Michael G. Conzemius

In vitro antibacterial properties of magnesium metal against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus

Bacterial infections are a costly sequela in any wound. The corrosion properties of 0.15, 0.30, 0.45 and 0.60 g of Mg metal were determined in Mueller-Hinton broth by serially measuring the Mg(2+) concentrations and pH over 72 h. In addition, the effect of Mg metal, increased Mg(2+) concentration and alkaline pH on the in vitro growth of Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus were evaluated in three separate experiments. The primary outcome measure for culture studies was colony-forming units/ml compared to appropriate positive and/or negative controls. Regardless of the mass of Mg added, there was a predictable increase in pH and Mg(2+) concentration. The addition of Mg and an increase of pH resulted in antibacterial effects similar to the fluoroquinolone antibiotic; however, a simple increase in Mg(2+) concentration alone had no effect. The results demonstrate an antibacterial effect of Mg on three common aerobic bacterial organisms, the mechanism of which appears to be an alkaline pH.

Relationship between objective and subjective assessment of limb function in normal dogs with an experimentally induced lameness

OBJECTIVE To evaluate the relationship between previously used subjective and objective measures of limb function in normal dogs that had an induced lameness. STUDY DESIGN Prospective, blinded, and induced animal model trial. ANIMALS Normal, adult, and mixed-breed dogs (n=24) weighing 25-35 kg. METHODS Force platform gait analysis was collected in all dogs before and after induction of lameness. All gait trials were videotaped; 60 video trials were evaluated by 3 surgeons with practice limited to small animal orthopedics and 3 first year veterinary students in an effort to establish the relationship between subjective and objective measures of lameness. Evaluators were unaware of the force platform data. RESULTS Concordance coefficients were low for all observers and were similar between students and surgeons. These values were further decreased when normal and non-weight bearing trials were removed. Agreement with the force platform data was low even when observers only had to be within +/-10% of the ground reaction forces. When repeat trials were evaluated surgeons had a much higher repeatability compared with students. CONCLUSIONS Subjective evaluation of the lameness in this study varied greatly between observers and agreed poorly with objective measures of limb function. CLINICAL RELEVANCE Subjective evaluation of gait should be interpreted cautiously as an outcome measure whether performed from a single or from multiple observers.

Proposed Definitions and Criteria for Reporting Time Frame, Outcome, and Complications For Clinical Orthopedic Studies in Veterinary Medicine

Outcome, and Complications For Clinical Orthopedic Studies in Veterinary Medicine James L. Cook, DVM, PhD, Diplomate ACVS, Richard Evans, PhD, Michael G. Conzemius, DVM, PhD, Diplomate ACVS, B. Duncan X. Lascelles, BVSc, PhD, Diplomate ECVS, Diplomate ACVS, C. Wayne McIlwraith, BVSc, PhD, Diplomate ACVS, Antonio Pozzi, DMV, MS, Diplomate ACVS, Peter Clegg, MA, VetMB, PhD, Diplomate ECVS, MRCVS, John Innes, BVSc, PhD, DSAS (Orth), MRCVS, Kurt Schulz, DVM, Diplomate ACVS, John Houlton, MA, VetMB, DVR, DSAO, MRCVS, Diplomate ECVS, Lisa Fortier, DVM, PhD, Diplomate ACVS, Alan R. Cross, DVM, Diplomate ACVS, Kei Hayashi, DVM, PhD, Diplomate ACVS, Amy Kapatkin, DVM, MS, Diplomate ACVS, Dorothy Cimino Brown, DVM, MSCE, Diplomate ACVS, and Allison Stewart, DVM, MS, Diplomate ACVS Comparative Orthopaedic Laboratory, University of Missouri, Columbia, MO, College of Veterinary Medicine, University of Illinois, Urbana, IL, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, Comparative Pain Research Laboratory, North Carolina State University,

Caregiver placebo effect for dogs with lameness from osteoarthritis.

OBJECTIVE To document the caregiver placebo effect in owners and veterinarians of dogs with lameness from osteoarthritis. DESIGN Prospective, randomized, double-blinded, placebo-controlled, multicenter clinical trial. ANIMALS 58 dogs with lameness secondary to osteoarthritis. PROCEDURES Dogs enrolled in the placebo arm of an FDA-approved study were evaluated to determine the relationship between subjective (caregiver responses) and objective (force platform gait analysis) patient outcome measures. RESULTS A caregiver placebo effect for owners evaluating their dogs lameness occurred 39.7% of the time. A caregiver placebo effect occurred 44.8% of the time when veterinarians examined dogs for lameness at a walk, 44.8% of the time when veterinarians examined dogs for lameness at a trot, and 43.1% of the time when veterinarians evaluated dogs for signs of pain on palpation of the joint. This effect was significantly enhanced with time. Mean ground reaction forces (GRFs) remained unchanged for dogs during treatment with the placebo. Individually, of 58 dogs, 5 had GRFs that worsened by ≥ 5% over 42 days, 7 had GRFs that improved by ≥ 5% over 42 days, and 46 had GRFs that remained unchanged. CONCLUSIONS AND CLINICAL RELEVANCE A caregiver placebo effect was common in the evaluation of patient response to treatment for osteoarthritis by both pet owners and veterinarians. Force platform gait analysis was an unbiased outcome measure for dogs with lameness from osteoarthritis. A caregiver placebo effect should be considered when interpreting owner and veterinary reports of patient response to treatment.

Hip Joint Contact Force in the Emu (Dromaius novaehollandiae) during Normal Level Walking

The emu is a large, (bipedal) flightless bird that potentially can be used to study various orthopaedic disorders in which load protection of the experimental limb is a limitation of quadrupedal models. An anatomy-based analysis of normal emu walking gait was undertaken to determine hip contact forces for comparison with human data. Kinematic and kinetic data captured for two laboratory-habituated emus were used to drive the model. Muscle attachment data were obtained by dissection, and bony geometries were obtained by CT scan. Inverse dynamics calculations at all major lower-limb joints were used in conjunction with optimization of muscle forces to determine hip contact forces. Like human walking gait, emu ground reaction forces showed a bimodal distribution over the course of the stance phase. Two-bird averaged maximum hip contact force was approximately 5.5 times body weight, directed nominally axially along the femur. This value is only modestly larger than optimization-based hip contact forces reported in literature for humans. The interspecies similarity in hip contact forces makes the emu a biomechanically attractive animal in which to model loading-dependent human orthopaedic hip disorders.

Short-term and long-term outcomes for overweight dogs with cranial cruciate ligament rupture treated surgically or nonsurgically

OBJECTIVE To determine short- and long-term rates of successful outcomes of surgical and nonsurgical treatments for overweight dogs with cranial cruciate ligament rupture (CCLR). DESIGN Prospective, randomized, clinical trial. Animals-40 client-owned overweight dogs with unilateral CCLR. PROCEDURES Dogs were randomly assigned to nonsurgical (physical therapy, weight loss, and NSAID administration) or surgical (tibial plateau leveling osteotomy) treatment groups; dogs in both groups received the same nonsurgical treatments. Dogs were evaluated immediately before and 6, 12, 24, and 52 weeks after initiation of treatments via owner questionnaires, gait analysis, and dual-energy x-ray absorptiometry. A successful outcome was defined as an affected limb net ground reaction force > 85% of the value for healthy dogs and a ≥ 10% improvement in values of questionnaire variables. RESULTS Owner questionnaire responses indicated dogs in both groups improved during the study, but dogs in the surgical treatment group seemed to have greater improvement. Body fat percentages for dogs in both treatment groups significantly decreased during the study. Surgical treatment group dogs had significantly higher peak vertical force for affected limbs versus nonsurgical treatment group dogs at the 24- and 52-week evaluation times. Surgical treatment group dogs had a higher probability of a successful outcome (67.7%, 92.6%, and 75.0% for 12-, 24-, and 52-week evaluations, respectively) versus nonsurgical treatment group dogs (47.1%, 33.3%, and 63.6% for 12-, 24-, and 52-week evaluations, respectively). CONCLUSIONS AND CLINICAL RELEVANCE Overweight dogs with CCLR treated via surgical and nonsurgical methods had better outcomes than dogs treated via nonsurgical methods alone. However, almost two-thirds of the dogs in the nonsurgical treatment group had a successful outcome at the 52-week evaluation time.

Focal cryogen insults for inducing segmental osteonecrosis: computational and experimental assessments of thermal fields

Orthopaedic management of femoral head osteonecrosis is a common clinical problem for which there presently is no good solution. Current animal models are inappropriate to study potential new solutions, since it has been difficult to replicate the natural history of structural collapse seen in the human disorder. Recently, progression to collapse was obtained for cryogenically induced osteonecrosis in emus, although the lesions involved were imprecisely controlled in terms of size or location. A new cryo-insult probe is here reported for the purpose of delivering well-prescribed local thermal insults in this new animal model, while minimizing damage to non-targeted regions. Finite element analysis was used to elucidate the influence of operator-controlled parameters upon the temporal/spatial variation of the thermal field. The numerical formulation includes convective heat transfer attributable to tissue bed perfusion. The computational results agreed closely with the results of thermocouple recordings in a companion bench-top experiment. The cryo-insult probe successfully produced segmental lesions in the emu model of sizes comparable to the computed freeze front diameters.

Comparison of the analgesic efficacy of perioperative firocoxib and tramadol administration in dogs undergoing tibial plateau leveling osteotomy

OBJECTIVE To evaluate the effects of perioperative oral administration of tramadol, firocoxib, and a tramadol-firocoxib combination on signs of pain and limb function after tibial plateau leveling osteotomy in dogs. DESIGN Randomized, blinded, prospective clinical trial. ANIMALS 30 adult client-owned dogs with unilateral cranial cruciate ligament disease. PROCEDURES Dogs were allocated into 3 treatment groups (tramadol, firocoxib, and a tramadol-firocoxib combination). Signs of pain (short-form Glasgow composite measure pain scale), serum cortisol concentrations, and limb function (pressure platform gait analysis) were recorded at several time points before surgery and through 3 days after surgery. Outcome measures were compared among groups. RESULTS A significantly greater number of dogs in the tramadol group (8/10 dogs) had a pain score > 6 after surgery, compared with the other groups. No significant differences were detected in the pain scores between the firocoxib and the tramadol-firocoxib combination groups. There were no significant differences in serum cortisol concentrations among the 3 groups. Limb function was significantly decreased for dogs in the tramadol group on days 1 and 2 after surgery and in the firocoxib group on day 1 after surgery. Although limb function decreased for dogs in the tramadol-firocoxib combination group, the change was not significant for any day after surgery. CONCLUSIONS AND CLINICAL RELEVANCE Dogs that received firocoxib orally, alone or in combination with tramadol, had lower pain scores, lower rescue opiate administration, and greater limb function than dogs that received only tramadol. When used alone, oral administration of tramadol may not provide sufficient analgesic efficacy to treat dogs with pain after orthopedic surgical procedures.

Mechanical Testing of Orthopedic Suture Material Used for Extra‐Articular Stabilization of Canine Cruciate Ligament‐Deficient Stifles

OBJECTIVE To determine (1) if braided, polyblend orthopedic suture materials are mechanically superior to monofilament nylon leader and (2) have mechanical properties similar to biomechanical properties of the canine cruciate ligament. SAMPLE POPULATION Different suture material types. METHODS Mechanical testing was performed on 5 different orthopedic suture materials: 80# test Mason monofilament nylon leader (MNL), FiberTape (FT), FiberWire (FW), Xgen OrthoFiber (XOF), and LigaFiba (LF) using a servohydraulic materials-testing machine. Materials were loaded to failure while collecting data for tensile strength, load at 3 mm and 5 mm of elongation and stiffness. Cyclic elongation of each suture material was tested under physiologic loading between 70 and 150 N for 1000 cycles using 3 mm of elongation to describe excessive elongation. Load at 3 mm of elongation and performance during cyclic testing were compared to previously published physiologic loads in the dog stifle. RESULTS Ultimate tensile strength was greatest with LF, followed by XOF that was stronger than FT and FW, and the weakest was MNL. LF was the stiffest of all tested materials at 3 mm of elongation. Cyclic elongation was greatest for the MNL elongating 3.75 mm after 1000 cycles. All polyblend braided materials continued to elongate throughout the 1000 cycles under physiologic loads. CONCLUSIONS Polyblend suture materials are stronger and elongate less than MNL in pure tension. The mechanical performance of all sutures tested is questionable when compared with the mechanical demands of the normal stifle in a mid-sized dog.

Comparison of three methods for the management of fragmented medial coronoid process in the dog - A systematic review and meta-analysis

The objective of this review and analysis was to compare arthroscopy, medial arthrotomy and medical management for treating fragmented coronoid process in the dog. The data come from manuscripts published in peer-reviewed veterinary journals, and the study design is a systematic review followed by meta-analysis. The meta-analysis combines data from a set of studies so that surgical techniques and medial management can be compared in a single analysis. Several literature databases and veterinary texts were thoroughly searched to provide a list of over 400 candidate manuscripts. Inclusion criteria were used to filter the candidate manuscripts to a final set of four manuscripts that directly pertained to the clinical question. They were scored for their evidentiary value using a semi-objective measure. The results were that arthroscopy was superior to medial arthrotomy and medical management, but medial arthrotomy was not superior to medical management. Only one manuscript was a randomized controlled trial, hence the results must be tempered by the evidentiary value of the data.