Hybrid Meniscal Allograft Transplantation via Posterior Bone Plug and Anterior Soft Tissue Fixation

Abstract

Background:

Lateral meniscal allograft transplantation (MAT) is a technically challenging procedure that can improve the meniscal load-bearing function and stability in patients after meniscectomy, despite some difficulty in resolving compartmental knee pain. In contrast to early studies, more recent literature suggests that a hybrid MAT with posterior horn bone block and anterior horn fixation with a push-in suture anchor may limit the rate of degeneration and development of osteoarthritis of the affected area.

Indications:

Indications for MAT include isolated lateral compartment knee pain with post-activity effusion, arthrosis, or desired high levels of low-impact athletic activity, as in this 21-year-old Division I field hockey player. Although well described in the current literature, nuances in the fixation for MAT, with posterior bone plug and anterior soft tissue fixation, are variable and not as well defined.

Technique Description:

The patient was placed in the supine position. The allograft was prepared with a 7-mm bone plug for the posterior horn and all soft tissue fixation for the anterior horn. The meniscal allograft was inserted through the anterolateral portal, and inside-out sutures were placed in a vertical mattress fashion circumferentially. A 4.75-mm PEEK SwiveLock anchor was placed on the anteromedial tibia for fixation of the posterior horn, and outside-in repair was performed on the anterior horn using a meniscal mender kit and polydioxanone suture fixation.

Results:

Outcomes after MAT are positive, with patients reporting lower visual analog scale pain scores and improved Lysholm functional scores. Motion and functional testing are nearly equal to those of the contralateral limb, and >80% of patients are satisfied with their procedure.

Discussion/Conclusion:

MAT with posterior bone plug and anterior soft tissue fixation is a viable treatment option for patients with lateral meniscal deficiency.

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 technique for a meniscal transplantation with a posterior bone plug and anterior soft tissue fixation.

Background

Lateral meniscal allograft transplantation (MAT) is a technically challenging procedure that can improve the meniscal load-bearing function and stability in patients after meniscectomy. Some cite difficulty in resolving compartmental knee pain, even after transplantation.^4,6 There are multiple options for fixation of the meniscal allograft horns, including soft-tissue, bone-plug, and bone-bridge techniques, as shown on the right from top to bottom. ³ There is even variation within soft-tissue fixation, such as opting for all-inside or inside-out sutures. In contrast to early studies, more recent literature suggests that a hybrid MAT with posterior horn bone block and anterior horn fixation with a push-in suture anchor may limit the rate of degeneration and development of osteoarthritis of the affected area, as described in this video technique.^4,6 However, nuances in this fixation method, including a posterior bone plug and anterior soft-tissue fixation, are not well described.^3,5

Indications

A 21-year-old woman presented to our clinic with the chief complaint of long-standing lateral knee pain worsened by prolonged standing and running. She previously failed conservative treatment with oral analgesics, 1 intra-articular corticosteroid injection, physical therapy, and activity modification. She had a history of 3 previous knee arthroscopy procedures with a lateral retinaculum release. She is currently an active Division I field hockey player.

On the physical examination, she demonstrated a full passive range of motion. Hamstring and quadriceps strengths were full bilaterally. She demonstrated neutral hip-knee alignment bilaterally. There was mild tenderness to palpation along the lateral joint line and minimal tenderness along the medial joint line. There was a positive patellofemoral grind maneuver with a negative J sign and a negative McMurray test. Lachman, anterior drawer, posterior drawer, and pivot shift testing were all stable.

Knee radiographs indicated no acute fracture or malalignment, no joint effusion, maintained joint spaces, and a bone island in the proximal tibia metaphysis. Full-length leg imaging demonstrated 2° of valgus in the tibiofemoral angle bilaterally.

Left knee magnetic resonance imaging without contrast demonstrated an absent anterior horn of the lateral meniscus with an intact medial meniscus. There were reactive bony changes along the anterior lateral tibial plateau with a moderate-sized joint effusion. The patellar tendon, medial collateral ligament, anterior cruciate ligament (ACL), and posterior cruciate ligament were intact. There was chondromalacia of the patella.

Indications for MAT include patients with lateral meniscal deficiency who have exhausted nonoperative measures and present with isolated lateral compartment knee pain associated with post-activity effusion, arthrosis, or desired high levels of low-impact athletic activity, as in this 21-year-old Division I field hockey player. This patient's indication includes an anterior meniscal deficiency, where posterior deficiencies are encountered more frequently. Alternative treatment options include physical therapy, a knee offloader brace, corticosteroid injections, and oral analgesics. Contraindications include unaddressed knee instability, marked malalignment without correction, and Outerbridge grade 4 articular changes without addressing them at the time of surgery. Some physicians discourage allograft transplantation in patients >50 years.

Technique Description

The patient was placed in a supine position in the operating room and prepped and draped in a sterile fashion. Standard medial and lateral portals were created, and a diagnostic arthroscopy was performed.

On a diagnostic arthroscopy, the lateral meniscus was inspected, and the anterior horn was found to be deficient.

The allograft was prepared at the back table with a 7-mm bone plug for the posterior horn and all soft tissue fixation for the anterior horn.

The tunnel for the posterior bone block was drilled at the anatomic root attachment site using a FlipCutter through a meniscal root repair guide.

Passing sutures were inserted into the drilled tunnel and then pulled out of the anterolateral portal.

The meniscal allograft was inserted through the anterolateral portal, and seating was obtained on the tibial plateau.

Inside-out sutures were placed in a vertical mattress fashion circumferentially on the superior and inferior aspects of the graft.

A meniscal repair device was then placed in the posterior horn for additional fixation with an all-inside stitch.

A 4.75-mm PEEK SwiveLock anchor (Arthrex) was placed on the anteromedial tibia to secure the posterior horn.

Fixation would later be performed using the SwiveLock anchor once the anterior horn is placed and fixed. This is beneficial because it avoids undermining the ipsilateral compartment, prevents skiving of the initial drill bit, and avoids interference from the ACL tunnel when a concomitant ACL reconstruction is being performed.

Under needle localization, an accessory anterior medial portal was created, and drilling for a 2.4-mm PushLock anchor was performed.

This drilling creates a low-profile tunnel that avoids any medial tunnels and can be placed close to the rim without risk of cortical compromise.

Next, outside-in repair was performed on the anterior horn using a meniscal mender kit and PDS suture fixation. This PushLock technique allows for fine-tuning of the position and fit of the meniscal transplant, particularly if there is a subtle mismatch in size.

If the allograft is larger, the posterior plug can be sunk slightly deeper. If the anterior horn is the incorrect size, its attachment can be adjusted for anatomic fit to prevent extrusion and ensure intact hoop stresses. If there is a concomitant ACL reconstruction, this technique prevents tunnel convergence with the ACL tibial tunnel and the complexity of rigid anterior horn bone plug fixation. The posterior horn was then fixed on the SwiveLock anchor, and the procedure was complete.

Additionally, we demonstrate an alternate method of anterior horn and root transosseous fixation, including the use of a sutureloc and adjunctive suture fixation. This was indicated for a patient with a previous allograft transplant who suffered an anterior horn avulsion.

The meniscal transplant was nicely intact throughout its posterior horn and body. The anterior root demonstrated laxity in fixation with an unstable root attachment. The prominent suture material was removed, and a retrograde drill guide was then used to drill up into the anatomic footprint. The trocar was removed, and a lasso wire was delivered through the cannula into the joint. The lasso wire was retrieved, and the drill pin was removed. The end of the sutureloc was loaded onto the wire and shuttled into the joint by pulling the lasso wire through the tibial tunnel. The anchor was seated just below the subchondral cortical bone. Tensioning the 4 individual sutures provisionally set the implant, and the anchor was locked by pulling on the loops at the distal end by the anterior tibia. The suture passer was used to advance a repair suture through the meniscal root tissue, and the free end was pulled out of the joint and passed through the same strand's loop. The same steps were taken for the second repair stitch using a suture passer to engage the meniscus and looping the repair stitch's free end through its loop outside of the joint. To convert and lock the repair stitches, the tail of the corresponding striped conversion sutures by the anterior tibia is pulled, which engages the knotless mechanism. An additional rip-stop suture is passed in mattress fashion and hand-tied to avoid radial suture cutout during final tensioning of the repair stitches.

Two outside-in 0-PDS sutures were passed and tied for adjunctive fixation of the anterior horn.

Complications of the procedure include graft extrusion, graft failure, cosmetic or functional deformity, infection, and graft loosening, among others.^1,2,6,7 Patients typically report lower visual analog scale pain scores and improved Lysholm functional scores.^4,5 Testing typically demonstrates near equal motion and function compared with the contralateral limb. Also, >80% of patients are satisfied with their procedure. ⁵

Results

For the first 2 weeks, patients are limited to heel touch weightbearing (HTWB) with crutches. A knee brace should be locked in full extension for sleeping and all activities, and it can be removed for exercise and hygiene. Passive range of motion (ROM) from 0° to 90° is acceptable when nonweightbearing, and patients should avoid weightbearing with flexion of >90°. From weeks 2 to 6, patients can HTWB with crutches. Their brace should remain locked from 0° to 90° during activity, and it can be taken off at night. Patients should avoid weightbearing with flexion of >90° and engage in ROM as tolerated. From weeks 6 to 8, patients can progress to full weightbearing. They can implement activity without bracing as tolerated and remove the brace at night. They can move within a ROM as tolerated. They should still avoid weightbearing with flexion of >90°. In weeks 8 to 12, patients can fully weightbear without bracing and move with full ROM. They can begin using a stationary bike. Patients can implement swimming at 16 weeks. After week 24, they can advance to sport-specific drills and begin a return to play progression at 36 weeks.

Conclusion

This hybrid technique provides a reproducible approach to meniscal allograft transplantation, combining secure posterior bone fixation with low-profile anterior soft tissue fixation to optimize graft stability.