Preserving plantar flexion strength after surgical treatment for contracture of the triceps surae: a computer simulation study.

Contractures of the triceps surae commonly are treated by surgical lengthening of the gastrocnemius aponeurosis or the Achilles tendon. Although these procedures generally relieve contractures, patients sometimes are left with dramatically decreased plantar flexion strength (i.e., decreased capacity to generate plantar flexion moment). The purpose of this study was to examine the trade-off between restoring range of motion and maintaining plantar flexion strength after surgical treatment for contracture of the triceps surae. A computer model representing the normal moment-generating characteristics of the triceps surae was altered to represent two conditions: isolated contracture of the gastrocnemius and contracture of both the gastrocnemius and the soleus. The effects of lengthening the gastrocnemius aponeurosis and the Achilles tendon were simulated for each condition. The simulations showed that nearly normal moment-generating characteristics could be restored when isolated gastrocnemius contracture was treated with lengthening of the gastrocnemius aponeurosis. However, when isolated gastrocnemius contracture was treated with lengthening of the Achilles tendon, the moment-generating capacity of the plantar flexors decreased greatly. This suggests that lengthening of the Achilles tendon should be avoided in persons with isolated gastrocnemius contracture. Our simulations also suggest that neither lengthening of the gastrocnemius aponeurosis nor lengthening of the Achilles tendon by itself is an effective treatment for combined contracture of the gastrocnemius and soleus. Lengthening the gastrocnemius aponeurosis did not decrease the excessive passive moment developed by the contracted soleus. Lengthening the Achilles tendon restored the normal passive range of motion but substantially decreased the active force-generating capacity of the muscles.(ABSTRACT TRUNCATED AT 250 WORDS)

Length changes of the hamstrings and adductors resulting from derotational osteotomies of the femur.

Derotational osteotomies of the femur are frequently performed to treat persons with cerebral palsy who walk with excessive internal rotation of the hip. However, whether these procedures stretch or slacken the surrounding muscles appreciably is unknown. Determination of how muscle lengths are altered by derotational osteotomies is difficult because the length changes depend not only on the osteotomy site and the degree of derotation, but also on the anteversion angle of the femur and the rotational position of the hip. We have developed a three-dimensional computer simulation of derotational osteotomies, tested by anatomical experiments, to examine how femoral anteversion, hip internal rotation, and derotation affect the lengths of the semitendinosus, semimembranosus, biceps femoris long head, adductor longus, adductor brevis, and gracilis muscles. Simulation of derotational osteotomies at the intertrochanteric, subtrochanteric, or supracondylar levels decreased the origin-to-insertion lengths of the hamstrings and gracilis in our model by less than 8 mm (1.8%). Hence, the lengths of the hamstrings and gracilis are not likely to be altered substantially by these procedures. The origin-to-insertion lengths of the adductor longus and adductor brevis decreased less than 4 mm (1.9%) with subtrochanteric correction in our model, but the length of adductor brevis increased 8 mm (6.3%) with 60 degrees of intertrochanteric derotation. These muscles are also unlikely to be affected by derotational osteotomies, unless a large degree of intertrochanteric derotation is performed.

Accessory arm--dysraphism or disparity? Case report.

The case of a 3-month-old infant with an accessory third arm is reported. The extra appendage was attached at the midcervical region and was associated with posterior cervical dysraphism and a cervical cord lipoma. Possible theories of origin are examined.

Transfer of the rectus femoris: effects of transfer site on moment arms about the knee and hip.

Decreased range of knee motion during gait is often treated by surgically releasing the rectus femoris from the patella and transferring it to one of four sites: semitendinosus, gracilis, sartorius, or the iliotibial tract. This study was conducted to determine if there are differences between these four tendon transfer sites in terms of post-surgical moment arms about the knee and hip. A graphics-based model of the lower extremity was used to simulate the origin-to-insertion path of the rectus femoris after transfer. Anatomical studies were conducted to evaluate the accuracy of the simulated tendon transfers by comparing knee flexion moment arms calculated with the computer model to moment arms measured in two anatomical specimens. The computer simulations and anatomical studies revealed substantial differences in the knee moment arms between the four sites. We found that the rectus femoris has the largest peak knee flexion moment arm (4-5 cm) after transfer to the semitendinosus. In contrast, after transfer to the iliotibial tract the rectus femoris has a slight (0-5 mm) knee extension moment arm. None of the transfers to muscle-tendon complexes on the medial side of the knee (semitendinosus, gracilis, sartorius) substantially affect the hip rotation moment arm of the rectus femoris. Transferring to the iliotibial tract increases hip internal rotation moment arm of the rectus femoris, but only when the hip is externally rotated.

Volkmann's contracture in children: aetiology and prevention.

A review was conducted of the records of fifty-five children who were admitted to the Hospital for Sick Children in Toronto between 1955 and 1975 with a diagnosis of Volkmann's contracture in fifty-eight limbs. Ten patients had been transferred to this hospital with established ischaemia after Bryant's traction for a fractured femur; all had a very poor outcome. Thirteen other cases of Volkmann's contracture affecting the superficial posterior compartment had been treated with a fixed Thomas' splint and a Bradford frame after fractures of the femoral shaft. Supracondylar fractures of the elbow resulting in Volkmann's contracture frequently had both an arterial injury and a compartment syndrome. Most of the fifty-five children reviewed here had not had early appropriate treatment. For the past twenty-one years the frequency of Volkmann's contracture has not declined in spite of many published reports on the compartment syndrome, and the hazards of supracondylar fractures and of Bryant's traction.

Assessment and management of the lower extremity in myelodysplasia.

The goal in managing the lower extremity in a child with spina bifida is to achieve a pattern of development as near normal as possible. Lower limb deformities are produced by muscle imbalance, weight-bearing, and the postural effects of gravity. At any point in time, the management of the lower extremities will depend on the child's general development. Lower limb paralysis, hydrocephalus, bladder infections, hydromyelia, and Arnold Chiari malformation, all contribute to developmental delay. A child's potential for mobility varies with the severity of the motor and sensory deficit. Surgery is done to correct deformity, provide joint stability, and improve joint mobility. The results of surgery will be compromised if the child is not neurologically stable, or if appropriate therapy and orthotic care are not available. Muscle imbalance produces the problem of deformity and instability of the hip. Deformity must be corrected if the child is to assume an upright posture. Instability is of concern only in those children with a strong quadriceps muscle. Hip surgery for instability should be limited to one procedure, which must achieve a stable concentric reduction and balance the muscle forces about the hip. The common deformities seen at the knee are recurvatum, knee flexion contractures, and genu valgum. Most knee deformities can be corrected by soft tissue procedures. Well-designed orthoses rocker sole shoes, and appropriate gait training help prevent knee deformities. The goal in managing foot deformities is to achieve a plantigrade foot with stable skin. Whenever there is a problem with sensation, concentrated pressure in one area of a deformed foot will lead to skin breakdown. Surgical procedures must completely correct deformity and restore muscle imbalance. After surgery, meticulous orthotic care is required to prevent skin breakdown and avoid loss of correction. The orthopedist has a significant role in helping a child with spina bifida to achieve a pattern of development as near normal as possible. He or she must work in concert with a team of professionals and realize that orthopedic surgery is but an incident in the habilitative program. This rather chatty narrative is based on spina bifida care experience, in Sheffield, Toronto, and Chicago.

Projected limb length inequality: selecting patients for surgery.

The selection of patients for surgery for limb length discrepancy is directed by the patient's desires and the limitations of surgery. All interventions have substantial advantages and disadvantages. In addition, the patient's ability to tolerate the intervention and the risks that accompany them are of paramount importance. The cause of the discrepancy, accompanying deformities or pathology, the patient's other medical conditions, and the predicted mature stature of the patient will all affect both the goals and viability of certain surgeries.

The pathoanatomy of congenital clubfoot.

Patients with resistant clubfeet were reviewed in their second and third decades. For comparison, normal embryological and fetal feet, untreated clubfeet, a recurrent clubfoot, and an amputated foot were dissected. In no child with a resistant clubfoot was the bone architecture normal. In untreated and recurrent clubfeet we found the lateral malleolus to be directed posteriorly, the head of the talus pointed laterally, and the navicular subluxated medially toward the medial malleolus. An operative technique to restore normal alignment of the talus in the ankle mortice, of the navicular and talus, and of the talus and os calcis is described.

Distraction osteogenesis in the hand.

Distraction osteogenesis was used to correct congenital hand deformities in 12 digits. The patients' ages at the time of distraction ranged between 2.5 and 7 years. A total of nine patients underwent lengthening of 12 bones. The average period of distraction was 31.1 +/- 17.6 days. The average length of distraction was 23.6 +/- 7.3 mm. Seventeen percent of the patients after lengthening had an angular deformity that required remodeling of the regenerate. No infections were noted. Distraction osteogenesis provides a useful tool for reliable and predictable correction of osseous defects with vascular bone in patients with congenital anomalies of the hand.

Congenital clubfoot: pathoanatomy and treatment.

A better understanding of the pathoanatomy of clubfoot, meticulous attention to detail during surgery, and orthotic maintenance of correction to facilitate remodeling should make it possible to improve the results of treatment.

Evaluation of residual clubfoot deformities using gait analysis.

Gait analysis was used to evaluate 15 patients who had previously undergone clubfoot surgery. Because six patients had had bilateral surgery, 21 feet had undergone previous clubfoot surgery. Three of the operated feet had no residual deformity. In the remaining 18 feet, the reason for referral was intoeing in 13, calcaneovalgus in three, hindfoot varus in one, and supination/adduction in one. Clinical assessment and information from the gait analysis were used to establish a treatment plan. Satisfactory treatment outcome was achieved in 13 patients, one result was unsatisfactory, and one result was undetermined.

Clubfoot analysis with three-dimensional foot models.

The purpose of this study was to develop a method of defining, in mathematical terms, the interpositional relationships of the bones of the hindfoot complex in the idiopathic clubfoot and the neurogenic clubfoot. The neurogenic clubfoot and contralateral normal-appearing foot of a stillborn infant with myelomeningocele, and the normal foot of a 10-year-old were sectioned with a cryomicrotome. Magnetic resonance images (MRIs) of the clubfoot and the normal foot of a 3-month-old boy were obtained. Using a computer program, three-dimensional foot models were generated from the digitized cryomicrotome sections and from the MRIs. The central principal axes were determined for the talus and calcaneus. The long central principal axes of the talus and calcaneus were neutrally rotated with reference to the bimalleolar axis in the idiopathic clubfoot while in the neurogenic clubfoot the long central principal axis of the talus was medially rotated 52 degrees and that of the calcaneus 10 degrees. The talocalcaneal angles defined by the long central principal axes in the superior and medial views were 0 degree and 10 degrees, respectively, in the idiopathic clubfoot, and 42 degrees and 56 degrees, respectively, in the neurogenic clubfoot.

Three-dimensional computerized reconstruction of histologic serial sections for orthopedic research.

New programs in image processing and computer graphics can now render three-dimensional images from serial tissue slices. Although neuroanatomists have used these techniques most intensively, there are exciting applications of this methodology in orthopedic research and investigative embryology. Three-dimensional reconstructions of histologic sections from newborn clubfeet have been used to determine the rotational alignment of the hindfoot bones. Similar studies could be undertaken to improve understanding of the normal and pathologic perinatal development of the spine, hip, and hand.

Limb salvage tumor surgery in children.

Limb salvage tumor surgery in children is quite popular. Low local recurrence rates and patient survival statistics prove it is a viable option for many patients. We review the major changes in medicine and paramedical fields that have allowed limb salvage to develop. We then discuss patient selection, limb salvage goals, review the surgical staging system, and examine common errors in evaluating a tumor patient. A discussion (with case examples) of various surgical options and a brief look at some current trends is then presented.

Use of animal models in musculoskeletal research.

Understanding of the human musculoskeletal system and common clinical disorders of bones, joints and soft tissues has been enhanced by the use of experimental animal models. Articles reporting on the results of these biomedical experiments frequently include conclusions that are based on the assumption that the biology of the animal model is similar to that of a human being for the disease process under investigation. The purpose of this investigation was to study the criteria and the considerations for selection of an animal model in musculoskeletal research. Selected journals from the musculoskeletal literature published between January 1991 and November 1995 were scrutinized for the use of animal models, and several criteria used in the selection of the various animal models were investigated. The selection criteria analyzed in this study included the biologic characteristics of the model, budget issues, the reproducibility of a musculoskeletal disease, and animal handling factors. A computer-assisted search of the musculoskeletal literature published from 1965 to 1995 was also performed to screen for reports comparing mammals used as animal models in terms of these selection criteria. Our findings imply that the selection of animal models in research of the musculoskeletal system is based partly on non-standardized criteria that are not necessarily based on the biology of the disease process being studied. In addition, there are limited comparative data on the selection and use of different animals for musculoskeletal research. We believe the selection of models should be more standardized based on both biological and non-biological criteria. Researchers would then be able to put in a more meaningful perspective the results of research using animal models and their clinical implications.