Veterinary Surgery

Steffen, Frank; Flueckiger, Mark; Montavon, Pierre M.

doi: 10.1053/jvet.2003.50056pmid: 14569568

Objective— To present a detailed description of a dog with atlanto‐occipital (A–O) luxation, including results of the neurologic examination, diagnostic imaging, and treatment by closed reduction. Study Design— Clinical case report. Sample Population— One adult intact male German shepherd dog. Results— Neurologic signs included nonambulatory tetraparesis and neck pain. An apparent hypoglossal nerve deficit was consistent with a lesion at the peripheral part of the nerve in the region of the craniocervical junction. Radiographic examination revealed a left‐sided luxation of the A–O joint, and fractures were excluded with the aid of computed tomography (CT). Closed reduction of the luxated articulation resulted in a stable A–O joint, and complete neurologic recovery occurred within 4 weeks. Conclusions— Hypoglossal nerve deficits may be associated with A–O luxation. Clinical Relevance— Closed reduction of a unilateral, traumatic luxation of the A–O joint is a therapeutic option in dogs. CT imaging, especially 3‐dimensional reconstruction, was considered helpful in excluding fractures as well as defining treatment options.

Semevolos, Stacy A.; Watkins, Jeffrey P.; Auer, Jörg A.

doi: 10.1053/jvet.2003.50053pmid: 14569569

Objectives— To describe surgical arthrodesis of the scapulohumeral joint and to evaluate its efficacy in reducing morbidity associated with severe shoulder dysfunction in miniature horses. Study Design— Retrospective study. Animals— Four miniature horses. Methods— Medical records and radiographs were reviewed for history, physical examination findings, lameness evaluation, radiographic evaluation, surgical techniques, postoperative complications, and outcome. A 10‐ or 11‐hole, 4.5‐mm narrow dynamic compression plate and 4.5‐mm cortical screws were applied to the cranial surface of the scapula and cranial surface of the humerus after osteotomy of the intermediate tubercle. In most horses, 1 or 2 screws were inserted in lag fashion across the joint, through holes in the plate. Results— Scapulohumeral osteoarthritis was diagnosed radiographically in 4 horses, and 3 horses had concurrent shoulder luxation or subluxation. All horses had grade 3 or 4 lameness before surgery, and most improved by 1 to 2 grades after surgery. Despite complications of implant failure (2 horses), infection (2 horses), scapular fracture (1 horse), and atrophy of the shoulder muscles (1 horse), functional arthrodesis reduced morbidity in all horses. Conclusions— Scapulohumeral arthrodesis facilitates early return to weight bearing in miniature horses with severe scapulohumeral joint osteoarthrosis. Despite functional gait abnormality, the horses ambulated quite well after surgery. Clinical Relevance— Scapulohumeral arthrodesis should be considered for debilitating conditions of the shoulder joint in miniature horses, especially when the intended outcome is breeding or pasture soundness.

Jann, Henry; Blaik, Margaret; Emerson, Robert; Tomioka, Michiko; Stein, Larry; Moll, David

doi: 10.1053/jvet.2003.50059pmid: 14569570

Objective— To describe the healing characteristics of deep digital flexor tenorrhaphy within the digital sheath. Study Design— Experimental study. Animals— Five mature horses. Methods— Right thoracic limb, deep digital flexor tenorrhaphy was performed within the digital sheath. Limbs were cast in partial flexion using a short limb cast for 6 weeks. Next, extended heel shoes were used for limb support for 14 weeks. Healing was evaluated by sequential ultrasonographic examinations, and limb use was evaluated by force plate analysis. At 26 weeks, mechanical strength and morphologic characteristics of the repair site were evaluated. Results— Gap (mean, 0.93 cm.) formation was evident in unloaded limbs at 3 weeks. This increased markedly by 6 weeks and was 5 cm at 26 weeks. Demarcation between the deep and superficial flexor tendons decreased as the transected ends adhered to the dorsal surface of the superficial flexor tendon. The intrathecal space was reduced by fibrous tissue. Mean maximum load to failure of the repair tissue was 4,616 ± 3,556 N, with a mean stress of 12.99 ± 2.78 MPa. The repair consistently failed at the adhesion between the transected tendon and the superficial flexor tendon. Conclusions— Intrathecal tenorrhaphy with external coaptation (in partial limb flexion) for 6 weeks resulted in gap healing, fibrous adhesion between the deep and superficial flexor tendons, fibrous tissue reduction of the intrathecal space, and a pasture‐sound horse at 26 weeks. Clinical Relevance— Without improved methods for immobilizing the deep digital flexor tendon, intrathecal tenorrhaphy is unlikely to result in first intention tendon healing.

Haerdi, Christina; Costa, Riccardo Dalla; Auer, Joerg A.; Linke, Berend; Steiner, Adrian

doi: 10.1053/jvet.2003.50049pmid: 14569571

Objective— To compare the gripping force of a standard clamp with click‐on and T clamps of the 4.5/5.5‐mm VetFix (AO Research Institute, Davos, Switzerland), mounted on smooth and roughened rods. Study Design— In vitro mechanical study. Methods— Rods were mounted on a clamp‐holding device. Each clamp type was tested on a materials‐testing machine in groups of 6 specimens for torsional and axial load stability on smooth and roughened rods (total, 72 specimens). The variable evaluated was the discontinuity point (DP) as a measure for gliding resistance of the clamp on the rod. Means (±SD) were calculated for all groups separately. For statistical comparison, a multiple regression model was fitted with level of significance set at P= .05. Results— The direction of torsion had a significant effect on DP for both asymmetric clamps (standard, click‐on). In torsion and axial load, the roughened rod had significantly higher DP levels than the smooth rod for the standard clamp. Rods differed only in axial load for the T clamp, again favoring the roughened rod. The click‐on clamp did not reach 10% of the values achieved by the other clamps, independent from the rods and loading conditions. Compared with the T clamp, standard clamp DP values were significantly higher in torsion on the roughened rod as well as in axial load on both rod types. Conclusions— The roughened rod with a standard clamp was mechanically superior. For the T clamp, the small loss of gripping force may be compensated for by the possibility of inserting 2 more screws. Clinical Relevance— The roughened rod may enhance the bending, compressive, and torsional properties of the 4.5/5.5‐mm VetFix system by reducing the risk of clamp gliding on the rod. The standard clamp is the clamp of choice, except for the metaphyseal or epiphyseal region, at which use of a T clamp may be indicated to increase the number of screws inserted at the end of the rod.

Zarucco, Laura; Swanstrom, Michael D.; Driessen, Bernd; Hawkins, David; Hubbard, Mont; Steffey, Eugene P.; Stover, Susan M.

doi: 10.1053/jvet.2003.50058pmid: 14569572

Objective— To develop and test an experimental model for in vivo short‐term recording of peak isometric forces of the digital flexor muscles in the forelimb of adult horses. Study Design— In vivo experimental study. Sample Population— Four healthy, anesthetized, adult Thoroughbred horses (3 to 7 years old; 527 ± 87 kg) Methods— In dorsal recumbency, ulnar and median nerves were exposed and instrumented with insulated bipolar cuff stimulation electrodes for later connection to an electrical stimulator. In left lateral recumbency, a biplanar fixator was applied to the right humerus and a custom‐made, rigid, aluminum frame connected to it, to allow loading of muscles distal to the fixator. Threaded transfixation pins through the radial and metacarpal condyles were clamped to the rigid frame so that the humerus, radius, ulna, and metacarpus were fixed in position. Each digital flexor muscle insertion tendon was transected just above the metacarpophalangeal joint, extracted from the carpal canal, and secured in a metal clamp positioned at the distal myotendinous (MT) junction. Distally, the clamp was connected in series to a load cell and a pneumatic actuator to record force and to maintain muscle length during nerve stimulation. A linear potentiometer was connected in parallel to the actuator to record MT junction position. Initial trials were conducted to identify median and ulnar nerve stimulation variables to achieve maximal muscle contraction. Isometric contractions were performed at different muscle lengths and peak forces registered during 3 seconds of supramaximal dual (ulnar and median) nerve stimulation. Results— A stimulation voltage of 2.5 to 5.0 V at 50 Hz usually produced maximal force for both the superficial digital flexor (SDF) and deep digital flexor (DDF) muscles. Single ulnar and median nerve stimulation elicited force development not only in the DDF muscle but also in the SDF muscle. At voltages higher than 1 V, normalized force was greatest with combined median and ulnar nerve stimulation for both the DDF and SDF muscles; however, normalized force was greater for median nerve stimulation than ulnar nerve stimulation in the DDF muscle, and the opposite relationship was observed for the SDF muscle. Final recording of dual supramaximal nerve stimulation of SDF and DDF muscles resulted in peak isometric forces of 716 ± 192 N and 1,577 ± 203 N, respectively. Conclusions— The instrumentation technique and experimental protocol enabled recording of peak isometric forces in the SDF and DDF muscles of anesthetized adult horses. Clinical Relevance— Studies using this model will improve knowledge of SDF and DDF muscle mechanics with insight to functional implications of the complex architecture of these muscles. Knowledge of the dynamic performance of the SDF and DDF muscles would also be useful for the development of new treatment strategies for flexor deformities and tendon injuries in horses.

Gordon, Wanda J.; Conzemius, Michael G.; Riedesel, Elizabeth; Besancon, Michael F.; Evans, Richard; Wilke, Vicki; Ritter, Matthew J.

doi: 10.1053/jvet.2003.50051pmid: 14569573

Objective— To evaluate the relationship between limb function and radiographic evidence of stifle osteoarthrosis (OA) in dogs. Study Design— The relationship between force platform data and radiographic OA score was evaluated on 2 separate days using regression analysis. Interday variation was also assessed. Animals— Forty‐one dogs with visible lameness and radiographic evidence of stifle OA. Methods— Force platform data were collected at a velocity of 1.7 to 2.0 m/s for 5 trials on day 1 and day 8. Radiographs taken on day 1 were scored using a previously reported OA scoring system. Results— No significant relationship was found between force platform data and OA score. No significant differences were found between any day 1 and day 8 force platform values. Conclusions— Although radiographic evidence of stifle OA provides evidence of pathology, it does a poor job of representing limb function. In addition, the absence of significant differences between day 1 and day 8 values in this population of dogs supports use of only a single force platform evaluation before measuring a treatment effect. Clinical Relevance— The presence of OA in the stifle joint does not correlate with clinical function; radiographic outcome should be used cautiously as a predictor of clinical outcome.

McDuffee, Laurie A.; Anderson, Gail I.

doi: 10.1053/jvet.2003.50060pmid: 14569574

Objective— To compare the osteogenic potential of cancellous bone of conventional graft sites with that of one nonconventional site (fourth coccygeal vertebra) and to investigate the tibial periosteum as a donor site with respect to osteogenic potential. Study Design— In vitro osteogenic cell culture system. Sample Population— Eight adult horses. Methods— Cancellous bone or tibial periosteum was aseptically collected and cut into bone chips or periosteal strips of 1 to 2 mm3 for primary explant cultures. After 2 weeks, primary tissue cultures that yielded a population of osteogenic cells were counted and subcultured at 1 × 105 cells/35‐mm dish in osteogenic media. After 7 to 10 days, subcultures were stained with Von Kossa (VK) to assess mineralized bone nodule formation. VK‐positive bone nodules were counted as osteoprogenitors and compared among 3 donor sites, which provided consistent primary osteogenic cells (tuber coxae, fourth coccygeal vertebra, periosteum) using ANOVA (P < .05). Results— Sternal and tibial bone yielded viable osteogenic cells from 25% and 50% of horses, respectively, whereas yields from tuber coxae, coccygeal vertebra, and periosteum were 75%, 100%, and 100%, respectively. Tuber coxae and periosteum had significantly greater numbers of osteoprogenitors compared with fourth coccygeal vertebra. Conclusions— Among the conventional donor sites, tuber coxae most consistently yielded viable osteogenic cells with an acceptable percentage of osteoprogenitors. Sternal and tibial sites were unreliable in providing osteogenic cells. Two new donor sites, the fourth coccygeal vertebra and tibial periosteum, were tissues with good osteogenic potential. Clinical Relevance— When a source of transplantable viable osteoprogenitor cells is desired, use of the tuber coxae as a conventional donor site is warranted. Use of tibial periosteum or fourth coccygeal vertebra as reliable sources of transplantable osteoprogenitors should be considered.

Goethem, Bart E. B. J.; Rosenveldt, Karin W.; Kirpensteijn, Jolle

doi: 10.1053/jvet.2003.50052pmid: 14569575

Objective— To compare the effect of using monopolar (MEC) or bipolar electrocoagulation (BEC) on surgical time for laparoscopic ovariectomy in dogs and to evaluate the influence of age, weight and obesity, and estrus or pseudopregnancy on surgical time. Study Design— Prospective, nonrandomized, clinical trial. Animals— One hundred three female dogs. Methods— Laparoscopic ovariectomy was performed with MEC or BEC by 1 surgeon using a standard protocol. Surgical time was recorded for the different procedural stages and was statistically evaluated for differences between MEC and BEC (χ2, Student t test, and ANOVA). The influence of significant variables was analyzed using multiple linear regression analysis. Results— Mean surgical time was 47 minutes (range, 27 to 110 minutes). With BEC, surgical time was significantly shorter (41 minutes; P < .001) than with MEC (53 minutes). Obesity (56 vs. 42 minutes; P < .001) and intraoperative mesovarial bleeding (56 vs. 46 minutes; P= .03) increased surgical time. Dog age, estrus, and pseudopregnancy did not significantly influence surgical time. Conclusions— BEC decreased laparoscopic ovariectomy time, decreased intraoperative hemorrhage, and, with the technique used, facilitated exteriorization of the ovaries. Clinical Relevance— Laparoscopic ovariectomy can be performed more rapidly when using BEC instead of MEC and with less risk of mesovarial hemorrhage.

Fettig, Arthur A.; Rand, William M.; Sato, Amy F.; Solano, Mauricio; McCarthy, Robert J.; Boudrieau, Randy J.

doi: 10.1053/jvet.2003.50054pmid: 14569576

Objective— To determine (1) the inter‐ and intraobserver variability in measurement of tibial plateau angle (TPA), (2) whether this inter‐ and intraobserver variability is related to the characteristics of the dog (age, size, and amount of degenerative joint disease (DJD)) and the experience level of the observer, and (3) the extent of any relationship between interobserver variability of TPA and the variability of the observers' selection of the specific cranial and caudal points along the tibial plateau. Study Design— Examination of tibial radiographs of 40 dogs clinically affected with a cranial cruciate ligament (CrCL)‐deficient stifle joint. Methods— Eleven different observers, divided into 3 groups based on their level of experience with the tibial plateau leveling osteotomy (TPLO) technique, measured the TPA on all 40 radiographs on 5 different occasions. The degree of DJD present in the stifle joint was independently graded as an overall measure and then again as it specifically related to the cranial and caudal points along the tibial plateau. The total observed variabilities of the TPA were assessed with reference to interobserver differences, intraobserver differences, and among the groups of observers with respect to the different dog characteristics. Finally, the specific points selected on the radiographs were reexamined to determine whether any variability was present in cranial and caudal point selection. Results— The interobserver standard deviation of the TPA measurements for each dog was 0.8°, and the intraobserver standard deviation was 1.5°. The TPA measurements obtained by the 11 observers differed significantly from each other (P < .001); however, there was no significant difference of TPA among the different groups of observers (P= .67). There was no significant correlation observed between either the inter‐ or intraobserver variability and the dog characteristics. Specific point data and their relationship to the various variables of dog characteristics and inter‐ and intraobserver TPA variability revealed significant correlations only to the amount of DJD present at the caudal point (P= .001). Conclusions— Interobserver variation, but no significant group variation, was present. Overall DJD did not appear to be related to the variability in TPA angle measurement. Most of the interobserver variability was attributable to variability in horizontal point selection at both the cranial and caudal points and vertical point selection at the caudal point. It appears that degenerative changes that specifically obscure the points on the tibial plateau, especially at the caudal point, are responsible for most of the interobserver variation. Clinical Relevance— The desired postoperative TPA of 5° is dependent on a precise initial measure of TPA preoperatively. This study indicates that there is statistically significant interobserver variability with measurement of TPA, which, therefore, can result in a similar amount of variability with the final tibial plateau slope obtained postoperatively.

doi: 10.1111/j.1532-950X.2003..xpmid: N/A