Aim: To evaluate long term effects of stress shieldieng phenomenon after cementless total hip arthroplasty. Materials-Methods: 80 female pts with OA were randomly allocated in 4 groups according to the type of the cementless stem which was primarily implanted (A-Zwey-Muller,B-Corail,C- Optifix,DAutophor900S). BMD changes of the operated hip (in seven zones), of the operated, contralateral normal hip and of the Lumbar spine were measured pre-op, at 2, 8 and 12 months and every year thereafter. Results: At ten years, 72 pts were available for follow up, all with satisfactory clinical and radiological results with no evidence of polyethylene wear or endosteal lysis. In all groups, the greatest reduction of BMD (calcar atrophyzone 7) was observed at the 2nd post-op year (A:24%, B:8%, C:14.8%, D:18.5%). In all groups, the greatest increase (zone 4) of BMD was also observed at the 2nd post-op year (A7%, B2%, C2.5%, D6.3%). In all groups a similar pattern of slow but progressive recovery of bone mineral density changes after the 3rd year was observed in both zones, approaching baseline values at 10 years in all groups. Preoperative lumbar BMD (osteopenia), body weight, sex and height were not statisticaly correlated to calcar atrophy. Conclusions:We suggest that the clinical and theoretical relevance of stress shielding phenomenon in total hip replacement has been overestimated in the literature

Aims: To determine the effect of fracture and immobilization on bone mineral density and mechanical parameters in postemenopausal women with a distal radius fracture. Methods: Seventeen postmenopausal women with a distal radius fracture with an indication for conservative treatment were included in the study. pQCT measurements of the fractured forearm were performed 2–3 days after the fracture, at 10 days after the fracture and at cast removal (35–45 days). All measurements were performed at a 10mm, 20mm and 40mm distance from a reference line set at the most proximal part of the distal radioulnar joint. Cortical, trabecular and total density and SSIx, SSIy and SSIpolar parameters were assessed. Results: At the fractured forearm, a high statistically signiþcant decrease of cortical density was observed only between second measurement and cast removal at 10 and 20mm (p< 0.01) Total density was not signiþcantly altered and trabecular density at 10mm was signiþcantly increased at cast removal compared to values at the time of the fracture (p< 0.01). Subcortical bone density at 10mm was also signiþcantly decreased at cast removal (p< 0.01). At cast removal, SSIx and SSI-polar parameters of the fractured forearm were also statistically signiþcantly decreased at distances of 10 and 20mm (p< 0.05). Conclusions: Distal radius fractures in postmenopausal women treated conservatively lead to a decrease of cortical density and an increase of trabecular density near the fracture site. They also aggravate bending and torsional mechanical properties. The shift from cortical bone to trabecular bone seems to be time-dependent and is signiþcant at cast removal.

Aim. The purpose of this study was to examine the symmetry of the mechanical and tomographic properties of the rat femur and tibia, frequently used in biomedical research.

Materials-Methods. For this purpose both femora and tibiae of 43 Wistar rats underwent tomographic (pQCT) evaluation while both femora and tibiae of 40 further Wistar rats were subjected to destructive three-point bending testing. The age of the animals ranged between 3 and 12 months and all were males.

Results. While there was significant variation between the structural and the biomechanical properties between different animals the differences between the femora and the tibiae of the same animal were not statistically significantly different in the majority of animals.

Conclusion. We conclude that in healthy, sexually mature Wistar rats, in the first year of their life, there is no significant diversity in terms of tomographic and biomechanical properties of their opposing posterior limb long bones.

Aim. We evaluated the effect of the intact periosteum on the biomechanical properties of the rat long bones. Materials-Methods. The biomechanical properties of both femora and tibiae of 30 male, 4-month old Wistar rats have been evaluated in three-point bending testing. In one bone of each pair of femora or tibiae the periosteum was preserved intact, while in the contra-lateral bone the periosteum was stripped off. Ultimate strength,stiffness,energy absorption and deflection were derived automatically from the load-deformation curve recorded for each bone.

Results. As regards the femur, the periosteum-covered bones displayed statistically significant higher values for all parameters measured compared to the periosteum-stripped bones. In the tibia, only energy absorption and deflection were significantly higher in the periosteum-covered bones. The fracture pattern was also different in these two groups. The periosteum-stripped femora and tibiae failed catastrophically, while in the periosteum-covered bones the two bone parts remained in close apposition stabilized by the periosteal membrane.

Conclusion. The periosteum exacerbates the biomechanical capacity of intact rat long bones examined in bending, probably taking advantage of its fibrous composition and elastic properties.

Purpose: The study was conducted to evaluate the effect of salmon calcitonin (sCT) on fracture healing in normal and hypogonadal male rats.

Material and Method: Fifty six male Wistar rats, aged 3 months, were undertaken hemiosteotomy of the distal femur shaft, of standard length and width. Half of the animals had been orchiectomised at the age of 2 months. The animals were divided in 8 groups, 7 rats each, as follow: A, a (normal, no sCT), B, b (normal+Sct), C,c(orchiectomised) and D,d (orchiectomised+Sct). Salmon calcitonin was administered immediately after the hemiosteotomy in a dose of 5IU/day subcutaneously. Groups A, a, C and c were given placebo. The animals of the groups a b, c, and d were killed at 2 weeks, while the animals of the groups A, B, C, and D were killed at 4 weeks. After the euthanasia, total bone density and cortical bone density of the callus was estimated by peripheral quantitative computed tomography (pQCT). Histological and histomorfometric parameters of the callus were estimated as well.

Results: The mean cortical bone density was 1221.93±13.82 (g/cm³±SE) for the group a, 1281.3±13.57 for b, 1221.41±18.24 for c, 1245±17.12 for d, 1173.45±34.14 for A, 1298.9±11 for B, 1280.78±13.68 for C, and 1279.4U19.2 for D. The mean total bone density was 843.95±13.69 (g/cm³±SE) for the group a, 859.84±26.46 for b, 892.27±25.3 fore, 861.37±10.88 for d, 818.97±32.5 for A, 926.39±19.6 for B, 888.31±24.19 for C, and 912.75±28.13 for D. Values of cortical bone density in group b and B were significantly greater than a and A, respectively (b> a, p=0.01 and B> A, p=0.002). Total bone density of the callus was statistically greater in group B than A (B> A, p=0.01). According to the histological and histomorphometric results, sCT increased the amount of cartilage (p=0.014) and the amount of woven bone (p=0.015) in group b compared to a, while osteoblasts number showed no difference between the two groups. Comparing groups c and d, sCT increased the amount of cartilage (p=0.036) and the amount of woven bone (p=0.0014) in group d compared to c, while decreased osteoblasts number in group d (p=0.03). In four weeks the amount of cartilage is significant greater in group D versus C (p=0.006), as well as the amount of woven bone (p=0.0004). The size of the callus is significant greater in group D compared to C as well (p=0.052).

Conclusion: It appears that salmon calcitonin administration improves significantly the parameters of callus bone density in normal rats and increases the amount of cartilaginous callus and woven bone both in normal and orchiectomised rats.

Achilles tendinitis can result, through inflammatory procedures, to tendon degeneration with microtears and nodules. Current conservative or surgical treatment of this lesion proved to be not effective enough. The reason for this is the absence of sufficient oxygenation in the area. In this study we report the results of a novel technique which tries to improve local vascularity.

We operated on 15 mature rabbits after they were anasthetized. Soleus fibers were trasplanted in the right achilles tendon. A lesion, 10mm long and 2mm wide was created in the inner band of the tendon simulating tendinitis. In the left achilles tendon the same procedure was done without transplantation. The rabbits were divided in three equal groups and were sacrificed in the first week, the 2nd and 3rd month after the operation. Histopathologic examination was done in both achilles tendons. The following parameters were assessed: transplanted muscle viability, inflammation and neoangiogenesis. We also evaluated the contact between muscle and tendon and the quality of tissue that was formed in the tendinitis simulating area.

Inflammatory process was noticed only in the 1st week after surgery. In the other groups viable muscle fibers and tendon tissue was observed. Muscle fibers were in contact with the tendon. The quality of tissue in the tendinitis simulating area was of better quality than in the control group.

We conclude that soleus transplanted muscle fibers in the rabbits achilles tendon seem to be oxygen carriers and improve the healing potential of the area. This fact results in tendon reinforcement.

Purpose: The efficacy of nasal salmon calcitonin (CT) in preventing bone loss after a hip fracture and in reducing the incidence of further contralateral hip fractures was evaluated.

Material and Methods: Fifty women aged 70–80 years who sustained a pertrochanteric fracture were randomly allocated to Group A (200 IU of nasal salmon calcitonin daily for three months) and Group B (placebo). Biochemical bone markers (1st, 7th, 15th, 45th and 90th day post injury) and bone mineral density of the lumbar spine and the intact contralateral hip (4th and 90th postoperative day, and one year after the fracture) were measured.

Results: Patients in the calcitonin group showed statistically significantly higher total (p< 0,005) and bone alkaline phosphatase (p< 0,002) and osteocalcin (p< 0, 05) levels on the 15th day, while statistically significantly lower uCTX values on the 15th (p< 0,045), 45th (p< 0,002) and 90th (p< 0,002) day and uHpr/Cr values on the 15th (p< 0,015) and on the 45th (p< 0.05) day post injury. In the placebo group patients showed a statistically significant reduction (all p values < 0.05) of bone density values at 3 months and one-year post surgery while in the calcitonin group no significant changes from baseline. When the two groups were compared, patients in the calcitonin group showed statistically significantly higher bone mineral density values (all p values < 0.05), in all recorded sites, at 3 months and one-year post operatively. After a four years clinical follow-up, five patients (5/25, 20%) sustained a new fracture of the contralateral hip in the placebo group.

Conclusion: Nasal salmon calcitonin prevented early bone loss in these patients and may have a protective role on the occurrence of a new fracture of the contralateral hip in the same patient.