bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fibroblast orientation to stretch begins within three hours
Authors: Neidlinger‐Wilke C. , Grood E. , Claes L. , Brand R. 
Published: August 2002

AbstractMost connective tissue cells align in response to stretch. Previous studies have shown these responses occur within 12–14 h of initiation of stretch, but do not identify the time at which this orientation occurs, nor whether the orientation continues after cessation of stretch. To ascertain the earliest times at which fibroblast orientation occurs, we cultured primary human fibroblasts on deformable culture dishes and stretched (1 Hz, 8% uniaxial strain) them for up to 24 h. We photographed the cells at 0.5, 1–6, 8, 10, 12, 14, 16, and 24 h. Similarly cells were photographed at 1–3, or 4 h after cessation of stretch for stretch durations of 1, 2, and 3 h. Orientation of cells were ascertained by an interactive computer program. The fibroblasts began to orient by 2–3 h and orientation appeared nearly complete by 24 h. Cultures stretched for 2 or 3 h continued to exhibit greater degrees of orientation (compared to controls) for 2 or 3 h respectively after cessation of stretch. We conclude fibroblasts begin to orient within 3 h of initiation of stretch, and that they continue to orient for several hours after cessation of stretch.© 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Effects of growth factors on cell proliferation and matrix synthesis of low‐density, primary bovine chondrocytes cultured in collagen I gels
Authors: Chaipinyo Kanda , Oakes Barry W. , van Damme Marie‐Paule I. 
Published: August 2002

AbstractLow cell density cell numbers and dedifferentiation are two major problems of human chondrocyte culture associated with articular cartilage repair. Bovine chondrocytes seeded at low density (3.5 x 104 cells/ml of gels) in three‐dimensional collagen type I gels do proliferate and maintain their phenotype as shown by cell counts, morphology and matrix synthesis. The combination of three growth factors (3GFs; 10 ng/ml TGF‐β1 + 100 ng/ml IGF‐I + 10 ng/ml b‐FGF) added to serum‐free culture medium in this culture system enhances the mitotic activity of bovine chondrocytes similar to 20% foetal calf serum (FCS). At day 21, cells proliferated by 41 fold in gels–FCS and 37 fold in gels–3GFs. Protein synthesis by gels–3GFs cultures was similar to 20% PCS when cultured for 3 weeks but much less proteoglycan was synthesized. The matrix deposition as observed by light and electron microscopy was quite different. More small diameter branching collagen fibrils and a denser matrix were presented in gels‐FCS culture whilst loosely arranged larger diameter collagen fibrils were observed in gels‐3GFs.© 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Denervation impairs healing of the rabbit medial collateral ligament
Authors: Ivie T. J. , Bray R. C. , Salo P. T. 
Published: August 2002

AbstractLittle is known about the contribution of innervation to ligament healing after traumatic disruption, although there is good evidence of an important role for the peripheral nervous system in the healing of fractures and skin injuries.Tissues such as ligament, with a low resting blood supply, are dependent on substantial increases in blood flow and vascular volume during the initial stages of repair. We hypothesized that this initial healing response would be strongly promoted by neurogenic inflammation. Since the saphenous nerve (a major sensory branch of the femoral nerve) supplies the medial half of the knee joint, we elected to use femoral nerve transection as a model to determine the role of sensory and autonomic innervation in the initial outcome of repair of the injured medial collateral ligament. Twelve adult, female NZW rabbits underwent right medial collateral ligament transection. Of these, six rabbits underwent right femoral nerve transection to disrupt the somatic sensory and autonomic nerve supply to the knee joint and six were kept neurologically intact (controls). At six weeks post‐injury, the animals were assessed by laser Doppler perfusion imaging (LDI) to determine the local blood flow, at both the injury site and at the uninjured contralateral ligament. The animals were then killed, the knee joints were removed and the biomechanical characteristics of the healing bone–median collateral ligament (MCL)–bone complexes assessed. In a separate cohort of 16 rabbits, vascular volumes of the injured ligaments were measured by infusion of a carmine red/gelatin solution.At six weeks post‐injury, in vivo measurement of perfusion with LDI revealed that normally innervated ligaments had an almost three‐fold higher average blood flow. Carmine red/gelatin infusion revealed a 50% higher density of blood vessels as compared to denervated ligaments. The force required for ultimate failure was found to be 50% higher in normally innnervated MCL's as compared to denervated MCL's: 153.14 ± 20.71 N versus 101.29 ± 17.88 N (p < 0.05). Static creep was increased by 66% in denervated MCL's: 2.83 ± 0.45% versus 1.70 ± 0.12% (p < 0.05). Total creep was increased by 45% in denervated MCL's: 5.29 ± 0.62% compared to 3.64 ± 0.31% in innervated MCL's (p < 0.05).We conclude that intact innervation makes a critical contribution to the early healing responses of the MCL of adult rabbits.© 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Achilles tendon healing: Long‐term biomechanical effects of postoperative mobilization and immobilization in a new mouse model
Authors: Palmes D. , Spiegel H. U. , Schneider T. O. , Langer M. , Stratmann U. , Budny T. , Probst A. 
Published: August 2002

AbstractThe aim of the study was to investigate the long‐term effects of postoperative immobilization as opposed to mobilization on the biomechanical attributes of healing Achilles tendons in a new experimental mouse model.In 114 Balb‐C‐mice the left Achilles tendon was transected and sutured by the Kirchmayr–Kessler technique. The tendons healed either under postoperative immobilization effected by fixing the upper ankle joint in equinus position or under mobilization through a limited range of movement. The contralateral Achilles tendons served as internal control. All tendons were tested biomechanically at short intervals up to the 112th postoperative day in terms of load to failure [N], tendon deflection [mm] and tendon stiffness [N/mm], and were evaluated histologically after 8 and 112 days.Postoperative mobilization resulted in a continuous and significantly more rapid restoration of load to failure in comparison to the immobilization group. Tendon deflection was decreased by postoperative mobilization, whereas under immobilization it paradoxically increased still further in the later course. After 112 days the tendons of the mobilization group had regained their original tendon stiffness, whereas the tendons after immobilization reached only about half the values seen in the control tendons. Histologically, postoperative mobilization led to increased immigration of inflammatory cells in the early phase. In the late phase, as compared to immobilization, tendon structure was more mature, with fibre bundles arranged in parallel and interposed tendocytes.Tensile loading of the healing tendon by postoperative mobilization leads to fundamental changes in the biological process of tendon healing resulting in accelerated restoration of load to failure and reduced tendon deflection.© 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Effects of femoral tunnel placement on knee laxity and forces in an anterior cruciate ligament graft
Authors: Markolf Keith L. , Hame Sharon , Monte Hunter D. , Oakes Daniel A. , Zoric Bojan , Gause Paul , Finerman Gerald A. M. 
Published: August 2002

AbstractThe purpose of this study was to measure the effects of variation in placement of the femoral tunnel upon knee laxity, graft pretension required to restore normal anterior–posterior (AP) laxity and graft forces following anterior cruciate ligament (ACL) reconstruction. Two variants in tunnel position were studied: (1) AP position along the medial border of the lateral femoral condyle (at a standard 11 o'clock notch orientation) and (2) orientation along the arc of the femoral notch (o'clock position) at a fixed distance of 6–7 mm anterior to the posterior wall. AP laxity and forces in the native ACL were measured in fresh frozen cadaveric knee specimens during passive knee flexion‐extension under the following modes of tibial loading: no external tibial force, anterior tibial force, varus–valgus moment, and internal–external tibial torque. One group (15 specimens) was used to determine effects of AP tunnel placement, while a second group (14 specimens) was used to study variations in o'clock position of the femoral tunnel within the femoral notch. A bone‐patellar tendon‐bone graft was placed into a femoral tunnel centered at a point 6–7 mm anterior to the posterior wall at the 11 o'clock position in the femoral notch. A graft pretension was determined such that AP laxity of the knee at 30 deg of flexion was restored to within 1 mm of normal; this was termed the laxity match pretension. All tests were repeated with a graft in the standard 11 o'clock tunnel, and then with a graft in tunnels placed at other selected positions. Varying placement of the femoral tunnel 1 h clockwise or counterclockwise from the 11 o'clock position did not significantly affect any biomechanical parameter measured in this study, nor did placing the graft 2.5 mm posteriorly within the standard 11 o'clock femoral tunnel. Placing the graft in a tunnel 5.0 mm anterior to the standard 11 o'clock tunnel increased the mean laxity match pretension by 16.8 N (62%) and produced a knee which was on average 1.7 mm more lax than normal at 10 deg of flexion and 4.2 mm less lax at 90 deg. During passive knee flexion‐extension testing, mean graft forces with the 5.0 mm anterior tunnel were significantly higher than corresponding means with the standard 11 o'clock tunnel between 40 and 90 deg of flexion for all modes of constant tibial loading. These results indicate that AP positioning of the femoral tunnel at the 11 o'clock position is more critical than o'clock positioning in terms of restoring normal levels of graft force and knee laxity profiles at the time of ACL reconstruction.© 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Activation of stress‐activated protein kinases (SAPK) in tendon cells following cyclic strain: the effects of strain frequency, strain magnitude, and cytosolic calcium
Authors: Arnoczky Steven P. , Tian Tao , Lavagnino Michael , Gardner Keri , Schuler Paul , Morse Patrick 
Published: August 2002

AbstractCyclic strain has been shown to benefit tendon health. However, repetitive loading has also been implicated in the etiology of tendon overuse injuries. Recent studies demonstrated that in several cell lines cyclic strain was associated with an activation of stress‐activated protein kinases (SAPKs). These SAPKs, in turn, were shown to be important upstream regulators of a variety of cell processes including apoptosis. To examine the effect of repetitive loading on SAPK activation in tendon cells in vitro, canine patellar tendon cells were cyclically strained, and the cellular stress response evaluated by measuring c‐Jun N‐terminal kinase (JNK) activation. The effects of strain frequency and strain magnitude as well as the role of calcium signaling in this mechanotransduction mechanism were also examined. Cyclic strain resulted in an immediate activation of JNK, which peaked at 30 min and returned to resting levels by 2 h. This activation was regulated by a magnitude‐dependent but not frequency‐dependent response and appeared to be mediated through a calcium‐dependent mechanotransduction pathway. While transient JNK activation is associated with normal cell processes, persistent JNK activation has been linked to the initiation of the apoptotic cascade. A similar mechanism could be responsible for initiating the pathological events (localized cell death) seen in tendon overuse injury.© 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
The effects of bone density and disc degeneration on the structural property distributions in the lower lumbar vertebral endplates
Authors: Grant J. P. , Oxland Thomas R. , Dvorak Marcel F. , Fisher Charles G. 
Published: August 2002

AbstractIn this study, we hypothesized that vertebral bone density and disc degeneration would affect the structural property distributions of the lower lumbar vertebral endplates (L3–L5). The results may have implications for improving interbody implant designs to better resist subsidence. A 3 mm diameter hemispherical indenter was used to perform indentation tests at 0.2 mm/s to a depth of 3 mm at 27 standardized locations in 55 bony endplates of intact human lumbar vertebrae (L3–L5). The resulting load–displacement curves were used to extract the failure load and stiffness of each test site. Bone density was measured using lateral DEXA scans. Disc condition was determined using a four‐point grading scale. Three‐way analyses of variance were used to analyze the relationships between the data. The overall failure load decreased with bone mineral density (BMD) in the superior (p = 0.0001) and inferior (p = 0.011) lumbar endplates. In both endplates, the posterolateral regions were significantly stronger than more central regions. With increasing BMD, this difference became more pronounced in the superior endplates only (p = 0.005). Increased disc degeneration was associated with an overall failure load decrease in the inferior lumbar endplates (p = 0.002). The strength in the central regions of the superior endplates was reduced with increasing degeneration, but this was not observed peripherally (p = 0.001). Stiffness magnitude or distribution was not significantly affected by BMD or disc degeneration. The locations of the strongest regions of the endplate did not change with either bone density or disc degeneration. This implies that implant shapes designed using the basic structural property maps for the L3–L5 endplates are appropriate for use in patients with a wide range of pathologies, even though overall failure loads are generally lower in patients with reduced bone density and greater degrees of disc degeneration.© 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Releasing the A3 pulley and leaving flexor superficialis intact increases pinch force following the Zancolli lasso procedures to prevent claw deformity in the intrinsic palsied finger
Authors: Valero‐Cuevas Francisco J. , Hentz Vincent R. 
Published: August 2002

AbstractObjective estimates of fingertip force magnitude following surgery to prevent digital metacarpophalangeal (MCP) hyperextension (clawing) in cases of paralysis of the hand's intrinsic muscles will assist clinicians in setting realistic expectations for post‐operative pinch strength. We used a cadaveric/optimization approach to predict and confirm the maximal biomechanically possible fingertip force in the intrinsic palsied hand before and after two popular tendon transfer methods to the volar plate of the MCP joint. Both surgeries were also evaluated after release of the A3 pulley—a modification predicted by our published computer model of the forefinger to increase fingertip force magnitude. We predicted maximal static fingertip force by mounting eight fresh cadaveric hands on a frame, placing their forefinger in a functional posture (neutral abduction, 45° of flexion at the MCP and proximal inter‐phalangeal joints, and 10° at the distal interphalangeal joint) and pinning the distal phalanx to a 3D dynamometer. We pulled on individual tendons with tensions up to 25% of maximal isometric force of their associated muscle and measured fingertip force and torque output. Using these measurements, we predicted the optimal combination of tendon tensions that maximized palmar force (analogous to pinch force, directed perpendicularly from the midpoint of the distal phalanx, and in the plane of finger flexion‐extension) for four cases: (i) the non‐paretic case (all muscles available), (ii) intrinsic palsied hand (no intrinsic muscles functioning), (iii) transfer of flexor superficialis tendon to the volar plate of the MCP (Zancolli lasso) in the intrinsic palsied hand, and (iv) leaving flexor superficialis intact and transferring a tendon of comparable strength to the volar plate of the MCP in the intrinsic palsied hand. Lastly, we applied these optimal combinations of tension to the cadaveric tendons and measured fingertip output. With the A3 pulley intact, the maximal palmar force in cases (ii)–(iv) averaged 48 ± 23% SD (non‐paretic = 100%; case (iv) (61 ± 25%) > cases (ii) and (iii) (43 ± 23% and 39 ± 19%, respectively), p < 0.05). Releasing the A3 pulley significantly increased the average palmar force in cases (ii)–(iv) (73 ± 42%, p < 0.05), with no significant differences among them. Thus, releasing the A3 pulley may improve palmar force magnitude when it is necessary to transfer the digit's own flexor superficialis tendon to the volar plate of the MCP to prevent clawing in the intrinsic palsied hand.© 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
The effect of mechanical stability on local vascularization and tissue differentiation in callus healing
Authors: Claes Lutz , Eckert‐Hübner Kerstin , Augat Peter 
Published: August 2002

AbstractTo investigate the influence of the stability of an osteotomy fixation on the local vascularization and tissue differentiation in callus healing, a transverse osteotomy of the right metatarsal with a gap size of 2 mm was performed in 10 sheep and stabilized with an external fixator. This fixator permitted a defined axial movement. Two groups of 5 sheep were each operated upon to allow 0.2 mm (group A) or 1 mm (group B) of axial movement. Nine weeks after surgery, the callus was dissected and histological sections prepared. The type of tissue and the vessel distribution were determined.Larger interfragmentary movements led to significantly more fibrocartilage (small axial movement A: 6.2%, large axial movement B: 21.6%) and significantly less bone formation (A: 38.2%, B: 26.3%). On average, and particularly close to the periosteum the number of vessels in the callus healing area was greater in the group with smaller movements than in the group with larger movements. There was a significant difference between the distribution of small (<20 μm) and large (>40 μm) vessels across the whole healing area for both groups. Whereas the large vessels showed maximum density in the medullary cavity, the small vessels showed the highest frequency in the peripheral part of the periosteal callus.© 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Visual linearization of the display of digital radiographs.
Authors: Li G , Yoshiura K , Welander U , Sällstrom P , McDavid W D 
Published: September 2002

OBJECTIVES To derive and test a method to linearize the visual response of the display of digital radiographs so that equal steps in gray levels will be perceived as equal steps in brightness. METHOD A mathematical analysis was performed and expressions for visual linearization were derived. Twenty-four test images were computer generated to confirm that visual linearization may be achieved. Each image had three groups of square areas of different size placed in three rows. The left and right squares in each row were given different gray levels to simulate various contrast levels. The middle squares were initially given the same gray level value as one of the outer squares. The images were examined by ten observers who could change the gray levels of the middle squares so that the step in brightness between the middle square and the outer squares become subjectively equal. The test was performed three times employing two different monitors. RESULTS The experimental test confirmed that visual linearization could be achieved. Linear regression analyses gave determination coefficients of 0.9926 amd 0.9942 for monitors with gamma-values of 1.93 and 2.50. respectively. The mean data from the ten observers perfectly fitted those theoretically calculated. CONCLUSION Visual linearization of gray levels can be achieved but further clinical research is needed to determine if this improves diagnosis.
The views of primary health care professionals about the management of breast problems in clinical practice
Authors:   The BRIDGE Study Group
Published: August 2002

Abstract Rationale, aims and objectives To identify primary health care professionals’ views about patients presenting with breast problems, and their approaches to clinical management. Methods Qualitative study using practice‐based semi‐structured group discussions with primary health care professionals. All practices were involved in a study evaluating the effect of the national breast symptom management guidelines on clinical practice. Discussion groups were conducted in the practices; 15 of the 34 study practices were audio‐taped. Groups comprised the partners and practice nurses at each practice. All members of each group were well known to one another. There was good attendance by all doctors, with 75% of male partners and 90% of female partners present at the meetings. Of the practice nurses, 51% attended. In all, 86 professionals attended the meetings. Results A number of themes arose consistently from the discussions. Participants were concerned about the possible consequences of errors in diagnosis and about difficulties concerning the ‘management of uncertainty’. Doctors were influenced especially by adverse past experiences. Other difficult situations included referral decisions and the management of risk factors in isolation from clinical presentation. Outside influences on presentation and management, such as the media, were also noted. Conclusions The management of breast disease is perceived as a complex issue by health professionals. The patient and doctor contextual factors described must be taken into account in discussions about what constitutes appropriate clinical management and in the development and implementation of clinical guidelines to improve management.