In vivo kinematics of healthy male knees during squat and golf swing using image-matching techniques

Knee biomechanics during rehabilitation exercise in individuals with and without anterior cruciate ligament reconstruction: A systematic review

BACKGROUND

Post-traumatic osteoarthritis rates are similar in individuals with anterior cruciate ligament injury who receive surgical reconstruction and those who opt for non-surgical management, indicating continuing changes in knee biomechanics post-surgery. There is no gold standard rehabilitation strategy for the post-reconstruction patient, however investigating the biomechanics of the knee during rehabilitation exercises will drive the development of more efficacious rehabilitation paradigms. This systematic review aimed to synthesise biomechanical data from healthy participants and participants with anterior cruciate ligament reconstruction during rehabilitation exercises to provide insights into knee biomechanical changes induced by injury and surgery.

METHODS

A systematic literature search was conducted in Web of Science, MEDLINE, EMBASE, PubMed, CINAHL and Scopus, using key terms relating to anterior cruciate ligament reconstruction, lower limb rehabilitation exercises, and knee biomechanics. 34 articles matching the inclusion criteria were identified following abstract and full text screening.

FINDINGS

The included studies reported data on 607 healthy participants and 175 participants with an anterior cruciate ligament reconstruction across five different exercises. Peak knee flexion angle was the most reported variable, whereas tibial anterior translation and adduction biomechanics were reported infrequently, despite their relevance to the ligament injury status.

INTERPRETATION

There is limited biomechanical data of rehabilitation exercise in the knee, with the exception of knee flexion angles. Furthermore, variations in data collection and reporting methods across studies cause difficulties in systematic analysis of results and demonstrate inconsistent kinematic results between articles.

Golf After Total Hip and Knee Arthroplasty: Getting Back Into the Swing

Golf is a popular sport with an estimated 60 million participants worldwide. The sport remains popular among older adults, including those with a total hip arthroplasty (THA) or total knee arthroplasty (TKA) because of the low-moderate intensity of the activity. Accordingly, golfers who are contemplating undergoing THA or TKA are interested in the rate of return to play, outcomes, and limitations after surgery. The factors affecting return to golf are numerous, including patient-specific factors and biomechanical changes in the hip and knee affecting the golf swing. Specifically, younger age, male sex, and lower body mass index are independent predictors of return to golf. Furthermore, changes in leg length, alignment, and implant type/position can also affect function and play. Despite these factors, golfing patients routinely demonstrate successful return to their sport with less pain and improved mobility after THA and TKA. A comprehensive preoperative evaluation, expectation setting to return to any recreational activity, patient-specific surgical planning, and a functional rehabilitation program can provide optimal outcomes in those wishing to return to golf after total joint arthroplasty.

Preoperative tibiofemoral contact point on standing lateral radiograph predicts anteroposterior knee kinematics in total knee arthroplasty

Purpose

This study investigated the tibiofemoral contact point (CP) on standing lateral radiographs in knee osteoarthritis and assessed the relationship between CP and pre- and postoperative knee kinematics in total knee arthroplasty (TKA).

Methods

The intraoperative knee status of 46 knees with varus deformity that underwent bicruciate stabilized TKA using a navigation system was investigated. The intraoperative anteroposterior (AP) position of the femur relative to the tibia at maximum extension, 15°, 30°, 45°, 60° and 90° was evaluated by the navigation system before and after TKA. The CP, defined as the CP between the femur and tibia, was assessed on standing lateral radiographs at the maximum extension of the knee before and 1 year after TKA. CP was expressed as the ratio of tibial plateau distance on a scale of 0-1, with 0 indicating the most anterior position of the femur relative to the tibia.

Results

The mean CP on standing lateral radiographs was 0.54 ± 0.12 and 0.46 ± 0.08 before and after TKA, respectively. The postoperative CP was significantly more anterior than the preoperative CP (p = 0.0002). The mean AP position of the femur relative to the tibia moved anteriorly during early knee flexion both before and after TKA, representing nonanatomical AP movement. The preoperative posterior CP group (CP > 0.54) showed more nonanatomical AP movement from 15° to 60° before and after TKA compared with the preoperative anterior CP group (CP < 0.54).

Conclusion

Preoperative posterior deviation of the femur relative to the tibia in the standing position was a predictive factor for nonanatomical AP knee kinematics. Biomechanical analysis of postoperative knees will be necessary; however, surgeons should focus on preoperative tibiofemoral CP on standing lateral radiographs to predict knee kinematics.

Level of Evidence

Level Ⅲ.

Sitting Sideways Causes Different Femoral-Tibial Rotations in Each Knee

Purpose According to a previous study, asymmetrical kneeling, such as sitting sideways, does not exhibit asymmetrical movements. Rotational analyses of each femur and tibia help explain why rotational knee kinematics while sitting sideways do not exhibit asymmetrical movement. We aimed to assess the rotation of the femur and tibia in normal knees while sitting sideways. Methods Each volunteer sat sideways under fluoroscopy. Two-dimensional and three-dimensional registration techniques were used. After evaluating the femoral rotation angle relative to the tibia at each flexion angle, the femoral and tibial sole rotation angles at each flexion angle were compared between the ipsilateral and contralateral knees. Results While sitting sideways, both knees showed femoral external rotation relative to the tibia with flexion. In the ipsilateral knees, the femurs exhibited an external rotation of 26.3 ± 8.0°, from 110° to 150° of flexion. Conversely, the tibia exhibited an external rotation of 12.2 ± 7.8°, from 110° to 150° of flexion. From 110° to 150° of flexion, femoral external rotation was significantly larger than tibial external rotation. In the contralateral knees, the femurs exhibited an internal rotation of 23.8 ± 6.3°, from 110° to 150° of flexion (110°, p < 0.001; 120°, p < 0.001; 130°, p < 0.001; 140°, p < 0.001; and 150°, p < 0.001). Contrastingly, the tibia exhibited an internal rotation of 30.4 ± 8.8°, from 110° to 150° of flexion, which was significantly larger than femoral internal rotation (110°, p = 0.002; 120°, p < 0.001; 130°, p < 0.001; 140°, p < 0.001; and 150°, p < 0.001). Conclusions Although bilateral knees exhibited femoral external rotation relative to the tibia while sitting sideways, the ipsilateral and contralateral knees showed femoral and tibial sole rotations in opposite directions. In particular, the contralateral knees might show a strained movement because both femurs and tibias exhibited internal rotation with flexion. Patients who have undergone guided-motion total knee arthroplasty (TKA) or medial-pivot TKAs might be advised to avoid sitting sideways.

DRR acceleration using inexpensive GPUs for model-image registration based joint kinematic measurements

Model-image registration methods are commonly used in research to measure three-dimensional joint kinematics from single-plane and bi-plane x-ray images. These methods have the potential to be beneficial if used clinically, but current techniques are too slow or expensive to be clinically practical. One technical element of these methods for measuring natural bone motion is the use of digitally reconstructed radiographs (DRRs). DRRs can be very expensive to compute, or require expensive and fast computer hardware. In this technical development, a numerically efficient Siddon-Jacobs algorithm for computing DRRs was implemented on a consumer-grade graphics card using a programming language for parallel architectures. Compared to traditional voxel projection algorithms with a central-processing-unit-only implementation, the parallel computation implementation on the graphics card provided speedups of 650-1546 times faster rendering, while retaining equivalent performance for joint kinematics measurements. The use of consumer grade graphics hardware may contribute to making model-image registration measurements of joint kinematics practical for clinical use.

Lower Limb Biomechanics during the Golf Downswing in Individuals with and without a History of Knee Joint Injury

Although prevention is better than treatment, after a knee injury occurs, the adjustment of the movement technique back to the posture before the injury and the restoration of accuracy is very important for professional and amateur players. This study aimed to compare the differences in lower limb mechanics during the golf downswing between those with and without a history of knee joint injury. A total of 20 professional golfers with single-digit handicaps were recruited for this study, 10 of whom had a knee injury history (KIH+), while another 10 players were without a knee injury history (KIH-). From the 3D analysis, selected kinematic and kinetic parameters during the downswing were analyzed using an independent samples t-test with a significance level of α = 0.05. During the downswing, individuals with KIH+ exhibited a smaller hip flexion angle, smaller ankle abduction angle, and larger ankle adduction/abduction range of motion (ROM). Moreover, there was no significant difference found in the knee joint moment. Athletes with a history of knee injury can adjust the motion angles of their hip and ankle joints (e.g., by avoiding excessive forward leaning of the trunk and maintaining stable foot posture without inward or outward rotation) to minimize the impact of changes in their movement patterns resulting from the injury.

[Kinematic Alignment of Total Knee Arthroplasty]

Nowadays, kinematic alignment is a widely used alignment philosophy in total knee arthroplasty. The concept of kinematic alignment respects the patient's individual prearthrotic anatomy and is based on the reconstruction of the femoral anatomy and thus the axes of motion of the knee joint. Only then the alignment of the tibial component is adapted to the femoral component. By means of this technique soft tissue balancing is reduced to a minimum. Due to the risk of excessive outlier alignment technical assistance or calipered techniques are recommended for precise implementation. This article attempts to provide an understanding of the fundamentals of kinematic alignment, and it focusses on how it differs from alternative alignment strategies and the way the philosophy is implemented in different surgical techniques.

Rotational Soft-Tissue Balance Is Highly Correlated with Rotational Kinematics in Total Knee Arthroplasty

Recovery of normal knee kinematics is critical for improving functional outcomes and patient satisfaction after total knee arthroplasty (TKA). The kinematics pattern after TKA varies from case to case, and it remains unclear how to reproduce normal knee kinematics. The present study aimed to evaluate rotational knee kinematics and soft-tissue balance using a navigation system and to assess the influence of intraoperative soft-tissue balance on the rotational knee kinematics. We evaluated 81 osteoarthritic knees treated with TKA using a posterior stabilized (50 knees) or cruciate retaining (31 knees) prosthesis. Rotational kinematics were assessed at 0, 30, 45, 60, and 90 degrees flexion angles by using a computer-assisted navigation system. Correlation between femorotibial rotational position and measured soft tissue balance was assessed by using Spearman's rank correlation coefficient. Rotational soft-tissue balance (the median angle of rotational stress) was significantly correlated with rotational kinematics (rotational axis of the femur relative to the tibia throughout the range of motion) at all measured angles after TKA. The correlation coefficients between the median angle of rotational stress and rotational kinematics were 0.97, 0.80, 0.74, 0.71, and 0.70 at 0, 30, 45, 60, and 90 degrees of flexion, respectively (p-values <0.0001 in all measured angles). The correlation coefficient increased as the knee approached full extension. Our findings suggest that soft-tissue balance is a key factor for rotational kinematics, following both cruciate-retaining and posterior-stabilized TKA.

[Accuracy of patellar tendon at the attachment as anatomic landmark for rotational alignment of tibial component]

Objective

To investigate the accuracy of the modified Akagi line which referenced the patellar tendon at the attachment and the geometrical center point of the tibial osteotomy surface for tibial rotational alignment.

Methods

Between July 2021 and December 2021, 72 patients who underwent three-dimension (3D) CT for varus osteoarthritis knees were enrolled. Among 72 patients, 18 were male and 54 were female with a mean age of 64.9 years (range, 47-84 years). The preoperative hip-knee-ankle angle ranged from 0° to 26°, with a mean of 9.3°. CT images were imported into Mimics 21.0 medical image control system to establish 3D models of the knees. The prominent point of lateral epicondyle and the medial epicondylar sulcus were identified in femoral 3D models to construct the surgical transepicondylar axis and the vertical line of its projection [anteroposterior (AP) axis]. In tibial 3D models, the patellar tendon at the attachment was used as anatomical landmarks to construct rotational alignment for tibial component, including the line connecting the medial border of the patellar tendon at the attachment (C) and the middle (O) of the posterior cruciate ligament insertion (Akagi line), the line connecting the point C and the geometric center (GC) of the tibial osteotomy plane [medial border axis of the patellar tendon (MBPT)], the line connecting the medial sixth point of the patellar tendon at the attachment and the point GC [medial sixth axis of the patellar tendon (MSPT)], the line connecting the medial third point of the patellar tendon at the attachment and point O [medial third axis of the patellar tendon 1 (MTPT1)], and the line connecting the medial third point of the patellar tendon at the attachment and point GC [medial third axis of the patellar tendon 2 (MTPT2)]. The angles between the five reference axes and the AP axis were measured, and the distribution of the rotational mismatch angles with the AP axis was counted (≤3°, 3°-5°, 5°-10°, and >10°).

Results

Relative to the AP axis, the Akagi line and MBPT were internally rotated (1.6±5.9)° and (2.4±6.9)°, respectively, while MSPT, MTPT1, and MTPT2 were externally rotated (5.4±6.6)°, (7.0±5.8)°, and (11.9±6.6)°, respectively. There were significant differences in the rotational mismatch angle and its distribution between reference axes and the AP axis ( F=68.937, P<0.001; χ 2=248.144, P<0.001). The difference between Akagi line and MBPT showed no significant difference ( P=0.067), and the differences between Akagi line and MSPT, MTPT1, MTPT2 were significant ( P<0.012 5).

Conclusion

When the position of the posterior cruciate ligament insertion can not be accurately identified on total knee arthroplasty, MBPT can be used as the modified Akagi line in reference to the geometrical center point of the tibial osteotomy surface to construct a reliable rotational alignment of the tibial component.

Golf Swing Biomechanics: A Systematic Review and Methodological Recommendations for Kinematics

Numerous studies have been conducted to investigate golf swing performance in both preventing injury and injury occurrence. The objective of this review was to describe state-of-the-art golf swing biomechanics, with a specific emphasis on movement kinematics, and when possible, to suggest recommendations for research methodologies. Keywords related to biomechanics and golf swings were used in scientific databases. Only articles that focused on golf-swing kinematics were considered. In this review, 92 articles were considered and categorized into the following domains: X-factor, crunch factor, swing plane and clubhead trajectory, kinematic sequence, and joint angular kinematics. The main subjects of focus were male golfers. Performance parameters were searched for, but the lack of methodological consensus prevented generalization of the results and led to contradictory results. Currently, three-dimensional approaches are commonly used for joint angular kinematic investigations. However, recommendations by the International Society of Biomechanics are rarely considered.

In Vivo three-dimensional kinematics of normal knees during sitting sideways on the floor

Background

The normal knee kinematics during asymmetrical kneeling such as the sitting sideways remains unknown. This study aimed to clarify in vivo kinematics during sitting sideways of normal knees.

Methods

Twelve knees from six volunteers were examined. Under fluoroscopy, each volunteer performed a sitting sideways. A two-dimensional/three-dimensional registration technique was used. The rotation angle, varus-valgus angle, anteroposterior translation of the medial and lateral sides of the femur relative to the tibia, and kinematic pathway in each flexion angle was evaluated.

Results

Bilateral knees during sitting sideways showed a femoral external rotation relative to the tibia with flexion (ipsilateral: 13.7 ± 3.5°, contralateral: 5.8 ± 6.8°). Whereas the ipsilateral knees showed valgus movement of 4.6 ± 2.5° from 130° to 150° of flexion, and the contralateral knees showed varus movement of -3.1 ± 4.4° from 110° to 150° of flexion. The medial side of the contralateral knees was more posteriorly located than that of the ipsilateral knees beyond 110° of flexion. The lateral side of the contralateral knees was more anteriorly located than that of the ipsilateral knees from 120° to 150° of flexion. In the ipsilateral knees, a medial pivot pattern followed by a bicondylar rollback was observed. In the contralateral knees, no significant movement followed by a bicondylar rollback was observed.

Conclusion

Even though the asymmetrical kneeling such as sitting sideways, the knees did not display asymmetrical movement.

Comparison of in vivo knee kinematics before and after bicruciate-stabilized total knee arthroplasty during squatting

Background

No studies have directly evaluated kinematic changes during squatting before and after bicruciate-stabilized total knee arthroplasty (BCS-TKA) with the dual cam-post mechanism and asymmetric surfaces. This study investigated the effect of BCS-TKA on changes to pre- and postoperative skeletal knee kinematics, to identify factors associated with postoperative skeletal kinematic parameters.

Methods

Seventeen knees in 17 patients were prospectively recruited before primary TKA for advanced medial knee osteoarthritis. Subjects underwent BCS-TKA and were evaluated more than 1 year postoperatively. In vivo dynamic skeletal knee kinematics were evaluated using periodic radiographic images collected during squatting to quantify the tibiofemoral functional extension/flexion angle, anteroposterior (AP) translation, and axial rotation angle using image-matching techniques. Rotational alignments of femoral and tibial components were measured postoperatively using computed tomography images.

Results

The pre- and postoperative tibiofemoral functional extension/flexion angles during squatting were 12.2° ± 6.7°/100.1° ± 16.8° and 9.6° ± 8.6°/109.4° ± 16.8°, respectively, with a significant difference in flexion angle (p < .05). Total AP translation was significantly larger postoperatively than preoperatively (10.8 mm ± 3.7 mm vs. 14.4 mm ± 4.2 mm, respectively; p < .05). The pre- and postoperative total rotation angles were 6.6° ± 3.0° and 6.4° ± 3.7°, respectively, indicating no significant difference. The pre- and postoperative tibiofemoral functional flexion angles were significantly associated with each other (p = .0434, r = .49). The postoperative total rotation angle was significantly smaller when the total component rotational mismatch angle between the femoral and tibial components was above 5° vs. below 5° (4.6° ± 2.7° vs. 8.3° ± 3.9°, respectively; p < .05).

Conclusions

BCS-TKA significantly increased the tibiofemoral functional flexion angles, with larger AP translation postoperatively. Both preoperative skeletal kinematics and surgical techniques affected the skeletal kinematics of the replaced knee. A total component rotational mismatch angle greater than 5° significantly decreased postoperative total knee rotation during squatting.

Consistent femoral external rotation during weight-bearing knee flexion is associated with better patient-reported pain and mediolateral balance after total knee arthroplasty

BACKGROUND

Normal knees generally show consistent femoral external rotation during knee flexion, although knees that have had total knee arthroplasty exhibit various rotational patterns with less rotational angle. This study aimed to determine whether consistent femoral external rotation during weight-bearing knee flexion after total knee arthroplasty is associated with better patient-reported outcomes and mediolateral joint balance.

METHODS

A total of 40 total knee arthroplasty knees with a high-flexion posterior-stabilized prosthesis were divided into two groups based on their axial rotational kinematic pattern during squatting activity, and the clinical results including patient-reported outcomes and joint laxity were compared between the consistent external rotation group (20 knees) and the inconsistent external rotation group (20 knees). The unpaired Student's t-test or Welch's test were used for group comparison, and Fisher's exact test was applied for categorical data.

FINDINGS

"Pain at rest" and "Pain at first gait in the morning" measured using a numerical rating scale (/10) were significantly lower in the consistent external rotation group compared with those in the inconsistent external rotation group. "Pain during gait on flat surface" tended to be lower in the consistent external rotation group. Medial stability was obtained in both groups with significantly greater lateral laxity in extension in the inconsistent external rotation group.

INTERPRETATION

Total knee arthroplasty knees with consistent femoral external rotation during weight-bearing knee flexion exhibited better patient-reported pain and mediolateral soft tissue balance. Surgical procedures that control the mediolateral balance with medial stability would induce consistent femoral external rotation and improve patient-reported pain.

Return to Play and Performance in Golfers After Total Knee Arthroplasty: Does Component Type Matter?

BACKGROUND

Golf is a popular sport among patients undergoing total knee arthroplasty (TKA). The golf swing requires significant knee rotation, which may lead to changes in golfing ability postoperatively. The type of implant used may alter the swing mechanics or place different stresses on the knee. The purpose of this study was to evaluate golf performance and subjective stability after TKA and compare outcomes between cruciate-retaining (CR) and posterior-stabilized (PS) implants.

HYPOTHESIS

Patients with CR implants will experience better stability during the golf swing compared to patients with PS implants.

STUDY DESIGN

Retrospective cohort study.

LEVEL OF EVIDENCE

Level 3.

METHODS

Patients who underwent primary TKA were identified from the medical record and sent an electronic questionnaire focusing on return to play (RTP), performance, pain, and stability during the golf swing. Knee injury and Osteoarthritis Outcome Scores (KOOS) were collected before and at multiple time points after surgery. Patients were surveyed postoperatively and asked to evaluate overall performance, pain, and stability before and after surgery. Outcomes were compared based on implant type.

RESULTS

Most patients (81.5%) were able to return to golf at an average of 5.3 ± 3.1 months from surgery. The average postoperative KOOS was 74.6 ± 12.5 in patients able to RTP compared with 64.4 ± 9.5 in those who were not (P < 0.05). Knee pain during golf significantly improved from 6.4 ± 2.1 to 1.8 ± 2.2 (P < 0.01). There were no significant differences in pain, performance, or stability between the CR and PS patients.

CONCLUSION

Most patients can successfully return to golfing after TKA. Knee replacement offers patients reliable pain relief during the golf swing and fewer physical limitations during golf, with no detriment to performance. There is no difference in performance or subjective knee stability based on component type.

CLINICAL RELEVANCE

Understanding associated outcomes of different TKA knee systems allows for unbiased and confident recommendations of either component to golfers receiving total knee replacement.

Characteristic kinematics of floor-sitting activities after posterior-stabilized total knee arthroplasty determined using model-based shape-matching techniques

BACKGROUND

Detailed kinematics of floor-sitting activities after total knee arthroplasty (TKA) have not been well explored. Knee kinematics of cross-legged sitting, seiza-sitting, and side-sitting after TKA were examined to clarify the differences in tibiofemoral kinematics of each activity.

METHODS

Subjects were 40 knees in 20 osteoarthritic patients who underwent bilateral TKA with a high-flexion fixed-bearing posterior-stabilized prosthesis. Dynamic radiographs of floor-sitting activities were taken, and the knee kinematics were compared among the three activities. The patients were also divided into two groups (possible/easy group and impossible/no-try group) for each activity, and group comparisons were conducted.

RESULTS

The maximum implant flexion angle was significantly greater in seiza-sitting. In valgus/varus rotation, seiza-sitting demonstrated neutral rotation, while cross-legged sitting showed varus of about 10°, and side-sitting exhibited valgus. In tibial internal/external rotation, seiza-sitting demonstrated a constant rotational angle, while cross-legged sitting showed tibial internal rotation with flexion, and side-sitting exhibited tibial external rotation with flexion. The kinematic pathway during deep flexion illustrated the medial pivot pattern in cross-legged sitting, a small amount of bicondylar rollback in seiza-sitting, and the weak lateral pivot pattern in side-sitting. A greater flexion angle was the important factor for the performance of each floor-sitting activity followed by varus laxity at 10° knee flexion.

CONCLUSIONS

This study successfully revealed characteristic kinematic patterns of TKA knees in three floor-sitting activities. Obtaining a greater knee flexion with adequate lateral laxity is the key to enhancing postoperative floor-sitting activities.

In Vivo Kinematics of Bicruciate-Retaining Total Knee Arthroplasty with Anatomical Articular Surface under High-Flexion Conditions

Bicruciate-retaining total knee arthroplasty (BCR-TKA) recreates normal knee movement by preserving the anterior cruciate and posterior cruciate ligaments. However, in vivo kinematics of BCR-TKA with the anatomical articular surface remains unknown. The objective of this study was to evaluate in vivo kinematics of BCR-TKA with the anatomical articular surface during high-flexion activities. For this purpose, 17 knees after BCR-TKA with an anatomical articular surface were examined. Under fluoroscopy, each patient performed squatting and cross-legged sitting motions. To estimate the spatial position and orientation of the knee, a two-dimensional or three-dimensional registration technique was used. Rotation, varus-valgus angle, and anteroposterior translation of medial and lateral contact points of the femoral component relative to the tibial component were evaluated in each flexion angle. The results showed that from 80 to 110° of flexion, the femoral external rotation during squatting was significantly larger than that during cross-legged sitting. At maximum flexion, the knees during sitting indicated significantly more varus alignment than during squatting. During squatting, a medial pivot pattern was observed from minimum flexion to 10° flexion, with no significant movement beyond 10° of flexion. Conversely, during cross-legged sitting, no significant movement was detected from minimum flexion to 60° of flexion, with a medial pivot beyond 60° of flexion. Therefore, the knees showed relatively normal kinematics after BCR-TKA with an anatomical articular surface; however, it varied during high-flexion activities depending on the activity.

Intraoperative kinematics of bicruciate-stabilized total knee arthroplasty during high-flexion motion of the knee

BACKGROUND

It is unknown whether intraoperative kinematics of bicruciate-stabilized total knee arthroplasty (BCS-TKA) are different for different activities. It has also not been established whether intraoperative high-flexion motions correlate with postoperative patient-reported outcome measures (PROMs). We aimed to clarify the intraoperative kinematics of BCS-TKA during high-flexion activities and describe the relationship between intraoperative and postoperative patient-reported outcomes.

METHODS

We examined 33 knees from 31 patients who underwent BCS-TKA and measured intraoperative knee kinematics, passive knee flexion, and cross-legged flexion using a navigation system. We also calculated knee flexion, varus-valgus, and rotation angles. As a secondary evaluation, we divided the patients into two clusters based on the PROMs and compared the kinematics between them.

RESULTS

The valgus moved by 1.3 ± 1.3° beyond 90° knee flexion during passive flexion. In contrast, during cross-legged flexion, the varus moved by 4.6 ± 5.1° beyond 30° flexion. This indicated significantly increased varus alignment in the cross-legged flexion as compared with passive flexion. Beyond 60° of flexion, the femur displayed 8.8 ± 4.8° of external rotation relative to the tibia. In cross-legged flexion, the femur displayed 9.2 ± 6.5° of external rotation relative to the tibia beyond 45° of flexion. At 90° of flexion, the cross-legged knees rotated more externally. There were no significant postoperative differences between the high- and low-score clusters.

CONCLUSION

The intraoperative knee kinematics after BCS-TKA during high-flexion motions differed depending on the performance of an individual. This will be useful for physicians who might recommend BCS-TKA to new patients.

Influence of tibial bearing curvatures of a customised total knee implant on squatting motion and loads

A range of preliminary designs of customised total knee implants (CTKIs) was created by resurfacing the distal femur and applying different tibial bearing surface curvatures. These were then compared with a scaled off-the-shelf symmetric total knee implant (STKI). To evaluate the biomechanical performance, a dynamic knee simulation model was created with patient-specific muscle and ankle joint loads calculated from an OpenSim musculoskeletal model. Simulation results showed the transverse curvatures of the tibial bearing surface influenced femoral mediolateral translation, while its longitudinal curvatures affected femoral adduction. Compared to the STKI, the CTKIs could restore patient knee function.

Evaluation of tibial rotational axis in total knee arthroplasty using magnetic resonance imaging

Surgeon-dependent factors such as optimal implant alignment of the tibial component are thought to play a significant role in the outcome following primary total knee arthroplasty (TKA). In addition, tibial component malrotation is associated with pain, stiffness, and altered patellofemoral kinematics in TKA. However, measuring tibial component rotation after TKA is difficult. Therefore, the purpose of this study was to find a reliable method for positioning the tibial component in TKA. To investigate the morphology of the tibial plateau, 977 patients' knees (829 females and 148 males) were evaluated using MRI. The relationships between the femoral transepicondylar axis (TEA), Akagi line, posterior tibial margin (PTM), medial third of the tibial tubercle (MTT), and anatomical tibial axis (ATS) were investigated in this study. In addition, gender difference in tibial rotational alignment were evaluated. Relative to the TEA, the MTT and ATS were externally rotated by 0.5° ± 4.4° and 0.5° ± 5.4°, respectively, while Akagi line and PTM were internally rotated by 3.7° ± 4.5° and 9.9° ± 6.1°, respectively. Gender differences were found in MTT, Akagi line and ATS (P < 0.05). Our result showed that the rotational alignment led to notable variance between femoral and tibial components using fixed bone landmarks. The MTT and ATS axes showed the closest perpendicular aspect with projected TEA. And the MTT and Akagi axes showed the reduced variance. In addition, PTM is not a reliable landmark for rotation of the tibial component. Based on the results of this study, surgeons may choose the proper anteroposterior axis of the tibial component in order to reduce rotational mismatch and improve clinical outcomes.

Rotational and varus-valgus laxity affects kinematics of the normal knee: A cadaveric study

PURPOSE

The aim of this study was to evaluate the relationship between soft tissue laxity and kinematics of the normal knee using a navigation system.

METHODS

Fifteen cadaveric knees from 11 fresh frozen whole-body specimens were included in this study. The navigation system automatically recorded the rotation angle of the tibia as the internal-external (IE) kinematics and the coronal alignment of the lower limb as the varus-valgus (VV) kinematics. These measurements were made with the joint in maximal extension, at 10° intervals from 0° to 120° of flexion, and at maximal flexion during passive knee motion. For evaluation of laxity, the examiner gently applied maximum manual IE and VV stress to the knee at 0°, 30°, 60°, and 90° of flexion.

RESULTS

The measurements showed almost perfect reliability. The mean correlation coefficient between the intraoperative tibial rotation angle and the intermediate angle of IE laxity was 0.82, while that between the coronal alignment of the lower limb and the intermediate angle of the VV laxity was 0.96. There was a statistically significant correlation between kinematics and laxity at all degrees of knee flexion.

CONCLUSION

The present study revealed that the rotation angle of the tibia was correlated to the intermediate angle of IE laxity at 0°, 30°, 60°, and 90° of knee flexion and the coronal alignment of the lower limb also correlated to the intermediate angle of VV laxity. These findings provide important reference data on soft tissue laxity and kinematics of the normal knee.

Tibiofemoral kinematics in healthy and osteoarthritic knees during twisting

Purpose

The purpose of this study was to determine the in vivo kinematics of healthy knees and those with osteoarthritis (OA), during twisting using density-based image-matching techniques.

Methods

Five healthy subjects and 26 patients with medial knee OA performed twisting under periodic X-ray imaging.

Results

The tibiofemoral rotation at the ipsilateral/contralateral twist in healthy and OA knees were 11° ± 9.3° externally/9.5° ± 5.6° internally (p < 0.05) and 4.4° ± 7.2° externally/2.7° ± 8° internally (p < 0.05), respectively.

Conclusions

The kinematic analysis of OA knees during twisting revealed significantly smaller tibiofemoral rotation than those of healthy knees.

Intraoperative analysis of the kinematics of the native knee including two-dimensional translation of the femur using a navigation system : a cadaveric study

The aim of this cadaveric study was to evaluate the intraoperative kinematics of the native knee including two-dimensional translation of the femur using a navigation system. Eight native knees of 4 fresh-frozen whole-body cadavers were used for the study. The kinematics of each knee were analyzed intraoperatively using the navigation system. Although anterior-posterior translation could not be assessed directly, it could be calculated using a formula derived from the parameters in the navigation system. The native knee showed external rotation of the femur in early knee flexion, transient internal rotation in mid flexion, and gradual external rotation in late flexion. There was no marked change in the coronal rotation angle of the mechanical axis during knee flexion. The femoral center moved anteriorly in early knee flexion and posteriorly in late flexion. The distance moved in the medial-lateral direction was relatively smaller than that in the anterior-posterior direction. Two-dimensional translation of the surgical epicondylar axis showed a medial pivot-like motion. In this cadaveric study, the kinematics of the native knee, including two-dimensional translation of the femur, could be satisfactorily assessed intraoperatively using a navigation system. The intraoperative kinematics of the knee can be analyzed in more detail using this methodology. J. Med. Invest. 66 : 367-371, August, 2019.

Total Knee Arthroplasty Kinematics

Knee kinematics is an analysis of motion pattern that is utilized to assess a comparative, biomechanical performance of healthy nonimplanted knees, injured nonimplanted knees, and various prosthetic knee designs. Unfortunately, a consensus between implanted knee kinematics and outcomes has not been reached. One might hypothesize that the kinematic variances between the nonimplanted and implanted knee might play a role in patient dissatisfaction following TKA. There is a wide range of TKA designs available today. With such variety, it is important for surgeons and engineers to understand the various geometries and kinematic profiles of available prostheses. The purpose of this review is to provide readers with the pertinent information related to TKA kinematics.

Preliminary study of a customised total knee implant with musculoskeletal and dynamic squatting simulation

Customised total knee replacement could be the future therapy for knee joint osteoarthritis. A preliminary design of a customised total knee implant based on knee anatomy was studied in this article. To evaluate its biomechanical performance, a dynamic finite element model based on the Oxford knee rig was created to simulate a squatting motion. Unlike previous research, this dynamic model was simulated with patient-specific muscle and joint loads that were calculated from an OpenSim musculoskeletal model. The dynamic response of the customised total knee implant was simulated under three cruciate ligament scenarios: both cruciate ligaments retained, only anterior cruciate ligament removed and both cruciate ligaments removed. In addition, an off-the-shelf symmetric total knee implant with retained cruciate ligaments was simulated for comparison analysis. The customised total knee implant with both cruciate ligaments retained showed larger ranges of femoral external rotation and posterior translation than the symmetric total knee implant. The motion of the customised total knee implant was also in good agreement with a healthy knee. There were no big differences in the tibiofemoral compressive forces in the customised total knee implant model under the three scenarios. These forces were generally consistent with other experimental and simulation results. However, the customised total knee implant design resulted in larger tibiofemoral compressive force than the symmetric total knee implant after 50° knee flexion, which was caused by the larger tibiofemoral relative motion.

Bicruciate-stabilised total knee arthroplasty provides good functional stability during high-flexion weight-bearing activities

PURPOSE

Bicruciate-stabilised total knee arthroplasty (BCS-TKA) uses a dual-post-cam mechanism as a substitute for the anterior cruciate ligament and posterior cruciate ligament (PCL), with the surface geometry providing additional guidance for axial rotation and posterior translation. However, the effect of weight-bearing on the kinematics of BCS-TKA has not been investigated. Therefore, the aim of this study was to clarify the effect of weight-bearing on the kinematics of BCS-TKA during high-flexion activities.

METHODS

The kinematics of 11 BCS-TKAs were evaluated under fluoroscopy, with two- and three-dimensional image registration, during squatting weight-bearing and active-assisted knee flexion non-weight-bearing. The following variables were measured: knee range of motion, axis of femoral rotation relative to the tibial component, anteroposterior (AP) translation of the medial contact point, kinematic path of the joint surfaces, lateral femorotibial contact point, and anterior and post-cam engagement.

RESULTS

The weight-bearing condition did not influence the range of knee flexion, axis of femoral rotation, medial pivot pattern during early flexion, or bicondylar rollback beyond mid-flexion. With regard to AP translation, both the medial and lateral contact points had more posterior locations in weight-bearing than in non-weight-bearing at the mid-flexion angle. Anterior engagement was identified in 6/11 knees (54.5%) in weight-bearing and 4/11 knees (36.3%) in non-weight-bearing. Post-cam engagement was observed in all knees, with the angle of flexion at engagement being larger in weight-bearing than in non-weight-bearing.

CONCLUSION

Although weight-bearing resulted in a posterior location of the medial and lateral contact points of the BCS-TKA design compared with non-weight-bearing in the mid-range of knee flexion, the amount of anterior translation was small overall. Therefore, BCS-TKA provides good stability during high-flexion weight-bearing activities. However, BCS-TKA is associated with high rate of the anterior engagement during early flexion. Therefore, understanding a patient's activities is an important factor when selecting the most appropriate TKA method.

Bony landmarks with tibial cutting surface are useful to avoid rotational mismatch in total knee arthroplasty

PURPOSE

The purpose of this study was to define various anteroposterior axes of the tibial component as references and to evaluate their accuracy and variability using virtual surgery. It was hypothesized that (1) Akagi's Line could result in high accuracy and low variability in varus osteoarthritic knees; (2) anteroposterior axes defined by using the tibial bony cutting surface as a landmark might be good substitutes for Akagi's Line; and (3) extra-articular bony landmarks might influence the variability of the anteroposterior axis.

METHODS

Three-dimensional bone models were reconstructed from the preoperative computed tomography data of 111 osteoarthritic knees with varus deformities. Seven different anteroposterior axes of the tibial component were defined: Akagi's Line, Axis MED, Axis 1/6MED, Axis 1/3MED, Axis of Oval Shape, Axis of Anterior Crest, and Axis Second Metatarsus. The rotational mismatch angle was measured between the tibial anteroposterior axis and the line perpendicular to the transepicondylar axis projected on the cutting surface (positive value: external rotation of the tibial anteroposterior axis).

RESULTS

The average rotational mismatch angles (referring to the projected anatomical/surgical epicondylar axes) were - 2.7° ± 5.8°/1.0° ± 6.0° (Akagi's Line), - 4.2° ± 7.7°/- 0.5° ± 7.8°, 2.9° ± 7.2°/6.6° ± 7.2°, 9.8° ± 7.0°/13.5° ± 6.8° (Axis MED, Axis 1/6MED, Axis 1/3MED), - 5.1° ± 7.9°/- 1.4° ± 7.8° (Axis of Oval Shape), and 19.3 ± 9.5°/23.0° ± 9.6°, - 2.0° ± 11.3°/1.7° ± 11.4° (Axis Anterior Crest, Axis Second Metatarsus), respectively.

CONCLUSIONS

Akagi's Line provided the best accuracy and least variability in varus osteoarthritic knees. Axis 1/6MED and Axis MED are good substitutes for Akagi's Line due to the difficulty of identifying the attachment site of the posterior cruciate ligament after the proximal tibia has been cut. Extra-articular bony landmarks should not be used for alignment due to their high variability. This study will aid surgeons in choosing the proper anteroposterior axis of the tibial component to reduce rotational mismatch and thus achieve good clinical knee outcomes.

LEVELS OF EVIDENCE

III.

The medial constrained insert restores native knee rotational kinematics after bicruciate-retaining total knee arthroplasty

PURPOSE

The aim of this study was to test the hypothesis that the medial constrained insert would reproduce the native knee kinematics after bicruciate-retaining (BCR) total knee arthroplasty (TKA).

METHODS

Using an image-free navigation system in six fresh-frozen whole-body cadavers, the rotation angle of the tibia at minimum flexion, at 10° intervals from 0° to 130° flexion, and at maximum flexion during manual passive knee flexion was assessed. The data was collected in native knees, in BCR TKA using a normal flat insert (BCR-XP), and in BCR TKA using a more constrained insert in the medial side (BCR-AS). The differences in the rotation angle of the tibia were statistically evaluated.

RESULTS

The rotation angles of the tibia in BCR-XP were significantly different from those of the native knees both in the early flexion phase (p = 0.002 at minimum knee flexion, p = 0.002 at 0°, p = 0.041 at 10°, p = 0.009 at 20°, p = 0.026 at 30°) and in the late flexion phase (p = 0.015 at 130°, p = 0.015 at maximum knee flexion), whereas the rotational angles of the tibia in BCR-AS were similar to those of the native knee.

CONCLUSION

This study shows that the rotational kinematics of the native knee is reproduced after BCR TKA with the medial constrained insert. Surgeons and implant designers should be aware that constraint of the medial side in BCR TKA is a crucial factor for restoration of native kinematics which may lead to better clinical outcome.

How prosthetic design influences knee kinematics: a narrative review of tibiofemoral kinematics of healthy and joint-replaced knees

INTRODUCTION

To improve the total knee arthroplasty (TKA) prosthesis design, it is essential to study the kinematics of the tibiofemoral joint. Many studies have been conducted in this area; however, conflicting results and incomparable testing methods make it difficult to draw definitive conclusions or compare research from studies. The goal of this article is to introduce what is known about both healthy and prosthetic tibiofemoral joint kinematics.

AREAS COVERED

Healthy tibiofemoral joint kinematics are reviewed in vivo by different activities, and the kinematics of existing knee prosthetic design features are considered separately. These features include but are not limited to cruciate retaining, posterior cruciate substituting, mobile-bearing, and high flexion.

EXPERT COMMENTARY

The type of activity that is being performed has a great influence on the kinematics of healthy knees, and the influences of different TKA prosthetic design features on the kinematics are complex and varied. Moreover, the TKA postoperative functional performance is influenced by many factors, and prosthetic design is among them, but not the only one that defines the performance.

Knee kinematics in bi-cruciate stabilized total knee arthroplasty during squatting and stair-climbing activities

This study aimed to evaluate clinical outcomes and in vivo kinematics of bi-cruciate stabilized (BCS) total knee arthroplasty (TKA), using image-matching techniques. We analyzed tibiofemoral anteroposterior translation, axial rotation, and anterior/posterior cam-post contact for 22 BCS TKAs during squatting and stair-climbing. The functional activities on the 2011 Knee Society Score were significantly improved from 36 to 71. The tibiofemoral translation and axial rotation during squatting/stair-climbing were 16.1 mm/7.1 mm and 2.5° external/1.1° internal, respectively. Anterior/posterior cam-post contacts were observed during squatting (14%/96%) and stair-climbing (27%/96%). In conclusion, BCS TKA produced physiological sagittal plane kinematics during activities with favorable clinical outcomes.

In vivo three-dimensional kinematics of normal knees during different high-flexion activities

Aims

In Asia and the Middle-East, people often flex their knees deeply in order to perform activities of daily living. The purpose of this study was to investigate the 3D kinematics of normal knees during high-flexion activities. Our hypothesis was that the femorotibial rotation, varus-valgus angle, translations, and kinematic pathway of normal knees during high-flexion activities, varied according to activity.

Materials and Methods

We investigated the in vivo kinematics of eight normal knees in four male volunteers (mean age 41.8 years; 37 to 53) using 2D and 3D registration technique, and modelled the knees with a computer aided design program. Each subject squatted, kneeled, and sat cross-legged. We evaluated the femoral rotation and varus-valgus angle relative to the tibia and anteroposterior translation of the medial and lateral side, using the transepicodylar axis as our femoral reference relative to the perpendicular projection on to the tibial plateau. This method evaluates the femur medially from what has elsewhere been described as the extension facet centre, and differs from the method classically applied.

Results

During squatting and kneeling, the knees displayed femoral external rotation. When sitting cross-legged, femurs displayed internal rotation from 10° to 100°. From 100°, femoral external rotation was observed. No significant difference in varus-valgus angle was seen between squatting and kneeling, whereas a varus position was observed from 140° when sitting cross-legged. The measure kinematic pathway using our methodology found during squatting a medial pivoting pattern from 0° to 40° and bicondylar rollback from 40° to 150°. During kneeling, a medial pivot pattern was evident. When sitting cross-legged, a lateral pivot pattern was seen from 0° to 100°, and a medial pivot pattern beyond 100°.

Conclusion

The kinematics of normal knees during high flexion are variable according to activity. Nevertheless, our study was limited to a small number of male patients using a different technique to report the kinematics than previous publications. Accordingly, caution should be observed in generalizing our findings.

Cite this article: Bone Joint J 2018;100-B:50–5.

Kinematic analysis of stair climbing in rotating platform cruciate-retaining and posterior-stabilized mobile-bearing total knee arthroplasties

INTRODUCTION

The aim of our study was to compare and contrast the effects of two types of mobile-bearing total knee arthroplasties (TKA), namely, the cruciate-retaining (CR) and posterior-stabilized (PS) TKAs, on clinical outcomes and in vivo kinematics during stair climbing.

MATERIALS AND METHODS

The Press-Fit Condylar Sigma rotating platform was used for both CR and PS TKAs. Patient-reported outcomes were assessed using the 2011 Knee Society Score. Quadriceps muscle strength was evaluated by isokinetic dynamometry. In vivo kinematics were evaluated using periodic sagittal plane radiographic images obtained during stair climbing to quantify anteroposterior (AP) tibiofemoral translation, implant flexion and axial rotation angles using image-matching techniques. Outcomes were evaluated in 20 TKAs, which had been undergone with clinical success, including ten knees with CR types and ten knees with PS types.

RESULTS

There were no significant differences between the CR and PS TKA groups (p > 0.05) in isometric extensor torque (1.0 ± 0.2 and 1.1 ± 0.6 N m/kg, respectively) or patient-reported score for stair climbing function (4.0 ± 0.5 and 3.8 ± 0.9, respectively). Both types of TKAs showed stable AP translation in the mid range of knee flexion and paradoxical translation in the low range of flexion, with limited rotation, during stair climbing. There were no significant differences between the CR and PS TKA groups (P > 0.05) in anterior translation from 80° to 40° of knee flexion (4.2 ± 1.2 and 3.5 ± 1.6 mm, respectively), posterior translation from 40° to 10° of knee flexion (2.3 ± 1.9 and 2.0 ± 1.5 mm, respectively), and total external rotation (2.8° ± 4.9° and 0.5° ± 5.0°, respectively).

CONCLUSIONS

Both CR and PS types of rotating platform mobile-bearing TKAs provided reproducible knee joint kinematics during stair climbing and equivalent clinical outcomes.

LEVEL OF EVIDENCE

IV.