BACKGROUND As the use of intramedullary nails (IMNs) has become more common, there are an increasing number of patients requiring total knee arthroplasty (TKA) who have an indwelling tibial IMN. The purpose of this study is to compare implant survivorship, clinical outcomes, and complications in patients undergoing primary TKA with a history of tibial IMN to those without. METHODS We retrospectively identified 24 TKAs performed between 2000 and 2017 after ipsilateral tibial IMN. Patients were matched 12 to patients undergoing primary TKA without history of tibial IMN based upon age, gender, body mass index, and year of surgery. Mean follow-up was 7 years. RESULTS The 10-year survivorship free of any revision was 100% for the tibial IMN cohort, and 96% for the control cohort, while the 10-year survivorship free of any reoperation was 91% and 89%, respectively (P = .72). Patients with a history of tibial IMN had similar Knee Society Scores to matched controls at 2 years (P = .77) and 5 years (P = .09). Acquired idiopathic stiffness trended toward being more common (17% vs 6%, P = .21) and operative time trended toward being longer (135 vs 118 min, P = .07) when the tibial IMN was removed, but there was no overall difference in complication rate between cohorts. https://www.selleckchem.com/products/uamc-3203.html CONCLUSIONS To our knowledge, this is the first report of primary TKA in patients with a history of ipsilateral tibial IMN. Compared to a matched cohort of patients without tibial IMN, these patients have similar outcomes in regards to implant survivorship, clinical outcomes, and risk of complications. LEVEL OF EVIDENCE Therapeutic Level III. BACKGROUND The aim of this study is to evaluate midterm clinical and radiographic results of total hip arthroplasties (THAs) with cementless implants for adult patients with sequelae from childhood hip infection. METHODS Between 2002 and 2016, 165 patients (165 hips) who had a hip infection during childhood were treated with THAs with cementless implants. The average duration of follow-up was 93.5 months (range 26-206). Clinical results were evaluated via the Harris Hip Score and radiographic results were analyzed with postoperative serial X-rays. RESULTS The average Harris Hip Score increased from 27 (range 8-53) before surgery to 91 (range 45-100) at the latest follow-up examination (P less then .001). At the latest follow-up evaluation, 9 cementless acetabular components demonstrated partial, nonprogressive radiolucencies. No subsidence of more than 2 mm or evidence of a radiolucent line was observed around the femoral components. Intraoperative periprosthetic fractures occurred in 11 hips, including 3 acetabular fractures, 2 fractures of greater trochanter, 1 femoral shaft fracture, and 5 fractures of femoral calcar. Postoperative complications included 3 cases of periprosthetic infection, 1 episode of dislocation, 1 case of a femoral periprosthetic fracture, 5 cases of sciatic nerve injury, 1 case of femoral nerve injury, and 1 case of squeaking from a ceramic bearing surface. CONCLUSION Cementless THA for adult patients with sequelae from childhood hip infection presents significant technical challenges and a relatively high complication rate. With meticulous surgical planning and anticipation for the key technical challenges frequently encountered, the medium-term clinical and radiographic results of THA in this setting were good with high implant survivorship and patient satisfaction. BACKGROUND We implemented a risk assessment tool (RAT) used by clinical navigators to quantify pre-operative mobility, home safety, social/cognitive barriers, and patient health history. We sought to determine if this RAT is associated with the need for post-acute care (PAC) services defined as inpatient rehabilitation and skilled nursing facility, home health, and none (home) following total joint arthroplasty. METHODS The study sample comprised of a total of 1438 primary TJA patients included in a bundled payment model. The RAT score, which ranges from 0 to 100, with higher scores representing healthier, more independent patents, was the key independent variable and post-acute service was the primary outcome variable. RESULTS The median RAT score was 83 (interquartile range 78-87.5) for no PAC discharges compared to 74 (interquartile range 67-81) for inpatient PAC discharges (P less then .0001). After adjusting for the effects of length of hospital stay, surgery type, and patient gender, there was 6× increased odds of inpatient PAC for higher risk patients compared to low risk patients. A RAT score of 74 predicts discharges without PAC 87% of the time. CONCLUSION The RAT that is based on psychosocial, cognitive, environmental factors, and health status was significantly associated with the need for PAC services. The next step is to build and validate a real time, risk adjustment model to assist physicians and patients with planning post-discharge resources. Human walking consists of two major sequential events (i.e., single- and double-support phases). Although there have been many studies relating to basic principles of the each stage, how the two distinct but continuous phases interact with each other remains to be clarified. We examined the change in walking strategy with varying walking speed on a local reference frame with telescoping and tangential axes; we expect that the telescoping directional dynamics at the end of a single-support phase change with walking speed to facilitate the modulation of the push-off work during a double-support phase. The telescoping directional force and power are calculated using two methods model simulation and kinematic configuration. The empirical walking data for eight healthy young subjects and the corresponding model parameters obtained from a data-fit optimization were used to investigate the changing trend of each factor (i.e., force and power) with the increase in speed. The resulting force at the end of the single-support phase significantly increased with the walking speed for both methods, whereas the resulting power remained nearly unchanged and was close to zero for the entire range of walking speeds. This result implies that the positive amount of the telescoping directional force at the end of the single-support phase may be a certain type of preparation for the double-support phase, which can contribute to a larger push-off.