Abstract: Objective To compare the effects of posterior cruciate ligament (PCL) resection vs. shallow medial collateral ligament (SMCL) releasing on joint gaps in the total knee arthroplasty (TKA) surgery. Methods From April 2013 to May 2014, there were 83 osteoarthritis patients with varus knee underwent unilateral TKA in our department. Patients were randomly divided into two groups, patients in group A underwent both PCL resection and SMCL releasing in surgery, while those in group B underwent only SMCL releasing. The joint gaps before and after surgical treatment and the related data were measured and analyzed. Results There were no statistical differences in extension gap and medial and lateral flexion gap between these two surgical treatments in group A (P> 0.05), while PCL resection increased medial and lateral flexion gap significantly(15.55±0.42) mm vs (16.88±0.53) mm, t=5.514, P=0.000; (19.58±0.53) mm vs. (20.60±0.63) mm, t=2.985, P=0.011. In group B, SMCL releasing showed significant differences on medial gap in both extension and flexion gaps(18.67±0.54) mm vs (19.53±0.53) mm, t=3.180, P=0.007; (15.62±0.68) mm vs (16.50±0.70) mm, t=3.705, P=0.002, but it showed no differences on lateral gap. The combination of PCL resection and SMCL releasing had more significant influence on range of gap opening than doing SMCL releasing alone in group B (t=3.949, P=0.002; t=5.687, P=0.000), while no significant difference was found in extension gap. Doing SMCL releasing after PCL resection in group A had more significant influence than doing SMCL releasing without PCL resection in group B on flexion gap (t=2.880, P=0.012; t=3.088, P=0.007) with no significant difference in extension gap. Conclusion PCL resection has influence on the balance of flexion and extension gap during TKA surgery, while SMCL releasing mainly has influence on the balance of medial and lateral gap, which suggests that whether using the combination of these two methods or one method alone depends on different situations during surgery.