Narrow Results

Glenoid failure is one of the major indications for revision in total shoulder arthroplasty. Glenoid components should be carefully designed to improve the reliability of the prostheses, and mechanical testing can be a key tool to compare the performances of different designs. The most relevant guidelines for mechanical testing of glenoid prostheses are included in the ASTM F2028-05 Standard. The Standard refers to glenoid subluxation tests, designed to evaluate the intrinsic stability of the prosthesis system, and to glenoid edge displacement tests, which estimate the risk of micro-motions at the bone-glenoid interface. However, some indications given by the Standard are not mandatory, leaving the possibility to choose some parameters of the testing set-up and procedure. The main goal of this study was to investigate how different testing parameters (i.e. loads, velocities and bone-glenoid conformity) may affect the test results. In order to reach this target an experimental apparatus was developed and mechanical tests were performed on a keeled glenoid. The study showed that the applied load and the bone-glenoid conformity have a significant effect on the tests results, because of bone and glenoid deformation. Contrarily, the testing velocity was not found to be an influencing testing parameter.

Background: Wrist arthroplasty is increasingly offered to patients with symptomatic wrist arthritis as an alternative to wrist arthrodesis. The purpose of this study was to present our outcomes with the ReMotion™ wrist arthroplasty in a consecutive series of patients with wrist arthritis from non-inflammatory conditions.

Methods: Thirteen (eight women, nine dominant wrists) patients, 68 (44–85) years of age with advanced radiocarpal arthritis due to SLAC/SNAC (11) and Kienbock disease (2) had a ReMotion™ (Stryker, Michigan, USA) wrist arthroplasty implanted, and were prospectively followed for 7 (4–9) years. The outcome measures included patient-rated wrist and hand evaluation (PRWHE) score, disabilities of the arm, shoulder and hand questionnaire (QuickDASH) score, visual analogue pain score (0–10) on the radial and ulnar aspect of the wrist at rest (VASrR/VASuR) and activity (VASrA/VASuA), active wrist range of motion (AROM) including flexion, extension, ulnar and radial deviation, pronation and supination and grip and key-pinch strength measured preoperatively and at yearly follow-ups by independent hand therapists.

Results: Six patients had ten re-operations during the follow-up including four revisions to a new arthroplasty. Four were considered loose at follow-up. A significant reduction in PRWHE (63 to 12), radial pain at activity (6 to 1) and increased pronation (85° v 90°) was observed.

Conclusions: We found a high complication and reoperation rate, two out of 13 had no complications or reoperations. The ReMotion™ arthroplasty should be used with caution in non-inflammatory wrist patients and the patients followed closely. A high reoperation and revision rate can be expected, and surgeons familiar with revision arthroplasty procedures should perform the surgery.

Level of Evidence: Level II (Therapeutic)