The Influence of Critical Shoulder Angle in Secondary Rotator Cuff Failure After Shoulder Replacement: An Age- and Sex-Matched Case-Control Study.

Introduction Decreased or increased critical shoulder angles (CSA) are associated with osteoarthritis or rotator cuff failure respectively. Secondary cuff failure after shoulder arthroplasty is disabling and often requires additional surgery. The aim of this study was to investigate if the initial CSA correlated with cuff failure in the context of shoulder arthroplasty. Methods Patients from a tertiary referral centre were reviewed from 2011-2017. Those who underwent revision from hemiarthroplasty (HA) or anatomic total shoulder arthroplasty (TSA) to a reverse shoulder arthroplasty (RSA) following rotator cuff failure were compared to an age and sex-matched control group. The CSA was calculated from initial pre-operative radiographs. Results In this study, 16 patients with symptomatic cuff failure after anatomic TSA or HA requiring revision to RSA were compared to a control group of 16 age- and sex-matched patients showing no signs of symptomatic cuff failure. The median CSA in the study group was significantly greater than that of the control group (31.5o, IQR = 29.8 - 36.1o vs. 29.5o, IQR = 27.6 - 30.4o; p= 0.026). Conclusion The difference in CSA between those who required revision for secondary cuff failure than those who didn't suggest that pre-operative measurement of CSA may help guide surgical planning in shoulder arthroplasty.

Medium-term rates of radiolucency after primary total shoulder arthroplasty using a cementless metal-backed pegged polyethylene glenoid.

BACKGROUND: Total shoulder arthroplasty is an established treatment with the commonest cause of failure loosening of the glenoid component. Hydroxyapatite metal-backed glenoid components could offer better survivorship due to improved fixation. The aim of this study was to investigate periprosthetic radiolucency rates associated with an uncemented, metal-backed polyethylene glenoid component with medium-term results. METHODS: A single centre retrospective study examining radiological outcomes of the Epoca metal-backed glenoid component. Radiographs were analysed for post-operative adequacy of glenoid seating and radiographs at follow-up assessed for periprosthetic lucencies and any revision procedures were recorded. RESULTS: Forty-one patients were followed up with a mean follow-up time of 5.5 years (3-8 years). Primary indication for total shoulder arthroplasty was osteoarthritis (80%). Mean age was 69 years (53-86 years). Ninety-five per cent of glenoid components were completely seated. At follow-up six patients had undergone revision (14.6%). Thirty of the remaining patients (86%) did not demonstrate any radiolucency on follow-up radiographs. Complete glenoid seating post-operatively was associated with lower rate of subsequent radiolucency and revision (P < 0.01). CONCLUSION: Low rates of radiolucency at medium-term follow-up with an uncemented metal-backed glenoid, however significant rates of revision. Complete seating of the glenoid component was associated with lower rates of radiolucency and revision.

Short-term rates of radiolucency after primary total shoulder arthroplasty using a cementless metal-backed pegged polyethylene glenoid.

BACKGROUND: Total shoulder arthroplasty has shown good clinical efficacy in treating primary and secondary degenerative conditions of the glenohumeral joint. Glenoid loosening, however, remains the commonest cause of failure. The purpose of this study was to investigate the rate of radiographic periprosthetic lucency associated with the use of an uncemented, pegged, metal-backed polyethylene glenoid component. MATERIALS AND METHODS: A retrospective, single-centre study using the Epoca (Synthes, Paoli, Pennsylvania) metal-backed glenoid component. Operations were performed by two experienced consultant upper limb surgeons. Radiographs were analysed for immediate post-operative component seating and periprosthetic radiolucent lines at predefined regular post-operative intervals. Intra- and inter-observer reliability was assessed to improve validity of results. RESULTS: Mean age and follow-up was 72 (48-91) years and 2.5 years (2-5), respectively. Main indications for total shoulder arthroplasty were primary osteoarthritis, rheumatoid arthritis, revision for failed hemi-arthroplasty and acute fracture. Ninety-six per cent of components were completely seated post-operatively. Fifty-four (95%) of the 57 shoulders had no periprosthetic radiolucent lines at most recent follow-up. Complete post-operative glenoid seating was significantly associated with the absence of later periprosthetic radiolucency (p < 0.01). CONCLUSION: This study reports low early radiolucency rates with the pegged, uncemented, metal-backed polyethylene glenoid prosthesis used. Excellent post-operative glenoid seating is associated with a significantly lower rate of radiolucency. Longer follow-up data are required to confirm these early promising results.Level of evidence: Therapeutic, level IV.

The influence of fatty infiltration and muscle atrophy of the rotator cuff muscles on midterm functional outcomes in total shoulder resurfacing at six years' follow-up.

BACKGROUND: We report functional outcomes at six years in patients with varying degrees of fatty infiltration and atrophy of the rotator cuff muscles who have undergone anatomic total shoulder replacement. METHODS: A retrospective analysis of case notes and magnetic resonance imaging scans of patients undergoing total shoulder replacement for primary glenohumeral arthritis was performed. Patients were grouped based upon their pre-operative magnetic resonance imaging findings for fatty infiltration, muscle area and tendinopathy. Post-operative functional outcomes were assessed using the Oxford Shoulder Score and Quick Disabilities of the Arm, Shoulder and Hand score. Post-operative measurements were made for active shoulder movements. RESULTS: Thirty-two patients were reviewed at a mean of 67 months following surgery. All patients demonstrated fatty infiltration on their pre-operative magnetic resonance imaging scan. Muscle atrophy was shown in 22 patients and 12 had tendinopathy. Multiple regression analysis showed no correlation between the Oxford Shoulder Score (p = 0.443), the Quick Disabilities of the Arm, Shoulder and Hand score (p = 0.419), forward flexion (p = 0.170), external rotation (p = 0.755) and any of the pre-operative independent variables. DISCUSSION: The degree of fatty infiltration, muscle atrophy and tendinopathy of the rotator cuff muscle on pre-operative magnetic resonance imaging scanning is not associated with functional outcome score or functional movement at medium-term follow-up following total shoulder replacement. LEVEL OF EVIDENCE: IV.

Thermal damage during humeral reaming in total shoulder resurfacing.

INTRODUCTION: Total shoulder resurfacing (TSR) provides a reliable solution for the treatment of glenohumeral arthritis. It confers a number of advantages over traditional joint replacement with stemmed humeral components, in terms of bone preservation and improved joint kinematics. This study aimed to determine if humeral reaming instruments produce a thermal insult to subchondral bone during TSR. PATIENTS AND METHODS: This was tested in vivo on 13 patients (8 with rheumatoid arthritis and 5 with osteoarthritis) with a single reaming system and in vitro with three different humeral reaming systems on saw bone models. Real-time infrared thermal video imaging was used to assess the temperatures generated. RESULTS: Synthes (Epoca) instruments generated average temperatures of 40.7°C (SD 0.9°C) in the rheumatoid group and 56.5°C (SD 0.87°C) in the osteoarthritis group (P = 0.001). Irrigation with room temperature saline cooled the humeral head to 30°C (SD 1.2°C). Saw bone analysis generated temperatures of 58.2°C (SD 0.79°C) in the Synthes (Epoca) 59.9°C (SD 0.81°C) in Biomet (Copeland) and 58.4°C (SD 0.88°C) in the Depuy Conservative Anatomic Prosthesis (CAP) reamers (P = 0.12). CONCLUSION: Humeral reaming with power driven instruments generates considerable temperatures both in vivo and in vitro. This paper demonstrates that a significant thermal effect beyond the 47°C threshold needed to induce osteonecrosis is observed with humeral reamers, with little variation seen between manufacturers. Irrigation with room temperature saline cools the reamed bone to physiological levels and should be performed regularly during this step in TSR.

Magnetic resonance scanning vs axillary radiography in the assessment of glenoid version for osteoarthritis.

BACKGROUND: Osteoarthritic shoulders are mainly associated with glenoid retroversion. Total shoulder arthroplasty with the glenoid component implanted in retroversion predisposes to loosening of the glenoid prosthesis. Correction of glenoid retroversion through anterior eccentric reaming, before glenoid component implantation, is performed to restore normal joint biomechanics. Accurate preoperative assessment is required to ascertain the degree of retroversion and calculate the degree of reaming. MATERIALS AND METHODS: We assessed the utility of magnetic resonance imaging (MRI) for the assessment of glenoid version in glenohumeral osteoarthritis compared with standard plain axillary radiography (AXR). Two independent observers reviewed both types of imaging in 48 primary osteoarthritic shoulders on 2 separate occasions. RESULTS: The mean glenoid version measured was -14.3° on MRI and -21.6° on AXR (mean difference, -7.36°; P < .001). Intraobserver and interobserver reliability coefficients were 0.96 and 0.9, respectively, for MRI and 0.8 and 0.71, respectively, for AXR. Glenoid retroversion was greater in 73% of AXR. CONCLUSION: We demonstrated that MRI is more reproducible in the assessment of glenoid version in osteoarthritis and provides excellent intraobserver and interobserver reliability. MRI is useful for preoperative osseous imaging for total shoulder arthroplasty because it offers a more precise method of determining glenoid version compared with x-ray imaging in addition to the standard assessment of rotator cuff integrity.

The influence of rotator cuff pathology on functional outcome in total shoulder replacement.

INTRODUCTION: Total shoulder replacement (TSR) is a reliable treatment for glenohumeral osteoarthritis. In addition to proper component orientation, successful arthroplasty requires accurate restoration of soft tissues forces around the joint to maximize function. We hypothesized that pathological changes within the rotator cuff on preoperative magnetic resonance imaging (MRI) adversely affect the functional outcome following TSR. MATERIALS AND METHODS: A retrospective analysis of case notes and MRI of patients undergoing TSR for primary glenohumeral osteoarthritis over a 4-year period was performed. Patients were divided into three groups based upon their preoperative MRI findings: (1) normal rotator cuff, (2) the presence of tendonopathy within the rotator cuff, or (3) the presence of a partial thickness rotator cuff tear. Intra-operatively tendonopathy was addressed with debridement and partial thickness tears with repair. Functional outcome was assessed with the Oxford Shoulder Score (OSS), and quick disabilities of the arm, shoulder and hand score (quick-DASH). RESULTS: We had a full dataset of complete case-notes, PACS images, and patient reported outcome measures available for 43 patients, 15 in group 1, 14 in group 2, and 14 in group 3. Quick-DASH and OSS were calculated at a minimum of 24 months following surgery. There was no statistically significant difference between the results obtained between the three groups of either the OSS (P = 0.45), or quick-DASH (P = 0.46). CONCLUSIONS: TSR is an efficacious treatment option for patients with primary glenohumeral osteoarthritis in the medium term, even in the presence of rotator cuff tendonopathy or partial tearing. Minor changes within the cuff do not significantly affect functional outcome following TSR.

Is MRA an unnecessary expense in the management of a clinically unstable shoulder? A comparison of MRA and arthroscopic findings in 90 patients.

BACKGROUND AND PURPOSE: In detection of glenoid labrum pathology, MR arthrography (MRA) has shown sensitivities of 88-100% and specificities of 89-93%. However, our practice suggested that there may be a higher frequency of falsely negative reports. We assessed the accuracy of this costly modality in practice. PATIENTS AND METHODS: We retrospectively reviewed MRA reports of 90 consecutive patients with clinical shoulder instability who had undergone shoulder arthroscopy. All had a history of traumatic anterior shoulder dislocation and had positive anterior apprehension tests. All underwent arthroscopy and stabilization during the same procedure. We compared the findings, using arthroscopic findings as the gold standard in the identification of glenoid labrum pathology. RESULTS: 83 of the 90 patients had glenoid labrum tears at arthroscopy. Only 54 were correctly identified at MRA. All normal glenoid labra were identified at MRA. This gave a sensitivity of 65% and a specificity of 100% in identification of all types of glenoid labrum tear. 74 patients had anterior glenoid labral tears that were detected at an even lower rate of sensitivity (58%). INTERPRETATION: The sensitivity of MRA in this series was substantially lower than previously published, suggesting that MRA may not be as reliable a diagnostic imaging modality in glenohumeral instability as previously thought. Our findings highlight the importance of an accurate history and clinical examination in the management of glenohumeral instability. The need for MRA may not be as high as is currently believed.

Shoulder hemiarthroplasty for fracture with a conservative rehabilitation regime.

INTRODUCTION: Standard rehabilitation regime following hemiarthroplasty for trauma is early mobilisation to prevent the development of a stiff shoulder. However, an aggressive early rehabilitation may lead to non-union of the greater tuberosity. We hypothesise that a delayed rehabilitation will result in a good union rate without undue risk of shoulder stiffness. MATERIALS AND METHODS: Between December 1996 and June 2003, 40 patients with three or four part fracture of proximal humerus with or without dislocation, not amenable to open reduction and internal fixation underwent hemiarthroplasty with reconstruction of tuberosities and a conservative rehabilitation regime at our centre (age range of 39-92 with a mean of 68). Pathologic fractures and non-cooperative and/or demented patients were excluded. Patients were kept in a sling for 4 weeks before physiotherapy was commenced. They were reviewed at an average of 55 months (12-95) for assessment of pain, range of movement, activities of daily living and strength. Radiographs were taken to evaluate the union of the greater tuberosity. RESULTS: One patient lost to follow up. In 12.8% of the patients (mainly elderly, with mean age of 78.8) the greater tuberosity failed to heal. In those with a healed greater tuberosity the average elevation was more than 130 degrees , and the average external rotation was 40 degrees . A total of 51.3% of the patients had excellent results, 33.3% had satisfactory and 15.4% had unsatisfactory results. CONCLUSION: Postoperative immobilisation did not result in excessive stiffness and excellent functional results were achieved, especially in those younger than 70 years of age. However, tuberosity union could not be guaranteed in very old patients.