Contrast-enhanced Computed Tomography Screening Is Effective for Detecting Venous Thromboembolism not Prevented by Prophylaxis after Total Knee Arthroplasty.

Venous thromboembolism (VTE) is a potential complication occurring after total knee arthroplasty (TKA). We investigated the incidence of VTE after TKA using contrast-enhanced computed tomography (CT), and assessed the efficacy of VTE prophylaxis (fondaparinux and enoxaparin). At our hospital, 189 patients (225 knees) underwent TKA between April 2007 and October 2011. The 225 knees were divided into a control group with no VTE prophylaxis (31 cases), a fondaparinux group (107 cases), and an enoxaparin group (87 cases). Contrast-enhanced CT screening for VTE was performed in all cases on day 5 or 6 after TKA. D-dimer levels were measured on day 5 after TKA, and were significantly lower in the fondaparinux (9.8 ± 3.8) and enoxaparin groups (9.4 ± 4.9) than in the control group (15.6 ± 9.8) (p ＜ 0.001). However, no statistically significant difference in the incidence of VTE was observed among the groups (control, 61.3%;fondaparinux, 49.5%;enoxaparin, 50.6%). Prophylaxis was not effective for the prevention of VTE as detected by contrast-enhanced CT after TKA. CT should be performed after TKA, even when VTE prophylaxis is used.

Modification of the cell adhesion and hydrophilic characteristics of poly(ether-ether-ketone) by 172-nm xenon excimer radiation.

BACKGROUND: Poly-ether-ether-ketone (PEEK) has biomechanical and chemical properties that are excellent for biomedical applications; however, PEEK adhesion to bone or chondral tissue proceeds slowly due to poor hydrophilicity and other surface characteristics. OBJECTIVE: We investigated the structural change, hydrophilicity, and cytocompatibility of a PEEK surface after 172-nm xenon excimer UV-irradiation. METHODS: The surface characteristics before and after irradiation were evaluated by contact angle and ATR-FTIR measurements. Mouse osteoblast-like cells (MC3T3-E1) were cultured on PEEK plates and collected after 6, 12 and 24 h for cell adhesion analysis by crystal violet staining (CVS) and scanning electron microscopy (SEM). RESULTS: UV-irradiation improved PEEK surface hydrophilicity, as indicated by a significant drop in water contact angle (p<0.05). Irradiated PEEK showed additional peaks around 3370 cm-1 and 1720 cm-1, highlighting the generation of hydroxyl and carbonyl groups. CVS and SEM revealed improved adhesion to the PEEK surface after UV-irradiation. CONCLUSION: Our results suggest that 172-nm UV-irradiated PEEK may be used in biomedical applications that require good cell adhesion.

Intercondylar notch size influences cyclops formation after anterior cruciate ligament reconstruction.

PURPOSE: The purpose of this study was to investigate the incidence of cyclops lesions and its relationship with the cross-sectional area of the intercondylar notch. METHODS: For this study, 55 patients (24 male and 31 female) underwent follow-up arthroscopy after bi-socket anterior cruciate ligament reconstruction with hamstring tendon grafts were included. All patients underwent magnetic resonance imaging measurements of intercondylar notch dimensions. We compared the femoral intercondylar notch sizes and bone tunnel sizes between knees with cyclops lesions (cyclops group) and those without cyclops lesions (no-cyclops group). The mean percentage of the tunnel size to the cross-sectional area of the femoral intercondylar notch was also compared between the groups. The median follow-up duration was 3.8 years. RESULTS: Cyclops lesions were found in 15 of the 55 knees (27.3 %) on second-look arthroscopy (cyclops group). Only 6 of the 55 knees (10.9 %) had extension loss (cyclops syndrome). The cyclops group included 3 men and 12 women. The two groups showed a statistical difference in sex variation (P = 0.04). No significant differences were found in the femoral and tibial tunnel sizes between the two groups. The cross-sectional area of the femoral intercondylar notch was significantly smaller in the cyclops group (251.7 ± 63.2 mm(2)) than in the no-cyclops group (335.6 ± 77.6 mm(2)) (P < 0.001). The percentage of the total femoral tunnel size to the cross-sectional area of the femoral intercondylar notch was significantly higher in the cyclops group (18.6 ± 5.3 %) than in the no-cyclops group (13.2 ± 3.6 %) (P = 0.02). CONCLUSIONS: A smaller intercondylar notch size may be a potential risk factor for cyclops lesion formation. LEVEL OF EVIDENCE: Case-control study, Level IV.

Postoperative change in medial meniscal length in concurrent all-inside meniscus repair with anterior cruciate ligament reconstruction.

PURPOSE: Meniscus repair can restore meniscal function that transfers the axial compressive force to circumferential tensile strain. However, few reports have investigated the relationship between concurrent meniscus repair with acute anterior cruciate ligament (ACL) reconstruction and postoperative meniscal position. This study aimed to evaluate medial meniscal size and clinical results in patients who underwent ACL reconstruction and concomitant all-inside medial meniscus repair. METHODS: Twenty patients underwent ACL reconstruction and concurrent medial meniscus repair of a peripheral longitudinal tear using the FasT-Fix meniscal repair device. Medial tibial plateau length (MTPL) and width (MTPW) were determined by radiographic images. We evaluated the Lysholm score, anteroposterior instability, meniscal healing and magnetic resonance imaging (MRI)-based medial meniscal length (MML) and width (MMW). Correlations between MRI-based meniscal size, radiographic measurement and height were investigated. RESULTS: All patients showed complete healing of the repaired meniscus in arthroscopic evaluation. However, one patient needed a subsequent meniscus repair during the follow-up period. Lysholm score and anteroposterior instability improved significantly. A better correlation was observed between MMW and MTPW than between MML and MTPL. Concurrent all-inside medial meniscus repair with ACL reconstruction significantly increased MML percentage (%MML) (100 MML/MTPL) but did not affect MMW percentage (%MMW) (100 MMW/MTPW). CONCLUSIONS: Concurrent all-inside medial meniscus repair with ACL reconstruction had satisfactory clinical results. %MML was increased by concurrent medial meniscus repair without affecting %MMW. Our results suggest that medial meniscus repair associated with ACL reconstruction may restore meniscal function by adjusting the anteroposterior length of the torn medial meniscus.

Comparison between normal and loose fragment chondrocytes in proliferation and redifferentiation potential.

PURPOSE: Loose fragments in osteochondritis dissecans (OCD) of the knee require internal fixation. On the other hand, loose fragments derived from spontaneous osteonecrosis of the knee (SONK) are usually removed. However, the difference in healing potential between OCD- and SONK-related loose fragments has not been elucidated. In this study, we investigated proliferative activity and redifferentiation potential of normal cartilage-derived and loose fragment-derived chondrocytes. METHODS: Cells were prepared from normal articular cartilages and loose fragment cartilages derived from knee OCD and SONK. Cellular proliferation was compared. Redifferentiation ability of pellet-cultured chondrocytes was assessed by real-time PCR analyses. Mesenchymal differentiation potential was investigated by histological analyses. Positive ratio of a stem cell marker CD166 was evaluated in each cartilaginous tissue. RESULTS: Normal and OCD chondrocytes showed a higher proliferative activity than SONK chondrocytes. Chondrogenic pellets derived from normal and OCD chondrocytes produced a larger amount of safranin O-stained proteoglycans compared with SONK-derived pellets. Expression of chondrogenic marker genes was inferior in SONK pellets. The CD166-positive ratio was higher in normal cartilages and OCD loose fragments than in SONK loose fragments. CONCLUSIONS: The OCD chondrocytes maintained higher proliferative activity and redifferentiation potential compared with SONK chondrocytes. Our results suggest that chondrogenic properties of loose fragment-derived cells and the amount of CD166-positive cells may affect the repair process of osteochondral defects.