InSpace Implant Compared with Partial Repair for the Treatment of Full-Thickness Massive Rotator Cuff Tears: A Multicenter, Single-Blinded, Randomized Controlled Trial

Background: The purpose of this study was to prospectively evaluate the efficacy and safety of a subacromial balloon spacer (InSpace implant; Stryker) compared with arthroscopic partial repair in patients with irreparable, posterosuperior massive rotator cuff tears.

Methods: Patients ≥40 years of age with symptomatic, irreparable, posterosuperior, massive rotator cuff tears and an intact subscapularis who underwent failed nonoperative management were included in this randomized controlled trial comparing the InSpace implant with partial repair. Clinical outcome data were collected at baseline through a 24-month follow-up. The primary outcome was improvement in the American Shoulder and Elbow Surgeons (ASES) scores. The secondary outcomes included change from baseline in the Western Ontario Rotator Cuff (WORC) score, the visual analog scale (VAS) pain score, the Constant-Murley shoulder score, the EuroQol-5 Dimensions-5-Level (EQ-5D-5L) score, active range of motion, and operative time. Complications and reoperations for each group were also recorded.

Results: Twenty sites randomized 184 patients: 93 in the InSpace group and 91 in the partial repair group. Significant and clinically relevant improvements in the ASES score from baseline were noted in both groups at Month 12 and were maintained at Month 24. Overall, 83% of patients in the InSpace group and 81% of patients in the partial repair group achieved the ASES minimally clinically important difference threshold, and 82% of patients in the InSpace group and 79% of patients in the partial repair group achieved the substantial clinical benefit threshold. Forward elevation was significantly greater in the InSpace group compared with the partial repair group at Day 10 (p = 0.04), Week 6 (p = 0.0001), Month 12 (p = 0.005), and Month 24 (p = 0.003). The operative time was significantly shorter in the InSpace group (p < 0.0001). No device-related surgical complications were noted, and 4 reoperations after InSpace implantation and 3 reoperations after partial repair were required.

Conclusions: The InSpace implant is an appropriate alternative to partial repair in patients with irreparable posterosuperior massive rotator cuff tears and an intact subscapularis. Notable benefits include early functional recovery and pain relief combined with a shorter operative time.

Level of evidence: Therapeutic Level I . See Instructions for Authors for a complete description of levels of evidence.