Biomechanical Comparison of Headless Compression Screws, Kirschner Wires and Bioabsorbable Pins in Distal Oblique Metatarsal Osteotomy for Correction of Hallux Valgus.

BACKGROUND: Distal osteotomy of the first metatarsal is a widely used method for the correction of mild-to-moderate hallux valgus deformities. The objective of this study was to compare the stability of headless compression screws, kirschner wires and absorbable pins in terms of stiffness and maximum load in distal oblique metatarsal osteotomy. METHODS: A total of 30 4th generation first metatarsal synthetic bone models were divided into three groups according to the fixation techniques. The stiffness of the first metatarsal was calculated as the slope of the linear curve that fit with the first linear part of the force displacement curve. The failure strength was recorded as the maximum load. The stiffness and maximum load values in the axillary and transverse configurations were compared between the three fixation groups. RESULTS: The stiffness was statistically higher in Group K and Group C compared to Group B in both axial and transverse loading. Similarly, the maximum load was significantly higher in both Group K and Group C compared to Group B in both loading conditions. No significant difference was found between Group K and Group C in stability. The higher failure strength was obtained with headless compression screws (113.34±35.88 N) in the axial loading. The lowest failure strength was found in the absorbable pins technique (16.17±7.72 N) in the transverse loading. CONCLUSION: No significant difference was found between the Kirschner wires and headless compression screws techniques, although the highest strength was obtained with headless compression screws that are increasingly used in orthopedic practice.

Effects of Stellate Ganglion Block on Healing of Fractures Induced in Rats.

OBJECTIVE: Sympathetic blocks are used as an adjunct for pain management in the treatment of orthopedic and traumatic conditions. Stellate ganglion (ganglion stellatum) provides sympathetic innervation of the head, neck and cervicothoracic regions, and upper extremities. No study was found in the literature investigating the effects of stellate ganglion block performed in the upper extremity, on blood supply to bone, density, vascularization, and bone metabolism. Therefore, the objective of this study was to investigate the effects of stellate ganglion block on healing of closed forearm fractures that were induced in rats. Material and Methods. A total of 42 Wistar albino rats weighing between 398 and 510 g were used in this study. The rats were randomly divided into 2 groups with one group treated with stellate ganglion and the other included as the control group. In each 2 groups, a closed forearm fracture was created, confirmed with X-ray, and then stabilized by splint application. The forearm bones were examined with X-ray views on the same day and were then decalcified. RESULTS: When histological findings of the fracture region were examined, predominantly cartilage and less woven bone were found in 7 rats, equally distributed cartilage and immature bone in 14 rats, and predominantly imitation bone and less cartilage formation in 21 rats. In the control group, the agreement between the 1st and 2nd orthopedists for the radiological evaluation of bone formation was moderate. CONCLUSION: The group administered stellate ganglion block showed a more significant fracture healing.

The effect of pentoxifylline on Achilles tendon healing in tenotomized rabbits.

OBJECTIVES: This study aims to evaluate the potential effects of pentoxifylline (PTX) on tendon healing and to compare the histopathological and biomechanical findings of the healed tendon among the groups. MATERIALS AND METHODS: The study was conducted on 36 male New Zealand albino rabbits (age, 3 months; weighing, 2.5±0.5 kg). Rabbits were randomized into two groups of 18 rabbits each. Partial Achilles tenotomy was performed 1.5 cm proximally from the calcaneal insertion of the tendon in both lower extremities of each rabbit and all groups were repaired primarily. After the operation, saline was injected intramuscularly to the control group and PTX was injected into the PTX group daily. Nine rabbits from each group were euthanized at weeks four and six postoperatively for histopathological (n=4) and biomechanical (n=5) testing. The histopathological findings were evaluated using the staging method of Curtis and Delee. Biomechanical effects were assessed by tensile testing. RESULTS: In the biomechanical evaluation results, the maximum displacement and maximum breaking force in the PTX group at fourth week were significantly higher than the control group. In the sixth week, the maximum breaking force in the control group was significantly higher than the PTX group. In the histopathological examination, collagen fiber alignment was more regular and vascularization was more frequent in the PTX group at both fourth and sixth weeks and the difference was significant. CONCLUSION: Pentoxifylline increased healing and strength in rabbit Achilles tendon by stimulating collagen synthesis, increasing vascularity and reducing inflammation, particularly in the early period both histopathologically and biomechanically. According to our study, PTX may be favorable for the treatment of human Achilles tendon injuries and tendinopathies.

Biomechanical comparison of a new handy tension band with malleolar screw, bicortical screw and conventional tension band for the fixation of transverse medial malleolar fractures.

OBJECTIVES: This study aims to compare the biomechanical features of a new handy tension band with the malleolar screw, bicortical screw and conventional tension band for the fixation of transverse medial malleolar fractures. MATERIALS AND METHODS: This study used 20 Kirschner wires, five cerclage wires, six double-hole U pins, six cortical screws, six malleolar screws, three malleolar clamps and one osteotomy set. A total of 24 tibias of two-year-old cows were obtained and stripped from soft tissue. Each tibia was cut with an electric saw at 15 cm proximal to the tibiotalar joint surface and the proximal tibia sections were discarded. A transverse fracture line was created with an osteotome on the medial malleolus. The tibias were separated into four groups with six tibias in each group. The distal tibia medial malleolar transverse fragments were fixed under guidance of fluoroscopy with the malleolar screw, bicortical screw, conventional tension band and the new handy tension band. RESULTS: In the application of both transverse and axial force, the new handy tension band resisted higher forces in respect of catastrophic damage force being more resistant compared to the bicortical screw, malleolar screw, and conventional tension band. However, in respect of the 2 mm displacement force of the forces applied in the axial and transverse sections, no difference was determined between the handy tension band and the other three implants. CONCLUSION: The new handy tension band seems to be more successful when biomechanically compared with the other implants.