Returning to pre‐injury level of sports before 9 months after medial patellofemoral ligament reconstruction increases the incidence of anterior knee pain in young patients

PURPOSE: This study aimed to identify the risk factors for anterior knee pain (AKP) after medial patellofemoral ligament reconstruction (MPFLR). METHODS: Patients aged 15-35 years who underwent isolated MPFLR between 2012 and 2022 were included in the study. These patients were divided into two groups (AKP and control group). Patient demographics and preoperative and postoperative clinical outcomes between the two groups were assessed and compared. Univariate logistic regression analysis was performed to explore the potential risk factors associated with postoperative AKP. Subgroup analysis stratified the results based on the time to return to sports (RTS) (>9 and ≤9 months). Furthermore, Spearman correlation analysis was performed to investigate the association between Kujala score and time to RTS. RESULTS: A total of 206 patients were included (AKP, n = 59; control, n = 147). At the 2-year follow-up, patients with AKP demonstrated a shorter duration in returning to their pre-injury activity level compared to those without AKP (9.0 ± 3.6 vs. 10.3 ± 2.7 months, p < 0.05). RTS earlier than 9 months after MPFLR was the only significant risk factor associated with postoperative AKP (odds ratio, 2.13, 95% confidence interval, 1.03-4.39; p < 0.05). Further subgroup analysis revealed that patient RTS earlier than 9 months exhibited worse patient-reported outcomes in both the total cohort and control group (p < 0.05). Furthermore, among patient RTS within 9 months, a longer recovery duration before RTS strongly correlated with a higher Kujala score (R = 0.670, p < 0.001). CONCLUSIONS: Young patients who RTS at their pre-injury levels before 9 months after MPFLR have a higher incidence of postoperative AKP and poorer functional outcomes compared to those who delay their return. Specifically, within the first 9 months after MPFLR, the earlier the RTS, the more severe the AKP symptoms. Careful consideration of the timing for RTS may help reduce the incidence of postoperative AKP. LEVEL OF EVIDENCE: Level III.