Purpose of study: The purpose of the study was to determine the influence of patient’s pre-operative mental state on post-operative physical outcomes in primary and revision total knee arthroplasty (TKA).

Methods: 100 Primary and 60 Revision TKA patients were prospectively assessed using SF-12 and WOMAC outcome measures. They were assessed pre-operatively and at six and twelve months post-operatively.

All surgery was performed by a single surgeon, using one prosthesis design in each group.

The data were assessed for any correlation between the pre-operative MCS and post-operative PCS, Pain, Stiffness and Function scores using Spearman’s Rank Correlation.

Results: There was a significant positive correlation between pre-operative MCS and post-operative PCS scores at six and twelve months (P=0.01 and P=0.031 respectively) in the primary TKA patients. There was no correlation in the revision patients.

There was a statistically significant negative correlation between pre-operative MCS and six month WOMAC Pain, Stiffness and Function scores (P=0.025, P=0.019 and P=0.011 respectively) in the primary patients. There was no significant correlation with twelve months WOMAC scores.

There was no significant correlation in terms of pre-operative MCS and six months WOMAC scores in the revision patients, but there was a statistically significant negative correlation between pre-operative MCS and the twelve months pain score (P=0.039).

Conclusion: The results support the concept that high generic mental health scores in patients prior to primary TKA are associated with good physical outcomes in terms of both generic health outcome measures and disease-specific outcome measures.