Use of high resolution dual‐energy x‐ray absorptiometry‐region free analysis (DXA‐RFA) to detect local periprosthetic bone remodeling events

Dual‐energy x‐ray absorptiometry (DXA) is the gold standard method for measuring periprosthetic bone remodeling, but relies on a region of interest (ROI) analysis approach. While this addresses issues of anatomic variability, it is insensitive to bone remodeling events at the sub‐ROI level. We have validated a high‐spatial resolution tool, termed DXA‐region free analysis (DXA‐RFA) that uses advanced image processing approaches to allow quantitation of bone mineral density (BMD) at the individual pixel (data‐point) level. Here we compared the resolution of bone remodeling measurements made around a stemless femoral prosthesis in 18 subjects over 24 months using ROI‐based analysis versus that made using DXA‐RFA. Using the ROI approach the regional pattern of BMD change varied by region, with greatest loss in ROI5 (20%, p < 0.001), and largest gain in ROI4 (6%, p < 0.05). Analysis using DXA‐RFA showed a focal zone of increased BMD localized to the prosthesis–bone interface (30–40%, p < 0.001) that was not resolved using conventional DXA analysis. The 20% bone loss observed in ROI5 with conventional DXA was resolved to a focal area adjacent to the cut surface of the infero‐medial femoral neck (up to 40%, p < 0.0001). DXA‐RFA enables high resolution analysis of DXA datasets without the limitations incurred using ROI‐based approaches. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:712–716, 2015.     

Three‐dimensional imaging and analysis of human cartilage degeneration using Optical Coherence Tomography

Optical Coherence Tomography (OCT) is an evolving imaging technology allowing non‐destructive imaging of cartilage tissue at near‐histological resolution. This study investigated the diagnostic value of real time 3‐D OCT in comparison to conventional 2‐D OCT in the comprehensive grading of human cartilage degeneration. Fifty‐three human osteochondral samples were obtained from eight total knee arthroplasties. OCT imaging was performed by either obtaining a single two‐dimensional cross‐sectional image (2‐D OCT) or by collecting 100 consecutive parallel 2‐D OCT images to generate a volumetric data set of 8 × 8 mm (3‐D OCT). OCT images were assessed qualitatively according to a modified version of the DJD classification and quantitatively by algorithm‐based evaluation of surface irregularity, tissue homogeneity, and signal attenuation. Samples were graded according to the Outerbridge classification and statistically analyzed by one‐way ANOVA, Kruskal Wallis and Tukey's or Dunn's post‐hoc tests. Overall, the generation of 3‐D volumetric datasets and their multiple reconstructions such as rendering, surface topography, parametric, and cross‐sectional views proved to be of potential diagnostic value. With increasing distance to the mid‐sagittal plane and increasing degeneration, score deviations increased, too. In conclusion, 3‐D imaging of cartilage with image analysis algorithms adds considerable potential diagnostic value to conventional OCT diagnostics. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:651–659, 2015.     

Extracorporeal CO2 removal as bridge to lung transplantation in life‐threatening hypercapnia

In patients awaiting lung transplantation (LTX), adequate gas exchange may not be sufficiently achieved by mechanical ventilation alone if acute respiratory decompensation arises. We report on 20 patients with life‐threatening hypercapnia who received extracorporeal CO₂ removal (ECCO2‐R) by means of the interventional lung assist (ILA®, Novalung) as bridge to LTX. The most common underlying diagnoses were bronchiolitis obliterans syndrome, cystic fibrosis, and idiopathic pulmonary fibrosis, respectively. The type of ILA was pumpless arteriovenous or pump‐driven venovenous (ILA activve®, Novalung) in 10 patients each. ILA bridging was initiated in 15 invasively ventilated and five noninvasively ventilated patients, of whom one had to be intubated prior to LTX. Hypercapnia and acidosis were effectively corrected in all patients within the first 12 h of ILA therapy: PaCO₂ declined from 109 (70–146) to 57 (45–64) mmHg, P < 0.0001; pH increased from 7.20 (7.06–7.28) to 7.39 (7.35–7.49), P < 0.0001. Four patients were switched to extracorporeal membrane oxygenation due to progressive hypoxia or circulatory failure. Nineteen patients (95%) were successfully transplanted. Hospital and 1‐year survival was 75 and 72%, respectively. Bridging to LTX with ECCO2‐R delivered by arteriovenous pumpless or venovenous pump‐driven ILA is feasible and associated with high transplantation and survival rates.     

More than a decade after live donor nephrectomy: a prospective cohort study

Previously reported short‐term results after live kidney donation show no negative consequences for the donor. The incidence of new‐onset morbidity takes years to emerge, making it highly likely that this will be missed during short‐term follow‐up. Therefore, evidence on long‐term outcome is essential. A 10‐year follow‐up on renal function, hypertension, quality of life (QOL), fatigue, and survival was performed of a prospective cohort of 100 donors. After a median follow‐up time of 10 years, clinical data were available for 97 donors and QOL data for 74 donors. Nine donors died during follow‐up of unrelated causes to donation, and one donor was lost to follow‐up. There was a significant decrease in kidney function of 12.9 ml/min (P < 0.001) at follow‐up. QOL showed significant clinically relevant decreases of 10‐year follow‐up scores in SF‐36 dimensions of physical function (P < 0.001), bodily pain (P = 0.001), and general health (P < 0.001). MFI‐20 scores were significantly higher for general fatigue (P < 0.001), physical fatigue (P < 0.001), reduced activity (P = 0.019), and reduced motivation (P = 0.030). New‐onset hypertension was present in 25.6% of the donors. Donor outcomes are excellent 10 years post‐donation. Kidney function appears stable, and hypertension does not seem to occur more frequently compared to the general population.     

Cytomegalovirus post kidney transplantation: prophylaxis versus pre‐emptive therapy?

Cytomegalovirus is the most important pathogen causing opportunistic infections in kidney allograft recipients. The occurrence of CMV disease is associated with higher morbidity, higher incidence of other opportunistic infections, allograft loss and death. Therefore, an efficient strategy to prevent CMV disease after kidney transplantation is required. Two options are currently available: pre‐emptive therapy based on regular CMV PCR monitoring and generalized antiviral prophylaxis during a defined period. In this review, we describe those two approaches, highlight the distinct advantages and risks of each strategy and summarize the four randomized controlled trials performed in this field so far. Taken this evidence together, pre‐emptive therapy and anti‐CMV prophylaxis are both equally potent in preventing CMV‐associated complications; however, the pre‐emptive approach may have distinct advantages in allowing for development of long‐term anti‐CMV immunity. We propose a risk‐adapted use of these approaches based on serostatus, immunosuppressive therapy and availability of resources at a particular transplant centre.