İn îhis study, the changes on the facetjoints of 5 lamb's spine whlch İmmobilized by application of interspinous segmental İnstrumentatİon wİthout arthrodesis for detecting the preservation of longltudinai vertebral growth was investigated. Their twins were selected as a control group. İnterspinous segmental İnstrumentatİon ıvas applied for eight segments at thoracolumbar area when they were eight weeks of age. Both groups were foiiowed for seven months. Ali animals were killed at the end of this period. İn study group, intervertebraI discs were thin and atrophİc, like an other part of vertebral column and under pressure posteriorly because of the developed lordosis. Hİstologİc examİnation of the facet joint cartilage revealed thinning, fibrillation, and loss of normal cartilage cellularity. These findings were consistent wİth the hlstologic appearance of osteoarthritis.
Keywords: Facet joint, fusİon, interspinous segmental İnstrumentatİon, intervertebra! disc.