Evaluation of End-threaded Positive and Negative Profile Intramedullary Pins for Management of Long Bone Fractures in Dogs

Background: Intramedullary pinning (IMP) is the most commonly used internal skeletal fixation technique. Threaded pins (also called Schanz Screws) provide a comparatively better holding strength than non-threaded tipped intramedullary pins. The present study was planned to evaluate and compare the efficacy of positive and negative profile end threaded intramedullary pins in the management of long bone fractures in dogs. Methods: Eleven clients owned dog suffering from fracture of long bones were randomly divided in to two groups. Animals of group I (n=5) and group II (n=6) were treated with end threaded positive and negative profile intra medullary pin, respectively. The intramedullary pinning was done using 3 to 5.5 mm diameter pins under general anesthesia, the time taken for surgery, size of end threaded intramedullary pin used in each case was noted down. Radiographs were taken preoperatively, immediately after fixation and then at regular intervals till signs of radiographic healing were evident. Result: There was no significant difference between the two groups in terms of time taken for fixation/surgery and in healing time, with a gradual improvement in weight bearing postoperatively in both the groups. There was mild periosteal callus formation in all the cases when observed radiographically and the pins were removed after radiographic healing was evident in an anticlockwise manner using Jacob’s chuck and key, under mild sedation. There was no complication like implant failure or pin tract sepsis or pin migration or pin breakage in any of the cases of two groups. However, passing the positive profile end threaded intramedullary pin in distal fragment is comparatively smoother and easier as compared to negative profile end threaded intra medullary pin.