Purpose. This study was to investigate the effect of posterior tibial slope (PTS) on the kinematics in the cruciate-retaining total knee arthroplasty (CR-TKA) using 2- to 3- dimensional registration technique. Material & Methods. A total of 75 knees in 58 patients were recruited and categorized into the following two groups according to PTS. Group A was categorized PTS under 7degrees (n = 33) and group B was categorized PTS over 7 degrees (n = 42). The average age of group A and group B at the time of fluoroscopic surveillance date was 73.5 ± 7.4 years and 74.3 ± 4.5 years, respectively and the average follow-up period from operation date to fluoroscopic surveillance date was 13.8 ± 9.3 months and 16.7 ± 8.6 months, respectively. In vivo kinematics during sequential deep knee bending under weight-bearing condition were evaluated using fluoroscopic image analysis and 2- to 3- dimensional registration technique. Range of motion (ROM), axial rotation, anteroposterior (AP) translations of medial and lateral nearest points of the femoral component relative to the tibial component were measured and compared between the two groups. The nearest points were determined by calculating the closest distance between the surfaces of femoral component model and the axial plane of coordinate system of the tibial component. We defined external rotation and anterior translation as positive. P values under 0.05 was defined as statistically significant. Results. The mean PTS in group A and B were 5.5 ± 1.4°and 9.9 ± 1.9°, respectively. There was no statistically significant difference in the degrees of axial rotation from 0° to 110° of flexion between the two groups (4.9 ± 4.2° vs 5.2 ± 4.2°, p > 0.05), respectively. The hyperextension of group B were significantly larger than group A (−2.3 ± 6.6°vs −9.8 ± 8.7°, p <0.05). The ROM of group B were significantly larger than group A (118.7 ± 10.8°vs 128.7 ± 17.7°, p <0.05). However, there was no significant difference in the maximum flexion between the two groups (116.4 ±10.8°vs 118.9±14.5°, p >0.05), respectively. In terms of AP translation, medial nearest points were located significantly more posterior at 0°, 10°, 30°, 40° of flexion in group B compared to group A. There was no significant difference in the location of lateral nearest points between the two groups during all knee range of motion. Discussion/Conclusion. The results shown in this study demonstrated that the PTS influenced the kinematics and ROM under weight-bearing condition in CR-TKA. The large PTS induced great posterior displacement of medial nearest points during early flexion phase and increased hyperextension between the femoral and tibial components

Bi-cruciate stabilized (BCS) TKA is the prosthesis that aims to substitute bi-cruciate ligament with post-cam engagement. We estimated to describe the in vivo kinematics during deep knee bending in BCS and Cruciate retaining (CR) TKA with the same articular geometry. We analyzed 26 knees who agreed to the current investigation under institutional review board approval. 17 knees were implanted with BCS (Journey ∥BCS, Smith & Nephew. Memphis, US) and 9 knees with CR (Journey∥CR). Each patient was asked to perform deep knee bending under weight-bearing condition. To estimate the spatial position and orientation of the TKA, 2D/3D registration technique with single fluoroscopy was used. We evaluated anteroposterior (AP) translation of the nearest point from femoral component to tibial axial plane for medial and lateral sides, femoral external rotation relative to tibial component and post-cam engagement in BCS. Measurement results were analyzed using Wilcoxon test. Values of P<0.05 were considered statistically significant. Medial AP translation indicated 11.7±5.1% posterior movement in BCS and 4.0±6.6% anterior movement in CR from minimum flexion to 130°. Lateral AP translation indicated 28.9±11.4% posterior movement in BCS and 18.3±6.2% posterior movement in CR from minimum flexion to 130°. Femoral external rotation were observed in both group and the amount of rotation were 5.2°±4.5° in BCS and 8.2°±4.0° in CR. Anterior post-cam engagement was not observed in all cases (76.5%). But medial AP translation in BCS was anteriorly in shallow flexion angles compared to CR. It suggested that anterior post-cam engagement couldn't work in valid.

Objectives. Preservation of both anterior and posterior cruciate ligaments in total knee arthroplasty (TKA) can lead to near-normal post-operative joint mechanics and improved knee function. We hypothesised that a patient-specific bicruciate-retaining prosthesis preserves near-normal kinematics better than standard off-the-shelf posterior cruciate-retaining and bicruciate-retaining prostheses in TKA. Methods. We developed the validated models to evaluate the post-operative kinematics in patient-specific bicruciate-retaining, standard off-the-shelf bicruciate-retaining and posterior cruciate-retaining TKA under gait and deep knee bend loading conditions using numerical simulation. Results. Tibial posterior translation and internal rotation in patient-specific bicruciate-retaining prostheses preserved near-normal kinematics better than other standard off-the-shelf prostheses under gait loading conditions. Differences from normal kinematics were minimised for femoral rollback and internal-external rotation in patient-specific bicruciate-retaining, followed by standard off-the-shelf bicruciate-retaining and posterior cruciate-retaining TKA under deep knee bend loading conditions. Moreover, the standard off-the-shelf posterior cruciate-retaining TKA in this study showed the most abnormal performance in kinematics under gait and deep knee bend loading conditions, whereas patient-specific bicruciate-retaining TKA led to near-normal kinematics. Conclusion. This study showed that restoration of the normal geometry of the knee joint in patient-specific bicruciate-retaining TKA and preservation of the anterior cruciate ligament can lead to improvement in kinematics compared with the standard off-the-shelf posterior cruciate-retaining and bicruciate-retaining TKA. Cite this article: Y-G. Koh, J. Son, S-K. Kwon, H-J. Kim, O-R. Kwon, K-T. Kang. Preservation of kinematics with posterior cruciate-, bicruciate- and patient-specific bicruciate-retaining prostheses in total knee arthroplasty by using computational simulation with normal knee model. Bone Joint Res 2017;6:557–565. DOI: 10.1302/2046-3758.69.BJR-2016-0250.R1

Purpose. To compare postoperative clinical outcomes between posterior cruciate ligament (PCL) retaining and resecting total knee arthroplasty (TKA) using same cruciate-substituting (CS) inserts, and to elucidate the clinical relevance of the residual PCL in cruciate-retaining TKA, considering intraoperative influence factors, such as the posterior tibial slope, posterior condylar offset, joint gap, joint balance, and joint laxity. Methods. A total of 64 consecutive knees (44 patients) were enrolled in this study and divided into following two groups: 39 knees underwent PCL-retaining TKA group (CR group), and 25 underwent PCL-resecting TKA group (CS group). Preoperative patients’ demographic data and one-year postoperative clinical outcomes including range of motion, the Knee Injury and Osteoarthritis Outcome Score (KOOS), the Japanese Orthopaedic Association (JOA) score, and Forgotten Joint Score-12 (FJS-12) were compared between two groups. Results. Regarding range of motion, the average preoperative ROM was -14.3/120.0 degrees in the CR group and improved to -2.4/118.9 degrees postoperatively. In the CS group, the average preoperative ROM was -7.5/130 degrees and changed to -2.2/122.4 degrees postoperatively. There was no significant difference in the postoperative ROM between the groups (P=0.16). The KOOS (from 47.1 to 69.5 in CR group; from 41.1 to 70.8 in CS group) and JOA scores (from 59.2 to 76.9 in CR group; from 55.6 to 80.8 in CS group) were significantly improved postoperatively in both groups (P < 0.01). However, there was no significance in these postoperative scores between two groups (P = 0.09). There was also no significance in FJS-12 between two groups (70.3 in CR group and 66.9 in CS group; P=0.53). Conclusions. Residual PCL in TKA with a CS insert would not impact one-year postoperative clinical outcomes including KOOS, JOA, and FJS-12

Objectives

The Attune total knee arthroplasty (TKA) has been used in over 600 000 patients worldwide. Registry data show good clinical outcome; however, concerns over the cement-tibial interface have been reported. We used retrieval analysis to give further insight into this controversial topic.