Magnetic resonance imaging of an equine fracture model containing stainless steel metal implants.

REASONS FOR PERFORMING STUDY: Post operative imaging in subjects with orthopaedic implants is challenging across all modalities. Magnetic resonance imaging (MRI) is preferred to assess human post operative musculoskeletal complications, as soft tissue and bones are evaluated without using ionising radiation. However, with conventional MRI pulse sequences, metal creates susceptibility artefact that distorts anatomy. Assessment of the post operative equine patient is arguably more challenging due to the volume of metal present, and MRI is often not performed in horses with implants. Novel pulse sequences such as multiacquisition variable resonance image combination (MAVRIC) now provide improved visibility in the vicinity of surgical-grade implants and offer an option for imaging horses with metal implants. OBJECTIVES: To compare conspicuity of regional anatomy in an equine fracture-repair model using MAVRIC, narrow receiver bandwidth (NBW) fast spin echo (FSE), and wide receiver bandwidth (WBW) FSE sequences. STUDY DESIGN: Nonrandomised in vitro experiment. METHODS: MAVRIC, NBW FSE and WBW FSE were performed on 9 cadaveric distal limbs with fractures and stainless steel implants in the third metacarpal bone and proximal phalanx. Objective measures of artefact reduction were performed by calculating the total artefact area in each transverse image as a percentage of the total anatomic area. The number of transverse images in which fracture lines were visible was tabulated for each sequence. Regional soft tissue conspicuity was assessed subjectively. RESULTS: Overall anatomic delineation was improved using MAVRIC compared with NBW FSE; delineation of structures closest to the metal implants was improved using MAVRIC compared with WBW FSE and NBW FSE. Total artefact area was the highest for NBW FSE and lowest for MAVRIC; the total number of transverse slices with a visible fracture line was highest in MAVRIC and lowest in NBW FSE. CONCLUSION: MAVRIC and WBW FSE are feasible additions to minimise artefact around implants.

Treatment of subchondral cystic lesions of the medial femoral condyle of mature horses with growth factor enhanced chondrocyte grafts: a retrospective study of 49 cases.

REASONS FOR PERFORMING STUDY: To evaluate the long-term clinical outcome after allogeneic chondrocyte and insulin-like growth factor-I (IGF-I) grafting of subchondral cystic lesions (SCLs) of the femoral condyle in horses. OBJECTIVE: To test the hypothesis that chondrocyte and IGF-I grafts will improve the long-term clinical outcome in arthroscopically debrided SCLs. METHODS: Medical records of 49 horses with SCLs of the femoral condyle treated by debridement and implantation of chondrocytes and IGF-I were reviewed. Preoperative radiographs were obtained, and caudocranial radiographic projections were used to establish a ratio between cyst and femoral condyle size. Arthroscopic cyst debridement followed by filling of the bone void with autologous cancellous bone (45 horses) or tricalcium phosphate granules (4 horses) was performed. A paired syringe containing a fibrinogen and chondrocyte mixture in one syringe and calcium-activated bovine thrombin with IGF-I in the other was used to cover the surface. A successful outcome was defined as a horse that performed to its intended use without lameness. RESULTS: A successful outcome was achieved in 36 of 49 horses (74%). Preoperative radiography was performed in all horses, with 33 horses having unilateral SCLs of the medial femoral condyle, 15 horses having bilateral SCLs of the medial femoral condyle, and one horse having bilateral SCLs of the lateral femoral condyle. Median age of the horses was 3.3 years. Fifteen horses had preoperative radiographic and arthroscopic evidence of osteoarthritis (OA). A successful outcome was not influenced by age of horse, presence of pre-existing osteoarthritis or preoperative size of the subchondral cyst. Grafting resulted in success for 80% of horses >3 years old, and in 80% of horses with OA. CONCLUSIONS: Implantation of allogeneic chondrocytes supplemented with IGF-I is an effective treatment for horses with SCLs of the femoral condyle, and particularly for older horses and horses with pre-existing osteoarthritis. POTENTIAL RELEVANCE: Chondrocyte implantation may offer a greater chance of long-term success in older horses and horses with osteoarthritis than has been previously reported with cyst debridement alone.

Relationships between race earnings and horse age, sex, gait, track surface and number of race starts for Thoroughbred and Standardbred racehorses in North America.

REASONS FOR PERFORMING STUDY: There is no consensus on objective outcome measures that can be used to determine if a medical or surgical treatment affects race performance. OBJECTIVE: To determine the association between 2 commonly used outcome measures (total starts and total earnings) and age, sex, gait and race surface. METHODS: A cross-sectional study was performed using the race performance data for all Thoroughbred horses age 2, 3, 4 and 5 years racing in the United States, and Standardbred horses of the same ages racing in the United States and Canada during the year 2006. Median earnings and starts were determined for each combination of age, sex and track surface (for Thoroughbred) or gait (for Standardbred). The effect these variables had on starts on race earnings ($) was determined using linear regression. RESULTS: Race records for 68,649 Thoroughbreds and 25,830 Standardbreds were obtained. All independent variables (age, breed, sex, gait, track surface and total number of starts) had a significant impact on total earnings (P<0.0001). CONCLUSIONS: The data show considerable variation across age groups and track surfaces for Thoroughbreds and across age groups for Standardbreds. They also show that the decision to use earnings or starts as outcome measures could have a marked effect on reported success for a particular treatment. POTENTIAL RELEVANCE: Both earning and start data should be reported in studies evaluating outcome following surgery or other intervention. Considerations of age, breed, sex, track surface and gait should be included in the design of these studies.

Effects of platelet rich plasma and acellular bone marrow on gene expression patterns and DNA content of equine suspensory ligament explant cultures.

REASONS FOR PERFORMING STUDY: Suspensory ligament (SL) desmitis is a common source of lameness. The results of this study will determine if blood-derived products stimulate SL matrix synthesis and have potential as regenerative therapies for SL desmitis OBJECTIVES: To determine if various blood-based biological products including plasma, blood, PRP, platelet poor plasma (PPP) and ABM aspirate stimulates anabolic and/or catabolic pathways in suspensory ligaments (SL). METHODS: The body of the SL was harvested from 6 horses and used to establish explant cultures. Explants were cultured in plasma, blood, PRP, PPP or ABM at concentrations of 10, 50 or 100%. Anabolic responses were assessed by use of quantitative PCR for collagens type I and III, cartilage oligomeric matrix protein (COMP) and decorin. Total DNA and collagen protein content were also measured. Catabolic reactions were measured by quantitative PCR for matrix metalloproteinases 3 and 13 (MMP-3, MMP-13). RESULTS: Acellular bone marrow aspirate at 100% stimulated decorin and COMP mRNA synthesis more than all other treatments at all concentrations. No treatment at any concentration stimulated the catabolic gene MMP-13; only 50% ABM stimulated MMP-13 mRNA expression. CONCLUSIONS: Acellular bone marrow is indicated, and might be preferred to plasma, blood or PPP, as a blood-based biological source for SL tissue regenerative therapy. Long-term, placebo controlled case studies are indicated to determine if ABM aids in recovery from SL desmitis. POTENTIAL RELEVANCE: Bone marrow aspirate is an autogenous, readily available biological source for SL regenerative therapy where the aim is to stimulate matrix synthesis.

Arthroscopic reattachment of osteochondritis dissecans lesions using resorbable polydioxanone pins.

REASONS FOR PERFORMING STUDY: Debridement of osteochondritis dissecans (OCD) cartilage lesions results in fibrocartilage and imperfect hyaline repair tissue, and forms a permanent irregularity to the subchondral bone plate. OBJECTIVE: To evaluate the clinical, radiographic and outcome effects of OCD cartilage flap reattachment for select lesions as an alternative to OCD debridement. HYPOTHESIS: Separated cartilage flaps resulting from OCD lesions may be re-incorporated into the hyaline cartilage surface by reattachment rather than debridement and removal. METHODS: Resorbable polydioxanone pins were used to reattach OCD flap lesions in 16 joints of 12 horses. Criteria for attachment, rather than removal, included an unmineralised cartilage flap on preoperative radiographs and a relatively smooth surface with some residual perimeter attachment at surgery. RESULTS: There were 12 subjects, 6 males and 6 females, 7 Thoroughbred or Standardbred weanlings, 3 Warmbloods, 1 Arabian and 1 Quarter Horse, mean age at surgery 6.8 months. All horses had effusion of the affected femoropatellar joint (n = 9), tarsocrural joint (n = 1) or fetlock (n = 2). Radiographic lesions varied in length between 1.8-6.3 cm; reattachment was used in 16 of 18 affected joints and the OCD cartilage was not satisfactory for salvage in 2 stifles. Number of pins required was 2-10. One horse was subjected to euthanasia due to a tendon laceration 8 weeks after surgery; of the remaining 11 horses, mean duration of follow-up was 3.9 years (range 4 months-8 years). Nine of these were sound and had entered work, while 2 were sound but remained unbroken 4 and 6 months post operatively, respectively. Radiographic resolution of the OCD lesion occurred in 14 of 16 pinned joints in the 9 horses with long-term follow-up. The 2 remaining joints had a 3 and a 5 mm mineralised flap in the original defect sites. CONCLUSIONS: This study indicated cartilage flap reattachment was an alternative to removal in selected OCD lesions. POTENTIAL RELEVANCE: Relatively smooth OCD cartilage flaps may be salvaged by reattachment and can result in normal radiographic subchondral contour and a high likelihood of athletic performance. Further case numbers are required to determine which lesions are too irregular or contain too much mineral for effective incorporation after reattachment.

Insulin-like growth factor-I enhances cell-based repair of articular cartilage.

Composites of chondrocytes and polymerised fibrin were supplemented with insulin-like growth factor-I (IGF-I) during the arthroscopic repair of full-thickness cartilage defects in a model of extensive loss of cartilage in horses. Repairs facilitated with IGF-I and chondrocyte-fibrin composites, or control defects treated with chondrocyte-fibrin composites alone, were compared before death by the clinical appearance and repeated analysis of synovial fluid, and at termination eight months after surgery by tissue morphology, collagen typing, and biochemical assays. The structure of cartilage was evaluated histologically by Toluidine Blue reaction and collagen type-I and type-II in situ hybridisation and immunohistochemistry. Repair tissue was biochemically evaluated by DNA assay, proteoglycan quantitation and characterisation, assessment of collagen by reverse-phase high-performance liquid chromatography, and collagen typing using cyanogen bromide digestion and peptide separation by polyacrylamide gel electrophoresis. The results at eight months showed that the addition of IGF-I to chondrocyte grafts enhanced chondrogenesis in cartilage defects, including incorporation into surrounding cartilage. Gross filling of defects was improved, and the tissue contained a higher proportion of cells producing type-II collagen. Measurements of collagen type II showed improved levels in IGF-I-treated defects, supporting in situ hybridisation and immunohistochemical assessments of the defects. IGF-I improves the repair capabilities of chondrocyte-fibrin grafts in large full-thickness repair models.

Insulin-like growth factor-I gene expression patterns during spontaneous repair of acute articular cartilage injury.

This study evaluated the constitutive insulin-like growth factor-I (IGF-I) gene expression pattern in spontaneously healing cartilage defects over the course of 16 weeks, and correlated the tissue morphology and matrix gene expression with IGF-I mRNA levels. Full-thickness 15 mm cartilage defects were debrided in the femoral trochlea of both femoropatellar joints of 8 horses and the healing defects examined 2, 4, 8, or 16 weeks after surgery. Samples were harvested for histologic assessment of tissue healing using H&E staining, toluidine blue histochemical reaction for proteoglycan deposition, and in situ hybridization and immunohistochemistry procedures to demonstrate collagen type II mRNA and protein expression. Total RNA was isolated for Northern analysis to measure cartilage matrix molecule expression, and for semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) to determine IGF-I gene expression patterns in healing cartilage defects. Full-thickness cartilage defects in horses were slow to heal compared to smaller lesions in similar locations in other animals. However, a progressive decline in tissue cellularity and vascularity, and increased tissue organization were observed on H&E stained specimens over the 16-week experiment. Evidence of early chondrogenic repair was detected through collagen type II in situ hybridization and immunohistochemistry. However, levels of collagen type II and aggrecan mRNA in lesions were not abundant on Northern analysis indicating incomplete chondrogenesis. IGF-I message expression followed a cyclic pattern with low levels at 2 weeks, followed by an increase at 4 and 8 weeks, and a subsequent decline at 16 weeks. There was no direct correlation between the stage of healing and cartilage matrix message expression, and the abundance of IGF-I mRNA in the healing lesions. In conclusion, this study demonstrated that the spontaneous healing of articular defects was accompanied by a temporal fluctuation in IGF-I gene expression which was discoordinate to the steady rise in expression of cartilage matrix molecules such as procollagen type II.

Tenoscopic examination and proximal annular ligament desmotomy for treatment of equine "complex" digital sheath tenosynovitis.

OBJECTIVE: To determine the outcome of horses with "complex" digital tenosynovitis treated by tenoscopic proximal annular ligament desmotomy and resection of synovial masses or adhesions, or both, within the digital sheath. STUDY DESIGN: Retrospective evaluation. ANIMALS OR SAMPLE POPULATION: Twenty-five horses with a clinical and ultrasonographic diagnosis of palmar or plantar proximal annular ligament constriction and ultrasonographic evidence of synovial masses or adhesions within the digital tendon sheath. METHODS: Each horse had tenoscopic surgery for annular ligament desmotomy combined with adhesiolysis and/or synovial mass resection. Mean follow-up time was 3.4 years. Spearman's rank correlation was used to assess the relationship between functional outcome or cosmetic results and preoperative variables including duration of clinical signs, digital sheath synovial fluid total protein concentration and nucleated cell count, thickness of the palmar or plantar proximal annular ligament (PAL), severity of adhesions, severity of synovial masses, degree of synovial distention, or limb affected. RESULTS: A total of 18 (72%) horses returned to athletic soundness, 4 were improved but not sound, and 3 were not improved. Cosmetic outcome was normal in 10 horses, improved but not normal in 12, and not improved in 3 horses. Cosmetic and functional outcome were significantly adversely affected by the duration of clinical signs and the severity of synovial masses. CONCLUSIONS: With appropriate tenoscopic surgical attention, horses with complex tenosynovitis syndrome characterized by synovial masses, adhesions, or both adhesions and masses, and PAL constriction, have a good prognosis for return to athletic soundness. CLINICAL RELEVANCE: Horses with PAL constriction and additional digital tendon sheath pathology such as adhesions and synovial masses have a 72% chance of returning to sound athletic performance, however 60% of horses retain some degree of cosmetic blemish in the affected limb. There is an inverse relationship between the duration of clinical signs and outcome, and therefore, prompt surgical attention is advised.

Isolation and chondrocytic differentiation of equine bone marrow-derived mesenchymal stem cells.

OBJECTIVE: To isolate mesenchymal stem cells from adult horses and determine specific monolayer culture conditions required to enhance biochemically and phenotypically defined chondrocytic differentiation. ANIMALS: 2 adult horse bone marrow donors without skeletal or hematologic abnormalities. PROCEDURE: Bone marrow was aspirated from the sternebra, and mesenchymal stem cells were isolated by centrifugation and cultured in monolayers. Subcultures were established in 24-well plates on day 13. Culture medium was harvested every 2 days, and culture of 12 of the 24 wells was terminated on day 6 and of the remaining wells on day 12. Medium proteoglycan content was determined for all samples, and proteoglycan monomeric size was determined for pooled samples from days 2-6 and 8-12. Total nucleated cell numbers were determined at culture termination on days 6 and 12. Histologic, histochemical, and collagen immunohistochemical analyses of multiwell chamber slides harvested on day 6 or 12 were performed. RESULTS: Mesenchymal cells were an abundant cellular constituent of bone marrow aspirates, and separation of hematopoietic elements was achieved by centrifugation and delayed medium exchange. The remaining mesenchymal stem cells progressed from large, spindyloid, fibroblastic-appearing cells to a rounder shaped cell which formed colony plaques; isolated cells remained more spindyloid. Mesenchymal cell transformation toward a chondrocytic phenotype was verified by a shift in expression from collagen type I to type II, and an increase in quantity and molecular size of proteoglycans synthesized over time. CONCLUSIONS: Mesenchymal stem cells obtained from adult horses have the capacity to undergo chondrogenic differentiation in monolayer cultures and may provide a locally recruitable or transplantable autogenous cell source for articular cartilage repair.

Cholelithiasis and cholecystitis in a dairy cow.

A 9-year-old Holstein cow was evaluated for colic and decreased milk production of 2 days' duration. Preoperative serum biochemical results suggested hepatic damage and cholestasis. On the basis of persistent signs of abdominal pain that were nonresponsive to analgesics, exploratory laparotomy was performed. The cow was found to have choleliths. Cholecystocentesis was performed, and samples were submitted for cytologic examination and bacterial culture. Bacterial culture yielded Escherichia coli and Clostridium perfringens. Using digital pressure, choleliths were reduced until they could be passed through the bile duct into the duodenum. The cow recovered from surgery without complications, and all serum biochemical test results returned to reference ranges. Cholelithiasis is rare in cattle but can result in signs of abdominal pain.

Distributional changes in substance P nociceptive fiber patterns in naturally osteoarthritic articulations.

OBJECTIVE: Studies have proved the importance of substance P (SP) in the development and perpetuation of inflammation in joints, and describe the abundant SP neural network in the soft tissue structures of various articulations. Less information is available on the innervation of the bony structures of joints, and there is a paucity of data describing the changes associated with disease conditions. Our objectives were to evaluate changes in the distribution of sensory nerve fibers in the bony structures of naturally osteoarthritic joints. METHODS: Five osteoarthritic metacarpophalangeal (MCP) articulations were removed from 4 horses euthanized because of clinically severe and persistent lameness. The articulations were examined grossly and by high detail radiographs, and substance P containing nociceptive fibers were identified on thin sections by immunoreaction. RESULTS: Gross examination and radiographs revealed evidence of osteoarthritis (OA), including thin, eroded, and fibrillated articular cartilage and, in the most severe cases, periarticular osteophytes and palmar metacarpal flattening with cystic cavitations. Histologically, there was a generalized loss of cartilage matrix basophilia, with chondrocyte clustering or death. SP nerve fibers were evident in the articular capsule and periosteum, and their appearance and frequency were similar to nonarthritic MCP articulations. Abnormal cartilage structures such as erosion channels and osteophytes on the dorsal proximal phalangeal perimeter contained short, tortuous, immunoreactive nerve fibers. Areas of chondrocyte cloning and abnormal fibrillated or eroded articular cartilage had increased generalized SP peptide staining, but no nerve fibers were identified. Additionally, hypercellular infiltrates in cystic cavitations in the subchondral bone stained intensely for SP, but true neurofilaments were absent. CONCLUSION: Combined, the findings of SP innervation in areas of articular remodeling such as erosion channels and osteophytes suggest that SP plays a role in the signaling and maintenance of pain associated with OA.

The diagnosis and surgical correction of congenital portosystemic vascular anomalies in two calves and two foals.

Two calves and two foals presented with episodic clinical signs of diffuse central nervous system disease. Portosystemic anomalies were tentatively diagnosed based on the history, clinical signs and increased serum concentrations of blood ammonia and total serum bile acids with normal concentrations of liver derived enzymes. one calf died before intraoperative contrast portography, whereas the other calf and both foals had marked clinical improvement after intensive medical therapy. Surgical correction was attempted in these three animals and was successful in one foal. A right paracostal celiotomy was superior to a ventral median approach for exposure to the portal vascular system and shunt access.

Arthroscopic removal of axial osteochondral fragments of the plantar/palmar proximal aspect of the proximal phalanx in horses: 119 cases (1988-1992).

Medical records from 119 horses that had undergone arthroscopic surgery for removal of axial osteochondral fragments of the palmar/plantar proximal aspect of the proximal phalanx were reviewed. Standardbred racehorses represented 109 (92%) of those affected. Ninety-three (78%) of the horses were < 3 years old. Gender distribution was consistent with that of the equine hospital population. Fragments most commonly were observed in the hind limbs (155/164; 95%), specifically, on the medial aspect of the left hind limb (72/164; 44%). Bilateral fragmentation occurred in 21 of 119 (18%) horses, and 15 of 119 (13%) horses had fragments in the medial and lateral aspect within the same joint. Fifteen (13%) horses had a concurrent osteochondritis dissecans lesion on the distal intermediate ridge of the tibia, and 30 of 119 (25%) had radiographic signs of osteoarthritis involving the centrodistal (distal intertarsal) and tarsometatarsal articulations. In 55 of 87 (63%) racehorses and in 100% of the 9 nonracehorses, performance returned to preoperative levels after surgery. Fragment numbers or distribution, concurrent osteochondritis dissecans lesions of the distal intermediate ridge of the tibia, or tarsal osteoarthritis were not significantly associated with outcome. Abnormal surgical findings, consisting of articular cartilage fibrillation or synovial proliferation, were significantly (P < 0.0001) associated with adverse outcome; these findings were documented in 31% of the 32 horses without successful outcome and in only 2% of the 55 horses with successful outcomes.

Topical use of 5-fluorouracil for treatment of squamous cell carcinoma of the external genitalia of horses: 11 cases (1988-1992).

Ten horses with histologically confirmed squamous cell carcinoma (SCC) and 1 horse with presumptive SCC of the external genitalia were treated with a combination of surgical debridement and topical administration of 5-fluorouracil, or with topical treatment alone. Tumor remission was obtained in all horses except 1 in which owner compliance was deficient, and no recurrences have been reported. Topical use of 5-fluorouracil as a chemotherapeutic agent for treatment of genital lesions of SCC in horses should be considered as a viable alternative to radical surgical excision.