A New Technique Determining Tibial Rotational Alignment In Total Knee Arthroplasty

Objective:Total knee arthroplasty has been applied clinically and achieved satisfactory effect,but recently the high rate of complications of patellofemoral joint and its results of premature wear and loose of prosthesis are still troublesome. Malalignment between femoral and tibial is an very important reason.It has been researched that surgical transepicondylar axis is the reliable marker determining femoral rotational alignment.But the reliable marker determining tibial rotational alignment has not been unified.Recently some scholars prefer that the range of ideal tibial rotational alignment in TKA was from medial border of the tibial tubercle to medical 1/3 of the tibial tubercle,and is decided by the degree of varus deformities and valgus deformities.The author designed the prospective clinical trail to compare traditional and improved method by observing and measuring in the operation to enhance the postoperative effect and reduce complications.Methods:From May 2006 to May 2007,60 patients with osteoarthritis, rheumatoid or traumatic arthritis(27 males,33females,aged 55～78years,)performed with TKA were randomly divided into 2 groups,30 patients in each:tibial rotational alignment in TKA in group A was determined by medical 1/3 of tibial tubercle;tibial rotational alignment in TKA in group B was determined by medial border of tibial tubercle if 0～9°varus,by medical 1/3 of tibial tubercle if 20°or greater varus or by the mean line between medial border of tibial tubercle and medical 1/3 of tibial tubercle if 10～19°varus.Calculate the angle of rotation of polyethylene cushion.The data was analyzed by SPSS11.5 and expressed by mean±standard deviation.Analysis of variance was adopted in inter-group comparison.Group comparision adopted Student's test.When P＜0.05 there was statistical significance.Results:The angle of rotation of polyethylene cushion in group A was 8.4±3.8°if 0～9°varus,3.5±2.7°if 10～19°varus and 0.0±2.4°if 20°or greater varus, respectively,and there was significant difference(P＜0.05).The angle of rotation of polyethylene cushion in group B was 0.0±2.1°if 0～9°varus,0.0±2.0°if 10～19°varus and 0.0±1.7°if 20°or greater varus,respectively,and there was no significant difference(P＞0.05).The angle of rotation of polyethylene cushion in group A averaged 5.6±2.8°,in group B averaged 0±1.9°,and there was significant difference (P＜0.05).Conclusion:Choosing the range from medial border of the tibial tubercle to medical 1/3 of the tibial tubercle,decided by the degree of varus deformities and valgus deformities,to determine the rotational alignment of the tibial component will create optimal tibiofemoral rotational alignment.Tibial rotational alignment in TKA should be determined by medial border of tibial tubercle if 0～9°varus,by medical 1/3 of tibial tubercle if 20°or greater varus or by the mean line between medial border of tibial tubercle and medical 1/3 of tibial tubercle if 10～19°varus.