Advertisement for orthosearch.org.uk
Results 1 - 20 of 31
Results per page:
Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_7 | Pages 135 - 135
4 Apr 2023
Monahan G Schiavi-Tritz J Vaughan T
Full Access

This study aims to assess the fracture mechanics of type-2 diabetic (T2D) femoral bone using innovative site-specific tests, whilst also examining the cortical and trabecular bone microarchitecture from various regions using micro-computed tomography (CT) of the femur as the disease progresses. Male [Zucker Diabetic Fatty (ZDF: fa/fa) (T2D) and Zucker Lean (ZL: fa/+) (Control)] rats were euthanized at 12-weeks of age, thereafter, right and left femora were dissected (Right femora: n = 6, per age, per condition; Left femora: n=8-9, per age, per condition). Right femurs were notched in the posterior of the midshaft. Micro-CT was used to scan the proximal femur, notched and unnotched femoral midshaft (cortical) of the right femur and the distal metaphysis (trabecular) of the left femur to investigate microarchitecture and composition. Right femurs were fracture toughness tested to measure the stress intensity factor (Kic) followed by a sideways fall test using a custom-made rig to investigate femoral neck mechanical properties. There was no difference in trabecular and cortical tissue material density (TMD) between T2D and control rats. Cortical thickness was unchanged, but trabeculae were thinner (p<0.01) in T2D rats versus controls. However, T2D rats had a greater number of trabeculae (p<0.05) although trabecular spacing was not different to controls. T2D rats had a higher connectivity distribution (p<0.05) and degree of anisotropy (p<0.05) in comparison to controls. There was no difference in the mechanical properties between strains. At 12-weeks of age, rats are experiencing early-stage T2Ds and the disease impact is currently not very clear. Structural and material properties are unchanged between strains, but the trabecular morphology shows that T2D rats have more trabecular struts present in order to account for the thinner trabeculae


The Journal of Bone & Joint Surgery British Volume
Vol. 89-B, Issue 10 | Pages 1402 - 1406
1 Oct 2007
Tayton K

Although much has been published on the causes of slipped upper femoral epiphysis and the results of treatment, little attention has been given to the mechanism of the slip. This study presents the results of the analysis of 13 adolescent femora, and the attempts to reproduce the radiological appearances of a typical slip. The mean age of the skeletons was 13 years (11 to 15). It was found that the internal bony architecture in the zone of the growth plate was such that a slip of the epiphysis on the metaphysis (in the normal meaning of the word slip) could not take place, largely relating to the presence of a tubercle of bone projecting down from the epiphysis. The only way that the appearance of a typical slipped upper femoral epiphysis could be reproduced was by rotating the epiphysis posteromedially on the metaphysis. The presence and size of this peg-like tubercle was shown radiologically by CT scanning in one pair of intact adolescent femurs


Orthopaedic Proceedings
Vol. 103-B, Issue SUPP_13 | Pages 95 - 95
1 Nov 2021
Timmen M Husmann N Wistube J Stange R
Full Access

Introduction and Objective. Klinefelter Syndrome (KS, karyotype 47,XXY) is the most frequent chromosomal aneuploidy in males, as well as the most common cause of infertility in men. Patients suffer from a lack of testosterone, i.e. hypergonadotropic hypogonadism provoking infertility, but KS men also show an increased predisposition to osteoporosis and a higher risk of bone fracture. In a mouse model for human KS, bone analysis of adult mice revealed a decrease in bone mass that could not be rescued by testosterone replacement, suggesting a gene dosage effect originating from the supernumerary X-chromosome on bone metabolism. Usually, X chromosome inactivation (XCI) compensates for the dosage imbalance of X-chromosomal genes between sexes. Some studies suggested that expression of genes that escape silencing of the supernumerary X-chromosome (e.g. androgen receptor) has an impact on sex differences, but may also cause pathological changes in males. As a promising new such candidate for a musculoskeletal escape gene, we identified the integral membrane protein (ITM) 2a, which is encoded on the X-chromosome and related to enchondral ossification. The aim of the project was to characterize systemic bone loss in the course of aging in our KS mouse model, and whether the supernumerary X-chromosome causes differences in expression of genes related to bone development. Materials and Methods. Bone structure of 24 month (=aged) old male wild type (WT) and 41, XXY mice (B6Ei.Lt-Y) were analysed by μCT. Afterwards bones were paraffin embedded and cut. In addition, tissue of brain, liver, kidney, lung and heart were also isolated and embedded for IHC staining. Using an anti-ITM2a antibody, expression and cellular localization of ITM2a was evaluated. IHC was also performed on musculoskeletal tissue of WT embryos (E18.5) and neonatal mice to determine possible age-related differences. Results. In 24 month old mice, the analysis of the lumbar vertebrae revealed a significantly lower BV/TV, trabecular bone volume and trabecular number in the XXY- group compared to WT. Trabecular thickness appeared lower but did not reach significance, with the cortical thickness being significantly higher in the XXY- group. High expression of ITM2a was detected in bone slices of both karyotypes in the chondrocytes inside the growth plate, as well as in megakaryocytes and leucocytes as well as endothelial cells of blood vessels inside the bone marrow. Osteocytes, along with erythrocytes and erythropoetic stem cells were negative for ITM2a. Other organs that showed ITM2a positive staining were kidney (blood vessels), heart (muscle) and brain (different structures). Liver and lung tissue were negative for ITM2a. No obvious difference in the intensity of the ITM2a-expression was observed between the WT and the XXY-karyotype. Analyses of embryotic bone tissue (WT) showed high expression of ITM2a in proliferating, hypertrophic and resting chondrocytes in the growth plates of tibia and femur. In comparison, the neonatal animals (WT) did not show any protein-expression in chondrocytes. Furthermore, within the metaphysis of both, embryotic and neonatal bones, endothelial cells and osteoblasts were ITM2a-positive. Further analyses of bones and tissues from young mice (4–6 month) are ongoing. Conclusions. Bone analyses revealed a significant reduction in trabecular bone mass along with fewer and thinner trabeculae in XXY mice compared to the WT, especially in the spine. ITM2a expression was visible in different cell types inside the bone, and in addition, different expression patterns at different stages of development (embryonic/neonatal) were observed. However, we have not found a significant difference in the quantity of ITM2a between tissues of XXY-karyotypes and WT. Further analyses of X-chromosomal encoded and therefore dysregulated modulators in XXY-karyotype mice and patients may reveal new sex chromosomal effector proteins in bone metabolism


Bone & Joint Research
Vol. 7, Issue 1 | Pages 6 - 11
1 Jan 2018
Wong RMY Choy MHV Li MCM Leung K K-H. Chow S Cheung W Cheng JCY

Objectives. The treatment of osteoporotic fractures is a major challenge, and the enhancement of healing is critical as a major goal in modern fracture management. Most osteoporotic fractures occur at the metaphyseal bone region but few models exist and the healing is still poorly understood. A systematic review was conducted to identify and analyse the appropriateness of current osteoporotic metaphyseal fracture animal models. Materials and Methods. A literature search was performed on the Pubmed, Embase, and Web of Science databases, and relevant articles were selected. A total of 19 studies were included. Information on the animal, induction of osteoporosis, fracture technique, site and fixation, healing results, and utility of the model were extracted. Results. Fracture techniques included drill hole defects (3 of 19), bone defects (3 of 19), partial osteotomy (1 of 19), and complete osteotomies (12 of 19). Drill hole models and incomplete osteotomy models are easy to perform and allow the study of therapeutic agents but do not represent the usual clinical setting. Additionally, biomaterials can be filled into drill hole defects for analysis. Complete osteotomy models are most commonly used and are best suited for the investigation of therapeutic drugs or noninvasive interventions. The metaphyseal defect models allow the study of biomaterials, which are associated with complex and comminuted osteoporotic fractures. Conclusion. For a clinically relevant model, we propose that an animal model should satisfy the following criteria to study osteoporotic fracture healing: 1) induction of osteoporosis, 2) complete osteotomy or defect at the metaphysis unilaterally, and 3) internal fixation. Cite this article: R. M. Y. Wong, M. H. V. Choy, M. C. M. Li, K-S. Leung, S. K-H. Chow, W-H. Cheung, J. C. Y. Cheng. A systematic review of current osteoporotic metaphyseal fracture animal models. Bone Joint Res 2018;7:6–11. DOI: 10.1302/2046-3758.71.BJR-2016-0334.R2


Orthopaedic Proceedings
Vol. 100-B, Issue SUPP_16 | Pages 136 - 136
1 Nov 2018
Elghobashy O Hadrawi A Alharbi H Dawood A Kutty S Gaine W
Full Access

Late presentation of DDH continues to remain a major problem particularly in the developing countries. Femoro-Acetabular Zones (FAZ) system is created to find a relation between acetabular maturity and severity of dislocation, in one hand, and the success of closed reduction, on the other hand. We hypnosis that the lower the acetabular index and the closer the femoral head to the acetabulum, the more likely the success of treatment. Thus, a retrospective study was performed on late diagnosed DDH hips that underwent closed treatment at a particular hospital in the Middle East. FAZ are drawn on the AP view of the pelvic x-ray and is based on a perpendicular from the acetabular index at the lateral margin of the superior acetabular rim then another perpendicular to Perkin's line is drawn. This gives three zones, graded I-III. The center of femoral metaphysis is identified denoting the position of the femoral head in relation to the zone classification. FAZ system was applied on 65 pelvic radiographs; mean patient age was 24 months (range: 12 to 36 months) with a minimum follow up of 3 years. Overall, 37 of 65 hips (57%) achieved a satisfactory outcome (Severin I&II), while 22 hips (33%) were found to be unsatisfactory (Severin III). 6 hips (10%) needed an open reduction (p-value 0.001). FAZ could perfectly predict the successful cases. FAZ system is a simple and novel classification and if employed, could reasonably predict the outcome of non-surgical treatment of DDH after walking age


Aims

This study intended to investigate the effect of vericiguat (VIT) on titanium rod osseointegration in aged rats with iron overload, and also explore the role of VIT in osteoblast and osteoclast differentiation.

Methods

In this study, 60 rats were included in a titanium rod implantation model and underwent subsequent guanylate cyclase treatment. Imaging, histology, and biomechanics were used to evaluate the osseointegration of rats in each group. First, the impact of VIT on bone integration in aged rats with iron overload was investigated. Subsequently, VIT was employed to modulate the differentiation of MC3T3-E1 cells and RAW264.7 cells under conditions of iron overload.


The Journal of Bone & Joint Surgery British Volume
Vol. 79-B, Issue 3 | Pages 487 - 489
1 May 1997
Magyar G Toksvig-Larsen S Moroni A

We measured the insertion and extraction torque forces in a randomised study of 76 external fixation screws in 19 patients treated by hemicallotasis for osteoarthritis of the medial side of the knee. The patients were randomised to have either standard tapered screws (Orthofix 6/5 mm) or the same screws with hydroxyapatite (HA) coating. One patient had two standard and two HA-coated screws. All patients had an anterior external fixator (Orthofix T-garche), with two screws in the proximal tibial metaphysis parallel to and about 2 cm below the joint surface and two in the tibial diaphysis. The mean torque forces for insertion of the standard screws were 260 Ncm for the proximal to medial screw, 208 for the proximal to lateral screw and 498 and 546 Ncm for the diaphyseal pins. The corresponding forces for the HA-coated pins were not significantly different. The torque forces for the extraction of the standard pins were 2 Ncm for the proximal pins, 277 and 249 Ncm for the distal pins and 482, 478, 585 and 620 Ncm, respectively (p < 0.005) for the HA-coated pins. All 18 of the metaphyseal standard screws were loose at extraction (extraction force < 20 Ncm), but only one of the HA screws in the metaphysis was loose. In the diaphysis the standard screws lost about 40% of their fixation in contrast to the HA-coated screws which retained full fixation strength


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_8 | Pages 36 - 36
1 Apr 2017
Ray S Thormann U Sommer U ElKhassawna T Rhonke M Henns A Gelinsky M Hanke T Schnettler R Heiss C Alt V
Full Access

Background. Multiple Myeloma is a hematological malignancy of terminally differentiated plasma cells associated with increased osteoclast activity and decreased osteoblast functions. Systemic antiproliferative treatment includes proteasome inhibitors such as bortezomib, a clinical potent antimyeloma agent. Local delivery of biological active molecules via biomaterial composite implants to the site of the lesion has been shown to be beneficial for bone and implant-associated infections. In anticancer treatment local delivery of anticancer agents to the neoplasia via biomaterial carriers has never been reported before. The purpose of the current is to present the concepts and the first in vivo results for proteasome inhibitor composite biomaterials for local delivery of bortezomib to proliferative multiple myeloma bone lesions including concentration measurements at different anatomical regions in a rat model. Methods. 80 female Sprague-Dawley rats were randomised into five different treatment groups (n=16/group): 1) Empty (2) Xerogel-granulat: XG (3) Xerogel-granulat+100mgbortezomib [b]: XG100b (4) Xerogel-granulat+500mgb:XG500b (5) Xerogel-granulat+2500mgb:XG2500b. A 2.5 mm drill hole was then created in the metaphysis of the left femur. The defect was then either filled with the previously mentioned substitutes or left empty to serve as a control. After 4 weeks femora were harvested followed by histological, histomorphometrical and immunohistochemical (BMP2; bone-morphogenic protein 2, OPG; osteoprotegerin, RANKL; Receptor activator of nuclear factor kappa-B ligand, ASMA; alpha smooth muscle actin, ED1;CD68 antibody). TOF-SIMS was used to assess the distribution of released strontium ions. Statistical analysis was done using SPSS software. Data was not found normally distributed and hence Mann-Whitney U with bonferroni correction was used. To avoid type I errors due to unequal variances and group sizes Games-Howell test was also performed


The Journal of Bone & Joint Surgery British Volume
Vol. 87-B, Issue 2 | Pages 261 - 266
1 Feb 2005
Földhazy Z Arndt A Milgrom C Finestone A Ekenman I

Strains applied to bone can stimulate its development and adaptation. High strains and rates of strain are thought to be osteogenic, but the specific dose response relationship is not known. In vivo human strain measurements have been performed in the tibia to try to identify optimal bone strengthening exercises for this bone, but no measurements have been performed in the distal radial metaphysis, the most frequent site of osteoporotic fractures. Using a strain gauged bone staple, in vivo dorsal metaphyseal radial strains and rates of strain were measured in ten female patients during activities of daily living, standard exercises and falls on extended hands. Push-ups and falling resulted in the largest compression strains (median 1345 to 3146 με, equivalent to a 0.1345% to 0.3146% length change) and falling exercises in the largest strain rates (18 582 to 45 954 με/s). On the basis of their high strain and/or strain rates these or variations of these exercises may be appropriate for distal radial metaphyseal bone strengthening


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_8 | Pages 67 - 67
1 Apr 2017
Ezzat A Iobst C
Full Access

Background. Plate fixation is one of several options available to surgeons for the management of pediatric femur fractures. Recent literature reports distal femoral valgus can be a complication following lateral plate fixation of femur fractures. We report on a case of extreme distal femoral valgus deformity and a lateral dislocation of the patella four years after having plate fixation of a left distal femoral fracture. Method. A single case was anonymised and retrospectively reviewed through examination of clinical and radiographic data. Results. A 15 year old male presented with 35 degree femoral valgus deformity, one inch leg length discrepancy, painful retained hardware and a lateral dislocation of the patella four years after undergoing lateral plate fixation of a left distal femur fracture. The fracture site healed after plate insertion, but later the patient reported worsening in alignment of lower extremity and complained of pain in the limb. Antero-posterior and lateral radiographs of the femur revealed 35 degrees of left distal femoral valgus. The previous femoral plate migrated proximally and was encased in bone. Due to plate migration, screws that were originally in the distal femoral metaphysis were protruding through the femoral shaft into soft tissues of the medial thigh. Successful treatment involved removal of prominent distal screws and use of a Taylor Spatial external fixator frame to correct the deformity. Lateral soft tissue release was performed to allow patellar relocation. At 12 weeks follow up leg alignment was restored, pain resolved and the patient was mobilising. Conclusion. Femoral valgus is a possible complication of lateral plate fixation in up to 30% of pediatric distal femur fractures. With this patient's combination of deformities as an example, we suggest early hardware removal after fracture union, preventing deformities developing. If plate removal is not chosen, then continued close monitoring of the patient is necessary until skeletal maturity. Level of Evidence. Type 4 (case report)


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_1 | Pages 30 - 30
1 Jan 2017
Pazzaglia U Congiu T Sibilia V Pagani F Benetti A Zarattini G
Full Access

The study of the chondrocyte maturation cycle and endochondral ossification showed that the developing vascular supply has appeared to play a key role in determining the cortical or trabecular structure of the long bones. The chondrocyte maturation cycle and endochondral ossification were studied in human, foetal cartilage anlagen and in postnatal meta-epiphyses. The relationship between the lacunar area, the inter territorial fibril network variations and CaP nucleation in primary and secondary ossification centres were assessed using light microscopy and SEM morphometry. The anlage topographic, zonal classification derived from the anatomical nomenclature of the completely developed long bone (diaphysis, metaphyses and epiphyses) allowed to follow the development of long bones cartilage model. A significant increase in chondrocyte lacunar area (p<0.001) was documented from the anlage epiphyseal zone 4 and 3 to zone 2 (metaphysis) and zone 1 (diaphysis), with the highest variation from zone 2 to zone 1. An inverse reduction in the intercellular matrix area (p<0.001) and matrix interfibrillar empty space (p<0.001) was also documented. These findings are consistent with the osmotic passage of free cartilage water from the interfibrillar space into the swelling chondrocytes, raising ion concentrations up to the critical threshold for mineral precipitation in the matrix. The mineralised cartilage served as a scaffold for osteoblasts apposition both in primary and secondary ossification centres and in the metaphyseal growth plate cartilage, but at different periods of bone anlage development and with distinct patterns for each zone. They all shared a common initial pathway, but it progressed with different times, modes and organisation in diaphysis, metaphysis and epiphysis. In the ossification phase the developing vascular supply has appeared to play a key role in determining the cortical or trabecular structure of the long bones


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XVIII | Pages 66 - 66
1 May 2012
Khan IH Nicol S Jackson M Monsell F Livingstone JA Atkins RM
Full Access

Lower limb mal-alignment due to deformity is a significant cause of early degenerative change and dysfunction. Standard techniques are available to determine the centre of rotation of angulation (CORA) and extent of the majority of deformities, however distal femoral deformity is difficult to assess because of the difference between anatomic and mechanical axes. We found the described technique involving constructing a line perpendicular to a line from the tip of the greater trochanter to the centre of the femoral head inaccurate, particularly if the trochanter is abnormal. We devised a novel technique which accurately determines the CORA and extent of distal femoral deformity, allowing accurate correction. Using standard leg alignment views of the normal femur, the distal femoral metaphysis and joint line are stylized as a block. A line bisecting the axis of the proximal femur is then extended distally to intersect the joint. The angle (Θ) between the joint and the proximal femoral axis and the position (p) where the extended proximal femoral axis intersects the joint line are calculated. These measurements can then be reproduced on the abnormal distal femur in order to calculate the CORA and extent of the deformity, permitting accurate correction. We examined the utility and reproducibility of the new method using 100 normal femora. Θ = 81 ± sd 2.5. As expected, Θ correlated with femoral length (r=0.74). P (expressed as the percentage of the distance from the lateral edge of the joint block to the intersection) = 61% ± sd 8%. P was not correlated with Θ. Intra-and inter-observer errors for these measurements are within acceptable limits and observations of 30-paired normal femora demonstrate similar values for Θ and p on the two sides. We have found this technique to be universally applicable and reliable in a variety of distal femoral deformities


The Journal of Bone & Joint Surgery British Volume
Vol. 80-B, Issue 4 | Pages 726 - 730
1 Jul 1998
Iwabu S Sasaki T Kameyama M Teruya T Horiuchi Y Yabe Y

We observed the healing process under rigid external fixation after Salter-Harris type-1 or type-2 physeal separation at the proximal tibia in immature rabbits. Metaphyseal vessels grew across the gap with little delay; the site of separation then came to lie in the metaphysis and was bridged by endochondral ossification. Union was achieved within two days in all rabbits. Progression of endochondral ossification repaired the separated physis, thus showing ‘primary healing of physeal separation’. This depends on accurate reduction and stable fixation to allow the survival of vessels across the gap


Orthopaedic Proceedings
Vol. 96-B, Issue SUPP_11 | Pages 196 - 196
1 Jul 2014
Lozano D López-Herrradón A Portal-Núñez S Ardura J Vila M Sánchez-Salced S Mulero F Gómez-Barrena E Vallet-Regí M Esbrit P
Full Access

Summary Statement. Parathytorid hormone-related protein (107–111) loaded onto biopolymer-coated nanocrystalline hydroxyapatite (HA. Glu. ) improves the bone repair in a cavitary defect in rat tibiae. Introduction. Biopolymer-coated nanocrystalline hydroxyapatite (HA. Glu. ) made as macroporous foams are promising candidates as scaffolds for bone tissue engineering applications. They exhibit optimal features, promoting internalization, proliferation and differentiation of osteoprogenitors, with an adequate cell colonization over the entire scaffold surface. Parathyroid hormone-related protein (PTHrP) is an important modulator of bone formation. Its 107–111 epitope (osteostatin) exhibits osteogenic properties at least in part by directly acting on osteoblasts. The main aim of this study was to evaluate whether osteostatin loading into HA. Glu. scaffolds might improve their bone regeneration capacity. Materials and Methods. HA. Glu. scaffolds were prepared as previously described (Sánchez-Salcedo S et al. J. Mater. Chem. 2010; 20:6956-61). Osteostatin was adsorbed onto HA. Glu. material by dipping into a solution containing this peptide at 100 nM (in phosphate-buffered saline, pH 7.4), following a standard protocol. We performed a cavitary defect (2 mm in diameter and 3 mm in depth) in both distal tibial metaphysis using a drill under general anesthesia in male Wistar rats (n=8) of 6 months of age. Unloaded HA. Glu. material (7 mg) was implanted into left tibial defects, whereas rigth tibial defects received the osteostatin-loaded material. Animals were sacrificed after 4 weeks for histological, μ-computerised tomography and gene expression analysis of the callus. Our protocol was approved by the Institutional Animal Care and Use Committee at the IIS-FJD. Mouse osteoblastic MC3T3-E1 cells were grown in differentiation medium (α-MEM with 10% fetal bovine serum, 50 µg/ml ascorbic acid, and 10 mM β-glycerolphosphate), in the presence or absence of HA. Glu. material with or without osteostatin. Cell viability (assessed by trypan blue staining), alkaline phosphatase (ALP) activity and mineralization (alizarin red) were analyzed at different culture times. Results. The mean uptake of osteostatin by HA. Glu. scaffolds was about 60 % (representing 0.7 μg/implanted scaffold) after 24 h of loading, and they released a mean of 80 % of loaded peptide to the surrounding medium within 1–24 h. At 4 weeks, this osteostatin-containing HA. Glu. material significantly increased the bone volumen fraction and trabecular thickness of regenerating bone in the tibial methaphysis, compared to those observed with unloaded HAGlu scaffolds. In addition, osteostatin-coated HA. Glu. scaffolds increased (2-fold) the gene expression of osteocalcin and vascular cell adhesion molecule 1, but decreased (2-fold) that of the Wnt inhibitors, SOST and Dickkopf homolog 1 (DKK-1) in the fracture callus. In MC3T3-E1 cell cultures, osteostatin-loaded HA. Glu. material increased cell viability and ALP activity (each by 30%), and matrix mineralization (by 50%) at days 4 and 10, respectively. Conclusions. These results indicate that osteostatin loading improves the bone regeneration capacity of HA. Glu. scaffolds. Our findings suggest that these scaffolds might be promising implants in orthopaedic applications. This work has been supported by a grant from Comunidad Autónoma de Madrid (S-2009/MAT/1472)


The Journal of Bone & Joint Surgery British Volume
Vol. 83-B, Issue 6 | Pages 921 - 929
1 Aug 2001
Aamodt A Lund-Larsen J Eine J Andersen E Benum P Husby OS

We have compared the changes in the pattern of the principal strains in the proximal femur after insertion of eight uncemented anatomical stems and eight customised stems in human cadaver femora. During testing we aimed to reproduce the physiological loads on the proximal femur and to simulate single-leg stance and stair-climbing. The strains in the intact femora were measured and there were no significant differences in principal tensile and compressive strains in the left and right femora of each pair. The two types of femoral stem were then inserted randomly into the left or right femora and the cortical strains were again measured. Both induced significant stress shielding in the proximal part of the metaphysis, but the deviation from the physiological strains was most pronounced after insertion of the anatomical stems. The principal compressive strain at the calcar was reduced by 90% for the anatomical stems and 67% for the customised stems. Medially, at the level of the lesser trochanter, the corresponding figures were 59% and 21%. The anatomical stems induced more stress concentration on the anterior aspect of the femur than did the customised stems. They also increased the hoop strains in the proximomedial femur. Our study shows a consistently more physiological pattern of strain in the proximal femur after insertion of customised stems compared with standard, anatomical stems


The Journal of Bone & Joint Surgery British Volume
Vol. 82-B, Issue 1 | Pages 138 - 141
1 Jan 2000
Skripitz R Andreassen TT Aspenberg P

Intermittent treatment with parathyroid hormone (PTH) has an anabolic effect on both intact cancellous and cortical bone. Very little is known about the effect of the administration of PTH on the healing of fractures or the incorporation of orthopaedic implants. We have investigated the spontaneous ingrowth of callus and the formation of bone in a titanium chamber implanted at the medioproximal aspect of the tibial metaphysis of the rat. Four groups of ten male rats weighing approximately 350 g were injected with human PTH (1-34) in a dosage of 0, 15, 60 or 240 μg/kg/day, respectively, for 42 days from the day of implantation of the chamber. During the observation period the chamber became only partly filled with callus and bone and no difference in ingrowth distance into the chamber was found between the groups. The cancellous density was increased by 90%, 132% and 173% in the groups given PTH in a dosage of 15, 60 or 240 μg/kg/day, respectively. There was a linear correlation between bone density and the log PTH doses (r. 2. = 0.6). Our findings suggest that treatment with PTH may have a potential for enhancement of the incorporation of orthopaedic implants as well as a beneficial effect on the healing of fractures when it is given in low dosages


The Journal of Bone & Joint Surgery British Volume
Vol. 83-B, Issue 2 | Pages 295 - 301
1 Mar 2001
Kim Y Kim J Cho S

Six pairs of human cadaver femora were divided equally into two groups one of which received a non-cemented reference implant and the other a very short non-dependent experimental implant. Thirteen strain-gauge rosettes were attached to the external surface of each specimen and, during application of combined axial and torsional loads to the femoral head, the strains in both groups were measured. After the insertion of a non-cemented femoral component, the normal pattern of a progressive proximal-to-distal increase in strains was similar to that in the intact femur and the strain was maximum near the tip of the prosthesis. On the medial and lateral aspects of the proximal femur, the strains were greatly reduced after implantation of both types of implant. The pattern and magnitude of the strains, however, were closer to those in the intact femur after insertion of the experimental stem than in the reference stem. On the anterior and posterior aspects of the femur, implantation of both types of stem led to increased principal strains E1, E2 and E3. This was most pronounced for the experimental stem. Our findings suggest that the experimental stem, which has a more anatomical proximal fit without having a distal stem and cortex contact, can provide immediate postoperative stability. Pure proximal loading by the experimental stem in the metaphysis, reduction of excessive bending stiffness of the stem by tapering and the absence of contact between the stem and the distal cortex may reduce stress shielding, bone resorption and thigh pain


Bone & Joint Research
Vol. 4, Issue 10 | Pages 170 - 175
1 Oct 2015
Sandberg OH Aspenberg P

Objectives

Healing in cancellous metaphyseal bone might be different from midshaft fracture healing due to different access to mesenchymal stem cells, and because metaphyseal bone often heals without a cartilaginous phase. Inflammation plays an important role in the healing of a shaft fracture, but if metaphyseal injury is different, it is important to clarify if the role of inflammation is also different. The biology of fracture healing is also influenced by the degree of mechanical stability. It is unclear if inflammation interacts with stability-related factors.

Methods

We investigated the role of inflammation in three different models: a metaphyseal screw pull-out, a shaft fracture with unstable nailing (IM-nail) and a stable external fixation (ExFix) model. For each, half of the animals received dexamethasone to reduce inflammation, and half received control injections. Mechanical and morphometric evaluation was used.


Bone & Joint Research
Vol. 3, Issue 7 | Pages 230 - 235
1 Jul 2014
van der Jagt OP van der Linden JC Waarsing JH Verhaar JAN Weinans H

Objectives

Electromagnetic fields (EMF) are widely used in musculoskeletal disorders. There are indications that EMF might also be effective in the treatment of osteoporosis. To justify clinical follow-up experiments, we examined the effects of EMF on bone micro-architectural changes in osteoporotic and healthy rats. Moreover, we tested the effects of EMF on fracture healing.

Methods

EMF (20 Gauss) was examined in rats (aged 20 weeks), which underwent an ovariectomy (OVX; n = 8) or sham-ovariectomy (sham-OVX; n = 8). As a putative positive control, all rats received bilateral fibular osteotomies to examine the effects on fracture healing. Treatment was applied to one proximal lower leg (three hours a day, five days a week); the lower leg was not treated and served as a control. Bone architectural changes of the proximal tibia and bone formation around the osteotomy were evaluated using in vivo microCT scans at start of treatment and after three and six weeks.


Bone & Joint Research
Vol. 3, Issue 11 | Pages 310 - 316
1 Nov 2014
Tomaszewski R Bohosiewicz J Gap A Bursig H Wysocka A

Objectives

The aim of this experimental study on New Zealand’s white rabbits was to investigate the transplantation of autogenous growth plate cells in order to treat the injured growth plate. They were assessed in terms of measurements of radiological tibial varus and histological characteristics.

Methods

An experimental model of plate growth medial partial resection of the tibia in 14 New Zealand white rabbits was created. During this surgical procedure the plate growth cells were collected and cultured. While the second surgery was being performed, the autologous cultured growth plate cells were grafted at the right tibia, whereas the left tibia was used as a control group.