Osteochondral allograft transplantation for treating medial femoral condyle subchondral bone cyst in a 14-year-old standardbred horse: a case report.

Allograft arthroplasty is a promising cartilage-resurfacing technique. A 14-year-old horse was diagnosed with a medial femoral condyle subchondral bone cyst. Allografts were harvested from a young donor animal and implanted to fill the cyst cavity. A visual assessment of the surgical site was possible during follow-up arthroscopy. In addition to a desirable gliding surface and a good adaptation of the grafts, fibrillation of the cranial ligament of the medial meniscus was noted and debrided. The recipient horse became sound four months after follow-up surgery with a high level of owner satisfaction. In conclusion allograft transplantation is a promising technique for treating subchondral bone cysts.

Experimental evaluation of cortical screw placement in lag fashion into the distal phalanx in standing horses.

The objectives of this in vivo experimental study were to evaluate the feasibility of cortical screw insertion into the intact distal phalanx in standing sedated horses and to document potential postoperative complications. One cortical screw was randomly inserted in lag fashion into each distal phalanx in 9 horses. The second surgery on the contralateral limbs was performed 2-3 weeks after the first operation, when a 4.5-mm cortical screw was inserted in lag fashion into the distal phalanx of sedated horses following perineural analgesia. Following surgery, the drill hole was filled with an antibiotic-soaked swab, which was changed every 48 h. The horses were euthanised 8 weeks after the second surgery. The hooves were disarticulated and evaluated macroscopically and by computed tomography. The surgery time was 13.9 ± 4.8 min (mean ± SD). Pain scores and lameness gradually decreased after 7 days. Solar canal penetration (SCP) was detected in 10 out of the 18 distal phalanges (55.5%). In 7 out of the 10 penetrations intraoperative bleeding was obvious. No postoperative infection was observed. Screw insertion into the distal phalanx was easily and quickly accomplished in standing horses, but its advantages in horses with sagittal fractures should be investigated further. SCP had no impact on postoperative lameness.

Quantitative sensory testing of the equine face.

BACKGROUND: Quantitative sensory testing methods are now standard in the evaluation of sensory function in man, while few normal equine values have been reported. OBJECTIVES: The aim of this experimental study was (a) to define the tactile sensory, mechanical nociceptive and thermal nociceptive thresholds of the equine face; (b) to assess the effect of age, sex, stimulation site and shaving; (c) to evaluate the reliability of the methods and (d) to provide reference facial quantitative sensory testing values. STUDY DESIGN: Method description. METHODS: Thirty-four healthy Warmblood horses were used in the study. Six (tactile sensory threshold) and five (mechanical nociceptive and thermal nociceptive thresholds) areas of the left side of the face with clear anatomical landmarks were evaluated. Ten horses had two (mechanical nociceptive threshold) or three (tactile sensory and thermal nociceptive thresholds) of these areas shaved for another study. A linear Mixed model was used for data analysis. RESULTS: All thresholds increased with age (tactile sensory threshold: by 0.90 g/y (CI = [0.12 g; 0.36 g]) P = .001; mechanical nociceptive threshold: by 0.25 N/y (CI = [0.13-0.36 N]) P = .000; thermal nociceptive threshold: by 0.2°C/y (CI = [0.055-0.361]) P = .008). Sex had no effect on thresholds (tactile sensory threshold: P = .1; mechanical nociceptive threshold: P = .09; thermal nociceptive threshold: P = .2). Stimulation site affected tactile sensory and mechanical nociceptive thresholds (P = .001 and P = .008), but not thermal nociceptive threshold (P = .9). Shaving had no significant effect on any of the thresholds (tactile sensory threshold: P = .06; mechanical nociceptive threshold: P = .08; thermal nociceptive threshold: P = .09). MAIN LIMITATIONS: Only the left side was investigated and measurements were obtained on a single occasion. CONCLUSIONS: Handheld quantitative sensory testing does not require shaving or clipping to provide reliable measurements. Stimulation over the nostril (tactile sensory threshold), temporomandibular joint (mechanical nociceptive threshold) and supraorbital foramen (thermal nociceptive threshold) resulted in the most consistent thresholds.

Ex vivo study of vagal branches at risk for iatrogenic injury during laryngoplasty in horses.

OBJECTIVE: To localize vagal branches within the surgical field of laryngoplasty and identify potentially hazardous surgical steps. STUDY DESIGN: Observational cadaveric study. SAMPLE POPULATION: Five equine head-neck specimens and four entire equine cadavers. METHODS: Dissection of the pharyngeal region from a surgical perspective. Neuronal structures were considered at risk if touched or if the distance to instruments was less than 5 mm. RESULTS: The branches of the pharyngeal plexus (PP) supplying the cricopharyngeal muscle (PPcr), the thyropharyngeal muscle (PPth), and the esophagus (PPes) were identified in the surgical field in nine of nine, five of nine, and one of nine specimens, respectively. The internal branch of the cranial laryngeal nerve (ibCLN) was identified within the carotid sheath in six of nine specimens. The external branch of the cranial laryngeal nerve (ebCLN) was identified close to the septum of the caudal constrictors in nine of nine specimens. The blade of the tissue retractor compressed the ibCLN in six of six, the ebCLN in four of six, the PPcr in six of six, the PPth in two of three, and the PPes in two of two specimens in which the respective nerves were identified after further dissection. Surgical exploration of the dorsolateral aspect of the pharynx and the incision of the septum of the caudal constrictors harmed the ebCLN in nine of nine, PPcr in seven of nine, and PPth in four of eight specimens. CONCLUSION: Several vagal branches were located in the surgical field and must be considered at risk because of their location. CLINICAL SIGNIFICANCE: Use of the tissue retractor, dissection over the pharynx, and dissection of the septum of the caudal constrictors involve a risk to damage vagal branches.

Outbreaks of a Methicillin-Resistant Staphylococcus aureus Clone ST398-t011 in a Hungarian Equine Clinic: Emergence of Rifampicin and Chloramphenicol Resistance After Treatment with These Antibiotics.

Between July 2011 and May 2016, a total of 40 Staphylococcus aureus strains originating from 36 horses were confirmed as methicillin resistant (methicillin-resistant Staphylococcus aureus [MRSA]) in a university equine clinic. An additional 10 MRSA strains from 36 samples of clinic workers were obtained in October 2017. The first equine isolate represented the sequence type ST398, spa-type t011, and SCCmec IV. This isolate was resistant to a wide spectrum of antimicrobial agents. MRSA strains with the same genotype and with very similar resistance profiles were isolated on 21 more occasions from September 2013 to September 2014. A second outbreak occurred from May 2015 until May 2016. The first isolate in this second outbreak shared the same genotype, but was additionally resistant to chloramphenicol. The second isolate from August 2015 also showed resistance to rifampicin. The clone was isolated 18 times. Most of the human isolates shared the same genotype as the isolates from horses and their resistance patterns showed only slight differences. We can conclude that the MRSA-related cases at the Department and Clinic of Equine Medicine were all nosocomial infections caused by the same clonal lineage belonging to the clonal complex 398. The clonal complex 398 of equine origin is reported for the first time in Hungary. In addition, our observation of the emergence of new resistance to antimicrobial agents within the clonal lineage after treatment with antibiotics is of concern. Strict hygiene regulations have been introduced to lower the incidence of MRSA isolation and the related clinical disease.

Evaluation of biomarkers following autologous osteochondral transplantation in the equine stifle joint - An experimental study.

The purpose of this study was to evaluate changes in biomarker and synovial parameters following autologous osteochondral transplantation (AOT) in the equine stifle joint, to test the hypothesis whether synovial parameters would show significant differences at selected time points following the surgery (at days 3, 14, 60 and 180) compared to baseline level (at day 0). Surgical intervention was performed in both stifles of nine horses (n = 18). The joints were randomly assigned to operated and sham-operated groups. Grafts 8.5 mm in diameter were harvested from the femoropatellar (FP) joint under arthroscopic control and the medial femorotibial (MFT) joints had AOT using mosaicplasty (MP) instrumentation, while the sham FP and sham MFT joints underwent arthroscopy and miniarthrotomy without transplantation, respectively. Synovial fluid (SF) parameters were evaluated at days 4, 14, 60 and 180. Data were analysed by two-way repeated- measures analysis of variance (ANOVA), and P < 0.05 was considered significant. During the first 10-14 days after surgery, lameness of degree 2-3/5 [American Association of Equine Practitioners (AAEP) scores] was present, which disappeared after 60 days. Joints with transplantation showed significant increases in synovial white blood cell count (WBC), total protein (TP), substance P, C1,2C and CS846 epitope concentration at day 3 compared to baseline and shamoperated joints (P < 0.05). These parameters returned to the baseline values by two months after surgery and remained within normal levels at 6 months postoperatively.

Diagnostic endoscopy of the navicular bursa using a needle endoscope by direct or transthecal approach: A comparative cadaver study.

OBJECTIVES: To compare the practicability, visualization of structures, and iatrogenic damage of direct and transthecal approaches to the navicular bursa for diagnostic needle endoscopy. STUDY DESIGN: Descriptive study. SAMPLE POPULATION: Equine cadaver forelimbs (n = 30). METHODS: Direct and transthecal approaches for insertion of a needle endoscope into the navicular bursa were performed. Video recordings of endoscopic procedures were assessed to determine all structures visualized within the navicular bursa. Number of attempts to gain access to the navicular bursa and total time for insertion and examination were recorded. Distribution and severity of iatrogenic lesions were assessed and scored after dissection. RESULTS: There were no statistical differences for number of attempts or time needed for insertion and examination between direct and transthecal approaches. The direct approach offered significantly increased visibility of the ipsilateral abaxial and proximal margins of the navicular bone, and ipsilateral collateral sesamoidean ligament. Iatrogenic lesions were superficial and focal, regardless of approach taken, or whether a blunt or sharp trocar tip was used. CONCLUSIONS: The direct approach provided significantly better visualization of the ipsilateral structures within the navicular bursa compared to the transthecal approach. Needle endoscopy offers a reliable technique to evaluate the navicular bursa and may complement or replace other diagnostic modalities in horses with lameness localized to the navicular region.

Evaluation of a Novel Screw Position in a Type III Distal Phalanx Fracture Model: An Ex Vivo Study.

OBJECTIVE: Mechanical evaluation of a novel screw position used for repair in a type III distal phalanx fracture model and assessment of solar canal penetration (SCP). STUDY DESIGN: Experimental study. SAMPLE POPULATION: Disarticulated equine hooves (n = 24) and 24 isolated distal phalanges. METHODS: Hooves/distal phalanges cut in a sagittal plane were repaired with 1 of 2 different cortical screw placements in lag fashion. In group 1 (conventional screw placement), the screw was inserted halfway between the proximal border of the solar canal (SC) and the subchondral bone surface on a line parallel to the dorsal cortex, whereas in group 2, the screw was inserted more palmar/plantar, where a perpendicular line drawn from the group 1 position reached the palmar/plantar cortex. Construct strength was evaluated by 3-point bending to failure. SCP was assessed by CT imaging and macroscopically. RESULTS: Screws were significantly longer in group 2 and in forelimbs. Group 2 isolated distal phalanges had a significantly more rigid fixation compared with the conventional screw position (maximum point at failure 31%, bending stiffness 41% higher). Lumen reduction of the SC was observed in 13/52 specimens (all from group 2), of which 9 were forelimbs. CONCLUSIONS: More distal screw positioning compared with the conventionally recommended screw position for internal fixation of type III distal phalangeal fractures allows placement of a longer screw and renders a more rigid fracture fixation. The novel screw position, however, carries a higher risk of SCP.

Bacterial meningitis after sinus surgery in five adult horses.

OBJECTIVE: To report meningoencephalitis as a complication after paranasal sinus surgery in 5 horses. STUDY DESIGN: Case series. ANIMALS: Adult horses (n = 5). METHODS: Medical records (2005-2010) of 5 horses that developed neurologic signs after sinus surgery were reviewed to identify potential risk factors, cause(s), or common pathways for infection. RESULTS: Underlying diseases were primary (n = 1) and secondary sinusitis (4) because of apical dental infection (1), sinus cyst (2), or masses in the ethmoturbinate region (2). Horses were treated by conventional surgical approaches and aftercare including repeated sinus lavage. Four horses had undulating pyrexia postoperatively despite antimicrobial therapy. All horses developed neurologic signs, eventually unresponsive to treatment. Suppurative meningoencephalitis was diagnosed macro- and/or microscopically on necropsy in all horses. CONCLUSION: Meningitis is a rare but fatal complication after sinus surgery in horses.

Mosaic arthroplasty of the medial femoral condyle in horses - An experimental study.

One Arabian and 5 Hungarian half-bred horses were used to study the macroscopic and microscopic survival of autologous osteochondral grafts in the weight-bearing surface of the medial femoral condyle (MFC). Grafts were harvested from the cranial surface of the medial femoral trochlea (MFT) under arthroscopic control. Three of them were transplanted into the weight-bearing surface of the contralateral MFC using an arthrotomy approach. Three months later this transplantation procedure was repeated on the opposite stifle joints in the same animals, but at that time transplantation was performed arthroscopically. Follow-up arthroscopy was carried out 12 months after the first operations, and biopsies were taken from both the recipient and the donor sites for histological examination. During follow-up arthroscopy, the transplanted areas looked congruent and smooth. Microscopically, the characteristics of hyaline cartilage were present in 5 out of the 10 biopsies examined; however, in the other half of biopsies glycosaminoglycan (GAG) loss and change in the architecture of the transplanted cartilage was observed. In a 16-year-old horse, all grafts broke during harvesting, and thus transplantation was not performed. No radiological signs of osteoarthritic changes were detected 9 to 12 months after the operations in the donor and recipient joints. Clinically, no lameness or effusion was present three months after the transplantations.

Penetrating keratoplasty and graft rejection in eight horses.

The aim of this study was to describe long-term follow-up and difference in immune reactions in the tear film following penetrating keratoplasty (PK) in horses when differently preserved corneas were utilised. This report describes for the first time the use of corneal grafts preserved in tissue culture media in equine PK. Eight experimental horses with normal eyes were included and freshly harvested, frozen or preserved corneal grafts were used for the PK. The graft-taking technique and storage, PK surgery, postoperative treatments and complications are described. The mean postoperative follow-up time was 286 days. Tear film samples taken before and periodically after surgery were measured for IgM, IgG and IgA contents by direct ELISA. All grafts were incorporated into the donor horse but were rejected to some degree. The differently harvested corneal grafts healed in the same manner and looked similar. Preoperatively, the clear corneas meant low risk for graft failure, and the fresh or stored tissues provided intact endothelium, although there were no clear graft sites postoperatively. The presence of IgA, IgG and IgM was demonstrated in the tear film from the early postoperative period. IgG levels were lower than IgA or IgM and had a constant baseline in every case, as IgA and IgM had great variability with time and an individual pattern in each eye.

A computer-assisted microscopic analysis of bone tissue developed inside a polyactive polymer implanted into an equine articular surface.

One of the most promising applications for the restoration of small or moderately sized focal articular lesions is mosaicplasty (MP). Although recurrent hemarthrosis is a rare complication after MP, recently, various strategies have been designed to find an effective filling material to prevent postoperative bleeding from the donor site. The porous biodegradable polymer Polyactive (PA; a polyethylene glycol terephthalate - polybutylene terephthalate copolymer) represents a promising solution in this respect. A histological evaluation of the longterm PA-filled donor sites obtained from 10 experimental horses was performed. In this study, attention was primarily focused on the bone tissue developed in the plug. A computer-assisted image analysis and quantitative polarized light microscopic measurements of decalcified, longitudinally sectioned, dimethylmethylene blue (DMMB)- and picrosirius red (PS) stained sections revealed that the coverage area of the bone trabecules in the PA-filled donor tunnels was substantially (25%) enlarged compared to the neighboring cancellous bone. For this quantification, identical ROIs (regions of interest) were used and compared. The birefringence retardation values were also measured with a polarized light microscope using monochromatic light. Identical retardation values could be recorded from the bone trabeculae developed in the PA and in the neighboring bone, which indicates that the collagen orientation pattern does not differ significantly among these bone trabecules. Based on our new data, we speculate that PA promotes bone formation, and some of the currently identified degradation products of PA may enhance osteo-conduction and osteoinduction inside the donor canal.

Laparoscopic cryptorchidectomy and ovariectomy in standing horses using the EnSeal® tissue-sealing device.

In the present series of cases, 8 laparoscopic cryptorchidectomies and 4 laparoscopic ovariectomies were carried out in sedated standing horses. Sedation involved a lesser anaesthesiological risk than does general anaesthesia. As compared to laparotomic exposure, the minimally invasive laparoscopic intervention provided better visualisation, shorter operative time and faster recovery. The blood vessels supplying the testes and ovaries and the suspensory ligaments of the organs were sealed and cut with EnSeal®, an adaptive bipolar electrosurgical blood vessel- and tissue-sealing device. The clinical use of the blood vessel- and tissue-sealing device proved to be successful in all cases. Gradual separation of the intact tissue from the treated, compacted, dehydrated and homogenised tissue areas and occlusion of the lumen of blood vessels treated with the device could be observed in all histological sections. To the best of our knowledge, this is the first report on the use of EnSeal® for laparoscopic cryptorchidectomy and ovariectomy in horses.

Assessment of the mineral density and mineral content of the equine third metacarpal and first phalanx bone by dual energy x-ray absorptiometry.

In the first part of this methodological study eleven metacarpi of 9 skeletally normal horses were examined from 4 directions by dual energy x-ray absorptiometry (DXA). The differences between the dorsopalmar-palmarodorsal and lateromedial-mediolateral (opposite sites) bone mineral density (BMD) values were found to be nonsignificant. In the second part of the study the precision of the Norland XR-26 densitometer was tested by measuring 34 metacarpal bones and 34 proximal phalanges, each of them three times, from a single direction. The difference between the individual measurements of the first phalanges and of the metacarpal bones originating from the right or the left side of the same horse were not significant, nor did the age or breed have a significant effect on BMD or bone mineral content (BMC). However, both BMD and BMC are greater in the metacarpal bones than in the proximal phalanges and are higher in geldings than in mares or to stallions, while the BMD or BMC values of mares and stallions did not differ from each other significantly. These data point to the necessity of further BMD studies in a higher number of patients.

Autologous osteochondral grafting--technique and long-term results.

BACKGROUND: Efficacious treatment of chondral and osteochondral defects of weightbearing articular surfaces is a daily challenge in musculoskeletal care. Autogenous osteochondral transplantation represents a possible solution for creating hyaline or hyaline-like repair in the affected area that has a noninflammatory pathoorigin. This paper discusses the experimental background and over 15 years of clinical experience with autologous osteochondral mosaicplasty. METHODS: Several series of animal studies and subsequent clinical practice of over 1,000 mosaicplasty patients were assessed to confirm the survival of transplanted hyaline cartilage and fibrocartilage filling of donor sites located on relatively less weightbearing surfaces, as well as donor-site disturbances and morbidity. Histological evaluations of dog and horse implantations as well as several series of clinical evaluations in the human material are summarized in this paper. Clinical scores, different types of imaging techniques, second-look arthroscopies, histological examination of biopsy samples, and cartilage stiffness measurements were used to evaluate the clinical outcomes and quality of the transplanted cartilage. RESULTS: Analysis of clinical scores has shown good to excellent results in 92% of patients with femoral condylar implantations, 87% of tibial resurfacements, 74% of patellar and/or trochlear mosaicplasties and 93% of talar procedures. Longterm donor-site complaints measured by the Bandi score were minor and present only in 3% of patients. 81 out of the 98 control arthroscopies represented congruent and good gliding surfaces and histologically proven survival of the transplanted hyaline cartilage as well as fibrocartilage covering of the donor sites. Complications in the entire patient group were four deep infections and four deep venous thromboses. In nearly 8% of the cases excessive intraarticular bleeding was observed in the early postoperative period, as a minor complication of the procedure. Multicentric, comparative, prospective evaluation of 413 arthroscopic resurfacing procedures (mosaicplasty, Pridie drilling, abrasion arthroplasty and microfracture cases in homogenised subgroups) demonstrated that mosaicplasty resulted in favourable clinical outcome in the long-term follow-up compared to other three techniques. Durability of the early results was confirmed in long-term evaluations both of the femoral condylar implantations and talar mosaicplasties. CONCLUSIONS: According to our encouraging results in this increasingly large series, supported by similar findings from other centres, it seems that autologous osteochondral mosaicplasty may be an alternative for small and medium-sized focal chondral and osteochondral defects of weightbearing surfaces of the knee and other weightbearing synovial joints.

Autologous osteochondral grafting (mosaic arthroplasty) for treatment of subchondral cystic lesions in the equine stifle and fetlock joints.

OBJECTIVE: To describe treatment of equine subchondral bone cysts (SBCs) by reconstruction of the articular surface with osteochondral grafts. STUDY DESIGN: Case series of horses with SBCs unresponsive to conservative therapy. ANIMALS: Eleven horses (1-12 years). METHODS: SBCs were identified in 4 locations: medial femoral condyle (5 horses), lateral femoral condyle (1), distal epiphysis of the metacarpus (4), or metatarsus (1). Osteochondral autograft transplantation (mosaic arthroplasty) was performed, taking grafts from the abaxial border of the medial femoral trochlea of the unaffected limb. Graft implantation was achieved through a small arthrotomy or by arthroscopy depending on SBC location. RESULTS: All horses improved postoperatively; 10 horses had successful outcomes with radiographic evidence of successful graft incorporation and 7 returned to a previous or higher activity level. On follow-up arthroscopy (5 horses) there was successful reconstitution of a functional gliding surface. One horse had delayed incorporation of a graft because of a technical error but became sound. One horse had recurrence after 4 years of work and soundness. One stallion was used for breeding and light riding because of medial meniscal injuries on the same limb. CONCLUSIONS: Implantation of osteochondral grafts should be considered for SBC when conservative management has not improved lameness and there is a risk of further joint injury and degeneration. CLINICAL RELEVANCE: Mosaic arthroplasty should be considered for treatment of subchondral bone cysts of the femoral condyle and distal articular surface of the metacarpus/tarsus in horses that are refractory to non-surgical management.

Experimental results of donor site filling for autologous osteochondral mosaicplasty.

PURPOSE: Autologous osteochondral mosaicplasty has become a treatment option for focal chondral and osteochondral defects in recent years. Excessive postoperative bleeding from the donor site was reported as a possible complication of the procedure. The purpose of this study was to investigate different biodegradable materials for donor site filling, which could prevent excessive postoperative bleeding from these sites but would allow reasonable blood clot formation on the articular surfaces of donor tunnels. TYPE OF STUDY: Basic science evaluation. METHODS: In an experimental model, "donor site plugs" made from hydroxylapatite, carbon fiber, polyglyconate-B, compressed collagen, and 2 versions of polycaprolactones were used to fill the bony tunnels created by harvesting. These materials were tested in 100 knees of 50 German Shepherd dogs to determine the quality of the repair tissue formation on the surfaces of the harvesting holes filled by these materials. Arthroscopies of the dogs were performed at several intervals, from 4 weeks to 26 weeks, and macroscopic studies were performed on euthanized animals between 8 weeks and 30 weeks to evaluate donor site filling and coverage. Empty donor tunnels served as controls for the evaluation of the different filling materials. RESULTS: All tested materials effectively decreased postoperative bleeding. Hydroxylapatite, carbon rods, polyglyconate-B, and melted polycaprolactone materials showed a good integration to the surrounding cancellous bone, but these fillings showed only a limited repair tissue formation, even at 30 weeks postoperatively. Second-look arthroscopy and histologic evaluation of necropsies showed the best fibrocartilage coverage after filling by compressed collagen. Technical details of the filling also had certain importance in the quality of the repair tissue formation. CONCLUSIONS: According to histologic results, compressed collagen appears to be a good material to fill donor tunnels of osteochondral graft harvest. This material is substituted gradually by bone formation and its articular surface can serve as an appropriate scaffold for fibrocartilage coverage created by the natural intrinsic repair process.