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The chondrogenic potential of carbon fiber and carbon fiber periosteum implants: an ultrastructural study in the rabbit
258 1063-4584/94/040253 + 06 $08.00/0
p o t e n t i a l o f c a r b o n fiber a n d c a r b o n fiber nts: a n u l t r a s t r u c t u r a l s t u d y in t h e rabbit W. REVILLET,M. HEAPES~', d. LYONS': AND D. MUCKLE§
:hildren, Crumlin, Dublin, Ireland; tElectron Microscopy Department, t; ~Department of Anaesthesia, Mater Hospital, Dublin, Ireland; brough General Hospital, Middlesbrough, U.K. Summary bon fiber rods in rabbit knee joints after 75 days of intermittent active motion m carbon fiber rods whose articular surfaces were covered with a free reversed effective in generating:articular tissue; however, tissue with ultrastructural aline cartilage was noted more frequently on the composite implants. If such ective then they might be useful in treating symptomatic osteochondral defects. Carbon, Periosteum, Repair.
the degenerative joint by growth of fibrovascular tissue through the subchondral plate or by surgical transposition of various nonarticular tissues and synthetic materials to osteochondral defects [4]. Several microscopic and biochemical studies have confirmed that synthesis of articular cartilage on osteochondral defects is enhanced following transplantation of free reversed periosteal grafts. Salter has suggested that use of post-operative continuous passive joint motion facilitates chondral metaplasia while joint immobilization inhibits it [5, 6]. Other clinical and experimental studies have confirmed that implanted subarticular woven carbon fiber induces repair by directing proliferating subchondral fibrovascular tissue to the joint surface [7-10]. Clinical data suggest t h a t this treatment may be useful in younger patients with symptomatic chondromalacia and it does not prejudice later arthroplasty [11]. Carbon fiber and periosteum induce chondrogene s i s ~ b y different mechanisms. Carbon fiber promotes subarticular chondrogenesis while periosteum induces surface chondrogenesis by direct metaplasia of the deep zone of cambial cells. It is possible in theory to combine these synthetic mechanisms by adding periosteum to a carbon rod, forming a composite implant. The object of this experimental study was to compare the s t r u c t u r e of articular tissue formed on carbon fiber with tissue formed on carbon fiber/periosteum composite implants. Light and electron microscopy
~tively few cells in load bearing depend on x t h a t contains proteoglycans a fibrils. Proteoglycans provide ~ressive stresses and collagen erdigitating three-dimensional proteoglycans and adds tensile issue [1]. Wear of articular atively common pathological joints that can lead to clinical ~his condition pain is appreciated w h e n attrition of cartilage is so advanced that s ~..h o n d r a l bone has become the load bearing :su~f~ce [2]. Osteochondral allografts m a y be used :~ replace diseased joint surfaces, but the risk of :~sease transmission, graft infection and delay in :~:e|~tal integration precludes general acceptance. ::~osthetic arthroplasty is very effective for older p~:tients, but implant wear, loosening and the certain need for revision surgery in t h e presence of diminishing bone stock must be considered when planning treatment strategies for younger patients. I n t r i n s i c repair of cartilage defects by proliferation of remaining chondrocytes is limited [3]. Extrinsic repair of chondral defects may occur in Submitted 7 March 1994; accepted 16 August 1994. Address correspondence to: Mr W. A. Curtin, 27 Maple Dr., Crampton Pk., Castleknock, Dublin 15, Ireland. 253
254
Curtin et al.: The chondrogenic potential of implants
was applied to all specimens generated in rabbit knee joints. M a t e r i a l s and m e t h o d s Twelve randomly selected, skeletally immature Californian rabbits between 3 and 4 months post n a t a l were used in the study. Anesthesia was induced intravenously (SAFFAN, Glaxovet) and m a i n t a i n e d during surgery with h a l o t h a n e and oxygen. Once the animal was fully anesthetized the right lower limb was isolated in a sterile field. The patellar groove of the distal femur was exposed t h r o u g h a medial parapatellar incision after lateral dislocation of the patella. The cartilage covering the entire patellar groove and the sloping ridges of the medial and lateral femoral condyles was t h e n removed using a small dental burr. Two holes each 3.2 mm in diameter were drilled in the base of the patellar groove distal to the physeal plate to a depth of 6 mm. A carbon fiber rod measuring 6 mm in length was inserted into each drill hole so t h a t the surface of the rod lay just below the articular surface. The periosteum
investing the medial facet of the proximal tibia w a s exposed by extending the skin incision distally and splitting the investing fascia. A free periosteal graft was harvested by sharp dissection and laid on the surface of one rod so t h a t the deep or cambial surface faced the joint cavity. The patella was t h e n reduced and the wound closed with interrupted absorbable sutures. Following surgery, the animals were allowed free motion within the confines of wire mesh cages. Each animal was fed vitamin-enriched commercial chow and water ad libitum. After 75 days the animals were killed by injecting a lethal dose of Nembutal into the peritoneal cavity. The patellar tendon of the operated limb was detached from its tibial insertion so t h a t the whole extensor mechanism could be reflected proximally. Sepsis was noted in one joint. No articular cartilage was recovered from either implant site in this animal. A n o t h e r animal yielded cartilaginous tissue from only one locus in which a carbon rod had been implanted. In the remaining animals (N = 10), tissue t h a t resembled cartilage was recovered from both implant sites. This cartilaginous tissue was excised
FIG. 1. (a) Light micrograph of the best differentiated sample obtained from a carbon fiber implant. Although there is some chondral metaplasia in the basal zone, the remaining tissue contains elongated fibroblasts arranged in concentric lamellae. Scale bar = 50 pm. (Toluidine blue.) (b) Light micrograph of typical fibrous histological appearance of samples obtained from carbon fiber implants. The tissue contains numerous fibroblasts and intercellular matrix which stains poorly with toluidine blue. Scale bar = 50 #m.
Osteoarthritis and Cartilage Vol. 2 No. 4
tzor blade, it was t h e n fixed in in 0.1 M phosphate buffer (pH hed in phosphate buffer for 1~/o Osmium Tetroxide at 2°C d in a graded series of acetone t in Araldite resin. tions from each sample were croscopy with 1~/o toluidine [y adjacent semi-thin sections ) mesh copper grids, stained ate in absolute m e t h a n o l and ~eynolds' lead citrate. The examined at 80 kV in a Jeol icroscope. Results ' FIBER IMPLANTS
doped post-operative septic tissue was synthesized in this animal, tissue was noted on ~rill hole into which a carbon ~ 11). Differentiation into
255
in three samples, in the remainder fibrocartilage was formed [Fig. l(a), (b)]. Electron microscopy showed t h a t these poorly differentiated samples contained elongated cells with large nuclei and scanty cytoplasm. Between contiguous cells, bundles of closely packed collagen fibrils pursued a convoluted course parallel to the j o i n t surface [Fig. 2(a), (b)]. CARBON FIBER/PERIOSTEUM
IMPLANTS
Tissue was recovered from 10 of the 11 sites Occupied by the composite implants. Of these samples eight demonstrated characteristics of articular cartilage. Under light microscopy the intercellular matrix demonstrated m e t a c h r o m a t i c staining with toluidine blue. R o u n d cell morphology and cell clusters were noted t h r o u g h the full thickness of these samples (Fig.3). Electron microscopy showed t h a t these specimens h a d m a n y of the u l t r a s t r u c t u r a l features of rabbit patellar groove cartilage [12]. Cell membrane filopodiae, and cytoplasm with rough endoplasmic reticulum, glycogen and mitochondriae were observed [Fig. 4(a)]. A zone of pericellular m a t r i x t h a t
FIG. 2. (a) Representative electron micrograph of typical cells noted in poorly differentiated samples from carbon fiber implants. The cells were elongated with scanty cytoplasm. Pericellular matrix was never observed around such cells. Scale bar = 3 #m. (b) High magnification electron micrograph from a representative poorly differentiated tissue sample generated on carbon fiber. Closely packed, banded fibrils were aligned parallel or almost parallel to the joint surface in such samples. Scale bar = 0.2 #m.
256
Curtin e t a l . : The chondrogenic potential of implants
articular
surface
FIG. 3. Light micrograph of a well-differentiated sample from carbon fiber/periosteum implants. These samples show characteristic hypocellularity, chondrocyte clusters and matrix affinity for toluidine blue. Scale bar = 43 #m.
FIG. 4. (a) Electron micrograph demonstrating certain ultrastructural features of articular cartilage in well-differentiated samples from composite implants. Cell membranes were infolded to produce numerous surface filopodiae which projected into a zone of pericellular matrix. Each cell contained a single nucleus and cytoplasm rich in mitochondriae and rough endoplasmic reticulum. Scale bar = 2 #m. (b) Representative high magnification electron micrograph of intercellular matrix from cartilage obtained from typical well-differentiated samples. Collagen fibrils were randomly aligned in these samples. The matrix between t h e m assumed a faint reticular pattern. Scale bar = 0.2 #m.
Osteoarthritis and Cartilage Vol. 2 No. 4
257
:'5 Electron micrograph of elongated structures noted in well-differentiated samples from composite implants. These i~:~ug~ested that the tissue was derived from periosteum. Each structure contained an electron dense outer envelope and ~n~ ~Iectron lucent core with microfibrils aligned along its long axis. Scale bar = 1 pm. . .cp~ained circumferentially arranged small caliber i ~ i l s separated the cells from the larger caliber, omly arranged collagen fibrils of the intercelKii~r ..... matrix [Fig. 4(b)]. In these well-differentiated : i ~ p l e s , elongated cigar shaped structures were 0b~erved under electron microscopy. At high mag.':~i'~6ation they were observed to consist of an ~i~ctron dense o u t e r rim and a lucent interior that ~ i ~ t a i n e d microfibrils aligned along their long :~:~is (Fig. 5). These structures have been previously d e s c r i b e d in the fibrous zone of periosteum and ~gest, therefore, that the tissue was derived from ~ o s t e u m (W. Curtin, unpublished observations). Discussion
Resurfacing of diseased joint surfaces with healthy cartilage is an attractive alternative. Morbidity associated with this type of surgery is m~nimal and resurfacing does not preclude ::definitive prosthetic arthroplasty later. Niedermann reported on five patients with symptomatic knee chondropathy treated by free periosteal grafts. Four patients were relieved of their preoperative symptoms and serial arthroscopic examinations revealed gradual filling of the
original defect with cartilaginous tissue [13]. Ritsala reported similar favorable results in treating knee and metatarsophalangeal a r t h r o p a t h y with periosteal and perichondral grafts [14]. Carbon fiber is well tolerated in synovial joints if it is implanted in a non load bearing capacity below the articular surface. In this w a y carbon fragmentation and synovitis is avoided. M u c k l e and Minns reported the results of carbon arthroplasty in 47 patients [t0]. At arthroscopy, 36 patients had no evidence of synovitis or carbon pigmentation, nine patients had mild pigmentation but no evidence of synovitis. A f u r t h e r clinical assessment of 96 patients whose mean age was 38 .~years showed that 76 patients experienced improvement in pain and function. Synovitis and progressive arthropathy were not observed in this group [11]. The present study demonstrated t h a t addition of periosteum to the surface of an implanted carbon fiber rod yielded a higher proportion of grafts with ultrastructural features of hyaline articular cartilage (80%). Carbon fiber implants yielded fewer well-differentiated grafts (27%). The yield of well-differentiated grafts was also higher than that observed following implantation of free periosteal
258
Curtin et al.: The chondrogenic potential of implants
grafts into animals of similar chronological age u n d e r similar experimental conditions (40%) [13]. Applying periosteum directly on carbon did not have an adverse effect on its capacity for chondral metaplasia. The excellent differentiation of the composite grafts suggests t h a t it may be possible for the periosteum to obtain a dual n u t r i t i o n from synovial fluid and tissue fluids which are transported to the surface of the carbon rod by capillary motion. In this study the grafts were assessed at 75 days. Salter has d e m o n s t r a t e d that, after 1 year, periosteal grafts can yield tissue which morphologically resembles hyaline a r t i c u l a r cartilage [6]. Usually the results of experimental studies should not be directly e x t r a p o l a t e d - t o clinical practice. The biological response to surface replacement, is less vigorous in humans t h a n in smaller animals. In this experimental study, adding periosteum to the surface of a carbon rod improved the quality of the repair tissue. It seems reasonable to consider, therefore, t h a t using similar composite implants in clinical practice could improve the results of carbon arthroplasty. It is likely t h a t composite implants will be most successful in young patients where the chondrogenic potential of periosteum is maximal.
References 1. Kempson GE, Muir H, Pollard C, Tuke MA. The tensile properties of the cartilage of human femoral condyles related to the content of collagen and glycosaminoglycans. Biochem Biophys Acta 1972;297:456-62. 2. Arnoldi C, Lemberg RK, Linderholm H. Intraosseous pain and hypertension in the knee. J Bone Joint Surg [Br] 1975;57:360-3. 3. DePalma AF, McKeever CD, Subin DK. Process of repair of articular cartilage demonstrated by histology and auroradiography with tritiated thymidine. Clin Orthop 1966;48:229-42.
4. Shimizu T, Videman T Shimazaki K, Mooney V. Experimental study on the repair of full thickness articular cartilage defects: effects of continuous passive motion, cage activity and immobilization. J Orthop Res 1987;5:187-97. 5. Salter R, O'Driscoll SW, Keeley F. The chondrogenic potential of free autogenous periosteal grafts for biological resurfacing of major full-thickness defects in joint surfaces under the influence of continuous passive motion. J Bone Joint Surg [Am] 1986;68:1017-34. 6. Salter R, O'Driscoll SW, Keeley F. Durability of regenerated articular cartilage produced by free autogenous periosteal grafts in major fullthickness defects in joint surfaces under the influence of continuous passive motion. J Bone Joint Surg [Am] 1988;69:595-606. 7. Minns RJ,, Muckle DS, Donkin JE. The repair of osteochondral ,defects in osteoarthritic rabbit knees by the use of carbon fibre. Biomaterials 1982;3:81-6. 8. Minns RJ BettslJA, Muckle DS et al. Carbon fibre arthroplasty of the knee: preliminary clinical experience in a new concept of biological resurfac~ ing. In: Noble J; Glasko B, Eds. Recent developments in orthopaedic surgery. Manchester: Manchester University Press 1987:282-9. 9. Minns RJ, Muckle DS. Mechanical and histological response of carbon fibre pads implanted in the rabbit patella. Biomaterials 1989;10:273-6. 10. Muckle DS, Minns RJ. B~:01ogicalresponse to woven carbon fibre pads in the:!~knee. J Bone Joint Surg [Br] 1990;71:60-2. 11. Pongor P, Betts J, Muckle D Bently G. Woven carbon surface replacement in the knee: independent clinical review. Biomaterials 1992:15; 1070-6. 12. Curtin WA, Reville J, Brady MP. Quantitative and morphological observations on the ultrastructure of articular tissue generated from free periosteal grafts. J Elect Microscopy 1992;41:82-90. 13. Niederman B, Boe S; Lauritzen J, Rubak J. Glued periosteal grafts in the knee. Acta Orthop Scand 1985;56:457-60. 14. Ritsala V, Poussa M, Rubak J, Snellman O, Osterma K. Periosteal and perichondral grafts in the reconstruction of joint surfaces. Acta Orthop Scand 1981;52:447-51.
p o t e n t i a l o f c a r b o n fiber a n d c a r b o n fiber nts: a n u l t r a s t r u c t u r a l s t u d y in t h e rabbit W. REVILLET,M. HEAPES~', d. LYONS': AND D. MUCKLE§
:hildren, Crumlin, Dublin, Ireland; tElectron Microscopy Department, t; ~Department of Anaesthesia, Mater Hospital, Dublin, Ireland; brough General Hospital, Middlesbrough, U.K. Summary bon fiber rods in rabbit knee joints after 75 days of intermittent active motion m carbon fiber rods whose articular surfaces were covered with a free reversed effective in generating:articular tissue; however, tissue with ultrastructural aline cartilage was noted more frequently on the composite implants. If such ective then they might be useful in treating symptomatic osteochondral defects. Carbon, Periosteum, Repair.
the degenerative joint by growth of fibrovascular tissue through the subchondral plate or by surgical transposition of various nonarticular tissues and synthetic materials to osteochondral defects [4]. Several microscopic and biochemical studies have confirmed that synthesis of articular cartilage on osteochondral defects is enhanced following transplantation of free reversed periosteal grafts. Salter has suggested that use of post-operative continuous passive joint motion facilitates chondral metaplasia while joint immobilization inhibits it [5, 6]. Other clinical and experimental studies have confirmed that implanted subarticular woven carbon fiber induces repair by directing proliferating subchondral fibrovascular tissue to the joint surface [7-10]. Clinical data suggest t h a t this treatment may be useful in younger patients with symptomatic chondromalacia and it does not prejudice later arthroplasty [11]. Carbon fiber and periosteum induce chondrogene s i s ~ b y different mechanisms. Carbon fiber promotes subarticular chondrogenesis while periosteum induces surface chondrogenesis by direct metaplasia of the deep zone of cambial cells. It is possible in theory to combine these synthetic mechanisms by adding periosteum to a carbon rod, forming a composite implant. The object of this experimental study was to compare the s t r u c t u r e of articular tissue formed on carbon fiber with tissue formed on carbon fiber/periosteum composite implants. Light and electron microscopy
~tively few cells in load bearing depend on x t h a t contains proteoglycans a fibrils. Proteoglycans provide ~ressive stresses and collagen erdigitating three-dimensional proteoglycans and adds tensile issue [1]. Wear of articular atively common pathological joints that can lead to clinical ~his condition pain is appreciated w h e n attrition of cartilage is so advanced that s ~..h o n d r a l bone has become the load bearing :su~f~ce [2]. Osteochondral allografts m a y be used :~ replace diseased joint surfaces, but the risk of :~sease transmission, graft infection and delay in :~:e|~tal integration precludes general acceptance. ::~osthetic arthroplasty is very effective for older p~:tients, but implant wear, loosening and the certain need for revision surgery in t h e presence of diminishing bone stock must be considered when planning treatment strategies for younger patients. I n t r i n s i c repair of cartilage defects by proliferation of remaining chondrocytes is limited [3]. Extrinsic repair of chondral defects may occur in Submitted 7 March 1994; accepted 16 August 1994. Address correspondence to: Mr W. A. Curtin, 27 Maple Dr., Crampton Pk., Castleknock, Dublin 15, Ireland. 253
254
Curtin et al.: The chondrogenic potential of implants
was applied to all specimens generated in rabbit knee joints. M a t e r i a l s and m e t h o d s Twelve randomly selected, skeletally immature Californian rabbits between 3 and 4 months post n a t a l were used in the study. Anesthesia was induced intravenously (SAFFAN, Glaxovet) and m a i n t a i n e d during surgery with h a l o t h a n e and oxygen. Once the animal was fully anesthetized the right lower limb was isolated in a sterile field. The patellar groove of the distal femur was exposed t h r o u g h a medial parapatellar incision after lateral dislocation of the patella. The cartilage covering the entire patellar groove and the sloping ridges of the medial and lateral femoral condyles was t h e n removed using a small dental burr. Two holes each 3.2 mm in diameter were drilled in the base of the patellar groove distal to the physeal plate to a depth of 6 mm. A carbon fiber rod measuring 6 mm in length was inserted into each drill hole so t h a t the surface of the rod lay just below the articular surface. The periosteum
investing the medial facet of the proximal tibia w a s exposed by extending the skin incision distally and splitting the investing fascia. A free periosteal graft was harvested by sharp dissection and laid on the surface of one rod so t h a t the deep or cambial surface faced the joint cavity. The patella was t h e n reduced and the wound closed with interrupted absorbable sutures. Following surgery, the animals were allowed free motion within the confines of wire mesh cages. Each animal was fed vitamin-enriched commercial chow and water ad libitum. After 75 days the animals were killed by injecting a lethal dose of Nembutal into the peritoneal cavity. The patellar tendon of the operated limb was detached from its tibial insertion so t h a t the whole extensor mechanism could be reflected proximally. Sepsis was noted in one joint. No articular cartilage was recovered from either implant site in this animal. A n o t h e r animal yielded cartilaginous tissue from only one locus in which a carbon rod had been implanted. In the remaining animals (N = 10), tissue t h a t resembled cartilage was recovered from both implant sites. This cartilaginous tissue was excised
FIG. 1. (a) Light micrograph of the best differentiated sample obtained from a carbon fiber implant. Although there is some chondral metaplasia in the basal zone, the remaining tissue contains elongated fibroblasts arranged in concentric lamellae. Scale bar = 50 pm. (Toluidine blue.) (b) Light micrograph of typical fibrous histological appearance of samples obtained from carbon fiber implants. The tissue contains numerous fibroblasts and intercellular matrix which stains poorly with toluidine blue. Scale bar = 50 #m.
Osteoarthritis and Cartilage Vol. 2 No. 4
tzor blade, it was t h e n fixed in in 0.1 M phosphate buffer (pH hed in phosphate buffer for 1~/o Osmium Tetroxide at 2°C d in a graded series of acetone t in Araldite resin. tions from each sample were croscopy with 1~/o toluidine [y adjacent semi-thin sections ) mesh copper grids, stained ate in absolute m e t h a n o l and ~eynolds' lead citrate. The examined at 80 kV in a Jeol icroscope. Results ' FIBER IMPLANTS
doped post-operative septic tissue was synthesized in this animal, tissue was noted on ~rill hole into which a carbon ~ 11). Differentiation into
255
in three samples, in the remainder fibrocartilage was formed [Fig. l(a), (b)]. Electron microscopy showed t h a t these poorly differentiated samples contained elongated cells with large nuclei and scanty cytoplasm. Between contiguous cells, bundles of closely packed collagen fibrils pursued a convoluted course parallel to the j o i n t surface [Fig. 2(a), (b)]. CARBON FIBER/PERIOSTEUM
IMPLANTS
Tissue was recovered from 10 of the 11 sites Occupied by the composite implants. Of these samples eight demonstrated characteristics of articular cartilage. Under light microscopy the intercellular matrix demonstrated m e t a c h r o m a t i c staining with toluidine blue. R o u n d cell morphology and cell clusters were noted t h r o u g h the full thickness of these samples (Fig.3). Electron microscopy showed t h a t these specimens h a d m a n y of the u l t r a s t r u c t u r a l features of rabbit patellar groove cartilage [12]. Cell membrane filopodiae, and cytoplasm with rough endoplasmic reticulum, glycogen and mitochondriae were observed [Fig. 4(a)]. A zone of pericellular m a t r i x t h a t
FIG. 2. (a) Representative electron micrograph of typical cells noted in poorly differentiated samples from carbon fiber implants. The cells were elongated with scanty cytoplasm. Pericellular matrix was never observed around such cells. Scale bar = 3 #m. (b) High magnification electron micrograph from a representative poorly differentiated tissue sample generated on carbon fiber. Closely packed, banded fibrils were aligned parallel or almost parallel to the joint surface in such samples. Scale bar = 0.2 #m.
256
Curtin e t a l . : The chondrogenic potential of implants
articular
surface
FIG. 3. Light micrograph of a well-differentiated sample from carbon fiber/periosteum implants. These samples show characteristic hypocellularity, chondrocyte clusters and matrix affinity for toluidine blue. Scale bar = 43 #m.
FIG. 4. (a) Electron micrograph demonstrating certain ultrastructural features of articular cartilage in well-differentiated samples from composite implants. Cell membranes were infolded to produce numerous surface filopodiae which projected into a zone of pericellular matrix. Each cell contained a single nucleus and cytoplasm rich in mitochondriae and rough endoplasmic reticulum. Scale bar = 2 #m. (b) Representative high magnification electron micrograph of intercellular matrix from cartilage obtained from typical well-differentiated samples. Collagen fibrils were randomly aligned in these samples. The matrix between t h e m assumed a faint reticular pattern. Scale bar = 0.2 #m.
Osteoarthritis and Cartilage Vol. 2 No. 4
257
:'5 Electron micrograph of elongated structures noted in well-differentiated samples from composite implants. These i~:~ug~ested that the tissue was derived from periosteum. Each structure contained an electron dense outer envelope and ~n~ ~Iectron lucent core with microfibrils aligned along its long axis. Scale bar = 1 pm. . .cp~ained circumferentially arranged small caliber i ~ i l s separated the cells from the larger caliber, omly arranged collagen fibrils of the intercelKii~r ..... matrix [Fig. 4(b)]. In these well-differentiated : i ~ p l e s , elongated cigar shaped structures were 0b~erved under electron microscopy. At high mag.':~i'~6ation they were observed to consist of an ~i~ctron dense o u t e r rim and a lucent interior that ~ i ~ t a i n e d microfibrils aligned along their long :~:~is (Fig. 5). These structures have been previously d e s c r i b e d in the fibrous zone of periosteum and ~gest, therefore, that the tissue was derived from ~ o s t e u m (W. Curtin, unpublished observations). Discussion
Resurfacing of diseased joint surfaces with healthy cartilage is an attractive alternative. Morbidity associated with this type of surgery is m~nimal and resurfacing does not preclude ::definitive prosthetic arthroplasty later. Niedermann reported on five patients with symptomatic knee chondropathy treated by free periosteal grafts. Four patients were relieved of their preoperative symptoms and serial arthroscopic examinations revealed gradual filling of the
original defect with cartilaginous tissue [13]. Ritsala reported similar favorable results in treating knee and metatarsophalangeal a r t h r o p a t h y with periosteal and perichondral grafts [14]. Carbon fiber is well tolerated in synovial joints if it is implanted in a non load bearing capacity below the articular surface. In this w a y carbon fragmentation and synovitis is avoided. M u c k l e and Minns reported the results of carbon arthroplasty in 47 patients [t0]. At arthroscopy, 36 patients had no evidence of synovitis or carbon pigmentation, nine patients had mild pigmentation but no evidence of synovitis. A f u r t h e r clinical assessment of 96 patients whose mean age was 38 .~years showed that 76 patients experienced improvement in pain and function. Synovitis and progressive arthropathy were not observed in this group [11]. The present study demonstrated t h a t addition of periosteum to the surface of an implanted carbon fiber rod yielded a higher proportion of grafts with ultrastructural features of hyaline articular cartilage (80%). Carbon fiber implants yielded fewer well-differentiated grafts (27%). The yield of well-differentiated grafts was also higher than that observed following implantation of free periosteal
258
Curtin et al.: The chondrogenic potential of implants
grafts into animals of similar chronological age u n d e r similar experimental conditions (40%) [13]. Applying periosteum directly on carbon did not have an adverse effect on its capacity for chondral metaplasia. The excellent differentiation of the composite grafts suggests t h a t it may be possible for the periosteum to obtain a dual n u t r i t i o n from synovial fluid and tissue fluids which are transported to the surface of the carbon rod by capillary motion. In this study the grafts were assessed at 75 days. Salter has d e m o n s t r a t e d that, after 1 year, periosteal grafts can yield tissue which morphologically resembles hyaline a r t i c u l a r cartilage [6]. Usually the results of experimental studies should not be directly e x t r a p o l a t e d - t o clinical practice. The biological response to surface replacement, is less vigorous in humans t h a n in smaller animals. In this experimental study, adding periosteum to the surface of a carbon rod improved the quality of the repair tissue. It seems reasonable to consider, therefore, t h a t using similar composite implants in clinical practice could improve the results of carbon arthroplasty. It is likely t h a t composite implants will be most successful in young patients where the chondrogenic potential of periosteum is maximal.
References 1. Kempson GE, Muir H, Pollard C, Tuke MA. The tensile properties of the cartilage of human femoral condyles related to the content of collagen and glycosaminoglycans. Biochem Biophys Acta 1972;297:456-62. 2. Arnoldi C, Lemberg RK, Linderholm H. Intraosseous pain and hypertension in the knee. J Bone Joint Surg [Br] 1975;57:360-3. 3. DePalma AF, McKeever CD, Subin DK. Process of repair of articular cartilage demonstrated by histology and auroradiography with tritiated thymidine. Clin Orthop 1966;48:229-42.
4. Shimizu T, Videman T Shimazaki K, Mooney V. Experimental study on the repair of full thickness articular cartilage defects: effects of continuous passive motion, cage activity and immobilization. J Orthop Res 1987;5:187-97. 5. Salter R, O'Driscoll SW, Keeley F. The chondrogenic potential of free autogenous periosteal grafts for biological resurfacing of major full-thickness defects in joint surfaces under the influence of continuous passive motion. J Bone Joint Surg [Am] 1986;68:1017-34. 6. Salter R, O'Driscoll SW, Keeley F. Durability of regenerated articular cartilage produced by free autogenous periosteal grafts in major fullthickness defects in joint surfaces under the influence of continuous passive motion. J Bone Joint Surg [Am] 1988;69:595-606. 7. Minns RJ,, Muckle DS, Donkin JE. The repair of osteochondral ,defects in osteoarthritic rabbit knees by the use of carbon fibre. Biomaterials 1982;3:81-6. 8. Minns RJ BettslJA, Muckle DS et al. Carbon fibre arthroplasty of the knee: preliminary clinical experience in a new concept of biological resurfac~ ing. In: Noble J; Glasko B, Eds. Recent developments in orthopaedic surgery. Manchester: Manchester University Press 1987:282-9. 9. Minns RJ, Muckle DS. Mechanical and histological response of carbon fibre pads implanted in the rabbit patella. Biomaterials 1989;10:273-6. 10. Muckle DS, Minns RJ. B~:01ogicalresponse to woven carbon fibre pads in the:!~knee. J Bone Joint Surg [Br] 1990;71:60-2. 11. Pongor P, Betts J, Muckle D Bently G. Woven carbon surface replacement in the knee: independent clinical review. Biomaterials 1992:15; 1070-6. 12. Curtin WA, Reville J, Brady MP. Quantitative and morphological observations on the ultrastructure of articular tissue generated from free periosteal grafts. J Elect Microscopy 1992;41:82-90. 13. Niederman B, Boe S; Lauritzen J, Rubak J. Glued periosteal grafts in the knee. Acta Orthop Scand 1985;56:457-60. 14. Ritsala V, Poussa M, Rubak J, Snellman O, Osterma K. Periosteal and perichondral grafts in the reconstruction of joint surfaces. Acta Orthop Scand 1981;52:447-51.