Biomechanical maturation of foot joints in typically developing boys: Novel insight in mechanics and energetics from a cross-sectional study.

BACKGROUND: A growing body of quantitative evidence has been provided regarding age-related differences in plantar foot loading, multi-segment foot kinematics and muscle activity. Fundamental insight into the joint mechanics and energetics of the maturing foot has yet to be provided. RESEARCH QUESTION/HYPOTHESIS: It was hypothesized that so-called 'biomechancial maturation' joint kinetics would be observed in children underneath the age of eight and that older age-groups would not differ from each other in these parameters. METHODS: Fourty-three typically developing boys were recruited and allocated to three different age groups: 1) an early childhood group, 2) a middle childhood group, and 3) an early and late adolescence group. Multi-segment joint kinematics and kinetics of the Ankle-, Chopart-, Lisfranc- and Hallux joint were collected during barefoot walking. One-way Analysis of Covariance was conducted to examine differences among the outcome measures with group as a fixed factor and walking cadence as covariate. RESULTS: The youngest group differed significantly from the other two age groups with respect to their ankle and chopart joint peak plantarflexion moment (p < 0.05). Ankle and chopart joint peak power generation as well as the lisfranc peak plantarflexion moment was found to be significantly lower in the youngest age group compared to the oldest group (p < 0.05). At the lisfranc joint, the youngest age group demonstrated a significantly higher peak plantarflexion velocity compared to the two older age groups (p < 0.05). SIGNIFICANCE: This study provides novel insight into the biomechanical maturation of the developing foot which may guide clinical interventions in paediatric cohorts.

Age estimation based on magnetic resonance imaging of the ankle joint in a modern Chinese Han population.

OBJECTIVES: To expand the database on magnetic resonance imaging (MRI) analysis of distal tibial and calcaneal epiphyses as proposed by Saint-Martin et al. and investigate a more elaborate staging technique to establish regression models for age estimation in a modern Chinese Han population. MATERIALS AND METHODS: T1-weighted ankle MRIs were retrospectively collected from April 2008 to July 2019, and data from 590 individuals (372 males and 218 females; aged from 8 to 25 years old) were obtained. One-sided sagittal images were assessed because data from both sides were considered coincidental, as no significant differences were found (P > 0.05). Three-stage and six-stage staging techniques were applied separately and subsequently compared. A subset was re-assessed a second time and by a different observer. Regression models were established accordingly. RESULTS: Our results showed very good repeatability and consistency of two staging techniques (all Cohen's kappa values were more than 0.8). By comparison, the values of the coefficient of determination (R2) of the six-stage technique were generally higher than those of the three-stage technique. Compared with the distal tibia and two ankle bones combined, the calcaneus decreased the mean absolute deviation (MAD) with the six-stage technique. In males, incorporating only the calcaneus resulted in a MAD of 2.15 years, with correct classification rates of 87.5% adults and 50.0% among minors. In females, the corresponding results were 1.67 years, 100.0%, and 44.4%, respectively. CONCLUSIONS: The six-stage technique may outperform the three-stage technique in MRI analysis of ankle bones for age estimation, while age estimation based on the calcaneus may perform better than that based on the distal tibia or both ankle bones in a modern Chinese Han population.

Correlation of Incisura Anatomy With Syndesmotic Malreduction.

BACKGROUND: The anatomy of the syndesmosis is variable, yet little is known on the correlation between differences in anatomy and syndesmosis reduction results. The aim of this study was to analyze the correlation between syndesmotic anatomy and the modes of syndesmotic malreduction. METHODS: Bilateral postreduction ankle computed tomography (CT) scans of 72 patients treated for fractures with syndesmotic disruption were analyzed. Incisura depth, fibular engagement into the incisura, and incisura rotation were correlated with degree of syndesmotic malreduction in coronal and sagittal planes as well as rotational malreduction. RESULTS: Clinically relevant malreduction in the coronal plane, sagittal plane, and rotation affected 8.3%, 27.8%, and 19.4% of syndesmoses, respectively. The syndesmoses with a deep incisura and the fibula not engaged into the tibial incisura were at risk of overcompression, anteverted incisuras at risk of anterior fibular translation, and retroverted incisuras at risk of posterior fibular translation. CONCLUSIONS: Certain morphologic configurations of the tibial incisura increased the risk of specific syndesmotic malreduction patterns. LEVEL OF EVIDENCE: Level III, comparative study.

Relationship of medial gastrocnemius relative fascicle excursion and ankle joint power and work performance during gait in typically developing children: A cross-sectional study.

Muscle fascicles lengthen in response to chronic passive stretch through in-series sarcomere addition in order to maintain an optimum sarcomere length. In turn, the muscles' force generating capacity, maximum excursion, and contraction velocity is enhanced. Thus, longer fascicles suggest a greater capacity to develop joint power and work. However, static fascicle length measurements may not be taking sarcomere length differences into account. Thus, we considered relative fascicle excursions through passive ankle dorsiflexion may better correlate with the capacity to generate joint power and work than fascicle length. Therefore, the aim of the present study was to determine if medial gastrocnemius relative fascicle excursions correlate with ankle joint power and work generation during gait in typically developing children. A sample of typically developing children (n = 10) were recruited for this study and data analysis was carried out on 20 legs. Medial gastrocnemius relative fascicle excursion from resting joint angle to maximum dorsiflexion was estimated from trigonometric relations of medial gastrocnemius pennation angle and thickness obtained from B-mode real-time ultrasonography. Furthermore, a three-dimensional motion capture system was used to obtain ankle joint work and power during the stance phase of gait. Significant correlations were found between relative fascicle excursion and peak power absorption (-) r(14) = -0.61, P = .012 accounting for 31% variability, positive work r(18) = 0.56, P = .021 accounting for 31% variability, and late stance positive work r(15) = 0.51, P = .037 accounting for 26% variability. The large unexplained variance may be attributed to mechanics of neighboring structures (e.g., soleus or Achilles tendon mechanics) and proximal joint kinetics which may also contribute to ankle joint power and work performance, and were not taken into account. Further studies are encouraged to provide greater insight on the relationship between relative fascicle excursions and joint function.

How does lower leg alignment differ between soccer players, other athletes, and non-athletic controls?

PURPOSE: The influence of type and intensity of sports during growth on knee alignment was investigated. The second aim was to ascertain whether the distal femur or proximal tibia contribute most to knee alignment. Also, the influence of field position and leg dominancy on knee alignment in soccer players was audited. METHODS: Standardized full-leg standing digital radiographs were obtained from 100 males and 100 females on which 8 different alignment parameters were measured. Participants were questioned on their sports activities during different stages of growth. Sports activities were graded according to the Tegner score. RESULTS: The mean (±SD) hip-knee-ankle angle (HKA) was significantly lower (p < 0.001) in high-activity male athletes (-2.8° ± 2.4°) than in low-activity male athletes (-0.9° ± 1.9°). No differences in HKA were observed between different activity levels in females. Males who practiced soccer between 10-12 years and 15-17 years had, in turn, a lower HKA than athletes practicing other high-activity sports in these age categories (mean difference ≥1.2°, p ≤ 0.046). The most contributing factor for the varus alignment in male soccer players was a lower medial proximal tibial angle (MPTA). CONCLUSION: High-activity sports participation during youth is associated with varus alignment at the end of growth in males. The most pronounced bowlegs were observed in male soccer players, and this was primarily determined by the proximal tibia. Adjustments in loads applied to the knees during skeletal growth in males might prevent the development of varus alignment and associated pathology, but further studies are required. LEVEL OF EVIDENCE: Diagnostic study, Level III.

Growth Disturbance of the Distal Tibia in Patients With Idiopathic Clubfeet: Ankle Valgus and Anteflexion of the Distal Tibia.

BACKGROUND: The aim of this study was to evaluate the incidence of deformities of the distal tibia in patients with idiopathic clubfeet who had undergone surgical intervention with a circumferential release through a Cincinnati incision in early infancy. METHODS: A retrospective follow-up evaluation of children with idiopathic clubfoot was conducted. We reviewed children who had undergone surgical treatment by a circumferential release in our department after unsuccessful casting, and who were at least 10 years of age. Main focus was the measurement of anteroposterior and lateral view radiographs for distal tibia deformities. Of 65 patients (93 feet) who had surgery for idiopathic clubfoot from 1998 to 2002, radiographic data of 35 patients (52 feet) were analyzed. RESULTS: An anteflexion deformity was present in 25 of 52 feet (48.1%) and a valgus deformity in 29 of 52 feet (55.8%). A flat-top talus was evident to some degree in all cases. An abnormal lateral talocalcaneal angle was evident in 42.3%. CONCLUSIONS: These results show the importance of conducting follow-up evaluations on patients with idiopathic clubfoot for secondary deformities of the distal tibia. This is the first study, to our knowledge, highlighting the high incidence of distal tibial deformities after surgery for idiopathic clubfoot. It is unclear at this time whether this is also true for clubfeet after conservative treatment. However, patients with clubfeet should have radiographs of the ankle joint between the age of 10 and 12 years to be able to treat possible deformities through guided growth. LEVEL OF EVIDENCE: Level III.

Variation of Syndesmosis Anatomy With Growth.

BACKGROUND: Syndesmosis injury is common in trauma and in the sport medicine population. Diagnosis and treatment of this pathology is controversial in adult population and almost unknown in a growing and immature ankle. The objective of this study was to describe the relationship between the distal tibia and fibula in immature, growing, and mature children. METHODS: A retrospective imaging study was performed on ankle magnetic resonance images (MRI), which were divided into 3 groups according to age: immature, growing, or mature. The syndesmosis anatomy was described in 3 planes following an established measurement system. The measurement system was also validated (intraobserver and interobserver reproducibility) on a subgroup of 30 MRIs with 4 surgeons. RESULTS: The measurement system, previously described on CT scans, is valid when used on MRIs. The mediolateral translation significantly increases with growth and external rotation of fibula decreases. The anteroposterior position is also significantly different between groups but the ratios are similar. CONCLUSIONS: This study reported differences in distal tibiofibular relationship in a growing population. This information will be crucial in future development of diagnostic and follow-up criteria of syndesmosis injury. It also presented a valid and precise measurement system to describe syndesmotic anatomy in 3 planes. LEVEL OF EVIDENCE: Level IV.

Secondary ossification centers in the development of the medial malleolus.

BACKGROUND: Accessory ossicles of the medial malleolus have been reported, however, these have not been linked to a pattern of development and are considered anomalies. Here, we describe a pattern of ossification of the medial malleolus in children including a secondary ossification center. METHODS: Twenty anteroposterior (AP) and mortise x-rays of each sex and age from 4 to 12 were randomly selected from skeletally immature patients identified at our institution. X-rays were excluded if there was a cast or splint, fracture, hardware, or obvious tibial deformity. Each x-ray was evaluated and categorized to a 4-part stage of development. These stages were then applied to randomly selected AP hip to ankle films from the same age groups. RESULTS: Four distinct stages of medial malleolus ossification were identified on ankle x-rays. Stage 1 consists of the widening of the epiphysis that did not reach the medial border of the metaphysis. In stage 2, the epiphysis had widened medially to the level of the metaphysis, however, had not extended distally to the level of the dome of the talus. In stage 3, the proximal portion of the medial malleolus has ossified distal to the dome of the talus with ossification centers at this level identified. Stage 4 consisted of a completely fused ossification center extending distally to a mature medial malleolus. The stages were reconfirmed on AP standing hip to ankle to have a similar distribution, secondary ossification centers were more common in females aged 6 to -9 and males aged 8 to 11 years. CONCLUSIONS: The medial malleolus develops in predictable stages which may involve a secondary ossification center in the final stages of development. These findings were initially described on AP and mortise views, then confirmed on AP hip to ankle radiographs were evaluated to exclude potentially confounding ankle pain. These secondary ossification centers were seen at similar ages on both ankle and hip to ankle x-rays. LEVEL OF EVIDENCE: Level III.

Medial malleolar screw versus tension-band plate hemiepiphysiodesis for ankle valgus in the skeletally immature.

BACKGROUND: Ankle valgus is frequently encountered in skeletally immature patients in association with a variety of musculoskeletal disorders. Guided growth with temporary medial malleolar transphyseal screw (MMS) hemiepiphysiodesis is an established surgical treatment capable of correcting the angular deformity, but is often complicated by symptomatic screw head prominence and difficult hardware removal. Tension-band plate (TBP) hemiepiphysiodesis has recently been advocated as an alternative; however, the relative efficacy of these 2 techniques has not been directly investigated. Thus, the purpose of this study was to compare MMS and TBP in treatment of pediatric ankle valgus deformity. METHODS: Medical records and radiographs of all patients undergoing distal tibial medial hemiepiphysiodesis for ankle valgus between January 1, 2005 and November 1, 2010 at a pediatric orthopaedic specialty hospital were retrospectively reviewed. Radiographs obtained preoperatively and at 6-month intervals postoperatively were reviewed and the tibiotalar angle was measured. Patient age, sex, underlying diagnosis, concurrent surgical procedures, surgical and postoperative complications, and the presence or absence of symptomatic hardware complaints were documented. RESULTS: Sixty ankles in 42 patients met the inclusion criteria, with adequate radiographs and minimum postoperative follow-up of 12 months (mean: 34 mo). Thirty-five ankles were treated with MMS, and 25 with TBP. Good mean correction of the tibiotalar angle was achieved in both groups (MMS: pre-77.1 degrees to post-87.8 degrees over 25.2 mo; TBP: pre-81.3 to post-87.6 over 20.0 mo). The mean rate of correction was faster in ankles treated with MMS than TBP, but differences did not reach statistical significance (0.55 vs. 0.36 degrees/mo, respectively; P=0.057). Complications included 6 hardware-related surgical complications in MMS ankles (17.1%) and 1 in TBP ankles (4.0%). The incidence of symptomatic hardware complaints was low in both groups (MMS, 5.7%; TBP, 0%). CONCLUSIONS: Both MMS and TBP techniques can result in successful correction of ankle valgus in the growing child. Although the rate of deformity correction may be faster with MMS, TBP seems to be associated with fewer hardware-related complications. This information may aid the clinician in selecting the surgical option most appropriate for each individual patient. LEVEL OF EVIDENCE: Level II-retrospective study.

Childhood development of common drive to a human leg muscle during ankle dorsiflexion and gait.

Corticospinal drive has been shown to contribute significantly to the control of walking in adult human subjects. It is unknown to what extent functional change in this drive is important for maturation of gait in children. In adults, populations of motor units within a muscle show synchronized discharges during walking with pronounced coherence in the 15-50 Hz frequency band. This coherence has been shown to depend on cortical drive. Here, we investigated how this coherence changes with development. Forty-four healthy children aged 4-15 years participated in the study. Electromyographic activity (EMG) was recorded from pairs of electrodes placed over the right tibialis anterior (TA) muscle during static dorsiflexion and during walking on a treadmill (speed from 1.8 to 4.8 km h(-1)). A significant increase of coherence with increasing age was found in the 30-45 Hz frequency band (gamma) during walking and during static ankle dorsiflexion. A significant correlation with age was also found in the 15-25 Hz frequency band (beta) during static foot dorsiflexion. χ(2) analysis of differences of coherence between different age groups of children (4-6, 7-9, 10-12 and 13-15 years of age) revealed a significantly lower coherence in the gamma band for recordings during walking in children aged 4-6 years as compared to older children. Recordings during static dorsiflexion revealed significant differences in both the beta and gamma bands for children in the 4-6 and 7-9 years age groups as compared to the older age groups. A significant age-related decrease in step-to-step variability of toe position during the swing phase of walking was observed. This reduction in the step-to-step variability of gait was correlated with increased gamma band coherence during walking. We argue that this may reflect an increased ability to precisely control the ankle joint position with age, which may be contingent on maturation of corticospinal control of the foot dorsiflexor muscles.

Ankle deformity secondary to acquired fibular segmental defect in children.

BACKGROUND: The authors report the long-term effect of acquired pseudoarthrosis of the fibula on ankle development in children during skeletal growth, and the results of a long-term follow-up of Langenskiold's supramalleolar synostosis to correct an ankle deformity induced by an acquired fibular segmental defect in children. METHODS: Since 1980, 19 children with acquired pseudoarthrosis of the fibula were treated and followed up for an average of 11 years. Pseudoarthrosis was the result of a fibulectomy for tumor surgery, osteomyelitis of the fibula and traumatic segmental loss of the fibula in 10, 6, and 3 cases, respectively. Initially, a Langenskiold's operation (in 4 cases) and fusion of the lateral malleolus to the distal tibial epiphysis (in 1 case) were performed, whereas only skeletal growth was monitored in the other 14 cases. After a mean follow-up of 11 years, the valgus deformity and external tibial torsion of the ankle joint associated with proximal migration of the lateral malleolus needed to be treated with a supramallolar osteotomy in 12 cases (63%). These ankle deformities were evaluated using the serial radiographs and limb length scintigraphs. RESULTS: In all cases, early closure of the lateral part of the distal tibial physis, upward migration of the lateral malleolus, unstable valgus deformity and external tibial torsion of the ankle joint developed during a mean follow-up of 11 years (range, 5 to 21 years). The mean valgus deformity and external tibial torsion of the ankle at the final follow-up were 15.2 degrees (range, 5 degrees to 35 degrees) and 10 degrees (range, 5 degrees to 12 degrees), respectively. In 12 cases (12/19, 63%), a supramalleolar corrective osteotomy was performed but three children had a recurrence requiring an additional supramalleolar corrective osteotomy 2-4 times. CONCLUSIONS: A valgus deformity and external tibial torsion are inevitable after acquired pseudoarthrosis of the fibula in children. Both Langenskiöld supramalleolar synostosis to prevent these ankle deformities and supramalleolar corrective osteotomy to correct them in children are effective initially. However, both procedures cannot maintain the permanent ankle stability during skeletal maturity. Therefore any type of prophylactic surgery should be carried out before epiphyseal closure of the distal tibia occurs, but the possibility of a recurrence of the ankle deformities and the need for final corrective surgery after skeletal maturity should be considered.

The effect of tibial lengthening on immature articular cartilage of the ankle joint.

Is the articular cartilage of the immature ankle joint damaged by tibial lengthening? Sixteen immature rabbits underwent a 30% diaphyseal lengthening by tibial callotasis. Damage was assessed by scanning electronic microscopy and histomorphometry at the completion of distraction and after an additional 5 weeks. Despite joint contracture, little damage in the articular cartilage was observed in contrast to the knee joint. The findings show that the immature ankle joint is more resilient to stress than the knee and implies that reduced weight bearing and decreased joint movement alone are not sufficient to cause cartilage damage, at least in the ankle.

Ankle Deformity Secondary to Acquired Fibular Segmental Defect in Children

BACKGROUND: The authors report the long-term effect of acquired pseudoarthrosis of the fibula on ankle development in children during skeletal growth, and the results of a long-term follow-up of Langenskiold's supramalleolar synostosis to correct an ankle deformity induced by an acquired fibular segmental defect in children. METHODS: Since 1980, 19 children with acquired pseudoarthrosis of the fibula were treated and followed up for an average of 11 years. Pseudoarthrosis was the result of a fibulectomy for tumor surgery, osteomyelitis of the fibula and traumatic segmental loss of the fibula in 10, 6, and 3 cases, respectively. Initially, a Langenskiold's operation (in 4 cases) and fusion of the lateral malleolus to the distal tibial epiphysis (in 1 case) were performed, whereas only skeletal growth was monitored in the other 14 cases. After a mean follow-up of 11 years, the valgus deformity and external tibial torsion of the ankle joint associated with proximal migration of the lateral malleolus needed to be treated with a supramallolar osteotomy in 12 cases (63%). These ankle deformities were evaluated using the serial radiographs and limb length scintigraphs. RESULTS: In all cases, early closure of the lateral part of the distal tibial physis, upward migration of the lateral malleolus, unstable valgus deformity and external tibial torsion of the ankle joint developed during a mean follow-up of 11 years (range, 5 to 21 years). The mean valgus deformity and external tibial torsion of the ankle at the final follow-up were 15.2degrees (range, 5degrees to 35degrees) and 10degrees (range, 5degrees to 12degrees), respectively. In 12 cases (12/19, 63%), a supramalleolar corrective osteotomy was performed but three children had a recurrence requiring an additional supramalleolar corrective osteotomy 2-4 times. CONCLUSIONS: A valgus deformity and external tibial torsion are inevitable after acquired pseudoarthrosis of the fibula in children. Both Langenskiold supramalleolar synostosis to prevent these ankle deformities and supramalleolar corrective osteotomy to correct them in children are effective initially. However, both procedures cannot maintain the permanent ankle stability during skeletal maturity. Therefore any type of prophylactic surgery should be carried out before epiphyseal closure of the distal tibia occurs, but the possibility of a recurrence of the ankle deformities and the need for final corrective surgery after skeletal maturity should be considered.

Avances del vendaje funcional de tobillo en el deporte / Advances on ankle taping in sport

El objetivo de este artículo ha sido realizar una revisión de los estudios con vendajes funcionales preventivos de tobillo en el deporte y formular unas hipótesis de futuros trabajos en base a unos ensayos biomecánicos con plataforma de fuerzas. En relación a la biomecánica de los vendajes funcionales preventivos de tobillo en la bibliografía encontramos cuatro temas principales: el estudio del posible descenso del rendimiento, la medición de la restricción de movimiento, la fatiga del vendaje y finalmente las revisiones bibliográficas y trabajos que aportan hipótesis para posibles investigaciones. Podemos concluir que predominan estudios estáticos de las restricciones del vendaje en la amplitud articular y sin embargo hay muy pocos estudios que analicen el comportameitno del vendaje realizando movimientos de situaciones deportivas. Pese a que los beneficios de la utilización de los vendajes están demostrados, cuando su uso no es el adecuado pueden darse una serie de efectos no deseados. A menudo, la dependencia que pueden provocar en el sujeto, le llevará a que esté expuesto a una lesión en el momento en que no esté protegido. El artículo acaba analizando movimientos básicos, presentes en muchos deportes: marcha, carrera, salto, cambio de dirección y amortiguación de caída. En estos movimientos se presentan resultados de la bibliografía y de estudios piloto propios, en los que se analiza la cinética del contacto en el suelo con y sin vendaje funcional preventivo del tobillo, de cara a proponer nuevas vías de investigación, que aborden no solo la eficacia del vendaje sino también la posible disminución en la eficacia de gestos deportivos y el riesgo añadido de nuevas lesiones

The purposes of this paper were to review the research on prophylactic ankle taping in sport, and to formulate hypotheses for future researches, on the basis of biomechanical trials on a force platform. There are four main topics on prophylactic ankle taping in the literature: the study of a possible performance decrease, the measurement of the limitation in the range of motion (ROM), the fatigue of the ankle taping and finally, the reviews and researches that contribute with hypotheses for further works. Most studies have been carried out in static conditions to test the limitations in the ROM; however, there are few studies where the ankle taping response during sports tasks or specfic movements had been analysed. Although the benefit of the use ankle taping are well established, when it is misused, undesirable effects could appear. The subjects´ dependence to these orthoses could lead to an injury, when they do not wear ankle taping during the sports activity. Dinally, the review analyses basic sports movements: gait, running, changes of direction ad landings. Data of these actions are presentes, from the literature and pilot studies performed in our laboratory, where ground reaction forces with and without prophylactic ankle taping have been analysed. Further investigations should focus more in deep not only on the ankle taping effectiveness but on the decreases in the effectiveness of sports movements, and the increase in the risk of injuries

Age-dependent variations in the directional sensitivity of balance corrections and compensatory arm movements in man.

We investigated the effects of ageing on balance corrections induced by sudden stance perturbations in different directions. Effects were examined in biomechanical and electromyographic (EMG) recordings from a total of 36 healthy subjects divided equally into three age groups (20-34, 35-55 and 60-75 years old). Perturbations consisted of six combinations of support-surface roll (laterally) and pitch (forward-backward) each with 7.5 deg amplitude (2 pure pitch, and 4 roll and pitch) delivered randomly. To reduce stimulus predictability further and to investigate scaling effects, perturbations were at either 30 or 60 deg s(-1). In the legs, trunk and arms we observed age-related changes in balance corrections. The changes that appeared in the lower leg responses included smaller stretch reflexes in soleus and larger reflexes in tibialis anterior of the elderly compared with the young. For all perturbation directions, onsets of balance correcting responses in these ankle muscles were delayed by 20-30 ms and initially had smaller amplitudes (between 120-220 ms) in the elderly. This reduced early activity was compensated by increased lower leg activity after 240 ms. These EMG changes were paralleled by comparable differences in ankle torque responses, which were initially (after 160 ms) smaller in the elderly, but subsequently greater (after 280 ms). Findings in the middle-aged group were generally intermediate between the young and the elderly groups. Comparable results were obtained for the two different stimulus velocities. Stimulus-induced trunk roll, but not trunk pitch, changed dramatically with increasing age. Young subjects responded with early large roll movements of the trunk in the opposite direction to platform roll. A similarly directed but reduced amplitude of trunk roll was observed in the middle-aged. The elderly had very little initial roll modulation and also had smaller stretch reflexes in paraspinals. Balance-correcting responses (over 120-220 ms) in gluteus medius and paraspinals were equally well tuned to roll in the elderly, as in the young, but were reduced in amplitude. Onset latencies were delayed with age in gluteus medius muscles. Following the onset of trunk and hip balance corrections, trunk roll was in the same direction as support-surface motion for all age groups and resulted in overall trunk roll towards the fall side in the elderly, but not in the young. Protective arm movements also changed with age. Initial arm roll movements were largest in the young, smaller in the middle aged, and smallest in the elderly. Initial arm roll movements were in the same direction as initial trunk motion in the young and middle aged. Thus initial roll arm movements in the elderly were directed oppositely to those in the young. Initial pitch motion of the arms was similar across age groups. Subsequent arm movements were related to the amplitude of deltoid muscle responses which commenced at 100 ms in the young and 20-30 ms later in the elderly. These deltoid muscle responses preceded additional arm roll motion which left the arms directed 'downhill' (in the direction of the fall) in the elderly, but 'uphill' (to counterbalance motion of the pelvis) in the young. We conclude that increased trunk roll stiffness is a key biomechanical change with age. This interferes with early compensatory trunk movements and leads to trunk displacements in the direction of the impending fall. The reversal of protective arm movements in the elderly may reflect an adaptive strategy to cushion the fall. The uniform delay and amplitude reduction of balance-correcting responses across many segments (legs, hips and arms) suggests a neurally based alteration in processing times and response modulation with age. Interestingly, the elderly compensated for these 'early abnormalities' with enlarged later responses in the legs, but no similar adaptation was noted in the arms and trunk. These changes with age provide an insight into possible mechanisms underlying falls in the elderly.

Pediatric ankle fractures: evaluation and treatment.

Pediatric ankle fractures account for approximately 5% of pediatric fractures and 15% of physeal injuries. The biomechanical differences between mature and immature bones, as well as the differing forces applied to those bones, help explain the differences between adult and pediatric fractures. The potential complications associated with pediatric ankle fractures include those seen with adult fractures (such as posttraumatic arthritis, stiffness, and reflex sympathetic dystrophy) as well as those that result from physeal damage (including leg-length discrepancy, angular deformity, or a combination thereof). The goals of treatment are to achieve and maintain a satisfactory reduction and to avoid physeal arrest. A knowledge of common pediatric ankle fracture patterns and the pitfalls associated with their evaluation and treatment will aid the clinician in the effective management of these injuries.

Distal tibiofibular diastasis secondary to osteochondroma in a child.

An 18-month-old girl with a distal tibiofibular diastasis secondary to an osteochondroma was seen with a valgus deformity of the ankle. The patient underwent operative excision of the osteochondroma at the age of 2 years. At 13-year followup there was resolution of the diastasis, and the patient was free of symptoms. Early excision obviates the need for complex reconstructive surgery to correct ankle deformity later.

[Fibular ligament rupture during growth]. / Zur fibularen Bandruptur im Wachstumsalter.

In comparison with injuries sustained in adult life, ruptures of the fibular ligaments before growth is complete are more frequently characterized by chondral, osseous and periosteal loosening, which was seen up to the 14th year of age in about 50% of our own population of 129 patients up to the 16th year of life. The average age of patients with osseous and chondral lesions was clearly lower than that of those with periosteal injuries, which was lower than that of patients with inter-ligament ruptures. Accidents at school and during school sports classes were the most frequent cause, being involved in more than 50% of cases; of the various kinds of sport engaged in soccer was the most frequent cause, accounting for 28.8% of all cases. Manual examination of ligamentous stability compared with the opposite side by roentgenoscopy without anaesthesia has proved its worth for a definite diagnosis in fresh injuries. In all cases of evident ligamentous instability operative treatment was indicated, with subsequent immobilization with a plaster cast for 6 weeks. Stable healing of the ligament and a good functional result in all cases as well as a very low rate of complications vindicate this management. Conservative therapy, especially in the age group with normally high activity levels, is now considered correct only in exceptional cases or when operative treatment is refused.