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Research: S. Munirah, O. C. Samsudin, H. C. Chen, S. H. Sharifah Salmah, B. S. Aminuddin, and B. H. I. Ruszymah Articular cartilage restoration in load-bearing osteochondral defects by implantation of autologous chondrocyte-fibrin constructs: AN EXPERIMENTAL STUDY IN SHEEP J Bone Joint Surg Br 2007; 89-B: 1099-1109 [Abstract] [Full text] [PDF]

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Articular cartilage restoration in load-bearing osteochondral defects

Benedict A Rogers, Charline Roslee   (15 October 2007)

Articular cartilage restoration in load-bearing osteochondral defects 15 October 2007
Benedict A Rogers, Specialist Registrar The Princess Royal Hospital, Haywards Heath, UK, Charline Roslee Send letter to journal: Re: Articular cartilage restoration in load-bearing osteochondral defects benedictrogers{at}hotmail.com Benedict A Rogers, et al.	Sir, We read this paper with interest and would like to make the following points: 1. Although sheep provide an adequate bone model for experimentation, significant inter-species variations exist in the intrinsic mechanical properties of distal femoral cartilage.1 Since cartilage is a hypocellular and avascular tissue that is intrinsically load sensitive, care must be taken when extrapolating the results of cartilage healing to other species. 2. In the methods section it is indicated that a full thickness punch biopsy was harvested from the trochlear groove, a high-load-bearing region of the distal femoral articular surface. Correlating these results with human autologous chondrocyte implantation (ACI) is difficult since chondrocytes for ACI are routinely harvested from non-weight-bearing regions of the affected knee.2 Is there regeneration of chondral defects using an autologous ‘chondrocyte-fibrin’ construct when the autologous chondrocytes are harvested from non-load-bearing regions? 3. The results report the macroscopic, histological and scanning electron microscopy (SEM) appearance of the regenerated chrondral defects. Despite this extensive structural evaluation, with correlation to the International Cartilage Repair Society (ICRS) classification, no quantification was made of chondral density. Cellular density can be quantified via direct cell counting using a haemocytometer3 or by the use of a fluorometric DNA assay employing a bisbenzimidazole dye.4 4. No quantitative analysis was made of the biochemical composition of the regenerated chrondral tissue which in turn is critical in determining its inherent mechanical properties. Despite the mention that ‘chondrocyte-secreting matrix was evident’ (SEM results), was any quantitative analysis made of the products of chondrocyte metabolism, namely collagen II, glycosaminoglycans, matrix metalloproteins (MMPs) or tissue inhibitors of matrix metalloproteins (TIMPS)? 5. We feel the hypothesis of this study should read, ‘that ACFC would promote early chondrogenesis and induce histological features consistent with hyaline-like cartilage regeneration at 12 weeks post-operation’. B.A. Rogers, MA, MSc, MRCGP, MRCS, Specialist Registrar, C. Roslee, MRCS, Princess Royal Hospital, Haywards Heath, UK. 1. Athanasiou KA, Rosenwasser MP, Buckwalter JA, Malinin TI, Mow VC. Interspecies comparisons of in situ intrinsic mechanical properties of distal femoral cartilage. J Orthop Res 1991;9:330-40. 2. Brittberg M, Lindahl A, Nilsson A, et al. Treatment of deep cartilage defects in the knee with autologous chondrocyte transplantation. N Engl J Med 1994;331:889-95. 3. Ishii I, Mizuta H, Sei A, et al. Healing of full-thickness defects of the articular cartilage in rabbits using fibroblast growth factor-2 and a fibrin sealant. J Bone Joint Surg [Br] 2007;89:693-700. 4. Kim YJ, Sah RL, Doong JY, Grodzinsky AJ. Fluorometric assay of DNA in cartilage explants using Hoechst 33258. Anal Biochem 1988;174:168-76.