Flexible Intramedullary Pin Fixation of Both Forearm Bone Fractures in Children

PURPOSE: To evaluate the efficacy of Flexible intramedullary pin fixation in pediatric forearm diaphyseal fractures. MATERIALS AND METHODS: In this retrospective study, we reviewed 15 cases of forearm diaphyseal fractures operated using flexible intra-medullary nail fixation technique between January 2000 and December 2004. Of these 15 children, there were 11 boys and 4 girls with an average age of 11.6 years (range, 7~15 years). The implants were introduced in the distal radius and proximal ulna in all patients. An average duration of fixation was 5.3 months in the radius, 4.7 months in the ulna. After operation, all patient were applied with a long arm cast and the duration of immobilization was 5.2 weeks (range, 4~6 weeks) on average. RESULTS: All fractures in this series healed with normal range of supination (average 80.0) and pronation (average, 71.6 degrees). Average operation time including anesthesia was 123 minutes and hospital stay was 5.4 days. Time to union was 8.4 weeks on average. Range of motion and functional results were satisfactory in all cases. There were one case of incomplete ulnar nerve injury and two cases of refracture which were treated conservatively without any permanent complication. CONCLUSION: Flexible intramedullary pin fixation technique is a good method in case of unstable displaced fracture and difficult or failed closed treatment.

Molecular Characterization of Congenital Pseudoarthrosis of the Tibia Associated with Neurofibromatosis / 대한정형외과학회잡지

PURPOSE: Congenital pseudarthrosis of the tibia, which is recalcitrant to treatments and prone to recur, is frequently associated with neurofibromatosis. The causative gene for neurofibromatosis, NF1, has been identified, but the pathomechanism of congenital pseudarthrosis has not been elucidated. The purposes of this study were to establish primary cell culture from the fibrous hamartoma tissue of pseudoarthrosis, and to compare the gene expression patterns of the fibrous hamartoma and normal bone. MATERIALS AND METHODS: Incubation of the enzymatically treated fibrous hamartoma tissue resulted in growth of the adherent fibroblast-like spindle cells. Expression of hundreds of genes including bone morphogenetic protein-2 and -4, and NF1 were screened by reverse transcription-polymerase chain reaction and cDNA array hydridization methods. RESULTS: Bone morphogenetic protein-2 and -4, and, NF1 were found to express in normal bone, normal periosteum as well as fibrous hamartoma and adjacent hypotrophic bone. Twenty-four genes were found to express exclusively in the fibrous hamartoma, and fifty genes only in the normal bone. CONCLUSION: These findings suggest that the causative gene of neurofibromatosis, NF1, may be associated with pathogenesis of the congenital pseudoarthrosis of the tibia in neurofibromatosis patients.

Changes of Length and Active Force of the Soleus Muscle According to the Position of Ankle Joint in Rabbit / 대한정형외과연구학회지

The dynamic performance of a skeletal muscle depends on the length-force and force-velocity relationships. The length-force relationship of muscle was described by Blix for the first time. The contractile elements of muscles produce the active length-force curve. The objective of this study is to determine the length-force relationship of the rabbit's soleus muscle and changes of tetanic force according to the position of ankle joint. The amount of excursion of the soleus muscle for full range of motion of the ankle joint was 25 mm. The ratio of excursion compared to the length of neutral position was 24%. That means that the soleus muscle has large amount of excursion that is responsible for producing active force throughout the whole range of ankle motion. The length at which active force of the muscle is maximal is called optimum length(Lo). The ratio of the optimum length compared to the length of neutral position was 98%. This means that the active force of the soleus muscle was maximal at the position of slight plantarflexion(about 2 degrees of plantarflexion). The value of the tetanic force was 3.1kg/cm2 in average, and the active length-force curve showed asymmetrical shape. The effective range is a length change from minimal point of zero active force to maximal point of zero active force. In this study, the minimal point of zero active force was 11mm shorter and maximal point of zero active force was 13mm longer than optimum length. Therefore, the effective range was 24mm. Active force increased abruptly at which muscle length was 90% of neutral length. At that point, active force was less than 20% of maximal tetanic force.