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.

If too small, additional pieces of the scaffold are implanted to fill the defect like a patchwork quilt. Several layers of Hyalograft may be needed to fill the defect up to surrounding cartilage (mille feuille technique) (Fig. 9D-9).

FIGURE 9D-9 Several layers of Hyalograft may be needed to fill the defect up to the surrounding cartilage (mille feuille technique).

Excess glue is taken away with a gentle move of the shaver. Care should be taken not to catch the implant with the shaver.

Graft adherence and integration are controlled by moving the knee joint with flexion and extension movements. The scaffold should either be in level with surrounding cartilage or slightly below (Fig. 9D-10).

FIGURE 9D-10 The scaffold after implantation.

The Tibial Plateau

In a defect that is situated on the tibial plateau and often depressed, the repair can be done in a retrograde direction. With a vector guide, a channel is drilled from the proximal tibia to the defect area (Fig. 9D-11). A Hyalograft scaffold is pushed through the channel to the cartilage defect surface followed by a bone graft filling of the channel (Fig. 9D-12). From the inside, a pusher or a curved tonsil elevator keeps the implant in place, while from the channel the bone paste is compressed against the implant with counter press (Fig. 9D-12).

FIGURE 9D-11 Retrograde drilling of a tibia plateau defect. With a vector guide, a channel is drilled from the proximal tibia to the defect area.

FIGURE 9D-12 A Hyalograft scaffold is pushed through the channel to the cartilage defect surface followed by a bone graft filling of the channel. An instrument that gives counter pressure on the Hyalograft is needed to get a compression on the bone grafts.

Hyalograft with Seeded Chondrocytes and Bone Grafting for Osteochondral Defects

When a bone grafting is needed for deep and large osteochondral defects such as osteonecrosis and osteochondritis dissecans (OCD), the seeded scaffold may be used directly in conjunction with bone grafts. The bone grafts may be harvested from the crista iliaca anterior superior region or from the proximal tibia (Fig. 9D-13).

FIGURE 9D-13 Bone grafts may be harvested from the crista iliaca anterior superior region or from the proximal tibia to be used in deep osteochondral defects.

The bone grafts are mixed with fibrin glue to a putty-like consistency, forming bone paste (Fig. 9D-14). The bone grafts are put into a 2-ml syringe where the top of syringe has been cut off leaving a round opening (Fig. 9D-15). The bone grafts may be mixed with an artificial bone substitute if needed.

FIGURE 9D-14 The bone grafts are mixed with fibrin glue to form a putty-like consistency, a bone paste.

FIGURE 9D-15 The bone grafts are put into the 2-ml syringe where the top of syringe has been cut off leaving a round opening.

The bony defect has been prepared by excision and subchondral drilling to stimulate the sclerotic bone region.

Finally, the bone paste is implanted via the syringe into the osteochondral defect (Fig. 9D-16). The bone paste is compressed to fill the osseous part of the defect (Figs. 9D-17 and 9D-18).

FIGURE 9D-16 The bone paste is implanted via the syringe into the osteochondral defect.

FIGURE 9D-17 The bone paste is pushed into the defect to fill up the osseous part to the level of the surrounding cartilage layer.

FIGURE 9D-18 The bone paste in place and compressed.

The cell seeded scaffold is implanted and put over the top of the bone grafts, saturated with fibrin glue (Fig. 9D-19). Extension-flexion motions are used to test the stability of the dual graft (Fig. 9D-20).

FIGURE 9D-19 The cell seeded scaffold is implanted and put over the top of the bone grafts plus additional fibrin glue for a firm adhesion.

FIGURE 9D-20 Hyalograft in place in the defect.

Postoperative Rehabilitation for an Implanted Knee Joint

The extremity is immobilized in a brace locked in extension for 2 weeks (Fig. 9D-21). Full weight bearing is allowed in the brace up to a level that pain allows. After 2 weeks, the brace is used outdoors, unlocked, for another 4 weeks.

FIGURE 9D-21 The extremity is immobilized in a brace locked in extension for 2 weeks.

A large defect may be protected by an unloader brace for a longer period. Or one may even consider performing a concomitant permanent unloading with osteotomy (see also Chapter 12).

The osteotomy can be performed as an arthroscopy plus an osteotomy. The defect is debrided first, followed by the osteotomy, and finally the Hyalograft is implanted transarthroscopically. Rehabilitation is the same as it is without an osteotomy.

Open-chained knee strengthening is advised at approximately 8 weeks postoperatively. Running is not advised until 9 to 10 months postsurgery. High-level activities are not advised before 12 to 14 months.

Preoperative antibiotics such as cloxacillin 1g × 3 times during 24 hours postoperatively are recommended. Antithrombotic treatment with low-fragment heparin once per day is recommended for 2 weeks.

Hyalograft-C Treatment for Talar Lesions of the Ankle

Using a vector guide and an arthroscopic examination through lateral and medial portals, the lesion is reached and debrided. With the vector guide positioned in the lesion, a 3.2-mm drill is used to drill a channel through the malleolus to reach the lesion area (Figs. 9D-22 and 9D-23). The sized graft is pushed through the channel like a handkerchief through a hole, the pusher in the center of the graft and the surrounding parts folded against the channel walls (Fig. 9D-24). When the graft has reached the lesion area, a curved tonsil elevator is inserted via a portal and used to spread out the graft in the lesion (Figs. 9D-25 and 9D-26). If needed, bone grafts can be used to fill a deep osteochondral defect before implantation of the cell graft.

FIGURE 9D-22 A talar defect is treated transarthroscopically by drilling to the defect through the malleolus using a vector guide. Frontal view, 3.2 mm.

FIGURE 9D-23 Lateral view of defect and drilled channel before implantation.

FIGURE 9D-24 The sized graft is pushed through the channel like a handkerchief through a hole; the pusher is in the center of the graft, and the surrounding parts are folded against the channel walls.

FIGURE 9D-25 When the graft has reached the lesion area, a curved tonsil elevator is inserted via a portal and is used to spread out the graft in the lesion.

FIGURE 9D-26 The graft is in place, in level with surrounding cartilage or slightly below.

Postoperative Rehabilitation

The ankle is put in a brace locked in 90 degrees for 2 weeks. Weight bearing is allowed with the brace. After 2 weeks, successive increased motions of the ankle are encouraged.