Development of a simple method to measure static body weight distribution in neurologically and orthopedically normal mature small breed dogs.

BACKGROUND: Objective outcome measures capable of tracking different aspects of functional recovery in dogs with acute intervertebral disc herniation are needed to optimize physical rehabilitation protocols. Normal, pre-injury distribution of body weight in this population is unknown. The aims of this study were to quantify static weight distribution (SWD) using digital scales and to establish the feasibility of different scale methods in neurologically normal, mature, chondrodystrophic small breed dogs predisposed to intervertebral disc herniation. RESULTS: Twenty-five healthy, mature dogs were enrolled with a mean age of 4.6 years (SD 2.7) and a mean total body weight of 11.5 kg (SD 3.6). SWD for the thoracic and pelvic limbs and between individual limbs was acquired in triplicate and expressed as a percentage of total body weight using commercially available digital scales in four combinations: two bathroom, two kitchen (with thoracic and pelvic limbs combined), four bathroom and four kitchen (with limbs measured individually). SWD was also obtained using a pressure sensing walkway for comparison to scale data. Feasibility for each method was determined and coefficients of variation were used to calculate inter-trial variability. Mean SWD values were compared between methods using an ANOVA. The two bathroom scales method had the highest feasibility and lowest inter-trial variability and resulted in mean thoracic and pelvic limb SWD of 63 % (SD 3 %) and 37 % (SD 3 %), respectively. Thoracic limb mean SWD was higher for the PSW compared to any of the scale methods (p < 0.0001). CONCLUSIONS: SWD in a population of healthy chondrodystrophic dogs was simple to obtain using inexpensive and readily available digital scales. This study generated SWD data for subsequent comparison to dogs recovering from acute intervertebral disc herniation.

A preliminary evaluation of the reliability of a modified functional scoring system for assessing neurologic function in ambulatory thoracolumbar myelopathy dogs.

BACKGROUND: The objective of this study was to develop and assess the reliability of a modified scoring system for evaluating the function of the two pelvic limbs separately, in ambulatory thoracolumbar myelopathy dogs. A previously established neurologic score scale for dogs with T3-L3 lesions was modified in order to provide a separate score for each pelvic limb. RESULTS: Seventeen ambulatory dogs with thoracolumbar myelopathies were evaluated. Using the new scale, two observers independently performed 22 observational gait analyses (OGAs) in ten dogs without videotape. Another 18 OGAs were performed in seven dogs by watching videotapes of them ambulating. There was poor agreement (concordance correlation coefficient, 0.87) between the two observers for all 40 OGAs. When stratified, the agreement was moderate (concordance correlation coefficient, 0.90) in the OGAs without videotaping and poor (concordance correlation coefficient, 0.80) for the OGAs based on videotapes. For the decision regarding which pelvic limb was more severely affected, a fair agreement (kappa value, 0.30) between the two observers was noted. Without videotape there was only slight agreement (kappa value, 0.05), but with videotape there was moderate agreement (kappa value, 0.56). CONCLUSIONS: The modified scoring system in this study provides moderate reliability in assessing the functional neurologic status of each pelvic limb, by OGA without videotape, in canine T3-L3 patients. Further development of this scoring system is required. However, imperfect agreement when visually quantifying neurological deficits is not unexpected.

Genome-wide survey indicates involvement of loci on canine chromosomes 7 and 31 in patellar luxation in Flat-Coated Retrievers.

BACKGROUND: Patellar luxation is an orthopedic disorder in which the patella moves out of its normal location within the femoral trochlea of the knee and it can lead to osteoarthritis, lameness, and pain. In dogs it is a heritable trait, with both environmental and genetic factors contributing to the phenotype. The prevalence of patellar luxation in the Dutch Flat-Coated Retriever population is 24%. In this study, we investigated the molecular genetics of the disorder in this population. RESULTS: Genome-wide association analysis of 15,823 single nucleotide polymorphisms (SNPs) in 45 cases and 40 controls revealed that patellar luxation was significantly associated with a region on chromosome CFA07, and possibly with regions on CFA03, CFA31, and CFA36. The exons of the genes in these regions, 0.5 Mb combined, were analyzed further. These exons from 15 cases and a pooled sample from 15 controls were enriched using custom genomic hybridization arrays and analyzed by massive parallel DNA sequencing. In total 7257 variations were detected. Subsequently, a selection of 144 of these SNPs were genotyped in 95 Flat-Coated Retrievers. Nine SNPs, in eight genes on CFA07 and CFA31, were associated with patellar luxation (P <10-4). Genotyping of these SNPs in samples from a variety of breeds revealed that the disease-associated allele of one synonymous SNP in a pseudogene of FMO6 was unique to Flat-Coated Retrievers. CONCLUSION: Genome-wide association analysis followed by targeted DNA sequencing identified loci on chromosomes 7 and 31 as being involved in patellar luxation in the Flat-Coated Retriever breed.

Biocompatibility of mussel-inspired water-soluble tissue adhesives.

Wound closure in surgeries is traditionally achieved using invasive methods such as sutures and staples. Adhesion-based wound closure methods such as tissue adhesives, sealants, and hemostats are slowly replacing these methods due to their ease of application. Although several chemistries have been developed and used commercially for wound closure, there is still a need for better tissue adhesives from the point of view of toxicity, wet-adhesion strength, and long-term bonding. Catechol chemistry has shown great promise in developing wet-set adhesives that meet these criteria. Herein, we have studied the biocompatibility of a catechol-based copolymer adhesive, poly([dopamine methacrylamide]-co-[methyl methacrylate]-co-[poly(ethylene glycol) methyl ether methacrylate]) or poly(catechol-MMA-OEG), which is soluble in water. The adhesive was injected subcutaneously in a mouse model on its own and in combination with a sodium periodate crosslinker. After 72 h, 4 weeks, and 12 weeks, the mice were euthanized and subjected to histopathological analysis. Both adhesives were present and still palpable at the end of 12 weeks. The moderate inflammation observed for the poly(catechol-MMA-OEG) cohort at 72 h had reduced to mild inflammation at the end of 12 weeks. However, the moderate inflammatory response observed for the poly(catechol-MMA-OEG) + crosslinker cohort at 72 h had not subsided at 12 weeks.

Prevalence of Work-Related Musculoskeletal Symptoms in Veterinary Surgeons-A Cross-Sectional Survey.

OBJECTIVES: The aim of this study was to determine the prevalence of work-related musculoskeletal symptoms (MSS) in veterinary surgeons using an online survey. STUDY DESIGN: An online survey was distributed to 1,031 diplomates of American College of Veterinary Surgeons. Responses were collected with data regarding surgical activities, experience with various types of MSS in 10 different body sites and attempts to reduce MSS. RESULTS: Two hundred and twelve respondents (21% response rate) completed the distributed survey in 2021. Ninety-three per cent of respondents had experienced MSS associated with surgery in at least one body part, with the neck, lower back and upper back frequently affected. Musculoskeletal discomfort and pain worsened with prolonged surgical hours. Forty-two per cent of them suffered from chronic pain persisting longer than 24 hours after surgeries. Musculoskeletal discomfort was common regardless of practice emphasis and procedure types. Forty-nine per cent of respondents with musculoskeletal pain had taken medication, 34% sought physical therapy for MSS and 38% ignored the symptoms. Over 85% of respondents showed more than some concern regarding career longevity due to musculoskeletal pain. CLINICAL SIGNIFICANCE: Work-related MSS are common in veterinary surgeons, and the results of this study warrant longitudinal clinical studies to determine risk factors and attention to workplace ergonomics in veterinary surgery.

Characterizing Exposure to Physical Risk Factors during Veterinary Surgery with Wearable Sensors: A Pilot Study.

OCCUPATIONAL APPLICATIONSVeterinarians provide comprehensive health services for animals, but despite exposure to similar occupational and safety hazards as medical physicians, physical risk factors for these doctors and healthcare teams have not been characterized. In this pilot study, we used wearable sensor technology and showed that veterinary surgeons commonly experience static and demanding postures while performing soft tissue and orthopedic surgeries. Observations showed that muscle activation was highest in the right trapezius. Job factors such as surgical role (attending vs. assisting) and surgical specialty (soft tissue vs. orthopedics) appeared to influence exposure to physical risk factors. These findings suggest a need to consider the unique demands of surgical specialties in order to address the key risk factors impacting injury risks among veterinarians. For example, static postures may be a priority for soft tissue surgeons, while tools that reduce force requirements are more pressing for orthopedic surgeons.

BACKGROUND: Although musculoskeletal fatigue, pain, and injuries are commonly reported among surgeons in veterinary medicine, few studies have objectively characterized the exposure to physical risk factors among veterinary surgeons. Purpose: This study aimed to characterize muscle activation and postures of the neck and shoulders during live veterinary surgeries in the soft tissue and orthopedic specialties. Methods: Forty-four ergonomic exposure assessments (exposures) were collected during 26 surgical procedures across five surgeons. Exposures were collected from both soft tissue (n = 23) and orthopedic (n = 21) specialties. Physical risk factors were characterized by: (1) directly measuring muscle activation and posture of the neck and shoulders, using surface electromyography and inertial measurement units, respectively; and (2) collecting self-reported workload, pain, and stiffness. Results: Across the 44 exposures, neck and back symptoms respectively worsened after the surgery in 27% and 14% of the exposures. Veterinary surgeons exhibited neck postures involving a mean of 17° flexion during the surgical procedures. Static postures were common, occurring during 53­80% of the procedures. Compared to soft tissue procedures (e.g., 13.2% MVC in the right trapezius), higher muscle activity was observed during orthopedic procedures (e.g., 27.6% MVC in the right trapezius). Conclusions: This pilot study showed that physical risk factors (i.e., muscle activity and posture of the neck/shoulder) can be measured using wearable sensors during live veterinary surgeries. The observed risk factors were similar to those documented for medical physicians. Further studies are needed to bring awareness to opportunities for improving workplace ergonomics in veterinary medicine and surgery.

Sheep as a Potential Model of Intradiscal Infection by the Bacterium Cutibacterium acnes.

The anaerobic bacterium Cutibacterium acnes has been increasingly linked to the development of degenerative disc disease (DDD), although causality is yet to be conclusively proven. To better study how this organism could contribute to the aetiology of DDD, improved animal models that are more reflective of human disc anatomy, biology and mechanical properties are required. Against this background, our proof-of concept study aimed to be the first demonstration that C. acnes could be safely administered percutaneously into sheep intervertebral discs (IVDs) for in vivo study. Following our protocol, two sheep were successfully injected with a strain of C. acnes (8.3 × 106 CFU/disc) previously recovered from a human degenerative disc. No adverse reactions were noted, and at one-month post inoculation all triplicate infected discs in our first animal grew C. acnes, albeit at a reduced load (5.12 × 104 to 6.67 × 104 CFU/disc). At six months, no growth was detected in discs from our second animal indicating bacterial clearance. This pilot study has demonstrated the feasibility of safe percutaneous injection of C. acnes into sheep IVDs under fluoroscopic guidance. The design of follow-up sheep studies to investigate the potential of C. acnes to drive pathological changes within infected discs should now be pursued.

The Effect of Increasing Fracture Site Stiffness on Bone-Pin Interface Stress and Foot Contact Pressure within the Equine Distal Limb Transfixation Cast: A Finite Element Analysis.

OBJECTIVE: The aim of this study was to determine how increasing stiffness of fracture site tissues distal to the pins in an equine distal limb transfixation cast influences stress at the bone-pin interface, within the bones distal to the transcortical pins, and contact pressure between the foot and the cast. STUDY DESIGN: A transfixation cast finite element model was used to compare the bone-pin interface stress, pin stress, bone stress distal to the pins and contact pressure between the foot and the cast, using six stiffness values for a composite tissue block representing progressive stages of fracture healing. RESULTS: Increasing stiffness of the composite tissue block resulted in a decrease in the maximum stresses at the bone-pin interface, an increase in stresses distal to the transcortical pins and a decrease in the maximum pin stresses. As the composite tissue block stiffness was increased, contact pressure between the bottom of the composite tissue block and the cast increased and the stress patterns surrounding the pin holes became less focal. CONCLUSION: The findings of this study illustrate that with good foot to cast contact within a transfixation cast, increases in tissue stiffness due to progressive fracture healing are expected to reduce bone-pin interface stresses, and increase fracture site loading and stress. Increasing the contact pressure between the foot and the cast could reduce transfixation casting complications such as pin loosening, pin hole fracture and poor fracture healing, if these results transfer to ex vivo and in vivo settings.

Finite Element Analysis of Six Transcortical Pin Parameters and Their Effect on Bone-Pin Interface Stresses in the Equine Third Metacarpal Bone.

OBJECTIVE: The objectives of this study were to validate a finite element model of the equine distal limb transfixation cast and to determine the effect of six transcortical pin parameters on bone-pin interface (BPI) stresses in the third metacarpal bone. STUDY DESIGN: A transfixation cast finite element model was developed from a computed tomography scan of the third metacarpal bone and modelled pin elements. The model was validated by comparing strain measured around a 6.3-mm transfixation pin in the third metacarpal bone with the finite element model. The pin parameters of diameter, number, location, spacing, orientation and material were evaluated by comparing a variety of pin configurations within the model. RESULTS: Pin diameter and number had the greatest impact on BPI stress. Increasing the diameter and number of pins resulted in lower BPI stresses. Diaphyseal pin location and stainless-steel pins had lower BPI stresses than metaphyseal location and titanium alloy pins, respectively. Offset pin orientation and pin spacing had minimal impact on BPI stresses during axial loading. CONCLUSION: The results provide evidence that diameter and number are the main pin parameters affecting BPI stress in an equine distal limb transfixation cast. Configurations of various pin size and number may be proposed to reduce BPI stresses and minimize the risk of pin related complications. Further refinement of these models will be required to optimize pin configurations to account for pin hole size and its impact on overall bone strength.

Collagen Type I and II Blend Hydrogel with Autologous Mesenchymal Stem Cells as a Scaffold for Articular Cartilage Defect Repair.

Collagen type II is a promising material to repair cartilage defects since it is a major component of articular cartilage and plays a key role in chondrocyte function. This study investigated the chondrogenic differentiation of bone marrow-derived mesenchymal stem cells (MSCs) embedded within a 3:1 collagen type I to II blend (Col I/II) hydrogel or an all collagen type I (Col I) hydrogel. Glycosaminoglycan (GAG) production in Col I/II hydrogels was statistically higher than that in Col I hydrogels or pellet culture, and these results suggested that adding collagen type II promoted GAG production. Col I/II hydrogels had statistically lower alkaline phosphatase (AP) activity than pellets cultured in a chondrogenic medium. The ability of MSCs encapsulated in Col I/II hydrogels to repair cartilage defects was investigated by creating two cartilage defects in the femurs of rabbits. After 13 weeks, histochemical staining suggested that Col I/II blend hydrogels provided favorable conditions for cartilage repair. Histological scoring revealed a statistically higher cartilage repair score for the Col I/II hydrogels compared to either the Col I hydrogels or empty defect controls. Results from this study suggest that there is clinical value in the cartilage repair capabilities of our Col I/II hydrogel with encapsulated MSCs.

Transference of reference intervals for variables of instrumented gait analysis in walking dogs.

OBJECTIVE: To use the small data approach of the Clinical and Laboratory Standards Institute (CLSI) to evaluate the transferability of reference intervals (RIs) for kinetic variables obtained with instrumented gait analysis (IGA) in dogs from an RI-originator laboratory to another laboratory that used the same data acquisition and analytic techniques for IGA in walking dogs. ANIMALS: 27 adult client-owned dogs without evidence of lameness. PROCEDURES: Dogs were individually walked at their preferred velocity on a pressure-sensing walkway for IGA at the Colorado State University Animal Gait Laboratory (CSU-AGL), and 6 valid trials were analyzed for each dog. The small data approach of the CLSI was then used to evaluate transferability of RIs previously established at the Purdue University Animal Gait Laboratory (PU-AGL). A linear model was used to establish weight-dependent RIs for peak vertical force (PVF). RESULTS: Results indicated that RIs of dynamic weight distribution (DWD), DWD symmetry index, DWD coefficient of variation, PVF symmetry index, and PVF coefficient of variation were transferable from PU-AGL to CSU-AGL, whereas the weight-dependent RIs for PVF were not. Regression slopes for PVF versus body weight were greater for all limbs in dogs tested at the CSU-AGL, compared with historic results for dogs tested at the PU-AGL. CONCLUSIONS AND CLINICAL RELEVANCE: Use of the small data approach method of the CLSI to validate transference of RIs for IGA kinetic variables in walking dogs was simple and efficient to perform and may help facilitate clinical and research collaborations on gait analysis.

Slipped capital femoral epiphysis.

Slipped capital femoral epiphysis (SCFE) is a common adolescent hip disorder. The etiology of SCFE includes biomechanical and biochemical factors. SCFEs are classified as stable and unstable and are more common in boys than girls and in certain racial groups; most children with SCFEs are obese. Bilateral SCFEs may have a simultaneous or sequential presentation. Imaging studies show a posterior slip of the epiphysis relative to the metaphysis, seen early on lateral radiographs. The most common and effective initial treatment for stable SCFEs is in situ central single-screw fixation; other options include epiphysiodesis, and osteotomy with or without surgical dislocation of the hip. Later reconstruction options, typically reserved for the child with functional abnormalities, include proximal femoral osteotomy, or surgical dislocation of the hip with removal of metaphyseal prominent bone to remove the source of femoroacetabular impingement. Unstable SCFEs have an increased risk of osteonecrosis; the role of reduction, methods of fixation, and decompression are controversial. The natural history of untreated SCFEs is associated with the risk of progression and later degenerative joint disease. Based on treatment methods of 30 to 40 years ago, in situ fixation provided the best long-term function with the lowest risk of complications and the most effective delay of degenerative arthritis regardless of the severity of the SCFE. Newer technologies and techniques are allowing the reevaluation of the role of either acute or later reconstructive osteotomy. It has not yet been determined if these improved techniques will result in better outcomes than in the past. Surgical dislocation of the hip with epiphyseal orientation is a considered treatment option for those technically adept at the procedure; however, the long-term outcome compared with in situ fixation is still unknown.

Temporospatial and kinetic characteristics of sheep walking on a pressure sensing walkway.

The walking gait of sheep was analyzed in terms of temporospatial and kinetic parameters and weight distribution among the 4 limbs. Eighteen mature female Suffolk-mix sheep walked comfortably with a halter-guide over a 1.5-m pressure sensing walkway. Six valid trials were acquired for each sheep without any previous selection or habituation. Stance phases of the forelimb and hind limb were 66.3% and 68.9%, respectively, of total gait cycle, and limb velocity was 1.06 m/s in both forelimbs and hind limbs while walking. The mean peak vertical force (PVF) and vertical impulse (VI) as percentage of body weight in the forelimbs were 52.5% and 19.9%, respectively, and those of the hind limbs were 38.5% and 14.9%, respectively. More body weight was loaded on the forelimbs than the hind limbs, at 59% and 41% of body weight, respectively. The walking gait of sheep measured with the pressure sensing (PS) walkway was similar to that reported in dogs and horses. The PS walkway enabled collection of temporospatial and kinetic data, and simplified the process of data collection.

Comparison of two-dimensional and three-dimensional systems for kinematic analysis of the sagittal motion of canine hind limbs during walking.

OBJECTIVE: To test the hypotheses that kinematic data of the sagittal motion of canine hind limbs during walking obtained with a 2-dimensional (2-D) system correlate well with those obtained with a 3-dimensional (3-D) system and that the data obtained with the 2-D system are repeatable. ANIMALS: 6 adult dogs with no evidence of lameness. PROCEDURES: Hind limb motions of 6 walking dogs were recorded via 2-D video and 3-D optoelectric systems simultaneously. Five valid trials were digitized, and 5 data sets (2-D 60 Hz, 3-D 180 Hz, 3-D sagittal 180 Hz, 3-D 60 Hz, and 3-D sagittal 60 Hz) of a complete gait cycle were created for each dog. In sagittal data sets, 3-D data were reduced to exclude coordinates for mediolateral orientation. Temporospatial parameters; angles of hip, stifle, and tarsal joints; and coefficients of variation of angular measurements of each dog were calculated for each data set. Accuracy of the 2-D analysis was determined by calculating mean absolute differences and estimating agreement between the 2-D and 3-D 180-Hz data sets. RESULTS: Values of joint angles and angular excursions measured with the 2-D system were repeatable and agreed with respective values obtained with the 3-D system. Reduction of the sampling rate had a greater impact on values of kinematic variables obtained with the 3-D system than did elimination of data on mediolateral orientation. CONCLUSIONS AND CLINICAL RELEVANCE: Kinematic analysis using a 2-D video system provided accurate and repeatable data of the sagittal angular motion of canine hind limbs during walking.

Effects of a surgical sealant on leakage pressure and circumference of fresh canine cadaver small intestinal anastomoses.

OBJECTIVE To evaluate the effect of a bovine albumin-derivatized glutaraldehyde (BA-DG) biopolymer sealant on leakage pressures of intestinal anastomoses in jejunal tissue collected from fresh canine cadavers and to evaluate changes in circumference and cross-sectional area of the anastomotic site resulting from sealant application. SAMPLE 24 jejunal anastomoses from 4 fresh canine cadavers. PROCEDURES Jejunal tissue specimens were collected, and adjacent segment anastomoses were created within 12 hours after euthanasia of each dog. The tissue constructs were randomly assigned to 1 of 2 groups in which sealant was or was not applied. The outer circumference of all anastomoses in the sealant group was measured before and after application of the sealant; the cross-sectional area at the anastomotic site was then calculated at each time point. Tissue constructs were pressure tested, and leakage pressure and site were recorded. All testing was completed within 24 hours after tissue collection. RESULTS Compared with preapplication findings, there were no significant changes in outer circumference or cross-sectional area at the anastomotic site after sealant application. Leakage pressures in the sealant group were significantly higher than those in the no-sealant group. CONCLUSIONS AND CLINICAL RELEVANCE The use of surgical sealant on fresh canine cadaver jejunal anastomoses resulted in significantly higher leakage pressure at the anastomotic site; no immediate tissue deformation of the outer circumference or cross-sectional area occurred after sealant application. Future in vivo investigations are warranted to evaluate the effects of this sealant and potential benefits for clinical patients undergoing enterectomy.

In Vivo Evaluation of Biodegradability and Biocompatibility of Fe30Mn Alloy.

OBJECTIVES: This study aims to evaluate the biodegradability and biocompatibility of an alloy of iron and manganese (Fe30Mn) in a bone model in vivo. METHODS: Resorption of a Fe30Mn wire was compared with traditional permanent 316L stainless steel (SS) wire after bilateral transcondylar femoral implantation in 12 rats. Evaluation of biodegradation over 6 months was performed using radiography, post-mortem histology and microscopic implant surface analysis. RESULTS: Corrosion and resorption of the novel iron-manganese implant with formation of an iron oxide corrosion layer was noted on all post-mortem histological sections and macroscopic specimens (corrosion fraction of 0.84 and 0 for Fe30Mn and 316L SS, respectively). Increased bone ongrowth was observed at the wire-bone interface (bone ongrowth fraction of 0.61 and 0.34 for Fe30Mn and 316L SS, respectively). Occasionally, poorly stained newly formed bone and necrotic bone in contact with corrosion was seen. In bone marrow, Fe30Mn alloy was scored as a mild local irritant compared with 316L SS (biocompatibility score of 8.8 and 5.3, respectively). There was no evidence of systemic adverse reaction. CLINICAL SIGNIFICANCE: Resorbable iron-manganese alloys may offer a promising alternative to permanent metallic implants. Further in vivo studies to control implant resorption at a rate suitable for fracture healing and to confirm the biocompatibility and biosafety of the resorbable Fe30Mn metallic implant are necessary prior to use in clinical settings.

Evaluation of 25% Poloxamer As a Slow Release Carrier for Morphine in a Rat Model.

The objectives of this study were to evaluate poloxamer as a slow release carrier for morphine (M) and potential tissue irritation after subcutaneous poloxamer-morphine (PM) injection in a rat model. Based on the result of a previous in vitro work, 25% poloxamer, with and without morphine, and saline were administered in 14 rats' flanks. Blood for morphine concentrations was automatically sampled at multiple preprogrammed time points using the Culex™ unit for 48 h. Skin tissues from the injection sites were harvested and evaluated for histopathological changes. Following M or PM administration, it was determined that the half-life (t1/2) was significantly longer in the PM (5.5 ± 7.2 h) than M (0.7 ± 0.8 h) indicated a slow dissolution of poloxamer with morphine. The tmax was within 15 min and Cmax was approximately three times higher with M than with PM, reaching 716.8 (±153.7 ng/ml) of plasma morphine concentrations. There was no significant difference in total area under the curve and clearance of M versus PM. Histology inflammatory scores were similar between M, PM, and poloxamer but were significantly higher than saline control. We concluded that 25% poloxamer was capable of increasing the t1/2 of morphine, without a significant tissue irritation.

Evaluation of a cross-linked acellular porcine dermal patch for rotator cuff repair augmentation in an ovine model.

In this study we evaluated 2 commercially available rotator cuff repair augmentation patches in an in vivo sheep model using mechanical testing and histologic techniques. Bilateral infraspinatus tears were created and repaired in 2 groups of 8 adult ewes. Each group (killed at 9 or 24 weeks) included 5 repaired with suture alone, 6 repaired and augmented with a cross-linked acellular porcine dermal (PD) patch (Zimmer Collagen Repair Patch), and 5 repaired and augmented with a porcine small intestine submucosa (SIS) patch (Restore Orthobiologic Soft Tissue Implant; DePuy Orthopaedics). At 3 weeks, sheep with suture repair and an SIS patch had significant elevation of plasma fibrinogen levels (P < .05) whereas sheep with suture repair and a PD patch elicited no elevation in plasma fibrinogen levels. At 9 weeks, the mean failure load was 201 +/- 60 lb for suture repairs, 182 +/- 63 lb for PD repairs, and 137 +/- 16 lb for SIS repairs. Within any individual sheep, the shoulder undergoing PD repair always had a higher failure load than the contralateral suture or shoulder undergoing SIS repair. At 9 weeks, macrophages were seen on all PD surfaces whereas most of the SIS materials were resorbed. At 24 weeks, failure loads were identical between groups. Macrophages had disappeared from the PD groups, and integration of the PD patch into the surrounding tissue with vascular and fibroblastic invasion was seen. For the SIS group, diverse tissue types (including ectopic bone) were seen.

Determination of baseline bone mineral density using dual energy X-ray absorptiometry in Suffolk-Dorset hybrid ewes.

Dual energy x-ray absorptiometry (DEXA) has the ability to rapidly and non-invasively measure bone mineral density and is the most widely accepted method for quantitative assessment of bone mineral status in vivo. There is scarce information available on the baseline bone mineral density (BMD) values in adult intact Suffolk Dorset ewes (5-7 years), a frequently used animal model for the study of post-menopausal osteoporosis. The objective of the present study was to determine the baseline bone mineral density values in 26 adult intact Suffolk-Dorset hybrid ewes using a Lunar Prodigy DPX x-ray bone densitometer. The DEXA scans of the femur, lumbar spine (L3-L6) and calcaneus were obtained. Because of the low variability between the scans for the lumbar vertebrae and calcaneus in the first two animals, only two scans were obtained for the remaining animals of the study. The femoral scans were rejected due to high variability between the scans. The BMD was calculated using the standard GE antero-posterior human spine acquisition software. The bone mineral densities of regions of interest (ROIs) were compared by the Bonferroni significant difference technique. The results of the study demonstrated that the BMD progressively reduced from L3 to L6 and a strong correlation was found between the BMD values for the ROIs from L3 to L6. The present study provided a precise and rapid method for measuring the BMD of the lumbar spine in Suffolk-Dorset breed of sheep and recorded reference values in adult sheep.

Slipped capital femoral epiphysis: current concepts.

Slipped capital femoral epiphysis is a common hip disorder in adolescents, with an incidence of 0.2 (Japan) to 10 (United States) per 100,000. The etiology is unknown, but biomechanical and biochemical factors play an important role. Symptoms at presentation include pain in the groin, thigh, or knee. Ambulatory patients also may present with a limp. Nonambulatory patients present with excruciating pain. The slipped capital femoral epiphysis is classified as stable when the patient can walk and unstable when the patient cannot walk, even with the aid of crutches. Because the epiphysis slips posteriorly, it is best seen on lateral radiographs. The treatment of choice for stable slipped capital femoral epiphysis is single-screw fixation in situ. This method has a high probability of long-term success, with minimal risk of complications. In the patient with unstable slipped capital femoral epiphysis, urgent hip joint aspiration followed by closed reduction and single- or double-screw fixation provides the best environment for a satisfactory result, while minimizing the risk of complications.