AMIC or ACI for arthroscopic repair of grade IV acetabular cartilage defects in femoroacetabular impingement.

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1 AMIC or ACI for arthroscopic repair of grade IV acetabular cartilage defects in femoroacetabular impingement. Dr. Andrea Fontana Istituto Auxologico Italiano Milan - Italy

2 Introduction Chondropathies of the acetabulum and the femoral head are a frequent cause of pain and functional limitation often associated to Femoral Acetabolar Impingement (FAI). Moreover, if cartilage defects in the hip are not adequately repaired, then progression of the damage and arthritic changes may occur. Several treatment options are available for the repair of chondral defects, such as debridement, microfracture, autologous chondrocyte implantation (ACI) and autologous matrix induced chondrogenesis (AMIC).

3 Introduction ACI is a two steps procedure. Autologous chondrocytes are seeded on a biodegradable scaffold which is then inserted into the joint to cover the chondral defect. Despite frequent use in the knee, experience with ACI for treatment of damaged cartilage in the hip is limited.

4 Introduction AMIC is a novel, one-step approach that combines microfracture with a collagen type I/III matrix (Chondro-Gide ) to cover the microfractured defect area. In this single-step procedure, the Chondro-Gide matrix is placed over the defect to stabilize the fragile blood clot that arises from microfracture and to provide infrastructure for repair tissue formation.

5 Purpose The aim of this study is to retrospectively evaluate the efficacy of arthroscopic AMIC and arthroscopic ACI for the treatment of grade IV acetabular cartilage defects in femoroacetabular impingement (FAI). Only patients with available data at end of study were included in the study.

6 Material & Methods Patients treated with ACI technique underwent two arthroscopic procedures. In the first operation, once the chondral defect was located, a cartilage biopsy was taken from pulvinar area and chondrocytes were cultured and seeded on the scaffold in the laboratory. In the second operation the scaffold was inserted into the hip via an arthroscopic cannula and positioned to cover the chondral defect.

7 ACI technique

8 Material & Methods AMIC technique. Once the chondral defect was properly measured and shaped, microfracture of the subchondral bone was performed and then the matrix was directly inserted into the joint, using an arthroscopic cannula to prevent its loss in the surrounding tissues. It was then adapted to cover the chondral defect. After having positioned the matrix the traction was released to perform a series of 4-6 extension and rotation movements of the hip. Traction was then re-applied, and the position of the implant was arthroscopically verified. In case the matrix was not stable into the defect it was removed and re-applied using Fibrin glue to fix it.

9 AMIC technique

10 Material & Methods 23 patients (11 male, 12 female) were treated with arthroscopic AMIC with the application of a collagen type I/III bilayer matrix (Chondro-Gide ) and 26 patients (9 male, 17 female) were treated with arthroscopic ACI. Patients were evaluated pre- and post-operatively by the Modified Harris Hip Score (MHHS). Mean patient age at surgery was 38±10 (range years) for AMIC and 38±9 (range years) for ACI. All patients presented grade IV acetabular chondral defects (ICRS classification) with a mean lesion size of 2.5±0.5 cm2 (range cm2) for AMIC and 3.4±1.3 cm2 (range 2-8 cm2) for ACI. Average follow-up was 51 months (range months) for AMIC and 73 months (range months) for ACI. 5 patients in the AMIC and 8 Patients in the ACI group had a concomitant chondropathy of the femoral head treated with microfracture only.

11 Results Baseline MHHS was 45±6 for AMIC and 46±7 for ACI and mean MHHS at end of study was 84±7 for AMIC and 83±7 for ACI. The greatest improvement was observed in the first 6 months and up to 12 months after surgery for both treatments. Improvements were maintained over time until the end of study pre-op post-op polymer hyaluronic acid collagen

12 Conclusion Arthroscopic AMIC and arthroscopic ACI are effective treatments for the repair of grade IV acetabular cartilage defects in FAI with comparable and stable results over time. The AMIC technique is a one-step procedure having advantages regarding costeffectiveness over two-step ACI.