Session IV - Foot & Ankle

Fri., 10/6/06 Foot & Ankle, Paper #24, 10:53 am

Does a Positive Ankle Stress Test Indicate Need for Operative Treatment?

Kenneth J. Koval, MD (n); Kenneth A Egol, MD (n);
Dartmouth Hitchcock Medical Center, Lebanon, New Hampshire, USA

Introduction: Historically, patients who present with an isolated lateral malleolus fracture with >4mm clear space widening on radiographic stress testing are deemed to have an unstable ankle and are advised to have surgery. However, this protocol may be associated with a high rate of false positive results, therefore subjecting people to surgery unnecessarily. At our institution, we have been using a standardized protocol employing MRI to evaluate ankle stability and need for surgery following a positive manual stress test for isolated lateral malleolus fractures. The purpose of this study was to evaluate the results using this standardized protocol.

Methods: Between December 2003 and June 2005, patients who had a positive ankle stress test (5 mm clear space widening) after Weber B (OTA Type 44-B) lateral malleolus fracture were further evaluated with use of MRI. If the MRI indicated the deep deltoid was completely disrupted, the patient was advised to have operative ankle repair. However, if the MRI demonstrated that the deep deltoid was intact or only partially disrupted, the patient was treated nonoperatively in a walking boot with weight bearing ambulation as tolerated. Patients were followed until fracture union and contacted at 6-month minimum follow-up to answer a functional questionnaire (SF-36) and return for clinical (AOFAS) and radiographic evaluation. Statistical analyses were performed to determine whether: (1) there was a relationship between the amount of clear space widening and MRI findings (eg, intact or partially torn deltoid ligament, degree or syndesmotic injury) and (2) there was a relationship between radiographic or MRI findings and clinical or radiographic outcomes.

Results: 21 patients had an MRI after a positive ankle stress test and comprised the study group. There were 12 men and 9 women with an average age of 27 years (range, 16-62). All patients had sustained the fracture as a result of a low-energy fall. Medial clear space on stress testing ranged from 5 to 8 mm. 19 of 21 patients (90%) had evidence of partially torn deep deltoid ligament and were treated nonoperatively, while 2 patients had MRI findings of a complete deep deltoid injury and underwent surgical treatment. These two patients had clear space measurements of 5 and 8 mm respectively. No ankle had evidence of complete syndesmotic tear on MRI. There was no correlation between the clear space measurement and MRI results. All 21 patients were doing well at latest follow-up (average 18 months) with AOFAS scores in the 90s and minimal complaints of ankle pain, stiffness, or reduced activity level compared to preinjury. All 21 fractures united without evidence of ankle incongruity on latest follow-up radiographs. No correlation was found between radiographic or MRI findings and clinical or radiographic outcomes.

Conclusion/Significance: Using our protocol, we were able to identify and provide effective nonoperative care to 19 patients who otherwise might have undergone operative treatment after isolated lateral malleolus fracture. Further work is needed to identify the subset of patients who could be treated nonoperatively without need for MRI scanning.

If noted, the author indicates something of value received. The codes are identified as a-research or institutional support; b-miscellaneous funding; c-royalties; d-stock options; e-consultant or employee; n-no conflicts disclosed, and *disclosure not available at time of printing.
· The FDA has not cleared this drug and/or medical device for the use described in this presentation (i.e., the drug or medical device is being discussed for an "off label" use). · · FDA information not available at time of printing.