The most important finding of the present study was that 91% of patients aged ≥ 70 years returned to sports activities, and 77% of them could perform postoperatively at the same or higher level compared to the preoperative level. These results were not significantly different from the younger age group. However, the ratio of high-impact sports participants was significantly lower in the age ≥ 70 years group than in the age < 70 years group. Factors related to RTS at the same or higher level were the preoperative knee score and the preoperative Tegner activity scale.
Recent studies have focused on RTS after HTO. A systematic review and meta-analysis of 33 studies involving 1914 patients with a mean age of 50.3 ± 9.9 years showed that the rate of RTS after OWHTO was 75.7% (range, 55%-100%) . Another study investigating subjects with a mean age of 50 years demonstrated that the strongest prognostic factor for RTS was continued sports participation in the year before surgery (odds ratio, 2.81; 95% CI, 1.37–5.76) . A high RTS rate after OWHTO has been reported in the relatively younger generation, and few reports have examined in detail the RTS rates in elderly persons. The present study showed that age, sex, BMI, and knee alignment did not affect RTS rates and provided evidence of a high rate of RTS in elderly persons.
One of the factors related to RTS in elderly persons is thought to be the extent of surgical invasion and recovery time. Improvements of surgical techniques and fixation devices in OWHTO have enabled early recovery with full-weight bearing, accelerated postoperative rehabilitation, and minimized muscle weakness [12, 13]. Accelerated rehabilitation protocols for OWHTO were introduced and lead to earlier improvement of the clinical results [12, 14]. In elderly patients, recent accelerated postoperative rehabilitation programs seems to work in favor of preventing muscle weakness and increasing RTS.
Types of sports seem to differ among age groups and may affect RTS after HTO. Younger people have a demand for returning to relatively higher impact sports, such as running, baseball, and tennis, whereas older people have a demand for lower impact sports, such as walking, gymnastic training, and golf. The present study demonstrated a higher rate of low-impact sports participants in the age ≥ 70 years group. Although the return to high impact sports after OWHTO was high in the younger population , most patients return to sports activities with a trend toward performing lower-impact sports . Thus, one of the reasons for the high rate of RTS in elderly persons may be the high rate of preoperative participation in low-impact sports. In addition, since the preoperative Tegner activity scale score in the age ≥ 70 years group was relatively low, it may not be affected by HTO surgery, and it is easy for the patients to return to the same level postoperatively.
Arthroplasty is an alternative treatment option for knee OA in elderly patients. The indication for unicompartmental knee arthroplasty (UKA) is similar to that for HTO, and a high RTS rate of 75–100% has been reported [16–18]. These rates are almost equivalent to the return rate in the present study. However, there has been controversy over the studies of RTS directly comparing HTO and UKA. Jacquet et al. demonstrated quicker RTS with a higher rate of patients able to practice impact activity and better sports-related functional scores in HTO compared to UKA . In contrast, Kim et al. reported that UKA had better short-term functional outcomes and return to recreational and sports activities than did HTO in patients with medial OA . A systematic review and meta-analysis regarding RTS in elderly patients after UKA showed that higher return rates were observed for low-impact sports, whereas high-impact sports prevented a full return to activities . Since there are risks of femoral component loosening and polyethylene wear in UKA [21–23], RTS after both surgical procedures needs to be assessed by long-term follow-up.
This study has several limitations. First, there were many cases that were lost to follow-up. More than half of the patients were excluded from this study, which may have caused selection bias. Second, the follow-up period was short. It is unclear whether patients who return to sports after surgery maintain sports activities at the same level for a long time. Third, this study was a retrospective investigation.