Patients with lumbar lateral recess syndrome (LRS) can be successfully cured by removing osseous excrescences that grow on the peripheral edge of articular surface of the facet joint. They cause narrowing of the lateral recess and compress a root of the spinal nerve. Their appearance is related to the instability of respective dynamic vertebral segment. The aim of this study was to analyze the osteophytic composition morphohistochemically and elucidate cellular processes that lead to this new formation appearance. It is necessary to find a possible causative-consequential relation between the osteophyte and instability. The ideal object to explore was the osteophyte in the lateral recess because it had to be removed during operative treatment. The group of 30 patients with clinical feature of LRS was chosen. Each patient had clinically verified LRS with consequential radiculopathy. Bony outgrowths were removed surgically and analyzed by histological and immunohistochemical methods: toluidine blue, Goldner trichrome, TRAP, indirect peroxidase with antibodies against BMP 3 and BMP 7. The outgrowths that caused lateral recess stenosis were composed of fibrous and hyaline cartilage and cancellous bone. The changes in cartilage and bone, and occurrence of intramembranous bone formation in sense of enlargement of trabeculae, leads to the conclusion that marginal osteophytic formations could be an adaptation to changed conditions in the dynamic vertebral segment and an attempt to stabilize this segment by enlargement of articular surface.