Isolated Lateral Meniscal Allograft Transplantation With an All-Soft Tissue Graft and Centralization

Abstract

Background:

The meniscus-deficient knee, especially in the lateral compartment, is prone to early degeneration, cartilage loss, and pain. Meniscus allograft transplantation (MAT) with an all-soft tissue graft and centralization is a technique used to treat unicompartmental pain and improve outcomes.

Indications:

Isolated lateral MAT with centralization is indicated for unicompartmental pain in a meniscus-deficient knee without significant articular cartilage loss, limb malalignment, or ligamentous instability.

Technique Description:

For MAT preparation, an osteotome is used to remove the anterior and posterior meniscus roots with small wafers of bone to preserve the entire meniscus length, and the meniscus is transected at the meniscus-capsule junction. Sutures are passed through the anterior and posterior roots for later transtibial fixation. Knee arthroscopy is performed, and the lateral meniscus is debrided to a stable rim. A suture is passed through the lateral capsule, just anterior to the popliteus, for centralization. A targeting guide is used to drill a tunnel from the anteromedial tibia to the lateral edge of the lateral plateau, and the centralization suture is retrieved into the tunnel. Then the posterior root insertion is prepared, and an anatomic tunnel is drilled. MAT is delivered into the joint via the posterior root suture through our previously established portal. Meniscus repair all-inside devices are used to fixate the MAT to the capsule in a vertical mattress configuration. Then the anterior root tunnel is prepared and drilled. MAT anterior root is shuttled into the tunnel. The centralization suture is first tied down over a button on the anteromedial tibia, followed by the posterior root over a separate button, and the anterior root over a third button at 60° of knee flexion.

Results:

MAT relieves pain and restores meniscal function in a meniscus-deficient knee. Clinical studies have demonstrated good long-term survivorship rates with improvements in functional and patient-reported outcomes after MAT. Centralization is used to decrease the size of the lateral compartment, improving MAT compartment fit and decreasing extrusion.

Discussion/Conclusion:

All-soft tissue MAT with centralization is a viable option for the treatment of the meniscus-deficient knee with isolated lateral compartment pain without ligamentous instability, malalignment, or focal cartilage loss.

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

For this video, we are presenting a technique for meniscal allograft transplantation (MAT) with an all-soft tissue graft and centralization. All author disclosures are listed here.

Background

MAT is a well-established method for treating meniscal deficiency or post-meniscectomy syndrome. ² Good functional outcomes and long-term survivorship rates have been reported after meniscus transplant. ⁵ Different techniques for meniscus transplant have evolved since it was first described in 1984, ³ and in this video, we demonstrate an all-soft tissue graft technique with centralization.

Indications

Isolated lateral MAT with centralization is indicated for unicompartmental pain in a meniscus-deficient knee without significant articular cartilage loss, limb malalignment, or ligamentous instability. Meniscal transplant can also be considered in the setting of articular cartilage repair and revision anterior cruciate ligament (ACL) reconstruction with meniscus deficiency.

Contraindications include osteoarthritis, inflammatory arthritis, arthrofibrosis, and prior infection. Relative contraindications include body mass index greater than 30 and age over 50.

In this video, we present a 33-year-old teacher with chronic lateral knee pain following 2 prior lateral meniscectomies, with the most recent being 5 years ago. On examination, he had 5° of hyperextension, 130° of flexion, focal lateral joint line tenderness, and a stable ligamentous examination. Plain radiographs demonstrated neutral alignment and a preserved joint space with early lateral compartment osteophytes. It is important to assess the overall limb alignment when considering meniscus transplant, as varus or valgus alignment may have detrimental impacts and thus may require concomitant or staged correction with osteotomy.^5,7 Magnetic resonance imaging demonstrated lateral meniscus deficiency consistent with post-meniscectomy syndrome. One must consider cartilage loss and ligamentous deficiency, as ligamentous instability or focal cartilage defects may require concomitant procedures, and in patients with Kellgren-Lawrence (KL) grade 3 or greater, meniscus transplant is typically not recommended. ²

The patient elected to proceed with a MAT. The remainder of this video represents our technique for lateral MAT with an all-soft tissue graft and capsular centralization.

Technique Description

The patient is positioned supine with a lateral post. Standard examination under anesthesia is performed to evaluate range of motion and ligamentous stability. Standard anteromedial (AM) and anterolateral (AL) knee arthroscopy portals are used.

For the MAT preparation, the senior author (V.M.) prefers a fresh-frozen allograft hemiplateau, sized by the Pollard method. ⁶ The junction between the posterior horn and midbody junction is first marked on the meniscus allograft. Then the junction between the body and anterior horn is marked for orientation. Planned sites of suture fixation are marked on the upper surface of the meniscus allograft.

An osteotome is used to remove the posterior root of the meniscus. A small 1- to 2-mm wafer of bone is left attached to the root, in order to preserve the entire length of the meniscus. The meniscus allograft is then transected at the junction between the meniscus and capsule, leaving approximately 1 to 2 mm of capsule on the meniscus allograft. Sutures are then passed through the bony wafers at the posterior root in a mattress fashion. These sutures will be used for shuttling and later fixation. The posterior root sutures are marked to confirm orientation when shuttling the meniscus allograft into the knee. Now, the anterior root is removed with an osteotome in the same fashion as previously. Again, a small bony wafer is left attached to the root, and sutures are placed in the same fashion as in the posterior root.

After a diagnostic arthroscopy is performed, the remaining meniscus is resected to a stable 1- to 2-mm rim. A suture-passing device is then placed into the AM portal. A centralization suture is passed through the lateral capsule just anterior to the popliteus in a horizontal mattress fashion. Next, an ACL tibial guide is placed through the AM portal to the far lateral aspect of the lateral tibial plateau. A 2- to 3-cm incision is made on the AM aspect of the tibia. A tunnel is then drilled into the far lateral aspect of the tibial plateau. The centralization suture is retrieved from the tunnel on the AM tibia for later fixation. To avoid an undersizing effect due to meniscal migration into the joint space, centralization through the capsule is the preferred method of the senior author.

The posterior root is prepared with the use of an angled arthroscopic curette and radiofrequency device to remove soft tissue and create a bony bleeding healing surface. Next, an ACL tibial guide is placed at the anatomic location of the posterior root of the lateral meniscus and drilled from the AM aspect of the tibia, approximately 1 cm medial to the centralization tunnel. A suture shuttling device is used to pass a shuttling suture up through the tunnel. The arthroscope is then moved to the AM portal. The AL portal incision is extended to accommodate the graft. The posterior root shuttling suture is then retrieved from the AL portal. The suture from the posterior root of the graft is then shuttled into the posterior root tunnel, and the graft is delivered into the knee joint with the aid of an arthroscopic grasper to keep the meniscus allograft from twisting. The suture on the posterior root is pulled tightly down into the anatomic tunnel. All-inside meniscus repair devices are then used to secure the graft to the capsule and passed in a vertical mattress fashion. The authors prefer to fixate the graft to the posterior capsule starting on the upper surface. We prefer to avoid placing sutures through the popliteus to maintain the normal mobility of the meniscus and popliteus tendon. All-inside sutures are then placed progressively more anterior. Once the transplant is secured to the capsule, all-inside devices are placed on the undersurface of the meniscus to balance the graft. Typically, a total of 6 to 8 all-inside meniscus repair devices are used for fixation.

Next, the anatomic location of the anterior root is prepared with the use of a radiofrequency device and arthroscopic curettes. Then, the anterior root tunnel is drilled from the AM aspect of the tibia. Note that this will be a shorter tunnel, usually around 1 cm, and it is more anterior and lateral to the previous tunnels, which may require some extension of the knee to place the drill. A suture-passing device is then used to pass a shuttling suture through the anterior root tunnel that is retrieved out of the AL portal. The suture from the anterior root of the meniscus allograft is then passed and shuttled down into the tunnel. A grasper is used to help keep the meniscus allograft from twisting or flipping during this step. The most anterior all-inside meniscus repair device is then placed at the junction of the body and the anterior horn of the meniscus allograft.

Next, attention is shifted to fixation of the transtibial sutures. First, the knee is brought to 60° of flexion, and the centralization suture is tied down over a button. Then, the posterior root is reduced and tied down over a separate button, again with the knee at 60° of flexion. Finally, the anterior root is reduced and tied down over a third button at the same degree of knee flexion.

Results

Postoperative rehabilitation protocol includes nonweightbearing in a hinged knee brace for the first 6 weeks with crutches. Within the first 4 weeks, the patient has a range of motion restriction from 0° to 60° of flexion. Patients begin using an unloader brace for the ipsilateral compartment at 3 months. Further restrictions include no deep flexion for the first 6 months and no high-impact running for the first year postoperatively. Return to sports or high-impact activities typically occur at about 1 year postoperatively.

Discussion/Conclusion

Studies show favorable clinical outcomes and satisfactory survival rates.^1,4,5,8 This study included 54 patients who received a MAT at a mean age of 30.0 ± 10.5 years and a mean follow-up of 10.4 ± 4.4 years. Improvements in patient-reported outcomes after MAT at 2 years are predictive of sustained success at midterm and long-term follow-up. ¹

Another study included 142 patients with a mean age of 29.6 ± 10.0 years and an average follow-up of 10.3 ± 7.5 years. MAT tears were observed in 32% of patients, typically occurring at a median of 1.2 years after surgery. Posterior root tears were present in 43% of the cases. Younger patient age and the use of suture fixation alone were identified as significant risk factors for MAT failure. ⁸

Thank you.