Evaluation of intraoperative ketamine on the prevention of severe rebound pain upon cessation of peripheral nerve block: a prospective randomised, double-blind, placebo-controlled study.

BACKGROUND: Pain after resolution of peripheral nerve block, known as 'rebound pain' (RP), is a major problem in outpatient surgery. The primary objective was to evaluate the benefit of intraoperative ketamine at an anti-hyperalgesic dose on the incidence of rebound pain after upper limb surgery under axillary plexus block in ambulatory patients. The secondary objective was to better understand the rebound pain phenomenon (individual risk factors). METHODS: In this prospective, double-blind study, patients were randomised to receive either a single dose of i.v. ketamine (0.3 mg kg-1) or a placebo. Preoperative mechanical temporal summation and central sensitization inventory were applied to question underlying central sensitisation. Pain catastrophising and Douleur Neuropathique 4 questionnaires were used. Rebound pain was defined as pain intensity score >7 (numeric rating scale, 0-10) after block resolution. Postoperative pain was recorded at Days 1, 4, and 30 after discharge. RESULTS: A total of 109 subjects completed the study, and 40.4% presented with rebound pain. Ketamine administration did not reduce rebound pain incidence or intensity. Temporal summation and central sensitisation inventory scores did not differ between subjects with and without rebound pain. The predictive risk factors were bone surgery (odds ratio [OR]=5.2; confidence interval [CI], 1.9-14.6), severe preoperative pain (OR=4.2; CI, 1.5-11.7), and high pain catastrophising (OR=4.8; CI, 1.0-22.3). At Day 30, the average daily pain was higher in the rebound pain group involving neuropathic characteristics. CONCLUSION: Ketamine at an anti-hyperalgesic dose showed no benefit on rebound pain development. Although central sensitisation might not be involved, preoperative pain intensity, and catastrophising stand as risk factors. Because rebound pain remains frequent despite adequate procedure-specific postoperative analgesia, future studies should focus on patient-specific pain management.

Recognizing Manual Activities Using Wearable Inertial Measurement Units: Clinical Application for Outcome Measurement.

The ability to monitor activities of daily living in the natural environments of patients could become a valuable tool for various clinical applications. In this paper, we show that a simple algorithm is capable of classifying manual activities of daily living (ADL) into categories using data from wrist- and finger-worn sensors. Six participants without pathology of the upper limb performed 14 ADL. Gyroscope signals were used to analyze the angular velocity pattern for each activity. The elaboration of the algorithm was based on the examination of the activity at the different levels (hand, fingers and wrist) and the relationship between them for the duration of the activity. A leave-one-out cross-validation was used to validate our algorithm. The algorithm allowed the classification of manual activities into five different categories through three consecutive steps, based on hands ratio (i.e., activity of one or both hands) and fingers-to-wrist ratio (i.e., finger movement independently of the wrist). On average, the algorithm made the correct classification in 87.4% of cases. The proposed algorithm has a high overall accuracy, yet its computational complexity is very low as it involves only averages and ratios.

Forearm deformity in multiple hereditary exostosis. Radiologic predictors of radial head dislocation.

INTRODUCTION: Radial head dislocation in patients with multiple hereditary exostosis (MHE) can lead to functional deficit. We investigated whether the location of the exostosis and certain radiological criteria predict risk of radial head dislocation/subluxation. HYPOTHESIS: We hypothesized that the radiological criteria differentiate between patients who need closer follow-up of the forearm and others for whom multiple radiographs are superfluous. PATIENTS AND METHODS: We retrospectively reviewed the demographics of patients with MHE in our hospital, and radiographic measurements were made on forearm radiographs: radial length, ulnar length, ulnar variance, radial articular angle, and radial bowing. RESULTS: Forty-nine forearms were analyzed in 30 patients. Mean age was 9.5 years at first evaluation and 11.8 years at last evaluation. Radial head dislocation or subluxation was found in 6 forearms (12%). Risk factors comprised isolated exostosis in the distal portion of the ulna or exostosis in the distal part of both the ulna and radius, radial or ulnar shortening>4.6cm, radial bowing>8.1%, radial articular angle>35°, and≥3 exostoses in the forearm. DISCUSSION: In patients with MHE with risk factors for radial head dislocation, close follow- up with regular radiography is indicated and early surgery should be performed before the radial head dislocates. LEVEL OF EVIDENCE: IV; retrospective study.

Effect of Intravenous Dexamethasone Dose on the Occurrence of Rebound Pain after Axillary Plexus Block in Ambulatory Surgery.

Rebound pain (RP) remains a challenge in ambulatory surgery, characterized by severe pain upon resolution of a peripheral nerve block (PNB). Intravenous (IV) administration of Dexamethasone (DEXA) potentiates PNB analgesic effect and reduces RP incidence although preventive effective dose remains undetermined. This retrospective analysis evaluates the preventive effect of IV DEXA on RP in outpatients undergoing upper limb surgery under axillary block. DEXA was divided into high (HD > 0.1 mg/kg) or low (LD < 0.1 mg/kg) doses. RP was defined as severe pain (NRS ≥ 7/10) within 24 h of PNB resolution. DEXA HD and LD patients were matched with control patients without DEXA (n = 55) from a previous randomized controlled study. Records of 118 DEXA patients were analyzed (DEXA dose ranged from 0.05 to 0.12 mg/kg). Intraoperative IV DEXA was associated with a significant reduction of the pain felt when PNB wore off as well as to a significant reduction of RP incidence (n = 27/118, 23% vs. 47% in controls, p = 0.002) with no effect related to the dose administered (p = 0.053). Our results support the administration of intraoperative DEXA as a preventive measure to reduce the occurrence of RP.

Characterizing biased visuospatial perception in complex regional pain syndrome.

BACKGROUND: Patients suffering from complex regional pain syndrome (CRPS) are increasingly shown to be affected by cognitive difficulties. While these cognitive symptoms were initially described as limited to the perception, representation and use of the body, that is, the somatic space, they were recently shown to also extend to the perception of extra-somatic space. CRPS patients seem indeed to pay less attention to visual stimuli occurring in the same side of space as their affected limb and especially those occurring close to that limb. The aim of the present study was to more precisely characterize these visuospatial biases, by investigating whether they may be dependent on the visually perceived proximity between the visual stimuli and the affected limb. METHODS: Upper-limb CRPS patients and matched control participants performed temporal order judgements on visual stimuli, one presented in either side of space, while they could either see their hands near the visual stimuli or not. RESULTS: Visuospatial biases were not modulated by the availability of visual feedback about the hands. However, secondary analyses revealed that these biases depended on the type of rehabilitation program that the patients followed: whereas patients who did not follow any specific program presented significant biases to the detriment of visual stimuli in the affected side of space, patients who did follow a CRPS-specialized program did not. CONCLUSIONS: Patients' cognitive strategies will be important to consider when studying inter-individual differences in the cognitive symptomatology and associated cognitive-based rehabilitation procedures in CRPS. SIGNIFICANCE: The existence of biases in visuospatial perception in Complex Regional Pain Syndrome has been reported but not always systematically replicated. We show that these biases might depend on the type of general rehabilitation program that the patients follow. Patients' individual cognitive strategies will be important to consider when studying the cognitive symptomatology of CRPS.

Intensive hands-on microsurgery course provides a solid foundation for performing clinical microvascular surgery.

PURPOSE: Microvascular surgery requires highly specialized and individualized training; most surgical residency training programs are not equipped with microsurgery teaching expertise and/or facilities. The aim of this manuscript was to describe the methodology and clinical effectiveness of an international microsurgery course, currently taught year-round in eight countries. METHODS: In the 5-day microsurgery course trainees perform arterial and venous end-to-end, end-to-side, one-way-up, and continuous suture anastomoses and vein graft techniques in live animals, supported by video demonstrations and hands-on guidance by a full-time instructor. To assess and monitor each trainee's progress, the course's effectiveness is evaluated using "in-course" evaluations, and participant satisfaction and clinical relevance are assessed using a "post-course" survey. RESULTS: Between 2007 and 2017, more than 600 trainees participated in the microsurgery course. "In-course" evaluations of patency rates revealed 80.3% (arterial) and 39% (venous) performed in end-to-end, 82.7% in end-to-side, 72.6% in continuous suture, and 89.5% (arterial) and 62.5% (venous) one-way-up anastomoses, and 58.1% in vein graft technique. "Post-course" survey results indicated that participants considered the most important components of the microcourse to be "practicing on live animals", followed by "the presence of a full-time instructor". In addition, almost all respondents indicated that they were more confident performing clinical microsurgery cases after completing the course. CONCLUSIONS: Microvascular surgery requires highly specialized and individualized training to achieve the competences required to perform and master the delicate fine motor skills necessary to successfully handle and anastomose very small and delicate microvascular structures. The ever-expanding clinical applications of microvascular procedures has led to an increased demand for training opportunities. By teaching time-tested basic motor skills that form the foundation of microsurgical technique this international microsurgery-teaching course is helping to meet this demand.

Use of a 3D-printed splint for the treatment of distal radius fractures: A randomized controlled trial.

BACKGROUND: Management of distal radius fractures typically includes a period of immobilization with either a cast or a splint. Traditional immobilization methods can have inconveniences such as poor resistance to water and poor ventilation, which can result in skin maceration, skin breakdown, and infection in case of wetting. HYPOTHESIS: 3D-printed splints could potentially overcome the inconveniences of traditional casts. In this report, we compare a 3D-printed splint (3DPS) with a conventional removable splint (CRS) and a traditional cast in a randomized clinical trial. PATIENTS AND METHODS: Thirty-four patients with a recent distal radius fracture were randomized to receive either a 3DPS or a CRS. An additional subset of nine patients benefitted from both splints for a direct comparison. Primary outcomes were measured based on a subjective assessment questionnaire and a clinical outcome. RESULTS: There was no statistical difference in the subjective assessment between the 3DPS and the CRS groups. Based on the clinical assessment, patients with the 3DPS experienced more pressure-related pain. Among the sub-sample of nine patients that benefited from both splints, eight preferred the CRS and one chose the 3DPS. The 3DPS was judged better for perspiration, coolness, and water resistance. DISCUSSION: The 3DPS was successful in solving shortcomings of conventional splints and cast (better ventilation, less perspiration, less warmness, more durability and water resistance). However, the rigid structure and sharp edges made it less comfortable, overall favouring the CRS. LEVEL OF EVIDENCE: II.

Instability of the extensor digitorum tendons in Jaccoud arthropathy assessed by semi-dynamic MRI of the metacarpophalangeal joints.

PURPOSE: The purpose of this study was to test the hypothesis that Jaccoud arthropathy (JA) in patients with systemic lupus erythematosus (SLE) is associated with instability of the extensor digitorum (ED) tendons during flexion of the metacarpophalangeal (MCP) joints by comparing the position of the ED tendons between SLE patients with JA and control subjects on hand MRI obtained with flexed and extended MCP joints. MATERIALS AND METHODS: Thirty-two hands of SLE patients with JA (13 women and 3 men; mean age, 50.0±12.2 [SD] years; age range: 26-68years) and 24 hands of sex- and age-matched control subjects (20 women and 4 men; mean age, 50.1±13.0 [SD] years; age range: 24-68years) were included in the study. Axial spin echo T1-weighted MRI images of the second to fifth MCP joints in flexion and in extension were obtained. Two radiologists (R1 and R2) separately measured the amplitude and assessed the direction of the displacement of the ED tendons with respect to the midline at the level of each MCP joint. Statistical analysis included two-way ANOVA with random effects to assess differences in amplitude and Fisher-Freeman-Halton exact test to assess differences in direction with P-values<0.0083 and<0.0063 considered as statistically significant respectively. RESULTS: Amplitude of the displacement of the ED tendons was statistically significantly greater in SLE patients with JA than in control subjects in flexion for both readers (median 58°, 95% confidence interval [CI]: 50°-65° vs. 20°, 95% CI: 16°-24°; P<0.0001 for R1 and 54°, 95% CI: 47°-61° vs. 25°, 95% CI: 22°-28°; P<0.0001 for R2) and in extension for one reader (17°, 95% CI: 15°-20° vs. 14°, 95% CI: 11°-16°; P=0.0048 for R1 and 20°, 95% CI: 15°-25° vs. 16°, 95% CI: 12°-18°; P=0.0292 for R2). Ulnar deviation of the ED tendons was statistically significantly more frequent in SLE patients with JA than in control subjects in flexion and in extension for both readers (P<0.0001). CONCLUSION: JA is associated with instability of the ED tendons in patients with SLE best depicted when MCP joints are flexed.

Visuomotor impairments in complex regional pain syndrome during pointing tasks.

ABSTRACT: Complex regional pain syndrome (CRPS) is thought to be characterized by cognitive deficits affecting patients' ability to represent, perceive, and use their affected limb as well as its surrounding space. This has been tested, among others, by straight-ahead tasks testing oneself's egocentric representation, but such experiments lead to inconsistent results. Because spatial cognitive abilities encompass various processes, we completed such evaluations by varying the sensory inputs used to perform the task. Complex regional pain syndrome and matched control participants were asked to assess their own body midline either visually (ie, by means of a moving visual cue) or manually (ie, by straight-ahead pointing with one of their upper limbs) and to reach and point to visual targets at different spatial locations. Although the 2 former tasks only required one single sensory input to be performed (ie, either visual or proprioceptive), the latter task was based on the ability to coordinate perception of the position of one's own limb with visuospatial perception. However, in this latter task, limb position could only be estimated by proprioception, as vision of the limb was prevented. Whereas in the 2 former tasks CRPS participants' performance was not different from that of controls, they made significantly more deviations errors during the visuospatial task, regardless of the limb used to point or the direction of pointing. Results suggest that CRPS patients are not specifically characterized by difficulties in representing their body but, more particularly, in integrating somatic information (ie, proprioception) during visually guided movements of the limb.

Manual ability in hand surgery patients: Validation of the ABILHAND scale in four diagnostic groups.

BACKGROUND: Patients treated in hand surgery (HS) belong to different demographic groups and have varying impairments related to different pathologies. HS outcomes are measured to assess treatment results, complication risks and intervention reliability. A one-dimensional and linear measure would allow for unbiased comparisons of manual ability between patients and different treatment effects. OBJECTIVE: To adapt the ABILHAND questionnaire through Rasch analysis for specific use in HS patients and to examine its validity. METHODS: A preliminary 90-item questionnaire was presented to 216 patients representing the diagnoses most frequently encountered in HS, including distal radius fracture (n = 74), basal thumb arthritis (n = 66), carpal tunnel syndrome (n = 53), and heavy wrist surgery (n = 23). Patients were assessed during the early recovery and in the late follow-up period (0-3 months, 3-6 months and >6 months), leading to a total of 305 assessments. They rated their perceived difficulty with queried activities as impossible, difficult, or easy. Responses were analyzed using the RUMM2030 software. Items were refined based on item-patient targeting, fit statistics, differential item functioning, local independence and item redundancy. Patients also completed the QuickDASH, 12-item Short Form Survey (SF-12) and a numerical pain scale. RESULTS: The rating scale Rasch model was used to select 23 mostly bimanual items on a 3-level scale, which constitute a unidimensional, linear measure of manual ability with good reliability across all included diagnostic groups (Person-Separation Index = 0.90). The resulting scale was found to be invariant across demographic and clinical subgroups and over time. ABILHAND-HS patient measures correlated significantly (p<0.001) with the QuickDASH (r = -0.77), SF-12 Physical Component Summary (r = 0.56), SF-12 Mental Component Summary (r = 0.31), and pain scale (r = -0.49). CONCLUSION: ABILHAND-HS is a robust person-centered measure of manual ability in HS patients.

Robot-assisted line bisection in patients with Complex Regional Pain Syndrome.

Complex Regional Pain Syndrome (CRPS) is characterized by pain, motor and inflammatory symptoms usually affecting one limb. Cognitive difficulties have been reported to affect patients' ability to represent, perceive and use their affected limb. It is debated whether these difficulties result from deficits in controlling goal-directed movements in space or from a learned strategy to protect the affected limb. In order to dissociate the two hypotheses, patients with upper-limb CRPS were asked to move with their unaffected hand towards visual targets projected at different positions on a horizontal semi-reflexive mirror. By means of a robotic handle placed below the screen, they were asked to move a cursor, to reach and cross lines at their estimated midpoint. In some of the stimulation series, the affected hand was placed below the mirror so that some lines appeared projected onto that hand. Vision of the hands and the robotic handle was preserved or prevented by opening or closing a shutter below the mirror. Lines were displayed on the mirror according to which part of the body was affected (ispi- vs. contralateral) and the actual position of the affected hand (inside vs. outside the workspace). Comparatively to control participants, CRPS patients generally biased their estimation by bisecting the lines towards their left side, irrelative of which part of the body was affected and the position of the affected hand, both in ipsi- and contralateral space, with only a few exceptions. Our results are in line with previous studies having described a visuospatial deficit in CRPS patients and discard the explanation of observed symptoms in terms of learned nonuse strategies, as only the unaffected hand was used to perform the task. It is suggested that CRPS patients can display difficulties to perform tasks requesting visuo-motor coordination, reflecting the complex cortical reorganization occurring in CRPS.

Biased visuospatial perception in complex regional pain syndrome.

Complex regional pain syndrome (CRPS) is a chronic pain condition associating sensory, motor, trophic and autonomic symptoms in one limb. Cognitive difficulties have also been reported, affecting the patients' ability to mentally represent, perceive and use their affected limb. However, the nature of these deficits is still a matter of debate. Recent studies suggest that cognitive deficits are limited to body-related information and body perception, while not extending to external space. Here we challenge that statement, by using temporal order judgment (TOJ) tasks with tactile (i.e. body) or visual (i.e. extra-body) stimuli in patients with upper-limb CRPS. TOJ tasks allow characterizing cognitive biases to the advantage of one of the two sides of space. While the tactile TOJ tasks did not show any significant results, significant cognitive biases were observed in the visual TOJ tasks, affecting mostly the perception of visual stimuli occurring in the immediate vicinity of the affected limb. Our results clearly demonstrate the presence of visuospatial deficits in CRPS, corroborating the cortical contribution to the CRPS pathophysiology, and supporting the utility of developing rehabilitation techniques modifying visuospatial abilities to treat chronic pain.

Tactile roughness discrimination of the finger pad relies primarily on vibration sensitive afferents not necessarily located in the hand.

This study aims to investigate the relative contribution of remote mechanoreceptors to perception of roughness and spatial acuity. We examined two unilateral pathological conditions affecting differently innervation of the index finger: unilateral carpal tunnel syndrome (n=12) and surgically repaired complete traumatic median nerve section at the wrist following surgical repair (n=4). We employed a control condition consisting of ring-block anesthesia of the entire index in 10 healthy subjects to model pathological denervation of the fingertip. Spatial acuity and the ability to discern roughness were assessed using a grating orientation task and a roughness discrimination task, respectively. In patients with carpal tunnel syndrome, we observed a significant reduction of spatial resolution acuity but an intact ability to discriminate roughness with the fingertip. For patients with traumatic median nerve section there was no recovery with the grating orientation task up to 20 months post surgery but a progressive and full recovery with the roughness discrimination task between 6 and 9 months. Finally, in the anesthetic ring bloc group, the nerve block completely disrupted performances in grating orientation task, but unexpectedly left unaffected performances in the roughness discrimination task. Taken together, these lines of evidence support the view that the neural mechanisms underlying tactile roughness discrimination differ from those involved in spatial resolution acuity. Vibrotaction is necessary and sufficient for the perception of fine textures and, when the innervation of the fingerpad is compromised, information about textures can be captured and encoded by remote mechanoreceptors located in more proximal tissues where the innervation is intact.

Tactile roughness discrimination threshold is unrelated to tactile spatial acuity.

The present study examined the relationship between the tactile roughness discrimination threshold (TRDT) and the tactile spatial resolution threshold (TSRT) at the index fingertip in humans. A new device was built for measuring TRDT, allowing pair-wise presentations of two sets of six different sandpaper grits. The smoothest grits ranged from 18 to 40 microm and the roughest grits ranged from 50 to 195 microm particle size. The reference sandpaper had a 46 microm particle size. A two-alternative forced choice paradigm and a double interlaced adaptive staircase procedure yielding a 75% just noticeable difference (75%jnd) was used according to Zwislocki and Relkin. Contact force and scanning velocity were measured at the fingertip with a built-in sensor. The TSRT was assessed with an extended set of grating domes. Fifty-three male and female subjects, spanning a wide age range participated in this study. The JND75% or TRDT was lower for the smoothest sandpapers (15+/-8.5 microm) compared to the roughest sandpapers (44+/-32.5 microm). TRDT performance was unrelated to age or gender. Additionally, grit size had no effect on the mean forces (normal and tangential) exerted at the fingertip or the mean scan velocities. In contrast, there was a significant degradation of TSRT performance with age. Lastly, there was no significant correlation between TRDT and TRST performance. Results of this study support the theory that the neural mechanisms underlying the perception of tactile roughness discrimination for fine textures differ from those involved in spatial resolution acuity often associated with the SA1 afferents.

Particle size influence in an impaction bone grafting model. Comparison of fresh-frozen and freeze-dried allografts.

BACKGROUND: Impaction bone grafting with large particles is considered as mechanically superior to smaller morsels. Interest of freeze-dried irradiated bone for impaction bone grafting has been observed with small particles. Influence of bone process on other particle sizes still needed to be assessed. MATERIAL AND METHODS: Twenty-four osteoarthrotic femoral heads were used to prepare fresh-frozen and freeze-dried irradiated cancellous bone. Each group was divided into four batches of different particle sizes, each batch containing 18 samples. The different particle sizes were obtained with a Retsch Cross Beater Mill SK 100, Noviomagus rotating bone mills with two sizes of rasps and a Luer bone rongeur. Bone grafts were impacted in a contained cylinder. Stiffness was monitored during impaction. RESULTS: Freeze-dried irradiated grafts showed higher stiffness than fresh-frozen bone whatever the size of the particles. Large particles obtained with the rongeur and the large rasp from the Noviomagus bone mill were mechanically superior than small particles up to 30 impactions. INTERPRETATION: Large particles offer better mechanical performance as a greater magnitude of force would be required to deform and break the particles. Freeze-dried irradiated bone brittleness reduces this advantage after 30 impactions. Large particles embrittlement leads to similar mechanical results as small particles at higher impaction rate. This may account for partial collapse of the graft layer in clinical situation when impaction rate is lower. This model supports the use of small particles obtained with thin rasp bone mill when freeze-dried irradiated bone for impaction bone grafting and large particles obtained with the Rongeur when fresh-frozen bone is available.

Freeze-dried irradiated bone brittleness improves compactness in an impaction bone grafting model.

BACKGROUND: Defatted bone chips with or without freeze-drying and irradiation have mechanical advantages as compared to fresh-frozen controls in in vitro models of impaction. These improved results have been ascribed to replacement of viscous bone marrow by saline and embrittlement of the freeze-dried bone by irradiation. MATERIAL AND METHODS: To determine which of these hypotheses is correct, we compared the development of stiffness and compactness of morselized bone graft that had been: 1) fat-reduced with saline, and 2) fresh-frozen, solvent-detergent defatted, 3) freeze-dried irradiated and 4) not irradiated. We used 12 osteoarthrotic femoral heads to prepare these four batches of morselized bone, and impacted 18 samples from each batch in a cylinder. The frozen bone grafts were tested after thawing at room temperature for 2 hours and the freeze-dried grafts were tested after 30 minutes of rehydration. We monitored the development of compactness and stiffness of the material during impaction. RESULTS: The stiffness of the freeze-dried irradiated bone was greater than that of the other three series after 10, 50 and 150 impactions. The freeze-dried bone chips that were not irradiated and the chips defatted with saline alone were less stiff than the fresh-frozen control after 150 impactions. INTERPRETATION: The brittleness of freeze-dried irradiated bone, caused by loss of the capacity to absorb energy in a plastic way, increases the compactness and stiffness of the morselized grafts. Washing bone with saline alone or treating bone with solvent-detergent but no irradiation had no similar mechanical advantage and the bone did not impact better than fresh-frozen undefatted bone in our model.