Onlay versus Inlay humeral steam in Reverse Shoulder Arthroplasty (RSA): clinical and biomechanical study.

Abstract

BACKGROUND AND AIM OF THE WORK:

Reverse shoulder arthroplasty (RSA) is becoming treatment of choice in glenohumeral arthropathies with massive lesion of the rotator cuff, due to a gradual extension of indications and new designs that provide better outcome. In this study we compared two different reverse shoulder prosthesis designs, defined as Inlay (or typical Grammont type) and a relatively new model defined as Onlay (that preserves tuberosity bone stock). We analyzed clinical, biomechanical and radiological outcomes, as well as complications of RSA in these two groups.

METHODS:

We performed a prospective study on a population of 42 patients undergoing Reverse Shoulder Replacement by a single expert surgeon. We consider 21 patients (group A) who underwent to reverse shoulder replacement with a curved onlay steam with 145° inclination (Ascend Flex group, Wright medical, Memphis, TN, USA)  and 21 patients who underwent to reverse shoulder replacement with a traditional Inlay Grammont steam (Modular Shoulder System SMR, Systema Multiplana Randelli; Lima-LTO, San Daniele del Friuli, Italy) between August 2010 and October 2018. We studied the following items: active range of motion (AROM), radiological parameters (lateralization shoulder angle LSA, Distalization Shoulder Angle DSA), functional scale (Constant-Murley Score), post-operative complications (infection, aseptical implant mobilitazion, residual pain, scapular notching, fractures, tuberosity reabsorbtion, dislocation, bleedings, nerve palsy, pulmonary embolus).

RESULTS:

A significant improvement in ROM and functional score (Constant Shoulder Score) were observed in both groups. Group A (Onlay design 145°, medial tray) provides improvement in adduction, extension and external rotation compared to group B. No significant differences were found in abduction, external rotation and forward flexion. At 6 months follow-up, pain relief was detected in all patients. Although complications occur in a high percentage of patients in literature, no postoperative complications were observed in our cases series.

CONCLUSIONS:

Our results showed how RSA is a real solution to improve quality of life and to restore pain-free shoulder ROM in patients where cuff tear arthropathy occurs. Onlay design 145° may provides better active external rotation, extension, adduction: it is necessary to continue follow up and include more cases to prove these data.

• Authors: Alessandro Beltrame, Paolo Di Benedetto, Chiara Cicuto, Vanni Cainero, Renato Chisoni, Araldo Causero
• Journal: Acta bio-medica : Atenei Parmensis (Acta Biomed) Vol. 90 Issue 12-S Pg. 54-63 (12 05 2019) ISSN: 2531-6745 [Electronic] Italy
• PMID: 31821285 (Publication Type: Comparative Study, Journal Article)

Topics

• Aged
• Aged, 80 and over
• Arthroplasty, Replacement, Shoulder (methods)
• Biomechanical Phenomena
• Female
• Humans
• Humerus (surgery)
• Male
• Middle Aged
• Postoperative Complications (epidemiology)
• Prospective Studies
• Prosthesis Design
• Radiology
• Range of Motion, Articular
• Shoulder Joint (diagnostic imaging, physiology, surgery)
• Shoulder Prosthesis
• Treatment Outcome