Pelvic tilt compensates for increased acetabular anteversion

Purpose

Pelvic tilt determines functional orientation of the acetabulum. In this study, we investigated the interaction of pelvic tilt and functional acetabular anteversion (AA) in supine position.

Methods

Pelvic tilt and AA of 138 individuals were measured by computed tomography (CT). AA was calculated in relation to the anterior pelvic plane (APP) and relative to the table plane. We analysed these parameters for gender-specific and age-related differences.

Results

The mean pelvic tilt was -0.1?±?5.5°. Pelvic sagittal rotation displayed no gender nor age related differences. Females showed higher angles of AA compared with males (20.0° vs 17.2°, p?<?0.001; AA relative to the APP). Anterior tilting of the pelvis positively correlated with AA and individuals with high AA had a higher anterior pelvic tilt compared with those with low AA (p?<?0.0001; AA relative to the APP).

Conclusions

AA has to be calculated regarding pelvic sagittal rotation for correct acetabular orientation. Pelvic tilt is dependent on acetabular orientation and compensates for increased AA.

     

Activating clinical inferences: a component of diagnostic reasoning in nursing

In this exploratory study, nursing inferences were examined within a framework of information processing theory. Verbal responses to a patient simulation by 28 nursing students and 15 practicing nurses were used as data. Six different categories of inferences were identified. Inferences most frequently activated across educational levels were those about immediate situational concerns. Practicing nurses activated significantly more complex inferences than the student groups. In each group, the majority of inferences were activated during the first half of the encounter. These results of this preliminary analysis support the proposition that inference activation is an important component of the diagnostic reasoning process used by both nurses and nursing students.     

Diagnostic reasoning strategies of nurses and nursing students

This study described and compared the cognitive strategies of diagnostic reasoning used by junior nursing students (n = 15), senior nursing students (n = 13), and practicing nurses (n = 15). Verbal responses to three videotaped vignettes provided the data. Findings suggested that diagnostic reasoning processes of both nurses and nursing students can be described by a general model developed from studies of physicians. Subjects activated diagnostic hypotheses early in the encounter and used systematic information gathering to rule in and rule out hypotheses. With increased levels of knowledge and experience, there was a trend toward more systematic data acquisition and greater accuracy in diagnosis. The number of hypotheses activated, the earliness with which they were activated, and their diagnostic accuracy were task-specific components of the process, but selection of data-acquisition strategies appeared to be more generalizable across cases.     

Allogenic versus autologous cancellous bone in lumbar segmental spondylodesis: a randomized prospective study

The current gold standard in lumbar fusion consists of transpedicular fixation in combination with an interbody interponate of autologous bone from iliac crest. Because of the limited availability of autologous bone as well as the still relevant donor site morbidity after iliac crest grafting the need exists for alternative grafts with a comparable outcome. Forty patients with degenerative spinal disease were treated with a monosegmental spondylodesis (ventrally, 1 PEEK-cage; dorsally, a screw and rod system), and randomly placed in two groups. In group 1, autogenous iliac crest cancellous bone was used as a cage filling. In group 2 the cages were filled with an allogenic cancellous bone graft. Following 3, 6, 9 and 12 months, the clinical outcome was determined on the basis of: the Oswestry Low Back Pain Disability Questionnaire; patient satisfaction; patient willingness to undergo the operation again; and a visual analog scale for pain. The radiological outcome was based on both fusion rate (radiographs, computed tomography), and on the bone mineral density of the grafts. After 6 months, the X-rays of the patients in group 2 had a significantly lower rate of fusion. Aside from this, there were no further significant differences. After 12 months, radiological results showed a similar fusion rate in both groups. Donor site complications consisted of five patients with hematoma, and three patients with persistent pain in group 1. No implant complications were observed. If a bone bank is available for support and accepting the low risk of possible transmission of infectious diseases, freeze–dried allogenic cancellous bone can be used for monosegmental spondylodeses. The results demonstrated an equivalent clinical outcome, as well as similar fusion rates following a 12-month period. This is in despite of a delayed consolidation process.     

Which Radiographic Parameters Are Linked to Failure of a Dynamic Spinal Implant?

Background  

Knowledge about factors leading to failure of posterior dynamic stabilization implants is essential to design future implants and establish surgical indications. Therefore, we analyzed an implant for single-level or hybrid configuration (adjacent to spondylodesis), which was recalled due to high failure rates.     

Correction to: Can artificial intelligence support or even replace physicians in measuring sagittal balance? A validation study on preoperative and postoperative full spine images of 170 patients

European Spine Journal -     

Inter- and intraobserver variability in the postoperative evaluation of transpedicular stabilization: computed tomography versus magnetic resonance imaging

Background contextComputed tomography (CT) represents the state of the art for the postoperative verification of the implant position after transpedicular stabilizations. Magnetic resonance imaging (MRI) has not challenged the CT, yet, because of susceptibility artifacts but would be favorable as a diagnostic tool for its excellent soft-tissue qualities.PurposeA study that analyzed if an artifact-reduced MRI could overcome this problem and provide sufficient data for the postoperative assessment was conducted.Study designThe study design was a radiologic comparison of CT and MRI techniques evaluating pedicle screw placement after spinal fusion.Patient sampleFifty consecutive patients were given an MRI and a CT after a transpedicular stabilization surgery. Thirty-eight patients suffered from degenerative spinal disorders; three surgeries had become necessary because of spondylodiscitis, eight patients suffered from metastatic vertebrae destruction, and one patient experienced a fracture.Outcome measuresAny contact of a malpositioned pedicle screw with the dura and/or radicular structures was identified as an implant-associated complication and was compared with postoperative clinical patient findings.MethodsIn total, 338 pedicular screws were analyzed in regard to their intrapedicular position. The double-blind evaluation of MRI and CT data was carried out by two radiologists and two spine surgeons. Accuracy of the CT analysis was calculated based on the interobserver agreement of 100%. Magnetic resonance imaging accuracy was calculated.ResultsThe interobserver accuracy of the CT data amounted to a median of 89.8% and in the MRI data of 86.7%. Intraobserver comparisons showed a significant difference between CT and magnetic resonance evaluations in one observer (κ=0.293). In all other observers, the results were concordant with kappa values from κ=0.328 to κ=0.702. There was a high degree of agreement regarding the diagnosis of malpositioned pedicle screw and corresponding clinical symptoms between both techniques.ConclusionsThe presented data show that artifact-reduced MRI is equivalent to CT imaging in the postoperative evaluation of titanium spinal rod-screw systems. We therefore conclude that MRI should be considered as an alternative tool for the golden standard CT for postoperative imaging controls for its advantages in soft-tissue analysis.