Meniscal Allograft Transplantation

Introduction

Loss of meniscal tissue drastically alters the biomechanical environment of the knee joint, especially in the lateral compartment, where contact stress can increase by 200% to 300% after total meniscectomy. Compartment overload syndrome can ensue, presenting with weight-bearing pain and recurrent effusions. Secondary osteoarthritis is a predictable endpoint, which has led to increased awareness among orthopedic surgeons of meniscal transplantation in cases where subtotal or total meniscectomy was unavoidable. In carefully selected patients, meniscal allograft transplantation can provide improved biomechanics and function while providing good pain relief.

Several techniques exist for allograft meniscus transplantation, including bone-plug and bone-bridge techniques, with additional variations within these groups based on different proprietary instrumentation sets. Regardless of the specific technique used, the majority of current transplantations are performed with bony fixation rather than relying on soft tissue healing of the meniscal roots to a prepared bed on the recipient tibial plateau.

This chapter discusses the techniques for open and arthroscopic meniscal allograft transplantation.

Indications

The ideal patient for meniscal allograft transplantation has a history of prior total or subtotal meniscectomy, usually followed by a symptom-free interval of varying duration. This is followed by the onset of weight-bearing pain localized to the involved compartment, frequently with recurrent effusions. The articular surfaces should be without full-thickness chondral defects, ligaments should be stable, and the knee should be normally aligned; otherwise, these comorbidities must be addressed in concurrent or staged fashion. Several reports that investigated the outcomes of concurrent meniscal transplantation and cartilage repair demonstrated results comparable to isolated meniscal transplantation. Therefore, repairable, focal chondral defects should not be viewed as a contraindication.

Contraindications include diffuse arthritic changes and significant joint space narrowing, especially when associated with advanced femoral condyle and tibial flattening, history of inflammatory arthritis, or marked obesity.

Planning

The preoperative radiographic evaluation includes weight-bearing anteroposterior (AP) and posteroanterior 45-degree flexion radiographs, non–weight-bearing 45-degree flexion lateral view, axial view of the patellofemoral joint, and a long-leg mechanical axis view to evaluate malalignment. Furthermore, we routinely perform magnetic resonance imaging to evaluate the joint for articular comorbidities, such as ligamentous or chondral injury.

Meniscal allografts are size-, side-, and compartment-specific; therefore, they must be individually measured and ordered for each patient. Preoperative measurements are obtained from AP and lateral radiographs with magnification markers placed on the skin at the level of the joint line. After accounting for radiographic magnification, meniscal width is measured on the AP radiograph from the edge of the ipsilateral tibial spine to the edge of the tibial plateau. Meniscal length is calculated by multiplying the depth of the tibial plateau (as measured on lateral radiographs) by 0.8 for medial and 0.7 for lateral meniscal grafts ( Fig. 14.1 ).

Technique