Meniscal Transplantation

Introduction

Our understanding of the role of the meniscus has evolved over many years. Dating back to 1948, Fairbank et al. described changes to the knee joint such as narrowing of the joint space, squaring of the femoral condyle, and ridge formation following meniscectomy. This led to his conclusion that a simple meniscectomy is not “wholly innocuous” and it leads to changes in joint mechanics that can be detrimental.

Through the years, extensive research has improved the understanding of meniscal anatomy, biology, mechanics, function, and pathology. This knowledge has adapted our treatment approaches. Prior to Fairbank's work, total meniscectomies were thought to be the ideal choice for knee pain due to a meniscal injury.

Starting in the 1980s, multiple publications identified the benefits of a partial meniscectomy over a total meniscectomy. These benefits included lower contact pressures, less long-term degenerative changes on radiographs, and improved patient satisfaction. Since this research, trends toward meniscal preservation developed including partial meniscectomy or meniscal repair.

Even with all the advances made over the years, there are still complex situations when meniscal preservation is not possible. For these difficult scenarios, meniscal transplantation may be an option. Dating back to 1989 when the first series of meniscal transplantations was published, there has been an increasing acceptance of meniscal allografts used for situations where the meniscus is nonfunctional, symptomatic, and irreparable. This chapter offers a comprehensive review of meniscal transplantation including preoperative workup, indications, techniques, and outcomes.

History

A thorough history is imperative for accurate diagnosis and reasonable treatment recommendations. A detailed understanding of a patient's pain including duration, quality, location, description, and alleviating and aggravating factors can give a valuable insight into their ailment. Other important factors include locking, catching, or swelling that indicates there is a mechanical issue with the knee. Reports of instability with increased joint line tenderness localized to the involved compartment are sometimes seen with meniscu deficiency. Intermittent swelling may also be present, specifically with an increased level of activity. Emphasis should be placed on reports of increasing pain in a particular compartment, because this pain may be associated with increased compartment loading and risk for progressive chondral damage.

Respecting patients’ goals of therapy is also important and can help guide the aggressiveness of treatment. Their age and activity level should be taken into consideration as this can alter the optimal treatment strategies for patients. A thorough surgical history regarding the knee can make future surgical procedures more difficult but also allow the surgeon to understand what state the knee is currently in. It is helpful to obtain prior operative reports as well as arthroscopy images if available to gain a better understanding of the status of the knee.

Physical Examination

The physical exam is key to determining the location of patients’ symptoms. Correlating symptoms with the location of the affected compartment is critical to a successful result.

Additionally, assessment of the patient with meniscal deficiency and/or articular cartilage damage must occur in the context of the alignment, stability, and meniscal status ( Fig. 95.1 ). The physical exam and imagining should focus on understanding the entire context of these factors.

Inspecting the standing alignment of the leg and assessing for varus or valgus angulation is essential to understanding the biomechanical context in which a patient's meniscal deficiency exists and should be substantiated with appropriate imaging. Assessment of range of motion (ROM) is helpful in differentiating the arthritic knee from the healthy knee. Significant motion loss is a contraindication to joint-preserving procedures. The presence or absence of an effusion is also a critical “vital sign” for how the knee is behaving. Joint effusions can be due to many etiologies including trauma, systemic diseases, infection, and mechanical irritation. A knee that is actively delaminating cartilage often presents with recurrent effusions and therefore large effusions can be indicative of progressive articular cartilage loss in this setting.

Focal tenderness along the joint line is also helpful in correlating symptoms in the affected compartment. Although there are a variety of provocative physical exam maneuvers described for detecting meniscal pathology, they are better suited to detecting meniscal tears rather than meniscal deficiency. A comprehensive ligamentous exam is essential, as untreated instability is a contraindication to meniscal reconstruction.

Lastly, since the vast majority of these patients have had prior surgery, assessment of prior incisions on the knee is key to consider as this may limit or alter the surgical plan.

Imaging

The history and physical exam should guide further workup of the patient, which in most cases entails additional imaging.

Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) is a valuable tool in the workup of these patients. It allows the physician to evaluate the soft tissue structures of the knee including the meniscus, cartilage, and ligaments, which are all important to consider when formulating a treatment plan. The MRI can also help assess the integrity and amount of residual meniscus ( Fig. 95.2 ).