Age-related morphometric changes of the tidemark in the ovine stifle.

Though the ovine stifle is commonly used to study osteoarthritis, there is limited information about the age-related morphometric changes of the tidemark. The objective of this study was to document the number of tidemarks in the stifle of research sheep without clinical signs of osteoarthritis and of various ages (n = 80). Articular cartilage of the medial and lateral tibial condyles and of the medial and lateral femoral condyles was assessed by histology: (a) to count the number of tidemark; and (b) to assess the OARSI (Osteoarthritis Research Society International) score for structural changes of cartilage. The number of tidemarks varied between anatomical regions, respectively, from 4.2 in the medial femoral condyle to 5.0 in the lateral tibial condyle. The axial part showed a significant higher number of tidemarks than the abaxial part, for all regions except the medial tibial condyle. Whilst the tidemark count strongly correlated with age (Spearman's correlation coefficient = 0.70; 95% confidence interval (95% CI): 0.67-0.73; p < 0.0001), the OARSI score was weakly correlated with age in our cohort of sheep (Spearman's correlation coefficient = 0.25; 95% CI: 0.19-0.30; p < 0.0001). Interestingly, no tidemark was seen in the three animals aged 6 months. Our data indicate that the number of tidemarks increases with age and vary with anatomical region. The regional variation also revealed a higher number of tidemarks in the tibia than in the femur. This could be attributed to the local variation in cartilage response to strain and to the difference in chondrocyte biology and density.

Communication between the distal interphalangeal joint and the navicular bursa in the horse at Computed Tomography Arthrography.

Diffusion of drugs injected into the distal interphalangeal joint or the navicular (podotrochlear) bursa can influence diagnosis and treatment of foot pain. Previous anatomical and radiographic studies of the communication between these synovial structures have produced conflicting results and did not identify the location of any communication if present. This anatomic study aimed to assess the presence and site of communication between the distal interphalangeal joint and the navicular bursa in the horse by computed tomography arthrography. Sixty-six pairs of cadaver forelimbs were injected with contrast medium into the distal interphalangeal joint and imaged by computed tomography arthrography. The presence of a communication, location of the communication and additional structural changes were assessed. Navicular bursa opacification occurred in 7 distal limbs (5.3%) following distal interphalangeal joint injection. One limb showed a communication through the T-ligament and 6 limbs showed a communication through the distal sesamoidean impar ligament. In 3 cases, the communication through the distal sesamoidean impar ligament was associated with a distal border fragment. Our study showed that communication between the distal interphalangeal joint and navicular bursa is uncommon and inconsistent. Clinically, the presence of a communication could (1) influence the interpretation of diagnostic analgesia of the distal interphalangeal joint or the navicular bursa by facilitating the diffusion of local anaesthetic between these structures; (2) allow the drug and its potential adverse effects to spread from the treated synovial cavity to the non-targeted synovial cavity; (3) be responsible for the failure of joint drainage in the case of sepsis.

A controlled study evaluating a novel surgical treatment for kissing spines in standing sedated horses.

OBJECTIVE: To compare the results of a novel minimally invasive surgical technique with intralesional corticosteroid medication, as treatment for overriding dorsal spinous processes (ORDSP) in horses. STUDY DESIGN: Retrospective controlled clinical case series. ANIMALS: Horses (n = 68) with ORDSP. METHODS: ORDSP was diagnosed based on history, clinical, and radiographic examination. All narrowed spaces were treated. Horses undergoing medical treatment had methylprednisolone acetate injected directly in the affected space under radiographic control. Surgical cases had interspinous ligament desmotomy (ISLD) using Mayo scissors; supraspinous ligaments were left intact. All horses had the same controlled exercise plan and returned to work 3-6 weeks after treatment. RESULTS: Methylprednisolone was administered in 1-7 spaces in 38 cases, compared with ISLD in 3-8 spaces in 37 cases. Thirty-four horses (89%) treated medically initially resolved signs of back compared with 35 horses (95%) treated surgically. From these, back pain recurred in 19 medical cases and in none of the surgical cases. Horses having ISLD were 24 times more likely to experience long-term resolution of signs of back pain (OR 24; 95%CI: 5-115; P = < .0001). Repeat radiographs in 19 surgical cases indicated that interspinous spaces widened significantly postoperatively (P = < .0001). CONCLUSIONS: This surgical technique allowed horses with back pain and radiographic ORDSP to return to work without further clinical signs of back pain and to show radiographic evidence of improvement.

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.

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.

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.

Teaching veterinary radiography by e-learning versus structured tutorial: a randomized, single-blinded controlled trial.

Case-based e-learning may allow effective teaching of veterinary radiology in the field of equine orthopedics. The objective of this study was to investigate the effectiveness of a new case-based e-learning tool, compared with a standard structured tutorial, in altering students' knowledge and skills about interpretation of radiographs of the digit in the horse. It was also designed to assess students' attitudes toward the two educational interventions. A randomized, single-blinded, controlled trial of 96 fourth-year undergraduate veterinary students, involving an educational intervention of either structured tutorial or case-based e-learning, was performed. A multiple-choice examination based on six learning outcomes was carried out in each group after the session, followed by an evaluation of students' attitudes toward their session on a seven-point scale. Text blanks were available to students to allow them to comment on the educational interventions and on their learning outcomes. Students also rated, on a Likert scale from 1 to 7, their performance for each specific learning outcome and their general ability to use a systematic approach in interpreting radiographs. Data were analyzed using the Mann-Whitney test, the t-test, and the equivalence test. There was no significant difference in student achievement on course tests. The results of the survey suggest positive student attitudes toward the e-learning tool and illustrate the difference between objective ratings and subjective assessments by students in testing a new educational intervention.

Endoscopic resection of dorsal spinous processes and interspinous ligament in ten horses.

OBJECTIVE: To describe endoscopic surgical subtotal resection of the dorsal spinous processes (DSP) and interspinous ligament in horses. STUDY DESIGN: Descriptive clinical study. ANIMALS: Adult horses (n=10) with back pain and impinging dorsal spinous processes METHODS: Diseased portions of DSP and interspinous ligament were resected by endoscopic surgery, using Destandau Endospine to create a surgical space and provide triangulation for the endoscope, suction cannula, and surgical instruments. Medical records of 10 horses with pain attributable to DSP pathology treated by endoscopic resection of DSP were reviewed to determine intra- and postoperative complications and outcome. RESULTS: Affected portions of DSP were successfully resected with minimal hemorrhage. Limited periosteal reaction was noticed after 3 months in 2 horses. Nine horses had no complications and returned to full work within 8 weeks; 1 developed a subcutaneous abscess, which was successfully managed, and returned to work after 3 months. Surgical resection improved presenting clinical signs and owner's complaint although 2 horses did not return to previous performance levels. CONCLUSION: Resection of DSP and interspinous ligament can be successfully performed endoscopically in horses. Hemorrhage was minimal but reduced visibility. Complications were minimal and most horses returned to work by 8 weeks. CLINICAL RELEVANCE: Endoscopic resection of DSP is a safe and reliable surgical procedure in horses.