Real-time motion onset recognition for robot-assisted gait rehabilitation.

BACKGROUND: Many patients with neurological movement disorders fear to fall while performing postural transitions without assistance, which prevents them from participating in daily life. To overcome this limitation, multi-directional Body Weight Support (BWS) systems have been developed allowing them to perform training in a safe environment. In addition to overground walking, these innovative/novel systems can assist patients to train many more gait-related tasks needed for daily life under very realistic conditions. The necessary assistance during the users' movements can be provided via task-dependent support designs. One remaining challenge is the manual switching between task-dependent supports. It is error-prone, cumbersome, distracts therapists and patients, and interrupts the training workflow. Hence, we propose a real-time motion onset recognition model that performs automatic support switching between standing-up and sitting-down transitions and other gait-related tasks (8 classes in total). METHODS: To predict the onsets of the gait-related tasks, three Inertial Measurement Units (IMUs) were attached to the sternum and middle of outer thighs of 19 controls without neurological movement disorders and two individuals with incomplete Spinal Cord Injury (iSCI). The data of IMUs obtained from different gait tasks was sent synchronously to a real-time data acquisition system through a custom-made Bluetooth-EtherCAT gateway. In the first step, data was applied offline for training five different classifiers. The best classifier was chosen based on F1-score results of a Leave-One-Participant-Out Cross-Validation (LOPOCV), which is an unbiased way of testing. In a final step, the chosen classifier was tested in real time with an additional control participant to demonstrate feasibility for real-time classification. RESULTS: Testing five different classifiers, the best performance was obtained in a single-layer neural network with 25 neurons. The F1-score of [Formula: see text] and [Formula: see text] are achieved on testing using LOPOCV and test data ([Formula: see text], participants = 20), respectively. Furthermore, the results from the implemented real-time classifier were compared with the offline classifier and revealed nearly identical performance (difference = [Formula: see text]). CONCLUSIONS: A neural network classifier was trained for identifying the onset of gait-related tasks in real time. Test data showed convincing performance for offline and real-time classification. This demonstrates the feasibility and potential for implementing real-time onset recognition in rehabilitation devices in future.

Short-term outcome of double-shelled braces in neuromuscular scoliosis.

INTRODUCTION: Scoliosis in patients with neuromuscular disease is a common issue and leads to secondary impairment. It is thus important to help such patients to regain and retain best possible stability to improve their quality of life. One option is the double-shelled brace (DSB). The aim of this study was to provide information on the degree of correction when using a DSB on patients with neuromuscular scoliosis. METHODS: We included patients with neuromuscular scoliosis treated with double-shelled braces in this retrospective study. Radiographs of the full spine were taken with and without the DSB, the Cobb angles were measured and compared. The correction was expressed in percent of the lumbar and thoracic Cobb angles. In addition, compounding factors such as age, sex, type of the curves, and movement disorder were included. RESULTS: We analyzed data from 84 patients with scoliosis with different neuromuscular disorders. The mean age was 12.3 years (± 5.9). In the lumbar spine we detected an improvement of 27.5% (SD ± 32.9), in the thoracic spine 25.3% (SD ± 38.0). INTERPRETATION: Short-term corrections with a double-shelled brace in neuromuscular scoliosis present an average improvement of one fourth of the lumbar and thoracic Cobb angles and, independent of age, sex, movement disorder, shape or type of the curve. Only spasticity has an influence on the lumbar scoliosis outcome.

Hip reconstruction in closed triradiate cartilage: long-term outcomes in patients with cerebral palsy.

INTRODUCTION: Hip reconstruction is an established procedure in pediatric patients with neurogenic hip dislocation. An open triradiate cartilage provides the advantage of a high plasticity of the bone which prevents an intraarticular fracture and postoperative adaptation of shape. Some patients with dislocated hips, however, arrive late. A hip reconstruction is still feasible as shown earlier but the long-term risk for osteoarthritis, and recurrence of dislocation, and functional outcome is unknown. It is the aim of our investigation to evaluate long-term clinical and radiological outcomes of hip reconstruction by Dega type pelvic osteotomy performed after fusion of the triradiate epiphyseal cartilage in patients suffering from cerebral palsy. MATERIAL AND METHODS: We retrospectively analyzed 43 hips in 37 patients with a hip reconstruction for correction of hip dislocation or subluxation. In all patients, the triradiate cartilage was fused before surgery. Age at surgery was 15 years and 2 months on average and follow-up time was mean 13 years 5 months. RESULTS: Mean Kellgren Lawrence score at final follow-up was significantly higher than at preoperative investigation (P < 0.00001). At long-term follow-up 3 of 43 hips had developed pain, and 1 of them required arthroplasty. Reimers´ migration index was stable over the years and was not higher at last follow-up compared to the index observed shortly after surgery (P = 0.857), so was the Sharp angle (P = 0.962). We found no significant reduction in the range of motion of the hip in the sagittal plane. CONCLUSION: We noted mild radiological signs of osteoarthritis which possibly occur due to an intraarticular acetabulum fracture during bending down the acetabulum. Nevertheless, hip reconstruction in patients with cerebral palsy and closed triradiate cartilage remains a valuable option as it results in a stable, painless hip for more than a decade.

Long-term follow-up after multilevel surgery in cerebral palsy.

INTRODUCTION: Single-event multilevel surgery (SEMLS) is frequently used to correct pathological gait patterns in children with bilateral spastic cerebral palsy (BSCP) in a single session surgery. However, in-depth long-term evaluation reports of gait outcomes are limited. Therefore, we investigated if SEMLS is able to correct lower extremity joint and pelvic angles during gait towards typically developing gait patterns (TDC) in children with BSCP, and if so, if this effect is durable over a 10-year period. MATERIALS AND METHODS: In total 13 children with BSCP GMFCS level II at time of index-surgery between the ages of 7.7-18.2 years at the time of SEMLS were retrospectively recruited. Three-dimensional gait data were captured preoperatively, as well as at short-, mid-, and long-term post-operatively, and used to analyze: movement analysis profile (MAP), gait profile score (GPS), and lower extremity joint and pelvic angles over the course of a gait cycle using statistical parametric mapping. RESULTS: In agreement with previous studies, MAP and GPS improved towards TDCs after surgery, as did knee extension during the stance phase (ɳ2 = 0.67; p < 0.001), while knee flexion in the swing phase (ɳ2 = 0.67; p < 0.001) and pelvic tilt over the complete gait cycle (ɳ2 = 0.36; p < 0.001) deteriorated; no differences were observed between follow-ups. However, further surgical interventions were required in 8 out of 13 of the participants to maintain improvements 10 years post-surgery. CONCLUSIONS: While the overall gait pattern improved, our results showed specific aspects of the gait cycle actually deteriorated post-SEMLS and that a majority of the participants needed additional surgery, supporting previous statements for the use of multilevel surgery rather than SEMLS. The results highlight that the field should not only focus on the overall gait scores when evaluating treatment outcomes but should offer additional long-term follow-up of lower extremity function.

[The influence of backpack weight in school children: gait, muscle activity, posture and stability]. / Einfluss des Schulrucksackgewichtes bei Grundschulkindern: Gang, Muskelaktivität, Haltung und Stabilität.

BACKGROUND: Wearing a school backpack every day may cause postural problems and affect the gait pattern of children and adolescents. The aim of the present study was to analyze the influence of a 4 kg backpack load on the gait pattern and postural sway. OBJECTIVES: The aim of the present study was to analyze the influence of a backpack load of 4 kg on the gait and postural sway of elementary school children. MATERIAL AND METHODS: In this prospective study, a group of 12 elementary school children aged between 7 and 10 years without neurological or orthopedic problems participated. The measurements included a clinical examination, three-dimensional gait analysis with electromyographic recordings and measurement of postural sway on a force plate. RESULTS: The backpack load, on average 15% of the body weight, led to a slower walking speed, shorter step length and increased double-support phase. Increased anterior pelvic and trunk tilt, as well as hip flexion were also observed. Furthermore, the muscle activity and postural sway of the children were affected by the increased load. CONCLUSIONS: School backpacks weighing 4 kg caused changes in gait, muscle activity, posture and stability in elementary school children. Due to the weight of the backpack, the centre of mass shifted backwards and the children became less stable. During gait, this was compensated by increased anterior pelvic and trunk tilt and increased hip flexion. The activity of the paraspinal muscles was decreased and indicates that the backpack is carried passively. This may cause a negative long-term effect.

Absorbable and non-absorbable suture fixation results in similar outcomes for tibial eminence fractures in children and adolescents.

PURPOSE: To evaluate efficacy and safety of extraphyseal tibial eminence avulsion fracture repair with absorbable sutures and a distal bone bridge fixation in comparison to previously described technique with non-absorbable sutures and distal screw fixation. METHODS: In a physeal-sparing technique, tibial eminence fractures (n = 25; McKeever type II/III n = 11/14) were either treated in group A (n = 15, follow-up 28.1 months) using an absorbable suture fixed over a bone bridge or in group B (n = 10, follow-up 47.4 months) with a non-absorbable suture wrapped around an extraarticular tibial screw. IKDC and Lysholm scores were assessed, and the difference between the surgical and contralateral knee in anteroposterior (AP) translation, measured with a Rolimeter. RESULTS: There was no significant difference between group A and group B in IKDC and Lysholm scores with 90.1 points ± 10.2 and 94.1 points ± 8.1, respectively (n.s.). AP translation did not differ between groups (n.s.). Eight of ten screws in group B had to be removed in a second intervention. A total of four arthrofibroses were counted (three in group A). CONCLUSION: Extraphyseal tibial eminence repair with absorbable sutures and a distal bone bridge fixation results in similar rates of radiographic and clinical healing at 3 months after surgery as non-absorbable sutures tied around a screw, while avoiding the need for hardware removal. The minimal invasive technique to fix an eminence fracture without any permanent sutures or hardware is advantageous for children. To our knowledge, this is the first study that compares non-absorbable with absorbable sutures for a physeal-sparing technique. LEVEL OF EVIDENCE: III.

Implant failure after biodegradable screw fixation in osteochondritis dissecans of the knee in skeletally immature patients.

PURPOSE: The primary purpose of this study was to retrospectively assess the incidence of bioabsorbable screw failure in skeletally immature patients treated for osteochondritis dissecans (OCD) of the knee. The second purpose was to assess implant degradation, focusing on differential breakdown of the intraosseous and extraosseous parts of the screw on magnetic resonance imaging (MRI). METHODS: In this retrospective study, 24 patients (30 knees) with MRI-confirmed OCD were treated with a total of 61 biodegradable screws and followed up for a minimum of 2 years or until the onset of new symptoms. MRI scans were performed every 6 months to assess differences in signal intensity between the head and body of the screw. The angle between the surface of the head and the body of the screw was measured, with an angle greater than 90° interpreted as indicating a broken screw (i.e., failed implant). RESULTS: Seven screws (all 2.7 mm, 11.5% of all screws) in 5 patients were considered broken screws. The implant failed completely in an additional 4 patients with breakage of 7 of 9 screws; 3 patients were considered late failures, occurring after more than 6 months. Altogether, 14 of a total of 61 screws (23%) were broken. CONCLUSIONS: Screw breakage is a surprisingly frequent cause of failure in resorbable OCD fixation in skeletally immature patients. MRI data showed differential decomposition of the screw within and outside of bone as a possible cause. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Meniscal suturing versus screw fixation for treatment of osteochondritis dissecans: clinical and magnetic resonance imaging results.

PURPOSE: The purpose of this study was to compare meniscal stabilization alone with screw fixation in restoring subjective and objective knee function and structural cartilage integrity in skeletally immature patients with osteochondritis dissecans (OCD) of the knee. METHODS: This study comprised 28 patients (32 knees) with magnetic resonance imaging (MRI)-confirmed OCD. Unstable menisci were treated with either stabilization (15 patients, 16 knees) or screw fixation (13 patients, 16 knees; control group). Patients were assessed by functional scoring (Hughston, International Knee Documentation Committee [IKDC]) and MRI for a minimum follow-up period of 2.5 years. RESULTS: In the meniscus stabilization group, the Hughston score improved from 1.4 to 3.8 (P < .01). There was improvement in the IKDC grade, from grade C preoperatively to grade A in 14 knees and grade B in 2 (P < .01). Of 16 knees, 15 had complete defect resolution on MRI by 1 year. There were 3 complications: 1 wound infection, 1 case of trauma requiring reoperation, and 1 revision because of treatment failure at 6 months. In the screw fixation group, the Hughston score improved from 1.4 to 3.6 (P < .01). There was a significant improvement in IKDC grade, from grade C preoperatively to grade A in 11 knees and grade B in 5 (P < .01). At 2 years postoperatively, no differences in these variables were found between the groups. CONCLUSIONS: Meniscal suturing alone for the treatment of an OCD of the knee shows good or excellent results in terms of clinical scoring and MRI assessment at almost 3 years' follow-up. The results are comparable with those of screw fixation but with a faster recovery in the postoperative course. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Poor outcome at 7.5 years after Stanisavljevic quadriceps transposition for patello-femoral instability.

INTRODUCTION: Congenital dislocation of the patella and recurrent symptomatic dislocation in adolescents are difficult pathologies to treat. Stanisavljevic described an extensive release procedure essentially involving medializing the entire lateral quadriceps and medial soft tissue stabilization. There are no significant series reporting the success of this method. This procedure has been performed in our institution over several years and we report our results. METHOD: Retrospective case series. Between 1990 and 2007, 20 knees in 13 children and adolescents (mean age 12.8 years; 4-17, 7 female) with recurrent or congenital dislocation of the patella (8 knees) underwent this procedure after failed conservative treatment (mean follow-up 7.5 years; 4-16). All were immobilized in a long leg cast for 6 weeks. RESULTS: Five knees in five patients (20 %, 1 congenital dislocation) reported their knees as improved without further dislocations. Out of the 15 knees with failures (80 %) 12 in six patients (60 %) were revised due to redislocation. Three knees in two patients (15 %) still had dislocations or subluxations, but any revision was refused. Three knees in three patients caused pain and discomfort during daily activity. Redislocation first developed after a mean of 21.3 months (4-72) postoperatively. Only one patient had returned to sport at the 12-month follow-up. DISCUSSION: The Stanisavljevic procedure produces a mediocre success rate with our long-term follow-up series showing a failure rate up to 80 %. We therefore recommend more specific procedures dealing with the anatomical deformity such as trochleaplasty to produce superior success rates.

Redisplacement rate after bony hip reconstructive surgery in nonambulatory patients with cerebral palsy: a systematic review and meta-analysis.

Purpose: Up to 90% of nonambulatory patients with cerebral palsy (CP) experience hip displacement during their lifetime. Reconstructive surgery is recommended. Redisplacement rate is an outcome parameter. Methods: In a systematic literature review (MEDLINE, Embase and CENTRAL databases) until January 2023 we searched for reports with redisplacement rates after bony hip reconstructive surgery in nonambulatory patients. Quantitative data synthesis, subgroup analysis and meta-regression with moderators were carried out. Results: The pooled mean redisplacement rate was 16% (95% CI: 12-21%) with a prediction interval of 3-51% (Q: 149; df: 32; P < 0.001; I2: 78%; τ2: 0.67 and τ: 0.82) in 28 studies (1540 hips). Varus derotation osteotomy (VDRO) alone showed a higher redisplacement rate than VDRO + pelvic osteotomy (30% vs 12%, P < .0001). Mean age in the VDRO-alone subgroup was 7.1 years and in the combined group 9.5 years (P = .004). In meta-regression, lower redisplacement rates were observed with higher preoperative migration index (MI) (correlation coefficient: -0.0279; P = .0137), where comprehensive surgery was performed. Variance in true effects are explained by type of bone surgery (57%), preoperative MI (11%), age (5%) and MI for definition of failure (20%). No significant reduction in the redisplacement rate could be observed over the mid-years of studies (1977-2015). Conclusion: Our pooled data support the more extensive surgical approach in patients with high preoperative MI and emphasize the superiority of combined surgery. Studies should report a coordinated set of parameters and outcome classifications according to internationally accepted gradings to reduce redisplacement in future.

Effect of femoral derotational osteotomy in patients with idiopathic increased femoral anteversion on joint loading and muscular demands.

Purpose: This study aimed to analyse the effect of the femoral derotational osteotomy (FDRO) on joint kinematics, kinetics, joint and muscle forces, and muscle moments in patients with idiopathic increased femoral anteversion compared with typically developing children (TDC). Methods: In this retrospective study, 17 patients (25 limbs, 13.2 ± 2.2 years, femoral anteversion = 49.0° ± 7.1°) were compared to nine TDC (9 limbs, 12.0 ± 3.0 years, femoral anteversion = 18.7° ± 4.1°). Gait analysis was performed 8.5 ± 7.2 months pre-surgery and 17.3 ± 5.5 months post-surgery. Joint angles, moments and forces as well as muscle forces and muscle contributions to joint moments were analysed using statistical parametric mapping. Results: Significant improvements in kinematics (hip rotation, foot progression, knee and hip flexion) were observed pre- to post-FDRO. Joint forces remained unaltered after surgery and did not differ from TDC. Gluteus minimus and deep external rotators muscle forces decreased in mid-stance, while adductor muscle forces increased during stance post-op compared to pre-op. Due to an improved knee extension postoperatively, the rectus femoris muscle force decreased to normal values during mid- and terminal stance. Postoperatively, only the deep external rotator muscle forces differed from TDC. Conclusions: This study showed that FDRO can restore muscle forces and muscle contributions to joint moments in addition to normal gait kinematics, while joint contact forces remain within normative ranges. This knowledge might also apply to other conditions in which pathological femoral anteversion is present.

Single procedure tibialis anterior tendon shortening in combination with Achilles tendon lengthening in unilateral cerebral palsy improves swing phase dorsiflexion in gait.

Purpose: Tibialis anterior tendon shortening combined with tendon Achilles lengthening showed satisfactory short- and long-term outcomes for pes equinus treatment. This retrospective study aimed to evaluate the effectiveness of a single tibialis anterior tendon shortening-tendon Achilles lengthening procedure for treating pes equinus, in a homogeneous unilateral cerebral palsy patient group. Methods: Gait analysis was conducted on 22 unilateral cerebral palsy patients (mean age at surgery = 13.3 years, standard deviation = 3 years) before and within 2.5 years (standard deviation = 0.61 years) after the tibialis anterior tendon shortening-tendon Achilles lengthening procedure. Primary outcome measures included foot drop occurrence in swing, foot dorsiflexion and the first ankle rocker presence compared to healthy reference data. Movement analysis profile and gait profile score were also calculated for the entire gait cycle. The clinical exam and the A2 peak ankle power were analyzed. Statistical analysis used the paired Wilcoxon's sign rank test (p < 0.05). Results: Post-operatively, significant improvements were observed in ankle dorsiflexion during swing (p = 0.0006) and reduced foot drop in swing (p = 0.0107). The occurrence of a first ankle rocker did not significantly change (p = 0.1489). Significant improvements in gait profile score and movement analysis profile for all joints and planes indicate overall gait quality improvement. The foot progression changed significantly (p = 0.0285), with a greater external orientation. Nineteen out of 22 patients were able to quit wearing their ankle foot orthoses. Conclusion: Tibialis anterior tendon shortening and tendon Achilles lengthening combination yielded positive outcomes, showing increased foot dorsiflexion, first ankle rocker presence, and overall improved gait quality. These findings support the effectiveness of this surgical approach for treating pes equinus in children with unilateral spastic cerebral palsy.

Are results after single-event multilevel surgery in cerebral palsy durable?

BACKGROUND: Gait and function may deteriorate with time in patients with spastic diplegia. Single-event multilevel surgery often is performed to either improve gait or prevent deterioration. However it is unclear whether the presumed gait improvements are durable. QUESTIONS/PURPOSES: We therefore determined whether (1) single-event multilevel surgery improves gait in patients with spastic diplegia and (2) whether the improved function is durable. METHODS: We retrospectively reviewed the data of 14 patients with spastic diplegia. At the time of surgery, one patient had gross motor Level I function, 10 patients had Level II function, and three patients had Level III function. There were four females and 10 males with a mean age of 13 years (range, 7-18 years). The mean number of orthopaedic procedures per single-event multilevel surgery session was 7.4 ± 2.8 (median, 6.5; range, 4-15). We used instrumented gait analysis to determine joint ROM, movement analysis profiles, and the gait profile score. The minimum followup was 1 year (mean, 2 years; range, 1-3 years). RESULTS: At last followup, movement analysis profiles for knee flexion, for ankle dorsiflexion, and for foot progression improved as did the gait profile score. Additional surgery after the index procedure was performed in nine of the 14 patients because of relapse of the original or new gait problems. Major surgical adverse events occurred in one of the 14 patients. CONCLUSIONS: Severe gait dysfunction in patients with spastic diplegia can be improved short-term in one operative session by single-event multilevel surgery, but to preserve the early improvements many patients require additional surgery. It is unknown whether the improvements will last for decades. LEVEL OF EVIDENCE: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Control of Tibial Advancement by the Plantar Flexors during the Stance Phase of Gait Depends on Knee Flexion with Respect to the Ground Reaction Force.

During the stance phase of a normal gait, the triceps surae muscle controls the advancement of the tibia, which contributes to knee extension. Plantar flexor weakness results in excessive dorsiflexion, and consequently, the knee loses this contribution. However, increasing knee flexion is also seen in patients with cerebral palsy who do not have plantar flexor weakness. We aimed to understand this mechanism through the use of a musculoskeletal dynamic model. The model consists of solid segments connected with rotatory joints and springs to represent individual muscles. It was positioned at different degrees of ankle plantarflexion, knee flexion, and hip flexion. The soleus muscle was activated concentrically to produce plantarflexion and push the foot against the ground. The resulting knee extension was analyzed. The principal determinant of knee flexion or extension associated with ankle plantarflexion was the position of the knee joint center. When this was anterior to the line of action of the ground reaction force (GRF), the soleus contraction resulted in increased knee flexion. The knee extension was obtained when the knee was flexed less than approximately 25°. The relation between joint angles, anthropometric parameters, and the position of the GRF was expressed in a mathematical formulation. The clinical relevance of this model is that it explains the failure of plantar flexor control on knee extension in patients with cerebral palsy, when increased knee flexion can occur even if there is a normal or plantarflexed foot position.

The functional role of hip muscles during gait in patients with increased femoral anteversion.

BACKGROUND: Femoral anteversion affects the lever arm and moment-generating capacity of the hip abductors, while an increased hip internal rotation during walking was proposed to be a compensatory mechanism to restore the abductive lever arm. Children with isolated increased femoral anteversion, however, do not always present a deficit in the net hip abduction moment during gait, suggesting that a more comprehensive understanding of the effect of morphology and motion on muscle forces and moments is needed to aid clinical decision making. RESEARCH QUESTION: Are muscle contributions to hip joint moments and muscle forces altered in patients with increased femoral anteversion and internally rotated gait pattern compared to a control group of typically developing children? And how would the functional role of the muscle be altered if the patients walked straight? METHODS: This follow-up study compared patients with increased femoral anteversion (n = 42, 12.8 ± 1.9 years, femoral anteversion: 39.6 ± 6.9°) to controls (n = 9, 12.0 ± 3.0 years, femoral anteversion: 18.7 ± 4.1°). Muscle forces and moment contributions were calculated using personalized musculoskeletal models. Additionally, a hypothetical scenario, in which the gait of the controls was modelled with an anteverted femoral morphology, was used to understand what would happen if the patients walked straight. RESULTS: Gluteus medius abductive contribution was lower in patients compared to controls, despite a comparable net abduction moment around the hip. Patients presented lower muscle forces. However, if modelled to walk straight, they would require higher forces as well as a larger co-contraction of both hip internal and external rotators in the transversal plane. SIGNIFICANCE: This study suggests that patients with increased femoral anteversion walking with an internally rotated gait pattern present lower muscle forces, but when modelled to walk straight muscle forces increase. The current results provide important information to better understand this condition and improve treatment recommendations in these patients.

Can developmental trajectories in gait variability provide prognostic clues in motor adaptation among children with mild cerebral palsy? A retrospective observational cohort study.

Aim: To investigate whether multiple domains of gait variability change during motor maturation and if this change over time could differentiate children with a typical development (TDC) from those with cerebral palsy (CwCP). Methods: This cross-sectional retrospective study included 42 TDC and 129 CwCP, of which 99 and 30 exhibited GMFCS level I and II, respectively. Participants underwent barefoot 3D gait analysis. Age and parameters of gait variability (coefficient of variation of stride-time, stride length, single limb support time, walking speed, and cadence; as well as meanSD for hip flexion, knee flexion, and ankle dorsiflexion) were used to fit linear models, where the slope of the models could differ between groups to test the hypotheses. Results: Motor-developmental trajectories of gait variability were able to distinguish between TDC and CwCP for all parameters, except the variability of joint angles. CwCP with GMFCS II also showed significantly higher levels of gait variability compared to those with GMFCS I, these levels were maintained across different ages. Interpretation: This study showed the potential of gait variability to identify and detect the motor characteristics of high functioning CwCP. In future, such trajectories could provide functional biomarkers for identifying children with mild movement related disorders and support the management of expectations.

Identifying treatment non-responders based on pre-treatment gait characteristics - A machine learning approach.

Background: Paediatric movement disorders such as cerebral palsy often negatively impact walking behaviour. Although clinical gait analysis is usually performed to guide therapy decisions, not all respond positively to their assigned treatment. Identifying these individuals based on their pre-treatment characteristics could guide clinicians towards more appropriate and personalized interventions. Using routinely collected pre-treatment gait and anthropometric features, we aimed to assess whether standard machine learning approaches can be effective in identifying patients at risk of negative treatment outcomes. Methods: Observational data of 119 patients with movement disorders were retrospectively extracted from a local clinical database, comprising sagittal joint angles and spatiotemporal parameters, derived from motion capture data pre- and post-treatment (physiotherapy, orthosis, botulin toxin injections, or surgery). Participants were labelled based on their change in gait profile score (GPS, non-responders with a decline in GPS of <1.6° vs. responders). Their pre-treatment features (sagittal joint angles, spatiotemporal parameters, anthropometrics) were used to train a support vector machine classifier with 5-fold cross-validation and Bayesian optimization within a MATLAB-based Classification Learner App. Results: An average accuracy of 88.2 ± 0.5 % was achieved for identifying participants whose gait will not respond to treatment, with 64 % true negative rate and an area under the curve of 88 %. Conclusion: Overall, a classical machine learning model was able to identify patients at risk of not responding to treatment, based on gait features and anthropometrics collected prior to treatment. The output of such a model could function as a warning signal, notifying clinicians that a certain individual might not respond well to the standard of care and that a more personalized intervention might be needed.

The Non-Affected Muscle Volume Compensates for the Partial Loss of Strength after Injection of Botulinum Toxin A.

Local botulinum toxin (BTX-A, Botox®) injection in overactive muscles is a standard treatment in patients with cerebral palsy. The effect is markedly reduced in children above the age of 6 to 7. One possible reason for this is the muscle volume affected by the drug. Nine patients (aged 11.5; 8.7-14.5 years) with cerebral palsy GMFCS I were treated with BTX-A for equinus gait at the gastrocnemii and soleus muscles. BTX-A was administered at one or two injection sites per muscle belly and with a maximum of 50 U per injection site. Physical examination, instrumented gait analysis, and musculoskeletal modelling were used to assess standard muscle parameters, kinematics, and kinetics during gait. Magnetic resonance imaging (MRI) was used to detect the affected muscle volume. All the measurements were carried out pre-, 6 weeks post-, and 12 weeks post-BTX-A. Between 9 and 15% of the muscle volume was affected by BTX-A. There was no effect on gait kinematics and kinetics after BTX-A injection, indicating that the overall kinetic demand placed on the plantar flexor muscles remained unchanged. BTX-A is an effective drug for inducing muscle weakness. However, in our patient cohort, the volume of the affected muscle section was limited, and the remaining non-affected parts were able to compensate for the weakened part of the muscle by taking over the kinetic demands associated with gait, thus not enabling a net functional effect in older children. We recommend distributing the drug over the whole muscle belly through multiple injection sites.

Distal femoral osteotomy using the LCP pediatric condylar 90-degree plate in patients with neuromuscular disorders.

BACKGROUND: In patients with cerebral palsy and other neuromuscular disorders, correction of a fixed knee flexion deformity is thought to be crucial for the improvement of gait. The distal femoral extension osteotomy (DFO) is one method to achieve this goal. The standard implant for fixation of the 2 fragments in DFO is the conventional AO blade plate. The aim of this study was to report the outcome of using the new LCP Pediatric Condylar 90-Degree Plate for DFO. METHODS: Thirty-eight patients undergoing 63 DFOs were included. The mean age was 16.3±4.4 years (range, 4 to 27 y) at the time of surgery. Thirty-two patients had a diagnosis of cerebral palsy and 6 patients had other neuromuscular disorders including myelomeningocoele and arthrogryposis. Thirteen patients had unilateral procedures and 25 had bilateral procedures. RESULTS: The mean duration of the surgical intervention was 67.9±26.5 minutes (range, 30 to 180 min) and the mean blood loss was 100.0±42.1 mL (range, 50 to 250 mL). In 84% of the cases, large-fragment (5.0 mm) implants were used. The mean extension correction in 84% of the patients (n=53) was 22.8±10.3 degrees (range, 5 to 50 degrees). In this series, there were 2 complications in 63 osteotomies (3%). Radiologic follow-up of the cohort was until the time of plate removal (14.2±4.3 mo; range, 6 to 26 mo). Three months after the index operation, all osteotomies were radiologically consolidated. At this time and at plate removal, there were no malunions or nonunions in this cohort. Clinical follow-up of the cohort was performed until the end of the study (mean 35.5±6.7 mo; range, 22 to 46 mo). At the end of the study, 59 plates (94%) had been removed. CONCLUSIONS: The new LCP Pediatric Condylar 90-Degree Plate provides stable and safe fixation of distal femoral correction osteotomies in patients with neuromuscular disorders. LEVEL OF EVIDENCE: Level IV.

Altered Muscle Contributions are Required to Support the Stance Limb During Voluntary Toe-Walking.

Toe-walking characterizes several neuromuscular conditions and is associated with a reduction in gait stability and efficiency, as well as in life quality. The optimal choice of treatment depends on a correct understanding of the underlying pathology and on the individual biomechanics of walking. The objective of this study was to describe gait deviations occurring in a cohort of healthy adult subjects when mimicking a unilateral toe-walking pattern compared to their normal heel-to-toe gait pattern. The focus was to characterize the functional adaptations of the major lower-limb muscles which are required in order to toe walk. Musculoskeletal modeling was used to estimate the required muscle contributions to the joint sagittal moments. The support moment, defined as the sum of the sagittal extensive moments at the ankle, knee, and hip joints, was used to evaluate the overall muscular effort necessary to maintain stance limb stability and prevent the collapse of the knee. Compared to a normal heel-to-toe gait pattern, toe-walking was characterized by significantly different lower-limb kinematics and kinetics. The altered kinetic demands at each joint translated into different necessary moment contributions from most muscles. In particular, an earlier and prolonged ankle plantarflexion contribution was required from the soleus and gastrocnemius during most of the stance phase. The hip extensors had to provide a higher extensive moment during loading response, while a significantly higher knee extension contribution from the vasti was necessary during mid-stance. Compensatory muscular activations are therefore functionally required at every joint level in order to toe walk. A higher support moment during toe-walking indicates an overall higher muscular effort necessary to maintain stance limb stability and prevent the collapse of the knee. Higher muscular demands during gait may lead to fatigue, pain, and reduced quality of life. Toe-walking is indeed associated with significantly larger muscle forces exerted by the quadriceps to the patella and prolonged force transmission through the Achilles tendon during stance phase. Optimal treatment options should therefore account for muscular demands and potential overloads associated with specific compensatory mechanisms.