Dual Posteromedial Portal Technique for Surgical Repair of an Unstable Medial Meniscal Ramp Lesion

Abstract

Background:

Medial meniscal ramp lesions, which commonly occur in the setting of anterior cruciate ligament (ACL) ruptures, are defined as structural lesions at the medial meniscocapsular junction and can involve the posteromedial capsular attachments or most peripheral aspect of the meniscus. Unstable ramp lesions can lead to rotational instability within the knee and may play a role in ACL graft failure if left untreated. The novel use of dual posteromedial portals, similar to those used in an arthroscopic labral repair, may allow for enhanced visualization, optimal access to the posteromedial compartment, and easier manipulation of the instrumentation for successful surgical repair of hidden ramp lesions.

Indications:

Surgical repair of medial meniscal ramp lesions is indicated in patients with a clinically unstable meniscus when probed during arthroscopy.

Technique Description:

This surgical technique video demonstrates a dual posteromedial portal arthroscopic approach to repair an unstable medial meniscal ramp lesion using a case example from a patient with a concomitant ACL rupture.

Results:

Surgical repair of medial meniscal ramp lesions has been reported to show improvements in meniscus healing and knee stability.

Discussion/Conclusion:

The use of dual posteromedial portals offers improved accessibility to the posteromedial compartment of the knee and provides excellent visibility during the surgical repair of a medial meniscal ramp lesion.

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

In this video, we are going to present the use of the Dual Posteromedial Portal Technique for Surgical Repair of an Unstable Medial Meniscal Ramp Lesion.

We have no disclosures to report.

The medial meniscus is a fibrocartilage structure anchored to the tibial plateau by anterior and posterior roots and the posteromedial joint capsule. In addition, the tibial attachment of the adjacent semimembranosus has nearby connections to the posteromedial joint capsule. Ramp lesions are described as the structural injuries to the meniscocapsular junction of the posterior horn of the medial meniscus. In the last decade, a better understanding and increased awareness of ramp lesions have resulted in a greater focus in the orthopedic literature. The Thaunat classification system describes 5 distinct types of ramp lesions based on the specific anatomical location of the medial meniscal tear. ⁷

Ramp lesions are associated with ACL injuries with a reported incidence of 9% to 42%. ¹⁰ Ramp lesions have been found to occur more frequently in males, individuals below 30 years of age, contact and chronic injuries, or when there is a concomitant lateral meniscus tear. ⁶ Bone bruising on preoperative magnetic resonance imaging (MRI), particularly at the posteromedial tibial plateau, has been reported to be associated with ramp lesions and, therefore, should further increase clinical suspicion that a ramp lesion may be present.

Although the biomechanics of ramp lesions is not fully understood, it is widely believed to be caused by an excess force transmitted onto the posteromedial capsule by a combination of valgus stress, internal tibial rotation, and axial loading during an ACL rupture. In addition, compensatory contraction of the semimembranosus during anterior tibial translation has been hypothesized to cause tears of the meniscotibial ligament. ⁴ Posterior traction may be transmitted indirectly through the capsular tissue and a highly vascularized intermediary adipose tissue. ¹ Failure to recognize, treat, and enable proper healing of medial meniscal ramp lesions may lead to greater knee instability and future ACL graft failure. ⁶

There is no specific physical examination finding defined for ramp lesions. The MRI may show an enhanced fluid signal at the meniscocapsular junction or meniscotibial ligament. However, a stepwise arthroscopic evaluation remains the gold standard. At our institution, a modified Gillquist view is performed as standard protocol for all ACL reconstructions (ACLRs) and utilized for medial meniscus repair surgeries for assessment of the posteromedial meniscus and capsule. A spinal needle is initially used to probe the region and a posteromedial portal is created for equivocal appearing cases. A heightened suspicion is maintained when preoperative MRI suggests there is an unstable ramp lesion that requires repair.

In the following case, our patient is a 33-year-old man who suffered an acute hyperextension, pivot shift injury to his left knee while practicing martial arts. On initial examination, the patient demonstrated full range of motion, positive medial McMurray test, medial joint line tenderness, a Grade 2B Lachman test and a Grade 2 pivot shift test.

Sagittal MRI images of the patient demonstrate a vertical longitudinal tear between the posterior horn of the medial meniscus and posteromedial joint capsule, extending from the articular surface of the posterior horn of the medial meniscus distally to the distal to tibial surface which is evidence of a medial meniscal ramp lesion that requires further arthroscopic evaluation.

While small stable ramp lesions can be treated conservatively or with simple debridement, there is a growing consensus in the literature to surgically repair unstable ramp lesions. All-inside and inside-out are the most commonly used suture techniques with both demonstrating favorable outcomes. ³ Ramp lesions are typically repaired arthroscopically using either more traditional anteromedial or anterolateral portals or with additional posterolateral and posteromedial portals.

This patient’s ramp lesion was located very centrally adjacent to the posterior root and did not extend out to the posterior horn-body junction. It was felt to be less accessible and a less amenable trajectory via inside-out suture placement. An initial posteromedial portal was created for placement of an 8-mm cannula for suture hook utilization. A second smaller 5-mm portal was created to facilitate with tissue retrieval, suture hook placement, suture shuttle retrieval, and management, analogous to an arthroscopic Bankart repair technique. Specifically, these advantages from utilizing a dual posteromedial approach greatly improved hook suturing capabilities in an otherwise technically challenging aspect of the knee to operate. In addition to ramp lesions, dual posteromedial portals may be indicated for other posterior knee pathologies, such as removal of a tumor or mass, pigmented villonodular synovitis (PVNS) synovectomy, posterior cruciate ligament (PCL) reconstruction, and meniscal root repairs.^2,9

Stable ramp lesions located in more highly vascular territories of the posterior medial meniscus can be treated conservatively, but unstable ramp lesions may have significant biomechanical consequences that indicate a need for surgical repair. Therefore, if there is marked instability of the medial meniscus upon probing during arthroscopy, it is recommended to proceed with repairing the ramp lesion, especially in patients undergoing ACLR.

For arthroscopic ramp repair, the patient is positioned supine. We prefer a high-thigh tourniquet in addition to the arthroscopy pump. The contralateral leg is placed on a gynecological leg holder to provide access to the medial and posteromedial aspect of the knee.

To view the posterior knee capsule, the scope is advanced posteriorly between the lateral wall of the medial femoral condyle and the PCL through the anterolateral portal as the knee is flexed at 90°. The posteromedial capsule is viewed first for the presence of the ramp lesion. Then, an 18-gauge spinal needle is introduced through the posteromedial portal. This is done by palpating the soft spot formed by the medial edge of the gastrocnemius, the medial collateral ligament, and the semimembranosus and is about 1 cm posterior to the edge of the joint line. Assessment for the trajectory of these portals to the lesion is important as well as planning the location of the 2 different-sized cannulas that are 8 and 5 mm, respectively.

The first portal is created through the superior border of this spot and the cannula is inserted. A second portal is created immediately inferior to the first portal and is more parallel to the tibial plateau. Keeping the inferior portal cannula close to the capsule minimizes the crowding within this confined space. A suture lasso is then introduced through the superior portal to pass the suture. We prefer passing it through the meniscus first and capsule second. The peripheral aspect of the meniscus can be dense, robust tissue and doing this in 2 separate passes may be considered. This would be repeated passing the suture lasso through the posteromedial capsule and the free end of the suture is shuttled through the capsule. A minimum of 5 square knots are then placed using the knot pusher. We prefer 2 to 3 sutures for the repair of the ramp lesion. The same steps are followed for the remaining sutures and the repair is complete.

Currently, there is no consensus on the postoperative rehabilitation regimen for ramp lesions.

We utilize a delayed weight-bearing meniscus repair protocol. We allow partial weight-bearing in the first 4 weeks with progression to full weight-bearing by week 6. Full knee flexion in a seated position in this period is allowed, and patients are allowed to walk with crutches with knees locked in extension in a knee immobilizer. We caution patients on avoiding weight-bearing flexion greater than 90° for the first 6 months postoperative, secondary to the high sheer forces on the meniscus in that position.

Return to sports also depends on the concomitant ACLR. Return to sports criteria include full ROM, especially extension, absence of pain and effusion, nontender joint line, restored muscle strength, and near symmetry on return to sport testing, including isokinetic dynamometry.

A recent study conducted by Hatayama et al ⁵ demonstrated that using an all-inside suturing technique through a posteromedial portal had significantly improved meniscal healing of ramp lesions with reduced signal intensity on 3T MRI at 1 year postsurgery when compared with a group of nonrepaired ramp lesions. A separate study conducted by Thaunat et al used the same posteromedial portal and all-inside approach to repair ramp lesions during ACLR. After a minimum of 2 years of follow-up, the study reported significant improvements in patient-reported outcomes and anterior knee laxity. ⁸

Repair of ramp lesions does present with a few possible postoperative complications. The overall failure of meniscal repairs remains relatively low at < 5%. However, the main concern when utilizing posteromedial portals is potential damage to the saphenous neurovascular bundle. Therefore, one should proceed with caution and meticulous preoperative planning.

Here are our references.

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