Anterior Cruciate Ligament Reconstruction With Transtibial Medial Meniscus Root Repair

Abstract

Background:

The incidence of anterior cruciate ligament (ACL) injuries has rapidly increased. Patients with ACL injuries frequently present with concomitant meniscal pathologies. Posterior medial meniscal root tears (PMMR) are less commonly seen with acute ACL injuries as compared with lateral tears and are often degenerative in nature or more rarely in an acute setting. Clinical studies have demonstrated medial meniscal deficiency to be a significant risk factor for graft failure and poor postoperative clinical outcomes. As such, given its demonstrated efficacy, there has been growing interest in transtibial meniscal repair mechanisms in combination with an ACL reconstruction as a potential solution to this challenging pathology.

Indication:

Patients are indicated for surgery when presenting with symptomatic ACL deficiency verified on provocative testing and advanced imaging and objective insufficiency of the medial meniscal root. Contraindications for this procedure include advanced osteoarthritis (Kellgren–Lawrence grade ≥3) on weight-bearing x-rays, age <50 years, and body mass index (BMI) > 30 as well as poor-quality meniscal tissue and unrepairable chondral defects.

Technique Description:

The ACL stump is debrided and a burr hole is created. A femoral aiming guide is used to drill the femoral tunnel. Following medial collateral ligament (MCL) release, a healing bony bed is prepared with a curette and shaver at the anatomic tibial footprint. An aiming device is then used through the anterior medial portal to create 2 transosseous tibial tunnels. A vertical mattress suture and simple suture are placed through the meniscal root, shuttled through the posterior and anterior transosseous tunnels, respectively. The tibial ACL tunnel is placed using a standard guide to avoid tunnel convergence with the root tunnels and prevent graft tunnel mismatch. After graft passage, interference screws are inserted while maintaining graft tension. The sutures are then tied over a cortical button over the tibia.

Results:

Within 2 years postoperatively, patients are expected to have improved overall knee-specific quality of life, reduced pain, and a successful return to activities with low rates of graft failure.

Discussion/Conclusion:

Recent advancements in our understanding of the relationship between the medial meniscus and the ACL should prompt surgeons to continue considering such combined treatments in indicated patients.

Patient Consent Disclosure Statement:

The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Graphical Abstract

This is a visual representation of the abstract.

Video Transcript

This is a surgical technique video demonstrating how to perform an arthroscopic anterior cruciate ligament (ACL) reconstruction with simultaneous medial meniscal root repair.

Meniscal root tears are defined as a tear within 1 cm of the root insertion. Recent literature is highlighted they are more prevalent than previously thought, comprising 20% of all meniscal tears. ⁹ While medial tears are not as common as lateral tears with ACL injury, the medial meniscus is still particularly important for anterior stability as a secondary stabilizer.^1,8 Surgical management of root tears is particularly important as untreated tears have shown significantly increased contact pressures and rapid progression to arthritis.

In this case, the patient presented as a 34-year-old man with an acute rotational injury-causing persistent pain and instability with associated mechanical symptoms. Physical examination was notable for an effusion with preserved range of motion, a grade 2 Lachman, and a 3-plus pivot shift test.

Standard knee radiographs showed no joint narrowing with long leg imaging demonstrated no significant malalignment. Magnetic resonance imaging (MRI) was obtained for further work up and demonstrating tearing of the ACL, along with a tear in the posterior medial meniscal root with significant medial meniscal extrusion.

Given his symptomatic presentation and imaging evidence of complete ACL and medial meniscal posterior root tears, he was indicated for ACL reconstruction with arthroscopic repair of his meniscal tear. After discussing graft options, the patient elected to proceed with bone–tendon–bone (BTB) autograft. A transtibial pullout technique was planned for the root due to its biomechanical efficacy as evidenced in the literature.^4,5

Examination under anesthesia is performed first to confirm ACL instability, re-demonstrating a 2-B Lachman, and a 3-plus pivot shift test. Medial collateral ligament, lateral collateral ligament (LCL), posterior cruciate ligament (PCL), and posterolateral corner (PLC) stability should also be confirmed. BTB autograft harvest is performed in the standard fashion using a midline incision with careful dissection through the peroneal. The graph length is measured to take the central 10 mm of the tendon. An oscillating saw is used to make a 10-by-20 mm patellar and 10-by-25 mm tibial bone plugs for the harvest.

The ACL stump is then debrided, and a burr hole is created midway between the anterior medial and post lateral bundles of the ACL. A femoral aiming guide is used to drill a guide pin and a 10-mL reamer is used to drill the femoral tunnel to a depth of 25 mm while maintaining a 1.5-mm back wall.

To assist with safe working space, a spinal needle is used to partially release the deep MCL. A healing bony bed is then prepared with a ring curette and shaver at the anatomic tibial footprint for the medial root tear. It is critical to identify the anatomic footprint at the root attachment site as biomechanical studies have shown placement even 5 mm outside the footprint may not appropriately restore joint loading. ⁶ The anatomic footprint of the posterior medial meniscus can be found using the medial tibial eminence (MTE) as a key landmark, located 10 mm posterior and 0.7 mm lateral to the center of the root attachment; thus, surgeons can track laterally and posteriorly along the bony surface of the MTE to navigate this location. Any posterior adhesions are released using an arthroscopic shaver to ensure adequate excursion to the anatomic footprint.

Viewing from the anterior lateral portal, an aiming device is used through the anterior medial portal to create 2 small transosseous tibial tunnels; each tunnel diameter was determined as 2.8 mm, with a gap of 5 mm between the 2 tunnels. Typically, it is easier to first drill the posterior tunnel and use the parallel offset guide to subsequently drill the more anterior tunnel. A canula is inserted in the medial portal for suture management. A suture passer is used to place a vertical mattress suture through the peripheral aspect of the posterior root, which is then shuttled through the posterior transosseous tunnel. A second simple suture is placed in the anterior aspect of the posterior root, which is then shuttled through the anterior tunnel to maximize surface contact area for healing.

The tibial ACL tunnel is then created with a standard guide pin followed by a 10-mm reamer. Importantly, the tunnel is placed 8-to-10 mm at an angle no greater than 65° lateral and distal to avoid tunnel convergence with the medial root tunnels and prevent graft tunnel mismatch. ⁶ The graft is passed into the joint with the cortical surface oriented. Confirmation of full seating is visualized and 7-by-20 mm titanium interference screw is inserted interiorly while maintaining graft tension. The roots sutures are then tied over a cortical button over the tibia under direct arthroscopic visualization to confirm anatomic seating and appropriate tension. The knee is cycled in and a 9-by-20 mm titanium interference screw is inserted in the tibial tunnel, with the knee fully extended while maintaining full graph tension. Repeat Lachman examinations should then be performed to confirm 1A stability with full knee range of motion.

A standard postoperative protocol is prescribed as shown, with an anticipated return to sport between 6 and 9 months after surgery.

Outcomes specific to ACL reconstruction and posterior medial root tears have shown high healing rates and return to sport. ⁷ A recent systematic review article ⁵ showed significant improvement in a variety of outcome scores following the transtibial pullout technique for meniscal root repair. Patient-reported outcomes also show significant improvement from preoperative to postoperative timing. ³

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