Minimally invasive application of a radial plate following placement of an ulnar rod in treating antebrachial fractures. Technique and case series.

OBJECTIVE: To describe a surgical technique for placement of a minimally invasive radial plate following application of an ulnar rod (MIPR) for treatment of antebrachial fractures. METHODS: Medical records (November 2005-June 2009) were searched to identify dogs with diaphyseal radius and ulna fractures stabilised by MIPR. Data retrieved included signalment, weight, limb affected, cause of injury, open versus closed fracture, number of fragments, implant size, number of screws used and cortices engaged, number of open screw holes, operative time, rod removal, complications and time to radiographic healing. To be included, dogs had to have evidence of radiographic healing during follow-up. RESULTS: Eight dogs with diaphyseal radius and ulna fractures treated with MIPR were included in the case series. All fractures were due to trauma and two fractures were open (grade 1). Rod loosening and osteomyelitis of the ulna occurred in one case which subsequently resolved with rod removal. Healing occurred in all cases with no implant failures. Median time to radiographic union was 10.5 weeks (mean ± SD = 17 ± 15 weeks; range 4-52 weeks). CLINICAL RELEVANCE: Use of MIPR constructs on diaphyseal fractures of the radius and ulna is an effective technique for managing these fractures using principles of biological osteosynthesis. An intramedullary rod in the ulna assists with fracture reduction and stabilisation and rod removal is recommended once fracture healing has occurred.

Arthroscopic treatment of osteochondritis dissecans of the shoulder in 126 dogs.

Osteochondritis dissecans of the shoulder joint was treated by arthroscopy in 126 dogs. Twenty-four dogs had bilateral surgery, making a total of 150 joints treated. The OCD flaps were removed in small pieces through the cannula or in a single piece through a stab incision. The lameness resolved completely within seven-60 days following arthroscopy in 137 out of 150 affected limbs. Within a subset of 47 dogs with unilateral OCD, it was found that lesions located on the caudo-medial region of the humeral head had a better functional outcome than those lesions located in the caudo-central region of the humeral head.

Concentrations of chondroitin sulfate epitopes 3B3 and 7D4 in synovial fluid after intra-articular and extracapsular reconstruction of the cranial cruciate ligament in dogs.

OBJECTIVE: To evaluate effects of intra-articular and extracapsular reconstruction of the cranial cruciate ligament (CCL) on metabolism of articular cartilage as reflected by concentrations of chondroitin sulfate epitopes 3B3 and 7D4 in synovial fluid. ANIMALS: 13 adult dogs. PROCEDURE: Each dog underwent unilateral CCL transection (CCLT). One month after CCLT, sham CCL reconstruction (3 dogs), intra-articular CCL reconstruction (5), or extracapsular CCL reconstruction (5) was performed. Synovial fluid was collected by direct arthrocentesis from CCLT and contralateral stifle joints immediately before (time 0) and 1, 3, and 5 months after CCLT. Fluid was examined for concentrations of 3B3 and 7D4 epitopes and total sulfated glycosaminoglycan (GAG) content. RESULTS: Concentrations of 3B3, 7D4, and GAG, 3B3:GAG, or 7D4:GAG in CCLT joints did not differ significantly among treatment groups nor in the ratios of these variables in CCLT joints to contralateral joints at 3 months. In a longitudinal analysis, concentrations of 3B3 and 7D4, 3B3:GAG, and 7D4:GAG in CCLT joints in all groups changed significantly with time, but we did not detect time X group interactions. CONCLUSIONS AND CLINICAL RELEVANCE: Transection of CCL resulted in significant perturbation in articular cartilage metabolism as reflected by alterations in concentrations of 3B3 and 7D4 in synovial fluid. These changes over time were not significantly influenced by method of CCL reconstruction. We did not find evidence that surgical stabilization of CCL-deficient joints by intra-articular or extracapsular techniques had any effect on preventing alterations in composition of synovial fluid that have been associated with secondary osteoarthritis.

Effects of an orally administered mixture of chondroitin sulfate, glucosamine hydrochloride and manganese ascorbate on synovial fluid chondroitin sulfate 3B3 and 7D4 epitope in a canine cruciate ligament transection model of osteoarthritis.

OBJECTIVE: To evaluate effects of an orally administered mixture of chondroitin sulfate, glucosamine hydrochloride and manganese ascorbate (CS-G-M) on articular cartilage metabolism in dogs with cranial cruciate ligament (CCL) deficient and reconstructed knees, as reflected by concentrations of synovial fluid 3B3, 7D4 and total sulfated glycosaminoglycan (GAG). METHODS: Sixteen adult dogs that underwent unilateral CCL transection were randomized into four groups. Thereafter, group I (N=3) had a sham CCL reconstruction, group II (N=3) had CS-G-M and sham CCL reconstruction, group III (N=5) had CCL reconstruction, and group IV (N=5) had CS-G-M and CCL reconstruction. Synovial fluid collected at 0, 1, 3 and 5 months was examined by ELISA for 3B3 and 7D4 epitope, and by DMMB assay for total GAG. RESULTS: Synovial fluid from CCL transected knees of CS-G-M treated dogs contained significantly elevated concentrations of 3B3 (P=0.029), 7D4 (P=0.036) and 7D4/GAG (P=0.007) in comparison to controls, in a cross-sectional analysis at 3 months. Furthermore, 7D4 and 7D4/GAG concentrations remained significantly elevated (P=0.012) in CCL transected knees of CS-G-M treated dogs over the 5 month period. However, when epitope concentrations were expressed as a ratio of CCL-transected to contralateral non-operated knee, treatment effect of CS-G-M was no longer significant. Reconstruction of the CCL had no significant effect on synovial fluid epitope. CONCLUSIONS: Administration of CS-G-M was associated with altered concentrations of 3B3 and 7D4 epitope in synovial fluid, suggesting that these compounds may act to modulate articular cartilage matrix metabolism in vivo.

Gracilis or semitendinosus myopathy in 18 dogs.

The clinical findings in 18 dogs with gracilis (n = 17) or semitendinosus (n = 1) myopathy are described. Each dog had a similar hind-limb gait abnormality characterized by a shortened stride with a rapid, elastic medial rotation of the paw, internal rotation of the hock and external rotation of the calcaneus [corrected] and internal rotation of the stifle during the mid-to-late swing phase of the stride. Medical management prior to or in lieu of surgery was attempted (n = 8) with no apparent response. Fifteen dogs had one or multiple surgical procedures. Although transection, partial excision, or complete resection of the affected muscle resulted in resolution of lameness following surgery, lameness recurred six weeks to five months (mean, 2.5 months; median, two months) following surgery. Adjunctive medical treatment did not prevent recurrence. Variable replacement of the affected muscle with fibrous connective tissue (predominantly along the caudolateral border of the muscle) was evident grossly, and replacement of myofibers with fibrous connective tissue was confirmed histologically. A definitive etiology could not be established.

Holding power of threaded external skeletal fixation pins in the near and far cortices of cadaveric canine tibiae.

We compared the pin-bone interfaces at the near and far cortical penetration sites of positive-profile end-threaded external fixation pins in cadaveric canine tibiae. The holding power of the pins in each cortical surface was independently measured in 21 pin-bone sections. Scanning electron microscopy (SEM) was used to compare subjectively the microstructural appearance of the pin-bone interfaces at the near and far cortical penetration sites in eight pin-bone sections. The far cortical penetration site provided greater holding power than did the near cortical site. SEM evaluation suggested more bony microfractures and debris with less pin-bone SEM evaluation suggested more bony microfractures and debris with less pin-bone interlock in the near cortical penetration sites than in the corresponding far cortical penetration sites. This study showed that after low-speed power insertion of positive-profile end-threaded pins in canine cadaveric tibiae, the near cortical penetration site contributes approximately 25% less to the overall holding power of the pin than does the far cortical penetration site.

Intraosseous infusion using the osteoport implant in the caprine tibia.

We evaluated the in vivo animal tolerance to intraosseous infusion via the Osteoport pediatric implant (model 2005PSO, Lifequest Medical, San Antonio, TX, U.S.A.) into the proximal tibia of immature goats and investigated the osseous effects of intermittent and sustained increases in intraosseous pressure (IOP). In group 1 (n = 3) autogenous whole blood was continuously infused (CI) for 5 days at flow rates producing an IOP of 30-45 mm Hg. Group 2 animals (n = 3) underwent a 5-s high-pressure infusion (HPI) of lactated Ringer solution (LRS) producing an IOP of 90-125 mm Hg twice daily for 10 days. In group 3, the Osteoports were left in place 5 (n = 2) or 10 days (n = 2) and evaluated for patency at 72-h intervals. An IOP > 35 mm Hg produced clinical evidence of bone pain. Bone mineral density was significantly increased (p < 0.05) in all implanted tibias (mean 1.04 g/cm2; range 0.87-1.21 g/cm2) compared with controls (mean 0.67 g/cm2; range 0.65-0.71 g/cm2). A nonsignificant increase (+9% to +31%) in periosteal new bone formation occurred in all implanted tibias. In the continuously infused group, there was a significant increase (p < 0.05) in cancellous new bone formation (+483%), percentage eroded bone surface (+143%), and osteoclast covered bone surface (+255%) compared with controls. HPI of LRS did not produce significant bone changes. Seemingly, the Osteoport provided a ready means of intraosseous infusion and may be associated with less complications than current methods of continual vascular access. Bone changes correlated more with the duration than the magnitude of increased intraosseous pressures.

Distraction osteogenesis using modified external fixation devices in five dogs.

Distraction osteogenesis was used to treat five dogs with limb deformities or limb shortening. The affected bones underwent osteotomy, and modified external fixators were attached. Complications included pin loosening, implant breakage, and soft-tissue contracture. Adequate limb length was attained in all cases, but clinical results varied from poor to excellent. Two dogs were not lame after the procedure, two dogs had improved function but were still lame, and one dog had complications necessitating amputation.

Principles of bone healing and biomechanics of external skeletal fixation.

External skeletal fixation is being used to treat an increasing number of orthopedic conditions in veterinary medicine. Study of the variables affecting the biomechanics of external fixation and bone healing is vital if patient morbidity is to be minimized. These are reviewed and incorporated into strategies that can be applied to decision making using external fixation in the clinical setting.

System behavior of commonly used cranial cruciate ligament reconstruction autografts.

Biomechanical analysis was performed on the cranial cruciate ligament (CCL) and three autogenous tissues used for CCL reconstruction in the canine stifle. The autogenous tissues were patellar ligament-based autografts described for over-the-top CCL replacement and included the central one third of the patellar ligament, the medial one third of the patellar ligament, and the lateral one third of the patellar ligament with fascia lata. Tension testing produced abrupt failure of the central and medial autografts but sequential failure of the lateral autograft. Structural properties were determined for the overload condition and within the load range of normal activity for the CCL (physiologic range). None of the autograft systems approached the stiffness, maximum load, and energy absorbed to maximum load of the CCL. The central and lateral autografts were stiffer, had greater maximum loads, and absorbed more energy to maximum load than the medial autograft. The central and lateral autografts had an elastic range, as defined by proportional limit, which corresponded to the physiologic range of loading for the CCL. Loads that corresponded to physiologic displacement of the lateral and central autografts were near the maximum load of the fixation site, which underscored the need for postoperative support of the repaired stifle.

Corrective osteotomy for pes varus in the dachshund.

Five dachshunds were treated for a distal varus deformity of one tibia. Angulations of 20 degrees to 30 degrees resulted from shortening of the medial tibial length with the maximum curvature at the distal metaphysis. Comparison with the contralateral limbs was required to determine the amount of correction necessary for functional and cosmetic results. Open wedge osteotomies stabilized with a modified type II external fixator resulted in correction of the deformities, early return of limb function, and healing of the osteotomies.

Mechanical evaluation of two canine iliac fracture fixation systems.

Twenty-three canine pelves were tested bilaterally to determine the stiffness and strength of intact ilium and stabilized oblique iliac osteotomies that simulated a common clinical fracture. Fixation systems tested were three 4.0 mm cancellous screws inserted ventral to dorsal across the osteotomy site and one laterally placed five hole 3.5 mm dynamic compression plate. Specimens were mechanically tested to failure under torsional, axial, or axial plus bending loads. Lag screw fixation was stiffer and stronger than plate fixation in all testing modes. The differences were statistically significant (p less than .05) in the torsional and axial plus bending loading modes. Fatigue testing was performed on implanted specimens with low-level cyclic loading under axial plus bending loading conditions. Physiologic loading conditions failed to produce mechanical failure of either fixation system after 100,000 cycles.

A comparison of standard femoral head and neck excision and femoral head and neck excision using a biceps femoris muscle flap in the dog.

Sixteen normal 20 to 30 kg dogs had standard femoral head and neck excision (8 dogs) or femoral head and neck excision with interposition of a biceps muscle flap (8 dogs). Lameness lessened at week 6, and did not differ between groups; neither group returned to a completely normal gait. Weightbearing decreased on the operated pelvic limb compared to controls (forceplate analysis). Weightbearing force of the muscle flap dogs was significantly less at weeks 6 and 16 than that of the standard femoral head and neck excision dogs. The operated limb of both groups was shortened; shortening was significantly greater for the muscle flap group. Hip extension was limited in both groups. Both groups had decreased (more acute) hip, stifle, and hock angles measured in standing position. Thigh muscle atrophy was more pronounced in the muscle flap group at week 6. More soft tissue was interposed in the muscle flap group at necropsy compared to the group with standard femoral head and neck excision, but the difference was not statistically significant. Skeletal muscle fibers were present in the interposed fibrous connective tissue of the muscle flap group, and the healed surfaces were smoother than those of the standard femoral head and neck excision group.

Carpal hyperextension in two-month-old pups.

Abnormal carpal configuration was observed in a litter of ten 2-month-old pups raised in a research colony. Five of the pups were exercised daily, and carpal configuration returned to normal within 7 to 10 days. The other 5 pups remained confined, and their carpal configuration returned to normal after 6 weeks. It was concluded that poor muscle tone was responsible for the carpal hyperextension.

Transoral hypophysectomy with mandibular symphysiotomy in the dog.

A surgical approach that offered direct visualization and removal of the hypophysis was evaluated in 17 dogs. Ten of the dogs were euthanatized and used to identify reliable landmarks for the drill site in the basisphenoid bone to expose the hypophysis. The intersphenoidal suture was an accurate landmark in that 1 cm caudal to the intersphenoidal suture was determined to be the precise point for the center of the drill hole. The remaining 7 dogs were hypophysectomized, using this approach. The landmarks were accurate, the surgery had a high degree of safety, and all hypophyses were removed.