Longitudinal changes in patient-reported outcome measures following total hip arthroplasty and predictors of deterioration during follow-up: a seven-year prospective international multicentre study.

AIMS: The primary aim of this study was to quantify the improvement in patient-reported outcome measures (PROMs) following total hip arthroplasty (THA), as well as the extent of any deterioration through the seven-year follow-up. The secondary aim was to identify predictors of PROM improvement and deterioration. PATIENTS AND METHODS: A total of 976 patients were enrolled into a prospective, international, multicentre study. Patients completed a battery of PROMs prior to THA, at three months post-THA, and at one, three, five, and seven-years post-THA. The Harris Hip Score (HHS), the 36-Item Short-Form Health Survey (SF-36) Physical Component Summary (PCS), the SF-36 Mental Component Summary (MCS), and the EuroQol five-dimension three-level (EQ-5D) index were the primary outcomes. Longitudinal changes in each PROM were investigated by piece-wise linear mixed effects models. Clinically significant deterioration was defined for each patient as a decrease of one half of a standard deviation (group baseline). RESULTS: Improvements were noted in each PROM between the preoperative and one-year visits, with one-year values exceeding age-matched population norms. Patients with difficulty in self-care experienced less improvement in HHS (odds ratio (OR) 2.2; p = 0.003). Those with anxiety/depression experienced less improvement in PCS (OR -3.3; p = 0.002) and EQ-5D (OR -0.07; p = 0.005). Between one and seven years, obesity was associated with deterioration in HHS (1.5 points/year; p = 0.006), PCS (0.8 points/year; p < 0.001), and EQ-5D (0.02 points/year; p < 0.001). Preoperative difficulty in self-care was associated with deterioration in HHS (2.2 points/year; p < 0.001). Preoperative pain from other joints was associated with deterioration in MCS (0.8 points/year; p < 0.001). All aforementioned factors were associated with clinically significant deterioration in PROMs (p < 0.035), except anxiety/depression with regard to PCS (p = 0.060). CONCLUSION: The present study finds that patient factors affect the improvement and deterioration in PROMs over the medium term following THA. Special attention should be given to patients with risk factors for decreased PROMs, both preoperatively and during follow-up. Cite this article: Bone Joint J 2019;101-B:768-778.

Evaluation of vitamin E-diffused highly crosslinked polyethylene wear and porous titanium-coated shell stability: a seven-year randomized control trial using radiostereometric analysis.

AIMS: Vitamin E-diffused, highly crosslinked polyethylene (VEPE) and porous titanium-coated (PTC) shells were introduced in total hip arthroplasty (THA) to reduce the risk of aseptic loosening. The purpose of this study was: 1) to compare the wear properties of VEPE to moderately crosslinked polyethylene; 2) to assess the stability of PTC shells; and 3) to report their clinical outcomes at seven years. PATIENTS AND METHODS: A total of 89 patients were enrolled into a prospective study. All patients received a PTC shell and were randomized to receive a VEPE liner (n = 44) or a moderately crosslinked polyethylene (ModXLPE) liner (n = 45). Radiostereometric analysis (RSA) was used to measure polyethylene wear and component migration. Differences in wear were assessed while adjusting for body mass index, activity level, acetabular inclination, anteversion, and head size. Plain radiographs were assessed for radiolucency and patient-reported outcome measures (PROMs) were administered at each follow-up. RESULTS: In total, 73 patients (82%) completed the seven-year visit. Mean seven-year linear proximal penetration was -0.07 mm (sd 0.16) and 0.00 mm (sd 0.22) for the VEPE and ModXLPE cohorts, respectively (p = 0.116). PROMs (p = 0.310 to 0.807) and radiolucency incidence (p = 0.330) were not different between the polyethylene cohorts. The mean proximal shell migration rate was 0.04 mm per year (sd 0.09). At seven years, patients with radiolucency (34%) demonstrated greater migration (mean difference: 0.6 mm (sd 0.2); p < 0.001). PROMs were lower for patients with radiolucency and greater proximal migration (p = 0.009 to p = 0.045). No implants were revised for aseptic loosening. CONCLUSION: This is the first randomized controlled trial to report seven-year RSA results for VEPE. All wear rates were below the previously reported osteolysis threshold (0.1 mm per year). PTC shells demonstrated acceptable primary stability through seven years, as indicated by low migration and lack of aseptic loosening. However, patients with acetabular radiolucency were associated with higher shell migration and lower PROM scores. Cite this article: Bone Joint J 2019;101-B:760-767.

Evaluation of in vivo wear of vitamin E-diffused highly crosslinked polyethylene at five years: a multicentre radiostereometric analysis study.

AIMS: The primary aim of this study was to compare the wear properties of vitamin E-diffused, highly crosslinked polyethylene (VEPE) and one formulation of moderately crosslinked and mechanically annealed ultra-high molecular weight polyethylene (ModXLPE) in patients five years after primary total hip arthroplasty (THA). The secondary aim was to assess the clinical results of patients treated with VEPE by evaluating patient-reported outcome measures (PROMs), radiological evidence of fixation, and the incidence of mechanical failure. PATIENTS AND METHODS: A total of 208 patients (221 THAs) from four international centres were recruited into a prospective study involving radiostereometric analysis (RSA) and the assessment of clinical outcomes. A total of 193 hips (87%) were reviewed at the five-year follow-up. Of these, 136 (70%) received VEPE (vs ModXLPE) liners and 68 (35%) received ceramic (vs metal) femoral heads. PROMs and radiographs were collected preoperatively and at one, two, and five years postoperatively. In addition, RSA images were collected to measure PE wear postoperatively and at one, two, and five years after surgery. RESULTS: We observed similar bedding in one year postoperatively and wear two years postoperatively between the two types of liner. However, there was significantly more penetration of the femoral head in the ModXLPE cohort compared with the VEPE cohort five years postoperatively (p < 0.001). The only variables independently predictive of increased wear were ModXLPE (vs VEPE) liner type (ß = 0.22, p = 0.010) and metal (vs ceramic) femoral head (ß = 0.21, p = 0.013). There was no association between increased wear and the development of radiolucency (p = 0.866) or PROMs. No patient had evidence of osteolysis. CONCLUSION: Five years postoperatively, patients with VEPE (vs ModXLPE) and ceramic (vs metal) femoral heads had decreased wear. The rates of wear for both liners were very low and have not led to any osteolysis or implant failure due to aseptic loosening.

POMICS: A Simulation Disease Model for Timing Fungicide Applications in Management of Powdery Mildew of Cucurbits.

A weather-based simulation model, called Powdery Mildew of Cucurbits Simulation (POMICS), was constructed to predict fungicide application scheduling to manage powdery mildew of cucurbits. The model was developed on the principle that conditions favorable for Podosphaera xanthii, a causal pathogen of this crop disease, generate a number of infection cycles in a single growing season. The model consists of two components that (i) simulate the disease progression of P. xanthii in secondary infection cycles under natural conditions and (ii) predict the disease severity with application of fungicides at any recurrent disease cycles. The underlying environmental factors associated with P. xanthii infection were quantified from laboratory and field studies, and also gathered from literature. The performance of the POMICS model when validated with two datasets of uncontrolled natural infection was good (the mean difference between simulated and observed disease severity on a scale of 0 to 5 was 0.02 and 0.05). In simulations, POMICS was able to predict high- and low-risk disease alerts. Furthermore, the predicted disease severity was responsive to the number of fungicide applications. Such responsiveness indicates that the model has the potential to be used as a tool to guide the scheduling of judicious fungicide applications.

Mid-term changes in blood metal ion levels after Articular Surface Replacement arthroplasty of the hip.

AIMS: Our first aim was to determine whether there are significant changes in the level of metal ions in the blood at mid-term follow-up, in patients with an Articular Surface Replacement (ASR) arthroplasty. Secondly, we sought to identify risk factors for any increases. PATIENTS AND METHODS: The study involved 435 patients who underwent unilateral, metal-on-metal (MoM) hip resurfacing (HRA) or total hip arthroplasty (THA). These patients all had one measurement of the level of metal ions in the blood before seven years had passed post-operatively (early evaluation) and one after seven years had passed post-operatively (mid-term evaluation). Changes in ion levels were tested using a Wilcoxon signed-rank test. We identified subgroups at the highest risk of increase using a multivariable linear logistic regression model. RESULTS: There were significant increases in the levels of metal ions for patients who underwent both MoM HRA (Chromium (Cr): 0.5 parts per billion (ppb); Cobalt (Co): 1.1 ppb) and MoM THA (Cr: 0.5 ppb; Co: 0.7 ppb). In a multivariable model considering MoM HRAs, the change in the levels of metal ions was influenced by female gender (Co: Odds Ratio (OR) 1.42; p = 0.002 and Cr: OR 1.08; p = 0.006). The change was found to be irrespective of the initial level for the MoM HRAs, whereas there was a negative relationship between the initial level and the change in the level for those with a MoM THA (Co: OR -0.43; p < 0.001 and Cr: OR -0.14; p = 0.033). CONCLUSION: The levels of metal ions in the blood increase significantly over the period until mid-term follow-up in patients with both a MoM HRA and those with a MoM THA. We recommend that the levels of metal ions be measured most frequently for women with a MoM HRA. While those with a MoM THA appear to stabilise at a certain level, the accuracy of this trend is not yet clear. Vigilant follow-up is still recommended. Cite this article: Bone Joint J 2017;99-B(4 Supple B):33-40.

[Acquired hemophilia A in prepartum: case report and literature review]. / Hémophilie A acquise découverte au cours de la grossesse : à propos d'un cas et revue de la littérature.

INTRODUCTION: Acquired hemophilia A (AH) is a rare hemorrhagic disorder, secondary to the occurrence of factor VIII inhibitor. In young patients, this disorder is commonly observed during the post-partum period, and has been rarely documented in the prepartum. We report a new case of a prepartum AH and review literature data. CASE REPORT: An isolated prolongation of the activated partial thromboplastin time (APTT) was fortuitously discovered in a 31-year-old pregnant women, with spontaneous ecchymosis of her lower limbs few days prior to delivery. Coagulation tests revealed decreased factor VIII activity (18%) and the presence of factor VIII inhibitor (1,4 Bethesda unit). In order to eradicate the autoantibody, the patient was first treated with prednisone and then with rituximab. CONCLUSION: Prepartum factor VIII inhibitors need to be precociously recognized to allow prophylactic management of the delivery bleeding.

ISO/IEC 17025 Sysmex R-500 hematology reticulocyte analyzer validation.

The Sysmex R-500 (R-500) Hematology Analyzer is a bench-top system appropriate for the analysis of limited batches of blood samples. The R-500 provides percentage proportional (RET%), absolute reticulocyte (RET#), and absolute red blood cell (RBC#) counts. The system was validated at the Doping Control Laboratory of Athens, according to the International Committee for Standardization in Hematology, International Standards Organization (ISO/IEC) 17025, and World Antidoping Agency (WADA) specifications. The instrument calibration was performed according to the manufacturer and validation parameters comprised linearity, precision, uncertainty (intermediate and long-term precision), comparability, effect of drift, carryover, stability, and accuracy. The linearity and the comparability studies for RET#, RET%, and RBC# were expressed in regression factors (R2) and coefficients of correlation [r(x, y)], respectively. For the precision studies, the coefficients of variation for RET#, RET%, and RBC# were 9.49%, 9.83%, and <1.5%, respectively. For the intermediate precision studies, the coefficients of variation for RET#, RET%, and RBC# were 3.1%, 3.6%, and 0.6%, respectively. Carryover was found to be negligible. Sample stability was demonstrated at both room temperature and at 4 degrees C over a 24-hour period. Comparability studies for the R-500 were performed using a Sysmex SE-9500. The total evaluation led to the conclusion that the R-500 is an accurate and precise analyzer and because of to its relatively limited size, it can be considered a portable instrument, capable to be used in sports competition and training sites, where doping control and health tests are conducted. The analytical methodology of RET% measurement by the R-500 has been incorporated into the Doping Control Laboratory of Athens' Scope of Accreditation according to the ISO/IEC 17025 and WADA specifications.

Minute-by-minute differences in co-activation during treadmill walking in cerebral palsy.

The primary purpose of this study was to determine, in children and adolescents with mild spastic cerebra palsy (CP); 1) minute-by-minute differences in lower limb antagonist muscle co-activation and stride length (SL) during treadmill walking following 12-15 minutes of treadmill walking practice, and 2) if the minute-by-minute pattern of co-activation is affected by site (thigh or lower leg) and lower limb dominance. A secondary purpose was to determine if overall there is a difference in co-activation between the dominant and non-dominant lower limbs. Eight independently ambulatory children and adolescents with mild spastic CP (9.2-15.7 yr) participated in the study. Minute-by-minute lower limb antagonist muscle co-activation and SL were measured during a 3-minute treadmill walk at 90% of individually determined fastest treadmill walking speed. Non-dominant thigh (quadriceps, hamstring muscles) co-activation decreased between minute 1 and a) minute 2 (6%), b) minute 3 (7.2%). Co-activation for the dominant lower leg (tibialis anterior, triceps surae muscles) decreased between minute 1 and minute 3 (11.3%). Non-dominant thigh co-activation was on average 27.3% higher than for the dominant thigh. Thigh co-activation was on average 27.7% higher than for the lower leg, independent of dominance or time. SL increased between minute 1 and minute 3 by 2.1%. Twelve to 15 minutes of treadmill walking practice may be sufficient time to obtain stable co-activation and SL values by minute 2 of a fast treadmill walk. Dominance and site affect the magnitude of co-activation.

Electrical characteristics of human ankle dorsi- and plantar-flexor muscles. Comparative responses during fatiguing stimulation and recovery.

Changes in muscle excitability were investigated during fatigue and the recovery of human dorsi- and plantar-flexor isometric contractions. The indirectly evoked muscle compound action potentials [tibialis anterior (TA) and soleus (SOL) M-waves] were used as an index of excitability. Ten subjects successfully completed five experiments, spaced at least 1 week apart, in which intermittent tetanic trains at different frequencies of stimulation (0-30 Hz) were used to fatigue the ankle dorsi-flexors. Muscles were rendered ischaemic via a thigh cuff inflated above mean arterial pressure. The effects of ischaemia were examined by repeating the 20-Hz stimulation protocol under non-ischaemic conditions. Five of those subjects also participated in one further session in which the ischaemic plantar-flexors were also fatigued. It was hypothesized that muscle excitability would be preferentially retained in the SOL. Maintenance of excitability in both muscles was possible for 1 min regardless of stimulus frequency; thereafter, stimulation at the highest frequencies induced the greatest decline [30 Hz stimulation; 95.4 (0.5)%, P < 0.01) in the amplitude of the M-wave. The decline in M-wave amplitude was always greater than the decline in M-wave area and occurred at firing rates not normally associated with neuromuscular blockade, implying propagation failure along the sarcolemma. The presence of ischaemia significantly accelerated the decline in both amplitude (78% versus 12%, P<0.01) and area (45% versus no decline, P<0.01) of the M-wave. Recovery was limited when tetanic stimulation ceased but progressed rapidly after circulation was restored. Twitch and tetanic torque declines were significantly different between SOL and TA (fall between rest and fatigue -SOL: 77%, 75.2%; TA: 95.5%, 96.9%, P<0.01, respectively). M-wave changes between the two muscles were not significantly different although the onset of the decline was delayed in the SOL. It is proposed that the observed delay in fatiguing decline was due to the early potentiation in muscle excitability observed in the SOL but not in the TA.

Use of a cold cathode for percutaneous stimulation of human plantarflexor muscles.

Prolonged, supramaximal stimulation of the soleus muscle is painful to humans. A method is proposed whereby percutaneous, supramaximal stimulation is possible using a cold cathode. Cooling the skin exposed to the stimulating current results in a sufficient anaesthesia of nociceptive cutaneous afferent nerves. This occurs without concomitant cooling of the muscle mass deep to the skin and subcutaneous tissue.

Depletion and sizes of motor units in spinal muscular atrophy.

Motor unit number estimation (MUNE) was applied to the biceps brachii muscles of 13 young patients (age 5--24 years) with spinal muscular atrophy (SMA) and the results compared with those of healthy control subjects matched for age and gender. In the SMA patients, all motor unit (MU) estimates fell below the control range, and there was good correspondence between the values for the two arms in the same subject. No correlation could be found between the MUNEs and the severity of the weakness. This unexpected result was attributed to the presence of small and normal-sized MUs in the muscles of patients, in addition to MUs that appeared to be considerably enlarged. The threefold mean increase in MU potential size was insufficient to compensate for the MU loss. In addition, the study confirmed that there are, on average, approximately 130 MUs in the healthy biceps brachii muscle.

Enhancing the ability of gait analyses to differentiate between groups: scaling gait data to body size.

One goal of gait analysis is to distinguish clearly between a set of abnormal gait values measured from a patient referenced to a comparable population. However, the comparable population is often composed of individuals of various heights and weights, which increases inter-subject gait value variation which reduces the ability of a statistical test to identify a set of gait data outcomes with evaluative properties. Therefore, scaling gait data, based on subject leg length and mass, is commonly used to decrease the inter-subject variation but the efficacy of these methods is unknown. In this paper each of eight scaling strategies (none, ad hoc, dimensionless numbers, and five connected strategies based on similarity, dimensional analysis and muscle properties) were used to modify a set of gait data outcomes acquired from 10 individuals spanning a wide range of height (1.33-1.96 m) and mass (42.3-148.8 kg). These data were then examined to select that strategy and those scaling factors which maximally reduced inter-subject variation. The ad hoc, dimensionless numbers, and dynamic/mechanical/elastic (diameter of a limb (D) proportional to it's length (L) to the 1.5 power; time proportional to L(2) D(-1)) scaling strategies reduced the global inter-subject gait data outcome variation to 44% of its un-scaled value. Considering ten commonly reported gait data outcomes (temporal and spatial (stride time, stride length, progression velocity), kinematic (angles in the sagittal and frontal planes, angles in the transverse plane), external kinetic (ground reaction force and moment), and internal kinetic (joint force, moment, and power)) these three scaling strategies provided the largest number of minimum inter-subject variations (10, 10, and 9, respectively). Reduced inter-subject variation in gait data outcomes increases the ability of a statistical tool to detect a difference between a patient and a comparable group. With a statistically significant difference a clinician can then decide if this patient's gait pattern clinically deviates from that of the comparable group and an appropriate intervention warranted. The ad hoc, dimensionless numbers, and the dynamic/mechanical/elastic scaling strategies all reduce maximally the inter-subject variation in gait data outcomes.

Use of orthoses lowers the O(2) cost of walking in children with spastic cerebral palsy.

PURPOSE: The aim of this study was to assess the effects of hinged ankle foot orthoses (AFO) on the metabolic and cardiopulmonary cost of walking and gross motor skills of children with cerebral palsy (CP). METHODS: Ten habitual users of hinged AFO with spastic diplegic CP (9.01 yr +/- 2.10) participated in the study. Expired gas and heart rate (HR) were measured during sitting and with AFO on and off during steady state treadmill walking at three speeds: 3 km.h(-1), comfortable walking speed (CWS), and 90% of their fastest walking speed (FWS). Comfortable and fastest ground walking speed and Gross Motor Function Measure scores were also assessed with AFO on and off and analyzed with ANOVA. Because not all children could walk at all speeds on the treadmill, an ANOVA was performed on data for children who walked at 3 km.h(-1) and CWS (N = 8 for HR; N = 9 for pulmonary ventilation and metabolic variables) and a t-test on data at 90% of FWS (N = 9 for HR; N = 8 for pulmonary ventilation and metabolic variables). RESULTS: When children wore their AFO net oxygen uptake (L.min(-1), absolute--sitting values) was significantly (P < 0.05) reduced by 8.9% at 3 km.h(-1) and by 5.9% at 90% of FWS. Net pulmonary ventilation (L.min(-1)) was significantly (P < 0.05) lower with AFO on by 10.3% but only at 3 km.h(-1). AFO did not affect net HR (beats.min(-1)) nor the respiratory exchange ratio at any speed, nor any physiologic variable at CWS, nor gross motor skills. CONCLUSIONS: Use of hinged AFO reduces the oxygen and ventilatory cost of walking in children with spastic diplegic CP.

Developmental apraxia arising from neonatal brachial plexus palsy.

OBJECTIVE: To determine whether motor unit activation is impaired in patients with persisting disability arising from neonatal brachial plexus palsy (NBPP). BACKGROUND: In NBPP patients, the authors previously found more extensive muscle reinnervation than might have been anticipated from the clinical examination. METHODS: Motor skills were tested in a group of nine boys and seven girls with prior NBPP, who then underwent physiologic investigation of proximal and distal muscles in their affected and unaffected arms. The latter tests comprised measurements of maximal evoked muscle compound action potential (M-wave) amplitude, maximal voluntary torque, twitch torque, and twitch interpolation. A group of 17 children of similar ages served as control subjects. RESULTS: In the NBPP group, motor skills were diminished and voluntary torque was reduced relative to M-wave amplitude and twitch torque. Moreover, interpolated twitches could be demonstrated in some NBPP patients but not in control subjects. CONCLUSION: Persisting disability in NBPP patients is due, at least in part, to impaired motor unit activation. The authors suggest that the impairment is a form of developmental apraxia caused by defective motor programming in early infancy.

Loss of twitch torque following muscle compression.

With the elbow flexed, compression of the human biceps brachii has been found to reduce twitch torque, with an approximately linear relationship being observed between the loss of torque and the applied pressure (up to 45 kPa). The decline in torque could no longer be demonstrated when the biceps muscle was stretched, by extending the elbow from a flexed position. The loss of torque in the flexed position appeared to be due to an inability of muscle sarcomeres to bulge sufficiently to take up the series elasticity at the fiber ends.

Changes in motor unit estimates with aging.

Elderly persons usually exhibit some degree of muscle atrophy, together with a reduction in voluntary strength, but there is still argument concerning the nature of the cellular events involved. This issue was reexamined by estimating the numbers and relative sizes of motor units in three limb muscles, using a fully automated system (Galea et al., 1993). In 79 healthy volunteers aged 20-98 years, estimations of motor unit numbers were performed on the thenar, biceps brachii, and extensor digitorum brevis muscles. Motor unit populations were noted to decrease significantly with age in the distal muscles but appeared to remain constant in the biceps. The excitable muscle fiber mass, as reflected in the peak-to-peak amplitude and area of the maximum M-wave, was diminished in all three muscles. Although the area of the average motor unit action potential was not significantly different between groups, the ratio of this potential to the M-wave area increased with increasing age. The results suggest that muscle deterioration in the elderly is due to a combination of changes in the muscle fibers and in their nerve supply and that the extent may differ between proximal and distal muscles.

Potentiation and depression of the M wave in human biceps brachii.

1. The effects of repeated excitation on the compound action potential, or M wave, of mammalian muscle fibres have been investigated in the human biceps brachii. 2. During continuous indirect stimulation at 10 and 20 Hz the mean voltage-time area of the M wave doubled within the first minute, while the mean peak-to-peak amplitude increased by approximately half. The enlargement of the M wave was sustained during stimulation at 10 Hz but not at 20 Hz. Stimulation at 3 Hz caused a small increase which was significant for M wave amplitude only. 3. When the 20 Hz stimulation was performed under ischaemic conditions, the M wave first enlarged and then gradually declined. After 20 Hz stimulation was discontinued, the M wave increased in size; in the ischaemic experiments the release of the cuff produced a further, rapid augmentation. In both the ischaemic and non-ischaemic experiments, the amplitudes and areas of the M waves during the recovery period became significantly larger than the resting values (range, 15-60% at the endplate zone). 4. The mean muscle fibre impulse conduction velocity decreased to less than half the resting value during 20 Hz stimulation, with or without ischaemia, and then increased above the resting value during recovery. 5. On the basis of previous experiments in animals, the augmentation of the M wave was attributed to enhanced electrogenic Na(+)-K+ pumping, and the biceps brachii appeared to be an excellent preparation for studying the time course of this enhancement.