Browsing by Author "Tan, Timothy L."

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    Cefazolin Prophylaxis for Total Joint Arthroplasty: Obese Patients Are Frequently Underdosed and at Increased Risk of Periprosthetic Joint Infection
    (Elsevier, 2018) Rondon, Alexander J.; Kheir, Michael M.; Tan, Timothy L.; Shohat, Noam; Greenky, Max R.; Parvisi, Javad; Orthopaedic Surgery, School of Medicine
    Background One of the most effective prophylactic strategies against periprosthetic joint infection (PJI) is administration of perioperative antibiotics. Many orthopedic surgeons are unaware of the weight-based dosing protocol for cefazolin. This study aimed at elucidating what proportion of patients receiving cefazolin prophylaxis are underdosed and whether this increases the risk of PJI. Methods A retrospective study of 17,393 primary total joint arthroplasties receiving cefazolin as perioperative prophylaxis from 2005 to 2017 was performed. Patients were stratified into 2 groups (underdosed and adequately dosed) based on patient weight and antibiotic dosage. Patients who developed PJI within 1 year following index procedure were identified. A bivariate and multiple logistic regression analyses were performed to control for potential confounders and identify risk factors for PJI. Results The majority of patients weighing greater than 120 kg (95.9%, 944/984) were underdosed. Underdosed patients had a higher rate of PJI at 1 year compared with adequately dosed patients (1.51% vs 0.86%, P = .002). Patients weighing greater than 120 kg had higher 1-year PJI rate than patients weighing less than 120 kg (3.25% vs 0.83%, P < .001). Patients who were underdosed (odds ratio, 1.665; P = .006) with greater comorbidities (odds ratio, 1.259; P < .001) were more likely to develop PJI at 1 year. Conclusion Cefazolin underdosing is common, especially for patients weighing more than 120 kg. Our study reports that underdosed patients were more likely to develop PJI. Orthopedic surgeons should pay attention to the weight-based dosing of antibiotics in the perioperative period to avoid increasing risk of PJI.
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    Midterm Survivorship and Complications of Total Knee Arthroplasty in Patients with Dwarfism
    (Elsevier, 2017) Tan, Timothy L.; Kheir, Michael M.; Modi, Ronuk; Chen, Chi-Lung; Shao, Hongyi; Chen, Antonia F.; Department of Orthopaedic Surgery, School of Medicine
    Background Dwarfism is associated with skeletal dysplasias and joint deformities that frequently result in osteoarthritis requiring treatment with total knee arthroplasty (TKA). These surgeries can be challenging because of alignment deformities, poor bone stock, and smaller components. This study aims to compare TKA implant survivorship and complications between dwarf and nondwarf patients. Methods A retrospective case-control study was performed from 1997-2014 evaluating 115 TKAs in patients under the height threshold of 147.32 cm. This cohort was compared with 164 patients of normal height. Medical records were reviewed for demographics, surgical characteristics, and outcomes. All cases had 2-year minimum follow-up. Results The revision rate was 8.7% in dwarfs compared with 3.7% in controls (P = .08). The 2-, 5-, and 10-year implant survivorship in dwarfs was 96.4%, 92.5%, and 90.2%, respectively; and 96.6%, 95.6%, and 94.8% for controls, respectively (P = .24). Dwarfs underwent significantly more manipulations for arthrofibrosis (P = .002). There was greater femoral (17.4% vs 2.1%, P < .01) and tibial (6.5% vs 2.7%, P < .01) component overhang in dwarfs compared with controls. Conclusion Despite a 2-fold increase in the revision rate of the dwarf cohort, the midterm survivorship is comparable between the dwarf and nondwarf patients. However, dwarfs were more likely to become stiff and undergo manipulation; the increased propensity for stiffness may be associated with oversized components, as evidenced by greater component overhang. Surgeons should be aware of this increased risk and may consider using smaller or customized implants to account for the morphological differences in this patient population.
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    Surgical Treatment of Chronic Periprosthetic Joint Infection: Fate of Spacer Exchanges
    (Elsevier, 2019) Tan, Timothy L.; Goswami, Karan; Kheir, Michael M.; Xu, Chi; Wang, Qiaojie; Parvizi, Javad; Orthopaedic Surgery, School of Medicine
    Introduction Patients with periprosthetic joint infection (PJI) undergoing two-stage exchange arthroplasty may undergo an interim spacer exchange for a variety of reasons including mechanical failure of spacer or persistence of infection. The objective of this study was to understand the risk factors and outcomes of patients that undergo spacer exchange during the course of a planned two-stage exchange arthroplasty. Methods Our institutional database was used to identify 533 patients who underwent a two-stage exchange arthroplasty for PJI, including 90 patients with a spacer exchange, from 2000-2017. A retrospective review was performed to extract relevant clinical information. Treatment outcomes included 1) progression to reimplantation and 2) treatment success as defined by a Delphi-based criterion. Both univariate and multivariate COX regression models were performed to investigate whether spacer exchange was associated with failure. Additionally, a propensity score analysis was performed based on a 1:2 match. Results A spacer exchange was required in 16.9%. Patients who underwent spacer exchanges had a higher body mass index (BMI) (p<0.001), rheumatoid arthritis (p=0.018), and were more likely to have PJI caused by resistant (0.048) and polymicrobial organisms (p=0.007). Patients undergoing a spacer exchange demonstrated lower survivorship and an increased risk of failure in the multivariate and propensity score matched analysis compared to patients who did not require a spacer exchange. Discussion Despite an additional load of local antibiotics and repeat debridement, patients who underwent a spacer exchange demonstrated poor outcomes, including failure to undergo reimplantation and twice the failure rate. The findings of this study may need to be borne in mind when managing patients who require spacer exchange.