Axis location of tibial rotation and its change with flexion angle

Comparison of screw-home movement between patients with knee osteoarthritis and normal adults

BACKGROUND

Tibial rotation accompanying sagittal movement contains the phenomenon of screw-home movement (SHM) of the knee, which plays an important role in knee stability during extension.

OBJECTIVE

This study aimed to investigate the change of SHM in patients with knee osteoarthritis (OA).

METHODS

Thirty-one sex-matched patients with knee OA and 31 normal subjects were recruited. The total tibial rotation was obtained during knee sagittal movement (extension and flexion) using an inertial measurement unit. The acquired angle of tibial rotation was divided into eight periods. The total tibial rotation and the variation of each period were compared between the OA and control groups. The difference in tibial rotation according to Kellgren-Lawrence (KL) grade was compared.

RESULTS

The total tibial rotation of the OA group decreased compared with the control group during knee extension and flexion (P< 0.001). Variations of tibial rotation were significantly different between groups in all periods (P< 0.001) except for knee extension at 70∘ to 45∘ (P= 0.081). There was no significant difference in tibial rotations among the KA grades of OA patients.

CONCLUSION

We found a reduction in the total tibial rotation and loss of the SHM in the unloaded OA knee. It could be predicted that reduced SHM appeared early in knee OA.

Implant survival of 3rd-condyle and post-cam posterior-stabilised total knee arthroplasty are comparable at follow-up > 10 years: a systematic review

PURPOSE

To summarise the literature on 3rd-condyle total knee arthroplasty (TKA) designs and compare their survival rates to those of post-cam TKA designs. The null hypothesis was that 3rd-condyle TKAs would have equivalent survival rates compared to contemporary post-cam TKAs.

METHODS

An electronic literature search for Level I-V studies was independently conducted by two researchers using Medline^® and Web of Science for studies published between January 1984 and October 2020 that specifically reported on rates of implant survival and complications, joint kinematics, clinical outcomes, and radiographic outcomes of 3rd-condyle TKA. The methodological quality of clinical studies was assessed according to the Downs and Black Quality Checklist for Health Care Intervention Studies, and for in vitro and in silico studies according to the Joanna Briggs Institute (JBI) tool for assessing analytical cross-sectional studies. Findings extracted for each TKA design were presented as reported and synthesised narratively. Survival rates at 5, 10 and > 10 years of 3rd-condyle TKA designs were graphically compared to rates of post-cam TKA designs published in joint registries.

RESULTS

A total of 38 studies were identified that reported on kinematics, clinical outcomes, radiographic alignment, and rates of complications and survival. Mean survival rates ranged from 96 to 98% at 5 years, 78-100% at 5-10 years, and 86-99% at > 10 years for 3rd-condyle PS TKAs. Mean survival rates ranged from 93 to 98% at 5 years, 89-99% at 5-10 years, and 88-95% at > 10 years for post-cam PS TKAs.

CONCLUSION

Implant survival rates of 3rd-condyle TKAs are comparable to those of post-cam TKAs at follow-up > 10 years. When compared to post-cam PS TKA, 3rd-condyle designs offer an alternative for younger and more active patients when considering the added benefits of a lowered point-of-contact and larger congruent contact area at the intercondylar tibial sulcus, that reduce risks of loosening and component wear.

LEVEL OF EVIDENCE

V.

Comparison of screw-home mechanism in the unloaded living knee subjected to active and passive movements

BACKGROUND

The screw-home mechanism (SHM) plays an important role in the stability of the knee. Accordingly, the analysis of tibial rotation patterns can be used to elucidate the effect of SHM-related factors.

OBJECTIVE

The purpose of this study was to compare the magnitude of the angle and the pattern of SHM between passive and active movements.

METHODS

We studied twenty healthy males, of which the angle of knee flexion-extension and tibial longitudinal rotation (TLR) during active and passive movements were measured using the inertial measurement unit. Student's t-tests were used to compare the magnitude of TLR. The waveform similarity was quantified using a coefficient of multiple correlation (CMC).

RESULTS

Significant differences were found in the TLR between the active and passive movements (p< 0.05). The knee flexion-extension waveform similarity was excellent (CMC = 0.956). However, the waveform similarity of TLR was weak (CMC = 0.629).

CONCLUSION

The SHM increased abruptly during the last 20∘ of the active (extension) movement compared with passive extension. The SHM occurred mainly owing to the geometry and shape of the articular surfaces of the knee joint. In addition, muscle contraction was considered to be an important factor in the articulation movement.

A novel manual therapy technique is effective for short-term increases in tibial internal rotation range of motion

The coupled motions of tibial internal rotation (T-IR) and ankle dorsiflexion (DF) are necessary for proper lower-limb function. Anecdotally, clinicians have been performing techniques to restore T-IR to improve ankle DF, however, no evidence exists to support their efficacy. Therefore, the two objectives were to: (a) determine the effectiveness of a manual therapy technique for improving T-IR range of motion (ROM) and (b) Examine the relationship between ankle DF and T-IR ROM. Twenty-four participants qualified to participate and were randomly allocated to either the control (n=12) or manual therapy (n=12) group. Closed-chain ankle DF and T-IR ROM were assessed at baseline and immediately posttreatment. Control group participants sat quietly for 5 minutes. The experimental group performed 3 sets of 15 repetitions of a manual therapy, mobilization with movement technique. With the patient in a kneeling lunge position, the examiner wrapped an elastic band around the tibia and fibula and was instructed to lunge forward while the examiner simultaneously manually internally rotated the lower leg. T-IR ROM significantly increased following the intervention for the manual therapy group when compared to the control group. There were no significant changes in standing or kneeling DF ROM. No significant correlation was found between T-IR and both standing and kneeling DF ROM. A single mobilization with movement treatment is effective for improving tibial IR ROM in the short-term compared to no treatment. However, active tibial IR and end-range dorsiflexion range of motion do not appear to be correlated based on these methods.

Biomechanical Evidence on Anterior Cruciate Ligament Reconstruction

Objective  Anterior cruciate ligament (ACL) reconstruction is recommended in athletes with high physical demands. Several techniques are used in reconstruction; however, the most relevant question still is the best biomechanical positioning for the graft. The present study aimed to analyze the biomechanical effect of the position of bone tunnels on load distribution and joint kinetics, as well as the medium-term functional outcomes after ACL reconstruction.

Methods  A biomechanical study using a finite element model of the original knee (without anterior cruciate ligament rupture) and reconstruction of the ACL (neoACL) was performed in four combinations of bone tunnel positions (central femoral-central tibial, anterior femoral-central tibial, posterosuperior femoral-anterior tibial, and central femoral-anterior tibial) using the same type of graft. Each neo-ACL model was compared with the original knee model regarding cartilaginous contact pressure, femoral and meniscal rotation and translation, and ligamentous deformation.

Results  No neo-ACL model was able to fully replicate the original knee model. When the femoral tunnel was posteriorly positioned, cartilage pressures were 25% lower, and the mobility of the meniscus was 12 to 30% higher compared with the original knee model. When the femoral tunnel was in the anterior position, internal rotation was 50% lower than in the original knee model.

Conclusion  Results show that the femoral tunnel farther from the central position appears to be more suitable for a distinct behavior regarding the intact joint. The most anterior position increases rotational instability.

Influence of Component Rotation in Total Knee Arthroplasty on Tibiofemoral Kinematics-A Cadaveric Investigation

BACKGROUND

Physiological tibiofemoral kinematics have been shown to be important for good knee function after total knee arthroplasty (TKA). The purpose of the present study was to investigate the influence of component rotation on tibiofemoral kinematics during knee flexion. We asked which axial component alignment best reconstructs physiological tibiofemoral kinematics and which combinations should be avoided.

METHODS

Ten healthy cadaveric knees were examined. By means of a navigational device, tibiofemoral kinematics between 0° and 90° of flexion were assessed before and after TKA using the following different rotational component alignment: femoral components: ligament balanced, 6° internal, 3° external rotation, and 6° external rotation in relation to the posterior condylar line; tibial components: self-adapted, 6° internal rotation, and 6° external rotation.

RESULTS

Physiological tibiofemoral kinematics could be partly reconstructed by TKA. Ligament-balanced femoral rotation and 6° femoral external rotation both in combination with 6° tibial component external rotation, and 3° femoral external rotation in combination with 6° tibial component internal rotation or self-aligning tibial component were able to restore tibial longitudinal rotation. Largest kinematical differences were found for the combination femoral component internal and tibial component external rotations.

CONCLUSION

From a kinematic-based view, surgeons should avoid internal rotation of femoral components. However, even often recommended combinations of rotational component alignment (3° femoral external and tibial external rotation) significantly change tibiofemoral kinematics. Self-aligning tibial components solely restored tibiofemoral kinematics with the combination of 3° femoral component of external rotation. For the future, navigational devices might help to axially align components to restore patient-specific and natural tibiofemoral kinematics.

Anatomical Characteristics and Biomechanical Properties of the Oblique Popliteal Ligament

This anatomical study sought to investigate the morphological characteristics and biomechanical properties of the oblique popliteal ligament (OPL). Embalmed cadaveric knees were used for the study. The OPL and its surrounding structures were dissected; its morphology was carefully observed, analyzed and measured; its biomechanical properties were investigated. The origins and insertions of the OPL were relatively similar, but its overall shape was variable. The OPL had two origins: one originated from the posterior surface of the posteromedial tibia condyle, merged with fibers from the semimembranosus tendon, the other originated from the posteromedial part of the capsule. The two origins converged and coursed superolaterally, then attached to the fabella or to the tendon of the lateral head of the gastrocnemius and blended with the posterolateral joint capsule. The OPL was classified into Band-shaped, Y-shaped, Z-shaped, Trident-shaped, and Complex-shaped configurations. The mean length, width, and thickness of the OPL were 39.54, 22.59, and 1.44 mm, respectively. When an external rotation torque (18 N·m) was applied both before and after the OPL was sectioned, external rotation increased by 8.4° (P = 0.0043) on average. The OPL was found to have a significant role in preventing excessive external rotation and hyperextension of the knee.

Intra-operative navigation of knee kinematics and the influence of osteoarthritis

Intra-operative assessment of knee kinematics should optimise implantation of total knee arthroplasties. The purpose of this work was to validate the data delivered by an adapted navigation system in 10 healthy cadaver knees and to investigate the kinematics of 10 osteoarthritic (OA) knees in patients undergoing total knee replacement. The system displayed the magnitude of axial rotation, the position of the instantaneous centre of axial rotation and the displacements of the condyles. Successive cycles from full extension to 140° of flexion in the same knee produced a mean external rotation of 20° ± 10°, which was correlated to knee flexion (r=0.6 ± 0.2 in healthy knees, r=0.8 ± 0.2 in OA knees). The centre of axial rotation migrated posteriorly an average of 8.2mm in both groups. The posterior displacements were 4 mm ± 5 mm in healthy and 5 mm ± 6 mm in OA knees for the medial condyle, and 21 mm ± 9 mm in healthy and 21 mm ± 10 mm in OA knees for the lateral condyle. The medial condyle lifted off beyond 110° of flexion. Results in healthy knees were consistent with those reported in the current literature. The kinematics of healthy and of OA knees with an intact anterior cruciate ligament did not differ significantly.

Influence of the anteromedial and posterolateral bundles of the anterior cruciate ligament on external and internal tibiofemoral rotation

BACKGROUND

The influence of the anteromedial and posterolateral bundles of the anterior cruciate ligament on tibiofemoral rotation might be of great value to detect anterior cruciate ligament injuries and investigate the postoperative restoration of rotational stability.

HYPOTHESIS

The anterior cruciate ligament and especially the posterolateral bundle will have a significant influence on isolated tibiofemoral rotation.

STUDY DESIGN

Controlled laboratory study.

METHODS

Tibiofemoral rotation was measured in 20 human cadaveric knees using a noninvasive external measurement device (Rotameter) and a knee navigation system. The measurements of the knees with the intact anterior cruciate ligament were compared with the measurements after isolated resection of the posterolateral bundle and after a complete resection of the anterior cruciate ligament at an applied torque of 5,10, and 15 N.m. Statistical analysis was made using analysis of variance and the post hoc Scheffé test. The Pearson coefficient was used to compare both measurement techniques.

RESULTS

In comparison with knees with an intact anterior cruciate ligament, the knees after isolated resection of the posterolateral bundle showed significant increase of tibiofemoral rotation at almost all applied torques (P <.05). Total resection of the anterior cruciate ligament also produced significant increases compared with the intact anterior cruciate ligament at torques of 5, 10, and 15 N.m as measured by the Rotameter (P <.05). Total resection of the anterior cruciate ligament yielded increases in rotation compared with posterolateral bundle resection alone, but these differences were not significant. The results of the knee navigation system confirmed the measured results of the Rotameter. Comparison of the 2 measurement methods revealed a high correlation at all applied torques, with Pearson correlation coefficients ranging from .85 to .95.

CONCLUSION

The anterior cruciate ligament and especially the posterolateral bundle of the anterior cruciate ligament have a significant effect on isolated tibiofemoral rotation. Therefore, the developed noninvasive device might be of great importance to investigate the status and the postoperative reconstruction of the anterior cruciate ligament in the clinical setting.

CLINICAL RELEVANCE

Noninvasive measurement of tibiofemoral rotation might be useful to detect anterior cruciate ligament tears and to evaluate the restoration of rotational stability after anterior cruciate ligament surgery.

A new model to predict in vivo human knee kinematics under physiological-like muscle activation

Although a number of approaches have attempted to model knee kinematics, rarely have they been validated against in vivo data in a larger subject cohort. Here, we assess the feasibility of four-bar linkage mechanisms in addressing knee kinematics and propose a new approach that is capable of accounting for lengthening characteristics of the ligaments, including possible laxity, as well as the internal/external rotation of the joint. MR scans of the knee joints of 12 healthy volunteers were taken at flexion angles of 0 degrees , 30 degrees and 90 degrees under both passive and active muscle conditions. By reconstructing the surfaces at each position, the accuracy of the four-bar linkage mechanism was assessed for every possible combination of points within each cruciate ligament attachment area. The specific set of parameters that minimized the deviation between the predictions and the in vivo pose was derived, producing a mean error of 1.8 and 2.5 on the medial and 1.7 and 2.4mm on the lateral side at 30 degrees and 90 degrees flexion, respectively, for passive motion, significantly improving on the models that did not consider internal/external rotation. For active flexion, mean medial errors were 3.3 and 4.7 mm and lateral errors 3.4 and 4.8 mm. Using this best parameter set, a generic predictive model was created and assessed against the known in vivo positions, producing a maximum average error of 4.9 mm at 90 degrees flexion. The accuracy achieved shows that kinematics may be accurately reconstructed for subject specific musculoskeletal models to allow a better understanding of the load distribution within the knee.

Human patellar tendon moment arm length: measurement considerations and clinical implications for joint loading assessment

Detailed understanding of the knee joint loading requires the calculation of muscle and joint forces in different conditions. In these applications the patellar tendon moment arm length is essential for the accurate estimation of the tibiofemoral joint loading. In this article, different methods that have been used to determine the patellar tendon moment arm length under in vivo and in vitro conditions are reviewed. The limitations and advantages associated with each of the methods are evaluated together with their applications in the different loading conditions that the musculoskeletal system is subjected to. The three main measurement methods that this review considers are the geometric method, the tendon excursion method and the direct load method. A comparison of relevant quantitative results is presented to asses the impact of the errors of each method on the quantification of the patellar tendon moment arm and the implications for joint loading assessment in clinical applications.

Lateral unicompartmental knee arthroplasty: survivorship and technical considerations at an average follow-up of 12.4 years

Successful medial unicompartmental knee arthroplasty is becoming standard; however, the "screw-home" mechanism, internal femoral rotation on a fixed tibia as the knee is fully extended, should be taken into account with lateral compartment arthroplasty. Twenty-nine consecutive lateral unicompartmental arthroplasties were performed with our unique tibial component positioning in 10 degrees to 15 degrees of internal rotation to compensate for the "screw-home" mechanism. The Hospital for Special Surgery knee score and serial radiographs were used in the evaluation of each patient. The mean duration of follow-up was 12.4 years with no revisions. The HSS score was excellent or good in all knees. The average postoperative femoral-tibial alignment was 5 degrees of valgus, and the average posterior tibial slope was 6 degrees . Lateral unicompartmental arthroplasty can provide excellent long-term results with modified positioning of the tibial component.

Cruciate coupling and screw-home mechanism in passive knee joint during extension–flexion

The screw-home mechanism and coupling between forces in cruciate ligaments during passive knee joint flexion were investigated for various boundary conditions, flexion axis alignments and posterior cruciate ligaments (PCL)/anterior cruciate ligament (ACL) conditions. A developed non-linear 3D finite element model was used to perform detailed elasto-static response analyses of the human tibiofemoral joint as a function of flexion angle varying from 10 degrees hyper-extension to 90 degrees flexion. The tibia rotated internally as the femur flexed and externally as the femur extended. The re-alignment of the flexion axis by +/-5 degrees rotation about the axial (distal-proximal) axis, transection of the ACL and changes in cruciate ligament initial strains substantially influenced the 'screw-home' motion. On the other hand, restraint on this coupled rotation diminished ACL forces in flexion. A remarkable coupling was predicted between ACL and PCL forces in flexion; forces in both cruciate ligaments increased as the initial strain or pretension in one of them increased whereas they both diminished as one of them was cut or became slack. This has important consequences in joint functional biomechanics following a ligament injury or replacement surgery and, hence, in the proper management of joint disorders.

Factors for the presence of anteromedial rotatory instability of the knee

Anteromedial rotatory instability (AMRI) of the knee joint was investigated with an instrument newly designed to simulate the manual AMRI test and to quantify its magnitude. Thirty healthy subjects, 20 patients with anterior cruciate ligament (ACL) injury, and 10 with both ACL and medial collateral ligament (MCL) injuries were examined. Using the instrument, 100 N of anterior force was applied to the proximal part of the tibia with the foot in neutral rotation, 30 degrees of internal rotation, and 30 degrees of external rotation, and the magnitude of anterior displacement was recorded. The measurement was carried out at 20 degrees and 90 degrees of flexion. A significant increase in anterior laxity was observed in all three rotation positions in the injured patients. However, the magnitude of laxity in external rotation was less than that in neutral rotation in the ACL injured patients, whereas it was the greatest in external rotation in ACL + MCL injured patients. Thus, we conclude that an injury involving both the ACL and MCL causes AMRI.

Establishment of a Knee-Joint Coordinate System From Helical Axes Analysis—A Kinematic Approach Without Anatomical Referencing

This study establishes a functional knee-joint coordinate system (FCS) derived from active motion. The scale invariant properties of helical axes were used in order to avoid inter-observer errors associated with the traditional anatomical referencing techniques. The algorithm was tested with six cadaveric specimens in a knee-joint motion and loading apparatus. To determine the FCS sensitivity to variable loading, rotational moments were applied to the tibia while extending and flexing the knee. Each derived FCS was compared with the clinically derived anatomical coordinate system (ACS). The FCS was reproducible when the loading condition was the same. Changing the rotational moments from internal to external affected the orientations and the positions of the FCS. The largest displacement of 20.8 mm in average occurred in the medio/lateral direction. The FCS corresponded with the ACS for all specimens and loading conditions. The origin was always located within the femur along the transepicondylar line. The orientations differed less than 16.6 degrees in average, thus allowing the use of clinical terminology. These findings suggest that the FCS might improve the ability to clinically assess kinematic alterations provided that the reference motion is reproducible.

Development of the concepts of knee kinematics

OBJECTIVES

To review the experimental evidence and development of concepts in knee kinematics and to present a synthesis of current theories.

DATA SOURCES

Historical literature from private collections and published journals, from Galen in 160 AD, and Weber and Weber in 1860, through to current research in knee kinematics, sourced through MEDLINE and CINAHL.

STUDY SELECTION

Studies of the healthy human knee in vivo and in vitro were included. Other studies were included when relevant, for example, when knee surgery methods have led to a change in kinematic concepts. Of 285 items, 94 were included based on their contribution to original research. When relevant, authors were contacted to resolve issues.

DATA EXTRACTION

Sources included were descriptive studies, anatomic dissections, controlled experimental designs, editorials, and review articles.

DATA SYNTHESIS

The axes of rotation of the knee are fundamental to kinematic models. The hinge model is contradicted by the ellipsoid shape of the femoral condyles, which results in a moving instant center of motion. However, the "instant center of motion" model was based on analysis of sagittal sections, oblique to the plane of movement and neglecting rotation. The four-bar linkage theory linked cruciate ligament isometry with the roll and glide pattern of knee motion. Recently, however, studies of the biomechanics and histology of the knee ligaments have enabled more accurate kinematic modeling. Three-dimensional imaging and computer modeling have made possible analysis of kinematics parallel to the planes of motion and incorporation of conjoint rotation. Femoral roll back is now described as the manifestation of longitudinal rotation during knee flexion.

CONCLUSIONS

Current research concludes that the knee has 4 independent axes: patella, posterior condylar, distal condylar, and longitudinal axes. The axes combine to produce the characteristic helical motion of the knee.

In vivo three-dimensional knee kinematics using a biplanar image-matching technique

A biplanar image-matching technique was developed and applied to a study of normal knee kinematics in vivo under weightbearing conditions. Three-dimensional knee models of six volunteers were constructed using computed tomography. Projection images of the models were fitted onto anteroposterior and lateral radiographs of the knees at hyperextension and every 15 degrees from 0 degrees to 120 degrees flexion. Knee motion was reconstructed on the computer. The femur showed a medial pivoting motion relative to the tibia during knee flexion, and the average range of external rotation associated with flexion was 29.1 degrees . The center of the medial femoral condyle translated 3.8 mm anteriorly, whereas the center of the lateral femoral condyle translated 17.8 mm posteriorly. This rotational motion, with a medially offset center, could be interpreted as a screw home motion of the knee around the tibial knee axis and a posterior femoral rollback in the sagittal plane. However, the motion of the contact point differed from that of the center of the femoral condyle when the knee flexion angle was less than 30 degrees. Within this range, medial and lateral contact points translated posteriorly, and a posterior femoral rollback occurred. This biplanar image-matching technique is useful for investigating knee kinematics in vivo.