Biomedical subjects

J R Davids

Publications and source records attributed to J R Davids.

36 records · Page 2Linked to original sources

PubMedDate not supplied

A dynamic biomechanical analysis of the etiology of adolescent tibia vara.

Biomechanical overload of the proximal tibial physis due to static varus alignment and excessive body weight has been implicated in the etiology of infantile tibia vara. Whether a similar pathophysiologic process applies to adolescent tibia vara is controversial, with poor consensus concerning the nature and significance of static knee alignment early in the course of the disease. This study examines the hypothesis that dynamic gait deviations to compensate for increased thigh girth associated with obesity (fat-thigh gait) could result in increased loading of the medial compartment of the knee during the gait cycle. Three-dimensional motion analysis was used to identify the kinematic/kinetic profile associated with fat-thigh gait. Gait deviations identified were dynamic stance-limb knee varus, increased stance-limb knee rotation, and swing-limb circumduction. Pathologic compressive forces were generated in an anthropometric model by using recorded fat-thigh gait deviations and clinically appropriate excessive body weight. This analysis supports the clinical observation that underlying static varus malalignment of the knee is not a prerequisite for the development of adolescent tibia vara and illustrates the significance of dynamic gait deviations when considering knee-joint loading.

Adolescent↗

PubMedDate not supplied

Objective assessment of dyskinesia in children with cerebral palsy.

The clinical classification of children with cerebral palsy is limited by multiple factors. Distinguishing between spasticity and dyskinesia is critical, because the outcome after standard orthopaedic and neurosurgical interventions is less predictable in children with cerebral palsy who have a significant dyskinetic component. This study applied computer-based analysis of gait to assess objectively the presence of significant dyskinesia in children with cerebral palsy. Three-dimensional gait analysis was performed on 18 normal children, 17 children with principally spastic cerebral palsy, and 23 children with significantly dyskinetic cerebral palsy. Children were assigned to the spastic or dyskinetic groups prospectively, based on clinical analysis by an experienced physician and physical therapist. The children with dyskinesia were found to have a significantly wider, and more variable normalized dynamic base of support, a smaller step profile (step length divided by step width), and a greater and more variable maximal lateral acceleration than the spastic and normal groups (mixed model analysis of variance, p = 0.0001). A predictive model of dyskinesia, (developed by logistic regression analysis), using these gait parameters, exhibited excellent sensitivity, correctly classifying 20 (87%) of 23 children as dyskinetic. This study shows that children with dyskinetic cerebral palsy have distinct gait parameters and that objective assessment of dyskinesia in children with cerebral palsy is possible with computer-based analysis of gait.

Adolescent↗

PubMedDate not supplied

Voluntary (normal) versus obligatory (cerebral palsy) toe-walking in children: a kinematic, kinetic, and electromyographic analysis.

Surgical management of toe-walking gait in children with cerebral palsy currently favors simultaneous, multilevel soft-tissue and bony interventions. Formulation of such a surgical plan is based on our ability to determine which of the gait deviations present are primary and which are secondary or compensatory. To evaluate this issue further, 32 normal children, walking normally and voluntarily toe-walking, were compared to 15 children with cerebral palsy walking in an obligatory toe-walking gait pattern. Computer-based analysis of gait was performed for each child, including time-distance, kinematic, kinetic, and electromyographic analyses. Significant deviations common to both normal and cerebral palsy toe-walking groups were determined to be due, at least in part, to the biomechanical constraints associated with a toe-walking gait pattern. Deviations unique to the cerebral palsy group were thought to represent primary gait deviations related to the underlying injury to the central nervous system. This study identifies the need to develop more sophisticated techniques of data collection and analysis and supports the inclusion of more varied and demanding functional activities for distinguishing between primary and secondary gait deviations in children with cerebral palsy.

Adolescent↗

PubMedDate not supplied

Surgical management of hallux valgus deformity in children with cerebral palsy.

Twenty-six cases of hallux valgus deformity, in 16 children with cerebral palsy, were managed with great toe metatarsophalangeal (MTP) arthrodesis. Mean age at the time of surgery was 16 years (range, 10 years and 11 months to 21 years and 11 months), and mean follow-up was 4 years and 11 months (range, 2 years and 1 month to 10 years). Significant improvement in the hallux valgus angle (preoperative, 36.3 degrees; follow-up, 9.6 degrees; p < 0.05), the intermetatarsal angle (preoperative, 12.3 degrees; follow-up, 8.4 degrees; p < 0.05), and lateral metatarsophalangeal angle (preoperative, 4.8 degrees; follow-up, 25.8 degrees; p < 0.05), were achieved and maintained after MTP arthrodesis. Functional outcome was documented by significant improvement in the modified American Orthopaedic Foot and Ankle Society Hallux Metatarsophalangeal-Interphalangeal Scale (preoperative mean score, 46.2; follow-up mean score, 90.9; p < 0.05). Patient/ parent/caregiver satisfaction (as determined by a questionnaire), with improvements in cosmesis, footwear, hygiene, activity, and pain were high, ranging from 81% to 100%. Hallux valgus deformity in children with cerebral palsy is best managed by MTP arthrodesis, in conjunction with other surgical procedures that address segmental foot malalignment and dynamic gait deviations.

Adolescent↗

PubMedDate not supplied

Management of lower extremity riding lawn mower injuries in children.

Eight children are injured by riding lawn mowers every day. The child, usually a bystander or passenger on the mower, can sustain life-threatening and limb-threatening injuries. Multidisciplinary care must be available to manage the numerous issues presented by the unique circumstance of a child with a severe injury in the acute and chronic settings. Whether the limb is salvaged or amputated, the ultimate goal is optimal functional outcome for the patient. We have developed a team approach to address these injuries from their onset until patient maturity, maximizing our ability to achieve this goal.

Amputation, Surgical↗

PubMedDate not supplied

Angular deformity of the lower extremity in children with renal osteodystrophy.

We have treated 15 children with end-stage renal disease (ESRD), renal osteodystrophy, and genu valgum in the last 22 years. In a retrospective review, we determined that periods of metabolic instability, best characterized as an alkaline phosphatase of 500 U for at least 10 months, were associated with progression of deformity. Histomorphometric bone biopsy provided information that proved essential for effective evaluation and treatment in this group. Complications of corrective osteotomy were related to perioperative metabolic instability. A surgical treatment protocol is described, emphasizing preoperative assessment by histomorphometric bone biopsy and multimodal medical management to maintain metabolic stability perioperatively.

Adolescent↗

PubMedDate not supplied

Metatarsal epiphyseal bracket: treatment by central physiolysis.

Longitudinal epiphyseal bracket (LEB) is a rare ossification anomaly in which an epiphysis brackets the diaphysis of a phalanx, metacarpal, or metatarsal. This abnormal epiphysis tethers longitudinal growth, resulting in a shortened and oval-shaped bone. Four patients with five LEBs were treated by central physiolysis and followed for a mean of 6 years. The patients had significant hallux varus deformity. Three patients had duplicated great toes, and two had tibia hemimelia significant enough to require epiphysiodesis as they neared adolescence. Resection of the LEB allowed the proximal and distal epiphysis to resume untethered growth. Silastic or methyl methacrylate was placed over the resected physis to prevent bony rebridging. The associated hallux varus deformity was corrected by capsulorrhaphy and K-wire fixation. In all patients, the metatarsal resumed longitudinal growth and correction of the hallux varus was maintained.

Child↗

PubMedDate not supplied

Significance of the confusion test in cerebral palsy.

The confusion test examines ankle dorsiflexion in patients with cerebral palsy. Orthopedists have related this test to swing-phase activity of the tibialis anterior, and have used it as a prerequisite for tendon transfer. To determine the validity of this assumption, ankle dorsiflexion was tested in 47 normal children. Forty-seven percent had a positive, unresisted confusion test, and 97% had a positive, resisted confusion test. Twenty-three patients with cerebral palsy who had a positive confusion test underwent gait analysis. Tibialis anterior electromyographs showed wide variability. Sagittal-plane ankle-movement curves revealed five patterns. Thirty-three percent of the patients showed abnormal swing-phase dorsiflexion, and 61% had abnormal swing-phase plantar-flexion. We conclude that the confusion test evaluates a normal, patterned response, and is positive in most children with cerebral palsy. Although a positive confusion test shows that active ankle dorsiflexion is possible, it is not predictive of swing-phase ankle kinematics.

Ankle↗

PubMedDate not supplied

Lateral condylar fracture of the humerus following posttraumatic cubitus varus.

Posttraumatic cubitus varus is widely regarded as just a cosmetic deformity. Six cases of lateral condylar fracture of the humerus in children with preexisting cubitus varus due to prior elbow fracture are presented. Five occurred following malunited extension-type supracondylar fractures of the humerus; the other occurred following a lateral condylar fracture complicated by lateral overgrowth. All cases were treated by anatomic reduction (two closed, four open) and percutaneous pinning of the lateral condylar fracture. Three of the six cases subsequently underwent supracondylar osteotomy of the distal humerus to correct the underlying varus malalignment. Biomechanical analysis suggests that both the torsional moment and the shear force generated across the capitellar physis by a routine fall are increased by varus malalignment. Posttraumatic cubitus varus may predispose a child to subsequent lateral condylar fracture and should be viewed as more than just a cosmetic deformity.

Bone Nails↗

PubMedDate not supplied

Single-incision combination biopsy (muscle and nerve) in the diagnosis of neuromuscular disease in children.

The diagnosis of specific neuromuscular diseases in infants and children is often suspected clinically and confirmed histologically by muscle biopsy. In relatively few cases, the differential diagnosis includes hereditary or acquired peripheral neuropathies, and nerve biopsy is required for diagnosis. Historically, children who needed both muscle and nerve biopsies have had two separate incisions at the thigh (muscle) and ankle (nerve) to obtain the specimens. A procedure has been developed that employs a single incision on the posterior aspect of the calf, which allows for simultaneous muscle (soleus or peroneals) and nerve (sural) biopsies. A retrospective study of 22 patients who underwent single-incision combination biopsy was performed. Age at time of biopsy ranged from 2 months to 14 years. Adequate specimens for histologic analysis were obtained in all but one case. Histologic diagnoses were made in 32% of the muscle biopsies and 29% of the nerve biopsies. Mean follow-up after biopsy was 3 years 6 months. Potentially significant complications of nerve biopsy were not seen in this cohort. Single-incision combination biopsy is the preferred technique when simultaneous muscle and nerve biopsies are required. Knowledge of the location of the sural nerve in the calf is essential. This technique is relatively less invasive than separate muscle and nerve biopsies, allows for the harvest of adequate muscle and nerve specimens, is minimally morbid, and can be performed on very young infants.

Adolescent↗

PubMedDate not supplied

Ultrasonography and developmental dysplasia of the hip: a cost-benefit analysis of three delivery systems.

The role of ultrasound (US) in the diagnosis and management of infants with developmental dysplasia of the hips (DDH) is becoming widely accepted. In our community, there exist three delivery systems for US-DDH: the radiology based, the combined radiology/orthopaedic based, and the orthopaedic office based. This study reviewed the costs and benefits of each delivery system and found that once expertise had been gained and start-up costs were met, the orthopaedic office-based system was the most convenient, efficient, and cost effective for the patient/family and treating physicians. This mirrors the experience of cardiologists, obstetricians, and family practitioners, fields in which the utility of office-based ultrasonography is widely recognized and has become the standard.

Cost-Benefit Analysis↗

PubMedDate not supplied

Wrist arthrodesis in children with cerebral palsy.

Wrist arthrodesis was performed on 19 upper extremities in 18 children with cerebral palsy to correct volar flexion and ulnar deviation deformities. Mean age at the time of surgery was 15.8 years, and mean follow-up was 4.7 years. Review of medical records and radiographs and follow-up clinical examination, including standardized functional testing and a child/parent questionnaire, were performed to assess outcome in technical, functional, and satisfaction domains. Technical domain outcomes were best when arthrodesis was performed by proximal row carpectomy with plate fixation. Functional improvement, as documented by the House scale, averaged 1.8 levels, with 14 children (83.3%) showing improvement. Child/parent satisfaction with cosmetic, hygienic, and functional outcomes was high, ranging from 72 to 94%. Wrist arthrodesis, when combined with appropriate procedures for the forearm, fingers, and thumb, provided excellent technical, functional, and satisfaction domain outcomes for children with cerebral palsy, particularly those with more severe upper extremity involvement, dyskinetic type cerebral palsy, or poor motivation for rehabilitation.

Adolescent↗

PubMedDate not supplied

Radiographic evaluation of bowed legs in children.

Radiographic screening is widely used to distinguish between Blount disease (infantile tibia vara) and physiologic bowing. Thirteen children with Blount disease, evaluated before 3 years of age, with initial radiographs showing no sign of Langenskiold changes, were compared with 50 children with physiologic bowing, also evaluated before 3 years of age with similar radiographic studies. Screening test accuracy was determined retrospectively for measurement of the mechanical axis, the tibial metaphyseal-diaphyseal angle (TDMA), and the epiphyseal-metaphyseal angle (EMA). A radiographic screening method combining the TMDA and the EMA, using cutoff values of 10 degrees and 20 degrees respectively, exhibited the best combination of sensitivity, specificity, and positive predictive value, correctly identifying all cases of Blount disease and 40 of 50 cases of physiologic bowing. Our data suggest that children between 1 and 3 years of age with TMDA <10 degrees, or TMDA > or =10 degrees and EMA < or =20 degrees, are at less risk for development of Blount disease. Children with TMDA > or =10 degrees and EMA >20 degrees are at greater risk for development of Blount disease and should be followed closely.

Child, Preschool↗

PubMedDate not supplied

Early radiographic differentiation of infantile tibia vara from physiologic bowing using the femoral-tibial ratio.

SUMMARY: The authors hypothesized that the ratio of the femoral to tibial metaphyseal-diaphyseal angles (femoral-tibial ratio [FTR]) more accurately differentiates physiologic bowing from infantile tibial vara than the tibial metaphyseal-diaphyseal angle (TMDA). The purpose of this study was threefold: to determine the false-negative and false-positive error rate of the FTR and TMDA; to determine to the effect of rotation on the FTR and TMDA; and to determine the reliability of the FTR and TMDA measurements. An FTR < 1 resulted in a false-negative error rate of 10% and a false-positive error rate of 7%, whereas a TMDA > 13 degrees resulted in a false-negative error rate of 23% and a false-positive error rate of 10%. The difference between internal and external rotation was not significant for the FTR, whereas it was for the TMDA. The FTR was found to have good interobserver and intraobserver reliability (0.78 and 0.98, respectively).

Age Factors↗

PubMedDate not supplied

Subcutaneous granuloma annulare: recognition and treatment.

Subcutaneous granuloma annulare (SGA) is a benign inflammatory disorder that occurs in children. The profiles of 12 children with SGA who were diagnosed and treated at our institution were reviewed. The patients presented with a rapidly growing, painless soft-tissue mass of the extremities or scalp. Parental concerns of malignancy and lack of recognition of this condition by the physician led to excessive diagnostic testing and, on occasion, inappropriate therapy. The mean age at presentation was 3.9 years, and the mean follow-up after biopsy study was 3.4 years. The lesions were most commonly located about the elbow, knee, and scalp. While complete blood count, erythrocyte sedimentation rate, and plain radiographs were helpful in ruling out other conditions, no ancillary test was specific for this disorder. In all cases, definitive diagnosis required a biopsy sample. Excisional biopsy was diagnostic but not therapeutic, because 75% of the children had one or more recurrences of this condition at either local or distant sites. Two of the subsequent lesions resolved spontaneously, and no child within the study group has progressed to any recognized systemic illness or connective-tissue disorder.

Adolescent↗

PubMedDate not supplied

Congenital muscular torticollis: sequela of intrauterine or perinatal compartment syndrome.

The etiology of congenital muscular torticollis remains a mystery despite intensive investigation. Magnetic resonance imaging (MRI) scans of 10 infants with this condition showed signals in the sternocleidomastoid muscle similar to those observed in the forearm and leg after compartment syndrome. Cadaver dissections and injection studies defined the sternocleidomastoid muscle compartment. Injection studies and pressure measurements performed at the time of bipolar release in three patients with congenital muscular torticollis confirmed the existence of this compartment in vivo. Clinical review of 48 children with congenital muscular torticollis showed a relation between birth position and the side affected by the contracture. Because of the association of congenital muscular torticollis with other intrauterine positioning disorders, we postulate that head positioning in utero can selectively injure the sternocleidomastoid muscle, leading to development of a compartment syndrome. Congenital muscular torticollis may represent the sequela of an intrauterine or perinatal compartment syndrome.

Child, Preschool↗

PubMedDate not supplied

Surgical management of ankle valgus in children: use of a transphyseal medial malleolar screw.

Valgus deformity of the ankle in children is associated with a wide variety of clinical conditions. A retrospective review was performed of 17 children (29 involved extremities) with ankle valgus deformity who had been managed by use of a percutaneously placed, transphyseal medial malleolar screw. Median age at the time of surgery was 11 years, 2 months. Median postoperative follow-up was 2 years, 2 months. Tibiotalar axis and ankle mechanical axis were the best radiographic indicators of ankle valgus deformity. Fibular station and epiphyseal wedging were poor predictors of ankle alignment. Significant improvement in the tibiotalar axis (median, 12 degrees) was noted at follow-up, and the median rate of correction was 0.59 degree/month. Resumption of physeal growth and recurrence of deformity (rate of 0.60 degree/month) was seen when the screws were removed before skeletal maturity. The transphyseal medial malleolar screw is a minimally invasive, minimally morbid, technically simple method of reversible partial epiphysiodesis at the ankle and is an effective technique for the correction of ankle valgus deformity associated with a wide variety of clinical conditions in children.

Adolescent↗

PubMedDate not supplied

Proximal tibiofibular bifurcation synostosis for the management of longitudinal deficiency of the tibia.

Three adults with severe longitudinal deficiency of the tibia (LDT), in which an unossified proximal tibial anlage was present, who had been treated with proximal tibiofibular bifurcation synostosis (PTFBS) in early childhood, were evaluated between 20 and 31 years after the index procedure. All three were found to be functioning well as below-the-knee (BK) amputees. Mediolateral stability and anteroposterior instability of the knee were present in all cases. Instrumented motion analysis revealed diminished loading characteristics of the prosthetic limb, similar to that described for BK amputees in general. The most significant gait deviations at the knee unique to this study group were a quadriceps-avoidance gait pattern and an increased dynamic varus alignment. Instrumented muscle testing suggested that these deviations were a consequence of ligamentous instability. This study supports the concept that the presence of a proximal tibial anlage in severe LDT is indication for a surgical strategy that preserves the biological knee joint. The PTFBS maintains the integrity of the knee-extensor mechanism, the fibular collateral ligament, the tibiofemoral joint capsule, and the medial collateral ligament, enhancing the long-term stability and function of the knee joint.

Adult↗