Jarmo Gunn

Bone attachment to glass-fibre-reinforced composite implant with porous surface.

A method has recently been developed for producing fibre-reinforced composites (FRC) with porous surfaces, intended for use as load-bearing orthopaedic implants. This study focuses on evaluation of the bone-bonding behaviour of FRC implants. Three types of cylindrical implants, i.e. FRC implants with a porous surface, solid polymethyl methacrylate (PMMA) implants and titanium (Ti) implants, were inserted in a transverse direction into the intercondular trabeculous bone area of distal femurs and proximal tibias of New Zealand White rabbits. Animals were sacrificed at 3, 6 and 12 weeks post operation, and push-out tests (n=5-6 per implant type per time point) were then carried out. At 12 weeks the shear force at the porous FRC-bone interface was significantly higher (283.3+/-55.3N) than the shear force at interfaces of solid PMMA/bone (14.4+/-11.0 N; p<0.001) and Ti/bone (130.6+/-22.2N; p=0.001). Histological observation revealed new bone growth into the porous surface structure of FRC implants. Solid PMMA and Ti implants were encapsulated mostly with fibrous connective tissue. Finite element analysis (FEA) revealed that porous FRC implants had mechanical properties which could be tailored to smooth the shear stress distribution at the bone-implant interface and reduce the stress-shielding effect.

Use of blood products and risk of stroke after coronary artery bypass surgery

BACKGROUND The impact of blood transfusion on the development of post-operative stroke after coronary artery bypass grafting (CABG) is not well established. We, therefore, investigated this issue. MATERIALS AND METHODS Complete data on peri-operative blood transfusion were available for 2,226 patients who underwent CABG in three Finnish hospitals. RESULTS Stroke occurred post-operatively in 53 patients (2.4%). Logistic regression showed that pre-operative creatinine (OR 1.003, 95% CI 1.000-1.006), extracardiac arteriopathy (OR 2.344, 95% CI 1.133-4.847), pre-operative atrial fibrillation (OR 2.409, 95% CI 1.149-5.052), and the number of packed red blood cell units transfused (OR 1.121, 95% CI 1.065-1.180) were significantly associated with post-operative stroke. When the various blood product transfusions instead of transfused units were included in the multivariable analysis, solvent/detergent treated plasma (Octaplas) transfusion (OR 2.149, 95% CI 1.141-4.047), but not red blood cell transfusion, was significantly associated with postoperative stroke. Use of blood products ranging from no transfusion (stroke rate 1.6%) to combined transfusion of red blood cells, platelets and Octaplas was associated with a significant increase in post-operative stroke incidence (6.6%, adjusted analysis: OR 1.727, 95% 1.350-2.209). Patients who received >2 units of red blood cells, >4 units of Octaplas units and >8 units of platelets had the highest stroke rate of 21%. CART analysis showed that increasing amount of transfused Octaplas, platelets and history of extracardiac arteriopathy were significantly associated with post-operative stroke. CONCLUSIONS Transfusion of blood products after CABG has a strong, dose-dependent association with the risk of stroke. The use of Octaplas and platelet transfusions seem to have an even larger impact on the development of stroke than red blood cell transfusions.

Repair of bone segment defects with surface porous fiber‐reinforced polymethyl methacrylate (PMMA) composite prosthesis: Histomorphometric incorporation model and characterization by SEM

Background and purpose Polymer technology has provided solutions for filling of bone defects in situations where there may be technical or biological complications with autografts, allografts, and metal prostheses. We present an experimental study on segmental bone defect reconstruction using a polymethylmethacrylate‐(PMMA‐) based bulk polymer implant prosthesis. We concentrated on osteoconductivity and surface characteristics. Material and methods A critical size segment defect of the rabbit tibia in 19 animals aged 18–24 weeks was reconstructed with a surface porous glass fiber‐reinforced (SPF) prosthesis made of polymethylmethacrylate (PMMA). The biomechanical properties of SPF implant material were previously adjusted technically to mimic the properties of normal cortical bone. A plain PMMA implant with no porosity or fiber reinforcement was used as a control. Radiology, histomorphometry, and scanning electron microscopy (SEM) were used for analysis of bone growth into the prosthesis during incorporation. Results The radiographic and histological incorporation model showed good host bone contact, and strong formation of new bone as double cortex. Histomorphometric evaluation showed that the bone contact index (BCI) at the posterior surface interface was higher with the SPF implant than for the control. The total appositional bone growth over the posterior surface (area %) was also stronger for the SPF implant than for controls. Both bone growth into the porous surface and the BCI results were related to the quality, coverage, and regularity of the microstructure of the porous surface. Interpretation Porous surface structure enhanced appositional bone growth onto the SPF implant. Under load‐bearing conditions the implant appears to function like an osteoconductive prosthesis, which enables direct mobilization and rapid return to full weight bearing.

Incidence and risk factors of postpericardiotomy syndrome requiring medical attention: The Finland postpericardiotomy syndrome study

OBJECTIVES Postpericardiotomy syndrome is a well-known complication after cardiac surgery. Nevertheless, little is known about the incidence and predictors of postpericardiotomy syndrome requiring medical attention or hospitalization in a contemporary set of patients undergoing isolated coronary bypass. METHODS This retrospective analysis included 688 patients from 2008 to 2010. The median follow-up time was 5.3 [4.5-6.0] years. RESULTS The incidence of postpericardiotomy syndrome was 61 of 688 patients (8.9%), and the median time to diagnosis was 21 [11-52] days, but only 13 patients (22%) required pleural drainage and 3 patients (4.9%) required pericardiocentesis. Patients with postpericardiotomy syndrome more often had 1 or more red blood cell units transfused (61% vs 43%, P = .008) after surgery and less often had diabetes (12% vs 31% P = .002) or metformin medication (3.3% vs 20%, P = .001) compared with those without postpericardiotomy syndrome. In multivariable Cox regression model, renal insufficiency and 1 or more red blood cell units transfused remained as independent predictors of postpericardiotomy syndrome and diabetes remained as a protective factor. Incidence of recurrences was high (38%), and increasing body mass index was the only predictor of relapse. CONCLUSIONS The incidence of symptomatic postpericardiotomy syndrome leading to medical care contact was markedly lower compared with that reported in older clinical studies. Postpericardiotomy syndrome was associated with the use of red blood cell units and was less common in patients with medically treated diabetes.

Comparison of Results of Coronary Artery Bypass Grafting Versus Percutaneous Coronary Intervention in Octogenarians

The aim of the present study was to compare the outcomes after coronary artery bypass grafting (CABG) and percutaneous coronary intervention (PCI) in patients aged ≥80 years. The present analysis included 274 patients who underwent isolated CABG and 393 patients who underwent PCI. The patients undergoing PCI had a greater prevalence of a history of cardiac surgery and recent myocardial infarction and had more frequently undergone emergency revascularization. Patients undergoing CABG had a significantly greater prevalence of 3-vessel coronary artery disease. The unadjusted 30-day mortality rate was 8.8% after CABG and 7.4% after PCI (p = 0.514). However, on multivariate analysis, CABG was associated with a significantly increased risk of 30-day mortality (odds ratio 2.246, 95% confidence interval 1.141 to 4.422). The unadjusted overall intermediate survival was significantly poorer after PCI (at 5 years, CABG 72.2% vs PCI 59.5%, p = 0.004), but this was not confirmed on multivariate analysis. PCI and CABG had similar intermediate survival rates when adjusted for propensity score (p = 0.698), a finding confirmed by the analysis of 130 propensity score-matched pairs (at 5 years, CABG 66.4% vs PCI 58.9%, p = 0.730). In conclusion, the survival of patients aged ≥80 years undergoing CABG is excellent, and the suboptimal survival after PCI seems to be related to the disproportionately greater risk of these patients compared to those undergoing CABG. When adjusted for important clinical variables, PCI and CABG achieved similar intermediate results.

Comparison of the osteoconductive properties of three particulate bone fillers in a rabbit model: Allograft, calcium carbonate (Biocoral®) and S53P4 bioactive glass

Abstract Aim. The aim of this study was to compare the osteoconductivity and suitability of three biomaterials used as particulate fillers; S53P4 bioactive glass, allogeneic fresh frozen bone and coral-derived calcium carbonate. Materials and methods. Materials were implanted into drill-holes in the femoral condyles of adult rabbits. Follow-ups were performed at 3, 6, 12 and 24 weeks. Host–response, osteoconductivity, bonding and filler-effect were evaluated by SEM, EDXA and histology and histomorphometry to evaluate. Results. All three materials were found to be biocompatible and osteoconductive. Defects filled with allograft seemed to have more bone at 24 weeks, although no statistically significant difference in new bone growth was found. In earlier time points, coral, however, was observed to degrade more quickly, leaving more empty space in the defects, thus making it a less suitable filler for cavitary defects. Conclusion. At all time points there was less filler material (i.e. biomaterial and new bone) in coral-filled defects than in BAG or allograft filled defects (p < 0.05).

Outcome after coronary artery bypass grafting and percutaneous coronary intervention in patients with stage 3b–5 chronic kidney disease

OBJECTIVES Patients with chronic kidney disease (CKD) are generally considered to be at an increased risk for cardiovascular events and cardiac mortality. The prognostic significance of severe renal impairment in patients undergoing coronary revascularization remains mainly unknown because these patients have been excluded from randomized clinical trials. The aim of the present study was to compare the outcome after percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG) in patients with an estimated glomerular filtration rate (eGFR) of <45 ml/min/m(2). METHODS This retrospective study includes 110 patients who underwent PCI and 148 patients who underwent isolated CABG between 2007 and 2010. All patients had stage 3b-5 CKD (eGFR <45 ml/min/m(2)). RESULTS The median follow-up time was 25 (interquartile range 30) months. At 30 days and 3 years, postoperative de novo dialysis was required in 3.4 and 16.2% of CABG patients and in 0 and 6.6% (P = 0.10) of PCI patients. PCI was associated with similar mortality at 30 days (PCI 10.0% and CABG 12.2%, P = 0.068). At 3 years, PCI was associated with a significantly higher risk of mortality (50.4 vs 32.9, adjusted analysis: HR 1.77, 95% CI 1.13-2.77), repeat revascularization (20.3 vs 0.8%, too few for adjusted analysis) and major adverse cardiac and cerebrovascular events (57.8 vs 34.3%, HR 2.19, 95% CI 1.41-3.40). These findings were supported by propensity score-matched analysis. CONCLUSION Patients with moderate to severe CKD have a high rate of mortality and morbidity after either PCI or CABG. The fear of postoperative dialysis rates after CABG appears overemphasized since less than 5% of patients needed dialysis in the early postoperative period. This study provides evidence that this high-risk subset of patients should also be revascularized according to general recommendations. When feasible, CABG could be associated with better survival and freedom from cardiovascular events than PCI.

Comparison of 30-day and 5-year outcomes of percutaneous coronary intervention versus coronary artery bypass grafting in patients aged≤50 years (the Coronary aRtery diseAse in younG adultS Study).

Data on the outcome of young patients after coronary artery bypass grafting (CABG) and percutaneous coronary intervention (PCI) are scarce. Data on 2,209 consecutive patients aged≤50 years who underwent CABG or PCI were retrospectively collected from 15 European institutions. PCI and CABG had similar 30-day mortality rates (0.8% vs 1.4%, p=0.27), late survival (at 5 years, 97.8% vs 94.9%, p=0.082), and freedom from stroke (at 5 years, 98.0% and 98.0%, p=0.731). PCI was associated with significantly lower freedom from major adverse cardiac and cerebrovascular events (at 5 years, 73.9% vs 85.0%, p<0.0001), repeat revascularization (at 5 years, 77.6% vs 92.5%, p<0.0001), and myocardial infarction (at 5 years, 89.9% vs 96.6%, p<0.0001) compared with CABG. These findings were confirmed in propensity score-adjusted and matched analyses. Freedom from major adverse cardiac and cerebrovascular events after PCI was particularly low in diabetics (at 5 years, 58.0% vs 75.9%, p<0.0001) and in patients with multivessel disease (at 5 years, 63.6% vs 85.1%, p<0.0001). PCI in patients with ST elevation myocardial infarction was associated with significantly better 5-year survival (97.5% vs 88.8%, p=0.001), which was driven by its lower 30-day mortality rate (1.5% vs 6.0%, p=0.017). In conclusion, patients aged≤50 years have an excellent immediate outcome after either PCI or CABG with similar long-term survival when used according to the current clinical practice. PCI was associated with significantly lower freedom from myocardial infarction and repeat revascularization.

Timing of Preoperative Aspirin Discontinuation and Outcome After Elective Coronary Artery Bypass Graft Surgery

OBJECTIVE Whether aspirin should be discontinued before coronary artery bypass grafting is controversial. The potential benefits and harms associated with late use of aspirin (no discontinuation or discontinuation <3 days before surgery) were investigated in this retrospective, multicenter study. DESIGN Retrospective, multicenter study. SETTING Two university hospitals and one central hospital. PARTICIPANTS A consecutive series of 859 patients who underwent elective coronary artery bypass grafting from January 2008 through December 2010. INTERVENTIONS Aspirin (100 mg/day) was used <3 days before surgery in 240 patients and was discontinued >3 days before surgery in 619 patients. RESULTS In the overall series, similar in-hospital mortality, amount of postoperative blood loss, rate of re-exploration for excessive bleeding, and use of blood products were observed in the study groups. However, aspirin discontinuation >3 days before surgery tended to be associated with a higher postoperative stroke rate (1.9% v 0.4%, p = 0.13). Such a trend was observed after off-pump (1.9% v 0%, p = 0.58) and on-pump (2.0% v 0.6%, p = 0.46) surgery. Among 153 pairs matched by the propensity score, patients with aspirin discontinued >3 days before surgery had a significantly higher rate of postoperative stroke (5.9% v 0.7%, p = 0.02) and tended to have a higher risk of the composite adverse outcome endpoint (19.6% v 12.4%, p = 0.09). The postoperative release of troponin I was similar in the study groups. CONCLUSIONS Late or no discontinuation of low-dose aspirin before coronary artery bypass grafting may decrease the risk of postoperative stroke without increased postoperative bleeding and need for blood transfusion. These findings and the risk of cardiovascular events possibly occurring at the time of its discontinuation suggest that the use of aspirin until the day of elective coronary surgery may be beneficial.

The effect of heat treatment of wood on osteoconductivity.

Wood is a natural porous fibre composite, which has some structural similarities to bone. Recently, it has been used as a modelling material in developing synthetic fibre-reinforced composite to be used as load-bearing non-metallic artificial bone material. In this study, the behaviour of wood implanted into bone was studied in vivo in the femur bone of the rabbit. Wood was pre-treated by heat, which altered its chemical composition and structure, as well as the biomechanical properties. In the heat treatment, woods dimensional stability is enhanced, equilibrium moisture content reduces and the biological durability increases. Cone-shaped implants were manufactured from heat-treated (at 200 and 140 degrees C) birch wood (Betula pubescens) and from untreated birch. A total of 62 implants were placed in the distal femur of 50 white New Zealand rabbits. The behaviour of the implants was studied at 4, 8 and 20 weeks with histological and histometrical analysis. Osteoconductive contact line and the presence of fibrous tissue and foreign body reaction were determined. The amount of fibrous tissue diminished with time, and the absence of foreign body reaction was found to be in correlation to the amount of heat treatment. Histologically found contact between the implant and the host bone at the interface was significantly more abundant in the 200 degrees C group (avg. 12.8%) vs. the 140 degrees C (avg. 2.7%) and the untreated groups (avg. 0.6%). It was observed that the heat treatment significantly modified the biological behaviour of the implanted wood. The changes of the wood by heat treatment showed a positive outcome concerning osteoconductivity of the material.