Subacromial Balloon Spacer versus Partial Repair for Massive Rotator Cuff Tears: A Prospective, Randomized, Multi-center Trial

Abstract

Objectives:Despite various treatment options, the successful management of irreparable, massive rotator cuff tears (MRCTs) remains challenging. Implantation of a biodegradable subacromial balloon spacer (InSpaceTM system; OrthoSpace, Caesarea, Isreal) has gained considerable interest for the treatment of MCRTs due to its ability to effectively recenter the humeral head within the glenoid. Despite promising results, investigations examining outcomes following balloon spacer implantation are limited to small case series and short-term prospective trials without comparison to other surgical modalities. The purpose of the present investigation was to prospectively evaluate the safety and efficacy of the arthroscopically deployed, subacromial spacer balloon compared to partial rotator cuff repair in patients with MRCTs at 24 month follow up.Methods:A non-inferiority, prospective, single-blinded, multicenter, randomized, controlled, pivotal study was conducted to compare the outcomes of arthroscopic subacromial balloon spacer implantation to partial repair in the treatment of MRCTs. Patients ≥ 40 years of age with symptomatic full thickness MRCTs (tears ≥ 5 cm or ≥ 2 tendons) that had failed non-operative management were included. Clinical outcome data, derived from subjective questionnaires and physical examination, were collected at baseline and follow-up intervals at Day 10, Week 6, Month 3, 6, 12 and 24. Postoperative magnetic resonance imaging (MRI) scans were obtained at 6 weeks and 12 months. The primary composite effectiveness endpoint was defined as achievement of the minimal clinically important difference (MCID) for the Western Ontario Rotator Cuff (WORC) score (275 points) and American Shoulder and Elbow Society (ASES) score (6.4 points) by week 6 and maintenance at month 12 without subsequent secondary surgical intervention (SSSI) or serious adverse device effects (SADEs). Secondary effectiveness endpoints included changes in individual and composite clinical outcome scores relative to baseline in addition to MRI findings. Intention-to-treat (ITT), per-protocol (PP), and safety analyses were performed separately.Results:A total of 20 sites were enrolled in the investigation. One hundred, eighty-four patients were randomized into the clinical study (n= 93 balloon spacer; n= 91 partial repair) and included in the safety population, of which 183 patients were included in the ITT analysis (n=93 balloon spacer; n= 90 partial repair) and 176 in the PP analysis (n= 88 balloon spacer; n= 88 partial repair). No significant difference in demographic characteristics based on mean age, sex, race or body mass index were appreciated between groups. Mean procedure duration was 44.6 ± 16.9 minutes for the balloon spacer group and 71.2 ± 30.1 minutes for the partial repair group. Significant improvement over time relative to baseline was observed in all WORC (Fig. 1) and ASES (Fig. 2) scores in both groups. The magnitude of improvement for subjects in the balloon spacer group was the same or better than for subjects in the partial repair group at 12 and 24 month follow up. At 12 months, 51% (n=45 of 88) of patients in the balloon spacer group and 35 patients 40% (n= 35 of 88) in the partial repair group had reached and maintained the primary composite endpoint, meeting the noninferiority criteria (non-inferiority margin 10%; p = 0.0049) and corresponding to an 11.4% mean advantage for the spacer implant group. Non-inferiority was similarly confirmed in the ITT population (p=0.0089). SSSI occurred in 6 subjects (n=3 balloon spacer; n=3 partial repair), with two subjects in each group requiring reverse shoulder arthroplasty and one subject in each group undergoing shoulder arthroscopy.Conclusions:Use of the balloon spacer was found to produce non-inferior outcomes when compared to partial rotator cuff repair for patients with MRCTs at 24 month follow up. Outcomes following balloon spacer device placement met non-inferiority criteria when compared to the partial repair group based on primary composite endpoints.