Relative role changing of lateral collateral ligament on the posterolateral rotatory instability according to the knee flexion angles: a biomechanical comparative study of role of lateral collateral ligament and popliteofibular ligament

Outcome of percutaneous reconstruction of chronic lateral collateral ligament rupture

PURPOSE

Many techniques have been described for the reconstruction of chronic lateral collateral ligament (LCL) rupture with different autograft options. The advantages of percutaneous LCL reconstruction include small incisions, minimal soft tissue disruption, less postoperative pain, and speedy rehabilitation and recovery. The aim of this study was to report the functional outcome of percutaneous LCL reconstruction and overall patient satisfaction in Africans.

METHODS

This prospective and interventional study involving 51 patients with chronic LCL rupture who had percutaneous LCL reconstruction using peroneus longus autograft was conducted between January 2021 and December 2022 in National Orthopaedic Hospital, Dala-Kano, Nigeria. The inclusion criteria were patients between the ages of 18 and 45 years with chronic isolated LCL and not more than 1 injury of knee ligament. Exclusion criteria were active infection, and multi-ligament knee injury requiring 2-staged surgery. The knee functions were assessed preoperatively, 3 months, 6 months, and 12 months postoperatively using the Lysholm scoring system. Patient satisfaction with the outcome of the treatment was assessed using a 5-point Likert scale. Relevant information was recorded into Microsoft Excel sheet and data was analyzed using SPSS version 23.0 for windows. The paired samples t-test was used to compare the clinical outcomes as continuous variables. Statistical significance was considered at p < 0.05.

RESULTS

The mean age of the patients was (30.10 ± 5.90) years. The median time from injury to surgery was 7 months (ranging from 3 to 28 months). The mean follow-up period was (14.07 ± 3.13) months. The mean preoperative and 1-year postoperative Lysholm scores were 44.33 ± 12.97 and 97.96 ± 1.23, respectively.

CONCLUSION

Percutaneous LCL reconstruction using peroneus longus autograft significantly improves patient knee function and results in excellent patient satisfaction.

In vivo kinematical validated knee model for preclinical testing of total knee replacement

BACKGROUND AND OBJECTIVE

A computational knee model facilitates efficient component design evaluations and preclinical testing under various dynamic loadings. However, the development of a highly mimicked dynamic whole knee model with specified ligament constraints that provides high predictive accuracy with in-vivo experiments remains a challenge.

METHODS

In the present study, a musculoskeletal integrated force-driven explicit finite-element knee model with tibiofemoral and patellofemoral joints constrained with detailed soft tissue was developed. A proportional-integral-derivative controller was concurrently added to the knee model to track the boundary conditions. The actuations of the quadriceps and hamstrings were predicted via a subject-specific musculoskeletal model and matched with electromyography results.

RESULTS

Compared to in-vivo fluoroscopic results in a gait cycle, the predicted results of the kinematics of the tibiofemoral joint exhibited an agreement in terms of tendency and magnitude (anterior-posterior translation: RMSE = 1.1 mm, r² = 0.87; inferior-superior translation: RMSE = 0.83 mm, r² = 0.84; medial-lateral translation: RMSE = 0.82 mm, r² = 0.05; flexion-extension rotation: RMSE = 0.23°, r² = 1; internal-external rotation: RMSE = 1.85°, r² = 0.65; varus-valgus rotation: RMSE = 1.39°, r² = 0.08). Contact mechanics, including the contact area, pressure, and stress, were synchronously simulated on the tibiofemoral and patellofemoral joints.

CONCLUSIONS

The study provides a calibrated knee model and a kinematical validation approach that can be widely used in preclinical testing and knee prosthesis design.

Shear wave speeds track axial stress in porcine collateral ligaments

Ligament tension is an important factor that can affect the success of total knee arthroplasty (TKA) procedures. However, surgeons currently lack objective approaches for assessing tension in a particular ligament intraoperatively. The purpose of this study was to investigate the use of noninvasive shear wave tensiometry to characterize stress in medial and lateral collateral ligaments (MCLs and LCLs) ex vivo and evaluate the capacity of shear wave speed to predict axial load. Nine porcine MCL and LCL specimens were subjected to cyclic axial loading while shear wave speeds were measured using laser vibrometry. We found that squared shear wave speed increased linearly with stress in both the MCL (r²_avg = 0.94) and LCL (r²_avg = 0.98). Shear wave speeds were slightly lower in the MCL than the LCL when subjected to a comparable axial stress (p < 0.001). Specimen-specific calibrations predicted tension within 13.0 N, or 5.2% of the maximum load. A leave-one-out analysis was also performed and showed that calibrated relationships based on ligament type could predict axial tension within 15% of the maximum load. These observations suggest it may be feasible to use noninvasive shear wave speed measures as a proxy of ligament loading, which in the future might enhance decision making during orthopedic procedures such as TKA.

Lateral Collateral Ligament Injury About the Knee: Anatomy, Evaluation, and Management

The lateral collateral ligament is the primary varus stabilizer of the tibiofemoral joint. Diagnosing an injury to this ligament can be challenging in the setting of multiligamentous trauma; however, failure to recognize these injuries can result in instability of the knee and unsatisfactory outcomes after cruciate ligament reconstruction. Recent literature exploring the anatomy and biomechanics of the lateral collateral ligament has enhanced our understanding and improved diagnosis and management of these injuries. Physical examination and imaging studies also are important in diagnosis and can facilitate classification of lateral collateral ligament tears, which affects treatment decisions. Nonsurgical, reparative, and reconstructive techniques can all be used to manage lateral collateral ligament injury about the knee; the optimal treatment is selected on the basis of injury severity.

A Combined Experimental and Computational Approach to Subject-Specific Analysis of Knee Joint Laxity

Modeling complex knee biomechanics is a continual challenge, which has resulted in many models of varying levels of quality, complexity, and validation. Beyond modeling healthy knees, accurately mimicking pathologic knee mechanics, such as after cruciate rupture or meniscectomy, is difficult. Experimental tests of knee laxity can provide important information about ligament engagement and overall contributions to knee stability for development of subject-specific models to accurately simulate knee motion and loading. Our objective was to provide combined experimental tests and finite-element (FE) models of natural knee laxity that are subject-specific, have one-to-one experiment to model calibration, simulate ligament engagement in agreement with literature, and are adaptable for a variety of biomechanical investigations (e.g., cartilage contact, ligament strain, in vivo kinematics). Calibration involved perturbing ligament stiffness, initial ligament strain, and attachment location until model-predicted kinematics and ligament engagement matched experimental reports. Errors between model-predicted and experimental kinematics averaged <2 deg during varus-valgus (VV) rotations, <6 deg during internal-external (IE) rotations, and <3 mm of translation during anterior-posterior (AP) displacements. Engagement of the individual ligaments agreed with literature descriptions. These results demonstrate the ability of our constraint models to be customized for multiple individuals and simultaneously call attention to the need to verify that ligament engagement is in good general agreement with literature. To facilitate further investigations of subject-specific or population based knee joint biomechanics, data collected during the experimental and modeling phases of this study are available for download by the research community.

Kinematics of Different Components of the Posterolateral Corner of the Knee in the Lateral Collateral Ligament-intact State: A Human Cadaveric Study

PURPOSE

To determine the static stabilizing effects of different anatomical structures of the posterolateral corner (PLC) of the knee in the lateral collateral ligament (LCL)-intact state.

METHODS

Thirteen fresh-frozen human cadaveric knees were dissected and tested using an industrial robot with an optical tracking system. Kinematics were determined for 134 N anterior/posterior loads, 10 N m valgus/varus loads, and 5 N m internal/external rotatory loads in 0°, 20°, 30°, 60°, and 90° of knee flexion. The PLC structures were dissected and consecutively released: (I) intact knee joint, (II) with released posterior cruciate ligament (PCL), (III) popliteomeniscal fibers, (IV) popliteofibular ligament, (V) arcuat and popliteotibial fibers, (VI) popliteus tendon (PLT), and (VII) LCL. Repeated-measures analysis of variance was performed with significance set at P < .05.

RESULTS

After releasing the PCL, posterior tibial translation increased by 5.2 mm at 20° to 9.4 mm at 90° of joint flexion (P < .0001). A mild 1.8° varus instability was measured in 0° of flexion (P = .0017). After releasing the PLC structures, posterior tibial translation further increased by 2.9 mm at 20° to 5.9 mm at 90° of flexion (P < .05) and external rotation angle increased by 2.6° at 0° to 7.9° at 90° of flexion (P < .05, vs II). Varus stability did not decrease. Mild differences between states V and VI were found in 60° and 90° external rotation tests (2.1° and 3.1°; P < .05).

CONCLUSIONS

The connecting ligaments/fibers to the PLT act as a primary static stabilizer against external rotatory loads and a secondary stabilizer against posterior tibial loads (when PCL is injured). After releasing these structures, most static stabilizing function of the intact PLT is lost. The PLC has no varus-stabilizing function in the LCL-intact knee.

CLINICAL RELEVANCE

Anatomy and function of these structures for primary and secondary joint stability should be considered for clinical diagnostics and when performing surgery in the PLC.

Lateral soft-tissue structures contribute to cruciate-retaining total knee arthroplasty stability

Little information is available to surgeons regarding how the lateral structures prevent instability in the replaced knee. The aim of this study was to quantify the lateral soft-tissue contributions to stability following cruciate-retaining total knee arthroplasty (CR TKA). Nine cadaveric knees were tested in a robotic system at full extension, 30°, 60°, and 90° flexion angles. In both native and CR implanted states, ±90 N anterior-posterior force, ±8 Nm varus-valgus, and ±5 Nm internal-external torque were applied. The anterolateral structures (ALS, including the iliotibial band), the lateral collateral ligament (LCL), the popliteus tendon complex (Pop T), and the posterior cruciate ligament (PCL) were transected and their relative contributions to stabilizing the applied loads were quantified. The LCL was found to be the primary restraint to varus laxity (an average 56% across all flexion angles), and was significant in internal-external rotational stability (28% and 26%, respectively) and anterior drawer (16%). The ALS restrained 25% of internal rotation, while the PCL was significant in posterior drawer only at 60° and 90° flexion. The Pop T was not found to be significant in any tests. Therefore, the LCL was confirmed as the major lateral structure in CR TKA stability throughout the arc of flexion and deficiency could present a complex rotational laxity that cannot be overcome by the other passive lateral structures or the PCL. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1902-1909, 2017.

The arcuate ligament revisited: role of the posterolateral structures in providing static stability in the knee joint

PURPOSE

To determine the involvement of the posterolateral structures including the lateral collateral ligament, the popliteus muscle-tendon unit, the arcuate ligament (popliteofibular ligament, fabellofibular ligament, popliteomeniscal fascicles, capsular arm of short head of the biceps femoris and anterolateral ligament) and the posterior cruciate ligament in providing restraint to excessive recurvatum, tibial posterior translation and external tibial rotation at 90° of flexion.

METHODS

Ten fresh-frozen cadaveric knees were tested with dial test, posterior drawer test and recurvatum test. The values were collected, using a surgical navigation system, on intact knees, following a serial section of the posterolateral corner (lateral collateral ligament, arcuate ligament and popliteus muscle-tendon unit), followed by the additional section of the posterior cruciate ligament.

RESULTS

The mean tibial external rotation, recurvatum and posterior drawer were, respectively, measured at 9° ± 4°, 2° ± 3° and 9 ± 1 mm on intact knees. These values increase to 12° ± 5°, 3° ± 2° and 9 ± 1 mm after cutting the lateral collateral ligament; 17° ± 6° (p < 0.05), 3° ± 2° and 10 ± 1 mm after sectioning the arcuate ligament; 18° ± 7°, 3° ± 2° and 10 ± 1 mm after sectioning the popliteus muscle-tendon unit and 27° ± 6° (p < 0.05), 5° ± 3° (p < 0.05) and 28 ± 2 mm (p < 0.05) after the additional section of the posterior cruciate ligament.

CONCLUSION

Among the different structures of the posterolateral corner, only the arcuate ligament has a significant role in restricting excessive primary and coupled external rotation. The popliteus muscle-tendon unit is not a primary static stabilizer to tibial external rotation at 90° of knee flexion. The posterior cruciate ligament is the primary restraint to excessive recurvatum and posterior tibial translation. The posterior cruciate ligament and the arcuate ligament have predominant role for the posterolateral stability of the knee. The functional restoration of these ligaments is an important part of the surgical treatment of posterolateral ligamentous injuries.

Clinical biomechanics of instability related to total knee arthroplasty

BACKGROUND

Tibiofemoral instability is a common reason for total knee arthroplasty failure, and may be attributed to soft tissue deficiency and incorrect ligament balancing. There are many different designs of implant with varying levels of constraint to overcome this instability; however there is little advice for surgeons to assess which is suitable for a specific patient, and soft tissue balance testing during arthroplasty is very subjective.

METHOD

The current theories on primary and secondary soft tissue restraints to anterior/posterior, varus/valgus, and internal/external rotational motion of the knee are discussed. The paper reviews biomechanics literature to evaluate instability in the intact and implanted knee.

FINDINGS

The paper highlights important intra- and extra-capsular structures in the knee and describes the techniques used by clinicians to assess instability perioperatively. In vitro cadaveric studies were found to be a very useful tool in comparing different implants and contributions of different soft tissues.

INTERPRETATION

In vitro cadaveric studies can be utilised in helping less experienced surgeons with soft tissue releases and determining the correct implant. For this to happen, more biomechanical studies must be done to show the impact of release sequences on implanted cadavers, as well as determining if increasingly constrained implants restore the stability of the knee to pre-deficient conditions.