Rotator cuff tear is the leading cause of shoulder pain in the elderly. There isn't enough evidence nor clinical guidelines to guide the treatment of massive rotator cuff tears, specially irreparable tears. Arthroscopic partial repair has been widely used and superior capsular reconstruction (SCR), either with allograft, autograft or augmentation with long head biceps brachii tendon (LHBBT), has been recently added. It is showing promising results, but lacking high quality evidence.

This is a prospective clinical study to compare the outcomes of different surgical methods for massive rotator cuff tendon tears. Minimal follow-up time will be two years. In this trial, massive rotator cuff tears will be anatomically repaired if possible. For irreparable tears a method will be randomly assigned intra-operatively once a tear is determined to be irreparable - either partial repair or partial repair with superior capsular reconstruction using the long head biceps brachii (LHBB) tendon. Patients who are eligible for the study but refuse operative treatment, will serve as conservative study group.

The hypothesis is that massive rotator cuff tears that are reparable will have the best functional outcomes. For irreparable tears, augmentation with LHBBT will give superior results over partial repair.

Patients with massive rotator cuff tendon tears aged between 50 to 80 years will be included in the study following the eligibility criteria. Massive tear is defined as grade III tear according to Davidson and Burkhart classification (2010), supraspinatus (SSP) tendon retraction described by Patte (1990) classification.

The study is conducted in Tartu University Hospital Sports Traumatology Centre and rotator cuff repair procedures will be done by three orthopaedic surgeons with long experience in arthroscopic shoulder surgery.

It is determined intra-operatively whether the tear is reparable or not. If possible, the tendon(s) will be anatomically repaired. For irreparable tears intra-operative urn randomization takes place - either partial repair or partial repair with SCR using the LHBB tendon. Surgical techniques will be standardized. Patients who refuse operative treatment, will be followed as conservative treatment group.

The primary objective of the study is the functional status of the included subjects in different treatment groups. The secondary objective of the study is to confirm whether the tendons are intact on follow-up magnetic resonance imaging (MRI) 6 months, 12 months and 24 months after operation using Sugaya classification (2007).

The post-operative therapy regimen will be the same for each study group. Subjects will come for scheduled visits at 6-month, 12-month, and 24-month timepoints. Assessment tools consist of range of motion (ROM), strength measurements, preoperative radiography measuring acromio-humeral index (AHI), critical shoulder angle (CSA), acromion type and shoulder arthrosis (Hamada), functional scores: The Disabilities of the Arm, Shoulder and Hand (DASH), The Constant-Murley score (CMS), The American Shoulder and Elbow Surgeons (ASES) and visual analogue scale (VAS), also including Tampa kinesiophobia score and emotional well-being (EEK) score. Goutallier classification (1994) will be used pre- and postoperatively to measure muscle fatty infiltration.

Inclusion Criteria:

• Massive rotator cuff tendon tear: grade III according to Davidson and Burkhart 2010 classification, diagnosed on MRI, and LHBB tendon is intact.
• Primary rotator cuff pathology AND
• Symptoms have not lasted more than 6 months.
• In case of trauma, traumatic event no more than 6 months ago.
• Aged between 50 and 80 at the time of enrollment.
• Subject is able and willing to give informed consent AND
• Subject is physically and mentally willing and able to comply with the post-operative rehabilitation protocol, questionnaires, and scheduled clinical and radiographic visits.

Exclusion Criteria:

• Previous rotator cuff surgery of the index shoulder.
• Acute or chronic osteomyelitis.
• Inflammatory joint disease (rheumatoid arthritis/ (pseudo)gout arthritis).
• Uncontrolled diabetes.
• Active oncological disease.
• Radiologically stage IV shoulder joint arthrosis (rotator cuff arthropathy).
• Systemic or intra-articular corticosteroid therapy less than 60 days prior to planned operation date.
• Intramuscular or peroral corticosteroid treatment less than 30 days prior to planned operation date.
• Acute or chronic conditions that are contraindications for functional testing.
• MRI contraindicated.
• Substance or alcohol abuse.
• Refusal or withdrawal of consent.