bluuebunny/crossref_metadata_2025 huggingface dataset:
Treatment of experimental osteomyelitis with antibiotic‐impregnated bone graft substitute
Authors: Cornell C. N. , Tyndall D. , Waller S. , Lane J. M. , Brause B. D.
Published: February 2005

The model of Norden was used to induce osteomyelitis in the left tibia of New Zealand White rabbits. Twenty‐one days following inoculation, the animals had primary debridement and then were randomized into one of three treatment groups. Group I received no additional treatment; in Group II, plain hydroxyapatite beads were packed into the defect; and in Group III, gentamicin crobefat‐loaded hydroxyapatite beads were packed into the defect. The animals were observed for 40 days after the primary debridement and then were killed. The intensity of infection was determined by swab cultures and quantitative bacterial cultures of the debrided material. At primary debridement, all of the animals in each group were equally infected. At the time of secondary debridement, only the animals in Group III had a statistically significant reduction in infection (p < 0.001). In this study, we demonstrated that an antibiotic‐loaded osteoinductive ceramic bead can effectively eliminate bacteria from an osteomyelitic cavity.
Ultrastructural immunolocalization of type‐VI collagen and chondroitin sulphate in ligament
Authors: Bray D. F. , Bray R. C. , Frank C. B.
Published: February 2005

Immunological methods were used to determine the identity of the major components comprising a network of electron‐dense seams (described by the authors in a previous work) within the extracellular matrix of medial collateral ligament (MCL) from humans and rabbits. Tissue obtained from MCL midsubstance was subjected to pre‐embedding labelling with colloidal gold at the electron microscopic level with monoclonal antibodies (MAbs) against type‐VI collagen and chondroitin sulphate (CS), before and after digestion with chondroitinase ABC and testicular hyaluronidase. Tissue labelled with anti‐type‐VI MAbs showed gold conjugates attached to the microfilamentous component of the seams both before and after enzyme digestion, which confirmed the identity of the beaded microfilaments as type‐VI collagen. Treatment of the tissue with anti‐CS MAbs resulted in labelling of undigested tissue only. In these treatments, gold particles were found attached to granules that were interspersed throughout the network of type‐VI microfilaments. Both the granules and gold labels were absent from the network following enzyme digestion. Thin nonbeaded microfilaments that did not label with anti‐type‐VI MAbs also were present within the seams. The loss of these nonbeaded microfilaments following enzyme digestion suggested that they might represent strands of hyaluronan. The codistribution and seqestering of type‐VI collagen and CS within discrete seams or channels suggests that these regions of the MCL midsubstance may contain higher concentrations of water than the surrounding dense fibrillar matrix.
Determination of the in situ loads on the human anterior cruciate ligament
Authors: Takai Shinro , Woo Savio L‐Y. , Livesay Glen A. , Adams Douglas J. , Fu Freddie H.
Published: February 2005

A noncontact, kinematic method was used to determine the lengths and in situ loads borne by portions of the human anterior cruciate ligament (ACL) by the combination of kinematic data from the intact knee and load‐length curves of the isolated ACL. Specimens from knees of cadavers of young people were tested in passive flexion and extension as well as with 100 N of anterior tibial drawer at 0, 30, 45, and 90° of flexion. The results showed that the in situ load on the whole ACL (as much as 129 N) can exceed the magnitude of the applied anterior tibial drawer. The load distribution within the ligament changes with flexion of the knee. The anterior and posterior portions share the anterior drawer force equally toward full extension. However, at flexion >45°, the anterior portion supports 90–95% of the load. This information is important for the determination of the function of the entire ACL and of its subportions in response to external loading of the intact knee. In particular, the preferential loading found for one of the portions of the ACL demonstrates that successful operative reconstruction of this ligament may not be achieved simply by reproduction of its gross anatomy; consideration of the role of the ligament in the overall kinematics of the knee is necessary.
Effect of reconstruction of the anterior cruciate ligament on proprioception of the knee and the heel strike transient
Authors: Co Fred H. , Skinner Harry B. , Cannon W. Dilworth
Published: February 2005

Abnormal proprioception of the knee joint has been documented after rupture of the anterior cruciate ligament (ACL) and may result in the loss of muscular reflexes. Excessive loading from the lack of muscular control may predispose the joint to osteoarthrosis. To investigate this problem, 10 patients were studied at an average of 31.6 months after ACL reconstruction. Three tests of joint proprioception and measurements of the vertical component of heel strike force during normal gait were used. A normal control group also was studied. For two of the proprioception tests (reproduction of passive motion and relative reproduction), there were no statistical differences among the uninjured (control) limbs, the normal contralateral limb of patients with a reconstructed ACL, and the extremity with a reconstructed ACL. In the third test (threshold of detection of motion), which previously has been shown to be adversely affected by ACL injury, the measurements for both extremities of patients with a reconstructed ACL were more accurate than those for the control group. The reconstructed extremity performed less accurately than the contralateral extremity (p < 0.05). The heel strike transient (vertical component of ground reaction force at heel strike) for uninjured and ACL‐reconstructed limbs was not significantly different. In fact, the extremity with the reconstructed ACL had a lower transient than the uninjured extremity. Heel strike transients in patients with a reconstructed ACL were higher than those in the controls, but the differences were significant only when corrected for velocity of gait. These results indicate that a well done ACL reconstruction with appropriate rehabilitation can result in proprioception that is essentially equal to that of the contralateral limb.
Repair of articular cartilage injury following intra‐articular chymopapain‐induced matrix proteoglycan loss
Authors: Williams James M. , Ongchi Dennis R. , Thonar Eugene J‐M. A.
Published: February 2005

The intra‐articular injection of 0.02, 0.2, or 2.0 mg of chymopapain (CP) into the knee of adolescent rabbits caused the loss of more than 50% of the proteoglycans (PGs) in the cartilaginous tissues within the joint. Sequential measurements of cartilage‐derived keratan sulfate epitope in serum and analyses of articular cartilage slices 2 days after the injection revealed that 0.02 mg of CP was nearly as effective as higher doses (0.2 or 2.0 mg of CP) in causing the depletion. The degradation and depletion of PGs in articular cartilage were shown to be localized to the joint and did not affect articular cartilage in the contralateral knee joint (no injection) or other cartilaginous tissues in the body. On day 9, partial replenishment of the articular cartilage PGs had occurred, irrespective of the dose used, and the articular surface within the joint remained intact. However, by day 21, articular cartilage in joints injected with 2.0 mg of CP had begun to show progressive degenerative changes, and these changes became more severe with time. In contrast, joints injected with 0.2 mg of CP continued to repair successfully by the reestablishment of a matrix that retained its integrity and appeared to remain functional for at least 6 months. These results suggest that the model may prove useful for the study of the repair processes that follow matrix injury and severe depletion of PGs from the articular cartilage matrix.
The cartilage end‐plate and intervertebral disc in scoliosis: Calcification and other sequelae
Authors: Roberts S. , Menage J. , Eisenstein S. M.
Published: February 2005

The morphology and composition of the intervertebral disc and also of the cartilage end‐plate were studied in patients with idiopathic or congenital scoliosis. The cartilage end‐plate was investigated because of its function as an epiphyseal plate in humans and the associaition between growth and progression of the scoliotic curve. The proteoglycan and water contents were reduced in both structures in specimens from scoliotic patients, particularly toward the concavity of the curve, compared with autopsy material. The distribution of some collagen types differed in tissue from scoliotic patients and autopsy tissue. Calcification of the cartilage end‐plate, and sometimes of the adjacent disc, occurred in all but three scoliotic patients, whereas there was minimal calcification in the autopsy specimens. We suggest that, although these changes are probably a secondary response to altered loading in the scoliotic patients, they may be highly significant to the progression of the scoliotic curve.
Effects of exercise and polysulfated glycosaminoglycan on repair of articular cartilage defects in the equine carpus
Authors: Todhunter R. J. , Minor R. R. , Wootton J. A. M. , Krook L. , Burton‐Wurster N. , Lust G.
Published: February 2005

Our aim was to determine if mild to moderate postoperative exercise and intra‐articular polysulfated glycosaminoglycan result in improved repair of large, experimentally induced osteochondral defects in a weight‐bearing surface of equine joints. Arthroscopic debridement was used to produce fullthickness defects in a weight‐bearing area of the radial carpal bones in 18 ponies. The ponies were randomly assigned to two groups balanced for age: nine animals in the exercise and nine in the no exercise group. Six ponies in each group were medicated weekly for 5 weeks with an intra‐articular injection of polysulfated glycosaminoglycan in one middle carpal joint beginning at the time of operation. Walking (twice daily) was begun 6 days postoperatively, and by the twelfth week postoperatively the ponies were trotting for 25 min and walking for 15 min twice daily. At the time of the ponies' death, 17 weeks postoperatively, each defect had an average of 50–75% coverage with repair tissue. Exercised, medicated joints had a significantly smaller area of coverage with repair tissue than exercised, nonmedicated joints. Cartilaginous repair tissue from exercised ponies contained significantly more glycosaminoglycan and type‐II collagen (r= 0.53, p < 0.05). The ratio of hydroxylysine to hydroxyproline was significantly lower and the ratio of collagen content to total protein was significantly higher in the repair tissue of medicated joints than in the repair tissue of nonmedicated joints; this is consistent with the presence of less type‐II collagen in the repair tissue in medicated joints. We concluded that postoperative exercise was beneficial and that the immediate postoperative use of intra‐articular polysulfated glycosaminoglycan was detrimental to the development of cartilaginous repair tissue in large osteochondral defects of equine joints.
Knee joint contact pressure decreases after chronic meniscectomy relative to the acutely meniscectomized joint: A mechanical study in the goat
Authors: Bylski‐Austrow D. I. , Malumed J. , Meade T. , Grood E. S.
Published: February 2005

Several studies have shown that meniscectomy causes an immediate, acute increase in knee joint contact pressure and that changes in pressure distribution cause remodeling of bone and soft tissue. Presumably, this remodeling in turn affects contact pressures. This study tested the hypothesis that medial compartment contact pressure increases immediately after medial meniscectomy and then decreases with time. Supporting hypotheses regarding medial compartment contact area and lateral compartment pressures also were tested. Unilateral medial meniscectomy was performed on seven adult goats. Four or 8 months later, contact pressure and area were measured in vitro in the involved joints, as well as in the contralateral joints, before and after removal of the meniscus. The medial compartment pressures of the chronically meniscectomized joints were significantly less than those of the acutely meniscectomized paired joints but remained significantly greater than those of the intact joints. For the 4 and 8 month groups combined, the mean pressures of the acutely and chronically meniscectomized joints were greater than the pressures of the paired intact joints by 70 and 42%, respectively. The mean medial compartment contact areas of the acute and chronic joints were lower than those of the intact joints by 60 and 50%, respectively; mean lateral compartment pressures remained the same. This study indicates that joint remodeling reduces joint contact pressures. It also suggests that the effectiveness of a treatment to reduce pressure concentrations may be determined only by comparison, at the same postoperative time of the pressure with that of the chronically meniscectomized joint, since pressures decreased with time without treatment.
Duration of pain and muscular adaptations in patients with dysfunction of the cervical spine
Authors: Weber Barbara R. , Uhlig Yvonne , Grob Dieter , Dvorák Jiri , Müntener Markus
Published: February 2005

Biopsies of the sternocleidomastoid and omohyoid muscle were taken from 24 patients who underwent arthrodesis for cervical dysfunction of different etiologies. The two muscles, which are involved differently in movements of the head and cervical spine, were investigated histochemically. Muscle fibers were classified as type I, IIA, IIB, or IIC (transitional fibers) according to the pH lability of myofibrillar ATPase and calculated relative distribution. In both muscles, fiber transformations (as evidenced by an increase in the relative amount of type‐IIC fibers) were regularly observed within the first 2 years after the onset of the symptoms. The occurrence of the transformation processes was independent of the patient's age and sex and was the same for the different etiologies. Since the overall fiber composition of the muscles remained essentially unchanged, the fiber transformations must occur alternatingly in both directions (from “slow” to “fast” and the reverse). Muscles of patients with a long case history showed no greater signs of fiber transformation. Therefore, fiber transformations in response to cervical dysfunction occur in the initial stage of the disease and involve different types of muscles. The muscles then return to a “stable” condition, independent of the continuation of the dysfunction and the chronic neck pain.
A method for production and characterization of metal prosthesis wear particles
Authors: Rogers Susan D. , Pearcy Mark J. , Hay Shelley J. , Haynes David R. , Bramley Allan , Howie Donald W.
Published: February 2005

The wear of joint prostheses generates wear particles that produce an inflammatory response in the surrounding tissues and may contribute to bone resorption resulting in prosthetic loosening. Although the effects of particles produced from prosthetic materials have been studied extensively in vitro and in vivo, little attention has been paid to the standardisation of methods for the generation and characterization of these particles. This paper describes a reproducible method for generation of metal particles by the abrasive shaking of joint replacement components. Particular attention was given to the production of metal particles that closely resembled particles found around solid and loose human prostheses. To achieve this, particle size, size distribution, chemical composition, and shape were characterized. Particles that were 0.5–3.0 μm in diameter were isolated by differential sedimentation, and the distribution of particle sizes was determined with use of a Coulter Multisizer. Chemical composition was measured by atomic absorption spectrophotometry, and transmission electron microscopy was used to characterize particle shape. The techniques were shown to be reproducible, since there was little variation between batches over a lengthy time period. These or similar methods of particle production and characterization should be an essential part of future in vitro and in vivo studies of wear particles.
Stress‐Generated potentials in bone: Effects of bone fluid composition and kinetics
Authors: Kowalchuk Roman M. , Pollack Solomon R.
Published: February 2005

It is now generally accepted that stress‐generated potentials (SGPs) at low frequencies are due to an electrokinetic phenomenon in the small interior surfaces of bone and are directly proportional to the zeta potential, a property of the poorly characterized bone surface‐bone fluid interface. We hypothesized that this interface would be labile and might explain the controversy over whether or not the polarity of SGPs can invert under certain conditions. In this paper, the effects of alterations in the steeping fluid on SGPs for 87 samples from 15 animals were examined in four‐point bending for steeping times of ⩽65 h. Calcium and fluoride in distilled‐deionized water and constant ionic strength solutions produced concentration‐dependent inversions in the SGP sign. A new steady state was reached in approximately 18 h. The effects of the fluoride anion (unlike the calcium cation) apparently were reversible. The results strongly suggest that the zeta potential at the labile bone surface‐bone fluid interface can undergo dramatic changes, not only in magnitude but also in sign. The results further suggest that the preparation of bone samples is critical to the understanding of this interface in vivo, and they support the hypothesis that SGPs have a role in bone remodeling.
Effects of parathyroid hormone‐related peptide on chick growth plate chondrocytes
Authors: Loveys Luke S. , Gelb Daniel , Hurwitz Shepard R. , Puzas J. Edward , Rosier Randy N.
Published: February 2005

Parathyroid hormone‐related peptide (PTHrP) and parathyroid hormone (PTH) have similar biological effects in vitro that are mediated through the PTH receptor. PTH receptors have been demonstrated in the zone of provisional calcification and the hypertrophic zone of the cartilaginous growth plate. The current study examined the biological effects of PTHrP on chick growth plate chondrocytes. Chondrocytes were exposed to varying doses of PTHrP for 24 h, and the incorporation of radioactive thymidine into DNA was used as an index of proliferation. A dose‐dependent stimulation of proliferation was seen, with a maximal 27‐fold increase at 50 nM PTHrP. A dose‐dependent stimulatin of cAMP was seen, with a maximal effect at a dose of 50 nM. Proteoglycan synthesis, measured by incorporation of radioactive sulfate, was stimulated, with a maximal effect of 65% at 1 nM. Collagen synthesis and alkaline phosphatase activity from both cellular and matrix vesicle sources decreased in a dose‐dependent fashion, with a maximal inhibition of 50% of the control value. The physiologic significance of the PTH and PTHrP‐responsiveness of growth plate chondrocytes is uncertain at the present time. It is possible that PTH or PTHrP, or both, act as a systemic, developmental modulator of cellular proliferation and differentiation in the growth plate.
Experimental model in vivo for quantitative assessment of bone resorption inhibition
Authors: Pazzaglia Ugo E. , Zatti Giovanni , Nucci Amalia Di , Coci Anna , Cherubino Paolo
Published: February 2005

Quantitative assessment of bone resorption inhibition in vivo is not easily accomplished; methods relying on a count of osteoclasts are questionable, and histomorphometric evaluation of the bone mass presents several technical problems as well. The authors developed a simple method to measure the inhibition of bone resorption by study of the proximal tibial metaphysis of growing rats: the height of the perichondrial bone ring was taken as an index of the balance between osteoblastic and osteoclastic activity because any agent that inhibits osteoclasts (without interference with osteoblasts) produces an increase in the height of this anatomical structure. Since the ring is well demarcated by surrounding tissues, its height can be measured with accuracy and used for quantitative assessment of bone resorption inhibition. This model was tested with salmon calcitonin, and it provides evidence in vivo that this hormone inhibits osteoclastic bone resorption.
Expression of collagens I, II, X, and XI and aggrecan mRNAs by bovine growth plate chondrocytes in situ
Authors: Sandell Linda J. , Sugai James V. , Trippel Stephen B.
Published: February 2005

The cells responsible for skeletal growth are the chondrocytes of the cartilaginous growth plate. These cells differentiate through a series of maturational stages, establishing different zones in the growth plate. Among the major functions of these cells is the production of appropriate extracellular matrix, primarily composed of collagens and proteoglycans. To determine whether matrix synthesis varies with respect to maturational stage and in which cell populations different collagens are expressed, bovine growth plates were analyzed by in situ hybridization ot mRNA and by Northern blot hybridization. The most abundant collagen mRNA in the growth plate was type‐II collagen. This mRNA was present at relatively low levels in the most immature cells of the growth plate but increased several‐fold as cells entered the proliferative stage and remained high through subsequent phases of maturation. Type‐XI collagen mRNA and mRNA for the cartilage‐characteristic proteoglycan, aggrecan, were codistributed with the type‐II collagen mRNA; however, both were present in much smaller quantities. Type‐X procollagen mRNA was localized to chondrocytes late in their maturation and was expressed at levels similar to the expression of type‐II collagen. In situ hybridization of serial sections revealed that growth plate chondrocytes in their more mature stages contain both type‐II and type‐X collagen mRNA. Type‐I collagen mRNA was not observed in growth plate chondrocytes at any maturational stage; rather, it was localized to a morphologically distinct population of cells attached to calcifying cartilage septa in the region of vascular invasion. These data indicate that the genes for major matrix constituents synthesized by the growth plate in some cases are expressed differentially at different stages of cellular maturation and in other cases are expressed coordinately. The pattern of mRNA expression suggests possible mechanisms of gene regulation.
Metabolic activity of bovine articular cartilage during refrigerated storage
Authors: Schachar N. S. , Cucheran D. J. , McGann L. E. , Novak K. A. , Frank C. B.
Published: February 2005

The ability of the chondrocytes in intact bovine articular cartilage (AC) to synthesize glycosaminoglycans (GAG) during short‐term refrigerated storage was examined. Closed and exposed bovine carpometacarpal joints were stored in a refrigerator for 4 hours, 1 day, 3 days, 5 days, or 7 days after the death of the animal. Full‐thickness 6 mm diameter cartilage disks were obtained from each joint, incubated in Na235SO4, digested, and assayed for GAG production. Similarly incubated cartilage samples were processed for autoradiography as a qualitative determination of 35S uptake by chondrocytes. All refrigerated samples of AC showed signs of some cellular metabolic activity. Only at 7 days did chondrocytes demonstrate a significant decline in activity. For all five storage periods, AC from joints exposed to nutrient media synthesized more GAG than cartilage from matched closed joints. These results suggest that some chondrocytes in AC destined for osteoarticular allografting retain the ability to synthesize GAG for as long as 5 days of refrigerated storage and that this synthesis is stimulated by storage of the joint surfaces in a sterile nutrient solution. While the implications of the chondrocytes' survival and metabolism for osteochondral allograft transplantation are unknown, these data indicate that intact bovine AC retains some metabolic activity for several days under the conditions described and would carry on this activity if transplanted within that period of time.
Localisation of bone‐forming cells during fracture healing by osteocalcin immunocytochemistry: An experimental study of the rabbit tibia
Authors: Stafford H. J. , Roberts M. T. , Oni O. O. A. , Hay J. , Gregg P.
Published: February 2005

An immunocytochemical method was used to localise osteocalcin‐producing cells during fracture healing in a rabbit model. In preliminary studies, tibial growth plates from young rabbits were used as a source of new bone formation, in order to determine the optimal tissue preparatory techniques. In the present study, a tibial shaft fracture was created in adult rabbits to study closed fracture healing. An indirect peroxidase method was used to stain paraffin‐embedded tissue sections for osteocalcin. Osteocalcin‐producing cells were positively identified at the periosteal and endosteal surfaces near the fracture site. Osteocalcin staining was not demonstrated in the surrounding soft tissues. At the interface between newly formed bone trabeculae and the cartilage layer within the callus, chondrocytic cells consistently showed localisation of osteocalcin. Within cartilaginous areas of the callus, some chondrocytes showed positive staining for osteocalcin. These cells were often seen in theproximity of blood vessels. The findings suggest that during fracture healing, under certain conditions, chondrocytes are capable of producing osteocalcin and thus could be considered capable of possible transformation into osteoblasts.
In vitro elution of ciprofloxacin from polymethylmethacrylate cement beads
Authors: Dimaio Frank R. , O'Halloran James J. , Quale John M.
Published: February 2005

The use of antibiotic‐impregnated polymethylmethacrylate (PMMA) cement beads for the local delivery of antibiotics in the treatment of chronic osteomyelitis has become a standard orthopaedic practice. The increasing resistance to antibiotics of organisms associated with orthopaedic infections has led to interest in the incorporation of more effective antibiotics into PMMA cement. Ciprofloxacin, a synthetic fluoroquinolone, is potent against a broad spectrum of bacteria associated with osteomyelitis. In this study, strands of ciprofloxacin‐impregnated PMMA cement beads were prepared with 0.2, 0.5, or 1.0 g of ciprofloxacin per 40 g of PMMA. The elution concentration of ciprofloxacin was at least 1–2 mcg/ml for 7 days (0.2 g), 30 days (0.5 g), and 42 days (1.0 g). This concentration is equivalent to the minimum inhibitory concentration for the common pathogens associated with osteomyelitis. Concurrent systemic and local ciprofloxacin therapy appears to be a method for the treatment of chronic osteomyelitis.
Neuropeptides in the human intervertebral disc
Authors: Ashton I. K. , Roberts S. , Jaffray D. C. , Polak J. M. , Eisenstein S. M.
Published: February 2005

The innervation of the human intervertebral disc was investigated by immunochemical methods. Immunoreactivity to the general nerve marker protein gene product (PGP 9.5) was found in the outer annulus fibrosus of 11 of 12 discs removed during anterior arthrodesis for back pain. PGP 9.5‐immunoreactive fibres ran between and across the collagenous lamellae, both in association with blood vessels and distant from them, and extended at least 3 mm into the disc. No innervation was observed in the nucleus pulposus. Fine fibres (< 1 μm in diameter) immunoreactive to calcitonin gene‐related peptide and substance P (neuropeptides located in sensory and possibly nociceptive nerves) were identified in eight and four of the annuli fibrosi, respectively. Nerve fibres immunoreactive to vasoactive intestinal peptide and to the c‐flanking peptide of neuropeptide Y were found in the majority of specimens of annulus fibrosus that were examined.
Adaptation of skeletal muscle in limb lengthening: A light diffraction study on the sarcomere length In situ
Authors: Matano Tetsuro , Tamai Kazuya , Kurokawa Takahide
Published: February 2005

Adaptation of skeletal muscle during limb lengthening was assessed by measurement of the length of sarcomeres in situ. An external fixator was applied to the rabbit radius and ulna to elongate the forelimb by 3.5 mm, while allowing all the joints to be free. At regular intervals after the operation, the extensor digitorum lateralis muscle of the fifth digit was exposed in situ and the length of the sarcomeres was measured by a laser diffraction technique. The sarcomeres, which had stretched to 3.51 μm immediately after elongation of the bone, became shorter with the passage of time. On postoperative day 9, the length was 3.10 μm, which was similar to the length of the unstretched muscle. These results indicated structural adaptation of the muscle to a new length and could explain why the efficiency of muscle function is maintained after limb lengthening. When these findings are combined with our previous results, it appears that stretch‐induced changes in sarcomere length are common in immobilized and nonimmobilized muscles.
Reflex hamstring contraction latency in anterior cruciate ligament deficiency
Authors: Beard David J. , Kyberd Peter J. , O'Connor John J. , Fergusson Colin M. , Dodd Christopher A. F.
Published: February 2005

Decreased dynamic stability of the knee joint associated with functional disability is a feature of anterior cruciate ligament deficiency (ACLD). The purposes of this study were to examine the between‐limbs difference in reflex contraction latency of the hamstring muscles in patients with unilateral ACLD and to investigate its relationship with instability and function. Fifty patients with arthroscopically diagnosed unilateral ACLD were measured bilaterally for reflex hamstring contraction latency (RHCL), and 20 normal volunteers were similarly tested. The subjects were measured in a position of single‐limb full weight‐bearing with the knee flexed 30°. An anteriorly directed shear force was applied to the tibia, and surface electromyographs (EMGs) recorded the activity of the hamstrings in response to the applied force. The latency of contraction was defined as the time from initial tibial movement, identified by accelerometry, to the onset of increased hamstring EMG activity. Both legs were tested and a between‐limbs difference was computed. A significant difference in RHCL wasfound between the limb with ACLD and the control limb. The mean RHCL of the limb with ACLD was nearly double that of the unaffected limb, for a significant mean between‐limbs difference (p < 0.05). The mean between‐limbs difference for the control subjects was not statistically significant. The conclusion is that patients with ACLD have an increased RHCL of the injured leg. As the RHCL is dependent on proprioceptive activity around the joint, it can be used as a measure of proprioceptive ability. The loss of the neurophysiological protective reflex involving the anterior cruciate ligament and hamstrings in patients with ACLD is likely to be a contributory factor in the decreased joint stability experienced by these patients.
Comparison of primate and canine models for bone ingrowth experimentation, with reference to the effect of ovarian function on bone ingrowth potential
Authors: Shaw James A. , Wilson Scott C. , Bruno Anthony , Paul Emmanuel M.
Published: February 2005

Bone growth into porous composite (mesh‐bead) titanium plugs was compared in elderly (postmenopausal) female monkeys and female dogs as a means of validating the cross‐species interpretations so often made between data from research on dogs and human applications. The effect of oophorectomy on bone ingrowth in the canine model was defined by the comparison of data on fractional ingrowth in animals that had had oophorectomy and in control animals that had had a sham operation. No significant difference in bone growth into the experimental plugs was identified between the two animal models, which lends credence to cross‐species interpretation of existing data from dogs. The presence or absence of active ovaries did not affect the ingrowth fraction in the canine model; this suggests that existing data are not confounded by the lack of control of ovarian function. Estrogen depletion does not appear to influence bone ingrowth adversely.
Comparison of absorption of aqueous lidocaine and liposome lidocaine following topical application on rabbit vessels
Authors: Hou Sheng‐Mou , Yu Hsiu‐Ying
Published: February 2005

Liposomes are small particles that encapsulate lidocaine to form topical drug carriers. Forty rabbits were used to compare the absorption of aqueous lidocaine with that of liposome lidocaine after application of each on femoral and iliac vessels. Both agents entered the circulation rapidly. The serum levels of lidocaine were significantly lower and the peaks in concentration appeared later after the use of liposome lidocaine than after the use of aqueous lidocaine. This phenomenon was due to local accumulation of liposome lidocaine and slow release of lidocaine from the liposome. As a topical spasmolytic agent, liposome lidocaine may be superior to the aqueous form due to a lower serum concentration and less total absorption.
Effect of cyclic and static tensile loading on water content and solute diffusion in canine flexor tendons: An in Vitro study
Authors: Hannafin Jo A. , Arnoczky Steven P.
Published: February 2005

This study was designed to determine the effects of various loading conditions (no load and static and cyclic tensile load) on the water content and pattern of nutrient diffusion of canine flexor tendons in vitro. Region D (designated by Okuda et al.) of the flexor digitorum profundus was subjected to a cyclic or static tensile load of 100 g for times ranging from 5 minutes to 24 hours. The results demonstrated a statistically significant loss of water in tendons subjected to both types of load as compared with the controls (no load). This loss appeared to progress with time. However, neither static nor cyclic loading appeared to alter the diffusion of 3H‐glucose into the tendon over a 24‐hour period compared with the controls. These results suggest that any benefit in tendon repair derived from intermittent passive motion is probably not a result of an increase in the diffusion of small nutrients in response to intermittent tensile load.
Identification of integrin receptors on cultured human bone cells
Authors: Saito Taichi , Albelda Steven M. , Brighton Carl T.
Published: February 2005

The interactions of bone cells with their surrounding extracellular microenvironment may be mediated by integrins, a family of heterodimeric glycoproteins consisting of α and β subunits that noncovalently interact to form cell‐substratum adhesion receptors. We previously described the integrins on calvarial bone cells in rats with use of polyclonal antibodies against some integrin subunits. In the present study, we expanded this initial characterization by employing a more complete panel of monoclonal antibodies to identify integrins on human bone cells. Minced fragments of trabecular bone obtained during total knee arthroplasty were grown in culture until bone cells became confluent. The cells then were dissociated, plated again, grown to confluence, and assayed for alkaline phosphatase activity, response of cyclic adenosine monophosphate to stimulation with parathyroid hormone, and osteocalcin content. The percentage of the cells that adhered to various substrates was measured; 60–70% adhered to type‐I collagen, fibronectin, vitronectin, and poly‐D‐lysine; 40–50% adhered to type‐IV collagen, laminin, and gelatin; and only 10% adhered to fibrinogen. Flow cytometric analysis with anti‐integrin monoclonal antibodies and sodium dodecyl sulfate‐polyacryamide gel electrophoresis analysis of immunoprecipitates of the human bone cells revealed high levels of α1β1, α3β1, α5β1, and αVβ5 integrins and much lower levels of α2β1, α4β1, αVβ1, and αVβ3 integrins. This description of the integrin repertoire of cultured human bone cells represents the first step toward an understanding of the role played by integrins in the growth, maintenance, and repair of bone.
Foot inversion‐eversion and knee kinematics during walking
Authors: Lafortune M. A. , Cavanagh P. R. , Sommer H. J. , Kalenak A.
Published: February 2005

The purpose of this study was to monitor selected aspects of the three‐dimensional kinematics of the knee during walking with regular shoes and with modified shoes that induced either pronation or supination of the foot. Steinmann traction pins were inserted into the right tibia and femur of five adult men who had apparently normal lower extremities. Target clusters mounted onto the pins were filmed by four cine cameras operating at 100 frames/sec. Two trials per subject were analyzed for each of the three experimental conditions: regular running shoes, running shoes with a 10° valgus wedge, and running shoes with a 10° varus wedge. The different types of footwear induced only minor kinematic changes at the knee during the stance phase of walking. The angular patterns of the tibiofemoral joint were modified by less than 1°, whereas the translatory patterns were altered by 2 mm. Immediately following foot‐strike, the valgus‐wedge shoes caused the tibia to rotate internally 4° more than the varus‐wedge shoes, but at the tibiofemoral joint no consistent differences in the pattern of internal‐external rotation between normal and modified footwear were measurable. These findings suggest that, in the healthy lower extremity, increased internal and external tibial rotation is resolved at the hip joint, with changes at the tibiofemoral joint that barely are detectable with the techniques used in this study.
Technique for in vivo measurement of the three‐dimensional kinematics and laxity characteristics of the ankle joint complex
Authors: Siegler Sorin , Wang Dinghua , Plasha Elizabeth , Berman Arnold T.
Published: February 2005

We introduce here a technique to measure the three‐dimensional kinematics and laxity characteristics of the ankle joint complex in vivo. The system consists of an optoelectric, kinematic data acquisition system that is used to measure the motion of the ankle joint complex in response to controlled moments applied through a system of pneumatic actuators. As a first step toward development of the method into a quantitative diagnostic tool for injuries of ankle ligaments, we addressed the following questions: (a) What is the reliability for measurement of range of motion and laxity of the ankle joint complex? (b) Are there significant differences in laxity between the left and right joints of a healthy individual? and (c) Are there significant differences in laxity of the ankle joint complex between men and women? To answer these questions, we performed repeated measures of range of motion and laxity of paired ankles in a population of 18 healthy young individuals. The high intraclass correlation coefficients obtained from the statistical analysis indicate that the new experimental system is highly reliable in measurement of total range of motion and total laxity of the ankle joint complex. We further concluded that, within the statistical power available in our experimental design, there are no significant differences in either range of motion or laxity between left and right ankles of healthy individuals or between men and women.
Scanning electron microscopic observations of the vascular structure of vertebral end‐plates in rabbits
Authors: Oki Sadaaki , Matsuda Yoshiro , Itoh Toshio , Shibata Taihoh , Okumura Hideo , Desaki Junzo
Published: February 2005

We used scanning electron microscopy to examine the microcirculation in the vertebral end‐plates of rabbits. The arteriola arborizes and swells at the end‐plate and then coils to make a microvessel loop. This loop is the structure we refer to as a vascular bud. We suggest that these loop structures of the capillaries play a major role in the nutrition of the intervertebral discs.
Centrifugal and biochemical comparison of proteoglycan aggregates from articular cartilage in experimental joint disuse and joint instability
Authors: Müller Francisco J. , Setton Lori A. , Manicourt Daniel H. , Mow Van C. , Howell David S. , Pita Julio C.
Published: February 2005

Two models involving altered joint loading were compared with regard to their effects on the biochemical composition and proteoglycan aggregate structure of articular cartilage. Disuse atrophy was created in greyhound dogs by nonrigid immobilization of the right knee in 90° of flexion, and joint instability was created by transection of the anterior cruciate ligament. Similarities and differences between the two experimental groups at two different time periods were examined to investigate why joint instability induces progressive and irreversible changes to the articular cartilage, whereas joint disuse induces changes that may be reversible when the joint is remobilized. The following studies were performed on the cartilage from all experimental and control groups: (a) compositional analyses to determine water, uronate, and hydroxyproline contents; (b) high performance liquid chromatography for detection of hyaluronan and chondroitin sulfates; and (c) centrifugation analyses of nondissociatively extracted and purified proteoglycans to isolate and quantify the populations of monomers and slow and fast‐sedimenting families of aggregates. In general, all cartilage was found to have a decreased ratio of proteoglycan to collagen after 4 weeks of disuse, and this ratio returned to control values at 8 weeks. In contrast, cartilage had an elevated ratio of proteoglycan to collagen as well as increased hydration at 12 weeks after transection of the anterior cruciate ligament. The most striking contrast between the two models was the finding of an approximately 80% decrease in the content of hyaluronan at both time periods after transection of the anterior cruciate ligament, with no evidence of a change after disuse. The results of centrifugation analyses indicated a significant decrease in the quantity of proteoglycan aggregates in both models. However, this decrease was associated primarily with a loss of slow‐sedimenting aggregates after disuse and a loss of both slow and fast‐sedimenting aggregates after transection of the anterior cruciate ligament. Furthermore, the population of fast‐sedimenting aggregates. The preservation of fast‐sedimenting aggregates as well as hyaluronan after periods of joint disuse but not joint instability suggests a possible mechanism for the reversibility of cartilage changes. Although the proteoglycan aggregates were depleted after disuse atrophy, it is possible that an aggregate‐depleted matrix could recover when normal proteoglycan synthesis is resumed. In contrast, although synthesis may be maintained or elevated after transection of the anterior cruciate ligament, the matrix may not be repopulated with aggregates because there is an insufficient amount of hyaluronan.
Effects of immobilization on achilles tendon healing in a rat model
Authors: Murrell George A. C. , Lilly Edward G. , Goldner Richard D. , Seaber Anthony V. , Best Thomas M.
Published: February 2005

The aim of this study was to evaluate the effects of immobilization and mobilization on the functional and biomechanical recovery of injured Achilles tendons. Male Sprague‐Dawley rats were allocated randomly into four groups: (a) sham operation, (b) division only (surgical transection of the Achilles tendon without immobilization), (c) “dummy” external fixation (division of the Achilles tendon and application of Kirschner wires), and (d) rigid external fixation (division of the Achilles tendon and immobilization with Kirschner wires connected by two triangular frames). All procedures were performed on the right lower limb; the left, uninjured, lower limb served as an internal control. Kirschner wires and external fixators were removed on day 12. Functional performance was determined from measurements of hind pawprints of rats walking preoperatively and on postoperative days 1, 3, 5, 7, 9, 11, 13, and 15. On day 15, the animals were killed and biomechanical evaluations were performed on both the injured and the uninjured Achilles tendon constructs. No functional or mechanical deficits were observed in the sham‐operation group. Animals subjected to division of the Achilles tendon had an initial functional deficit that returned to near normal by day 15. The application of Kirschner wires was associated with an impairment of the functional performance of the rat as well as of the mechanical properties of the tendon‐bone constructs. Immobilization by connection of the Kirschner wires to an external frame had an additional, highly significant (p < 0.001) detrimental effect on the functional and mechanical recovery of Achilles tendon‐calcaneal complexes.
Effect of link protein and free hyaluronic acid binding region on spacing of proteoglycans in aggregates
Authors: Kahn Anthony , Taitz Ari D. , Pottenger Lawrence A. , Alberton Gregory M.
Published: February 2005

Aging of articular cartilage results in accumulation of aggrecan fragments of various sizes that retain their ability to aggregate even though they may have relatively few glycosaminoglycan chains. Residual binding of partially degraded aggrecan may prevent binding of newly synthesized aggrecan subunits that have greater numbers of glycosaminoglycan chains. This study was undertaken to determine the effects of various relative molar ratios of intact aggrecan, link proteins, and hyaluronic acid binding region fragments on the structure of reconstituted aggregates. High molar ratios of link proteins relative to aggrecan decreased the spacing between adjacent aggrecan subunits; low molar ratios of hyaluronic acid binding region relative to aggrecan (4:1 or less) had no significant effect on spacing, and high molar ratios resulted in an increase in the spacing and a decrease in the percentage of aggrecan subunits found in aggregates. These data suggest that the density of aggrecan subunits on the aggregate is determined primarily by steric hindrance of the glycosaminoglycan chains of the aggrecan subunits and that, to a limited extent, partial degradation of aggrecan in an aggregate allows attachment of more aggrecan subunits.
Elastic modulus of calcified cartilage is an order of magnitude less than that of subchondral bone
Authors: Mente P. L. , Lewis J. L.
Published: February 2005

The elastic moduli of calcified cartilage and subchondral bone tissues were measured experimentally with use of a three‐point bending test. Specimens were obtained from a bovine patella and the distal end of a bovine femur, from two different animals. Fifteen specimens were tested as “pure” subchondral bone beams, and 15 were tested as composite calcified cartilage/subchondral bone beams. A least‐squares optimization scheme was used to obtain modulus values from the composite beams. The elastic modulus for subchondral bone calculated from the “pure” subchondral bone beams was 2.3 ± 1.5 GPa (3.9 ± 1.5 GPa for specimens from the femur and 1.6 ± 0.7 GPa for specimens from the patella). The composite beam optimization resulted in a modulus for subchondral bone of 5.7 ± 1.9 GPa and a modulus for calcified cartilage of 0.32 ± 0.25 GPa. The modulus for the calcified cartilage was more than an order of magnitude lower than the modulus of the underlying subchondral bone. This supports the idea that the zone of calcified cartilage forms a transitional zone of intermediate stiffness between the articular cartilage and the subchondral bone.