Psychological readiness is associated with long-term joint awareness after isolated anterior cruciate ligament reconstruction: A within-patient comparison with the contralateral healthy knee.

PURPOSE: To compare long-term joint awareness between reconstructed and contralateral healthy knees following isolated anterior cruciate ligament reconstruction (ACLR) and to investigate the relationships among objective knee stability, psychological readiness and joint awareness.

METHODS: Patients who underwent isolated hamstring tendon autograft ACLR between January 2019 and March 2021 and had a minimum follow-up of 5 years were retrospectively reviewed. Patients with concomitant meniscal, chondral, multiligament, lateral extra-articular procedures or nonhamstring grafts were excluded. Joint awareness was assessed using the forgotten joint score-12 (FJS-12) for both reconstructed and contralateral healthy knees, and the primary within-patient interlimb comparison was based on FJS-12. Secondary outcomes included ACL-return to sport after injury (ACL-RSI), International Knee Documentation Committee (IKDC), Lysholm, visual analogue scale (VAS), Tegner Activity Scale, patient satisfaction and objective stability assessed using Lachman and pivot-shift tests. Multivariable regression and mediation analyses were performed.

RESULTS: Sixty-nine patients were included in the final analysis. At a mean follow-up of 68.5 ± 3.3 months, reconstructed knees demonstrated significantly lower FJS-12 scores than contralateral healthy knees (81.2 ± 6.4 vs. 90.1 ± 5.0; p < 0.001). Patients with residual instability showed significantly lower ACL-RSI, FJS-12, IKDC and Lysholm scores (all p < 0.001). ACL-RSI was strongly correlated with reconstructed-knee FJS-12 (rho = 0.786, p < 0.001) and independently predicted both reconstructed-knee FJS-12 (β = 0.833, p < 0.001) and interlimb FJS-12 differences (β = 0.668, p < 0.001). Mediation analysis identified a statistically significant indirect association between pivot-shift status and FJS-12 through ACL-RSI (95% bootstrap CI: -11.06 to -5.29).

CONCLUSION: Although isolated ACLR provided excellent long-term functional outcomes and restored objective stability in most patients, reconstructed knees remained perceptually inferior to contralateral healthy knees. Psychological readiness was strongly associated with long-term joint awareness. The observed associations suggest that psychological readiness may contribute to the relationship between residual rotational instability and impaired ability to achieve a 'forgotten knee'.

LEVEL OF EVIDENCE: Level III, retrospective comparative study.