摘要:

AbstractCo, Cr, and Ni concentrations were determined by electrothermal atomic absorption spectrophotometry in serum and urine specimens collected from a group of 28 patients at intervals of from 1 day to 2.5 years after total knee or hip arthroplasty with porous‐coated prostheses fabricated of Co‐Cr alloy (ASTM F‐75‐82). Two control groups were also tested: (a) 42 healthy adults and (b) 16 orthopaedic patients after total knee or hip arthroplasty with porous‐coated prostheses fabricated predominantly of Ti‐Al‐V alloy (ASTM F‐136‐84). All prostheses contained polyethylene components to avoid metal‐to‐metal contact. Mean Co concentrations in serum and urine were slightly increased in patients with Co‐Cr knee implants at 6–120 weeks after surgery, compared with (a) preoperative values, (b) corresponding values in patients with Co‐Cr hip implants, and (c) corresponding values in control patients with Ti‐Al‐V knee and hip prostheses. Substantially increased Co levels were observed in serum and urine of two patients at 7 weeks and 22 months postarthroplasty, associated with loosening of the prostheses; one of the patients also had elevated Cr levels in serum and urine. Although ASTM F‐75‐82 and F‐136‐84 alloys contain very little Ni (<1.0 and<0.2% Ni, respectively, by wt), mean Ni concentrations in serum and urine were greatly increased at 1–2 days after implantation of Ti‐Al‐V and Co‐Cr prostheses, diminishing by 2 weeks. The postoperative hypernickelemia and nickeluresis may reflect contamination of the operative field with Ni‐containing particles from the drills, cutting jigs, and drilling jigs, or it may represent a previously un

ISSN:0736-0266    

DOI:10.1002/jor.1100070302

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

年代:1989

数据来源: WILEY

摘要:

AbstractA new model was developed to study the histologic and biochemical events during intramedullary bone repair and ingrowth into porous coated implants. Adult chickens were used because of the availability of specific antibody probes. Repair in the metaphysis and diaphysis were compared. Entering through a medial arthrotomy, the distal tibiotarsus was reamed and either impianted with a double‐ended porous coated rod or allowed to heal without implantation of a rod. Specimens analyzed histologically at 7, 14, 21, and 70 days postoperatively revealed direct formation of bone by osteoblasts with no evidence of a cartilaginous phase. At 70 days bony ingrowth was observed deep within the porous surface. Analysis of collagens with sodium dodecyl sulfate polyacrylamide gel electrophoresis demonstrated that the synthesis of type I collagen predominated. Biosynthetic data coupled with quantitative immunologic analyses using antibodies to type II and type X collagen showed that neither of these two collagen types, which are characteristic of cartilage undergoing endochondral ossification, were produced during intramedullary bone repair. These results establish that the adult chicken is capable of bony ingrowth into porous coated implants and that this process is through direct bone deposition by osteoblasts without a cartilaginous intermediat

ISSN:0736-0266    

DOI:10.1002/jor.1100070303

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

年代:1989

数据来源: WILEY

摘要:

AbstractUltracentrifugal polydispersity differential [g(S)] distributions were determined for the proteoglycans of various postmortem human articular cartilage samples extracted from six lateral patellar grooves in nondissociative conditions after mild collagenase digestion of the tissue. The samples consisted of 53 slices (250 μm thick), from normal, mildly fibrillated, and extensively ulcerated knee joints. When statistically analyzed in various subgroupings, the obtained average sedimentation coefficients and polydispersity profiles supported the following conclusions: (a) loss of proteoglycan aggregation and sedimentability is confirmed to be a primary sign of cartilage matrix degradation; (b) higherSvalues for proteoglycans of the high weight (HW)‐bearing areas and lower values for those of the low weight (LW)‐bearing areas were a typical finding in normal cartilage samples; (c) inversion of this pattern was indicative of matrix degradation, suggesting that the HW regions are more affected than the LW‐bearing areas; (d) the averageSvalue distribution across cartilage thickness tended to resemble the corresponding proteoglycan content versus distance from articular surface; and (e) the deepest cartilage layer had, in most cases, the smallest amount of aggregates while the highest average sedimentability was observed at the middle zone of the normal samples. In the discussion, a role of proteoglycan aggregation for providing a means to “pack” more proteoglycans within the collagen meshwork and to control the generation of osmotic pressure gradients is

ISSN:0736-0266    

DOI:10.1002/jor.1100070304

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

年代:1989

数据来源: WILEY

摘要:

AbstractKnees of mature dogs were immobilized for 6 weeks by long‐leg casts allowing 8°–15° of motion, a model studied by others, or with external fixators, a new, more severe model that kept the joints rigid. Some animals were allowed to recover for 1 week after the immobilization period. Articular cartilage was examined histologically and biochemically. After 6 weeks of immobilization, water increased 7% in both casted and fixator‐immobilized joints compared with normal knee cartilage, while hexuronic acid was 23 and 28% lower, respectively. The limited motion permitted by the casts resulted in a smaller depression of proteoglycan synthesis and less proteoglycan loss during immobilization than occurred in the rigid external fixator group. The protective effect of limited motion was shown clearly during the recovery period: as measured by hexuronic acid content. cartilage from the casted joints had almost recovered within 1 week, whereas the external fixator group experienced little or no recovery during the week after treatment. In contrast to previous studies by others with casted joints, both newly synthesized [35S]sulfate‐labeled and accumulated unlabeled proteoglycans from both casted and fixator‐immobilized cartilages were able to form complexes with exogenous hyaluronic acid to the same extent as those from control cartilage. Thus, in immobilized cartilage, failure of the newly synthesized proteoglycan to bind to hyaluronate is not a mechanism of accelerated proteoglycan loss. The accelerated proteoglycan turnover appears to be caused by a combination of decreased synthesis and increased proteolysis of the secreted proteoglycans. Clinically external fixators used to immobilize joint injuries should be applied for the shortest time possible and if possible should be mechanically modified to allow up to 10° of

ISSN:0736-0266    

DOI:10.1002/jor.1100070305

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

年代:1989

数据来源: WILEY

摘要:

AbstractFor osteochondral allograft transplantation to be successful, chondrocytes must survive preservation and retain their capacity to produce normal matrix components: proteoglycans and Type II collagen. Clinical success with osteochondral allograft transplantation has created an increased demand for supplies of suitable cartilage‐bearing grafts. This demand has stimulated attempts to find successful methods for low temperature storage of cartilage for “banking” and heightened interest in cartilage cryobiology. In order to achieve the maximum viability of cryopreserved articular cartilage, previous comprehensive studies have focused on rates and temperatures of freezing, cryoprotective agents, and methods and influences of thawing. This study presents evidence that cryopreserved articular chondrocytes maintain their ability to grow in tissue culture following thawing and to produce normal matrix components. Chondrocytes isolated from Japanese white rabbits were divided into groups of fresh controls and experimental cryopreserved cells. Cells were incubated in dimethylsulfoxide, frozen at a rate of −1°C/min, stored at −79°C, rapidly thawed, and plated for culture, Growth rates were comparable in all groups. In all groups, typical chondroid characteristics were maintained throughout 14 days of culture. Typical cartilage phenotypic characteristics included maintenance of polygonal and rhomboidal cells, cell aggregation, proteoglycan production, and Type II collagen synthesis. This investigation strongly indicates that articular chondrocyte cryopreservation yields viable, functional cells and although these results cannot be directly extrapolated to intact adult articular cartilage, they do give further support for low temperature banking of cartilage‐bearing allografts for tr

ISSN:0736-0266    

DOI:10.1002/jor.1100070306

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe restoration of the biomechanical properties of articular cartilage was studied after 15 weeks of remobilization of the knee joint in beagles previously immobilized with a cast for 11 weeks. The shear moduli were determined with an indentation creep test immediately after load application and at equilibrium at six predefined test points of femoral, tibial, and patellar cartilages. Permeability of the cartilage was estimated from the creep measurements. The values were compared with nontreated, age‐matched (55 weeks) controls and with cartilage collected immediately after immobilization. Remobilization reduced the high creep rates created by immobilization and shifted the depressed equilibrium shear moduli towards those of the controls. However, in the femoral condylar cartilage, the equilibrium shear modulus remained at lower level (p<0.05) and permeability at higher level (p<0.05) as compared with the controls. We conclude that articular cartilage, showing signs of atrophy after long‐term immobilization, was capable of restoring its biomechanical properties during remobilization. This repair was not, however, completed in all parts of the knee joint by the end of the observation per

ISSN:0736-0266    

DOI:10.1002/jor.1100070307

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

年代:1989

数据来源: WILEY

摘要:

AbstractNeurohistologic examination of the spinal cord and cauda equina were compared for 28 beagles undergoing anterior and posterior spinal destabilization procedures—Group I (n = 7), destabilized operative controls; Group II (n = 7), posterolateral bone grafting; Group III (n = 7), Harrington distraction instrumentation and posterolateral fusion; and Group IV (n = 7), Luque rectangular instrumentation and posterolateral fusion. All dogs had appeared neurologically intact upon repeated examinations prior to death. Neurohistological abnormalities (Wallerian degeneration of the dorsal columns, corticospinal tracts, and nerve roots, focal cystic degeneration, and intraspinal central cavitation) occurred in only 1 of the 14 animals (7%) in Groups I and II (noninstrumented) and in 9 of the 14 animals (64%) in Groups III and IV (instrumented). This result is statistically significant (p<0.001). Transient sensory disturbances and radicular paresthesias have been described in clinical reports of spinal instrumentation. It is probable that subclinical neurologic injuries, such as intraspinal and nerve root infarction in posterior neural tissue, can occur with the use of sublaminar hooks or wires. The chondrodystrophic beagle spinal model in this study should be considered a “worst case situation,” and the clinical incidence of neurohistologic changes is expected to be

ISSN:0736-0266    

DOI:10.1002/jor.1100070308

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe goal of this study was to estimate the loads internal to the lumbar trunk that arise during level walking. To do this, (a) trunk muscle activities were calibrated in terms of muscle contraction force levels in a set of isometric exertions; (b) trunk muscle myoelectric activities were measured during level walking; and then (c) the muscle contraction forces that arose during walking were calculated from these measurements and calibrations. Lumbar trunk muscle myoelectric activities were quantified in 10 healthy young males. Myoelectric activities were monitored using eight bipolar surface electrode pairs placed around the trunk at the level of the third lumbar vertebrae. The subjects first performed four static weight‐resisting tasks to calibrate muscle force/activity relationships. They then traversed a 8.25 m walkway three times each at cadences of 72 and 120 steps/min. A biomechanical model incorporating 22 lumbar trunk muscles was used to predict muscle contraction forces for the calibration tasks. Predicted forces were linearly correlated with the measured myoelectric activities for these tasks. The regression equations were then interpolated to estimate the muscle contraction forces from the myoelectric data during gait. Peak contraction forces for the iliocostalis muscles were calculated to be approximately 55 N per side, corresponding to total erector spinae peak contractions on the order of 140 N per side. For the other six muscles that were monitored, contraction forces were less than 15 N per side. This suggests that peak net reaction moments and peak spine compressions on the lumbar trunk during these walking tasks were on the order of 15 Nm and 1.2 times body weight, respectivel

ISSN:0736-0266    

DOI:10.1002/jor.1100070309

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe purpose of this study was to investigate neurophysiologically and anatomically the soft tissues of the dorsal compartment of the lumbar spine in order to understand better their possible role in low back pain. The focus was primarily on the lumbar facet joint and supraspinous ligament of the Sprague–Dawley rat. Microdissection of the dorsal ramus and electrophysiological and neuroanatomical studies of the dorsal ramus and its terminations in paravertebral tissue revealed that (a) there are mechanosensitive, slowly adapting fibers in the rat lumbar facet joint capsule; (b) there are slowly adapting, mechanosensitive units in the rat supraspinous ligaments that respond to tensile loading; both types of mechanosensitive units have high threshold; (c) mechanical stimulation of these tissues sometimes elicits afterdischarges lasting several minutes; (d) many extracellular recordings from the medial branch of the dorsal ramus appear to be reflex activity to mechanical stimulation; (e) silver impregnation of the rat joint capsule reveals individual axons, very few of which were encapsulated, suggesting that they terminate in free nerve endings; and (f) the nerves of the rat facet joint capsule contain 68, 160, and 200 kdalton polypeptide subunits of neurofilament protein (NFP). These results indicate that neurons of lumbar facet joint capsules and ligaments in the back are sensitive to mechanical strain and that the higher threshold neurons may serve a nociceptive (pain) functio

ISSN:0736-0266    

DOI:10.1002/jor.1100070310

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe effect of bending stiffness of external fixators on the early healing of transverse tibial osteotomies was studied in a canine model to determine whether there is a particular range of fixation stiffness where healing is poor. Five unilateral fixators with different stiffnesses were developed and employed along with a dynamic compression plate to fix experimental osteotomies of dog tibias and the contraiateral intact tibias served as controls. The six experimental fixation devices were: plate (P), stainless steel sidebar fixator (SS), stiff aluminum sidebar fixator (SA), intermediate aluminum sidebar fixator (IA), flexible aluminum sidebar fixator (FA), and Delrin sidebar fixator (D). Compared with human tibial fixation methods, the fixators ranged from a rigidity greater than a plate on a human tibia to a flexibility similar to a plaster cast on a human lower leg. Sixty‐four adult male mongrel dogs (29 ± 3 kg) underwent surgery and 52 completed the 9‐week study, leaving 7 to 10 dogs in each experimental group (P = 8, SS = 7, SA = 9, IA = 9, FA = 10, D = 9). After the 9‐week survival period the experimental tibias were radiographed and callus area was digitized. Both the experimental and control tibias were then tested to failure in four‐point bending, and failure moment, stiffness, and energy to failure were determined. Of the 52 osteotomies, only four developed nonunions: 3 of 10 in the FA group and 1 of 7 in the SS group. Using analysis of variance, no statistical differences were detected in failure force, stiffness, or energy to failure as a function of fixator groups. The mean callus area in the most flexible fixation group (D) was significantly greater than that in the P, SS, and I

ISSN:0736-0266    

DOI:10.1002/jor.1100070311

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

年代:1989

数据来源: WILEY