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Biomedical subjects

Robert M Kay

Publications and source records attributed to Robert M Kay.

At least 19 recordsLinked to original sources
PubMed2006

The contributions of anterior and posterior tibialis dysfunction to varus foot deformity in patients with cerebral palsy.

BACKGROUND: According to traditional teaching, the posterior tibialis is the main cause of varus foot deformity in patients with cerebral palsy. However, the relative frequency of anterior and posterior tibialis dysfunction has only been reported with use of dynamic electromyography in relatively small series of patients, with contrasting results. The purpose of the current study was to determine the relative prevalence of posterior and anterior tibialis dysfunction with use of gait analysis in a large group of patients with cerebral palsy and varus foot deformity. METHODS: The muscular contributors to varus foot deformity in seventy-eight patients (eighty-eight feet) who had cerebral palsy were evaluated with use of computerized motion analysis and dynamic electromyography. Data also were examined to identify any relationships between the timing of varus during gait and the contributing muscle. RESULTS: The muscular contributor to varus deformity was the anterior tibialis in thirty feet, the posterior tibialis in twenty-nine feet, both the anterior tibialis and the posterior tibialis in twenty-seven feet, and another contributor in two feet. Seventy feet had varus deformity during both stance phase and swing phase. Of these seventy feet, twenty-five exhibited dysfunction of the anterior tibialis, twenty exhibited dysfunction of the posterior tibialis, and twenty-three exhibited dysfunction of both muscles. Therefore, the timing of varus was not predictive of the contributing muscle or muscles. CONCLUSIONS: The current study demonstrated a higher prevalence of anterior tibialis dysfunction, both alone and in combination with posterior tibialis dysfunction, as a contributor to pes varus in patients with pes varus and cerebral palsy than had been reported previously. Dynamic electromyography provides clinically useful information for the assessment of such patients.

Adolescent↗
PubMed2006

Causes of intoeing gait in children with cerebral palsy.

BACKGROUND: Intoeing is a frequent gait problem in children with cerebral palsy. It is essential to determine the cause(s) of intoeing when surgical intervention is being planned. The purpose of this study was to evaluate the prevalence of various causes of intoeing in children with cerebral palsy and to determine whether the causes differ between children with bilateral and those with unilateral involvement. METHODS: The cause of intoeing gait was examined retrospectively, with use of gait analysis, in 412 children with cerebral palsy (587 involved sides). The causes were evaluated separately for the children with bilateral involvement (diplegia or quadriplegia) and those with hemiplegia. RESULTS: Overall, the most common causes of intoeing were internal hip rotation (322 of 587 sides) and internal tibial torsion (296 of 587 sides). Pes varus contributed to intoeing of thirty-five of the eighty-two involved limbs of the patients with hemiplegia and of forty-two of the 505 limbs of the patients with diplegia or quadriplegia. Multiple causes of intoeing were noted in 215 of the 587 involved limbs, including 176 of the 505 limbs of the patients with bilateral involvement and thirty-nine of the eighty-two involved limbs of the patients with hemiplegia. The most common causes of intoeing in the subjects with bilateral involvement were internal hip rotation (288 of 505), internal tibial torsion (261 of 505), and internal pelvic rotation (ninety-two of 505). The most common causes in the hemiplegic children were internal tibial torsion (thirty-five of eighty-two), pes varus (thirty-five of eighty-two), internal hip rotation (thirty-four of eighty-two), and metatarsus adductus (twenty of eighty-two). CONCLUSIONS: More than one-third of children with cerebral palsy have multiple causes of intoeing. Pes varus commonly contributes to intoeing by children with hemiplegic cerebral palsy but rarely contributes to intoeing by those with diplegia or quadriplegia. These findings should be carefully considered prior to surgical correction of the intoeing gait of these patients.

Adolescent↗
PubMed2005

Production of human monoclonal antibody in eggs of chimeric chickens.

The tubular gland of the chicken oviduct is an attractive system for protein expression as large quantities of proteins are deposited in the egg, the production of eggs is easily scalable and good manufacturing practices for therapeutics from eggs have been established. Here we examined the ability of upstream and downstream DNA sequences of ovalbumin, a protein produced exclusively in very high quantities in chicken egg white, to drive tissue-specific expression of human mAb in chicken eggs. To accommodate these large regulatory regions, we established and transfected lines of chicken embryonic stem (cES) cells and formed chimeras that express mAb from cES cell-derived tubular gland cells. Eggs from high-grade chimeras contained up to 3 mg of mAb that possesses enhanced antibody-dependent cellular cytotoxicity (ADCC), nonantigenic glycosylation, acceptable half-life, excellent antigen recognition and good rates of internalization.

Animals↗
PubMed2005

How closely do surgeons follow gait analysis recommendations and why?

Gait laboratory recommendations for surgery were compared with actual surgeries performed in 30 consecutive patients. The agreement between the procedures performed and those recommended by the gait laboratory averaged 93.2+/-13.4% overall and 86.0+/-18.3% excluding patients referred by the gait laboratory physician. For 23 patients (77%), the recommended surgeries exactly matched the surgeries ultimately performed. In the other patients, seven procedures that had not been recommended were performed, and seven procedures that had been recommended were not performed. Explanations for the differences included preoperative clinical or radiographic evaluation, intraoperative assessment, changes in function between gait analysis and surgery, and patient/family request.

Adolescent↗
PubMed2005

The effect of surgical delay on acute infection following 554 open fractures in children.

BACKGROUND: Traditional recommendations hold that open fractures in both children and adults require urgent surgical debridement for a number of reasons, including the preservation of soft-tissue viability and vascular status as well as the prevention of infection. Following the widespread use of early administration of antibiotics, a number of single-institution studies challenged the belief that urgent surgical debridement decreases the risk of acute infection. METHODS: We performed a retrospective, multicenter study of open fractures that had been treated at six tertiary pediatric medical centers between 1989 and 2000. The standard protocol at each medical center was for all children to be given intravenous antibiotics upon arrival in the emergency department. The medical records of all children with open fractures were reviewed to identify the location of the fracture, the interval between the injury and the time of surgery, the Gustilo and Anderson classification, and the occurrence of acute infection. RESULTS: The analysis included 554 open fractures in 536 consecutive patients who were eighteen years of age or younger. The overall infection rate was 3% (sixteen of 554). The infection rate was 3% (twelve of 344) for fractures that had been treated within six hours after the injury, compared with 2% (four of 210) for those that had been treated at least seven hours after the injury; this difference was not significant (p = 0.43). When the fractures were separated according to the Gustilo and Anderson classification system, there were no significant differences in the infection rate between those that had been treated within six hours after the injury and those that had been treated at least seven hours after the injury. Specifically, these infection rates were 2% (three of 173) and 2% (two of 129), respectively, for type-I fractures, 3% (three of 110) and 0% (zero of forty-four), respectively, for type-II fractures, and 10% (six of sixty-one) and 2% (two of thirty-seven), respectively, for type-III fractures (p > 0.05 for all three comparisons). CONCLUSIONS: In the present retrospective, multicenter study of children with Gustilo and Anderson type-I, II, and III open fractures, the rates of acute infection were similar regardless of whether surgery was performed within six hours after the injury or at least seven hours after the injury. The findings of the present study suggest that, in children who receive early antibiotic therapy following an open fracture, surgical debridement within six hours after the injury offers little benefit over debridement within twenty-four hours after the injury with regard to the prevention of acute infection.

Acute Disease↗
PubMed2004

Gastrocnemius and soleus lengths in cerebral palsy equinus gait--differences between children with and without static contracture and effects of gastrocnemius recession.

Equinus gait is one of the most common abnormalities in children with cerebral palsy. Although it is generally assumed that the calf muscles are abnormally short in equinus gait, no studies have been done to confirm that the muscles are short and that this shortness contributes to the equinus. This study used musculoskeletal modeling combined with computerized gait analysis to examine medial gastrocnemius (MGAS), lateral gastrocnemius (LGAS), and soleus (SOL) musculotendinous lengths during equinus gait in children with cerebral palsy. All three muscles were abnormally short during equinus gait whether or not the children had equinus contractures (P < or = 0.005). Children with static contractures had shorter maximum static MGAS and LGAS lengths than children with dynamic equinus (P < or = 0.002). The children with static contractures had ratios of peak dynamic length to maximum static length close to 1.0 for MGAS and LGAS (1.005 +/- 0.015) but lower ratios for SOL (0.984 +/- 0.024). For the children with static contracture, these ratios did not change significantly after gastrocnemius recession (P > or = 0.14) because both static and dynamic lengths increased postoperatively (P < or = 0.04). These results support the current clinical understanding of the role of calf "tightness" in equinus gait, including the appropriateness and effectiveness of gastrocnemius recession for children with equinus contracture.

Ankle Joint↗
PubMed2004

Outcome of gastrocnemius recession and tendo-achilles lengthening in ambulatory children with cerebral palsy.

Preoperative and postoperative gait analysis data were retrospectively studied for 54 children with cerebral palsy who had undergone either gastrocnemius recession (GR) or tendo-achilles lengthening (TAL) as part of multi-level surgery. Decision-making between GR and TAL was based on the Silfverskiöld test. The TAL group had greater equinus preoperatively than the GR group. Both groups showed significant improvement in static and dynamic dorsiflexion and in outcome measured by a modified Physician Rating Scale (PRS) postoperatively. Calf spasticity decreased and push-off power increased after GR. Both GR and TAL are effective in appropriately selected patients. However, a potential for over- and under-correction with both GR and TAL was demonstrated.

Achilles Tendon↗
PubMed2004

Lateral-entry pin fixation in the management of supracondylar fractures in children.

BACKGROUND: There has been controversy regarding the optimal pin configuration in the management of supracondylar humeral fractures in children. A crossed-pin configuration may be mechanically more stable than lateral pins in torsional loading, but it is associated with a risk of iatrogenic injury to the ulnar nerve. Previous clinical studies have suggested that lateral pins provide sufficient fixation of unstable supracondylar fractures. However, these studies were retrospective and subject to patient-selection bias. METHODS: A displaced supracondylar humeral fracture was fixed with only lateral-entry pins in 124 consecutively managed children. Medical records and radiographs were reviewed to identify any complications, including loss of fracture reduction, iatrogenic ulnar nerve injury, infection, loss of motion of the elbow, and the need for additional surgery. In addition, eight displaced supracondylar humeral fractures that had been reduced and fixed with lateral pins at other institutions and had lost reduction were analyzed to determine the causes of the failures. RESULTS: Sixty-nine children had a type-2 fracture, according to Wilkins's modification of Gartland's classification system; forty-three (62%) of those fractures were stabilized with two pins and twenty-six (38%), with three pins. Fifty-five children had a type-3 fracture; nineteen (35%) of those fractures were stabilized with two pins and thirty-six (65%), with three pins. A comparison of perioperative and final radiographs showed no loss of reduction of any fracture. There was also no clinically evident cubitus varus, hyperextension, or loss of motion. There were no iatrogenic nerve palsies, and no patient required additional surgery. One patient had a pin-track infection. Our analysis of the eight clinical and radiographic failures of lateral pin fixation that were not part of the consecutive series showed that the loss of fixation was due to fundamental technical errors. CONCLUSIONS: In this large, consecutive series without selection bias, the use of lateral-entry pins alone was effective for even the most unstable supracondylar humeral fractures. There were no iatrogenic ulnar nerve injuries, and no reduction was lost. The important technical points for fixation with lateral-entry pins are (1) maximize separation of the pins at the fracture site, (2) engage the medial and lateral columns proximal to the fracture, (3) engage sufficient bone in both the proximal segment and the distal fragment, and (4) maintain a low threshold for use of a third lateral-entry pin if there is concern about fracture stability or the location of the first two pins.

Adolescent↗
PubMed2004

Botulinum toxin as an adjunct to serial casting treatment in children with cerebral palsy.

BACKGROUND: Although botulinum toxin A is frequently used to augment serial casting in the treatment of soft-tissue contractures in children with cerebral palsy, its effectiveness for this purpose has not been evaluated. The purpose of the present study was to determine whether botulinum toxin A injection increases the efficacy of serial casting. METHODS: A prospective, randomized trial was undertaken to compare serial casting only with serial casting combined with botulinum toxin A (Botox) injection for the treatment of ankle equinus contractures in twenty-three children with cerebral palsy. Range-of-motion testing, spasticity assessment, and computerized gait analysis were performed as long as twelve months after treatment. RESULTS: There was no difference between the groups with regard to the duration of casting required to correct the equinus contracture. Both groups maintained a significant improvement in passive ankle dorsiflexion throughout the follow-up period, although the group managed with casting and Botox had a significant loss of dorsiflexion when the values at six, nine, and twelve months were compared with the value at three months. Peak dorsiflexion during the stance and swing phases was significantly improved in both groups at three months but only in the group managed with casting alone at twelve months. Plantar flexor spasticity was significantly decreased at three months in both groups, but it was significantly decreased at six, nine, and twelve months only in the group managed with casting alone. Spasticity was significantly greater in the group managed with casting and Botox than it was in the group managed with casting only at six, nine, and twelve months. CONCLUSIONS: The present study demonstrates the efficacy of serial casting in the treatment of equinus contractures in children with cerebral palsy who are able to walk. Contrary to our hypothesis, the addition of botulinum toxin A to a serial casting regimen led to earlier recurrence of spasticity, contracture, and equinus during gait. The results of the present study suggest that botulinum toxin combined with serial casting for the treatment of fixed contractures will lead to a recurrence of plantar flexor spasticity and equinus contracture by six months in this patient population. While previous research has indicated that the injection of botulinum toxin A is superior to casting for the treatment of dynamic equinus, the present study suggests that serial casting alone is preferable for the treatment of fixed equinus contractures in children with cerebral palsy.

Adolescent↗
PubMed2003

The surgical management of pediatric fractures of the lower extremity.

The majority of pediatric fractures of the lower extremity can and should be treated with closed reduction, immobilization, and close follow-up. However, there is an ongoing debate in the orthopaedic community regarding the exact role of surgical management in the treatment of pediatric fractures. In the past 2 decades, surgical management of certain fractures provided markedly better results than closed management. In certain cases, such as those requiring anatomic realignment of the physis or articular surface, there are clear indications for surgical management. Increasingly, however, surgical management is being used to maintain optimal alignment, to allow early motion, or to facilitate mobilization of children with a lower extremity fracture. For many types of fractures, both nonsurgical and surgical methods have yielded good results and have vocal advocates. Certain technical advances, such as the use of flexible intramedullary fixation and bioreabsorbable implants, have further increased enthusiasm for surgical management of pediatric fractures of the lower extremity.

Adolescent↗
PubMed2002

Growth arrest of the distal radius following a metaphyseal fracture: case report and review of the literature.

We report a 12-year-old girl who developed growth arrest of the distal radius physis 9 months after sustaining a complete fracture of the distal radial and ulnar metaphysis with no involvement of the physis evident at time of injury. The girl sustained a fracture of the metaphysis of her right distal radius and ulna after a fall. Anterior-posterior, lateral and oblique radiographs at injury, and during subsequent healing show no evidence of the fracture involving the physis. She was treated with closed reduction and casting for 6 weeks and healed uneventfully. She returned 4 month later concerned about distal ulnar prominence. Radiographs revealed a loss of radial tilt and with suspicion of a physeal bar. Magnetic resonance imaging confirmed a physeal bar located in the dorsal radial region. A literature search of the Medline database was used to obtain prior case reports for review purpose. The patient underwent an epiphysiodesis of the distal radius and ulna along with an opening wedge osteotomy and bone grafting of the distal radius to restore radial height and inclination. She healed without complication and with restoration of the normal relationship of the distal radius and ulna. A review of the literature reveals five reported case of distal radial metaphyseal fractures not invloving the physis leading to growth arrest. By comparison, there are 31 reported cases of distal radius physeal arrest following fractures involving the physis. The physician should be aware that common distal radius metaphyseal fractures may rarely lead to growth arrest.

Child↗
PubMedDate not supplied

Predictive value of the Duncan-Ely test in distal rectus femoris transfer.

Fifty-six patients who underwent 94 distal rectus femoris transfers and pre- and postoperative gait analyses were retrospectively reviewed. The patients were divided into three groups based on pre- and postoperative Duncan-Ely tests. Group A (34 limbs) had positive tests both before and after surgery. Group B (46 limbs) had positive tests before surgery and negative tests after surgery. Group C (13 limbs) had negative tests both before and after surgery. One limb had a negative test before surgery and a positive test after surgery and was not included in any group. Knee arc increased significantly in both groups with positive preoperative Duncan-Ely tests (groups A and B), but not in the group with negative preoperative tests (group C). The timing of peak knee flexion in swing improved in all groups, but the change was smaller and not statistically significant in the group with negative preoperative tests (group C). The findings of the current study indicate that the Duncan-Ely test may be a helpful predictor of outcome in children for whom distal rectus femoris transfer is being considered. Caution should be exercised when patients have weak quadriceps and a negative Duncan-Ely test before surgery, particularly when concurrent calf lengthening procedures are planned.

Adolescent↗
PubMedDate not supplied

Effect of surgical delay on perioperative complications and need for open reduction in supracondylar humerus fractures in children.

This retrospective study examined whether a delay of greater than 12 hours is associated with an increased risk of perioperative complications in the operative treatment of supracondylar humerus fractures in children. Of 150 consecutive children with supracondylar fractures, 50 underwent surgery in less than 12 hours and 100 underwent surgery greater than 12 hours after injury. There was no significant difference between groups in rate of open reduction (P = 0.55), pin tract infection (P = 1.0), iatrogenic nerve injury (P = 1.0), vascular complication (P = 0.33), or compartment syndrome (P = 1.0), including when Gartland type III fractures were analyzed independently. There was no iatrogenic nerve injury, no compartment syndrome, and one pin tract infection in 150 patients. The study confirms previous retrospective studies finding no significant difference in perioperative complications or rate of open reduction in children undergoing early versus delayed surgical treatment of supracondylar humerus fractures.

Child↗
PubMedDate not supplied

Changes in pelvic rotation after soft tissue and bony surgery in ambulatory children with cerebral palsy.

The authors performed a retrospective review of pelvic rotation in 59 children with cerebral palsy who underwent lower extremity surgery and pre- and postoperative gait analysis. Two groups were studied: a femoral derotation osteotomy (FDRO) group and a soft tissue surgery only (no FDRO) group. Both groups exhibited abnormal pelvic rotation preoperatively and normalization of this abnormal pelvic rotation postoperatively. Though the mean change in pelvic rotation was small (3.3 degrees +/- 6.0 degrees), some patients demonstrated postoperative changes as large as 21 degrees. Variability in pelvic rotation was greater in the no FDRO group than in the FDRO group. Improvement in pelvic rotation occurred both in children with unilateral (hemiplegic) involvement and in those with bilateral (diplegic or quadriplegic) involvement. Surgeons planning lower extremity surgery in children with cerebral palsy should expect improvement in abnormal pelvic rotation in both hemiplegic and diplegic patients, whether or not bony surgery is planned in addition to soft tissue surgery.

Cerebral Palsy↗