Objective—To compare heat generation during insertion, pullout strength, and associated microdamage between a self-tapping positive profile transfixation pin (STTP) and nontapping positive profile transfixation pin (NTTP).
Sample Population—30 pairs of third metacarpal bones (MC3s) from adult equine cadavers.
Procedures—One MC3 of each pair was assigned to the STTP group; the other was assigned to the NTTP group. The assigned pin was inserted into the diaphysis in a lateral to medial direction. Bone temperature increase during pilot-hole drilling and pin insertion was recorded at 1 mm from the final thread position with wire thermocouples at cis and trans cortices. Resistance to axial extraction before and after cyclic loading was measured in a material testing device, and microstructural damage caused by transfixation pin insertion was assessed with scanning electron microscopy.
Results—The STTP group developed a significant increase in bone temperature, compared with the NTTP group. No significant difference was found between the mean maximal pullout strength of the STTP and the NTTP in both non–cyclic-loaded and cyclic-loaded groups. Microdamage to the bone-pin interface was lower when the STTP versus the NTTP was used, but more bone debris was apparent after inserting the STTP.
Conclusion and Clinical Relevance—Because of the significant increase in temperature generation and debris accumulation despite similar pullout strengths and lesser microfracture formation, the STTP likely poses a higher risk of bone necrosis and potential loosening than the NTTP. This might be corrected by redesign of the tapping aspect of the STTP.
Objective—To ultrasonographically quantify experimentally induced effusion of the distal interphalangeal (DIP) joint of horses and compare results with those obtained with palpation.
Sample—8 forelimbs from equine cadavers and forelimbs of 5 mares.
Procedures—Preliminary ex vivo experiments were performed to validate the methods. Then, the DIP joints of the forelimbs of standing horses were serially distended with saline (0.9% NaCl) solution (1, 4, and 10 mL) by injection through an intra-articular catheter. Two ultrasonographers measured distension of the dorsal recess of the DIP joint, and 2 surgeons, who were not aware of the volume injected, graded joint effusion by palpation.
Results—Intraobserver and interobserver repeatability was excellent for ultrasonographic measurements. Interobserver agreement for use of palpation to detect joint distension was moderate (κ = 0.45). There was an overall increase in the palpation distension grade with an increase in injected volume. Sensitivity for detection with palpation of larger volumes (4 and 10 mL) was high (92% and 100%, respectively). However, sensitivity was lower (57%) for detection with palpation of minimal distension (1 mL).
Conclusions and Clinical Relevance—Although palpation provided a reliable clinical assessment of DIP joint effusion for volumes of 4 to 10 mL, ultrasonographic measurements were easy to obtain, more accurate, and able to detect smaller amounts of distension. This may be clinically relevant for the assessment of effusion of the DIP joint that can arise in horses with early osteoarthritis or infectious arthritis with concomitant soft tissue swelling that precludes accurate assessment with palpation.
Case Description—4 horses with a history of neck pain, abnormal head carriage, and related inability to perform were examined. Cranial nuchal bursitis was diagnosed in 2 horses, and caudal nuchal bursitis was diagnosed in the other 2.
Clinical Findings—All 4 horses had prominent swelling in the region between the frontal bone and temporal fossa (ie, the poll) and abnormal head carriage. Ultrasonographic examination revealed fluid distention and synovial thickening of the cranial or caudal nuchal bursa in all 4 horses. Ultrasonography-guided aspiration of the affected region was performed successfully in 3 horses. Radiography revealed bony remodeling and mineralization over the dorsal aspect of the atlas in 1 horse and a radiolucency at the axis in another. Nuclear scintigraphy revealed an increase in radioisotope uptake at the level of C2 in 1 horse. Although a septic process was considered among the differential diagnoses in all horses, a septic process could only be confirmed in 1 horse.
Treatment and Outcome—All horses were refractory to conservative management consisting of intrabursal injection of anti-inflammatory medications. Bursoscopic debridement and lavage of the affected bursae resulted in resolution of the clinical signs in all horses, and they all returned to their intended use.
Clinical Relevance—Cranial and caudal nuchal bursitis, of nonseptic or septic origin, should be considered as a differential diagnosis in horses with head and neck pain. Horses undergoing surgical intervention consisting of nuchal bursoscopy have the opportunity to return to their original degree of exercise. (J Am Vet Med Assoc 2010;237:823–829)