Is a helical shaped implant a superior alternative to the Dynamic Hip Screw for unstable femoral neck fractures? A biomechanical investigation

Background

The Dynamic Hip Screw is well established for the treatment of femoral neck fractures. However, cut-out occurs in 1–6% of all cases. This study compared the biomechanical performance of a helical shaped implant (DHS-Blade) to the Dynamic Hip Screw in an unstable femoral neck fracture model.

Methods

Ten pairs of human cadaveric femora were either instrumented with a DHS-Blade or a Dynamic Hip Screw. Osteotomies were created using a custom-made saw-guide. Cyclic loading was performed by introducing in vivo measured load-trajectories to the femoral head. Starting at 1500 N, the load was stepwise increased until failure of the construct. Radiographs were taken in 5000 cycles increments to identify onset of femoral head migration with respect to the implant. A survival analysis was performed on the cycles to onset of migration. A paired t-test was carried out on the displacements of the femoral head relative to the shaft as determined by optical motion tracking.

Findings

One hundred percent migrations occurred for the Dynamic Hip Screw compared to 50% for the DHS-Blade. The survival probability in terms of implant anchorage was found higher for the blade (P = 0.023). However, significant higher deformation of the repair construct was observed for the DHS-Blade (P = 0.004).

Interpretation

The study showed superior implant anchorage of the DHS-Blade compared to the DHS, which might reduce the cut-out risk. Nevertheless, the blade allowed higher deformation of the femur mainly resulting in shortening of the neck, which might be due to a systematic loss of fracture reduction.     

Does pedicle screw fixation of the subaxial cervical spine provide adequate stabilization in a multilevel vertebral body fracture model? An in vitro biomechanical study

BackgroundCervical vertebral body fractures generally are treated through an anterior-posterior approach. Cervical pedicle screws offer an alternative to circumferential fixation. This biomechanical study quantifies whether cervical pedicle screws alone can restore the stability of a three-column vertebral body fracture, making standard 360° reconstruction unnecessary.MethodsRange of motion (2.0 Nm) in flexion-extension, lateral bending, and axial rotation was tested on 10 cadaveric specimens (five/group) at C2–T1 with a spine kinematics simulator. Specimens were tested for flexibility of intact when a fatigue protocol with instrumentation was used to evaluate construct longevity. For a C4–6 fracture, spines were instrumented with 360° reconstruction (corpectomy spacer + plate + lateral mass screws) (Group 1) or cervical pedicle screw reconstruction (C3 and C7 only) (Group 2).FindingsResults are expressed as percentage of intact (100%). In Group 1, 360° reconstruction resulted in decreased motion during flexion-extension, lateral bending, and axial rotation, to 21.5%, 14.1%, and 48.6%, respectively, following 18,000 cycles of flexion-extension testing. In Group 2, cervical pedicle screw reconstruction led to reduced motion after cyclic flexion-extension testing, to 38.4%, 12.3%, and 51.1% during flexion-extension, lateral bending, and axial rotation, respectively.InterpretationThe 360° stabilization procedure provided the greatest initial stability. Cervical pedicle screw reconstruction resulted in less change in motion following cyclic loading with less variation from specimen to specimen, possibly caused by loosening of the shorter lateral mass screws. Cervical pedicle screw stabilization may be a viable alternative to 360° reconstruction for restoring multilevel vertebral body fracture.     

Mechanical comparison of biodegradable femoral fixation devices for hamstring tendon graft – A biomechanical study in a porcine model

Background

Initial fixation strength is critical for the early post-operative rehabilitation of patients with anterior cruciate ligament reconstructions. However, even the best femoral fixation devices remain controversial. We compared the biomechanical characteristics of tendon grafts fixed by different biodegradable femoral fixation devices following anterior cruciate ligament reconstruction.

Methods

The Bio-TransFix, Rigidfix, Bioscrew with EndoPearl augmentation and Bioscrew devices were used to fix porcine flexor digitorum profundus tendon grafts in 32 porcine femora. Displacement of each tendon graft was evaluated after cyclic loading testing. Stiffness, ultimate failure load and failure mode of these fixation devices were measured with load-to-failure testing.

Findings

The displacement of the femur–graft–cement complex in response to cyclic loading was lower (P < 0.05) for the Bio-TransFix than the Rigidfix, Bioscrew with EndoPearl augmentation, and Bioscrew groups. The fixation stiffness values of the Rigidfix and the Bioscrew were significantly greater (P < 0.05) than that of the Bio-TransFix. The ultimate failure load was significantly greater for the Bio-TransFix and the Rigidfix than the Bioscrew with EndoPearl augmentation or the Bioscrew (P < 0.05).

Interpretation

The Bio-TransFix provided the least graft displacement under cyclic loading. However, this device gave less stability. The Rigidfix device provided better stability and stiffness of the tendon graft among those fixation devices that showed no significant differences in graft displacement under cyclic loading. However, no single fixation device provided less displacement along with a larger failure load and stiffness in this study.     

Contradictory working length effects in locked plating of the distal and middle femoral fractures―a biomechanical study

BackgroundWorking length have been reported to affect the plate stress and fixation stiffness. However, the results of previous studies have been controversial. The present study was to determine working length effects on different locations of femoral bone gap.MethodsFive composite femurs with wide bone gaps at five levels (G1, 2, 3, 5, and 7), were fixed with locking plates. G1-3, G5 and G7 represented gaps at distal femur, distal-middle femur and middle femur respectively. Strain gauges were applied near the screw holes. The plate-bone constructs were loaded through a hemicylinder on the femoral head with total constraints at the distal femur. The micro-strains, axial stiffness and interfragmentary motions were recorded. Then the locking screws were removed one by one and the tests were re-run. The working length effects were compared and correlated.FindingsIn distal femurs (G1-3), long working length was negatively correlated with the highest strains (r = −0.97, −0.95 and − 0.95, p < 0.01) and axial stiffness (r = −1, −0.96 and −0.99, p < 0.01). In distal-middle femurs (G5), as the working length increased, the highest strain decreased initially and then increased (r = 0.81, p = 0.026) and the axial stiffness decreased (r = −0.98, p < 0.01). In middle femurs (G7), the highest strain and gap motions were much higher than that in the other groups and not significantly correlated with the working length change.InterpretationLong working length could reduce the highest plate strain in distal femurs, but had no significant effects in middle femurs. The working length effects were markedly affected by the loading and boundary conditions.     

How does a novel knitted titanium nucleus prosthesis change the kinematics of a cervical spine segment? A biomechanical cadaveric study

BackgroundTotal disc replacement is a possible treatment alternative for patients with degenerative disc disease, especially in the cervical spine. The aim is to restore the physiological flexibility and biomechanical behavior. A new approach based on these requirements is the novel nucleus prosthesis made of knitted titanium wires.MethodsThe biomechanical functionalities of eight human cervical (C4-C7) spine segments were investigated. The range of motion was quantified using an ultra-sound based motion analysis system. Moreover, X-rays in full flexion and extension of the segment were taken to define the center of rotation before and after implantation of the nucleus prosthesis as well as during and after complex cyclic loading.FindingsThe mean range of motion of the index segment (C5/6) in flexion/extension showed a significant reduction of range of motion from 9.7° (SD 4.33) to 6.0° (SD 3.97) after implantation (P = 0.037). Lateral bending and axial rotation were not significantly reduced after implanting and during cyclic loading in our testing. During cyclic loading the mean range of motion for flexion/extension increased to 7.2° (SD 3.67). The center of rotation remained physiological in the ap-plane and moved cranially in the cc-plane (−27% to −5% in cc height) during the testing.InterpretationThe biomechanical behavior of the nucleus implant might lower the risk for adjacent joint disorders and restore native function of the index segment. Further in vivo research is needed for other factors, like long-term effects and patient's satisfaction.     

Do facet screws provide the required stability in lumbar fixation? A biomechanical comparison of the Boucher technique and pedicular fixation in primary and circumferential fusions

Background

Transfacet pedicle screws are scarcely used in primary posterior fixation, and have limited use unilaterally or with existing anterior instrumentation. Nevertheless, the incomplete literature suggests equivalent or better performance of ipsilateral, bilateral, facet screws compared to bilateral pedicle screws.

Methods

Two groups of seven human cadaver spines (L3-S1) were tested under pure moments of 6 Nm. Each specimen was tested in a primary and circumferential fixation (Spacer, Spacer + Plate) environment. Both transfacet and bilateral pedicle screws were used as posterior fixation, in separate groups. Motion was obtained at L4-L5 for single-level constructs in flexion-extension, lateral bending and axial rotation modes.

Findings

In primary fixation, both transfacet and bilateral pedicle screws reduced motion below intact levels. Statistically, the level of circumferential fixation (anterior, posterior, or both) proved to be more influential than the type of posterior fixation. Incorporating a spacer and plate with pedicle screws provided a greater relative gain in stability than with facet screws. The interpretation is explained through a model describing the location of fixation with respect to the center-of-rotation of the vertebral bodies. In lateral bending and axial rotation, bilateral pedicle screw constructs were stiffer than transfacet pedicle screw constructs as a trend.

Interpretation

Transfacet pedicle screws provided similar fixation to bilateral pedicle screws in primary and circumferential fixations during flexion-extension. In the other modes, transfacet screw rigidity is, on average, less than bilateral pedicle screws when used alone, but with the addition of other anterior instrumentation the differences are minimized. Therefore, facet screws are warranted based on the surgical effect desired, and in the presence of additional anterior fixation.     

Effectiveness of surgical rib fixation on prolonged mechanical ventilation in patients with traumatic rib fractures: A propensity score–matched analysis

PurposeWe investigated whether surgical rib fixation improved outcomes in patients with traumatic rib fractures.Materials and MethodsThis was a retrospective study using a Japanese administrative claim and discharge database. We included patients with traumatic rib fractures admitted to hospitals where surgical rib fixation was available from July 1 2010, to March 31, 2013. We detected patients who underwent surgical rib fixation within 10 days of hospital admission (surgical group) and those who did not (control group). The main outcome was prolonged mechanical ventilation, defined as that performed for 5 or more days, or death within 28 days. One-to-four propensity score matching was performed between the 2 groups with adjustment for possible confounders.ResultsAmong 4577 eligible patients, 90 (2.0%) underwent the surgical rib fixation. After the matching, we obtained 84 and 336 patients in the surgical and control groups, respectively. Logistic regression analyses showed that the surgical group was significantly less likely to receive prolonged mechanical ventilation or die within 28 days than the control group (22.6% vs 33.3%; odds ratio, 0.59; 95% confidence interval, 0.36-0.96; P = .034).ConclusionsSurgical rib fixation within 10 days of hospital admission may improve outcomes in patients with traumatic rib fractures.     

Are there benefits of a 2D gait analysis in the evaluation of the subtalar extra-articular screw arthroereisis? Short-term investigation in children

BackgroundA juvenile flexible flatfoot is a common abnormality during growth. For children with a pathological manifestation, subtalar extra-articular screw arthroereisis is a popular operative technique. Although this minimally invasive operation technique has been performed for >45 years, complications still occasionally occur. For this reason, we created this pilot study to investigate whether a two-dimensional (2D) gait analysis is able to identify functional movement deficits after surgery.MethodsFourteen children (27 ft) with a mean age of 12.38 years (SD, 1.40 years) were analyzed. Biomechanics were examined before and 4 weeks after surgery using a 2D gait analysis. For this purpose, the patients were filmed on a treadmill. In focus were static and dynamic recordings of the heel angle, rearfoot angle, and the leg axis angle. In addition, the step length and self-selected speed were measured.FindingsAfter surgery rearfoot angle showed significant reduction (p < 0.001) from 12.49° to 3.63° under static conditions and from 12.65° to 4.58° under dynamic conditions. Heel angle responded similar (p < 0.001). There were no significant differences in self-selected speed or step length. Undoubtedly, gait analysis was able to identify intraindividual deficits, leading to a closer monitoring of five patients and an adjustment of the screw in one foot.InterpretationBy means of the 2D gait analysis, we were able to show functional improvement after subtalar extra-articular screw arthroereisis. Nonetheless, we identified a few children who still had functional abnormalities. Certainly, it is unclear whether this additional examination is able to reveal all complications that would have occurred later.     

A case in point? A parasuicide patient's recollections of being nursed: a discourse analysis

This paper highlights the recollections of being nursed from the perspective of a patient (Gabby) admitted to a general medical ward after attempting suicide. A discourse analysis was used to discuss the way in which Gabby was nursed, enabling identification of the social structure which supports the nurse-patient relationship. This research evolved with the realisation that the point of view of parasuicide patients was primarily absent within nursing literature. Inattention within the literature was later replicated by Gabby's expressions of inadequate interaction between nurses and parasuicide patients.     

Does religious psychotherapy improve anxiety and depression in religious adults? A review of randomized controlled studies

Nurses in mental health settings are expected to provide insightful, wholistic, and effective care. Many patients in mental health settings have concerns or needs related to spiritual or religious dimensions. Unfortunately, many of these concerns are not addressed. Religious psychotherapy (RPT) is an approach to therapy that attempts to recognize and utilize the religious beliefs of clients in treatment for the purposes of reducing mental health difficulties. The purpose of this paper is to review the current randomized and controlled research (RCT) on the utilization of RPT in adult populations with anxiety and depressive disorders and to make recommendations for practice and future research. A search of the literature yielded four studies. A critical review of the studies yielded the following findings: (1) The findings across studies consistently demonstrate that RPT is as effective as standard treatment; (2) the results in each study were statistically significant and appeared to qualify as being clinically significant; and 3) the studies reviewed, although varying in quality, were true experiments marked by intervention, randomization, and control groups or comparison with standard treatment groups. There is warrant for greater consideration of the religious beliefs of depressed and anxious clients in outpatient settings. Nurses should be aware of the potential for the reduction of distressing symptomology through the consideration of clients' belief systems as they effect clients' perceptions of their own mental health.     

Does nanoscale porous titanium coating increase lumbar spinal stiffness of an interbody fusion cage? An in vivo biomechanical analysis in an ovine model

BackgroundQuantitative objective measures to determine fusion achievement further enable the comparison of new technologies, such as interbody cage surface enhancement. Our aims were to compare in vivo biomechanical responses of ovine L4/5 lumbar motion segments with two cages: 1) Polyetheretherketone or 2) Polyetheretherketone with a nanosurfaced titanium porous scaffold from Nanovis, Inc.MethodsFourteen Merino sheep randomly received either 1) standard Polyetheretherketone cage or 2) Nanocoated Polyetheretherketone cage at L4/L5 with autologous bone graft. At baseline and one-year follow-up, dynamic spinal stiffness was quantified in vivo using a validated mechanical assessment at 2 Hz, 6 Hz, and 12 Hz. The dorsoventral secant stiffness (k_y = force/displacement, N/mm) and L4-L5 accelerations were determined at each frequency. A repeated measures analysis of variance with Bonferonni correction was used to evaluate within and between group differences among the biomechanical variables.FindingsBoth implants increased spinal stiffness at 2 Hz (21 and 39%, respectively, p < .005), and at 6 Hz (12 and 27%, p < .0001). Significantly greater spinal stiffness was observed with Nanocoated Polyetheretherketone at one-year for both frequencies (p < .05). No significant differences were observed at 12 Hz within or between groups. L4-L5 dorsoventral accelerations were significantly decreased one year following cage placement only with Nanocoated Polyetheretherketone (p < .05) and greater reductions in acceleration were observed with Nanocoated Polyetheretherketone compared to standard Polyetheretherketone (p < .05).InterpretationBoth cages increased spinal stiffness, yet, nanosurfaced cages resulted in greater spinal stiffness changes and decreases in L4-L5 accelerations. These findings may assist in clinical decision making and post-operative recovery strategies.     

Does gender bias in cardiac stress testing still exist? A videographic analysis nested in a randomized controlled trial

Objectives

Despite a high prevalence of coronary heart disease in both genders, studies show a gender disparity in evaluation whereby women are less likely than men to undergo timely or comprehensive cardiac investigation. Using videographic analysis, we sought to quantify gender differences in provider recommendations and patient evaluations.

Does the presence of an emergency physician improve access based quality indicators in a rural emergency department?

Objective: To assess the effect that the presence of an emergency physician in the ED has on the access indicators of the Australian Council on Healthcare Standards. Methods: A retrospective study was carried out in a 265 bed regional referral hospital in Victoria. The performance of the ED over a 6 month period, during which time there was incomplete emergency physician coverage, was monitored using The Australian Council on Healthcare Standards (ACHS) access indicators as the benchmark. These indicators are waiting time by triage category, and access block. Results: A total of 11 999 patient presentations were eligible for inclusion in the study. Emergency physicians were present for 76.5% of these presentations. All the indicators show a trend towards improvement when an emergency physician was present. However, the only indicator that shows a significant improvement is waiting time by triage category, and this is due mainly to an improvement within triage category 4. Conclusion: There is some evidence that the presence of an emergency physician improves performance within this group of access based indicators within a rural ED, however, the effect seen here is small. More studies are needed on this topic and also on the development of quality indicators for rural ED.     

A checklist manifesto: Can a checklist of common diagnoses improve accuracy in ECG interpretation?

ObjectiveTo determine whether a checklist of possible etiologies for syncope provided alongside ECGs helps Emergency Medicine (EM) residents identify ECG patterns more accurately than with ECGs alone.MethodsWe developed a test of ten ECGs with syncope-related pathology from ECG Wave-Maven. We reviewed the literature and used expert consensus to develop a checklist of syncope-related pathologies commonly seen and diagnosed on ECGs. We randomized residents from three New York EM residency programs to interpret ECGs with or without a checklist embedded into the test.ResultsWe randomized 165 residents and received completed tests from 100 (60%). Of those who responded, 39% were interns, 23% PGY2s, and 38% were PGY3s or PGY4s. We found no significant difference in overall test scores between those who read ECGs with a checklist and those who read ECGs alone. In post-hoc analysis, residents given a checklist of syncoperelated etiologies were significantly more likely to recognize Brugada (96% vs. 78%, p = 0.007), long QT (86% vs. 68%, p = 0.03) and heart block (100% vs 78%, p = 0.003) as compared to those without a checklist. Those with a checklist were more likely to overread normal ECGs (72% vs 35%, p = 0.0001) compared to those without a checklist, finding pathology where there was none.ConclusionUsing a checklist with common syncope-related pathology when interpreting an ECG for a patient with clinical scenario of syncope may improve residents' ability to recognize some clinically important pathologies; however it could lead to increased interpretation and suspicion of pathology that is not present.