SLR - March 2020 - Mira Pandya

Step Activity After Surgical Treatment of Ankle Arthritis

Reference: Shofer JB, Ledoux WR, Orendurff MS, Hansen ST, Davitt J, Anderson JG, Bohay D, Coetzee JC, Houghton M, Norvell DC, Sangeorzan BJ. Step Activity After Surgical Treatment of Ankle Arthritis. J Bone Joint Surg Am. 2019 Jul 3; 101(13): 1177-1184.  

Scientific Literature Review

Reviewed By: Mira Pandya, DPM
Residency Program: MedStar Georgetown University Hospital – Washington, DC

Podiatric Relevance: Ankle arthritis is a debilitating pathology that can significantly affect a patient’s daily life. When considering surgical treatments such as ankle arthrodesis or arthroplasty, a common question asked by patients may include which procedure allows for greater postoperative activity and a timeline for return to function. This study measured the changes in step activity from preoperative baseline to assess improvement in function, whether effectiveness differed by procedure type, and if step activity was associated with patient reported outcome measures (PROM) in patients after ankle arthrodesis or arthroplasty.

Methods: Two hundred seventy-three patients with ankle arthritis were enrolled from 2006-2011 in a prospective patient-preference study comparing ankle arthrodesis (AD) or arthroplasty (AP); there were 103 and 170 patients in both groups, respectively. All participants wore a step activity monitor (SAM) preoperatively and at six, 12, 24 and 36 months postoperatively for two-week intervals. Baseline steps per day and per-day metrics of low, medium and high-activity step counts, Sustained Activity Index 60 (max number of steps in one hour) and Peak Activity Index (mean step rate for 30 minutes) were recorded. Step activity was compared with each subject’s PROM as reported on the Musculoskeletal Function Assessment (MFA) and the Short-Form 36 (SF-36) physical function and bodily pain subscales. Linear mixed-effects regression analysis was used to test for improvement in step activity and association between MFA or SF-36 and total steps, with fixed covariates of age/gender/BMI and study visit/surgical procedure/age/gender/BMI for each treatment group, respectively.
Results: Two hundred thirty-four out of 273 patients were available for analysis. There was no significant difference in SAM measurements and PROM by surgical procedure, nor at any individual follow-up time. Both groups showed significant mean improvement (11 percent) in step totals from 12 months to 36 months postoperatively, with high-activity step counts showing the greatest increase (46 percent). At six months, there was a mean high activity step improvement for the AP group, compared to a decline in the AD, however by 36 months postoperatively, this difference was no longer present. An increase of 1000 total steps within a patient was associated with a mean change in the MFA, SF-36 physical function, and SF-36 bodily pain scores. The trajectory of step total continued to increase up to 36 months, however PROMs showed improvement at six months and plateaued after one year.

Conclusions: This study found that although there is a slower improvement initially for patients receiving arthrodesis compared to arthroplasty, there is no significant difference in long term high-activity step count at 36 months. Step counts continued to improve to 36 months, however PROMs leveled off at six months. Currently, there is no definitive consensus regarding these two surgical treatment options, and studies are frequently based on physician and patient reported measures, as well as proprietary measures. Utilizing a wearable device to evaluate pre-and-postoperative activity level allows for unbiased, objective data that a foot and ankle surgeon can provide to their patient. A limitation of this study included noncompliance in wearing the SAM, thus some activity may not have been recorded.

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