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invasive percutaneous thread-transecting surgical technique for carpal tunnel and trigger digit release in humans has been described. 23 – 27 Under ultrasonographic guidance, a cutting thread is looped around the ligament using needles and the desmotomy is

Open access
in American Journal of Veterinary Research

at low speeds 5 and continuous lavage should be provided to lubricate the drill hole and therefore reduce friction. Pin design is another important factor to consider. Bone debris must be cleared during insertion of a threaded pin to reduce

Full access
in American Journal of Veterinary Research

tear production. 23,24 Another quantitative tear film test, the PRTT, is less frequently used in veterinary medicine. However, the shorter time required to perform the PRTT and the small size of the thread may make this test particularly suitable for

Full access
in Journal of the American Veterinary Medical Association

Objective

To evaluate the in vitro axial extraction forces necessary to remove pins and to evaluate mechanical trauma resulting from pin insertion, using various types of pins and insertion techniques.

Design

Prospective, controlled study.

Subjects

Femurs of cadavers of dogs.

Procedure

Pins were inserted as follows: 1 non-threaded pin without drilling of a pilot hole, 1 enhanced threaded pin with drilling of a pilot hole, and 1 enhanced threaded pin without drilling of a pilot hole. After pin insertion, mechanical damage and proper pin insertion was determined by means of radiography. Axial extraction forces were determined for all pins, using a universal testing machine. Mechanical damage was evaluated in 12 additional femurs. After pin insertion, all pins were removed from the bone by use of a low-speed power drill. Samples were sectioned, processed, and evaluated by use of dissecting and scanning electron microscopy.

Results

Using radiography, a significant difference was detected in the number of periosteal trans-cortex fractures between the enhanced threaded and non-threaded pins. Axial extraction force was not significantly different between the enhanced threaded pins, regardless of insertion technique; however, the axial extraction force was significantly greater for enhanced threaded pins, compared with that for nonthreaded pins. Microfractures only were detected on the periosteum of the trans-cortex of enhanced threaded pins by use of scanning electron microscopy.

Clinical Implications

We cannot recommend a particular insertion technique to decrease mechanical trauma to the bone and to increase axial extraction force needed for removal of enhanced threaded pins from the femur of dogs. (J Am Vet Med Assoc 1996;208:883–887)

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To compare the in vitro holding power and associated microstructural damage of 2 large-animal centrally threaded positive-profile transfixation pins in the diaphysis of the equine third metacarpal bone.

Sample Population—25 pairs of adult equine cadaver metacarpal bones.

Procedure—Centrally threaded positive-profile transfixation pins of 2 different designs (ie, self-drilling, self-tapping [SDST] vs nonself-drilling, nonself-tapping [NDNT] transfixation pins) were inserted into the middiaphysis of adult equine metacarpal bones. Temperature of the hardware was measured during each step of insertion with a surface thermocouple. Bone and cortical width, transfixation pin placement, and cortical damage were assessed radiographically. Resistance to axial extraction before and after cyclic loading was measured using a material testing system. Microstructural damage caused by transfixation pin insertion was evaluated by scanning electron microscopy.

Results—The temperature following pin insertion was significantly higher for SDST transfixation pins. Periosteal surface cortical fractures were found in 50% of the bones with SDST transfixation pins and in none with NDNT transfixation pins. The NDNT transfixation pins were significantly more resistant to axial extraction than SDST transfixation pins. Grossly and microscopically, NDNT transfixation pins created less damage to the bone and a more consistent thread pattern.

Conclusions and Clinical Relevance—In vitro analysis revealed that insertion of NDNT transfixation pins cause less macroscopic and microscopic damage to the bone than SDST transfixation pins. The NDNT transfixation pins have a greater pull out strength, reflecting better initial bone transfixation pin stability. (Am J Vet Res 2000;61:1298–1303)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate in vitro holding power and associated microstructural and thermal damage from placement of positive-profile transfixation pins in the diaphysis and metaphysis of the equine third metacarpal bone.

Sample Population—Third metacarpal bones from 30 pairs of adult equine cadavers.

Procedure—Centrally threaded positive-profile transfixation pins were placed in the diaphysis of 1 metacarpal bone and the metaphysis of the opposite metacarpal bone of 15 pairs of bones. Tensile force at failure for axial extraction was measured with a materials testing system. An additional 15 pairs of metacarpal bones were tested similarly following cyclic loading. Microstructural damage was evaluated via scanning electron microscopy in another 6 pairs of metacarpal bones, 2 pairs in each of the following 3 groups: metacarpal bones with tapped holes and without transfixation pin placement, metacarpal bones following transfixation pin placement, and metacarpal bones following transfixation pin placement and cyclic loading. Temperature of the hardware was measured with a surface thermocouple in 12 additional metacarpal bones warmed to 38 C.

Results—The diaphysis provided significantly greater resistance to axial extraction than the metaphysis. There were no significant temperature differences between diaphyseal and metaphyseal placement. Microstructural damage was limited to occasional microfractures seen only in cortical bone of diaphyseal and metaphyseal locations. Microfractures originated during drilling and tapping but did not worsen following transfixation pin placement or cyclic loading.

Conclusions and Clinical Relevance—Centrally threaded, positive-profile transfixation pins have greater resistance to axial extraction in the diaphysis than in the metaphysis of equine third metacarpal bone in vitro. This information may be used to create more stable external skeletal fixation in horses with fractures. (Am J Vet Res 2000;61:1304–1308)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To investigate the biomechanics of cervical vertebral motion units (VMUs) before and after a ventral slot procedure and after subsequent pin-polymethylmethacrylate (pin-PMMA) fixation and to assess the use of smooth and positive-profile threaded (PPT) pins in pin-PMMA fixation and intravertebral pin placement.

Sample Population—Cervical portions (C3 through C6 vertebrae) of 14 cadaveric canine vertebral columns.

Procedure—Flexion and extension bending moments were applied to specimens before and after creation of a ventral slot across the C4-C5 intervertebral space and after subsequent smooth or PPT pin-PMMA fixation at that site. Data for the C3-C4, C4-C5, and C5-C6 VMUs were compared among treatments and between pin types, and pin protrusion was compared between pin types.

Results—Compared with values in intact specimens, ventral slot treatment increased neutral zone range of motion (NZ-ROM) by 98% at the treated VMUs and appeared to decrease overall ROM at adjacent VMUs; pin-PMMA fixation decreased NZ-ROM by 92% at the treated VMUs and increased overall NZ-ROM by 19% to 24% at adjacent VMUs. Specimens fixed with PPT pins were 82% (flexion) and 80% (extension) stiffer than smooth–pin-fixed specimens. Overall, 41% of pins protruded into foramina; PPT pins were more likely to protrude into transverse foramina.

Conclusions and Clinical Relevance—Results indicated that fixation of a cervical VMU alters the biomechanics of adjacent VMUs and may contribute to degeneration of adjacent intervertebral disks. Use of threaded pins may lower the incidence of pin loosening and implant failure but enhances the likelihood of transverse foramina penetration. ( Am J Vet Res 2005;66:678–687)

Full access
in American Journal of Veterinary Research

interference between surgical implants and soft tissues and improving interfragmentary stability. A headless, tapered, fully threaded, variable-pitch, self-tapping screw a (ie, headless tapered compression screw) originally designed for orthopedic disorders

Full access
in American Journal of Veterinary Research