance. This study quantifies the scores in 71 patients at 1 year following arthroscopic sub acromial decompression and rotator cuff repair. All of the procedures were performed by 1 consultant shoulder specialist. The patient filled out a shoulder questionnaire pre-operatively, at 6 months and 1 year. The score was 72 for subacromial decompression (n = 32) and 85 for rotator cuff repair +/− decompression (n = 39). Oxford shoulder score was also taken and had a rise of 4.3 and 6.9 respectively. Our study indicates that these procedures are highly valued and are recommended by patients according to the Friends and Family Test. The results of the Friends and Family Test correlated well with postoperative functional improvement and satisfaction. We conclude from this study that a compound score based on the Friends and Family Test is a useful addition to traditional measures of patient satisfaction

A consecutive series of 372 patients who underwent surgery for disorders of the rotator cuff involving arthroscopic subacromial decompression and open or arthroscopic repairs of the cuff were prospectively investigated as to the comparability of subjective and objective assessment scores of shoulder function. Assessments were made before operation and at 3, 6, 12, 18 and 24 months after surgery using the Disabilities of the Arm, Shoulder, and Hand score, the Oxford shoulder score and the Constant-Murley score, which was used as a reference. All scores were standardised to a scale of 0 to 100 for comparison. Statistical analysis compared the post-operative course and the mean score for the subjective Disabilities to the Arm, Shoulder and Hand score and Oxford shoulder score, with the objective Constant score at each interval. A strong correlation was evident between both subjective scores and the Constant score. We concluded that both the subjective scores would be useful substitutes for the Constant score, obviating the need for a trained investigator and the specialist equipment required to perform the Constant score

Background: Subacromial decompression surgery is associated with significant postoperative pain. We compared the effect of intrascalene block (ISB) and sub-acromial bursa block (SBB) with simple opiate based analgesia. Methods: In a prospective, randomised controlled trial, fifty-three (n = 53) patients scheduled for arthroscopic subacromial decompression were randomised into three groups receiving Intrascalene block (n =19), Subacromial Bursa block (n =19) or neither of the two blocks (n =15 controls). Patients with cuff pathology were excluded. ISB was performed preoperatively with 20 mls of 1% Prilocaine and 10 mls of 0.5 % Bupivacaine. SBB was given with 20 mls of 0.5% Bupivacaine postoperatively. All patients received standardised general anaesthetic and postoperative analgesia. Pain, sickness and sedation scores were noted at 1, 2, 4, 8, 12 and 24 hours postoperatively. The postoperative consumption of morphine and the time when the first bolus of morphine was required were also noted. Results: The visual analogue pain scores in the ISB and SBB group were lower than the control group in the first twelve hours postoperatively achieving statistical significance but there were no significant differences between the SBB and ISB groups. The controls consumed more morphine postoperatively (mean 32.3 mls) than SBB (21.21 mls) and ISB groups (14.00 mls) (p < 0.001). The time for first bolus was earlier in the controls (mean 30.2 mins) as compared to both SBB (72.7 mins) and ISB groups (105.8 mins) (p< 0.001). The oral analgesic intake was less in the SBB and ISB groups than the controls (p = 0.004), but there was no difference between the two treatment groups. Conclusion: Whilst intrascalene block remains the gold standard where expertise is available for its administration, subacromial bursa block is a safe alternative in patients with intact rotator cuff undergoing arthroscopic subacromial decompression

This investigation was performed to determine whether MRI would provide any additional diagnostic information to the clinical evaluation and diagnostic arthroscopy of the shoulder. The study was performed in patients with shoulder impingement syndrome booked for an arthroscopic subacromial decompression. Although there was significant discordance between the MRI and arthroscopic findings, the MRI did not change the diagnosis or treatment plan in a clinically important way. To determine whether the radiologist’s MRI report provided to an arthroscopist upon completion of a standard diagnostic shoulder arthroscopy would result in changes to the initial arthroscopic findings. Despite high percentage of discordance between MRI and arthroscopy, the MRI information modified the initial arthroscopic diagnosis in a much smaller percentage of cases. In only one patient, did the change in diagnostic information have an impact on the planned treatment. MRI adds minimal clinically important information to diagnostic shoulder athroscopy in patients with impingement syndrome. The percentage discordance between MRI and arthroscopy for each structure of interest was calculated along with the percentage change in diagnosis based upon the arthroscopic re-evaluation and the consequence of the change. Supraspinatus 55.2% discordance(n=32/58), 18.8% change in diagnosis(n=6/32), in 1 patient a change in the planned operation occurred from subacromial decompression to mini-open rotator cuff repair. Infra-spinatus 44.8% discordance(n=26/58), 3.8% change in diagnosis(n=1/26), and no consequence to planned treatment. Subscapularis 37.9% discordance(n=22/58), no change in diagnosis. Biceps tendon 62.3% discordance(n=33/53; five patients not adequately visualized on MRI), no change in diagnosis. Fifty-eight patients presenting with shoulder impingement syndrome underwent a standardized MRI prior to planned arthroscopic subacromial decompression. A standard diagnostic arthroscopy was performed. The anatomic and pathologic findings were documented intra-operatively by an independent observer. The arthroscopist was initially blinded to the MRI information. MRI results were then revealed to the surgeon. An arthroscopic re-evaluation was performed to resolve discrepancies between MRI and arthroscopy