Aims. To achieve expert clinical consensus in the delivery of hydrodilatation for the treatment of primary frozen shoulder to inform clinical practice and the design of an intervention for evaluation. Methods. We conducted a two-stage, electronic questionnaire-based, modified Delphi survey of shoulder experts in the UK NHS. Round one required positive, negative, or neutral ratings about hydrodilatation. In round two, each participant was reminded of their round one responses and the modal (or ‘group’) response from all participants. This allowed participants to modify their responses in round two. We proposed respectively mandating or encouraging elements of hydrodilatation with 100% and 90% positive consensus, and respectively disallowing or discouraging with 90% and 80% negative consensus. Other elements would be optional. Results. Between 4 August 2020 and 4 August 2021, shoulder experts from 47 hospitals in the UK completed the study. There were 106 participants (consultant upper limb orthopaedic surgeons, n = 50; consultant radiologists, n = 52; consultant physiotherapist, n = 1; extended scope physiotherapists, n = 3) who completed round one, of whom 97 (92%) completed round two. No elements of hydrodilatation were “mandated” (100% positive rating). Elements that were “encouraged” (≥ 80% positive rating) were the use of image guidance, local anaesthetic, normal saline, and steroids to deliver the injection. Injecting according to patient tolerance, physiotherapy, and home exercises were also “encouraged”. No elements were “discouraged” (≥ 80% negative rating) although using hypertonic saline was rated as being “disallowed” (≥ 90% negative rating). Conclusion. In the absence of rigorous evidence, our Delphi study allowed us to achieve expert consensus about positive, negative, and neutral ratings of hydrodilatation in the management of frozen shoulder in a hospital setting. This should inform clinical practice and the design of an intervention for evaluation. Cite this article: Bone Jt Open 2022;3(9):701–709

Aims. A pragmatic multicentre randomized controlled trial, UK FROzen Shoulder Trial (UK FROST), was conducted in the UK NHS comparing the cost-effectiveness of commonly used treatments for adults with primary frozen shoulder in secondary care. Methods. A cost utility analysis from the NHS perspective was performed. Differences between manipulation under anaesthesia (MUA), arthroscopic capsular release (ACR), and early structured physiotherapy plus steroid injection (ESP) in costs (2018 GBP price base) and quality adjusted life years (QALYs) at one year were used to estimate the cost-effectiveness of the treatments using regression methods. Results. ACR was £1,734 more costly than ESP ((95% confidence intervals (CIs) £1,529 to £1,938)) and £1,457 more costly than MUA (95% CI £1,283 to £1,632). MUA was £276 (95% CI £66 to £487) more expensive than ESP. Overall, ACR had worse QALYs compared with MUA (-0.0293; 95% CI -0.0616 to 0.0030) and MUA had better QALYs compared with ESP (0.0396; 95% CI -0.0008 to 0.0800). At a £20,000 per QALY willingness-to-pay threshold, MUA had the highest probability of being cost-effective (0.8632) then ESP (0.1366) and ACR (0.0002). The results were robust to sensitivity analyses. Conclusion. While ESP was less costly, MUA was the most cost-effective option. ACR was not cost-effective. Cite this article: Bone Jt Open 2021;2(8):685–695

Aims. This systematic review places a recently completed multicentre randomized controlled trial (RCT), UK FROST, in the context of existing randomized evidence for the management of primary frozen shoulder. UK FROST compared the effectiveness of pre-specified physiotherapy techniques with a steroid injection (PTSI), manipulation under anaesthesia (MUA) with a steroid injection, and arthroscopic capsular release (ACR). This review updates a 2012 review focusing on the effectiveness of MUA, ACR, hydrodilatation, and PTSI. Methods. MEDLINE, Embase, PEDro, Science Citation Index, Clinicaltrials.gov, CENTRAL, and the World Health Organization (WHO) International Clinical Trials Registry were searched up to December 2018. Reference lists of included studies were screened. No language restrictions applied. Eligible studies were RCTs comparing the effectiveness of MUA, ACR, PTSI, and hydrodilatation against each other, or supportive care or no treatment, for the management of primary frozen shoulder. Results. Nine RCTs were included. The primary outcome of patient-reported shoulder function at long-term follow-up (> 6 months and ≤ 12 months) was reported for five treatment comparisons across four studies. Standardized mean differences (SMD) were: ACR versus MUA: 0.21 (95% confidence interval (CI) 0.00 to 0.42), ACR versus supportive care: -0.13 (95% CI -1.10 to 0.83), and ACR versus PTSI: 0.33 (95% CI 0.07 to 0.59) and 0.25 (95% CI -0.34 to 0.85), all favouring ACR; MUA versus supportive care: 0 (95% CI -0.44 to 0.44) not favouring either; and MUA versus PTSI: 0.12 (95% CI -0.14 to 0.37) favouring MUA. None of these differences met the threshold of clinical significance agreed for the UK FROST and most confidence intervals included zero. Conclusion. The findings from a recent multicentre RCT provided the strongest evidence that, when compared with each other, neither PTSI, MUA, nor ACR are clinically superior. Evidence from smaller RCTs did not change this conclusion. The effectiveness of hydrodilatation based on four RCTs was inconclusive and there remains an evidence gap. Cite this article: Bone Jt Open 2021;2(9):773–784

The purpose of the study was to test the hypothesis that cellular mechanisms of fibroblasts derived from primary frozen shoulder (PFS) exhibit similar activity in terms of contraction, response to cytokine transforming growth factor-beta1 (TGF beta1) and mechanical stimulation similar to that generated by fibroblasts derived from Dupuytren’s disease. Frozen shoulder has been postulated to be Dupuytren’s disease of the shoulder with an association inferred since 1936. Primary explant cultures of fibroblasts from seven patients with PFS and five control patients were obtained using standard tissue culture techniques. Fibroblasts were seeded in 3-D collagen constructs and contraction force generated over 24 hours measured using a culture force monitor (CFM) in real time. Increasing concentrations of TGF-beta1 were added to cell seeded gels and force generated measured using the CFM over 24 hours. These mechanical output data were statistically compared to data available from Dupuytren’s disease. Compared to Dupuytren’s fibroblasts, PFS fibroblasts showed a statistically reduced ability to contract a 3-D collagen gel over 24 hours (p< 0.01). In Dupuytren’s disease, fibroblasts derived from nodules and cords generate peak forces of 140 dynes and 110 dynes respectively, while PFS fibroblasts generated peak force of 8 dynes The response to TGF-beta1 stimulation, which has been shown to enhance peak force contraction in Dupuytren’s fibroblasts had no effect on PFS fibroblasts and this was statistically significant (p< 0.01). These data suggest intrinsic differences in cellular activity and mechanisms between Dupuytren’s and Primary Frozen Shoulder even though clinically they both manifest with a contracted extracellular matrix affecting function and requiring surgical intervention. This may explain increased post surgical recurrence in Dupuytren’s as compared to Primary Frozen Shoulder release

The purpose of the study was to test the hypothesis that cellular mechanisms of fibroblasts derived from primary frozen shoulder(PFS) exhibit similar activity in terms of contraction, response to cytokine (transforming growth factor-beta1) and mechanical stimulation similar to that generated by fibroblasts derived from dupuytren’s disease. PFS is a debilitating disease of unknown aetiology, characterised by fibrosis with contracture of the cora-cohumeral ligament, tissues of the rotator interval and glenohumeral ligaments, leading to restrictive shoulder movements. Frozen shoulder has been postulated to be Dupuytren’s disease of the shoulder with an association inferred since 1936. Materials and Methods: Primary explant cultures of fibroblasts from seven patients with PFS and five control patients were obtained using standard tissue culture techniques. Fibroblasts were seeded in 3-D collagen constructs and contraction force generated over 24hours measured using a culture force monitor(CFM) in real time. Increasing concentrations of TGF-beta1 were added to cell seeded gels and force generated measured using the CFM over 24hours. These mechanical output data were statistically compared to data available from Dupuytren’s disease. Results and Discussion: Compared to Dupuytren’s fibroblasts, PFS fibroblasts showed a statistically reduced ability to contract a 3-D collagen gel over 24hours (p< 0.01). In Dupuytren’s disease, fibroblasts derived from nodules and cords generate peak forces of 140dynes and 110dynes respectively, while PFS fibro-blasts generated peak force of 8dynes The response to TGF-beta1 stimulation, which has been shown to enhance peak force contraction in Dupuytren’s fibro-blasts had no effect on PFS fibroblasts and this was statistically significant (p< 0.01). Conclusion: These data suggest intrinsic differences in cellular activity and mechanisms between Dupuytren’s and Primary Frozen Shoulder even though clinically they both manifest with a contracted extracellular matrix affecting function and requiring surgical intervention. This may explain increasing post surgically recurrence in Dupuytren’s as compared to Primary Frozen Shoulder release

There are many types of treatment used to manage the frozen shoulder, but there is no consensus on how best to manage patients with this painful and debilitating condition. We conducted a review of the evidence of the effectiveness of interventions used to manage primary frozen shoulder using the Cochrane Database of Systematic Reviews, the Database of Abstracts of Reviews of Effects, the Physiotherapy Evidence Database, MEDLINE and EMBASE without language or date restrictions up to April 2009. Two authors independently applied selection criteria and assessed the quality of systematic reviews using the Assessment of Multiple Systematic Reviews (AMSTAR) tool. Data were synthesised narratively, with emphasis placed on assessing the quality of evidence. In total, 758 titles and abstracts were identified and screened, which resulted in the inclusion of 11 systematic reviews. Although these met most of the AMSTAR quality criteria, there was insufficient evidence to draw firm conclusions about the effectiveness of treatments commonly used to manage a frozen shoulder. This was mostly due to poor methodological quality and small sample size in primary studies included in the reviews. We found no reviews evaluating surgical interventions. More rigorous randomised trials are needed to evaluate the treatments used for frozen shoulder

Aims. Ultrasound (US)-guided injections are widely used in patients with conditions of the shoulder in order to improve their accuracy. However, the clinical efficacy of US-guided injections compared with blind injections remains controversial. The aim of this study was to compare the accuracy and efficacy of US-guided compared with blind corticosteroid injections into the glenohumeral joint in patients with primary frozen shoulder (FS). Methods. Intra-articular corticosteroid injections were administered to 90 patients primary FS, who were randomly assigned to either an US-guided (n = 45) or a blind technique (n = 45), by a shoulder specialist. Immediately after injection, fluoroscopic images were obtained to assess the accuracy of the injection. The outcome was assessed using a visual analogue scale (VAS) for pain, the American Shoulder and Elbow Surgeons (ASES) score, the subjective shoulder value (SSV) and range of movement (ROM) for all patients at the time of presentation and at three, six, and 12 weeks after injection. Results. The accuracy of injection in the US and blind groups was 100% (45/45) and 71.1% (32/45), respectively; this difference was significant (p < 0.001). Both groups had significant improvements in VAS pain score, ASES score, SSV, forward flexion, abduction, external rotation, and internal rotation throughout follow-up until 12 weeks after injection (all p < 0.001). There were no significant differences between the VAS pain scores, the ASES score, the SSV and all ROMs between the two groups at the time points assessed (all p > 0.05). No injection-related adverse effects were noted in either group. Conclusion. We found no significant differences in pain and functional outcomes between the two groups, although an US-guided injection was associated with greater accuracy. Considering that it is both costly and time-consuming, an US-guided intra-articular injection of corticosteroid seems not always to be necessary in the treatment of FS as it gives similar outcomes as a blind injection. Cite this article: Bone Joint J 2021;103-B(2):353–359

In patients with DM (Diabetes Mellitus types I & II), primary frozen shoulders tend to be refractory to all forms of treatment. We collected tissue from the joint capsule of shoulder joints from a variety of patients undergoing surgery as follows:. Diabetic Group (DFS): patients with DM who have primary frozen shoulders. Other patients suffering from primary frozen shoulders (FS). Control group (NS). Patients undergoing shoulder surgery that does not involve stiffness of the gleno-humeral joint. Tissue was collected from near to the rotator interval under arthroscopic control. Fibroblast lines were established by serial passage. Thereafter they were exposed to graded concentrations of insulin in vitro for 24 hours and the supernatant retained for assay. Fibroblast lines were analysed from 3 subjects in each group (n=9). Luminex multiplex analysis was performed for MMPs (Matrix Metalloproteinases). TIMP-1 (Tissue Inhibitor of MetalloProteinases) expression. Informed consent was obtained from all subjects. Results: Production of MMP 1,2,3 and 8 by fibroblast lines were distinct between patient groups. MMP-1 production in DFS (mean 716pg/mL) was significantly reduced compared to FS derived patient cells (mean 972pg/mL) (p=0.0138, Mann-Whitney Test). Moreover, striking differences were observed when fibroblasts from DFS patients were compared with those from NS controls (mean 5898pg/mL) (p< 0.000). Calculating MMP-1/TIMP-1 ratios revealed significantly lower ratios in DFS (2597), or FS (2860) compared with NS (24,326) (p < 0.001). There was no significant difference between ratios of MMP1/TIMP1 in DFS and FS (p=0.977). MMPs 7,9,12 and 13 were not detected in any of the samples. This is the first time these enzymes have been measured and quantified in cells derived from shoulder tissues. Primary Frozen Shoulders produce less MMPs and have a smaller MMP/TIMP ratio than controls. Similarly the diabetic patient derived cells produce less MMP-1, at an even lower level. These deficiencies in MMP1 production may reflect an altered capacity for local tissue re-modelling. MMP modulation may allow therapeutic intervention in the diabetic and frozen shoulder group of patients

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

Background. Frozen Shoulder is a common condition which causes significant morbidity in people of working age. The 2 most popular forms of surgical treatment for this condition are Manipulation under Anaesthesia (MUA) or MUA plus Arthroscopic Capsular Release (ACR). Both treatment modalities are known to give good results, but no-one has compared the two to see which is better. Aim. To compare the outcome in patients with primary frozen shoulder, who are treated by either MUA or MUA plus ACR. Methods. 56 patients with primary frozen shoulder were treated by either MUA or MUA plus ACR. Each patient had their American Shoulder and Elbow Score (ASES), and their Oxford Shoulder Score (OSS) measured pre- and post-operatively. Results. The patients who had MUA plus ACR had a mean ASES of 19.6 pre-operatively, 78.3 at 6 months, and a mean of 80.1 at 12 months. The mean OSS was 32.5 pre-operatively, 53.6 at 6 months and 53.8 at 12 months. The patients who had a MUA had a mean ASES of 28.7 pre-operatively, 57.9 at 6 months and 58 at 12 months. The mean OSS was 33 pre-operatively, 42.5 at 6 months and 48 at 12 months. Conclusions. Both treatments give good results; MUA plus ACR give significantly superior results at 6 to 12 months post-operatively. However, there is no significant difference beyond 12 months

We treated 22 patients with a diagnosis of primary frozen shoulder resistant to conservative treatment by manipulation under anaesthetic and arthroscopic release of the rotator interval, at a mean time from onset of 15 months (3 to 36). Biopsies were taken from this site and histological and immunocytochemical analysis was performed to identify the types of cell present. The tissue was characterised by the presence of fibroblasts, proliferating fibroblasts and chronic inflammatory cells. The infiltrate of chronic inflammatory cells was predominantly made up of mast cells, with T cells, B cells and macrophages also present. The pathology of frozen shoulder includes a chronic inflammatory response with fibroblastic proliferation which may be immunomodulated

Aim: The purpose of this study was to evaluate the results of arthroscopic capsular release in patients with primary adhesive capsulitis of the glenohumeral joint. Methods: Twenty-eight shoulders in 27 patients with adhesive capsulitis of the glenohumeral joint were treated with manipulation and arthroscopic capsular release. Their average age was 54.5 years (range, 39–67). During surgery, synovectomy and a combined anterior, posterior and inferior arthroscopic release using electrocautery or laser was performed. Range of motion and evaluation with the Constant score before and after surgery was performed in all patients. Results: The mean follow-up was 32 months (24–63). The mean Constant score significantly improved from 44.6 (28–52) preoperatively to 86.3 (73–52) postoperatively (p< 0.001, paired t-test). Range of motion for all planes significantly improved. Abduction improved from 72° preoperatively to 165° postoperatively; Internal rotation improved from 13° to 60° and external rotation from 10° to 75°. Subjectively all patients had remarkably less pain, and there were no complications. Conclusions: Our study suggest that arthroscopic treatment of primary adhesive capsulitis with capsular release is an effective and reliable method for restoring a painless motion of the glenohumeral joint

Background – Frozen Shoulder is a common condition which causes significant morbidity in people of working age. The 2 most popular forms of surgical treatment for this condition are Manipulation under Anaesthesia (MUA) or MUA plus Arthroscopic Capsular Release (ACR). Both treatment modalities are known to give good results, but no-one has compared the 2 to see which is better. Aim – To compare the outcome in patients with primary frozen shoulder, who are treated by either MUA or MUA plus ACR. Method – 61 patients with primary frozen shoulder were treated by either MUA or MUA plus ACR. Each patient had their American Shoulder and Elbow Score (ASES), and their Oxford Shoulder Score (OSS) measured pre and post-operatively. Results – The patients who had MUA plus ACR had a mean ASES of 24.8 preoperatively, 64 at 4 months, and a mean of 75.4 at 12 months. The mean OSS was 32.5 pre-operatively, 48.5 at 4 months and 53.4 at 12months. The patients who had a MUA had a mean ASES of 28.7 pre-operatively, 60.9 at 4months and 69.6 at 12months. The mean OSS was 33 preoperatively, 46.5 at 4 months and 50.9 at 12 months. Conclusions – Both treatments give good results. MUA plus ACR give superior numerical results at 6 to 12 months post-operatively, however, these figures did not reach statistical significance

The effect of timing of a manipulation under anaesthetic (MUA) and injection of corticosteroid and local anaesthetic for the treatment of frozen shoulder has attracted little attention to date. All studies describe a period of conservative treatment before proceeding to an MUA. Delay has been associated with a poorer outcome. We present a retrospective review of a prospectively collected, single-surgeon, consecutive series of 246 patients with a primary frozen shoulder treated by MUA within four weeks of presentation. The mean duration of presenting symptoms was 28 weeks (6 to 156), and time to initial post-operative assessment was 26 days (5 to 126). The Oxford shoulder score (OSS) improved by a mean of 16 points (Wilcoxon signed-ranks test, p < 0.001) with a mean OSS at this time of 43 (7 to 48). Linear regression analysis showed no correlation between the duration of presenting symptoms and OSS at initial follow-up (R2 < 0.001) or peri-operative change in OSS (R2 < 0.001) or OSS at long-term follow-up (R2 < 0.03). Further analysis at a mean of 42 months (8 to 127) revealed a sustained improvement with a mean OSS of 44 (16 to 48). A good outcome follows an MUA and injection of corticosteroid and local anaesthetic in patients with primary frozen shoulder, independent of the duration of the presenting symptoms, and this improvement is maintained in the long term

We prospectively studied 50 patients with the diagnosis of primary frozen shoulder. The serum lipid levels were measured in 43 of these patients and compared with those in 43 age-matched and sex-matched control subjects. The fasting serum triglyceride and cholesterol levels were significantly elevated in the frozen-shoulder group (cholesterol p < 0.01; triglyceride p < 0.02)

Manipulation under anaesthetic (MUA) for the treatment of frozen shoulder is well established and effective however timing of surgery remains controversial. Intervention before 9 months has previously been shown to be associated with improved outcome. We test this theory by measuring Oxford Shoulder Score (OSS), re-MUA and subsequent surgery rate. A retrospective review of a prospectively collected, single surgeon, consecutive patient series revealed 244 primary frozen shoulders treated by MUA within 4 weeks of presentation. The mean duration of antecedent symptoms was 28 weeks (95% CI 4-44 weeks) and time to follow up was 26 days (95% CI 11-41 days). The mean OSS improved by 16 points (2-tailed t test p< 0.001) with a mean follow up OSS of 43 (95% CI 38-48). 195 shoulders were manipulated before 38 weeks (9 months) and had the same mean change in OSS (16) as the 49 shoulders manipulated after 38 weeks. 48 shoulders, including 15 diabetic shoulders required further MUA. 8 shoulders had subsequent surgery. These events were also independent of antecedent symptom duration. Early MUA does not appear to produce improved outcomes when compared to later intervention but we note does result in an earlier return to function

Of 935 consecutive patients referred with shoulder pain, 50 fitted the criteria for primary frozen shoulder. Twelve patients who failed to improve after conservative treatment and manipulation had excision of the coracohumeral ligament and the rotator interval of the capsule. The specimens were examined histologically, using special stains for collagen. Immunocytochemistry was performed with monoclonal antibodies against leucocyte common antigen (LCA, CD45) and a macrophage/synovial antigen (PGMI, CD68) to assess the inflammatory component, and vimentin and smooth-muscle actin to evaluate fibroblasts and myofibroblasts. Our histological and immunocytochemical findings show that the pathological process is active fibroblastic proliferation, accompanied by some transformation to a smooth muscle phenotype (myofibroblasts). The fibroblasts lay down collagen which appears as a thick nodular band or fleshy mass. These appearances are very similar to those in Dupuytren's disease of the hand, with no inflammation and no synovial involvement. The contracture acts as a check-rein against external rotation, causing loss of both active and passive movement

This is the largest reported natural history study of frozen shoulder. 500 patients were identified from a specialist shoulder clinic register with a diagnosis of frozen shoulder based on Codman’s criteria. 273 patients with primary frozen shoulder replied to a detailed postal questionnaire regarding their condition. Mean follow up from symptom onset was 52 months (range 12–240months), with 89% of shoulders followed up for a minimum of 3 years. A positive family history was identified in 20% (n=45) of 1st degree relatives. The relative risk to siblings compared with a control population was 4:1. Patients with mild to moderate symptoms recovered more quickly than those with severe or unbearable symptoms. The mean age of onset was 53 years (range27–85yrs). The female to male ratio was 1.6:1. The condition was bilateral in 20%, with no incidence of ipsilateral recurrence. 22% of patients reported a history of minor trauma to the upper limb prior to the onset of symptoms. 16% were diabetic and 4% reported a history of Dupuytren’s contracture. Right and left arms were affected equally with no relationship to hand dominance. 61% reported slow, and 39% reported sudden onset of symptoms. Generally pain and stiffness improved with time but at 3 and 4 years after onset 13% and 9% respectively still had symptoms. Frozen shoulder affects people mainly in their 6th decade. Genetic factors play an important role in the aetiology. The natural history is for improvement with time, with the less severe symptoms at onset improving most quickly. 9% of patients were still symptomatic at 4 year follow up

Aim: To compare 2 rehabilitation regimes after arthroscopic interval release: immediate mobilization versus immediate mobilization and external rotation night splint for ten days. Methods: 30 patients aged 40–67 years with primary frozen shoulder were included in the study. The surgical procedure consisted of release of the coracohumeral ligament, rotator interval and the posterior capsule with electrocautery, followed by gentle manipulation. Patients were randomised into 2 rehabilitation groups: immediate mobilization (IM) or immediate mobilization with external rotation night splint (ERS) used for 10 days post-operatively. Patients were assessed pre & post operatively and using the visual analogue score for pain, Constant and Oxford scoring systems. Results: There were 15 patients in the IM group and 15 in ERS group. In the IM group the Constant score improved from 35±10 (mean±SD) pre-operatively to 63±14 at 1 month and 75±11 at 6 months, and in the ERS group the Constant score improved from 33±9 pre-operatively to 59±14 at 1 month and 75±7 at 6 months. The Oxford score in the IM group improved from 35±9 pre-operatively to 25±8 at 1 month and 18±9 at 6 months, and in the ERS group from 38±9 pre-operatively to 27±8 at 1 month and 18±8 at 6 months (all changes P< 0.001 cf pre-operative, but NS from 1 to 6 months). Improvements in VAS were significant in both groups (P< 0.02) at 6 months but not at 1 month. There was no significant difference between the two groups in terms of Oxford or Constant scores or VAS at 1 and 6 months. Conclusion: Arthroscopic interval release is successful in restoring range of motion in patients with idiopathic frozen shoulder. Both groups showed significant improvement during the study period with most improvement in terms of range of movement occurring in the first month. There was no significant difference in outcome between the two groups studied