High and low performers in internal rotation after reverse total shoulder arthroplasty: a biplane fluoroscopic study

The impact of scapular posture and sagittal spine alignment on motion and functional outcomes following reverse total shoulder arthroplasty: a scoping review

Background

Reverse total shoulder arthroplasty (RTSA) has evolved beyond its initial indication for elderly patients with rotator cuff arthropathy and is now performed in younger patients for various shoulder pathologies. This surgical procedure has recently gained popularity and has been shown to result in similar functional improvements and complication rates compared to anatomical total shoulder arthroplasty. Scapular posture and sagittal spine alignment (SSPA) have recently emerged as factors potentially influencing RTSA outcomes. This scoping review aimed to assess the existing body of evidence on this topic.

Methods

A systematic search was conducted on MEDLINE, Embase, and CENTRAL databases to evaluate the impact of scapular posture and SSPA on RTSA outcomes.

Results

A total of 6 studies (616 shoulders) were included in this review. Scapular posture was found to influence RTSA outcomes, with studies reporting correlations between scapular posture with postoperative range of motion and functional scores. Suboptimal scapular posture, particularly type C (kyphotic posture with protracted scapulae), appeared to be associated with reduced external rotation. However, findings among the included studies regarding SSPA were varied. Some studies suggested that SSPA, notably thoracic kyphosis, might impact RTSA outcomes by influencing scapular posture, while others did not find a clear relationship.

Conclusion

Scapular posture was implicated as a potential factor affecting RTSA outcomes; however, the role of SSPA remains inconclusive. There is currently a lack of high-quality evidence in the literature to draw definitive conclusions regarding the impact of scapular posture and SSPA on RTSA outcomes. More research is warranted to investigate these relationships more comprehensively.

Obesity is associated with improvement in functional outcome but lower internal rotation after reverse shoulder arthroplasty

Background

The role of obesity as an independent risk factor for increased complications following reverse shoulder arthroplasty (RSA) continues to generate debate. While no standardized body mass index (BMI) cutoff values for shoulder arthroplasty exist, many surgeons are concerned about the potential for poor outcomes and decreased range of motion (ROM) in patients with a high BMI. The purpose of this study was to compare functional outcomes in obese and nonobese patients preoperatively and at short-term follow-up after RSA.

Methods

A retrospective review was performed of a prospectively maintained, multicenter database of primary RSAs performed by 14 surgeons between 2015 and 2019 with minimum 2-year follow-up. A total of 245 patients met the study criteria, including 111 obese (BMI >30) and 134 nonobese (BMI <30) patients. Patient-reported outcomes (PROs) as well as ROM measurements were compared between the 2 groups.

Results

At baseline, obese patients had significantly lower American Shoulder and Elbow Surgeons (36.6 vs. 42.0, P = .014), Western Ontario Osteoarthritis of the Shoulder scores (33.1 vs. 37.8, P = .043), external rotation at 90° (19° vs. 28°, P = .007), internal rotation (IR) spinal level (L5 vs. L4, P = .002), and belly press strength (P = .003) compared to the nonobese cohort. There were no statistical differences in 2-year outcomes (PROs, ROM, and strength) other than a worse IR (spinal level) in the low BMI group (L4 vs. L3, P = .002). In linear regression analyses controlling for confounding variables, increasing BMI was negatively correlated with preoperative external rotation (B = -0.591, P = .034) and preoperative IR spinal level (B = 0.089, P = .002). Increasing BMI was not correlated with postoperative external rotation at 90° (B = 0.189, P = .490) but was associated with worse postoperative IR by spinal level (B = 0.066, P = .043).

Conclusions

Obese patients have greater restrictions in external and internal rotation as well as American Shoulder and Elbow Surgeons and Western Ontario Osteoarthritis of the Shoulder scores at baseline prior to RSA. However, there are no major differences in postoperative PROs or ROM measurements between obese and nonobese patients apart from a worse active IR by spinal level in the obese group (L4 vs. L3, P = .002). This study suggests that an RSA procedure does not need to be restricted solely based on BMI.

Practical considerations for determination of scapular internal rotation and its relevance in reverse total shoulder arthroplasty planning

BACKGROUND

Scapulothoracic orientation, especially scapular internal rotation (SIR) may influence range of motion in reverse total shoulder arthroplasty (RTSA) and is subjected to body posture. Clinical measurements of SIR rely on apical bony landmarks, which depend on changes in scapulothoracic orientation, while radiographic measurements are often limited by the restricted field of view (FOV) in CT scans. Therefore, the goal of this study was (1) to determine whether the use of CT scans with a limited FOV to measure SIR is reliable and (2) if a clinical measurement could be a valuable alternative.

METHODS

This anatomical study analyzed the whole-body CT scans of 100 shoulders in 50 patients (32 male and 18 female) with a mean age of 61.2 ± 20.1 years (range 18; 91). (1) CT scans were rendered into 3D models and SIR was determined as previously described. Results were compared to measurements taken in 2D CT scans with a limited FOV. (2) Three apical bony landmarks were defined: (the angulus acromii (AA), the midpoint between the AA and the coracoid process tip (C) and the acromioclavicular (AC) joint. The scapular axis was determined connecting the trigonum scapulae with these landmarks and referenced to the glenoid center. The measurements were repeated with 0°, 10°, 20°, 30° and 40° anterior scapular tilt.

RESULTS

Mean SIR was 44.8° ± 5.9° and 45.6° ± 6.6° in the 3D and 2D model, respectively (p < 0.371). Mean difference between the measurements was 0.8° ± 2.5° with a maximum of 10.5°. Midpoint AA/C showed no significant difference to the scapular axis at 0° (p = 0.203) as did the AC-joint at 10° anterior scapular tilt (p = 0.949). All other points showed a significant difference from the scapular axis at all degrees of tilt.

CONCLUSION

2D CT scans are reliable to determine SIR, even if the spine is not depicted. Clinical measurements using apical superficial scapula landmarks are a possible alternative; however, anterior tilt influenced by posture alters measured SIR.