Long term quadriceps strength defictis have been reported after a TKA performed with a quadriceps splitting approach. Will an MIS-TKA performed with a mini midvastus approach significantly improve long term quadriceps strength retention?

147 subjects were chosen in a retrospective manner for this study. 52 MIS-TKA, 48 quadriceps splitting TKA, and 47 controls with normal knees and no prior surgery. All groups were age and gender matched. All knees were tested more than 1 year after the index operation on a Cybex isokinetic dynamometer. All surgeries were performed by the author.

The average Knee Society knee score for the MIS-TKA group was 94.3 and the average age was 71. The quadriceps splitting group had an average knee score of 95.7 and an average age of 72. The control group had an average age of 70. All groups averaged 38% male and 62% female. At 30 degrees from full extension the MIS-TKA group retained 96.6% of the control group strength and the quadriceps splitting group 94.5%. At 15 degrees from full extension the MIS-TKA group improved to 99.7% while the quadriceps splitting group fell to 85% of the control group strength.

MIS TKA with a mini midvastus approach preserves terminal quadriceps strength better than a standard quadriceps splitting approach.