Francis Desbrosse

A technique for computed tomography (CT) of the foot in the standing horse

Summary Computed tomography (CT) in equine orthopaedics is currently limited because of the price, availability, impossibility to transport the scanner into surgical theatre, and the contraindications of general anaesthesia in some patients. A pQCT (peripheral quantitative computerised tomography) scanner was designed by the authors to image the limbs of the horse, both in standing or recumbent position. Standing computed tomography of the foot with a pQCT scanner is feasible and well tolerated by the horse. It enables good visualisation of bony structures but is not suitable to evaluate soft tissues. The technique can also assist surgery by assessing the 3D configuration of bone lesions.

Use of computed tomography to diagnose new bone formation associated with desmitis of the proximal aspect of the suspensory ligament in third metacarpal or third metatarsal bones of three horses.

CASE DESCRIPTION 3 horses with lameness localized to the proximal aspect of the metacarpus or metatarsus. CLINICAL FINDINGS All horses had evidence of problems that originated from the proximal aspect of the suspensory ligament (PASL), including signs of pain on palpation, positive results of diagnostic nerve blocks, ultrasonographic detection of enlargement and diffuse areas of reduced echogenicity in the proximal region of insertion of the ligament, and radiographic detection of increased mineral opacity in the proximal aspect of the metacarpus or metatarsus. Desmitis of the PASL was diagnosed in each horse; however, conservative treatment failed to improve the lameness. The horses were taken to surgery for splitting of the PASL and osteostixis of the proximal aspect of the third metacarpal or metatarsal bone. At that time, the proximal aspect of the metacarpus or metatarsus was evaluated via computed tomography (CT), which identified new bone formation at the proximal aspect of the third metacarpal or metatarsal bone that had not already been identified. TREATMENT AND OUTCOME In all horses, the newly formed bone was removed surgically under radiographic and CT guidance, and the splitting and osteostixis that had been planned were performed. After rehabilitation, all horses returned to full training at 6 months after surgery. All horses responded well to the surgical treatment and were sound 8 months afterward. CLINICAL RELEVANCE Use of CT imaging should be considered in lame horses with pain associated with the proximal aspect of the third metacarpal or metatarsal bones that does not improve with conservative treatment.

Use of Computed Tomography in Standing Position to Identify Guidelines for Screw Insertion in the Distal Phalanx of Horses: An Ex Vivo Study

OBJECTIVES To compare the precision of radiography and computed tomography (CT) preoperatively in the standing position for identification of guidelines for screw insertion in the distal phalanx, and to identify whether standing CT might improve operative time compared with preoperative radiographic planning. STUDY DESIGN Experimental ex vivo study. ANIMALS Cadaveric equine thoracic limb pairs (n=10). METHODS Insertion of a 4.5 mm cortex screw in lag fashion into an intact distal phalanx was evaluated in 2 groups (n=10) of cadaveric equine thoracic limbs. In 1 group, the site, direction, and length of the implant were determined by radiography, and in the other group, by CT. Accuracy of screw placement was verified by specimen dissection. Outcomes were (1) absence of penetration of the articular surface, the solar surface, or the semilunar canal (2) appropriate length and direction of the screw. Surgical time was also measured. RESULTS No screw penetrated the articular surface, the solar surface, or the semilunar canal in either group. CT was more accurate to identify guidelines for screw insertion (U=23.50, P=.049). With CT, surgical time (mean, 7.7 minutes) was significantly shorter (U=0.000, P=.000) than with radiography (mean, 12.7 minutes). CONCLUSION Standing CT can be used to accurately determine anatomic landmarks for screw insertion in lag fashion in sagittal fractures of the distal phalanx. CLINICAL RELEVANCE This study has a clear clinical relevance for improved internal fixation of sagittal fractures of the distal phalanx.

Innervation and nerve injections of the lumbar spine of the horse: a cadaveric study.

REASONS FOR PERFORMING STUDY The distal limb innervation of the horse has been studied extensively to allow use of local anaesthetic techniques to detect the origin of pain in lameness. However, the innervation of the lumbar spine has so far been poorly described and a more precise description may assist clinicians to localise back pain in the horse. OBJECTIVES To gain better knowledge of the innervation of the lumbar spine and identify salient anatomical features that might be used for diagnostic and therapeutic ultrasound guided injections. METHODS The spines of 8 mature horses were dissected. Branches of the dorsal rami were followed and their anatomical relationship, with articular facets, interspinous structures and muscles, noted. The spines of 3 other horses were sectioned transversely and dissected to identify ultrasonographic landmarks of the nerves. Six other spines were used to assess the accuracy of ultrasound guided injections of the nerves with blue dye. RESULTS Gross dissections confirmed the dual segmental innervation of the articular facets. Each lumbar articular facet of 2 lumbar vertebrae was innervated by the medial branch of the dorsal ramus exiting from the intervertebral foramen between those vertebrae, but also by the branch originating of the dorsal ramus cranial to it. The medial branch divided into 2 nerves before exiting the intertransverse space and has salient anatomical landmarks which could be identified ultrasonographically. The ultrasound guided injection technique appeared to be of an accuracy that would be clinically useful. CONCLUSION The results identified that the salient anatomical features of the medial branch of the dorsal ramus, as described in the present study, can be used as landmarks for reliable ultrasound-guided injection. POTENTIAL RELEVANCE This study has a clear clinical relevance for development of diagnostic and therapeutic injection techniques of the lumbar spine in the horse.

Competency Frameworks: Which Format for Which Target?

In veterinary medical education, it is now necessary to design competency frameworks (CFs) that list expected competencies at graduation. Three different CFs with different formats and contents have been published in Europe, such as the Day One Skills (DOS), the recommendations of the World Organization for Animal Health(OIE), and the Veterinary Professional (VetPro). In the current study, on the basis of a survey among Belgian veterinarians, a fourth document was designed that lists the necessary knowledge, skills, and attitudes grouped into families according to professional situations. The objectives of this study were to assess the perception of CFs by various categories of stakeholders, identify the possible uses of CFs, and determine whether one format should be preferred to another. We used a qualitative approach based on semi-structured face-to-face interviews with different stakeholders after they had reviewed the four different documents (CFs). This study showed that an obligation to design CFs was clearly perceived by academic and professional authorities. Teachers and veterinarians may be either enthusiastic or apprehensive about CFs, while students perceive the usefulness of the documents to plan and assess their learning objectives. Three main roles of CFs were identified: they can be used as communication tools, regulatory tools, or educational tools. However, not one of the documents used in this study was perceived to fulfill all roles. It is therefore likely that no one ideal document yet exists and a combination of formats is necessary.

LE TRAITEMENT CHIRURGICAL DES FRACTURES DU DOIGT CHEZ LE CHEVAL, ASSISTÉ PAR LE SCANNER

In sport horses, fractures of the digit are common, especially in the distal and proximal phalanxes. They can be simple or comminuted, and they are frequently intra-articular. Accurate reconstruction and strong stabilisation are compulsory to limit the development of osteoarthritis. CT-assisted surgery relies on the acquisition of images before or during the surgical procedure, to visualize the fracture in two or three dimensions, and assist the surgeon in his decision and surgical procedure. We use computed tomography pre- or preoperatively, as when preparing surgery on a foot with the horse standing. The objective of this article is to present both techniques and describe three clinical cases: a fracture of the distal phalanx and two different types of fractures of the proximal one.

Computed tomography to identify preoperative guidelines for internal fixation of the distal sesamoid bone in horses: an in vitro study.

OBJECTIVE To assess the reliability of computed tomography (CT) to identify the direction of implant insertion for cortical screws along the longitudinal axis of intact (nonfractured) distal sesamoid bones. STUDY DESIGN In vitro study. SAMPLE POPULATION Cadaveric paired equine forelimbs (n=16). METHODS Insertion of a cortical screw in lag fashion along the longitudinal axis of intact (nonfractured) distal sesamoid bones was evaluated in 2 groups (3.5 and 4.5 mm) of 8 paired limbs. In each group, the direction of the distal sesamoid bone was determined by CT (Equine XTC 3000 pQCT scanner). Screw placement was verified by specimen dissection. Implant direction was considered satisfactory if the entire screw length was within the distal sesamoid bone and not damaging the articular or flexural surfaces. RESULTS In our sample and according to our criteria, the proportion of satisfactory direction of screws was 0.63 (5/8) for 4.5 mm implants, and 0.87 (7/8) for 3.5 mm implants. CONCLUSIONS CT is a useful imaging modality to identify anatomic landmarks for insertion of a 3.5 mm cortical screw in the distal sesamoid bone.

Evaluation of a vessel sealing device to assist eye enucleation and exenteration in the horse.

Summary This study describes and evaluates the LigaSure for eye enucleation or exenteration in horses. According to the medical records of the Clinique Desbrosse, 17 horses underwent eye removal using the LigaSure between April 2005 and March 2009. It was applied at 7 different steps of the procedure and accounted for the different possible sources of bleeding. The Ligasure was also used to transect the optic pedicle in the 5 most recent cases. Very few complications were encountered with the technique described. Reliable vessel sealing and haemostasis was achieved in all horses.

ACTUALITÉS EN RADIOPROTECTION: RADIOBIOLOGIE, RÉGLEMENTATION INTERNATIONALE ET NATIONALE, PRATIQUES VÉTÉRINAIRES

Radiation protection is “the set of rules, procedures and means designed to monitor and prevent or reduce the harmful effects of ionizing radiation on humans and the environment”. It is subject to international scientific monitoring, and national regulations are constantly being updated to comply with international recommendations and European directives. The veterinary profession must deal with radiation protection, as not only it uses fixed or mobile xray generators for radiodiagnostics, but it is also increasingly turning to new and more complex imaging techniques and sealed sources for cancer treatments or unsealed sources with radioactive tracers for diagnostic purposes. Dosimetry studies have been conducted or are underway to improve our understanding of the risks inherent in these different sources and thus define a code of practice. Although it ignored such regulations for many years, the veterinary profession is now taking a responsible view, as evidenced by the availability of professional statistics, dosimetric monitoring or inspection reports. In less than ten years, the number of holders of passive dosimeters and of authorizations for the detention and use of ionizing radiation has increased and radiation protection is now part of the veterinary training.