PURPOSE: The authors have observed a failure to achieve secure fixation in elderly patients when inserting a half-pin at the anteromedial surface of the tibia. The purpose of this study was to compare two methods for inserting a half-pin at tibia diaphysis in elderly patients. MATERIALS AND METHODS: Twenty cadaveric tibias were divided into Group C or V. A half-pin was inserted into the tibias of Group C via the conventional method, from the anteromedial surface to the interosseous border of the tibia diaphysis, and into the tibias of Group V via the vertical method, from the anterior border to the posterior surface at the same level. The maximum insertion torque was measured during the bicortical insertion with a torque driver. The thickness of the cortex was measured by micro-computed tomography. The relationship between the thickness of the cortex engaged and the insertion torque was investigated. RESULTS: The maximum insertion torque and the thickness of the cortex were significantly higher in Group V than Group C. Both groups exhibited a statistically significant linear correlation between torque and thickness by Spearman's rank correlation analysis. CONCLUSION: Half-pins inserted by the vertical method achieved purchase of more cortex than those inserted by the conventional method. Considering that cortical thickness and insertion torque in Group V were significantly greater than those in Group C, we suggest that the vertical method of half-pin insertion may be an alternative to the conventional method in elderly patients.
Aged ; Aged, 80 and over ; *Bone Nails ; Bone Screws ; Diaphyses/radiography/surgery ; *External Fixators ; Female ; Humans ; Male ; Tibia/radiography/*surgery ; *Torque ; X-Ray Microtomography

Adult ; Aged ; Aged, 80 and over ; Bone Cements ; Bone Neoplasms ; diagnostic imaging ; surgery ; Diaphyses ; diagnostic imaging ; pathology ; surgery ; Female ; Humans ; Limb Salvage ; methods ; Male ; Middle Aged ; Radiography ; Treatment Outcome

Human adipose tissue-derived mesenchymal stem cell (hATMSC) have emerged as a potentially powerful tool for bone repair, but an appropriate evaluation system has not been established. The purpose of this study was to establish a preclinical assessment system to evaluate the efficacy and safety of cell therapies in a nude rat bone defect model. Segmental defects (5 mm) were created in the femoral diaphyses and transplanted with cell media (control), hydroxyapatite/tricalcium phosphate scaffolds (HA/TCP, Group I), hATMSCs (Group II), or three cell-loading density of hATMSC-loaded HA/TCP (Group III-V). Healing response was evaluated by serial radiography, micro-computed tomography and histology at 16 weeks. To address safety-concerns, we conducted a GLP-compliant toxicity study. Scanning electron microscopy studies showed that hATMSCs filled the pores/surfaces of scaffolds in a cell-loading density-dependent manner. We detected significant increases in bone formation in the hATMSC-loaded HA/TCP groups compared with other groups. The amount of new bone formation increased with increases in loaded cell number. In a toxicity study, no significant hATMSC-related changes were found in body weights, clinical signs, hematological/biochemical values, organ weights, or histopathological findings. In conclusion, hATMSCs loaded on HA/TCP enhance the repair of bone defects and was found to be safe under our preclinical efficacy/safety hybrid assessment system.
Adipose Tissue/*cytology ; Animals ; Biocompatible Materials/therapeutic use ; Bone Diseases/pathology/radiography/*therapy ; Bone Regeneration/physiology ; Calcium Phosphates/therapeutic use ; Diaphyses/radiography/surgery/ultrastructure ; Disease Models, Animal ; Durapatite/therapeutic use ; Femur/*pathology/radiography/surgery ; Humans ; Male ; *Mesenchymal Stem Cell Transplantation ; Mesenchymal Stem Cells/*cytology ; Rats ; Rats, Nude ; Tissue Engineering ; Tomography, X-Ray Computed ; Transplantation, Heterologous