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

Background. Total knee arthroplasty (TKA) is an effective surgical procedure to alleviate excruciating pain and correct dysfunction due to severe knee deformity. The satisfaction rate with current TKA is 80%, While 20% of the patients report uncomfortable feeling during stair descending and deeply knee bending. Preserving the ligaments might allow a restoration close to the natural function, although sacrifice of the ACL is common with the conventional TKA technique. The current bicruciate-retaining (BCR) TKA would be a way to go concerning this issue. This study aimed at evaluating the intraoperative kinematics and joint laxity on BCR TKA if the native function would be replicated and thus assessing the range of motion (ROM) at final followup. Methods. BCR TKAs were performed in 22 knees (12 women, 10 men, average aged 67.2-year-old) with image-free navigation system (Kolibli. TM. ) under general anesthesia. The intraoperative kinematics was evaluated about flexion extension gap (FEG), anterior-posterior translation (APT, bi-condylar rollback) and axial rotation (AR, medial pivot) with passive motion. These kinematic patterns were assessed with the post-operative ROM. Results. There was no paradoxical anterior translation in any cases. The implant kinematics was regulated to the medial pivot motion at early flexion phase and the bi-condylar rollback motion to full flexion angle. The mean flexion was changed from 132 degrees at preoperation to 126 degrees at followup, and the mean flexion contracture improved from 4 degrees to 1 degree. Conclusion. BCR TKA were preserved the nature kinematics including the medial pivot motion and rollback mechanism. Postoperative ROM was quite similar when the preoperative knee flexion was not restricted

Background

Total knee arthroplasty (TKA) was primarily considered a successful procedure, several new knee implants were introduced in recent years that seek to obtain improved stability and higher flexion. One of the implant, Vanguard XP^TM BiCruciate retaining (BCR), Zinmmer-Biomet, USA recreates a specific kinematic model through the principle of normal joint.

Bicruciate ligament retaining total knee arthroplasty preserves all of the ligaments of the knee while still addressing the ligament balance and the flexion-extension gaps. The concept of cruciate ligament preservation is not new and both Townley and Cartier designed prostheses in the late 1980s that did preserve all of the ligaments. Their results were quite acceptable for that time in knee replacement surgery but the posterior stabilised and cruciate retaining designs controlled most of the market. The surgical technique for cruciate ligament preservation was more difficult, and without clear clinical benefit, most surgeons gravitated towards the cruciate retaining and posterior stabilised designs. In the late 1990s, evaluation of the total knee arthroplasty began to assess knee kinematics in addition to pain and functional outcomes. At the same time, studies on the unicondylar knee arthroplasty demonstrated impressive scores in motion and patient satisfaction with preservation of all of the ligamentous structures of the knee. Over the past two years, new designs that preserve all of the ligaments of the knee have returned to the market. The instruments have been improved and the prostheses have been changed to respect the kinematics of the knee. Fifteen to twenty percent of all total knee replacement patients are not completely satisfied with the surgery and the authors believe that complete ligament preservation may address this complaint.

The goals of a total knee arthroplasty include approximation of the function of a normal knee and achievement of balance post-surgery. Accurate bone preparation and the preservation of natural ligaments along with a functional knee design, holds the potential to provide a method of restoring close to normal function.

Although conventional knee arthroplasty is considered a successful intervention for end-stage osteoarthritis, some patients still experience reduced functionality and in some cases, require revision procedures. With conventional manual techniques, accurate alignment of the tibial component has been difficult to achieve. Even in the hands of skilled knee surgeons, outliers beyond 2 degrees of the desired alignment may occur in as many as 40%-60% of cases using conventional methods, and the range of component alignment varies considerably.

Similarly, for total knee replacement outliers beyond 2 degrees of the desired alignment may occur in as many as 15% of cases in the coronal plane, going up to 40% of unsatisfactory alignment in the sagittal plane.

Robotics-assisted arthroplasty has gained increasing popularity as orthopaedic surgeons aim to increase accuracy and precision of implant positioning. With advances in computer generated data, with image free data, surgeons have the ability to better predict and influence surgical outcomes. Based on planned implant position and soft tissue considerations, robotics-assisted systems can provide surgeons with virtual tools to make informed decisions for knee replacement, specific to the needs of the patient.

Here, for the first time in a live surgical setting, we assess the accuracy and technique of a novel imageless semiautonomous handheld robotic surgical technique in bi-cruciate retaining total knee arthroplasty (Navio, Smith and Nephew). The system supports image-free anatomic data collection, intraoperative surgical planning and execution of the plan using a combination of robotic burring and saw cut guides.

Aims

The removal of the cruciate ligaments in total knee arthroplasty (TKA) has been suggested as a potential contributing factor to patient dissatisfaction, due to alteration of the in vivo biomechanics of the knee. Bicruciate retaining (BCR) TKA allows the preservation of the cruciate ligaments, thus offering the potential to reproduce healthy kinematics. The aim of this study was to compare in vivo kinematics between the operated and contralateral knee in patients who have undergone TKA with a contemporary BCR design.

Introduction

Many fluoroscopic studies on total knee arthroplasty (TKA) have identified kinematic variabilities compared to the normal knee, with many subjects experiencing paradoxical motion patterns. The intent of this study was to investigate the results of a newly designed PCR TKA to determine kinematic variabilities and assess these kinematic patterns with those previously documented for the normal knee.

Aims. The aim of this study was to determine the risk of tibial eminence avulsion intraoperatively for bi-unicondylar knee arthroplasty (Bi-UKA), with consideration of the effect of implant positioning, overstuffing, and sex, compared to the risk for isolated medial unicondylar knee arthroplasty (UKA-M) and bicruciate-retaining total knee arthroplasty (BCR-TKA). Methods. Two experimentally validated finite element models of tibia were implanted with UKA-M, Bi-UKA, and BCR-TKA. Intraoperative loads were applied through the condyles, anterior cruciate ligament (ACL), medial collateral ligament (MCL), and lateral collateral ligament (LCL), and the risk of fracture (ROF) was evaluated in the spine as the ratio of the 95. th. percentile maximum principal elastic strains over the tensile yield strain of proximal tibial bone. Results. Peak tensile strains occurred on the anterior portion of the medial sagittal cut in all simulations. Lateral translation of the medial implant in Bi-UKA had the largest increase in ROF of any of the implant positions (43%). Overstuffing the joint by 2 mm had a much larger effect, resulting in a six-fold increase in ROF. Bi-UKA had ~10% increased ROF compared to UKA-M for both the male and female models, although the smaller, less dense female model had a 1.4 times greater ROF compared to the male model. Removal of anterior bone akin to BCR-TKA doubled ROF compared to Bi-UKA. Conclusion. Tibial eminence avulsion fracture has a similar risk associated with Bi-UKA to UKA-M. The risk is higher for smaller and less dense tibiae. To minimize risk, it is most important to avoid overstuffing the joint, followed by correctly positioning the medial implant, taking care not to narrow the bone island anteriorly. Cite this article: Bone Joint Res 2022;11(8):575–584

Aims. The aim of this study was to compare a bicruciate-retaining (BCR) total knee arthroplasty (TKA) with a posterior cruciate-retaining (CR) TKA design in terms of kinematics, measured using fluoroscopy and stability as micromotion using radiostereometric analysis (RSA). Methods. A total of 40 patients with end-stage osteoarthritis were included in this randomized controlled trial. All patients performed a step-up and lunge task in front of a monoplane fluoroscope one year postoperatively. Femorotibial contact point (CP) locations were determined at every flexion angle and compared between the groups. RSA images were taken at baseline, six weeks, three, six, 12, and 24 months postoperatively. Clinical and functional outcomes were compared postoperatively for two years. Results. The BCR-TKA demonstrated a kinematic pattern comparable to the natural knee’s screw-home mechanism in the step-up task. In the lunge task, the medial CP of the BCR-TKA was more anterior in the early flexion phase, while laterally the CP was more posterior during the entire movement cycle. The BCR-TKA group showed higher tibial migration. No differences were found for the clinical and functional outcomes. Conclusion. The BCR-TKA shows a different kinematic pattern in early flexion/late extension compared to the CR-TKA. The difference between both implants is mostly visible in the flexion phase in which the anterior cruciate ligament is effective; however, both designs fail to fully replicate the motion of a natural knee. The higher migration of the BCR-TKA was concerning and highlights the importance of longer follow-up. Cite this article: Bone Joint J 2023;105-B(1):35–46

Introduction. A common problem for patients receiving total knee arthroplasty (TKA) is postoperative functional impairment of the joint. This is minimized in bicruciate-retaining (ACL preserving) knee replacements, due to the important role of the anterior cruciate ligament (ACL) in normal kinematic patterns of the knee. We explore ACL sparing TKA by estimating the fraction of osteoarthritic TKA patients with a compatible ACL (assessed intraoperatively), while also examining potential preoperative indicators of ACL status. Method. We retrospectively examined 498 patients with a primary diagnosis of osteoarthritis who underwent a TKA by one surgeon between September 2013 and March 2015. Exclusion criteria included a prior TKA, a unicompartmental knee replacement, or inflammatory arthritis. Extensive preoperative data (within four months of surgery) for each patient was collected (anatomical alignment, extension, flexion, range of motion (ROM), Lachman test, and BMI) in addition to de-identified demographic data. The intraoperative assessment of ACL status (normal/functionally intact, compromised/deficient, or absent) was then obtained from our local database and compared with the preoperative data. IRB exemption was obtained to retrospectively collect data. Results. Intraoperative assessment of ACL status found 73.5% normal ACL, 12.9% compromised ACL, and 13.6% absent ACL. A significant demographic predictor of ACL status was gender (female - more likely intact, male - more likely absent; χ2 = 12.43, P<0.002). Patients with an intact ACL were also shown to have significantly better preoperative extension (χ2=14.83, P<0.022), flexion (F. 2, 469. = 9.93, P < 0.001), and ROM (F. 2, 469. = 9.38, P < 0.001) than those with a compromised ACL. We had a very small number of positive Lachman test results, and therefore could not draw any valid conclusion for preoperative predictive ability of the test. There was no significant difference in age, ethnicity, BMI or preoperative alignment between ACL status groups. Conclusion. Our study found 73.5% of 498 osteoarthritic TKA patients have an intact ACL. The strongest preoperative indicators of ACL status were gender, flexion, and ROM. Taken together, our results highlight a significant percentage of patients who are potential candidates for a bicruciate-retaining TKA

Introduction. Bicruciate-retaining (BiCR) total knee replacements (TKRs) were designed to improve implant performance; however, functional advantages during daily activity have yet to be demonstrated. Although level walking is a common way to analyze functionality, it has been shown to be a weak test for identifying gait abnormalities related to ACL pathologies. The goal of this study is to set up a functional motion analysis test that will examine the effects of the ACL in TKR patients by comparing knee kinematics, kinetics, and muscle activation patterns during level and downhill walking for patients with posterior-cruciate retaining (PCR) and BiCR TKRs. Methods. Motion and electromyography (EMG) data were collected simultaneously for 12 subjects (4/8 m/f, 64±11 years, 31.3±7.3 BMI, 6/6 right/left) with BiCR TKRs and 15 subjects (6/9 m/f, 67±7 years, 30.5±5.1 BMI, 4/11 right/left) with PCR TKRs during level and downhill walking using the point cluster marker set. Surface electrodes were placed on the vastus medialis obliquus (VMO), rectus femoris (RF), biceps femoris (BF), and semitendinosus (ST) muscles. EMG data are reported as percent relative voluntary contraction (%RVC), normalizing the signal during downhill walking to the mean maximum EMG value during level walking. Results. For level walking, there were no significant differences between groups in knee kinematics, kinetics, and EMG patterns. During downhill walking, subjects with BiCR implants showed significantly lower peak muscle activity in the VMO (73.9 ± 49.1%RVC for BiCR vs. 113 ± 24.0%RVC for PCR; p=0.045) and RF (96.0 ± 25.7%RVC for BiCR vs. 128 ± 28.6%RVC for PCR; p=0.018). There was also a trending higher knee peak flexion moment for the BiCR subjects (2.0 ± 0.6% BW*HT vs. 1.5 ± 0.6% BW*HT, p = .076), as well as significantly more knee flexion at heel strike (5.1 ± 4.7 degrees vs. 1.8 ± 2.8 degrees, p = 0.044) compared with the PCR group. Discussion. Retention of the ACL led to altered muscle recruitment during downhill walking in BiCR subjects compared with PCR subjects. In BiCR subjects, quadriceps activity was reduced during downhill walking compared to level walking. PCR subjects on average did not show this reduction, possibly in compensation for decreased knee stability. While there were only a few significant kinematic/kinetic differences, it appears that BiCR TKRs may offer some neuromuscular benefits during more strenuous tasks like downhill walking. In conclusion, level and downhill walking knee kinematics and kinetics together with the corresponding quadriceps and hamstrings EMG signals begin to build an overall picture of implant functionality during motion analysis testing

Aims

Mobile-bearing unicompartmental knee arthroplasty (UKA) with a flat tibial plateau has not performed well in the lateral compartment, leading to a high rate of dislocation. For this reason, the Domed Lateral UKA with a biconcave bearing was developed. However, medial and lateral tibial plateaus have asymmetric anatomical geometries, with a slightly dished medial and a convex lateral plateau. Therefore, the aim of this study was to evaluate the extent at which the normal knee kinematics were restored with different tibial insert designs using computational simulation.

Aims

Commonly performed unicompartmental knee arthroplasty (UKA) is not designed for the lateral compartment. Additionally, the anatomical medial and lateral tibial plateaus have asymmetrical geometries, with a slightly dished medial plateau and a convex lateral plateau. Therefore, this study aims to investigate the native knee kinematics with respect to the tibial insert design corresponding to the lateral femoral component.

We report on the long-term results of 163 bicruciate-retaining Hermes 2C total knee replacements in 130 patients at a mean follow-up of 22.4 years (20.3 to 23.5). Even when the anterior cruciate ligament had a partially degenerative appearance it was preserved as long as the knee had a normal anterior drawer and Lachman’s test pre-operatively. The description and surgical technique of this minimally constrained prosthesis were published in 1983 and the ten-year clinical results in 1999.

A total of 12% of the knees (20 of 163) in this study were revised because of wear of the polyethylene tibial insert. Excellent stability was achieved and the incidence of aseptic component loosening was 4.3% (seven of 163). The survival rate using revision for any reason as the endpoint was 82% (95% confidence interval 76.2 to 88.0).

Although this series included a relatively small number of replacements, it demonstrated that the anterior cruciate ligament, even when partially degenerated at the time of TKR, remained functional and provided adequate stability at a long-term follow-up.

Cite this article: Bone Joint J 2013;95-B:917–22.