Subacromial balloon spacer for irreparable rotator cuff tears of the shoulder (START:REACTS): a group-sequential, double-blind, multi-centre randomized controlled trial
Andrew Metcalfe, Helen Parsons, Nicholas Parsons, Jaclyn Brown, Josephine Fox, Elke Gemperlé Mannion, Aminul Haque, Charles Hutchinson, Rebecca Kearney, Iftekhar Khan, Tom Lawrence, James Mason, Nigel Stallard, Martin Underwood*, Stephen Drew*, on behalf of the START:REACTS team
To review is to opine
Rotator cuff tears are a common cause for shoulder pain and disability. While the majority of rotator cuff tears are amenable to surgical repair, a third of tears cannot be repaired to its original site of attachment. Massive irreparable rotator cuff tears remain a challenge for the shoulder surgeon in any age range. Patients with irreparable tears have worse outcomes from traditional rotator cuff surgery and have fewer treatment options. As a result, novel surgical procedures have been introduced as options for these complex situations. The InSpace subacromial balloon spacer device (Stryker, USA) is a saline-filled biodegradable balloon inserted into the subacromial space. The device maintains this space with the goal of improving the mechanics of the shoulder and aid rehabilitation.
The purpose of the study was to determine the effectiveness of the InSpace balloon for people with irreparable rotator cuff tears. The authors recognize the potential harm patients are exposed to when a new surgical procedure is introduced. In addition, the authors recognize the need for careful evaluation of new surgical procedures before widespread use.
The purpose of the study was to determine the effectiveness of the InSpace balloon for people with irreparable rotator cuff tears.
Materials and Methods
A double-blind multi-centre, superiority randomized controlled trial across 24 hospitals in the UK was performed using a group sequential adaptive design with two preplanned interim analyses. Adults with symptomatic irreparable rotator cuff tears and for whom conservative management had been unsuccessful were included. The control group (debridement only) underwent arthroscopic debridement of the subacromial space and biceps tenotomy. The intervention group (debridement and device) underwent the same procedure with the insertion of the InSpace balloon using the manufacturer’s recommended technique. All participants were offered the same rehabilitation. All primary (Oxford Shoulder Score) and secondary outcomes (Constant Score, flexion and abduction, WORC Index, EuroQol, EQ-5D-5L, change in symptoms, Participant Global Impression of Chane, resource use, and adverse events) were assessed at 3, 6, and 12 months.
One hundred seventeen participants were randomly allocated to a treatment group, 61 to the debridement only group and 56 to the debridement with device group. The average age of the debridement only group was 67·3 (+/-9·0) 66·4 (+/-7·6) for the debridement with device group. Fifty-seven percent of all participants were male, the average duration of symptoms was4·9 (6·7) years, and 21% had previous surgery. The mean tear size was similar between groups (debridement only 4.3cm versus debridement with device 4.2cm).
|Results at 12 months|
|Outcome||Mean Difference or
Adjusted Odds Ratio
Adjusted mean difference* (95% CI)
*Negative values favour the debridement-only group
**OR with 95% CI with Fishers exact test.
|Oxford Shoulder Score||–4·2 (–7·8 to –0·6)||Not significant,
favoring debridement only
|WORC Index||–8·4 (–16·8 to –0·1)||Not significant,
favoring debridement only
|EQ-5D-5L||–0·056 (–0·150 to 0·035)||Not significant,
favoring debridement only
|Participant Global Impression of Change, since the operation||0·5 (0·3 to 1·1)||||Not significant,
|Analgesia Use||0·8 (0·4 to 1·8)**|
|Overall||9 (15%)||11 (20%)|
|Any Serious Adverse Events||2 (3%)||4 (7%)|
|Unrelated to Surgery||1 (pain after fall)||2 (pain after fall, proximal humerus fracture after fall)|
|Related to Surgery||1 (pain)||2 (pain, 1 converted to RSP)|
A blinded randomized controlled trial design with predefined stopping boundaries allowed the study to be stopped at more than half the maximum potential sample size of 221 participants allowing the authors to report their findings early. During the time of the study the COVID-19 restrictions limited face-to-face assessments therefore there was a high amount of missing data. In the primary analysis the authors found that arthroscopic debridement only was superior to arthroscopic debridement with the InSpace device based on the Oxford Shoulder Score at 12 months. In addition, secondary outcomes were similar to the primary outcome.
Through this adaptive design methodology with interim analyses the authors concluded that the InSpace device is unlikely to be of benefit and may be harmful to this patient population. The authors recommended against the use of the InSpace subacromial balloon spacer device for the treatment of irreparable rotator cuff tears.
Lancet is one of the most prestigious medical journals with an impact factor of ~80, and the authors’ conclusions are strongly worded and in sharp contrast to that of the recent JBJS study on the balloon. Additional clinical research is required on this device, and it will be interesting to see in the coming years which of these studies on the balloon more accurately describes the clinical performance of the InSpace for treatment of irreparable rotator cuff tears.
Metcalfe A, Parsons H, Parsons N, Brown J, Fox J, Gemperlé Mannion E, Haque A, Hutchinson C, Kearney R, Khan I, Lawrence T, Mason J, Stallard N, Underwood M, Drew S; START:REACTS team. Subacromial balloon spacer for irreparable rotator cuff tears of the shoulder (START:REACTS): a group-sequential, double-blind, multicentre randomised controlled trial. Lancet. 2022 May 21;399(10339):1954-1963. doi: 10.1016/S0140-6736(22)00652-3. Epub 2022 Apr 21. PMID: 35461618.
Verma N, Srikumaran U, Roden CM, Rogusky EJ, Lapner P, Neill H, Abboud JA; SPACE GROUP. InSpace Implant Compared with Partial Repair for the Treatment of Full-Thickness Massive Rotator Cuff Tears: A Multicenter, Single-Blinded, Randomized Controlled Trial. J Bone Joint Surg Am. 2022 Apr 22. doi: 10.2106/JBJS.21.00667. Epub ahead of print. PMID: 35777921.