Is MIO-RSA Noninferior to BIO-RSA When it Comes to Mechanical Implant Stability? (CARS-2)

From Cuff Arthropathy to Reverse Shoulder Arthroplasty - a Multicentre Randomized Control Trial (CARS 2: Is MIO-RSA Noninferior to BIO-RSA When it Comes to Mechanical Implant Stability Measured With CT-based Motion Analysis (CTMA)?).

This clinical trial will investigate whether metallic lateralization in reverse shoulder arthroplasty is as stable as bony lateralization during the first two postsurgical years, measured with CT-based motion analysis (CTMA).

Lateralization of reverse shoulder arthroplasties may reduce the risk for complications such as limited range of motion (ROM), and scapular notching, where the lower part of the scapular neck becomes eroded due to impingement against the humeral component. There's several ways to lateralize the glenoid component, a bone transplant placed underneath the glenoid component (Bony Increased Offset Reversed Shoulder Arthroplasty: BIO-RSA) has been used for some time. Recently glenoid components with metallic lateralization of the joint centre (Metal-Increased Offset Reversed Shoulder Arthroplasty: MIO-RSA) have been introduced, but there is not much comparative literature on metal vs. bony lateralization. Patients with osteoarthritis and medialization of the glenoid articular surface, who willing to participate in a study will be randomized to receive either MIO-RSA or a BIO-RSA. CT-based motion analysis (CTMA) will be used to measure the 3-dimensional migration pattern of the glenoid components to assess the stability of the prostheses up to two years after implantation.

Reverse shoulder arthroplasty, BIO-RSA, MIO-RSA, Bony lateralization, Metallic lateralization, Orthopedic Surgery

Participants and health personnel examining the participants will be blinded. It will not be possible to blind the surgeons due to the nature of the intervention.

Patients will have a reversed shoulder arthroplasty with lateralization of the joint centre using bony lateralization (BIO-RSA).

Patients will have a reversed shoulder arthroplasty with lateralization of the joint centre using metallic lateralization (MIO-RSA).

CT-based motion analysis (CTMA) will be used to measure the 3-dimensional migration pattern of the glenoid components to assess the stability of the prostheses up to two years after implantation. The motion analysis includes measurement of translation along three orthogonal axes and rotations around two orthogonal axes. CTMA is a marker-free motion analysis, and the images are obtained on a standard CT-machine. Analysis and computation of motion data are performed using proprietary software at Sectra AB (collaborating partner) CTMA is a relative new method to measure implant migration. The precision of the measurements is 0.08-0.15 mm for translation and 0.23-0.54º for rotation, therefore, CTMA is capable of measuring very small movements of the implant relative to the surrounding bone.

The Western Ontario Osteoarthritis of the Shoulder (WOOS) index is a patient-reported, disease-specific questionnaire for the measurement of the quality-of-life in patients with osteoarthritis. There are 19 questions divided into four domains: Physical symptoms, sports and work, lifestyle and emotions. Each question is answered on a visual analogue scale ranging from 0 to 100. The overall score ranges from 0 to 1900, with 1900 being the worst. For ease of interpretation, the scores are often converted to a percentage of the maximum score.

The CMS is a multi-item functional scale assessing pain, ADL, ROM and strength of the affected shoulder. Its score ranges from 0 to 100 points, representing worst and best shoulder function, respectively. The test is divided into subjective and objective components. Two subjective: pain and activities of daily living (ADL) and two objective: range of motion (ROM) and strength. The subjective components can receive up to 35 points and the objective 65. Pain and ADL are answered by the patient; ROM and strength require a physical evaluation and are answered by the orthopaedic surgeon or the physiotherapist.

he widely used EuroQol-5 (EQ-5D-5L) will be used to measure health-related quality of life. The EQ5D-5L consists of two parts: A descriptive system (Mobility, self-care, usual activities, pain/discomfort and anxiety/depression) and the EQ-VAS that record patients self-rated health on a visual analog scale that range from 0 -100, higher levels indicate better self-rated health. The descriptive system can be converted to a single summary index number where lower levels indicate poorer health related quality of life.

The patient's active and passive range of motion (ROM) in the affected shoulder will be measured by an experienced physiotherapist with a long-legged goniometer. The directions measured will be flexion, abduction, external rotation and internal rotation, measured in degrees and/or physical landmarks.

The SSV score is defined as the subjective evaluation by the patient of shoulder function, expressed as a percentage of a normal shoulder. This score ranges from 0 to 100%.

This anchor question is asked to help determine Patient Acceptable Symptom State (PASS). "Considering all daily activities that involves your operated shoulder, your level of pain and degree of function, how satisfied are you with the condition of your shoulder is right now?" Alternatives: Satisfied/somewhat satisfied/Neither satisfied or unsatisfied/somewhat unsatisfied/Unsatisfied

This anchor question is asked to help determine Minimal Important Difference (MID) and Substantial Clinical Benefit (SCB). "Think of all the ways your operated shoulder has affected you the last week. Since your surgery, has there been any change in the condition of your shoulder that you would consider important or meaningful to you?" Alternatives: Much better/moderately better/a bit better/no change/a bit worse/moderately worse/Much worse

Inclusion Criteria: Eligible for primary RSA due to OA, massive RC tear, failed RC repair or post-instability osteoarthritis massive glenoid medialization Able to read or write Norwegian Exclusion Criteria: Severe osteoporosis Osteonecrosis of the humeral head Dementia Poor deltoid function Revision surgery ASA IV Suspected chronic infection Acute fracture