David G. Levine

Efficacy of Three Tourniquet Types for Intravenous Antimicrobial Regional Limb Perfusion in Standing Horses

OBJECTIVE To determine (1) if clinically useful concentrations of amikacin sulfate can be obtained in synovial fluid during regional limb perfusion (RLP) performed above the carpus in standing sedated horses and (2) to determine the efficacy of 3 tourniquet types (narrow rubber [NR], wide rubber [WR], pneumatic [PN]). ANIMALS Horses (n=9). METHODS Bilateral forelimb RLP with amikacin sulfate (2.5 g) were administered through the cephalic vein in standing sedated horses. Limbs were randomly assigned to the 3 tourniquet types (NR, WR, PN) applied above the carpus. Metacarpophalangeal synovial fluid was obtained 0.5 hour after perfusion. Amikacin concentration in the synovial fluid was detected using fluorescence polarization immunoassay. RESULTS Mean synovial concentrations of amikacin in the PN (mean 236 μg/mL; range 23-913 μg/mL) and WR (mean 64.2 μg/mL; range 7-315 μg/mL) were significantly higher (P=.000 and .032, respectively) than the NR tourniquet (mean 2.1 μg/mL; range 0.9-3.3 μg/mL). CONCLUSIONS The PN tourniquet resulted in the highest synovial fluid amikacin concentrations in all horses, although administration with PN and WR tourniquets achieved adequate amikacin concentrations. NR tourniquet is ineffective and should not be used for RLP above the carpus in the standing horse.

Effect of topical application of 1% diclofenac sodium liposomal cream on inflammation in healthy horses undergoing intravenous regional limb perfusion with amikacin sulfate

OBJECTIVE To determine whether topical application of 1% diclofenac sodium cream would decrease inflammation at sites of IV regional limb perfusion (IVRLP) in healthy horses. ANIMALS 6 healthy adult horses (12 forelimbs). PROCEDURES Bilateral IVRLP with 2.5 g of amikacin sulfate was performed twice in each horse, with 24 hours between each session. Horses were treated with topical 1% diclofenac liposomal cream (treated limbs) or a placebo cream (control limbs). All injection sites were evaluated before the first IVRLP session and 24 hours after the second session by means of ultrasonographic examination by a trained ultrasonographer who was unaware of the treatment received. Circumferential measurements and subjective visible inflammation scores were recorded by a veterinarian who was also unaware of treatment received. RESULTS After IVRLP, control limbs had a significantly greater increase in subcutaneous thickness, compared with treated limbs. Ultrasonographic and visual assessment scores were significantly higher in control versus treated limbs. The mean change in limb circumference was greater, but not significantly so, in control limbs, compared with treated limbs. CONCLUSIONS AND CLINICAL RELEVANCE Topical application of 1% diclofenac sodium liposomal cream to sites of IVRLP in healthy horses decreased inflammation as judged by visual assessment and ultrasonography. Decreased inflammation may allow extended use of IVRLP and may result in a reduction in pain in treated horses.

The Normal and Abnormal Equine Neonatal Musculoskeletal System.

The first weeks of life are critical in many aspects, and the musculoskeletal system is no exception. Being able to stand and nurse within hours of life is necessary for survival. Laxity, flexural deformities, and skeletal immaturity can all make it difficult for neonates to ambulate. The increased vascularity to bones and cartilage mixed with the newly forming immune system also make neonates susceptible to infections that we rarely see in adult animals. This article concentrates on orthopedic conditions seen in the first 2 weeks of life.

Use of locking compression plates in ulnar fractures of 18 horses*: JACOBSet al.

OBJECTIVES To describe the outcome, clinical findings, and complications associated with the use of the locking compression plate (LCP) for various types of ulnar fractures in horses. STUDY DESIGN Retrospective case series. SAMPLE POPULATION Client owned horses (n = 18). METHODS Medical records, radiographs, and follow-up for horses having an ulnar fracture repaired using at least 1 LCP were reviewed. Fifteen of 18 horses had fractures of the ulna only, and 3 horses had fractures of the ulna and proximal radius. RESULTS All 18 horses were discharged from the hospital. Complications occurred in 5 horses; incisional infection (n = 4, 22%), implant-associated infection (n = 2, 11%), and colic (n = 1, 6%). Follow-up was available for all horses at a range of 13-120 months and 15 horses (83%) were sound for their intended purpose and 3 horses (17%) were euthanatized. One horse was euthanatized for complications associated with original injury and surgery. CONCLUSIONS The LCP is a viable method of internal fixation for various types of ulnar fractures, with most horses in this series returning to soundness.

Using distraction forces to drive an autodistractor during limb lengthening

Distraction osteogenesis can result in high forces developing in the limb. To determine and control the distraction forces (DF), a motorized distractor driven by feedback from DF was developed and used to lengthen the tibiae of 6 sheep undergoing distraction osteogenesis. The forces were measured continually, and, in 4 of the sheep, a force threshold was set, above which an increase in rate was initiated. The rate kept increasing to a set limit if forces remained above the threshold; otherwise, the rate was decreased. Radiographs were acquired biweekly, and muscle samples were analyzed from both the operated and contralateral limbs upon termination of the experiment. Results demonstrated a drop in DF associated with increased lengthening rate, attributed to separation of the callus as indicated by radiography. Histological evidence of muscle damage generally correlated with higher DF levels. There was a significant decrease in muscle fiber diameter in lengthened relative to contralateral limbs. Collectively, the results demonstrated the use of a force-driven distraction system and support the need for considering force data in regulating distraction rates to achieve optimal clinical outcomes.

Multiple Rib Fracture Repair in a Neonatal Holstein Calf

OBJECTIVES To report rib fracture repair in a neonatal calf using the Securos Cranial Cruciate Ligament Repair System (SCCLRS). STUDY DESIGN Case report. ANIMALS A 2-day-old female Holstein calf with fracture of right ribs 4-10. METHODS On the day of admission the calf was anesthetized and rib fractures were repaired using open reduction and the SCCLRS. RESULTS Rib fractures were successfully stabilized and the calf discharged from the hospital 8 days postoperatively. CONCLUSIONS Modification of previously reported use of the SCCLRS to repair rib fractures in foals was required because of the different anatomy in the calf. This new technique was rapidly and easily performed for a large number of fractured ribs in this case. CLINICAL RELEVANCE Effective rib fracture repair in calves can be readily performed using the SCCLRS with modification of the technique reported in foals.

Physeal Fractures in Foals

Physeal fractures are common musculoskeletal injuries in foals and should be included as a differential diagnosis for the lame or nonweightbearing foal. Careful evaluation of the patient, including precise radiographic assessment, is paramount in determining the options for treatment. Prognosis mostly depends on the patients age, weight, and fracture location and configuration.

Force feedback in limb lengthening

A new variable-rate distraction system using a motorized distractor driven by feedback from the distraction force was designed. The distractor was mounted on a unilateral fixator and attached to the tibiae of 6 sheep that underwent distraction osteogenesis. The sheep were divided equally into 3 groups. In group 1, the forces were recorded but were not used to drive the lengthening rate. In group 2, force feedback was used and the desired distraction force level was set to 300 N and the initial rate was 1 mm/day. Group 3 also underwent force feedback with the desired force limit at 300 N, but the rate change was initiated earlier, at 200 N. The distraction force was recorded at 15 second intervals throughout the distraction phase and stored onboard the distractor.

Optimizing Limb Lengthening Using an Autodistractor and Force Measurement

The procedure of limb lengthening is a common method for correcting limb length inequality. The lengthening procedure, however, can result in serious complications such as premature consolidation of bone and soft-tissue contractures. To avoid adverse effects, it is important to determine the safe limits of the lengthening procedure in terms of forces applied, rate of distraction, overall length added and effects of the procedure on associated tissue. In this study, we investigate the relationship between distraction speed and callus formation in the fracture gap and how this affects the distraction resisting force (DRF) and muscle adaptation. A new distraction system was designed to continuously measure the DRF during tibial lengthening using a unilateral fixator. Measurements were made in 2 sheep for 51 days and 38 days respectively. The first sheep acquired 5cm (25% of its original length) of new bone with various rates of distraction. The second sheep acquired 3.8cm (15% of its original length) of new bone with 1mm/day fixed rate of distraction. During the lengthening procedure, the DRF steadily increased as the callus was being formed in the distraction gap. In sheep1 the lengthening rate was increased from 1mm/day to 1.25mm/day at the lengthening day 36 to manage what was interpreted to be signs of early premature consolidation. The DRF decreased to 310N from 400N at the lengthening day 43. Radiographs taken at day 43 showed separation in the callus. During the 1.25mm/day lengthening the sheep lost ankle joint movement completely. The major muscles, long digital extensor (LDE), cranial tibial (CT), gastrocnemius and deep digital flexor (DDF) were collected from the operated and non-operated hind limbs. The result showed that LDE and CT were damaged while gastrocnemius and DDF were intact. In sheep2, the distraction rate was maintained at 1mm/day and it showed a similar increase of DRF up to 550N at the end of distraction (lengthening day 38). There was no visible joint restriction observed. None of the four muscles collected showed signs of the profound tissue damage noted in sheep1. Comparison of the DRF profile with radiological interpretation confirmed that the degree of callus formation was appropriate at DRF of 300 ∼ 500N. Additionally the ability of the muscle to adapt to the given length could be affected by the time when the rate was changed. Additional studies are underway to determine the optimal regimen including appropriate rates and forces.Copyright