Tibial Internal-external Rotation Research Articles

Poster 265: Bony Morphology Is a Poor Predictor of Anterior Cruciate Ligament Elongation During High Demand Activities

Objectives: Bony morphology has been proposed as a potential risk factor for anterior cruciate ligament (ACL) injury. There have been several reports on the relationship between bony morphology and knee kinematics, however, no reports have investigated if knee bony morphological parameters that are associated with knee kinematics are also associated with ACL elongation. The purpose of this study was to determine if bony morphological parameters that have been associated with ACL injury risk and knee kinematics are also predictive of ACL elongation during fast running and double-legged drop jump. Our hypothesis was that a steeper lateral posterior tibial slope (LPTS), a deeper medial tibial plateau (MTP) depth, and a larger lateral femoral condyle anteroposterior width (LCAP)/ lateral tibial plateau anteroposterior width (TPAP) (LCAP/ TPAP) would predict more ACL elongation during high demand activities. Methods: Written informed consent was obtained from 19 healthy collegiate athletes with no history of knee injury who were active in sports that require running, jumping, and/or cutting (11 males and 8 females). Both knees were imaged within a biplane radiography imaging system (150 images/sec, 90kV, 160mA, 1ms exposure) for three trials per knee during fast running (5.0m/s on an instrumented treadmill) and double-legged drop jump off a 60cm platform. Tibiofemoral motion was tracked using a previously validated volumetric model-based tracking process that matched CT based subject-specific 3D bone models to the synchronized biplane radiographs to measure knee kinematics with an accuracy of 0.7 mm in translation and 0.9° in rotation. ACL elongation was measured as the distance between the femoral and tibial ACL attachment points, identified on magnetic resonance imaging (MRI) and registered to the CT based subject-specific 3D bones. Bony morphological parameters of LPTS, MTP depth, and LCAP/ TPAP were measured on MRI using Mimics version 24.0 (Materialise, Leuven, Belgium) as previously reported (Figure 1) and input to a multiple linear regression model to predict knee kinematics (the range of tibial internal-external rotation and the range of tibial anteroposterior translation) and ACL elongation at 3 instants during each activity (0%, 30%, and 60% of the stance phase in fast running and 0%, 50%, and 100% of the stance phase in double-legged drop jump). Significance level was set as P < 0.05. Results: Participant’s average age was 20.1±1.3 years and the mean BMI was 24.0±2.8 kg/m2. The mean LPTS was 4.7±1.8°, the mean MTP depth was 1.8±0.5 mm, and the mean LCAP/TPAP was 1.5±0.1. None of the bony morphology features predicted ACL elongation or knee kinematics during fast running (Tables 1, 2). During double-legged drop jump, deeper MTP predicted greater ACL elongation at toe off of the drop jump (β= 0.456, p= 0.006) (Table 1). In contrast, several bone morphology parameters predicted knee kinematics: A steeper LPTS and a deeper MTP depth predicted a greater range of tibiofemoral internal/external rotation (β= 0.382, p= 0.012 and β= 0.331, p= 0.028, respectively) and shallower MTP depth and a larger LCAP/TPAP predicted a greater range of anterior tibial translation (β= -0.352, p= 0.018 and β= 0.441, p= 0.005, respectively) during drop jump (Table 2). Conclusions: As in previous reports, bony morphology predicted knee kinematics, but only during the double-legged drop jump activity. However, contrary to our hypothesis, only at toe-off during the double-legged drop jump, when the knee was maximally extended, a deeper MTP depth was associated with greater ACL elongation. These findings suggest that bone morphology features that are associated with kinematics that in isolation increase ACL elongation ( e.g., anterior tibial translation) may not predict ACL elongation during high demand activities. The lack of association between ACL relative elongation and bony morphology during fast running may be due to the overriding influence of large forces applied to the knee during flexion immediately after foot strike. These results are limited to healthy athletes performing fast running and drop jump activities in a controlled laboratory setting, and to knees with relatively normal bony morphology. In conclusion, previously reported relationships between bony morphology and kinematics or ACL injury risk should not be extrapolated to suggest that those bone morphology features are also associated with ACL elongation during high demand activities.

Significantly better precision with new machine learning versus manual image registration software in processing images from single-plane fluoroscopy to determine tibiofemoral kinematics following total knee replacement.

One common method to determine tibiofemoral kinematics following total knee replacement (TKR) is to capture single-plane fluoroscopic images of a patient activity and determine anterior-posterior (AP) positions of the femoral condyles and internal-external (IE) tibial rotation. Although JointTrack is widely used to analyze such images, precision (i.e. repeatability) in determining AP positions and IE tibial rotations using the two publicly available programs has never been quantified. The objectives were to determine the precision and reproducibility of results using both programs. Fluoroscopic images of 16 patients who performed a weight-bearing deep knee bend following TKR were analyzed. JointTrack Manual (JTM) and JointTrack Machine Learning (JTML) were used to perform 3D model-to-2D image registration after which AP positions of the femoral condyles and IE tibial rotations were determined. Precision in AP positions and IE rotations was quantified. Intraclass correlation coefficients (ICCs) for both repeatability (i.e. intraobserver) and reproducibility (i.e. interobserver) also were determined. Precision using JTM was worse than JTML for AP positions of the medial and lateral femoral condyles (1.0 mm and 0.9 mm vs 0.3 mm and 0.4 mm, respectively; p < 0.001 for both). For IE tibial rotation, precision also was worse using JTM versus JTML (1.1º vs 0.9°, p = 0.010). ICC values for JTML indicated good to excellent agreement (range: 0.82-0.98) whereas ICC values for JTM indicated only moderate to good agreement (range: 0.58-0.88). JTML has better precision and reproducibility than JTM and also is more efficient to use. Therefore, use of JTML over JTM is strongly recommended.

Joint Coordinate System Using Functional Axes Achieves Clinically Meaningful Kinematics of the Tibiofemoral Joint as Compared to the International Society of Biomechanics Recommendation.

Quantification of clinically meaningful tibiofemoral motions requires a joint coordinate system (JCS) with motions free from kinematic crosstalk errors. The objectives were to use a JCS with literature-backed functional axes (FUNC) and a JCS recommended by the International Society of Biomechanics (ISB) to determine tibiofemoral kinematics of the native (i.e., healthy) knee, determine variability associated with each JCS, and determine whether the FUNC JCS significantly reduced kinematic crosstalk errors compared to the ISB JCS. Based on a kinematic model consisting of a three-cylindric joint chain, the FUNC JCS included functional flexion-extension (F-E) and internal-external (I-E) tibial rotation axes. In contrast, the ISB JCS included F-E and I-E axes defined using anatomic landmarks. Single-plane fluoroscopic images in 13 subjects performing a weighted deep knee bend were analyzed. Tibiofemoral kinematics using the FUNC JCS fell within the physiological range of motion in all six degrees-of-freedom. Internal tibial rotation averaged 13 deg for the FUNC JCS versus 10 deg for the ISB JCS and motions in the other four degrees-of-freedom (collectively termed off-axis motions) were minimal as expected based on biomechanical constraints. Off-axis motions for the ISB JCS were significantly greater; maximum valgus rotation was 4 deg and maximum anterior and distraction translations were 9 mm and 25 mm, respectively, which is not physiologic. Variabilities in off-axis motions were significantly greater with the ISB JCS (p < 0.0002). The FUNC JCS achieved clinically meaningful kinematics by significantly reducing kinematic crosstalk errors and is the more suitable coordinate system for quantifying tibiofemoral motions.

Optimized Joint Coordinate System Achieves Clinically Meaningful Kinematics of the Tibiofemoral Joint as Compared to the International Society of Biomechanics (ISB) Recommendation.

Quantification of clinically meaningful tibiofemoral motions requires a coordinate system where motions are free from kinematic crosstalk errors. The objectives were to 1) develop an algorithm for assigning an optimized joint coordinate system (OPT JCS) that minimizes kinematic crosstalk errors based on a kinematic model of the tibiofemoral joint, 2) determine tibiofemoral kinematics of the native (i.e. healthy) knee during deep knee bend using OPT JCS and a coordinate system recommended by the International Society of Biomechanics (ISB JCS), and 3) determine whether OPT JCS significantly reduces kinematic crosstalk errors compared to ISB JCS. A novel algorithm was developed for assigning a patient-specific, OPT JCS based on a two rotational degree-of-freedom kinematic model, which included flexion-extension and internal-external tibial rotation axes. Single-plane fluoroscopic images of native knees of 13 subjects performing deep knee bend were analyzed to show that tibiofemoral kinematics using OPT-JCS fell within the physiological range of motion in all six degrees of freedom. Internal rotation of the tibia with respect to the femur averaged 11 deg and off-axis motions were minimal as expected based on biomechanical constraints. In contrast, off-axis motions for ISB JCS were non-physiologic; maximum valgus rotation was 12 deg, maximum posterior translation was 12 mm, and maximum distraction translation was 28 mm. Hence, an optimized JCS achieved clinically meaningful kinematics by significantly reducing kinematic crosstalk errors compared to the ISB recommendation and is the more suitable coordinate system for evaluating tibiofemoral joint function.

In vivo comparison of rotating platform and fixed bearing knee replacements during lunge and pivot activities

BackgroundThe objective of this study was to discover whether notable differences in mobile and fixed-bearing kinematics occur during activity that promotes tibial rotation, and to compare these results with normal healthy kinematics. We hypothesized that rotating-platform knee replacements would exhibit greater rotation of the tibia relative to the fixed-bearing knee replacements. Materials and MethodsThe in vivo motion of the tibia relative to the femur was measured in subjects with posterior stabilized fixed-bearing (FB) and rotating-platform (RP) total knee arthroplasties using a high-speed stereo radiography system during a lunge and gait with a change in direction (pivot). ResultsThe in vivo internal/external (IE) rotation and anterior/posterior translation of the tibia relative to the femur was similar between mobile and fixed-bearing total knee prostheses during two activities of daily living that included an activity that challenged tibial IE rotation. Measurements of IE rotation in participants with RP had higher variability and significantly greater range between maximum internal and external rotation compared with FB participants. The greater amount of variability of RP was not unlike the healthy knee. ConclusionThe pattern of IE rotation and AP translation for both RP and FB designs were similar to healthy kinematics but with less IE rotation. The RP implants more closely replicated the asymmetrical posterior condylar translation and range of IE rotation of the healthy knee during activity that challenged tibial IE rotation.

Six-Degree-of-Freedom Tibiofemoral and Patellofemoral Joint Motion During Activities of Daily Living.

The purpose of this study was to measure the three-dimensional movements of the femur, tibia and patella in healthy young people during activities of daily living. A mobile biplane X-ray imaging system was used to obtain simultaneous measurements of six-degree-of-freedom (6-DOF) tibiofemoral and patellofemoral kinematics and femoral condylar motion in ten participants during standing, level walking, downhill walking, stair ascent, stair descent and open-chain (non-weightbearing) knee flexion. Seven of the eleven secondary motions at the knee-three translations at the tibiofemoral joint, three translations at the patellofemoral joint, and patellar flexion-were coupled to the tibiofemoral flexion angle (r2 ≥ 0.71). Tibial internal-external rotation, tibial abduction-adduction, patellar rotation, and patellar tilt were each weakly related to the tibiofemoral flexion angle (r2 ≤ 0.45). The displacements of the femoral condyles were also coupled to the tibiofemoral flexion angle (r2 ≥ 0.70), with the lateral condyle translating further on the tibial plateau than the medial condyle. The center of rotation of the tibiofemoral joint in the transverse plane was located on the medial side in all activities. These findings expand our understanding of the kinematic function of the healthy knee and may be relevant to a range of applications in biomechanics, including the design of prosthetic knee implants and the development of knee models for use in full-body simulations of movement.

Age-Related Changes in In-Vivo 3D Knee Kinematics during Knee Joint Flexion Observed using 2D/3D Registration Technique

We aimed to identify 3D motion differences in knee joint articular surface kinematics in healthy young and old participants during weight-bearing knee flexion. Twelve healthy male volunteers, six in their 60s and six in their 20s, without any musculoskeletal system disease involving the knees participated. 3D bone models of the femur and tibia were obtained using CT and matched into the fluoroscopic images captured during split squatting. Translation and rotation of the tibia to the femur during weight-bearing flexion were compared between the groups. Translation of the nearest medial-lateral articular surface location and rotational angle of medial-lateral connecting lines were also compared. As the tibial internal-external rotation angle and medial contact point anterior-posterior translation were significantly correlated between the groups, they could not represent the characteristics of age-related changes. Similar to lateral contact point translation and contact points line angles were significantly different during the initial 10° flexion period. At the 40°-45° knee flexion period, a significant difference was detected in the contact point line angle and in the tibial superior-inferior translation. 3D knee joint kinematic differences between participants in their 20s and 60s, especially during initial and 40°-45° periods, can predict kinematic effects on age-related disease.

Kinematic alignment in total knee arthroplasty better reproduces normal gait than mechanical alignment.

Kinematic alignment technique for TKA aims to restore the individual knee anatomy and ligament tension, to restore native knee kinematics. The aim of this study was to compare parameters of kinematics during gait (knee flexion-extension, adduction-abduction, internal-external tibial rotation and walking speed) of TKA patients operated by either kinematic alignment or mechanical alignment technique with a group of healthy controls. The hypothesis was that the kinematic parameters of kinematically aligned TKAs would more closely resemble that of healthy controls than mechanically aligned TKAs. This was a retrospective case-control study. Eighteen kinematically aligned TKAs were matched by gender, age, operating surgeon and prosthesis to 18 mechanically aligned TKAs. Post-operative 3D knee kinematics analysis, performed with an optoelectronic knee assessment device (KneeKG®), was compared between mechanical alignment TKA patients, kinematic alignment TKA patients and healthy controls. Radiographic measures and clinical scores were also compared between the two TKA groups. The kinematic alignment group showed no significant knee kinematic differences compared to healthy knees in sagittal plane range of motion, maximum flexion, abduction-adduction curves or knee external tibial rotation. Conversely, the mechanical alignment group displayed several significant knee kinematic differences to the healthy group: less sagittal plane range of motion (49.1° vs. 54.0°, p = 0.020), decreased maximum flexion (52.3° vs. 57.5°, p = 0.002), increased adduction angle (2.0-7.5° vs. - 2.8-3.0°, p < 0.05), and increased external tibial rotation (by a mean of 2.3 ± 0.7°, p < 0.001). The post-operative KOOS score was significantly higher in the kinematic alignment group compared to the mechanical alignment group (74.2 vs. 60.7, p = 0.034). The knee kinematics of patients with kinematically aligned TKAs more closely resembled that of normal healthy controls than that of patients with mechanically aligned TKAs. This may be the result of a better restoration of the individual's knee anatomy and ligament tension. A return to normal gait parameters post-TKA will lead to improved clinical outcomes and greater patient satisfaction. III.

Comparison of Kinematics in Cruciate Retaining and Posterior Stabilized for Fixed and Rotating Platform Mobile-Bearing Total Knee Arthroplasty with respect to Different Posterior Tibial Slope.

Reconstructed posterior tibial slope (PTS) plays a significant role in kinematics restoration after total knee arthroplasty (TKA). However, the effect of increased and decreased PTS on prosthetic type and design has not yet been investigated. We used a finite element model, validated using in vitro data, to evaluate the effect of PTS on knee kinematics in cruciate-retaining (CR) and posterior-stabilized (PS) fixed TKA and rotating platform mobile-bearing TKA. Anterior-posterior tibial translation and internal-external tibial rotation were investigated for PTS ranging from -3° to 15°, with increments of 1°, for three different designs of TKA. Tibial posterior translation and external rotation increased as the PTS increased in both CR and PS TKAs. In addition, there was no remarkable difference in external rotation between CR and PS TKAs. However, for the mobile-bearing TKA, PTS had less effect on the kinematics. Based on our computational simulation, PTS is the critical factor that influences kinematics in TKA, especially in the CR TKA. Therefore, the surgeon should be careful in choosing the PTS in CR TKAs.

The influence of geometric design variables on the kinematic performance of a surface-guided total knee replacement.

Tibiofemoral geometries in a total knee replacement (TKR) affect the performance of an implant during activities of daily living. The specially shaped components of a surface-guided TKR aim to control the tibiofemoral motion, such that a normal pattern of motion is achieved, even at high flexion angles. The purpose of this study was to assess the influence of the design parameters on the kinematic behavior of such an implant. A combination of design variables was determined that resulted in the least deviation from the design kinematic target. Six major design variables were considered to generate customized surface-guided TKR candidates. The contribution of these variables was evaluated by principal component analysis considering the input design variables and the results of the kinematic performance from a virtual simulation of deep squatting. The tibial internal-external rotation and the anterior-posterior translation of the medial and lateral femoral condyles were recorded for each design candidate. A quantified objective function of the kinematic behavior was used to define the design with a maximum agreement with the target pattern of motion. The location and orientation of the flexion-extension axis and the tibial slope were the most contributing parameters on the modes of variation. On the other hand, the conformity between the lateral guiding arcs had the least contribution. Virtual simulation showed that the current TKR reached deep flexion angles under squat load, while the tibia pivoted around the medial center. The tibial rotation was within the expected range of the IE rotation from healthy joints.

Posteromedial Meniscocapsular Lesions Increase Tibiofemoral Joint Laxity With Anterior Cruciate Ligament Deficiency, and Their Repair Reduces Laxity

Background: Injury to the posteromedial meniscocapsular junction has been identified after anterior cruciate ligament (ACL) rupture; however, there is a lack of objective evidence investigating how this affects knee kinematics or whether increased laxity can be restored by repair. Such injury is often overlooked at surgery, with possible compromise to results. Hypotheses: (1) Sectioning the posteromedial meniscocapsular junction in an ACL-deficient knee will result in increased anterior tibial translation and rotation. (2) Isolated ACL reconstruction in the presence of a posteromedial meniscocapsular junction lesion will not restore intact knee laxity. (3) Repair of the posteromedial capsule at the time of ACL reconstruction will reduce tibial translation and rotation to normal. (4) These changes will be clinically detectable. Study Design: Controlled laboratory study. Methods: Nine cadaveric knees were mounted in a test rig where knee kinematics were recorded from 0° to 100° of flexion by use of an optical tracking system. Measurements were recorded with the following loads: 90-N anterior-posterior tibial forces, 5-N·m internal-external tibial rotation torques, and combined 90-N anterior force and 5-N·m external rotation torque. Manual Rolimeter readings of anterior translation were taken at 30° and 90°. The knees were tested in the following conditions: intact, ACL deficient, ACL deficient and posteromedial meniscocapsular junction sectioned, ACL deficient and posteromedial meniscocapsular junction repaired, ACL patellar tendon reconstruction with posteromedial meniscocapsular junction repair, and ACL reconstructed and capsular lesion re-created. Statistical analysis used repeated-measures analysis of variance and post hoc paired t tests with Bonferroni correction. Results: Tibial anterior translation and external rotation were both significantly increased compared with the ACL-deficient knee after posterior meniscocapsular sectioning (P < .05). These parameters were restored after ACL reconstruction and meniscocapsular lesion repair (P > .05). Conclusion: Anterior and external rotational laxities were significantly increased after sectioning of the posteromedial meniscocapsular junction in an ACL-deficient knee. These were not restored after ACL reconstruction alone but were restored with ACL reconstruction combined with posterior meniscocapsular repair. Tibial anterior translation changes were clinically detectable by use of the Rolimeter. Clinical Relevance: This study suggests that unrepaired posteromedial meniscocapsular lesions will allow abnormal meniscal and tibiofemoral laxity to persist postoperatively, predisposing the knee to meniscal and articular damage.

Motion of the femoral condyles in flexion and extension during a continuous lunge.

Numerous studies have reported on in-vivo posterior femoral condyle translations during various activities of the knee. However, no data has been reported on the knee motion during a continuous flexion-extension cycle. Further, few studies have investigated the gender variations on the knee kinematics. This study quantitatively determined femoral condylar motion of 10 male and 10 female knees during a continuous weightbearing flexion-extension cycle using two-dimensional to three-dimensional fluoroscopic tracking technique. The knees were CT-scanned to create three-dimensional models of the tibia and femur. Continuous images of each subject were taken using a single-fluoroscopic imaging system. The knee kinematics were measured along the motion path using geometric center axis of the femur. The results indicated that statistical differences between the flexion and extension motions were only found in internal-external tibial rotation and lateral femoral condylar motion at the middle range of flexion angles. At low flexion angles, male knees have greater external tibial rotation and more posteriorly positioned medial femoral condyle than females. The knee did not show a specific pivoting type of rotation with flexion. Axial rotation center varied from lateral to medial compartments of the knee. These data could provide useful information for understanding physiological motion of normal knees.

Is there a gold standard for TKA tibial component rotational alignment?

Joint function and durability after TKA depends on many factors, but component alignment is particularly important. Although the transepicondylar axis is regarded as the gold standard for rotationally aligning the femoral component, various techniques exist for tibial component rotational alignment. The impact of this variability on joint kinematics and stability is unknown. We determined how rotationally aligning the tibial component to four different axes changes knee stability and passive tibiofemoral kinematics in a knee after TKA. Using a custom surgical navigation system and stability device to measure stability and passive tibiofemoral motion, we tested 10 cadaveric knees from five hemicorpses before TKA and then with the tibial component aligned to four axes using a modified tibial tray. No changes in knee stability or passive kinematics occurred as a result of the four techniques of tibial rotational alignment. TKA produces a 'looser' knee over the native condition by increasing mean laxity by 5.2°, decreasing mean maximum stiffness by 4.5 N·m/°, increasing mean anterior femoral translation during passive flexion by 5.4 mm, and increasing mean internal-external tibial rotation during passive flexion by 4.8°. However, no statistically or clinically important differences occurred between the four TKA conditions. For all tibial rotations, TKA increased laxity, decreased stiffness, and increased tibiofemoral motion during passive flexion but showed little change based on the tibial alignment. Our observations suggest surgeons who align the tibial component to any of the axes we examined are expected to have results consistent with those who may use a different axis.

A Clinical Device for Measuring Internal-External Rotational Laxity of the Knee

Background: The dial test can be improved by providing reproducible, accurate measurements to improve diagnosis and treatment comparisons. Purpose: Validation of a rotational measurement device (RMD) for measuring knee internal-external rotational laxity. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: The RMD consisted of 3 components: a femoral clamp and a tibial splint using paired inclinometers to measure rotations, and a boot to apply tibial internal-external rotation torque. A separate boot inclinometer allowed for foot rotations to be measured independently. The measurements were simultaneously compared with electromagnetic “nest of birds” (NOB) sensors. Sequential paired knee measurements were taken at 4, 6, and 8 N·m of torque at 30° and 90° of flexion in 46 volunteers. Results: The correlation coefficient was 0.92 (95% CI, 0.89 to 0.94) and 0.63 (95% CI, 0.54 to 0.70) between the NOB and RMD and between the NOB and boot inclinometer, respectively. Bland-Altman analysis revealed that the RMD was on average within 2° (95% CI, 1° to −4°) of NOB readings, whereas the boot overestimated by 34° (95% CI, −9° to −58°). Maximum side-to-side differences measured by the NOB, RMD, and boot were 1°, 3°, and 21°, respectively. The mean +2× standard deviation data gave a range of side-to-side differences of less than 5° for the RMD. The intraobserver intraclass correlation was 0.9 (95% CI, 0.78 to 0.97) at both 30° and 90° of flexion, and the 95% CI of the differences between readings taken on 2 occasions, the interobserver repeatability, was 1° or less. Conclusion: The novel clinical RMD for measuring rotational laxity of the knee was portable, easy, and comfortable to use in the clinical setting. The RMD showed significant correlation and accuracy compared with sensors of known high accuracy. Side-to-side differences of less than 5° were found in 95% of normal knees, compared with differences of 13° or more for clinical diagnosis of pathological rotational laxity. Measuring knee rotation at the foot showed poor correlation and accuracy.

The functions of the fibre bundles of the anterior cruciate ligament in anterior drawer, rotational laxity and the pivot shift

This paper reviews the functional anatomy of the anterior cruciate ligament (ACL), which has a parallel array of collagen fascicles that have usually been divided into two 'fibre bundles': anteromedial (AM) and posterolateral (PL), according to their tibial attachment sites. The PL bundle has shorter fibres, and so it is subjected to greater tensile strains than the AM bundle when the whole ACL is stretched; its oblique orientation in the coronal plane imbues it with greater ability to resist tibial rotation than the more vertical AM fibre bundle. Most studies have found that the AM bundle is close to isometric when the knee flexes, while the PL bundle slackens approximately 6mm. There is little evidence of significant fibre bundle elongation in response to tibial rotation. Selective bundle cutting studies have been performed, allowing both the bundle tensions and their contributions to resisting tibial anterior translation and tibial rotation to be calculated. These show that the function of the PL bundle was dominant near knee extension in some studies, particularly when resisting anterior drawer and that its contribution reduced rapidly with knee flexion through 30 degrees. There has been little study of the contributions of the fibre bundles in control of tibial internal-external rotation or the pivot shift: one study found that the AM bundle had larger tensions than the PL bundle during a simulated pivot shift, but another study found that cutting the PL bundle allowed a larger increase in coupled tibial anterior translation than cutting the AM bundle. It was concluded that the AM bundle is most important for resisting tibial anterior drawer-the primary function of the ACL-while the PL bundle is tight near knee extension, when it has a role in control of tibial rotational laxity. There is a clear need for further study of dynamic knee instability, to gain better understanding of how best to reconstruct the ACL and associated tissues.

Tibial rotation in anterior cruciate ligament reconstructed knees during single limb hop and drop landings

BackgroundAlterations in knee joint kinematics have been suggested as a potential mechanism that influences the development of osteoarthritis of the knee after anterior cruciate ligament reconstruction. Whilst previous work has shown changes in internal–external tibial rotation during level walking, many patients aim to return to high impact activities following surgery. This study examined tibial rotation during single limb hop and drop landings in anterior cruciate ligament reconstructed knees compared to a control group, and also evaluated the influence of graft type (hamstring or patellar tendon). MethodsIn 48 participants (17 patellar tendon graft, 18 hamstring graft and 13 controls) internal–external rotation was measured during single limb hop and drop landings in a gait laboratory at mean of 10months after surgery. FindingsThere was no difference between the two graft types and both patient groups had less internal rotation when compared to the control group. For 60% of patients, internal rotation values were at least 5° less than the control group mean. InterpretationAnterior cruciate ligament reconstructed knees with both hamstring tendon and patellar tendon grafts show altered rotational kinematic patterns during high impact dynamic load activities.

Tibial Rotation Under Combined In Vivo Loading After Single- and Double-Bundle Anterior Cruciate Ligament Reconstruction

To evaluate in vivo the differences in tibial rotation between single- and double-bundle anterior cruciate ligament (ACL)-reconstructed knees under combined loading conditions. An 8-camera optoelectronic system and a force plate were used to collect kinematic and kinetic data from 14 patients with double-bundle ACL reconstruction, 14 patients with single-bundle reconstruction, 12 ACL-deficient subjects, and 12 healthy control individuals while performing 2 tasks. The first included walking, 60° pivoting, and stair ascending, and the second included stair descending, 60° pivoting, and walking. The 2 variables evaluated were the maximum range of internal-external tibial rotation and the maximum knee rotational moment. Tibial rotation angles were not significantly different across the 4 groups (P = .331 and P = .851, respectively) or when side-to-side differences were compared within groups (P = .216 and P = .371, respectively) for the ascending and descending maneuvers, nor were rotational moments among the 4 groups (P = .418 and P = .290, respectively). Similarly, for the descending maneuver, the rotational moments were not significantly different between sides (P = .192). However, for the ascending maneuver, rotational moments of the affected sides were significantly lower by 20.5% and 18.7% compared with their intact counterparts in the single-bundle (P = .015) and double-bundle (P = .05) groups, respectively. High-intensity activities combining stair ascending or descending with pivoting produce similar tibial rotation in single- and double-bundle ACL-reconstructed patients. During such maneuvers, the reconstructed knee may be subjected to significantly lower rotational loads compared with the intact knee. Level III, retrospective comparative study.

Correlation of axial impact forces with knee joint forces and kinematics during simulated ski-landing

Anterior cruciate ligament (ACL) rupture, during ski-landing, is caused by excessive knee joint forces and kinematics, like anterior tibial translation, internal tibial rotation, and valgus rotation. It is not well understood how these forces/kinematics are directly related to ski-landing impact. In the present study, we applied simulated ski-landing impact to knee specimens, and examined joint force/kinematic responses and their correlations with impact force. Ten human cadaveric knees were subjected to axial impact loading at 70° of flexion to simulate ski-landing impact. Impact was repeated with incremental magnitude until ACL failure. Axial impact forces, anterior-posterior and medial-lateral tibial forces were measured using a tri-axial load cell. Anterior-posterior tibial translation, internal-external tibial rotation, and valgus-varus rotation were determined using a motion-capture system. We found positive correlations of axial impact force with anterior tibial force, medial tibial force, anterior tibial translation, internal tibial rotation, and valgus joint rotation. Axial impact forces were more strongly correlated with anterior tibial forces (R 2 = 0.937 ± 0.050), anterior tibial translation (R 2 = 0.916 ± 0.059), and internal tibial rotation (R 2 = 0.831 ± 0.141) than medial tibial force (R 2 = 0.677 ± 0.193) and valgus joint rotation (R 2 = 0.630+0.271). During ski-landing, these joint forces/kinematics can synergistically act to increase ACL injury risk, whereby the failure mechanism would be dominated by anterior tibial forces, anterior tibial translation, and internal tibial rotation.

Stress changes of lateral collateral ligament at different knee flexion with or without displaced movements: a 3-dimensional finite element analysis

Objective To create a 3-dimensional finite element model of knee ligaments and to analyse the stress changes of lateral collateral ligament (LCL) with or without displaced movements at different knee flexion conditions. Methods A four-major-ligament contained knee specimen from an adult died of skull injury was prepared for CT scanning with the detectable ligament insertion footprints, locations and orientations precisely marked in advance. The CT scanning images were converted to a 3-dimensional model of the knee with the 3-dimensional reconstruction technique and transformed into finite element model by the software of ANSYS. The model was validated using experimental and numerical results obtained by other scientists. The natural stress changes of LCL at five different knee flexion angles (0°, 30°, 60°, 90°, 120°) and under various motions of anterior-posterior tibial translation, tibial varus rotation and internal-external tibial rotation were measured. Results The maximum stress reached to 87%-113% versus natural stress in varus motion at early 30° of knee flexions. The stress values were smaller than the peak value of natural stress at 0° (knee full extension) when knee bending was over 60° of flexion in anterior-posterior tibial translation and internal-external rotation. Conclusion LCL is vulnerable to varus motion in almost all knee bending positions and susceptible to anterior-posterior tibial translation or internal-external rotation at early 30° of knee flexions.

Evaluation of tibial rotational stability of single-bundle vs. anatomical double-bundle anterior cruciate ligament reconstruction during a high-demand activity — A quasi-randomized trial

The purpose of this study was to compare the tibial rotational stability of anatomical double-bundle anterior cruciate ligament reconstructed knees with single-bundle anterior cruciate ligament reconstructed knees during a high-demand activity. Total of 66 subjects, (22 with double-bundle anterior cruciate ligament reconstruction, 22 with single-bundle anterior cruciate ligament reconstruction, and 22 healthy control individuals) were examined in this study. Using a 9-camera motion analysis system, motion subjects were recorded performing during a drop landing and cutting. Using the point cluster technique, the internal-external tibial rotation of both knees was calculated. The mean maximum range of motion for each knee was evaluated for 3 groups (double-bundle group, single-bundle group, and control group). Clinical assessment, including Tegner score, Lysholm score, and knee arthrometric measurement, revealed restoration of the reconstructed knee stability with no differences between the two anterior cruciate ligament reconstruction groups. The results showed that both groups resulted in tibial rotation values that were significantly smaller than those in the intact legs and those in the healthy controls. There were no significant differences in tibial rotation between the DB group and the SB group. Therefore anatomical double-bundle reconstruction restores normal tibial rotation no more than single-bundle reconstruction during this high-demand dynamic activity. These results suggest a trend towards dynamic overcorrection after the ACL reconstruction.