Radiation synovectomy with holmium-166 ferric hydroxide macroaggregate in equine metacarpophalangeal and metatarsophalangeal joints

OBJECTIVES: To evaluate the effects of radiation synovectomy (RSYN) with holmium-166 ferric hydroxide macroaggregate (Ho-166 FHMA) on synovium and synovial fluid in normal metacarpo- and metatarsophalangeal joints of horses and to determine intraarticular distribution of radioactivity after Ho-166 FHMA treatment. STUDY DESIGN: Either Ho-166 FHMA or nonradioactive Ho-165 FHMA was injected into metacarpo- or metatarsophalangeal joints. ANIMALS: Six adult mixed-breed horses without any clinical evidence of metacarpo- or metatarsophalangeal joint disease. METHODS: Joints were injected with a single high dose of Ho-166 FHMA (mean, 1,000 MBq/joint) or a nonradioactive Ho-165 FHMA preparation (controls). Clinical examination, arthroscopy, synovial fluid analyses, and histologic studies were performed to detect effects of RSYN. Scintigraphy was used to localize intraarticular distribution of Ho-166 FHMA. RESULTS: Ho-166 FHMA treatment induced joint inflammation leading to regional edema, effusion, and scar tissue formation. Scintigraphy revealed the highest intensity of radioactivity in the proximal plantar joint pouch, at which the Ho-166 FHMA treatment caused multifocal necrosis. In the dorsal joint pouch, however, arthroscopic study and histologic analysis showed very little effect of RSYN. There was no regeneration of synovium evident within 2 months. Synovial fluid protein concentration was significantly (P <.01) elevated, and some residual radioactivity remained for 5 days after Ho-166 FHMA injection. CONCLUSIONS: Injection of a single high dose of Ho-166 FHMA caused multifocal necrosis of synovium and deep, soft-tissue injury in equine fetlock joints. CLINICAL RELEVANCE: Inflamed equine joints with synovial lining hyperplasia could benefit from Ho-166 FHMA-induced radiation synovectomy if excessive scar tissue formation can be avoided.     

MAGNETIC RESONANCE IMAGING OF CANINE DEGENERATIVE LUMBAR SPINE DISEASES

Degenerative lumbar spine diseases, i.e., sacrolumbar stenosis, intervertebral disk degeneration and protrusion and spondylosis deformans of the canine lumbar spine were studied in eleven canine patients and three healthy controls using radiography and 0.02 T and 0.04 T low field magnetic resonance imaging. The T1 and T2 weighted images were obtained in sagittal and transverse planes. The loss of hydration of nucleus pulposus, taken as a sign of degeneration in the intervertebral disks, could be evaluated in both T1 and T2 weighted images. As a noninvasive method magnetic resonance imaging gave more exact information about the condition of intervertebral disks than did radiography. Sacrolumbar stenosis and compression of the spinal cord or cauda equina and surrounding tissue could be evaluated without contrast medium.     

RADIOGRAPHIC APPEARANCE OF THE NAVICULAR BONE AND DISTAL INTERPHALANGEAL JOINT AND THEIR RELATIONSHIP WITH OSSIFICATION OF THE COLLATERAL CARTILAGES OF THE DISTAL PHALANX IN FINNHORSE CADAVER FOREFEET

Radiographic findings in the navicular bone and distal interphalangeal joint as well as the ossification status of the collateral cartilages of the distal phalanx were evaluated in 100 Finnhorse cadaver forefeet. The most common shapes of the proximal articular margin of the navicular bone were convex and straight. Remodeling of the navicular bone was common, especially on the lateral extremity. No bony fragments were identified at the distal flexor margin even though this area appeared irregular in several feet. Several large, rounded or lollipop-shaped synovial invaginations were identified in only six feet. The thickness of the flexor cortex varied considerably, and the corticomedullary junction was uni- or bilaterally indistinct in nine feet. The shape of the sagittal ridge of the flexor cortex was commonly flat but varied. It appeared locally irregular or indistinct in 17 feet, but changes elsewhere along the flexor cortex were rare. Osteophytosis on the dorsal and palmar margins of the distal interphalangeal joint and entheseophytosis on the dorsal aspect of the middle phalanx and on the extensor process of the distal phalanx were common. "Possibly significant" ossification of the collateral cartilages (high side-bones or separate centers of ossification) was present in 36 feet; all grades of ossification in the proximal/ palmaroproximal direction as well as palmar ossification were seen. A statistically significant relationship was found between entheseophytosis on the proximal flexor margin of the navicular bone and "possibly significant" ossification. Osteophytosis on the palmarodistal margin of the middle phalanx was more common in feet with a relatively long distal phalanx, suggestive of palmar ossification. Radiographic changes in the navicular bone or in the distal interphalangeal joint did not otherwise appear to be associated with ossification of the collateral cartilages of the distal phalanx in Finnhorses.     

Application of optical coherence tomography enhances reproducibility of arthroscopic evaluation of equine joints

Background

Arthroscopy is widely used in various equine joints for diagnostic and surgical purposes. However, accuracy of defining the extent of cartilage lesions and reproducibility in grading of lesions are not optimal. Therefore, there is a need for new, more quantitative arthroscopic methods. Arthroscopic optical coherence tomography (OCT) imaging is a promising tool introduced for quantitative detection of cartilage degeneration and scoring of the severity of chondral lesions. The aim of this study was to evaluate the inter-investigator agreement and inter-method agreement in grading cartilage lesions by means of conventional arthroscopy and with OCT technique. For this aim, 41 cartilage lesions based on findings in conventional and OCT arthroscopy in 14 equine joints were imaged, blind coded and independently ICRS (International Cartilage Repair Society) scored by three surgeons and one PhD-student.

Results

The intra- and inter-investigator percentages of agreement by means of OCT (68.9% and 43.9%, respectively) were higher than those based on conventional arthroscopic imaging (56.7% and 31.7%, respectively). The intra-investigator Kappa coefficients were 0.709 and 0.565 for OCT and arthroscopy, respectively. Inter-investigator Kappa coefficients were 0.538 and 0.408 for OCT and arthroscopy, respectively.

Conclusions

OCT can enhance reproducibility of arthroscopic evaluation of equine joints.     

Repair of radial fractures in toy breed dogs with self-reinforced biodegradable bone plates, metal screws, and light-weight external coaptation

OBJECTIVE: To describe a surgical technique for, and outcome after, treatment of radial fractures with biodegradable self-reinforced polylactide plates and metal screws, and external coaptation. STUDY DESIGN: Prospective clinical study. SAMPLE POPULATION: Eleven Toy breed dogs. METHODS: Radial fractures were repaired by application of a single or 2 stacked biodegradable self-reinforced polylactide plates (poly-L/D, L-lactide, stereocopolymer [LL-and DL-lactide ratio 70/30]; SR-PLA (70/30) implants) secured with metal screws, and light-weight external coaptation. Healing was evaluated clinically and by radiography at 2, 4, 6, 8, 9, 12, 24-26 weeks, and at 1 and 2 years. Owners were interviewed 3 years after surgery. RESULTS: Radial fracture lines disappeared within 4-14 weeks in 10 dogs; an implant failed in 1 dog. Ambulation was excellent for healed fractures. Excessive skin tension led to removal of implants in 1 dog and suture repair in another dog. No foreign body reaction from implant degradation was observed and the plate was usually no longer palpable at 2 years. One dog had a fracture through a screw hole at 1 year. CONCLUSION: Healing and complication rates after repair of radial fractures with SR-PLA (70/30) plates were considered similar or better than reported after repair with metallic plates or external fixation in Toy breed dogs. No radiographic signs of osteopenia were identified under the plate during follow-up. CLINICAL RELEVANCE: Biodegradable polylactide plates could be considered as an alternative to metal plates for radial fracture repair in Toy breed dogs, however available plates are likely not strong enough when used as a single plate. Implant removal is usually not needed.     

Cardiovascular effects of medetomidine-ketamine anaesthesia in sheep, with and without 100% oxygen, and its reversal with atipamezole.

The cardiovascular effects of intravenously (iv) administered medetomidine 20 μg/kg bodyweight (bwt) and ketamine (2 mg/kgbwt), with and without 100% inspired oxygen, were investigated in six domestic sheep. A second dose of medetomidine and ketamine was administered iv, at dose 10 μg/kg bwt and 1 mg/kg bwt respectively, 25 minutes after the initial injection. Heart rate, PaO₂ pH and haemoglobin saturation decreased whereas PaCO₂ and base excess increased post-injection. Transient hypertension and an increase in respiration rate were evident within the first 10 minutes of anaesthesia. Significant hypoxaemia (P<0.01) developed in sheep breathing room air. Inspired 100% oxygen improved PaO₂ (but the difference was not significant), and improved haemoglobin saturation significantly (P<0.05), however, this effect varied between individuals. One sheep breathing room air suffered a cardiac arrest immediately post-injection and had to be resuscitated. Atipamezole 125 μg/kg given intramuscularly 45 minutes after the initial injection rapidly reversed the effects of medetomidine. Recovery times did not significantly differ although time to extubation and standing tended to be longer in sheep breathing room air compared to the sheep breathing 100% oxygen. The quality of the recovery did not differ.     

MONITORING THE PROGRESSION OF TARSAL OSSIFICATION WITH ULTRASONOGRAPHY AND RADIOGRAPHY IN THREE IMMATURE FOALS

Repeated ultrasonographic and radiographic examinations of both tarsi were performed on three immature foals at individually adjusted times to monitor the progression of ossification. The first examination was performed soon after birth, and all foals were found to have incomplete ossification of the tarsal bones. Two of the foals were monitored until ossification of the small tarsal bones was complete. The rate of ossification varied, and it seemed to be affected by the general health of the foal and by its weight-bearing. In two foals the pattern of ossification was markedly irregular and several ossifying foci were often found within the bones. Ultrasonography was found to be a practical method for monitoring the changes in the outline and echogenity of the bones in the distal tarsal area. Radiography confirmed the ultrasonographic findings and was necessary for evaluating the internal structure of the bones.     

Determination of the unsaturated disaccharides of hyaluronic acid in equine synovial fluid by high-performance liquid chromatography and fluorescence detection

Background

The purpose of this study was to develop and validate an analytical method to determine the presence of hyaluronic acid derived disaccharides in equine synovial fluid.

Findings

A high-performance liquid chromatography method for the determination of hyaluronic acid derived unsaturated disaccharides in equine synovial fluid was developed and validated. The method is based on the measurement of unsaturated disaccharides released by digestion of linear hyaluronic acid molecules. The method showed linearity (r² = 0.996) over the full working concentration range 0.89-30 mg/l. Relative standard deviation of intra- and inter-day precision ranged from of 4.3-6.7% and 7.1-7.8% respectively. The detection limit was 0.3 mg/l corresponding to 20 mg/l in synovial fluid. Accuracy of the assay was 97-103%. This method was evaluated by determining the concentration of unsaturated disaccharides from hyaluronic acid in synovial fluid of horses with lameness in the metacarpo-/metatarsophalangeal joint localized with positive response to intra-articular anesthesia.

Conclusions

The described method is valid for determination of hyaluronic acid derived disaccharides in equine synovial fluid. This method was applied to a larger research project dealing with a new form of intra-articular therapy in horses with arthritic diseases.