Our 32 and 38 mm alumina ceramic-on-metal (COM) bearings were run in a hip simulator study for comparison with 32 mm metal-on-metal (MOM) controls. The 32 mm MOM bearings demonstrated an overall wear rate of 1.58 mm(3)/million cycles (Mc) that was comparable to previous simulator studies. The peak run-in MOM wear-rates (10, 15.7 mm(3)/Mc) were higher than in previous simulator studies. There was a noticeable graying in color of serum lubricants with MOM wear rates of 2-3 mm(3)/Mc and with wear rates of 10-15 mm(3)/Mc the serum became much darker. The COM lubricants darkened during two "break-away" wear events with wear-rates 5.8-6.7 mm(3)/Mc. The 32 and 38 mm COM bearings demonstrated overall wear-rates of 0.38 and 0.29 mm(3)/Mc, approximately four-fold reduced compared to MOM controls. The COM wear-rates were also much higher than in the one previous COM study. There may be methodological reasons that could explain this discrepancy. Our ion concentrations assessed from serum lubricants had Cobalt (Co) 68% and Chromium (Cr) 32% for average ratio of metal ion composition (i.e. averaging Co/Cr ratios: 2.26) in the parent alloy. Comparing Co ion concentrations during run-in, the COM bearings represented a 35-fold reduction compared to MOM. At 3.0 Mc, the COM represented a 33-fold reduction compared to MOM. Overall, our simulator study confirmed previously published advantages of low wear and reduced metal ions with the ceramic-metal coupling compared to standard metal-metal bearings.
We investigated the effects of varus-valgus alignment on the long-term outcomes after cementless total hip arthroplasty (THA) using a porous coated version of Bi-Metric femoral stems. The Kaplan-Meier survival analysis was performed in 71 hips. The survival rate with femoral revision for aseptic loosening as the end point was 100% at 17 years. Nevertheless, the initial stem alignment was more valgus in patients with the Engh grade III-IV stress shielding than patients with the Engh grade I-II. Our results suggest that valgus misalignment of cementless Bi-Metric stem might be a potential risk factor for the progression of stress shielding.
Purpose: The purpose of the present study was to follow up Japanese patients with deep vein thrombosis (DVT) after total knee arthroplasty (TKA) and also to examine factors associated with residual thrombus within the sixth postoperative month. Methods: DVT evaluation was performed by noninvasive venous ultrasonography. We retrospectively reviewed 88 Japanese patients (88 knees) receiving primary unilateral TKA, who had no preoperative DVT. We examined the influence of the following four factors on postoperative DVT: (1) patient factors (age, sex, body height, body weight, and body mass index), (2) surgical factors (operation time, bleeding amount, avascularization time, and anesthesia method), (3) postoperative factors (bleeding amount, period to ambulation, period of venous foot pump use, and ratio of graduated compression stocking use), and (4) DVT conditional factors (location, length, number of vein branches, and the presence of >5 mm vasodilatation). Results: The total prevalence of venous thromboembolism (VTE) was 62.5% (55 of the 88 patients). Among the 55 VTE patients, the rates of distal and proximal DVT were 96.4% and 3.6%, respectively. Bilateral DVT was found in 34.5%, while unilateral DVT on the surgical and nonsurgical sides were 52.7% and 12.7%, respectively. Asymptomatic pulmonary embolism was 1.8%. DVT was exacerbated in five patients (11.9%), of whom three showed additional thrombus formation. The remaining two patients had thrombus elongation or propagation from distal to proximal veins. In comparisons between thrombus-unresolved and -resolved groups within the sixth postoperative month, statistical significances were found in the incidence of bilateral DVT (50.0% vs. 15.4%, p ¼ 0.02) and unilateral DVT (43.8% vs. 76.9%, p ¼ 0.02). On the other hand, operation time (107.0 + 17.3 min vs. 94.5 + 11.9 min, p ¼ 0.01) and avascularization time (99.8 + 17.6 min vs. 88.0 + 11.5 min, p ¼ 0.01) in bilateral DVT patients were significantly longer than in unilateral ones. Conclusion: Our results suggest that an extended operation and avascularization time may be a risk factor for bilateral DVT and residual thrombus over 6 months.
It has been recognized that perioperative hemostasis management after joint-replacement surgery for hemophilia patients is complicated and cumbersome, due to the necessity of rigorous monitoring for clotting-factor levels throughout the infusion. Between 2005 and 2014, we examined seven patients with hemophilia A (ten joints: six hips and four knees) receiving total hip or knee arthroplasty (THA or TKA) for hemophilic arthropathy. One male patient (31 years old) showed an intra-articular hematoma formation after THA (case 1). In another male patient (46 years old) receiving TKA, the postoperative trough factor VIII level became lower significantly than reference levels (80%–100% for the 5–10 postoperative days) recommended by the guidelines from the Japanese Society on Thrombosis and Hemostasis, despite sufficient coagulant based on the guidelines being administered (case 2). In the latter patient, deep infection and hematoma formation were observed postoperatively. In this article, we provide a detailed clinical report regarding these two complication cases at the early postoperative periods, and the management of bleeding control for hemophilia patients is discussed.
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