Reverse polarity total shoulder arthroplasty (RTSA) has gained popularity over recent years for the treatment of the painful cuff deficient shoulder. Although proposed over 20 years ago and despite good clinical outcomes the RTSA has struggled to gain popularity due to reported high levels of complications.

One such complication is post-operative instability with frequencies of up to 30% (De Wilde 2002). The Bayley-Walker RTSA was designed specifically for patients with difficult reconstruction problems in whom an unconstrained prosthesis would not offer sufficient stability. It is a reverse anatomy fixed fulcrum constrained prosthesis. The glenoid component has a long HA-coated tapered helical screw, with large pitch and depth, fixation is augmented by a grooved HA coated glenoid plate.

The purpose of this study was to review the clinical experience from The Royal National Orthopaedic Hospital Stanmore and to ascertain the rate of glenoid component loosening. We also carried out a radiographic review to correlate loosening with patterns of lucency on post-operative radiographs. One hundred and five B-W TSRs in 103 patients were included, 24% of which were performed as revision of previous failed arthroplasty. In total, 8/105 glenoids required revision. Of those eight patients, two were cases of septic loosening. Of all nine specified areas of glenoid, tip lucency on x-ray appeared to be most strongly associated with need for glenoid revision. 5/9 cases with tip lucency progressed to loosening of the glenoid. Where tip lucency was not seen, 93/96 glenoid components remained secure, giving tip lucency a negative predictive value of 97%. Excluding the two infected cases, the glenoid remained secure in 97/103 patients undergoing BW-TSR with follow-up up to 13 years. The BW-TSR is a satisfactory and durable solution to the cuff-deficient shoulder in variety of challenging groups including younger patients and as a salvage procedure following failed, cuff-deficient arthroplasty.

Introduction

The Stanmore Percentage of Normal Shoulder Assessment (SPONSA) is a simple, fast and reproducible measure of the subjective state of a shoulder. It has been invaluable in our busy clinical practice. This study validates the SPONSA score against the Oxford Shoulder and Constant score and demonstrates a greater sensitivity to change.

Arthroplasty as a salvage procedure for cuff and glenoid deficiency poses major problems due to the limitations in treatment options and debilitating symptoms. We hypothesized that computer aided deigned and manufactured (CADCAM) total shoulder arthroplasty, using a precisely fitted glenoid shell, can relieve the pain and poor function associated with irreparable rotator cuff pathology and severe glenoid deficiency in the shoulder.

Of the 127 cases so far performed, a prospective cohort study 79 consecutive subjects, with a mean 28.7 month follow-up, were evaluated by a single practitioner blinded to their group status. Outcome was assessed using a validated clinical shoulder scoring system and radiographic review.

The subjects had a mean age of 58 (41–82) and their indication (where recorded) was mainly revision total shoulder replacement (62%) with some cases for primary osteoarthritis (12%) and rheumatoid arthritis (9%) and a proportion for other reasons (19%) including 1 re-revision case for dislocation.

Clinical follow-up was limited in this population (n=58, 73%) The ‘CADCAM’ group’s mean Stanmore Percentage of Normal Shoulder Assessment scores (SPONSA) were relatively unchanged post surgery (47 to 42 p=0.3). The Oxford Shoulder scores improved significantly (15 to 33, p< 0.0001). Most significantly, and by way of explanation, post surgery subjects recorded a reduction in the Visual Analogue Scale (Pain) scores (6.6 to 2.9) p< 0.0001). Patient satisfaction was generally good.

Radiographic review of the 79 cases revealed glenoid component screw breakage (4%, n=5) which is a moderate correlate of glenoid loosening (r = 0.65, r2 = 0.42) and probably more accurate than radiographic lucent lines seen in 6% (n=7). Humeral lucency was seen in 10%, (n=8). These radiographic findings correlated well with the clinical findings.

Postoperative pain and function was significantly improved in subjects undergoing the ‘CADCAM’ technique of shoulder arthroplasty offering a consistent salvage option for situations where no alternative to glenoid reconstruction is feasible.

This pilot study assesses level of agreement between surface and fine wire electromyography (EMG), in order to establish if surface is as reliable as fine wire in the diagnosis and treatment of abnormal muscle patterning in the shoulder. 18 subjects (11 female, mean 36 years) with unstable shoulders were recruited after written consent and ethical approval. Anthropometric information and mean skinfold size for triceps, subscapular, biceps and suprailiac sites were obtained. Triple stud self adhesive surface electrodes (“Triode” – Thermo Scientific) were placed over Pectoralis Major (PM), Latissimus Dorsi (LD), Anterior Deltoid (AD) and Infraspinatus (IS) at standardised locations. A ‘Medi-Link’ dual channel surface EMG (Electro Medical Supplies) displayed a rectified smoothed signal. Patients performed five identical uniplanar standard movements (flexion, abduction, external rotation, extension and cross body adduction). After a rest period, a dual needle technique for fine wire insertion was used displaying a raw EMG signal on a ‘Sapphire II’ four channel EMG unit. An experienced examiner in each technique reported if muscle activation patterns differed from agreed normal during any movement and were blinded to the other test results. Sensitivity, specificity and kappa values for level of agreement between methods were calculated for each muscle according to the method of Altman. 15 patients were successfully tested. Sensitivity, specificity and kappa values between techniques for each muscles were PM (57%, 50%, 0.07), LD (38%, 85%, 0.22), AD (0%, 76%, −0.19) and IS (85%, 75%, 0.6). Only IS demonstrated high sensitivity and specificity and a moderate level of agreement between the two techniques. There was no correlation between skinfold size and agreement levels. Surface did not agree with wire analysis for PM, LD and AD, although IS did show moderate agreement. Subcutaneous fat did not appear to affect correlation.

Aim. To identify and quantify the reasons for failure of primary shoulder arthroplasty.

Materials. Seventy-nine Revision Shoulder Arthroplasties (RSA) in 75 patients were performed between January 1990 and July 2003. Twelve patients underwent more than one revision. Five patients were lost to follow-up. The indications for PSA (38 total shoulder arthroplasties, 37 hemiarthroplasties) were trauma (22), osteoarthritis (13), rheumatoid arthritis (11), avascular necrosis (9), cuff tear arthropathy (9), traumatic arthritis (5), capsulorraphy arthropathy (4),and instability (2). Glenoid and humeral bone stock, and rotator cuff integrity were analysed and the reasons for failure of the index procedure were determined.

Results. The median interval between PSA and RSA was 46 months (1 month to 22.8 years; mean 28 months). Thirty-six (58.1%) PSAs (of which 26 of 37 hemiarthroplasties (70%)) failed in the first three years. Failure of the PSA was caused by rotator cuff deficiency (24), glenoid bone erosion (19), glenoid component loosening (25), humeral bone erosion (3), infection of the implant (3) and periprosthetic fracture (1). Revision of a loose humeral component was performed in 6 cases, but 31 humeral components were revised in order to deal with glenoid or rotator cuff conditions.

Conclusion. When faced with a limited surgical armamentarium or tactic, there is a predictable rate of failure of shoulder replacement involving the interaction of the failed or failing rotator cuff and the evolution of glenoid deficiency.

Aim: To evaluate the role and outcome of FFTSA in shoulders with arthritis and/or irreparable rotator cuff tears.

Materials. The records of 60 consecutive patients with FFTSA were retrospectively reviewed. Primary FFTSA (group 1) was performed in 29 (48%), revision FFTSA (group 2) in 26 (43%), and re-revision FFTSA (group 3) in 5 (9%) patients. The mean age at primary FFTSA was 70 years (37 – 82), and at revision FFTSA, 67.6 years (38 – 89) at a mean interval of 38 months after primary intervention. In re-revision FFTSA the interval between the primary (mean age 64 years) and final (mean age 68.4 years) interventions varied from 20 to 148 months. Primary FFTSA was performed for cuff arthropathy in 18 (62%) and after trauma in 5 (17%): all 29 patients had rotator cuff insufficiency. Revision FFTSA was performed for failure of humeral head replacement (HHR) after fracture in 17 (65%) of which 14 had rotator cuff insufficiency. All those in group 3 had rotator cuff insufficiency. The dominant indication for intervention was pain in 59 cases. The glenoid component was uncemented in all cases. The humeral component was cemented in 27 of the 29 Primary FFTSA. CADCAM variations of the standard humeral design were used in 8 cases.

Results. At a mean follow-up of 25 months, 81% of primary FFTSA had no or mild pain, and 87.5% were satisfied or very satisfied with the outcome: both outcomes were independent of the original rotator cuff defect. At a mean follow-up of 41 months, 69% of revision FFTSA had no or mild pain, and 68 % were satisfied or very satisfied: the least satisfied patients were those in which a previous HHR for fracture had been the primary intervention. There were 3 complications in group 1, 2 in group 2, and 2 in group 3. In 4 patients with deficient deltoid function, 3 were satisfied with the eventual outcome

Conclusion. FFTSA has a clear role in the management of shoulders in which the rotator cuff has failed and a joint replacement is required for pain relief.

Aim: To demonstrate that inappropriate sequencing of activation of shoulder muscles can cause shoulder instability.

Methods. The records of 933 cases of recurrent shoulder instability referred to a specialist shoulder service between 1993 and 2003 were reviewed. All patients were assessed clinically. Muscle patterning abnormality (Bayley 1986) was identified in 428 patients (46%). Confirmatory functional electromyography was performed in 166 (36%). Inappropriate pectoralis major activation was identified in 73% of anterior instability. In posterior instability, inappropriate activation of latissimus dorsi and anterior deltoid was present in 72% and infra-spinatus was suppressed in 19%. Arthroscopic assessment was performed in 141 (33%), identifying structural lesions of instability in 86 (20%).

All patients diagnosed with muscle patterning disorder received specilalist physical therapy using biofeedback. Symptomatic improvement or stability was achieved in 76% of patients with anterior instability but with no previous surgery, and in 53% of patients with previous surgery. Posterior instability was eliminated in 85% of cases.

Conclusion. Muscle patterning abnormalities contribute to recurrent instability of the shoulder in 46% of cases. The success of physical therapy in these patients is high.