Day-case success rates after primary total hip arthroplasty (THA), total knee arthroplasty (TKA), and medial unicompartmental knee arthroplasty (mUKA) may vary, and detailed data are needed on causes of not being discharged. The aim of this study was to analyze the association between surgical procedure type and successful day-case surgery, and to analyze causes of not being discharged on the day of surgery when eligible and scheduled for day-case THA, TKA, and mUKA. A multicentre, prospective consecutive cohort study was carried out from September 2022 to August 2023. Patients were screened for day-case eligibility using well defined inclusion and exclusion criteria, and discharged when fulfilling predetermined discharge criteria. Day-case eligible patients were scheduled for surgery with intended start of surgery before 1.00 pm.Aims
Methods
The primary outcome was investigating differences in wear, as measured by femoral head penetration, between cross-linked vitamin E-diffused polyethylene (vE-PE) and cross-linked polyethylene (XLPE) acetabular component liners and between 32 and 36 mm head sizes at the ten-year follow-up. Secondary outcomes included acetabular component migration and patient-reported outcome measures (PROMs) such as the EuroQol five-dimension questionnaire, 36-Item Short-Form Health Survey, Harris Hip Score, and University of California, Los Angeles Activity Scale (UCLA). A single-blinded, multi-arm, 2 × 2 factorial randomized controlled trial was undertaken. Patients were recruited between May 2009 and April 2011. Radiostereometric analyses (RSAs) were performed from baseline to ten years. Of the 220 eligible patients, 116 underwent randomization, and 82 remained at the ten-year follow-up. Eligible patients were randomized into one of four interventions: vE-PE acetabular liner with either 32 or 36 mm femoral head, and XLPE acetabular liner with either 32 or 36 mm femoral head. Parameters were otherwise identical except for acetabular liner material and femoral head size.Aims
Methods
Increased collection of patient-reported outcome measures (PROM) in registries enables international comparison of patient-centered outcomes after knee and hip replacement. We aimed to investigate 1) variations in PROM improvement, 2) the possible confounding factor of BMI, and 3) differences in comorbidity distributions between registries. Registries affiliated with the International Society of Arthroplasty Registries (ISAR) or OECD membership countries were invited to report aggregate EQ-5D, OKS, OHS, HOOS-PS and KOOS-PS values. Eligible patients underwent primary total, unilateral knee or hip replacement for osteoarthritis within three years and had completed PROMs preoperatively and either 6 or 12 months postoperatively, excluding patients with subsequent revisions. For each PROM cohort, Chi-square tests were performed for BMI distributions across registries and 12 predefined PROM strata (male/female, age 20-64/65-74/>75, high or low preoperative PROM scores). Comorbidity distributions were reported for available comorbidity indexes. Thirteen registries from 9 countries contributed data, n~130000 knee (range 140 to 79848) and n~113000 hip (range 137 to 85281). Mean EQ-5D index values (10 registries) ranged from 0.53 to 0.71 (knee) and 0.50 to 0.70 (hips) preoperatively and 0.78 to 0.85 (knee) and 0.83 to 0.87 (hip) postoperatively. Mean OKS (6 registries) ranged from 19.3 to 23.6 preoperatively and 36.2 to 41.2 postoperatively. Mean OHS (7 registries) ranged from 18.0 to 23.2 preoperatively and 39.8 to 44.2 postoperatively. Four registries reported KOOS-PS and three reported HOOS-PS. Proportions of patients with BMI >30 ranged from 35 to 62% (10 knee registries) and 16 to 43% (11 hip registries). For both knee and hip registries, distributions of patients across six BMI categories differed significantly among registries (p30 were for patients in the youngest age groups (20 to 64 and 65 to 74 years) with the lowest baseline scores. Additionally, females with lowest preoperative PROM scores had highest BMI. These findings were echoed for the OHS and OKS cohorts. Proportions of patients with ASA scores ≥3 ranged from 7 to 42% (9 knee registries) and 6 to 35% (8 hip registries). PROM-score improvement varies between international registries, which may be partially explained by differences in age, sex and preoperative scores. BMI and comorbidity may be relevant to adjust for.
Previous publications have suggested that the incidence of revisions due to infection after THA is increasing. We performed updated time-trend analyses of risk and timing of revision due to infection after primary THAs in the Nordic countries during the period 2004–2018. 569,463 primary THAs reported to the Nordic Arthroplasty Register Association from 2004 through 2018 were studied. We estimated adjusted hazard ratios (aHR) with 95% confidence interval by Cox regression with the first revision due to infection after primary THA as endpoint. The risk of revision was investigated. In addition, we explored changes in the time span from primary THA to revision due to infection.Aim
Methods
Young patients are at increased risk of revision after primary THA (THA). The bearing surface may be of importance for the longevity of the joint. We aimed to compare the risk of revision of primary stemmed cementless THA with MoM and CoC with metal-on-highly-crosslinked-polyethylene (MoXLP) bearings in patients between 20–54 years. From NARA, we included 2,153 MoM, 4,120 CoC and 10,329 MoXLP THA operated between 1995 and 2017. Kaplan-Meier estimator was used for calculation of THA survivorship and Cox regression to estimate the hazard ratio (HR) of revision (95% CI) due to any and specific causes. MoXLP was reference. The median follow-up was 10.3 years for MoM, 6.6 years for CoC and 4.8 years for MoXLP. 15 years postoperatively the Kaplan-Meier survival estimates were 80% (78–83%) for MoM, 92% (91–93%) for CoC and 94% (93–95%) for MoXLP. The 0–2, 2–7 and 7–15 years adjusted HRs of revision by any cause were 1.4 (0.9–2.4), 3.2 (2.1–5.1) and 3.9 (1.9–7.9) for MoM and 1.1 (0.8–1.4), 1.0 (0.7–1.3) and 2.5 (1.3–4.8) for CoC bearings. After 7–15 years follow-up, the unadjusted HR of revision due to aseptic loosening was 5.4 (1.2–24) for MoM and 4.2 (0.9–20) for CoC THA. MoM and CoC had a 7–15 year adjusted HR of revision due to ‘other’ causes of 4.8 (1.6–14) and 2.1 (0.8–5.8). MoXLP bearings were associated with better survival than MoM and CoC bearings, mainly because of lower risk of revision due to aseptic loosening and ‘other’ causes.
Hip osteoarthritis (OA) is the leading cause for total hip arthroplasty (THA). Although, being considered as the surgery of the century up to 23% of the patients report long-term pain and deficits in physical function and muscle strength may persist after THA. Progressive resistance training (PRT) appear to improve several outcomes moderately in patients with hip OA. Current treatment selection is based on low-level evidence as no randomised controlled trials have compared THA to non-surgical treatment. The primary objective of this trial is to determine the effectiveness of THA followed by standard care compared to 12 weeks of supervised PRT followed by 12 weeks of optional unsupervised PRT, on changes in hip pain and function, in patients with severe hip OA after 6 months. This is a protocol for a multicentre, parallel-group, assessor blinded, randomised controlled superiority trial. Patients aged ≥50 years with clinical and radiographic hip OA found eligible for THA by an orthopaedic surgeon will be randomised to THA or PRT (allocation 1:1). The primary outcome will be change in patient-reported hip pain and function, measured using the Oxford Hip Score. Key secondary outcomes will be change in the Hip disability and Osteoarthritis Outcome Score subscales, University of California Los Angeles Activity Score, 40-meter fast-paced walk test, 30-second chair stand test, and number of serious adverse events.Introduction and Objective
Materials and Methods
The most frequent indication for revision surgery in total hip arthroplasty (THA) is aseptic loosening. Aseptic loosening is associated with polyethylene liner wear, and wear may be reduced by using vitamin E-doped liners. The primary objective of this study was to compare proximal femoral head penetration into the liner between a) two cross-linked polyethylene (XLPE) liners (vitamin E-doped (vE-PE)) versus standard XLPE liners, and b) two modular femoral head diameters (32 mm and 36 mm). Patients scheduled for a THA were randomized to receive a vE-PE or XLPE liner with a 32 mm or 36 mm metal head (four intervention groups in a 2 × 2 factorial design). Head penetration and acetabular component migration were measured using radiostereometric analysis at baseline, three, 12, 24, and 60 months postoperatively. The Harris Hip Score, University of California, Los Angeles (UCLA) Activity Score, EuroQol five-dimension questionnaire (EQ-5D), and 36-Item Short-Form Health Survey questionnaire (SF-36) were assessed at baseline, three, 12, 36, and 60 months.Aims
Methods
Aseptic loosening is the leading cause of revision of total hip arthroplasty (THA). It is well recognized that an occult infection is the underlying cause of some aseptic revisions. Intraoperative cultures are central to the diagnosis of prosthetic joint infection (PJI). However, the diagnostic and prognostic value of unexpected positive intraoperative cultures remains unclear. The aim was to study whether first-time aseptic revision of a total hip arthroplasty with unexpected bacterial growth in cultures of intraoperatively taken biopsies have an increased risk of secondary revision due to all causes and increased risk of PJI revision, specifically. Cases reported as first-time aseptic loosening revisions to the Danish Hip Arthroplasty Register (DHR) performed during January 1st, 2010, to May 15th, 2016, were included. DHR data were merged with the Danish Microbiology Database, which contains data from all intraoperatively obtained cultures in Denmark. Included first-time revisions were grouped based on the number of positive cultures growing the same bacteria genus: ≥2, 1 and 0 cultures. Revisions were followed until secondary revision, death, or end of follow-up period after one year. Relative risk for secondary revision due to all causes and PJI was estimated.Aim
Method
What is the fate of revision total joint arthroplasty, when conventional tissue sample culture (TSC) is negative and sonication fluid culture (SFC) is positive, in terms of re-revision? We prospectively analyzed explanted prosthetic materials from 211 consecutive cases of total hip and knee arthroplasty revision surgery performed on any indication during a one year period. We used a sonication apparatus and protocol that was previously described [Borens et al, 2013. J Orthop Res]. Sampling of five periprosthetic tissue biopsies was performed according to the local protocol and incubated for 5 days. In our non-interventional study design, clinicians were blinded to the results from sonication-culture, which were not used for the subsequent treatment strategy. In cases with suspected deep infection, thorough debridement was performed during revision surgery, and routine antibiotic treatment was dicloxacillin for 6–8 weeks. Patients were routinely seen in the outpatient clinic after 3 and 12 months, where clinical examination and any antibiotic treatment were documented. Minimum follow-up was 1 year. This cohort study is reported according to the STROBE guidelines.Aim
Method
To study whether revision for prosthetic joint infection (PJI) after early PJI in primary Total Hip Arthroplasty (THA) is associated with a high mortality, when compared with: Patients, who did not undergo revision for any reason and Patients who underwent an aseptic revision. This population-based cohort study was based on the Danish Hip Arthroplasty Register on primary THA performed in Denmark from 2005 to 2014. Data from the Danish Hip Arthroplasty Register were linked to microbiology databases, the National Register of Patients, and the Civil Registration System to obtain data on microbiology, comorbidity, and vital status on all patients. The mortality risk for the patients who underwent revision for PJI within 1 year from implantation of primary THA was compared with (1) the mortality risk for patients who did not undergo revision for any reason within 1 year of primary THA; and (2) the mortality risk for patients who underwent an aseptic revision.Aim
Method
The primary aim of this in vitro study was to test the efficacy of daptomycin to eradicate staphylococcal biofilms on various orthopedic implant surfaces and materials. The secondary aim was to quantitatively estimate the formation of staphylococcal biofilm on various implant materials with different surface properties. We tested six clinically important biomaterials: cobalt chrome alloy, pure titanium, grid-blasted titanium, porous plasma-coated titanium with/without hydroxyapatite, and polyethylene. Two laboratory strains of bacteria commonly causing PJI were used, namely The time to detection expressed as the heat flow >50 µW (TTD-50) indirectly quantifies the initial amount of biofilm bacteria, with a shorter TTD-50 representing a larger amount of bacteria.Aim
Method
The metal on metal implants was introduced without the proper stepwise introduction. The ASR resurfacing hip arthroplasty (RHA) withdrawn due to high clinical failure rates and the large diameter head THA (LDH-THA) are also widely abandoned. Early (2 year) radiostereometry studies does not support early instability as cause of failure but more likely metal wear products. A possible advantage may be maintenance of bone mineral density (BMD). We present 5 year prospective follow up from a randomized series, aiming to report changes from baseline and to investigate links between implant micromotion, Cr & Co ions and BMD. Patients eligible for an artificial hip were randomized to RHA, Biomet LDH-THA or standard Biometric THA. 19, 17 and 15 patients completed 5 year follow-up. All followed with BMD of the femur, acetabulum and for RHA the collum. RHA and THA with whole blood Co and Co. LDH-THA only at 5 year. RHA had marker based RSA of both components, cup only for LDH-THA. Translations were compiled to total translation (TT= √(x2+y2+z2)). Data were collected at baseline, 8 weeks, 6 months, 1, 2 and 5 years. Statistical tests: ANCOVA for TT movement, Spearman's correlation for BMD, Cr, Co and BMI to TT at 5 years RSA: The 5 year median (25%to75%) RHA cup translations were X=-0.00(−0.49 to 0.19) Y=0.15(−0.03 to 0.20), z=0.24(−0.42 to 0.37) and TT 0.58 (0.16 to 1.82) mm. For the LDH-THA X=−0.33(−0.90 to 0.20) Y=0.28(0.02 to 0.54), z=0.43(−1.12 to −0.19) and TT 1.06 (0.97 to 1.72) mm. The TT was statistically different (p<0.05) for the two cups. The RHA femoral component moved X=0.37(0.21 to 0.56) Y=0.02(−0.07 to 0.11), z=-0.01(−0.07 to 0.26) and TT 0.48 (0.29 to 0.60) mm at 5 years. There was no TT movement from year 2. The mean (SD) acetabular BMD was diminished to 93(90–97)% for RHA and 97(93–99.9)% for THA, but LDH-THA maintained 99(95–103)%. Overall femoral BMD was unchanged at 5 years for all interventions, but both stemmed implants lost 17% at the calcar. Median (25%to75%) whole-blood Cr peaked in the LDH-THA group with 1.7 (0.9 to 3.1) followed by RHA 1.2 (0.8 to 5.0) and THA with 0.5 (0.4 to 0.7)ppb. For Co the highest levels were found in RHA with 1.6(0.8 to 4.7) followed by LDH-THA 1.2 (0.7–1.7) and THA 0.2 (0.2 to 0.6) ppb. The only correlations above +/−0.3 for TT were the RHA femoral component with a correlation of 0.47 to BMI, 0.30 to Co and Cr. The ASR cup conversely had a negative correlation of −0.60 to BMI and again, the LDH-THA cup had a negative correlation of −0.37 to Cr. In contrast to registered revision rates, we found significantly larger movement for the Biomet cup than the ASR cup. The metal ion levels were similar. The LDH-THA cup maintained the acetabular BMD best at 5 years, but the difference was small, we are limited by small numbers and the correlations between TT and the covariates showed no clear pattern.
We conducted a randomized controlled trial (RCT) to investigate if iodine impregnated incision drapes (IIID) increases bacterial recolonization rates compared to no drape use under conditions of simulated total knee arthroplasty (TKA) surgery. Background: To prevent surgical site infection (SSI), one of the important issues is managing the patient´s own skin flora. Many prophylactic initiatives have been suggested, including the use of IIID. IIID has been debated for many years and was deemed ineffective in preventing SSI in a recent systematic review [1], while some evidence suggests a potential increase in postoperative infection risk, as a result of IIID use [2]. IIID is sparsely investigated in orthopaedic surgery. An increase in the number of viable bacteria in the surgical field of an arthroplasty operation has a potential to increase the risk of SSI in an otherwise elective and clean procedure [3]. 20 patients scheduled for TKA were recruited. Each patient had one knee randomized for draping with IIID [4] while the contralateral knee was left bare, thus the patients acted as their own controls. Operating theater settings with laminar airflow and standard perioperative procedures were simulated. Sampling was performed with the cup-scrup technique [5] using appropriate neutralizers. Samples were collected from the skin of each knee prior to disinfection and on 2 occasions after skin-preparation, 75 minutes apart. Bacterial quantities were estimated by spread plating with 48-hour aerobic incubation. Outcome was measured as colony forming units per square centimeter of skin. We used Wilcoxon signed-rank test for comparative analysis within and between knees. Following skin-disinfection we found no significant difference in bacterial quantities between the intervention and the control knee (p = 0.388). Neither did we see any difference in bacterial quantities between the two groups after 75 minutes of simulated surgery (p = 0.367). When analyzed within the intervention and control group, bacterial quantities had not significantly increased at the end of surgery when compared to baseline, thus no recolonization was detected (p = 0.665 and 0.609, respectively). Iodine impregnated incision drapes did not increase bacterial recolonization rates in simulated TKA surgery. Thus, the results of this RCT study does not support the hypothesis that iodine impregnated incision drapes promotes bacterial recolonization and postoperative infection risk.
To compare the number of airborne bacteria and particles under laminar airflow (LAF) versus turbulent airflow (TAF) with 100% and 50% reduced fresh air exchange during simulated total hip arthroplasty (THA) Two equally dimensioned operating rooms (OR) build in 2009 with modern ventilation systems of LAF and TAF respectively were used during 32 simulated THA-operations under four different ventilation conditions: LAF or TAF with either full (n=8+8) or 50% reduced (n=8+8) fresh air exchange volume. We followed a protocol controlling the complete perioperative setup including interior cleaning, sterile materials, OR-personnel procedures, surgical clothing, instruments and 50-minute surgical procedure on a full-sized dummy at 37°C. Microbial contamination was determined intra-operatively by ISO-validated Microbiological Active Sampler (MAS-100, Merck, 100 L/min) at two 10-minute intervals in 30 cm distance of the operating field. Blood-agar plates from each operation were incubated for 2 days at 35°C and the microbial concentration was determined by viable counting of colony-forming units (CFU) per m3 air. Furthermore airborne particulate (0,5–10 µm) was sampled with ISO-validated light scattering particle analyzer (MET-one, Beckman Coulter, 28,3 L/min) during the 50-minute surgical procedure (1,42 m3/operation). Large particle sizes (>5 µm) are correlated with microbial contamination (Stocks, 2010). According to standards large-sized particle number must not exceed a 2.900/m3-threshold for cleanroom operations. Microbial air concentration (mean CFU/m3 ±standard deviation) under LAF conditions with full and 50% reduced fresh air exchange were 0,4±0,8 and 0,4±0,4 respectively, whereas air contamination under TAF conditions were significantly higher with 7,6±2,0 and 10,3±8,1 (p<0,05). Large (>5 µm) airborne particulate (mean no./m3 ±standard deviation) under LAF conditions with full and 50% reduced fresh air exchange were 1.581±2.841 and 1.018±1.084 respectively, whereas particulate under TAF conditions were 7.923±5.151 and 6.157±2.439 respectively. Microbial air contamination was significantly lower under LAF ventilation compared to TAF during simulated THA under both full and 50% reduced fresh air exchange in modern operating theatres used in daily clinic. The number of particles measured under TAF conditions exceeded the threshold for cleanroom operations in 12/16 simulated operations. These findings indicate that LAF reduces the airborne microbial risk factor of surgical site infection in comparison to TAF.
The Danish Hip Arthroplasty Register (DHR) is a national database on total hip arthroplasties (THAs) with a high completeness and validity of registration for primary procedures. The aim was to validate the registration in DHR for revisions due to Prosthetic Joint Infection (PJI). We identified a cohort of patients in the DHR who underwent primary THA from January 1, 2005 to December 31, 2012 and we followed these patients until first-time revision, death, emigration or December 31, 2012. The PJI diagnosis registered was tested against a gold standard encompassing information from microbiology, prescription, and clinical biochemistry registries in combination with clinical findings retrieved from medical records. We estimated the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) with 95% confidence interval (CI) for PJI in DHR alone and in DHR combined with microbiology registries. Out of 37,828 primary THAs, 1,382 were registered with any revision, 232 of which were due to PJI. For PJI revisions in DHR, the sensitivity was 67.0% (CI: 61.0 – 72.6), specificity 95.2% (CI: 93.8 – 96.4), PPV 77.2% (CI: 71.2 – 82.4), and NPV 92.3% (CI 90.7 – 93.8). Combining DHR with microbiology registries led to a notable increased in the sensitivity for PJI revision to 90.3% (CI: 86.1 – 93.5) and likewise for specificity 99.6% (CI: 99.1 – 99.9), PPV 98.4% (CI: 95.9 – 99.6) and NPV 98.5% (CI: 97.6 – 99.1). Only two thirds of PJI revisions were captured in DHR and the PPV was moderate. However, combining DHR with microbiology registries improved the accuracy remarkably. The study was supported by Region of Southern Denmark and Lillebaelt Hospitals.
Despite high revision rates, the mean two year migration of the ASRTM cup is within an acceptable threshold. Slightly higher migration rates found for the M2a- Magnum™ Porous Coated Acetabular Component but longer follow up is needed to establish if this implant is at risk. RSA can detect the migration of an implant, and continuous migration is a predictor for failure (1). The ASRTM resurfacing implant was withdrawn from the marked due to excessive failure rate but showed initial femoral component stability. The aim of this study was to investigate the initial implant stability for the ASR cup as a possible explanation for the high revision rate, and to compare it to another metal on metal (MoM) cup.Summary
Introduction
Total leg muscle function in hip OA patients is not well studied. We used a test-retest protocol to evaluate the reproducibility of single- and multi-joint peak muscle torque and rapid torque development in a group of 40–65 yr old hip patients. Both peak torque and torque development are outcome measures associated with functional performance during activities of daily living. Patients: Twenty patients (age 55.5±3.3, BMI 27.6±4.8) who underwent total hip arthroplasty participated in this study. Reliability: We used the intra-class correlation (ICC) and within subject coefficients of variation (CVws) to evaluate reliability. Agreement: Relative Bland-Altman 95% limits of agreements (LOA) and smallest detectable difference (SDD) were calculated and used for evaluation of measurement accuracy. Parameters: Maximal muscle strength (peak torque, Nm) and rate of torque development (Nm•sec-1) for affected (AF) and non-affected (NA) side were measured during unilateral knee extension-flexion (seated), hip extension-flexion, and hip adduction-abduction (standing), respectively. Contractile RTD100, 200, peak was derived as the average slope of the torque-time curve (torque/time) at 0–100, 0–200 and 0 peak relative to onset of contraction. Protocol: After 5 min level walking at self-selected and maximum speeds each muscle group was tested using 1–2 sub-maximal contraction efforts followed by 3 maximal contractions 4s duration. Statistics: The variance components were estimated using STATA12, with muscle function and occasion as independent variable and patients as random factor, using the restricted maximum likelihood method (=0.05).Introduction
Material and Methods
Metal on metal articulations produce chromium (Cr) and cobalt (Co) debris, particularly when the articulations are worn in. High levels in the peripheral blood are indicative of excess wear and may cause adverse effects. The present RCT investigates metal ion levels and the relationship of Co, Cr ions and lymphocyte counts during the running-in period. Following randomization to RHA (ASRTM, DePuy) or THA we obtained whole blood (wb), and serum (s) samples at baseline, 8 w, 6 m and 1 y. We measured the Co and Cr concentrations, the total lymphocyte count as well as the CD3+, CD4+, CD8+, CD19+ and CD16+/CD56+ sub populations. Cup inclination and anteversion angles came from conventional radiographs. Activity was measured as steps by pedometer and UCLA activity. Data are presented as median (range).Introduction
Materials and Methods
The treatment of femoral neck fracture with internal fixation (IF) is recommended in younger patients and has compared to arthroplasty the advantage of retaining the femoral head. A big problem with osteosynthesis is though failure. Finding predictors for fixation failure is still an ongoing process and osteoporosis has been suggested as a predictor. To correlate bone mineral density (BMD) in regard to failure of IF in osteosynthesized femoral neck fractures.Background
Aim
The combined incubation of a composite scaffold with bone marrow stromal cells in a perfusion bioreactor could make up a novel hybrid graft material with optimal properties for early fixation of implant to bone. The aim of this study was to create a bioreactor activated graft (BAG) material, which could induce early implant fixation similar to that of allograft. Two porous scaffold materials incubated with cells in a perfusion bioreactor were tested in this study. Two groups of 8 skeletally mature female sheep were anaesthetized before aspiration of bone marrow from the iliac crest. For both groups, mononuclear cells were isolated, and injected into a perfusion bioreactor (Millenium Biologix AG, Switzerland). Scaffold granules Ø∼900–1500 μm, ∼88% porosity) in group 1, consisted of hydroxyapatite (HA, 70%) with -tricalcium-phosphate (−TCP, 30%) (Danish Technological Institute, Denmark). The granules were coated with poly-lactic acid (PLA) 12%, in order to increase the mechanical strength of the material (Phusis, France). Scaffold granules Ø∼900–1400 μm, 80% porosity) in group 2 consisted of pure HA/-TCP (Fin Ceramica, Italy). For both groups, cells were incubated in the bioreactor for 2 weeks. Fresh culture medium supplemented with dexamethasone and ascorbic-acid was added every third or fourth day. Porous titanium alloy implants with diameter=length=10mm (Biomet, USA) were inserted bilaterally in each of the distal femurs of the sheep; thus 4 implants in each sheep. The concentric gap (2 mm) surrounding the implant was filled with 1) BAG (autogenous), 2) granules, 3) granules+bone marrow aspirate (BMA, autologous) or 4) allograft. The sheep were euthanized after 6 weeks. Distal femurs were removed and implant-bone samples were divided in two parts. The superficial part was used for mechanical testing and micro-CT scanning, and the profound part for histomorphometry. Push-out tests were performed on an 858 Bionix MTS hydraulic materials testing machine. Shear mechanical properties between implant and newly generated bone were calculated to assess implant fixation. Results were assessed by One-way ANOVA. P-values less than 0.05 were considered significant.Introduction
Methods and Materials
