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Dive into the research topics where Virak Tan is active.

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Featured researches published by Virak Tan.


Clinical Orthopaedics and Related Research | 2001

Anatomy, histologic features, and vascularity of the adult acetabular labrum.

Richard M. Seldes; Virak Tan; Jennifer Hunt; Mark A. Katz; Raz Winiarsky; Robert H. Fitzgerald

Acetabular labrum tears have been implicated as a cause of hip pain in adult patients. Few studies describe the anatomy, histologic features, and microvasculature of the acetabular labrum and labral tears. Fifty-five embalmed and 12 fresh-frozen adult hips with a mean age of 78 years (range, 61–98 years) were studied. Of these, 96% (53 of 55) of the hips had labral tears, with 74% of the tears located in the anterosuperior quadrant. Histologically, the fibrocartilaginous labrum was contiguous with the acetabular articular cartilage through a 1-to 2-mm zone of transition. A consistent projection of bone extends from the bony acetabulum into the substance of the labrum that is attached via a zone of calcified cartilage with a well-defined tidemark. Two distinct types of tears of the labrum were identified histologically. The first consisted of a detachment of the fibrocartilaginous labrum from the articular hyaline cartilage at the transition zone. The second consisted of one or more cleavage planes of variable depth within the substance of the labrum. Both types of labral tears were associated with increased microvessel formation seen within the tear. The acetabular labrum tear appears to be an acquired condition that is highly prevalent in aging adult hips. Labral tears occur early in the arthritic process of the hip and may be one of the causes of degenerative hip disease.


International Journal of Neuroscience | 1997

Goal setting as a predictor of return to work in a population of chronic musculoskeletal pain patients

Virak Tan; Martin D. Cheatle; Suzanne Mackin; Paul J. Moberg; John L. Esterhai

To assess prospectively the association between personal attributes, vocational factors, and the return to work outcome for patients with chronic, nonmalignant, musculoskeletal pain, we assessed return to work (RTW) motivation though an open-format listing of treatment goals in 59 chronic pain patients admitted to a university pain management program. Patients were then followed (average of 17.9 months) in the posttreatment period to determine whether they had in fact returned to employment. Results indicated that a number of pretreatment factors predicted future employment status in this patient population. Age, marital status, education and decreased length of unemployment were predictive of RTW outcome. Overall, RTW goal was the single best predictor of return to work outcome. In contrast, increased number of premorbid jobs, compensation status, patients race and sex were not predictive. The present study suggests that the assessment of an individuals motivation as defined by goal-setting may be a key factor in predicting a favorable outcome in this typically refractory population of patients.


Journal of Hand Surgery (European Volume) | 2010

Effects of Nonsteroidal Anti-Inflammatory Drugs on Flexor Tendon Adhesion

Virak Tan; Ali Nourbakhsh; John T. Capo; Jessica A. Cottrell; Marcus Meyenhofer; J. Patrick O'Connor

PURPOSE Besides its anti-inflammatory effects, nonsteroidal anti-inflammatory drug therapy may affect tendon healing and the development of peritendinous adhesions. The purpose of this study was to compare the effect of nonselective (ibuprofen) and COX-2 selective (rofecoxib) nonsteroidal anti-inflammatory drugs on the adhesion formation after tendon repair. METHODS We assigned 67 rabbits to one of 3 (placebo, ibuprofen, or rofecoxib) groups. The deep flexor tendon was transected, followed by a primary repair. Dosing of the medication began the day after surgery and continued for 27 days. The animals were immobilized in a cast for the first 14 days. Postoperatively, tendon adhesion formation was assessed histologically by calculating the total adhesion in serial axial tendon sections at 3 and 6 weeks and by range of motion measurements at 6 and 12 weeks. We measured range of motion by fixing the metacarpal, applying increasing weight to the free end of the flexor digitorum profundus, and measuring the flexion angle between the metacarpal and the proximal phalanx. Comparison was performed between the treatment groups, as well as to the unoperated forepaws. RESULTS Based on histology, we found no difference between the treatment groups when determining the percentage of adhesion between the flexor tendon and its sheath. Control unoperated forepaws had a significantly greater range of metacarpophalangeal joint flexion than the surgically repaired groups. At 12 weeks, range of motion in the ibuprofen group was significantly better than the placebo (p=.009) and rofecoxib (p=.009) groups. CONCLUSIONS Ibuprofen has a more important effect in limiting adhesion formation compared with rofecoxib after flexor tendon repair. Because ibuprofen inhibits both COX-1 and COX-2, whereas rofecoxib only inhibits COX-2, ibuprofen therapy appears to offer a greater beneficial effect on tendon repair by reducing formation of adhesions.


Journal of Hand Surgery (European Volume) | 2008

Foreign-Body Reaction to the Artelon CMC Joint Spacer: Case Report

Edward W. Choung; Virak Tan

The Artelon CMC spacer (Small Bone Innovations, Inc., Morrisville, PA) is a relatively new device that was developed for the treatment of basal joint arthritis. It is composed of a biodegradable polycaprolactone-based polyurethane urea that acts to resurface the distal part of the trapezium and stabilize the trapeziometacarpal joint by augmenting the joint capsule. This is a case report of a foreign-body tissue reaction to the Artelon CMC spacer.


Journal of Orthopaedic Trauma | 2000

Major pediatric hand trauma associated with fireworks.

Richard S. Moore; Virak Tan; John P. Dormans; David J. Bozentka

OBJECTIVES To characterize the injury pattern and economic impact of major pediatric hand trauma secondary to fireworks. DESIGN Retrospective. SETTING Pediatric Level I trauma center. INTERVENTION N/A MAIN OUTCOME MEASUREMENTS: Fractures, amputations, soft tissue defects, length of hospitalization, number and type of procedures performed were obtained from charts, radiographs, and operative reports. Hospital charges were obtained from the billing office. PATIENTS/PARTICIPANTS Records of patients with a diagnosis of fireworks-related injuries admitted over a period of ten years were reviewed. Twenty-two patients were identified to have sustained twenty-two hand injuries. The group consisted of nineteen boys and three girls, with an average age of 9.3 years (range, 4 to 17 years). RESULTS There were thirty-one fractures, nineteen amputations, and one dislocation. The nineteen amputations occurred in nine hands. Local skin graft or flap coverage was required in six hands acutely, and delayed soft tissue procedures were performed on four hands. Four hands had digital neurovascular injuries; two required microsurgical repairs at the time of injury, and two were irreparable. Resource use included: average hospital stay of 4.3 days (range, 0 to 20), average number of trips to the operating room, 1.2 (range, 0 to 3), and average hospital charges of


Acta Orthopaedica | 2009

A comparison of the effects of ibuprofen and rofecoxib on rabbit fibula osteotomy healing

J. Patrick O'Connor; John T. Capo; Virak Tan; Jessica A. Cottrell; Michaele B Manigrasso; Nicholas Bontempo; J. Russell Parsons

11,582 (range,


Journal of Orthopaedic Trauma | 2000

Well-leg compartment pressures during hemilithotomy position for fracture fixation.

Virak Tan; Matthew D. Pepe; David L. Glaser; Richard M. Seldes; R. Bruce Heppenstall; John L. Esterhai

1,035 to


Journal of Hand Surgery (European Volume) | 2012

Comparative Analysis of Intramedullary Nail Fixation Versus Casting for Treatment of Distal Radius Fractures

Virak Tan; Walter W. Bratchenko; Ali Nourbakhsh; John T. Capo

39,489). CONCLUSIONS This study illustrates the severity of pediatric hand injuries associated with fireworks and the significant burden placed on medical resources in treating these injuries. Efforts toward public education and legislative reforms may help to prevent these unnecessary injuries.


Journal of Trauma-injury Infection and Critical Care | 2009

Acute Forearm Compartment Syndrome Secondary to Local Arterial Injury After Penetrating Trauma

Robert J. Morin; Kenneth G. Swan; Virak Tan

Background and purpose Non-steroidal anti-inflammatory drugs (NSAIDs) inhibit cyclooxygenase (COX) activity, which is the rate-limiting enzyme in the synthesis of prostaglandins. Previous studies have indicated that NSAID therapy, and in particular NSAIDs that specifically target the inflammatory cyclooxygenase (COX-2), impair bone healing. We compared the effects of ibuprofen and rofecoxib on fibula osteotomy healing in rabbits to determine whether nominal, continuous inhibition of COX-2 with rofecoxib would differentially affect fracture healing more than cyclical inhibition of COX-2 using ibuprofen, which inhibits COX-1 and COX-2 and has a short half-life in vivo. Methods Bilateral fibula osteotomies were done in 67 skeletally mature male New Zealand white rabbits. The rabbits were treated with placebo, rofecoxib (12.5 mg once a day), or ibuprofen (50 mg 3 times a day) for 28 days after surgery. Plasma ibuprofen levels were measured by HPLC analysis. Bone healing was assessed by histomorphometry at 3 and 6 weeks after osteotomy, and at 6 and 12 weeks by torsional mechanical testing. Results Plasma ibuprofen levels peaked and declined between successive doses. Fracture callus morphology was abnormal in the rofecoxib-treated rabbits and torsional mechanical testing showed that fracture healing was impaired. Ibuprofen treatment caused persistence of cartilage within the fracture callus and reduced peak torque at 6 weeks after osteotomy as compared to the fibulas from the placebo-treated rabbits. In the specimens allowed to progress to possible healing, non-union was seen in 5 of the 26 fibulas from the rofecoxib-treated animals as compared to 1 of 24 in the placebo group and 1 of 30 in the ibuprofen treatment group. Interpretation Continuous COX-2 inhibition as modeled by rofecoxib treatment appears to be more deleterious to fracture repair than cyclical cyclooxygenase inhibition as modeled by ibuprofen treatment. Ibuprofen treatment appeared to delay bone healing based upon the persistence of cartilage within the fracture callus and diminished shear modulus. Despite the ibuprofen-induced delay, rofecoxib treatment produced worse fracture (osteotomy) healing than ibuprofen treatment.


Hand Clinics | 2008

Carpometacarpal Joint Disease: Addressing the Metacarpophalangeal Joint Deformity

Edward J. Armbruster; Virak Tan

OBJECTIVE To evaluate the relationship between the well-leg compartment pressures and time during hemilithotomy position for fracture fixation. DESIGN Prospective. SETTING Level 1 trauma center. PATIENTS/PARTICIPANTS Ten patients who underwent intramedullary nailing of a fractured femur in the hemilithotomy position (with a well-leg holder). INTERVENTION Continuous pressure monitoring was achieved with in-dwelling slit catheters inserted into the calf compartments of the well leg. Baseline measurements were obtained in the supine position. After the leg was placed in the hemilithotomy position, compartment pressures were monitored throughout surgery. MAIN OUTCOME MEASUREMENTS Calf compartment pressures at baseline, during hemilithotomy position, and post-hemilithotomy were compared. The association between body mass index and compartment pressure was analyzed. RESULTS A consistent pattern was observed between compartment pressures and time. The curve was that of a step function in which the pressure increased as soon as the leg was placed in the well-leg holder and remained elevated until the leg was taken down. The pressure jumped from a baseline of 9.2 to 27.3 millimeters of mercury (mm Hg) (p<0.0001). While in the hemilithotomy position, the leg pressure trended slightly upward. Once the leg was taken down, the pressure immediately returned to a near-baseline level of 8.1 mm Hg (p<0.0001). A significant correlation was also found between the body mass index and leg pressure (R2 = 0.713; F = 0.002). CONCLUSIONS The use of the well-leg holder to maintain hemilithotomy position increases the calf compartment pressures dramatically and significantly. Therefore, we recommend avoiding this position for fracture fixation in at-risk patients.

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Aaron Daluiski

Hospital for Special Surgery

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Matthew D. Pepe

University of Pennsylvania

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John P. Dormans

Children's Hospital of Philadelphia

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Andrew J. Weiland

Hospital for Special Surgery

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Lawson A. Copley

Children's Medical Center of Dallas

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Richard M. Seldes

Hospital for Special Surgery

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