[Effect of extended release of posterior clearance on flexion clearence and range of motion of the knee in total knee arthroplasty].

Objective: To observe the change of clearance and range of joint improved situation during total knee arthroplasty (TKA) by operating extended release manipulation of the posterior knee clearance.

Methods: A total of 120 patients with knee osteoarthritis undergoing unilateral TKA from March 2010 to March 2012 were equally randomized prospectively assigned to the experimental group and control group, each 60 cases. There were 46 male and 74 female patients, the mean age was 63.6 years (range from 49 to 75 years). After the osteotomy of the tibia and the femoral condyle and before the release of soft tissue intraoperation, patients in experimental group were taken the extended release manipulation of the posterior knee clearence while the control group were cleaned the osteophyte of the posterior condyle only, 2-sided paired t test was used to compare the clearence intraoperation and the time to flexion angle of 90° and 120° and the maximum angle after 3 months' follow-up.

Results: There was no significant difference of the index between the experimental group and control group (P > 0.05). Between experimental group and control group, the difference was significant in extention clearance ((18.9 ± 1.5) mm vs. (17.9 ± 1.6) mm, t = 3.53, P < 0.01) intraoperation, and no significant difference in flexion clearance ((20.7 ± 1.8) mm vs. (20.2 ± 1.9) mm, t = 1.48, P > 0.05). It took longer time for the knee flexion range of motion to 90°(t = 10.2399, P < 0.01) or 120°(t = 11.142, P < 0.01) of the control group than that of the experimental group, and the difference of the maximum range of motion between experimental group and control group was significant statistically at the 3-months follow-up (t = 4.4255, P < 0.01). All the patients were followed up for 3 - 24 months, average of 14.6 months, no femoral component loosening happened.

Conclusions: Extended release of the posterior knee clearance benefits the knee extension clearence intraoperation and functional exercise of range of motion postoperation, while it is no meaning to the flexion clearence.