Reduction of cement leakage by sequential PMMA application in a vertebroplasty model

PURPOSE Leakage is the most common complication of percutaneous cement augmentation of the spine. The viscosity of the polymethylmethacrylate (PMMA) cement is strongly correlated with the likelihood of cement leakage. We hypothesized that cement leakage can be reduced by sequential cement injection in a vertebroplasty model. METHODS A standardized vertebral body substitute model, consisting of aluminum oxide foams coated by acrylic cement with a preformed leakage path, simulating a ventral vein, was developed. Three injection techniques of 6 ml PMMA were assessed: injection in one single step (all-in-one), injection of 1 ml at the first and 5 ml at the second step with 1 min latency in-between (two-step), and sequential injection of 0.5 ml with 1-min latency between the sequences (sequential). Standard PMMA vertebroplasty cement was used; each injection type was tested on ten vertebral body substitute models with two possible leakage paths per model. Leakage was assessed by radiographs using a zonal graduation: intraspongious = no leakage and extracortical = leakage. RESULTS The leakage rate was significantly lower in the "sequential" technique (2/20 leakages) followed by "two-step" (15/20) and "all-in-one" (20/20) techniques (p < 0.001). The RR for a cement leakage was 10.0 times higher in the "all-in-one" compared to the "sequential" group (95 % confidence intervals 2.7-37.2; p < 0.001). CONCLUSIONS The sequential cement injection is a simple approach to minimize the risk for leakage. Taking advantage of the temperature gradient between body and room temperature, it is possible to increase the cement viscosity inside the vertebra while keeping it low in the syringe. Using sequential injection of small cement volumes, further leakage paths are blocked before further injection of the low-viscosity cement.

Lavage prior to vertebral augmentation reduces the risk for cement leakage

PURPOSE This study aimed at assessing the cement leakage rate and the filling pattern in patients treated with vertebroplasty, kyphoplasty and stentoplasty with and without a newly developed lavage technique. STUDY DESIGN Retrospective clinical case-control study. METHODS A newly developed bipedicular lavage technique prior to cement application was applied in 64 patients (45.1 %) with 116 vertebrae, ("lavage" group). A conventional bipedicular cement injection technique was used in 78 patients (54.9 %) with 99 levels ("controls"). The outcome measures were filling patterns and leakage rates. RESULTS The overall leakage rate (venous, cortical defect, intradiscal) was 37.9 % in the lavage and 83.8 % in the control group (p < 0.001). Venous leakage (lavage 12.9 % vs. controls 31.3 %; p = 0.001) and cortical defect leakage (lavage 17.2 % vs. controls 63.3 %; p < 0.001) were significantly lower in the lavage group compared to "controls," whereas intradiscal leakages were similar in both groups (lavage 12.1 % vs. controls 15.2 %; p = 0.51). For venous leakage multivariate logistic regression analysis showed lavage to be the only independent predictor. Lavage was associated with 0.33-times (95 % CI 0.16-0.65; p = 0.001) lower likelihood for leakage in compared to controls. CONCLUSIONS Vertebral body lavage prior to cement augmentation is a safe technique to reduce cement leakage in a clinical setting and has the potential to prevent pulmonary fat embolism. Moreover, a better filling pattern can be achieved.

Evaluation of New Cone-beam Computed Tomographic Criteria for Radiographic Healing Evaluation after Apical Surgery: Assessment of Repeatability and Reproducibility.

INTRODUCTION Conventional 2-dimensional radiography uses defined criteria for outcome assessment of apical surgery. However, these radiographic healing criteria are not applicable for 3-dimensional radiography. The present study evaluated the repeatability and reproducibility of new cone-beam computed tomographic (CBCT)-based healing criteria for the judgment of periapical healing 1 year after apical surgery. METHODS CBCT scans taken 1 year after apical surgery (61 roots of 54 teeth in 54 patients, mean age = 54.4 years) were evaluated by 3 blinded and calibrated observers using 4 different indices. Reformatted buccolingual CBCT sections through the longitudinal axis of the treated roots were analyzed. Radiographic healing was assessed at the resection plane (R index), within the apical area (A index), of the cortical plate (C index), and regarding a combined apical-cortical area (B index). All readings were performed twice to calculate the intraobserver agreement (repeatability). Second-time readings were used for analyzing the interobserver agreement (reproducibility). Various statistical tests (Cohen, kappa, Fisher, and Spearman) were performed to measure the intra- and interobserver concurrence, the variability of score ratios, and the correlation of indices. RESULTS For all indices, the rates of identical first- and second-time scores were always higher than 80% (intraobserver Cohen κ values ranging from 0.793 to 0.963). The B index (94.0%) showed the highest intraobserver agreement. Regarding interobserver agreement, the highest rate was found for the B index (72.1%). The Fleiss' κ values for R and B indices exhibited substantial agreement (0.626 and 0.717, respectively), whereas the values for A and C indices showed moderate agreement (0.561 and 0.573, respectively). The Spearman correlation coefficients for R, A, C, and B indices all exhibited a moderate to very strong correlation with the highest correlation found between C and B indices (rs = 0.8069). CONCLUSIONS All indices showed an excellent intraobserver agreement (repeatability). With regard to interobserver agreement (reproducibility), the B index (healing of apical and cortical defects combined) and the R index (healing on the resection plane) showed substantial congruence and thus are to be recommended in future studies when using buccolingual CBCT sections for radiographic outcome assessment of apical surgery.

Assessment of the nonoperated root after apical surgery of the other root in mandibular molars: a 5-year follow-up study

INTRODUCTION If a surgical approach is chosen to treat a multirooted tooth affected by persistent periapical pathosis, usually only the affected roots are operated on. The present study assessed the periapical status of the nonoperated root 5 years after apical surgery of the other root in mandibular molars. METHODS Patients treated with apical surgery of mandibular molars with a follow-up of 5 years were selected. Patient-related and clinical parameters (sex, age, smoking, symptoms, and signs of infection) before surgery were recorded. Preoperative intraoral periapical radiographs and radiographs 5 years after surgery were examined. The following data were collected: tooth, operated root, type and quality of the coronal restoration, marginal bone level, length and homogeneity of the root canal filling, presence of a post/screw, periapical index (PAI) of each root, and radiographic healing of the operated root. The presence of apical pathosis of the nonoperated root was analyzed statistically in relation to the recorded variables. RESULTS Thirty-seven patients fulfilled the inclusion criteria. Signs of periapical pathosis in the nonoperated root 5 years after surgery (PAI ≥ 3) could be observed in only 3 cases (8.1%). Therefore, statistical analysis in relation to the variables was not possible. The PAI of the nonoperated root before surgery had a weak correlation with signs of apical pathosis 5 years after surgery. CONCLUSIONS Nonoperated roots rarely developed signs of new apical pathosis 5 years after apical surgery of the other root in mandibular molars. It appears reasonable to resect and fill only roots with a radiographically evident periapical lesion.

Analysis of expansin-induced morphogenesis on the apical meristem of tomato

Our previous work has shown that localised activity of the cell-wall-loosening protein expansin is sufficient to induce primordia on the apical meristem of tomato, consistent with the hypothesis that tissue expansion plays a key role in leaf initiation. In this paper we describe the earliest morphogenic events visible on the surface of the apical meristem of tomato (Lycopersicon esculentum Mill.) following treatment with expansin and report on the spectrum of final structures formed. Our observations are consistent with a proposed primary function of expansin effecting morphogenesis via altered biophysical stress patterns in the meristem. The primordia induced by expansin do not complete the full program of leaf development. We present data indicating that one reason for this might be the inability of exogenous expansin to mimic the endogenous pattern of expansin activity in the meristem. These data provide the first detailed analysis at the cellular level of expansin action on living tissue, the first description of the spectrum of structures induced by expansin on the apical meristem, and give an insight into a potentially fundamental mechanism in plant development.

Prevention of cement leakage into the hip joint by a standard cement plug during PFN-A cement augmentation: a technical note.

Medial penetration of the helical blade into the hip joint after fixation of trochanteric fractures using the proximal femur nail antirotation (PFN-A) is a potential failure mode. In low demand patients a blade exchange with cement augmentation may be an option if conversion to total hip arthroplasty is unfeasible to salvage the cut-through. This article describes a technique to avoid intraarticular cement leakage using a cement plug to close the defect in the femoral head caused by the cut-through.

Solute losses from various shoot parts of field-grown wheat by leakage in the rain

Leakage from field-grown wheat was investigated during two seasons differing considerably in their rainfall patterns. For all solutes analyzed, these losses were low from non-senescing plant parts, increased after the onset of senescence and became maximal in fully senesced (dry, brown) organs. The cumulative losses of potassium by leakage in the rain were 65% of the content at anthesis for the flag leaf and 95% for the third leaf from the top, while these relative values were lower for magnesium (50 to 80%) and calcium (around 55%) and extremely low for sodium (<10%). The differences between potassium and sodium may be due to a different compartmentation on the tissue level or on the subcellular level. It became evident that for certain nutrients (e.g. potassium or magnesium) leakage in the rain may represent a major loss from senescing leaves and can be a relevant flux in maturing wheat.