【Abstract】 Objective To compare the two different techniques determining tibial rotational al ignment in total kneearthroplasty(TKA) to enhance postoperative effect and reduce compl ications. Methods From May 2006 to April 2007, 60 patients(27 males, 33 females, aged 55-78 years ) received TKA and randomly divided into 2 groups(n =30): tibial rotational al ignmentin TKA was determined by medical 1/3 of tibial tubercle in Group A, by medial border of tibial tubercle at 0-9°varus inGroup B, by medical 1/3 of tibial tubercle at 20°or greater varus or by the mean l ine between medial border of tibial tubercle andmedical 1/3 of tibial tubercle at 10-19°varus. The angle of rotation of polyethylene cushion was calculated. Results The angleof rotation of polyethylene cushion in Group A was (8.4±3.8)° at 0-9°varus, (3.5±2.7)° at 10-19°varus and (0 ±2.4)° at 20°varusor over, respectively, and there was significant difference (P lt; 0.05). The angle of rotation of polyethylene cushion in Group Bwas (0 ±2.1)° at 0-9° varus, (0 ±2.0)° at 10-19°varus and (0 ±1.7)° at 20°varus or over, respectively, and there was no significantdifference (P gt; 0.05). The angle of rotation of polyethylene cushion averaged (5.6±2.8)°in Group A and (0±1.9)° in Group B,showing significant difference (P lt; 0.05). Conclusion The range of ideal tibial rotational al ignment in TKA was from medialborder of the tibial tubercle to medical 1/3 of the tibial tubercle, and is decided by the degree of varus deformities and valgus deformities.