BackgroundPrevious studies regarding modular head-neck taper corrosion were largely based on cobalt chrome (CoCr) alloy femoral heads. Less is known about head-neck taper corrosion with ceramic femoral heads.Questions/purposesWe asked (1) whether ceramic heads resulted in less taper corrosion than CoCr heads; (2) what device and patient factors influence taper fretting corrosion; and (3) whether the mechanism of taper fretting corrosion in ceramic heads differs from that in CoCr heads.MethodsOne hundred femoral head-stem pairs were analyzed for evidence of fretting and corrosion using a visual scoring technique based on the severity and extent of fretting and corrosion damage observed at the taper. A matched cohort design was used in which 50 ceramic head-stem pairs were matched with 50 CoCr head-stem pairs based on implantation time, lateral offset, stem design, and flexural rigidity.ResultsFretting and corrosion scores were lower for the stems in the ceramic head cohort (p = 0.03). Stem alloy (p = 0.004) and lower stem flexural rigidity (Spearman’s rho = −0.32, p = 0.02) predicted stem fretting and corrosion damage in the ceramic head cohort but not in the metal head cohort. The mechanism of mechanically assisted crevice corrosion was similar in both cohorts although in the case of ceramic femoral heads, only one of the two surfaces (the male metal taper) engaged in the oxide abrasion and repassivation process.ConclusionsThe results suggest that by using a ceramic femoral head, CoCr fretting and corrosion from the modular head-neck taper may be mitigated but not eliminated.Clinical RelevanceThe findings of this study support further study of the role of ceramic heads in potentially reducing femoral taper corrosion.

This retrieval study documents taper damage at modular interfaces in retrieved MOM THA systems and investigates if increased modularity is associated with increased fretting and corrosion. One hundred thirty-four (134) heads and 60 stems (41 modular necks) of 8 different bearing designs (5 manufacturers) were analyzed. Damage at the shell–liner interface of 18 modular CoCr acetabular liners and the corresponding 11 acetabular shells was also evaluated. The results of this study support the hypothesis that fretting and corrosion damage occurs at a variety of modular component interfaces in contemporary MOM THAs. We also found that modularity of the femoral stem was associated with increased damage at the head. An analysis of component and patient variables revealed that dissimilar alloy pairing, larger head sizes, increased medio-lateral offsets and longer neck moment arms were all associated with increased taper damage at the modular interfaces.

While first generation porous coatings have had clinical success, aseptic loosening remains a leading cause of revision. The purpose of this study was to investigate the reason for revision and to assess the amount of bone ingrowth in retrieved porous tantalum components. In a prospective multicenter retrieval program, 76 porous tantalum acetabular shells, 5 femoral stems, 7 patellas and 36 tibial trays were collected from revision surgeries. A subset of the implants were analyzed for bone ingrowth. The main reason for revision was infection for acetabular shells (1.4 year implantation time) and instability for tibial trays (1.8 years implantation time). Two of the thirty primary surgery acetabular shells and one of the thirty-six primary surgery tibial trays were revised for implant loosening. We observed full depth penetration of bone into the porous tantalum layer for the acetabular shells and femoral stems.

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In both cases, wear debris and inflammation may have contributed to osteolysis. Surgeons using ProDisc prostheses should be aware of these rare complications.

We aimed to assess the clinical efficacy of glucose-insulin-potassium (GIK) in acute myocardial infarction. Experimental data provided evidence of the beneficial effects of GIK on ischemic myocardium. The clinical trials, mostly uncontrolled and conducted mainly before the thrombolytic era, were inconclusive due to the small number of patients and discrepancies in protocols. In order to evaluate the efficacy of this intervention, we have performed a prospective multicenter randomized study. The study consisted of 954 patients with acute myocardial infarction (MI) randomized within 24 hours from the onset of symptoms to low-dose GIK (n = 494), which consisted of 1000 mL 10% dextrose, 32-20 U insulin, and 80 mEq K-, or to the control group (n = 460), which was given 1000 mL 0.89% sodium chloride, by intravenous 24-hour infusion at a rate of 42 mL/h. Cardiac mortality and the occurrence of cardiac events at 35 days did not differ between GIK and control-allocated patients (32 (6.5%) vs. 21 (4.6%), respectively; OR 1.45, 95% CI 0.79-2.68, P = 0.20; and 214 (43.3%) vs. 192 (41.7%), OR 1.07, 95% CI 0.82-1.38, P = 0.62). Total mortality at 35 days was significantly higher in the GIK than in the control group (44 (8.9%) vs. 22 (4.8%), respectively, OR 1.95, 95% CI 1.12-3.47, P = 0.01). The excess of non-cardiac deaths in the GIK group may have occurred by chance. Low-dose GIK treatment does not improve the survival and clinical course in acute MI.

Due to the stable oxidative and mechanical properties, EtO-sterilized tibial components appear to be an effective alternative to gamma-sterilized inserts, at least in short-term implantations.

Contemporary total knee designs incorporating highly porous metallic surfaces have demonstrated promising clinical outcomes. However, stiffness differences between modular and monoblock porous tantalum tibial trays may affect bone ingrowth. This study investigated effect of implant design, spatial location and clinical factors on bone ingrowth in retrieved porous tantalum tibial trays. Three modular and twenty-one monoblock tibial trays were evaluated for bone ingrowth. Nonparametric statistical tests were used to investigate differences in bone ingrowth measurements by implant design, spatial location on the tray, substrate depth and clinical factors. Modular trays (5.3±3.2%) exhibited higher bone ingrowth than monoblock trays (1.6±1.9%, p=0.032). Bone ingrowth in both designs was highest in the initial 500 μm from the surface. Implantation time was positively correlated with bone ingrowth for monoblock trays.