The effect of excessive tibial torsion on the capacity of muscles to extend the hip and knee during single-limb stance

Mitigating Crouch Gait With an Autonomous Pediatric Knee Exoskeleton in the Neurologically Impaired

Crouch gait is one of the most common compensatory walking patterns found in individuals with neurological disorders, often accompanied by their limited physical capacity. Notable kinematic characteristics of crouch gait are excessive knee flexion during stance and reduced range of motion during swing. Knee exoskeletons have the potential to improve crouch gait by providing precisely controlled torque assistance directly to the knee joint. In this study, we implemented a finite-state machine-based impedance controller for a powered knee exoskeleton to provide assistance during both stance and swing phases for five children and young adults who exhibit chronic crouch gait. The assistance provided a strong orthotic effect, increasing stance phase knee extension by an average of 12 deg. Additionally, the knee range of motion during swing was increased by an average of 15 deg. Changes to spatiotemporal outcomes, such as preferred walking speed and percent stance phase, were inconsistent across subjects and indicative of the underlying intricacies of user response to assistance. This study demonstrates the potential of knee exoskeletons operating in impedance control to mitigate the negative kinematic characteristics of crouch gait during both stance and swing phases of gait.

A new method for assessing tibial torsion using computerized tomography in a pediatric population

Purpose

Tibial torsion disorders may lead to abnormal gait, frequently leading to a consultation with a pediatric orthopedic surgeon. The present study evaluated an alternative method for assessing tibial torsion on computerized tomography (CT) images that considers the tibial distal axis to be equivalent to the geometric axis of the tibiotalar joint.

Methods

One hundred CT scans were reviewed retrospectively, and four measurements were taken: proximal transtibial angle (PTTA), posterior margin tibial plateau angle (PMTPA), intermalleolar angle (IMA), and talar angle (TA). The tibial torsion angle was then calculated using these different angles.

Results

The patient cohort comprised 38 girls and 62 boys, with a mean age of 12 ± 4.4 years. Median PTTA and PMTPA were -8.4° ± 14.7° and -8.8° ± 14.2°, respectively, with no statistically significant difference. Mean IMA and TA were 23° ± 16.2° and 17.2° ± 16.9°, respectively, with a statistically significant difference. Mean total measurement time per patient was 6'44", with means of 2'24" for PTTA, 36" for PMTPA, 2'14" for IMA, and 1'12" for TA.

Conclusion

Tibial torsion values may differ significantly depending on the axis chosen to define tibial orientation. At the level of the proximal tibia, the choice of PTTA or PMTPA had little influence on the calculation of the tibial torsion angle. There was a significant difference of 5.8° when measuring the distal tibia. Measuring the PMTPA and TA is probably more suited for use in clinical practice because their tracing is simple and faster.

Exploring the morphology of adult tibia and fibula from Sima de los Huesos site in sierra de Atapuerca, Burgos, Spain

The analysis of the locomotor anatomy of Late Pleistocene Homo has largely focused on changes in proximal femur and pelvic morphologies, with much attention centered on the emergence of modern humans. Although much of the focus has been on changes in the proximal femur, some research has also been conducted on tibiae and, to a lesser extent, fibulae. With this in mind, we present one of the largest samples of the same population of human tibiae and fibulae from the Middle Pleistocene to determine their main characteristic traits and establish similarities and differences, primarily with those of Neanderthals and modern humans, but also with other Middle Pleistocene specimens in the fossil record. Through this study, we established that the Middle Pleistocene population from the Sima de los Huesos (Atapuerca, Burgos, Spain) had lower leg long bones similar to those of Neanderthals, although there were some important differences, such as bone length, which this fossil individuals resembled those of modern humans and not to Neanderthals. This fact is related to the crural index and leg length, even though we do not have any true association between femora and tibiae yet, it has implications for establishing locomotor efficiency and climate adaptation.

Intraoperative Angle Measurement of Anatomical Structures: A Systematic Review

Ensuring precise angle measurement during surgical correction of orientation-related deformities is crucial for optimal postoperative outcomes, yet there is a lack of an ideal commercial solution. Current measurement sensors and instrumentation have limitations that make their use context-specific, demanding a methodical evaluation of the field. A systematic review was carried out in March 2023. Studies reporting technologies and validation methods for intraoperative angular measurement of anatomical structures were analyzed. A total of 32 studies were included, 17 focused on image-based technologies (6 fluoroscopy, 4 camera-based tracking, and 7 CT-based), while 15 explored non-image-based technologies (6 manual instruments and 9 inertial sensor-based instruments). Image-based technologies offer better accuracy and 3D capabilities but pose challenges like additional equipment, increased radiation exposure, time, and cost. Non-image-based technologies are cost-effective but may be influenced by the surgeon's perception and require careful calibration. Nevertheless, the choice of the proper technology should take into consideration the influence of the expected error in the surgery, surgery type, and radiation dose limit. This comprehensive review serves as a valuable guide for surgeons seeking precise angle measurements intraoperatively. It not only explores the performance and application of existing technologies but also aids in the future development of innovative solutions.

Does patella lowering as part of multilevel surgery improve knee kinematics in children with cerebral palsy and crouch gait? A meta-analysis of comparative studies

Purpose

To evaluate differences in knee kinematic outcomes of patellar-lowering surgery, specifically patellar tendon advancement or patellar tendon shortening, compared with no-patellar-lowering surgery in multilevel surgery for children with cerebral palsy and crouch gait.

Methods

Four databases were searched to retrieve studies published from inception until 2023. Three reviewers independently screened for studies with observational or randomized control designs, comparing two groups of patients with cerebral palsy and crouch gait who underwent multilevel surgery (with patellar-lowering surgery versus no-patellar-lowering surgery), where various gait analysis outcomes were reported (CRD42023450692). The risk of bias was assessed with the Risk Of Bias In Non-randomised Studies - of Interventions (ROBINS-I) tool.

Results

Seven studies (249 patients and 368 limbs) met the eligibility criteria. Patients undergoing patellar-lowering surgery demonstrated statistically significant improvements in knee flexion at initial contact (mean difference = -6.39; 95% confidence interval = [-10.4, -2.75]; p = 0.0006; I2 = 84%), minimum knee flexion in stance (mean difference = -14.27; 95% confidence interval = [-18.31, -10.23]; p < 0.00001; I2 = 89%), and clinical knee flexion contracture (mean difference = -5.6; 95% confidence interval = [-9.59, -1.6]; p = 0.006; I2 = 95%), with a significant increase in anterior pelvic tilt (mean difference = 2.97; 95% confidence interval = [0.58, 5.36]; p = 0.01; I2 = 15%). However, improvements in gait deviation index and decrease in peak knee flexion in swing did not reach statistical significance. Subgroup analysis reduced heterogeneity and revealed (1) greater improvement using patellar tendon shortening versus patellar tendon advancement techniques; (2) lack of knee flexion contracture improvement in high-quality or longer-term studies; (3) longer-term improvement only in minimum knee flexion in stance, with a decrease in peak knee flexion in swing; and (4) an inability to assess the potential benefit of rectus femoris procedure and hamstring preservation.

Conclusions

Overall, the combination of patellar-lowering surgery with multilevel surgery demonstrated superior improvements in stance-phase knee kinematics compared with multilevel surgery alone, despite an increase in anterior pelvic tilt and a longer-term knee flexion reduction during the swing phase.

Level of evidence

Level III, Systematic review of level III studies.

Crouch Gait in Cerebral Palsy: Current Concepts Review

Background and Objective

Crouch gait is the most common pathological gait pattern in cerebral palsy and is commonly seen in patients with spastic diplegia. It is characterized by excessive knee flexion throughout the stance phase of gait cycle. The aim of this review is to discuss the current literature about CG for a more comprehensive understanding.

Methods

A literature review about various aspects of crouch gait in cerebral palsy was undertaken. This included its etiology and pathophysiology, biomechanics in crouch gait, natural history of untreated crouch gait, clinical and radiological evaluation and different modalities of available treatment.

Results

The etiology is multifactorial and the pathophysiology is poorly understood. This makes its management challenging, thereby leading to a variety of available treatment modalities. Inadvertent lengthening of muscle-tendon units is an important cause and can be avoided. A meticulous clinical and radiological evaluation of patients, supplemented by observational and instrumented gait analysis is mandatory in choosing correct treatment modality and improving the treatment outcome. Younger children can be managed satisfactorily by various non-operative methods and spasticity reduction measures. However, crouch gait in cerebral palsy has a progressive natural history and surgical interventions are needed frequently. The current literature supports combination of various soft tissue and bony procedures as a part of single event multilevel surgery. Growth modulation in the form of anterior distal femur hemiepiphysiodesis for correction of fixed flexion deformity of knee has shown encouraging results and can be an alternative in younger children with sufficient growth remaining.

Conclusions

In spite of extensive research in this field, the current understanding about crouch gait has many knowledge gaps. Further studies about the etiopathogenesis and biomechanics of crouch using instrumented gait analysis are suggested. Similarly, future research should focus on the long term outcomes of different treatment modalities through comparative trials.

The association between tibial torsion, knee flexion excursion and foot progression during gait in people with knee osteoarthritis: a cross-sectional study

BACKGROUND

Lower limb malalignment is associated with gait kinematics, but there is limited information on the relationship between gait kinematics and tibial torsion in individuals with knee osteoarthritis (OA). This study aimed to investigate possible associations between tibial torsion and early stance kinematics during gait in people with mild and moderate medial knee OA.

METHODS

Forty-seven participants (age: 62.1 ± 6.0 years; female/male: 37/10) diagnosed with medial knee OA were recruited from a regional hospital. Thirty of them had mild and seventeen had moderate knee OA. Lower limb alignment including tibial torsion and valgus/varus alignment were assessed by an EOS biplaner X-ray system with participants in weight-bearing position. Lower limb kinematics during gait was captured using the Vicon motion analysis system. The associations were estimated by partial Pearson correlation coefficient test.

RESULTS

Our results indicated that external tibial torsion was related to early stance knee flexion excursion in participants with moderate knee OA (r = -0.58, p = 0.048), but not in participants with mild knee OA (r = 0.34, p = 0.102). External tibial torsion was associated with external foot progression angle (r = 0.48, p = 0.001), and knee varus/valgus alignment was associated with knee flexion excursion (r = -0.39, p = 0.010) in all participants.

CONCLUSIONS

Both horizontal and frontal lower limb alignments were associated with knee flexion excursion at early stance of gait cycle in participants with medial knee OA. The distal rotational profile of lower limb would likely affect knee motion in sagittal plane. It implies that people with moderate knee OA could possibly benefit from correction of rotational alignment of lower limb.

A prospective assessment of gait kinematics and related clinical examination measures in cerebral palsy crouch gait

Background While prospectively assessed crouch gait in cerebral palsy (CP) does not necessarily progress, prospective changes in clinical examination measures have not been reported. This study prospectively examined the association between selected clinical examination variables and change in crouch gait in a cohort with bilateral CP. Methods Inclusion criteria were a diagnosis of ambulant bilateral CP, knee flexion at mid-stance >19 0 and a minimum of two-years between gait analyses. The change in kinematic variables was assessed using Statistical Parameter Mapping (SPM) and changes in clinical measures using appropriate paired tests. Linear regression examined the association between progression of crouch and clinical examination variables. Results There was no mean change in crouch in 27 participants over 3.29 years. However, there was significant variability within this group. Clinical hamstring tightness (60.00 0 to 70.48 0, p<0.01) and external knee rotation during stance (SPM analysis, p<0.001) increased but there was no association between changes in clinical examination variables and changes in crouch (p-values 0.06 - 0.89).    Conclusions This prospective study found no association between the changes in clinical examination variables and changes in crouch highlighting the likely multi-factorial aetiology of this gait pattern and the need for larger prospective studies. The variability crouch gait progression among the 27 participants highlights the pitfall of group mean values in such a heterogeneous population.

A prospective assessment of gait kinematics and related clinical examination measures in cerebral palsy crouch gait

Background While prospectively assessed crouch gait in cerebral palsy (CP) does not necessarily progress, prospective changes in clinical examination measures have not been reported. This study prospectively examined the association between selected clinical examination variables and change in crouch gait in a cohort with bilateral CP. Methods Inclusion criteria were a diagnosis of ambulant bilateral CP, knee flexion at mid-stance >190 and a minimum of two-years between gait analyses. The change in kinematic variables was assessed using Statistical Parameter Mapping (SPM) and changes in clinical measures using appropriate paired tests. Linear regression examined the association between progression of crouch and clinical examination variables. Results There was no mean change in crouch in 27 participants over 3.29 years. However, there was significant variability within this group. Clinical hamstring tightness (60.000 to 70.480, p<0.01) and external knee rotation during stance (SPM analysis, p<0.001) increased but there was no association between changes in clinical examination variables and changes in crouch (p-values 0.06 - 0.89).    Conclusions The variability crouch gait progression highlights the pitfall of group mean values in such a heterogeneous population.  The lack of association between changes in clinical examination variables and changes in crouch highlights the multi-factorial aetiology of this gait pattern and the need for larger prospective studies.

Conclusion or Illusion: Quantifying Uncertainty in Inverse Analyses From Marker-Based Motion Capture due to Errors in Marker Registration and Model Scaling

Estimating kinematics from optical motion capture with skin-mounted markers, referred to as an inverse kinematic (IK) calculation, is the most common experimental technique in human motion analysis. Kinematics are often used to diagnose movement disorders and plan treatment strategies. In many such applications, small differences in joint angles can be clinically significant. Kinematics are also used to estimate joint powers, muscle forces, and other quantities of interest that cannot typically be measured directly. Thus, the accuracy and reproducibility of IK calculations are critical. In this work, we isolate and quantify the uncertainty in joint angles, moments, and powers due to two sources of error during IK analyses: errors in the placement of markers on the model (marker registration) and errors in the dimensions of the model’s body segments (model scaling). We demonstrate that IK solutions are best presented as a distribution of equally probable trajectories when these sources of modeling uncertainty are considered. Notably, a substantial amount of uncertainty exists in the computed kinematics and kinetics even if low marker tracking errors are achieved. For example, considering only 2 cm of marker registration uncertainty, peak ankle plantarflexion angle varied by 15.9°, peak ankle plantarflexion moment varied by 26.6 N⋅m, and peak ankle power at push off varied by 75.9 W during healthy gait. This uncertainty can directly impact the classification of patient movements and the evaluation of training or device effectiveness, such as calculations of push-off power. We provide scripts in OpenSim so that others can reproduce our results and quantify the effect of modeling uncertainty in their own studies.

Tibial torsion correlates with talar morphology

BACKGROUND

There is limited literature on axial rotation of the ankle or variations in anatomy of the talus. We aim to evaluate the rotational profile of the distal tibia and its relationship to talus morphology, radiographic foot-type, and tibiotalar tilt in arthritic ankles.

METHODS

Preoperative imaging was reviewed in 173 consecutive patients with ankle arthritis. CT measurements were used to calculate tibial torsion and the talar neck-body angle (TNBA). Tibiotalar tilt and foot-type were measured on weightbearing plain radiographs.

RESULTS

Measurements indicated mean external tibial torsion of 29.2±9.1˚ and TNBA of 35.2±7.5˚ medial. Tibiotalar tilt ranged from 48˚ varus to 23.5˚ valgus. A moderate association between increasing external tibial torsion and decreasing TNBA was found (ρ=-0.576, p<.0001). Weak relationships were found between external tibial torsion and varus tibiotalar tilt (ρ=-0.239, p=.014) and plantarflexion of the talo-first metatarsal angle (ρ=-0.218, p<.025).

CONCLUSION

We observed a statistically significant correlation between tibial torsion and morphology of the talus, tibiotalar tilt, and first ray plantarflexion. This previously unreported association may provide information regarding the development of foot and ankle deformity and pathology.

LEVEL OF EVIDENCE

Level III.

A Novel Fluoroscopic Method for Assessing Rotational Malalignment of the Tibia

OBJECTIVE

To evaluate the accuracy and reliability of a novel fluoroscopic technique for assessing tibial rotation and compare it with a previously described fluoroscopic method.

METHODS

A multiplanar circular ring external fixator was secured to the tibial diaphysis of 5 cadaveric lower extremity specimens. Using deformity correction software, the frame and tibia were programed to randomly rotate 5, 10, 15, 20, 25, and 30 degrees of internal and external rotation. After each rotation, 2 blinded, independent observers measured the degree of tibial rotation using 2 different fluoroscopic methods: the previously described "mortise" method and the novel "intermalleolar" method. A total of 65 measurements were made by each observer. Accuracy and interobserver reliability were calculated.

RESULTS

Both intermalleolar and mortise methods had a mean absolute rotational difference from the true torsion of 3 degrees (standard error 1; range, 0-10 degrees intermalleolar vs. 0-18 degrees mortise). We found that 98.5% (128/130) of measurements using the intermalleolar method were less than 10 degrees from the true rotation compared with 93.8% (122/130) using the mortise method. Both the intermalleolar and the mortise methods had excellent interobserver reliability (intraclass correlation coefficient 0.99 and 0.96, respectively).

CONCLUSION

Measuring tibial rotation fluoroscopically using the intermalleolar method is both accurate and reliable. Compared with the previously described mortise method, it has similar accuracy and provides a value that approximates the true tibial rotation. Also, it can be used reliably and effectively intraoperatively to identify tibial malrotation and assist in intraoperative rotational corrections.

Does pathologically increased or decreased tibial torsion affect muscle activations during walking in typically developing adolescents?

A reduced capacity of plantar flexors and other muscles to extend the hip and knee during gait was shown in modelling studies when the tibial torsion angle is > 30° than normal. The aim of the current study was to determine if patients with increased or decreased tibial torsion show deviating muscle activations in knee and hip extensors in surface electromyography (EMG). Patients with CT confirmed increased tibial torsion (n = 19, ITT), decreased tibial torsion (n = 21, DTT) and age-matched healthy controls (n = 20) were included in this retrospective study. Additionally, kinematic and kinetic data were recorded during three-dimensional gait analysis. Surface EMG was recorded for vastus medialis and medial hamstrings. Statistical parametric mapping with a one-way ANOVA and post-hoc Bonferroni corrected two-sample t-tests were used to obtain differences in joint angles and moments. ITT and DTT showed an increased and decreased external foot progression angle, respectively. No additional muscle activations in vastus medialis and medial hamstrings were found in both patient groups compared to controls. DTT showed an increased hip flexion through parts of the gait cycle and both patient groups had a decreased knee extension moment in terminal stance. Our hypothesis of deviating muscle activation had to be rejected. It could be that in most orthopaedic patients the amount of exceeding tibial torsion is too low to cause substantial deviations in gait and muscle activation patterns.

The Impact of Patellar Tendon Advancement on Knee Joint Moment and Muscle Forces in Patients with Cerebral Palsy

Background: Patellar tendon advancement (PTA) is performed for the treatment of crouch gait in patients with cerebral palsy (CP). In this study, we aimed to determine the influence of PTA in the context of single-event multilevel surgery (SEMLS) on knee joint moment and muscle forces through musculoskeletal modeling; Methods: Gait data of children with CP and crouch gait were retrospectively analyzed. Patients were included if they had a SEMLS with a PTA (PTA group, n = 18) and a SEMLS without a PTA (NoPTA group, n = 18). A musculoskeletal model was used to calculate the pre- and postoperative knee joint moments and muscle forces; Results: Knee extensor moment increased in the PTA group postoperatively (p = 0.016), but there was no statistically significant change in the NoPTA group (p > 0.05). The quadriceps muscle forces increased for the PTA group (p = 0.034), while there was no difference in the NoPTA group (p > 0.05). The hamstring muscle forces increased in the PTA group (p = 0.039), while there was no difference in the NoPTA group (p > 0.05); Conclusions: PTA was found to be an effective surgery for the treatment of crouch gait. It contributes to improving knee extensor moment, decreasing knee flexor moment, and enhancing the quadriceps and hamstring muscle forces postoperatively.

Factors associated with increased terminal swing knee flexion in cerebral palsy

BACKGROUND

Increased terminal swing knee flexion (TSKF) impacts on step length, walking efficiency and may lead to knee flexion in stance in cerebral palsy (CP). Surgical lengthening of the hamstrings is often used to address this issue, but outcomes are inconsistent. There is an established association between TSKF and functional shortening or reduced lengthening velocity of the hamstrings. However, the aetiology of increased TSKF in CP is complex and additional associated factors are not well understood. An examination of clinical and kinematic factors associated with increased TSKF may demonstrate this complexity, highlight the multifactorial nature of this feature and provide a basis for enhanced treatment decision making.

RESEARCH QUESTION

What kinematic and clinical factors are associated with TSKF in individuals with CP?.

METHODS

A retrospective database review was conducted. Individuals with bilateral CP were identified and a subset was extracted which represented the full spectrum of degree of TSKF in the database. The total dataset for analysis was n = 88. Associations between absolute clinical and kinematic data and TSKF were explored using correlation analysis, linear and multivariate regression. Time series data were examined across quartiles using statistical parametric mapping analysis of variance (SPM ANOVA).

RESULTS

Increased TSKF was associated with overall gait impairment (GDI), degree of knee flexion throughout the stride, knee extension velocity, hamstring lengthening characteristics and functional status (GMFCS). There was no relationship to walking speed or clinical measures of hamstring extensibility on clinical assessment.

SIGNIFICANCE

TSKF is associated with multiple factors which clinicians need to consider when devising treatment strategies. Caution is advised when relying on degree of TSKF to independently guide surgical decision-making.

Radiographic cortical thickness parameters as predictors of rotational alignment in proximal tibial shaft fractures: a cadaveric study

AIM

The treatment of tibial fractures with an intramedullary nail is an established procedure. However, torsional control remains challenging using intraoperatively diagnostic tools. Radiographic tools such as the Cortical Step Sign (CSS) and the Diameter Difference Sign (DDS) may serve as tools for diagnosing a relevant malrotation. The aim of this study was to investigate the effect of torsional malalignment on CSS and DDS parameters and to construct a prognostic model to detect malalignment.

METHODS

A proximal tibial shaft fracture was set in human tibiae. Torsion was set stepwise from 0° to 30° in external and internal torsion. Images were obtained with a C-arm and transferred to a PC for measuring the medical cortical thickness (MCT), lateral cortical thickness (LCT), tibial diameter (TD) in AP and the anterior cortical thickness (ACT) as well as the posterior cortical thickness (PCT) and the transverse diameter (TD) of the proximal and the distal main fragment.

RESULTS

There were significant differences between the various degrees of torsion for each of the absolute values of the examined variables. The parameters with the highest correlation were TD, LCT and ACT. A model combining ACT, LCT, PCT and TD lateral was most suitable model in identifying torsional malalignment. The best prediction of clinically relevant torsional malalignment, namely 15°, was obtained with the TD and the ACT.

CONCLUSION

This study shows that the CSS and DDS are useful tools for the intraoperative detection of torsional malalignment in proximal tibial shaft fractures and should be used to prevent maltorsion.

Torsion Tool: An automated tool for personalising femoral and tibial geometries in OpenSim musculoskeletal models

Common practice in musculoskeletal modelling is to use scaled musculoskeletal models based on a healthy adult, but this does not consider subject-specific geometry, such as tibial torsion and femoral neck-shaft and anteversion angles (NSA and AVA). The aims of this study were to (1) develop an automated tool for creating OpenSim models with subject-specific tibial torsion and femoral NSA and AVA, (2) evaluate the femoral component, and (3) release the tool open-source. The Torsion Tool (https://simtk.org/projects/torsiontool) is a MATLAB-based tool that requires an individual's tibial torsion, NSA and AVA estimates as input and rotates corresponding bones and associated muscle points of a generic musculoskeletal model. Performance of the Torsion Tool was evaluated comparing femur bones as personalised with the Torsion Tool and scaled generic femurs with manually segmented bones as golden standard for six typically developing children and thirteen children with cerebral palsy. The tool generated femur geometries closer to the segmentations, with lower maximum (-19%) and root mean square (-18%) errors and higher Jaccard indices (+9%) compared to generic femurs. Furthermore, the tool resulted in larger improvements for participants with higher NSA and AVA deviations. The Torsion Tool allows an automatic, fast, and user-friendly way of personalising femoral and tibial geometry in an OpenSim musculoskeletal model. Personalisation is expected to be particularly relevant in pathological populations, as will be further investigated by evaluating the effects on simulation outcomes.

A Validated, Automated, 3-Dimensional Method to Reliably Measure Tibial Torsion

BACKGROUND

Tibial torsion is a twist in the tibia measured as an angle between a proximal axis line and a distal axis line. Abnormal torsion has been associated with a variety of painful clinical syndromes of the lower limb. Measurements of normal tibial torsion reported by different authors vary by 100% (ranging from 20° to 42°), making it impossible to determine normal and pathological levels.

PURPOSE

To address the problem of unreliable measurements, this study was conducted to define an automated, validated computer method to calculate tibial torsion. Reliability was compared with current clinical methods. The difference between measurements of torsion generated from computed tomography (CT) and magnetic resonance imaging (MRI) scans of the same bone, and between males and females, was assessed.

STUDY DESIGN

Controlled laboratory study.

METHODS

Previous methods of analyzing tibial torsion were reviewed, and limitations were identified. An automated measurement method to address these limitations was defined. A total of 56 cadaveric and patient tibiae (mean ± SD age, 37 ± 15 years; range, 17-71 years; 28 female) underwent CT scanning, and 3 blinded assessors made torsion measurements by applying 2 current clinical methods and the automated method defined in the present article. Intraclass correlation coefficient (ICC) values were calculated. Further, 12 cadaveric tibiae were scanned by MRI, stripped of tissue, and measured using a structured light (SL) scanner. Differences between torsion values obtained from CT, SL, and MRI scans, and between males and females, were compared using t tests. SPSS was used for all statistical analysis.

RESULTS

When the automated method was used, the tibiae had a mean external torsion of 29°± 11° (range, 9°-65). Automated torsion assessment had excellent reliability (ICC, 1), whereas current methods had good reliability (ICC, 0.78-0.81). No significant difference was found between the torsion values calculated from SL and CT (P = .802), SL and MRI (P = .708), or MRI and CT scans (P = .826).

CONCLUSION

The use of software to automatically perform measurements ensures consistency, time efficiency, validity, and accuracy not possible with manual measurements, which are dependent on assessor experience.

CLINICAL RELEVANCE

We recommend that this method be adopted in clinical practice to establish databases of normal and pathological tibial torsion reference values and ultimately guide management of related conditions.

Tibial torsion analysis in computed tomography: development and validation of a real 3D measurement technique

PURPOSE

Pathological tibial torsion is known to negatively influence the functionality of the lower extremity, and therefore, its assessment might play an important role. While 3D imaging is used for many examinations of the musculoskeletal system, for the determination of tibial torsion no 3D measurement technique has been available so far. We developed a 3D measurement method and assess its interobserver reliability as well as its correlation with standard 2D measurement methods.

METHODS

CT scans of 82 tibiae in 79 patients with a mean age of 41 years were included. A novel 3D measurement technique was developed and applied. Measurements were compared with two frequently used 2D measurement methods. ICC (intraclass correlation coefficient) for the new technique was determined and compared to the 2D measurement method. Furthermore, differences between left and right legs as well as between males and females were assessed.

RESULTS

The ICC for the 2D methods was 0.917 and 0.938, respectively. For the 3D measurements, ICCs were calculated to be 0.954 and 0.950. Agreement between 2 and 3D methods was moderate to good with ICCs between 0.715 and 0.795. Torsion values for left and right legs did not differ significantly in 2D and in 3D (26.2 vs 28.5° and 27.2 vs. 25.9°). The same is true for the differences between male and female in 2D and 3D (26.2 vs. 29.6° and 25.0 vs. 31.2°).

CONCLUSION

The newly developed 3D measurement technique shows a high intraclass agreement and offers an applicable opportunity to assess the tibial torsion three-dimensionally.

Tibial Torsion and Patellofemoral Pain and Instability in the Adult Population: Current Concept Review

PURPOSE OF REVIEW

Tibial torsion is a recognized cause of patellofemoral pain and instability in the paediatric population; however, it is commonly overlooked in the adult population. The aim of this review article is to summarize the current best evidence on tibial torsion for the adult orthopaedic surgeon.

RECENT FINDINGS

The true incidence of tibial torsion in the adult population is unknown, with significant geographical variations making assessment very difficult. CT currently remains the gold standard for quantitatively assessing the level of tibial torsion and allows assessment of any associated femoral and knee joint rotational anomalies. Surgical correction should only be considered after completion of a course of physiotherapy aimed at addressing the associated proximal and gluteal weakness. Tibial torsion greater than 30° is used as the main indicator for tibial de-rotation osteotomy by the majority of authors. In patients with associated abnormal femoral rotation, current evidence would suggest that a single-level correction of the tibia (if considered to be a dominant deformity) is sufficient in the majority of cases. Proximal de-rotational osteotomy has been more commonly reported in the adult population and confers the advantage of allowing simultaneous correction of patella alta or excessive tubercle lateralization. Previous surgery prior to de-rotational osteotomy is common; however, in patients with persistent symptoms surgical correction still provides significant benefit. Tibial torsion persists into adulthood and can play a significant role in patellofemoral pathology. A high index of suspicion is required in order to identify torsion clinically. Surgical correction is effective for both pain and instability, but results are inferior in patients with very high pain levels pre-surgery and multiple previous surgeries.

Intraoperative torsion control using the cortical step sign and diameter difference in tibial mid-shaft fractures

AIM

Intramedullar nailing of tibial mid-shaft fractures is a common surgical treatment. Fracture reduction, however, remains challenging and maltorsion is a common discrepancy which aggravates functional impairment of gait and stability. The use of radiographic tools such as the cortical step sign (CSS) and the diameter difference sign (DDS) could improve fracture reduction. Therefore, the validity of the CSS and DDS was analyzed to facilitate detection of maltorsion in tibial mid-shaft fractures.

METHODS

Tibial mid-shaft fractures were induced in human cadaveric tibiae according to the AO classification type A3. Torsional discrepancies from 0° to 30° in-/external direction were enforced after intramedullary nailing. Fluoroscopic-guided fracture reduction was assessed in two planes via analysis of the medical cortical thickness (MCT), lateral cortical thickness (LCT), tibial diameter (TD), anterior cortical thickness (ACT), posterior cortical thickness (PCT) and the transverse diameter (TD) of the proximal and distal fracture fragment.

RESULTS

The TD, LCT and ACT have shown a highly significant correlation to predict tibial maltorsion. While a model combining ACT, LCT, PCT and TD lateral was most suitable model to identify tibial maltorsion, a torsional discrepancy of 15°was most reliably detected with use of the TD and ACT.

CONCLUSION

The present study has shown, that maltorsion can be reliably assessed by the CSS and DDS during fluoroscopy. Thus, torsional discrepancies in tibial mid-shaft fractures can be most reliably assessed in the lateral plane by analysis of the LCT and TD.

Tibial rotation outcomes following hamstring lengthening as part of single event multilevel surgery in children with cerebral palsy

BACKGROUND

Hamstring lengthening remains the most common surgical procedure in the treatment of crouch gait for children with cerebral palsy (CP). While sagittal plane knee kinematics have been shown to improve post-surgery, the effects on transverse plane kinematics have not been reported. Given the differing actions of the medial and lateral hamstring muscles there is potential for change in tibial rotation post hamstring lengthening.

RESEARCH QUESTION

What is the effect of medial only versus combined medial and lateral hamstring lengthening on tibial rotation during gait in children with CP?

METHODS

A retrospective analysis of children with a diagnosis of CP who underwent a hamstring lengthening procedure. These children were divided into 2 groups: G1 (n = 18) had isolated medial hamstring lengthening while G2 (n = 30) had combined medial and lateral hamstring lengthening. A matched non-surgical control group (n = 15) was also included. Kinematic data were analysed pre and post-operatively. Pre-operative to post-operative outcomes for G1 and G2, a comparison at baseline for both groups and the difference in outcomes between the groups were analysed. Baseline to follow-up outcomes for the control group were also analysed.

RESULTS

External tibial rotation increased significantly within groups (G1: -10°, p < 0.01; G2: -11°, p < 0.001, control: -7.7, p < 0.01), with no significant difference in the change between the intervention groups. Foot progression angles became more external in both intervention groups (G1: -15°, p < 0.001; G2: -15°, p < 0.0001) and did not change in the control group.

SIGNIFICANCE

Results demonstrated similar increases in external tibial rotation, regardless of whether an isolated medial or combined medial and lateral surgery was performed. The control group demonstrated a similar change in external tibial rotation suggesting that hamstring lengthening surgery does not contribute to increased external tibial rotation in children with CP compared to what would be expected due to natural progression.

Muscle capacity to accelerate the body during gait varies with foot position in cerebral palsy

BACKGROUND

Children with cerebral palsy (CP) often have altered gait patterns compared to their typically developing peers. These gait patterns are characterized based on sagittal plane kinematic deviations; however, many children with CP also walk with altered transverse plane kinematics.

RESEARCH QUESTION

How do both altered skeletal alignment and kinematic deviations affect muscles' capacity to accelerate the body during gait?

METHODS

A three-dimensional gait analysis was completed for 18 children with spastic CP (12.5 ± 2.9 years; GMFCS level II). Musculoskeletal models were developed for each participant, and tibial torsion, measured during a static standing trial and assessed using motion capture, was incorporated. An induced acceleration analysis was performed to evaluate the capacity of muscles to accelerate the body center of mass throughout stance. Differences between the root-mean-square muscle capacity for children with CP walking with internally rotated, standard, and externally rotated postures were evaluated.

RESULTS

Externally rotated postures resulted in a lower capacity to accelerate the body center of mass compared with internally rotated postures. Both changes in skeletal alignment and kinematics contributed to changes in muscle capacity to accelerate the body.

SIGNIFICANCE

Altered transverse plane skeletal alignment and compensatory kinematics should both be considered in surgical treatment of children with CP.

Compensatory gait deviations in patients with increased outward tibial torsion pre and post tibial derotation osteotomy

BACKGROUND

Tibial torsion describes the rotation between the proximal and distal joint axis along the shaft, which can be, as rotational deformity, pathologically increased or decreased. Some patients might increase hip internal rotation during walking to compensate increased outward tibial torsion.

RESEARCH QUESTION

The aim of this study was to assess the effect of tibial derotation osteotomy on gait deviations in patients with increased outward tibial torsion.

METHODS

Thirteen patients (13.5 ± 1.4 yrs, 22 limbs) with increased tibial torsion (CT confirmed 49.2 ± 4.8°) were analyzed pre and post tibial derotation osteotomy and compared with 17 typically developing children (TDC, 13.5 ± 2.3 yrs, 32 limbs). Kinematic and kinetic data were recorded. Subgroup analyses were performed whether patients showed compensatory hip internal rotation (Comp) or not (NoComp). Principal component (PC) analysis was used to achieve data transformation. A linear mixed model was used to estimate the main effect of PC-scores of retained PCs explaining 90% of the cumulative variance.

RESULTS

Compensatory hip internal rotation (Comp, present in 45.5% of limbs analyzed) led to a lower external foot progression angle compared to patients without compensatory hip internal rotation (NoComp). In both patient groups foot progression angle was normalized after tibial derotation osteotomy. Post-operative NoComp had normalized frontal plane joint loadings, while Comp showed an increased hip and knee adduction moment.

SIGNIFICANCE

Future studies should investigate if more time is needed for Comp to normalize gait patterns post-operative or if a pre and post-operative gait training might help. Otherwise the increased knee adduction moment might be clinically relevant due to previous studies reporting a possible association with knee osteoarthritis.

Pre-operative hamstring length and velocity do not explain the reduced effectiveness of repeat hamstring lengthening in children with cerebral palsy and crouch gait

BACKGROUND

Hamstring lengthening surgery (HSL) is often performed to correct crouch gait in patients with cerebral palsy (CP). However, crouch can recur over time, and repeat HSL may be ineffective. One possible reason is that the hamstrings in repeat HSL patients are neither short nor lengthening slowly and would therefore not benefit from HSL.

RESEARCH QUESTION

This study aimed to determine whether the hamstrings are short and/or slow preoperatively only in patients with primary, and not repeat, HSL.

METHODS

We compared pre- and postoperative dynamic semimembranosus muscle-tendon lengths for children with CP who had primary (N = 15) or repeat (N = 8) HSL to a group of control participants (N = 10). Outcome measures were compared between visits (pre- vs. postoperative) and groups (control, primary HSL, repeat HSL) using mixed model analysis.

RESULTS

Preoperatively, hamstrings were shorter and slower than normal on average in both HSL groups (p < 0.001); all but 3 limbs (primary 26/28, repeat 13/14) had hamstrings that were shorter and/or slower than controls by more than two standard deviations. Postoperative improvements were observed in the primary HSL group for popliteal angle, initial contact knee flexion, minimum stance knee flexion, and dynamic hamstring length (p ≤ 0.001). The repeat HSL group improved only in dynamic hamstring length (p = 0.004) and worsened in passive knee extension (p = 0.01) and minimum hip flexion in stance (p = 0.04). Hamstrings in both surgical groups on average remained shorter and slower than controls postoperatively (p ≤ 0.001).

SIGNIFICANCE

The fact that repeat HSL is less effective in improving knee motion is not due to a lack of short or slow hamstrings preoperatively. However, in recurrent crouch, short or slow hamstrings do not usually indicate hamstring dysfunction, and correction of other deformities such as rotational malalignment, fixed knee flexion contractures, patella alta, weak calf muscles, and/or loose heelcords should be considered rather than repeat HSL.

Effect of twister wrap orthosis on foot pressure distribution and balance in diplegic cerebral palsy

OBJECTIVES

To evaluate the effectiveness of twister wrap orthosis (TWO) on foot pressure distribution and postural balance in children with spastic diplegic cerebral palsy (CP).

METHODS

Thirty children with spastic diplegic CP, with ages ranging from 6 to 8 years, were assigned randomly into two groups. The control group received the conventional physical therapy and ankle foot orthosis (AFO), whereas the study group received the same program as the control group in addition to TWO. Measurement of foot pressure distribution using a pressure platform as well as stability indices using the Biodex Stability System was performed before and after 12 weeks of the treatment program.

RESULTS

Both groups showed a significant increase in mean and peak planter pressure on forefoot and rear foot with a significant decrease on mid foot after treatment (P⟨0.05). The study group showed a significant improvement in balance after treatment (P⟨0.05) while there was no significant difference in the control group. After treatment, the study group showed significant improvement in planter pressure and balance compared with the control group (P⟨0.05).

CONCLUSIONS

TWO could provide correction of foot pressure distribution and improve postural balance in children with spastic diplegic CP.

Lower-extremity rotational profile and toe-walking in preschool children with autism spectrum disorder

The aim of this study was to establish the torsional and toe-walking profiles of children with autism spectrum disorder (ASD), and to analyze the correlations between torsion, toe-walking, autism severity score, and age. In total, 79 consecutive children with autism were examined to determine their hip rotations, thigh-foot angle, degree of toe-walking, and autism severity. Femoral and tibial torsion values, of the preschool patients, were compared statistically with age-matched controls. The hip rotation profile of the patients was similar to the normal group. Nearly a half of the patients with ASD present excessive external tibial torsion. The difference in the tibial torsion between patients and normal children was statistically significant. A weak correlation was found only between tibial torsion and the autism severity score, but no correlation was found between the other parameters. External tibial torsion is the cardinal and persistent orthopedic manifestation among patients with ASD. Toe-walking is the second most common such manifestation and is an independent orthopedic feature in these patients. External tibial torsion may potentially contribute toward the described gait abnormalities in patients with ASD.

Strength Training Effects on Muscle Forces and Contributions to Whole-Body Movement in Cerebral Palsy

Strength training is often prescribed for children with cerebral palsy (CP); however, links between strength gains and mobility are unclear. Nine children (age 14 ± 3 years; GMFCS I-III) with spastic CP completed a 6-week strength-training program. Musculoskeletal gait simulations were generated for four children to assess training effects on muscle forces and function. There were increases in isometric joint strength, but no statistical changes in fast-as-possible walking speed or endurance after training. The walking simulations revealed changes in muscle forces and contributions to body center of mass acceleration, with greater forces from the hip muscles during walking most commonly observed. A progressive strength-training program can result in isometric and dynamic strength gains in children with CP, associated with variable mobility outcomes.

Mid-term development of hamstring tendon length and velocity after distal femoral extension osteotomy in children with bilateral cerebral palsy: a retrospective cohort study

AIM

Flexed knee gait can be treated with distal femoral extension osteotomy (DFEO) and additional patellar tendon advancement (PTA) in children with cerebral palsy (CP). This study assesses changes in hamstring muscle tendon length (MTL) and velocity after DFEO (+PTA).

METHOD

Nineteen children (mean age 13y [standard deviation 3y] at surgery) with CP and flexed knee gait who were treated with DFEO (15 limbs) or DFEO+PTA (10 limbs) were retrospectively included in this study. Gait analyses were performed preoperatively (E0), 1 year postoperatively (E1), and for 10 limbs additionally 2 to 5 years postoperatively (E2). Hamstring MTL and velocities were assessed at all examination dates using OpenSim.

RESULTS

Hamstring MTL and velocity did not change significantly over time. From E0 to E1, knee flexion in stance improved for both DFEO and DFEO+PTA (p<0.05), knee flexion in swing only improved after DFEO+PTA (p<0.05). The improved knee flexion in stance and swing was maintained at E2.

INTERPRETATION

DFEO led to a significant improvement in knee kinematics at E1 which was maintained at E2. DFEO seems to prevent recurrent hamstring tightness but does not lead to lengthened or fastened hamstrings.

WHAT THIS PAPER ADDS

Distal femoral extension osteotomy (DFEO) does not change hamstring muscle tendon length. DFEO does not change hamstring lengthening velocity. DFEO leads to a significant improvement in knee kinematics. Changes in knee kinematics after DFEO can be maintained at mid-term. DFEO seems to prevent recurrent hamstring tightness.

OpenSim: Simulating musculoskeletal dynamics and neuromuscular control to study human and animal movement

Movement is fundamental to human and animal life, emerging through interaction of complex neural, muscular, and skeletal systems. Study of movement draws from and contributes to diverse fields, including biology, neuroscience, mechanics, and robotics. OpenSim unites methods from these fields to create fast and accurate simulations of movement, enabling two fundamental tasks. First, the software can calculate variables that are difficult to measure experimentally, such as the forces generated by muscles and the stretch and recoil of tendons during movement. Second, OpenSim can predict novel movements from models of motor control, such as kinematic adaptations of human gait during loaded or inclined walking. Changes in musculoskeletal dynamics following surgery or due to human-device interaction can also be simulated; these simulations have played a vital role in several applications, including the design of implantable mechanical devices to improve human grasping in individuals with paralysis. OpenSim is an extensible and user-friendly software package built on decades of knowledge about computational modeling and simulation of biomechanical systems. OpenSim's design enables computational scientists to create new state-of-the-art software tools and empowers others to use these tools in research and clinical applications. OpenSim supports a large and growing community of biomechanics and rehabilitation researchers, facilitating exchange of models and simulations for reproducing and extending discoveries. Examples, tutorials, documentation, and an active user forum support this community. The OpenSim software is covered by the Apache License 2.0, which permits its use for any purpose including both nonprofit and commercial applications. The source code is freely and anonymously accessible on GitHub, where the community is welcomed to make contributions. Platform-specific installers of OpenSim include a GUI and are available on simtk.org.

Hip- and patellofemoral-joint loading during gait are increased in children with idiopathic torsional deformities

BACKGROUND

Torsional deformities of the femur and tibia are associated with gait impairments and joint pain. Several studies have investigated these gait deviations in children with cerebral palsy. However, relatively little is known about gait deviations in children with idiopathic torsion and debate ensues about the management of these patients.

RESEARCH QUESTION

What are the effects of idiopathic increased femoral neck anteversion and external tibial torsion on lower-limb kinematics, kinetics and joint loading during gait in children and adolescents.

METHODS

Patient-specific musculoskeletal models were created for 12 children/adolescents (mean age of 14 years) with torsional deformities using low-dose biplane radiographic imaging and 3D gait analysis. Comparisons of joint motion and net joint torques during gait were made to an age-matched control group with no torsional deformities. The effects of torsional deformities on muscle and joint contact forces were investigated using two personalised musculoskeletal models: one with normal torsion and another with patient-specific torsion.

RESULTS

Femoral neck anteversion and external tibial torsion for the patients were (mean ± SD) 38° ± 9° and 40° ± 10°, respectively. Patients had increased internal hip rotation and external knee rotation as well as increased pelvic tilt during gait. Additionally, the efficacy of the plantarflexor-knee extension mechanism was diminished. Hip joint contact force was higher in the model with patient-specific torsion. The mediolateral component of the patellofemoral joint contact force was also increased despite the magnitude of the resultant patellofemoral contact force being unchanged.

SIGNIFICANCE

It has been previously established that idiopathic lower-limb torsional deformities alter gait kinematics. However, this study also showed that loading of the hip and patellofemoral joints are increased. This is an important insight for the clinical management of these patients and highlights that idiopathic lower-limb torsional deformities are not a purely cosmetic issue.

Correlation between physical examination and three-dimensional gait analysis in the assessment of rotational abnormalities in children with cerebral palsy

Objective

To evaluate the correlation between physical examination data concerning hip rotation and tibial torsion with transverse plane kinematics in children with cerebral palsy; and to determine which time points and events of the gait cycle present higher correlation with physical examination findings.

Methods

A total of 195 children with cerebral palsy seen at two gait laboratories from 2008 and 2016 were included in this study. Physical examination measurements included internal hip rotation, external hip rotation, mid-point hip rotation and the transmalleolar axis angle. Six kinematic parameters were selected for each segment to assess hip rotation and shank-based foot rotation. Correlations between physical examination and kinematic measures were analyzed by Spearman correlation coefficients, and a significance level of 5% was considered.

Results

Comparing physical examination measurements of hip rotation and hip kinematics, we found moderate to strong correlations for all variables (p<0.001). The highest coefficients were seen between the mid-point hip rotation on physical examination and hip rotation kinematics (rho range: 0.48-0.61). Moderate correlations were also found between the transmalleolar axis angle measurement on physical examination and foot rotation kinematics (rho range 0.44-0.56; p<0.001).

Conclusion

These findings may have clinical implications in the assessment and management of transverse plane gait deviations in children with cerebral palsy.

Long-term Outcome of Internal Tibial Derotation Osteotomies in Children With Cerebral Palsy

BACKGROUND

External tibial torsion (ETT) is a common bony deformity in children with cerebral palsy (CP). The current recommended treatment is tibial derotation osteotomy (TDO) to improve gait biomechanics. Satisfactory short-term results after TDO have been reported but long-term results have not been studied. The purpose of this study was to evaluate the long-term outcome following TDO to correct ETT in ambulatory children with CP.

METHODS

Following IRB approval, gait kinematics and passive range of motion measurements were retrospectively evaluated in children with spastic CP who underwent TDO due to ETT comparing preoperative (E0), short-term postoperative (E1; 1 to 3 y post), and long-term postoperative (E2; >5 y post) results. Limbs were categorized as corrected, undercorrected, or overcorrected at both E1 and E2, by comparing mean tibial rotation (MTR) in gait to a group of typically developing children. Age at surgery, E0 MTR, E0 gait velocity, gross motor function classification system (GMFCS) score, and foot deformity were evaluated to determine their influence on long-term results.

RESULTS

The study sample consisted of 43 legs (with E0 and E2) and 22 legs (with E0, E1, and E2). The mean age at surgery was 10.3±3.4 years (range, 6 to 19.2 y). In the group MTR trended toward improvement moving from -26±17 degrees (E0, external negative) to -16±16 degrees (E1) and relapsed to -23±17 degrees at the long term (P=0.071, E0/E1; P=0.589, E0/E2). Improvement was also seen in the transmalleolar axis (P=0.074), mean ankle rotation, and mean foot orientation (P<0.05, E0/E2). At the long-term evaluation, 16 legs (37%) were found to be in the kinematic corrected group, 25 legs (58%) in the kinematic undercorrected group, and 2 legs (5%) in the kinematic overcorrected group. There were no significant differences between the corrected and undercorrected groups of children with respect to age at surgery, GMFCS, E0 MTR, gait velocity, or foot deformity.

CONCLUSIONS

Although internal TDO improves ETT in the short term, recurrence is frequent with an apparent developmental trend toward external rotation of the tibia.

LEVELS OF EVIDENCE

Level IV-therapeutic study.

Long-term Outcome of External Tibial Derotation Osteotomies in Children With Cerebral Palsy

BACKGROUND

Internal tibial torsion (ITT) is a common boney deformity in children with cerebral palsy (CP). The current recommended treatment is tibial derotation osteotomy (TDO) to improve gait biomechanics. Satisfactory short-term results after TDO have been reported but long-term results have not been studied. The purpose of this study was to evaluate the long-term outcome after external TDO performed to correct ITT in ambulatory children with CP.

METHODS

Following IRB approval, gait kinematics and passive range of motion measurements were retrospectively evaluated in children with spastic CP who underwent TDO due to ITT comparing preoperative (E0), short-term postoperative (E1; 1 to 3 y post), and long-term postoperative (E2; >5 y post) results. Limbs were categorized as corrected, undercorrected, or overcorrected at both E1 and E2, by comparing the subjects mean tibial rotation (MTR) in gait to a group of typically developing children. Age at surgery, preop MTR (at E0), preop gait velocity (at E0), gross motor function classification system score, and foot deformity were evaluated to determine their influence on long-term results.

RESULTS

The study sample consisted of 36 legs (with E0 and E2) and 17 legs (with E0, E1, and E2). The mean age at surgery was 7.4±2.8 (range, 4 to 16.6) years. Comparing the changes over time, kinematic MTR improved from 17±11 degrees initially (E0) to -10±14 degrees short term (E1) and progressed to -23±13 degrees long term (E2) (P<0.05 E0/E1/E2; internal rotation is positive). At E2, 16 legs (44%) were found to be in the kinematic corrected group and 20 legs (56%) in the kinematic overcorrected group. There were no significant differences between the corrected and overcorrected groups of children in respect to age of surgery, gross motor function classification system, E0 MTR, gait velocity, or foot deformity.

CONCLUSIONS

Although external TDO is an accepted form of treatment in children with CP, in the long term a tendency to move into external tibial torsion is common. Therefore, caution is warranted with children who initially present with ITT to avoid overcorrection.

LEVEL OF EVIDENCE

Level IV-therapeutic study.

Effects of multilevel surgery on a flexed knee gait in adults with cerebral palsy

Aims

A flexed knee gait is common in patients with bilateral spastic cerebral palsy and occurs with increased age. There is a risk for the recurrence of a flexed knee gait when treated in childhood, and the aim of this study was to investigate whether multilevel procedures might also be undertaken in adulthood.

Patients and Methods

At a mean of 22.9 months (standard deviation 12.9), after single event multi level surgery, 3D gait analysis was undertaken pre- and post-operatively for 37 adult patients with bilateral cerebral palsy and a fixed knee gait.

Results

There was a significant improvement of indices and clinical and kinematic parameters including extension of the hip and knee, reduction of knee flexion at initial contact, reduction of minimum and mean knee flexion in the stance phase of gait, improved range of movement of the knee and a reduction of mean flexion of the hip in the stance phase. Genu recurvatum occurred in two patients (n = 3 legs, 4%) and an increase of pelvic tilt (> 5°) was found in 12 patients (n = 23 legs, 31%).

Conclusion

Adult patients with bilateral cerebral palsy and a flexed knee gait benefit from multilevel surgery including hamstring lengthening. The risk of the occurence of genu recurvatum and increased pelvic tilt is lower than has been previously reported in children. Cite this article: Bone Joint J 2017;99-B:1256–64.

Tibial derotational osteotomies in two neuromuscular populations: comparing cerebral palsy with myelomeningocele

PURPOSE

To review the outcomes of tibial derotational osteotomies (TDOs) as a function of complication and revision surgery rates comparing a cohort of children with myelodysplasia to a cohort with cerebral palsy (CP).

METHODS

A chart review was completed on TDOs performed in a tertiary referral centre on patients with myelodysplasia or CP between 1985 and 2013 in patients aged > 5 years with > 2 years follow-up. Charts were reviewed for demographics, direction/degree of derotation, complications and need for re-derotation. Two-sample T-tests were used to compare the characteristics of the two groups. Two-tailed chi-square tests were used to compare complications. Generalised linear logit models were used to identify independent risk factors for complication and re-rotation.

RESULTS

The 153 patients (217 limbs) were included. Average follow-up was 7.83 years. Overall complication incidence was 10.14%, including removal of hardware for any reason, with a 4.61% major complication incidence (fracture, deep infection, hardware failure). After adjusting for gender and age, the risk of complication was not statistically significantly different between groups (p = 0.42) nor was requiring re-derotation (p = 0.09). The probability of requiring re-derotation was 31.9% less likely per year increase in age at index surgery (p = 0.005).

CONCLUSION

With meticulous operative technique, TDO in children with neuromuscular disorders is a safe and effective treatment for tibial torsion, with an acceptable overall and major complication rate. The risk of re-operation decreases significantly in both groups with increasing age. The association between age at initial surgery and need for re-derotation should help guide the treatment of children with tibial torsion.

Simulated impacts of ankle foot orthoses on muscle demand and recruitment in typically-developing children and children with cerebral palsy and crouch gait

Passive ankle foot orthoses (AFOs) are often prescribed for children with cerebral palsy (CP) to assist locomotion, but predicting how specific device designs will impact energetic demand during gait remains challenging. Powered AFOs have been shown to reduce energy costs of walking in unimpaired adults more than passive AFOs, but have not been tested in children with CP. The goal of this study was to investigate the potential impact of powered and passive AFOs on muscle demand and recruitment in children with CP and crouch gait. We simulated gait for nine children with crouch gait and three typically-developing children with powered and passive AFOs. For each AFO design, we computed reductions in muscle demand compared to unassisted gait. Powered AFOs reduced muscle demand 15-44% compared to unassisted walking, 1-14% more than passive AFOs. A slower walking speed was associated with smaller reductions in absolute muscle demand for all AFOs (r2 = 0.60-0.70). However, reductions in muscle demand were only moderately correlated with crouch severity (r2 = 0.40-0.43). The ankle plantarflexor muscles were most heavily impacted by the AFOs, with gastrocnemius recruitment decreasing 13-73% and correlating with increasing knee flexor moments (r2 = 0.29-0.91). These findings support the potential use of powered AFOs for children with crouch gait, and highlight how subject-specific kinematics and kinetics may influence muscle demand and recruitment to inform AFO design.

Gastrocnemius operating length with ankle foot orthoses in cerebral palsy

BACKGROUND

Many individuals with cerebral palsy wear ankle foot orthoses during daily life. Orthoses influence joint motion, but how they impact muscle remains unclear. In particular, the gastrocnemius is commonly stiff in cerebral palsy. Understanding whether orthoses stretch or shorten this muscle during daily life may inform orthosis design and rehabilitation.

OBJECTIVES

This study investigated the impact of different ankle foot orthoses on gastrocnemius operating length during walking in children with cerebral palsy.

STUDY DESIGN

Case series, within subject comparison of gastrocnemius operating length while walking barefoot and with two types of ankle foot orthoses.

METHODS

We performed gait analyses for 11 children with cerebral palsy. Each child was fit with two types of orthoses: a dynamic ankle foot orthosis (Cascade dynamic ankle foot orthosis) and an adjustable dynamic response ankle foot orthosis (Ultraflex ankle foot orthosis). Musculoskeletal modeling was used to quantify gastrocnemius musculotendon operating length and velocity with each orthosis.

RESULTS

Walking with ankle foot orthoses could stretch the gastrocnemius more than barefoot walking for some individuals; however, there was significant variability between participants and orthoses. At least one type of orthosis stretched the gastrocnemius during walking for 4/6 and 3/5 of the Gross Motor Functional Classification System Level I and III participants, respectively. AFOs also reduced peak gastrocnemius lengthening velocity compared to barefoot walking for some participants, with greater reductions among the Gross Motor Functional Classification System Level III participants. Changes in gastrocnemius operating length and lengthening velocity were related to changes in ankle and knee kinematics during gait.

CONCLUSION

Ankle foot orthoses impact gastrocnemius operating length during walking and, with proper design, may assist with stretching tight muscles in daily life. Clinical relevance Determining whether ankle foot orthoses stretch tight muscles can inform future orthotic design and potentially provide a platform for integrating therapy into daily life. However, stretching tight muscles must be balanced with other goals of orthoses such as improving gait and preventing bone deformities.

Effectiveness of surgical and non-surgical management of crouch gait in cerebral palsy: A systematic review

BACKGROUND

Cerebral palsy (CP) is a prevalent group of neuromotor disorders caused by early injury to brain regions or pathways that control movement. Patients with CP exhibit a range of functional motor disabilities and pathologic gait patterns. Crouch gait, characterized by increased knee flexion throughout stance, is a common gait pattern in CP that increases energy costs of walking and contributes to ambulatory decline. Our aim was to perform the first systematic literature review on the effectiveness of interventions utilized to ameliorate crouch gait in CP.

METHODS

Comprehensive searches of five medical databases yielded 38 papers with 30 focused on orthopaedic management.

RESULTS

Evidence supports the use of initial hamstring lengthenings and rectus femoris transfers, where indicated, for improving objective gait measures with limited data on improving gait speed or gross motor function. In contrast, evidence argues against hamstring transfers and revision hamstring lengthening, with recent interest in more technically demanding corrective procedures. Only eight studies evaluated alternatives to surgery, specifically strength training, botulinum toxin or orthoses, with inconsistent and/or short-lived results.

CONCLUSIONS

Although crouch in CP is recognized clinically as a complex multi-joint, multi-planar gait disorder, this review largely failed to identify interventions beyond those which directly address sagittal plane knee motion, indicating a major knowledge gap. Quality of existing data was notably weak, with few studies properly controlled or adequately sized. Outcomes from specific procedures are confounded by multilevel surgeries. Successful longer term strategies to prevent worsening of crouch and subsequent functional decline are needed.

LEVEL OF EVIDENCE

Systematic review.

Effect of body weight support variation on muscle activities during robot assisted gait: a dynamic simulation study

BACKGROUND AND OBJECTIVES

While body weight support (BWS) intonation is vital during conventional gait training of neurologically challenged subjects, it is important to evaluate its effect during robot assisted gait training. In the present research we have studied the effect of BWS intonation on muscle activities during robotic gait training using dynamic simulations.

METHODS

Two dimensional (2-D) musculoskeletal model of human gait was developed conjointly with another 2-D model of a robotic orthosis capable of actuating hip, knee and ankle joints simultaneously. The musculoskeletal model consists of eight major muscle groups namely; soleus (SOL), gastrocnemius (GAS), tibialis anterior (TA), hamstrings (HAM), vasti (VAS), gluteus maximus (GLU), uniarticular hip flexors (iliopsoas, IP), and Rectus Femoris (RF). BWS was provided at levels of 0, 20, 40 and 60% during the simulations. In order to obtain a feasible set of muscle activities during subsequent gait cycles, an inverse dynamics algorithm along with a quadratic minimization algorithm was implemented.

RESULTS

The dynamic parameters of the robot assisted human gait such as joint angle trajectories, ground contact force (GCF), human limb joint torques and robot induced torques at different levels of BWS were derived. The patterns of muscle activities at variable BWS were derived and analysed. For most part of the gait cycle (GC) the muscle activation patterns are quite similar for all levels of BWS as is apparent from the mean of muscle activities for the complete GC.

CONCLUSIONS

Effect of BWS variation during robot assisted gait on muscle activities was studied by developing dynamic simulation. It is expected that the proposed dynamic simulation approach will provide important inferences and information about the muscle function variations consequent upon a change in BWS during robot assisted gait. This information shall be quite important while investigating the influence of BWS intonation on neuromuscular parameters of interest during robotic gait training.

Full-Body Musculoskeletal Model for Muscle-Driven Simulation of Human Gait

OBJECTIVE

Musculoskeletal models provide a non-invasive means to study human movement and predict the effects of interventions on gait. Our goal was to create an open-source 3-D musculoskeletal model with high-fidelity representations of the lower limb musculature of healthy young individuals that can be used to generate accurate simulations of gait.

METHODS

Our model includes bony geometry for the full body, 37 degrees of freedom to define joint kinematics, Hill-type models of 80 muscle-tendon units actuating the lower limbs, and 17 ideal torque actuators driving the upper body. The model's musculotendon parameters are derived from previous anatomical measurements of 21 cadaver specimens and magnetic resonance images of 24 young healthy subjects. We tested the model by evaluating its computational time and accuracy of simulations of healthy walking and running.

RESULTS

Generating muscle-driven simulations of normal walking and running took approximately 10 minutes on a typical desktop computer. The differences between our muscle-generated and inverse dynamics joint moments were within 3% (RMSE) of the peak inverse dynamics joint moments in both walking and running, and our simulated muscle activity showed qualitative agreement with salient features from experimental electromyography data.

CONCLUSION

These results suggest that our model is suitable for generating muscle-driven simulations of healthy gait. We encourage other researchers to further validate and apply the model to study other motions of the lower extremity.

SIGNIFICANCE

The model is implemented in the open-source software platform OpenSim. The model and data used to create and test the simulations are freely available at https://simtk.org/home/full_body/, allowing others to reproduce these results and create their own simulations.

Clinical motion analyses over eight consecutive years in a child with crouch gait: a case report

BACKGROUND

This case report provides a unique look at the progression of crouch gait in a child with cerebral palsy over an 8-year time period, through annual physical examinations, three-dimensional gait analyses, and evaluation of postural balance. Our patient received regular botulinum toxin-A injections, casting, and physical therapy but no surgical interventions.

CASE PRESENTATION

A white American boy with spastic diplegic cerebral palsy was evaluated annually by clinical motion analyses, including physical examination, joint kinematics, electromyography, energy expenditure, and standing postural balance tests, from 6 to 13 years of age. These analyses revealed that the biomechanical factors contributing to our patient's crouch gait were weak plantar flexors, short and spastic hamstrings, moderately short hip flexors, and external rotation of the tibiae. Despite annual recommendations for surgical lengthening of the hamstrings, the family opted for non-surgical treatment through botulinum toxin-A injections, casting, and exercise. Our patient's crouch gait improved between ages 6 and 9, then worsened at age 10, concurrent with his greatest body mass index, increased plantar flexor weakness, increased standing postural sway, slowest normalized walking speed, and greatest walking energy expenditure. Although our patient's maximum knee extension in stance improved by 14 degrees at 13 years of age compared to 6 years of age, peak knee flexion in swing declined, his ankles became more dorsiflexed, his hips became more internally rotated, and his tibiae became more externally rotated. From 6 to 9 years of age, our patient's minimum stance-phase knee flexion varied in an inverse relationship with his body mass index; from 10 to 13 years of age, changes in his minimum stance-phase knee flexion paralleled changes in his body mass index.

CONCLUSIONS

The motor deficits of weakness, spasticity, shortened muscle-tendon lengths, and impaired selective motor control were highlighted by our patient's clinical motion analyses. Overall, our patient's crouch gait improved mildly with aggressive non-operative management and a supportive family dedicated to regular home exercise. The annual clinical motion analyses identified changes in motor deficits that were associated with changes in the child's walking pattern, suggesting that these analyses can serve to track the progression of children with spastic cerebral palsy.

Muscle parameters estimation based on biplanar radiography

The evaluation of muscle and joint forces in vivo is still a challenge. Musculo-Skeletal (musculo-skeletal) models are used to compute forces based on movement analysis. Most of them are built from a scaled-generic model based on cadaver measurements, which provides a low level of personalization, or from Magnetic Resonance Images, which provide a personalized model in lying position. This study proposed an original two steps method to access a subject-specific musculo-skeletal model in 30 min, which is based solely on biplanar X-Rays. First, the subject-specific 3D geometry of bones and skin envelopes were reconstructed from biplanar X-Rays radiography. Then, 2200 corresponding control points were identified between a reference model and the subject-specific X-Rays model. Finally, the shape of 21 lower limb muscles was estimated using a non-linear transformation between the control points in order to fit the muscle shape of the reference model to the X-Rays model. Twelfth musculo-skeletal models were reconstructed and compared to their reference. The muscle volume was not accurately estimated with a standard deviation (SD) ranging from 10 to 68%. However, this method provided an accurate estimation the muscle line of action with a SD of the length difference lower than 2% and a positioning error lower than 20 mm. The moment arm was also well estimated with SD lower than 15% for most muscle, which was significantly better than scaled-generic model for most muscle. This method open the way to a quick modeling method for gait analysis based on biplanar radiography.

The role of altered proximal femoral geometry in impaired pelvis stability and hip control during CP gait: A simulation study

Children with cerebral palsy (CP) often present aberrant hip geometry, more specifically increased femoral anteversion and neck-shaft angle. Furthermore, altered gait patterns are present within this population. This study analyzed the effect of aberrant femoral geometry, as present in subjects with CP, on the ability of muscles to control hip and knee joint kinematics. Given the specific gait deficits observed during crouch gait, increased ability to abduct, externally rotate the hip and extend the knee and hip were denoted as beneficial effects. We ran dynamic simulations of CP and normal gait using two musculoskeletal models, one reflecting normal femoral geometry and one reflecting proximal femoral deformities. The results show that the combination of aberrant bone geometry and CP-specific gait characteristics beneficially increased the ability of gluteus medius and maximus to extend the hip and knee. In contrast, the potentials of the hamstrings to extend the hip decreased whereas the potentials to flex the knee increased. These changes closely followed the observed changes in the muscle moment arm lengths. In conclusion, this study emphasizes the concomitant effect of the presence of proximal femoral deformity and CP gait characteristics on the muscle control of hip and knee joint kinematics during single stance. Not accounting for subject-specific geometry will affect the calculated muscles' potential during gait. Therefore, the use of generic models to assess muscle function in the presence of femoral deformity and CP gait should be treated with caution.