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Dive into the research topics where Robert M. Kay is active.

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Featured researches published by Robert M. Kay.


Journal of Pediatric Orthopaedics | 2005

Prevalence of specific gait abnormalities in children with cerebral palsy: influence of cerebral palsy subtype, age, and previous surgery.

Tishya A. L. Wren; Susan A. Rethlefsen; Robert M. Kay

The authors retrospectively reviewed a series of 492 consecutive cerebral palsy patients undergoing computerized motion analysis. The prevalence of 14 specific gait abnormalities was evaluated and compared based on involvement (hemiplegia, diplegia, or quadriplegia), age, and history of previous surgery (lower extremity orthopaedic surgery or rhizotomy). Stiff knee in swing, equinus, and intoeing were all seen in more than 50% of the subjects in each of the hemiplegic, diplegic, and quadriplegic groups. Increased hip flexion and crouch were also present in more than 50% of the subjects in the diplegic and quadriplegic groups, and hip adduction occurred in more than 50% of the quadriplegic subjects. The likelihood of having stiff knee in swing, out-toeing, calcaneus deformity, and crouch increased with prior surgery. The likelihood of having rotational malalignment of the leg (internal hip rotation with out-toeing), calcaneus, out-toeing, varus and valgus foot deformities, and hip internal rotation increased with age. These findings provide important information for counseling ambulatory children with cerebral palsy and their families.


Journal of Bone and Joint Surgery, American Volume | 2001

Operative treatment of supracondylar fractures of the humerus in children. The consequences of pin placement

David L. Skaggs; Julia M. Hale; Jeffrey Bassett; Cornelia Kaminsky; Robert M. Kay; Vernon T. Tolo

Background: The commonly accepted treatment of displaced supracondylar fractures of the humerus in children is fracture reduction and percutaneous pin fixation; however, there is controversy about the optimal placement of the pins. A crossed‐pin configuration is believed to be mechanically more stable than lateral pins alone; however, the ulnar nerve can be injured with the use of a medial pin. It has not been proved that the added stability of a medial pin is clinically necessary since, in young children, pin fixation is always augmented with immobilization in a splint or cast. Methods: We retrospectively reviewed the results of reduction and Kirschner wire fixation of 345 extension-type supracondylar fractures in children. Maintenance of fracture reduction and evidence of ulnar nerve injury were evaluated in relation to pin configuration and fracture pattern. Of 141 children who had a Gartland type-2 fracture (a partially intact posterior cortex), seventy‐four were treated with lateral pins only and sixty-seven were treated with crossed pins. Of 204 children who had a Gartland type-3 (unstable) fracture, fifty‐one were treated with lateral pins only and 153 were treated with crossed pins. Results: There was no difference with regard to maintenance of fracture reduction, as seen on anteroposterior and lateral radiographs, between the crossed pins and the lateral pins. The configuration of the pins did not affect the maintenance of reduction of either the Gartland type-2 fractures or the Gartland type-3 fractures. Ulnar nerve injury was not seen in the 125 patients in whom only lateral pins were used. The use of a medial pin was associated with ulnar nerve injury in 4% (six) of 149 patients in whom the pin was applied without hyperflexion of the elbow and in 15% (eleven) of seventy‐one in whom the medial pin was applied with the elbow hyperflexed. Two years after the pinning, one of the seventeen children with ulnar nerve injury had persistent motor weakness and a sensory deficit. Conclusions: Fixation with only lateral pins is safe and effective for both Gartland type-2 and Gartland type-3 (unstable) supracondylar fractures of the humerus in children. The use of only lateral pins prevents iatrogenic injury to the ulnar nerve. On the basis of our findings, we do not recommend the routine use of crossed pins in the treatment of supracondylar fractures of the humerus in children. If a medial pin is used, the elbow should not be hyperflexed during its insertion.


Journal of Bone and Joint Surgery, American Volume | 2004

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

David L. Skaggs; Michael W. Cluck; Amir Mostofi; John M. Flynn; Robert M. Kay

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 Wilkinss modification of Gartlands 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.


Lancet Neurology | 2011

Cerebral palsy: clinical care and neurological rehabilitation

Mindy Aisen; Danielle M. Kerkovich; Joelle Mast; Sara Mulroy; Tishya A. L. Wren; Robert M. Kay; Susan A. Rethlefsen

Cerebral palsy (CP) is defined as motor impairment that limits activity, and is attributed to non-progressive disturbances during brain development in fetuses or infants. The motor disorders of CP are frequently accompanied by impaired cognition, communication, and sensory perception, behavioural abnormalities, seizure disorders, or a combination of these features. CP is thought to affect three to four individuals per 1000 of the general population. The incidence, prevalence, and most common causes of CP have varied over time because of changes in prenatal and paediatric care. Medical management of children and adults involves care from primary-care physicians with input from specialists in neurology, orthopaedics, and rehabilitation medicine. Physicians should also work in conjunction with rehabilitation therapists, educators, nurses, social care providers, and schoolteachers. The focus of rehabilitation treatment has recently shifted to neurological rehabilitation in response to increasing evidence for neuroplasticity. This approach aims to improve development and function by capitalising on the innate capacity of the brain to change and adapt throughout the patients life. As the life expectancy of individuals with CP approaches that of the general population, therapies must be developed that address the needs of adults ageing with disability.


The Journal of Urology | 2002

Clinical Behavior and A Contemporary Management Algorithm for Prepubertal Testis Tumors: A Summary of the Prepubertal Testis Tumor Registry

Jonathan H. Ross; Lisa Rybicki; Robert M. Kay

PURPOSE The Prepubertal Testis Tumor Registry was established by the Urologic Section of the American Academy of Pediatrics in 1980 to record data on a large number of prepubertal testis tumors regarding presentation, treatment and outcome to define appropriate management better. We reviewed the registry data in the context of other modern studies to elucidate the appropriate management of these rare tumors. MATERIALS AND METHODS Relevant data in the prepubertal testis tumor registry were tabulated and analyzed. RESULTS There were 395 prepubertal patients who had a primary testis tumor. Generally benign tumors accounted for 38% of cases. A significant proportion of tumors were benign regardless of patient age. alpha-Fetoprotein levels for patients with benign and malignant tumors overlapped in children younger than 6 months. Of the patients with yolk sac tumor 80% presented with stage 1 disease and overall survival was excellent. There were no metastases or deaths among the patients with teratoma. Of all patients with stromal tumors metastases developed in only 1. CONCLUSIONS We recommend initial excisional biopsy for all amenable prepubertal testis tumors, except those with an alpha-fetoprotein level that is clearly increased for patient age. Patients with benign tumors may be released from oncological followup. Patients with stage I yolk sac tumor should be monitored closely, and those with recurrent or metastatic yolk sac tumor should be treated with chemotherapy. Retroperitoneal lymph node dissection is reserved for patients with recurrent retroperitoneal masses following chemotherapy. Aggressive treatment of metastatic Sertoli cell or undifferentiated stromal tumors is warranted.


Cell | 1980

Linkage of adult α- and β-globin genes in X. laevis and gene duplication by tetraploidization

Alec J. Jeffreys; David Wood; J. Paul Simons; Robert M. Kay; Jeffrey G. Williams

Abstract We have used cloned adult X. laevis α- and β-globin cDNAs to analyze globin genes in X. laevis DNA. We detected α 1 - and β 1 -globin genes which contain intervening sequences and code for the major adult globins, plus additional diverged α 2 - and β 2 -globin genes of unknown coding potential. Unlike the case in mammals, the X. laevis α 1 - and β 1 -globin genes are closely linked and occur in the sequence 5′-α 1 -9 kb-β 1 -3′. The α 2 - and β 2 -globin genes are also linked, and analysis of globin genes in X. tropicalis suggests that this duplication of an α-β-globin gene pair in X. laevis is the result of chromosome duplication by tetraploidization. The close linkage of α- and β-globin genes in Xenopus provides evidence that vertebrate α- and β-globin genes evolved by tandem duplication of a single primordial globin gene.


Spine | 2000

Complications of posterior iliac crest bone grafting in spine surgery in children.

David L. Skaggs; Michael A. Samuelson; Julie M. Hale; Robert M. Kay; Vernon T. Tolo

Study Design. The perioperative and postoperative complications associated with harvesting posterior iliac crest bone graft in children were reviewed. A retrospective study was performed and a questionnaire interview conducted. Objectives. To determine the morbidity associated with posterior iliac crest bone graft in children. Summary of Background Data. Iliac crest bone is commonly used as a source of bone graft in spine surgery. Although there are multiple reports of complications in adults, there are no reports in children. Methods. A retrospective chart review was performed of 214 consecutive children who underwent spinal fusion with posterior iliac crest bone graft from 1990 through 1996. An interview was conducted of 87 patients with normal mental status, predominantly those with idiopathic scoliosis with a minimum of 2 years’ follow-up (mean, 55 months). Results. The review showed one (0.5%) instance of arterial injury in the sciatic notch. Two (1%) patients had infections, both of which resolved with a single irrigation and débridement. There was one documented instance of sacroiliac penetration that did not cause clinical problems. The chart review showed three (1.4%) instances of continued pain and one (0.5%) of numbness. By contrast to the few reports of pain in the chart review, responses to an interview of 87 patients showed 21 (24%) children reporting pain at the iliac crest site, with 13 (15%) reporting problems with daily activities. The self-reported pain, on a scale of 1 to 10, ranged from 1 to 10 with a mean of 4. Nonsteroidal anti-inflammatory drugs (NSAIDS) were taken by eight (9%) children for pain at the bone graft site. Five (6%) reported skin irritation, and 18 (20%) mentioned numbness surrounding the scar. Conclusion. The perioperative rate of complications in iliac crest bone grafting in children is low (2%). The complication of pain (24%) and pain that is severe enough to interfere with daily activity (15%) is significant at a mean follow-up of more than 4 years. The true extent of pain and numbness after posterior iliac crest bone grafting in children was severely underreported in the medical records and may be underrecognized.


Journal of Bone and Joint Surgery, American Volume | 2005

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

David L. Skaggs; Lauren Friend; Benjamin A. Alman; Henry G. Chambers; Michael Schmitz; Brett Leake; Robert M. Kay; John M. Flynn

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.


The Journal of Urology | 2001

LAPAROSCOPIC CROSS-TRIGONAL COHEN URETERONEOCYSTOSTOMY: NOVEL TECHNIQUE

Inderbir S. Gill; Lee E. Ponsky; Mahesh Desai; Robert M. Kay; Jonathan H. Ross

PURPOSE We describe a novel technique of laparoscopic transvesical cross-trigonal Cohen anti-reflux ureteroneocystostomy. MATERIALS AND METHODS A 10, an 11 and a 32-year-old patient with symptomatic unilateral vesicoureteral reflux underwent laparoscopic cross-trigonal ureteral reimplantation. Two 5 mm. balloon tip ports were suprapubically inserted into the bladder. Using a transurethral resectoscope with a Collins knife a 4 to 5 cm. cross-trigonal submucosal trough was created from the refluxing ureteral orifice to the contralateral side of the bladder. The refluxing ureteral orifice and intramural ureter were completely mobilized intravesically, advanced transtrigonally and secured to the detrusor muscle at the apex of the trough with 3 deep interrupted sutures. The elevated mucosal flaps of the trough were suture approximated over the ureter to create a submucosal tunnel. All suturing was performed by freehand laparoscopic technique. RESULTS Operative time was between 2.5 and 4.5 hours and blood loss was 10 to 50 cc. Adequate submucosal trough creation, ureteral extravesical mobilization and intravesical advancement, and bladder mucosal flap reapproximation were done to create a submucosal tunnel in all cases. Satisfactory transtrigonal anchoring of the neoureteral orifice to the detrusor muscle and mucosa was achieved with 3 stitches. Hospital stay was 2, 2 and 1 days in the 3 cases, and the Foley catheter remained in place for 3, 1 and 1 week, respectively. At 6 months reflux had resolved in 2 patients, while in 1 grade II reflux persisted, which was improved from grade IV preoperatively. All patients have remained infection-free without antibiotics. CONCLUSIONS Laparoscopic transvesical cross-trigonal antireflux ureteral reimplantation is technically feasible. Intravesical laparoscopic suturing is possible. Potential advantages include a decreased hospital stay, decreased narcotic requirement and better cosmesis. Further experience is necessary to refine the technical nuances and evaluate outcomes compared to the open technique.


Journal of Bone and Joint Surgery, American Volume | 2004

Botulinum Toxin as an Adjunct to Serial Casting Treatment in Children with Cerebral Palsy

Robert M. Kay; Susan A. Rethlefsen; Anna Fern-Buneo; Tishya A. L. Wren; David L. Skaggs

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.

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David L. Skaggs

Children's Hospital Los Angeles

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Susan A. Rethlefsen

Children's Hospital Los Angeles

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Tishya A. L. Wren

University of Southern California

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Vernon T. Tolo

Children's Hospital Los Angeles

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Reiko Hara

Children's Hospital Los Angeles

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Deirdre D. Ryan

Children's Hospital Los Angeles

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