INTRODUCTION:
Repeated transfers and wheelchair propulsion in patients with a neurological deficit of the lower limbs overloads the upper limbs mechanically, particularly the shoulders, which become weight-bearing. Under these conditions, arthroplasty implants are subjected to large stresses, even though this indication is controversial in such a context. We hypothesized that joint replacement in weight-bearing shoulders will relieve pain and improve range of motion, with a positive impact on function and autonomy, without increasing the complication rate relative to the able-bodied population.

MATERIALS AND METHODS:
This retrospective study involved 13 implants in 11 patients (4 total shoulder arthroplasty, 4 hemi-arthroplasty and 3 reverse shoulder arthroplasty) who had a mean follow-up of 33.7 ± 27 months (12-85 months). The clinical assessment included active and passive range of motion, pain, Constant score, and the Wheelchair User's Shoulder Pain Index (WUSPI). Radiographs were evaluated to look for signs of loosening and scapular notching. The patients' autonomy was evaluated through the number of transfers, means of locomotion (manual or electric wheelchair) and the functional independence measure (FIM). Two subgroups were defined based on the initial pathology: neurological shoulder or functional shoulder.

RESULTS:
The 11 patients had a mean age of 64 ± 19 years (23-85 years) and were all long-term wheelchair users (electrical or mechanical). The pain level on VAS decreased from 8 ± 3 preoperatively to 4 ± 2 postoperatively (p = 0.003). The mean Constant score increased 90% from 22 ± 11 preoperatively to 42 ± 23 postoperatively (p = 0.008). The WUSPI score decreased by 73% from 80 ± 30 to 21 ± 15 (p = 0.001). The range of motion improved in the subgroup of patients with functional shoulders but not in the subgroup of patients with neurological shoulders. The means of locomotion was altered in five patients (63%) by the acquisition of an electric wheelchair, but with no significant change in the number of daily transfers. There were no radiographic signs of implant loosening at the final assessment. Two implants had to be revised: one anatomical prosthesis was converted to a reverse configuration because of a secondary rotator cuff rupture; one case of early infection required a two-stage implant change.

DISCUSSION:
Joint replacement in weight-bearing shoulders is an effective medium-term solution for cuff tear arthropathy and glenohumeral OA, mainly for addressing pain, with slight improvements in range of motion, depending on the initial pathology. This intervention requires lifestyle adaptations such as changes in daily transfer practices and means of locomotion.

LEVEL OF EVIDENCE:
IV, retrospective study.



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