The Medial Collateral Ligament in Primary Total Knee Arthroplasty: Anatomy, Biomechanics, and Injury

Combined Medial Collateral Ligament Reconstruction and Polyethylene Exchange for Valgus Instability Following Total Knee Arthroplasty

Valgus instability can occur after total knee arthroplasty (TKA) due to traumatic medial collateral ligament (MCL) injury, component malpositioning, or progressive ligamentous laxity. Although revision TKA with exchange of the polyethylene to a varus-valgus-constrained liner can reduce laxity due to MCL insufficiency, isolated liner exchange in the setting of collateral ligament insufficiency may lead to greater strain at the cement-bone or implant-cement interface and possibly a greater rate of aseptic loosening. Anatomic MCL reconstruction can be performed in conjunction with liner exchange to restore stability and reduce strain compared with liner exchange alone. The purpose of this Technical Note is to describe a technique for MCL reconstruction and liner exchange for treatment of valgus instability after TKA.

Intraoperative Medial Instability During Total Knee Arthroplasty

A review article summarizes the existing literature on intraoperative injury to medial collateral ligament (MCL) during total knee arthroplasty (TKA), methods of fixation, repair, and the outcomes after these injuries. The options for increasing implant constraint and repair of the MCL injury are discussed with the potential indications for each. There is also a review of risk factors for MCL injury during TKA to help anticipate potential issues preoperatively. The proper use of retractors during total knee replacement is also discussed with a focus on careful protection of the MCL during surgery.

Medial stability and lateral flexibility of the collateral ligaments during mid-range flexion in medial-pivot total knee arthroplasty patients demonstrates favorable postoperative outcomes

PURPOSE

The objectives of the present study were to investigate the length change in different bundles of the superficial medial collateral ligament (sMCL) and lateral collateral ligament (LCL) during lunge, and to evaluate their association with Knee Society Score (KSS) following medial-pivot total knee arthroplasty (MP-TKA).

METHODS

Patients with unilateral MP-TKA knees performed a bilateral single-leg lunge under dual fluoroscopy surveillance to determine the in-vivo six degrees-of-freedom knee kinematics. The contralateral non-operated knees were used as the control group. The attachment sites of the sMCL and LCL were marked to calculate the 3D wrapping length. The sMCL and LCL were divided into anterior, intermediate, and posterior portions (aMCL, iMCL, pMCL, aLCL, iLCL, pLCL). Correlations between lengths/elongation rate of ligament bundles from full extension to 100° flexion and the KSS were examined.

RESULTS

The sMCL and LCL demonstrated relative stability in length at low flexion, but sMCL length decreased whereas LCL increased with further flexion on operated knees. The sMCL length increased at low flexion and remained stable with further flexion, while the LCL length decreased with flexion on the contralateral non-operated knees. The lengths of aMCL, iMCL, and pMCL showed moderate (0.5 < r < 0.7, p < 0.05) negative correlations with the KSS, and the lengths of aLCL, iLCL, and pLCL were positively correlated with the KSS at mid flexion on operated knees (p < 0.05). The elongation rates of aLCL, iLCL, and pLCL were negatively correlated with the KSS at high flexion on operated knees (p < 0.05). However, no significant correlations between the length of different bundles of sMCL or LCL with KSS were found on contralateral non-operated knees.

CONCLUSIONS

The elongation pattern of sMCL/LCL on MP-TKA knees showed differences with contralateral non-operated knees. The sMCL is tense at low to middle flexion and relaxed at high flexion, while LCL is relaxed at low to middle flexion and tense at high flexion following MP-TKA. Medial stability and proper lateral flexibility during mid flexion were associated with favorable postoperative outcomes in MP-TKA patients. In contrast, lateral relaxation at deep flexion should be avoided when applying soft-tissue balancing in MP-TKA.

LEVEL OF EVIDENCE

Level III.

Knee valgus deformity and lateral bone defects affect the function of superficial medial collateral ligament: A finite element analysis

Purpose

The superficial medial collateral ligament (sMCL) is the primary restraint to valgus laxity of the knee, which is one of the significant indicators of implant selection in valgus knee. Our purpose is to explore the influence of knee valgus deformity and lateral bone defects in the function of sMCL.

Methods

the right knee joint of a healthy male volunteer was subjected to CT and MRI scans. The scanned data were imported into Mimics, Geomagic, Solidworks and Ansys software to establish a three-dimensional finite element model of the human knee joint. Femorotibial angle (FTA)5°,10°,15°,20°,25°,30°,35° and lateral bone defect 0,0.5,1,1.5,2 cm are controlled in Solidworks. Tensile test in vitro of maximum load on sMCL was simulated in Ansys.

Results

The peak stress of sMCL is raising with valgus deformity while there is no lateral defect. Increasing lateral bone defect can lessen the augmentation of the stress of sMCL caused by the valgus deformity. The peak stress of sMCL when it is in maximum load is 35.252 MPa. While valgus 35°, the peak stress of sMCL exceeds the value, with or without bone defect; the same is true for the valgus 30° with 0, 0.5, 1 cm bone defect and valgus 25° without defect.

Conclusion

Our findings allow for preoperative evaluation of sMCL function in the valgus knee, which would play an instructive role to some extent for implant selection in total knee arthroplasty.

Impact of increasing total knee replacement constraint within a single implant line on coronal stability: an ex vivo investigation

INTRODUCTION

Despite the existence of diverse total knee implant designs, few data is available on the relationship between the level of implant constraint and the postoperative joint stability in the frontal plane and strain in the collateral ligaments. The current study aimed to document this relation in an ex vivo setting.

MATERIALS AND METHODS

Six fresh-frozen lower limbs underwent imaging for preparation of specimen-specific surgical guides. Specimens were dissected and assessed for joint laxity using the varus-valgus stress tests at fixed knee flexion angles. A handheld dynamometer applied tensile loads at the ankle, thereby resulting in a knee abduction-adduction moment of 10 Nm. Tibiofemoral kinematics were calculated using an optical motion capture system, while extensometers attached to medial collateral (MCL) and lateral collateral ligament (LCL) measured strain. Native joint testing was followed by four TKA designs from a single implant line-cruciate retaining, posterior stabilised, varus-valgus constrained and hinged knee (HK)-and subsequent testing after each implantation. Repeated measures linear mixed-models (p < 0.05) were used to compare preoperative vs. postoperative data on frontal plane laxity and collateral ligament strain.

RESULTS

Increasing implant constraint reduced frontal plane laxity across knee flexion, especially in deep flexion (r² > 0.76), and MCL strain in extension; however, LCL strain reduction was not consistent. Frontal plane laxity increased with knee flexion angle, but similar trends were inconclusive for ligament strain. HK reduced joint laxity and ligament strain as compared to the native condition consistently across knee flexion angle, with significant reductions in flexion (p < 0.024) and extension (p < 0.001), respectively, thereby elucidating the implant design-induced joint stability. Ligament strain exhibited a strong positive correlation with varus-valgus alignment (r² = 0.96), notwithstanding knee flexion angle or TKA implant design.

CONCLUSION

The study demonstrated that increasing the constraint of a TKA resulted in lower frontal plane laxity of the knee. With implant features impacting laxity in the coronal plane, consequentially affecting strain in collateral ligaments, surgeons must consider these factors when deciding a TKA implant, especially for primary TKA.

LEVEL OF EVIDENCE

V.

Medial Collateral Ligament and Posterior Oblique Ligament Reconstruction for Valgus Instability After Total Knee Arthroplasty

Medial collateral ligament (MCL) injuries are typically managed non-operatively, with high rates of clinical success. However, patients who present with medial knee laxity with valgus stress testing of a fully extended knee, anteromedial rotatory instability, associated tibial plateau fracture, or multiligament injury or those who continue to be symptomatic after non-operative treatment may benefit from surgical intervention. Patients with a history of total knee arthroplasty who suffer MCL and posterior oblique ligament (POL) injuries represent a challenging patient population and often require surgical attention. In this Technical Note, we describe the preoperative assessment, decision making, and surgical technique for anatomic reconstruction of the superficial MCL and POL with an Achilles allograft in young, active patients with medial-sided knee injuries after total knee arthroplasty.

[Effectiveness analysis of lateral condyle sliding osteotomy in total knee arthroplasty for the treatment of lateral femoral bowing deformity]

OBJECTIVE

To investigate the effectiveness of lateral condyle sliding osteotomy (LCSO) in total knee arthroplasty (TKA) for the treatment of lateral femoral bowing deformity.

METHODS

The clinical data of 17 patients with lateral femoral bowing deformity treated by LCSO during TKA between July 2018 and July 2020 was retrospectively analysed. There were 3 males and 14 females, with an average of 63.2 years (range, 58-68 years). The etiology of lateral femoral bowing deformity included 12 cases of femoral developmental deformity and 5 cases of femoral fracture malunion. Kellgren-Lawrence classification of knee osteoarthritis was 4 cases of grade Ⅲ and 13 cases of grade Ⅳ. The preoperative hip-knee shaft was 9.5°-12.5° (mean, 10.94°). The disease duration was 3-25 years (mean, 15.1 years). The mechanical lateral distal femur angle (mLDFA), hip-knee-ankle angle (HKA), and mechanical axis deviation (MAD) of the distal femur were measured before operation and at last follow-up to evaluate the correction of extra-articular deformities in the joints and the recovery of mechanical force lines of the lower extremities. The knee society score (KSS) knee score and function score, visual analogue scale (VAS) score, knee joint range of motion (ROM) were used to evaluate effectiveness. The knee varus/valgus stress test and osteotomy healing by X-ray films were performed to evaluate the joint stability and the safety of LCSO.

RESULTS

All incisions of the patients healed by first intention after operation, and there was no early postoperative complication such as infection of the incision and deep vein thrombosis of the lower extremities. All 17 patients were followed up 12-36 months, with an average of 23.9 months. The osteotomy slices all achieved bony healing, and the healing time was 2-5 months, with an average of 3.1 months. After operation, the knee varus/valgus stress tests were negative, and there was no relaxation and rupture of the lateral collateral ligament, instability of the knee joint, loosening, revision and infection of the prosthesis occurred. At last follow-up, mLDFA, HKA, MAD, knee ROM, VAS score, KSS knee score and function score significantly improved when compared with preoperative ones ( P<0.05).

CONCLUSION

LCSO is effective and safe in TKA with lateral femoral bowing deformity. Extra-articular deformities are corrected intra-articularly. The mechanical force line and joint balance of the lower extremities can be restored simultaneously in an operation.

Impact of intraoperative medial collateral ligament injury on outcomes after total knee arthroplasty: a meta-analysis and systematic review

BACKGROUND

As an uncommon but severe complication, medial collateral ligament (MCL) injury in total knee arthroplasty (TKA) may be significantly under-recognized. We aimed to determine whether MCL injury influences postoperative outcomes of patients undergoing TKA.

METHODS

Two independent reviewers searched PubMed, Cochrane Library, and EMBASE from their inception to July 1, 2021. The main outcomes were postoperative function, and secondary outcomes included the incidences of revision and complications.

RESULTS

A total of 403 articles yielded 15 studies eligible for inclusion with 10 studies used for meta-analysis. This study found that there was a statistically significant difference in postoperative functional scores, range of motion (ROM), complications, and revision rates, with adverse outcomes occurring more commonly in patients with MCL injury.

CONCLUSIONS

This meta-analysis highlights the complexity of MCL injury during TKA and shows the impact on postoperative function, joint mobility, complications, and revision. Surgeons need to prevent and put more emphasis on MCL injury during TKA.