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Combined anterior cruciate ligament reconstruction and meniscal allograft transplantation
OVERVIEW
Chapter synopsis
Combined anterior cruciate ligament (ACL) and meniscal deficiency alters knee function and predisposes the patient to accelerated degenerative osteoarthritis. Combined ACL reconstruction (ACLR) with meniscal allograft transplantation (MAT) has been advocated to treat this combined deficiency. During combined MAT and ACLR, a size-matched meniscal allograft is transplanted into the appropriate compartment. With concomitant ACLR, utilize an autograft or allograft depending on patient’s factors and surgeon’s preference. Studies have shown significant improvement of patient-reported outcome (PRO) scores and return to recreational activities in most patients.
Important points
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Preferably, patients should be under 50 years of age with both symptomatic meniscal and ACL deficiency.
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Transplantation should be avoided in the presence of advanced chondral changes that cannot be addressed with a concomitant cartilage restoration procedure.
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The meniscal allograft can be affixed using a bone bridge or bone plug technique, although we prefer the bone bridge technique (for both lateral and medial meniscus transplants).
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Patients typically can return to recreational activities.
Clinical and surgical pearls
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Soft-tissue allografts (Achilles, hamstring, or tibialis anterior) are generally preferred for ACLR in this setting.
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The meniscus should be positioned as laterally as possible for lateral MAT or as medially as possible for medial MAT to increase the bone bridge between the ACLR tibial tunnel and the MAT slot.
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In a medial MAT, the bone bridge can be notched at the location of the tibial ACL tunnel to lessen contact between the bone and ACL graft.
Clinical and surgical pitfalls
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MAT tibial slot and ACLR tibial tunnel convergence.
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Failure to adequately visualize entire tibia through arthrotomy and arthroscope.
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Neurovascular injury during inside-out suture fixation of the meniscal allograft.
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Broken bone bridge can be avoided by creating a slot 1mm wider than the bone bridge.
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Knowledge of screw/burr rotation in relation to the side of the operation can prevent inadvertent “skating” across the tibia during slot preparation.
Introduction
The menisci play a vital role in normal knee kinematics, contributing to both function and joint stability; this function is exaggerated in the setting of anterior cruciate ligament (ACL) deficiency. The menisci also contribute to joint lubrication, proprioception, and load sharing. They also increase the congruity between the femur and tibia to protect the articular cartilage. Up to 70% of the load can be transmitted through the meniscus in the lateral compartment and up to 50% of the load can be transmitted through the meniscus in the medial compartment. , Consequently, the absence of the menisci can lead to joint space narrowing, seen radiographically. Fairbanks et al. reported significant changes in the knee joint after medial and lateral meniscectomies. This is most likely due to altered loading on the surface of the knee, resulting in progressive damage and eventual osteoarthritis when the meniscus is absent. Although chondral changes occur more rapidly after lateral meniscectomy, medial meniscectomy more predictably results in cartilage degeneration. In the setting of meniscal injuries, meniscal repair or partial meniscectomy is commonly utilized in an attempt to avoid total meniscectomy. However, in the presence of complex and/or deep radial tears, subtotal or total meniscectomy may be unavoidable.
Knees post-meniscectomy with combined ACL deficiency are susceptible to more rapid progression of osteoarthritic degeneration. , In addition, the results of ACLR in knees with medial meniscal deficiency are usually worse than in knees with intact medial menisci. The ACL acts as the primary stabilizer to anterior tibial translation, while the posterior horn of the medial meniscus acts as a secondary stabilizer. The ACL and menisci synergistically maintain knee stability. In an ACL deficient knee, ACLR is recommended to restore the knee to a stable environment in which MAT can succeed. This can be performed in a staged fashion, but a single-stage procedure with combined MAT and ACLR is an option and perhaps preferable. The presence of an intact meniscus has been correlated with better outcomes after ACLR, with loss of either meniscus being associated with fivefold increase in ACL-graft failure 2 years post-surgery. Getgood et al. presented the International Meniscus Reconstruction Experts Forum (IMREF), which recommends MAT be performed as a concomitant procedure to ACLR in the presence of meniscal deficiency based on the long-term follow-up and reported clinical results in peer reviewed literature. Performance of MAT combined with ACLR has been advocated to diminish pain, improve knee stability and function, and delay degenerative changes in the knee. The meniscal graft is expected to protect the ACL and vice versa. , In this chapter, we present our preferred technique to address the combined deficiency of an ACL and a meniscus, as well as published clinical outcomes.
Preoperative considerations
History
It is essential to elicit a thorough history, which includes the initial injury, associated injuries, and prior treatments (conservative and surgical). Prior operative reports are helpful to evaluate arthritic changes, menisci status, prior tunnels position, presence of prior hardware, and more.
Typical history
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Knee injury, often an acute knee injury that may include an episode of hemarthrosis, “giving way,” or a “locked knee.”
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One or more meniscectomies, and possibly ACL reconstruction.
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Persistent pain in the affected compartment and symptomatic instability.
Physical examination
The first step of the physical examination begins with inspection of the patient’s habitus, gait, and bilateral limb alignment, followed by inspection and documentation of muscle atrophy, symmetry, effusion, swelling, compromised skin, and an assessment of the range of motion and motor strength of muscles around the knee. Palpation of the joint line, as well as bony and soft-tissue structures around the knee, is critical to localize tenderness. The ligamentous stability of both knees should be assessed and compared. In order to evaluate the ACL, Lachman, anterior drawer tests, and the pivot-shift test should be performed. If increased anterior tibial translation appreciated during the anterior drawer test is equal to or greater than the Lachman test translation, there is a likely loss of secondary stabilizers from either a deficient posterior horn of the medial meniscus or from posteromedial or posterolateral insufficiency. , Further tests for the evaluation of collateral ligaments, tests for meniscal pathology, and a distal neurovascular exam should conclude the exam, unless other specific tests are indicated.
Imaging
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