[Minimally invasive total knee arthroplasty through a quadriceps sparing approach: a comparative study].

OBJECTIVE: To evaluate the short term clinical results of minimally invasive total knee arthroplasty (MIS-TKA) through a quadriceps sparing (QS) approach compared with a standard TKA using a medial parapatellar exposure.

METHODS: Between March 2005 and March 2006, 26 consecutive unilateral primary MIS-TKA through a QS approach were performed. It was compared that the short term clinical results of this group with an age-matched and sex-match cohort of total knee arthroplasty done with a standard medial parapatellar approach. Length of incision, tourniquet time, blood loss, flexion degree, visual analog scale (VAS) score, Knee Society score, tibiofemoral angle and the ability to do a straight leg raising maneuver were evaluated respectively.

RESULTS: The mean follow-up time were 17 months (range 12-23 months). The average length of incision was (9.5+/-1.5) cm in the QS group and (14.0+/-2.3) cm in the standard group (P<0.05). Average tourniquet times were (83+/-16) minutes in the QS group and (55+/-11) minutes for the standard group (P<0.05). Postoperative tibiofemoral angles averaged (5.7+/-1.5) degrees valgus in the QS group knees and (6.0+/-1.4) degrees valgus in the standard group knees (P>0.05). The average VAS scores were significantly lower at the first, the third and the seventh postoperative days in the QS group compared with that of the standard group, and the difference was not significant after 6 weeks between two groups. Mean flexion at one week was greater for the QS group (107+/-12) degrees than that in the standard group (95+/-11) degrees. Improved ROM also was seen 6 and 12 weeks postoperatively in the QS group with significant difference. There were no differences in ROM between the two groups in 12 months. The ability to straight leg raised at one week postoperatively was better in the QS group (23/26, 88%) than that of the standard group (21/33, 64%). At the 6 weeks follow-up, the average knee score was (78+/-15) points in the QS group and (71+/-20) points for the standard group (P<0.05). Deep vein thrombosis were found in 1 case of the QS group and 3 cases for the standard group. One patient in the QS group developed superficial wound necrosis that healed uneventfully. There were no other complications such as deep infection, neurovascular injury and so on.

CONCLUSIONS: The MIS-TKA through a QS approach is associated with a more rapid functional recovery and improves range of motion. But higher specifications and more restrictive indications are of importance with the QS technique.