Prospective randomized study on the effect of concurrent bone filling of tibial peg holes in cementless total knee arthroplasty.

BACKGROUND: In total knee arthroplasty (TKA), cementless fixation is initially weaker than cement fixation. This study aimed to examine whether filling the tibial peg holes with bone improves initial fixation strength in cementless TKA. METHODS: This prospective, comparative study examined 88 joints in 66 patients randomized to the bone filling (48 joints) or conventional group (no bone filling; 40 joints). All patients underwent TKA with the NexGen® trabecular metal modular tibial component. In the bone filling group, resected cancellous bone was filled into the peg holes before insertion of the tibial component. We performed clinical and plain radiographic evaluations after the operation and measured bone mineral density (BMD) at five sites below the component at 1, 3, 6, and 12 months postoperatively. RESULTS: Operative time and clinical evaluations were not significantly different. Plain radiography showed significant longitudinal thickening of the trabecula below the peg (P<0.05) and decreased occurrence of reactive lines (P=0.07) in the bone filling group compared with the conventional group. BMD was significantly higher in the bone filling group in the medial region below the peg at 1, 3, and 6 months and in the central region at 1 and 3 months (all P<0.05). CONCLUSIONS: When using the NexGen trabecular metal modular tibial component, concurrent peg hole bone filling increases the initial component fixation strength. Possible effects on long-term stabilization warrant further study.

Which is better? Anterior or posterior referencing for femoral component position in total knee arthroplasty.

When sizing the femoral component or determining its placement in total knee arthroplasty (TKA), if the anterior-posterior diameter of the femoral condyle is between component sizes, the selected size will differ depending on whether anterior referencing (AR) or posterior referencing (PR) is used. As a result, the amount of resected bone will also vary. In the present prospective study, we compared the two referencing methods to determine which is more suitable for individual patients. We recruited 58 patients (92 joints) who received TKA using the standard technique with intermediate-size components. AR was used in 26 joints, and PR in 23 joints. Seventeen of the patients underwent same-day bilateral TKA in which components of different sizes were used for the left and right joints. AR resulted in significantly smaller anterior and posterior offsets than PR. Preoperative clinical evaluation revealed no significant differences among cases in which intermediate-size components were indicated, or those in which components of different sizes were indicated. When an intermediate-sized component was indicated using the AR method, moving the sizer forward resulted in a larger posterior gap, but this technique was nevertheless considered acceptable. AR is likely to be more suitable than PR as it achieves more physiological anterior clearance.

Efficacy and risks of fondaparinux 7.5 mg for deep vein thrombosis after total knee arthroplasty.

OBJECTIVES: High-dose fondaparinux therapy at 7.5 mg/day (FPX 7.5 mg) for deep vein thrombosis (DVT) may increase the risk of hemorrhage. We investigated the efficacy and safety of FPX 7.5 mg to treat DVT after total knee arthroplasty. METHODS: This study included 101 patients (91 with osteoarthritis, 10 with rheumatoid arthritis; mean age at total knee arthroplasty: 72.9 years) with asymptomatic postoperative DVT. Medical prophylaxis for DVT was started on postoperative day 1. Vascular ultrasound was conducted within 2 days postoperatively; patients were switched to FPX 7.5 mg after DVT diagnosis. Ultrasound was repeated to monitor DVT resolution. Adverse reactions were assessed. RESULTS: DVT resolved in 72 patients (71.3%) receiving FPX 7.5 mg. There were no significant differences between patients with versus without DVT resolution in the timing of FPX 7.5 mg therapy, treatment period, age, body mass index, or D-dimer or hemoglobin levels. There was no significant difference in DVT outcome between patients starting FPX 7.5 mg within 4 days postoperatively versus on day 5 or later, or between patients treated for ≤7 versus ≥8 days. Hemoglobin decreased to ≤7 g/dL in three patients (2.9%). CONCLUSIONS: FPX 7.5 mg can be expected to resolve DVT in 71.3% of patients; however, the risk of associated hemorrhagic complications may be higher than the risk of pulmonary embolism. To treat DVT with FPX 7.5 mg without compromising safety, patients should be selected carefully and the timing of treatment should be adjusted appropriately.

Mid-term results of total knee arthroplasty with a porous tantalum monoblock tibial component.

BACKGROUND: The objectives of the present study were to assess the mid-term results of cementless total knee arthroplasty (TKA) with the porous tantalum monoblock tibial component and to examine the time course of bone changes on plain radiographs. METHODS: The subjects were 32 patients, 29 patients were available for follow-up. We investigated the mid-term results of TKA after a mean follow-up period of 7 years and 8 months. We also examined changes of the bone over time on plain radiographs. RESULTS: The Knee Society Clinical Rating scores showed significant improvement. Bone changes around the tibial component were as follows: new bone formation and longitudinal trabecular thickening in 41.4% (Type A), only longitudinal trabecular thickening in 41.4% (Type B), and no changes in 17.2% (Type C). Type A and B changes were more frequent in patients with osteoarthritis, whereas Type C was only seen in patients with rheumatoid arthritis. Three knees had an initial gap, but this disappeared in all cases, and no new radiolucent lines were detected. Stress shielding was observed in seven knees (21.9%), but there was no implant loosening related to it. When we examined the relationship between the mechanical axis and the locations of the tips of the tibial pegs in patients with or without stress shielding, no significant differences were found. CONCLUSIONS: The results of mid-term follow-up have demonstrated favorable bone ingrowth, suggesting that porous tantalum is a promising material for cementless TKA.