Femoral muscle attachment locations in children and adults, and their prediction from clinical measurement

Predictive estimation of ovine hip joint centers: A regression approach

Estimation of the hip joint center in ovine biomechanical analysis is often overlooked or estimated using a marker on the greater trochanter which can result in large errors that propagate through subsequent analyses. The purpose of this study was to develop a novel method of estimating the hip joint centers in sheep to facilitate more accurate analysis of ovine biomechanics. CT scans from 16 sheep of varying ages, weight, sex, and phenotypes were acquired and the data was used to calculate the known hip joint center by sphere fitting the femoral head. Anatomical measurements and additional subject information were used to create a variety of regression models to estimate the hip joint centers in absence of CT data. The best regression equation created utilized markers placed on the tuber coxae and tuber ischii of the pelvis and resulted in a mean 3D Euclidean distance error of 6.43 ± 2.22 mm (mean ± standard deviation) between the known and estimated hip joint center. The regression models produced allow for more detailed, accurate and robust analysis of sheep biomechanics.

Sex differences in linear bone measurements occur following puberty but do not influence femoral or tibial torsion

Torsional, angular, and linear measurements in a paediatric population are clinically important but not well defined and understood. Different methods of measurement and discrepancies between assessors leads to a lack of understanding of what should be defined as typical or atypical for the growing skeleton. From a large dataset of 333 paediatric CT scans, we extracted three-dimensional torsional, angular, and linear measurements from the pelvis, femur, and tibia/fibula. Sex differences in linear measurements were observed in bones of children aged 13+ (around puberty), but femoral and tibial torsion were similar between males and females. The rotational profile (femoral anteversion minus tibial torsion) tended to increase with growth. Epicondylar, condylar, and malleolar widths were smaller in females than males for the same bone length after the age of 13 years, which could explain why females may be more at risk for sport injuries during adolescence. This rich dataset can be used as an atlas for researchers and clinicians to understand typical development of critical rotational profiles and linear bone measurements in children.

The Utility of Lesser Trochanter Version to Estimate Femoral Anteversion in Total Hip Arthroplasty: A Three-Dimensional Computed Tomography Study

Objective: Femoral anteversion is an important parameter that can prevent complication following total hip arthroplasty (THA) caused by improper positioning of the implant. However, assessing the femoral anteversion can be challenging in situations with significant defect of the femoral neck. In this study, the lesser trochanter version was nominated as alternative parameter to femoral anteversion. So, the main objective of this study is to determine whether the femoral anteversion correlates with the lesser trochanter version. Design: Retrospective study. Methods: Three-dimensional images of 100 femora were generated and their femoral anteversion and lesser trochanter version was measured. Correlation between the parameters were calculated. Results: The mean lesser trochanter version was 38.54° ± 7.86° (mean ± SD), while the mean femoral anteversion was 11.84° ± 10.06°. The lesser trochanter version was inversely correlated with the femoral anteversion with a correlation coefficient of −0.72. Conclusions: The lesser trochanter should be considered as an additional bony landmark to assess proper implant positioning in THA.

A multi-scale modelling framework combining musculoskeletal rigid-body simulations with adaptive finite element analyses, to evaluate the impact of femoral geometry on hip joint contact forces and femoral bone growth

Multi-scale simulations, combining muscle and joint contact force (JCF) from musculoskeletal simulations with adaptive mechanobiological finite element analysis, allow to estimate musculoskeletal loading and predict femoral growth in children. Generic linearly scaled musculoskeletal models are commonly used. This approach, however, neglects subject- and age-specific musculoskeletal geometry, e.g. femoral neck-shaft angle (NSA) and anteversion angle (AVA). This study aimed to evaluate the impact of proximal femoral geometry, i.e. altered NSA and AVA, on hip JCF and femoral growth simulations. Musculoskeletal models with NSA ranging from 120° to 150° and AVA ranging from 20° to 50° were created and used to calculate muscle and hip JCF based on the gait analysis data of a typically developing child. A finite element model of a paediatric femur was created from magnetic resonance images. The finite element model was morphed to the geometries of the different musculoskeletal models and used for mechanobiological finite element analysis to predict femoral growth trends. Our findings showed that hip JCF increase with increasing NSA and AVA. Furthermore, the orientation of the hip JCF followed the orientation of the femoral neck axis. Consequently, the osteogenic index, which is a function of cartilage stresses and defines the growth rate, barely changed with altered NSA and AVA. Nevertheless, growth predictions were sensitive to the femoral geometry due to changes in the predicted growth directions. Altered NSA had a bigger impact on the growth results than altered AVA. Growth simulations based on mechanobiological principles were in agreement with reported changes in paediatric populations.

Estimation of the hip joint centre in human motion analysis: a systematic review

BACKGROUND

Inaccuracies in locating the three-dimensional position of the hip joint centre affect the calculated hip and knee kinematics, force- and moment-generating capacity of muscles and hip joint mechanics, which can lead to incorrect interpretations and recommendations in gait analysis. Several functional and predictive methods have been developed to estimate the hip joint centre location, and the International Society of Biomechanics recommends a functional approach for use with participants that have adequate range of motion at the hip, and predictive methods in those with insufficient range of motion. The purpose of the current systematic review was to substantiate the International Society of Biomechanics recommendations. This included identifying the most accurate functional and predictive methods, and defining 'adequate' range of motion.

METHODS

A systematic search with broad search terms was performed including five databases.

FINDINGS

The systematic search yielded to 801 articles, of which 34 papers were included. Eleven different predictive and 13 different functional methods were identified. The results showed that the geometric sphere fit method and Harrington equations are the most accurate functional and predictive approaches respectively that have been evaluated in vivo.

INTERPRETATION

In regard to the International Society of Biomechanics recommendations, the geometric sphere fit method should be used in people with sufficient active hip range of motion and the Harrington equations should be used in patients without sufficient hip range of motion. Multi-plane movement trials with at least 60° of flexion-extension and 30° of ab-adduction range of motion are suggested when using functional methods.

A validation study for estimation of femoral anteversion using the posterior lesser trochanter line: an analysis of computed tomography measurement

The aim of this study was to introduce a simple and reliable intraoperative reference guide to reproduce the normal femoral anteversion during total hip arthroplasty (THA). We hypothesized that the posterior lesser trochanter line (PLTL) could be a useful guide for estimating femoral anteversion during THA. We conducted a study of 56 men (112 hips) to evaluate the relationship between the PLTL and the femoral anteversion using computed tomography scans. The mean femoral anteversion was 9.0° ± 8.1° (range, -16.2° to 32.9°). The PLTL angle correlated (r(2) = 0.12, P < 0.05) with the femoral anteversion. We found a constant relationship between the PLTL and femoral anteversion, and the PLTL may be used as a guide for estimating the femoral stem anteversion during femoral stem fixation.

Kinematic determinants of anterior knee pain in cerebral palsy: a case-control study

OBJECTIVE

To quantify the role patellofemoral and tibiofemoral kinematics may play in development of anterior knee pain (AKP) in individuals with cerebral palsy (CP).

DESIGN

Case-control.

SETTING

Clinical research center.

PARTICIPANTS

Knees from individuals with diagnosed CP (n=20) and control knees (n=40) were evaluated. Controls were matched for sex and age based on the group average. Matching by height and weight was a secondary priority. Subjects in the control cohort were asymptomatic with no history of lower leg abnormalities, surgery, or major injury. Only individuals who were physically capable of sustaining slow, cyclic knee flexion-extension for 2.5 minutes and had no contraindications to magnetic resonance imaging were enrolled. Both groups were samples of convenience.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Three-dimensional patellofemoral and tibiofemoral joint kinematics, acquired during active leg extension, under volitional control.

RESULTS

Participants with CP and AKP (n=8) demonstrated significantly greater patellofemoral extension, valgus rotation, and superior and posterior displacement relative to controls and to the subgroup of participants with CP and no AKP (n=12). Patellofemoral extension discriminated AKP in individuals with CP with 100% accuracy.

CONCLUSIONS

In quantifying the 3-dimensional, in vivo knee joint kinematics during a volitional extension task, kinematic markers that discriminate AKP in individuals with CP were identified. This provides an ability to predict which individuals with CP are most likely to develop AKP and could enable aggressive conservative treatment, aimed at reducing patella alta and excessive patellofemoral extension, to be prescribed before considering surgical options. The current findings will likely lead to improved clinical diagnostics and interventions for individuals with CP, with the ultimate goal of helping maintain, if not improve, functional mobility throughout the lifespan.

Calf muscle-tendon lengths before and after Tendo-Achilles lengthenings and gastrocnemius lengthenings for equinus in cerebral palsy and idiopathic toe walking

The calf muscle-tendon lengths in children exhibiting equinus gait in two clinical populations, cerebral palsy (CP) and idiopathic toe walking (ITW), were examined to compare the effects of diagnosis and two different surgical procedures, Tendo-Achilles lengthening (TAL) versus Vulpius procedure (VP) gastrocnemius recession. Pre- and post-surgical gait data were obtained from 38 subjects (58 limbs) and 38 age-matched controls. Peak muscle-tendon lengths increased following surgery in 84% of limbs. For medial gastrocnemius (MGAS) and lateral gastrocnemius (LGAS) in stance, muscle-tendon lengths increased significantly following TAL surgeries but were not significantly different pre- and post-VP surgeries. For soleus (SOL) (swing and stance) and MGAS and LGAS (swing), muscle-tendon lengths increased significantly following both TAL and VP surgeries. Pre-operatively, muscle-tendon lengths were significantly shorter for the TAL group compared to the VP group; however, post-operatively the lengths were not significantly different between the surgeries. There were no significant differences between CP and ITW patients or indications that the surgery affected the groups differently. The change in length following surgery was well correlated to the subjects' initial muscle-tendon length.

Correlation between lower limb bone morphology and gait characteristics in children with spastic diplegic cerebral palsy

BACKGROUND

Children with spastic diplegic cerebral palsy (CP) exhibit abnormal walking patterns and frequently develop lower limb, long bone deformities. It is important to determine if any relationship exists between bone morphology and movement of the lower limbs in children with CP. This is necessary to explain and possibly prevent the development of these deformities.

METHODS

This study investigated the relationship between bone morphology and gait characteristics in 10 healthy children (age range, 6-13 years; mean, 8 years 7 months; SD, +/-2 years 7 months) and 9 children with spastic diplegic CP (age range, 6-12 years; mean, 9 years 2.5 months; SD, +/-1 year 10.5 months) with no previous surgery. Three-dimensional magnetic resonance images were analyzed to define bone morphology. Morphological characteristics, such as the bicondylar angle, neck-shaft angle, anteversion angle, and tibial torsion, were measured. Gait analyses were performed to obtain kinematic characteristics of CP and normal children's gait. Principal component analysis was used to reduce the dimensionality of 27 parameters (26 kinematics variables and age of the children) to 8 independent variables. Correlations between gait and bone morphology were determined for both groups of children.

RESULTS

Results indicated that in healthy children, hip adduction was correlated with neck-shaft and bicondylar angles. In CP children, pelvic obliquity correlated with neck-shaft angle, and foot rotation with bicondylar angle. In the transverse plane, hip and pelvic rotational kinematics were related to femoral anteversion in healthy children and to tibial torsion in CP children.

CONCLUSION

Different development was observed in femoral and tibial morphology between CP and healthy children. The relationship between bone shape and dynamic gait patterns also varied between these populations. This needs to be taken into account, particularly when surgical treatment is planned.

CLINICAL RELEVANCE

Understanding the relationship between gait abnormality and bone deformity could eventually help in developing treatment regimens that will address gait deviations at the correct level and promote normal bone growth in children with CP.

A new anatomically based protocol for gait analysis in children

Human movement analysis still suffers from the weakness of the currently used protocols for data collection and reduction. Reliable data comparisons and precise functional assessment require anatomically based definitions of the reference axes and frames, and therefore careful identification and tracking of the landmarks. When impaired children are analysed, the marker-set and other measurement procedures have to be minimised to reduce the time of the experiment and ensure patient collaboration. A new protocol is proposed for the analysis of pelvis and lower limb motion obtained as a compromise between these two requirements. A marker-set is proposed which involves the attachment of 22 skin markers, the calibration by a pointer of 6 anatomical landmarks, and the identification of the hip joint centre by a prediction approach. Anatomical reference frames and joint rotations are defined according to current recommendations. The protocol was assessed by analysing a single child in several repetitions by different examiners, and a population of 10 healthy children, mean age 9.7-years-old. The entire analysis was repeated after subtraction of the offset by static posture angles. The minimum and maximum means of the standard deviations from five examiners of the same child were respectively 2.1 degrees in pelvic obliquity and 6.8 degrees in knee rotation. The minimum and maximum means of the standard deviations from the 10 healthy children were 2.1 degrees in pelvic obliquity and 9.6 degrees in knee internal-external rotation. The protocol is feasible and allows 3D anatomical-based measurements of segment and joint motion and data sharing according to current standards.

Prediction of the hip joint centre in adults, children, and patients with cerebral palsy based on magnetic resonance imaging

The location of the hip joint centre (HJC) is required for calculations of hip moments, the location and orientation of the femur, and muscle lengths and lever arms. In clinical gait analysis, the HJC is normally estimated using regression equations based on normative data obtained from adult populations. There is limited relevant anthropometric data available for children, despite the fact that clinical gait analysis is predominantly used for the assessment of children with cerebral palsy. In this study, pelvic MRI scans were taken of eight adults (ages 23-40), 14 healthy children (ages 5-13) and 10 children with spastic diplegic cerebral palsy (ages 6-13). Relevant anatomical landmarks were located in the scans, and the HJC location in pelvic coordinates was found by fitting a sphere to points identified on the femoral head. The predictions of three common regression equations for HJC location were compared to those found directly from MRI. Maximum absolute errors of 31 mm were found in adults, 26 mm in children, and 31 mm in the cerebral palsy group. Results from regression analysis and leave-one-out cross-validation techniques on the MRI data suggested that the best predictors of HJC location were: pelvic depth for the antero-posterior direction; pelvic width and leg length for the supero-inferior direction; and pelvic depth and pelvic width for the medio-lateral direction. For single-variable regression, the exclusion of leg length and pelvic depth from the latter two regression equations is proposed. Regression equations could be generalised across adults, children and the cerebral palsy group.