Medial Collateral Ligament Repair With Internal Suture Brace Augmentation in Total Knee Arthroplasty

Abstract

Medial collateral ligament (MCL) insufficiency during or after total knee arthroplasty (TKA) is a challenging scenario that often necessitates constrained implants or allograft reconstruction. This series describes 3 patients who underwent MCL repair with internal suture brace augmentation (ISBA). Two patients (ages 54 and 51) had chronic valgus instability after primary TKA and were treated with revision surgery using a more constrained implant or liner plus ISBA. A third patient (age 77) sustained an intraoperative MCL disruption during primary TKA and was managed acutely with ISBA. At 12–34.5 months of follow-up, all patients achieved full motion and medial stability. ISBA provided soft-tissue reinforcement and may represent a useful adjunct for medial instability, though its long-term effectiveness remains uncertain.

Introduction

Medial collateral ligament (MCL) instability after total knee arthroplasty (TKA) is a rare but challenging complication that can lead to valgus instability, gap mismatch, and eventual failure of the prosthesis [1,2]. The MCL provides restraint to valgus stress throughout the arc of motion, with peak tension in mid-flexion (around 30°) and continued contribution to stability in both deeper flexion and full extension [3]. The superficial MCL is the primary restraint to valgus stress throughout the range of motion (ROM), while the deep MCL, closely associated with the joint capsule and medial meniscus, functions as a secondary stabilizer, contributing to control of external rotation and fine-tuning valgus stability, particularly in flexion [4]. MCL injuries can be acute, often due to iatrogenic damage during surgery, or chronic, resulting from progressive ligament insufficiency. Treatment options vary and may include polyethylene liner exchange, ligament repair, graft augmentation, or revision to a more constrained implant [[5], [6], [7]].

Highly constrained implants can restore coronal stability in cases of MCL deficiency, but their use may increase stress at the implant-bone or implant-cement interface, potentially leading to early loosening or mechanical failure [8,9]. In contrast, primary repair or reinforcement of the native ligament may offer a soft tissue–preserving alternative in select patients.

Internal suture brace augmentation (ISBA) using high-strength suture has shown favorable outcomes in the management of multiligamentous knee injuries [10,11], but its role in arthroplasty has not been well established. To our knowledge, no prior clinical series has described the use of ISBA for MCL insufficiency during or after TKA. We present 3 patients—2 with chronic medial laxity following TKA and one with acute intraoperative MCL injury—who were treated with MCL repair and ISBA in combination with appropriate implant selection. The goal of this series is to illustrate how ISBA may be integrated into surgical decision-making for medial instability after TKA.

Case reports

Case 1

A 54-year-old man presented with pain and valgus instability 7 months after a right TKA. His history included anterior cruciate ligament reconstruction in his early 20s and knee arthroscopy 2 years before TKA for loose body and osteophyte removal. He reported progressive pain, swelling, and instability requiring a knee brace. Examination revealed grade 3 medial laxity at 30° flexion and a 5° flexion contracture with flexion to 120° (Supplementary Video 1). Imaging showed well-fixed implants with mild medial opening, and infection workup was negative (Fig. 1). After failing conservative management, he underwent revision to a Stryker Triathlon TS+ (transitional-stabilized) polyethylene insert (Stryker Orthopaedics, Mahwah, NJ, USA) and MCL repair with ISBA (Fig. 2). The internal suture brace was placed and tensioned after the final polyethylene insert was implanted, as residual medial laxity was observed intraoperatively. At 34.5 months postoperatively, he had no pain, a ROM of 0° to 115°, and stable gaps throughout motion.

Figure 1.

Preoperative anteroposterior radiograph of both knees (Case 1) demonstrating well-fixed femoral and tibial components in the right total knee arthroplasty, without evidence of loosening. Mild medial joint space widening is suggestive of valgus instability.

Figure 2.

Postoperative anteroposterior radiograph (Case 1) showing retained femoral and tibial components with a newly inserted posterior-stabilized polyethylene liner. Medial joint space and alignment appear restored.

Case 2

A 51-year-old woman developed pain and knee instability 3 years after cemented TKA. Her history included a prior supracondylar femur fracture treated with open reduction and internal fixation, later converted to a TKA with partial hardware removal. Following the conversion, mild instability symptoms were noted and gradually progressed, ultimately leading to revision TKA. She experienced limping, recurrent falls, and required a cane. Examination revealed grade 3 medial instability and ROM from 0° to 120°.

Imaging showed well-fixed implants with valgus alignment, and infection markers were normal (Fig. 3). Full component revision was performed using a constrained condylar knee system with porous metaphyseal sleeves on both the femoral and tibial sides (Anderson Orthopaedic Research Institute type 2A defects). A 16-mm rotating insert was used. During trialing, persistent medial gapping in extension prompted augmentation with ISBA. Suture anchors were placed at the femoral origin and 2 tibial points corresponding to the deep and superficial MCL insertions. The MCL was secured to the high-strength suture construct using a Krakow stitch. Final tensioning was performed after all components were implanted (Fig. 4). At 22.1 months postoperatively, she had no valgus instability and maintained full ROM.

Figure 3.

Preoperative anteroposterior radiograph (Case 2) showing a right total knee arthroplasty with retained distal femoral hardware and valgus malalignment consistent with medial collateral ligament deficiency.

Figure 4.

Postoperative anteroposterior radiograph (Case 2) demonstrating newly implanted femoral and tibial components with porous metaphyseal sleeves and correction of valgus alignment after constrained condylar knee revision.

Case 3

A 77-year-old woman with advanced knee osteoarthritis underwent elective TKA (Fig. 5). Preoperatively, she had a 5° flexion contracture and flexion limited to 85°. Intraoperatively, during gap balancing in flexion, significant medial opening was observed, and disruption of the deep MCL was noted. Trialing demonstrated satisfactory stability in flexion and extension; however, an internal suture brace was added to support both the deep and superficial MCL. Suture anchors were placed anatomically during trialing to enhance medial stability before final implantation of the components. Following preparation and drying of the bone surfaces, all components were cemented separately. A 14-mm condyle-pivot-stabilized insert was selected to increase constraint and optimize coronal plane stability (Fig. 6). A lateral release was not required, and patellar tracking was central throughout.

Figure 5.

Preoperative anteroposterior radiograph (Case 3) showing bilateral tricompartmental osteoarthritis, more severe on the right side, with valgus deformity and joint space narrowing.

Figure 6.

Postoperative anteroposterior radiograph (Case 3) showing a well-aligned right total knee arthroplasty with a condylar pivot-stabilized polyethylene insert and no radiographic evidence of loosening.

At 1 year postoperatively, the patient reported high satisfaction and had full ROM from 0° to 120° with a stable knee.

Surgical technique of MCL repair procedure with ISBA

The ISBA technique was used to address medial instability in all 3 cases, regardless of whether the instability was chronic or acute.

For the chronic cases (Case 1 and Case 2), revision TKA was performed in a standard manner, including medial release and implant/liner revision to a more constrained design. After implant placement, residual medial instability due to superficial MCL (sMCL) and posterior oblique ligament (POL) insufficiency was managed with ISBA and MCL imbrication. [12]

For the acute case (Case 3), ISBA was performed during primary TKA. Intraoperative assessment confirmed deep MCL disruption, requiring reinforcement with ISBA to restore stability.

At the time of the repair, the surgeon should locate the medial epicondyle and dissect down to the sMCL origin (Fig. 7a). A punch, then tap, was used to create a threaded hole for suture anchor placement 3.2 mm proximal and 4.8 mm posterior to the medial epicondyle based on the anatomical description of the sMCL by LaPrade et al. [13] The repair sutures of the sMCL were passed through the eyelet of a 4.75-mm Vented BioComposite SwiveLock suture anchor (Arthrex, Naples, FL) loaded with FiberTape (Arthrex) functioning as the internal brace. The first suture anchor was deployed while the repair sutures of the sMCL were tensioned to reapproximate the ligament toward the femoral insertion. Ten millimeters distal and slightly posterior to the tibia-polyethylene junction, around the POL insertion on the tibia, one tail of the FiberTape suture was retrieved and secured with a 4.75-mm BioComposite SwiveLock suture anchor (Arthrex, Naples, FL) while the knee was in extension (Fig. 7b). The second tail of the FiberTape suture was retrieved and placed with a 4.75-mm BioComposite SwiveLock suture anchor (Arthrex, Naples, FL) 6 cm distal to the joint line around the tibial insertion of the sMCL with the knee in 30° flexion under varus force (Fig. 7c). This provided additional medial support, particularly with more flexion. The suture was routed through native soft tissues to avoid contact with the femoral and tibial components or the polyethylene articulation. Tensioning of the construct was assessed intraoperatively by checking isometry as the knee was taken through a full ROM. Final fixation was performed with the knee positioned between 0° and 20° of flexion in neutral rotation and slight varus reduction, ensuring the suture was slightly looser than the native MCL to avoid overtensioning. The proximal tissue was then imbricated using the extra suture from the proximal anchor to increase proximal tension and enhance medial stability. The principles of the reconstruction technique are based on the anatomical reconstruction presented by LaPrade et al. [14] After repair, the knee was stable in valgus stress with retained ROM in flexion and extension. Following this, the arthrotomy and the skin were closed with the usual technique (Fig. 7d).

Figure 7.

(a) Intraoperative identification and exposure of the femoral origin of the medial collateral ligament, located just posterior to the medial epicondyle. (b) High-strength suture passed through a tapped femoral anchor site during preparation for anchor insertion. (c) Final suture tensioning performed with the knee in approximately 30 degrees of flexion under applied varus stress. (d) Suture tensioning and fixation of the superficial medial collateral ligament and posterior oblique ligament with the knee in full extension. The free suture from the proximal anchor was used to imbricate excess medial collateral ligament tissue.

Postoperative care

Postoperatively, patients were immobilized in a hinged knee brace set in varus alignment. Weight-bearing as tolerated was allowed for the first 6 weeks, with the brace locked in extension. Passive ROM (0°–90°) was permitted in seated or supine positions, avoiding valgus stress. The rehabilitation protocol focused on isometric exercises and quadriceps strengthening.

By the 3-month follow-up, all patients reported a stable knee without mechanical symptoms or pain and were cleared for linear activities. By 6 months postoperatively, they resumed full, unrestricted activity. At the latest evaluations, at 34.5 months (Case 1), 22.1 months (Case 2), and 12 months (Case 3), each patient demonstrated full ROM (0°-120°) with no medial instability.

Discussion

Structures on the medial side of the knee, including the MCL and the POL, are critical to controlling valgus and rotational instability. Loss of MCL integrity compromises knee function and may lead to early loosening and accelerated polyethylene wear. [1,15] In patients with medial instability, anatomical reconstruction of the MCL and POL offers an alternative to hinged arthroplasty, which, while effective, may increase implant-cement stress and long-term failure risk. [5,16]

The incidence of complete MCL injuries during TKA ranges from 0.8% to 2.7%. [1,17,18] Optimal management of intraoperative iatrogenic MCL injury remains controversial. [19] Surgical options include polyethylene liner exchange, primary ligament repair, augmentation with grafts, ligament reconstruction, or, in some cases, revision to constrained implants. [20] However, there is limited literature on managing MCL injuries following TKA.

Several studies have explored MCL reconstruction techniques in TKA. Henstenburg et al. reported successful MCL allograft reconstruction without the need for a constrained prosthesis. [5] Kerzner et al. described a technique using an Achilles tendon allograft for MCL and POL reconstruction in young, active patients. [7] Wierer et al. found favorable results using a semitendinosus autograft [16], while Kanakamedala et al. demonstrated good outcomes with MCL allograft reconstruction and varus-valgus constrained liner exchange. [21]

Our cases present an alternative strategy to addressing medial instability with MCL repair with augmentation, avoiding allografts and increasing implant constraint as needed to avoid conversion to hinged prostheses. The use of ISBA has gained attraction in sports medicine for multiligamentous knee injuries, showing satisfactory outcomes with low revision rates. [12,[22], [23], [24]] Frisch et al. conducted a biomechanical study evaluating this approach in TKA cadaveric knees with medial instability, demonstrating adequate stability and strength to address MCL incompetence without the need for external braces or constrained implants. [25] To our knowledge, this is the first publication reporting 3 cases where internal high-strength suture augmentation was used in patients with medial instability during and after TKA.

In the first case, a TS polyethylene liner revision was performed with MCL repair with ISBA and imbrication restoring medial stability, avoiding femoral and tibial component revision. In the second case, a constrained condylar knee implant was used, complemented by MCL repair with ISBA, thus avoiding conversion to a hinged implant. In the third case, an acute MCL disruption during primary TKA was successfully managed with ISBA, avoided using constraint implants and resulted in a stable knee postoperatively. All 3 cases achieved medial stability with MCL repair and augmentation, avoiding the need for hinged revisions and potentially reducing the risk of future complications. [26,27] The long-term durability of this approach remains uncertain, and further investigation is warranted.

Repair with ISBA offers a promising option for managing medial instability after TKA while avoiding allografts and hinged implants. Future comparative studies are needed to establish optimal treatment protocols. As more cases and longer follow-up are reported, evolving technique descriptions and annotated video resources will continue to improve understanding and reproducibility.

Summary

This case series highlights the use of ISBA in 3 patients with MCL instability during or after TKA. In each case, ISBA was used to reinforce soft tissue repair and restore stability while avoiding the need for hinged implants. These cases illustrate that ISBA may be a valuable adjunct in managing medial instability, but its long-term durability remains uncertain.

Informed patient consent

The author(s) confirm that written informed consent has been obtained from the involved patient(s) or if appropriate from the parent, guardian, power of attorney of the involved patient(s); and, they have given approval for this information to be published in this case report (series).

CRediT authorship contribution statement

Sergio F. Guarin Perez: Writing – review & editing, Writing – original draft, Project administration, Methodology, Investigation, Formal analysis, Conceptualization. Diego Alarcon Perico: Writing – review & editing, Investigation, Conceptualization. Katherine E. Mallet: Writing – review & editing, Methodology, Investigation, Conceptualization. Rafael J. Sierra: Writing – review & editing, Visualization, Validation, Supervision, Resources, Project administration, Methodology, Investigation, Formal analysis, Conceptualization. Robert A. Cates: Writing – review & editing, Visualization, Validation, Supervision, Resources, Project administration, Methodology, Investigation, Formal analysis, Conceptualization.

Conflicts of interest

R.J. Sierra received royalties from Zimmer Biomet, Link, and OrthAlign; received research support as a Principal Investigator from Arthrex and Hip Society; received royalties, financial or material support from Springer; and is a board member/committee appointments for AAHKS, Muller Foundation, and Hip Society; all other authors declare no potential conflicts of interest.

For full disclosure statements refer to https://doi.org/10.1016/j.artd.2025.101836.

Appendix A. Supplementary data

Video 1

Preoperative examination demonstrating medial collateral ligament (MCL) instability, with excessive valgus laxity during stress testing.

Video 2

Intraoperative placement of the tibial suture anchor for internal suture brace augmentation (ISBA). A drilled hole is prepared approximately 6 cm distal to the joint line, with the knee in 30° flexion under varus stress. The suture was then secured at the tibial insertion site to reinforce medial stability.

Video 3

Intraoperative visualization of the distal medial collateral ligament (MCL) branches and medial balancing assessment. Both superficial and deep branches of the MCL were identified, and medial gap balancing was evaluated.

Video 4

Final medial balancing assessment after deep arthrotomy. Following deep arthrotomy, medial balancing was reassessed to confirm proper ligament tension and stability throughout the range of motion.