The impact of hip abductor muscle status on in vivo joint loads through kinematics and muscle activity 51 months following total hip arthroplasty

Background: Well-established clinical scores show that total hip arthroplasty (THA) in primary hip osteoarthritis alleviates pain and markedly improves the performance of activities of daily living (ADLs). However, objective measurements show that THA patients’ movement and electrophysiological patterns do not match those of healthy age- matched individuals. Surgical incision as well as intraoperative soft tissue traction and compression cause iatrogenic damage of the hip muscles, which is associated with their atrophy and fatty degeneration. An unfavorable muscle status may negatively affect joint loads. An improper in vivo hip joint resultant contact force (Fres) may shorten an implant’s lifespan and also determine functional outcome following THA. This retrospective analysis aimed to identify whether kinematics and electrophysiological activity mediate the impact of structural muscle impairment on kinetics. Materials and methods: In order to determine the Fres, instrumented femoral prostheses were implanted via a direct lateral approach. Nine patients (two females, seven males) participated in synchronous recordings of load patterns and surface electromyography along with three-dimensional mapping of motion sequences at a mean of 51 months (period: 35-64 months) postoperatively. The hip movement patterns of five ADLs (level walking, ascending stairs, descending stairs, standing up, sitting down) and the electrophysiological activity of the hip abductors gluteus maximus muscle, gluteus medius muscle, and tensor fasciae latae muscle (TFL) were assessed and correlated with both the hip abductor muscle status (total muscle volume [TMV], fat ratio [FR]) evaluated by postoperative computed tomography images and the in vivo Fres. Findings: Across all ADLs, the results yield high inter-individual variability. Compared to asymptomatic control groups in the literature, this study’s patients produced reduced extension and lower sagittal range of motion (ROM) in level walking, while stair negotiation resulted in higher flexion and greater ROM in the sagittal plane. Particularly TFL activity patterns are shaped by irregularities and hyperactivity. TMV and FR have an effect on both motion patterns in the sagittal and frontal planes and shape and timing of muscle activity. Furthermore, compensatory movement strategies and abnormal muscle activity may lead to not only higher but also lower hip joint loads. Interpretation: The data do not provide conclusive evidence of muscle damage affecting joint loads via atypical movement and electrophysiological patterns. Overall, however, the results support the hypothesis that structural impairment of hip abductors may lead to the development of pathomechanical movement patterns and irregular muscle activity, which in turn may adversely affect hip joint loads.Fragestellung: Gängige klinische Scores zeigen, dass die Implantation einer Hüfttotalendoprothese bei primärer Coxarthrose die Schmerzen der Patienten bedeutend lindern und die Ausführung von Aktivitäten des täglichen Lebens merklich verbessern kann. Ergebnisse objektivierbarer Messmethoden zeigen jedoch, dass weder die Bewegungsmuster noch die Muskelaktivität dieser Patienten denen gesunder Gleichaltriger entspricht. Die Implantation einer Hüfttotalendoprothese führt entweder über ein Schnitt- oder ein Quetschtrauma zu einer iatrogenen Schädigung der Hüftmuskulatur, was mit deren Atrophie und Verfettung einhergeht. Ein abträglicher Muskelstatus kann sich ungünstig auf die Hüftgelenksbelastung auswirken. Die resultierende Hüftkontaktkraft ist ein bedeutender Faktor für die Haltbarkeit einer Hüfttotalendoprothese, die das funktionelle Ergebnis eines endoprothetischen Ersatzes mitbestimmt. Das Ziel dieser retrospektiven Analyse war es, das Verständnis für die auf die in vivo resultierende Hüftgelenksbelastung wirkenden Zusammenhänge zwischen periartikulärer Muskelschädigung, pathologischen Bewegungsabläufen und irregulärer Muskelaktivität zu erweitern. Material und Methodik: Zwecks in-vivo-Bestimmung der Hüftkontaktkräfte erfolgte per transglutealem Zugang die Implantation von instrumentierten Hüfttotalendoprothesen. Neun Patientinnen und Patienten (zwei weiblich, sieben männlich) nahmen zum durchschnittlichen Zeitpunkt von 51 Monaten (Zeitraum: 35-64 Monate) postoperativ an synchronen Belastungsmessungen, dreidimensionalen Bewegungserfassungen und Oberflächen-Elektromyographie-Messungen teil. Die Bewegungsmuster der Hüfte von fünf Aktivitäten des alltäglichen Lebens (ebenes Gehen, treppauf Gehen, treppab Gehen, Aufstehen, Hinsetzen) sowie die Muskelaktivität der Hüftabduktoren (M. gluteus maximus, M. gluteus medius, M. tensor fasciae latae) wurden erfasst und jeweils mit dem anhand von postoperativen computertomographischen Aufnahmen evaluierten Muskelstatus (Gesamtvolumen, prozentuale Verfettung) und der Hüftkontaktkraft korreliert. Ergebnisse: Über alle Aktivitäten hinweg ergab sich aus den Messergebnissen eine hohe interindividuelle Streuung. Im Vergleich zu symptomlosen Kontrollgruppen aus der Literatur zeigte sich beim Gehen eine reduzierte Extension und ein geringerer Bewegungsumfang in der Sagittalebene. Beim Treppengang hingegen erfolgten eine höhere Flexion und ein größerer Bewegungsumfang in der Sagittalebene. Insbesondere die Aktivitätsmuster des M. tensor fasciae latae waren von Unregelmäßigkeiten und Überaktivität geprägt. Die Daten zeigen auf, dass Muskelvolumen und -verfettung sowohl die Hüftbewegung in der Sagittal- und Frontalebene als auch die elektrophysiologische Form und den Zeitablauf von Muskelaktivität beeinflussen. Die Ergebnisse weisen ferner darauf hin, dass beeinträchtigte Bewegungsabläufe und gestörte Muskelaktivität nicht nur eine Erhöhung, sondern auch eine Verminderung der Hüftkontaktkraft bewirken können. Schlussfolgerung: Die Daten liefern keine stichhaltigen Beweise für einen durchgehenden Effekt einer Muskelschädigung über atypische Bewegungsabläufe und elektrophysiologische Signale auf die Gelenkbelastungen. Jedoch bekräftigen die Ergebnisse insgesamt die Hypothese, dass eine strukturelle Beeinträchtigung der Hüftabduktoren zur Entstehung von pathomechanischen Bewegungsmustern und unregelmäßiger Muskelaktivität führen kann, was sich wiederum ungünstig auf die Hüftkontaktkräfte auswirken kann

Automating the multimodal analysis of musculoskeletal imaging in the presence of hip implants

In patients treated with hip arthroplasty, the muscular condition and presence of inflammatory reactions are assessed using magnetic resonance imaging (MRI). As MRI lacks contrast for bony structures, computed tomography (CT) is preferred for clinical evaluation of bone tissue and orthopaedic surgical planning. Combining the complementary information of MRI and CT could improve current clinical practice for diagnosis, monitoring and treatment planning. In particular, the different contrast of these modalities could help better quantify the presence of fatty infiltration to characterise muscular condition after hip replacement. In this thesis, I developed automated processing tools for the joint analysis of CT and MR images of patients with hip implants. In order to combine the multimodal information, a novel nonlinear registration algorithm was introduced, which imposes rigidity constraints on bony structures to ensure realistic deformation. I implemented and thoroughly validated a fully automated framework for the multimodal segmentation of healthy and pathological musculoskeletal structures, as well as implants. This framework combines the proposed registration algorithm with tailored image quality enhancement techniques and a multi-atlas-based segmentation approach, providing robustness against the large population anatomical variability and the presence of noise and artefacts in the images. The automation of muscle segmentation enabled the derivation of a measure of fatty infiltration, the Intramuscular Fat Fraction, useful to characterise the presence of muscle atrophy. The proposed imaging biomarker was shown to strongly correlate with the atrophy radiological score currently used in clinical practice. Finally, a preliminary work on multimodal metal artefact reduction, using an unsupervised deep learning strategy, showed promise for improving the postprocessing of CT and MR images heavily corrupted by metal artefact. This work represents a step forward towards the automation of image analysis in hip arthroplasty, supporting and quantitatively informing the decision-making process about patient’s management

Joint Multimodal Segmentation of Clinical CT and MR from Hip Arthroplasty Patients

Magnetic resonance imaging (MRI) is routinely employed to assess muscular response and presence of inflammatory reactions in patients treated with metal-on-metal hip arthroplasty, driving the decision for revision surgery. However, MRI is lacking contrast for bony structures and as a result orthopaedic surgical planning is mostly performed on computed tomography images. In this paper, we combine the complementary information of both modalities into a novel framework for the joint segmentation of healthy and pathological musculoskeletal structures as well as implants on all images. Our processing pipeline is fully automated and was designed to handle the highly anisotropic resolution of clinical MR images by means of super resolution reconstruction. The accuracy of the intra-subject multimodal registration was improved by employing a non-linear registration algorithm with hard constraints on the deformation of bony structures, while a multi-atlas segmentation propagation approach provided robustness to the large shape variability in the population. The suggested framework was evaluated in a leave-one-out cross-validation study on 20 hip sides. The proposed pipeline has potential for the extraction of clinically relevant imaging biomarkers for implant failure detection

Support for total hip replacement surgery: Structures modeling, Gait Data Analysis and Report system

For the treatment of advanced damages of hip joints, Total Hip Arthroplasty is well proven. Due to the different mechanical properties of the prosthesis material and the bone tissue, a partial unloading of the periprosthetic bone occurs. The bone cement causes reduction in bone density as a result of removal of normal stress from the bone, leading to weakening of the bone in that area and the fracture risk increases. Bone loss is identified as one of the main reasons for loosening of the stem. Otherwise, thanks to the press-fit of the non-cemented stem achieved by surgery, the bone layers immediately adjacent to the stem are preloaded, thus encouraged growing, and the bone getting stronger. The non-cemented stem would be the better choice for every patient, but the question remains if the femur can handle the press- fitting surgery. This studies aim to develop a monitoring techniques based on Gait analysis and bone density changes to assess patient recovery after Total Hip Arthroplasty. Furthermore, to validate computational processes based on 3D modeling and Finite Element Methods for optimizing decision making in the operation process and selecting the suited surgical procedure. A vision could be minimizing risk of periprosthetic fracture during and after surgery. Patients: The sample presents 11 patients receiving cemented implant and 13 for the uncemented. Patients are grouped by type of implant. Three checkpoints were considered: before, after operation and one year later. CT scans, gaitrite and kinepro measurements have been realized. Main outcome measures: Fracture risk probability is higher in bone with low bone mineral density; therefore bones are more fragile in elderly people. BMD is indeed one parameter considered among all the observations. Periprosthetic fracture of the femur is a rare but complex complication of THA, and requires demanding surgery. As such, they result in considerable morbidity and dysfunction. Thus, tests of force reaction have been accomplished to support surgeons during the prosthesis fitting. Identification of risk factors for fracture will improve preoperative counseling and aid primary prevention. To assess eventual improvements or find out trends respecting the implant used, gait data have been collected and compared with muscles mass modeling

Contribution to the clinical validation of a generic method for the classification of osteoarthritic and non-pathological knee function

The Cardiff Dempster-Shafer (DS) classifier is a generic automated technique for analysing motion analysis (MA) data. It can accurately discriminate between level gait characteristics of non-pathological (NP) and osteoarthritic (OA) knee function. It can also quantify and visualise the functional outcome of a total knee replacement (TKR). A number of studies were undertaken to explore and enhance this method. The training set for the classifier was increased by 48% by collecting additional knee function data for level gait. Knee function for nine new patients was classified pre and post-TKR surgery. At 12 months post-TKR, two patients exhibited non-dominant NP knee function. The remaining patients did not recover NP gait. This finding is similar to previous classifications of level gait. To improve the distinction between varying degrees of knee function, stair gait was introduced into the trial. A staircase was designed and validated. Adduction and flexion moments acting about the knee joint and medial component of the ground reaction force were found to be important in the classification of OA and NP knee function from stair gait. Using a combination of these variables the DS classifier was able to characterise OA and NP function for 15 subjects correctly with 100% accuracy, determined using a leave-one-out method of cross validation. The variables were tested to assess the outcome of TKR surgery. The patient assessed recovered NP stair gait post surgery. An image based study was undertaken to investigate the quality of the MA data used in the DS classifier. A step up/down activity for 5 NP and 5 TKR subjects was recorded using non-simultaneous MA and dynamic fluoroscopy. Accurate knee kinematics were computed from the fluoroscopy images using KneeTrack image registration software. MA measured significantly larger knee joint translations and non-sagittal plane rotations. The largest errors in MA derived kinematics were 9.53 for adduction-abduction range of motion (ROM) measured from the NP cohort and 2.63cm compression-distraction ROM of the tibio-femoral joint, measured from the TKR cohort. The generic nature of the DS classifier was tested by its application to distinguish hip function following a lateral (LA) and posterior (PA) approach to total hip arthroplasty. The use of different variables was investigated with the classifier. The best classifier was able to distinguish between NP and LA function with 96.7% accuracy, LA and NP with 86.2% accuracy and between LA and PA with 81.5% accuracy. The PA approach was found to lead to more characteristic NP hip function than LA. These studies show that variables from stair gait should be included in addition to level gait in the classifier. Due to errors when measuring non-sagittal plane rotations using MA, these should be interpreted with caution. The generic nature of the classifier has been proven by its application to another joint, thus answering another orthopaedic question.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

The effect of change of direction angle on kneeand hip biomechanics : implications foranterior cruciate ligament injury

ACL injuries have been referred to poor mechanics as they frequently occur without contact. Changes in the knee valgus (abduction) angle and knee valgus (external abduction) moment and limb asymmetry have been linked to greater risk of ACLinjury. Change of direction (COD) manoeuvres are important for many field sports, however they are unfortunately associated with non-contact anterior cruciate ligament (ACL) injuries. There is limited literature exploring the associations between lower-limb biomechanical variables during COD manoeuvre associated with ACL injuries. Although players frequently COD at >90° angles, limited knowledge is available on hip and knee joints kinematics and kinetics in term of limb asymmetry and differences between COD at 90° and 135° manoeuvres. In addition, high knee valgus angle and moment during COD manoeuvre is associated with joint positions including increased hip flexion, abduction and internal rotation angles. In addition, isometric hip muscle strength has been reported to predict ACL injuries, indicating that weakness in hip muscles is a modifiable risk factor of the non-contact ACLinjury. However, the relationship between knee valgus angle and moment with hip kinematics and muscle strength during COD at 90° and 135° manoeuvres still unknown. Currently, there has been no published research correlating the hip abductor, extensor, and external rotator strength on frontal plane hip and knee biomechanics during 90° and 135° COD manoeuvres. Therefore, the purposes of this thesis was to (1) determine whether asymmetry in knee and hip biomechanics kinematics and kinetics and hip muscle strength between preferred and nonpreferred limbs during COD manoeuvres at 90° and 135° angles exists, (2)determine whether differences in knee and hip biomechanics kinematics and kinetics between COD manoeuvres at 90° and 135° angles exists and (3) explore the relationships between ACL injury risk factors (knee valgus angle and moment) and hip kinematics and muscles strength during 90° and 135° COD manoeuvres.Three-dimensional (3D) motion analysis technique is a gold stander to assess biomechanical lower-limb during functional activities. In fact, the gold standard for examining lower limb biomechanics is 3D motion analysis system and allows researchers to calculate all three motion planes during dynamic manoeuvres. Inaddition, the isokinetic dynamometer has been considered as a gold standard measurement tool for assessing isometric hip muscle strength and become more popular in sport, research and clinic setting. Healthy male recreational soccer players performed COD manoeuvres at 90° and 135° angles and maximal voluntaryisometric contractions of the hip abductors, extensors, and external rotators. From recorded motion capture, ground reaction force data and hip and knee biomechanics as well as, hip muscles peak torque were calculated. To determine limb asymmetry,a paired sample t-test was conducted using a Holm method correction. Then, pearson’s correlation coefficient (r) was used to explore the relationships between hip kinematics and strength and knee valgus angle and moment. 36 individuals took part in the study (24.25 ±6.21 years, 1.72 ±0.06 m and 66.41 ±10.83 kg). At 135° COD, participants showed greater knee valgus angles at initialcontact and greater peak external knee abduction moments than at 90°. However, no effect of COD angles on knee flexion angle and peak vGRF were found. The results suggest that there were no differences between preferred and non-preferred limbs. Furthermore, the results highlight an important role the hip motion play in controlling kinematic and kinetic risk factors of ACL injury during COD manoeuvres. The findings provided some support that excessive knee valgus angle and moment is potentially associated with poor hip control in all planes. However, there were nosignificant correlation between hip muscles strength and knee frontal plane kinetics and kinematics. It can be concluded that different COD angles demand different hip and knee kinematics and kinetics. The results suggest that sharper COD angle place the knee at more risk for ACL injuries. COD manoeuvres at 90° may be useful for evaluating of individuals but may not be challenging enough to reveal poor neuromuscular control over hip and knee motion. Therefore, sharper angles of examination should be utilized in the evaluation of individuals. Moreover, these results may help provide an appropriate manipulation and intervention on COD manoeuvre to reduce the risk of ACL injury. The findings of this study will increase the knowledge base of ACL injury and can aid in the design of more appropriate neuromuscular and plyometrictraining protocols for injury prevention

Contribution to the clinical validation of a generic method for the classification of osteoarthritic and non-pathological knee function

The Cardiff Dempster-Shafer (DS) classifier is a generic automated technique for analysing motion analysis (MA) data. It can accurately discriminate between level gait characteristics of non-pathological (NP) and osteoarthritic (OA) knee function. It can also quantify and visualise the functional outcome of a total knee replacement (TKR). A number of studies were undertaken to explore and enhance this method. The training set for the classifier was increased by 48% by collecting additional knee function data for level gait. Knee function for nine new patients was classified pre and post-TKR surgery. At 12 months post-TKR, two patients exhibited non-dominant NP knee function. The remaining patients did not recover NP gait. This finding is similar to previous classifications of level gait. To improve the distinction between varying degrees of knee function, stair gait was introduced into the trial. A staircase was designed and validated. Adduction and flexion moments acting about the knee joint and medial component of the ground reaction force were found to be important in the classification of OA and NP knee function from stair gait. Using a combination of these variables the DS classifier was able to characterise OA and NP function for 15 subjects correctly with 100% accuracy, determined using a leave-one-out method of cross validation. The variables were tested to assess the outcome of TKR surgery. The patient assessed recovered NP stair gait post surgery. An image based study was undertaken to investigate the quality of the MA data used in the DS classifier. A step up/down activity for 5 NP and 5 TKR subjects was recorded using non-simultaneous MA and dynamic fluoroscopy. Accurate knee kinematics were computed from the fluoroscopy images using KneeTrack image registration software. MA measured significantly larger knee joint translations and non-sagittal plane rotations. The largest errors in MA derived kinematics were 9.53 for adduction-abduction range of motion (ROM) measured from the NP cohort and 2.63cm compression-distraction ROM of the tibio-femoral joint, measured from the TKR cohort. The generic nature of the DS classifier was tested by its application to distinguish hip function following a lateral (LA) and posterior (PA) approach to total hip arthroplasty. The use of different variables was investigated with the classifier. The best classifier was able to distinguish between NP and LA function with 96.7% accuracy, LA and NP with 86.2% accuracy and between LA and PA with 81.5% accuracy. The PA approach was found to lead to more characteristic NP hip function than LA. These studies show that variables from stair gait should be included in addition to level gait in the classifier. Due to errors when measuring non-sagittal plane rotations using MA, these should be interpreted with caution. The generic nature of the classifier has been proven by its application to another joint, thus answering another orthopaedic question

Understanding Movement and its Influence on Tribology of the Human Hip

Total hip arthroplasty is one of the most successful and innovative medical procedures developed during the 20th century. Success post-op has been shown to decrease for younger, more active patients when compared to those who are older and less active, raising concerns surrounding the reasons behind the increased risk of prosthesis failure for some individuals. Sliding distance, cross-shear, load and edge loading are important factors when determining potential wear rates at the hip. Global and local hip biomechanics were calculated for eighteen healthy subjects, completing thirteen common daily activities. Results showed variation in cross-shear motion and hip reaction forces between individuals and across activities. Variation in motion paths and loading, between and within activities, suggested variation in the fluid film thickness and corresponding lubrication regimes at the joint. Walking tasks showed high levels of cross-shear and the potential for excessive wear both at initial contact and heel-off. More linear activities, such as sitting and standing, showed low cross-shear alongside a potential risk of posterior edge loading. Tribological discrepancies were shown between hip simulator input data (ISO) and measured walking data, with the ISO cycle potentially underestimating cross-shear wear at initial contact, during walking. Results provide detailed data that may facilitate improvements in the reliability of pre-clinical testing for hip prostheses and tissue engineered cartilage substitution. The data indicates that durability testing standards should consider incorporating a range of activities, rather than just walking, and aim to represent the variability shown between individuals. Results also provide evidence for determining the appropriateness of specific activities/ rehabilitation for post-operative total hip replacement patients