Biomechanical Study of Patellar Component Fixation with Varying Degrees of Bone Loss.

Background: The decision as to whether or not to resurface the patella in revision total knee arthroplasty (TKA) is affected by the amount of patellar bone stock remaining; however, the impact of the cancellous bone status on patellar component fixation has not been studied. Therefore, we conducted a biomechanical study of patellar component fixation with varying degrees of cancellous bone loss.

Methods: Sixty pairs of cadaveric patellae were randomly assigned between 3 groups and prepared in similar manner to a TKA with the standard 3-hole configuration.

Muscular architecture of the popliteus muscle and the basic science implications.

Background: The function of the popliteus muscle is largely treated as a static stabilizer and has a lack of basic muscular architectural data to enable study of its dynamic function. A large volume of literature supports its static function and the essential need for reconstruction in the posterolateral knee when injured to restore knee stability.

Hypothesis/purpose: We hypothesize that the popliteus muscle is more significant as a dynamic presence in the knee.

Single stage bilateral flexible intramedullary fixation of periprosthetic distal femur fractures.

We present a patient with bilateral Rorabeck II/Su III periprosthetic distal femur fractures treated successfully with bilateral single stage flexible intramedullary fixation. Flexible intramedullary fixation of Rorabeck II/Su III periprosthetic distal femur fractures provides the benefits of shorter operative time, lower blood loss, and preservation of bone stock compared to plate fixation and distal femur replacement. We suggest that for patients with similar injuries flexible intramedullary fixation can be a viable treatment option.

The Radiographic Prepatellar Fat Thickness Ratio Correlates With Infection Risk After Total Knee Arthroplasty.

Background: Obesity has been associated with complications after a total knee arthroplasty (TKA). Surgical site infection (SSI) after TKA is one of the feared complications as it increases revision rates, costs, and stress to the patient. There is conflicting evidence in the literature regarding body mass index (BMI) and risk of infection after TKA, and some studies have suggested that site-specific fat distribution may be a better metric for determining risk of postoperative infections.

Protecting the PCL During Total Knee Arthroplasty Using a Bone Island Technique.

Background: Prior studies have shown that the posterior cruciate ligament (PCL) may be partially resected during cruciate retaining (CR) total knee arthroplasty (TKA) using highly experienced hands and standard surgical technique; therefore, proper surgical technique is aimed at preservation and balance of the PCL during CR TKA. The central objective of this study is to evaluate the effectiveness of a simple surgical technique to prevent PCL damage during performance of a CR TKA.

Methods: Sixty embalmed cadaver specimens were randomized into 2 groups, experimental and control.

Periprosthetic Femoral Stress Fracture After Bisphosphonate Treatment Resulting in Nonunion Successfully Treated with Teriparatide: A Case Report.

Case: We present the case of a postmenopausal osteoporotic woman, treated with bisphosphonates, who developed a stress fracture at the tip of a revision femoral component, resulting in nonunion after several operative treatment attempts. The nonunion healed after 7 months of subcutaneous injections of 20 μg/day of teriparatide.

Conclusion: Teriparatide treatment should be considered for use in recalcitrant stress fractures after total hip arthroplasty.

Effect of Posterior Tibial Slope on Flexion and Anterior-Posterior Tibial Translation in Posterior Cruciate-Retaining Total Knee Arthroplasty.

Reduced posterior tibial slope (PTS) and posterior tibiofemoral translation (PTFT) in posterior cruciate-retaining (PCR) total knee arthroplasty (TKA) may result in suboptimal flexion. We evaluated the relationship between PTS, PTFT, and total knee flexion after PCR TKA in a cadaveric model. We performed a balanced PCR TKA using 9 transfemoral cadaver specimens and changed postoperative PTS in 1° increments.

Shortening femoral osteotomy with stemmed resurfacing total knee arthroplasty for severe flexion contracture in Juvenile Rheumatoid Arthritis.

Juvenile Rheumatoid Arthritis (JRA) is a progressive disease characterized by pain, swelling, and loss of motion in the joints of adolescents. Total knee arthroplasty (TKA) can be indicated, during the adolescent years, in patients with advanced JRA to alleviate pain and improve function. Because of the relative infrequency of TKA in patients with JRA, evaluation of the type of TKA performed and the results merit review.

Efficacy of skin preparation in eradicating organisms before total knee arthroplasty.

The solution of 2% chlorhexidine gluconate and 70% isopropyl alcohol (Chloraprep) is commonly used for antiseptic skin preparation before surgery. We conducted a study to evaluate the efficacy of this solution in eradicating organisms during skin preparation for total knee arthroplasty (TKA), to isolate the organism type, and to evaluate possible contributing factors leading to infection. Ninety-nine patients who were undergoing TKA were swabbed for cultures in the popliteal fossa before and after solution application.

Displaced ischial stress fracture following revision total hip arthroplasty.

Stress fractures of the ischium are uncommon and are most likely caused by excessive stretching or contracture of the hamstring muscles. In addition, revision total hip arthroplasty (THA) may weaken the ilium, and metabolic bone disease may also contribute to a fracture. Treatment is usually conservative and prognosis is favorable.

Quadriceps and patellar tendon pie-crusting as a treatment for limited flexion in total knee arthroplasty.

The pie-crusting method of ligament and tendon lengthening has been used successfully in various tissues but is not reported in the literature as an option for patellar or quadriceps tendons to address flexion limitation. Our case report discusses a patient with longstanding flexion limitation who underwent primary total knee arthroplasty. The report reviews the literature on intraoperative treatments, which primarily pertains to the condition of patella baja, and demonstrates that the pie-crusting technique should be included as a treatment option for a tight extensor mechanism while having some advantages over tibial tubercle osteotomy or Z-plasty.

Total knee arthroplasty with concurrent femoral and tibial osteotomies in osteogenesis imperfecta.

Three total knee arthroplasties (TKA) with concurrent femoral and/or tibial osteotomies in 2 patients with osteogenesis imperfecta were performed from 2004 to 2009. The 2 patients were followed for a mean of 6 years. One patient with concurrent TKA, and femoral and tibial osteotomies developed a nonunion of the tibial site that responded to open reduction and internal fixation with iliac crest bone graft.

Evaluating factors affecting patellar component fixation strength in total knee arthroplasty.

Complications related to the patellofemoral joint after total knee arthroplasty (TKA) represent up to 50% of TKA reoperations. Shear forces across the knee produce wear and occasionally result in failure of fixation of all-polyethylene patellar components. We conducted a study to evaluate the effect of 2 factors on the shear strength of patellar component fixation: time between cement mixing and application of the patellar component, and amount of pressure applied during implantation.

Simultaneous proximal femoral rotational and distal femoral varus osteotomies for femoral retroversion and genu valgum.

Whereas excess femoral anteversion and its related symptoms have been described many times, excess femoral retroversion is less well documented. We report the case of a 30-year-old woman who had a history of chronic bilateral hip and knee pain and evidence of excess femoral retroversion, genu valgum, early-onset lateral and patellofemoral compartment osteoarthritis of both knees, and hip arthritis. She experienced symptomatic relief after undergoing staged bilateral simultaneous proximal femoral rotational and distal femoral lateral opening wedge osteotomies.

Risk factors in total joint arthroplasty: comparison of infection rates in patients with different socioeconomic backgrounds.

Infection after total joint arthroplasty is a serious complication. Several risk factors have been shown to increase the risk of total joint infections. The purpose of this study was to evaluate whether socioeconomic background was a risk factor for infection in primary total joint arthroplasty.

Failed closed reduction of hip arthroplasty secondary to prosthetic incarceration in the pelvis.

This report describes a patient with dislocation of a unipolar hemiarthroplasty that could not be reduced by closed reduction methods because of perforation of the prosthesis through the ileum.