Is There a Significant Relationship Between Tibiotalar Joint Space and Ankle Function Following Ankle Surgery?
Authors: Mullens Jess , Clanton Thomas , Daney Blake , Matheny Lauren 
Published: September 2018

Category: Ankle Arthritis Introduction/Purpose: The ankle joint is unique in epidemiological, anatomic, and biomechanical characteristics compared to other lower extremity joints. While primary hip and knee arthritis is common, approximately 70% of ankle arthritis is generally a result of another initiating event or underlying pathologic process. Post-traumatic arthritis is the most common indication for ankle arthrodesis and total ankle replacement. Few studies have documented the relationship between preoperative tibiotalar joint space and outcomes. Understanding this relationship may aid in preoperative patient counseling of expectations, and proper patient selection. The purpose of this study was to determine whether patients with narrow joint space (<2.0 mm vs. > 2.0 mm) preoperatively had inferior outcomes, as measured by the Foot and Ankle Ability Measure (FAAM) score, at a postoperative minimum of two years. Methods: All patients who underwent ankle surgery and a preoperative ankle radiograph were included in this study. Radiographic measurements were taken on an ankle mortise film with appropriate magnification conversions. Medial, central, and lateral measurements were completed for each patient. Of the three measurements, the lowest value was used for analysis. Patients completed a subjective questionnaire at minimum of two years following ankle surgery, which included the FAAM Activities of Daily Living (ADL) and Sport scales. All data were collected prospectively and stored in a data registry. The FAAM ADL and sport scores were compared between joint space cohorts (<2.0 mm vs. >2.0 mm) using an independent t-test. Correlations between the FAAM ADL and Sport scores and joint space were conducted using Pearson correlation coefficient. Results: There were 251 patients (145 males, 106 females) with an average age of 44.4 years included in this study. Average joint space in the <2.0 mm cohort was 0.60 mm (range 0–1.9) and 3.2 mm (range 2.0–5.3) in the >2 mm cohort. Average follow-up was 3.8 years (range 2.0–7.4). There was a significant difference in FAAM ADL and Sport scores between cohorts. Average FAAM ADL for the <2 mm cohort was 77 (37–100) and 86 (range 1–100) for the >2 mm cohort(p<.001). Average FAAM Sport for the <2 mm cohort was 43 (range 3–100) and 68 (range 0–100) for the >2 mm cohort(p<.001). There was a significant positive correlation between joint space millimeters and the FAAM ADL (?=.166, p=.009) and the FAAM Sport (?=.308, p<.001). Conclusion: It is important to counsel patients regarding their future outcome when discussing surgical procedures. Ankle radiographs are routinely performed in the clinical setting and allow quick interpretation compared to other advanced imaging modalities. In our study, patients who had joint space less than 2 mm had significantly lower ankle function as indicated by the FAAM ADL and Sport scores. There was a significant positive relationship between joint space and function. While a decreased joint space should not exclude a patient from obtaining relief from a surgical procedure, patients should be well educated on what to expect given their radiologic joint space.