Combined anterior cruciate ligament, posterior cruciate ligament, and posterolateral corner reconstruction with autogenous hamstring grafts in chronic instabilities.

PURPOSE: The purpose of this study was to evaluate the clinical outcome after 1-stage reconstructions of the anterior and posterior cruciate ligaments (ACL, PCL) with reconstruction of the posterolateral corner (PLC) structures using autogenous hamstring grafts in chronic knee injuries. TYPE OF STUDY: Prospective case series. METHODS: We reviewed 17 patients (13 men and 4 women) with chronic multiligamentous injuries after a minimum follow-up of 2 years (range, 24 to 66.3 months). Arthroscopically assisted combined ACL/PCL reconstructions with autogenous semitendinosus-gracilis tendon grafts were performed using the single-incision endoscopic ACL technique and the single femoral tunnel, single-bundle transtibial tunnel PCL technique. The PLC was reconstructed with a free autogenous semitendinous tendon graft. The primary outcome measures were the International Knee Documentation Committee (IKDC) score and stress radiography. As secondary outcome measure, all patients were evaluated with a subjective questionnaire, physical examination, radiologic assessment, and KT-1000 arthrometer testing. RESULTS: The mean time from injury to the reconstructive procedure was 70.2 +/- 96.7 months (range, 5.1 to 312.6 months). At final IKDC evaluation, 4 patients (29.4%) were graded level B (nearly normal), 10 patients (58.8%) level C (abnormal), and 2 patients (11.8%) level D (grossly abnormal). The mean postoperative subjective IKDC score was 71.8 +/- 19.3 points. Mean posterior tibial displacement as measured through stress radiography at 90 degrees of knee flexion was reduced from -15.06 +/- 4.68 mm preoperatively to -7.12 +/- 3.37 mm postoperatively (P < .001). Mean anterior tibial displacement was 0.94 +/- 2.75 mm preoperatively compared with -1.59 +/- 3.50 mm postoperatively (P < .01). Three patients had a fixed posterior tibial subluxation (posterior tibial displacement < or = -3 mm on anterior stress radiographs) postoperatively. Severe subjective instability was reduced significantly by the operative procedure (P < .001). The mean postoperative total anterior-posterior side-to-side difference with the KT-1000 arthrometer testing was 2.00 +/- 2.23 mm (range, -4 to 7 mm). CONCLUSIONS: Combined chronic ACL/PCL/PLC instabilities can be successfully treated with 1-stage arthroscopic cruciate ligament reconstruction combined with PLC reconstruction using autogenous hamstring grafts. Although current reconstruction techniques are not able to restore normal tibiofemoral kinematics, most patients recover a functionally stable knee and have considerably improved knee function compared with their preoperative status, based on subjective parameters and objective criteria. LEVEL OF EVIDENCE: Level IV, case series, no historical or control group.

Endostatin/collagen XVIII--an inhibitor of angiogenesis--is expressed in cartilage and fibrocartilage.

UNLABELLED: Aim of the study was to get a deeper insight in the mechanisms regulating avascularity of cartilaginious tissues. In the center of our interest was the expression of the anti-angiogenic fragment of collagen XVIII and its potency to inhibit angiogenesis. We observed a strong endostatin/collagen XVIII production in articular and fibrocartilage and an inhibitory potency concerning the VEGF-signalling pathway. INTRODUCTION: Cartilaginous tissue is mainly avascular and shows a limited intrinsic capacity for healing. Aim of this study was to investigate the expression of the antiangiogenic peptide endostatin/collagen XVIII in cartilage and fibrocartilage. RESULTS: In fetal epiphyseal cartilage of humans high endostatin/collagen XVIII levels could be detected by ELISA whereas significantly lower levels were found in articular cartilage of adults. In the fibrocartilaginous tissue of the menisci, there was no significant difference in the endostatin/collagen XVIII concentrations between samples of fetuses and adults. But in the menisci of adults, endostatin/collagen XVIII concentrations were higher in the internal avascular two thirds of the meniscus whereas in the fetal menisci higher endostatin/collagen XVIII concentrations were found in the external third. Endostatin/collagen XVIII immunostaining of rat articular cartilage shows that endostatin/collagen XVIII downregulation starts soon after birth. In fetal cartilage and fibrocartilage of rats and humans, endostatin/collagen XVIII could be immunostained in the extracellular matrix and in the pericellular matrix of endothelial cells, fibrochondrocytes and chondrocytes. In adult cells, weak endostatin/collagen XVIII immunostaining was restricted to the pericellular matrix of fibrochondrocytes and chondrocytes. The detection of endostatin/collagen XVIII could be verified by in situ hybridization. Chondrocytes in vitro released measurable amounts of endostatin/collagen XVIII into culture supernatants. Stimulation of chondrocytes with EGF, as an example of a growth factor, or dexamethasone had no influence on endostatin/collagen XVIII expression. Endostatin inhibited VEGF-induced phosphorylation of MAPK in chondrocytes. CONCLUSIONS: The spatial and temporal expression of endostatin/collagen XVIII in cartilaginous tissue and its potency regarding inactivation of VEGF signalling suggests that this antiangiogenic factor is important not only for the development but also for the maintenance of avascular zones in cartilage and fibrocartilage. EXPERIMENTAL PROCEDURES: We analyzed the spatial and temporal expression of endostatin/collagen XVIII--an endogenous angiogenesis inhibiting factor--in cartilage and fibrocartilage of humans and rats by immunohistochemical and biochemical (ELISA) methods and by in situ hybridization. To elucidate possible factors responsible for the induction or suppression of endostatin/collagen XVIII in cartilaginous tissues, chondrocytes (cell line C28/I2) were exposed to EGF and dexamethason. To study the possible interaction of endostatin/collagen XVIII with angiogenic factors, the immortalized human chondrocytes (C28/I2) have been incubated with VEGF and the phosphorylation of the MAPK Erk 1/2 (extracellular-regulated kinases), a known signal transduction pathway for VEGF has been determined under the influence of endostatin.

Production of endogenous antibiotics in articular cartilage.

OBJECTIVE: Defensins are broad-spectrum antimicrobial peptides that are components of innate immunity. To date, only epithelial surfaces and blood cells have been shown to produce these cationic peptides in bactericidal concentrations when challenged with microorganisms or inflammatory cytokines. Infections caused by gram-negative pathogens occur only infrequently in association with joint surgery. The present study was undertaken to investigate whether this may be explained by intraarticular production of gram-negative-specialized antimicrobial peptides. METHODS: Healthy articular cartilage and cultured T/C-28a2 chondrocytes were assessed, by reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry, for expression of various antimicrobial peptides. The expression of human beta-defensin 2 (HBD-2) was studied in cultured chondrocytes after exposure to bacterial supernatants and proinflammatory cytokines and was assayed by real-time RT-PCR and immunoblot analysis. A septic arthritis mouse model was used to investigate the regulation of the murine homolog of HBD-2 in articular cartilage after bacterial inoculation. RESULTS: Healthy articular cartilage and T/C-28a2 chondrocytes were able to produce different antimicrobial peptides. After exposure to gram-negative bacteria and proinflammatory cytokines, expression of cartilage-derived HBD-2 strongly increased. Immunoblot analysis revealed up-regulation of the gram-negative-specialized HBD-2 in microbicidal doses. Immunohistochemistry analysis revealed induction of the murine homolog of HBD-2 in vivo after intraarticular injection of bacteria. CONCLUSION: This study demonstrated a previously unrecognized function of human chondrocytes. In addition to its biomechanical properties, articular cartilage has the ability to produce antimicrobial substances when challenged with microorganisms. The expression of HBD-2 in microbicidal doses suggests that antimicrobial peptides may contribute to host defense mechanisms in articular joints.