Background: A balloon spacer is a relatively simple addition to an arthroscopic debridement procedure for irreparable rotator cuff tears.
Objective: To evaluate the clinical and cost-effectiveness of a subacromial balloon spacer for individuals undergoing arthroscopic debridement for irreparable rotator cuff tears.
Design: A multicentre participant-and assessor-blinded randomised controlled trial comparing arthroscopic debridement with the InSpace® (Stryker, Kalamazoo, MI, USA) balloon to arthroscopic debridement alone, using a novel adaptive design. Pretrial simulations informed stopping boundaries for two interim analyses, using outcome data from early and late time points.
Setting: A total of 24 NHS centres.
Participants: Adults with a symptomatic, irreparable rotator cuff tear for whom conservative management had been unsuccessful.
Interventions: Arthroscopic debridement of the subacromial space plus insertion of the InSpace balloon compared with arthroscopic debridement alone.
Main outcome measures: Oxford Shoulder Score at 12 months.
Results: A predefined stopping boundary was met at the first interim analysis. Recruitment stopped with 117 participants randomised. We obtained primary outcome data on 114 participants (97%). The mean Oxford Shoulder Score at 12 months was 34.3 in the debridement-only group (59 participants of 61 randomised) and 30.3 in the debridement with balloon group (55 participants of 56 randomised; mean difference: −4.2; 95% confidence interval −8.2 to −0.26; p = 0.037). There was no difference in safety events. In the cost-effectiveness analysis, debridement-only dominated with a probability of <1% that the device is cost-effective.
Magnetic resonance imaging substudy: To evaluate the function of the balloon, we developed a dynamic magnetic resonance imaging protocol to induce humeral movement by activating the deltoid. The pandemic restricted recruitment, so the sample size was small (n = 17).
Statistical methodology study: We applied the novel adaptive design approach to data from seven previous randomised controlled trials. The method would have been applicable to five of these trials and would have made substantial savings in time to recruitment, without compromising the main findings of the included trials.
Interim analysis interpretation study: We asked potential data monitoring committee members to review interim analysis reports presented using Bayesian and frequentist frameworks. They did not always follow the stopping rules and would benefit from additional information to support decision-making.
Limitations: The InSpace balloon could be beneficial in a different population although we are not aware of it being widely used for other purposes. As a result of the pandemic, we were not able to complete data collection for objective measures.
Conclusions: In this efficient adaptive trial, clinical and cost-effectiveness favoured the control treatment without the InSpace balloon. Therefore, we do not recommend this device for the treatment of irreparable rotator cuff tears.
Future work: There is an urgent need for high-quality research into interventions for people with irreparable rotator cuff tears as there is a lack of good evidence for all available treatment options at present.
Trial registration: This trial is registered as ISRCTN17825590.
Funding: This project (project reference 16/61/18) was funded by the Efficacy and Mechanism Evaluation (EME) Programme, a Medical Research Council and National Institute for Health and Care Research (NIHR) partnership. The trial is co-sponsored by the University of Warwick and University Hospitals Coventry and Warwickshire NHS Trust. This study will be published in full in Efficacy and Mechanism Evaluation; Vol. 10, No 3. See the NIHR Journals Library website for further project information.
Tears of the rotator cuff tendons of the shoulder are very common. Some people with a rotator cuff tear have pain and loss of function that is not improved by simple treatments, and they may undergo surgery.
Many people have the tear repaired. if this cannot be done, keyhole surgery can be used to clear space around the tendons and allow the shoulder to move better. This procedure is called an arthroscopic debridement.
The InSpace® (Stryker, Kalamazoo, MI, USA) balloon is a dissolvable device that is placed by the surgeon above the shoulder joint, after an arthroscopic debridement. We wanted to know if it improved results for patients and was good value.
We compared the standard operation, arthroscopic debridement, with the same procedure with the InSpace balloon inserted. We collected data from 117 people with rotator cuff tears from 24 NHS hospitals. Because of the COVID-19 pandemic, we could not directly measure strength or movement and used well-established questionnaires instead.
Twelve months after their operation, most people had improved. People who had the standard operation alone, without the balloon, had less pain and could use their shoulder more.
We calculated the costs of each treatment, including lost earnings. The InSpace balloon was more expensive and was poor value for money for the NHS.
We developed a new method for doing an early statistical analysis to decide whether we could stop the study early. Because of this, around half the number of people were needed in the study, compared with the number we would normally need to do this work. We did additional research and found that this new method would work for some other studies and would give much quicker results about which treatments work best.
We developed a new method for doing magnetic resonance imaging scans of the shoulder, although data collection was limited by the COVID-19 pandemic.
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