David W. Lowenberg
Stanford University
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Featured researches published by David W. Lowenberg.
Journal of The American Academy of Orthopaedic Surgeons | 2012
Julius A. Bishop; Ariel Palanca; Michael J. Bellino; David W. Lowenberg
&NA; No standard criteria exist for diagnosing fracture nonunion, and studies suggest that assessment of fracture healing varies among orthopaedic surgeons. This variability can be problematic in both clinical and orthopaedic trauma research settings. An understanding of risk factors for nonunion and of diagnostic tests used to assess fracture healing can facilitate a systematic approach to evaluation and management. Risk factors for nonunion include medical comorbidities, age, and the characteristics of the injury. The method of fracture management also influences healing. Comprehensive evaluation includes an assessment of the patients symptoms, signs, and immune and endocrine status as well as the biologic capacity of the fracture, presence of infection, and quality of reduction and fixation. Diagnostic tests include plain radiography, CT, ultrasonography, fluoroscopy, bone scan, MRI, and several laboratory tests, including assays for bone turnover markers in the peripheral circulation. A systematic approach to evaluating fracture union can help surgeons determine the timing and nature of interventions.
Clinical Journal of The American Society of Nephrology | 2013
Sumi Sukumaran Nair; Aya Mitani; Benjamin A. Goldstein; Glenn M. Chertow; David W. Lowenberg; Wolfgang C. Winkelmayer
BACKGROUND AND OBJECTIVES Patients with ESRD experience a fivefold higher incidence of hip fracture than the age- and sex-matched general population. Despite multiple changes in the treatment of CKD mineral bone disorder, little is known about long-term trends in hip fracture incidence, treatment patterns, and outcomes in patients on dialysis. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Fourteen annual cohorts (1996-2009) of older patients (≥67 years) initiating dialysis in the United States were studied. Eligible patients had Medicare fee-for-service coverage for ≥2 years before dialysis initiation and were followed for ≤3 years for a first hip fracture. Type of treatment (internal fixation or partial or total hip replacement) was ascertained along with 30-day mortality. Cox and modified Poisson regressions were used to describe trends in study outcomes. RESULTS This study followed 409,040 patients over 607,059 person-years, during which time 17,887 hip fracture events were recorded (29.3 events/1000 person-years). Compared with patients incident for ESRD in 1996, adjusted hip fracture rates increased until the 2004 cohort (+41%) and declined thereafter. Surgical treatment included internal fixation in 56%, partial hip replacement in 29%, and total hip replacement in 2%, which remained essentially unchanged over time; 30-day mortality after hip fracture declined from 20% (1996) to 16% (2009). CONCLUSIONS Hip fracture incidence rates remain higher today than in patients reaching ESRD in 1996, despite multiple purported improvements in the management of CKD mineral bone disorder. Although recent declines in incidence and steady declines in associated short-term mortality are encouraging, hip fractures remain among the most common and consequential noncardiovascular complications of ESRD.
American Journal of Transplantation | 2014
S. Sukumaran Nair; Colin R. Lenihan; Maria E. Montez-Rath; David W. Lowenberg; Glenn M. Chertow; Wolfgang C. Winkelmayer
It is currently unknown whether any secular trends exist in the incidence and outcomes of hip fracture in kidney transplant recipients (KTR). We identified first‐time KTR (1997–2010) who had >1 year of Medicare coverage and no recorded history of hip fracture. New hip fractures were identified from corresponding diagnosis and surgical procedure codes. Outcomes studied included time to hip fracture, type of surgery received and 30‐day mortality. Of 69 740 KTR transplanted in 1997–2010, 597 experienced a hip fracture event during 155 341 person‐years of follow‐up for an incidence rate of 3.8 per 1000 person‐years. While unadjusted hip fracture incidence did not change, strong confounding by case mix was present. Using year of transplantation as a continuous variable, the hazard ratio (HR) for hip fracture in 2010 compared with 1997, adjusted for demographic, dialysis, comorbid and most transplant‐related factors, was 0.56 (95% confidence interval [CI]: 0.41–0.77). Adjusting for baseline immunosuppression modestly attenuated the HR (0.68; 95% CI: 0.47–0.99). The 30‐day mortality was 2.2 (95% CI: 1.3–3.7) per 100 events. In summary, hip fractures remain an important complication after kidney transplantation. Since 1997, case‐mix adjusted posttransplant hip fracture rates have declined substantially. Changes in immunosuppressive therapy appear to be partly responsible for these favorable findings.
Journal of Orthopaedic Trauma | 2013
David W. Lowenberg; Rudolf F. Buntic; Gregory M. Buncke; Brian M. Parrett
Objectives: To determine long-term outcomes and costs of Ilizarov bone transport and flap coverage for lower limb salvage. Design: Case series with retrospective review of outcomes with at least 6-year follow-up. Setting: Academic tertiary care medical center. Patients: Thirty-four consecutive patients with traumatic lower extremity wounds and tibial defects who were recommended amputation but instead underwent complex limb salvage from 1993 to 2005. Intervention: Flap reconstruction and Ilizarov bone transport. Main Outcome Measurements: Outcomes assessed were flap complications, infection, union, malunion, need for chronic narcotics, ambulation status, employment status, and need for reoperations. A cost analysis was performed comparing this treatment modality to amputation. Results: Thirty-four patients (mean age: 40 years) were included with 14 acute Gustilo IIIB/C defects and 20 chronic tibial defects (nonunion with osteomyelitis). Thirty-five muscle flaps were performed with 1 flap loss (2.9%). The mean tibial bone defect was 8.7 cm, mean duration of bone transport was 10.8 months, and mean follow-up was 11 years. Primary nonunion rate at the docking site was 8.8% and malunion rate was 5.9%. All patients achieved final union with no cases of recurrent osteomyelitis. No patients underwent future amputations, 29% required reoperations, 97% were ambulating without assistance, 85% were working full time, and only 5.9% required chronic narcotics. Mean lifetime cost per patient per year after limb salvage was significantly less than the published cost for amputation. Conclusions: The long-term results and costs of bone transport and flap coverage strongly support complex limb salvage in this patient population. Level of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.
Journal of The American Academy of Orthopaedic Surgeons | 2015
Rohan A. Shirwaiker; Bryan D. Springer; Mark J. Spangehl; Grant E. Garrigues; David W. Lowenberg; David N. Garras; Jung U. Yoo; Paul S. Pottinger
Orthopaedic implants improve the quality of life of patients, but the risk of postoperative surgical site infection poses formidable challenges for clinicians. Future directions need to focus on prevention and treatment of infections associated with common arthroplasty procedures, such as the hip, knee, and shoulder, and nonarthroplasty procedures, including trauma, foot and ankle, and spine. Novel prevention methods, such as nanotechnology and the introduction of antibiotic-coated implants, may aid in the prevention and early treatment of periprosthetic joint infections with goals of improved eradication rates and maintaining patient mobility and satisfaction.
Journal of The American Academy of Orthopaedic Surgeons | 2014
Michalis Panteli; Ravindra Puttaswamaiah; David W. Lowenberg; Peter V. Giannoudis
Malignant transformation as a result of chronic osteomyelitis represents a relatively rare and late complication with a declining incidence in the modern world. For most patients, the interval between the occurrence of the original bacterial infection and the transformation to malignant degeneration is several years. The diagnosis of malignant transformation in a chronic discharging sinus requires a high index of clinical suspicion. Wound biopsies should be obtained early, especially with the onset of new clinical signs such as increased pain, a foul smell, and changes in wound drainage. Squamous cell carcinoma is the most common presenting malignancy. Definitive treatment is amputation proximal to the tumor or wide local excision, combined with adjuvant chemotherapy and radiation therapy in selected patients. Early diagnosis may sometimes allow for treatment consisting of en bloc excision and limb salvage techniques. However, the most effective treatment is prevention with definitive treatment of the osteomyelitis, including adequate débridement, wide excision of the affected area, and early reconstruction.
Journal of Orthopaedic Trauma | 2016
Cory Collinge; Robert A. Hymes; Michael T. Archdeacon; Phillip Streubel; William T. Obremskey; Timothy Weber; J. Tracy Watson; David W. Lowenberg
Objectives: A few small case series have found that proximal femur fractures treated with a proximal femur locking plate (PFLP) have experienced more failures than expected. The purpose of this study was to review the clinical results of patients with acute, unstable proximal femur fractures treated with proximal femoral locking plates in a large, multicenter patient cohort. Design: This is a retrospective clinical study. Setting: The study included patients from 12 regional trauma centers and tertiary referral hospitals. Patients: One hundred eleven consecutive patients with unstable proximal femur fractures stabilized with a PFLP and having required clinical and radiographic follow-up at a minimum of 12 months after injury. Intervention: Surgical repair of an unstable proximal femur fracture with a PFLP. Main outcome measurements: Treatment failures (failure of fixation, nonunion, and malunion) and need for revision surgery. Results: Forty-six patients (41.4%) experienced a major treatment failure, including failed fixation with or without nonunion (39), surgical malalignment or malunion (18), deep infection (8), or a combination of these. Thirty-eight (34%) patients underwent secondary surgeries, including 30 for failed fixation, nonunion, or both. Treatment failure was found to occur at a significantly higher rate in patients with major comorbidities, in femurs repaired in varus malalignment, and using specific plate designs. Conclusions: Proximal femoral locking plates are associated with a high complication rate, frequently requiring revision or secondary surgeries in the treatment of unstable proximal femur fractures. Given the high complication rate with PFLPs, careful attention to reduction, use of a PFLP implant, and consideration should be given to alternative implants or fixation techniques when appropriate. Level of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.
Orthopedic Clinics of North America | 2014
David W. Lowenberg; Christopher Boone
There is a growing mass of literature to suggest that circular external fixation for high-energy tibial fractures has advantages over traditional internal fixation, with potential improved rates of union, decreased incidence of posttraumatic osteomyelitis, and decreased soft tissue problems. To further advance our understanding of the role of circular external fixation in the management of these tibial fractures, randomized controlled trials should be implemented. In addition to complication rates and radiographic outcomes, validated functional outcome tools and cost analysis of this method should be compared with open reduction with internal fixation.
Tissue Engineering Part A | 2018
Arnaud Bruyas; Seyedsina Moeinzadeh; Sungwoo Kim; David W. Lowenberg; Yunzhi Peter Yang
IMPACT STATEMENT Providing customized geometries and improved control in physical and biological properties, 3D-printed polycaprolactone/beta-tricalcium phosphate (PCL/β-TCP) composite constructs are of high interest for bone tissue engineering applications. A critical step toward the translation and clinical applications of these types of scaffolds is terminal sterilization, and E-beam irradiation might be the most relevant method because of PCL properties. Through in vitro experimental testing of both physical and biological properties, it is proven in this article that E-beam irradiation is relevant for sterilization of 3D-printed PCL/β-TCP scaffolds for bone tissue engineering applications.
Techniques in Orthopaedics | 2015
David W. Lowenberg
Introduction: Successful treatment of the mangled lower extremity can be very difficult. Management of large soft-tissue and bony defects is complex and are often treated with amputation. In carefully selected patients, limb salvage with combined muscle transfer and circular external fixation can be a safe and effective treatment. The purpose of this article is to present the surgical technique and case series. Technique: After careful patient selection, initial limb stabilization with a circular external fixator and serial debridement is carried out until a sterile wound is achieved. Often the patient is left with a large soft-tissue and bone defect. A free-tissue transfer is performed by the microvascular surgeons and the circular frame construct is completed. Bone transport through corticotomy and distraction osteogenesis is then performed to bridge the bony defect. Bone grafting at the docking site is frequently necessary after bone transport is complete. Results: A total of 127 patients were treated with free-tissue transfer and circular external fixation for limb salvage over a 22-year period. Three failures resulted in amputation. Two patients undergoing amputation failed treatment due to psychosocial issues and 1 because of medical comorbidity. There were 2 flap losses in the acute period and 1 flap with partial necrosis. Conclusions: Single-stage limb reconstruction with simultaneous muscle transfer and circular external fixation is a safe and effective method for limb salvage. It requires careful patient selection, thoughtful planning, and meticulous surgical technique.