Correlation of Ulnar Length and Apoptotic Cell Death in Degenerative Lesions of the Triangular Fibrocartilage

Purpose: The purpose of this study was to investigate apoptosis in degenerative disc lesions (Palmer type IIC) and differentiate between patients with ulna-plus and ulna-neutral variance. Methods: Seventeen patients with degenerative tears (Palmer type IIC) in the articular disc of the triangular fibrocartilage were included in this study. The triangular fibrocartilage was debrided arthroscopically with a punch and the histologic sections were used to analyze necrosis and apoptosis. Apoptosis and necrosis was quantified by terminal deoxyribonucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) assay. Apoptotic cells were visualized by poly(ADP-ribose) polymerase (PARP) p85 immunohistochemistry. The number of apoptotic and necrotic cells was then correlated with ulnar length. Results: PARP- and TUNEL-positive cells were found in each patient. In addition, patients with an ulna plus variance showed a significantly increased number of apoptotic cells in comparison to patients with an ulna neutral variance. The distribution of the apoptosis-positive cells did not show any accumulation in the inner part of the specimen, but were evenly distributed. Conclusions: This study showed that patients with ulna plus present with significantly higher numbers of apoptotic cells in degenerative lesions in comparison to patients with ulna neutral. The apoptotic cells were evenly distributed throughout the entire specimen. Clinical Relevance The results of this study revealed that increased length of the ulna is related to increased cell death. Therefore, techniques that decrease the ulna variance would appear to be appropriate and would improve the clinical situation by preventing further cell death.