Purpose: Histopathologic analysis of femoral head specimens following total hip arthroplasty (THA) is a routine practice that represents a significant use of health care resources. However, it occasionally results in discovery of undiagnosed hematopoietic malignancy and other discrepant diagnoses such as avascular necrosis. The purpose of this study was to determine the rate of discordant and discrepant diagnoses discovered from routine histopathological evaluation of femoral heads following THA and perform a cost analysis of this practice. Materials and Methods: A review of patients undergoing primary THA between 2004-2017 was conducted. A comparison of the surgeon’s preoperative and postoperative diagnosis, and the histopathologic diagnosis was performed. In cases where the clinical and histopathology differed, a review determined whether this resulted in a change in clinical management. Medicare reimbursement and previously published cost data corrected for inflation were utilized for cost calculations. Results: A review of 2,134 procedures was performed. The pathologic diagnosis matched the postoperative diagnosis in 96.0% of cases. Eighty-three cases (4.0%) had a discrepant diagnosis where treatment was not substantially altered. There was one case of discordant diagnosis where lymphoma was diagnosed and subsequently treated. The cost per discrepant diagnosis was $141,880 and per discordant diagnosis was $1,669 when using 100% Medicare reimbursement and Current Procedural Terminology (CPT) code combination 88304+88311. Conclusion Histopathologic analysis of femoral head specimens in THAs showed an association with high costs given the rarity of discordant diagnoses. Routine use of the practice should be at the discretion of individual hospitals with consideration for cost and utility thresholds.

Background: While multiple studies have demonstrated a lower venous thromboembolism disease (VTED) risk for unicompartmental knee arthroplasty (UKA) compared to primary total knee arthroplasty (TKA), recent reports have shown that revision TKA also had a lower VTED risk compared to primary TKA, an unexpected finding because of its theoretical increased risk. Given the paucity of up-to-date comparative studies, our goal was to perform a highpowered VTED risk comparison study of UKA and revision TKA to primary TKA using recent data. Methods: The National Surgical Quality Improvement Program (NSQIP) database was queried between 2011 and 2018, and we identified 213,234 patients for inclusion: 191,810 primary TKA, 9294 UKA, and 12,130 revision TKA.Demographics, medical comorbidities, and possible VTE risk factors were collected. Thirty-day outcomes, including deep vein thrombosis (DVT), pulmonary embolism (PE), and all-cause VTED were compared between knee arthroplasty types. Results: On multivariate analysis, UKA was significantly associated with lower rates of DVT [OR 0.44 (0.31–0.61); P < 0.001], PE [OR 0.42 (0.28–0.65); P < 0.001], and all-cause VTED [OR 0.42 (0.32–0.55); P < 0.001] when compared to primary TKA. Revision TKA was significantly associated with lower rates of PE [OR 0.62 (0.47–0.83); P = 0.002], and allcause VTED [OR 0.82 (0.70–0.98); P = 0.029] when compared to primary TKA. Conclusions Utilizing recent data from a nationwide patient cohort and controlling for confounding variables, our results showed that both revision TKA and UKA had a lower risk of VTED compared to primary TKA, corroborating the results of recent investigations. Additional prospective investigations are needed to explain this unexpected result.

Background: While multiple studies have demonstrated a lower venous thromboembolism disease (VTED) risk for unicompartmental knee arthroplasty (UKA) compared to primary total knee arthroplasty (TKA), recent reports have shown that revision TKA also had a lower VTED risk compared to primary TKA, an unexpected finding because of its theoretical increased risk. Given the paucity of up-to-date comparative studies, our goal was to perform a highpowered VTED risk comparison study of UKA and revision TKA to primary TKA using recent data. Methods: The National Surgical Quality Improvement Program (NSQIP) database was queried between 2011 and 2018, and we identified 213,234 patients for inclusion: 191,810 primary TKA, 9294 UKA, and 12,130 revision TKA.Demographics, medical comorbidities, and possible VTE risk factors were collected. Thirty-day outcomes, including deep vein thrombosis (DVT), pulmonary embolism (PE), and all-cause VTED were compared between knee arthroplasty types. Results: On multivariate analysis, UKA was significantly associated with lower rates of DVT [OR 0.44 (0.31–0.61); P < 0.001], PE [OR 0.42 (0.28–0.65); P < 0.001], and all-cause VTED [OR 0.42 (0.32–0.55); P < 0.001] when compared to primary TKA. Revision TKA was significantly associated with lower rates of PE [OR 0.62 (0.47–0.83); P = 0.002], and allcause VTED [OR 0.82 (0.70–0.98); P = 0.029] when compared to primary TKA. Conclusions Utilizing recent data from a nationwide patient cohort and controlling for confounding variables, our results showed that both revision TKA and UKA had a lower risk of VTED compared to primary TKA, corroborating the results of recent investigations. Additional prospective investigations are needed to explain this unexpected result.

Purpose: Accurate component placement and restoration of patient anatomy are critical in total hip arthroplasty (THA) surgery. Although intraoperative radiographs are sometimes utilized, it is unclear whether this practice can improve accuracy. Materials and Methods: This study evaluated acetabular cup abduction, anteversion, leg length, and offset among 100 posterior approach THAs performed without imaging (No X-ray group) and compared them to a subsequent series of 100 THAs where an intraoperative radiograph was taken with the trial components in place (X-ray group). THAs were performed using a posterior approach by a single, experienced surgeon whose goal was to place the cup at 45° of abduction and 30° of anteversion. Supine anteroposterior pelvic digital radiographs taken at the first (nominal 4-week) postoperative visit were used for measurements. Results: Slight differences in cup abduction (47°±6° vs 44°±6°, respectively, P=0.003) and anteversion angle (35°±6° vs 31°±6°, respectively, P<0.001) were observed between the X-ray and No X-ray groups; however, a similar proportion of cups within 10° of the target angles was observed (76% vs 83%, respectively, P=0.22). No difference in offset measurements (1.1±6.6 mm vs 0.3±6.9 mm, respectively, P=0.42) or leg lengths (0.3±3.8 mm vs 0.3±4.8 mm, respectively, P=0.94) was observed between the X-ray and No X-ray groups; however, the X-ray group showed less leg length variation (P=0.05). Conclusion In this study, the routine use of intraoperative radiographs was not associated with improved implant positioning for uncomplicated primary THA.

Background: Preoperative radiographic templating for total knee arthroplasty (TKA) has been shown to be inaccurate. Patient demographic data, such as gender, height, weight, age, and race, may be more predictive of implanted component size in TKA. Materials and methods: A multivariate linear regression model was designed to predict implanted femoral and tibial component size using demographic data along a consecutive series of 201 patients undergoing index TKA.Traditional, two-dimensional, radiographic templating was compared to demographic-based regression predictions on a prospective 181 consecutive patients undergoing index TKA in their ability to accurately predict intraoperative implanted sizes. Surgeons were blinded of any predictions. Results: Patient gender, height, weight, age, and ethnicity/race were predictive of implanted TKA component size.The regression model more accurately predicted implanted component size compared to radiographically templated sizes for both the femoral (P = 0.04) and tibial (P < 0.01) components. The regression model exactly predicted femoral and tibial component sizes in 43.7 and 43.7% of cases, was within one size 90.1 and 95.6% of the time, and was within two sizes in every case. Radiographic templating exactly predicted 35.4 and 36.5% of cases, was within one size 86.2 and 85.1% of the time, and varied up to four sizes for both the femoral and tibial components. The regression model averaged within 0.66 and 0.61 sizes, versus 0.81 and 0.81 sizes for radiographic templating for femoral and tibial components. Conclusions A demographic-based regression model was created based on patient-specific demographic data to predict femoral and tibial TKA component sizes. In a prospective patient series, the regression model more accurately and precisely predicted implanted component sizes compared to radiographic templating.Level of evidence: Prospective cohort, level II.

Purpose: The aim of this study was to determine if contralateral knee range of motion is associated with postoperative range of motion in the operative knee after total knee arthroplasty. Methods: Contralateral (nonoperative) knee range of motion was compared to postoperative knee range of motion after total knee arthroplasty using linear regression models in 59 patients who had undergone primary total knee arthroplasty with a minimum of 4 months postoperative follow-up data (range 4–13 months). Results: A strong linear relationship was observed between contralateral knee ranges of motion of 115° or greater and postoperative knee ranges of motion after total knee arthroplasty (slope 0.93, 95% CI 0.58–1.29, P < 0.0001), with a mean difference of −7.44° (95% CI −10.3 to −4.63, P < 0.0001). However, there was no association between contralateral knee range of motion and postoperative knee range of motion when contralateral knee range of motion was less than 115°. Conclusion Contralateral knee range of motion of 115° or greater correlates linearly with postoperative range of motion after total knee arthroplasty, and thus may be predictive in such cases.

Background: Preoperative radiographic templating for total knee arthroplasty (TKA) has been shown to be inaccurate. Patient demographic data, such as gender, height, weight, age, and race, may be more predictive of implanted component size in TKA. Materials and methods: A multivariate linear regression model was designed to predict implanted femoral and tibial component size using demographic data along a consecutive series of 201 patients undergoing index TKA.Traditional, two-dimensional, radiographic templating was compared to demographic-based regression predictions on a prospective 181 consecutive patients undergoing index TKA in their ability to accurately predict intraoperative implanted sizes. Surgeons were blinded of any predictions. Results: Patient gender, height, weight, age, and ethnicity/race were predictive of implanted TKA component size.The regression model more accurately predicted implanted component size compared to radiographically templated sizes for both the femoral (P = 0.04) and tibial (P < 0.01) components. The regression model exactly predicted femoral and tibial component sizes in 43.7 and 43.7% of cases, was within one size 90.1 and 95.6% of the time, and was within two sizes in every case. Radiographic templating exactly predicted 35.4 and 36.5% of cases, was within one size 86.2 and 85.1% of the time, and varied up to four sizes for both the femoral and tibial components. The regression model averaged within 0.66 and 0.61 sizes, versus 0.81 and 0.81 sizes for radiographic templating for femoral and tibial components. Conclusions A demographic-based regression model was created based on patient-specific demographic data to predict femoral and tibial TKA component sizes. In a prospective patient series, the regression model more accurately and precisely predicted implanted component sizes compared to radiographic templating.Level of evidence: Prospective cohort, level II.