AUTOLOGOUS CHONDROCYTE IMPLANTATION – ACI



AUTOLOGOUS CHONDROCYTE IMPLANTATION – ACI

LABORATORY AND CLINICAL PROTOCOL, INCLUSION CRITERIA AND POST-OPERATIVE REHABILITATION SCHEDULE

THE HISTORY

The aim of the method is to stimulate the healing of chondral and osteochondral defects using autologous chondrocytes. Peterson and Brittberg pioneered this technique during the past 15 years, with reports (1994,2000,2002) of their own method when chondrocytes were isolated and cultivated under in-vitro conditions and later injected into the defect cavity covered by a periostal flap. However this described method of chondrocyte transplantation is not optimal due to the periostal flap fixation not always being ideally strong or even waterproof, which can result in chondrocyte loss. For this reason the modifications to the original technique focus on a better fixation of the cultured chondrocytes using a suitable three-dimensional carrier scaffold.

THE LIVING DONOR OF AUTOLOGOUS TISSUE

For ACI this is the most common indication which is made by an orthopaedic or trauma surgeon according to the patient's medical and social history and the clinical examination.

TODAY´S ATTITUDE TO ACI

Patients suffering from joint derangements can be indicated for ACI when they fulfill the following indication criteria (abbreviated review):

INDICATIONS

Age: approx. 6 -60 yrs

Diagnoses:

focal chondral defects approaching the subchondral bone, with an area up to about 4x2 cm

osteochondritis dissecans (OCD)

unicompartmental osteoarthritic changes (eg. after meniscectomy, OA grades III) of an area up to 4x2 cm, with a relatively good surrounding hyaline cartilage

fresh cartilage fractures with no possibility of other treatment

unsuccessfull surgical procedures in the patient´s history (eg.microfracturing, abrasion, mosaicplasty etc.)

possibility of combination with other procedures – anterior cruciate ligament (ACL) reconstruction, opening wedge osteotomy

PREOPERATIVE INFORMED CONSENT

Appropriate information concerning the aim of the cartilage recovery, possible risks of the therapeutic treatment and the post-operative rehabilitation program has to be presented in written form and the patient´s consent has to be signed before the cartilage recovery proceeds.

CARTILAGE BIOPSY

The articular cartilage biopsy is obtained arthroscopically from the non-weight bearing area of the patient´s knee, respectively ankle joints, when a rice-seed sample of the hyaline cartilage is harvested.

STANDARD SEROLOGICAL TESTS

The same minimum set of testing requirements  must be applied as for allogeneic living donors:

HIV-1/ HIV-2 Antibody, Hepatitis B Surface Antigen, Hepatitis B Core Antibody, Hepatitic C Virus Antibody and test for syphilis.

Even in the case of positive results the treatment is not excluded.

TRANSPORT OF THE CARTILAGE

The recovered cartilage is placed in the standard recovery kit. The transport to the Cell Culture Laboratory is realized under controlled conditions (standard transport box with appropriate labelling concerning identification of the tissue, identification of the health care facility providing the tissue, identification of the cell culture laboratory, date and time of the recovery and warning FOR AUTOLOGOUS PURPOSES ONLY).

CARTILAGE PROCESSING

The cartilage tissue is cleaned and cut into small pieces under laminar air flow hood conditions. Chondrocytes are embedded in a dense matrix of proteoglycans which must be digested by enzymatic treatment to release therelatively small cellular compartment of the tissue. The fragments of the cartilage are treated with trypsin and collagenase to digest the matrix and to isolate the chondrocytes.

The released chondrocytes are propagated by the standard monolayer technique. The chondrocytes suspended in Ham´s F12 medium supplemented with fetal bovine serum and Gentamycin are inoculated into flasks and cultured in a CO2 atmosphere at 37 C. During successful primocultivation a cell monolayer is formed. The required number of cells is obtained via subculturing of the primoculture. The time needed for cultivation of chondrocytes is on average 3 - 4 weeks.

Proliferation of the chondrocytes is monitored using inverted microscopy. Quality control (QC) of the process is done periodically and includes QC of cultured chondrocytes (morphology and viability) and QC of the culture medium (microbiological and biochemical controls).

AUTOLOGOUS CHONDROGRAFT PREPARATION

Modifications of the original Peterson-Brittberg technique give preference to an improved fixation of the cultured chondrocytes, using a suitable three-dimensional carrier scaffold. In our case the combination of chondrocytes with fibrin glue (Tissucol) resulted in a solid chondrograft formation under the controlled rate solidification process.

The final product is ready for immediate use and is convenient for the surgeon because of its appropriate mechanical properties. It is possible to adapt the size and thickness of the graft according to the cavity's size and depth.

When the ACI surgery has to be postponed the cultured chondrocytes are cryopreserved and the chondrograft is ready to be implanted on demand.

DISTRIBUTION OF THE CHONDROGRAFT

The final product is transported to the hospital in the standard transport kit under controlled conditions (standard transport box with appropriate labelling concerning identification of the product, identification of cell culture laboratory, identification of health care facility, date and time of the chondrograft preparation and warning FOR AUTOLOGOUS PURPOSES ONLY).

CERTIFICATE OF QUALITY CONTROL

The certificate is sent together with chondrograft and includes ID, the morphological and physiological properties of the chondrocytes, the results of the serological tests of the donor, safe-keeping instructions and application instructions.

ACI – SURGICAL PROCEDURE

Depends on the indications, with a wide variety of procedures possible. The procedure is based on using fibrin glue to fix the chondrograft to the defect bottom. Combination with other surgical procedure(s) is possible (eg. ACL reconstruction, opening wedge osteotomy – even both!), of course evidently, after the primary arthroscopic joint evaluation and harvesting of chondrocytes.

POSTOPERATIVE REHABILITATION PROGRAM

Basically, bracing or the use of splint fixation is needed in both (knee, ankle) joints. After the surgery the brace with a limited range of motion (ROM) is adjusted, primarily from the immediate minimal movement (0 to 20 degrees), which is afterwards commonly followed by a release of about 30 degrees more every 2 weeks. Full ROM is allowed after 6 weeks. No-weight bearing is administred during the first 2 months after the surgery, then full weight bearing is allowed. Sports activity is allowed after 6 months.

MAGNETIC RESONANCE IMAGING (MRI) CHECK-UP

Preoperatively (eg. after the harvesting), 2 months after the surgery (to verify the chondrograft´s correct position) and after 1,3,5 yrs (to confirm the healing and ingrowth process).

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