Medialized versus Lateralized Center of Rotation in Reverse Total Shoulder Arthroplasty: A Systematic Review and Meta-Analysis

Abstract

One of the original biomechanical principles of reverse total shoulder arthroplasty (RTSA) is medialization of the center of rotation (COR) relative to the native level of the glenoid. Several authors have proposed the lateralized center of rotation, which is characterized by a lateralized (L) glenoid and medialized (M) humeral component. The aim of this review is to compare the clinical and functional outcomes of COR in medialized (M-RTSA) and lateralized (L-RTSA) RTSA in patients with uniform indications and treatment through a meta-analysis. A PRISMA-guided literature search of PubMed, Medline, Embase, Scopus, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews and Cochrane Clinical Answers was conducted from April to May 2021. Twenty-four studies were included in the qualitative synthesis, and 19 studies were included in the meta-analysis. Treatment with RTSA resulted in positive post-operative outcomes and low complication rates for both groups. Statistically relevant differences between L-RTSA group and M-RTSA group were found in post-operative improvement in external rotation with arm-at-side (20.4° and 8.3°, respectively), scapular notching rates (6.6% and 47.7%) and post-operative infection rates (1% and 7.7%). Both lateralized and medialized designs were shown to improve the postoperative outcomes. Nevertheless, a lateralized COR resulted in greater post-operative external rotation.

Influence of lateralized versus medialized reverse shoulder arthroplasty design on external and internal rotation: a systematic review and meta-analysis

“…They also found that lateralized versus medialized RSA had lower rates of scapular notching (6.6% vs. 47.7%, P<0.01) and postoperative infection (1% vs. 7.7%, P=0.01). Berton et al [ 3 ] used stricter inclusion and exclusion criteria in their study compared to Cho et al, [ 5 ] and their work was more similar to the present study, as they included studies reporting on patients with indications limited to cuff tear arthropathy, irreparable cuff tear, or cuff tear associated with osteoarthritis. Although Berton et al [ 3 ] also excluded studies including patients undergoing revision RSA or an indication of rheumatoid arthritis, acute fracture, post-traumatic fracture sequelae, tumor, or active infection, the authors only required 1 year of follow-up.…”

“…Berton et al [ 3 ] used stricter inclusion and exclusion criteria in their study compared to Cho et al, [ 5 ] and their work was more similar to the present study, as they included studies reporting on patients with indications limited to cuff tear arthropathy, irreparable cuff tear, or cuff tear associated with osteoarthritis. Although Berton et al [ 3 ] also excluded studies including patients undergoing revision RSA or an indication of rheumatoid arthritis, acute fracture, post-traumatic fracture sequelae, tumor, or active infection, the authors only required 1 year of follow-up. Since ROM is known to continue to improve up to 2 years postoperatively [ 52 ], the findings of Berton et al [ 3 ] may not accurately represent the full improvement that occurs with lateralized implants.…”

“…Prior meta-analyses have been conducted to compare axial ROM after lateralized versus medialized RSA [ 3 , 5 , 51 ]; however, their inclusion and exclusion criteria vary. Cho et al [ 5 ] included five studies that compared lateralized (n=346) versus medialized (n=217) RSA and found no difference in postoperative ER (standardized mean difference, 0.21 [−0.14 to 0.56]; P=0.238); however, pre- to postoperative improvement in ER favored lateralized RSA in their analysis of two studies (standardized mean difference, 0.71 [0.36–1.07]; P<0.001).…”

“…Although Berton et al [ 3 ] also excluded studies including patients undergoing revision RSA or an indication of rheumatoid arthritis, acute fracture, post-traumatic fracture sequelae, tumor, or active infection, the authors only required 1 year of follow-up. Since ROM is known to continue to improve up to 2 years postoperatively [ 52 ], the findings of Berton et al [ 3 ] may not accurately represent the full improvement that occurs with lateralized implants. Despite variations in inclusion and exclusion criteria, most prior meta-analyses agree that lateralized RSA provides superior ER compared to medialized RSA, with no consistent differences in clinical outcome scores across studies.…”

“…Since its first description by Grammont in 1985 [ 1 , 2 ], the design of reverse shoulder arthroplasty (RSA) has evolved considerably. While effective at alleviating pain and improving overhead range of motion (ROM), initial reports showed poor restoration of satisfactory external and internal rotation (ER and IR, respectively) [ 3 , 4 ]. Consequently, these reports led many to believe that RSA leads to poor active ER and poor active and passive IR.…”