Trunk and lower limb biomechanics during stair climbing in people with and without symptomatic femoroacetabular impingement

BackgroundFemoroacetabular impingement is a pathomechanical hip condition leading to pain and impaired physical function. It has been shown that those with femoroacetabular impingement exhibit altered gait characteristics during level walking and stair climbing, and decreased muscle force production during isometric muscle contractions. However, no studies to-date have looked at trunk kinematics or muscle activation during dynamic movements such as stair climbing in this patient population. The purpose of this study was to compare biomechanical outcomes (trunk and lower limb kinematics as well as lower limb kinetics and muscle activation) during stair climbing in those with and without symptomatic femoroacetabular impingement.MethodsTrunk, hip, knee and ankle kinematics, as well as hip, knee and ankle kinetics and muscle activity of nine lower limb muscles were collected during stair climbing for 20 people with clinical and radiographic femoroacetabular impingement and compared to 20 age- and sex-matched pain-free individuals.FindingsThose with femoroacetabular impingement ascended the stairs slower (effect size = 0.82), had significantly increased peak trunk forward flexion angles (effect size = 0.99) and external hip flexion moments (effect size = 0.94) and had decreased peak external knee flexion moments (effect size = 0.90) compared to the control group.InterpretationFindings from this study indicate that while those with and without femoroacetabular impingement exhibit many biomechanical similarities when ascending stairs, differences in trunk forward flexion and joint kinetics indicate some important differences. Further longitudinal research is required to elucidate the cause of these differences as well as the clinical relevance.     

Kinematic and kinetic differences during walking in patients with and without symptomatic femoroacetabular impingement

BackgroundFemoroacetabular impingement is a common hip pathology resulting in pain and impaired physical function. However, very little is known about gait differences between those with and without femoroacetabular impingement. Thus, the purpose of this study was to compare three-dimensional gait kinematics and kinetics between those with femoroacetabular impingement and a healthy, pain-free control group.MethodsThree-dimensional gait analysis was conducted on 30 individuals with symptomatic femoroacetabular impingement scheduled for surgery and 30 pain-free controls. Spatiotemporal and peak hip kinematics and joint moments were compared between the two groups. Ensemble averages were also calculated for kinematic and kinetic profiles across the gait cycle in all three planes of movement for visual inspection.FindingsParticipants with femoroacetabular impingement walked slower and with significantly smaller cadences than those in the control group. Kinematically, the impingement group exhibited significantly less peak hip extension, adduction and internal rotation during stance, with effect sizes ranging from 0.48 (adduction) to 1.00 (internal rotation). Finally, those with FAI exhibited significantly less peak external hip flexion (effect size = 0.52) and external rotation (effect size = 0.85) moments than the control group.InterpretationIndividuals with femoroacetabular impingement exhibit differences in gait kinematics in all planes of motion compared to those with without FAI. These findings support the need for focused neuromuscular reconditioning across all movement directions in this patient group.     

Association between severity of hip chondrolabral injuries,dynamic hip muscle strength and quality of life: A cross-sectional study in patients with femoroacetabular impingement syndrome scheduled for hip arthroscopy

BackgroundWe assessed the association between: the severity of hip chondral or labral pathology with dynamic hip muscle strength or quality of life in patients with femoroacetabular impingement syndrome scheduled for hip arthroscopy. We also assessed the association between dynamic hip muscle strength with quality of life.MethodsEighty-three participants with femoroacetabular impingement syndrome scheduled for hip arthroscopy were included. We measured dynamic hip abduction and adduction muscle strength with an isokinetic dynamometer (Nm/kg), and quality of life with the iHoT-33 questionnaire. The severity of hip chondrolabral pathologies was scored using the modified Beck classification. Linear regression analyses were conducted to assess the association between severity of hip chondral or labral pathology with dynamic hip muscle strength and quality of life.FindingsThe regression analyses showed no association between the (i) severity of hip chondral (adjusted r²: 0.14) or labral (adjusted r²: 0.08) pathology and quality of life (P > 0.05), (ii) between the severity of hip chondral or labral pathology and dynamic hip abduction and adduction muscle strength (P > 0.05). Significant correlation was observed for quality of life and hip abduction (adjusted r²:0.29; P < 0.001) or adduction (adjusted r²: 0.32; P < 0.001) muscle strength.InterpretationThe severity of hip chondral or labral pathologies were not associated with quality of life or dynamic hip muscle strength in participants with femoroacetabular impingement syndrome. Greater dynamic hip abduction and adduction muscle strength were associated with better quality of life in participants with femoroacetabular impingement syndrome scheduled for hip arthroscopy.     

Hüftarthroskopie bei Koxarthrose

Based on the development of surgical techniques the results of clinical studies and regular “hands-on” workshops, hip arthroscopy has become widely accepted. At the same time it is becoming more frequent especially in younger and active patients with osteoarthritis of the hip joint to request a joint-preserving surgical treatment. In current retrospective clinical studies the results of hip arthroscopy were significantly worse with higher grades of osteoarthritis than with an intact joint cartilage. Nevertheless, some good indications for hip arthroscopy in cases of osteoarthritis were found. Mechanical symptoms are frequently improved by the removal of loose osteochondral fragments. A recontouration of the head/neck junction with subsequent anterolateral capsulotomy increases the range of motion in osteoarthritic patients with a femoroacetabular impingement. Patients have to achieve a realistic attitude towards the possibly minimal improvement in complaints in the clinical outcome of hip arthroscopy in cases of osteoarthritis.     

Sinnvolle Indikationen zur Hüftarthroskopie

In addition to its diagnostic precision, arthroscopy has proven to be a successful minimally invasive operative treatment for various traumatic and nontraumatic disorders of the hip joint. The list of indications has been growing in recent years. Hip arthroscopy is not only used as a diagnostic tool in unclear hip pain and as a therapeutic option for removal of loose bodies or resection of cartilage or ligamentous tears. Hip arthroscopy has also become a reconstructive technique for treatment of cartilage defects, femoroacetabular impingement, or other pathologic conditions of the hip joint. The following report presents beneficial indications for arthroscopy of the hip joint taking anatomical and surgical aspects into consideration.     

The pelvifemoral rhythm in cam-type femoroacetabular impingement

Background

There is growing evidence that femoroacetabular impingement is a potentially important risk factor for the development of early idiopathic osteoarthritis in the nondysplastic hip. Understanding of affected joint kinematics is a basic prerequisite in the evaluation of mechanical disorders in a clinical and research oriented setting. The aim of the present study was to compare pelvifemoral kinematics between subjects diagnosed with femoroacetabular impingement and healthy controls.

Methods

The authors collected motion data of the femur and pelvis on a total of 43 hips – 19 cam impingement hips and 24 healthy controls – using a validated electromagnetic tracking device. The pelvifemoral rhythm in supine position was defined during both active and passive hip flexion and statistically compared between both groups.

Findings

A significant increase in posterior pelvic rotation was observed during active hip flexion in the femoroacetabular impingement group compared with the control group (P < 0.001). During passive hip flexion, however, posterior pelvic rotation between the impingement group and the controls did not differ significantly (P = 0.628).

Interpretation

Posterior pelvic rotation during active high-end hip flexion is increased in femoroacetabular impingement, indicating the presence of an active compensational mechanism that decreases the extent of harmful joint conflict during high-flexion activities.     

Restoring range of motion in reduced acetabular version by increasing femoral antetorsion – What about joint load?

BackgroundAcetabular retroversion results in reduced range of motion, and is thought to contribute to femoroacetabular impingement. Severe retroversion can be corrected with a periacetabular osteotomy, which is a technically demanding intervention. In this study, we investigated whether increasing femoral antetorsion is a potential alternative to restore the range of motion and how this approach would affect hip joint loading.MethodsSix different finite element models of the same subject were built from MRI and used to simulate different load scenarios during stance phase, including healthy and pathological configurations with different acetabular version and femoral torsion angles. The subject's gait was analysed in our gait lab and motion data as well as joint reaction forces were integrated into the model. Hip range of motion, hip abductor muscle forces as well as localization and magnitude of hip joint loads were determined.FindingsThe negative effects of acetabular retroversion on hip range of motion including flexion and internal rotation can be reversed by increasing femoral anteversion. The rotation of the femur furthermore affected muscular functionality by shortening the moment arms of the hip abductor muscles, resulting in increased abductor muscle forces, joint reaction forces and hip joint loading.InterpretationEven though increased femoral antetorsion can compensate for the loss of hip range of motion due to reduced acetabular version, rotational ostotomy of the proximal femur is likely to alter muscular moment arms and therefore increase hip joint load, conflicting the goal of a long-term healthy joint.     

Biomechanics during cross-body lunging in individuals with and without painful cam and/or pincer morphology

BackgroundFemoroacetabular impingement is a patho-mechanical hip condition that can lead to restrictions in hip motion, particularly in end-range hip flexion, adduction and/or internal rotation. Radiographic evidence of femoroacetabular impingement – cam and/or pincer morphology - is prevalent in the general and athletic populations. There is, however, a lack of studies that have analyzed the performance of sport-specific movements in people possessing these morphologies. Therefore, the purpose of this study was to compare cross-body lunge biomechanics between individuals with and without painful cam and/or pincer morphology.MethodsThis was an exploratory, cross-sectional study where nine participants with cam and/or pincer morphology and symptoms, thirteen participants with asymptomatic cam and/or pincer morphology, and eleven pain-free controls performed the cross-body lunge during a single session. Trunk, pelvis, hip, knee and ankle kinematics, as well as hip, knee and ankle kinetics and vertical ground reaction forces were examined.FindingsOverall, the groups performed the movement similarly, with most variables statistically similar between groups. However, pelvis sagittal plane excursion throughout the entire cross-body lunge was significantly larger in those with cam and/or pincer morphology and symptoms compared to those with asymptomatic cam and/or pincer morphology (P = .046, effect size = 0.98).InterpretationThe results of this study show that cross-body lunge performance is similar across individuals with and without painful cam and/or pincer morphology. However, future research should aim to better understand pelvis biomechanics during sporting activities, as pelvis sagittal plane excursion may have important implications in rehabilitation and sport performance.     

Femoroacetabular impingement syndrome: Nonarthritic hip pain in young adults

OBJECTIVE

To provide family physicians with an approach to the diagnosis and management of nonarthritic hip pain in young adults, which might occur as a result of femoroacetabular impingement syndrome.

SOURCES OF INFORMATION

A MEDLINE search from 1950 to April 2007 was carried out using the MeSH terms femoroacetabular, impingement, hip, and syndrome. The existing literature consists of level II studies. To date, randomized controlled trials have not been carried out.

MAIN MESSAGE

Nonarthritic hip pain in the active adult population has long been a difficult clinical problem to manage. Arthroplasty is rarely an appropriate option and the usual conservative therapies for musculoskeletal problems are frequently ineffective. Recently, abnormal impingement between the acetabulum and femoral head-neck junction, or femoroacetabular impingement syndrome, has been recognized as a relatively common and possibly prearthritic cause of these symptoms. Family physicians can identify these patients by recognizing the clinical history and through specific examination findings. Emerging evidence suggests that early surgical intervention improves function and perhaps prevents or delays the onset of degenerative changes in the hip joint.

CONCLUSION

Family physicians can identify patients with possible femoroacetabular impingement syndrome and play an important role in the appropriate management of these cases.     

Hip kinematics and kinetics in persons with and without cam femoroacetabular impingement during a deep squat task

BackgroundPrevious studies have indicated that hip and pelvis kinematics may be altered during functional tasks in persons with femoroacetabular impingement. The purpose of this study was to compare hip and pelvis kinematics and kinetics during a deep squat task between persons with cam femoroacetabular impingement and pain-free controls.MethodsFifteen persons with cam femoroacetabular impingement and 15 persons without cam femoroacetabular impingement performed a deep squat task. Peak hip flexion, abduction, and internal rotation, and mean hip extensor, adductor, and external rotator moments were quantified. Independent t-tests (α < 0.05) were used to evaluate between group differences.FindingsCompared to the control group, persons with cam femoroacetabular impingement demonstrated decreased peak hip internal rotation (15.2° (SD 9.5°) vs. 9.4° (SD 7.8°); P = 0.041) and decreased mean hip extensor moments (0.56 (SD 0.12) Nm/kg vs. 0.45 (SD 0.15) Nm/kg; P = 0.018). In addition persons in the cam femoroacetabular impingement group demonstrated decreased posterior pelvis tilt during squat descent compared to the control group, resulting in a more anteriorly tilted pelvis at the time peak hip flexion (12.5° (SD 17.1°) vs. 23.0° (SD 12.4°); P = 0.024).InterpretationThe decreased hip internal rotation observed in persons with cam femoroacetabular impingement may be the result of bony impingement. Furthermore, the decrease in posterior pelvis tilt may contribute to impingement by further approximating the femoral head–neck junction with the acetabulum. Additionally, decreased hip extensor moments suggest that diminished hip extensor muscle activity may contribute to decreased posterior pelvis tilt.     

Dynamic hip kinematics in patients with hip osteoarthritis during weight-bearing activities

BackgroundThere is an interest in quantifying the hip kinematics of patients with end-stage hip disorders before total hip arthroplasty. The purpose of the present study was to obtain dynamic hip kinematics under four different conditions, including deep flexion and rotation, in patients with osteoarthritis of the hip.MethodsContinuous X-ray images were obtained in 14 patients during gait, chair-rising, squatting, and twisting, using a flat panel X-ray detector. These patients received computed tomography scan to generate virtual digitally reconstructed radiographs. The density-based digitally reconstructed radiographs were then compared with the serial X-ray images acquired using image correlations. These 3D-to-2D model-to-image registration techniques determined the 3D positions and orientations of the pelvis and femur during the movement cycle of each activity.FindingsFor gait, chair-rising, and squatting, the maximum hip flexion angles averaged 22°, 64°, and 68°, respectively. The pelvis was tilted anteriorly by an average of around 7° during the full gait cycle. For chair-rising and squatting, the maximum absolute values of anterior/posterior pelvic tilt averaged 8°/17° and 6°/18°, respectively. Hip flexion showed maximum flexion angle on the way of movement due to further anterior pelvic tilt during both chair-rising and squatting. For twisting, the maximum absolute values of internal/external hip rotation averaged 3°/13°.InterpretationPatients with hip osteoarthritis prior to total hip arthroplasty demonstrated the limited ranges of coordinated motion of the pelvis, femur, and hip joint during each activity, especially in deeply flexed and rotated postures.     

Three-dimensional gait analysis in women with a total hip arthroplasty

OBJECTIVES. The purposes of this study were: (1) to identify the primary (hip) and secondary (neighboring joints) impairments during gait in subjects with a total hip arthroplasty total hip arthroplasty, (2) to determine which impairments persist when controlling for gait speed and (3) to study the relationships between primary and secondary impairments in order to describe the locomotor strategies used by these patients.DESIGN. This cross-sectional study compared the gait patterns of women with a total hip arthroplasty to those of healthy women.BACKGROUND. Several studies have reported residual hip impairments in the sagittal plane during gait after a total hip arthroplasty. There is, however, a substantial lack of knowledge in regard to the changes at the neighboring joints and in the other planes of movement.METHODS. Subjects have been examined during a gait laboratory testing session including the simultaneous recording of three-dimensional kinematics and ground reaction forces on one side, and bilateral activation of six lower limb muscles.RESULTS. A significant decrease of 20% in the hip extensor moment of force during the early stance phase was correlated (R(2)=43%) with a significant decrease of 14% in gait speed. Moreover, a significant decrease of 59% in the range of hip extension at the end of the stance phase was observed together with secondary impairments such as a significant increase in the anterior pelvic rotation, in knee flexion and in ankle dorsiflexion. Lastly, a significant increase in ipsilateral bending of the trunk during the single limb support on the operated limb was concomitant with a significant decrease in the hip abductor moment of force.CONCLUSIONS. The decrease in gait speed and the persistence of abnormal gait patterns one year after the total hip arthroplasty were associated respectively with a decrease in the hip extensor moment of force and with a decrease in the range of hip extension (sagittal plane) or in the hip abductor moment of force (frontal plane).RelevanceThe data provided in this paper may serve as guidelines to establish rehabilitation programs designed to restore optimal locomotor function.     

Comparison of total hip arthroplasty surgical approaches by Statistical Parametric Mapping

BackgroundThe most common surgical approaches in use for total hip arthroplasty are the lateral and posterior. When comparing these approaches in terms of gait biomechanics, studies usually rely on pre-defined discrete variables related to the events of gait cycle. However, this analysis may miss differences in other parts of the movement pattern that are not explored. We applied Statistical Parametric Mapping to compare hip kinematics between patients who underwent arthroplasty using either a lateral or posterior approach, contrasting these results with discrete variable analysis.MethodsTwenty-two participants (11 lateral, 11 posterior; age between 50 and 80 years) underwent gait analysis before, 3 weeks and 12 weeks after hip arthroplasty. One-dimensional (e.g. time-varying) trajectories and zero-dimensional (e.g. peak extension) discrete variables were used to assess differences between groups in each plane of hip movement (sagittal, frontal, and transverse).FindingsOne-dimensional and zero-dimensional analyses found no significant differences between groups. Statistical Parametric Mapping revealed that both groups presented significant changes over time in hip adduction at 11–43% of the gait cycle. Zero-dimensional analysis seems to overstate sagittal plane changes over time since no such changes were found by Statistical Parametric Mapping.InterpretationOur results agreed with previous studies suggesting that surgical approach do not affect hip kinematics at the early post-operative stage after arthroplasty. However, Statistical Parametric Mapping revealed changes in frontal plane kinematics over time that were underestimated by the zero-dimensional variables. These findings suggest hip adduction impairment up to 12 weeks after arthroplasty.     

Femoroacetabular impingement

Femoroacetabular impingement, both cam and pincer types, is a recently appreciated cause of hip pain, acetabular cartilage and labral damage, and hip degenerative change. Abnormalities in the morphology of the acetabulum or the proximal femur may be the primary predisposing factor. This article reviews the imaging findings and treatment strategies of cam- and pincer-type femoroacetabular impingement.     

The effect of total knee replacement on dynamic support of the body during walking and stair ascent

BACKGROUND: Little is known about the effects of total knee replacement surgery on the contributions of individual joint moments to the total support moment. A better understanding of these effects may enhance rehabilitation protocols and determine factors related to long-term surgical outcome. METHOD: Twenty-one subjects with total knee replacement and 21 controls performed level walking and stair ascent at two testing periods, pre- and 6 months post-surgery. Variables studied included gait velocity, stride length, knee flexion angle, net joint moments of the hip, knee and ankle, and total support moment. Data were analyzed at the first peak vertical ground reaction force. FINDINGS: For level walking, the total support moment, knee extensor moment, and knee flexion angle of total knee replacement patients were less than controls at post-surgery. For stair ascent, the patient group total support moment, ankle plantarflexor moment, and knee flexion angle were less than controls at both testing periods, while knee extensor moment was less than controls at post-surgery. Extensor synergies of the total knee replacement patients revealed less knee and more hip contributions during level walking and larger hip contributions during stair ascent to the total support moment than controls at both testing periods. INTERPRETATION: A feature of total knee replacement gait, pre- and post-surgery, is a stiff knee attitude which may serve to protect the quadriceps. The larger hip extensor contribution to the total support moment observed in the patients may compensate for the diminished knee extensor contribution during level walking and stair ascent.     

Direct anterior approach for total hip arthroplasty: Hip biomechanics and muscle activation during three walking tasks

BackgroundTotal hip replacement with minimally invasive direct anterior approach using the “Smith Petersen” interval is an alternative technique to conventional surgery aimed at preserving the integrity of the muscles around the hip joint. This study aimed to observe hip biomechanics, gait variables, hip muscle activation and locomotor performance during three locomotor tasks (forward, lateral, and backward walking), in subjects who undergo total hip arthroplasty with direct anterior approach.MethodsFourteen patients with primary osteoarthritis who underwent direct anterior approach were included in the study. The optoelectronic 3-D motion analysis system integrated with an electromyography surface device was used to acquire the biomechanics of patients before surgery and at 3 and 6 months post-surgery. Spatio-temporal, dynamic, and hip muscle electromyographic parameters were analyzed and compared whit those of healthy controls.FindingsAlmost all gait parameters improved after surgery. The majority of gait variables neared to the control group at 6 months, while the hip joint range of motion did not. The abnormally increased activation of the muscles around the hip joint was reduced at 6 months post-surgery during all three locomotor tasks. Conversely, the altered gait phase-related electromyographic pattern did not change after the surgery.InterpretationOur results indicate that hip and gait function during several locomotor tasks improved after surgery, while simultaneously either preserve or restore the muscle activation around the hip joint. A full biomechanical evaluation of the hip function during locomotion may aid physicians and surgeons in optimizing the management of patients before and after hip replacement surgery.     

Operative treatment of FAI: open hip preservation surgery

Femoroacetabular Impingement (FAI) is characterized by abnormal contact of the hip joint. Many etiologies cause this painful condition, which leads to early osteoarthritis. While hip arthroscopy has become the most prevalent way to surgically correct a hip, some presentations of FAI require open surgical hip preservation techniques to fully address the pathology at hand. Certain head neck deformities may require open surgical hip dislocation utilizing a trochanteric slide osteotomy. A retroverted acetabulum may require an open periacetabular osteotomy to gain anteversion and eliminate impingement in the hip joint. Acetabular protrusio may require surgical hip dislocation with rim trimming and a possible valgus intertrochanter osteotomy. The sequelae of Legg-Calvé-Perthes disease causes complex abnormalities about the hip joint, which may require open surgery to address both the intra-articular pathology and the extra-articular pathology. Osteotomies of the proximal femur and acetabulum may all be necessary to restore a hip back to normal morphology. Chronic slipped capital femoral epiphysis (SCFE) may also require open surgical hip dislocations and complex intertrochanter osteotomies to recreate normal morphology.     

构建Cam型髋关节撞击综合征有限元模型及力学分析

背景：Cam型髋关节撞击综合征可使关节承受力学过载并最终导致髋关节骨关节炎,然而其诱发骨关节炎的相关力学机制仍不清楚。 目的：运用三维有限元的方法,分析Cam型髋关节撞击综合征的关节内力学环境,进一步了解其病理力学特点。 方法：采用正常髋关节CT数据,利用Mimics和Hypermesh软件准确构建正常髋关节和Cam型髋关节撞击综合征三维有限元模型。在LS-DYNA 软件中,模拟坐下、起立时的力学加载条件,对正常髋关节和Cam型髋关节撞击综合征髋关节的软骨接触力学进行分析。 结果与结论：基于CT数据准确构建了包含关节软骨的正常髋关节和Cam型髋关节撞击综合征髋关节三维有限元力学分析模型。坐下、起立加载过程中,正常髋关节在最大屈髋位时峰值接触压力分别为4.43,4.59 MPa;而Cam型髋关节撞击综合征髋关节分别为14.96,14.86 MPa,髋臼缘前上方出现过高压力和应力集中。提示髋臼软骨过高的接触压力可能是Cam型髋关节撞击综合征导致骨关节炎的力学机制。     

Long-term gait biomechanics in level,uphill, and downhill conditions following anterior cruciate ligament reconstruction

BackgroundAltered gait biomechanics have been linked to post-traumatic knee osteoarthritis development following anterior cruciate ligament reconstruction surgery, but the persistence of aberrant gait biomechanics after the first year post-surgery is inconsistent in the literature. Gait biomechanics are typically evaluated on a level surface, but this task may not elucidate discrepancies in individuals further removed from surgery due to the simplicity of the task. Graded surfaces are common in real-world ambulation and may exacerbate aberrant gait biomechanics due to greater mechanical demands.MethodsForty-seven individuals post-anterior cruciate ligament reconstruction (4 ± 3 years post-surgery) and forty-seven uninjured controls completed gait analysis under level, uphill, and downhill conditions on an instrumented treadmill. Outcomes included knee flexion displacement and peak knee flexion angle, vertical ground reaction force, and knee extension and abduction moments.FindingsKnee extension moment and knee flexion displacement were lesser in the surgical limb compared to the contralateral during the downhill condition, with lesser knee flexion displacement also observed during the level condition. Additionally, knee extension moment was less symmetrical in the surgical group during both uphill and downhill conditions compared to controls. Knee flexion displacement was less symmetrical in the surgical group during both level and downhill conditions compared to controls.InterpretationGraded surfaces elucidate aberrant gait biomechanics in individuals more than 1 year post-anterior cruciate ligament reconstruction that are not apparent during level walking. These findings suggest that gait assessment on level surfaces may mask existing deficiencies, and warrant emphasizing ambulation of graded surfaces during anterior cruciate ligament rehabilitation.     

ESB Clinical Biomechanics Award 2020: Pelvis and hip movement strategies discriminate typical and pathological femoral growth – Insights gained from a multi-scale mechanobiological modelling framework

BackgroundMany children with cerebral palsy (CP) develop skeletal deformities during childhood. So far, it is unknown why some children with CP develop bony deformities whereas others do not. The aims of this study were to (i) investigate what loading characteristics lead to typical and pathological femoral growth, and (ii) evaluate why some children with CP develop femoral deformities whereas other do not.MethodsA multi-scale mechanobiological modelling workflow was used to simulate femoral growth based on three-dimensional motion capture data of six typically developing children and 16 children with CP. Based on the growth results, the participants with CP were divided into two groups: typical growth group and pathological growth group. Gait kinematics and femoral loading were compared between simulations resulting in typical growth and those resulting in pathologic growth.FindingsHip joint contact forces were less posteriorly-oriented in the pathological growth simulations compared to the typical ones. Compared to the typically developing participants, the CP group with pathological femoral growth presented increased knee flexion and no hip extension. The CP group with simulated typical growth presented similar sagittal plane joint kinematics but differed in the frontal plane pelvic and hip movement strategy, which normalized the hip joint contact force and therefore contributed to typical femoral growth trends.InterpretationOur simulation results identified specific gait features, which may contribute to pathological femoral growth. Furthermore, the hip joint contact force orientation in the sagittal plane seems to be the dominant factor for determining femoral growth simulations.