Summary
BCS-TKA showed no significant difference in AP joint displacement when compared with control knees and Oxford UKA knees. The BCS-TKA design is likely to reproduce native anterior cruciate ligament and posterior cruciate ligament function, and improve the AP joint stability in mid-flexion range.
Abstract
Introduction
Total knee arthroplasty (TKA) is reported to be an effective procedure for treating osteoarthritis of the knee that provides excellent pain relief and reliable long-term results. However, postoperative patient satisfaction is lower than that for total hip arthroplasty (THA), with 10%–20% of patients reportedly left dissatisfied after TKA. This may be because, although it is currently possible to choose between retaining the posterior cruciate ligament (PCL) or replacing it (cruciate-retaining or posterior cruciate-substituting surgery), the anterior cruciate ligament (ACL) must always be resected, meaning that ACL dysfunction is present in all post-TKA knees. As a result, conventional TKA cannot normally achieve kinematics or function equivalent to that of a healthy knee, and ACL defects may also cause abnormal tibiofemoral positioning and anterior knee laxity. This may lead to postoperative knee dysfunction, reducing patient satisfaction. Bi-Cruciate Substituting (BCS) TKA has a cam-post structure designed to possess the functions of both the ACL and the PCL, reproducing the kinematics, function, and stability of a healthy knee. Several studies have reported that it shows similar knee kinematics in BCS-TKA as in normal knee function and favorable clinical results. However, no study has yet addressed the question of anteroposterior (AP) joint displacement. The aim of this study is to compare the AP joint displacement between a n BCS-TKA and cruciate-retaining Oxford unicompartmental knee arthroplasty (UKA) and PCL-retaining (CR) TKA and PCL-substituting (PS) TKA.
Materials And Methods
In this study, 114 subjects (160 knees) undergoing BCS-TKA (Journey II: Smith and Nephew) and 72 subjects (89 knees) undergoing Oxford UKA (Zimmer-Biomet holdings, Inc., IN) and 73 subjects (93 knees) undergoing CR-TKA (FNK: Teijin Nakashima Medical, Okayama, Japan) and 48 subjects (63 knees) undergoing PS-TKA (FNK: Teijin Nakashima Medical, Okayama, Japan) were included. AP joint displacement was measured using the KT-1000 arthrometer (Medmetric, San Diego, CA, USA), at 30 in flexion. An anterior force of 67N, 133 N, manual maximum was applied. As a control, the asymptomatic contralateral knees of subjects undergoing Oxford UKA were evaluated (53 knees).
Results
AP joint displacements (mm) at anterior force of(67N/134N/MAX)in 30 in flexion were (4.3/6.7/10.6)in the BCS-TKA, (6.3/9.2/14.3)in CR-TKA, (4.8/7.2/12.2)in PS-TKA, (3.9/6.0/9.8)in the Oxford UKA, and (4.0/6.1/9.4)in the control knees. No significant difference in AP joint displacements was observed among the BCS-TKA and UKA and control groups. And there was significant difference between BCS-TKA and CR- TKA, BCS-TKA and PS-TKA.
Conclusions
BCS-TKA showed no significant difference in AP joint displacement when compared with control knees and Oxford UKA knees. The BCS-TKA design is likely to reproduce native anterior cruciate ligament and posterior cruciate ligament function, and improve the AP joint stability in mid-flexion range.