Return to sport at the pre-injury level following anterior cruciate ligament reconstruction is influenced by patients' perceived knee status and psychological readiness, and does not correlate with functional ability

Objectives: The purposes of this study were to (1) prospectively evaluate clinical and functional outcomes of athletes following anterior cruciate ligament (ACL) reconstruction up to 12 months after surgery, (2) to identify the correlations between functional and subjective tests, and (3) to determine which factors influence patients' capability to resume sports at pre-injury level. Methods: Patients who underwent ACL reconstruction using doubled autologous hamstring graft were prospectively assessed pre-operatively, 6, and 12 months after surgery using International Knee Documentation Committee (IKDC) Subjective Knee Form, Tegner activity level, and ACL-Return to Sport after Injury (ACL-RSI) scale. Jumping ability was instrumentally assessed using a test battery including bipodalic squat jump (SJ), bipodalic countermovement jump (CMJ), monopodalic CMJ, and monopodalic side-hop test. Results: Thirty-three patients were available for clinical evaluation at 12-months follow-up. Average age was 34.0 years (SD 11.5, range 19-50). Male/female ratio was 31:2. Mean overall IKDC, and ACL-RSI scores increased from 52.5 to 47.1 preoperatively, to 89.9 (SD: 12.2, range 36.8-100) and 81.3 (SD 21.7, range 10-98.3), respectively at last followup (p < 0.001). Monopodalic jump tests showed improvements at 12-month evaluation compared to 6-month followup (p < 0.01). No statistically significant correlation was reported for ACL-RSI and jump limb symmetry index (LSI) (p = 0.08 vs. CMJ; p = 0.07 vs. side-hop test). No differences were observed in terms of jump LSI between patients who returned to pre-injury activity level and those who did not (p = 0.11 for CMJ, p = 0.09 for side-hop test). A significantly higher IKDC score at 6 months was observed in patients who did not return to pre-injury levels (p = 0.009). Patients who did not return to pre-injury activity reported lower ACL-RSI scores at 12-months follow-up (p = 0.007). Conclusions: One year after ACL reconstruction, an improvement in jumping ability was observed, while a persistence of lower limbs asymmetries when performing jump tests was noted at 6-months follow-up. The ability to perform vertical jumps was not influenced by psychological outcomes 12 months following surgery. Higher values of subjective knee score and psychological readiness weakly correlated to return to sport at preinjury level, while no correlation was reported concerning jumping performance.