SEPTEMBER 2008 VOLUME XXXVII NUMBER 9 pISSN:1078-4519 eISSN:1934-3418

E-PUBLISHING

149	Guest Editorial—Imaging in Developmental Dysplasia of the Hip: When Less Is More Steven L. Buckley, MD Dr. Buckley is Director of Pediatric Orthopaedics, The Orthopaedic Center, Huntsville, Alabama. Abstract not available. Am J Orthop. 2008;37(9):E149.
150	Pin-Tract Infection During Limb Lengthening Using External Fixation Valentin Antoci, MD, PhD, Craig M. Ono, MD, Valentin Antoci, Jr., PhD, and Ellen M. Raney, MD Dr. Antoci is Clinical Associate Professor, Department of Orthopaedic Surgery & Rehabilitation, Texas Tech University, Health Sciences Center, Paul L. Foster School of Medicine, El Paso, Texas; and Orthopaedic Surgeon, Deming Orthopaedic Services, Mimbres Memorial Hospital, Deming, New Mexico. We evaluated the incidence of pin-tract infection (PTI) during limb lengthening using external fixation in 88 patients and the effects of infection on final outcomes and incidence of additional procedures. The PTI rate was 96.6%. The rate of half-pin site infection was significantly (P<.05) higher in half-pin fixators (100%) than in hybrid fixators (78%). There was a significantly (P<.05) higher incidence of half-pin site infection (78%) than fine-wire site infection (33%). The rate of additional surgeries for treating PTI was higher for half-pin sites than for fine-wire sites. Three (3.4%) of the 88 cases led to chronic osteomyelitis. Careful insertion and a simple, well-defined, excellent pin-care protocol can minimize PTI. Am J Orthop. 2008;37(9):E150-E154.
155	Developmental Dysplasia of the Hip in Infants With Congenital Muscular Torticollis Keith P. Minihane, MD, John J. Grayhack, MD, Todd D. Simmons, MD, Roopa Seshadri, PhD, Robert W. Wysocki, MD, and John F. Sarwark, MD Dr. Minihane is Senior Resident, Department of Orthopaedic Surgery, Northwestern University, Chicago, Illinois. Infants with congenital muscular torticollis (CMT) are at increased risk for developmental dysplasia of the hip (DDH), which has led to increased use of diagnostic procedures. Our goal in this study was to establish indications for imaging the hips of infants presenting with CMT. We reviewed the cases of 292 patients with the diagnosis of CMT, 16 of whom were found to have DDH. Each patient with DDH had an abnormal clinical hip examination. Our study results demonstrate that, despite the association of these disorders, an infant presenting with CMT does not require routine hip imaging in light of a normal clinical hip examination. The coexistence rate for CMT and DDH requiring treatment is 4.5%, which is lower than the commonly accepted 20%. Am J Orthop. 2008;37(9):E155-E158.
159	Intraoperative Use of 3-D Fluoroscopy in the Treatment of Developmental Dislocation of the Hip in an Infant Andrew B. Wolff, MD, Matthew E. Oetgen, MD, and Peter A. DeLuca, MD Dr. Wolff is Resident, Department of Orthopaedics and Rehabilitation, Yale University School of Medicine, New Haven, Connecticut. Abstract not available. Introduction provided instead. Confirming reduction of a developmental dislocation of the hip (DDH) through a spica cast is an imaging challenge. Computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound have been advocated.1-11 Each of these modalities has its benefits and drawbacks. Ultrasound allows the hip to be visualized in the operating room but is operator-dependent and requires cutting a window in the posterolateral aspect of the cast—thereby weakening an area that is crucial in holding the reduction. MRI is useful for visualizing the hip, acetabulum, and soft-tissue structures through a spica cast, but MRI availability and cost, and the prolonged sedation required, make this modality prohibitive for routine use at many centers. CT provides excellent visualization of bony details and anatomical relationships but subjects patients to ionizing radiation. In addition, both MRI and CT require waiting for the patient to recover from general anesthesia before moving him or her from the operating room to the scanner. When the reduction is suboptimal, the patient must be returned to the operating room for repeat anesthesia and corrective action. At our institution, we have begun using a 3-dimensional (3-D) fluoroscope (Siremobil Iso-C3D; Siemens Medical Solutions, Erlangen, Germany) in the operating room to confirm reductions after application of spica casts. Similar to a conventional C-arm, this instrument is portable and can provide 2-D images useful for intraoperative arthrography. Unlike a standard fluoroscope, the 3-D fluoroscope automatically rotates 190° around an isocentric point on the patient. It obtains either 50 fluoroscopic images in 1 minute or 100 images in 2 minutes, depending on the desired level of anatomical detail. Specialized software then processes the images and reconstructs them to provide axial, coronal, and sagittal views of the anatomy. These images are of high quality and are comparable to those obtained with a CT scanner. The radiation dose for the 50- image cycle is equivalent to 20 seconds of standard fluoroscopy or approximately 0.77 mGy (77 mrad).12 The radiation dose for the 100-image cycle is equivalent to 40 seconds of standard fluoroscopy or approximately 1.57 mGy (157 mrad).12 We have found that the 50-image cycle provides adequate visualization of anatomical detail. To put the radiation dose in perspective, natural background radiation from the atmosphere is approximately 1 mrad per day. The primary benefit of this instrument in the treatment of an infant with DDH is that it allows the surgeon to assess the reduction without taking the patient off the operating table, and corrective action can be taken without the risks associated with repeat anesthesia or the cost and inconvenience of a return trip to the operating room. We present the case of an infant with DDH to illustrate the use of 3-D fluoroscopy in reduction imaging. We obtained informed consent from the patient’s family to perform the procedure and publish the case data. Am J Orthop. 2008;37(9):E159-E162.
163	Evaluation of Scrotal and Testicular Radiation Doses for Heterotopic Ossification Prophylaxis Hejal Patel, MD, Craig L. Silverman, MD, Luis Carrascosa, MD, Arthur Malkani, MD, and Catheryn M. Yashar, MD Dr. Patel is Resident in Radiation Oncology, University of Louisville, Louisville, Kentucky. The majority of patients with heterotopic ossification are males with traumatic injuries in the hip/femur region. The testes, given their proximity, are exposed to scatter radiation, which has the potential to alter sperm count and morphology. In a prospective study, patients were treated with an 800-cGy dose of radiation without direct exposure of the testes/scrotum but with a testicular shield. Thermoluminescent dosimeters were placed inside and outside the shield. Mean dose inside and outside the shield was 10.2 and 20.2 cGy, respectively (sperm abnormalities have been reported with 15 cGy). Given our study results, young males should be counseled and should be treated with a testicular shield. Am J Orthop. 2008;37(9):E):E163-E166.
167	Patellar Tendon Rupture as a Manifestation of Lyme Disease Nirav K. Pandya, MD, Miltiadis Zgonis, MD, Jaimo Ahn, MD, PhD, and Craig Israelite, MD Dr. Pandya is Resident, Department of Orthopaedic Surgery, Penn Presbyterian Medical Center, University of Pennsylvania, Philadelphia, Pennsylvania. Abstract not available. Introduction provided instead. Patellar tendon ruptures can result from overloading eccentric contraction injuries (as occur in athletic patients), chronic tendon weakening from repetitive microtrauma,1 and chronic inflammation leading to degeneration and subsequent tear.2 Ruptures that result from acute, traumatic events generally occur at the attachment near the inferior pole of the patella,3 whereas midsubstance disruptions are more common with inflammation from systemic conditions.4-6 Here we present what we believe is the first reported case of a patellar tendon rupture as an extra-articular manifestation of the late phase of Lyme disease around the knee. We informed our patient that data concerning her case would be submitted for publication, and she gave us written permission to publish this report in print and electronically. Am J Orthop. 2008;37(9):E167-E170.

453	Guest Editorial—Five Studies in Fracture Management David L. Helfet, MD Dr. Helfet, this journal’s Associate Editor for Trauma, is Director, Orthopaedic Trauma Service, Hospital for Special Surgery and New York Presbyterian Hospital, New York, New York, and Professor, Orthopaedic Surgery, Weill Cornell University Medical College, New York, New York. Abstract not available. Am J Orthop. 2008;37(9);453-454.
455	Computer-Reconstructed Radiographs Are as Good as Plain Radiographs for Assessment of Acetabular Fractures Joseph Borrelli, Jr., MD, Michael Peelle, MD, Elizabeth McFarland, MD, Bradley Evanoff, MD, and William M. Ricci, MD Dr. Borrelli is Professor and Chairman, Department of Orthopaedic Surgery, University of Texas Southwestern Medical Center, Dallas, Texas. Radiographic evaluation of acutely injured patients with a displaced acetabular fracture usually includes plain radiographs and computed tomography (CT) scans. Because of patient and technologist factors, plain radiographs can be compromised and therefore can be insufficient for assessment of the fractured acetabulum. We conducted a study to determine whether computer-reconstructed radiographs (CRRs), plain radiograph–like images created from CT data, are equivalent to traditional radiographs for assessment of acetabular fractures. Five orthopedic surgeons with various trauma experience compared 77 radiographic images from 11 retrospectively identified patients with a displaced acetabular fracture. CRRs were found to be equal to plain radiographs for fracture pattern recognition, image clarity, level of information provided, and overall reviewer satisfaction. Reviewers were confident in their ability to assess fractures using CRRs and found them more aesthetically pleasing than plain radiographs. CRRs provide information equal to that of plain radiographs for assessment of displaced acetabular fractures and have the potential to overcome the problems associated with patient factors (discomfort, body habitus, fracture pattern, presence of overlying osseous structures, bowel gas and intestinal contrast materials) and technologist factors. Am J Orthop. 2008;37(9):455-460.
462	Biomechanical Evaluation of 10 Configurations of a Small External Fixator Set Leonid I. Katolik, MD, Mark Stewart, MD, John Fernandez, MD, Allison MacLennan, MD, and Mark Cohen, MD Dr. Katolik is Assistant Professor, Department of Orthopaedic Surgery, Thomas Jefferson University School of Medicine, and Attending Surgeon, The Philadelphia Hand Center, PC, Philadelphia, Pennsylvania. The small AO (Synthes, Paoli, Pa) external fixator is a valuable tool for the treatment of distal radius fractures. The construct has many possible bar and pin configurations. However, there are no data regarding which construct is optimal with respect to strength and versatility. We tested 10 configurations to determine bending stiffness, rotation, and axial loading. Although slight variations were found between constructs for bending and rotation forces, there were marked differences between constructs during axial loading. A frame design without bar- to-bar clamps was determined stiffest. However, this configuration may be more difficult to apply and adjust in the clinical setting. Although an “ideal” construct applicable to all fracture types does not exist, knowledge of the strengths of various configurations may allow for optimization of fixator assembly to meet specific clinical needs. Am J Orthop. 2008;37(9):462-465.
466	Pullout Strength Variance Among Self-Tapping Screws Inserted to Different Depths Andrew Schoenfeld, MD, Gregory Vrabec, MD, FRCS(C), Suneel Battula, PhD, Ann Salvator, MS, and Glen Njus, PhD Dr. Schoenfeld is Clinical Fellow at Harvard Medical School/Brigham and Women’s Hospital, Boston, Massachusetts. The cortical self-tapping screw (STS) has replaced the non-STS as an aid in fracture fixation. In a recent biomechanical investigation, Berkowitz and colleagues found that STS pullout strength increased with insertion depth up to 1 mm past the far cortex only. In the present study, we wanted to apply a standardized protocol of assessing pullout strength to STSs of different compositions and manufacturers while eliminating the sample-size and block- variance issues that affected the previous investigation. Ninety STSs were randomly divided into 5 groups, each representing a different insertion depth. Peak force was determined with trials ending in screw pullout or failure. A statistically significant difference in pullout strength was identified with insertion depths up to 1 mm past the far cortex. No block variance was detected. These results support the recommendation that STSs be inserted only 1 mm past the far cortex in healthy cortical bone. Am J Orthop. 2008;37(9):466-469.
470	Venous Thromboembolism Clinically Detected After Hip Fracture Surgery With Prophylaxis in a Clinical Practice Setting Phillip Comp, MD, Laura E. Happe, PharmD, MPH, Matt Sarnes, PharmD, and Eileen Farrelly, MPH Dr. Comp is Professor of Medicine, Hematology/Oncology Section, University of Oklahoma Health Sciences Center, Veterans Administration Medical Center, Oklahoma City, Oklahoma. Clinical trials have shown differences in efficacy among anticoagulants used for venous thromboembolism (VTE) prophylaxis after hip fracture surgery, but the applicability of their results is limited by constraints of the clinical trial setting. We conducted this retrospective cohort study to assess VTE after hip fracture surgery in patients who received prophylaxis with dalteparin, enoxaparin, fondaparinux, or unfractionated heparin in a hospital setting. After adjustments were made for demographic differences, risk for VTE was significantly higher for dalteparin (odds ratio [OR], 1.4; 95% confidence interval [CI], 0.99-1.92), enoxaparin (OR, 1.4; 95% CI, 1.05-1.86), and unfractionated heparin (OR, 1.9; 95% CI, 1.39-2.58) compared with fondaparinux. These findings confirm the results of clinical trials in a real-world setting. Am J Orthop. 2008;37(9):470-475.
475	Stress Fractures and Stress Reactions of the Diaphyseal Femur in Collegiate Athletes: An Analysis of 25 Cases Scott J. Koenig, MD, Alison P. Toth, MD, and Joseph A. Bosco, MD Dr. Koenig is Resident Physician, Department of Orthopaedic Surgery, Boston University Medical Center, Boston, Massachusetts. In this review of prospectively collected data, representing the largest series of its kind, we identified 25 stress injuries of the diaphyseal femur in 20 athletes at an NCAA (National Collegiate Athletic Association) Division I university. All 20 patients successfully completed rehabilitation and returned to activity without limitations. Seventeen of these patients (representing 22 injuries) were female, and all 5 patients who sustained 2 stress injuries were female. The higher proportion of injured females in this study, and the histories of menstrual irregularities and disordered eating, raised the concern that the female athlete triad may be a factor. It is important to consider the diagnosis of stress injuries of the diaphyseal femur when evaluating thigh pain in running athletes, especially females, as early diagnosis and treatment lead to excellent outcomes and full return to activity. Magnetic resonance imaging should be considered the gold standard in the diagnostic evaluation of these injuries. Further, as stress fractures may be the first presentation of the female athlete triad, it is also important for orthopedic surgeons to identify the presence of risk factors that may predispose athletes to recurrent stress injuries and other health problems. Am J Orthop. 2008;37(9):476-480.

back to top