Effect of early compared with late weightbearing on the outcomes of subtalar joint arthrodesis

Aims: Although end-stage osteoarthritis (OA) of the subtalar joint is routinely managed surgically with arthrodesis, postoperative weightbearing regimens vary widely from immediate weightbearing through to prolonged (≥ six weeks) non-weightbearing. It has been assumed that immediate weightbearing may compromise the rate of union and be associated with an increased rate of complications, but these concerns have not been substantiated. This systematic review and meta-analysis of single proportions aimed to assess the effect of early compared with late weightbearing regimens on the outcomes after isolated elective subtalar arthrodesis. Methods: All studies reporting on isolated elective subtalar arthrodesis for primary OA, post-traumatic arthritis, inflammatory arthritis, coalition, or planovalgus/cavovarus deformity correction were identified from MEDLINE, Embase, or Cochrane CENTRAL databases from inception to July 2024. Risk of bias was assessed with the MINORS tool. No direct comparative studies comparing weightbearing regimens were identified. A meta-analysis of single proportions was performed to generate a pooled proportion of the outcomes of interest, with early (≤ two weeks), intermediate (two to six weeks), and late (≥ six weeks) weightbearing regimens used to stratify the results. Results: A total of 32 studies reporting on 1,629 subtalar arthrodeses were included; four studies had early weightbearing regimens, three were intermediate weightbearing, and 25 reported outcomes from delayed weightbearing regimens. The overall rates of union were 95% (95% CI 92 to 97) with no difference between the regimens. Rates of wound complications, infection, and removal of metalwork were also not grossly different between the weightbearing regimens. Conclusion: Early weightbearing (≤ two weeks after isolated primary subtalar arthrodesis) is not associated with any deleterious effects on union, infection rates, or wound complications. This study also identified that there is a paucity of evidence regarding the impact of early compared with late weightbearing on outcomes after subtalar arthrodesis, and is limited by the quality of the studies available for this meta-analysis of single proportions.