bluuebunny/crossref_metadata_2025 huggingface dataset:
Response of cultured bone cells to a capacitively coupled electric field: Inhibition of cAMP response to parathyroid hormone
Authors: Brighton Carl T. , McCluskey William P.
Published: February 2005

Fetal rat calvarial bone cells grown in monolayers were exposed to a capacitively coupled electrical field of 2.62 mV/cm for 2.5–30 min. There was a 59% increase in cAMP concentration after electrical stimulation, compared with a 3615% increase after parathyroid hormone (PTH) adminstration. PTH administration after electrical stimulation resulted in less cAMP synthesis than following either electrical stimulation alone or PTH administration alone. When PTH administration was delayed for 30 min following cessation of the electrical stimulation, there was an inhibition in the cAMP response. This suggests that one possible mechanism of electrically induced osteogenesis is the desensitization of the bone cell to PTH. Since the effect of PTH is to increase bone resorption, desensitizing or blocking the effect of PTH at the bone cell level would result in a net increase in bone formation.
Sustained pressurization of polymethylmethacrylate: A comparison of low‐ and moderate‐ viscosity bone cements
Authors: Bean D. J. , Hollis J. M. , Woo S. L.‐Y , Convery F. R.
Published: February 2005

There is at present great uncertainty relating to the fixation of joint implants. The deficiencies of acrylic bone cement are well documented, but the limitations of cementless fixation are as yet imcompletely identified. The purpose of this study was to investigate the potential of sustained external pressurization to improve the mechanical characteristics of conventional acrylic bone cement. The effect of serially increasing sustained pressurization of two commerically available acrylic bone cements (Simplex‐P and LVC) was evaluated in human cadaver femora. A new method for determination of the shear strength of the bone‐cement interface in place of the traditional pushout tests was used. In this model, there was a significant increase in the bone‐cement interfacial shear strength with increasing pressure, but no difference in the shear strength was found between the two cements. At all pressure levels, the shear strength of the cement was greater than that previously reported. Increased cement penetration into the cortical bone was demonstrated with increasing pressure and low‐viscosity cement, but the extent of cement penetration did not correlate with the shear strength of the bone‐cement interface.
Ligament length relationships in the moving knee
Authors: Sidles John A. , Larson Roger V. , Garbini Joseph L. , Downey Daniel J. , Matsen Frederick A.
Published: February 2005

This article presents an investigation of potential ligament attachment sites for surgical reconstruction of the anterior and posterior cruciate ligaments as well as for the lateral extraarticular iliotibial band tenodesis. Our methodology was based on quantitative measurements of knee anatomy and motion in fresh cadavers, not on biomechanical modeling. Using computer search techniques, we located all the ligament insertion sites that were nearly isometric for motion of the intact knee.
Kinematics of the cervical spine: Effects of multiple total laminectomy and facet wiring
Authors: Goel Vijay K. , Clark Charles R. , Harris Kurt G. , Schulte Kary R.
Published: February 2005

The effect of multiple‐level total laminectomies followed by stabilization on the load‐deformation behavior of the cervical spine is described. Fresh human ligamentous cervical spines (C2‐T2) were potted and clinically relevant load types applied via a loading frame attached to the C‐2 vertebra of the specimen. A set of three infrared light‐emitting diodes (LEDs) were attached rigidly to each of five vertebrae (C3‐7) to record their spatial locations after each load step application, using a Selspot II system. The specimen was tested again after total laminectomy performed on C5. The supraspinous, interspinous, and flavum ligaments between the C4‐5 and C5‐6 motion segments were cut; thereafter, the vertebral arch was removed. The specimen testing was resumed after inducing injury at C‐6 in a similar fashion. The specimen was stabilized, using a facet wiring construct, across the C4‐7 segment before testing for the final time. The load‐deformation data of the injured and stabilized tests were normalized with regard to the corresponding results of the intact test. In flexion‐extension mode, an increase in motion of about 10% after laminectomies was observed. Facet wiring was found to be an effective technique to stabilize injured cervical spines (≈80% reduction in motion, compared with intact spines, was observed).
Treatment of denervation/disuse osteoporosis in the rat with a capacitively coupled electrical signal: Effects on bone formation and bone resorption
Authors: Brighton Carl T. , Tadduni Gregory T. , Goll Stephen R. , Pollack Solomon R.
Published: February 2005

Utilizing a sciatic neurectomy model of disuse osteoporosis, the effects on rates of bone formation and bone resorption were examined when a capacitively coupled electrical signal was applied to the denervated tibia in the rat. It was found that a low‐voltage, symmetrical sine wave, 60‐kHz, capacitively coupled signal had no significant effect on the amount of bone resorption occurring in denervated right tibiae in rats previously labeled with [3H]tetracycline. This was true whether the signal was applied while osteoporosis was developing (prevention of osteoporosis) or after it had been established (treatment of osteoporosis). If a similar capacitively coupled signal was applied to rats in which osteoporosis was well established, and the rats were labeled with [3H]tetracycline daily during a 12‐day treatment period, it was found that there was statistically significant enhancement of the amount of new bone formation (increased [3H]tetracycline incorporation) in the tibiae that received the signal as compared with that of the controls. These results indicate that prevention or amelioration of disuse osteoporosis that occurs with a capacitively coupled electrical signal is due not to a change in the rate of bone resorption, but to an increase in the rate of bone formation.
Effect of direct current on cultured growth cartilage cells in vitro
Authors: Okihana Hiroyuki , Shimomura Yutaka
Published: February 2005

Cultured growth cartilage cells of young rabbits were stimulated by three levels(10, l and 0.l μA) of constant direct current (DC). The effect of DC was examined by measuring the activities of proteoglycan synthesis (uptake of [35S]sodium sulfate and toluidine blue staining) and DNA synthesis (uptake of [3H]thymidine). DC increased syntheses of both proteoglycans and DNA when l μA calculated curren densiy of l μA/cm2 was applied for 3 days. A longer stimulation resulted in a larger difference between stimulated and unstimulted cells. Ten‐microampere stimulation devitalized the cells, while 0.l μA had no effect on cell activities.
Transplacental effects of vitamin A on fetal bones in mice—follow‐up studies on postnatal recovery
Authors: Atkin Isaac , Cohen Irena , Schwartz Z. , Castiglione G. , Ornoy Asher
Published: February 2005

Pregnant mice were injected with pharmacological doses of vitamin A during days 11–19 of gestation with the purpose of studying the long bones of offspring up to the age of 1 week. Tibiae were collected for routine light microscopic examination and tranmission electron microscopic examination. In addition, biochemical studies were conducted to determine the calcium, phosphorus, and magnesium content as well as the hydroxyproline and protein content of the bones. Treatment with vitamin A resulted in reduced weight and length of the long bones, as well as the presence of excessive calcification throughout the hypertrophic zone of the cartilaginous epiphyses. Matrix vesicles, many of them containing hydroxyapatite crystals, were observed and found to be distributed within the cartilaginous epiphyses in a similar pattern as in untreated control mice offspring, but mineral crystals were also observed unassociated with the matrix vesicles. The calcium, phosphate, magnesium, and hydroxyproline content was reduced in the vitamin A offspring. However, the percentage of these minerals expressed per dry weight bone was higher than in controls, verifying the morphological findings that although vitamin A inhibits bone growth, it enhances calcification in the growth plate.
Postural control in single‐limb stance
Authors: Tropp Hans , Odenrick Per
Published: February 2005

Postural control in single‐limb stance has previously been shown to be impaired among soccer players with functional instability (FI) of the ankle joint. The aim of the present study was to further study the role of the ankle in postural control. A dynamic method was used involving optoelectronic movement recordings of body segments and force‐plate recordings of the reaction ground force. Surface electromyography was recorded for the peroneus longus muscle. Thirty physically active men were selected. Fifteen of them had FI of the ankle chosen for recording. The results show that different patterns exist for maintaining equilibrium in single‐limb stance. The ankle has a central role for postural corrections. The position of center of pressure is highly correlated to the position of the ankle and peroneal muscle activity. When the body was in disequilibrium, corrections were made at the hip. It is proposed that a change from an inverted pendulum model to a multisegmental chain model takes place when adjustments at the ankle joint no longer suffice to maintain postural control. The men with FI showed impaired postural control associated with increased upper segmental corrections.
Standardized biomechanical measurement for varus‐valgus stiffness and rotation in normal knees
Authors: Bryant J. T. , Cooke T. D. V.
Published: February 2005

Seventeen female and 24 male subjects had varus and valgus and apparent rotations measured using a standardized mechanical testing device that cyclically applied a 20‐Nm moment in each direction. Five parameters‐apparent varus rotation, apparent valgus rotation, apparent overall rotation, varus stiffness, and valgus stiffness showed intersubject variations approaching 40%. Right‐left variations in the same subject averaged 12%, with no significant right‐left differences overall. Female knees rotated 66% more than male knees and were 35% less stiff. The ratio of apparent valgus rotation to apparent varus rotation averaged 0.775, and the ratio of valgus stiffness to varus stiffness averaged 1.23 for all knees. Stiffness and rotation parameters were highly correlated for both genders in the valgus phase of testing. Results suggest that although magnitudes of measured parameters vary considerably from subject, common relationships between parameters from the same normal knee exist.
Geometry of the first metatarsophalangeal joint
Authors: Yoshioka Yuki , Siu David W. , Cooke T. Derek V. , Bryant J. T. , Wyss Urs
Published: February 2005

This study aimed to define the articular geometry of the metatarsophalangeal (MTP) joint of the great toe. Embedded in resin blocks, five pairs of cadaveric first MTP joints (all from men) were sequentially cut in the sagittal plane with a milling machine, removing 0.5 mm of bone in each cut. The photographed cartilaginous outline of each cut was digitized against reference markers, which enabled a computer system to superimpose each outline in three dimensions. The intersesamoidal ridge was found to be parallel to the lateral shaft. The peak of the ridge was just lateral to the midline of the MT head. The articular outline, through the ridge of each sample, was circular; however, other surface contours were noncircular. The undulating plantar aspect of the MTP head formed by the intersesamoidal ridge and related grooves was found to have symmetric relationships to the sesamoid bones and a consistent orientation to the shaft. The rounded distal dorsal aspect of the MTP head showed consistent differences to the concavity formed by the phalangeal base. The sample size is too small for the sizing of prostheses but it is adequate to study the geometry of the MTP joint. More data are needed for the accurate replication of a resurfacing prosthesis and understanding of joint kinematics.
Geometry of the humeroulnar joint
Authors: Shiba Ryoichi , Sorbie Charles , Siu David W. , Bryant J. Timothy , Cooke T. Derek V. , Wevers Hendrik W.
Published: February 2005

Clinical results with elbow prostheses have been disappointing. A detailed knowledge of elbow joint geometry and mechanics is necessary to improve prosthetic design. In this study, the humeroulnar articulation of four human cadaver elbows was examined using surface analytic methods. In this article, the location of the transverse axis of elbow flexion‐extension is suggested in relation to well‐defined landmarks, the medial and lateral epicondyles, and subsequently to the line connecting their most lateral points—the transepicondylar line. The geometry of the structures responsible for the carrying angle is discussed, as is the extent of cartilage‐covered bearing areas of the lower humerus and upper ulna. Implications pertaining to prosthetic design and surgical technique resulting from this study are discussed.
An electron microscopic study of the changes observed in osteocytes under ischemic conditions
Authors: Usui Yasuo , Kawai Kazuo , Hirohata Kazushi
Published: February 2005

The purpose of this study was to observe the process of ischemia in osteocytes using light and electron microscopy and to compare the changes in these ischemic osteocytes with those in other types of osteocytes (i.e., degenerative osteocytes in physiological states, steroid‐induced lipid‐accumulating osteocytes) that have been previously reported. Five female Japanese white rabbits were used in this study. Osteochondral chips were taken from one side of the femoral condyle, covered with Millipore filters, and then inserted into the other side of the knee joint. These tissues were examined after 12 h and after 2, 5, 8, and 14 days of ischemia under both light and electron microscopy. Under light microscopy, osteocytes and lacunae were classified into four types: normal osteocyte, pyknotic osteocyte, pale osteocyte, and empty osteocyte lacuna. The number of each type of osteocyte (or lacuna) in a settled area was counted. The ratio of normal osteocytes decreased significantly (p < 0.001) after the second day of ischemia. Pyknotic osteocytes increased at 12 h (p < 0.01) and 2 days (p < 0.001) of ischemia. On the fifth day of ischemia, the percentage of pale osteocytes reached a peak. This was followed by a gradual increase in the number of empty lacunae. On the fourteenth day of ischemia, empty lacunac constituted >40% of the cell types. When viewed by electron microscopy, these necrotic osteocytes were similar to the degenerative osteocytes that have been observed in physiological states and apparently different from lipid‐accumulating osteocytes. The results suggested that there could be at least two types of necrotic processes in osteocytes that eventually lead to cell death.
Effects of indomethacin on bone ingrowth
Authors: Keller J. C. , Trancik T. M. , Young F. A. , Mary E. St.
Published: February 2005

The effects of indomethacin, a nonsteriodal antiinflammatory agent, on bone ingrowth were studied using a rabbit animal model and a porous cylindrical implant system. Bone ingrowth was found to be independent of pore size in the range tested (0.6–1.0 mm). In the control (placebo‐treated) group, there was a significant increase in bone ingrowth between the 2‐ and 8‐week groups of animals. However, in the indomethacin‐treated group, there was no increase in bone ingrowth with time.
Growth factor stimulation of adult articular cartilage
Authors: Osborn Keith D. , Trippel Stephen B. , Mankin Henry J.
Published: February 2005

We have examined the effect of peptide growth factors on DNA and proteoglycan synthesis by adult bovine articular cartilage in organ culture. The actions of somatomedin‐C/insulin‐like growth factor I (Sm‐C/IGF‐I), insulin, epidermal growth factor (EGF), and fibroblast growth factor (FGF) from bovine pituitary were investigated individually and in combination. FGF stimulated a 10‐fold increase in tritiated thymidine incorporation while other factors used individually did not influence mitotic activity. Used in concert, insulin with EGF and insulin with FGF acted synergistically in stimulating DNA synthesis 20‐fold and 40‐fold, respectively. All of these growth factors, acting individually, significantly enhanced radiosulfate incorporation. This stimulation was additive for Sm‐C/IGF‐I in combination with EGF or FGF, but not with insulin. These data indicate that adult bovine articular chondrocytes possess the capacity to augment both mitotic and differentiated cell functions in response to growth factors. The data further suggest that, with the exception of insulin and Sm‐C/IGF‐I, which appear to share a common mechanism of action, these factors produce their cellular effects via different receptor or postreceptor pathways.
Mechanical properties of primate vascularized vs. nonvascularized patellar tendon grafts; changes over time
Authors: Butler David L. , Grood Edward S. , Noyes Frank R. , Olmstead Marvin L. , Hohn R. Bruce , Arnoczky Steven P. , Siegel Mark G.
Published: February 2005

Mechanical properties of patellar tendon autografts used to replace the anterior cruciate ligament (ACL) in the cynomolgus monkey were measured at four time periods up to 1 year. The ACL was replaced in each knee with the medial half of the patellar tendon: as a vascularized graft (VG) on one side and as a nonvascularized or free graft (FG) on the other. Postoperative care consisted of 4 weeks of cast immobilization at 30° flexion followed by unrestricted activity in a large cage. Both grafts showed low stiffness and maximum force at 7 weeks (24% and 16% of ACL control values, respectively), increasing to 57% of control ACL stiffness and 39% of control maximum force by 1 year. Corresponding material properties, modulus and maximum stress, also increased over time, but at 1 year were only 34% and 26% of ACL values, respectively. The results indicate that retaining vascularity does not prevent significant reduction in graft properties that occur postoperatively, nor does it accelerate the return in strength and stiffness. Tissue stiffness, which returns earlier than maximum force and joint anteroposterior (AP) force displacement data, should be routinely reported in any healing study. Finally, in studies of this kind, the large variation in the results makes sampling only one or two animals from each time period unreliable.
Nonalcoholic carbonated beverage consumption and bone fractures among women former college athletes
Authors: Wyshak Grace , Frisch Rose E. , Albright Tenley E. , Albright Nile L. , Schiff Isaac , Witschi Jelia
Published: February 2005

We report on data relating to nonalcoholic carbonated beverage consumption and bone fractures in 5,398 college alumnae, 2,622 former college athletes and 2,776 nonathletes, who responded to a detailed mailed questionnaire. A statistically significant association between nonalcoholic carbonated beverage consumption and bone fractures was found only in the former athletes, not the nonathletes. Among the athletes, the age‐adjusted odds ratio (OR) for the association of drinkers (yes/no) with any fracture (yes/no) was 1.35,95% confidence limits (CL) (1.14, 1.59). The dose‐response relationship between the amount of carbonated beverages consumed daily and the number of bone fractures of the athletes was also statistically significant. Results of multiple logistic regression analysis, which included only alumnae ≥50 years of age and which controlled for current exercise and other potential confounding factors, were as follows:(a) for athletes, the OR for the association of drinking nonalcoholic carbonated beverages and a first bone fracture at or after age 40 was 2.28, 95% CL (1.36, 3.84); (b) for all alumnae, a low milk diet was a risk factor for first bone fractures at or after age 40, OR = 1.92, 95% CL (1.15, 3.16); (c) former college athletes had a significantly lower risk of first fractures at or after age 40 than did nonathletes; OR = 0.63, 95% CL (0.40, 0.99). The deleterious effect of nonalcoholic carbonated beverage consumption on the risk of bone fractures has not been reported, as far as we know. These results, if confirmed, may have important public health implications because of the 300% increase in carbonated beverage consumption combined with a decline in milk consumption in the U.S. over the last three decades.
Dynamic changes in the dimensions of the lumbar spinal canal: An experimental study in vitro
Authors: Schönström Nils , Lindahl Sven , Willén Jan , Hansson Tommy
Published: February 2005

The variation in the dimensions of the lumbar spinal canal under both flexion‐extension and axial compression‐distraction was studied using computerized tomography (CT) scans in human cadaver lumbar spine specimens. In 3‐mm‐thick CT slices through the disk at L3‐L4, the cross‐sectional area of the spinal canal was reduced by around 40 mm2, corresponding to a 16% reduction of the initial area when the lumbar spines were moved both from flexion to extension and from distraction to compression. A corresponding reduction in the midsagittal diameter of the canal of 2 mm was found. During these motions, the ligamentum flavum did not appear to be a significant factor for the dynamic changes affecting the dimensions of the canal. This held true even after the disk had been excised in order to produce a total collapse of the disk space.
Blood indices of muscle injury associated with eccentric muscle contractions
Authors: Fridén J. , Sfakianos P. N. , Hargens A. R.
Published: February 2005

Serum muscle enzyme activities of eight healthy men (22–32 years old) were measured before and 48 h after separate bouts of repetitive concentric, eccentric, and isometric contractions of the lower leg anterior compartments. Serum creatine kinase and glutamic oxaloacetic acid transaminase levels were both elevated 2 days after the eccentric exercise regimen, exclusively (36 and 17%, respectively). Lactic dehydrogenase levels were not affected by any of the protocols. Delayed muscle soreness was exclusively reported from the eccentrically exercised limb. We suggest that the high tensions developed during eccentric exercise cause mechanical damage, possibly including sarcolemmal degeneration. Subsequently, muscle enzymes are released to the blood. We conclude that postexercise serum levels of some muscle enzymes, at the time of maximal soreness, are qualitative markers of muscle damage.
Electromyographic study of the anterior cruciate ligament–hamstrings synergy during isometric knee extension
Authors: Grabiner M. D. , Campbell K. R. , Hawthorne D. L. , Hawkins D. A.
Published: February 2005

The purpose of this investigation was to determine the role the hamstrings group may play in augmenting passive articular mechanisms during activity in which anterior drawer force may detrimentally affect the anterior cruciate ligament (ACL). Nine male subjects performed non‐weight‐bearing isometric knee extension at 10% increments of maximum voluntary contraction (MVC). Electromyographic (EMG) signals were detected and recorded from the vastus lateralis, vastus medialis oblique, vastus medialis longus, and the long head of the biceps femoris. The EMG signals were rectified and integrated over 1000 ms and normalized to subject‐specific values. The data were subjected to a repeated‐measures analysis of variance. The results demonstrated that expected significant increases in quadriceps excitation accompanied increases in knee extensor torque. Hamstrings excitation was not found to change significantly (total change = 3.4%). It was concluded that functionally adequate knees do not require posterior drawer force in excess of that provided passively by articular structures.
Limb lengthening by epiphyseal distraction in chondrodystrophic bone: An experimental study in the canine femur
Authors: Fjeld Terje O. , Steen Harald
Published: February 2005

Epiphyseal distraction of the left distal femur was accomplished in 18 chondrodystrophic dogs (age 19–22 weeks). A distraction rate of 0.5 mm/day was applied by means of a unilateral device. Epiphysiolysis occurred after 4 to 9 days. Lengthening was continued for 3 weeks. The animals were killed at 3 (Group 1; n = 5), 19 (Group 2; n = 10), and 71 (Group 3; n = 3) weeks after the end of distraction to verify the magnitude of elongation at removal of the device (Group 1) and at the time of growth cessation (Groups 2 and 3), and to register possible permanent secondary joint changes (Group 3). The average lengthening of 1.2 cm (12.3%) at removal of the device was reduced to 0.7 cm (6.4%) at cessation of growth. The middiaphyseal diameter of the elongated femur was enlarged after the lengthening procedure in all animals. The average torsional strength of the elongated femur compared with the contralateral control was 83% in Group 1, 98% in Group 2, and 107% in Group 3. Degenerative changes were observed in the knee joints of three animals in each group. A two‐way analysis of variance was applied for all data sets to test differences between control and elongated bones and between time periods. The reduction in gained length by retardation of residual growth in the distal femur was significant (p < 0.05). The difference in external diameter between lengthened and control bones was significant in Groups 1 and 3 (p < 0.05). We conclude that early onset of bilateral lengthening by epiphyseal distraction in chondrodystrophic bone required in successive treatment of bone segments may result in significant loss of gained length due to reduction of residual growth. The observed degenerative changes in the knee joint are a sequela that calls into question the use of the method in the femur.
Microscopical investigation of canine anterior cruciate ligament and patellar tendon: Collagen fascicle morphology and architecture
Authors: Yahia L.‐H. , Drouin G.
Published: February 2005

The collagen structure of the canine anterior cruciate ligament (ACL) and patellar tendon (PT) was examined by using light and scanning electron microscopy. The collagen waviness known as a crimping was found to occur in ACL and PT fascicles. This waviness, seen at the periphery of fascicles, is very smooth, and its amplitude seems to decrease from the periphery toward the fascicular center. It appears as a periodic collapse of the fascicle in two dimensions. Two models of the architectural patterns of the ACL and PT wavy fascicles are presented. The constituent collagen fibrils are either parallel or twisted relative to the fascicle axis, giving rise to planar and helical wave patterns, respectively. There is a distinct difference between the ACL and PT collagen structure. The helical wave pattern occurs in both PT and ACL while the planar waveform is found only in the centrally located ACL fascicles. In addition, there is less variability in fascicular size and density over the PT cross‐section than in ACL.
Contact pressures in the patellofemoral joint during impact loading on the human flexed knee
Authors: Haut Roger C.
Published: February 2005

Currently, a bone fracture criterion is used by the automotive industry to assess the potential for a lower extremity injury from impact directed on the flexed knee. However, recent studies with animal models indicate irreversible damage to articular cartilage due to overpressures generated within the patellofemoral (P‐F) joint without bone fracture, and suggest this injury may lead to a progressive, degenerative disease of the joint. The purpose of this investigation was to measure contact pressure in the human P‐F joint during impact loading on the isolated, flexed knee. Loads were delivered on the patella with a free‐flight inertial mass that had a rigid or foam padded interface. The experiments were conducted by serially increasing the impactor velocity in repeated tests until bone fracture was observed. The distribution of maximum pressures generated within the joint was recorded with a pressuresensitive film. Fracture of the patella or the femur occurred at impact loads of approximately 8.5 kN. The average P–F pressure was approximately 25 MPa for 8 kN of impact load on the 90° flexed joint. The P–F contact area varied with the level of contact load and degree of joint flexion. The distribution of P–F pressures was nonuniform. At approximately 70% of the fracture load for the 90° flexed knee, nearly 35% of the contact area was exposed to pressures greater than 25 MPa. In an earlier study by others using subchondral bonecartilage preparations, this level of pressure resulted in fissures and lacerations of the cartilage.
Effect of denervation on limb growth
Authors: Dietze Frederick R.
Published: February 2005

This study used Rana pipiens tadpoles to assess the effect of complete and partial sciatic denervation on tibial bone growth and foot growth. Complete sciatic denervation was performed in R. pipiens at Stages XIV, XVII, and XX and they were killed at Stages XVII, XX, and XXIV. Partial denervation consisted of peroneal or tibial nerve sectioning at Stages XVII and XX with killing at Stages XX and XXIV. Analysis of experimental animals and controls consisted of (a) quantitative axon counts, (b) tibial length, (c) midtibial cross‐sectional area, (d) midtibial cortical thickness, (e) midtibial cartilage anlage cross‐sectional area, (f) foot silhouette area, and (g) osteocyte number and osteocyte density. Both complete and partial denervation resulted in significant effects on bone and foot growth: (a) decreased bone length, (b) decreased cross‐sectional bone area without cortical thinning, (c) increased cartilage anlage cross‐sectional area, and (d) decreased foot size. This experiment demonstrated a trophic effect of nerve on bone growth and development and foot growth. The mechanism of this action is unknown but the data suggests a slowed rate of maturation in denervated bones. The possibility exists that defective peripheral nerve–limb tissue interactions may cause human deformities such as idiopathic clubfoot and idiopathic limb length discrepancy.
Frequency spectrum analysis of wrist motion for activities of daily living
Authors: Mann Kenneth A. , Wernere Frederick W. , Palmer Andrew K.
Published: February 2005

A frequency spectral analysis was performed on wrist motion data for 24 activities of daily living (ADLs). Wrist motion was measured using a triaxial electrogoniometer attached to the wrist using tape (for 12 subjects) and pins (for one subject). Results show that the average predominant frequency component of these ADLs was ∼ 1 Hz with 75% of the spectral energy <5 Hz. The taped‐on electrogoniometer, when compared with the pinned electrogoniometer, was adequate for calculating the predominant frequency componenet and spread of spectral data, but overestimated the magnitudes of the maximum spectral density and total area of the spectral curves. This discrepancy was largest for axial rotation.
Cobalt, chromium, and nickel concentrations in body fluids of patients with porous‐coated knee or hip prostheses
Authors: Sunderman F. William , Hopfer Sidney M. , Swift Thomas , Rezuke William N. , Ziebka Linda , Highman Paul , Edwards Brian , Folcik Marilyn , Gossling Harry R.
Published: February 2005

Co, Cr, and Ni concentrations were determined by electrothermal atomic absorption spectrophotometry in serum and urine specimens collected from a group of 28 patients at intervals of from 1 day to 2.5 years after total knee or hip arthroplasty with porous‐coated prostheses fabricated of Co‐Cr alloy (ASTM F‐75‐82). Two control groups were also tested: (a) 42 healthy adults and (b) 16 orthopaedic patients after total knee or hip arthroplasty with porous‐coated prostheses fabricated predominantly of Ti‐Al‐V alloy (ASTM F‐136‐84). All prostheses contained polyethylene components to avoid metal‐to‐metal contact. Mean Co concentrations in serum and urine were slightly increased in patients with Co‐Cr knee implants at 6–120 weeks after surgery, compared with (a) preoperative values, (b) corresponding values in patients with Co‐Cr hip implants, and (c) corresponding values in control patients with Ti‐Al‐V knee and hip prostheses. Substantially increased Co levels were observed in serum and urine of two patients at 7 weeks and 22 months postarthroplasty, associated with loosening of the prostheses; one of the patients also had elevated Cr levels in serum and urine. Although ASTM F‐75‐82 and F‐136‐84 alloys contain very little Ni (<1.0 and <0.2% Ni, respectively, by wt), mean Ni concentrations in serum and urine were greatly increased at 1–2 days after implantation of Ti‐Al‐V and Co‐Cr prostheses, diminishing by 2 weeks. The postoperative hypernickelemia and nickeluresis may reflect contamination of the operative field with Ni‐containing particles from the drills, cutting jigs, and drilling jigs, or it may represent a previously unrecognized pathophysiological response to surgery.
Intramedullary bone repair and ingrowth into porous coated implants in the adult chicken: A histologic study and biochemical analysis of collagens
Authors: Brown Cameron C. , McLaughlin Robert E. , Balian Gary
Published: February 2005

A new model was developed to study the histologic and biochemical events during intramedullary bone repair and ingrowth into porous coated implants. Adult chickens were used because of the availability of specific antibody probes. Repair in the metaphysis and diaphysis were compared. Entering through a medial arthrotomy, the distal tibiotarsus was reamed and either impianted with a double‐ended porous coated rod or allowed to heal without implantation of a rod. Specimens analyzed histologically at 7, 14, 21, and 70 days postoperatively revealed direct formation of bone by osteoblasts with no evidence of a cartilaginous phase. At 70 days bony ingrowth was observed deep within the porous surface. Analysis of collagens with sodium dodecyl sulfate polyacrylamide gel electrophoresis demonstrated that the synthesis of type I collagen predominated. Biosynthetic data coupled with quantitative immunologic analyses using antibodies to type II and type X collagen showed that neither of these two collagen types, which are characteristic of cartilage undergoing endochondral ossification, were produced during intramedullary bone repair. These results establish that the adult chicken is capable of bony ingrowth into porous coated implants and that this process is through direct bone deposition by osteoblasts without a cartilaginous intermediate.
Cryopreserved articular chondrocytes grow in culture, maintain cartilage phenotype, and synthesize matrix components
Authors: Schachar N. , Nagao M. , Matsuyama T. , McAllister D. , Ishii S.
Published: February 2005

For osteochondral allograft transplantation to be successful, chondrocytes must survive preservation and retain their capacity to produce normal matrix components: proteoglycans and Type II collagen. Clinical success with osteochondral allograft transplantation has created an increased demand for supplies of suitable cartilage‐bearing grafts. This demand has stimulated attempts to find successful methods for low temperature storage of cartilage for “banking” and heightened interest in cartilage cryobiology. In order to achieve the maximum viability of cryopreserved articular cartilage, previous comprehensive studies have focused on rates and temperatures of freezing, cryoprotective agents, and methods and influences of thawing. This study presents evidence that cryopreserved articular chondrocytes maintain their ability to grow in tissue culture following thawing and to produce normal matrix components. Chondrocytes isolated from Japanese white rabbits were divided into groups of fresh controls and experimental cryopreserved cells. Cells were incubated in dimethylsulfoxide, frozen at a rate of −1°C/min, stored at −79°C, rapidly thawed, and plated for culture, Growth rates were comparable in all groups. In all groups, typical chondroid characteristics were maintained throughout 14 days of culture. Typical cartilage phenotypic characteristics included maintenance of polygonal and rhomboidal cells, cell aggregation, proteoglycan production, and Type II collagen synthesis. This investigation strongly indicates that articular chondrocyte cryopreservation yields viable, functional cells and although these results cannot be directly extrapolated to intact adult articular cartilage, they do give further support for low temperature banking of cartilage‐bearing allografts for transplantation.
Loads on the lumbar trunk during level walking
Authors: Cromwell Ronita , Schultz Albert B. , Beck Robert , Warwick David
Published: February 2005

The goal of this study was to estimate the loads internal to the lumbar trunk that arise during level walking. To do this, (a) trunk muscle activities were calibrated in terms of muscle contraction force levels in a set of isometric exertions; (b) trunk muscle myoelectric activities were measured during level walking; and then (c) the muscle contraction forces that arose during walking were calculated from these measurements and calibrations. Lumbar trunk muscle myoelectric activities were quantified in 10 healthy young males. Myoelectric activities were monitored using eight bipolar surface electrode pairs placed around the trunk at the level of the third lumbar vertebrae. The subjects first performed four static weight‐resisting tasks to calibrate muscle force/activity relationships. They then traversed a 8.25 m walkway three times each at cadences of 72 and 120 steps/min. A biomechanical model incorporating 22 lumbar trunk muscles was used to predict muscle contraction forces for the calibration tasks. Predicted forces were linearly correlated with the measured myoelectric activities for these tasks. The regression equations were then interpolated to estimate the muscle contraction forces from the myoelectric data during gait. Peak contraction forces for the iliocostalis muscles were calculated to be approximately 55 N per side, corresponding to total erector spinae peak contractions on the order of 140 N per side. For the other six muscles that were monitored, contraction forces were less than 15 N per side. This suggests that peak net reaction moments and peak spine compressions on the lumbar trunk during these walking tasks were on the order of 15 Nm and 1.2 times body weight, respectively.
The effect of grip strength on radial bone in postmenopausal women
Authors: Sandler Rivka Black , Cauley Jane A. , Sashin Donald , Scialabba Mary Ann , Kriska Andrea M.
Published: February 2005

This communication explores the correlation in 255 postmenopausal women of grip strength to bone tissue density (BTD) and cross‐sectional area (CSArea) of the radius. While grip strength correlated cross‐sectionally with the baseline measures of both BTD and CSArea, grip strength affected differentially the changes that transpired in the two bone parameters over the 3 years of the study. Thus, the increases in the CSArea of the radius were significantly enhanced by higher grip strength, while BTD losses were not. Since the power of muscle contraction is a factor in the mechanical loading of a bone, it is argued that the differential effects of grip strength on the two bone parameters of the radius suggest that moderate loading can effect favorable changes in the geometry of the bone, without necessarily affecting changes in BTD.
Gowth factor production by sarcoma cells in primary culture
Authors: Bell R. S. , Bell D. F. , Jacob J. , Trippel S. , Gebhardt M. C. , Mankin H. J.
Published: February 2005

Cell lines derived from human sarcomas have been previously shown to produce a protein growth factor which, similar to platelet‐derived growth factor (PDGF), can induce competence for mitosis in fibroblasts. Whether this factor production is an important feature of sarcomas in vivo or simply an artefact caused by long‐term culture conditions is unclear, however. We demonstrated growth factor activity in conditioned medium from six of 11 primary sarcoma cultures, utilizing flow cytometric analysis of DNA to monitor the presence of sarcoma cells in cultures. Cells isolated from control tissues failed to show a similar mitotic effect.
Injury of the anterior cruciate ligament: The role of collagenase in ligament degeneration
Authors: Amiel D. , Ishizue K. K. , Harwood F. L. , Kitabayashi L. , Akeson W. H.
Published: February 2005

Rapid degeneration of the anterior cruciate ligament (ACL) has been observed following acute ACL rupture. An understanding of this process might explain some of the poor clinical results of primary ACL repair. We created a surgical rabbit model of acute ACL injury and developed an in vitro assay for collagenase activity in the ACL and menisci. Microscopic evaluation revealed a rapidly degenerative process in injured ACLs, with loss of cellularity and matrix organization. This was associated with a significant increase in collagenase activity and a decrease in total collagen of the injured ACLs as compared with sham‐operated controls. These findings confirm the observation that cut ACL ligament ends rapidly degenerate. This degenerative process might be partly due to a response of cells intrinsic to the ACL to injury. Left unchecked, this process may be detrimental to surgical attempts for primary ACL repair.
The effect of cryopreservation on the biomechanical behavior of bovine articular cartilage
Authors: Kiefer G. N. , Sundby K. , McAllister D. , Shrive N. G. , Frank C. B. , Lam T. , Schachar N. S.
Published: February 2005

The short‐term effect of cryopreservation on specific mechanical behaviors of bovine articular cartilage has been investigated. A flat‐ended nonporous indentor was used in a nondestructive, repetitive, axisymmetric unconstrained testing system. Cyclical indentation from a fixed position to a fixed load was applied until a steady‐state load‐deformation relationship (limit cycle) was achieved. Indentation behaviors measured from the limit cycles of each articular cartilage specimen before and after treatment were compared. Testing was done in vitro using fresh, mature bovine radiocarpal joints. Twenty pairs of cartilage‐subchondral bone cores from anatomically similar sites on contralateral joints were separated into three groups; thickness controls, dimethylsulfoxide (DMSO) controls, and cryopreserved experimental samples. Thickness controls and DMSO controls were used to examine the isolated effects of the thickness measurement and DMSO incubation techniques on articular cartilage indentation characteristics. Experimental samples were cryopreserved using DMSO, their thicknesses similarly measured and indentation behaviors examined. Following testing, histological and histochemical assessment of the specimens confirmed the nondestructive nature of the tests. Intra‐ and intergroup comparisons of controls and experimentals revealed no statistical differences in the mechanical behaviors measured from the limit cycle or in cartilage thickness. These results indicate that the cryopreservation protocol used did not have an effect that we could measure on these specific mechanical behaviors of articular cartilage.
Effects of electrical stimulation on joint contracture in a rat model
Authors: Tart Roger P. , Dahners Laurence E.
Published: February 2005

This study was intended to delineate whether electrical stimulation could significantly reduce the amount of joint contracture in a rat model. Rat knees were surgically immobilized in 150° of flexion. Two groups of rats had sham electrodes, and two groups were electrically stimulated. All rats were killed 14 days after surgery. The degree of joint contracture was assessed by measuring the femorotibial angles with a 0.015‐Nm extension moment applied. When the electrical current was applied in a transverse manner, there was a statistically significant reduction in the amount of posterior capsule (p < 0.005) and anterior cruciate ligament (ACL) (p < 0.005) contracture. When the electrical current was applied longitudinally, no significant difference in the amount of joint contracture was found. These findings support the hypothesis that electrical stimulation can inhibit joint contracture. These findings also suggest that the effect occurs when the electrical current is applied transversoly as opposed to longitudinally.
Different effects of mechanical vibration on bone ingrowth into porous hydroxyapatite and fracture healing in a rabbit model
Authors: Usui Yasuo , Zerwekh Joseph E. , Vanharanta Heikki , Ashman Richard B. , Mooney Vert
Published: February 2005

The effects of mechanical vibration on bone ingrowth into porous hydroxyapatite implants and fracture healing were examined radiographically, histomorphometrically, and biomechanically in a rabbit model. Fifty‐three female NZW rabbits were used in this study. These rabbits were divided into four separate studies to assess the effects of 20 and 60 min of vibration/day in both implant and osteotomy models as compared with the respective nonvibrated controls. For the implant model, coral hydroxyapatite goniopora rods were implanted bilaterally into tibiae and for the osteotomy model, bilateral fibulae were osteotomized. A resonant frequency of 25 Hz mechanical vibration was used. After periods of 2, 3, 4, and 6 weeks of vibration, the rabbits were killed and examined. For the implant model, there was no significant difference between control, 20, or 60 min of vibration/day with respect to the rate or amount of new bone ingrowth. For the fracture model, 60 min of vibration/day produced a significantly larger callus as compared with the nonvibrated controls (p < 0.05), whereas 20 min of vibration/day did not. Although biomechanical testing demonstrated a general trend for increased strength in the vibrated animals, it failed to reach significance. These results suggest that the mechanical vibration used in the present study had a beneficial effect on callus volume, possibly due to the stimulation of secondary bone healing processes, but does not appear to promote bone ingrowth into a porous hydroxyapatite implant.
Allograft incorporation: A biomechanical evaluation in a rat model
Authors: Pelker Richard R. , McKay James , Troiano Nancy , Panjabi Manohar M. , Friedlaender Gary E.
Published: February 2005

Allogeneic bone from Sprague‐Dawley rat femurs was subjected to levels of freezing and/or irradiation that are known to have produced changes in the associated immune responses to these grafts. This bone was transplanted into an experimentally created gap in the femur of Lewis rats. The subsequent healing of the transplants in the Lewis rats was studied at 2,4,8, and 16 weeks after transplantation using torsion testing to failure. There was no clear advantageous biologic response in the union of the grafted material accompanying the alterations in immunologic response as measured by biomechanical testing of the proximal osteosynthesis site in torsion. The torsional strength of all of these groups remained lower than that of intact bone. Furthermore, none of the frozen and/or irradiated allografts exceeded the strength of the fresh allograft at a statistically significant level.