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Charcot-Marie-Tooth disease (CMT) can cause progressive muscle weakness and contracture, leading to gait abnormalities such as increased and delayed peak ankle dorsiflexion and reduced ankle power generation in terminal stance. Understanding strength loss on ankle function during gait is important for interpreting treatment outcomes and evaluating new therapies designed to improve gait. Do ankle kinematics and kinetics vary as a function of age, disease progression with associated loss of muscle strength and CMT type in youth with CMT types 1 and 2? A prospective convenience sample of 45 participants with CMT1 and 2, ages 7–22 years, underwent comprehensive gait analysis. Seventeen patients underwent repeat analyses totaling 67 tests. Generalized mixed effects linear modeling was used to compare CMT1 versus CMT2 and to examine the effects of age on ankle strength, range of motion, kinematics, and kinetics within each CMT type. Plantarflexor and dorsiflexor strength were less in CMT2 compared with CMT1 (p ≤ 0.05), while peak dorsiflexion in terminal stance (TST) was greater (p = 0.02). Peak plantarflexion moment and power generation were also less in CMT2 (p ≤ 0.02). In CMT1, peak dorsiflexion in TST increased with age through 13 years (p = 0.004); then plateaued in the normal range (p = 0.73). Peak ankle angle in mid-swing was closely related to the angle in TST (p < 0.001) following a similar pattern with age. In CMT2, no significant associations were observed between age, peak dorsiflexion in TST, and peak ankle angle in mid-swing (p ≥ 0.19). There were no consistent trends with age for individual patients with repeat tests. The heterogeneity of joint level impairments and gait kinematics and kinetics point to the importance of having an in-depth understanding of gait at the individual patient level using comprehensive gait analysis including valid and reliable strength measures. • In CMT1 peak dorsiflexion in terminal stance (TST) increased through age 13. • In CMT1 peak dorsiflexion in TST plateaued in the normal range after 13. • In CMT1 peak ankle angle in mid-swing was closely related to the angle in TST. • In CMT2 there was no significant association of ankle function with age. • Heterogeneity in gait highlights the need to understand patient-specific gait changes. [ABSTRACT FROM AUTHOR]

Background: Charcot-Marie-Tooth disease (CMT) results in muscle weakness and contracture leading to a wide variety of gait issues including atypical ankle kinematics in both stance and swing. Knowledge of the stance and swing phase kinematic patterns for CMT type 1 (CMT1), the most common CMT type, will improve our understanding of expected gait outcomes and treatment needs to improve gait function.Research Question: What are the stance/swing phase ankle phenotypes in CMT1?Methods: A prospective convenience sample of 25 participants with CMT1, ages 7-19 years, underwent comprehensive gait analysis following standard procedures. Ankle phenotypes based on peak ankle dorsiflexion in terminal stance and mid-swing were defined and compared using linear mixed models.Results: Patients with CMT1 presented with three stance phase ankle phenotypes: 21 limbs (42 %) with reduced (mean 5°, SD 2°), 19 limbs (38 %) with typical (mean 11°, SD 1°) and 10 limbs (20 %) with excessive (mean 15°, SD 2°) peak dorsiflexion in terminal stance (p < 0.05). There were two swing phase phenotypes: 19 limbs (38 %) with typical (mean -1.7°, SD 1.5°) and 31 limbs (62 %) with excessive (mean -5.6°, SD 1.4°) plantarflexion in mid-swing (p < 0.002). Eleven patients (44 %) had ankles that were classified into different stance groups, and 9 patients (36 %) had ankles that were classified into different swing groups. The most common combination of stance/swing ankle phenotypes was decreased dorsiflexion in terminal stance with increased plantarflexion in mid-swing (16 sides, 32 %).Significance: This study shows that youth with CMT1 have multiple combinations of combined ankle kinematics for stance and swing. The ankle phenotypes identified in this study reflect contributions of both dorsi/plantarflexor weakness and plantarflexor contracture, which require different treatment approaches. Comprehensive gait analysis can distinguish between multiple ankle phenotypes to assist in determining the most appropriate treatment to improve gait for individual patients. [ABSTRACT FROM AUTHOR]

Background: The purpose of this study was to determine the differences in billable provider charges between single event multilevel surgery (SEMLS) based on comprehensive gait analysis and a staged surgical approach (SSA) without comprehensive gait analysis for the orthopedic treatment of ambulatory children with cerebral palsy (CP).Methods: The charges associated with nine common orthopedic surgical combinations (both unilateral and bilateral, soft tissue or soft tissue plus bony) for children with CP were determined and compared between SEMLS and SSA. The charges included surgical, anesthesia, operating room, recovery room, hospital stay, physical therapy, and, for SEMLS only, comprehensive computerized gait analysis.Results: Total charges to complete each combination was higher for SSA than for SEMLS. The differential ranged from $10,247 to $75,069 with the percentage difference ranging from 20% to 47%. The mean difference was $43,606 (p = 0.0002). The dollar difference (r = 0.98, p < 0.0001) and percentage difference (r = 0.79, p = 0.01) were both related to the total charge of the SEMLS surgery.Significance: Financial costs are lower for SEMLS vs. SSA for the treatment of multilevel gait issues in children with CP. The cost of gait analysis is much smaller than the cost differential between SEMLS and SSA. Although some patients who have SEMLS may need additional orthopedic surgery with associated costs, this is also possible for SSA. Therefore, due to the many benefits of SEMLS, which also include more informed treatment decision-making as well as reduced time away from school and work (for caregivers), SEMLS guided by gait analysis is recommended over SSA for the treatment of gait disorders in children with CP. [ABSTRACT FROM AUTHOR]

Background: Charcot-Marie-Tooth disease (CMT) results in distal muscle weakness that leads to gait difficulties in both the stance and swing phases, thus limiting function in the community. A primary purpose of ankle foot orthoses (AFOs) is to improve gait function; however, little is known about what AFOs are prescribed and how they benefit children with CMT.Research Question: To determine the impact of previously prescribed AFOs on gait in children with CMT using comprehensive gait analysis techniques.Methods: We examined strength, passive range of motion and gait (kinematics, kinetics and temporal-spatial) for barefoot and AFO walking on 15 children with a diagnosis of CMT. Participants used their prescribed AFOs, the design of which varied depending on the patient. Comparisons between barefoot and AFO walking were completed for selected ankle, knee and hip kinematics and kinetics and temporal-spatial parameters. Subgroups were also evaluated based upon specific ankle kinematics relevant to AFO prescription.Results: AFOs resulted in increased walking velocity (0.91, SD 0.31 to 1.13, SD 0.23 m/sec, p = 0.001) and improved ankle kinematics (dorsiflexion in mid-swing: -11, SD 10 to 0, SD 5 degrees, p = 0.0001) and kinetics (peak plantar flexor moment in stance: 0.71, SD 0.30 to 0.85, SD 0.29 Nm/kg, p = 0.001). In patients with increased equinus in swing, AFOs resulted in improved ankle kinematics. In patients with increased dorsiflexion in terminal stance, AFOs did not provide the support that was needed to improve gait function.Significance: AFOs enhance gait function in children with CMT by improving walking velocity and selected ankle kinematics and kinetics. It is important that the AFO design be aligned with the patient's specific joint level impairment and associated gait dysfunction. Comprehensive gait analysis techniques can measure differences between barefoot and AFO function and help to clarify the most appropriate AFO prescription for an individual child. [ABSTRACT FROM AUTHOR]

• Children with Charcot-Marie-Tooth walk more slowly than their age-matched peers. • Deficits in walking velocity increase with age. • Deficits in walking velocity start younger in Type 2 versus Type 1. • Deficits in walking velocity are due to reduced stride length. • To improve walking velocity treatment should target increasing stride length. The purpose of this study is to assess how Charcot-Marie-Tooth disease, a group of inherited peripheral neuropathies that result in distal weakness, affects walking velocity over time in comparison to age-matched controls. Comprehensive gait analysis of 57 children (mean age 12.0, SD 3.7 years) compared to 76 age-matched controls (mean age 10.1, SD 3.4 years) demonstrated slower walking velocity (p <0.001) due to both shorter stride length (p <0.001) and diminished cadence (p =0.01). There was higher walking velocity (p <0.001), stride length (p =0.002) and cadence (p <0.001) in patients with dorsiflexor strength ≥3 and higher walking velocity (p =0.001) and cadence (p =0.03) in patients plantar flexor strength ≥4. Analysis of Charcot-Marie-Tooth type 1 and type 2 subgroups showed that walking velocity increased significantly with age in controls (p =0.001) but did not increase in children with either subtype (p >0.54). Stride length increased significantly with age in all groups (p <0.001) but at a slower rate in type 1 and 2 compared to controls. These differences contributed to increasing deficits in walking velocity and stride length with age in type 1 and 2 in comparison to controls, with deficits appearing earlier in type 2. Since the slower walking velocity in children with Charcot-Marie-Tooth disease is primarily due to short stride length, treatments that enable improved stride length, such as plantar flexor strengthening and bracing, may improve walking velocity and associated gait function. [ABSTRACT FROM AUTHOR]

Background: Gait analysis provides quantitative data that can be used to supplement standard clinical evaluation in identifying and understanding gait problems. It has been established that gait analysis changes treatment decision making for children with cerebral palsy, but this has not yet been studied in other diagnoses such as spina bifida.Research Question: To determine the effects of gait analysis data on pathology identification and surgical recommendations in children with spina bifida.Methods: Two pediatric orthopaedic surgeons and two therapists with >10 years of experience in gait analysis reviewed clinical, video, and gait analysis data from 43 ambulatory children with spina bifida (25 male; mean age 11.7 years, SD 3.8; 25 sacral, 18 lumbar). Primary gait pathologies were identified by each assessor both before and after consideration of the gait analysis data. Surgical recommendations were also recorded by the surgeons before and after consideration of the gait analysis data. Frequencies of pathology and surgery identification with and without gait analysis were compared using Fisher's exact test, and percent change in pathology and surgery identification was calculated.Results: Pathology identification often changed for common gait problems including crouch (28% of cases), tibial rotation (35%), pes valgus (18%), excessive hip flexion (70%), and abnormal femur rotation (75%). Recognition of excessive hip flexion and abnormal femur rotation increased significantly after consideration of gait analysis data (p < 0.05). Surgical recommendations also frequently changed for the most common surgeries including tibial derotation osteotomy (30%), antero-lateral release (22%), plantar fascia release (33%), knee capsulotomy (25%), 1st metatarsal osteotomy (60%), and femoral derotation osteotomy (89%). At the patient level, consideration of gait analysis data altered surgical recommendations for 44% of patients.Significance: Since gait analysis data often changes pathology identification and surgical recommendations, treatment decision making may be improved by including gait analysis in the patient care process. [ABSTRACT FROM AUTHOR]

External femoral derotation osteotomy (FDO) is an orthopaedic intervention to correct increased femoral anteversion and associated excessive internal hip rotation and internal foot progression during gait in children with cerebral palsy. The resulting functional issues may include clearance problems and hip abductor lever-arm dysfunction. The purpose of this study was to evaluate long-term gait outcomes of FDO. Twenty ambulatory patients (27 sides) with cerebral palsy who underwent pre-operative (P0) and a one year post-operative (P1) gait analysis as part of the standard of care had a second post-operative analysis (P2) approximately 11 years post-surgical intervention. Mean hip rotation in stance showed statistically significant decreases in internal rotation at P1 post-surgical intervention that were maintained long-term (mean hip rotation P0: 21±9, P1: 0±9 and P2: 6±12 degrees internal). Similar results were seen with mean foot progression (P0: 9±16 degrees internal, P1: 14±13 degrees external, P2: 13±16 degrees external). However, 2/27 sides (9%) showed a recurrence of internal hip rotation of >15° at the 11year follow-up. The reasons for this recurrence could include age, surgical location and ongoing disease process all of which need to be further examined. We conclude that FDO can show long-term kinematic and functional benefits when performed in the prepubescent child with cerebral palsy in comparison to the natural progression of of hip rotation in cerebral palsy. [ABSTRACT FROM AUTHOR]

Aim: This study aims to achieve an international expert consensus on joint patterns during gait for children with cerebral palsy (CP) by means of Delphi surveys.Method: In Stage 1, seven local experts drafted a preliminary proposal of kinematic patterns for each lower limb joint in the sagittal, coronal, and transverse plane. In Stage 2, 13 experts from eight gait laboratories (four in the USA and four in Europe), participated in a Delphi consensus study. Consensus was defined by a pre-set cut-off point of 75% agreement among participants.Results: After the first stage, 44 joint patterns were presented in a first survey and 29 patterns reached consensus. Consensus improved to 47 out of 48 patterns in the third survey. Only one pattern, 'abnormal knee pattern during loading response', did not reach consensus. The expert panel agreed to define six patterns for the knee during swing, most of them representing characteristics of a stiff knee pattern.Interpretation: The defined joint patterns can support clinical reasoning for children with CP as joint patterns during gait might be linked to different treatment approaches. Automating the classification process and incorporating additional trunk, foot, and electromyography features should be prioritized for the near future. [ABSTRACT FROM AUTHOR]

Aim The aim of this study was to examine differences in gait kinematics and spatiotemporal parameters in ambulatory children and adolescents with bilateral spastic cerebral palsy ( BSCP) among Gross Motor Function Classification System ( GMFCS) levels I-III. Method A retrospective review was conducted of individuals with BSCP who had three-dimensional motion analysis (3 DGA) at one of seven pediatric hospitals. Means and standard deviations of each gait parameter were stratified by GMFCS levels (I-III) and for a typically developing comparison group. Results Data from 292 children and adolescents with BSCP (189 males, 103 females; mean age 13y) were compared to a typically developing comparison group (24 male, 26 female; mean age 10y 6mo). Gait patterns differed from typically developing in all GMFCS levels, with increasing deviation as GMFCS level increased in 21 out of 28 parameters. Despite significant differences in selected mean kinematic parameters among GMFCS levels such as knee angle at initial contact of 24°, 29°, and 41° in GMFCS levels I, II and III respectively, there was also substantial overlap among GMFCS levels. Interpretation GMFCS levels cannot be identified using specific gait kinematics. Treatment decisions should be guided by comprehensive 3DGA that allows measurement of gait impairments at the joint level for each individual. [ABSTRACT FROM AUTHOR]

Background/aims: Multilevel surgical intervention is a common approach for the correction of gait abnormalities in children with cerebral palsy (CP). The short-term outcomes for the combination of rectus femoris transfer, hamstring lengthening and gastrocnemius lengthening have been well documented using three-dimensional motion analysis. However, the impact of time, growth, and puberty on these short-term outcomes of this combination of procedures is not well understood. The purpose of this study was to evaluate the long-term outcomes of these procedures on gait in patients with CP.Methods: Twenty-two patients underwent rectus femoris transfers, medial hamstring lengthenings and gastrocnemius lengthenings in combination with a selection of other soft tissue and/or bony procedures of the lower limb. All patients had a pre-operative motion analysis and post-operative analysis one and 11 years following surgery.Results: Significant changes in both clinical and gait variables from pre to 1 year post surgery confirmed the short-term gait benefits of this combination of surgical procedures. Long-term follow-up data indicated that the passive range of motion gains noted 1 year after surgery were lost at the knee and ankle. However, the improvements in ankle dorsiflexion and knee extension at initial contact were maintained over 11 years. As well, peak ankle dorsiflexion in stance was maintained and peak ankle plantar flexor moments and powers did not show declines long-term. Peak knee flexion showed a decline over the long-term, however, the timing of peak knee flexion in swing was maintained.Conclusion: When compared to declines in gait kinematics in persons with CP without surgery, these results demonstrate the possible long-term benefits of surgical intervention. [ABSTRACT FROM AUTHOR]

Highlights: [•] Ankle kinematics and kinetics and clinical exam parameters vary in adolescents with CMT. [•] Three ankle kinematic patterns based on peak dorsiflexion in terminal stance. [•] Patterns included: increased, within typical range and reduced peak dorsiflexion. [•] Clinical findings: most common is plantar flexor weakness, cavus, and possible plantar flexor contracture. [•] Understanding of kinematics and impairments needed for treatment decisions. [Copyright &y& Elsevier]

Abstract: The purpose of this study was to determine the effects of orthopedic procedures performed after skeletal maturity on ambulatory patients with cerebral palsy. Twenty-five patients (46 sides) had pre- and postoperative computerized gait analysis. All patients underwent any one or a combination of the following procedures: hamstring lengthenings, ankle plantar flexor lengthenings, rectus femoris transfers, psoas lengthenings, and femoral derotation osteotomies. Surgical results were similar in this group of older patients to those for younger individuals with cerebral palsy. Surgical procedures were evaluated pre- versus postoperatively within the subgroups of patients that had a particular procedure. Patients experienced the following results 1 year postoperatively: (1) improved knee extension at initial contact following hamstring lengthenings (n =35 sides, preop=32±15°, postop=22±13°, p <0.01), (2) improved peak dorsiflexion in swing (n =23 sides, preop=−1±9°, postop=6±8°, p <0.01) and improved modulation with peak dorsiflexion occurring later in stance (preop=31±15% of gait cycle, postop=43±13% of gait cycle, p <0.01) following ankle plantar flexor lengthenings, (3) improved hip rotation following femoral derotational osteotomies (n =9 sides, preop=19±12° internal, postop=0±12°, p <0.01), (4) improved peak knee flexion in swing following rectus femoris transfers (n =23 sides, preop=47±11°, postop=55±13°, p =0.01), (5) a reduction in excessive hip flexion during terminal stance was found in those patients with psoas lengthening (n =8 sides, preop=18±21°, postop=9±19°, p =0.04). [Copyright &y& Elsevier]

Abstract: Stiff-knee gait is a movement abnormality in which knee flexion during swing phase is significantly diminished. This study investigates the relationships between knee flexion velocity at toe-off, joint moments during swing phase and double support, and improvements in stiff-knee gait following rectus femoris transfer surgery in subjects with cerebral palsy. Forty subjects who underwent a rectus femoris transfer were categorized as “stiff” or “not-stiff” preoperatively based on kinematic measures of knee motion during walking. Subjects classified as stiff were further categorized as having “good” or “poor” outcomes based on whether their swing-phase knee flexion improved substantially after surgery. We hypothesized that subjects with stiff-knee gait would exhibit abnormal joint moments in swing phase and/or diminished knee flexion velocity at toe-off, and that subjects with diminished knee flexion velocity at toe-off would exhibit abnormal joint moments during double support. We further hypothesized that subjects classified as having a good outcome would exhibit postoperative improvements in these factors. Subjects classified as stiff tended to exhibit abnormally low knee flexion velocities at toe-off () and excessive knee extension moments during double support (). Subjects in the good outcome group on average showed substantial improvement in these factors postoperatively. All eight subjects in this group walked with normal knee flexion velocity at toe-off postoperatively and only two walked with excessive knee extension moments in double support. By contrast, all 10 of the poor outcome subjects walked with low knee flexion velocity at toe-off postoperatively and seven walked with excessive knee extension moments in double support. Our analyses suggest that improvements in stiff-knee gait are associated with sufficient increases in knee flexion velocity at toe-off and corresponding decreases in excessive knee extension moments during double support. Therefore, while stiff-knee gait manifests during the swing phase of the gait cycle, it may be caused by abnormal muscle activity during stance. [Copyright &y& Elsevier]

In the last fifteen years, a new paradigm has emerged for orthopaedic clinical decision-making to optimize the walking ability of children with cerebral palsy. This paradigm is based on the biomechanics of normal gait, pathologic gait and gait disruptions associated with distinct clinical disease processes as well as on a greater understanding of the anatomy and physiology of the muscle-tendon unit and the importance of skeletal alignment. Investigation of the anatomy and physiology of the muscle-tendon unit has revealed numerous variables that can influence the unit"s ability to generate a moment about a joint during the gait cycle. These variables include aspects of myoarchitecture such as muscle mass, fiber length and pennation angle which are used to determine the physiological cross-sectional area.

The diminished knee flexion associated with stiff-knee gait, a movement abnormality commonly observed in persons with cerebral palsy, is thought to be caused by an over-active rectus femoris muscle producing an excessive knee extension moment during the swing phase of gait. As a result, treatment for stiff-knee gait is aimed at altering swing-phase muscle function. Unfortunately, this treatment strategy does not consistently result in improved knee flexion. We believe this is because multiple factors contribute to stiff-knee gait. Specifically, we hypothesize that many individuals with stiff-knee gait exhibit diminished knee flexion not because they have an excessive knee extension moment during swing, but because they walk with insufficient knee flexion velocity at toe-off. We measured the knee flexion velocity at toe-off and computed the average knee extension moment from toe-off to peak flexion in 17 subjects (18 limbs) with stiff-knee gait and 15 subjects (15 limbs) without movement abnormalities. We used forward dynamic simulation to determine how adjusting each stiff-knee subject''s knee flexion velocity at toe-off to normal levels would affect knee flexion during swing. We found that only one of the 18 stiff-knee limbs exhibited an average knee extension moment from toe-off to peak flexion that was larger than normal. However, 15 of the 18 limbs exhibited a knee flexion velocity at toe-off that was below normal. Simulating an increase in the knee flexion velocity at toe-off to normal levels resulted in a normal or greater than normal range of knee flexion for each of these limbs. These results suggest that the diminished knee flexion of many persons with stiff-knee gait may be caused by abnormally low knee flexion velocity at toe-off as opposed to excessive knee extension moments during swing. [Copyright &y& Elsevier]

Background: Increased knee flexion at initial contact and in stance is a common problem for children with cerebral palsy. Surgical correction with percutaneous hamstring lengthening is an alternative to open hamstring lengthening; however, outcomes are less well documented, and there is concern about increasing anterior pelvic tilt. The purpose of this study was to evaluate the short-term outcomes of percutaneous hamstring lengthenings in children with cerebral palsy using comprehensive gait analysis techniques.Research Question: Does percutaneous hamstring lengthening improve knee function, and do knee and anterior pelvic tilt outcomes vary by GMFCS level?Methods: A convenience sample of 52 patients with both pre and post-surgical gait analyses was evaluated retrospectively for changes in gait function in terms of temporal-spatial parameters, kinematics and kinetics. Patients were divided into two GMFCS subgroups: GMFCS level I/II and III.Results: The percutaneous hamstring lengthening results in statistically significant improvements in knee function during gait with increased knee extension at initial contact (mean 32° SD 13° to mean 21° SD 11°, p = 0.000) and improved mean knee flexion in stance (mean 23° SD 12° to mean 16° SD 11°, p = 0.000) for the total study cohort. Beneficial changes were found for knee function in both GMFCS level subgroups; however, there was an increase in pelvic tilt pre to post-surgery in the GMFCS level III subgroup (mean 21° SD 8° to mean 26° SD 6°, p = 0.012) but not the GMFCS level I/II subgroup (mean 18° SD 7° to mean 20° SD 8°, p = 0.427).Significance: Percutaneous hamstring lengthening can improve knee function for all patients; however, the impact on anterior pelvic tilt varies by GMFCS level, with increasing anterior tilt for GMFCS level III only. This study highlights the importance of understanding differences in surgical outcomes by GMFCS level to better predict post-surgical function. [ABSTRACT FROM AUTHOR]

The drop vertical jump (DVJ) is commonly used in return-to-play evaluations to assess movement quality and risk during a dynamic task. However, across biomechanics literature, a multitude of DVJ variations have been used, influencing the generalizability and potential interpretation of the reported findings. The purpose of this study was to identify differences in lower extremity kinematics and kinetics between DVJ variations that differ based on horizontal jump distance, verbal instructions, and the use of a jump target. A single-group repeated measures design was used in a laboratory setting. Twenty participants were tested, and three-dimensional angles and moments of the pelvis, hip, knee, and ankle were computed. Wilcoxon signed rank tests were performed to determine differences between DVJ variations. Reduced knee flexion at initial contact and greater knee extensor moments across the descent phase were observed with increased horizontal jump distance. Additionally, both verbal instructions and a jump target influenced movement strategies at the pelvis, hip, and knee. Ground reaction forces were found to be similar across conditions and jump height following the first landing increased with a target. Although subtle, the biomechanical differences observed between task variations emphasize the importance of standardizing motion analysis protocols for research and clinical decision-making. Given the findings of the current study, the authors recommend using the Half Height variation in patients treated for a knee injury as it will likely be the most indicative of movement quality. • Greater horizontal jump distance led to reduced knee flexion at initial contact. • Greater knee extensor moments across descent were found with further jump distance. • Verbal instructions and a jump target altered pelvis, hip, and knee mechanics. • Jump height following the first landing increased with the use of a jump target. • Motion analysis protocols for clinical / research assessments must be standardized. [ABSTRACT FROM AUTHOR]

This commentary is on the original article by Schwartz et al. on pages 1139–1145 of this issue. [ABSTRACT FROM AUTHOR]

Limb asymmetry is an important consideration when evaluating rehabilitation progress or re-injury risk. The drop vertical jump (DVJ) task is commonly used to assess landing mechanics; however, the extent to which task setup influences limb asymmetry is unknown. Our purpose was to examine limb asymmetries across DVJ variations. We hypothesized that more demanding variations involving greater jump distance and target use would elicit greater landing asymmetries. Participants performed six DVJ variations while lower extremity joint kinematics and kinetics were collected. Joint angles and internal moments of the hip, knee and ankle were computed at initial contact and over the decent phase of the initial landing. The horizontal jump distance and the verbal instructions provided on how to jump off the box influenced limb asymmetries. The DVJ variation without a horizontal jump distance resulted in significant differences at the hip and knee; specifically, greater hip and knee flexion asymmetry (7.0° and 15.2° differences, respectively) were observed between limbs at initial contact. Instructions restricting take-off and landing strategies reduced asymmetry; this indicates that verbal instructions are critical to avoid altering natural landing mechanics. To best utilize DVJ as a tool, study protocols should be standardized to allow for more generalizable research and clinical findings. [ABSTRACT FROM AUTHOR]

This commentary is on the original article by Wren et al. on pages 919–925 of this issue. [ABSTRACT FROM AUTHOR]

Background: The step-down tap (SDT) is a commonly used task to assess unilateral neuromuscular control and to identify deficient movement patterns of the trunk and lower extremities. However, instruction of the SDT varies greatly in recent reports, which may alter the clinical interpretation of potential movement deficiencies.Research Question: The purpose of this study was to identify differences in trunk and lower extremity kinematics between variations of a step-down tap that differ based on step direction, fixing the arms or stance foot, and trial collection methods.Methods: This study followed a single-group repeated measures design in a laboratory setting. Three-dimensional angles of the trunk, hip, and knee of 18 participants were evaluated at 60 degrees of knee flexion and at maximum squat depth during six SDT variations. Wilcoxon signed rank tests were performed to determine the effects of an anterior verse lateral step direction, a fixed arm or stance foot position, and an individual verse continuous trial collection method.Results: Knee flexion, external pelvic rotation, and external trunk rotation were greater in the anterior SDT, while the lateral SDT elicited greater pelvic tilt and hip flexion. Additionally, overall squat depth was greater across participants during the anterior SDT. Few clinically significant differences (≥3°) were observed due to fixing arm or stance foot position, and no differences were identified based on trial collection methods.Significance: The standardization of task instructions for motion analysis protocols utilized for research purposes and/or clinical decision-making is crucial. Specifically, for the SDT, the authors recommend using the anterior step direction. A fixed arm and stance foot position is not necessary, and trials may be collected individually or continuously based on convenience for a small number of repetitions. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this systematic review was to evaluate and summarize the current evidence base related to the clinical efficacy of gait analysis. A literature review was conducted to identify references related to human gait analysis published between January 2000 and September 2009 plus relevant older references. The references were assessed independently by four reviewers using a hierarchical model of efficacy adapted for gait analysis, and final scores were agreed upon by at least three of the four reviewers. 1528 references were identified relating to human instrumented gait analysis. Of these, 116 original articles addressed technical accuracy efficacy, 89 addressed diagnostic accuracy efficacy, 11 addressed diagnostic thinking and treatment efficacy, seven addressed patient outcomes efficacy, and one addressed societal efficacy, with some of the articles addressing multiple levels of efficacy. This body of literature provides strong evidence for the technical, diagnostic accuracy, diagnostic thinking and treatment efficacy of gait analysis. The existing evidence also indicates efficacy at the higher levels of patient outcomes and societal cost-effectiveness, but this evidence is more sparse and does not include any randomized controlled trials. Thus, the current evidence supports the clinical efficacy of gait analysis, particularly at the lower levels of efficacy, but additional research is needed to strengthen the evidence base at the higher levels of efficacy. [Copyright &y& Elsevier]

Background: The incidence of shoulder and elbow injuries in adolescent baseball players is rapidly increasing. One leading theory about this increase is that breaking pitches (such as the curveball) place increased moments on the dominant arm and thereby increase the risk of injury. Hypothesis: There is no difference in the moments at the shoulder and elbow between fastball and curveball pitches in adolescent baseball pitchers. Study Design: Controlled laboratory study. Methods: Thirty-three adolescent baseball pitchers with a minimum of 2 years of pitching experience underwent 3-dimensional motion analysis using reflective markers aligned to bony landmarks. After a warm-up, pitchers threw either a fastball or curveball, randomly assigned, from a portable pitching mound until 3 appropriate trials were collected for each pitch technique. Kinematic and kinetic data for the upper extremities, lower extremities, thorax, and pelvis were collected and computed for both pitch types. Statistical analysis included both the paired sample t test and mixed model regression. Results: There were lower moments on the shoulder and elbow when throwing a curveball versus when throwing a fastball. As expected, speed for the 2 pitches differed: fastball, 65.8 ± 4.8 mph; and curveball, 57.7 ± 6.2 mph (P < .001). Maximal glenohumeral internal rotation moment for the fastball was significantly higher than for the curveball (59.8 ± 16.5 N·m vs 53.9 ± 15.5 N·m; P < .0001). Similarly, the maximum varus elbow moment for the fastball was significantly higher than for the curveball (59.6 ± 16.3 N·m vs 54.1 ± 16.1 N·m; P < .001). The wrist flexor moment was greater in the fastball, 8.3 ± 3.6 N·m, than in the curveball, 7.8 ± 3.6 N·m (P < .001), but the wrist ulnar moment was greater in the curveball, 4.9 ± 2.0 N·m, than in the fastball, 3.2 ± 1.5 N·m (P < .001). Relatively minor motion differences were noted at the shoulder and elbow throughout the pitching motion, while significant differences were seen in forearm and wrist motion. The forearm remained more supinated at each point in the pitching cycle for the curveball but had less overall range of motion (62° ± 20°) than with the fastball (69° ± 17°) (P < .001), and the difference in the forearm pronation and supination moment between the pitches was not significant (P = .104 for pronation and P = .447 for supination). The wrist remained in greater extension during the fastball from foot contact through ball release but did not have significantly different total sagittal range of motion (53° ± 11°) when compared with the curveball (54° ± 15°) (P = .91). Conclusion: In general, the moments on the shoulder and elbow were less when throwing a curveball than when throwing a fastball. In each comparison, the fastball demonstrated higher moments for each individual pitcher for both joints. Clinical Relevance: The findings based on the kinematic and kinetic data in this study suggest that the rising incidence of shoulder and elbow injuries in pitchers may not be caused by the curveball mechanics. Further evaluation of adolescent and adult baseball pitchers is warranted to help determine and subsequently reduce the risk of injury. [ABSTRACT FROM AUTHOR]

Abstract: Rectus femoris transfer is frequently performed to treat stiff-knee gait in subjects with cerebral palsy. In this surgery, the distal tendon is released from the patella and re-attached to one of several sites, such as the sartorius or the iliotibial band. Surgical outcomes vary, and the mechanisms by which the surgery improves knee motion are unclear. The purpose of this study was to clarify the mechanism by which the transferred muscle improves knee flexion by examining three types of transfers. Muscle-actuated dynamic simulations were created of ten children diagnosed with cerebral palsy and stiff-knee gait. These simulations were altered to represent surgical transfers of the rectus femoris to the sartorius and the iliotibial band. Rectus femoris transfers in which the muscle remained attached to the underlying vasti through scar tissue were also simulated by reducing but not eliminating the muscle''s knee extension moment. Simulated transfer to the sartorius, which converted the rectus femoris’ knee extension moment to a flexion moment, produced 32±8° improvement in peak knee flexion on average. Simulated transfer to the iliotibial band, which completely eliminated the muscle''s knee extension moment, predicted only slightly less improvement in peak knee flexion (28±8°). Scarred transfer simulations, which reduced the muscle''s knee extension moment, predicted significantly less (p<0.001) improvement in peak knee flexion (14±5°). Simulations revealed that improved knee flexion following rectus femoris transfer is achieved primarily by reduction of the muscle''s knee extension moment. Reduction of scarring of the rectus femoris to underlying muscles has the potential to enhance knee flexion. [Copyright &y& Elsevier]

Niemann-Pick disease type C (NPC) is a progressive neurodegenerative disorder for which there is no effective treatment other than supportive therapy. Recently, the oral medication miglustat has been offered as a possible therapy aimed at reducing pathological substrate accumulation. This article describes the use of computerized three-dimensional motion analysis to evaluate a 3-year-old child with NPC treated with miglustat for 12 months. Motion analysis provided quantitative data on the patient's gait. However, dementia and motor dysfunction progressed despite the treatment, and the patient lost the ability to walk between 9 and 12 months of the study. Motion analysis should be considered among the tools for measuring functional outcomes in future therapeutical trials of patients with neurodegenerative diseases. It is not possible to draw conclusions about miglustat therapy in NPC from a single patient experience. © 2007 Movement Disorder Society [ABSTRACT FROM AUTHOR]

Abstract: Biomechanical model assumptions affect the interpretation of the role of the muscle or joint moments to the segmental power estimated by induced acceleration analysis (IAA). We evaluated the effect of modeling the pelvis and trunk segments as two separate segments (8 SM) versus as a single segment (7 SM) on the segmental power, support of the body, knee and hip extension acceleration produced by the joint moments during the stance phase of normal walking. Significant differences were observed in the contribution of the stance hip abductor and extensor moments to support, ipsilateral knee and hip acceleration, and ipsilateral thigh and upper body power. The primary finding was that the role of the stance hip moment in generating ipsilateral thigh and upper body power differed based on degrees of freedom in the model. Secondarily, the magnitude of contributions also differed. For example, the hip abductor and extensor moments showed greater contribution to support, hip and knee acceleration in the 8 SM. IAA and segment power analysis are sensitive to the degrees of freedom between the pelvis and trunk. There is currently no gold standard by which to evaluate the accuracy of IAA predictions. However, modeling the pelvis and trunk as separate segments is closer to the anatomical architecture of the body. An 8 SM appears to be more appropriate for estimating the role of joint moments, particularly to motion of more proximal segments during normal walking. [Copyright &y& Elsevier]

A three-dimensional biomechanical analysis on baseball pitching technique among adolescent is presented. The purpose of the study was to understand the etiology of injuries common to adolescent baseball pitchers. Kinetic and kinematics data for the lower and upper extremities, thorax, and pelvis of 24 adolescent pitchers were collected and analyzed using three-dimensional computerized motion analysis. Result of the measurements of motion of forearm, wrist shoulders, thorax and pelvic are analyzed. It is concluded that the measured parameters and the difference between adolescent and adult pitchers can be used to determine causes of pitching injuries.

Background: This paper updates our 2011 systematic review on the clinical efficacy of three-dimensional instrumented gait analysis (3DGA).Research Question: What is the current evidence base pertaining to the clinical efficacy of 3DGA?Methods: We identified English language articles published from September 2009 to October 2019 reporting primary research that used typical motion analysis laboratory methods to study human walking. Five gait laboratory experts classified articles according to the highest type of efficacy they addressed: type 1 (technical), 2 (diagnostic accuracy), 2b (outcome prediction), 3-4 (diagnostic thinking and treatment), 5 (patient outcome), 6 (societal). Articles classified into type 3-4 and higher were rated for quality using LEGEND.Results: Of 2712 articles related to the efficacy of 3DGA, over 99% addressed technical (n = 313), diagnostic (n = 1466), or outcome prediction (n = 927) efficacy. Six type 3-4 studies showed that 3DGA changes treatment plans, increases clinicians' confidence in their treatment decisions, and increases agreement among clinicians. Two type 5 articles based on a randomized controlled trial demonstrated that patient outcomes improved only when 3DGA data were available and its recommendations were followed. A population-based type 5 study found that the incidence of severe crouch gait dropped from 25% to 4% following practice changes including the addition of 3DGA. The strength of evidence was mainly 3b (lesser quality prospective cohort studies) but also included stronger studies (three level 2 controlled clinical trials).Significance: Literature related to the clinical efficacy of 3DGA has grown substantially over the last decade. Thousands of articles contribute to continued improvement of data collection and interpretation, as well as understanding of gait pathology and treatment. A smaller number of studies clearly demonstrate the efficacy of 3DGA in changing and reinforcing treatment decisions, increasing clinicians' confidence in treatment planning, and increasing agreement among clinicians, as well as the potential to improve patient outcomes. [ABSTRACT FROM AUTHOR]

• Greater severity of gait deviations in CMT Type 2 compared to CMT Type 1. • CMT Type 2 has greater compensations in swing than Type 1. • CMT Type 1 has greater planti/dorsiflexion strength than Type 2. • CMT Type 2 trends towards greater disease severity on CMTPedS than Type 1. • Inclusion of motion analysis data provides understanding of CMT types on gait. Charcot-Marie-Tooth (CMT) disease is an inherited peripheral neuropathy that causes progressive distal extremity nerve degeneration and muscle atrophy which can negatively impact function, gait and quality of life. The purpose of this study was to determine if differences exist in gait patterns, clinical examination and functional measures between CMT type I (CMT1) and type II (CMT2) in childhood to young adults. It was hypothesized that individuals with CMT2 would present with greater ankle weakness, increased and/or prolonged ankle dorsiflexion in stance during gait and demonstrate greater disease severity on the CMT Pediatric Scale (CMTPedS) compared to CMT1. Twenty-seven individuals diagnosed with CMT1 or CMT2 underwent three-dimensional gait analysis, clinical examination and evaluation of disease severity using the CMTPedS. Subjects groups were divided based on CMT type: CMT1 (n = 20) and CMT2 (n = 7). CMT2 group presented with a trend towards increased plantar flexion weakness compared to CMT1 of 61.1 ± 58.1 N to 137.9 ± 51.4 N (p < 0.012), respectively. CMT2 presented with significantly decreased dorsiflexion strength, 31.9 ± 30.9 N, compared to CMT1, 80.4 ± 37.4 N, (p < 0.0052) which negatively influenced gait patterns in CMT2. Associated gait findings demonstrated CMT2 group with significantly decreased peak ankle power generation in stance compared to CMT1 (1.46 ± 0.39 W/kg to 3.13 ± 0.98 W/kg respectively) (p < 0.0001). CMT1 was more likely to demonstrate a dorsiflexion moment in loading response than CMT2. There was a consistent trend of a higher score and therefore greater disease severity for CMT2 based on CMTPedS. Study results suggest that at a given age, individuals with CMT2 have greater limitations in terms of gait function and disease severity than individuals with CMT1. Overall the CMT2 was shown to have greater gait limitations at the ankle during stance and swing with associated compensatory mechanisms at the knee and hip in swing. [ABSTRACT FROM AUTHOR]

Introduction: Charcot-Marie-Tooth (CMT) disease is an inherited peripheral neuropathy that causes progressive distal extremity nerve degeneration and muscle atrophy which can negatively impact function, gait and quality of life. The purpose of this study was to determine if differences exist in gait patterns, clinical examination and functional measures between CMT type I (CMT1) and type II (CMT2) in childhood to young adults. It was hypothesized that individuals with CMT2 would present with greater ankle weakness, increased and/or prolonged ankle dorsiflexion in stance during gait and demonstrate greater disease severity on the CMT Pediatric Scale (CMTPedS) compared to CMT1.Methods: Twenty-seven individuals diagnosed with CMT1 or CMT2 underwent three-dimensional gait analysis, clinical examination and evaluation of disease severity using the CMTPedS. Subjects groups were divided based on CMT type: CMT1 (n = 20) and CMT2 (n = 7).Results: CMT2 group presented with a trend towards increased plantar flexion weakness compared to CMT1 of 61.1 ± 58.1 N to 137.9 ± 51.4 N (p < 0.012), respectively. CMT2 presented with significantly decreased dorsiflexion strength, 31.9 ± 30.9 N, compared to CMT1, 80.4 ± 37.4 N, (p < 0.0052) which negatively influenced gait patterns in CMT2. Associated gait findings demonstrated CMT2 group with significantly decreased peak ankle power generation in stance compared to CMT1 (1.46 ± 0.39 W/kg to 3.13 ± 0.98 W/kg respectively) (p < 0.0001). CMT1 was more likely to demonstrate a dorsiflexion moment in loading response than CMT2. There was a consistent trend of a higher score and therefore greater disease severity for CMT2 based on CMTPedS.Conclusion: Study results suggest that at a given age, individuals with CMT2 have greater limitations in terms of gait function and disease severity than individuals with CMT1. Overall the CMT2 was shown to have greater gait limitations at the ankle during stance and swing with associated compensatory mechanisms at the knee and hip in swing. [ABSTRACT FROM AUTHOR]

Background: Patients with recurrent clubfoot may seek intervention to address impairments that impact gait function. An understanding of these impairments and associated gait issues will provide valuable information about ongoing treatment requirements.Research Question: The purpose of this study was to describe the prevalence of impairments and associated gait deviations in children with recurrent clubfoot and to evaluate whether these findings differ depending on unilateral or bilateral presentation.Methods: Eighty-four affected feet (42 unilateral, 21 bilateral) were retrospectively reviewed. History, clinical exam, and gait data were collected. Statistical analysis included evaluations of associations between clinical exam and gait parameters and differences among patients with unilateral versus bilateral clubfoot and a database of healthy controls.Results: The average age was 7.5 ± 3.3 years for unilateral and 7.0 ± 2.8 years for bilateral patients. Patients presented with limited passive ankle dorsiflexion (unilateral/bilateral:67%/57%), limited ankle plantar flexion strength (unilateral/bilateral:53%/55%), metatarsus adductus (unilateral/bilateral:86%/83%) and internal foot-thigh angles (unilateral/bilateral:83%/82%), while only a subset presented with internal bi-malleolar axis angles (unilateral/bilateral:36%/45%). The most common gait deviations were internal foot progression (unilateral/bilateral:76%/73%), external hip rotation (unilateral/bilateral:66%/69%), reduced peak ankle plantar flexion moments (unilateral/bilateral:84%/83%), and reduced peak ankle power generation (unilateral/bilateral:67%/74%). Passive dorsiflexion was significantly correlated with peak dorsiflexion during stance and swing in both groups. Patients with unilateral compared to bilateral clubfoot showed decreased peak dorsiflexion and an associated knee flexor moment.Significance: Patients with recurrent clubfoot show gait deviations at the ankle that can be explained by joint level impairment and compensations at the knee, hip and pelvis. Patients with unilateral clubfoot typically show decreased dorsiflexion range of motion and associated greater gait impacts and compensations than bilateral clubfoot. Understanding the relationships between impairments and gait function and the implications of unilateral versus bilateral clubfoot will help improve prognostic ability and optimize future treatment outcomes. [ABSTRACT FROM AUTHOR]

Background: The incidence of upper extremity injuries in baseball pitchers is increasing. Over the past decade there has been a great deal of research attempting to elucidate the cause of these injuries, focusing mainly on the mechanics of the pitching arm with no examination of other key segments, such as the trunk. This is surprising, as coaches will often comment on trunk position in an effort to improve pitching outcomes. Purpose: To determine the association between contralateral trunk lean and ball velocity and the moments about the elbow and glenohumeral joint. Study Design: Descriptive laboratory study. Methods: A total of 99 pitchers were recruited for this study and underwent a pitching analysis using 3-dimensional motion analysis techniques. A random intercept mixed-effects regression model was used to determine if statistically significant associations existed between contralateral trunk lean (away from the pitching arm side) and ball velocity, as well as the elbow varus moment and glenohumeral internal rotation moment. Results: The results demonstrated that the greatest contralateral trunk lean occurs around the time of the peak elbow varus moment. Statistically significant associations were found between contralateral trunk lean and increased ball velocity (P = .003) indicating that for every 10 increase in contralateral lean, ball velocity increased 0.5 m/s. Results also indicated that for every 10 increase in contralateral lean, elbow varus moments increased by 3.7 Nm and glenohumeral internal rotation moments increased by 2.5 Nm (P \ .001 for both). Conclusion: Study findings indicate that the positioning of the trunk plays a substantial role in pitching performance and pitcher injury potential. This work helps to demonstrate the importance of proper trunk mechanics in pitching and highlights the need for future research to understand the contribution of the trunk to pitching mechanics. Clinical Relevance: Pitching coaches and trainers can use the results of this study to stress the importance of proper trunk mechanics in pitching. Specifically, improving core strength and trunk control in an effort to maintain a more upright posture through the pitching cycle can reduce upper extremity joint stresses. [ABSTRACT FROM AUTHOR]

Current pitching literature focuses primarily on the elbow and glenohumeral joints. This has led to a paucity of information regarding the forearm and wrist, and the limited data available are inconsistent. Therefore, this article seeks to provide a comprehensive description of the kinematics and kinetics of the wrist and forearm for the fastball, curveball, slider/cutter, and change-up for college-level baseball pitchers. Thirty-six collegiate pitchers were evaluated using motion analysis techniques. Results indicated that pitching the curveball generated the greatest forearm supination (16 ± 13°) compared with the other three pitch types (p < 0.05). The curveball and slider/cutter were pitched with less wrist extension and greater ulnar deviation compared with the fastball and change-up. The curveball was found to produce the greatest ulnar moment (7.3 ± 2.2 Nm) and was significantly different from the moments noted when pitching the fastball and change-up (5.1 ± 1.9 and 4.9 ± 1.9 Nm, respectively;p < 0.05). These results indicate that it may be possible to objectively determine pitch type from kinematic data of the wrist and forearm. It may also be possible that coaches may be able to identify abnormal pitching mechanics from more proximal segments by understanding the motion of the wrist. [ABSTRACT FROM PUBLISHER]

Aim This prospective multicenter study assessed performance and changes over time, with and without surgical intervention, in the modified Timed Up and Go (mTUG) and One-Minute Walk tests (1MWT) in children with bilateral cerebral palsy (CP). Minimum clinically important differences (MCIDs) were established for these tools. Method Two hundred and nineteen participants with bilateral spastic CP (Gross Motor Function Classification System [GMFCS] levels I-III) were evaluated at baseline and 12 months follow-up. The non-surgical group ( n=168; 54 females, 114 males; mean age 12y 11mo, [SD 2y 7mo], range 8y 1mo-19y) had no surgical interventions during the study. The surgical group ( n=51; 19 females, 32 males; mean age 12y 10mo [SD 2y 8mo] range 8y 2mo-17y 5mo) underwent soft-tissue and/or bony procedures within 12 months from baseline. The mTUG and 1MWT were collected and MCIDs were established from the change scores of the non-surgical group. Results Dependent walkers (GMFCS level III) required more time to complete the mTUG ( p≤0.01) than independent walkers (GMFCS levels I and II). For the 1MWT, distance walked decreased with increasing impairment ( p≤0.01). 1MWT and mTUG change scores were not significantly different at any GMFCS level for either the surgical or non-surgical groups ( p≤0.01). Interpretation Children with varying levels of function (GMFCS level) perform differently on the 1MWT and mTUG. The data and MCID values can assist clinicians in interpreting changes over time and in assessing interventions. [ABSTRACT FROM AUTHOR]

Abstract: Stiff-knee gait is characterized by diminished and delayed knee flexion during swing. Rectus femoris transfer surgery, a common treatment for stiff-knee gait, is often recommended when a patient exhibits prolonged activity of the rectus femoris muscle during swing. Treatment outcomes are inconsistent, in part, due to limited understanding of the biomechanical factors contributing to stiff-knee gait. This study used a combination of gait analysis and dynamic simulation to examine how activity of the rectus femoris during swing, and prior to swing, contribute to knee flexion. A group of muscle-actuated dynamic simulations was created that accurately reproduced the gait dynamics of ten subjects with stiff-knee gait. These simulations were used to examine the effects of rectus femoris activity on knee motion by eliminating rectus femoris activity during preswing and separately during early swing. The increase in peak knee flexion by eliminating rectus femoris activity during preswing (7.5±3.1°) was significantly greater on average (paired t-test, p=0.035) than during early swing (4.7±3.6°). These results suggest that preswing rectus femoris activity is at least as influential as early swing activity in limiting the knee flexion of persons with stiff-knee gait. In evaluating rectus femoris activity for treatment of stiff-knee gait, preswing as well as early swing activity should be examined. [Copyright &y& Elsevier]

Abstract: Children with crouch gait frequently walk with improved knee extension during the terminal swing and stance phases following hamstrings lengthening surgery; however, the mechanisms responsible for these improvements are unclear. This study tested the hypothesis that surgical lengthening enables the hamstrings of persons with cerebral palsy to operate at longer muscle–tendon lengths or lengthen at faster muscle–tendon velocities during walking. Sixty-nine subjects who had improved knee extension after surgery were retrospectively examined. The muscle–tendon lengths and velocities of the subjects’ semimembranosus muscles were estimated by combining kinematic data from gait analysis with a three-dimensional computer model of the lower extremity. Log-linear analyses confirmed that the subjects who walked with abnormally short muscle–tendon lengths and/or slow muscle–tendon velocities preoperatively tended to walk with longer lengths (21 of 29 subjects, ) or faster velocities (30 of 40 subjects, ) postoperatively. In these cases, surgical lengthening may have slackened the subjects’ tight hamstrings and/or diminished the hamstrings’ spastic response to stretch. Other subjects walked with muscle–tendon lengths and velocities that were neither shorter nor slower than normal preoperatively (22 of 69 subjects), and the semimembranosus muscles of most of these subjects did not operate at increased lengths or velocities after surgery; in these cases, the subjects’ postsurgical improvements in knee extension may have been unrelated to the hamstrings surgery. Analyses of muscle–tendon lengths and velocities may help to distinguish individuals who have “short” or “spastic” hamstrings from those who do not, and thus may augment conventional methods used to describe patients’ neuromusculoskeletal impairments and gait abnormalities. [Copyright &y& Elsevier]

Abstract: Persons with cerebral palsy frequently walk with excessive knee flexion during terminal swing and stance. This gait abnormality is often attributed to “short” or “spastic” hamstrings that restrict knee extension, and is often treated by hamstrings lengthening surgery. At present, the outcomes of these procedures are inconsistent. This study examined whether analyses of the muscle-tendon lengths and lengthening velocities of patients’ hamstrings during walking may be helpful when deciding whether a candidate is likely to benefit from hamstrings surgery. One hundred and fifty-two subjects were cross-classified in a series of multi-way contingency tables based on their pre- and postoperative gait kinematics, muscle-tendon lengths, muscle-tendon velocities, and hamstrings surgeries. The lengths and velocities of the subjects’ semimembranosus muscles were estimated by combining kinematic data from gait analysis with a three-dimensional computer model of the lower extremity. Log-linear analysis revealed that the subjects who walked with abnormally “short” or “slow” hamstrings preoperatively, and whose hamstrings did not operate at longer lengths or faster velocities postoperatively, were unlikely to walk with improved knee extension after treatment (p <0.05). Subjects who did not walk with abnormally short or slow hamstrings preoperatively, and whose hamstrings did operate at longer lengths or faster velocities postoperatively, tended to exhibit unimproved or worsened anterior pelvic tilt after treatment (p <0.05). Examination of the muscle-tendon lengths and velocities allows individuals who walk with abnormally short or slow hamstrings to be distinguished from those who do not, and thus may help to identify patients who are at risk for unsatisfactory postsurgical changes in knee extension or anterior pelvic tilt. [Copyright &y& Elsevier]

Study Design: Prospective study. Objective: Evaluate the impact of the distal fusion level on overall spine motion in patients with adolescent idiopathic scoliosis. Summary Of Background Data: In the surgical treatment of adolescent idiopathic scoliosis, the impact of incorporating a single additional distal lumbar fusion level on residual spinal motion is unclear. This study uses radiographs and computerized motion capture technology to determine whether the addition of a single lumbar level in a posterior fusion construct produces a detectable alteration in spinal motion. Methods: Twenty-three patients with adolescent idiopathic scoliosis were evaluated with standing radiographs and computerized motion analysis preoperatively and 1 year after fusion. Patients were divided into 2 groups: L1-L2 group (distal fusion ended at L1-L2) and an L3 group (distal fusion ended at L3). Cobb angle, coronal vertical alignment, sagittal vertical alignment, thoracic kyphosis, and lumbar lordosis were measured from radiographs. Three-dimensional motion data were obtained for static standing and repeated bending or twisting motions. Statistical analysis was performed with Student t test, analysis of variance, and Fisher exact methods. Results: Both the L1-L2 and L3 groups demonstrated loss of spinal motion compared with preoperative values. The L1-L2 group showed a significant loss of rotational motion but no significant loss of motion in the sagittal and coronal planes. The L3 group demonstrated significant loss of motion in both the coronal plane and the rotational plane. When the 2 groups were compared, the L3 group showed a significant loss of coronal plane bending (18° ± 10°, P = 0.002). Conclusion: Distal extension of a posterior spinal fusion construct to include L3 results in a significant decrease in spine motion in at least one plane. Preservation of a single lumbar segment may improve overall spine motion in the short term and may have implications for the long-term health of the unfused spine. Level Of Evidence: 3. [ABSTRACT FROM AUTHOR]