SLR - October 2023 - Varney
Title: Concomitant Unstable and Stable Gravity Stress Tests on Weight-Bearing Stable Weber B Ankle Fractures Treated Nonoperatively: A 2-Year Outcome StudyReference: Gregersen MG, Robinson HS, Molund M. Concomitant Unstable and Stable Gravity Stress Tests on Weight-Bearing Stable Weber B Ankle Fractures Treated Nonoperatively: A 2-Year Outcome Study [published online ahead of print, 2023 Jul 27]. J Bone Joint Surg Am. 2023;10.2106/JBJS.23.00195.
Level of Evidence: II
Reviewed By: Rebecca Varney, DPM
Residency Program: Inova Fairfax Medical Campus, Fair Oaks, VA
Podiatric Relevance:
Operative intervention for isolated Weber B ankle fractures has been recommended if the fracture is unstable due to a concomitant deltoid ligament injury. Weight bearing stress and gravity stress radiographs are alternative methods for evaluating deltoid ligament integrity, however instability is indicated in up to 3% of weight bearing films vs. 48% of gravity stress films. It has been proposed that this difference is due to a superficial vs. deep deltoid rupture. The authors hypothesized that there would be no outcome difference between ankles with stable or unstable gravity stress radiographs if the weight bearing radiograph indicated stability.
Methods:
Patients aged 18-80 years old who suffered an isolated Weber B ankle fracture with a medial clear space (MCS) of <7.0 mm were prospectively enrolled. Patients remained non-weight-bearing (NWB) in a below knee cast for 3-7 days post-injury until stability examination. To assess stability, the cast was removed and weight bearing and gravity stress x-rays were performed. The fractures were then stratified according to the MCS measurements. If the MCS remained <5.0mm on both weight bearing and gravity stress films, the fracture was classified as a Lauge-Hansen SER2. If MCS remained <5.0mm on weight bearing films, but was increased on gravity stress, the fracture was classified as an SER4a (superficial deltoid insufficiency). If MCS was >5.0mm on weight bearing films, the fracture was classified as an SER4b (deep deltoid insufficiency), treated operatively, and excluded from the study. All SER2 and SER4a patients were subsequently weight bearing as tolerated with a functional ankle brace. Range of motion exercises without the brace were encouraged. Follow-up visits were conducted at 2, 6, and 12 weeks and 1 and 2 years post-injury. Outcome measures included the Manchester-Oxford Foot and Ankle Questionnaire (MOXFQ), Olerud-Molander Ankle Score (OMAS), and radiographic congruity and MCS.
Results:
One-hundred forty-nine patients patients were enrolled with SER2 n=88 and SER4a n=61. The mean age was 50 ± 15 years. At 2-year follow up, the patient reported outcome scores of SER4a fractures (MOXFQ 3±9, OMAS 97±10) were not inferior to those of SER2 (MOXFQ 2±4, OMAS 97±26). The mean between group difference in MCS at 2-year follow up was -0.1mm (95% CI, -0.3 to 0.1mm; p=0.311) and consistent with equivalence.
Conclusions:
The results of this study are consistent with those in previous studies that have demonstrated satisfactory patient reported outcomes and radiographic outcomes following non-operative management of weight-bearing stable Weber B fractures (SER2 and SER4a). In this prospective, non-inferiority study, an unstable stress gravity view did not result in a worse outcome in patients who were stable on weight-bearing films. This finding indicates that gravity stress views in a weight-bearing stable Weber B fracture may be redundant and unnecessary for surgical planning. Considering that SER4a patients would have traditionally been treated operatively due to gravity stress instability, the results of this study may result in decreased operative intervention and therefore a reduced risk of complications associated with surgery without sacrificing patient outcomes.