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The Bone & Joint Journal
Vol. 105-B, Issue 2 | Pages 158 - 165
1 Feb 2023
Sigmund IK Yeghiazaryan L Luger M Windhager R Sulzbacher I McNally MA

Aims

The aim of this study was to evaluate the optimal deep tissue specimen sample number for histopathological analysis in the diagnosis of periprosthetic joint infection (PJI).

Methods

In this retrospective diagnostic study, patients undergoing revision surgery after total hip or knee arthroplasty (n = 119) between January 2015 and July 2018 were included. Multiple specimens of the periprosthetic membrane and pseudocapsule were obtained for histopathological analysis at revision arthroplasty. Based on the Infectious Diseases Society of America (IDSA) 2013 criteria, the International Consensus Meeting (ICM) 2018 criteria, and the European Bone and Joint Infection Society (EBJIS) 2021 criteria, PJI was defined. Using a mixed effects logistic regression model, the sensitivity and specificity of the histological diagnosis were calculated. The optimal number of periprosthetic tissue specimens for histopathological analysis was determined by applying the Youden index.


Bone & Joint Research
Vol. 12, Issue 6 | Pages 362 - 371
1 Jun 2023
Xu D Ding C Cheng T Yang C Zhang X

Aims

The present study aimed to investigate whether patients with inflammatory bowel disease (IBD) undergoing joint arthroplasty have a higher incidence of adverse outcomes than those without IBD.

Methods

A comprehensive literature search was conducted to identify eligible studies reporting postoperative outcomes in IBD patients undergoing joint arthroplasty. The primary outcomes included postoperative complications, while the secondary outcomes included unplanned readmission, length of stay (LOS), joint reoperation/implant revision, and cost of care. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using a random-effects model when heterogeneity was substantial.


Bone & Joint Research
Vol. 12, Issue 8 | Pages 455 - 466
1 Aug 2023
Zhou H Chen C Hu H Jiang B Yin Y Zhang K Shen M Wu S Wang Z

Aims

Rotator cuff muscle atrophy and fatty infiltration affect the clinical outcomes of rotator cuff tear patients. However, there is no effective treatment for fatty infiltration at this time. High-intensity interval training (HIIT) helps to activate beige adipose tissue. The goal of this study was to test the role of HIIT in improving muscle quality in a rotator cuff tear model via the β3 adrenergic receptor (β3AR).

Methods

Three-month-old C57BL/6 J mice underwent a unilateral rotator cuff injury procedure. Mice were forced to run on a treadmill with the HIIT programme during the first to sixth weeks or seventh to 12th weeks after tendon tear surgery. To study the role of β3AR, SR59230A, a selective β3AR antagonist, was administered to mice ten minutes before each exercise through intraperitoneal injection. Supraspinatus muscle, interscapular brown fat, and inguinal subcutaneous white fat were harvested at the end of the 12th week after tendon tear and analyzed biomechanically, histologically, and biochemically.


The Bone & Joint Journal
Vol. 106-B, Issue 1 | Pages 28 - 37
1 Jan 2024
Gupta S Sadczuk D Riddoch FI Oliver WM Davidson E White TO Keating JF Scott CEH

Aims

This study aims to determine the rate of and risk factors for total knee arthroplasty (TKA) after operative management of tibial plateau fractures (TPFs) in older adults.

Methods

This is a retrospective cohort study of 182 displaced TPFs in 180 patients aged ≥ 60 years, over a 12-year period with a minimum follow-up of one year. The mean age was 70.7 years (SD 7.7; 60 to 89), and 139/180 patients (77.2%) were female. Radiological assessment consisted of fracture classification; pre-existing knee osteoarthritis (OA); reduction quality; loss of reduction; and post-traumatic OA. Fracture depression was measured on CT, and the volume of defect estimated as half an oblate spheroid. Operative management, complications, reoperations, and mortality were recorded.


Bone & Joint Research
Vol. 13, Issue 7 | Pages 342 - 352
9 Jul 2024
Cheng J Jhan S Chen P Hsu S Wang C Moya D Wu Y Huang C Chou W Wu K

Aims

To explore the efficacy of extracorporeal shockwave therapy (ESWT) in the treatment of osteochondral defect (OCD), and its effects on the levels of transforming growth factor (TGF)-β, bone morphogenetic protein (BMP)-2, -3, -4, -5, and -7 in terms of cartilage and bone regeneration.

Methods

The OCD lesion was created on the trochlear groove of left articular cartilage of femur per rat (40 rats in total). The experimental groups were Sham, OCD, and ESWT (0.25 mJ/mm2, 800 impulses, 4 Hz). The animals were euthanized at 2, 4, 8, and 12 weeks post-treatment, and histopathological analysis, micro-CT scanning, and immunohistochemical staining were performed for the specimens.


Bone & Joint Research
Vol. 11, Issue 11 | Pages 835 - 842
17 Nov 2022
Wiesli MG Livio F Achermann Y Gautier E Wahl P

Aims

There is a considerable challenge in treating bone infections and orthopaedic device-associated infection (ODAI), partly due to impaired penetration of systemically administrated antibiotics at the site of infection. This may be circumvented by local drug administration. Knowledge of the release kinetics from any carrier material is essential for proper application. Ceftriaxone shows a particular constant release from calcium sulphate (CaSO4) in vitro, and is particularly effective against streptococci and a large portion of Gram-negative bacteria. We present the clinical release kinetics of ceftriaxone-loaded CaSO4 applied locally to treat ODAI.

Methods

A total of 30 operations with ceftriaxone-loaded CaSO4 had been performed in 28 patients. Ceftriaxone was applied as a single local antibiotic in 21 operations and combined with vancomycin in eight operations, and in an additional operation with vancomycin and amphotericin B. Sampling of wound fluid was performed from drains or aspirations. Ceftriaxone concentrations were measured by liquid chromatography with tandem mass spectrometry (LC-MS/MS).


Bone & Joint Research
Vol. 12, Issue 5 | Pages 339 - 351
23 May 2023
Tan J Liu X Zhou M Wang F Ma L Tang H He G Kang X Bian X Tang K

Aims

Mechanical stimulation is a key factor in the development and healing of tendon-bone insertion. Treadmill training is an important rehabilitation treatment. This study aims to investigate the benefits of treadmill training initiated on postoperative day 7 for tendon-bone insertion healing.

Methods

A tendon-bone insertion injury healing model was established in 92 C57BL/6 male mice. All mice were divided into control and training groups by random digital table method. The control group mice had full free activity in the cage, and the training group mice started the treadmill training on postoperative day 7. The quality of tendon-bone insertion healing was evaluated by histology, immunohistochemistry, reverse transcription quantitative polymerase chain reaction, Western blotting, micro-CT, micro-MRI, open field tests, and CatWalk gait and biomechanical assessments.


The Bone & Joint Journal
Vol. 106-B, Issue 9 | Pages 1021 - 1030
1 Sep 2024
Oto J Herranz R Fuertes M Plana E Verger P Baixauli F Amaya JV Medina P

Aims

Bacterial infection activates neutrophils to release neutrophil extracellular traps (NETs) in bacterial biofilms of periprosthetic joint infections (PJIs). The aim of this study was to evaluate the increase in NET activation and release (NETosis) and haemostasis markers in the plasma of patients with PJI, to evaluate whether such plasma induces the activation of neutrophils, to ascertain whether increased NETosis is also mediated by reduced DNaseI activity, to explore novel therapeutic interventions for NETosis in PJI in vitro, and to evaluate the potential diagnostic use of these markers.

Methods

We prospectively recruited 107 patients in the preoperative period of prosthetic surgery, 71 with a suspicion of PJI and 36 who underwent arthroplasty for non-septic indications as controls, and obtained citrated plasma. PJI was confirmed in 50 patients. We measured NET markers, inflammation markers, DNaseI activity, haemostatic markers, and the thrombin generation test (TGT). We analyzed the ability of plasma from confirmed PJI and controls to induce NETosis and to degrade in vitro-generated NETs, and explored the therapeutic restoration of the impairment to degrade NETs of PJI plasma with recombinant human DNaseI. Finally, we assessed the contribution of these markers to the diagnosis of PJI.


The Bone & Joint Journal
Vol. 96-B, Issue 1 | Pages 75 - 81
1 Jan 2014
Kukkonen J Joukainen A Lehtinen J Mattila KT Tuominen EKJ Kauko T Äärimaa V

We have compared three different methods of treating symptomatic non-traumatic tears of the supraspinatus tendon in patients above 55 years of age. A total of 180 shoulders (173 patients) with supraspinatus tendon tears were randomly allocated into one of three groups (each of 60 shoulders); physiotherapy (group 1), acromioplasty and physiotherapy (group 2) and rotator cuff repair, acromioplasty and physiotherapy (group 3). The Constant score was assessed and followed up by an independent observer pre-operatively and at three, six and twelve months after the intervention. Of these, 167 shoulders were available for assessment at one year (follow-up rate of 92.8%). There were 55 shoulders in group 1 (24 in males and 31 in females, mean age 65 years (55 to 79)), 57 in group 2 (29 male and 28 female, mean age 65 years (55 to 79)) and 55 shoulders in group 3 (26 male and 29 female, mean age 65 years (55 to 81)). There were no between-group differences in the Constant score at final follow-up: 74.1 (. sd. 14.2), 77.2 (. sd. 13.0) and 77.9 (. sd. 12.1) in groups 1, 2 and 3, respectively (p = 0.34). The mean change in the Constant score was 17.0, 17.5, and 19.8, respectively (p = 0.34). These results suggest that at one-year follow-up, operative treatment is no better than conservative treatment with regard to non-traumatic supraspinatus tears, and that conservative treatment should be considered as the primary method of treatment for this condition. Cite this article: Bone Joint J 2014;96-B:75–81


The Journal of Bone & Joint Surgery British Volume
Vol. 92-B, Issue 7 | Pages 970 - 974
1 Jul 2010
Foruria AM Sperling JW Ankem HK Oh LS Cofield RH

This study was performed to review the safety and outcome of total shoulder replacements in patients who are ≥ 80 years of age. A total of 50 total shoulder replacements in 44 patients at a mean age of 82 years (80 to 89) were studied. Their health and shoulder status, the operation and post-operative course were analysed, including pain, movement, patient satisfaction, medical and surgical complications, radiographs, the need for revision surgery, and implant and patient survival. A total of 27 patients had an ASA classification of III or IV and medical abnormalities were common. Of the 13 shoulders with bony deficiency of the glenoid, nine required grafting. The duration of hospital stay was prolonged and blood transfusions were common. There were no peri-operative deaths. The mean follow-up was for 5.5 years (2 to 12). Pain was significantly reduced (p < 0.001) and movement improved in active elevation and both external and internal rotation (p < 0.001). Using the Neer scale for assessing outcome, 40 (80%) shoulders had an excellent or satisfactory result. There were medical or surgical complications in 17 cases. Four shoulders developed radiological evidence of loosened glenoid components, and three of these had a poor outcome. Three other shoulders required revision, two for instability. By the time of this review 39 of the patients had died from unrelated causes at a mean of 7.5 years (0.8 to 16.4) after surgery. Total shoulder replacement is a relatively effective treatment in this elderly group of patients. However, there is a requirement for more intense patient care in the peri-operative period, and non-fatal medical or surgical complications are common. Most of these elderly patients will have a comfortable functional shoulder for the rest of their lives


The Journal of Bone & Joint Surgery British Volume
Vol. 93-B, Issue 1 | Pages 57 - 61
1 Jan 2011
Naveed MA Kitson J Bunker TD

The combination of an irreparable tear of the rotator cuff and destructive arthritis of the shoulder joint may cause severe pain, disability and loss of independence in the aged. Standard anatomical shoulder replacements depend on a functioning rotator cuff, and hence may fail in the presence of tears in the cuff. Many designs of non-anatomical constrained or semi-constrained prostheses have been developed for cuff tear arthropathy, but have proved unsatisfactory and were abandoned. The DePuy Delta III reverse prosthesis, designed by Grammont, medialises and stabilises the centre of rotation of the shoulder joint and has shown early promise. This study evaluated the mid-term clinical and radiological results of this arthroplasty in a consecutive series of 50 shoulders in 43 patients with a painful pseudoparalysis due to an irreparable cuff tear and destructive arthritis, performed over a period of seven years by a single surgeon. A follow-up of 98% was achieved, with a mean duration of 39 months (8 to 81). The mean age of the patients at the time of surgery was 81 years (59 to 95). The female to male ratio was 5:1. During the seven years, six patients died of natural causes. The clinical outcome was assessed using the American Shoulder and Elbow score, the Oxford Shoulder Score and the Short-form 36 score. A radiological review was performed using the Sirveaux score for scapular notching. The mean American Shoulder and Elbow score was 19 (95% confidence interval (CI) 14 to 23) pre-operatively, and 65 (95% CI 48 to 82) (paired t-test, p < 0.001) at final follow-up. The mean Oxford score was 44 (95% CI 40 to 51) pre-operatively and 23 (95% CI 18 to 28) (paired t-test, p < 0.001) at final follow-up. The mean maximum elevation improved from 55° pre-operatively to 105° at final follow-up. There were seven complications during the whole series, although only four patients required further surgery


The Bone & Joint Journal
Vol. 95-B, Issue 9 | Pages 1232 - 1238
1 Sep 2013
Wiater BP Boone CR Koueiter DM Wiater JM

Some surgeons are reluctant to perform a reverse total shoulder arthroplasty (RTSA) on both shoulders because of concerns regarding difficulty with activities of daily living post-operatively as a result of limited rotation of the shoulders. Nevertheless, we hypothesised that outcomes and patient satisfaction following bilateral RTSA would be comparable to those following unilateral RTSA. A single-surgeon RTSA registry was reviewed for patients who underwent bilateral staged RTSA with a minimum follow-up of two years. A unilateral RTSA matched control was selected for each shoulder in those patients undergoing bilateral procedures. The Constant–Murley score (CMS), American Shoulder and Elbow Surgeons (ASES) score, Subjective Shoulder Values (SSV), visual analogue scale (VAS) for pain, range of movement and strength were measured pre- and post-operatively. The mean CMS, ASES, SSV, VAS scores, strength and active forward elevation were significantly improved (all p < 0.01) following each operation in those undergoing bilateral procedures. The mean active external rotation (p = 0.63 and p = 0.19) and internal rotation (p = 0.77 and p = 0.24) were not significantly improved. The improvement in the mean ASES score after the first RTSA was greater than the improvement in its control group (p = 0.0039). The improvement in the mean CMS, ASES scores and active forward elevation was significantly less after the second RTSA than in its control group (p = 0.0244, p = 0.0183, and p = 0.0280, respectively). Pain relief and function significantly improved after each RTSA in those undergoing a bilateral procedure. Bilateral RTSA is thus a reasonable form of treatment for patients with severe bilateral rotator cuff deficiency, although inferior results may be seen after the second procedure compared with the first. Cite this article: Bone Joint J 2013;95-B:1232–8


The Bone & Joint Journal
Vol. 101-B, Issue 12 | Pages 1512 - 1519
1 Dec 2019
Klug A Konrad F Gramlich Y Hoffmann R Schmidt-Horlohé K

Aims. The aim of this study was to evaluate the outcome of Monteggia-like lesions at midterm follow-up and to determine whether the surgical treatment of the radial head influences the clinical and radiological results. Patients and Methods. A total of 78 patients with a Monteggia-like lesion, including 44 women and 34 men with a mean age of 54.7 years (19 to 80), were available for assessment after a mean 4.6 years (2 to 9.2). The outcome was assessed using the Mayo Elbow Performance Score (MEPS), Oxford Elbow Score (OES), Mayo Modified Wrist Score (MMWS), and The Disabilities of the Arm, Shoulder and Hand (DASH) score. Radiographs were analyzed for all patients. A total of 12 Mason type I, 16 type II, and 36 type III fractures were included. Surgical treatment consisted of screw fixation for all type II and reconstructable type III fractures, while radial head arthroplasty (RHA) or excision was performed if reconstruction was not possible. Results. The mean MEPS was 88.9 (40 to 100), mean OES was 40.1 (25 to 48), mean MMWS was 88.1 (50 to 100), mean DASH score was 14.7 (0 to 60.2), and mean movement was 114° (. sd. 27) in extension/flexion and 155° (. sd. 37) in pronation/supination. Mason III fractures, particularly those with an associated coronoid fracture treated with RHA, had a significantly poorer outcome. Suboptimal results were also identified in patients who had degenerative changes or heterotopic ossification on their latest radiograph. In contrast, all patients with successful radial head reconstruction or excision had a good outcome. Conclusion. Good outcomes can be achieved in Monteggia-like lesions with Mason II and III fractures, when reconstruction is possible. Otherwise, RHA is a reliable option with satisfactory outcomes, especially in patients with ligamenteous instability. Whether the radial head should be excised remains debatable, although good results were achieved in patients with ligamentous stability and in those with complications after RHA. Cite this article: Bone Joint J 2019;101-B:1512–1519


The Bone & Joint Journal
Vol. 101-B, Issue 7 | Pages 852 - 859
1 Jul 2019
Reigstad O Holm-Glad T Korslund J Grimsgaard C Thorkildsen R Røkkum M

Aims. Plate and screw fixation has been the standard treatment for painful conditions of the wrist in non-rheumatoid patients in recent decades. We investigated the complications, re-operations, and final outcome in a consecutive series of patients who underwent wrist arthrodesis for non-inflammatory arthritis. Patients and Methods. A total of 76 patients, including 53 men and 23 women, with a mean age of 50 years (21 to 79) underwent wrist arthrodesis. Complications and re-operations were recorded. At a mean follow-up of 11 years (2 to 18), 63 patients completed questionnaires, and 57 attended for clinical and radiological assessment. Results. Of the 76 patients, 46 (60.5%) had complications, resulting in 65 re-operations, mainly related to the plate and screws. In the 63 patients who completed the questionnaires, the mean Quick Disabilities of Arm, Shoulder and Hand (QuickDASH) score was 36 (0 to 91), the mean Patient-Rated Wrist and Hand Evaluation (PRWHE) score was 40 (0 to 96), and 14 patients (22%) reported no wrist pain. Grip strength, pinch strength, and pronation and supination were significantly reduced compared with the contralateral forearm. The outcome was worse in patients who had previously undergone surgery to the wrist, and those with complications. A total of 13 are awaiting further re-operations, giving a total re-operation rate of 63% (40/63). Conclusion. We observed complications and re-operations throughout the follow-up period and therefore consider wrist arthrodesis to be more complicated than previously assumed. Many of the patients never got used to or accepted their stiff wrists and reported a substantial reduction in function and residual pain. Motion-sparing surgery should be offered prior to wrist arthrodesis. Cite this article: Bone Joint J 2019;101-B:852–859


Bone & Joint 360
Vol. 11, Issue 5 | Pages 34 - 36
1 Oct 2022


The Bone & Joint Journal
Vol. 101-B, Issue 12 | Pages 1489 - 1497
1 Dec 2019
Wang J Ma H Chou TA Tsai S Chen C Wu P Chen W

Aims. The aim of this meta-analysis was to compare the outcome of total elbow arthroplasty (TEA) undertaken for rheumatoid arthritis (RA) with TEA performed for post-traumatic conditions with regard to implant failure, functional outcome, and perioperative complications. Materials and Methods. We completed a comprehensive literature search on PubMed, Web of Science, Embase, and the Cochrane Library and conducted a systematic review and meta-analysis. Nine cohort studies investigated the outcome of TEA between RA and post-traumatic conditions. The preferred reporting items for systematic reviews and meta-analysis (Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)) guidelines and Newcastle-Ottawa scale were applied to assess the quality of the included studies. We assessed three major outcome domains: implant failures (including aseptic loosening, septic loosening, bushing wear, axle failure, component disassembly, or component fracture); functional outcomes (including arc of range of movement, Mayo Elbow Performance Score (MEPS), and the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire), and perioperative complications (including deep infection, intraoperative fracture, postoperative fracture, and ulnar neuropathy). Results. This study included a total of 679 TEAs for RA (n = 482) or post-traumatic conditions (n = 197). After exclusion, all of the TEAs included in this meta-analysis were cemented with linked components. Our analysis demonstrated that the RA group was associated with a higher risk of septic loosening after TEA (odds ratio (OR) 3.96, 95% confidence interval (CI) 1.11 to 14.12), while there was an increased risk of bushing wear, axle failure, component disassembly, or component fracture in the post-traumatic group (OR 4.72, 95% CI 2.37 to 9.35). A higher MEPS (standardized mean difference 0.634, 95% CI 0.379 to 0.890) was found in the RA group. There were no significant differences in arc of range of movement, DASH questionnaire, and risk of aseptic loosening, deep infection, perioperative fracture, or ulnar neuropathy. Conclusion. The aetiology of TEA surgery appears to have an impact on the outcome in terms of specific modes of implant failures. RA patients might have a better functional outcome after TEA surgery. Cite this article: Bone Joint J 2019;101-B:1489–1497


Bone & Joint Open
Vol. 3, Issue 10 | Pages 746 - 752
1 Oct 2022
Hadfield JN Omogbehin TS Brookes C Walker R Trompeter A Bretherton CP Gray A Eardley WGP

Aims

Understanding of open fracture management is skewed due to reliance on small-number lower limb, specialist unit reports and large, unfocused registry data collections. To address this, we carried out the Open Fracture Patient Evaluation Nationwide (OPEN) study, and report the demographic details and the initial steps of care for patients admitted with open fractures in the UK.

Methods

Any patient admitted to hospital with an open fracture between 1 June 2021 and 30 September 2021 was included, excluding phalanges and isolated hand injuries. Institutional information governance approval was obtained at the lead site and all data entered using Research Electronic Data Capture. Demographic details, injury, fracture classification, and patient dispersal were detailed.


The Journal of Bone & Joint Surgery British Volume
Vol. 88-B, Issue 8 | Pages 1105 - 1109
1 Aug 2006
Kandemir U Allaire RB Jolly JT Debski RE McMahon PJ

Our aim was to determine the most repeatable three-dimensional measurement of glenoid orientation and to compare it between shoulders with intact and torn rotator cuffs. Our null hypothesis was that glenoid orientation in the scapulae of shoulders with a full-thickness tear of the rotator cuff was the same as that in shoulders with an intact rotator cuff. We studied 24 shoulders in cadavers, 12 with an intact rotator cuff and 12 with a full-thickness tear. Two different observers used a three-dimensional digitising system to measure glenoid orientation in the scapular plane (ie glenoid inclination) using six different techniques. Glenoid version was also measured. The overall precision of the measurements revealed an error of less than 0.6°. Intraobserver reliability (correlation coefficients of 0.990 and 0.984 for each observer) and interobserver reliability (correlation coefficient of 0.985) were highest for measurement of glenoid inclination based on the angle obtained from a line connecting the superior and inferior points of the glenoid and that connecting the most superior point of the glenoid and the most superior point on the body of the scapula. There were no differences in glenoid inclination (p = 0.34) or glenoid version (p = 0.12) in scapulae from shoulders with an intact rotator cuff and those with a full-thickness tear. Abnormal glenoid orientation was not present in shoulders with a torn rotator cuff


The Journal of Bone & Joint Surgery British Volume
Vol. 91-B, Issue 3 | Pages 367 - 373
1 Mar 2009
Allom R Colegate-Stone T Gee M Ismail M Sinha J

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


The Bone & Joint Journal
Vol. 98-B, Issue 2 | Pages 218 - 223
1 Feb 2016
Scalise J Jaczynski A Jacofsky M

Aims. The eccentric glenosphere was principally introduced into reverse shoulder arthroplasty to reduce the incidence of scapular notching. There is only limited information about the influence of its design on deltoid power and joint reaction forces. The aim of our study was to investigate how the diameter and eccentricity of the glenosphere affect the biomechanics of the deltoid and the resultant joint reaction forces. . Methods. Different sizes of glenosphere and eccentricity were serially tested in ten cadaveric shoulders using a custom shoulder movement simulator. Results. Increasing the diameter of the glenosphere alone did not alter the deltoid moment arm. However, using an eccentric glenosphere increased the moment arm of the deltoid, lowered the joint reaction force and required less deltoid force to generate movement. Conclusion. Eccentricity is an independent variable which increases deltoid efficiency and lowers joint reaction forces in a reverse shoulder arthroplasty. Cite this article: Bone Joint J 2016;98-B:218–23