The Risk of a Deep Infection Associated With Intraarticular Injections Before a Total Knee Arthroplasty.

The aim of the study is to identify the risks associated with an intraarticular injection before a total knee arthroplasty (TKA). A total of 1628 patients were retrospectively studied over a 7-year period. The patients were divided into 2 groups: patient who received an intraarticular injection before a TKA and patients who did not receive an injection before a TKA. There were 16 deep infections identified (0.98%). Ten deep infections were identified in the patients who did not receive an injection before a TKA (1.18%), and 6 deep infections were identified in patients who received an injection before a TKA (0.77%). There does not appear to be a correlation with the timing of the injection before surgery and increased risk of infection.

Can Component Size in Total Knee Arthroplasty Be Predicted Preoperatively?-An Analysis of Patient Characteristics.

Accurately predicting component sizing in total knee arthroplasty (TKA) can ensure appropriate implants are readily available, avoiding complications from malsizing while also reducing cost by improving workflow efficiency through a reduction in instrumentation. This study investigated the utility of demographic variables to reliably predict TKA component sizes. A retrospective chart review of 337 patients undergoing primary TKA was performed. Patient characteristics (age, sex, race, height, weight) were recorded along with implant and shoe size. Correlation between shoe size and TKA component size was assessed using Pearson's correlation coefficient and linear regression analysis using three models: (A) standard demographic variables, (B) shoe size, and (C) combination of both models. Shoe size demonstrated the strongest correlation with femoral anteroposterior (FAP) (p < 0.001) followed by height (p < 0.001). Conversely, height exhibited the strongest correlation with tibial mediolateral (TML) (p < 0.001) followed by shoe size (p < 0.001). Model C was able to correctly predict both the femur and tibia within one and two sizes in 83.09 and 98.14% of cases, respectively. Individually, model C predicted the FAP within one and two sizes in 83.09 and 96.14% of cases, and the TML in 98.81 and 100% of cases, respectively. A patient's shoe size demonstrates a strong correlation to the TKA implant size, and when combined with standard demographic variables the predictive reliability is further increased. Here, we present a predictive model for implant sizing based solely on easily attainable demographic variables, that will be useful for preoperative planning to improve surgical efficiency. LEVEL OF EVIDENCE: II, Diagnostic.

Delayed peroneal nerve palsy after total knee arthroplasty--a rare complication of tibial osteolysis.

We present a case of peroneal nerve palsy which occurred 12 years after primary total knee arthroplasty as a result of extensive tibial osteolysis. The tibial osteolytic cyst extended through a cortical defect in the proximal tibia into the anterolateral compartment of the leg causing compressive neuropathy of the peroneal nerve. Imaging included radiographs, CT scan and MRI. At revision surgery, the tibial component was found loose with significant proximal tibial osteolysis. The cyst in the leg was decompressed through the cortical defect in the proximal tibia and analysis of cystic fluid revealed polyethylene debris. At 7-year follow-up after revision, the osteolytic cyst had resolved but the peroneal palsy did not recover.