Lubna Khaldi

Mechanical Stimulation in the Form of Vibration Prevents Postmenopausal Bone Loss in Ovariectomized Rats

Abstract. Physical exercise is recommended for the prevention and treatment of osteoporosis. However, its exact role and effectiveness in adulthood is unclear. While vigorous exercise of long duration enhances bone density, few adult individuals comply with such training programs. The present study evaluates the influence of nonphysiological mechanical stimulation, in the form of low intensity vibration (frequency: 50 Hz, acceleration: 2 g, 30 min/day for 5 days/week), on the prevention of bone loss in an animal model of postmenopausal osteoporosis. In the ovariectomised groups of rats a statistically significant (p < 0.05) decrease of bone density (femur and tibia) was recorded at 5 weeks postovariectomy. This effect was maintained for the 12 week duration of the study. Vibration prevented early bone loss after ovariectomy. Vibrated ovariectomised rats showed statistically significantly higher (p < 0.05) BMD values compared to those of their ovariectomised controls at 5 weeks. Vibration did not influence the bone density of the SHAM-operated rats. Although vibration increased ultimate strength (fracture load of the rat femur) in the ovariectomised rats, this finding was not statistically significant. Our data indicate that this method of safe and easily applicable vibration, in the form of a vibrating platform, is effective in preventing early postovariectomy bone loss in an animal model.

Subchondral cyst development and MMP-1 expression during progression of osteoarthritis: An immunohistochemical study

BACKGROUND Subchondral bone cyst (SBC) formation is often identified in patients with osteoarthritis. Furthermore, several studies have shown that expression of matrix metalloproteinases (MMPs) is elevated in patients with OA. OBJECTIVES The aim of our study is to correlate the presence of SBCs and MMP-1 expression with the osteochondral alterations during OA progression. METHODS We studied the cartilage and subchondral bone of 15 patients who had undergone total knee or hip replacement due to primary OA. As controls, we used the femoral heads of three patients without macroscopic OA changes. We evaluated three specimens per patient. RESULTS Specimens were divided in four groups based on the Mankin histological severity score. Using immunohistochemistry, we noted SBCs at the site of greatest disease severity. Specifically, these were present more frequently in group III (Mankin score: 6-7) and IV (Mankin: ≥ 8), compared with group I (Mankin: 1-3) and II (Mankin: 4-5). Mild OA stages (Mankin: 1-6) were characterized by degeneration and thinning of the cartilage, followed by increased osteoblast and osteoclast activity of the subjacent bone and the subsequent appearance of SBCs. Simultaneously, we observed expression of MMP-1 in groups I and II in the cartilage and III and IV in both the cartilage and the subchondral bone. Moreover, osteoblast-like cells in the lining of the SBCs showed an increased expression of MMP-1 in stages III and IV. CONCLUSION Our study provides immunohistological evidence that SBCs accumulate in advanced OA and contain activated cells, which express MMP-1, suggesting that they may thus participate in the osteochondral changes of OA. LEVEL OF EVIDENCE Level III; prospective comparative study.

Effect of autologous platelet-rich plasma in combination with a biphasic synthetic graft material on bone healing in critical-size cranial defects.

Purpose The aim of the study was to investigate the effect of autologous platelet-rich plasma (PRP) on the osteogenic potential of a biphasic synthetic graft material composed of hydroxyapatite and beta-tricalcium phosphate (HA/&bgr;-TCP) in critical-size cranial defects in rabbits. Materials and Methods Three circular bicortical critical-size cranial defects were created in each of 18 rabbits. The first of the defects was grafted with autologous PRP and HA/&bgr;-TCP, the second was grafted with HA/&bgr;-TCP without PRP, and the third was left unfilled as a negative control. Animals were euthanized at 2, 4, and 6 weeks after surgery. Harvested tissue specimens were evaluated histologically and histomorphometrically. Several parameters associated with osteoclastic and osteoblastic activities were measured and calculated. The results were statistically analyzed using the 1-way analysis of variance statistical method. Results Histologic analysis of the samples showed bone tissue formation at all experimental sites including untreated control defects. A statistically significant difference in new bone formation between the defects treated with HA/&bgr;-TCP + PRP and defects treated with HA/&bgr;-TCP alone was not observed. Control untreated defects showed the greatest bone regeneration. Conclusions In this animal model, autologous PRP had no effect on bone healing in addition to a biphasic HA/&bgr;-TCP synthetic graft material after 2, 4, and 6 weeks of implantation.

Unusual presentation of osteoid osteoma of the scaphoid

The small carpal bones are infrequent sites for osteoid osteomas, and their clinical and imaging pictures may be quite confusing leading to suspect other etiologies. The authors present herein an unusual case of osteoid osteoma of the scaphoid superimposed on a wrist injury caused by a fall on the outstretched hand.

Chondroprotective effect of high‐dose zoledronic acid: An experimental study in a rabbit model of osteoarthritis

To address the need to impact the subchondral bone‐articular cartilage interaction for the treatment of degenerative osteoarthritis (OA), bisphosphonates may be used as a means to inhibit the subchondral bone resorption. The purpose of the present study is to evaluate the chondroprotective effect of zoledronic acid (ZOL) in a model of OA. Eighteen adult male rabbits underwent an anterior cruciate ligament transection and were separated into two groups: ZOL group (n = 10) received 0.6 mg/kg intravenous injection of ZOL on day 1, 15, and 29 and placebo group (n = 8) received saline. The animals were euthanized at 8 weeks. Macroscopically, the ZOL group had significantly milder ulcerations, cartilage softening and fibrillation compared to the placebo group. Microscopically, morphology of the articular cartilage was better in the ZOL treated group compared with the placebo group, without complete disorganization in any section of the ZOL group. Furthermore, the chondrocytes in the ZOL treated group were mainly cloning, indicating cartilage repairing and regeneration process, while in the placebo group hypocellularity predominated. Additionally, subchondral necrosis was evident in some specimens of the placebo group. Zoledronic acid, in a high‐dose regimen, proved to be chondroprotective in a well‐established animal model of OA.

Expression of matrix metalloproteinase-1 (MMP-1) in Wistar rat's intervertebral disc after experimentally induced scoliotic deformity.

IntroductionA scoliotic deformity on intervertebral discs may accelerate degeneration at a molecular level with the production of metalloproteinases (MMPs). In the present experimental study we evaluated the presence of MMP-1 immunohistochemically after application of asymmetric forces in a rat intervertebral disc and the impact of the degree of the deformity on MMP-1 expression.Material-MethodThirty female Wistar rats (aged 2 months old, weighted 200 ± 10 grams) were used. All animals were age, weight and height matched. A mini Ilizarov external fixator was applied at the base of a rat tail under anaesthesia in order to create a scoliotic deformity of the intervertebral disc between the 9th and 10th vertebrae. Rats were divided into three groups according to the degree of the deformity. In group I, the deformity was 10°, in group II 30° and in group III 50°. The rats were killed 35 days after surgery. The discs were removed along with the neighbouring vertebral bodies, prepared histologically and stained immunohistochemically. Immunopositivity of discs cells for MMP-1 was determined using a semi-quantitative scored system.ResultsMMP-1 immunopositivity was detected in disc cells of annulus fibrosus of all intervertebral disc specimens examined. The percentage of MMP-1 positive disc cells in annulus fibrosus in group I, II and III were 20%, 43% and 75%, respectively. MMP-1 positivity was significantly correlated with the degree of the deformity (p < 0,001). An increase of chondrocyte-like disc cells was observed in the outer annulus fibrosus and at the margin of the intervertebral disc adjacent to the vertebral end plates. The difference in the proportion of MMP-1 positive disc cells between the convex and the concave side was statistically not significant in group I (p = 0,6), in group II this difference was statistically significant (p < 0,01). In group III the concave side showed a remarkable reduction in the number of discs cells and a severe degeneration of matrix microstructure.ConclusionThe present study showed that an experimentally induced scoliotic deformity on a rat tail intervertebral disc results in over-expression of MMP-1, which is dependent on the degree of the deformity and follows a dissimilar distribution between the convex and the concave side.

Reconstruction of anterior cruciate ligament using the doubled tendon graft technique: an experimental study in rabbits

Abstract In an attempt to assess reconstruction of the anterior cruciate ligament (ACL) by a new method, 18 New Zealand white rabbits underwent ACL replacement using the medial one-third of the patellar tendon and the semitendinosus tendon, thus partly reproducing the anatomical configuration of the ACL, with the semitendinosus tendon replacing the posterolateral bundle of the ACL and the patellar tendon replacing the anteromedial bundle. The Noulis-Trillat-Lachman test was performed before and after transection of the ACL, after reconstruction and before sacrifice. The animals were divided into four groups and were killed at 3, 6, 12 and 22 weeks after surgery. Femur-ligament-tibia complexes were evaluated postoperatively for gross morphology and histological appearance. The tendons of the first group showed compact parallel fibres with no definitive separation of their bundles and areas of disorganized collagen matrix. Tendons were surrounded by trabecular lamellar bone haphazardly arranged. The tendons of the second, third and fourth groups looked more like normal tendon. The trabecular bone surrounding the tendons formed a tunnel. The Noulis-Trillat-Lachman test result was negative before the procedure, 6.5±0.5 mm on average after transection of the ACL, 1.5±0.6 mm after the procedure, and negative again before sacrifice. The joints of the animals killed at 12 and 22 weeks showed signs of osteoarthritic lesions.

Expression of the growth factor pleiotrophin and its receptor protein tyrosine phosphatase beta/zeta in the serum, cartilage and subchondral bone of patients with osteoarthritis

OBJECTIVES Pleiotrophin is a heparin-binding growth factor expressed in embryonic but not mature cartilage, suggesting a role in cartilage development. Elucidation of the molecular changes observed during the remodelling process in osteoarthritis is of paramount importance. This study aimed to investigate serum pleiotrophin levels and expression of pleiotrophin and its receptor protein tyrosine phosphatase beta/zeta in the cartilage and subchondral bone of osteoarthritis patients. METHODS Serum samples derived from 16 osteoarthritis patients and 18 healthy donors. Pleiotrophin and receptor protein tyrosine phosphatase beta/zeta in the cartilage and subchondral bone were studied in 29 patients who had undergone total knee or hip replacement for primary osteoarthritis and in 10 control patients without macroscopic osteoarthritis changes. RESULTS Serum pleiotrophin levels and expression of pleiotrophin in chondrocytes and subchondral bone osteocytes significantly increased in osteoarthritis patients graded Ahlback II to III. Receptor protein tyrosine phosphatase beta/zeta was mainly detected in the subchondral bone osteocytes of patients with moderate osteoarthritis and as disease severity increased, in the osteocytes and bone lining cells of the distant trabeculae. CONCLUSIONS These data render pleiotrophin and receptor protein tyrosine phosphatase beta/zeta promising candidates for further studies towards developing targeted therapeutic schemes for osteoarthritis.

Biological response to β-tricalcium phosphate/calcium sulfate synthetic graft material: an experimental study.

Purpose:The aim of this study was to evaluate the effect of a biphasic synthetic bone graft material composed of &bgr;-tricalcium phosphate (&bgr;-TCP) and calcium sulfate (CS) in 12 New Zealand rabbits. Materials and Methods:A circular bicortical critical-size cranial defect was created in each of 12 rabbits. The defects were grafted with &bgr;-TCP/CS. Animals were euthanized at 3 and 6 weeks. Harvested tissue specimens were evaluated histologically and histomorphometrically. Parameters associated with new bone formation and graft resorption were measured and calculated. The results were statistically analyzed using the Mann-Whitney test. Results:Our data demonstrated the biocompatibility of synthetic &bgr;-TCP/CS, as no inflammatory response was observed, and no fibrosis was developed between the graft particles and the newly formed bone. Moreover, &bgr;-TCP/CS acted as an osteoconductive scaffold that allowed a significant bone regeneration and graft biodegradation with time. Conclusion:In this animal model, synthetic &bgr;-TCP/CS proved to be a biocompatible, osteoconductive, and bioresorbable bone graft substitute.

Macrophage-specific metalloelastase (MMP-12) immunoexpression in the osteochondral unit in osteoarthritis correlates with BMI and disease severity

BACKGROUND Metalloproteinase 12 (MMP-12) is induced in chondrocytes during fetal development and malignant transformation. OBJECTIVES The aim of our study is to examine the expression of MMP-12 in the cartilage and the subchondral bone of patients with osteoarthritis (OA) and to correlate its expression with disease severity and anthropometric characteristics. METHODS Overall, 60 sections from 20 patients with idiopathic OA, were examined for the immunolocalization of MMP-12. As controls, we used the femoral heads of 4 patients treated with seniarthroplasty after fracture. Demographic characteristics and Body Mass Index (BMI) were calculated for all subjects. RESULTS Specimens were divided into four groups based on the Mankin histological severity score. The immunohistochemical study showed MMP-12 expression in the cartilage and subchonral bone of OA patients, while there was no expression in normal controls. At the moderate OA changes (Mankin score: 6-7), MMP-12 was detected mainly at the matrix of fibrocartilage tissue. During disease progression, MMP-12 was expressed at the sides of the cartilage and bone erosion and in the bone cysts. Furthermore, it was traced in the osteocytes of the subchondral bone. Osteoblast-like cells and bone lining cells express MMP-12 during the stage of severe OA (Mankin: ≥8). Osteoclasts expressing MMP-12 were also detected in the group of severe OA. Interestingly, MMP-12 expression was positively correlated with the age and the BMI of OA patients. CONCLUSION The increased expression of MMP-12 in the bone-cartilage unit of OA patients suggests a possible role in OA pathogenesis and progression. LEVEL OF EVIDENCE III, prospective comparative study.