[Show abstract][Hide abstract] ABSTRACT: The purpose of this study was to create a controlled partial thickness cartilage lesion in a sheep model, and to provide a foundation to study the natural history of the progression of this lesion. Twenty-eight sheep divided into four groups (1, 12, 24, and 52 weeks, n=7/group) were used in this study. In one stifle, a mechanical tool was used to create a 200 microm partial thickness lesion (1.5x1.5 cm2) on the medial femoral condyle via arthroscopy. Joint fluid was drawn presurgery and after euthanasia for analysis of collage II 3/4 C (long) (C2C). After euthanasia, the condyle was analyzed by gross appearance, confocal laser microscopy (CLM) for cell viability, scanning electronic microscopy (SEM) for surface roughness, Artscan for cartilage stiffness, and histology for cartilage morphology. The gross appearance of the treated area appeared rough, soft, and swollen compared to untreated control over time. CLM demonstrated that the depth of cell death increased to 590 microm at 52 weeks after surgery. SEM demonstrated that the treated area became more irregular over time. Stiffness of the treated area was significantly less than control by 12 weeks after surgery. Histologic analysis demonstrated that the 12, 24, and 52 week groups had significantly poorer histologic scores than the 1 week group. Joint fluid analysis demonstrated that the treatment group at 1 week had significant higher levels of C2C than the pretreatment baseline data. The results of this study demonstrated that partial thickness injury of cartilage continued to propagate and degenerate over time in this sheep model. Options for the prevention or treatment of this lesion may be tested using this model in the future.
Full-text · Article · Oct 2006 · Journal of Orthopaedic Research
[Show abstract][Hide abstract] ABSTRACT: To determine whether bone microcracks are altered after application of focused and radial extracorporeal shock wave therapy (ESWT) to the equine distal limb.
An ex vivo experimental model.
A contralateral limb specimen was obtained from 11 Thoroughbred racehorses with a unilateral catastrophic injury. Distal limb specimens were also obtained from 5 non-racing horses.
Three separate skin-covered bone segments were obtained from the mid-diaphysis of the metacarpus (MC3) or metatarsus (MT3). Focused (9,000 shockwaves, 0.15 mJ/mm2, 4 Hz) and radial (9,000 shockwaves, 0.175 mJ/mm2, 4 Hz) ESWT treatments were randomized to the proximal and distal segments and the middle segment was used as a treatment control for pre-existing microcracks. After treatment, bone specimens were bulk-stained with basic fuchsin and microcracks were quantified in transverse calcified bone sections.
ESWT had small but significant effects on microcracks. Microcrack density (Cr.Dn) and microcrack surface density (Cr.S.Dn) were increased after focused ESWT, whereas Cr.Le was increased after radial ESWT. In racing Thoroughbreds, Cr.Le increased with increased number of races undertaken. Cr.Dn and Cr.S.Dn were not significantly influenced by the number of races undertaken.
ESWT has small but significant effects on bone microcracking ex vivo.
These preliminary data suggest that ESWT has the potential to increase bone microcracking in equine distal limb bone in vivo. Such effects may be more pronounced in Thoroughbreds that are actively being raced, because in vivo microcracking increases with increased number of races undertaken.
No preview · Article · Jan 2004 · Veterinary Surgery