Duration Of Lengthening Research Articles

Humerus Lengthening with a Motorized Intramedullary Nail: A Systematic Review of Outcomes and Complications.

In the past decade, internal limb lengthening nails have gained popularity. In this study, we aim to systematically review the literature on humerus limb lengthening with a motorized intramedullary nail (MIN). We intend to assess the outcome and complications of this technique. A systematic review was performed in the following databases: PubMed, Embase, Web of Science, and the Journal of Limb Lengthening and Reconstruction. The inclusion criteria included limb lengthening of the humerus using an intramedullary nail, clinical studies, all levels of evidence, and no restriction to the date of publication. Our search yielded 239 journal articles. A total of nine articles remained relevant based on the inclusion and exclusion criteria. The total number of patients was 20, with 22 segments lengthened. The mean age of the patients was 20.8-year-old [standard deviation (SD), 12.0; range, 13-51]. The mean gained length was 5.7 cm (SD, 0.9; range, 5-7.5) with a mean distraction protocol of 0.82 mm/day (SD, 0.2; range, 0.6-1). The average duration of lengthening was 71.6 days (SD, 12.8; range, 50-93), and the mean duration of consolidation was 192.3 days (SD, 40.5; range, 120-228). Reported complications included a range of motion (ROM) limitation, hardware failure, and hypertrophic bone regeneration. Humeral lengthening with an MIN provides favourable outcomes with low complication rates. Future high-level studies should focus on comparing long-term outcomes of humeral lengthening utilising internal and external fixation techniques. Humeral lengthening using MIN can be used safely. Each surgical approach and type of nail have different risks and benefits. These should be carefully discussed when planning the surgery. Lorange JP, Alamiri N, Marwan Y, et al. Humerus Lengthening with a Motorized Intramedullary Nail: A Systematic Review of Outcomes and Complications. Strategies Trauma Limb Reconstr 2022;17(3):165-171.

Can temperature-dependent changes in myocardial contractility explain why fish only increase heart rate when exposed to acute warming?

ABSTRACTFish increase heart rate (fH), not stroke volume (VS), when acutely warmed as a way to increase cardiac output (Q). To assess whether aspects of myocardial function may have some basis in determining temperature-dependent cardiac performance, we measured work and power (shortening, lengthening and net) in isolated segments of steelhead trout (Oncorhynchus mykiss) ventricular muscle at the fish's acclimation temperature (14°C), and at 22°C, when subjected to increased rates of contraction (30–105 min−1, emulating increased fH) and strain amplitude (8–14%, mimicking increased VS). At 22°C, shortening power (indicative of Q) increased in proportion to fH, and the work required to re-lengthen (stretch) the myocardium (fill the heart) was largely independent of fH. In contrast, the increase in shortening power was less than proportional when strain was augmented, and lengthening work approximately doubled when strain was increased. Thus, the derived relationships between fH, strain and myocardial shortening power and lengthening work, suggest that increasing fH would be preferable as a mechanism to increase Q at high temperatures, or in fact may be an unavoidable response given constraints on muscle mechanics as temperatures rise. Interestingly, at 14°C, lengthening work increased substantially at higher fH, and the duration of lengthening (i.e. diastole) became severely constrained when fH was increased. These data suggest that myocardial contraction/twitch kinetics greatly constrain maximal fH at cool temperatures, and may underlie observations that fish elevate VS to an equal or greater extent than fH to meet demands for increased Q at lower temperatures.

Congenital Posteromedial Bowing of Tibia: Comparison of Early and Late Lengthening.

Congenital posteromedial bowing of tibia (CPMBT), a rare anomaly, is characterized by a decreasing deformity and a gradually increasing limb shortening. Lengthening in CPMBT has not been studied extensively. Our series compares the duration and complications of lengthening in younger versus older children to determine early lengthening safety and benefits. We studied 28 tibial lengthenings performed by a single surgeon in 23 patients, divided into 2 equal groups of 14 segments: group A 5 years or younger (preschool) and group B above 5 years. All were lengthened with circular external fixators, of which 3 were lengthened over a nail. We measured preoperative (bo) and postoperative (po) sagittal, coronal, and oblique plane deformities, initial limb length discrepancy (LLD), percentage LLD (% LLD), amount of lengthening (AmtL), percentage lengthening (%L), external fixator duration (EFD), and external fixator index (EFI). We graded complications by Lascombes' criteria, results by Association for the Study and Application of the Methods of Ilizarov bone score. The mean age was 8.8±7.1 years; the mean follow-up was 7.9 years. Group A had significantly greater bo-sagittal, coronal, and oblique plane deformities. Mean LLD (3.4 cm in group A vs. 4.1 cm in group B) was similar in both. Expected LLD at maturity (LLDM) using the multiplier method was greater than previously reported (mean, range in group A: 7.2 cm, 4.4 to 9.5 cm; group B: 5 cm, 2.5 to 9.7 cm). Though AmtL (3.5 and 4.1 cm) was similar in both, %L was 24% in group A and 15.7% in group B (P=0.002). EFD (116.6 days) and EFI (33.7 days/cm) were lesser in group A compared with group B (200.3 days, P=0.001; 50.2 days/cm, P=0.01). Lascombes' triple contract was fulfilled in 11/14 lengthenings in group A versus 3/14 in group B. Association for the Study and Application of the Methods of Ilizarov bone score was good and excellent in both groups (P=0.44). In a large series of lengthenings in CPMBT, we found younger children presenting with large deformities and large projected length discrepancies could be safely lengthened with significantly lesser EFD and complications than in older children. Level IV-therapeutic study.

How should we lengthen post-traumatic limb defects? a systematic review and comparison of motorized lengthening systems, combined internal and external fixation and external fixation alone.

Various external fixation systems for lower extremity long bone deformities have been used to various degrees of success, while newer mechanical lengthening nail (MLN) systems offer the potential for improved patient outcomes. Proponents of MLNs argue that they reduce the number of operations, infectious complications, and improve quality of life; however, the evidence to support these claims is scant. This systematic review aims to evaluate the optimal lengthening system for treating post-traumatic long bone deformity. The systematic review was conducted in accordance with PRISMA guidelines. PUBMED, EMBASE, CINAHL, and the Cochrane Library were searched for comparative studies of lengthening techniques among adult patients with axial deformities. Studies were screened and data extracted in duplicate. Treatment groups were pooled into external fixation (EF) alone, combined internal and external fixation (CIF), and mechanical lengthening nail (MLN). Outcomes were mean lengthening achieved, lengthening index, and reported complications. Thirteen studies with 725 patients (mean age: 29.6years, 74% male) were included. Nearly all of the studies were either prospective or retrospective cohort studies (n = 12), with one randomized controlled trial of moderate study quality. The mean limb lengthening achieved, lengthening index, and rate of reoperation were similar among the MLN, EF, and CIF groups. The purported decreased the duration of lengthening and the risk of reoperation associated with MLNs was not demonstrated in this review. Patients with post-traumatic leg length deformities remain a challenging patient population to treat, with intervention being associated with high rates of infectious complications and need for revision operations.

Forearm lengthening and prosthetic management in children with transverse congenital forearm deficiency

In cases of transverse congenital forearm deficiency, achieving a good prosthesis fit during childhood remains a challenge. Ulnar lengthening is a treatment option for improving the prosthesis fit. The objective of this study was to evaluate surgical ulnar lengthening and the subsequent prosthesis fit. We reviewed four cases of ulnar lengthening in children with transverse congenital forearm deficiency. The procedure was evaluated in terms of the duration of lengthening, increase in ulnar length and healing index. The elbow range of motion, functional outcome (Prosthetic Upper Extremity Functional Index, PUFI) and time spent using the prosthesis per day were evaluated. The mean age at the time of the lengthening procedure was 3.5 years, the mean duration of lengthening was 58.3 days, the mean length gain was 21 mm, and the mean healing index was 70.1 days/cm. Elbow range of motion was restricted in one patient (100°–140°) and full in the other three patients. Based on the PUFI, 88.4% of activities were performed without the prosthesis. Children only used their prosthesis to perform specific tasks. Given the high complication rate and the lack of prosthesis use during daily activities, the main indication for forearm lengthening is a very short forearm that prevents prosthesis fitting. This procedure should be performed later in life – in adolescence.

Lengthening of the humerus with intramedullary lengthening nails\u2014preliminary report

Distraction osteogenesis of the humerus with fully implantable lengthening is now possible since the diameter of the available nails was reduced to 10 mm and below. We report on the first intramedullary lengthening cases of the humerus with two different lengthening devices (FITBONE and PRECICE). Two different approaches and implantation techniques were used. We retrospectively reviewed clinical and radiographic data and pointed out results, pitfalls and complications of the procedure. Four adult patients with relevant length discrepancy of the humerus were treated with fully implantable systems in two centers between 2012 and 2015. Three patients were treated with FITBONE by an antegrade approach; one patient had lengthening with a PRECICE and a retrograde approach. Average nail lengthening was 55 mm (40–65 mm), and the average duration of lengthening was 70 days (52–95 days). The average distraction index was 0.72 mm/day (range 0.4–1.0 mm/day) or 12.5 days/cm (range 8.0–16.2 days/cm). The average consolidation index was 33.6 days/cm (range 25–45 days/cm). There was an implant failure (arrest) with the PRECICE. After consolidation and exchange with a technically improved implant, the course of treatment was uneventful. In patients with antegrade lengthening shoulder abduction decreased, and in the patient with the retrograde approach it improved but elbow extension decreased marginally. Reduced motion of the adjacent joints can be a major problem in intramedullary lengthening of the humerus. This first case series in the field of a rare indication suggests that lengthening of the humerus by fully implantable lengthening nails might be a valuable alternative to lengthening with external fixation. Main advantage of the PRECICE technology is the possible shortening in-between of lengthening.

Humeral Lengthening with the PRECICE Magnetic Lengthening Nail

Different types of external fixators have been used for humeral lengthening with successful outcomes reported in literature. Motorized intramedullary (IM) lengthening nails have been developed as an alternative to external fixators for long bone lengthening in the lower extremity. This case series reports on using the new technology of IM lengthening nails for humeral lengthening. We assessed the radiological healing and functional outcomes after using the PRECICE IM nail for humeral lengthening. This multicenter retrospective study included a total of six humeri in five patients (mean age was 20years) that underwent lengthening with the magnetic IM PRECICE nail in two centers in the USA. The etiology was humeral growth arrest post-bone cyst (two segments), post-septic growth arrest (two segments), and multiple hereditary exostosis (bilateral segments in one patient). The outcomes measured were the length achieved, distraction index (DI; the length achieved in mm divided by the duration of lengthening in days), consolidation index (CI; number of days from surgery until consolidation divided by the length of the regenerate in cm), complications encountered, and functional outcomes (shoulder and elbow range of motion, the upper extremity functional index (UEFI), and QuickDASH functional scores). The mean follow-up period was 1.8years (0.9 to 2.4years). All segments achieved the goal of lengthening; the mean was 5.1cm (4.5 to 5.8cm). Mean DI was 0.7mm/day (0.5 to 0.8). Mean CI was 36days/cm (25 to 45days/cm). No complications were observed. At the last follow-up, all patients maintained their preoperative range of motion (ROM) except one patient had reduced shoulder ROM. QuickDASH score and upper extremity functional index showed postoperative improvement compared to the preoperative scores. IM lengthening nails can provide successful and safe humeral lengthening. Specifically, the PRECICE nail has accurate control over the lengthening process.

Distraction Osteogenesis is an Effective Method to Lengthen Digits in Congenital Malformations

The aim of this study was to investigate the feasible amount of lengthening by distraction osteogenesis in congenital hand deficiencies. A total of 60 patients (1.6-17.8 years) underwent lengthening of 71 bones between 1994 and 2014. Bone lengthening was performed on 46 metacarpals and 25 phalanges. Mostly the first (n=30) and the fifth (n=21) rays were lengthened. Bone lengthening was performed to treat primarily symbrachydactyly (b=32) and amniotic band syndrome (n=10). To analyze the amount of lengthening preoperative radiographs and radiographs taken while removing the external fixator were compared. The charts were reviewed regarding age at surgery, duration of lengthening, duration of bony consolidation, complication, etc. The average of metacarpal distraction was 18.4 mm=73% lengthening with respect to the preoperative length; the average of phalange distraction was 14.0 mm=77% of the preoperative length. In both, metacarpals and phalanges, a lengthening of > 100% of the preoperative bone length was possible. In target length was reached in 89% of the procedures. The average time for consolidation was 6.1 (1-20) days/mm lengthening. The external fixator was in use on average for 140 (50-346) days. After removing of the external fixator an axial K-wire was used to stabilize the callus in 9 procedure, and an iliac bone craft plus axial K-wire in 11 procedures. The rate of complications was 30% (early consolidation, deviation, joint dislocation, pin infection, tendon dislocation). All complications could be treated without with acceptable results. Metacarpal and phalangeal distraction lengthening is an effective but demanding technique for ray reconstruction in congenital malformations of the hand. It is possible to lengthen a bone by more than 100%. Complications are common, but in most cases easy to handle.

Usefulness of two-dimensional longitudinal strain pattern to predict left ventricular recovery and in-hospital complications after acute anterior myocardial infarction treated successfully by primary angioplasty.

The aim of this study was to test the usefulness of two-dimensional longitudinal strain pattern in segments with wall motion abnormalities to predict left ventricular recovery and in-hospital cardiac events as well as coronary microvascular impairment (CMI) in patients with recent acute anterior myocardial infarction. Forty-nine consecutive patients with acute myocardial infarction (mean age, 59±13years) treated successfully with primary coronary angioplasty prospectively underwent transthoracic Doppler echocardiography 24hours after angioplasty and during follow-up (6months). A two-dimensional strain analysis, including measurement of the duration of systolic lengthening expressed as a percentage of systolic duration (SL % duration), the lengthening-to-shortening ratio, the postsystolic shortening index in segments with wall motion abnormalities, and global longitudinal strain and left anterior descending coronary artery territory strain, was performed. Cardiac events were defined as a composite of death, reinfarction, and heart failure. CMI was assessed noninvasively by transthoracic Doppler left anterior descending coronary artery investigation <24h after angioplasty and was defined as coronary flow velocity reserve<1.7 and/or a no-reflow pattern (mean coronary flow velocity reserve, 1.8±0.6 in the whole group). At the segmental level, SL % duration, lengthening-to-shortening ratio, and postsystolic shortening index were correlated with recovery (defined as normalization of wall motion abnormalities), whereas in multivariate analysis, only SL % duration independently predicted recovery (threshold level, 40%; area under the curve, 0.76; P<.01). At the patient level, in univariate analysis, SL % duration, global longitudinal strain, left anterior descending coronary artery territory strain, and troponin peak were correlated with recovery (defined as an absolute improvement of left ventricular ejection fraction of >5%). In multivariate analysis, SL % duration was independently related to recovery (area under the curve, 0.78; P<.01). Furthermore, SL % duration was independently linked to cardiac events (n=13) and CMI (n=24) (P<.01 for all). In patients with AMI treated by primary angioplasty, two-dimensional strain predicts left ventricular recovery independently of more traditional parameters and is independently linked to cardiac events and CMI.

0139: Usefulness of two-dimensional longitudinal strain pattern to identify viable myocardium and in-hospital cardiac events after acute anterior myocardial infarction

to test the usefulness of two-dimensional longitudinal strain pattern (2DS) in segments with wall motion abnormalities (WMA) to predict left ventricular (LV) recovery and in-hospital cardiac events (CE) after acute anterior myocardial infarction (AMI). 45 consecutive patients (mean age 60±14 years, 40% women) with first AMI treated successfully by primary percutaneous coronary angioplasty underwent prospectively a transthoracic Doppler-echocardiography, 24hours after angioplasty, and during follow-up (3-6 months), including 2DS analysis: duration of systolic lengthening expressed as percentage of systolic duration (SL), lengthening to shortening ratio (L/S), and post-systolic shortening index (PSSi) in segments with WMA using a 18 segment model, as well as global longitudinal strain (GLS) and left anterior descending artery territory strain (LAD-S). At follow-up, recovery was defined at segmental level by normalization of WMA, at patient level by improvement of LVEF ≥10%. CE (n=14) were defined as a composite of death, reinfarction, heart failure, LV apical thrombus. 330 of the 778 segments analyzable had WMA at the acute phase (mean 7.8±1.2 per patient), 153 recovered and 177 did not. At segmental level, SL, L/S, PSSi were correlated to recovery, whereas in multivariate analysis, only SL independently predicted recovery (threshold level 40%, sensitivity 79%, specificity 68%, p < 0. 01, AUC 0.75). At patient level, in univariate analysis, WMSI, LVEF, SL, GLS, LAD-S, and troponin peak were correlated to recovery and to CE. In multivariate analysis, SL was independently related to recovery (≤ 3 segments with SL >40%, Se = 78%, Sp=78%, p< 0.001, AUC 0.83), and to CE (with LAD-S) (all, p < 0.05). In patients with AMI treated by primary angioplasty, 2DS predict viability as well as CE independently of more traditional parameters.

Identification of Viable Myocardium in Acute Anterior Infarction Using Duration of Systolic Lengthening by Tissue Doppler Strain: A Preliminary Study

The aim of this study was to investigate whether strain Doppler echocardiography before reperfusion therapy could quantify ischemic dysfunction and predict viable myocardium in acute myocardial infarction as determined by magnetic resonance imaging. Twenty-six patients (mean age, 60 ± 12 years; seven women) with acute myocardial infarctions who underwent acute percutaneous coronary intervention were examined using strain Doppler echocardiography immediately before the procedure. Percutaneous coronary intervention was performed 296 ± 122 min after the onset of pain. Peak left ventricular systolic longitudinal strain and the duration of systolic lengthening were analyzed. Magnetic resonance imaging was performed 11 ± 5 months after therapy. Scarring exceeding 50% of the segment area was considered nonviable. Peak systolic strain fell gradually (becoming less negative) from normal segments to segments with transmural infarction (P < .0001), and the duration of systolic lengthening increased (P < .0001). Myocardial scarring was closely correlated with peak systolic strain (R = 0.76, P < .00001) and the duration of systolic lengthening (R = 0.88, P < .00001). There was a significant correlation between the degree of scarring and time to percutaneous coronary intervention (R = 0.40, P = .045). In segments with systolic lengthening, the improvement in strain after remodeling was significantly higher (5.5 ± 5.1%) than in segments with duration of systolic lengthening > 67% of systole (2.2 ± 3.7%) (P < .001). Receiver operating characteristic curve analyses showed that duration of systolic lengthening > 67.3% could identify nonviable myocardium (sensitivity, 90%; specificity, 94%). In patients with acute myocardial infarctions in the anterior wall, strain measurements can identify myocardium with nontransmural scarring. The duration of systolic lengthening is a novel, easily implemented variable that may identify ischemic but viable myocardium. Myocardial infarctions in other left ventricular regions should be investigated in future studies.

Abstract 1878: Improved Detection of Viable Myocardium by a Novel Strain Doppler Measure in Patients with Acute Myocardial Infarction

BACKGROUND: Detection of viable myocardium is vital for treatment strategy during acute myocardial infarction (AMI). The aim was to study if strain Doppler echocardiography (SDE) prior to reperfusion therapy could predict viable myocardium in AMI as determined by cardiac magnetic resonance imaging (CMR). METHODS: Twenty-five patients (58 ± 12 years, 7 women) with AMI who underwent percutaneous coronary intervention (PCI) were examined by SDE immediately prior to PCI. End-systolic longitudinal strain and duration of systolic lengthening was analyzed in 16 left ventricular segments. CMR was performed 11 ± 4 months after reperfusion therapy. Scars exceeding 50% of the segment was considered non-viable. RESULTS: Duration of systolic lengthening in non-viable myocardial segments was 249 ± 135 ms compared to 39 ± 86 ms in viable segments (p&lt;0.0001), with a direct relationship to scar transmurality (r=0.89, p&lt;0.0001). A duration of systolic lengthening longer than 67.3% (~2/3) of systole (Figure ) detected non-viable myocardium by a sensitivity of 90% and a specificity of 93%. Strain demonstrated end-systolic shortening (−15 ± 6%) in viable segments in contrast to lengthening in non-viable segments (3 ± 4%, p&lt;0.0001). End-systolic strain correlated also with the scar transmurality (r=0.71, p&lt;0.0001). CONCLUSION: SDE performed before reperfusion therapy in AMI can identify viable myocardium. Duration of systolic lengthening which is a novel parameter might prove to be a superior measure for predicting recovery of myocardial function.

Duration of orthodontic treatment and mandibular lengthening by means of distraction or bilateral sagittal split osteotomy in patients with angle class II malocclusions

The purpose of this study was to investigate the duration of treatment of patients with skeletal Angle Class II malocclusions treated with orthodontic appliances and surgical lengthening of the mandible to close residual overjets. In this retrospective study, the patients were divided into 3 groups. Group A consisted of 10 patients (5 boys, 5 girls; mean age, 10.11 years; range, 9.1-13.9 years at the beginning of treatment) who were treated with a headgear-activator, fixed appliances, and intraoral osteodistraction of the mandible. Group B consisted of 19 patients (10 boys, 9 girls; mean age, 12.3 years; range, 9.6-16.1 years) treated with fixed appliances and intraoral distraction. In group C, 13 patients (4 men, 9 women; mean age, 27.3 years; range, 12.11-40.7 years) were treated with fixed appliances and bilateral sagittal split osteotomy (BSSO). In patients treated with orthodontic appliances and surgical lengthening of the mandible, treatment time was influenced by the appliances and the surgical technique used. Patients treated with a headgear-activator, fixed appliances, and intraoral distraction osteogenesis (group A) needed significantly more treatment time than patients treated with fixed orthodontic appliances and intraoral distraction (group B) or fixed appliances and BSSO (group C). Duration of treatment with intraoral mandibular distraction (group B) was significantly (P < .05) shorter compared with mandibular lengthening with BSSO (group C). However, no definitive conclusions can be drawn, because of the retrospective study design. The best time and the best surgical procedure for correcting mandibular length have yet to be determined, and a prospective randomized trial is recommended.

Optimum take-off techniques and muscle design for long jump.

A two-segment model based on Alexander (1990; Phil. Trans. R. Soc. Lond. B 329, 3-10) was used to investigate the action of knee extensor muscles during long jumps. A more realistic representation of the muscle and tendon properties than implemented previously was necessary to demonstrate the advantages of eccentric force enhancement and non-linear tendon properties. During the take-off phase of the long jump, highly stretched leg extensor muscles are able to generate the required vertical momentum. Thereby, serially arranged elastic structures may increase the duration of muscle lengthening and dissipative operation, resulting in an enhanced force generation of the muscle-tendon complex. To obtain maximum performance, athletes run at maximum speed and have a net loss in mechanical energy during the take-off phase. The positive work done by the concentrically operating muscle is clearly less than the work done by the surrounding system on the muscle during the eccentric phase. Jumping performance was insensitive to changes in tendon compliance and muscle speed, but was greatly influenced by muscle strength and eccentric force enhancement. In agreement with a variety of experimental jumping performances, the optimal jumping technique (angle of attack) was insensitive to the approach speed and to muscle properties (muscle mass, the ratio of muscle fibre to tendon cross-sectional area, relative length of fibres and tendon). The muscle properties also restrict the predicted range of the angle of the velocity vector at take-off.

Relaxation is impaired in the diaphragm muscle of the cardiomyopathic Syrian hamster.

Relaxation was examined in diaphragm muscle strips of cardiomyopathic Syrian hamsters and control hamsters. Isotonic lengthening velocity and isometric tension decay were analyzed over the load continuum in response to twitch. For each load level (P), we measured the maximum extent of shortening (deltaL), the peak lengthening velocity (VL), and the peak rate of tension decline (-dP/dtmax). The kinetics of sarcomere length (SL) were simultaneously measured by laser diffraction. In an attempt to account for the influence of shortening and/or load on relaxation, we calculated the slopes of the VL - deltaL and -dP/dtmax - P relationships. In both groups, there was a direct relationship between (1) VL and deltaL and (2) -dP/dtmax and P. In myopathic hamsters, we observed a decrease in the slope of the VL - deltaL relationship (p < 0.05), a decrease in VL at any common value of both muscle and sarcomere extent of shortening, and an increase in the duration of overall lengthening. Isometric tension decay was significantly prolonged in myopathic muscle strips, while the -dP/dtmax - P relationship was not significantly different than in controls. At low-to-medium loads, SLs at the onset of tension decline were greater in myopathy. These data indicate that relaxation of the diaphragm was both slowed and prolonged in myopathic Syrian hamsters.

The Ilizarov method for correction of complex deformities. Psychological and functional outcomes.

We reviewed the psychological profile and functional ability of forty-five children (fifty-two extremities) who had had correction of deformities of the lower extremities with the Ilizarov method. Psychological changes were evaluated with the Post-Hospitalization Behavior Questionnaire and the Children's Depression Inventory, and the functional status was measured with the Children Health Information Service Rand Scale. The over-all satisfaction of the patient with regard to the outcome of the operation was assessed as well. The operations were performed between 1988 and 1992. The average age at the time of the operation was twelve years (range, three to eighteen years), and the average duration of follow-up was thirty-six months (range, twenty-four to seventy-two months). The lengthening index, duration of lengthening, and average number of complications were similar to those reported in other studies. All of the children had a normal psychological score, forty-two had no limitations in daily activities, and thirty-seven were satisfied with the over-all result.

Leg muscle activation during gait in Parkinson's disease: adaptation and interlimb coordination

Adaptation in leg muscle activity and coordination between lower limbs were studied during walking on a treadmill with split belts in one group of parkinsonian patients and one of age-matched healthy subjects. Four different belt speeds (0.25/0.5/0.75/1.0 m/sec) were applied in selected combinations to the left and right leg. While these walking conditions were easily tolerated by the healthy subjects, the parkinsonian patients usually reached the limits of their walking capabilities. Both groups adapted automatically to a change in belt speed within approximately 20 stride cycles. Healthy subjects adapted by reorganizing their stride cycle with a relative shortening of duration of support and lengthening of the swing phase of the “fast” leg and vice versa on the “slow” leg. The patients showed a restricted range of stride frequencies for the. various belt speeds during normal and split-belt walking with consequent deviations in the reorganization of the stride cycle. In both healthy subjects and patients, ipsilateral gastrocnemius and contralateral tibialis anterior electromyographic (EMG) activity increased predominantly with an ipsilateral increase in belt speed. Two main differences were observed in the EMG patterns: (1) In the patients leg muscle EMG activity was less modulated and gastrocnemius EMG amplitude was small during normal and split-belt walking. However, there was no significant difference between the two groups in respect to the reorganization of the EMG pattern required for the various split-belt walking conditions. (2) The amount of co-activation of antagonistic leg muscles during the support phase of the stride cycle was greater in the patients compared to the healthy subjects during normal and split-belt walking. It is suggested that reduced EMG modulation and recruitment in the leg extensors may contribute to the impaired walking of the patients. This in turn is a result of an irepaired proprioceptive feedback from extensor load receptors. This defective control is partially compensated for in parkinsonian patients by a greater amount of leg flexor activation which leads to a higher degree of co-activation. Visual input plays a role in the control of this increased activation.

Vapor-grown carbon fibers from benzene pyrolysis

Carbon fibers were grown on alumina substrates by vapor phase decomposition of benzene in the presence of hydrogen in a tubular reactor. The effect of lengthening duration and temperature on the average fiber length was studied at two different benzene concentrations (13.2 and 18.6 mol%). In the temperature range (1283–1353 K) investigated, the maximum average fiber length increased with an increase in temperature. At a constant temperature, the average fiber length initially increased with duration of lengthening, and finally reached an asymptotic value. The fiber lengths were unaffected by thickening. A two-parameter model can satisfactorily explain the observed variation in average fiber length with duration of lengthening.