We investigated acetabular dysplasia patients’ participation in sports activities before and after CPO, and compared patients who participated and did not participate in sports activities post-operatively. Patients who participated in sports activities post-operatively were allowed to return to FWB earlier than those who did not. To our knowledge, this is the first study on the sports activities of patients with acetabular dysplasia who have undergone CPO. Our results will help medical staff ascertain the likelihood that patients with acetabular dysplasia will be able to participate in sports activities after CPO.
In this study, the pre- and post-operative sports activity participation rates of acetabular dysplasia patients who underwent CPO were 55.8% and 72.1%, respectively, versus 31.1% and 55.3% in patients who underwent PAO, respectively . Patients who underwent CPO had significantly higher pre- and post-operative sports activity participation rates than patients who underwent PAO (P = 0.047 and = 0.003, respectively). Although these results suggest that CPO might increase post-operative sports activity participation relative to PAO, the pre-operative participation rates were substantially different between studies. Therefore, future studies are required to compare sports activity participation rates after CPO and other osteotomies, such as rotational acetabular osteotomy and PAO, in patients with similar baseline sports activities participation.
Compared to PAO, CPO is less invasive and can create better contact between bone surfaces, resulting in stable fixation and tight bonding . Because early post-operative rehabilitation is possible with CPO, early physical function can be improved. Thus, patients with improved physical function are more willing or able to maintain or improve physical function, resulting in higher sports activity participation. This is corroborated by patients’ self-reported reasons for participating in sports activities (Fig. 2). Furthermore, activity level and satisfaction are reported to be correlated in patients with hip disease . In this study, 74.1% of patients were satisfied with daily life, suggesting that high satisfaction might positively affect sports activity participation. Therefore, medical staff can use the results of this study to provide guidance to patients who want to participate in sports activities after CPO.
Patients participated in sports activities ranging from low to high impact, with the latter being performed less frequently; this trend is similar to previous reports on sports activities before and after total hip arthroplasty  or PAO . Many low-impact sports activities are safe for patients to do alone and do not require higher physical functioning in comparison to high-impact sports activities. In addition, post-operative participation in sports activities is reported to be unrelated to OA progression regardless of sports activity impact . Therefore, clinicians can recommend that patients who have undergone CPO participate in low-impact sports activities post-operatively. Meanwhile, a few patients in this study participated in high-impact sports activities. As such activities require high physical functioning, most patients likely refrained from participating in them owing to concerns of deterioration of physical condition, such as OA progression. However, Hara et al. report that among 162 acetabular dysplasia patients, participation in high-impact sports activities after PAO did not significantly influence the progression of OA grade . Because CPO is a modified PAO , it is expected to yield the same prognosis as PAO. Hence, some patients participate in high-impact sports activities after CPO or PAO. Therefore, clinicians should support patients who wish to participate in high-impact sports activities with careful follow-up, such as confirmation of OA grade.
The main reasons for not participating in sports activities post-operatively were lack of time and pain. The oldest patient in this study was 62 years. The retirement age in many workplaces in Japan is 65 years. Therefore, given that most patients in this study were younger, many might have had limited time for sports activities because of work. In addition, fear of pain or hip damage hinders post-operative participation in sports activities . Therefore, clinicians should provide patients appropriate guidance for participating in sports activities after obtaining informed consent. Moreover, from the viewpoint of extending healthy life expectancy, it is preferable to advise low-impact sports activities such as walking and cycling. Accordingly, clinicians should avoid giving all patients uniform guidance regarding exercise and instead give individualised guidance, because patients who have undergone CPO might only be able to perform limited sports activities owing to living environment-related or psychological reasons.
In this study, patients who participated in sports activities had a smaller pre-operative hip flexion range of motion than those who did not participate in sports activities. Patients with acetabular dysplasia typically have increased hip flexion, which is reduced by PAO . In other words, patients who participated in sports activities after CPO in this study likely had a smaller flexion angle compared to those who did not participate. Therefore, patients with acetabular dysplasia might be able to participate in post-operative sports activities if they have close-to-smaller hip flexion. In addition, FWB was allowed earlier among patients who participated in sports activities than those who did not, likely because early recovery of muscle strength is associated with early permission for FWB after osteotomy . However, given that allowing FWB when bone fusion is insufficient increases the risk of fracture , safety must be prioritised over allowing FWB at an early stage regardless of individual characteristics.
One limitation of our study is its retrospective design using a self-reported questionnaire. Although recall bias might have influenced the results, the recall period was limited to three years pre-operatively to minimise such bias. Another limitation is lack of data, specifically post-operative physical function assessments. Although we examined pre-operative physical function and post-operative sports activity, if patients had a certain level of pre-operative physical function, pre-operative physical function might not significantly affect post-operative participation in sports activities. Therefore, further studies examining the effects of post-operative physical function and sports activity participation are needed. Another limitation is the small sample size: few patients were eligible for CPO, especially considering the five-year study period. Therefore, multivariate analysis could not be performed.