Do preoperative scapular fractures affect long-term outcomes after reverse shoulder arthroplasty?

BACKGROUND: Postoperative scapular stress fractures (SSF) are a formidable problem after reverse shoulder arthroplasty (RSA). Less is known about patients who have these fractures preoperatively. The primary aim of this study was to examine postoperative satisfaction in patients undergoing primary RSA who have preoperative SSF and compared to a matched cohort without preoperative fracture. The secondary aim was to examine the differences in patient reported outcomes between and within study cohorts.

METHODS: A retrospective chart review of primary RSAs performed by a single surgeon from 2000 to 2020 was conducted. Patients diagnosed with cuff tear arthropathy (CTA), massive cuff tear (MCT), or rheumatoid arthritis (RA) were included. Five hundred twenty-five shoulders met inclusion criteria. Fractures identified on preoperative CTs were divided into three groups: 1) os acromiale, 2) multi-fragments (MF), and 3) Levy types. Seventy-two shoulders had an occurrence of SSF. The remaining 453 shoulders were separated into a non-fractured cohort. ASES and VAS scores were compared pre- and postoperatively in the total fracture group and the non-fractured group cohort. The multi-fragment subgroup was also compared to the pooled Os/Levy subgroup.

RESULTS: The total incidence of SSF in all shoulders was 13.7%. There was a difference in satisfaction scores at all time points between the nonfracture (7.9 ± 2.8) and total fracture group (5.4 ± 3.6; p = < 0.001 at last visit). There was also a greater ASES total in the non-fractured group vs the total fracture group at the final visit. (69.4 ± 23.4 and 62.1 ± 24.2; p = 0.02). The MF group had worse ASES functional or VAS functional scores than the Os/Levy group at all time points: at 1 year, ASES function: (MF 24.2 ± 14.5 and Os/Levy 30.7 ± 14.2; p = 0.045); at 2 year ASES function: (MF 21.4 ± 14.4 and Os/Levy 35.5 ± 10.6; p = <0.001) and at last follow-up VAS function: (MF 4.8 ± 2.8 and Os/Levy 6.4 ± 3.2; p = 0.023).

DISCUSSION: Scapular fractures were proportionally most common in patients diagnosed with CTA (16.3%) compared to a 9.2% and 8.6% incidence in patients diagnosed with MCT and RA, respectively. Patients with preoperative SSF still see an improvement in ASES scores after RSA but do have lower satisfaction scores compared to the non-fractured cohort. The multi-fragment fracture group has lower functional and satisfaction scores at all postoperative time points compared to both the non-fracture and the Os/Levy fracture group.