Operative time, length of stay and reoperation rates for orthognathic surgery.

Orthognathic surgery improves quality of life in terms of oral function and facial aesthetics. Our aim was to establish and compare operative time and length of inpatient stay for orthognathic procedures, and to assess the reoperation rate. Departmental electronic data base was used to identify all patients undergoing orthognathic surgery in a single unit between the 01/01/2016 and the 01/08/2018. 251 patients were identified who underwent 409 orthognathic surgery procedures. The mean operating time for a bimaxillary osteotomy (n=107) was 139.3 min. For single jaw procedures, the mean operating time for a Le Fort I osteotomy (n= 42) was 82.2 min and for a bilateral sagittal split osteotomy (BSSO) (n= 102) was 80.3min. Bimaxillary osteotomy combined with genioplasty (n=17) this increased the operating time on average by 31 min. and of a BSSO combined with a genioplasty (n=14) by 27 mins. The mean postoperative hospital stay was 1.2 ± 0.2 days. 96.4% patients spent only one postoperative night in hospital. 6/251 (2.4%) patients required re-operation. In regression analysis, age was the only significant factor in increasing length of stay (p<0.008), 95% CI 0.03-0.2). Our review shows short operating times and postoperative inpatient stays in a large cohort of patients undergoing orthognathic surgery. This is combined with a low reoperation rate. This may point to a patient benefit from high volume orthognathic centres.

Process mapping and Lean principles applied to orthognathic surgery.

Process mapping in industry is a well-established tool to improve efficiency. It is defined as a quality improvement technique that breaks down a process, or task, into its individual components, or steps, then analyses it. Lean principles are used to reduce waste and produce consistently good outcomes. Improving the operative efficiency of orthognathic surgery has many benefits. There is increasing demand for this complex surgery, and patients have appropriately high expectations with relation to their outcome. There are also increasing pressures for hospitals to reduce costs. In a recent paper by our group (Bowe et al, in press), we have published operating times for orthognathic procedures that are significantly shorter than in previously available series, with an average time for a bimaxillary osteotomy of 2 hours and 19 mins. Through observation of the senior authors' uniform technique, refined from experience of over 2,000 cases, a bimaxillary osteotomy was broken down into individual steps, all arranged in a process-mapped template with which to increase efficiency and results. We show here the multiple small operative efficiencies we have developed, and the Lean surgical principles which we use. This has enabled us to reduce the operative time of these common procedures, without compromising outcomes. This study presents an approach to process map bimaxillary orthognathic operations and shows how the application of Lean principles improves operative efficiency, and produces consistent results.

Nanoscale magnetic field detection using a spin torque oscillator.

Magnetic field detection with extremely high spatial resolution is crucial to applications in magnetic storage, biosensing, and magnetic imaging. Here, we present the concept of using a spin torque oscillator (STO) to detect magnetic fields by measuring the frequency of the oscillator. This sensor's performance relies predominantly on STO properties such as spectral linewidth and frequency dispersion with magnetic field, rather than signal amplitude as in conventional magnetoresistive sensors, and is shown in measured devices to achieve large signal to noise ratios. Using macrospin simulations, we describe oscillator designs for maximizing performance, making spin torque oscillators an attractive candidate to replace more commonly used sensors in nanoscale magnetic field sensing and future magnetic recording applications.

Near-surface nanoscale InAs Hall cross sensitivity to localized magnetic and electric fields.

We have measured the room temperature response of nanoscale semiconductor Hall crosses to local applied magnetic fields under various local electric gate conditions using scanning probe microscopy. Near-surface quantum wells of AlSb/InAs/AlSb, located just 5 nm from the heterostructure surface, allow very high sensitivity to localized electric and magnetic fields applied near the device surfaces. The Hall crosses have critical dimensions of 400 and 100 nm, while the mean free path of the carriers is about 160 nm; hence the devices nominally span the transition from diffusive to quasi-ballistic transport. With certain small gate voltages (V(g)) the devices of both sizes are strongly responsive to the local magnetic field at the center of the cross, and the results are well described using finite element modeling. At high V(g), the response to local magnetic fields is greatly distorted by strong electric fields applied near the cross corners. However we observe no change in behavior with the size of the device.

Management of regional metastatic disease in cutaneous malignancy of the head and neck. 3. Merkel cell carcinoma.

This is the third of three articles that give an overview of the current evidence for management of the neck and parotid in patients with cutaneous cancers of the head and neck. In this paper we discuss Merkel cell carcinoma (MCC) and review the latest evidence for management of the regional nodes.

Sentinel lymph node biopsy for melanoma of the head and neck: a multicentre study to examine safety, efficacy, and prognostic value.

Sentinel lymph node biopsy (SLNB) is an accurate staging procedure for malignant melanoma but its use in patients with melanoma of the head and neck has been questioned in the past because of a perceived record of poor safety and accuracy. Technical improvements have sought to redress this. Vital structures and variable lymphatic pathways can make its use in the head and neck challenging. In our study we have examined the data and the experiences of clinicians from University Hospital Southampton and the Royal Surrey County Hospital. We retrospectively analysed the data and case notes of 143 patients who had SLNB to establish its safety, efficacy, and prognostic value. The detection rate of at least one sentinel lymph node was 100%. Nodes positive for metastatic melanoma were found in 20% of patients. Of them, 76% went on to have completion lymphadenectomy. Multivariate Cox regression analysis suggested that positive SLNB was a strong predictor of reduced overall survival for all Breslow-thickness melanomas (HR=3.9, p=0.019) and intermediate melanomas (HR=6.3, p=0.007). It predicted reduced recurrence-free survival for all melanomas (HR=7.4, p<0.001) and was a strong predictor for those of intermediate thickness (HR=8.3, p<0.001). The false negative rate was 9.4% and false omission rate 2.6%. Temporary and permanent morbidity rates were 2.1% and 0%, respectively. SLNB for melanoma in the head and neck is a safe, accurate staging procedure that offers prognostically useful information. The upstaging of disease allows access to trial-based targeted treatments.

Silicone wafers at the Royal Surrey County Hospital: 3-year review.

Accurate orthognathic wafers manufactured in the laboratory are essential for the transfer of preoperative prescribed movements to theatre, and most are made of poly(methyl methacrylate) (PMMA). At the Royal Surrey County Hospital we used 416 silicone wafers in 292 patients from January 2011 to December 2013. We report how a revised design has improved self-retention and intraoperative visualisation.

Effects of limb-length discrepancy on gait economy and lower-extremity muscle activity in older adults.

BACKGROUND: The amount of limb-length discrepancy necessary to adversely affect gait parameters in older adults is unknown, with information being largely anecdotal. This investigation was conducted to determine the effects of limb-length discrepancy on gait economy and lower-extremity muscle activity in older adults. METHODS: Forty-four men and women ranging in age from fifty-five to eighty-six years with no evidence of limb-length discrepancy of >1 cm participated in the study. Subjects walked on a treadmill at a self-selected normal walking pace with artificial limb-length discrepancies of 0, 2, 3, and 4 cm applied in a randomly selected order. Indirect calorimetry was used to measure oxygen consumption and minute ventilation. Electromyography was used to measure muscle activity of the right and left quadriceps femoris, plantar flexors, gluteus maximus, and gluteus medius. Heart rate, the rating of perceived exertion, and frequency of gait compensation patterns were also measured. RESULTS: There was a significant increase in oxygen consumption and the rating of perceived exertion with 2, 3, and 4-cm artificial limb-length discrepancies; a significant increase in heart rate, minute ventilation, and quadriceps activity in the longer limb with 3 and 4-cm artificial limb-length discrepancies; and a significant increase in plantar flexor activity in the shorter limb with a 4-cm artificial limb-length discrepancy compared with the same parameters with no artificial limb-length discrepancy. CONCLUSIONS: Both oxygen consumption and the rating of perceived exertion were greater with a 2-cm artificial limb-length discrepancy than they were with no artificial limb-length discrepancy. There appears to be a breakpoint between 2 and 3 cm of artificial limb-length discrepancy in older adults with regard to the effects on most other physiological parameters. A 3-cm artificial limb-length discrepancy is likely to induce significant quadriceps fatigue in the longer limb. Elderly patients with substantial pulmonary, cardiac, or neuromuscular disease may have difficulty walking with a limb-length discrepancy as small as 2 cm.