摘要:

AbstractThe purpose of this investigation was to examine the extracellular matrix of rabbit ligament before and after digestion with glycosaminoglycan degrading enzymes. In order to preserve and enhance the visibility of negatively charged tissue components, particularly the glycosaminoglycancontaining proteoglycans, the, cationic stains ruthenium red (RR) and ruthenium hexammine trichloride (RHT) were used. Cross‐sections of the midsubstance of 10‐month‐old (mature) rabbit medial collateral ligaments fixed using conventional procedures revealed a sparse population of stellate‐shaped cells that did not appear to be interconnected. Similar tissue fixed in either RR or RHT showed an extensive network of thin, electron‐dense “seams” that interconnected cells and appeared to irregularly subdivide the extracellular matrix (ECM). These seams mainly consisted of a meshwork of microfilaments throughout which small granules were dispersed. Numerous 14‐nm microfibrils, as well as mature elastic fibers were also present within the seams. The size and shape of the microfilaments, together with their threadlike, beaded appearance suggested that they could be Type VI collagen. The seam granules were easily removed with chondroitinase ABC, chondroitinase AC II, and mild (0.18M) salt treatment. Only chondroitinase ABC succeeded in removing additional granules, tentatively identified as proteodermatan sulphate molecules, that were periodically located at d band sites along the Type I collagen fibrils. These results suggest that the seam granules are not dermatan sulphate containing proteoglycans, and further, that these proteoglycans may be sequestered into specific zones within the ECM through loose association with the seam microfilaments. While the functional significance of the seams remains unknown and their specific composition clearly requires further study, it is likely that they represent important functional (e.g., viscoelastic) or biological (e.g., nutritional) subdivisions of lig

ISSN:0736-0266    

DOI:10.1002/jor.1100080102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe concept that flexor tendons have the intrinsic capacity to participate actively in the repair process following laceration has been developed in recent years as the result of experimental studies from numerous laboratories. However, the role of the outer/epitenon and inner/endotenon cell populations with regard to protein synthesis is still controversial. The purpose of this study was to investigate the respective participation of these tendon fibroblast populations in the synthesis of the collagen matrix during in vitro repair of the flexor tendon from nonhuman primates, utilizing immunohistochemical techniques and a Type I procollagen antibody. Zone II profundus flexor tendon segments were obtained from young adultMacaca nemestrinamonkeys. One centimeter segments were cultured either with or without a transverse laceration across 90% of the midsection of the tendon segment. Frozen sections of the cultured tendon segments were reacted with the (mouse monoclonal) Type I procollagen antisera. At all times of culture of the nonlacerated tendon segment, only a few of the epitenon cells along the surface of the tendon and distant from the cut end stained positively for active collagen synthesis. In the lacerated segments, and as early as 9 days of culture and repair, the procollagen reaction product was starting to appear in those cells of the outer epitenon cell layer. These studies support the concept that the inner fibroblasts do actively participate in collagen production. However, it now also appears that a significant degree of collagen synthesis during tendon repair resides in the outer/epitenon layer of cells enveloping the tendon segment, and that the repair response of the flexor tendon in vitro is proportional to the degree of injury.

ISSN:0736-0266    

DOI:10.1002/jor.1100080103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractWe analyzed the healing capability of the human superficialis (sublimus) flexor tendon in response to injury in vitro by performing a morphologic study of tendon repair. Tendon segments were cultured in cell‐free medium for 2, 4, or 8 weeks, and the cut‐end repair sites were compared with those in fresh control segments on light and electron microscopy. Tendon encapsulation had occurred at 2 weeks, by the proliferation and migration of elongated fibroblasts from the epitenon and from collagen bundles of the endotenon to cover the surface of the cut tendon ends. As migrating epitenon cells approached the cut margin, they consistently shifted from a parallel to a circumferential orientation with respect to the tendon axis. By 4 weeks, the encapsulating surface cells had lost their membranous ruffles and had become flattened. Within the capsule, phagocytic cells engulfed collagen debris, and fibroblasts containing extensive rough endoplasmic reticulum profiles and secretory vesicles participated in protein synthesis. The surface of the capsule was smooth and, at 8 weeks, was almost indistinguishable from the epitenon surface of uncultured controls. The capsule now had a collagen‐synthesizing layer of fibroblasts superimposed on layers of maturing collagen bundles that separated restingphase fibroblasts. These findings demonstrate that segments of human superficialis flexor tendons participate in an intrinsic repair response without contributions from extrinsic

ISSN:0736-0266    

DOI:10.1002/jor.1100080104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThis investigation was designed to study the biomechanical recovery of a free bone‐ligament‐bone graft that was returned to its normal extraarticular position, with as little disturbance to its mechanical and biological environments as possible. Twenty‐five adult New Zealand white rabbits had their right bone‐medial collateral ligament (MCL)‐bone complex removed completely and replaced immediately using internal fixation. Animals were allowed unrestricted cage activity before sacrifice in groups of five at intervals of 3, 6, 12, 24, and 48 weeks posttransplantation. Contralateral legs served as internal controls and a separate series of normal animals served as external controls. All MCLs were tested biomechanically using a detailed testing protocol. Results showed early deterioration of 20–35% in autograft complex structural behavior, with weakening of both ligament substance and insertions. Viscoelastic behavior of these ligaments was also affected, showing increases in the amount of both cyclic load‐relaxation and static load‐relaxation at early healing intervals. These properties were statistically indistinguishable, however, from controls at 48 weeks. Failure behavior of autografts was even better preserved, reaching a low of 65% of control values at 24 weeks and recovering to within 10% of controls at 48 weeks. These results, plus the major changes in failure modes that occurred over that duration, suggest that autograft incorporation is a slow but dynamic process. These results further suggest that at least some connective tissue autografts, when placed under, as yet undefined, “proper biological and mechanical conditions,” can retain and recover a number of biomechanical properties over a period of 1 year. The longer‐term fate of these autografts and the exact nature of their similarities or differences from other graft alternatives (e.g., tendon for ligament)

ISSN:0736-0266    

DOI:10.1002/jor.1100080105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThis study was designed to test the mechanical behavior of a frozen/thawed bone‐medial collateral ligament (MCL)‐bone allograft in a rabbit model and to compare allograft behavior with contralateral unoperated ligaments as well as a group of normal bone‐ligament‐bone preparations prior to freezing. Twenty‐five mature rabbits received similarly frozen bone‐MCL‐bone allografts and were subsequently allowed to heal without immobilization in groups of five for 3, 6, 12, 24, or 48 weeks after transplantation. A series of biomechanical tests was performed on each allograft, contralateral, and external normal control ligament. Results demonstrated that allografts were significantly tighter than controls at 3 weeks and they remained tight over time. All allografts, however, had inferior structural and material behaviors as compared with controls. Allograft insertional bone and substance deteriorated to about 60% of contralateral strength at 12 and 48 weeks. Bony insertions became the most common site of graft weakness. Both stress at failure and the elastic modulus of allograft substance similarly reached a plateau at those intervals, but at about 30% of contralateral controls. Cyclic and load relaxation properties of allografts, on the other hand, did not deteriorate and were, in fact, indistinguishable from contralateral and normal values at 48 weeks. Comparison with a series of fresh autografts suggests that, with the exception of this viscoelastic recovery, allografts were mechanically inferior to autografts in their healing at the intervals tested. Collectively, these results suggest that allograft MCL healing in this composite model is dynamic but slow, featuring changes in bone and soft tissue over the first year after transplantation. Although “viable” and vascular, allografts have not normalized mechanically and, in fact, appear to have reached a new equilibrium whereby properties are neither improving nor deteriorating. Despite this apparent equilibrium, the trend for some viscoelastic recovery provides hope that allografts may have further potential for improvement. Longer‐term studies of MCL allograft mechanical behaviors a

ISSN:0736-0266    

DOI:10.1002/jor.1100080106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractStrain in the anteromedial fibers of the anterior cruciate ligament [ACL(am)] was studied in six cadaver knees. ACL(am) strain was measured in five knees during the application of isometric quadriceps forces alone and simultaneously applied isometric quadriceps and hamstrings forces at 10° increments from 0° to 90° of knee flexion. ACL(am) strain during muscle loading was measured with respect to the ACL(am) strain measured with the knee in its resting position (neutral or near neutral position). A sixth knee was used to investigate the reproducibility of the resting position and quadriceps‐induced ACL(am) strains. The strains induced in the ACL(am) by the quadriceps were significantly greater than 0 at knee flexion angles from 0 to 40° and not significantly different from 0 for 50 to 90° The ACL(am) strains induced by simultaneously applied hamstrings and quadriceps forces were not significantly different from 0 at any of the knee flexion angles tested. Simultaneously applied hamstrings and quadriceps forces significantly reduced ACL(am) strain at 10, 20, and 90° of knee flexion compared to the ACL(am) strain induced by quadriceps forces alone. The hamstrings are potentially capable of both significantly reducing and negating quadriceps‐induced ACL(am) strain at 10 and 20° of kn

ISSN:0736-0266    

DOI:10.1002/jor.1100080107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThis study measured the vertical displacement of three kinds of cementless tibial components [Porous Coated Anatomical (PCA), Tricon, and Whiteside], under eccentric loading up to 2,225 N. Displacement between the tibial tray and the proximal tibia was measured with linear variable differential transformers at the anterior and posterior side when anteriorly or posteriorly loaded, and at the medial and lateral side when medially or laterally loaded. The general pattern of motion was sinking at the loaded side and lift‐off at the opposite side and lift‐off at the opposite side. Lift‐off opposite the loaded side was fairly small for all components at all measurement sites. Among the three components, the Whiteside showed the smallest displacements. The Tricon (when anteriorly or posteriorly loaded), and the PCA (when medially or laterally loaded) showed sinking at the loaded side. Anterior screw fixation of the PCA was not effective in preventing anterior lift‐off. The tilting motion of the tibial components obseved in this study implies instability of the initial fixation, which could possibly compromise bony ingrowth. Furthermore, this tilting could cause uneven distribution of load, and potentially result in fracture of the underlyi

ISSN:0736-0266    

DOI:10.1002/jor.1100080108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe effect of metallic chelating agents (EDTA, EGTA) on cartilage metabolism was studied both in vitro, on calf cartilage, and in vivo, in rabbits. The question asked was whether it was possible to affect neutral protease activity, and not also inhibit beneficial synthetic systems. In vitro, EDTA suppressed anabolic processes, while EGTA had no effect. However, EDTA in vivo did not suppress glycosaminoglycan or RNA production, but paradoxically stimulated them. At the same time, EDTA inhibited neutral protease activity in normal animals.

ISSN:0736-0266    

DOI:10.1002/jor.1100080109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractWe have examined extracts of articular cartilage from rabbits aged 3–100 weeks for evidence of age‐related changes in the structure and content of link protein (LP) in this tissue, with the following findings: (a) Two major molecular weight forms of LP were seen on SDS–PAGE (41 and 48 kDa) and the proportion of these changed markedly with age. The 48 kDa species was predominant in young animals (representing about 78% of the total LP at 5 weeks) whereas the 41 kDa species increased in amount with age (representing 35% of the total LP at 100 weeks). A minor form of about 43 kDa, representing less than 20% of the total, was present only during the growth phase. A small amount of fragmented link protein (less than 5% of the total) of about 25–30 kDa was present in samples from mature and aged rabbits only. (b) The quantitation of LP in guanidinium: HCl extracts of cartilage, by radioimmunoassay with monoclonal antibody 8‐A‐4, was markedly influenced by the conditions of preparation and pretreatment of samples. Assays of dialyzed guanidine extracts following treatment at 80°C for 15 min in 0.025% (w/v) SDS indicated that immature and mature cartilage contains about 50 and 180 μg of LP/g of tissue, respectively. On the other hand, assays following treatment at 100°C for 20 min in 0.1% (w/v) SDS suggested that rabbit cartilage contains about 300 μg of LP/g of tissue at all ages; finally, assay of CsCl purified proteoglycan samples under these conditions indicated a content of about 500 μg of LP/g at all ages. (c) Calculations based on the analysis of proteoglycan preparations for aggregating monomer and link protein suggest that a LP:aggregating monomer molar ratio of about 0.9 is maintained in the articular cartilage throughout maturation and agi

ISSN:0736-0266    

DOI:10.1002/jor.1100080110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe objective of this study was to investigate the effects of mechanical fatigue in the form of cyclic shear strain on articular cartilage. Three millimeter diameter full‐thickness plugs were cored from the lateral aspect of bovine tibial plateaus. Sinusoidal shear strains of ±5, ±10, and ±15% were applied to the specimens at 100 Hz for 3 h (a total of 108 ±X 104cycles). The mechanical shear properties of the tissue (loss and storage moduli) were determined as a function of the number of applied strain cycles. A rapid, irreversible decrease of approximately 35% of initial modulus was found to occur in both loss and storage modulus during application of the first 90,000 cycles. Further decay in the moduli was found to occur from 90 ±X 103to 108 ±X 104cycles, but was of considerably smaller magnitude than the initial decrease. The moduli remained relatively constant beyond application of 108 ±X 104cycles. No consistent change in proteoglycan content was found to be associated with the fatigue process when comparing tested specimens with fresh untested tissue, and with experimental controls. In addition, no structural defects in the mechanically altered tissue were revealed by scanning electron mi

ISSN:0736-0266    

DOI:10.1002/jor.1100080111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY