Preoperative radiographic valgus alignment predicts the extent of lateral soft tissue release and need for constraint in valgus total knee arthroplasty.

Background: In total knee arthroplasty (TKA) for valgus knees, the decision to use a constrained implant is often made intraoperatively depending on the extent of soft tissue releases performed and residual soft tissue imbalance. The purpose of this study is to determine if preoperative radiographic criteria of valgus knees can predict the extent of soft tissue releases required and the level of constraint needed to balance the knee during TKA.

Methods: A single surgeon's 807 consecutive TKA standing hip-knee-ankle radiographs from 2007-2012 were analyzed.

Calculating the Cost and Risk of Comorbidities in Total Joint Arthroplasty in the United States.

Background: With increased scrutiny regarding the cost and safety of health care delivery, there is increasing interest in judicious patient selection for total joint arthroplasty (TJA) procedures. It is unknown which comorbidities incur the greatest increase in risk to the patient and cost to the system after TJA. Therefore, this study sought to characterize the association of common preoperative comorbidities with both the risk for postoperative in-hospital complications and the total hospital cost in patients undergoing TJA.

The effective quadriceps and patellar tendon moment arms relative to the tibiofemoral finite helical axis.

The moment arm is a crucial parameter for understanding musculoskeletal dynamics as it defines how linear muscle force is transformed into a moment. Yet, for the quadriceps tendon this parameter cannot be directly calculated, as the patella creates a dynamic fulcrum. Thus, the effective quadriceps moment arm (EQma) was developed to define the quadriceps force to tibial moment relationship.

Antimicrobial Release From Prefabricated Spacers Is Variable and the Dose Is Low.

Background: High-dose antimicrobial-loaded bone cement (ALBC) is recommended to treat orthopaedic infections. Elution characteristics from prefabricated ALBC spacers and how they compare with hand-mixed ALBC are not well described.

Questions/purposes: (1) How does antimicrobial release from prefabricated spacers compare with release from hand-mixed ALBC over time? (2) Is antimicrobial release uniform across the surface of prefabricated ALBC spacers? (3) Do variations exist between different prefabricated spacer components? (4) Do textured surfaces release more antimicrobial than smooth surfaces?

Methods: Six prefabricated ALBC spacer components, two hip and four knee, and three hand-mixed ALBC formulations were studied in this comparative laboratory study.