Histological features of metatarsophalangeal plantar plate structure
Background. Objective was to analyze the plantar plate histology results, to reveal the features of the plantar plate enthesis structure. Materials and methods. Eleven samples of metatarsophalangeal joint plantar plates were obtained for histology assessment: 6 plantar plates from fresh traumatic amputated limb, five after second toe exarticulation. Three persons were males, 4 - females, the average age of patients was 65.28 ± 10.32 years (range 45-74). Paraffin sections (5 microns) were analyzed with bright-field light microscopy (Оlympus CX41). Grades of severity of morphological signs were evaluated by the visual analogue scale from low to high grade, with 100×. Results. The characteristic histological signs were revealed in the structure of fibrocartilaginous enthesis. There was a gradual transformation of fibrous tissue into mineralized bone tissue that microscopically was characterized by the zonation of this transition. The plantar plate enthesis had four zones: zone 1 - dense connective tissue, zone 2 - non-calcified fibrous cartilage, zone 3 - calcified fibrous cartilage, zone 4 - the bone. Conclusions. The histological structure of the attachment of the plantar plate of metatarsophalangeal joint capsule to the heads of metatarsal bones corresponds to the typical structure of the fibrocartilaginous enthesis, the characteristic feature of which is the presence of fibrous cartilage, localization predominantly near epiphyses, and the limited attachment area.