Response to “Letter Regarding: Comparison of Clinical and Radiographic Outcomes of Supination External Rotation Type IV Equivalent Ankle Fractures With and Without Deltoid Repair”

Dear Editor,

Thank you to Dr Bahl for the thoughtful comments and concerns regarding our study, “Comparison of Clinical and Radiographic Outcomes of Supination External Rotation Type IV Equivalent Ankle Fractures With and Without Deltoid Repair.” ¹ The letter raises several relevant and important points, which I would like to address point by point.

I agree that this study carries inherent limitations, as is often the case with retrospective designs. However, we believe it provides valuable insight into the evolving role of the pre- and intraoperative external rotation stress test and how we might better quantify deltoid integrity in a clinical setting.

Objective Criteria for the Stress Test

We agree on the importance of standardization. In our study, external rotation stress tests were considered positive for deltoid rupture when there was ≥4 mm of medial clear space widening with either weightbearing, stress radiographs, or stress fluoroscopy in accordance with previously published literature. This threshold was consistently applied across all cases. We did not have a standardization of torque applied to the ankle. Rather, the test was performed by fellowship-trained foot and ankle surgeons with extensive experience in treating ankle fractures. The attendings would apply this external rotation stress to the ankle in a standard fashion to elicit instability. In the future, we can consider torque-measuring devices to limit variance in the force applied.

Confirmation of Deltoid Rupture

To address concerns regarding injury severity, it is important to clarify that all patients included in the deltoid repair group had confirmed deltoid ligament rupture, as documented in their operative notes. This was a key inclusion criterion to reduce heterogeneity in injury severity across groups. That being said, it is likely that some of these were high-grade partial vs complete injuries. Each of the patients had documented widening of the medial clear space preoperatively. However, in each case after the fibula was adequately fixed surgeon preference determined whether or not to address the deltoid. In many cases, the patients had an intraoperative stress test that demonstrated valgus laxity because of the deltoid injury. However, the medial clear space diastasis had been reduced likely secondary to the fact that these were lower SER IV equivalent injuries with a presumed intact intraosseus ligament. In many cases we used either MRI or intraoperative arthroscopy to further classify these injuries. Some of these cases also had varying degrees of AITFL and PITFL involvement as well. Further attempts to subclassify these injuries may be valuable, but given the number in the study, we would be left with smaller groups to compare. I am happy to discuss this issue further.

Surgical Variability

We acknowledge that the involvement of 13 surgeons introduces some variability in surgical technique. However, all surgeons adhered to a general institutional algorithm for fixation and deltoid repair, which minimized major technique discrepancies. In each case the fibula was addressed first and the ankle was then reassessed. If the ankle was still malreduced, further procedures were performed to address this. In the well-aligned ankle with a well-fixed fibula, attending preference determined if a deltoid repair was required. This cohort are the patients of interest in our study. Future prospective work could benefit from a stratified analysis based on technique, as you suggested.

Preoperative MCS <4 mm in Repaired Patients

We appreciate your attention to the finding that 21 patients (26.9%) in the deltoid repair group had a preoperative medial clear space <4 mm. However, these patients were all either stress radiograph–positive or intraoperative fluoroscopy–positive preoperatively. We could include these values as opposed to the values presented on their initial injury films if that is more valuable. We assert that preoperative nonweightbearing, and nonstress radiographs may not capture the full extent of deltoid injury and that intraoperative assessment remains a critical tool. We hope this finding will prompt further investigation into the limitations of preoperative MCS thresholds.

PROMIS Scores and Statistical Power

We agree that the subset analysis based on PROMIS scores limits statistical power. However, we performed an a priori power analysis to ensure adequate sample size. PROMIS data were available for the following:

1. Preoperative scores: 44 of 66 (67%) in the repair group, 51 of 78 (65%) in the nonrepair group, totaling 95 of 144 (66%).

2. Postoperative scores: 50 of 66 (76%) in the repair group, 54 of 78 (69%) in the nonrepair group, totaling 104 of 144 (72.2%).

We typically have a 70% threshold for postoperative follow-up for publication at FAI and FAO. Despite this, we recognize the limitations of missing data and the need for more robust prospective studies with complete data sets.

Thank you again for your constructive feedback. We hope our responses provide greater clarity on the methodology and interpretations. We also appreciate your engagement in this important and evolving area of foot and ankle surgery.

Warm regards,

Supplemental Material

sj-pdf-1-fao-10.1177_24730114251361508 – Supplemental material for Response to “Letter Regarding: Comparison of Clinical and Radiographic Outcomes of Supination External Rotation Type IV Equivalent Ankle Fractures With and Without Deltoid Repair”

Supplemental material, sj-pdf-1-fao-10.1177_24730114251361508 for Response to “Letter Regarding: Comparison of Clinical and Radiographic Outcomes of Supination External Rotation Type IV Equivalent Ankle Fractures With and Without Deltoid Repair” by Mark Drakos in Foot & Ankle Orthopaedics

Mark Drakos, MD Hospital for Special Surgery, New York, NY, USA Email: [e-mail]