Kinematic 3-D motion analysis of shoulder resurfacing hemiarthroplasty - An objective assessment method

Shoulder replacement is indicated in the treatment of pain due to osteoarthritis. Few studies have objectively assessed range of motion (RoM) gains at different post-operative time points. This is a prospective 3D motion analysis study to objectively quantify RoM changes at multiple time points following shoulder resurfacing arthroplasty (SRA) for primary gleno-humeral osteoarthritis, comparing it with clinically measured RoM. Clinical assessment, Visual Analog Scale (VAS) pain score, Constant-Morley (CS) and Oxford Shoulder Score (OSS) were recorded. Motion analysis was performed for RoM and three activities of daily living tasks (ADL), pre-operatively and post-operatively at 4 and 12 months. Nineteen shoulders in fifteen patients were included. The mean age was 72 years (range 52-84). There were significant improvements in external and internal rotation, ability to place the hand behind the head and reach the fifth lumbar vertebra, at 4 months on clinical examination and kinematic analysis with no further improvements at 12 months. There was significant improvement in abduction at 4 months with further improvement at 12 months, which was significantly more than noted on clinical assessment. In contrast, kinematic analysis showed a reduction in flexion between 4 and 12 months, while clinically there appeared to be an improvement between these time periods. This is the first study to prospectively utilise objective kinematic 3-D motion analysis in addition to clinical measurements and outcome scores, to investigate the outcome of resurfacing arthroplasty at multiple time points after surgery, providing an understanding into the trends of change in these parameters.