Expression of TRAIL and death receptor DR4 in Palmer type 2 TFCC lesions.

INTRODUCTION: Degenerative articular disc perforations of the triangular fibrocartilage (TFC) of the wrist are characterized by fibrocartilage cell loss and are often associated with ulna-plus situations. Apoptosis has been found to play a crucial role in fibrocartilage cell loss, however, the molecular mechanism and mediators are still poorly understood. AIM: The purpose of this study was to identify receptors to apoptosis in degenerative disc lesions. PATIENTS: Included in the study were 17 patients with degenerative articular disc tears of the TFC (Palmer type 2C). Following arthroscopic debridement of the TFC, histological sections were examined to assess the presence of apoptosis. Apoptosis was determined using TRAIL and death receptor DR4 agonists for immunohistochemical analyses. The number of cells positive for apoptosis was then correlated with ulna length. RESULTS: Cells positive for TRAIL and DR4 were found in all specimens. The number of cells positive for TRAIL was significantly increased in specimens of patients with an ulna positive variance (P = 0.040). However, DR4 was not significantly increased in ulna plus (P > 0.05). Both, TRAIL and DR4 positive cells were found to be evenly distributed throughout each specimen. There was no accumulation of any type of cells in any particular zone of the biopsies. CONCLUSION: This is the first study that shows that TFCC cells express TRAIL and DR4, which suggests that apoptosis, as well as, mechanical trauma are involved in the development of disc perforation. The TRAIL/DR4 receptor system is a molecular mediator of apoptosis induction in TFC cells and therefore plays a role in cell loss in degenerative disc lesions.

Cartilage cell proliferation in degenerative TFCC wrist lesions.

INTRODUCTION: The central zone of the triangular fibrocartilage complex (TFCC) of the wrist is thought to be avascular and is generally considered to lack any healing potential. AIM: The purpose of this study was to investigate, if cartilage cells of degenerative disc lesions possess any healing or proliferation potential and whether ulna length plays a significant role in the proliferation process. RESULTS: Cells positive for proliferating cell nuclear antigen (PCNA) were found in all specimens. Specimens of patients with ulna positive variance showed a decreased number of PCNA positive cells than specimens of patients with either negative or neutral ulna variance. CONCLUSION: We found that cartilage cells of Palmer type 2C lesions undergo mitotic cell division, thus exhibiting proliferation capability. It could not be shown that ulnar length is significantly correlated with the number of PCNA positive cells.

Apoptotic pathways in degenerative disk lesions in the wrist.

PURPOSE: Degenerative articular disk perforations of the triangular fibrocartilage (TFC) of the wrist could result from chronic loading of the ulnocarpal joint. Apoptosis played a crucial role in fibrocartilage cell loss, and the purpose of this study was to clarify which apoptotic pathway was involved in the development of degenerative disk lesions. We also investigated whether ulna length played an etiologic role in the occurrence of fibrocartilage cell loss. METHODS: Included in the study were 17 patients with degenerative articular disk tears of the TFC (Palmer type 2C). After arthroscopic debridement of the TFC, histologic sections were examined to assess the presence of apoptosis. Apoptosis was determined by use of caspase 3, caspase 8, and caspase 9 immunohistochemistry. Furthermore, Fas ligand and BID (BH3 interacting domain death) agonist were applied for immunohistochemical analysis. RESULTS: Cells positive for caspase 3, caspase 8, caspase 9, Fas ligand, and BID were found in all specimens. The number of cells positive for caspase 3 and BID was significantly increased in specimens from patients with an ulna-positive variance. In contrast, for cells positive for caspase 8, caspase 9, and Fas ligand, no significant difference was found between specimens from patients with an ulna-positive variance and those from patients with an ulna-neutral/ulna-negative variance. CONCLUSIONS: The extrinsic and intrinsic apoptotic pathways are involved in the development of degenerative disk lesions. Fibrocartilage cell loss occurs mainly through the intrinsic apoptotic pathway. The accumulation of apoptotic cells is not significantly different between the 3 zones of the TFC. It could be verified that ulna length is correlated with fibrocartilage cell loss. CLINICAL RELEVANCE: Ulnar shortening is a valuable treatment option for degenerative TFC lesions. Knowledge of the specific apoptotic pathway that is causing degenerative disk lesions is critical in selecting the appropriate and most beneficial therapeutic treatment to halt further cell loss and the degeneration of the TFC.

High-resolution MRI of the triangular fibrocartilage complex (TFCC) at 3T: comparison of surface coil and volume coil.

PURPOSE: To evaluate high-resolution MRI of the triangular fibrocartilage complex (TFCC) at 3T using a surface coil (SC) or volume coil (VC). MATERIALS AND METHODS: MRI was obtained from nine volunteers in the supine position with a 3-inch SC and in prone position with a transmit-receiver wrist VC at 3 T. Coronal two-dimensional-gradient echo (2D-GRE) images (TR/TE/FA = 500 msec/15 msec/40 degrees , 1 mm slice-thickness, 60 mm field of view [FOV], 192 x 256 matrix) and coronal 3D-GRE images (TR/TE/FA = 33 msec/15 msec/10 degrees , 0.8 mm slice-thickness, 80 mm FOV, 256 x 256 matrix) were used. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the TFCC and surrounding structures were measured. For qualitative measurement, visualization of TFCC and intercarpal ligaments was graded. RESULTS: SNR of TFCC, cartilage, and bone marrow on 2D-GRE with SC/VC was as follows: 5.3/5.3 (TFCC), 16.5/14.4 (cartilage), and 3.61/3.96 (bone marrow). 3D-GRE showed similar SNR. Cartilage-TFCC/cartilage-bone marrow CNR were 11.1/12.8 (SC-2D-GRE), 8.8/10.5 (VC-2D-GRE), 14.1/15.5 (SC-3D-GRE), and 11.9/15.0 (VC-3D-GRE). Quantitative values were not significantly different between SC and VC. Visualization of TFCC and intercarpal ligament with SC was superior to that with VC. All structures show higher scores with 3D-GRE imaging compared to 2D-GRE imaging. CONCLUSION: SC may provide superior qualitative and quantitative results and can be an alternative in case of difficulty in prone position at 3T.