The InSpace Ballon Implant was introduced to the U.S. medical device market by Stryker in July 2021 for arthroscopic treatment of massive irreparable rotator cuff tears (see this link). The InSpace device had previously received Conformité Européenne marking in 2010, and had been used in 29,000 procedures. The InSpace device is a saline-filled biodegradable balloon that is inserted surgically in the space between the humerus and the acromion. The cost of this device may vary, but locally it is about $7,000. This cost may or may not be covered by the patient's insurance.

The authors of the April 2022 Lancet publication, Subacromial balloon spacer for irreparable rotator cuff tears of the shoulder (START:REACTS): a group-sequential, double-blind, multicentre randomised controlled trial, assessed the outcomes of this device with debridement in comparison to debridement alone.

They point out that "new surgical procedures can expose patients to harm and should be carefully evaluated before widespread use". They aimed to determine the effectiveness of the InSpace balloon (Stryker, USA), an innovative surgical device that has been recommended as treatment for rotator cuff tears that cannot be repaired (see this link).

They conducted a double-blind, group-sequential, adaptive randomised controlled trial in 24 hospitals in the UK, comparing arthroscopic debridement of the subacromial space with biceps tenotomy (debridement only group) with the same procedure but including insertion of the InSpace balloon (debridement with device group). Participants had an irreparable rotator cuff tear, which had not resolved with conservative treatment, and they had symptoms warranting surgery. Eligibility was confirmed intraoperatively before randomly assigning (1:1) participants to a treatment group using a remote computer system. Masking was achieved by using identical incisions for both procedures, blinding the operation note, and a consistent rehabilitation programme was offered regardless of group allocation. Patients and assessors were blinded to group allocation, with intraoperative randomisation ensuring allocation concealment to ensure a low risk of bias. The primary outcome was the Oxford Shoulder Score at 12 months.

They assessed allocated qualifying and consenting patients: 61 participants to the debridement only group and 56 to the debridement with InSpace Balloon group. 43% of participants were female, 57% were male.

They obtained primary outcome data for 114 (97%) participants. The mean Oxford Shoulder Score at 12 months was 34·3 (SD 11·1) in the debridement only group and 30·3 (10·9) in the debridement with InSpace Balloon group (mean difference adjusted for adaptive design –4·2 [95% CI –8·2 to –0·26];p=0·037) favoring debridement alone over debridement with InSpace Balloon.

There was no difference in adverse events between the two groups.

The authors found that the InSpace balloon is not an effective treatment, could be harmful, and is unlikely to be cost-effective. They concluded, "In an efficient, adaptive trial design, our results favoured the debridement only group. We do not recommend the InSpace balloon for the treatment of irreparable rotator cuff tears."

Comment: This is the first published randomised trial on the balloon and the first study to clearly demonstrate an absence of benefit for the device. The fact that the FDA has "cleared" this device for use (see this link) and that the United States Centers for Medicare & Medicaid Services (CMS) has established a new Healthcare Common Procedure Coding System (HCPCS) code C9781 for outpatient hospitals and ambulatory surgery centers to report the insertion of Stryker's InSpace balloon implant (see this link) would seem to attach some legitimacy to the use of this device. However, as pointed out in a recent post (see this link), these actions do not assure the safety, efficacy or cost-effectiveness of new innovative devices.

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