Introduction

To facilitate the implantation of cultured chondrocytes and make it possible to perform an autologous chondrocyte implantation (ACI) procedure transarthroscopically, different porous scaffolds have been developed. One such material is based on the benzylic ester of hyaluronic acid (Hyaff 11, Fidia Advanced Biopolymers, Abano Terme, Italy) and consists of a network of 20-μm-thick fibers with interstices of variable sizes.

It has been demonstrated to be an optimal physical support to allow cell-cell contacts, cluster formation, and extracellular matrix deposition and to deliver differentiated chondrocytes.^1,2

The cells harvested from the patient are expanded and then seeded onto the scaffold where the cells are able to redifferentiate and retain a chondrocytic phenotype even after a long period of in vitro expansion in monolayer culture^1,2 (Fig. 9D-1). The Hyalograft with cultured chondrocytes may be implanted by press fitting directly into the lesion as described by Kon et al.³ The scaffold has self-adhesive properties, but most often additional fibrin glue is needed for a secure positioning. In this chapter, the authors describe a modified implantation technique: the “folded blanket” technique for the knee and for the ankle.

FIGURE 9D-1 A Hyalograft with cultured chondrocytes has been implanted subcutaneously into a Severe combined immunodeficiency syndrome (SCID) mouse after 4 weeks of in vitro culture. This section is demonstrating the cartilage tissue produced after 8 weeks in vivo.

Indications

See the indication for ACI described in Chapter 9C.

Technical Overview

Cartilage is harvested as described in Chapter 9C. The cell culture takes a longer time to grow compared to when cells are transplanted as suspension. After 4 to 5 weeks, the scaffold is delivered as 2 × 2 cm large patches (Fig. 9D-2). Depending on the quality of the cultured cells, the seeded scaffolds have different strength.

FIGURE 9D-2 The scaffold is delivered as a 2 × 2 cm large patch.

Operative Technique for the Knee

A high anteromedial or anterolateral portal is created, and a standard arthroscopy is performed in supine position.

The arthroscopic Hyalograft-chondrocyte technique is applicable for defects at the medial and lateral femoral condyle, trochlea, tibial plateau, and in some rare cases when reachable also for the patella.

For a defect at the medial femoral condyle, a medial suprameniscal portal is created. This portal is needed to introduce the matrix into the joint.

A half pipe introducer may be used to introduce the scaffold into the joint.

The defect has already been debrided as described in Chapter 3. The central part of the defect is treated by a microfracture awl to get a fixation point (mushroom fixation) (Fig. 9D-3).

FIGURE 9D-3 The central part of the cartilage defect is treated by a microfracture awl to get a fixation point (mushroom fixation). The central part of the graft is pushed into the hole to get a secure position and fixation.

The chondrocyte-seeded matrix is then cut with a scissor or scalpel to the approximate size of the defect (Fig. 9D-4).

FIGURE 9D-4 The chondrocyte-seeded matrix is cut with a scissor or scalpel to the approximate size of the defect.

The scaffold is covered with a thin fibrin glue layer (Fig. 9D-5), grasped with an arthroscopic grasp instrument with plain surfaces (Fig. 9D-6), and introduced into the joint along the half pipe intruder to reach the defect (Fig. 9D-7).

FIGURE 9D-5 The scaffold is covered with a thin layer of fibrin glue and becomes saturated and easier to handle.

FIGURE 9D-6 The sized graft is grasped with an arthroscopic grasp instrument with plain surfaces.

FIGURE 9D-7 The graft is introduced into the joint along a half pipe intruder to reach the defect area in the knee joint.

The pressure controlled pump may be stopped intermittently during the procedure. (The operation may also be done in CO₂.)

The scaffold is released from the grasper and with a smooth arthroscopy obturator caught and moved into the defect. The central part of the scaffold is pressed gently into the fixation point.

Some extra fibrin glue is injected over the implanted scaffold, and the scaffold is compressed toward the defect bottom with a curved smooth tonsil elevator. If the scaffold is oversized, the edges may be folded like a blanket into the defect to fill it up entirely (Fig. 9D-8).

FIGURE 9D-8 If the scaffold is oversized, the edges may be folded like a blanket into the defect to fill it up entirely.