bluuebunny/crossref_metadata_2025 huggingface dataset:
Fluorometric determination of DNA in cartilage of various species
Authors: Oegema Theodore R. , Carpenter Barbara J. , Thompson Roby C.
Published: February 2005

A sensitive, modified 3,5‐diaminobenzoic acid (DABA), fluorometric DNA assay was developed and compared to mithramycin and ethidium bromide assays in determining the DNA content of dense connective tissues including: Swarm rat chondrosarcoma, rabbit, dog, monkey, and most importantly, adult human articular cartilage. In the more cellular cartilages, the three methods gave equivalent results. However, in the relatively acellular human cartilage, the DABA method was shown to be superior. Both the mithramycin and ethidium bromide gave falsely high values compared to the DABA method, which by subtraction after DNase digestion approached the DABA value. The latter was completely DNase sensitive. With the DABA method, the DNA content of human cartilage can be obtained on less than 5 mg wet weight of fresh, alcohol‐fixed, or lyophilized material. While the DNA can also be released by digestion with papain or protease from Streptomyces griseus, proteinase K was preferable. The comparison of literature values for other fluorometric and spectrophotometric assays of human cartilage suggest these methods overestimate human articular cartilage DNA concentrations, whereas the DABA values were in line with those predicted from previous morphometric analysis. Thus, the modified method represents an improvement in DNA analysis of dense connective tissues.
Development of a variable stiffness external fixation system for stabilization of segmental defects of the tibia
Authors: Tencer A. F. , Claudi B. , Pearce S. , Bucholz R. W. , Johnson K. D.
Published: February 2005

The mechanical properties of a variable stiffness external fixation system were explored. Initial testing of a unilateral fixator configuration demonstrated that system rigidity could be increased by maximizing pin separation distance in the fracture component and the number of pins used while minimizing pin separation distance across the fracture site and the sidebar offset distance from bone. A triangulated system composed of half pin frames mounted anteriorly and medially on the tibial aspects and linked by crossbars was devised. Progressive disassembly of the frame was shown to result in progressive decreases in fixator rigidity in all planes.
Force ratios in the quadriceps tendon and ligamentum patellae
Authors: Huberti H. H. , Hayes W. C. , Stone J. L. , Shybut G. T.
Published: February 2005

We measured forces in the quadriceps tendon and ligamentum patellae in six human cadaver knee joints loaded through a range of flexion angles from 30 to 120°. Using standardized loads based on one‐sixth of maximum isometric quadriceps moments reported in human volunteers, we measured maximum average forces at 60° flexion of 532 N in the quadriceps tendon (FQ) and 470 N in the ligamentum patellae (FL). Linear extrapolation to full maximum extensor moments results in estimates of 3,200 N for FQ and 2,800 N for FL. The force ration (FL/FQ) reached a maximum value of 1.27 at 30° and minimums of 0.7 at 90 and 120° knee flexion. Contrary to prevailing opinion, our results indicate that the patella is not a simple pulley that serves only to change the direction of equal forces in the quadriceps tendon and ligamentum patellae. Instead, the ratio of forces in these structures varies significantly with flexion angle. The ratio appears to be determined by the changing location of the patellofemoral contact area relative to the insertions of the tendon and ligament. These findings emphasize the biomechanical importance of patellar length and of the vertical dimensions and locations of the patellofemoral contact area. Attempts at surgical intervention for the treatment of disorders of the extensor apparatus should recognize these variations. Procedures that tend to move the contact area more proximally (at a particular flexion angle) will also tend to decrease the FL/FQ ratio.
Metal/cement interface strength in cemented stem fixation
Authors: Ahmed A. M. , Raab S. , Miller J. E.
Published: February 2005

To characterize the strength of the interface between stem‐type metal implants and bone cements, a fracture mechanics parameter was used. This parameter, the critical strain energy release rate (Gc), was determined from “push‐out” tests of cylindrical specimens. The specimens, formed using molds of bone, were maintained and tested at body temperature. The strength of interfaces formed with cancellous bone surrounding the cement mantle was significantly less than the strength of those formed in apposition to cortical bone. A marked degradation of strength was found with saline immersion for SS316LVM/cement interfaces formed with Zimmer regular, Simplex‐P, and Zimmer LVC cements. After 60 days of immersion the interface Gc was only 10–20% of the value for bulk cement. Interfaces formed with thin‐film polymethylmetharcrylate‐precoated metals (SS316LVM, Co‐Cr‐Mo, and Ti‐6A1‐4V) yielded “dry” Gc values one order of magnitude greater than those measured with interfaces formed with uncoated metals. Moreover, the strength of precoated SS316LVM/cement interfaces formed with all three brands of cement did not change after saline immersion for 60 days.
Ultrastructure of sensory nerve endings in monkey (Macaca fascicularis) knee joint capsule
Authors: Halata Zdenek , Badalamente Marie A. , Dee Roger , Propper Michael
Published: February 2005

Ultrastructural studies of sensory endings in monkey posterior medial knee joint capsule were undertaken. Three distinct sensory nerve endings have been identified: free nerve endings, Ruffini corpuscles, and Pacinian corpuscles. The free nerve endings are present in all layers of the joint capsule excluding the synovium. Two types of Ruffini corpuscles have been found in the fibrous layer. The first type is characterized by a thin perineurial capsule, the second type by a thicker perineurial capsule, and extensive intracapsular space. Both types of Ruffini corpuscles are innervated by approximately one to four myelinated axons which lose their sheaths as they course through the corpuscle. They terminate on collagen fiber bundles as distinct swellings with spiny membrane projections that are covered by a thin basal lamina. These terminals contain abundant mitochondria, agranular vesicles, and irregularly arranged neurofilaments and neurotubules. Two types of Pacinian corpuscles were occasionally observed. The first was a small, typically laminated structure with an inner core at the layer between the synovium and the fibrous layer and between the fibrous layer and muscle/ligament; larger Vater‐Pacinian corpuscles were noted only at the boundary between the fibrous layer and the muscle/ligament layer.
Characterization of growth plate mitochondria
Authors: Stambough J. L. , Brighton C. T. , Iannotti J. P. , Storey B. T.
Published: February 2005

The growth plate chondrocyte plays a central role in growth plate function. The purpose of this study was to characterize the respiratory and calcium transport properties of isolated mammalian growth plate chondrocytes and mitochondria obtained from these cells and to quantitate the mitochondrial weight and volume fraction in each zone of the growth plate. A new method was developed for isolation of mitochondria from chondrocyte suspensions. Isolated chondrocyte mitochondria demonstrated an eightfold increase in oxygen consumption in response to calcium and a two‐ to threefold increase in oxygen consumption in response to adenosine diphosphate. Similar responses were observed in chondrocytes treated with digitonin. The mitochondrial protein content of the growth plate and hyaline cartilage chondrocytes is significantly less than hepatocytes. Conversely, the chondrocyte mitochondrial cytochrome aa3 content is similar to mitochondria from a wide variety of sources. A zonal analysis of the growth plate demonstrates an increase in the mitochondrial weight (protein) fraction from the reserve to the hypertrophic zone whereas the mitochondrial volume fraction decreases from the reserve to the hypertrophic zone. The findings of this study emphasize the dependence of chondrocytes on glycolysis as a prime energy source and support the concept that chondrocyte mitochondria have become specialized in the process of matrix calcification.
Quantification of regional blood flow to canine flexor tendons
Authors: Weidman Kevin A. , Simonet William T. , Wood Michael B. , Cooney William P. , Ilstrup Duane M.
Published: February 2005

Although the blood supply and the microcirculation of flexor tendons have been studied and defined extensively using qualitative methods, the quantitative assessment of blood flow has been lacking because of the limitations of the available experimental techniques. We studied the regional blood supply to the flexor tendons of dogs by the technique of radionuclide‐labeled microspheres. Seven adult mongrel dogs were used. Microsphere injection and tissue‐counting techniques previously used for other tissues were applied. Samples of proximal, isthmus, and distal portions of the profundus and superficialis flexor tendons were harvested from each digital unit of available limbs from each dog. Mean (± SE) flows (ml/100 g dry tissue/min) were proximal profundus 1.78 ± 0.60 and superficialis 7.10 ± 1.50. The differences were significant (p < 0.01). The study suggests that regional variation in blood flow to canine digital flexor tendons exists, so that a single value for blood flow to these tendons is not relevant. Furthermore, the study supports the concept of dual (vascular and synovial) nutrition to the digital flexor tendons in dogs. These observations may have implications regarding tendon repair techniques.
Clinical utility of the erythrocyte sedimentation rate in preoperative evaluation of solitary skeletal lesions
Authors: Simon Michael A. , Schaaf H. William , Metz Charles E.
Published: February 2005

We investigated the utility of the erythrocyte sedimentation rate in planning the diagnostic and surgical strategy for patients who were found by conventional radiography to have a solitary skeletal lesion. A series of 101 patients was separated into two groups according to their ultimate diagnoses. Group I included patients with skeletal metastases of unknown origin, unusual bone infections, and marrow cell tumors. Group II included benign and malignant primary bone tumors. Using the Westergren method to determine the erythrocyte sedimentation rate prior to biopsy, we found that only one of 65 Group II patients had a rate above 30 mm/h whereas 22 of 36 Group I patients had rates greater than 60 mm/h. By using Receiver Operating Characteristic analysis, we estimated the trade‐offs between sensitivity and specificity that can be achieved with various threshold sedimentation rates. In particular, we found that a critical erythrocyte sedimentation rate of 30 mm/h allows separation of Group II patients from Group I patients with 96.9% sensitivity and 82.6% specificity. Our results indicate that the erythrocyte sedimentation rate can be used effectively in conjunction with conventional radiography in the planning of an appropriate further diagnostic strategy.
Bone density in women: A modified procedure for measurement of distal radial density
Authors: Awbrey B. J. , Jacobson P. C. , Grubb S. A. , McCartney W. H. , Vincent L. M. , Talmage R. V.
Published: February 2005

This is a cross‐sectional study of bone densitometry in >700 normal healthy white women ranging in age from 18 to 98 years. A modified procedure for single–photon bone density analysis of the distal radius is described and compared with dual‐photon densitometric measurements of the second through fourth lumbar vertebrae. The distal radial site measured was separated from the ulna by 5 mm. This “5 mm” site was characterized according to trabecular and cortical bone content, measurement reproducibility, positioning precision, and the effects of wrist pronation or supination. The radial site demonstrated a bone density loss of <0.1%/year for normal women 25–50 years of age, increasing to 0.7%/year after 50 years of age. In contrast to the variability and inconsistency obtained by us and others utilizing the standard “9/10” site, bone loss with age at the new “5 mm” site correlated closely with generalized bone mineral loss of the axial skeleton. We suggest that there is a unique role for single‐beam densitometric measurements of the radius, permitting the rapid and relatively inexpensive evaluation of large populations of women without requiring a visit to a medical center. Such a process can select those requiring further evaluation or medical attention.
Effect of antigen‐induced synovitis on the extensor tendons within the retinacular compartment of the dog
Authors: Manske Paul R. , Lesker Peggy A.
Published: February 2005

Antigen‐induced proliferative synovitis was produced within the extensor retinacular compartment of one forepaw of young littermate dogs. The extensor tendons within the synovitis compartment were compared with the tendons in control compartments of the opposite forepaw. At 7 days following challenge, the tendons from the proliferative synovitis compartment showed increased uptake of [3H]proline at 5 min after pulse labeling. At 7, 14, and 28 days following challenge, the tendons within the proliferative synovitis compartment showed a significant increase in metabolic activity compared with control tendons after radioactive labeling for 6 h, with no associated difference in total collagen content of the control and synovitis tendons. These results indicate an increase in protein synthesis and degradation by the synovitis‐surrounded tendons.
Increased collagenolytic activity in severed and sutured tendons following topical application of exogenous collagen in chickens
Authors: Porat S. , Nyska M. , Sofer B. , Shoshan S.
Published: February 2005

To verify the role of collagenase in reduction of peritendinous adhesion by topical application of exogenous collagen, the flexor tendons of 30 chickens were severed and sutured. Exogenous, native enriched collagen solution (ECS) was introduced in the tendon sheath via a polyethylene catheter. The effect of ECS on collagenolytic activity in the healing tendon was assessed 1, 2, and 3 weeks later both by determining the relative amounts of dialyzable protein and hydroxyproline and by using the collagen film collagenase assay. The results obtained indicated a significant increase in both dialyzable hydroxyproline level and collagenolytic activity in the ECS‐treated tendons as compared with the untreated controls. It is suggested that the effect of the topically applied exogenous collagen on increasing the collagenolytic activity may be directly related to previously observed increased gliding capacity of the tendons in the same experimental model.
Swelling of articular cartilage and other connective tissues: Electromechanochemical forces
Authors: Eisenberg Solomon R. , Grodzinsky Alan J.
Published: February 2005

We have measured the relationship between tissue swelling stress and consolidation for bovine articular cartilage and corneal stroma in uniaxial confined compression as a function of bath ionic strength. Our experimental protocol and results clearly demonstrate that two concentration‐dependent material properties are necessary to describe the chemical dependence of tissue swelling stress in uniaxial compression over the range of deformations and concentrations explored. A general electromechanochemical model for the swelling stress of charged connective tissues is developed. The model focuses on the role of charged matrix macromolecules in determining the mechanical behavior of the tissue. A constitutive relation for the swelling stress in uniaxial confined compression in formulated and the concentration dependence of the material properties of articular cartilage and corneal stroma is determined. The associated free swelling behavior of cartilage and cornea specimens is computed from these results and is found to compare favorably with data from the literature.
Degradative enzyme systems in osteoarthritic cartilage
Authors: Ehrlich Michael G.
Published: February 2005

In osteoarthritis, despite increased matrix synthesis, there is a reduction of both major matrix components, proteoglycan and collagen. This study suggests that this is the result of enhanced degradative activity intrinsic to the cartilage. Because osteoarthritis is a focal disease, histologic controls were used to measure the severity in different areas of the cartilage and in different specimens. Neutral proteoglycanase and collagenase were both described in human cartilage, and their levels matched the severity of the disease as did acid phosphatase, a marker of lysosomal enzyme. Articular cartilage collagenase has an inhibitor in the cartilage and has negligible activity in normal cartilage. This was found not to be a lysosomal enzyme. A model of osteoarthritis was studied and found to have the same biochemical pattern as human disease. Using this method, inhibitors of degradative enzymes were used as a treatment. The chelator of metallic cations EDTA was found to have a significant effect on reduction of degradative enzyme activity and altered the arthritic process.
Quantitative studies of the flexion‐relaxation phenomenon in the back muscles
Authors: Schultz Albert B. , Haderspeck‐Grib Karol , Sinkora Glenda , Warwick David N.
Published: February 2005

In quiet standing positions involving substantial trunk flexion, myoelectric activity in the back muscles diminishes to low levels. Aspects of that “flexion‐relaxation” phenomenon were explored through measurements of myoelectric activities in 11 young men during performance of 19 isometric tasks in flexed positions. Biomechanical model analyses were used to predict the internal loads imposed on the lumbar trunk structures during those performances. Flexion‐relaxation consistently occurred in quiet flexed standing, but marked increases in myoelectric activity were found on imposition of external loads in flexed positions. Increases in myoelectric activity per unit increase in back muscle contraction force increase were nearly the same as those found in upright postures. Whether or not flexion‐relaxation occurs, large trunk flexions load the spine heavily.
Age‐related changes in articular cartilage proteoglycans: Electron microscopic studies
Authors: Buckwalter Joseph A. , Kuettner Klaus E. , Thonar Eugene J‐M.
Published: February 2005

Biochemical and biophysical studies have demonstrated that proteoglycan monomers from immature and adult articular cartilage differ in composition and size. To investigate the structural basis of age‐related differences in articular cartilage proteoglycan monomers and aggregates, we isolated and purified high buoyant density proteoglycans from the articular cartilages of 2‐ to 3‐month‐old calves and 18‐month‐old steers. The molecular architecture and dimensions of the proteoglycans were examined using the electron microscope monolayer method. Aggregated and nonaggregated monomers from calf cartilage were longer and less variable in length than the corresponding monomers from steer articular cartilage. Calf monomer lengths had unimodal frequency distributions whereas nonaggregated steer monomer lengths had a bimodal distribution. These observations were confirmed by acrylamide‐agarose electrophoresis, which demonstrated that the samples contained only one species of proteoglycan monomer in calf but two species in steer. In addition, calf aggregated monomers had longer thin segments indicating that calf and steer monomers differed in structure as well as in size. Steer proteoglycan aggregates were shorter and had fewer monomers than those from calf. These observations demonstrate the existence of significant age‐related structural differences in articular cartilage proteoglycans and form the basis for future study of the mechanisms responsible for these differences.
Altered orientation of glycosaminoglycans and cellular changes in the tibial cartilage in the first two weeks of experimental canine osteoarthritis
Authors: Dunham Jane , Shackleton D. R. , Nahir A. M. , Billingham M. E. J. , Bitensky Lucille , Chayen J. , Muir I. Helen
Published: February 2005

Changes in the cellularity and in the nature of the matrix were studied in the cartilages of the tibial plateau in experimentally induced arthritis in the dog, 7 and 14 days after section of the anterior cruciate ligament. Samples from the different regions of these cartilages were chilled and sectioned in a cryostat, with a variable microtome chuck to allow precise orientation of the specimens. The samples were examined by normal light microscopy, by microscopic interferometry, and by quantitative polarized light microscopy. The orientation of the glycosaminoglycans was assessed by the new “induced birefringence” method. The results indicated that only the region of the medial tibial cartilage that was unprotected by the meniscus was affected, showing increased water content, loss of superfical cells, and a decrease in orientation of the glycosaminoglycans. Whereas the birefringence of the collagen was markedly increased: this may be a useful indicator of early osteoarthritic changes.
Effects of spinal fusion on the proteoglycans of the canine interverebral disc
Authors: Cole Tak‐Chun , Burkhardt Daniel , Ghosh Peter , Ryan Micheal , Taylor Thomas
Published: February 2005

Posterior lumbar two‐level spinal fusion was undertaken in 10 mature beagles. The animals were sacrificed 6 and 12 months later. Two months before sacrifice control and experimental animals received intravenously Na (1 mCi/Kg). Discs encompassed by the fusion and those adjacent to it were dissected into the nucleus pulposus and annulus fibrosus (AF), which were analysed separately. Proteoglycans (PGs) were extracted with 4.0 M guanidine HCL and purified by CsCL density gradient ultracentrifugation. The hydrodynamic size and ability of the PG subunits to aggregate in the presence of hyaluronic acide were investigated by Sepharose CL‐2B chromatography. The PG subunits were analysed for their galactosamine (galN), glucosamine (glcN), hexuronic acid, and protein content or were subjected to digestion with papain or chondroitin ‐ABC‐lyase to establish the size of the chrondroitin (CS) and keratan (KS) sulphate chains and the KS‐PG core protein complex. Decreased ability to aggregate of PGs isolated from discs 6 and 12 months was generally the same or smaller than those in control tissues, the PG population present after 12 months was larger, particularly in the AF. Analysis of PG subunits from fusion discs afforded galN/glcN, galN/protein, and hexuronic acid/protein rotios that were compatible with the presence in these tissues of PGs in which the proportion of CS attached to core protein was greater than in control tissues. These. These studies provide the first experimental evidence that a metabolic response of discs in a fused segment may be accompanied by the biosynthesis of a new PG population whose structure is similar to that present in immature tissues.
Biomechanical time‐tolerance of fresh cadaveric human spine specimens
Authors: Panjabi Manohar M. , Krag Martin , Summers Donald , Videman Tapio
Published: February 2005

Changes in the biomechanical properties of fresh cadaveric spinal specimens due to long‐term freeze storage and long test periods have been investigated. Fresh cadaveric specimens were divided into three groups: Group A specimens were tested fresh on the 1st day and 13 subsequent days; Group B specimens were tested on the 1st day, frozen in sealed bags at −18°C for 21 days, and tested for 13 consecutive days after thawing; and Group C specimens were frozen for up to 232 days and tested for 14 consecutive days after thawing. We could not find any significant differences between the behavior of the three test groups. This implies that freezing and storage, even for long periods, do not significantly alter the physical properties of cadaveric spinal specimens. Concerning the differences observed on a daily basis, the mean value of the maximum displacement for the 1st day did not differ significantly from the corresponding mean value for the 13 consecutive days. This was true for all three groups, although there was some indication that the fresh group specimens showed greater variation that the two frozen groups.
Comparative study of porous hydroxyapatite and tricalcium phosphate as bone substitute
Authors: Shimazaki Kazuhisa , Mooney Vert
Published: February 2005

This study was performed to quantitate the bone ingrowth and biodegradability of porous calcium phosphate. Two kinds of coralline hydroxyapatite (CHA), along with sintered triculcium phosphate (TCP), were evaluated. All implants had totally interconnecting pores. These pores measured 260–600 μ for CHA‐Goniopora (CHAG), 190–230 μm for CHA‐Porites (CHAP), and 100–300 μm fot TCP. Cylindrical implants (3 mm in diameter by 8 mm in length) were implanted into the diaphyses of rabbit tibias for 3 to 24 weeks. The quantity of regeneration bone, remaining implant, nonmineralized space, and the middle two quarters of the cortical area were measured by a computerized operator‐assisted anaylsis for bone, histomorphometry. At 3 weeks after implantation, 17.3% of CHAG, 11.3% of CHAP, and 7.0% of TCP were infiltrated by regenerated bone. At 24 weeks, 56.1% of CHAG, 52.7% of CHAP, and 44.7% of TCP were occupied by lamellar‐type bone. Implant degradation was noted to be 46.4% for TCP and 27.5% for CHAP. In contrast, CHAG did not show appreciable degradation until 24 weeks.
Fracture healing in the rabbit fibula when subjected to various capacitively coupled electrical fields
Authors: Brighton Carl T. , Hozack William J. , Brager Myles D. , Windsor Russell E. , Pollack Solomon R. , Vreslovic Edward J. , Kotwick John E.
Published: February 2005

The effect of capacitively coupled electrical stimulation on the healing of midshaft transverse osteotomies of the rabbit fibula is assessed roentgenographically, mechanically, and histologically. The results show that a dose‐response curve for capacitive coupling and fracture healing exists and that a 220 mV, 250 μA, 60 kHz applied electrical signal (0.33 V/cm internal electric field) is the most effective signal for fracture stimulation in this model.
Repeatability of phasic muscle activity: Performance of surface and intramuscular wire electrodes in gait analysis
Authors: Kadaba M. P. , Wootten M. E. , Gainey J. , Cochran G. V. B.
Published: February 2005

Repeatability is an important consideration for gait analysis data that are being used as an adjunct to clinical decision making. An index of repeatability of wave forms over a number of identical cycles. The purpose of this study was to use the variance ratio to assess the repeatability of phasic muscle activity recorded with surface and bipolar imtramuscular wire electrodes during gait on 10 normal subjects. Variance ratios were calculated using rectified and smoothed elctromyographic data recorded simultaneously from the two types of electrodes. Three measures of repeatability (reproducibility, reliability, and constancy—defined as the cycle‐to‐cycle, run‐to‐run, and day‐to‐day repeatability of phasic muscle activity) were used to compare the performance of the two electrode techniques. Results show that the reproducibility and reliability were better for surface elctrodes than for intramuscular wire electrodes, and constancy was good for sufrace elctrodes and poor for intramuscular wire electrodes. Repeatability improved with increasing smoothing window lengths but was better for surface electrodes than wire electrodes, irrespective of the smoothing window. This study indicates that surface electrode data represent a more consistent measure of activity of superficial muscles, if comparisons are to be made between gait data from different test days.
Workshop on the bone‐joint implant interface
Authors: Lewis Jack L. , Galante Jorge O.
Published: February 2005

A workshop on the bone‐implant interface, as related to loosening of total joint implants, was held in Chicago on September 14–16, 1983. More than 60 orthopaedic clinicians and researchers and basic connective tissue biologists met to review problems and potential solutions to joint implant loosening. The following is a synopsis of the presentations and discussions.
Bone grafting: Role of histocompatibility in transplantation
Authors: Goldberg Victor M. , Powell Arnold , Shaffer John W. , Zika Jocelyn , Bos Gary D. , Heiple Kingsbury G.
Published: February 2005

The role of histocompatibility matching in bone allografting was studied in two canine bone graft models. In a cancellous ulnar segmental replacement model, frozen bone allografts exchanged between closely matched dogs were significantly better incorporated by radiographic and histologic criteria than were strongly incompatible grafts. Frozen allograts from disparate donors in recipients receiving immunosuppression appeared indistinguishable 6 months later from those in the untreated closely matched groups and from fresh autografts. Fresh vascularized orthotopically placed fibular bone grafts were evaluated by quantitative blood flow assessment, microangiography, and fluorochrome histomorphometry. Revascularized grafts exchanged between untreated closely matched dogs demonstrated preservation of blood flow and a pattern of repair that was delayed by not otherwise different than vascularized autografts. These results suggest that fresh vascularized grafts in the Judiciously matched or immunosuppressed recipient offer attractive clinical possibilities.
Passive movement of radioactive microspheres from bone and soft tissue in an extremity
Authors: Robertson William W. , Janssen Herbert F. , Walker Robert N.
Published: February 2005

Bone biopsy is the definitive method for bone tumor diagnosis. Unfortunately, the procedure is not without risk and may substantially increase the rate and extent of tumor cell metastasis. This study used radioactive microspheres (15 μm diameter) to explore the spread of cell‐sized particles from the distal femur into the lymphatic system, venous drainage, and local tissue following a simulated biopsy in the canine model procedure. In the initial group of test animals the microspheres rapidly moved from the femur through the venous system to the lungs. There was no movement from the femur into the lymphatic system within 4 days. The lungs effectively filtered the 15μm microspheres, thus preventing arterial dissemination. Additional groups were used to explore the movement of the cell‐sized particles from the soft tissue surrounding the bone. At the end of the 4 day experimental period, microspheres were found in the iliac lymph nodes in two of nine animals. Microspheres were not detected in the lungs of any of these nine animals. These results suggest that tumor cell‐sized particles can move rapidly from the bone venous system to the lungs following a bone biopsy. It appears that the lymphatic system does not contribute to this rapid dissemination. However, the role of lymphatics in a more chronic process remains unclear.
Stress analysis of a condylar knee tibial component: Influence of metaphyseal shell properties and cement injection depth
Authors: Cheal Edward J. , Hayes Wilson C. , Lee Chong H. , Snyder Brian D. , Miller Jo
Published: February 2005

We generated three‐dimensional finite element models of the proximal tibia with an implanted tibial component. The component features a cobalt‐chromium tray with four short vertical posts and a porous‐coated surface for improved fixation to polymethylmethacrylate (PMMA). We examined the stresses after varying: (a) the structural rigidity of the metaphyseal cortical shell; (b) the surface area of the cobalt‐chromium tray; and (c) the depth of pressure‐injected PMMA bone cement. Our results indicate that previous finite element models of prosthetic tibial components have overestimated the structural contribution of the metaphyseal cortical shell by a factor of approximately 6. A standard size tray, in contrast to a tray that extends to the cortical shell, does not significantly alter the axial load distribution but could result in bone resorption beyond the tray periphery. An important consequence of the component peg locations is that they direct the compressive stresses into dense regions of trabeculae that run from the subchondral articular surface to the metaphyseal‐diaphyseal junction. The use of a modified von Mises failure criterion suggests that at excessive load levels the most likely location of material failure is at the bone cement–trabecular bone interface immediately distal to the fixation posts. Due to its added rigidity, injection of cement beyond the fixation posts results in slightly increased stresses in this region, but these stress increases are compensated for by an increased strength of the cementbone composite.
Effect of femoral stem length on stress raisers associated with revision hip arthroplasty
Authors: Panjabi Manohar M. , Trumble Thomas , Hult J. Erik , Southwick Wayne O.
Published: February 2005

The objective of this study was to experimentally determine the optimal length of a femoral component in revision total hip arthroplasty (THA). Embalmed cadaveric femurs were loaded in a physiologic manner, and strains on the lateral cortex were measured. Two kinds of defects were tested to simulate THA after removal of a nail plate and after removal of a loose femoral stem. A drill hole was made in the lateral cortex of the femur to simulate the removal of a nail plate. A reaming defect was made, using flexible reamers to thin the cortex from the lesser trochanter distally to a site corresponding to the tip of a standard femoral component, to simulate THA after removal of a previously inserted femoral stem. Femurs were tested intact, with the defects, and after insertion of femoral components with stem lengths of 100 to 250 mm. The strain increased with the creation of a defect and decreased with the insertion of an implant. For a femur with a defect, the strain was minimized when the stem length extended 1.5 femoral diameters past the defect.
Influence of cartilage conformation on its equilibrium water partition
Authors: Torzilli P. A.
Published: February 2005

The spatial and bulk water equilibrium partition and fluid content were determined for normal adult bovine articular cartilage as a function of pH, temperature, and geometric confinement. Water partition averaged 60 ± 7% at neutral pH and 37°C and increased with decreasing pH and increasing temperature without a concomitant change in fluid content. The variation in water partition appeared to be a result of local conformation changes in the collagen fibril ultrastructure causing a transfer between free and trapped water volume. Removal of the lateral and subchondral bone geometric constraints caused an increase in both the water partition and fluid content. However, this partiton variation could be accounted for solely from a change in free fluid volume. These results suggest that in articular cartilage the proteoglycan‐collagen interaction may be an important mechanism for controlling the partition of water between a freely exchangeable space and a space allowing no fluid exchange.
Structural changes in reassembled growth plate aggregates
Authors: Buckwalter Joseph A. , Rosenberg Lawrence
Published: February 2005

To investigate possible structural changes in reassembled proteoglycan aggregates during cartilage mineralization, we examined the molecular architecture and dimensions of growth plate proteoglycan aggregates by electron microscopy. The ends of fetal bovine femurs and tibias were separated into three regions: the epiphysis; the cartilage growth plate, consisting of the proliferative zone and the unmineralized portion of the hypertrophic zone; and the calcified portion of the hypertrophic zone along with part of the metaphysis. Aggregates from all three regions had the same molecular architecture. They consisted of central hyaluronic filaments with multiple attached monomers. Monomers consisted of two segments: (a) a peripheral thick segment, which represents primarily the chondroitin sulfate‐rich region, and (b) a thin segment attached directly to the hyaluronic acid filament. The length of aggregated monomers did not differ between the growth plate cartilage and the metaphysis, nor did the lengths of the thin and thick segments, indicating that the chondroitin sulfate‐rich region of aggregated monomers is not degraded during cartilage mineralization. Between the growth plate cartilage and the metaphysis, aggregates became shorter and had fewer monomers and wider spacing between monomers. These structural alterations in proteoglycan aggregates may be one of the events that prepares the matrix for mineralization.
Prevention of ectopic bone formation by local application of ethane‐1‐hydroxy‐1,1‐diphosphonate (EHDP): An experimental study in rabbits
Authors: Ahrengart L. , Lindgren U.
Published: February 2005

This report shows that ectopic bone formation, a serious problem in orthopedic surgery, can be controlled in an animal model by local application of EHDP (disodium‐ethane‐1‐hydroxy‐1,1‐diphosphonate). The results might be particularly pertinent to the clinical problem of preventing the recurrence of ectopic bone after surgical excision. Male New Zealand white rabbits were treated with immobilization and intermittent passive manipulation of the right knee. The treatment caused bone formation in the quadriceps muscle, which was visible on radiographs after 3 weeks. In this model, the effect of methacrylate implants containing EHDP was studied. A concentration of 16 g EHDP/100 g methacrylate inhibited bone formation in experimental cortical defects. Release of radiolabeled EHDP was studied in an in vitro system. The release of the drug was approximately 20 mg/day and implant initially, decreasing to about 0.1 mg/day/implant after 30 days.

Standardized implants containing 16 g EHDP/100 g were then surgically attached to the femur, and the ectopic bone formation created by immobilization and intermittent manipulation was compared with that in rabbits treated with implants but without EHDP. The ectopic bone was measured from lateral and frontal radiograms and from radiograms of serial transverse sections of the thigh. We found that the EHDP implants were capable of preventing major ectopic bone formation in all cases, whereas all rabbits with an implant containing no EHDP had substantial ectopic bone formation at the end of the experiment. There was no difference between groups in the relative amount of cartilage, connective tissue, and normal bone. We conclude that local administration of EHDP may be a useful method for prevention of ectopic bone formation under the conditions and time employed.
Computerized tomography of proximal femoral trabecular patterns
Authors: Kerr Roger , Resnick Donald , Sartoris David J. , Kursunoglu Sevil , Pineda Carlos , Haghighi Parviz , Greenway Guerdon , Guerra Jose
Published: February 2005

A comprehensive imaging and pathologic investigation utilizing patients and cadaver material was performed in order to identify the normal trabecular pattern of the proximal femur and to assess alterations in this pattern in various disorders. Patients and specimens were studied with computed tomography (CT), including three‐dimensional CT image reconstruction in selected cases and plain film radiography. The CT imaging of the proximal femur provides insight into the dynamic state of bone in this region. Despite limited resolution, three‐dimensional CT image reconstruction is capable of portraying the concentration and orientation of major trabeculae in the proximal femur. Increased trabecular spacing occurs in osteoporosis and is well depicted by CT. Proliferation and thickening of the most superior subchondral primary compressive trabeculae is an early sign of osteoarthritis. In the region of the calcar femorale, crossing trabeculae, similar to the appearance of an enchondroma or bone infarct, have been described in osteoporosis and osteoarthritis and probably represent unmasking of normally present reinforcing trabeculae. In ischemic necrosis, CT should be considered a useful modality for detection of early or mild alterations and may be valuable in treatment planning.
Biomechanical optimization of a model particulate composite for orthopaedic applications
Authors: Gerhart Tobin N. , Hayes Wilson C. , Stern Steven H.
Published: February 2005

Particulate composites are a potential solution to the need for an injectable, biocompatible, resorbable material that could be used to reinforce fractures and defects in bone and temporarily to stabilize porous ingrowth prostheses. We have developed a model system for producing and testing particulate composites to determine if mechanical properties suitable for orthopaedic applications can be achieved. The experiments used bovine cortical bone and various forms of hydroxyapatite for the particulate phase and a collagen and particulate reinforced gelatin‐resorcinol‐formaldehyde (G‐R‐F) adhesive for the matrix phase. Using unconfined compression testing, we measured the effects of variation in particulate type, size, shape, and volume fraction on the material properties of the particulate composites. We found that compressive strengths greater than 10 MPa and compressive moduli greater than 100 MPa could be achieved in this model system. Rough and irregular particulates exhibited higher compressive strengths and moduli than smooth and spherical particulates. Mechanical properties were largely independent of particulate size in the range of 125–850 μm diameter. This model system suggests that, with the development of new biocompatible matrix materials, particulate composites with mechanical properties suitable for orthopaedic applications can be achieved.
Flexor tendon repair
Authors: Gelberman Richard H. , Manske Paul R. , Akeson Wayne H. , Woo Savio L‐Y. , Lundborg Goran , Amiel David
Published: February 2005

Healing canine flexor tendons treated with either total immobilization, delayed protected mobilization, or early protected mobilization was studied by biomechanical, microangiographic, biochemical, and histologic techniques at intervals through 12 weeks. The healing characteristics of the early mobilization tendons showed higher tensile strengths and improved gliding function than the delayed mobilization and immobilization tendons. Protected passive motion brought about accelerated changes in peritendinous vessel density and configuration, as well as increased repair site total DNA content. While adhesions obliterated the space between the tendon surface and the tendon sheath of the immobilized repairs, the mobilized tendons demonstrated coverage of the repair site by cells from the epitenon by 10 days, and a smooth, gliding surface that was maintained free of adhesions through 42 days. A series of in vitro studies demonstrated the cellular processes involved in the repair: phagocytosis of cellular debris and collagenous fragments by cells from the epitenon, and collagen synthesis primarily by endotenon cells.
Three‐dimensional load‐displacement curves due to froces on the cervical spine
Authors: Panjabi Manohar M. , Summers Donald J. , Pelker Richard R. , Videman Tapio , Friedlaender Gary E. , Southwick Wayne O.
Published: February 2005

Load‐displacement curves were measured for six types of pure force loading of the cervical spine specimens obtained from fresh human cadavers. A new measuring and mounting technique was developed that yielded data for all of the functional spinal units for each specimen tested. All five of the coupled, as well as the main, load‐displacement curves were studied. For anterior and posterior shear loadings, the main resulting motions were translation in that direction (1.6 ± 0.3 and 1.9 ± 0.3 mm), and the major coupled motions were flexion and extension (3.6° ± 1.2° and 6.3° ± 1.2°). The main motions with right and left lateral shear loadings were translations laterally (1.4 ± 0.3 and 1.6 ± 0.3 mm), and the major coupled motions were axial rotations (1.5° ± 0.6° and 2.3° ± 0.6°) and not lateral bending. For compression and distraction loadings, the main motions were translations in that direction (0.7 ± 0.3 and 1.1 ± 0.3 mm), and the major coupled motions were flexion and extension (2.0° ± 1.0° and 2.8° ± 1.0°) and lateral bending (1.4° ± 0.3° and 1.9° ± 0.3°). The neutral zones for anterior and posterior shear forces were 1.6 ± 0.2 mm of translation and 5.8° ± 1.3° of rotation, for lateral shear force 1.4 ± 0.3 mm and 2.0° ± 0.5°, and for compression/distraction 0.6 ± 0.1 mm and 2.8° ± 0.9°.
A longitudinal study of the growth of the New Zealand white rabbit: Cumulative and biweekly incremental growth rates for body length, body weight, femoral length, and tibial length
Authors: Masoud Ibrahim , Shapiro Frederic , Kent Ralph , Moses Alan
Published: February 2005

This longitudinal study documents cumulative and incremental growth in the New Zealand white rabbit from 2 to 34 weeks of age at biweekly intervals. Body weight, body length, femoral length, and tibial length have been assessed in 17 male and 12 female rabbits, with the data tabulated separately. A specially designed restrainer was used that allowed the sequential clinical measurements and femoral and tibial radiographs to be performed without the use of anesthesia. Skeletal growth was complete at 28 weeks, with the 34‐week values thus representing mature adult lengths. The mean body weight at 2 weeks of age was 6% that at 34 weeks, and by 16 weeks, 72% of the weight at 34 weeks was achieved. Weight continued to increase in the adult. The mean body length at 2 weeks was 40% that at 34 weeks, and by 16 weeks, 91% of mature adult length was achieved. The mean femoral length at 2 weeks was 38% of the adult length, and at 16 weeks, it reached 95% of adult length. The mean tibial length at 2 weeks was 38% of the adult length, and 94% of the adult value was achieved by 16 weeks. The longitudinal data document the rate and extent of growth of the New Zealand white rabbit, and allow for more accurate timing and quantitation of physical and systemic interventions on the developing skeleton of the commonly investigated New Zealand white rabbit.
Electromyographic studies of the lumbar trunk musculature during the development of axial torques
Authors: Pope M. H. , Andersson G. B. J. , Broman H. , Svensson M. , Zetterberg C.
Published: February 2005

The myoelectric activity of selected trunk muscles at the L3 level was studied during the development of a controlled isometric axial torque. Muscle activity was recorded with surface electrodes bilaterally over the erector spinae muscles, the rectus abdominus, the obliques externus, and the obliques internus. Subjects applied graded isometric axial torque efforts with the addition of a Valsalva. The largest myoelectric activities were recorded over the obliques externus and internus. The side of the muscle developing the torque did show the greatest myoelectric activity, but considerable antagonistic activity was also present. Neither the rectus abdominus nor the internal oblique muscles showed any difference from side to side. The calculated forces in the rectus abdominus and the erectores spinae were high, suggesting that a considerable amount of the muscle contraction was used to control the posture. A Valsalva did not decrease myoelectric activity, but did increase the torque developed.