摘要:

AbstractBecause internal and external fixation devices alter blood flow, and thus the transport of nutrients to the cortical bone of a healing fracture, we studied the effects of a fluted intrameduilary rod (IMR), a half‐frame external fixator (EF), and a compression plate (PL) on the cortical bone directly adjacent to the fracture site at 4 and 48 h and 14 and 90 days after fixation. Three specific areas of cortical bone were studied: endosteal cortex, periosteal cortex, and subplate cortex (cortical bone under the compression plate). The fractures fixed with IMR had the lowest blood flow at all time periods studied. At 4 h, the difference between IMR and PL or EF was statistically significant in the endosteal cortex (p<0.01 or p<0.05, respectively); also, the difference between the IMR and EF in the subplate cortical bone region was significant (p<0.05). At 14 days, the blood flow to the endosteal cortex was still significantly lower with IMR than with EF (p<0.025). At 90 days, the blood flow to the subplate region of cortical bone was significantly (p<0.02) higher with PL than with IMR but there was no significant difference in bone remodeling with the different fixation device

ISSN:0736-0266    

DOI:10.1002/jor.1100080402

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe effect of anaesthesia on the rate of bone blood flow in the rabbit was studied. Two estimates of bone blood flow were performed, using 15 μm radioactively labelled microspheres, in three groups of rabbits. The first group was anaesthetised and the interval between the two estimates was 5 min. The second group was also anaesthetised but the interval between estimates was 60 min. The third group of rabbits was conscious and the interval between the two estimates was 4 h. In the first group, small uniform falls in whole bone blood flow were observed (mean change = −5%). In the second group, larger and less predictable reductions were observed (mean change = −24%). In the third group (conscious), little change was observed in whole bone blood flow during the 4‐h experiment (mean change = + 7%). It is concluded that substantial falls can occur in bone blood flow in the rabbit during a 1‐h anaesthetic. If bone blood flow is to be monitored under anaesthesia, then the effect of the anaesthetic on bone blood flow must be accurately defined. In conscious rabbits, estimates of whole bone blood flow performed at an interval of 4 h under control conditions will give reproducable

ISSN:0736-0266    

DOI:10.1002/jor.1100080403

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

年代:1990

数据来源: WILEY

摘要:

AbstractSmall amounts (1–2 ml) of local anesthetics (bupivacaine, lidocaine, and mepivacaine) were injected into the abductor pollicis brevis muscles of 35 monkeys. Control muscles were injected with saline. The muscles were preserved for histology from 4.5 h to 48 days after the injection. Histological damage to muscle fibers was evident from the time of the first sampling. Invasion of damaged muscle fibers by phagocytic cells was prominent by 2–3 days postinjection. At 4 to 5 days, areas of muscle fiber damage were characterized by dense concentrations of phagocytes and mononuclear myoblastic cells. At 6 days, fields of early myotubes were evident. Maturation of myotubes into immature cross‐striated muscle fibers occurred over the next week. Occasional myotubes or immature regenerating muscle fibers were seen as late as 28 days. The topographical pattern of muscle fiber degeneration and regeneration showed a concentration along the surfaces of muscle fascicles or, if intrafascicular, around the presumed site of inje

ISSN:0736-0266    

DOI:10.1002/jor.1100080404

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

年代:1990

数据来源: WILEY

摘要:

AbstractAn electron microscopic study was done on abductor pollicis brevis muscles of 18 Rhesus monkeys after intramuscular injections of 0.75% bupivacaine, 2% mepivacaine, or 2% lidocaine + epinephrine. The muscles were examined for from 2 h to 28 days. Severe muscle fiber damage, consisting of breakdown of sarcolemma and myofibrils, was seen as early as 2 h. Phagocyte‐mediated fragmentation of the degenerating muscle fibers was at its peak during the third and fourth days. Myoblasts were abundant during the fourth day. Early myotubes appeared on the fifth and sixth days, and they matured during the second week. Satellite cells appeared alongside mature myotubes. Overall, the local anesthetic‐induced breakdown and regeneration of skeletal muscle fibers in the monkey followed a course quite similar to that seen in the

ISSN:0736-0266    

DOI:10.1002/jor.1100080405

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe relationship between excessive articular contact pressure, aseptic necrosis, and the long‐term outcome with unilateral congenital dislocation of the hip (CDH) was studied in a series of 84 patients treated by closed reduction and followed for an average of 29.2 years. Contact stress was estimated from archived radiographs taken at the time of maturity and at several follow‐up visits. At a recent review, each patient was rated both clinically for pain and function and radiographically for deformity, degeneration, and aseptic necrosis. For each of 431 films, articular contact stress (force/area) was estimated mathematically, based upon a frontal plane equilibrium (force) analysis and a landmark‐based inference of three‐dimensional head surface (area). Good correlation with final deformity (Spearman ρ = 0.78) was obtained when the hips were ranked in terms of a new cumulative overpressure index P̂, defined as a time‐pressure product involving years of pressure exposure beyond a 2 MPa pressure damage level. An unsatisfactory outcome occurred in 90.4% of the hips experiencing P̂>10 MPa‐years (most of which had aseptic necrosis involvement), whereas the outcome was satisfactory in 80.9% of hips with P

ISSN:0736-0266    

DOI:10.1002/jor.1100080406

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe effect of the maximum unloaded graft length (Lo) and femoral fixation hole location on graft force with the knee under anteriorly directed tibial loads was measured in five fresh cadaver knees with a reconstruction of the anterior cruciate ligament (ACL). The reconstruction was performed using a composite graft consisting of the semitendinosus and gracilis tendons augmented with the Kennedy ligament augmentation device (LAD). Buckle transducers were used to measure ligament and graft forces. The total graft force was adjusted to match the intact ACL at 30° flexion using a force‐setting method so that a standardized reference configuration could be repeatedly obtained. The graft force was highly sensitive to L0, typically changing by 50% with a change in L0of 3 mm. Variation in femoral hole location of 5 mm anterior, posterior, proximal, and distal to the anatomic position produced changes in graft force, particularly at 60° and 90° flexion; however, these changes were not statistically significant. The effect of femoral hole location varied considerably between knees. This variability makes predicting proper hole placement difficult, and suggests the need to adjust each knee at surgery to account for this variable femoral hole position sensiti

ISSN:0736-0266    

DOI:10.1002/jor.1100080407

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

年代:1990

数据来源: WILEY

摘要:

AbstractWe examined three surgical variables that affect the ability of an anteior cruciate ligament replacement to restore the limit of anterior tibial translation. These were the placement site of the substitute on the femur, the initial tension applied to the replacement, and the flexion angle of the knee at the time of tensioning. An anterior load of 100 N was applied to the tibia. As the knee was flexed, we measured the tensile force in the substitute and the anteroposterior position of the femur relative to the tibia. Placement largely determined whether the force in the replacement increased or decreased with flexion. Placement also largely determined whether the tibia moved anteriorly or posteriorly with flexion compared to its position in the intact knee. The initial tension and the flexion angle at tensioning affected the magnitude of force in the substitute and the magnitude of the change in AP position. They did not affect how force and AP position changed with flexion. Greater increases in force and greater posterior shifts in tibial position were produced by changing the flexion angle at tensioning from 0° to 30° than by increasing the initial tension from 22 to 44

ISSN:0736-0266    

DOI:10.1002/jor.1100080408

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

年代:1990

数据来源: WILEY

摘要:

AbstractThere is a need to document the mechanical properties of patellar tendon allografts used for reconstructive surgery of the damaged anterior cruciate ligament, especially the effects of irraidiation sterilization. The purpose of this study was to investigate the influences of in vitro test environment and low‐level cyclic stretching prior to failure tests on nonirradiated and irradiated human graft tissues. Bilateral patellar tendons were split and each half processed accordingly. Some graft tissues were stretched cyclically at 2.5 mm deformation before failure. Experiments were performed in a 37°C saline bath or with tissues moistened with a drip of the same. The irradiated grafts relaxed less and generated less slack length in the drip environment than the nonirradiated controls. Cyclic stretching did not alter failure characteristics of either graft tissue. While no significant differences in the tensile responses or failure characteristics were noted for irradiated and nonirradiated grafts in the drip, in the bath environment the nonirradiated tissues had greater strength and modulus. This resulted in there being a significant difference between irradiated and nonirradiated tissue responses in a heated saline bath environment. These experimental results exemplify the need to control in vitro test environments in the evaluation of various sterilization and preservation protocols for soft tissue allograf

ISSN:0736-0266    

DOI:10.1002/jor.1100080409

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

年代:1990

数据来源: WILEY

摘要:

AbstractAn experimental model for inducing chronic Achilles paratenonitis with tendinosis in the rabbit is presented. Thirteen rabbits were exercised in a kicking machine producing passive flexions and extensions of the ankle joint. Active contractions of the triceps surae muscles were induced by electric stimulation via surface electrodes. The animals were exercised for 5 to 6 weeks, with a rate of 150 flexions and extensions per minute for 2 h, three times a week. Light microscopic examination showed degenerative changes of the tendon, and increased number of capillaries, infiltrates of inflammatory cells, edema, and fibrosis in the paratenon. We conclude that chronic Achilles paratenonitis with tendinosis can be experimentally induced in a standardized manner in rabbits.

ISSN:0736-0266    

DOI:10.1002/jor.1100080410

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe early histological, biochemical, and biomechanical characteristics of the anterior cruciate ligament (ACL) were determined in a rabbit model of acute hemarthrosis. The ACLs of 19 rabbits were given seven consecutive daily knee injections of 2 ml of fresh autologous blood, and then compared to contralateral ACLs from control knees injected with 2 ml of lactated Ringer's solution daily for 7 days. The rabbits were then sacrificed. Synovial proliferation with iron deposition within synoviocytes was observed; however, the architecture of the ACL was maintained. Additionally, the total collagen content, collagenase activity, and biomechanical properties of the ACL were unaltered.

ISSN:0736-0266    

DOI:10.1002/jor.1100080411

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

年代:1990

数据来源: WILEY