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Key Points• Patients undergoing total knee arthroplasty can develop anti-PF4/heparin antibodies without heparin exposure.• Dynamic mechanical prophylaxis is a heparinindependent risk factor for anti-PF4/heparin antibody formation in this patient population.Platelet-activating antibodies, which recognize platelet factor 4 (PF4)/heparin complexes, induce spontaneous heparin-induced thrombocytopenia (HIT) syndrome or fondaparinuxassociated HIT without exposure to unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH). This condition mostly occurs after major orthopedic surgery, implying that surgery itself could trigger this immune response, although the mechanism is unclear. To investigate how surgery may do so, we performed a multicenter, prospective study of 2069 patients who underwent total knee arthroplasty (TKA) or hip arthroplasty. Approximately half of the patients received postoperative thromboprophylaxis with UFH, LMWH, or fondaparinux. The other half received only mechanical thromboprophylaxis, including dynamic (intermittent plantar or pneumatic compression device), static (graduated compression stockings [GCSs]), or both. We measured anti-PF4/heparin immunoglobulins G, A, and M before and 10 days after surgery using an immunoassay. Multivariate analysis revealed that dynamic mechanical thromboprophylaxis (DMT) was an independent risk factor for seroconversion (odds ratio [OR], 2.01; 95% confidence interval [CI], 1.34-3.02; P 5 .001), which was confirmed with propensity-score matching (OR, 1.99; 95% CI, 1.17-3.37; P 5 .018). For TKA, the seroconversion rates in patients treated with DMT but no anticoagulation and in patients treated with UFH or LMWH without DMT were similar, but significantly higher than in patients treated with only GCSs. The proportion of patients with ‡1.4 optical density units appeared to be higher among those treated with any anticoagulant plus DMT than among those not treated with DMT. Our study suggests that DMT increases risk of an anti-PF4/heparin immune response, even without heparin exposure. This trial was registered to

Performing THA after failed treatment of trochanteric fractures requires consideration of complication risk and incorrect femoral neck anteversion.

BackgroundPostoperative pain relief can be achieved with various modalities. However, there are only few reports that have analyzed postoperative analgesic techniques in total hip arthroplasty patients. The aim of this retrospective study was to compare the postoperative outcomes of three different analgesic techniques after total hip arthroplasty.MethodsWe retrospectively reviewed the influence of three analgesic techniques on postoperative rehabilitation after total hip arthroplasty in 90 patients divided into three groups (n = 30 patients per group). Postoperative analgesia consisted of continuous epidural analgesia (Epi group), patient-controlled analgesia with morphine (PCA group), or a continuous femoral nerve block (CFNB group). We measured the following parameters relating to postoperative outcome: visual analog scale scores, the use of supplemental analgesia, side effects, length of the hospital stay, plasma D-dimer levels, and the Harris hip score.ResultsEach group had low pain scores with no significant differences between the groups. The PCA group had a lower frequency of supplemental analgesia use compared to the Epi and CFNB groups. Side effects (nausea/vomiting, inappetence) and day 7 D-dimer levels were significantly lower in the CFNB group (p < 0.05). There were no significant differences between the groups in terms of the length of the hospital stay or the Harris hip score.ConclusionsAlthough there were no clinically significant differences in outcomes between the three groups, the CFNB provided good pain relief which was equal to that of the other analgesics with fewer side effects and lower D-dimer levels in hospitalized patients following total hip arthroplasty.

BackgroundWe investigated whether the calcar femorale, a cortical septum in the region of the lesser trochanter of the femur, correlates with results of femoral stem implantation in patients with osteoarthritis of the hip secondary to developmental dysplasia using computed tomography.MethodsThis retrospective study included 277 hips (41 males and 236 females; age, 37 to 92 years) of patients who had presented to Okayama Medical Center with hip pain. Of these, a total of 219 hips (31 males and 188 females) had previously undergone total hip arthroplasty. According to the Crowe classification, 147 hips were classified as Crowe grade I, 72 hips as Crowe grade II–IV, and 58 hips as normal.ResultsThe calcar femorale was identified in 267 hips (96.4%). The calcar femorale was significantly shorter and more anteverted in Crowe grade II–IV hips than in Crowe grade I or normal hips. Significant differences in the shape of the calcar femorale were found according to the severity of hip deformity. Three stem designs were analyzed: single-wedge (59 hips), double-wedge metaphyseal filling (147 hips), and modular (13 hips). Single-wedge stems were inserted more parallel to the calcar femorale rather than femoral neck anteversion, while other types of stems scraped the calcar femorale.ConclusionsThe angle of the calcar femorale differs according to the severity of hip deformity, and the calcar femorale might thus serve as a more useful reference for stem insertion than femoral neck anteversion in total hip arthroplasty using a single-wedge stem.