PURPOSE: This study was performed to determine new criteria for performing lateral retinacular release (LRR) without having a detrimental effect on patellar tracking. MATERIALS AND METHODS: For 17 patients who underwent bilateral TKAs, LRR was not performed at one side (A) due to improvement of patellar tracking after deflation of tourniquet although maltracking existed with the inflation of tourniquet. At the other side (B), LRR was not performed either because patellar tracking improved with one stich method although maltracking existed regardless of tourniquet status. We measured the lateral patellar tilt angle (LPTA) of each side inthose 17 patients after 1 year after TKAs and compared them. We also surveyed the incidence of LRR in 225 primary TKAs with the staged method of patellar tracking evaluation during the same period. RESULTS: The average LPTA was 3.4degrees at side (A) and 4.6degrees at side (B) respectively. There was no significant difference in LPTA between side (A) and side (B) (p=0.337). From the survey for incidence of LRR in 225 primary TKAs during the same period, LRR was not required in 19% of patients showing good patellar tracking with inflation of tourniquet, 58% of patients showing improved patellar tracking after deflation of tourniquet and 21% of patients showing improved patellar tracking by one stitch method regardless of tourniquet status. Consequently, only 2% of patients required LRR in primary TKA. CONCLUSION: One stitch method under the deflation of tourniquet in evaluating process of patellar tracking during primary TKAs is supposed to be very effective and to reduce the incidence of LRR to only 2% without influencing the LPTA.