Comparison of revision strategies for failed C2-posterior cervical pedicle screws: a biomechanical study

Study purpose

With increasing usage within challenging biomechanical constructs, failures of C2 posterior cervical pedicle screws (C2-pCPSs) will occur. The purpose of the study was therefore to investigate the biomechanical characteristics of two revision techniques after the failure of C2-pCPSs.

Materials and methods

Twelve human C2 vertebrae were tested in vitro in a biomechanical study to compare two strategies for revision screws after failure of C2-pCPSs. C2 pedicles were instrumented using unicortical 3.5-mm CPS bilaterally (Synapse/Synthes, Switzerland). Insertion accuracy was verified by fluoroscopy. C2 vertebrae were potted and fixed in an electromechanical testing machine with the screw axis coaxial to the pullout direction. Pullout testing was conducted with load and displacement data taken continuously. The peak load to failure was measured in newtons (N) and is reported as the pullout resistance (POR). After pullout, two revision strategies were tested in each vertebra. In Group-1, revision was performed with 4.0-mm C2-pCPSs. In Group-2, revision was performed with C2-pedicle bone-plastic combined with the use of a 4-mm C2-pCPSs. For the statistical analysis, the POR between screws was compared using absolute values (N) and the POR of the revision techniques normalized to that of the primary procedures (%).

Results

The POR of primary 3.5-mm CPSs was 1,140.5 ± 539.6 N for Group-1 and 1,007.7 ± 362.5 N for Group-2; the difference was not significant. In the revision setting, the POR in Group-1 was 705.8 ± 449.1 N, representing a reduction of 38.1 ± 32.9 % compared with that of primary screw fixation. For Group-2, the POR was 875.3 ± 367.9 N, representing a reduction of 13.1 ± 23.4 %. A statistical analysis showed a significantly higher POR for Group-2 compared with Group-1 (p = 0.02). Although the statistics showed a significantly reduced POR for both revision strategies compared with primary fixation (p < 0.001/p = 0.001), the loss of POR (in %) in Group-1 was significantly higher compared with the loss in Group-2 (p = 0.04).

Conclusions

Using a larger-diameter screw combined with the application of a pedicle bone-plastic, the POR can be significantly increased compared with the use of only an increased screw diameter.     

High sensitive C-reactive protein-Effective tool in determining postoperative recovery in lumbar disc disease

Background:

It is common in medical practice to see patients having persistent pain and radiculopathy even after undergoing discectomy surgery. Inflammatory cytokines, such as interleukins are produced at the site of disc herniation and are now considered responsible for the pain perceived by the patient. This study has used high sensitive C-reactive protein (HSCRP) assay for predicting inflammation around the nerve roots on very same principle, which has used HSCRP for predicting coronary artery diseases in current clinical practice. Thus, purpose of this study is to test whether HSCRP can stand as an objective tool to predict postoperative recovery in patients undergoing lumbar discectomy. That is, to study association between preoperative HSCRP blood level and postoperative recovery with the help of modified Oswestry Back Disability Score.

Materials and Methods:

A study group consisting of 50 cases of established lumbar disc disease and control group of 50 normal subjects, matched with the study group. Both the study and control groups were subjected to detailed evaluation with the help of modified Oswestry Low Back Pain Scale both pre and postoperatively at 3 months, 6 months and 1-year. The preoperative blood samples were analyzed to assess the HSCRP concentration. All the cases underwent surgery over a period of 1-year by the same surgeon.

Results:

The level of HSCRP in the study group was between 0.050– and 0.710 mg/dL and in the control group, 0.005-0.020 mg/dL. There was highly significant positive correlation between preoperative HSCRP level and postoperative score at P < 0.005. Cases with HSCRP level in the range of 0.1820 ± 0.079 mg/dL, showed better recovery (score improved > 10 points), while those with HSCRP level in the range of 0.470 ± 0.163 mg/dL, showed poor recovery (score improved < 10 points).

Conclusion:

HSCRP will serve as a good supplementary prognostic marker for operative decision making in borderline and troublesome cases of lumbar disc disease.     

Gynaecomastia correction: A review of our experience

Introduction:

Gynaecomastia is a common problem in the male population with a reported prevalence of up to 36%. Various treatment techniques have been described but none have gained universal acceptance. We reviewed all gynaecomastia patients operated on by one consultant over a 7-year period to assess the morbidity and complication rates associated with the procedure.

Materials and Methods:

Clinical notes and outpatient records of all patients who underwent gynaecomastia correction at University Hospital North Staffordshire between 01/10/2001 to 01/10/2009 were retrospectively reviewed. A modified version of the Breast Evaluation Questionnaire was used to assess patients satisfaction with the procedure.

Results:

Twenty-nine patients and a total of 53 breasts were operated on during the study period. Patients underwent either liposuction alone (6 breasts - 11.3%), excision alone (37 breasts - 69.8%) or both excision and liposuction (10 breasts - 18.9%). Twelve operated breasts (22.6%) experienced some form of complication. Minor complications included seroma (2 patients), superficial wound dehiscence (2 patients) and minor bleeding not requiring theatre (3 patients). Two patients developed haematomas requiring evacuation in theatre. No cases of wound infection, major wound dehiscence or revision surgery were encountered. Twenty-six patients (89.7%) returned the patient satisfaction questionnaire. Patients scored an average 4.12 with regards comfort of their chest in different settings, 3.98 with regards chest appearance in different settings, and 4.22 with regards satisfaction levels for themselves and their partner/family. Overall complication rate was 22.6%. Grade III patients experienced the highest complication rate (35.7%), followed by grade II (22.7%) and grade I (17.6%). Overall complication rates among the excision only group was the highest (29.8%) followed by the liposuction only group (16.7%) and the liposuction and excision group (10.0%). There were high satisfaction rates amongst both patients and surgeon. Eleven patients (37.9%) had their outcome classified as ‘excellent’ by the operating surgeon, 16 patients (55.2%) as ‘good’, 1 (3.4%) as ‘satisfactory’ and 1(3.4%) as ‘poor’.

Conclusion:

Gynaecomastia is a complex condition which poses a significant challenge to the plastic surgeon. Despite the possible complications our case series demonstrates that outcomes of operative correction can be favourable and yield high levels of satisfaction from both patient and surgeon.KEY WORDS: Plastic Surgery, University Hospital North Staffordshire, Correction, gynaecomastia, surgery     

An optimal control model for cloud seeding in a deterministic and stochastic environment

To promote artificial rain in India and other such developing countries, in this article, we have proposed and analyzed a nonlinear mathematical model for cloud seeding by considering that aerosols are introduced proportional to the density of water vapors present in the atmosphere. The model is analyzed using Lyapunov's stability theory of differential equations. To reduce the cost of cloud seeding, an optimal control strategy is designed by incorporating four control parameters. We have shown the existence and uniqueness of solution of this optimal control problem, using Pontryagins Maximum Principle. To minimize the cost in making artificial rain, the optimal control problem provides the strategy for the rate of introduction of aerosols in the atmosphere. To capture the effects of environmental noise on control strategies, the model in deterministic framework is converted into stochastic framework. In this regard, the Hamilton-Jacobi-Bellman equation for stochastic control cost function has been formed. The stochastic analysis implies that the control strategy is effective in reducing the cost and increasing rainfall.     

Genetic diversity and distribution of tomato-infecting begomoviruses in Iran

The incidence and severity of tomato leaf curl disease (TLCD) is increasing worldwide. Here we assess the diversity and distribution within tomato producing areas of Iran of begomoviruses that cause this disease. Tomato with typical TLCD symptoms and asymptomatic weeds were collected in 2005 and 2006 and tested for the presence of begomovirus DNA using polymerase chain reaction (PCR). Analysis of cloned and sequenced PCR products revealed that both mono- and bipartite begomoviruses are associated with TLCD in Iran. Furthermore, our results confirmed the symptomless infection with mono- and bipartite begomoviruses of two weed species, Chrozophora hierosolymitana Spreng (Euphobiaceae) and Herniaria sp. (Caryophyllaceae). Eighteen Iranian begomovirus isolates were classified into two major groups and two or three subgroups according to the 5′-proximal 200 nucleotides of the coat protein (CP) gene or the N-terminal 600 nucleotides of the Rep gene. Whereas most of the monopartite isolates showed closest similarity to tomato yellow leaf curl virus-Gezira (TYLCV-Ge), the three bipartite isolates were most similar to Tomato leaf curl New Delhi virus (ToLCNDV). Mixed mono- and a bipartite begomovirus infections were detected in both tomato and C. hierosolymitana. Our results indicate that the tomato producing areas in central, southern, and southeastern Iran are threatened by begomoviruses originating from both the Mediterranean basin and the Indian subcontinent.     

Hurdles in stroke thrombolysis: Experience from 100 consecutive ischemic stroke patients

Background:

Acute management of ischemic stroke involves thrombolysis within 4.5 h. For a successful outcome, early recognition of stroke, transportation to the hospital emergency department immediately after stroke, timely imaging, proper diagnosis, and thrombolysis within 4.5 h is of paramount importance.

Aim:

To analyze the obstacles for thrombolysis in acute stroke patients.

Materials and Methods:

The study was conducted in a tertiary care center in South India. A total of hundred consecutive patients of acute ischemic stroke who were not thrombolysed, but otherwise fulfilled the criteria for thrombolysis were evaluated prospectively for various factors that prevented thrombolysis. The constraints to thrombolysis were categorized into: i) Failure of patient to recognize stroke symptoms, ii) patient''s awareness of thrombolysis as a treatment modality for stroke, iii) failure of patient''s relative to recognize stroke, iv) failure of primary care physician to recognize stroke, v) transport delays, vi) lack of neuroimaging and thrombolysis facility, and vii) nonaffordability.

Results:

The biggest hurdle for early hospital presentation is failure of patients to recognize stroke (73%), followed by lack of neuroimaging facility (58%), nonaffordability (56%), failure of patient''s relative to recognize stroke (38%), failure of the primary care physician to recognize stroke (21%), and transport problems (13%). Awareness of thrombolysis as a treatment modality for stroke was seen only in 2%.

Conclusion:

Considering the urgency of therapeutic measures in acute stroke, there is necessity and room for improvement to overcome various hurdles that prevent thrombolysis.     

Chronic brainstem ischemia in subclavian steal syndrome

Subclavian steal syndrome is usually an incidental finding and rarely causes vertebrobasilar ischemia. We present a 58-year-old man who, over six months, experienced progressive slowing in both talking and walking. Cervical duplex sonography revealed severe stenosis of the right subclavian artery; fixed retrograde flow was noted in the right vertebral artery on transcranial Doppler. The hyperemia–ischemia cuff test resulted in considerable reduction in flow velocities in both posterior cerebral arteries. We attributed his slowness to chronic vertebrobasilar ischemia and surgical revascularization was performed. His symptoms subsided immediately after surgery. The improved perfusion in the posterior circulation was demonstrated on technetium-99 hexamethylpropyleneamine oxime single photon-emission CT. Early diagnosis and prompt treatment resulted in an improved quality of life.