- 1.The conduction of the power analysis in a randomized controlled trial should be based on the primary outcome parameter as this is the main parameter under investigation in the planned trial and as such will determine the confirmation or rejection of the hypothesis as was the case in our study. Therefore, our study can be considered sufficiently powered. An additional qualitative and quantitative description of secondary outcome parameters as, for example, complications seems feasible in our opinion.
- 2.I disagree with the author as I believe that a 90% follow-up rate can generally be considered as sufficient in clinical studies. As per journal policy, randomized controlled trials need to reach a threshold level of 80% follow-up rate to be considered a level 1 trial. This was successfully accomplished in this study. Nonetheless, the potential attrition bias is outlined in the limitations section of our manuscript.
- 3.I agree that the presence of a bilateral instability might influence the perception of integrity of the investigated shoulder; however, the rate of bilateral affection was similar in both groups (P = .542) and, therefore, does not confound the results of our study.
- 4.Assessment of instability recurrence included the following parameters: dislocation (a postoperative instability event with shoulder dislocation for a certain period of time requiring a reduction maneuver), subluxation (a postoperative instability event reported by the patient without complete dislocation and without requiring a reduction maneuver), and apprehension (defined as positive apprehension and relocation test).
- 5.In order to increase the external validity of our study results, we included 2 centers with 4 surgeons experienced in performing both techniques. The fact that all 4 surgeons were highly specialized surgeons does not compromise the comparability between groups but might have reduced the risk of complications in both groups. Whether the same results can be obtained with iliac-crest bone graft transfer techniques employing screws or buttons remains speculative and subject to future investigations. The only certainty is that a technique using implants will add the risk of implant-related problems. This, however, does not exclude the potential for other advantages.
- 6.Although it is true that the rate of donor site morbidity reported in the study is rather high, it must be noted that sensory disturbances around the harvesting site at the iliac-crest typically do not bother the patients. Nonetheless, I completely agree that the necessity of harvesting a bone graft from the iliac crest will always be a disadvantage. This is the reason why we have attempted to use allograft for glenoid reconstruction surgery before but observed extensive osteolysis of the grafts with subpar clinical outcomes.1,2We are aware that other authors from other countries have published very appealing results for allograft glenoid reconstruction in anterior shoulder instability. This difference is likely best explained by the availability and use of different types of allografts.
- Massive graft resorption after iliac crest allograft reconstruction for glenoid bone loss in recurrent anterior shoulder instability.140. Arch Orthop Trauma Surg, 2020: 895-903
- The biomechanical effect of bone grafting and bone graft remodeling in patients with anterior shoulder instability.Am J Sports Med. 2020; 48: 1857-1864