The most important aim of TAA is to provide an improved and pain relieved ankle joint. Differences of operative outcomes for TAA between men and women could be expected, since there are differences in bone mineral density (BMD), the prevalence of generalized joint laxity, physical activity, and anatomic variations including alignment of lower extremity and bone size between the genders.[24, 34–38] Thus, the primary purpose of this study was to compare the intermediate-term outcomes of TAA depending on gender difference. In this study, primary outcomes were greatly improved in both groups, but we did not find differences with most patient-reported outcomes, complication rates, and survivorship between the two groups. Consequently, those differences between men and women would not be considered as an affecting factor in the clinical outcomes.
Interestingly, unlike other clinical scores, SF-36 is more likely to have a higher score in men than women. Several studies have demonstrated outcome comparisons between men and women for SF-36 scores of the hip and knee.[23, 25] Cherian et al. analyzed 272 consecutive total knee arthroplasty and reported that the SF-36 PCS was significantly better in men at 7 years of follow-up.[25] Khashan et al. suggested that gender-related analysis resulted in significantly higher scores for men compared to women in SF-36 scores for hip osteoarthritis patients.[23] In regard to knee or hip, men have been reported to score significantly better in the SF-36 test. The activities of daily life have been extensively examined and some studies have reported that men were more tolerant of functional recovery and pain relief, while women on the other hand, tended to perceive their function and pain as more restrictive than they actually were.[22, 39]
In terms of radiographic data, the preoperative tibiotalar angles were worse for women than men (Table 3). Since there was a significant difference with tibiotalar angles between men and women before surgery, this was considered to be significantly improved by the process of intra-operative correction. Lee et al. reported that, regardless of preoperative deformity type or degree, if the tibiotalar angle of the ankle was corrected with any ligament imbalance or hindfoot deformity through an additional procedure, the TAA showed good outcomes.[19]
The survivorship rate was not significantly different between men and women at a mean follow-up of 7.5 years (96.4% and 93.4%, respectively)(p = 0.621) (Fig. 2). Gender had minimal effect on survival rates in TAA, perhaps attributable to the fact that there were no significant differences between the mean age at surgery (p = 0.114) or failure rates (p = 0.752) between men and women.
In our data, although not statistically significant, prevalence of osteolysis and its complication was higher in women (16 cases, 18.6%) than in men (10 cases, 9.2%) (Table 4). Men and women are known to have a difference in BMD due to multiple factors including hormonal differences, and we thought these differences may be associated with development of osteolysis with aseptic loosening. Morakis et al. reported that aseptic loosening was associated with a significant decrease of cortical bone and trabecular bone volumetric-BMD.[40] Runolfsdottir et al. suggested that women had lower BMD than men, and a greater increase in BMD reductions with decreasing female hormones.[41] In other words, the BMD difference between men and women suggests that women are more likely to develop aseptic loosening than men. However, gender was not a risk factor or prognostic factor for revision by aseptic loosening in total knee arthroplasty.[42] Therefore, further studies on the relationship between the prevalence of osteolysis with aseptic loosening and bone mineral density are needed.
There were several strengths and weaknesses of our study. Furthermore, a single surgeon performed all TAA using the same prosthesis and underwent a similar rehabilitation treatment. Second, all data were prospectively collected and added to this study. However, there were some limitations. First, the overall mean follow-up duration was 7.5 years. This might not be long enough to include late complications. Second, the sample size of the two groups was relatively small to detect a difference on this general subject. This might have limited our ability to evaluate the influence of baseline and perioperative characteristics on the outcomes of interest. Finally, this study did not further evaluate objective indicators such as BMD, generalized joint laxity, and whole lower extremity alignment.