Debate continues about the best treatment for patients over 65 years with non-displaced subcapital hip fractures: internal fixation (IF) or hemiarthroplasty (HA). Surgical aggression, mortality, complications and recovery of walking ability after 1year have been compared between both treatments. Match-paired comparison of 2 retrospective cohorts. 220 patients with IF vs 220 receiving a cemented bipolar HA. Matching by age (82.6±7.16 years (65–99)), sex (74.5% women), year of intervention (2013–2021) and ASA scale (24.2% ASA II, 55.8% III, 20.0% IV). Age (p=0.172), sex (p=0.912), year of intervention (p=0.638) and ASA scale (p=0.726) showed no differences. Surgical aggression smaller in IF: Surgical time (p< 0,00001), haemoglobin/haematocrit loss (p <0,00001), need for transfusion (p<0,00008), in-hospital stay (p<0,00001). Mortality: higher in-hospital for hemiarthroplasties (12 deaths (5.5%) vs 1 (0.5%) (p=0.004) (RR=12, 1.5–91.5)). But no significant differences in 1-month (13 hemiarthroplasties, 6%, vs 9 osteosynthesis, 4.1%) and 1-year mortality (33 hemiarthroplasties, 15%, vs 35, 16%). Medical complications: no differences in urinary/respiratory infections, heart failure, ictus, myocardial infarction, digestive bleeding, pressure sores or pulmonary embolus (p=0.055). Surgical complications: no significant differences. HA: 6 intraoperative (2,7%) and 5 postoperative periprosthetic fractures (2,3%), 5 infections (2,3%), 10 dislocations (4,5%), 3 neurovascular injuries. IF: 10 acute fixation failures (4,5%), 2 infections (0,9%), 9 non-unions (4,1%), 16 ischemic necrosis (7,3%). Functional results: no significant differences; 12 patients in each group (5,5%) never walked again (p=1), 110 HA (50%) and 100 IF (45.5%) suffered worsening of previous walking ability (p=0.575), 98 HA (44%) and 108 IF patients (49%) returned to pre-fracture walking ability (p=0.339). Fixation with cannulated screws may be a better option for non-displaced femoral neck fractures because recovery of walking ability and complications are similar, while surgical aggression and in-hospital mortality are lower

Aims

This study was designed to develop a model for predicting bone mineral density (BMD) loss of the femur after total hip arthroplasty (THA) using artificial intelligence (AI), and to identify factors that influence the prediction. Additionally, we virtually examined the efficacy of administration of bisphosphonate for cases with severe BMD loss based on the predictive model.

Aims. We aim to evaluate the usefulness of postoperative blood tests by investigating the incidence of abnormal results following total joint replacement (TJR), as well as identifying preoperative risk factors for abnormal blood test results postoperatively, especially pertaining to anaemia and acute kidney injury (AKI). Methods. This is a retrospective cohort study of patients who had elective TJR between January and December 2019 at a tertiary centre. Data gathered included age at time of surgery, sex, BMI, American Society of Anesthesiologists (ASA) grade, preoperative and postoperative laboratory test results, haemoglobin (Hgb), white blood count (WBC), haematocrit (Hct), platelets (Plts), sodium (Na. +. ), potassium (K. +. ), creatinine (Cr), estimated glomerular filtration rate (eGFR), and Ferritin (ug/l). Abnormal blood tests, AKI, electrolyte imbalance, anaemia, transfusion, reoperation, and readmission within one year were reported. Results. The study included 2,721 patients with a mean age of 69 years, of whom 1,266 (46.6%) were male. Abnormal postoperative bloods were identified in 444 (16.3%) patients. We identified age (≥ 65 years), female sex, and ASA grade ≥ III as risk factors for developing abnormal postoperative blood tests. Preoperative haemoglobin (≤ 127 g/dl) and packed cell volume (≤ 0.395 l/l) were noted to be significant risk factors for postoperative anaemia, and potassium (≤ 3.7 mmol/l) was noted to be a significant risk factor for AKI. Conclusion. The costs outweigh the benefits of ordering routine postoperative blood tests in TJR patients. Clinicians should risk-stratify their patients and have a lower threshold for ordering blood tests in patients with abnormal preoperative haemoglobin (≤ 127 g/l), blood loss > 300 ml, chronic kidney disease, ASA grade ≥ III, and clinical concern. Cite this article: Bone Jt Open 2023;4(11):899–905

Primary total joint arthroplasty (TJA) is an increasingly common and safe way of treating joint disease. Robust preoperative assessment improved intraoperative techniques and holistic rehabilitation contribute to an uneventful postoperative period. Despite there being evidence against the utility of postoperative blood tests, it is still often part of routine practice. We aim to evaluate the usefulness of these tests by investigating their incidence following TJA as well as identifying preoperative risk factors for abnormal blood test results postoperatively especially pertaining to anaemia and acute kidney injury (AKI). This is a retrospective cohort study of patients who had elective TJA between January and December 2019 at a tertiary centre. An independent student's t-test and Fisher's exact test was used to compare variables between the normal and abnormal postoperative results groups. An analysis of variance (ANOVA) was performed to identify risk factors for an abnormal blood test result. Analyses of receiver operating characteristic (ROC) curves and the area under the curve (AUC) were used to determine cut off values that could be suggestive of abnormal test results postoperatively. The study included 2721 patients with a mean age of 69 of which 46.6% were males. Abnormal postoperative bloods were identified in 444 (16.3%) patients. We identified age (≥65 years), female gender, ASA ≥ 3 as risk factors for developing abnormal postoperative blood tests. Preoperative haemoglobin (≤ 127 g/dL), haematocrit (≤ 0.395L/L) and potassium (≤ 3.7 mmol/L) were noted as cut-offs that could be predictive of postoperative anaemia or AKI respectively. The costs outweigh the benefits of ordering routine postoperative blood tests in TJA patients. Clinicians should risk stratify their patients and have a lower threshold for ordering blood tests in patients with one or more of the risk factors we have identified. These risk factors are age (≥65 years), females, ASA ≥ 3, preoperative haemoglobin (≤ 127 g/L), haematocrit (≤ 0.395L/L), and potassium (≤ 3.7 mmol/L)

Aims

Our objective was describing an algorithm to identify and prevent vascular injury in patients with intrapelvic components.

Abstract. Objectives. to evaluate the efficacy and safety of topically applied tranexamic acid (TXA) in thoracolumbar spinal tuberculosis surgery, posterior approach. Methods. Thoracolumbar spine tuberculosis patients who requiring debridement, pedicle screw fixation and fusion surgery were divided into two groups. In the TXA group (n=50), the wound surface was soaked with TXA (1 g in 100 mL saline solution) for 3 minutes after exposure, after decompression, and before wound closure, and in the control group (n=116) using only saline. Intraoperative blood loss, drain volume 48 hours after surgery, amount of blood transfusion, transfusion rate, the haemoglobin, haematocrit after the surgery, the difference between them before and after the surgery, incision infection and the incidence of deep vein thrombosis between the two groups. Results. EBL for the control group was 783.33±332.71 mL and for intervention group 410.57±189.72 mL (p<0.001). The operative time for control group was 3.24±0.38 hours and for intervention group 2.99±0.79 hours (p<0.695). Hemovac drainage on days1 and 2 for control group was 167.10±53.83mL and 99.33±37.5 mL, respectively, and for intervention group 107.03±44.37mL and 53.38±21.99mL, respectively (p<0.001). The length of stay was significantly shorter in the intervention group (4.8±1.1 days) compared to control group (7.0±2.3 days). There was bo different in incision side infection and DVT. Conclusions. Topical TXA is a viable, cost-effective method of decreasing perioperative blood loss in major spine surgery with fewer overall complications than other methods. Further studies are required to find the ideal dosage and timing

Reported incidence of blood transfusion following primary and revision total hip arthroplasty (pTHA, rTHA) has decreased considerably compared to historical rates. However, it is not known if further adoption of techniques to limit transfusions has resulted in further reduction on a large scale. The purpose of this study was to assess recent trends in blood transfusions and contemporary risk factors for transfusions using a large, national database. The American College of Surgeons National Surgical Quality Improvement Program was queried to identify patients undergoing pTHA and rTHA between 2011 to 2019. pTHA for fracture, infection, tumor, and bilateral procedures were excluded. Only aseptic rTHA were included. Annual incidence of transfusions and proportion of patients with optimized preoperative hematocrit (HCT) (defined as ≥33%) were assessed. Risk factors for transfusion were evaluated with 2018 and 2019 data using multivariate analyses. 234,352 pTHA and 16,322 rTHA were included. Transfusion following pTHA decreased from 21.4% in 2011 to 2.5% in 2019 and from 33.5% in 2011 to 12.0% in 2019 for rTHA (p<0.0001). Patients with optimized HCT increased for pTHA (96.7% in 2011 vs 98.1% in 2019, p<0.0001) and did not change for rTHA (91.5% in 2011 vs 91.6% in 2019, p=0.27). Decreased HCT was most strongly associated with transfusions, with each three-point change corresponding to odds ratio of 1.90 and 1.78 for pTHA and rTHA, respectively. Increased age, female sex, history of bleeding disorders or preoperative transfusion, ASA score ≥3, non-spinal anesthesia, and longer operative times were also associated with increased odds for transfusion. Incidence of blood transfusion has continued to decrease following pTHA and rTHA. Despite care improvements, transfusions still occur in certain high-risk patients. While transfusion in pTHA may have reached the lower asymptote, further reduction in rTHA may be possible through further improvements in preoperative optimization and surgical technique

Aims

Minimally manipulated cells, such as autologous bone marrow concentrates (BMC), have been investigated in orthopaedics as both a primary therapeutic and augmentation to existing restoration procedures. However, the efficacy of BMC in combination with tissue engineering is still unclear. In this study, we aimed to determine whether the addition of BMC to an osteochondral scaffold is safe and can improve the repair of large osteochondral defects when compared to the scaffold alone.

Aims

This study used an artificial neural network (ANN) model to determine the most important pre- and perioperative variables to predict same-day discharge in patients undergoing total knee arthroplasty (TKA).

Aims

The direct anterior approach (DAA) for total hip arthroplasty (THA) has potential advantages over other approaches and is most commonly performed with the patient in the supine position. We describe a technique for DAA THA with the patient in the lateral decubitus position and report the early clinical and radiological outcomes, the characteristics of the learning curve, and perioperative complications.

Aims. While preoperative bloodwork is routinely ordered, its value in determining which patients are at risk of postoperative readmission following total knee arthroplasty (TKA) and total hip arthroplasty (THA) is unclear. The objective of this study was to determine which routinely ordered preoperative blood markers have the strongest association with acute hospital readmission for patients undergoing elective TKA and THA. Methods. Two population-based retrospective cohorts were assembled for all adult primary elective TKA (n = 137,969) and THA (n = 78,532) patients between 2011 to 2018 across 678 North American hospitals using the American College of Surgeons National Quality Improvement Programme (ACS-NSQIP) registry. Six routinely ordered preoperative blood markers - albumin, haematocrit, platelet count, white blood cell count (WBC), estimated glomerular filtration rate (eGFR), and sodium level - were queried. The association between preoperative blood marker values and all-cause readmission within 30 days of surgery was compared using univariable analysis and multivariable logistic regression adjusted for relevant patient and treatment factors. Results. The mean TKA age was 66.6 years (SD 9.6) with 62% being females (n = 85,163/137,969), while in the THA cohort the mean age was 64.7 years (SD 11.4) with 54% being female (n = 42,637/78,532). In both cohorts, preoperative hypoalbuminemia (< 35 g/l) was associated with a 1.5- and 1.8-times increased odds of 30-day readmission following TKA and THA, respectively. In TKA patients, decreased eGFR demonstrated the strongest association with acute readmission with a standardized odds ratio of 0.75 per two standard deviations increase (p < 0.0001). Conclusion. In this population level cohort analysis of arthroplasty patients, low albumin demonstrated the strongest association with acute readmission in comparison to five other commonly ordered preoperative blood markers. Identification and optimization of preoperative hypoalbuminemia could help healthcare providers recognize and address at-risk patients undergoing TKA and THA. This is the most comprehensive and rigorous examination of the association between preoperative blood markers and readmission for TKA and THA patients to date. Cite this article: Bone Jt Open 2021;2(6):388–396

Aims

The purpose of this study was to examine the efficacy and safety of carbazochrome sodium sulfonate (CSS) combined with tranexamic acid (TXA) on blood loss and inflammatory responses after primary total hip arthroplasty (THA), and to investigate the influence of different administration methods of CSS on perioperative blood loss during THA.

Tranexamic acid (TXA) is an inexpensive antifibrinolytic. Currently there are no national guidelines in the UK that promote the use of TXA in femoral fragility fracture (FFF) management. The aim of the study was to determine whether intra-operative intravenous TXA affects the requirement for post-operative blood transfusion following FFF surgery. A prospective non-randomized case-control study of consecutive FFF admitted to the study centre was performed. 361 patients were included in the study (mean age 81.4yrs; mean BMI 23.5; 73.7% female). TXA was given at the discretion of the operating surgeon, with 178 (49%) patients receiving TXA. Patient demographics, surgical management, peri-operative haemoglobin (Hb) and haematocrit, intravenous TXA use, and requirement for blood transfusion were recorded prospectively. Percentage fall in Hb from preoperative level was calculated at postoperative day one. Calculated-blood-loss (CBL) was determined using the Nadler and Gross formulae. The groups were well matched in terms of patient demographics, injury types and surgical management. The requirement for postoperative blood transfusion was significantly reduced in the TXA group: 15/178 (8.4%) compared to 58/183 (31.7%) (p<0.001; Chi square). TXA significantly reduced both the percentage fall in Hb (mean difference 4.3%, p<0.001) and the CBL (mean difference -222ml, p<0.001). There was no difference in venous thrombosis embolism events between the groups. Intra-operative intravenous TXA during the surgical management of FFF significantly reduced rate of transfusion, CBL and the percentage drop in HB

Aims

Debate continues regarding the optimum management of periprosthetic distal femoral fractures (PDFFs). This study aims to determine which operative treatment is associated with the lowest perioperative morbidity and mortality when treating low (Su type II and III) PDFFs comparing lateral locking plate fixation (LLP-ORIF) or distal femoral arthroplasty (DFA).

Blood management protocols attempt to reduce blood loss by strategies including autologous blood donation, red cell salvage, normovolaemic haemodilution and haemostatic agents such as tranexamic acid (TXA). TXA usage in particular has become increasingly commonplace with numerous studies demonstrating a significant reduction in peri-operative blood loss and proportion of patients requiring transfusion, without increasing the risk of venous thromboembolism. Tourniquet usage has now become ubiquitous in TKA operations with reported benefits of improved visualization, shorter operative time and decreased intra-operative bleeding. However, its use is not without considerable complications including wounding dehiscence, increased venous thromboembolism, superficial wound infection and skin blistering. It is therefore imperative that we review tourniquet usage in light of ever evolving blood management strategies. The aim of this study was to evaluate the effect of stopping tourniquet usage in primary TKRs, performed by an experienced surgeon, in light of new blood reduction measures, such as a TXA. A retrospective analysis identified a total of 31 patients who underwent primary TKR without the use of a tourniquet from January 2018 to March 2019. This was compared to an earlier group of patients from the same surgeon undergoing TKR with the use of a tourniquet; dating from July 2016 to November 2017. All surgeries were performed within the same hospital (CXH). Peri-operative factors and outcome measures were collected for analysis. There was no significant difference in post-operative haemoglobin drop (Tourniquet, 23.1 g/L; No Tourniquet, 24.4 g/: p=0.604) and fall in haematocrit (Tourniquet, 0.082; No Tourniquet, 0.087: p=0.604). Allogenic blood transfusion rates were the same in both groups at 12.9% (2 patients) and blood loss was not found to be significantly different (Tourniquet, 1067ml; No tourniquet, 1058mls). No significant difference was found in operative time (Tourniquet, 103 minutes; No Tourniquet, 111.7 minutes: p=0.152) or length of stay (Tourniquet, 5.5 days; No Tourniquet, 5.2 days: p=0.516). Tranexamic acid usage was not found to be significant (p=1.000). ROM of motion and analgesia requirement was significantly better in the no tourniquet group on one post-operative day out of five analysed (p=0.025, p=00.011). No post-operative thromboembolic events were reported in either group. There was no significant difference in readmission rates (p=0.492) or complications (p=0.238). The increase in minor complications and potential increased VTE risk with tourniquet usage must be balanced against an improved visual field and reduced blood loss in TKR patients. Our study found no difference in post-operative blood loss and transfusion rates between tourniquet and no tourniquet groups. With ever evolving and improving blood loss management strategies, including the use of TXA, the application of tourniquet may not be needed. Further prospective RCTs are needed to assess the impact of tourniquet usage in light of this

In recent years, reduction in the length of stay in patients undergoing UKA has gained considerable interest. This has led to development of ‘fast-track' and even day-case protocols aimed at decreasing length of stay (LOS), enhancing post-operative recovery and decreasing post-operative morbidity. One potential barrier to faster discharge and patient recovery is the need for post-operative haemoglobin checks and allogenic blood transfusion; which has been shown to increase LOS. Allogenic blood transfusion itself is not without risk, including immunological reactions, transfusion associated lung injury, infection and transmission of disease, thus reducing blood loss and the need for transfusion is imperative. Currently there is a knowledge gap regarding post-operative transfusion need and blood loss following UKA. We aimed to investigate blood loss and transfusion rates following UKA. Our primary aim was to evaluate the extent of post-operative transfusion need following UKA and identify which patients are at higher risk of needing transfusion. Following institutional approval, a retrospective analysis of all patients undergoing unicompartmental knee arthroplasty (UKA) at our level one academic university hospital was conducted. Operative records of all patients undergoing primary UKA were reviewed between March 2016 and March 2019. Patients' pre-operative haemoglobin and haematocrit, BMI, co-morbidities, application of tourniquet, tourniquet time, administration of Tranexamic Acid, need for post-operative blood transfusion, hospital length of stay, complications and re-admission were all recorded. Blood loss was estimated using the post-operative haematocrit. A total number of 155 patients were included. There were 70 females (45%) and 85 males (55%). The mean age was 66±10 years. Median pre-op blood volume was 4700mls (IQR; 4200–5100). Median blood loss was 600 mls (IQR; 400–830). Mean pre-op Haemoglobin was 135±14g/L and mean post-op Haemoglobin was 122±13g/L. No patient had a post-op Haemoglobin under 80g/L (Range 93–154). No patients in our study needed transfusion. A further comparison group of high-blood loss and low-blood loss patients was included in analysis. High-blood loss patients were defined as those losing greater than 20% of their pre-operative blood volume whilst low-blood loss patients were defined as those losing ≤20% of their blood volume. Results of these groups are presented in Table 3. No significance was found between the two groups in patient's demographics and in terms of intra-operative factors including TXA usage (p=0.68) and tourniquet time (p=0.99). There was no difference in terms of post-operative complications (p=1.0), length of stay (p=0.36) or readmission rates (p=0.59). The results of our study indicated that post-operative haemoglobin and haematocrit check proved unnecessary in all of our patients and could have been omitted from post-operative routines. We conclude that routine post UKA check of haemoglobin and haematocrit can be avoided and be saved for special circumstances depending on patient's physiology

Introduction. The ideal type of total knee arthroplasty (TKA) prosthesis remains a debatable topic with many different options available. Uncemented TKA has been a viable option due to its decreased operating room (OR) time but also because of its proposed improved long term fixation. Unfortunately, in the past uncemented TKA was associated with increased blood loss. Surgical technique and perioperative treatments have changed since these original studies and tranexamic acid (TXA) has become the gold standard for TKA blood loss management. The objective of this study was to evaluate if there was a difference in hemoglobin and hematocrit change, along with blood loss volume during surgery between cemented and cementless TKA when modern blood loss techniques are utilized. Methods. We retrospectively reviewed data from TKAs performed by three high volume surgeons between 2016 and 2019. We excluded bilateral TKA, revisions, hardware removal intraoperatively and other indications for TKA than primary OA. Power analysis determined 85 patients in both the cementless and cemented TKA groups. Patients were matched 1:1 for age, sex, BMI and surgeon. Use of TXA, intraoperative blood loss, differences in hemoglobin and hematocrit pre- and postoperatively days one, two, and three were recorded. Continuous variables were analyzed using T-tests and categorical variables were evaluated using Chi-squared tests. Results. No significant difference was observed between the cementless and cemented groups for hemoglobin (p=0.214), hematocrit (p=0.164), or intraoperative blood loss volume (p=0.343). A trend towards significantly shorter OR time was seen in the cementless group (p = 0.058). Conclusion. With modern TKA surgery, including the use of TXA, there is no difference in perioperative blood loss between cemented and cementless TKA. Unlike previous studies, the use of modern blood loss salvage techniques in conjunction with cementless TKA fixation, does not result in more blood loss during the perioperative period

Aims

The purpose of this study was to develop a personalized outcome prediction tool, to be used with knee arthroplasty patients, that predicts outcomes (lengths of stay (LOS), 90 day readmission, and one-year patient-reported outcome measures (PROMs) on an individual basis and allows for dynamic modifiable risk factors.

Over 300,000 total hip arthroplasties (THA) are performed annually in the USA. Surgical Site Infections (SSI) are one of the most common complications and are associated with increased morbidity, mortality and cost. Risk factors for SSI include obesity, diabetes and smoking, but few studies have reported on the predictive value of pre-operative blood markers for SSI. The purpose of this study was to create a clinical prediction model for acute SSI (classified as either superficial, deep and overall) within 30 days of THA based on commonly ordered pre-operative lab markers and using data from the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database. All adult patients undergoing an elective unilateral THA for osteoarthritis from 2011–2016 were identified from the NSQIP database using Current Procedural Terminology (CPT) codes. Patients with active or chronic, local or systemic infection/sepsis or disseminated cancer were excluded. Multivariate logistic regression was used to determine coefficients, with manual stepwise reduction. Receiver Operating Characteristic (ROC) curves were also graphed. The SSI prediction model included the following covariates: body mass index (BMI) and sex, comorbidities such as congestive heart failure (CHF), chronic obstructive pulmonary disease (COPD), smoking, current/previous steroid use, as well as pre-operative blood markers, albumin, alkaline phosphate, blood urea nitrogen (BUN), creatinine, hematocrit, international normalized ratio (INR), platelets, prothrombin time (PT), sodium and white blood cell (WBC) levels. Since the data met logistic assumption requirements, bootstrap estimation was used to measure internal validity. The area under the ROC curve for final derivations along with McFadden's R-squared were utilized to compare prediction models. A total of 130,619 patients were included with the median age of patients at time of THA was 67 years (mean=66.6+11.6 years) with 44.8% (n=58,757) being male. A total of 1,561 (1.20%) patients had a superficial or deep SSI (overall SSI). Of all SSI, 45.1% (n=704) had a deep SSI and 55.4% (n=865) had a superficial SSI. The incidence of SSI occurring annually decreased from 1.44% in 2011 to 1.16% in 2016. Area under the ROC curve for the SSI prediction model was 0.79 and 0.78 for deep and superficial SSI, respectively and 0.71 for overall SSI. CHF had the largest effect size (Odds Ratio(OR)=2.88, 95% Confidence Interval (95%CI): 1.56 – 5.32) for overall SSI risk. Albumin (OR=0.44, 95% CI: 0.37 – 0.52, OR=0.31, 95% CI: 0.25 – 0.39, OR=0.48, 95% CI: 0.41 – 0.58) and sodium (OR=0.95, 95% CI: 0.93 – 0.97, OR=0.94, 95% CI: 0.91 – 0.97, OR=0.95, 95% CI: 0.93 – 0.98) levels were consistently significant in all clinical prediction models for superficial, deep and overall SSI, respectively. In terms of pre-operative blood markers, hypoalbuminemia and hyponatremia are both significant risk factors for superficial, deep and overall SSI. In this large NSQIP database study, we were able to create an SSI prediction model and identify risk factors for predicting acute superficial, deep and overall SSI after THA. To our knowledge, this is the first clinical model whereby pre-operative hyponatremia (in addition to hypoalbuminemia) levels have been predictive of SSI after THA. Although the model remains without external validation, it is a vital starting point for developing a risk prediction model for SSI and can help physicians mitigate risk factors for acute SSI post THA

Total knee arthroplasty (TKA) is the most commonly performed elective orthopaedic procedure. With an increasingly aging population, the number of TKAs performed is expected to be ∼2,900 per 100,000 by 2050. Surgical Site Infections (SSI) after TKA can have significant morbidity and mortality. The purpose of this study was to construct a risk prediction model for acute SSI (classified as either superficial, deep and overall) within 30 days of a TKA based on commonly ordered pre-operative blood markers and using audited administrative data from the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database. All adult patients undergoing an elective unilateral TKA for osteoarthritis from 2011–2016 were identified from the NSQIP database using Current Procedural Terminology (CPT) codes. Patients with active or chronic, local or systemic infection/sepsis or disseminated cancer were excluded. Multivariate logistic regression was conducted to estimate coefficients, with manual stepwise reduction to construct models. Bootstrap estimation was administered to measure internal validity. The SSI prediction model included the following co-variates: body mass index (BMI) and sex, comorbidities such as congestive heart failure (CHF), chronic obstructive pulmonary disease (COPD), smoking, current/previous steroid use, as well as pre-operative blood markers, albumin, alkaline phosphatase, blood urea nitrogen (BUN), creatinine, hematocrit, international normalized ratio (INR), platelets, prothrombin time (PT), sodium and white blood cell (WBC) levels. To compare clinical models, areas under the receiver operating characteristic (ROC) curves and McFadden's R-squared values were reported. The total number of patients undergoing TKA were 210,524 with a median age of 67 years (mean age of 66.6 + 9.6 years) and the majority being females (61.9%, N=130,314). A total of 1,674 patients (0.8%) had a SSI within 30 days of the index TKA, of which N=546 patients (33.2%) had a deep SSI and N=1,128 patients (67.4%) had a superficial SSI. The annual incidence rate of overall SSI decreased from 1.60% in 2011 to 0.68% in 2016. The final risk prediction model for SSI contained, smoking (OR=1.69, 95% CI: 1.31 – 2.18), previous/current steroid use (OR=1.66, 95% CI: 1.23 – 2.23), as well as the pre-operative lab markers, albumin (OR=0.46, 95% CI: 0.37 – 0.56), blood urea nitrogen (BUN, OR=1.01, 95% CI: 1 – 1.02), international normalized ratio (INR, OR=1.22, 95% CI:1.05 – 1.41), and sodium levels (OR=0.94, 95% CI: 0.91 – 0.98;). Area under the ROC curve for the final model of overall SSI was 0.64. Models for deep and superficial SSI had ROC areas of 0.68 and 0.63, respectively. Albumin (OR=0.46, 95% CI: 0.37 – 0.56, OR=0.33, 95% CI: 0.27 – 0.40, OR=0.75, 95% CI: 0.59 – 0.95) and sodium levels (OR=0.94, 95% CI: 0.91 – 0.98, OR=0.96, 95% CI: 0.93 – 0.99, OR=0.97, 95% CI: 0.96 – 0.99) levels were consistently significant in all prediction models for superficial, deep and overall SSI, respectively. Overall, hypoalbuminemia and hyponatremia are both significant risk factors for superficial, deep and overall SSI. To our knowledge, this is the first prediction model for acute SSI post TKA whereby hyponatremia (and hypoalbuminemia) are predictive of SSI. This prediction model can help fill an important gap for predicting risk factors for SSI after TKA and can help physicians better optimize patients prior to TKA