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Short-Term Outcomes of Supination External Rotation IV Bimalleolar and Deltoid Variant Fractures With No Deltoid
Mahant Malempati1, Nicholas C Danford, Bonnie Y Chien
1Department of Orthopaedic Surgery, Columbia University Irving Medical Center, New York, NY.
Objectives:
To evaluate whether radiographic and clinical outcomes differ between supination-external rotation (SER) type IV bimalleolar (BM) fractures and deltoid ligament injuries treated without deltoid repair. A secondary aim was to compare outcomes between universal tubular (TB) and fibula-specific (FS) plates for fibular fixation.
Design:
Retrospective cohort study.
Setting:
Academic medical center.
Patient Selection Criteria:
Skeletally mature patients with SER-IV (AO/OTA 44-B2) ankle fractures (either BM or deltoid ligament injury without medial malleolar fracture) treated between November 2011 and July 2024. Exclusions: pathologic/pilon fractures, congenital deformity, nonunion repair, posterior malleolar fixation, or <3 months of follow-up. Secondary comparison included rotational ankle fractures (SER, pronation external rotation) stabilized with TB or FS plates.
Outcome Measures And Comparisons:
Radiographic outcomes included medial clear space (MCS), superior clear space (SCS), tibiofibular clear space (TFCS), talocrural angle, and Takakura score. Clinical outcomes included complication rates, secondary surgeries, infections, and conversions to arthroplasty. Comparisons were made between intraoperative and final postoperative radiographic measurements.
Results:
A total of 132 patients with SER-IV fracture were included in the primary study arm, with 89 in the BM group and 43 in the deltoid-variant (DV) group. Demographics were similar between cohorts, including age (BM: 49.5 ± 19.2 vs. DV: 46.0 ± 15.4 years, P = 0.25), body mass index (BM 28.8 kg/m 2 ± 5.4 vs. DV 31.1 kg/m 2 ± 9.4, P = 0.16), diabetes (BM 11.2% vs. DV 2.3%, P = 0.16), smoking (BM 9.0% vs. DV 9.3%, P = 1.0), Charlson Comorbidity Index (BM 1.8 ± 2.4 vs. DV 1.2 ± 1.8, P = 0.09), and American Society of Anesthesiologists' score (BM 1.9 ± 0.8 vs. DV 1.8 ± 0.7, P = 0.93). Changes in radiographic alignment between intraoperative and final postoperative measurements were comparable between groups, including MCS (BM: 0.3 ± 0.7 mm vs. DV: -0.5 ± 0.9 mm, P = 0.097), SCS (BM: -0.5 ± 0.9 mm vs. DV: -0.7 ± 0.7 mm, P = 0.112), and TFCS (BM: 0.0 ± 1.2 mm vs. DV: 0.2 ± 1.5 mm, P = 0.887). A total of 342 patients with rotational ankle fractures were included in this second study arm, with 282 in the TB group and 60 in the FS group. Demographics were comparable between cohorts, including age (TB 47.5 ± 19.5 vs. FS 47.0 ± 17.7, P = 0.85), body mass index (TB 29.5 ± 6.6 vs. FS 29.3 ± 7.9, P = 0.86), diabetes (TB 13.1% vs. FS 10.0%, P = 0.65), smoking (TB 8.9% vs. FS 15.0%, P = 0.23), Charlson Comorbidity Index (TB 1.7 ± 2.3 vs. FS 1.6 ± 1.9, P = 0.72), and American Society of Anesthesiologists score (TB 1.9 ± 0.7 vs. FS 1.9 ± 0.7, P = 1.00). Changes in radiographic alignment differed between groups; however, these changes were not clinically significant. This included MCS (TB: -0.2 mm vs. BS: -0.7 mm, P = 0.0047), SCS (TB: -0.6 mm vs. BS: -1.3 mm, P = 0.0002), and TFCS (TB: +0.5 mm vs. BS: -0.5 mp = 0.0065).
Conclusions:
Patients with BM-equivalent injuries treated with fibular fixation alone demonstrated outcomes comparable with those with BM fractures treated with fibular and/or medial malleolar fixation. In lateral malleolus fractures with medial deltoid injury, deltoid repair had not seemed necessary to restore normal alignment and radiographic outcomes. FS and TB plates both maintained alignment.
Level Of Evidence:
Prognostic, Level III. See Instructions for Authors for a complete description of levels of evidence.
