Soft-tissue balancing navigation used in total knee arthroplasty for the varus knee

Abstract

Objective To use soft-tissue balancing navigation for real-time quantitative observation of medial soft-tissue releasing in total knee arthroplasty (TKA) for the varus knee. Methods From October 2006 through September 2010,25 patients with knee osteoarthritis plus knee varus received TKA under soft-tissue balancing navigation.The soft-tissue balancing navigation system was used in the knee after routine bone cutting.The soft tissue stresses and balancing status observed and documented before and during the releasing under the guidance of the navigation system.Clinical outcomes were followed up. Results In this series,the mean operating time was 62 minutes (from 48 to 80 minutes) and the mean intraoperative blood loss was 320 mL ( from 100 to 500 mL).An average follow-up of 36.4 months (from 12 to 54 months)revealed no revision due to infection or loosening.The mean HSS scores were imuproved significantly from preoperative 53.4 ± 12.8 to 89.2 ± 17.3 at the last follow-up( t =17.411,P =0.000 ).The alignment of the lower limb decreased significantly from preoperative varus of 16.4°± 10.0° to postopcrative varus of 1.8° ± 2.1°(t=7.526,P=0.000).The differences in the medial and lateral stresses of the soft tissue at the knee extension and flexion were significant between pre-releasing and post-releasing ( P ＜ 0.05).In releasing the posterior portion of medial collateral ligament (MCL),the decreasc in medial and lateral stresses at the knee extension (42.33％ ± 20.88％ ) was significantly greater than that at the knee flexion ( 12.33％ ± 9.75％ ) ( t =6.714,P =0.000).In releasing both the anterior and posterior portions of MCL.the decrease in medial and lateral stresses at the knee extension (50.33％ ± 18.82％ ) was significantly smaller than that at the knee flexion (59.42％ ± 21.46％ ) ( t =2.492,p =0.021 ). Conclusion The soft-tissue balancing uavigation system is capable of real-time quantitative measurement of the soft tissue stress and balance in TKA for the varus knee. Key words: Osteoarhritis, knee; Surgcry, computer-assisted; Arthroplasty, replacement,knee; Soft tissue balamce