In recent years, use of anatomic stemless total shoulder arthroplasty (AsTSA) has increased. Despite evidence to suggest good mid-term results at 2-year follow-up there is a paucity of evidence for longer term follow-up. This study aimed to investigate outcomes at a minimum of 5 years post-operatively following primary AsTSA. This study is a retrospective case series of all patients who underwent a Mathys Affinis AsTSA from July 2010 (first case) to August 2018 (to allow minimum 5-year follow-up). Clinical outcomes included revision rate, range of motion and patient reported outcomes (Oxford Shoulder Score and Numerical Satisfaction Score). Radiological outcome was assessment of radiolucent lines for Lazarus grading. A total of 105 stemless TSAs were implanted. Five patients underwent revision (4.8%). Seventy-five AsTSA's were included in the final study for analysis of 5-year outcomes. Median follow-up time was 6.1 years. Median age was 69 years old and 81% were female. Oxford shoulder score showed a range of 18 to 48, with a median score of 47. Satisfied or very Satisfied was selected in 94.37%. Median range of motion assessments showed forward elevation 160°, abduction 150°, external rotation 40°, and mode internal rotation was to the lumbar spine. No glenoid lucency was present in 79.7%. There were 9.5% with Lazarus Grade 1 lucency, 5.4% with Lazarus Grade 2, and 5.4% Lazarus Grade 3. No humeral lucency was observed. This cohort study demonstrates promising clinical and radiological outcomes for the Mathys Affinis Stemless TSA at minimum 5 years post-operatively.
Over the last decade stemless shoulder arthroplasty has become increasingly popular. However, stability of metaphyseal loading humeral components remains a concern. This study aimed to assess the stability of the Affinis stemless humeral component using Radiostereometric analysis (RSA). Patients underwent total shoulder arthroplasty via a standardised technique with a press-fit stemless humeral component and a cemented pegged glenoid. Tantalum beads were inserted into the humerus at the time of operation. RSA of the relaxed shoulder was completed at weeks 1, 6, 13, 26, 52 and 104 post-operatively. Stressed RSA with 12 newtons of abduction force was completed from week 13 onwards. ABRSA 5.0 software (Downing Imaging Limited, Aberdeen) was used to calculate humeral component migration and induced movement. 15 patients were recruited. Precision was: 0.041, 0.034, 0.086 and 0.101 mm for Superior, Medial, Posterior and Total Point Motion (TPM) respectively. The mean TPM over 2 years was 0.24 (0.30) mm, (Mean (Standard deviation)). The mean rate of migration per 3 month time period decreased from 0.45 (0.31) to 0.02 (0.01) mm over 2 years. Mean inducible movement TPM peaked at 26 weeks at 0.1 (0.08) mm, which reduced to 0.07 (0.06) mm by 104 weeks when only 3 patients had measurable inducible motion. There was no clear trend in direction of induced movement. There were no adverse events or revisions required. We conclude migration of the humeral component was low with little inducible movement in the majority of patients implying initial and 2 year stability of the stemless humeral component.
