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Biomedical subjects

Samir Mehta

Publications and source records attributed to Samir Mehta.

At least 19 recordsLinked to original sources
PubMed2007

Posterior cervical arthrodesis for subacute odontoid fracture in a patient with osteopetrosis: case report.

STUDY DESIGN: A case of subacute odontoid fracture in a patient with osteopetrosis treated with posterior cervical arthrodesis using transarticular screws and interspinous wiring. OBJECTIVES: To report the first successful cervical arthrodesis in a patient with osteopetrosis and to highlight the potential perioperative pitfalls in this rare surgical population. SUMMARY OF BACKGROUND DATA: Osteopetrosis is a group of skeletal dysplasias characterized by osteoclast dysfunction, impaired bone resorption, and poor bone remodeling. Unique challenges associated with surgical fixation in osteopetrotic bone include a high incidence of nonunion, intraoperative fractures, intraoperative instrumentation failure, infection, and prosthesis loosening. We report the case of a patient with a subacute odontoid fracture treated successfully with posterior cervical arthrodesis using transarticular screws and interspinous wiring. METHODS: The surgical technique, intraoperative pitfalls, and 2-year follow-up data are reported. RESULTS: The patient underwent a successful posterior cervical arthrodesis using transarticular screws and interspinous wiring with autogenous iliac crest graft. At 2 years, a stable fixation was achieved with only mild postoperative limitation in neck range of motion. CONCLUSIONS: Cervical fractures and instability that require surgery in patients with osteopetrosis represent a unique challenge to the orthopedic spine surgeon. Despite the increased potential for perioperative instrumentation complications, nonunion, and infection, posterior cervical arthrodesis can be achieved and should be considered in the treatment armamentarium for this potentially catastrophic injury.

Adult↗
PubMed2006

Prospective trial of laparoscopic nissen fundoplication versus proton pump inhibitor therapy for gastroesophageal reflux disease: Seven-year follow-up.

Laparoscopic Nissen fundoplication and proton pump inhibitor (PPI) therapy are both established treatments for gastroesophageal reflux disease (GERD). We have performed a prospective randomized study comparing these two treatments and now have long-term follow-up data. Between July 1997 and August 2001, 183 patients in Norwich took part in a randomized controlled trial comparing laparoscopic Nissen fundoplication and PPI therapy for the treatment of GERD. In October 2005, patients were followed up and asked to complete a reflux symptom questionnaire. Ninety-one patients were randomized to have surgery and 92 to have optimized PPI therapy. After 12 months, those who had been randomized to PPI were offered the opportunity to have surgery. Fifty-four patients went on to have antireflux surgery; the remaining 38 did not. In all three groups, there was a significant improvement in symptom score after the initial 12 months (P < 0.01; Mann-Whitney U test). However, those who later had surgery despite having had optimal PPI treatment beforehand experienced further symptomatic improvement (P < 0.01) at long-term follow-up (median 6.9 years, range, 4.3-8.3). Both optimal PPI therapy and laparoscopic Nissen fundoplication are effective treatments for GERD. However, surgery offers additional benefit for those who have only partial symptomatic relief whilst on PPIs.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed2006

The effect of intraperitoneal local anesthesia in laparoscopic cholecystectomy: a systematic review and meta-analysis.

Intraperitoneal administration of local anesthesia is often used to improve pain relief after laparoscopic cholecystectomy. We have conducted a meta-analysis to establish the efficacy of this technique in reducing early postoperative abdominal pain. A systematic literature search revealed 24 randomized, controlled trials assessing intraperitoneal local anesthetic use in laparoscopic cholecystectomy that met inclusion criteria. Of these, 16 studies reported sufficient data to allow pooled quantitative analysis. The weighted mean differences (WMD) in visual analog pain score at 4 h after surgery were pooled using a random effects model. Overall, the use of intraperitoneal local anesthesia resulted in a significantly reduced pain score at 4 h (WMD, -9 mm; 95% confidence interval [CI], -13 to -5). Subgroup analysis suggested that the effect was greater when the local anesthetic was given at the start of the operation (WMD, -13 mm; 95% CI, -19 to -7) compared with instillation at the end (WMD, -6 mm; 95% CI, -10 to -2). No adverse events related to local anesthetic toxicity were reported. We conclude that the use of intraperitoneal local anesthesia is safe, and it results in a statistically significant reduction in early postoperative abdominal pain.

Abdominal Pain↗
PubMed2006

Sacral fractures.

Sacral fractures most commonly occur after pelvic ring injuries but occasionally in isolation. Although the true incidence of sacral fractures is unknown, an estimated 30% are identified late. Sequelae of inappropriately treated or untreated sacral fractures include persistent pain, decreased mobility, and neurologic compromise. Because these fractures often result from high-energy trauma, concomitant injuries should be suspected. A thorough physical examination, including a detailed neurologic assessment and radiographic evaluation, is necessary to determine treatment. Computed tomography of the pelvis/sacrum can provide significant information about fracture pattern. Surgical intervention, often as a combination of neural decompression and stabilization, is indicated in patients with neurologic deficits, significant soft-tissue compromise, and lumbosacral instability. Patient satisfaction with surgical intervention has not been definitively documented, although neurologic improvement with timely intervention has been noted.

Fracture Fixation↗
PubMed2005

Nucleus implant parameters significantly change the compressive stiffness of the human lumbar intervertebral disc.

Nucleus replacement by a synthetic material is a recent trend for treatment of lower back pain. Hydrogel nucleus implants were prepared with variations in implant modulus, height, and diameter Human lumbar intervertebral discs (IVDs) were tested in compression for intact, denucleated, and implanted condition. Implantation of nucleus implants with different material and geometric parameters into a denucleated IVD significantly altered the IVD compressive stiffness. Variations in the nucleus implant parameters significantly change the compressive stiffness of the human lumbar IVD. Implant geometrical variations were more effective than those of implant modulus variations in the range examined.

Compressive Strength↗
PubMed2004

Supraspinatus tendon organizational and mechanical properties in a chronic rotator cuff tear animal model.

Rotator cuff tears of the shoulder are a common cause of pain and disability. The successful repair of rotator cuff tendon tears depends on the time from onset of injury to the time of surgical repair. However, the effect of time from injury to repair remains poorly understood. A rat model was used to investigate the supraspinatus tendon organizational and mechanical property changes that occur with time post-injury to understand the natural injury response in the absence of repair. It was hypothesized that increased time post-injury would result in increased detrimental changes to tendon organizational and mechanical properties. Tendons were detached at the insertion on the humerus without repair and the quantitative organizational and mechanical properties were analyzed at 1, 2, 4, 8, and 16 weeks post-detachment. Tendon detachment resulted in a dramatic decrease in mechanical properties initially followed by a progressive increase with time. The quantitative collagen fiber orientation results provided corroborating support to the mechanical property data. Based on similarities in histology and mechanical properties to rotator cuff tears in humans, the animal model presented here is promising for future investigations of the tendon's natural injury response in the absence of repair.

Animals↗
PubMed2004

Effect of bracing on paralytic scoliosis secondary to spinal cord injury.

BACKGROUND: The incidence of paralytic scoliosis subsequent to acquired spinal cord injury (SCI) has been reported to range from 46% to 97% in patients injured before the adolescent growth spurt. OBJECTIVE: The purpose of this report is to review early bracing of children with SCI as a means of preventing or delaying surgical fusion. METHODS: Patient records from January 1996 to December 2001 from the Shriners Hospitals for Children-Philadelphia were retrospectively reviewed; 123 patients met the inclusion criteria of cervical or thoracic SCI prior to skeletal maturity. Patients were divided into 5 groups based on their radiographic curve severity at presentation, and then they were subdivided into a group that was managed with prophylactic bracing and a group that was not braced. End-points included completion of bracing regimen, surgery, or cessation of growth. RESULTS: Forty-two patients presented with a curve < 10 degrees, 29 of whom were braced, and 13 who were not. Of the braced group, 13 (45%) went on to surgery, whereas 10 (77%) of the nonbraced group had surgical correction (P = 0.03). Of the patients who were initially braced, the average time to surgery was 8.5 years, whereas that for the nonbraced group was 4.2 years (P = 0.002). A similar trend was seen in the patients who presented with an initial curve between 11 degrees and 20 degrees (P < 0.001). There was no significant difference between time to surgery for the braced and nonbraced patient groups at higher (> 20 degrees) initial curve presentations. CONCLUSION: Bracing of children with SCI before significant curve formation (< 20 degrees) delays the time to surgical correction of the deformity as it progresses. At smaller curves (< 10 degrees), bracing may even prevent the need for surgery. As curve size increases (> or = 20 degrees), bracing seems to play a limited role, because it does not seem to prevent surgery or delay time to surgical correction.

Age of Onset↗
PubMed2004

The tension required at repair to reappose the supraspinatus tendon to bone rapidly increases after injury.

Rotator cuff tears occur frequently and can cause significant pain and reduced shoulder function. A high percentage of patients are satisfied after surgical repair of rotator cuff tears, but a smaller percentage of patients with chronic tears continue to have pain and poor shoulder function. This may be partly attributable to an increase in the repair tension, the force required at repair to reappose the tendon to its original insertion site on the humerus. Increases in repair tension have been shown to occur for long-standing ruptures of the supraspinatus tendon, but the precise tension at various times after injury are unknown. Therefore, the objective of the current study was to determine the repair tension at various times after a rotator cuff tear. This was achieved by creating a full-thickness supraspinatus tendon tear in a rat model and measuring the mechanical characteristics of the musculotendinous unit at 0, 2, 4, 9, and 16 weeks after injury. The repair tension rapidly increased initially after injury followed by a progressive, but less dramatic, increase with additional time. These findings suggest that rotator cuff tears should be repaired early in the clinical setting. Future studies will investigate the effect of repair tension on tendon to bone healing after repair.

Animals↗
PubMed2004

Langerhans cell histiocytosis of the spine in children. Long-term follow-up.

BACKGROUND: Langerhans cell histiocytosis causes destructive lesions in a child's spine. Few large, long-term studies have evaluated the clinical and radiographic presentation, natural history, outcomes of modern treatment approaches, and maintenance of normal spinal growth and stability after the diagnosis of this disease in children. METHODS: Twenty-six children with biopsy-proven Langerhans cell histiocytosis involving the spine were treated at our institution between 1970 and 2003. They had a total of forty-four involved vertebrae (twenty cervical, fourteen thoracic, and ten lumbar). Vertebral body collapse was measured on radiographs and classified as grade I (0% to 50% collapse) or grade II (51% to 100% collapse) and subclassified as A (symmetric collapse) or B (asymmetric collapse). Lesions of the posterior elements of the spine were classified as grade III. Twenty-three children were followed for two years or more (mean, 9.4 years), and the analyses of treatment and long-term outcomes were performed in that group of patients. RESULTS: There was a predominance of lesions in the cervical spine (p </= 0.02). Sixteen (62%) of the twenty-six children were found to have multifocal skeletal disease. Cervical and lumbar lesions were more commonly associated with multilevel spinal disease. The extent of the initial collapse seen radiographically was grade IA for twenty vertebrae, IB for three, IIA for ten, IIB for nine, and III for two. Grade-I lesions were more likely to be associated with symmetric collapse than were grade-II lesions. Spinal deformity developed in four children, and two later required spinal fusion. No relationship was observed between the grade of the initial collapse and the subsequent development of spinal deformity. Despite heterogeneous treatment, all patients were alive and well with resolution of all presenting signs and symptoms and no evidence of active disease at the time of the most recent follow-up. CONCLUSIONS: We found a particularly high prevalence of lesions in the cervical spine and a high prevalence of multiple skeletal lesions. In contrast to the classic finding of vertebra plana, we found that more severe lesions often led to asymmetric collapse; yet, asymmetric collapse was not found to be associated with the development of subsequent spinal deformity. The natural history of these lesions in the spine in the absence of systemic disease or spinal deformity is such that aggressive surgical management is usually not indicated; only follow-up is necessary to monitor recovery and spinal balance.

Adolescent↗
PubMed2004

The relationship between required medical school instruction in musculoskeletal medicine and application rates to orthopaedic surgery residency programs.

BACKGROUND: Orthopaedic residency programs lack gender and race diversity. This study examines the hypothesis that exposure to a required course in musculoskeletal medicine in medical school is associated with a higher rate of application to orthopaedic surgery residency programs by underrepresented groups. METHODS: All 122 medical schools in the United States were surveyed in 2001 to determine whether they required dedicated course work in musculoskeletal medicine, defined as a preclinical module or clinical clerkship in orthopaedic surgery, rheumatology, or physiatry. Data from the Electronic Residency Application Service were obtained for the class of 2002. From these two sources, the rate of applications from students to orthopaedic surgery residency programs was calculated as a function of exposure to a required course in musculoskeletal medicine. Subgroup analysis was further carried out for women and for African Americans, Latinos, and Native Americans. RESULTS: In 2002, there were 16,294 graduates of American medical schools, of whom approximately 55% had mandatory instruction in musculoskeletal medicine. The rate of application to orthopaedic surgery residency programs was 5.7% among the students with required instruction compared with a rate of 5.1% for students without such required instruction. The rate of application for female students was 2.0% for those who had required courses and 1.1% for the female students who had not had the required courses. The rate of application for minority students in schools with required courses was 8.2% compared with a rate of 6.1% for those students without such exposure. CONCLUSIONS: Required instruction in musculoskeletal medicine was associated with a 12% higher rate of application to orthopaedic surgery residency programs among all students (5.7% of those who received required instruction compared with 5.1% of those who did not). The relative difference was more pronounced among women (a 75% difference in the rate of application) and minorities (a 35% difference in the rate of application). This study suggests that required instruction in musculoskeletal medicine can help to promote diversity in orthopaedic surgery residency programs.

Cultural Diversity↗
PubMed2003

An atypical presentation of Langerhans cell histiocytosis of the cervical spine in a child.

STUDY DESIGN: A case report of a child with Langerhans cell histiocytosis of the posterior elements of the cervical spine treated conservatively and with long-term follow-up is described. OBJECTIVES: To describe the unique diagnostic and therapeutic challenges of treating Langerhans cell histiocytosis located atypically in the posterior elements of the spine. SUMMARY OF BACKGROUND DATA: Langerhans cell histiocytosis involves the spine in approximately 20% of children with the disease. In nearly 95% of cases, spinal Langerhans cell histiocytosis results in destruction of the vertebral body, sparing the posterior elements. Confident diagnosis of vertebral body lesions is often made based on plain radiographs and MRI; however, the diagnosis of posterior element disease is not so straight forward. The natural history of isolated skeletal Langerhans cell histiocytosis is benign in most cases. METHODS: The clinical and radiographic presentation of a child with Langerhans cell histiocytosis involving the posterior elements of C3 is described. A soft tissue mass was observed on magnetic resonance imaging; however, a biopsy confirmed the benign diagnosis of Langerhans cell histiocytosis. No further surgical treatment was needed, and conservative therapy incorporating a short course of cervical bracing and low-grade chemotherapy was begun. RESULTS: Within a year, reconstitution of the posterior elements of C3 was apparent on radiographs. By 9 years after diagnosis, the child had near full reconstitution of the posterior elements of C3 and resolution of anterior pseudosubluxation of C3 on C4 that was present at diagnosis. Although diagnosis of Langerhans cell histiocytosis was made difficult by an atypical location in the posterior elements of the spine, after biopsy, conservative treatment led to excellent vertebral reconstitution. CONCLUSIONS: Isolated involvement of the posterior spine in Langerhans cell histiocytosis has not been described in detail previously. The reported case illustrates the diagnostic challenges of isolated posterior spine Langerhans cell histiocytosis. Despite an unusual presentation, posterior spine Langerhans cell histiocytosis should be treated conservatively in a similar manner to anterior lesions.

Cervical Vertebrae↗
PubMed2003

Etiologic and pathogenetic factors for rotator cuff tendinopathy.

Etiologic and pathogenetic factors for rotator cuff tendinopathy, although often compartmentalized to intrinsic or extrinsic causes, have multifactorial roots. The development of animal models for the study of rotator cuff disease has increased the fund of knowledge regarding this disease and has paved the way for future studies. Further multidisciplinary studies at molecular, biomechanical, and clinical levels should be undertaken to enhance the understanding of this common disorder. Ultimately, the goals of improved care, increased comprehension, and prevention of rotator cuff tendinopathy are attainable.

Animals↗
PubMed2002

Effect of permeation enhancer pretreatment on the iontophoresis of luteinizing hormone releasing hormone (LHRH) through human epidermal membrane (HEM).

A 2 x 2 factorial design was performed to determine the effect of a permeation enhancer (oleic acid/propylene glycol), iontophoresis (2 V), and the combination of the two treatments on the permeation enhancement of a model peptide, LHRH (luteinizing hormone releasing hormone), through human epidermal membrane (HEM). In parallel studies, TEAB (tetraethylammonium bromide, a small ionic solute) and sucrose (an electroosmotic flow marker) were also investigated. Structural changes in the HEM were monitored via conductance measurements, differential scanning calorimetry (DSC), and infrared (IR) spectroscopy experiments. LHRH enhancement due to enhancer in combination with iontophoresis (I + E; 29.5 times passive permeability, P), was greater than during iontophoresis alone (I; 14.3) and enhancer treatment alone (E; 3.5). I + E had an additive effect of I and E, indicating the mechanisms of action of the individual enhancement strategies were likely to be located at different sites in the skin. Also, no synergistic enhancement was observed with I + E for either TEAB or sucrose. For TEAB, permeability enhancement due to I (approximately 1400) was much higher than that due to E (14.9), and no additive effect could be detected. For sucrose, E had no effect on either passive or iontophoretic permeability, eliminating the possibility that electroosmosis could explain increases in LHRH permeability. Evidence of synergy between E and I was found, with conductance measurements indicating that I + E synergistically increased the membrane permeability to conducting ions (Na+ and Cl-). It appears these pathways were not available for transport for the solutes used in the current study. DSC and IR investigations showed significant changes in stratum corneum lipid structure following E treatment but not following I. These findings probably arise from the localized action of iontophoresis compared with the bulk action of enhancer. In summary, increased LHRH delivery through HEM in vitro can be achieved using an enhancer in combination with iontophoresis.

Calorimetry, Differential Scanning↗
PubMed2002

A comparison of stemmed and unstemmed components in revision knee arthroplasty.

The purpose of the current study was to compare retrospectively the results of the Insall-Burstein constrained condylar knee implant used with and without intramedullary stems in 207 revision knee arthroplasties with the Insall-Burstein constrained condylar knee implant. One hundred sixty-one knees had either one or two stems placed. One hundred eight femoral stems and 76 tibial stems were placed. Fifty-five knees had no femoral or tibial stem. The average knee scores ranged from 52 preoperatively to 86 postoperatively. The average range of motion postoperatively was 4 degrees (range, 0 degrees -10 degrees ) to 106 degrees (range, 94 degrees -118 degrees ) in this group. The average postoperative knee score was 86 in the unstemmed group and 85 in the stemmed group with no difference in average range of motion. There were four (3%) cases of tibial loosening and two (2%) cases of femoral loosening in the unstemmed group. There were two (2%) cases of tibial loosening and two (2%) cases of femoral loosening at an average followup of 4.2 years (range, 2-6.2 years). Despite the higher constraint inherently designed in an Insall-Burstein constrained condylar knee component, the current study did not show a significantly higher loosening in implants without stems compared with implants used with stems. Therefore, the use of a semiconstrained component does not alone constitute a requirement for the use of an intramedullary stem.

Adult↗