Near-zero contact force atomic force microscopy investigations using active electromagnetic cantilevers.

Atomic force microscopy (AFM) belongs to the high resolution and high sensitivity surface imaging technologies. In this method force interactions between the tip and the surface are observed to characterize sample properties. In the so-called contact AFM (C AFM) mode the tip is brought into continuous contact with the sample. Significant progress in the AFM technology can be obtained, when the so-called active cantilever technology is implemented in the surface measurements. The built-in deflection actuator enables very precise excitation of the cantilever. Moreover, as the mass of the beam is very small the static beam displacement can be controlled in the wide frequency range. In the experiments, which we describe in this article, we applied the so called active electromagnetic cantilevers. They integrate a conductive loop which, when immersed in the magnetic field and biased with electric current, acts as an electromagnetic deflection actuator. The induced and precisely estimated Lorentz force, which is a function of bias current, cantilever geometry and magnetic field makes the cantilever deflect. Moreover, the probe stiffness can be calibrated with lower uncertainty as in the case of standard thermomechanical analysis. NZ AFM technology required application of a novel control algorithm, called PredPID, in which the cantilever bending caused by a proportional-integral-derivative (PID) block maintaining the constant load force was predicted.

Randomized feasibility trial of replacing or discarding the nail plate after nail-bed repair in children.

BACKGROUND: Nail-bed injuries are the most common hand injury in children. Surgical dogma is to replace the nail plate after repairing the nail bed. Recent evidence suggests this might increase infection rates and returns to clinic. The aim of this feasibility trial was to inform the design and conduct of a definitive trial comparing replacing or discarding the nail plate after nail-bed repair. METHODS: This study recruited participants from four hand units in the UK between April and July 2015. Participants were children under the age of 16 years with a nail-bed injury requiring surgery. They were randomized to either having the nail plate replaced or discarded after nail-bed repair. The follow-up method was also allocated randomly (postal versus clinic). Information was collected on complications at 2 weeks and 30 days, and on nail-plate appearance at 4 months using the Zook classification. Two possible approaches to follow-up were also piloted and compared. RESULTS: During the recruitment phase, there were 156 potentially eligible children. Sixty were randomized in just over 3 months using remote web-based allocation. By 2 weeks, there were two infections, both in children with replaced nail plates. The nail-replaced group also experienced more complications. There was no evidence of a difference in return rates between postal and clinic follow-up. CONCLUSION: Recruitment was rapid and nail-bed repair appeared to have low complication and infection rates in this pilot trial. The findings have led to revision of the definitive trial protocol, including the mode and timing of follow-up, and modification of the Zook classification.

A systematic review of outcomes following hand reconstruction using flaps from the superficial palmar branch of the radial artery (SUPBRA) system.

BACKGROUND: Flaps based on the superficial branch of the radial artery (SUPBRA) are indicated when homo- or heterodigital flaps are inappropriate, but glabrous or like-for-like reconstruction is required. AIM: To systematically review the outcomes of hand reconstruction using SUPBRA flaps. METHODS: PubMed was searched for English-language articles studying SUPBRA flaps in November 2019. Data collected included flap vascular supply, dimensions, complications, donor site closure, and two-point discrimination. RESULTS: Twenty-six papers were eligible (410 flaps). Flaps were classified as glabrous, nonglabrous or combined. Nonglabrous flaps were either free- (52%) or reverse-flow pedicled (1.7%) wrist flaps. Glabrous flaps were either free palmar (36.3%), reverse-flow pedicled palmar (2%), antegrade-flow pedicled palmar (0.2%) or perforator-based island palmar flaps (3.7%). Combined glabrous/nonglabrous flaps formed 4.1% of flaps. Maximal flap dimensions allowing direct closure were: 3.1 × 6 cm for wrist flaps and <3 × 10 cm for glabrous palmar flaps. Combined flaps can be 10 × 16 cm. Overall, complete and partial flap failure rates were 3.17% and 0.98%, respectively. Most complete failures were due to venous thrombosis. All 220 wrist donor sites were closed directly. Two out of 173 palmar donor sites (≥3.1) could not be primarily closed. Wound complications were rare, but 53.4% of free palmar flaps required debulking. The results of neurorrhaphy were inconsistent. CONCLUSIONS: Flaps based on the SUPBRA are robust, provide like-for-like reconstruction of glabrous skin defects in one-stage, offer versatility due to diverse skin paddle orientation patterns and are in the same operative field as the defect.

St Andrew's COVID-19 surgery safety study: hand trauma.

INTRODUCTION: Adaptation is vital to ensure successful healthcare recovery during the COVID-19 pandemic. Hand trauma represents the most common acute emergency department presentation internationally. This study prospectively evaluates the COVID-19 related patient risk, when undergoing management within one of the largest specialist tertiary referral centres in Europe, which rapidly implemented national COVID-19 safety guidelines. MATERIALS AND METHODS: A prospective cohort study was undertaken in all patients referred to the integrated hand trauma service, during the UK COVID-19 pandemic peak (April-May 2020); all were evaluated for 30-day COVID-19 related death. Random selection was undertaken for patients with hand trauma who either underwent non-operative (control group) or operative (surgery group) management; these groups were prospectively followed-up within a controlled cohort study design and telephoned at 30 days following first intervention (control group) or postoperatively (surgery group). RESULTS: Of 731 referred patients (566 operations), there were no COVID-19 related deaths. Both groups were matched for sex, age, ethnicity, body mass index, comorbidities, smoking, preoperative/first assessment COVID-19 symptoms, pre- and postoperative/first assessment isolation and positive COVID-19 contact (p > 0.050). There were no differences in high service satisfaction (10/10 compared with 10/10; p = 0.067) and treatment outcome (10/10 compared with 10/10; p = 0.961) scores, postoperative/first assessment symptoms (1%, 1/100 compared with 0.8%, 2/250; p = 1.000) or proportion of positive tests (7.1%, 1/14 compared with 2.2%, 2/92; p = 0.349), between the control (n = 100) and surgery (n = 250) groups. CONCLUSION: These data support continued and safe service provision and no increased risk to patients who require surgical management. Such findings are vital for healthcare providers when considering service adaptations to reinstate patient treatment.

Non-cholinergic modulation of antisaccade performance: a modafinil-nicotine comparison.

INTRODUCTION: The antisaccade task provides a powerful tool with which to investigate the cognitive and neural systems underlying goal-directed behaviour, particularly in situations when the correct behavioural response requires the suppression of a prepotent response. Antisaccade errors (failures to suppress reflexive prosaccades towards sudden-onset targets) are increased in patients with damage to the dorsolateral prefrontal cortex, and in patients with schizophrenia. Nicotine has been found to improve antisaccade performance in patients with schizophrenia and healthy controls. This performance enhancing effect may be due to direct effects on the cholinergic system, but there has been no test of this hypothesis. MATERIALS AND METHODS: In a double blind, double dummy, placebo-controlled design, we compared the effect of nicotine and modafinil, a putative indirect noradrenergic agonist, on antisaccade performance in healthy non-smokers. RESULTS AND DISCUSSION: Both compounds reduced latency for correct antisaccades, although neither reduced antisaccade errors. These findings are discussed with reference to the pharmacological route of performance enhancement on the antisaccade task and current models of antisaccade performance.

Management of painful scar-tethered cutaneous nerves of the upper limb.

We report the results of treatment by division and proximal relocation of 44 painful, scar-tethered cutaneous nerves of the upper limb in 22 patients. In all patients, neuropathic pain had developed either following surgery or trauma, but without apparent direct nerve injury. The mean duration of pain symptoms prior to relocation was 17 (range 7-44) months. Adequate treatment involved relocation of 35 nerves at a first operation for each of the 22 patients, with six patients requiring further surgery to relocate 9 nerves. At a minimum follow-up of 6 months, nerve relocation resulted in complete resolution of all forms of pain at the primary site in 21/22 (95%) patients and no pain or hypersensitivity at the final relocation site in 19 of the 22 patients (86%).

Free flap surgery in the elderly: Experience with 110 cases aged ≥70 years.

We report our experience with free tissue transfer in the elderly based on a retrospective review of patients aged ≥70 years who underwent surgery during a 7-year period. A total of 110 free tissue transfers in 104 patients, with a mean age of 78 years (range: 70-92 years), were identified for inclusion. The demographic and operative variables and postoperative medical and surgical complications were analyzed. Sixty-four of the 110 procedures encountered at least one complication. Medical complications were observed in 25 cases and were predominantly pulmonary, whereas surgical complications occurred in 54 cases in addition to one perioperative death. Successful free tissue transfer was achieved in 105 of the 110 flaps. There was no statistically significant difference in the rate of postoperative complications between patients aged 70-79 years and those aged ≥80 years. Anesthetic time was a statistically significant predictor of postoperative medical complications (odds ratio 1.345, 95% confidence interval 1.117-1.663, P = 0.001). Preoperative comorbidity status, graded according to the ACE-27 index, was a statistically significant predictor of flap recipient site complications. Free tissue transfer may be performed in aging patients with a high degree of technical success and low operative mortality. Chronological age alone should not be used as a criterion when evaluating a patient for free tissue transfer. The patient's premorbid status should be carefully assessed. To minimize postoperative medical complications, duration of general anesthesia should be kept to a minimum.

Transcutaneous Peripheral Nerve Stimulation for the Treatment of Neuropathic Pain in the Upper Limb.

BACKGROUND: A small number of patients develop intractable peripheral nerve pain following injury or surgery to the upper limb that is refractory to pharmacological treatment. This study reports our results of using transcutaneous peripheral nerve stimulation (TPNS), a non-invasive form of neuromodulation, to treat this difficult problem. METHODS: Seventy-two patients were treated for intractable pain in the upper limb using this technique. Electrical current was delivered transcutaneously through a handheld probe, placed on the skin overlying the affected peripheral nerve proximal to the site of pain. Pain severity was determined before and immediately after treatment by subjective patient self-assessment using a visual analogue pain scale. Pre-post treatment changes in pain severity were analysed by Student's test for paired data. Outcome in respect of overall effectiveness of this treatment, was graded according to the maximum duration of pain relief achieved. RESULTS: Overall, TPNS reduced pain intensity from 8.4 (SD 1.6) before treatment to 4.2 (SD 3.5) immediately after treatment, a highly significant effect ([Formula: see text]). The treatment achieved cure in 8/72 (11%) of our patients and a useful therapeutic outcome (pain relief ≥ 1 day) in 27/72 (38%). The treatment failed in 37/72 (51%). CONCLUSIONS: TPNS warrants consideration as a therapy for neuropathic pain in the upper limb after drug treatment has failed and before offering surgery or spinal root stimulation.

Metrology of electromagnetic static actuation of MEMS microbridge using atomic force microscopy.

The objective of this paper is to describe application of atomic force microscopy (AFM) for characterization and calibration of static deflection of electromagnetically and/or thermally actuated micro-electromechanical (MEMS) bridge. The investigated MEMS structure is formed by a silicon nitride bridge and a thin film metal path enabling electromagnetic and/or thermal deflection actuation. We present how static microbridge deflection can be measured using contact mode AFM technology with resolution of 0.05nm in the range of up to tens of nm. We also analyze, for very small structure deflections and under defined and controlled load force varied in the range up to ca. 32nN, properties of thermal and electromagnetical microbridge deflection actuation schemes.

Zigzag bipedicle flaps for closure of full-thickness longitudinal palmar defects.

This paper reports a new technique of closure of longitudinal full-thickness palmar defects with bipedicle flaps, used in six patients.

Joint replacement in 131 painful osteoarthritic and post-traumatic distal interphalangeal joints.

This study reports the results of Swanson replacement of 131 DIP joints for painful osteoarthritis and two for ongoing pain after injury. Thirty-seven arthroplasties (28 patients) were carried out with extensor tendon division and repair, and postoperative immobilization for 8 weeks. Ninety-four (60 patients) were then carried out without tendon division, allowing immediate mobilization. At assessment after a mean period of 57 months, the mean postoperative range of movement was 39°, and the mean extensor lag was 11°, with significant improvement of both in both operative groups. The severity of pain improved significantly following surgery. All but one patient were satisfied with the cosmetic result of replacement. The overall complication rate was 7/131(5%). Three joints developed cellulitis and one developed osteomyelitis, requiring subsequent fusion. Two joints had subsequent fusions because of persistent lateral instability and marked ulnar deviation and one had a persistent mallet-type deformity, corrected by tendon shortening.

The surgical management of painful nerves of the upper limb: a unit perspective.

Some patients develop excessive peripheral nerve pain beyond that normally experienced after injury or surgery. Managing this pain can be a difficult and frustrating experience for both the surgeon and patient concerned. We present a system for the classification, assessment and treatment of painful neuromas of the upper limb.

Long-term outcomes of osseointegrated digital prostheses for proximal amputations.

This paper presents outcomes after 13, 4, and 3½ years in three digital amputees treated with osseointegrated prostheses. One had prosthetic replacement of the index and middle fingers at the PIP level. The second had four fingers replaced at the PIP level, but only three prostheses were retained. The third had a thumb replacement at the MCP level. All patients scored their reconstructed hand highly in terms of appearance and frequency of use. The first and third patients rated the function of the reconstructed hand as similar to the normal hand, and this was confirmed by the Jebsen Test, but the second patient had poor function. All patients could detect pressure and vibration through their prostheses, although grip and pinch strengths were weaker in all three. All three also experienced some pain in the implanted fingers. This study identifies osseointegration as a stable long-term reconstructive option.

Expanded beam deflection method for simultaneous measurement of displacement and vibrations of multiple microcantilevers.

Here we present an extension of optical beam deflection (OBD) method for measuring displacement and vibrations of an array of microcantilevers. Instead of focusing on the cantilever, the optical beam is either focused above or below the cantilever array, or focused only in the axis parallel to the cantilevers length, allowing a wide optical line to span multiple cantilevers in the array. Each cantilever reflects a part of the incident beam, which is then directed onto a photodiode array detector in a manner allowing distinguishing between individual beams. Each part of reflected beam behaves like a single beam of roughly the same divergence angle in the bending sensing axis as the incident beam. Since sensitivity of the OBD method depends on the divergence angle of deflected beam, high sensitivity is preserved in proposed expanded beam deflection (EBD) method. At the detector, each spot's position is measured at the same time, without time multiplexing of light sources. This provides real simultaneous readout of entire array, unavailable in most of competitive methods, and thus increases time resolution of the measurement. Expanded beam can also span another line of cantilevers allowing monitoring of specially designed two-dimensional arrays. In this paper, we present first results of application of EBD method to cantilever sensors. We show how thermal noise resolution can be easily achieved and combined with thermal noise based resonance frequency measurement.

Congenital vascular malformation associated with multiple cranial, vertebral and upper limb skeletal abnormalities.

The association between congenital vascular malformations and altered bone growth, the so-called vascular bone syndrome, is well documented. Various eponymous syndromes each with their individual traits, such as Klippel-Trenaunay, Parkes-Weber and Servelle-Martorell syndrome have been described, along with variations. We report on a previously undescribed case of congenital vascular malformation associated with multiple skeletal abnormalities affecting the skull, vertebrae and right upper limb, and discuss the literature.