Optimum Screw Configuration for the Fixation of Sanders Type IIC Tongue-Type Fractures? A Biomechanical Study.

BACKGROUND: The minimally invasive technique (percutaneous screw fixation) is one of the options for treating tongue-type IIC fractures successfully. The aim of this study was to assess the biomechanics of four different screw configurations used for the fixation of tongue-type IIC calcaneal fractures. METHODS: Identical osteotomies, recapitulating a type IIC injury, were created in synthetic calcaneus specimens using a saw. The specimens were randomly assigned to one of the four fixation groups (n = 7 per group): two divergent screws, two parallel screws, two parallel screws plus one screw axially oriented toward the sustentaculum tali, and three parallel screws. A load test was performed on all of the groups, and the specimens were then tested using offset axial loading until 2, 4, and 5 mm of fracture displacement occurred. RESULTS: Mean force values for the three-parallel screw construct at 2-, 4-, and 5-mm fracture displacements were found to be significantly higher compared with those for the other groups. CONCLUSIONS: The use of a three-parallel screw construct seems to provide more stability in the treatment of tongue-type IIC fractures.

The Effect of Autologous Platelet Rich Plasma in the Treatment of Achilles Tendon Ruptures: An Experimental Study on Rabbits.

BACKGROUND: Achilles tendon ruptures are characterized by a long recovery period, high re-rupture rate and late return to work. To overcome these difficulties and augment tendon repair, many agents have been used. AIMS: To determine the effect of autologous platelet rich plasma (PRP) in the treatment of Achilles tendon ruptures in rabbits. STUDY DESIGN: Animal experimentation. METHODS: The study included 14 New Zealand albino rabbits that were divided randomly into 2 groups, A and B, each containing seven rabbits. On day zero, all 28 Achilles tendons were tenotomized and repaired. In group A, the tendons were injected with PRP post-surgery, whereas those in group B were left untreated. On day 28, the right tendons in both groups were examined histopathologically via both light and electron microscopy, and the left tendons were subjected to biomechanical testing. RESULTS: The histological and biomechanical findings in both light and electron microscopy in group A were better than those in group B, but the difference was not significant. According to Tang's scale, the mean value in Group A was 3.57, while it was 3.0 in Group B. The mean value of Group A for the length of collagen bands was 48.09 nm while the mean value of Group B was 46.58 nm (p=0.406). In biomechanical tests, although stiffness values were higher in group A, the difference between groups was not significant. In addition, maximum load values did not differ between groups A and B. CONCLUSION: PRP had no effect on the healing process 28 days post-Achilles tendon rupture.

Combination of anatomical locking plate and retrograde intramedullary nail in distal femoral fractures: comparison of mechanical stability.

OBJECTIVES: This study aims is to investigate mechanical properties of intramedullary (IM) nailing and anatomical locking plate in a bone model based on the hypothesis that their combined usage increases safety of fixation stabilization. MATERIALS AND METHODS: Twenty-one left distal femoral fracture models were used in the study. Bones were divided into three equal groups. Group 1 specimens were fixed laterally by distal femoral anatomical locking plate. Group 2 specimens were fixed with retrograde distal femoral IM nail. Group 3 specimens were fixed with both distal femoral anatomical locking plate and retrograde distal femoral IM nail. In mechanical tests, alterations in axial loading, torsion angles, and load to failure values were measured and compared between groups. RESULTS: Compared to group 1, group 2 was relatively more resistant in axial load tests (p=0.225), and significantly more resistant in load to failure tests (p=0.048). Group 1 was relatively more resistant in torsional load tests (p=0.949) compared to group 2. Group 3 was significantly more resistant than group 1 in axial (p=0.001), torsional (p=0.012) load tests and load to failure tests (p=0.008). Group 3 was significantly more resistant compared to group 2 in axial (p=0.003), torsional (p=0.008) load tests, and relatively more resistant (p=0.059) in load to failure tests. CONCLUSION: Thanks to its high mechanical strength and early mobilization capability, distal femoral anatomical locking plate and IM nail combination might be a choice of treatment in complicated osteoporotic or distal femoral fractures from high-energy trauma in young adults.

Biomechanical comparison of intact lumbar lamb spine and endoscopic discectomized lamb spine.

OBJECTIVES: This study aims to perform a biomechanical comparison of changes on motion segments after minimally invasive percutaneous endoscopically discectomized and intact spine and to investigate the effects of endoscopic discectomy on the lumbar spine of the lamb. MATERIALS AND METHODS: Ten fresh-frozen lamb spines were used in this study. Percutaneous endoscopic discectomy was performed on each spine at L4-L5 level. The biomechanical tests for both intact spine and endoscopically discectomized spine were performed by using axial compression testing machine. The axial compression was applied to all specimens with a loading speed of 5 mm/min. 8400 N/mm moment was applied to each specimen to achieve flexion and extension motions, right and left bending through a specially designed fixture. RESULTS: In axial compression and flexion tests, the specimens were more stable based on displacement values. The displacement values of discected spines were closer to the values of intact specimens. Comparing both groups, only displacement values of the left-bending anteroposterior test were significant (p≤0.05). CONCLUSION: Percutaneous transforaminal endoscopic discectomy (PTED) has no biomechanical and clinical disadvantages. Endoscopic discectomy has also no stability disadvantages. Only anteroposterior displacement values of left bending test were statistically significant. We consider that the reason for such results were due to the fact that PTED was performed on the left side of all specimens.