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Biomedical subjects

Michael S Kwon

Publications and source records attributed to Michael S Kwon.

2 recordsLinked to original sources

Does surgical approach affect total hip arthroplasty dislocation rates?

Dislocation is a common complication of total hip arthroplasty, but exact effect of surgical approach on dislocation rates remains unclear. Because little randomized prospective data exist in this context, we performed a meta-analysis comparing dislocation rates using the posterior approach with and without soft tissue repair. A systematic literature review resulted in five studies which directly compared the posterior approach with and without soft tissue repair. The dislocation rates with and without repair were 0.49% and 4.46%, respectively. The relative risk for dislocation was determined using a fixed effects model with chi square test for interstudy heterogeneity. The posterior approach without soft tissue repair was found to have an 8.21 times greater relative risk of dislocation than with soft tissue repair (95% confidence interval, 4.05-16.67). A separate systematic review of 11 studies revealed comparable dislocation rates associated with the anterolateral, direct lateral, and posterior approaches with soft tissue repair (0.70%, 0.43%, and 1.01%, respectively). These data demonstrate that adequate soft tissue repair greatly reduces the relative risk of dislocation using the posterior approach, and that the dislocation rates for the three most prevalent approaches are similar. Further prospective randomized trials examining dislocation rates and other clinical parameters are needed.

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A novel total knee arthroplasty infection model in rabbits.

Infection of biomaterial implants is an expensive and devastating complication of orthopaedic surgery historically ranging from less than 1% in primary total knee arthroplasty (TKA) to 10% in revision TKA. An in vivo animal model was developed to test the efficacy of innovative therapies for the prevention of biomaterial centered infections caused by methicillin-resistant Staphylococcus aureus bacteria (MRSA). Twenty-two New Zealand White rabbits were used in this study. After proper anesthesia, a stainless-steel screw with a high molecular weight polyethylene (UHMWPE) washer was cemented in a defect created in the intra-articular, non-articulating portion of the lateral femoral condyle of each knee. After closure of the joint capsule, each knee was inoculated with 0, 10(2), 10(3), or 10(4) colony forming units (CFU) of MRSA. Animals were sacrificed after 7 days at which time joint aspirate, tissues and biomaterial samples were examined for evidence of infection. A total of 42 knees were used for analysis. When saline was injected into the knee, 0/10 of the knees demonstrated evidence of biomaterial centered infection (with the contralateral knee receiving 10(4)CFU MRSA). Four of 10 knees developed a biomaterial centered infection when 10(2)CFU MRSA was introduced. Seven out of 10 knees developed a biomaterial centered infection when either 10(3) or 10(4)CFU MRSA was injected. No evidence of septicemia (positive blood cultures) was found in any animal. This rabbit knee model utilizes commonly employed inexpensive orthopaedic implant materials in an in vivo milieu and provides an effective method for the evaluation of treatments for biomaterial centered infections.

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