The Effects of a Crosslinked, Modified Hyaluronic Acid (xCMHA-S) Gel on Equine Tendon Healing.

OBJECTIVE: To assess the effects of a crosslinked, modified hyaluronic acid (xCMHA-S) gel on equine tendon healing using an in vivo surgical model. STUDY DESIGN: In vivo experimental study. ANIMALS: Adult horses (n = 5). METHODS: Full thickness bilateral forelimb window tenectomies were surgically created in both forelimb superficial digital flexor tendons and xCMHA-S gel was implanted intraoperatively into the right forelimb lesion of each horse whereas the left forelimb served as the untreated control. Healing was monitored by serial ultrasound examinations every 14 days over the course of the 84 day study. In addition, gross pathology, scanning electron microscopy for fiber diameter, and histological scoring were completed on tendon samples harvested after euthanasia at 84 days. RESULTS: Ultrasound assessment demonstrated a significant decrease in mean lesion size of treated (0%) compared to control (30%) tendons at 84 days. Mean (±SD) cumulative histologic tendon scores for control tendons (17.7 ± 2.7) were significantly higher than treated tendons (13.6 ± 1.9), indicating less advanced healing in the control group. Tendon cell density was increased and neovascularization, intensity of inflammation, and uniformity of fiber diameter were increased in control compared to treated tendons. There were no differences in fibroblast shape, levels of intralesional hemorrhage, linearity of collagen fibers, or collagen fiber diameter or distribution between treated and control tendons. CONCLUSION: Tendons treated with xCMHA-S gel at the time of model induction had superior histologic healing scores and sonographically smaller lesions compared to controls, suggesting that xCMHA-S gel may aid the natural healing process.

Mechanical characterization of matrix-induced autologous chondrocyte implantation (MACI®) grafts in an equine model at 53 weeks.

There has been much interest in using autologous chondrocytes in combination with scaffold materials to aid in cartilage repair. In the present study, a total of 27 animals were used to compare the performance of matrix-assisted chondrocyte implantation (MACI®) using a collagen sponge as a chondrocyte delivery vehicle, the sponge membrane alone, and empty controls. A total of three distinct types of mechanical analyses were performed on repaired cartilage harvested from horses after 53 weeks of implantation: (1) compressive behavior of samples to measure aggregate modulus (HA) and hydraulic permeability (k) in confined compression; (2) local and global shear modulus using confocal strain mapping; and (3) boundary friction coefficient using a custom-built tribometer. Cartilage defects receiving MACI® implants had equilibrium modulus values that were 70% of normal cartilage, and were not statistically different than normal tissue. Defects filled with Maix™ membrane alone or left empty were only 46% and 51-63% of control, respectively. The shear modulus of tissue from all groups of cartilage defects were between 4 and 10 times lower than control tissue, and range from 0.2 to 0.4 MPa. The average values of boundary mode friction coefficients of control tissue from all groups ranged from 0.42 to 0.52. This study represents an extensive characterization of the mechanical performance of the MACI® grafts implant in a large animal model at 53 weeks. Collectively, these data demonstrate a range of implant performance, revealing similar compressive and frictional properties to native tissue, with inferior shear properties.

Spiral colon impaction in juvenile alpacas: 12 cases (2006-2010).

OBJECTIVE: To describe clinical signs and treatment outcomes for juvenile alpacas with spiral colon impaction (SCI). DESIGN: Retrospective case series. Animals-12 juvenile (< 6 months old) camelids with SCI. PROCEDURES: Crias with SCI were identified by searching the medical records database of the Cornell University Equine and Farm Animal Hospital. A keyword-based search method was used. Inclusion required confirmation of SCI on the basis of surgical or necropsy findings. History, signalment, examination findings, diagnostic test results, medical treatments, and surgical reports as well as short- and long-term outcomes were reviewed. Peritoneal fluid parameters were compared with those of age-matched comparison crias in which SCI was suspected but ruled out at necropsy or exploratory celiotomy. RESULTS: 12 crias with confirmed SCI were identified. Common clinical signs included lethargy and diarrhea. Abdominal distention was observed in 9 crias. In 3 crias, a mass in the region of the spiral colon was palpated. Seven crias underwent peritoneal fluid analysis; compared with age-matched comparison crias, SCI-affected crias had higher peritoneal fluid nucleated cell counts and nucleated cell count-to-total protein concentration ratios. A ventral midline celiotomy was performed in 9 crias; 7 underwent an enterotomy, and 2 underwent transmural infusion of saline (0.9% NaCl) solution with manual breakdown of ingesta; 3 of these crias survived for at least 6 months. CONCLUSIONS AND CLINICAL RELEVANCE: Crias with SCI that were not resolved by medical management had a poor prognosis. During celiotomy, transmural infusion of saline solution with manual breakdown of ingesta provided a less invasive alternative to enterotomy.

Partial carpal arthrodesis in a 2-year-old alpaca.

A 2-year-old alpaca was presented for acute onset right forelimb lameness. Clinical findings included bilateral carpal valgus (more severe in the affected forelimb) and medial instability of the right radio-carpal joint. Surgical treatment consisted of radio-carpal joint arthrodesis, which is presented as a therapeutic option for severe carpal instability secondary to injury to the supporting ligamentous structures of the carpus.