Identification and interpretation of gait analysis features and foot conditions by explainable AI.

Clinical gait analysis is a crucial step for identifying foot disorders and planning surgery. Automating this process is essential for efficiently assessing the substantial amount of gait data. In this study, we explored the potential of state-of-the-art machine learning (ML) and explainable artificial intelligence (XAI) algorithms to automate all various steps involved in gait analysis for six specific foot conditions. To address the complexity of gait data, we manually created new features, followed by recursive feature elimination using Support Vector Machines (SVM) and Random Forests (RF) to eliminate low-variance features. SVM, RF, K-nearest Neighbor (KNN), and Logistic Regression (LREGR) were compared for classification, with a Majority Voting (MV) model combining trained models. KNN and MV achieved mean balanced accuracy, recall, precision, and F1 score of 0.87. All models were interpreted using Local Interpretable Model-agnostic Explanation (LIME) method and the five most relevant features were identified for each foot condition. High success scores indicate a strong relationship between selected features and foot conditions, potentially indicating clinical relevance. The proposed ML pipeline, adaptable for other foot conditions, showcases its potential in aiding experts in foot condition identification and planning surgeries.

Short-term results of gait analysis with the Heidelberg foot measurement method and functional outcome after operative treatment of ankle fractures.

BACKGROUND: Ankle fractures are common fractures in trauma surgery. Several studies have compared gait patterns between affected patients and control groups. However, no one used the Heidelberg Foot Measurement Method in combination with statistical parametric mapping of the entire gait cycle in this patient cohort. We sought to identify possible mobility deficits in the tibio-talar joint and medial arch in patients after ankle fractures as a sign of stiffness and pain that could result in a pathological gait pattern. We focused on the tibio-talar flexion as it is the main movement in the tibio-talar joint. Moreover, we examined the healing progress over time. METHODS: Fourteen patients with isolated ankle fractures were included prospectively. A gait analysis using the Heidelberg Foot Measurement Method was performed 9 and 26 weeks after surgery to analyse the tibio-talar dorsal flexion, the foot tibia dorsal flexion, the subtalar inversion and the medial arch as well as the cadence, the walking speed and the ground reaction force. The American Orthopedic Foot & Ankle Society ankle hindfoot score was used to obtain clinical data. Results were compared to those from 20 healthy participants. Furthermore, correlations between the American Orthopedic Foot & Ankle Society hindfoot score and the results of the gait analysis were evaluated. RESULTS: Statistical parametric mapping showed significant differences for the Foot Tibia Dorsal Flexion for patients after 9 weeks (53-75%: p = 0.001) and patients after 26 weeks (58-70%: p = 0.011) compared to healthy participants, respectively. Furthermore, significant differences regarding the tibio-talar dorsal flexion for patients 9 weeks after surgery (15-40%: p < 0.001; 56,5-70%: p = 0.007; 82-88%: p = 0.033; 97-98,5%: p = 0.048) as well as patients after 26 weeks (62,5-65%: p = 0.049) compared to healthy participants, respectively. There were no significant differences looking at the medial arch and the subtalar inversion. Moreover, significant differences regarding the ground reaction force were found for patients after 9 weeks (0-17%: p < 0.001; 21-37%: p < 0.001; 41-54%: p < 0.001; 60-64%: p = 0.013) as well as patients after 26 weeks (0-1,5%: p = 0.046; 5-15%: p < 0.001; 27-33%: p = 0.001; 45-49%: p = 0.005; 57-59%: p = 0.049) compared to healthy participants, respectively. In total, the range of motion in the tibio-talar joint and the medial arch was reduced in affected patients compared to healthy participants. Patients showed significant increase of the range of motion between 9 and 26 weeks. CONCLUSIONS: This study shows, that patients affected by ankle fractures show limited mobility in the tibio-talar joint and the medial arch when compared to healthy participants. Even though the limitation of motion remains at least over a period of 26 weeks, a significant increase can be recognized over time. Furthermore, if we look at the absolute values, the patients' values tend to get closer to those of the control group. TRIAL REGISTRATION: This study is registered at the German Clinical Trials Register ( DRKS00023379 ).

Pain in Adults With Cerebral Palsy After Single-Event Multilevel Surgery.

OBJECTIVE: The aim of the investigation was to assess the contribution of pain to functional, social, and health-related quality-of-life outcomes in adults with cerebral palsy. DESIGN: This monocentric, prospective study included long-term data for ambulant adults with cerebral palsy and at levels I-III in the Gross Motor Function Classification System who had received orthopedic multilevel surgery in adulthood and in whom preoperative and postoperative three-dimensional gait analysis was conducted, including the Gait Profile Score. A questionnaire including the Visual Analog Scale, Oswestry Disability Index, and European Quality of Life 5 Dimensions 3 Level was analyzed. RESULTS: Twenty-four adults at a mean age of 38.0 yrs were included. Sixteen patients (66.7%) indicated that they experienced pain and 10 patients (41.7%) had pain for more than 6 mos. Overall, 13 patients (54%) experienced both pain and anxiety. There was no correlation of the Gait Profile Score with pain, Gross Motor Function Classification System, and Oswestry Disability Index. The Oswestry Disability Index showed a positive correlation with the Gross Motor Function Classification System (r = 0.39, P = 0.05) and pain (r = 0.57, P = 0.004). CONCLUSIONS: Pain and anxiety represent relevant comorbidities in adults with cerebral palsy. The occurrence of pain correlates with the Oswestry Disability Index and is higher than in children with cerebral palsy.

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.

Biomechanical assessment of patellar tendon advancement in patients with cerebral palsy and crouch gait.

BACKGROUND: Patellar height is a valuable measure to evaluate the effect of patellar tendon advancement (PTA) on knee function. In the literature, there is no validated procedure to measure the patellar height. In this study we aimed to (1) determine the patella position through musculoskeletal modeling, (2) investigate the effects of two surgical procedures applied for PTA, and (3) assess the effect of PTA in combination with single-event multilevel surgery (SEMLS) on the knee kinematics of patients with cerebral palsy (CP) and crouch gait. METHOD: Three-dimensional gait and X-ray data of children with CP and crouch gait were retrospectively analyzed if they had received a SEMLS in combination with PTA (PTA group, n = 18) or without PTA (NoPTA group, n = 18). A computational musculoskeletal model was used to quantify patella position, knee extension moment arm, and knee kinematics pre- and postoperatively. RESULTS: Patellar height significantly decreased in the PTA group (P = 0.004), while there was no difference in the NoPTA group (P > 0.05). The bony procedure for PTA provided a better Insall-Salvati ratio than the soft tissue procedure. The peak knee extension moment arm significantly increased in the PTA group (P = 0.008). In terms of postoperative knee joint kinematics, the PTA group was closer to typically developed children than the NoPTA group. CONCLUSION: Musculoskeletal modeling was found to be an effective tool for the determination of the patellar height. PTA improved the patella position, knee extension moment arm, and knee kinematics and was an effective procedure for the surgical management of crouch gait in patients with CP.

Scapulohumeral rhythm in patients after total shoulder arthroplasty compared to age-matched healthy individuals.

PURPOSE: The coordination of the glenohumeral joint and the shoulder girdle has been known as scapulohumeral rhythm. The effects of anatomical total shoulder arthroplasty (aTSA) are still subject to research. Former studies showed a higher amount of scapula lateral rotation to compensate for reduced glenohumeral elevation. The purpose of the present study was to confirm this mechanism and examine additional effects on the sternoclavicular and acromioclavicular joints' kinematics. METHODS: 3D motion analysis was used to examine 23 shoulders of 16 patients with a mean age of 71.2 (SD: 5.2) years with a mean follow up of 5.4 (SD: 2.1) years after aTSA and to compare kinematics and coordination to 22 shoulders of 11 healthy age-matched individuals with a mean age of 69.6 (SD: 5.3) years while performing elevation movement in frontal and sagittal plane. RESULTS: The ratio of glenohumeral to shoulder girdle contribution was reduced compared to healthy individuals: Shoulder girdle contribution to elevation was 36.5% (SD: 8.1) in the aTSA group vs. 28.5% (SD: 8.2) in the control group in the sagittal plane and 38.1% (SD: 9.1) vs. 30.2% (SD: 7.1) in the frontal plane. Kinematics of the sternoclavicular and acromioclavicular joints showed significantly different patterns. CONCLUSION: Patients after aTSA showed altered shoulder girdle kinematics and higher contribution of the shoulder girdle towards elevation. Whether this is a result of the surgery, of limited glenohumeral range of motion or due to the preoperative status remains unclear. Further investigation with a prospective study design is necessary.

Differences in gait analysis and clinical outcome after TightRope® or screw fixation in acute syndesmosis rupture: study protocol for a prospective randomized pilot study.

BACKGROUND: Ankle sprains and fractures are most common injuries in orthopedic and trauma surgery. The concurrent occurrence of syndesmosis ruptures in these injuries represents a more complex problem, as they often remain undetected. A proper and accurate treatment of injuries of the syndesmosis, both isolated and combined with fractures, is necessary to avoid long-term consequences (chronic instability, cartilage damage, and post-traumatic osteoarthritis). The most popular treatment option is a static screw fixation and the newly developed dynamic TightRope® (Arthrex, Naples, FL, USA). The aim of this pilot study is to compare monitor ankle range of motion and maximum ankle power in gait as functional outcome parameters of instrumented gait analysis, as well as clinical and radiographic outcome for assessing the stabilization of acute syndesmosis rupture with either a static implant (a 3.5 mm metallic screw) or a dynamic device (TightRope®). METHODS: This prospective, randomized, controlled, clinical trial will be carried out at the Center for Orthopedics, Trauma Surgery and Spinal Cord Injury of the University Hospital Heidelberg. Adult patients, who suffer from an acute syndesmosis rupture, both isolated and in combination with fractures of the lateral malleolus (Weber C and Maisonneuve fractures) and who are undergoing surgery at our trauma center will be included in our study. The patients will be randomized to the different treatment options (screw fixation or "TightRope®"). Subsequent to the surgical treatment, all patients will receive the same standardized follow-up procedures including a gait analysis and MRI of the ankle at 6 months follow-up. The primary endpoint of the study is the successful healing of the syndesmosis and biomechanical investigation with gait analysis. DISCUSSION: The results of the gait analysis from the current study will help to impartially and reliably evaluate the clinical and biomechanical outcome of both treatment options of acute syndesmosis ruptures. We hypothesize that the dynamic fixation provides an equivalent or better biomechanical, clinical, and radiographic outcome in comparison to the screw fixation. TRIAL REGISTRATION: German Clinical Trials Register (DRKS) DRKS00013562 . Registered on July, 12, 2017.

3D motion analysis of latissimus dorsi tendon transfer in patients with posterosuperior rotator cuff tears: Analysis of proprioception and the ability to perform ADLS.

BACKGROUND: Massive irreparable posterosuperior rotator cuff tears may result in a loss of external rotation. Most of these patients lose their ability to perform activities of daily living (ADLs), especially where external rotation and abduction are needed. Latissimus dorsi tendon transfer (LDTT) is a method to restore abduction and external rotation in patients with posterosuperior rotator cuff tears. There are no objective data concerning whether LDTT can restore range of motion (ROM), especially in performing ADLs and if proprioception changes after LDTT. METHODS: We examined 12 patients 4.2 years (1-9 years) after LDTT with simultaneous 3D motion analysis; the opposite, nonaffected side was assessed as control. The measurement protocol included maximum values in flexion/extension, abduction/adduction, internal/external rotation in 0° and in 90° flexion and in 90° abduction. To evaluate competences, we measured seven activities of daily life and examined the proprioceptive ability using an active angle reproduction test. RESULTS: In total, 4.2 years (1-9 years) after LDTT there was no significant difference in flexion/extension and abduction/adduction compared to the healthy side. Maximum external rotation was significantly reduced compared to the opposite side. Eleven patients (85%) were able to perform all ADL. Proprioceptive ability did not differ from the healthy side. CONCLUSION: LDTT cannot fully restore a patient's ability for external rotation after a posterosuperior rotator cuff tear. However, 4.2 years after surgery, 85% of the patients are able to perform all ADLs. Proprioceptive ability is not affected by the transfer.

Variation of the glenohumeral and scapulothoracic motion in progressive severity of glenohumeral osteoarthritis.

INTRODUCTION: The aim of this study is to investigate the variation of the glenohumeral and scapulothoracic motion in progressive severity of glenohumeral osteoarthritis using a 3-D-motion analysis. Moreover, the variation of the Constant Score is evaluated. HYPOTHESIS: The hypothesis is that the motion of the scapulothoracic joint may partly compensate for the loss of the glenohumeral joint movement in patients with increasing severity of glenohumeral osteoarthritis. MATERIAL AND METHODS: A total of 21 patients with primary osteoarthritis of the glenohumeral joint were clinically examined, divided in three groups (SP1-SP3) according to size of their caudal osteophyte. The contribution of the scapulothoracic (acromioclavicular and sternoclavicular) joint to the total arm (humerothoracical) elevation in sagittal and frontal plane was measured with 3D motion analysis and the Constant Score was evaluated. DISCUSSION: In sagittal plane elevation (anteversion) the contribution of the scapulothoracic joint to the total elevation was while arm raising 32.7% (SD 8.0%) in Group SP1, 36.6% (SD 11.0%) in Group SP2 and 49.6% (SD 9.0%) in Group SP3 (p=0.002). The contribution of the scapulothoracic joint to the total elevation while arm lowering was 31.4% (SD 9.0%) in Group SP1, 39.0% (SD 13.0%) in Group SP2 and 49.7% (SD 12.0%) in Group SP3 (p=0.043). In frontal plane elevation (abduction) the contribution of the scapulothoracic joint was while arm raising 33.7% (SD 8.0%) in Group SP1, 34.0% (SD 10.0%) in Group SP2 and 42.3% (SD 9.0%) in Group SP3 (p=0.071). While arm lowering the contribution of the scapulothoracic joint was 30.8% (SD 10.0%) in Group SP1, 36.3% (SD 12.0%) in Group SP2 and 44.8% (SD 8.0%) in Group SP3 (p=0.022). The group SP1 achieved a Constant Score of 78.00 (SD 9.823) points. The group SP2 achieved a Constant Score of 53.57 (SD 13.92) and the group SP3 38.64 (SD 10.40). There is a significant difference between the three groups (p<0.001). Increasing severity of glenohumeral osteoarthritis leads to a reduced motion of the glenohumeral joint. Instead the magnitude of the scapulothoracic motion increases. LEVEL OF PROOF: V, Case Series.

Long-term muscle changes after hamstring lengthening in children with bilateral cerebral palsy.

AIM: To evaluate short-term (1y postoperatively; E1) and long-term (at least 4y postoperatively; E2) changes in hamstring muscle-tendon length (MTL) and lengthening velocity after hamstring lengthening in children with bilateral cerebral palsy (CP). METHOD: Three-dimensional gait analysis was performed in 19 children (16 males, 3 females; 36 limbs; mean age at surgery 9y [SD 3y]; range 6-10y) with flexed knee gait, preoperative ankle dorsiflexion lower than 20 degrees, and CP before bilateral hamstring lengthening (E0), at E1 and E2. Hamstring MTL (normalized by leg length) and velocity were assessed via OpenSim software. RESULTS: MTL increased from E0 to E1 (p=0.004) and decreased from E1 to E2 (p<0.020). Hamstring lengthening velocity did not change. In the subgroup with short, not slow hamstrings, the increase in MTL was maintained at E2. INTERPRETATION: Hamstring lengthening is an efficient procedure to lengthen short and/or slow hamstrings short-term. The desired outcome with maintenance of the postoperative changes in hamstring MTL is only achieved for preoperatively short, not slow hamstrings. WHAT THIS PAPER ADDS: Surgical hamstring lengthening can be confirmed via musculoskeletal modelling in OpenSim software. Surgical hamstring lengthening in cerebral palsy does not change hamstring lengthening velocity. Short, not slow hamstrings present a long-lasting muscle-tendon length (MTL) increase after hamstring lengthening. Changes in MTL after hamstring lengthening cannot be maintained for slow hamstrings. MTL does not change after hamstring lengthening for neither short nor slow hamstrings.

CAMBIOS MUSCULARES A LARGO PLAZO DESPUÉS DEL ALARGAMIENTO DE LOS ISQUIOTIBIALES EN NIÑOS CON PARÁLISIS CEREBRAL BILATERAL: OBJETIVO: Evaluar los cambios a corto plazo (un año después de la operación; E1) y a largo plazo (al menos cuatro años después de la operación; E2) de la longitud del tendón muscular de los isquiotibiales (LT) y la velocidad de alargamiento después del estiramiento en niños con parálisis cerebral bilateral (PC). MÉTODO: Se realizó un análisis tridimensional de la marcha en 19 niños (16 varones, tres mujeres; 36 extremidades; edad media en la cirugía 9 años [DS 3 años]; rango 6-10 años) con la marcha en flexión de la rodilla, dorsiflexión preoperatoria del tobillo inferior a 20 grados, antes del alargamiento bilateral de los isquiotibiales (E0), en E1 y E2. El LT de los músculos isquiotibiales (normalizado por la longitud de la pierna) y la velocidad fueron evaluadas mediante el OpenSim. RESULTADOS: El LT aumentó de E0 a E1 (p = 0,004) y disminuyó de E1 a E2 (p<0,020). La velocidad de alargamiento de los isquiotibiales no cambió. En el subgrupo con isquiotibiales cortos, pero no lentos, el aumento de la LT se mantuvo en E2. INTERPRETACIÓN: El alargamiento de los isquiotibiales es un procedimiento eficiente para los isquiotibiales cortos y/o lentos a corto plazo. El resultado deseado con el mantenimiento de los cambios postoperatorios en la longitud de los isquiotibiales solo se logra para los isquiotibiales cortos no lentos antes de la operación.

ALTERAÇÕES MUSCULARES A LONGO PRAZO APÓS ALONGAMENTO DE ISQUIOTIBIAIS EM CRIANÇAS COM PARALISIA CEREBRAL BILATERAL: OBJETIVO: Avaliar a curto (um ano de pós-operatório; E1) e longo prazo (no mínimo quatro anos de pós-operatório; E2) alterações no comprimento do tendão do músculo (CTM) isquiotibial e a velocidade de estiramento após alongamento do isquiotibial em crianças com paralisia cerebral bilateral (PC). MÉTODO: Foi realizada a análise tridimensional da marcha em 19 crianças (16 meninos, três meninas; 36 membros; média de idade de cirurgia de 9 anos [DP 3 anos]; variação de 6-10 anos) com marcha com flexão de joelho, ângulo de dorsiflexão de tornozelo menor que 20o no pré-operatório, e PC antes do alongamento bilateral dos isquiotibiais (E0), em E1 e E2. CTM dos isquiotibiais (normalizado pelo comprimento da perna) e a velocidade foram avaliados pelo OpenSim. RESULTADOS: CTM aumentou de E0 para E1 (p=0,004) e diminuiu de E1 para E2 (p<0,020). A velocidade de estiramento do isquiotibial não mudou. No subgrupo com isquiotibial encurtado e não lento, o aumento no CTM foi mantido em E2. INTERPRETAÇÃO: O alongamento do músculo isquiotibial é um procedimento eficiente para alongar isquitotibiais encurtados e/ou lentos a curto prazo. O resultado desejado com a manutenção das alterações no pós-operatório no CTM do isquiotibial é atingida somente para isquiotibial curto e não lento no pré-operatório.

Supracondylar femoral rotation osteotomy affects frontal hip kinetics in children with bilateral cerebral palsy.

AIM: To evaluate the influence of supracondylar femoral derotation osteotomy (FDO) on hip abduction muscle force and frontal hip moments in children with bilateral cerebral palsy. METHOD: For this retrospective cohort study 79 children (36 females, 43 males; mean age at surgery 11y [SD 3y]; range 4-17y) with bilateral cerebral palsy and preoperatively and 1-year postoperatively documented frontal hip moments who received supracondylar FDO in 134 limbs were included. The control group consisted of eight children (two females, six males; mean age 11y [SD 4y]; range 5-17y) who received single-event multi-level surgery without FDO. RESULTS: Hip joint impulse (p<0.001) and the first peak of frontal hip moments (p=0.003) increased, whereas the second peak decreased (p<0.001) from preoperatively to postoperatively. Hip abductor strength improved (p=0.001) from preoperatively to postoperatively. INTERPRETATION: Despite the compensatory mechanism, frontal hip moments are decreased preoperatively. Supracondylar FDO results in increased frontal hip moments. Changes in anteversion directly influence hip kinetics, although no direct change of the proximal bony geometry is performed. WHAT THIS PAPER ADDS: Internal rotation gait cannot fully restore the frontal hip moment. Supracondylar femoral derotation osteotomy (FDO) influences frontal hip kinetics in children with bilateral cerebral palsy. Supracondylar FDO changes the curve progression of frontal hip moments. Supracondylar FDO restores the hip abductor moment arm. Supracondylar FDO leads to an increase in hip abductor muscle force.

Equinus Correction During Multilevel Surgery in Adults With Cerebral Palsy.

BACKGROUND: Equinus foot deformity constitutes a common gait disorder in ambulatory adults with bilateral spastic cerebral palsy (BSCP). The outcome after intramuscular aponeurotic lengthening in the context of single-event multilevel surgery (SEMLS) in adulthood has not been investigated. METHODS: We followed a group of 31 ambulatory adults with BSCP and equinus who underwent SEMLS including gastrocnemius-soleus intramuscular aponeurotic recession or Achilles tendon lengthening. All patients were analyzed preoperatively and at least 1 year (mean follow-up period: 1.6 years) postoperatively by clinical examination and 3-dimensional instrumented gait analysis including the Gait Profile Score (GPS). RESULTS: Clinical examination showed no significant improvement of ankle dorsiflexion ( P = .5) and an unchanged plantarflexion ( P = .7) with knee extended but a significant postoperative reduction of spasticity in the calf muscle ( P = .0001) as measured by clinical examination following the modified Ashworth scale. Significant improvement of mean ankle dorsiflexion in stance and swing ( P = .0001) was found. The GPS decreased and improved significantly (15.9 ± 4.6 to 11.4 ± 3.1; P = .0001). Persistence of equinus and calcaneal gait indicating under- and overcorrection at follow-up was found in 1 patient (3%), respectively. CONCLUSION: Intramuscular gastrocnemius-soleus aponeurotic recession is part of multilevel surgery corrected equinus deformity in adults. The increase in muscle length led to significant improvement of kinetic and kinematic parameters during walking without a loss of muscle strength and push-off capacity. The risk of overcorrection after equinus correction in adults with BSCP was found to be relatively low. LEVEL OF EVIDENCE: Level IV, retrospective case series.

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.

Preoperative hip rotation moments do not predict long-term development after femoral derotation osteotomy in children with cerebral palsy.

BACKGROUND: Femoral derotation osteotomy (FDO) is the standard treatment for internal rotation gait (IRG) in children with cerebral palsy (CP) although high rates of recurrence have been reported recently. Various factors associated with recurrence could be identified, but no predictor named. RESEARCH QUESTIONS: Does FDO lead to a change of internal transversal hip moments? Are preoperative internal transversal hip moments a predictor for recurrence of IRG? METHODS: 41 children with spastic bilateral CP and 72 limbs that received a FDO (10.4 ±â€¯2.7 years at surgery) were included retrospectively. Kinematic data were analyzed pre- (2 ±â€¯3 months), postoperatively (12 ±â€¯3 months) and at long-term follow-up (at least five years postoperatively; 84 ±â€¯13 months), internal transversal hip moments were analyzed pre- and postoperatively. RESULTS: The maximum peaks of the internal hip rotation moment during loading response decreased significantly (p = 0.003). The minimum during the second half of the stance phase increased significantly (p = 0.004) and the initially internal externally rotating moment changed to an internal internally rotating moment. No correlation between changes in hip rotation from postoperatively to the long-term follow-up and the preoperative internal hip rotation moment could be identified. SIGNIFICANCE: FDO leads to changes in internal hip rotation moments. Preoperative internal hip rotation moments can't be used as predicting factor for recurrence of IRG. The data suggest, that recurrence of IRG depends less on patient specific motion patterns, but more on the time point of surgery and the therapy of all concomitant deformities during SEMLS.

Long-term development of overcorrection after femoral derotation osteotomy in children with cerebral palsy.

BACKGROUND: Recent studies showed rates of recurrence of internal rotation gait (IRG) after femoral derotation osteotomy (FDO) up to 40%. Some surgeons even advice overcorrection during FDO to avoid a later recurrence. RESEARCH QUESTION: Evaluation of the long-term development of limbs with initial overcorrection after FDO. METHODS: 29 limbs of 20 children (9.9 ±â€¯3.2 years at surgery) with IRG, cerebral palsy (CP) and more than 5° external hip rotation postoperatively were included retrospectively. A gait analysis and clinical examination were performed preoperatively (less than one year, E0), postoperatively (9-23 months, E1) and at the long-term follow-up (at least five years postoperatively, E2). Differences between those children that remained overcorrected at E2 and those with a hip rotation within normal range at E2 were evaluated. RESULTS: At E2 41% of these limbs remained overcorrected, 52% showed a hip rotation within normal range and 7% showed recurrence of IRG. A comparison of those limbs that remained overcorrected and those ending within normal range revealed neither a difference in age at surgery nor in static and dynamic torsional parameters at E0 and E1 except for pelvic rotation. A significantly larger pelvic internal rotation at E1 for those with remaining overcorrection could be identified. SIGNIFICANCE: A general overcorrection during FDO in children with CP to avoid recurrence of IRG cannot be recommended, as 41% remain overcorrected. Preoperative predictors for long-term development couldn't be identified. If pelvic mal-rotation is corrected, hip rotation may change into normal range over the time in combination with the development of a flexed knee gait.

Long-term development of gait after multilevel surgery in children with cerebral palsy: a multicentre cohort study.

AIM: We investigated the long-term efficacy and safety of multilevel surgery (MLS) in ambulatory children with bilateral spastic cerebral palsy (CP). METHOD: Two hundred and thirty-one children were evaluated at short term (1.1y, SD 0.4) and long term (9.1y, SD 3.0) follow-up using clinical examination and gait analysis. MLS was investigated by studying changes in the Gait Profile Score (GPS) referenced to the minimally important clinical difference. RESULTS: Ambulatory children aged 10 years and 7 months (SD 2y 11mo) at MLS in Gross Motor Function Classification System levels I (19), II (144), and III (68) showed a decrease (improvement) in preoperative GPS from 16.3° (SD 4.8) to 11.3° (SD 3.2) at short-term follow-up, an improvement of 5°. At long-term follow-up, GPS was maintained at 11.4° (SD 3.1). Overall, 177 (76.6%) children maintained their improvement in GPS after 9 years. INTERPRETATION: Multilevel surgery is a safe and effective surgical intervention, which leads to a significant improvement in gait kinematics in children with bilateral spastic CP. This study improves our understanding of MLS in the long term and will help to inform families and children when planning for MLS. WHAT THIS PAPER ADDS: Largest study of multilevel surgery (MLS) for children with bilateral spastic cerebral palsy, with longest follow-up. MLS resulted in significant long-term improvements in gait function. Minor adverse events were common, while events requiring intervention were uncommon (4% of children). Thirty-nine per cent of children required additional surgery during follow-up. 'Single-event multilevel surgery' was changed to the more realistic term 'multilevel surgery'.

Three-dimensional motion analysis for validation of shoulder internal rotation.

BACKGROUND: 10% of the points for the Constant-Murley score (CMS) are allocated for the capacity for internal rotation (IR), measured as unassisted active movement of the dorsum of the hand or the thumb to reach different anatomical landmarks. However, there is little information about the validity of this method and no three-dimensional measurement of the degree of IR that is necessary to reach these landmarks. METHODS: Sixteen volunteers with healthy shoulders were recruited. The degree of IR was defined using the following landmarks as described in the CMS: (1) lateral aspect of thigh, (2) buttock, (3) sacroiliac joint, (4) level of waist, (5) vertebra T12, (6) interscapular. The validity of IR measurement was assessed by simultaneous 3D motion analysis. RESULTS: Using the thumb as pointer, there were significant increases in IR from 39.3° at position 1 to 80.4° at position 2, followed by 105.1°, 108.6°, 110.1°, and 125.3° at position 3-6. Taking the dorsum of the hand as pointer, there were significant increases in IR between all positions, starting from 71.2° (position 1) and followed by 99.3°, 104.1°, 110.3°, 115.2°, and 119.7° at positions 2 to 6. Comparing the two measurement methods, a significant difference was found for the amount of IR between positions 1 and 2. CONCLUSION: Measurement of IR as described in the CMS is a suitable method. However, there was an increase of only 10° in IR between positions 3 and 5, which may be hard to measure with a standard goniometer in clinical practice.

Patient-specific bone geometry and segment inertia from MRI images for model-based analysis of pathological gait.

Patient-specific modeling is a vital component in the translation of computational multibody dynamics into clinical practice. Recent research has focused on ways to derive such models from medical imaging, but the process is usually time consuming and sensitive to operator skill. Here, we present methods to derive kinematic and inertial properties of body segments from MRI images, and condense them into a dynamically consistent patient-specific multibody model (PSM). We develop a semi-automated tool chain to classify bone, muscle and fat in the lower body and use optimization and geometrical methods to derive personalized bone meshes and segment inertial properties. The tool chain is applied to investigate the gait of a 12-yr old female with bone deformities. The patient-specific results are compared to those arising from generic scaled models with parameters based on regression equations. We found several kinematic and inertial differences between the two models, and overall the PSM resulted in markedly smaller angular and force residuals. The PSM was able to capture vital aspects of this patient׳s gait in the transverse plane that were overlooked by the generic model. These results are relevant to the use of multibody dynamics in the planning of surgical interventions, and form the basis for developing efficient and automatic methods to create patient-specific models.

The influence of timing of knee recurvatum on surgical outcome in cerebral palsy.

Recent reports have shown that timing of genu recurvatum (GR) might be caused by different underlying factors and that equinus leads to GR especially during early stance. The purpose of this study was to investigate the reduction of GR after surgical correction of equinus in children with bilateral spastic cerebral palsy and whether the children with early and late type GR show differences in reduction of knee hyperextension after a surgery. In 24 limbs (mean age 10.3 years, GMFCS I-III) showing equinus and GR the kinematics of the knee and ankle as well as the kinetics of the knee were evaluated before and one year (mean follow up period: 12.8 months) after surgical correction of equinus. The study was approved by the local ethical committee. Limbs with early type GR showed a reduction by 11.1° (p<0.001) and those with late type GR by 6.0° (p<0.049) in GR after surgery. Before surgery limbs with early type GR showed increased external extending moments, which decreased significantly after surgery. In contrast limbs with late GR did not show a significant reduction of those moments. The findings of this study underline the influence of equinus on early GR as an underlying factor. As equinus is attributed to early knee hyperextension and proximal factors are more important as underlying factors in late type GR, a classification into early and late onset GR is useful to identify underlying factors and to choose adequate treatment.

Hip-joint congruity after Dega osteotomy in patients with cerebral palsy: long-term results.

INTRODUCTION: Neurogenic hip dislocation is quite common in children with cerebral palsy (CP). The purpose of this study was to evaluate the long-term outcome of single-event multilevel surgery (SEMLS) in combination with hip reconstruction by using a periacetabular osteotomy as described by Dega concerning post-operative remodeling and plasticity of the femoral head post-operatively. METHODS: A total of 72 patients with CP as the primary disease and in whom a complex surgical hip reconstruction was performed during SEMLS between 1998 and 2004 were included in the study. There were 45 men and 27 women, with a median age of 7.6 (4.7-16.3) years at the time SEMLS was performed. The mean follow-up time was 7.7 years (4.9-11.8). X-rays were taken before and after surgery, and Rippstein 1 and 2 were used for follow-up. As the most reliable value for decentration, migration percentage (MP) as described by Reimers was used. To measure hip-joint cover at follow-up, the centre-edge angle was used. The hip was divided into four different categories according to sphericity and congruity. Using this approach, we could evaluate joint remodeling. RESULTS: Pre-operatively, the mean MP measured by X-ray was 68 %. Directly after surgery, this value decreased on average by 12 % and at the long-term follow-up was 16.0 % on average. A high rate of incongruence was observed on X-rays taken directly after surgery: 66 hip joints were classified as incongruent. The number of aspherical and incongruent joints decreased to 54 at the follow-up examination. CONCLUSION: Data of our study with high plasticity of the hip joint suggest that even if the femoral head is deformed and a persistent incongruency after surgery is expected, hip reconstruction can be recommended.