What are the 2-year survivorship outcomes of custom hemipelvis reconstruction after hemipelvectomy and revision arthroplasty? The evolution of a custom ilium "monoflange".

BACKGROUND: Innovations in machined and three-dimensionally (3D) printed implant technology have allowed for customized complex pelvic reconstructions. We sought to determine the survivorship of custom hemipelvis reconstruction using ilium-only fixation at a minimum 2-year follow-up, their modes of failure, and the postoperative complications resulting from the procedure. METHODS: A retrospective review identified 12 consecutive patients treated with custom hemipelvis reconstruction. Indications for surgery were bone tumor requiring internal hemipelvectomy (four patients) or multiply revised, failed hip arthroplasty with massive bone loss (eight patients). All patients had a minimum of 2-year follow-up with a mean of 60.5 months. Kaplan-Meier survivorship analysis was determined for all patients. Postoperative complications and reoperations were categorized for all patients. RESULTS: At a mean of 60.5 months, 11 of 12 patients had retained their custom implant (92% survivorship). One implant was removed as a result of an acute periprosthetic joint infection (PJI). There were no cases of aseptic loosening. Seven of 12 patients required reoperation (three PJI; two dislocations; two superficial wound complications), with five patients going on to reoperation-free survival. CONCLUSIONS: Custom hemipelvis reconstruction utilizing an ilium monoflange provides durable short-term fixation at a minimum 2-year follow-up. Reoperation for infection and dislocation is common.

Robotic-Assisted Total Knee Arthroplasty Allows for Trainee Involvement and Teaching Without Lengthening Operative Time.

BACKGROUND: Robot-assisted total knee arthroplasty (RA-TKA) is more accurate than mechanical total knee arthroplasty (M-TKA) and can provide real-time feedback about alignment and soft-tissue balancing that may be helpful in trainee education. However, both robotic-assist and trainee involvement potentially increase the surgical time. This study sought to evaluate whether RA-TKA procedures were longer than M-TKA procedures and whether trainee participation added additional surgical time. METHODS: This retrospective cohort study reviewed 220 consecutive primary TKAs (110 M-TKA and 110 RA-TKA) performed by an orthopedic trainee under supervision or performed by the consultant surgeon with an assistant present. For M-TKAs, a measured resection technique was used. For all RA-TKAs, the MAKO robotic system (Stryker, USA) was used. Tourniquet time was measured from inflation immediately prior to skin incision to deflation after placement of the final polyethylene insert. Procedures performed by a consulting surgeon with a surgical assist were used as controls for procedures performed by the trainee. In trainee-conducted procedures, the trainee is responsible for performing all critical aspects of the procedure while the consulting surgeon provides supervision and acts as first assist. RESULTS: 103 M-TKA and 96 RA-TKA were included. Tourniquet time was significantly longer for RA-TKAs vs M-TKAs (100 vs 89 minutes, P < .0001). However, there were no significant differences in tourniquet times between surgery performed by a trainee vs the consulting surgeon with surgical assist for either M-TKA (P = .3452) or RA-TKA (P = .6724). CONCLUSIONS: While RA-TKA takes longer, orthopedic trainees do not add additional time. Trainees at all stages of postgraduate learning can be educated in the use of robotic technology and potentially benefit from real-time feedback without further compromising surgical efficiency or increasing patient risk.

A novel technique for retrieval of a broken biopsy needle.

A broken needle is a rare complication of bone biopsy. We describe an easily applied technique of retrieval of a retained biopsy needle fragment using a cannulated drill typically used for internal fixation of femoral neck fractures. This approach allows for removal under moderate conscious sedation and can be performed by a radiologist using fluoroscopic or CT-fluoroscopic guidance in the radiology suite.

Why Do Patients Stay Longer Than Three Nights Following Hip and Knee Arthroplasty?

BACKGROUND: Prolonged length of stay (PLOS) is frequently cited by secondary data studies as an adverse outcome following hip and knee arthroplasty. Although perhaps indisputable that PLOS increases the cost of hospitalization, it is unknown whether it is an appropriate measure of the quality of an arthroplasty procedure. METHODS: We searched our institution's database for all hip and knee arthroplasty procedures over a 5-year period using MS-DRG (Medicare Severity-Diagnosis Related Group) 469 and 470. Cases with greater than 3 night stays were identified. Charts were manually reviewed by 2 independent reviewers to identify the primary reason for PLOS, and the need for 30-day readmission or reoperation. RESULTS: Of a total 4347 hip and knee arthroplasty cases, 218 (5.0%) were identified with LOS greater than 3 nights. The majority of prolonged stays were due to exclusively medical reasons (81 cases: 37.2%; 95% confidence interval [CI] 31.0-43.7). The second most common cause was inpatient days prior to the arthroplasty procedure (45 cases: 20.6%; 95% CI 15.8-26.5). Orthopedic reasons for PLOS were significantly less common than medical reasons (36 cases: 16.5%; 95% CI 12.2-22.0, P < .0001), most often due to failure to meet therapy goals. Neither readmission (31 cases: 14.2%) nor reoperation (10 cases: 4.6%) was associated with an underlying reason for PLOS. CONCLUSION: When evaluating LOS as a measure of quality of an arthroplasty procedure, readers of secondary "big data" studies should be aware that there are significant limitations to its utility. Even after controlling for potential confounders, we found that PLOS does not necessarily reflect an adverse outcome.

Is There an Optimal Cutoff for Aspiration Fluid Volume in the Diagnosis of Periprosthetic Joint Infection?

BACKGROUND: The diagnosis of periprosthetic joint infection is often challenging in the setting of low aspiration volumes, or in the presence of infection with a slow-growing organism. We sought to determine if an optimal threshold of aspiration fluid volume exists when cultures from the preoperative aspiration are compared to intraoperative cultures. METHODS: All revision total hip and knee arthroplasty procedures over 5 years at our institution were reviewed. Cases were excluded if they underwent joint lavage during aspiration, had an antibiotic spacer in place, were suspected of adverse local tissue reaction to metal debris, did not have an accurate aspiration volume recorded, or if there were no aspiration or operative cultures available. Receiver operating characteristic curves were used to evaluate aspiration volume for identifying cases with identical aspiration and culture results. RESULTS: A total of 857 revision cases were reviewed, among which 294 met inclusion criteria. There were 45 cases (15.3%) with discordant aspiration and operative cultures. The mean aspiration volume for identical cases was significantly higher than for discordant cases (19.1 vs 10.2 mL, P = .02). The proportion of slow-growing organisms was significantly greater among discordant compared to identical operative cultures (52.4% for discordant cases vs 8.2% for identical cases, P < .001). The optimal cutoff value for predicting identical cultures was 3.5 mL for typical organisms and 12.5 mL for slow-growing organisms. CONCLUSION: Aspiration cultures are more likely to correlate with intraoperative cultures with higher aspiration volumes, and the optimal aspiration volume is higher for slow-growing organisms.

The Clinical and Financial Consequences of the Centers for Medicare and Medicaid Services' Two-Midnight Rule in Total Joint Arthroplasty.

BACKGROUND: To lessen the financial burden of total joint arthroplasty (TJA) and encourage shorter hospital stays, the Centers for Medicare and Medicaid Services (CMS) recently removed TKA from the inpatient-only list. This policy change now requires providers and institutions to apply the two-midnight rule (TMR) to short-stay (1-midnight) inpatient hospitalizations (SSIH). METHODS: The National Inpatient Sample from 2012 through 2016 was used to analyze trends in length of stay following elective TJA. Using publically-available policy documentation, published median Medicare payments, and National Inpatient Sample hospital costs, we analyzed the application of the TMR to SSIHs and compared the results to the previous policy environment. Specifically, we modeled 3 scenarios for all 2016 Medicare SSIHs: (1) all patients kept an extra midnight to satisfy the TMR, (2) all patients discharged as an outpatient, and (3) all patients discharged as an inpatient. RESULTS: The overall percentage of Medicare SSIHs increased significantly from 2.7% in 2012 to 17.8% in 2016 (P < .0001). Scenario 1 resulted in no change in out-of-pocket (OOP) costs to patients, no change in CMS payments, and hospital losses of $117.0 million. Scenario 2 resulted in no change in patient OOP costs, reduction in payments from CMS of $181.8 million, and hospital losses of $357.3 million. Scenario 3 resulted in no change in patient OOP costs, no change in CMS payments, and an estimated $1.71 billion of SSIH charges at risk to hospitals for audit. CONCLUSION: The results of this analysis reveal the conflict between length of stay trends following TJA and the imposition of the TMR.

Frequency, Cost, and Clinical Significance of Incidental Findings on Preoperative Planning Images for Computer-Assisted Total Joint Arthroplasty.

BACKGROUND: The frequency of incidental findings with computer-assisted total joint arthroplasty (CA TJA) preoperative imaging and their clinical significance are currently unknown. METHODS: We reviewed 573 patients who underwent primary CA TJA requiring planning imaging. Incidental findings were defined as reported findings excluding those related to the planned arthroplasty. Secondary outcomes were additional tests or a delay in surgery. Associated charges were obtained from our institution's website. Charge and incidence data were combined with TJA volumes obtained from the 2016 National Inpatient Sample to model costs to the healthcare system. RESULTS: Overall, 262 patients (45.7%) had at least 1 incidental finding, 144 patients (25.1%) had 2, and 65 (11.3%) had 3. The most common finding types were musculoskeletal (MSK, 67.7%), digestive (19.5%), cardiovascular (4.9%), and reproductive (4.7%). Also, 9.3% of patients had at least 1 non-MSK incidental finding. Both MSK and non-MSK incidental findings were more common with total hip arthroplasty compared to total knee arthroplasty (67.9% vs 42.2%, P < .0001, and 15.4% vs 8.3%, P < .05, respectively). Further testing was required in 6 cases (1.0%); 1 case required delay in surgery (0.2%). Using the 2016 volume of TJA procedures and assuming a 10%, 15%, and 25%, utilization rate of image-based CA TJA, the annual cost of additional testing was $2.7 million (95% confidence interval, $1.1-$6.3 million), $4.1 million ($1.6-$9.5 million), and $6.9 million (95% confidence interval, $2.7-$15.8 million), respectively. CONCLUSION: Incidental findings are relatively common on planning images. Stakeholders should be aware of the hidden costs of incidental findings given the increasing popularity of image-based CA TJA.

Can a Convolutional Neural Network Classify Knee Osteoarthritis on Plain Radiographs as Accurately as Fellowship-Trained Knee Arthroplasty Surgeons?

BACKGROUND: Osteoarthritis (OA) is the leading cause of disability among adults in the United States. As the diagnosis is based on the accurate interpretation of knee radiographs, use of a convolutional neural network (CNN) to grade OA severity has the potential to significantly reduce variability. METHODS: Knee radiographs from consecutive patients presenting to a large academic arthroplasty practice were obtained retrospectively. These images were rated by 4 fellowship-trained knee arthroplasty surgeons using the International Knee Documentation Committee (IKDC) scoring system. The intraclass correlation coefficient (ICC) for surgeons alone and surgeons with a CNN that was trained using 4755 separate images were compared. RESULTS: Two hundred eighty-eight posteroanterior flexion knee radiographs (576 knees) were reviewed; 131 knees were removed due to poor quality or prior TKA. Each remaining knee was rated by 4 blinded surgeons for a total of 1780 human knee ratings. The ICC among the 4 surgeons for all possible IKDC grades was 0.703 (95% confidence interval [CI] 0.667-0.737). The ICC for the 4 surgeons and the trained CNN was 0.685 (95% CI 0.65-0.719). For IKDC D vs any other rating, the ICC of the 4 surgeons was 0.713 (95% CI 0.678-0.746), and the ICC of 4 surgeons and CNN was 0.697 (95% CI 0.663-0.73). CONCLUSIONS: A CNN can identify and classify knee OA as accurately as a fellowship-trained arthroplasty surgeon. This technology has the potential to reduce variability in the diagnosis and treatment of knee OA.

Hip Disarticulation for Periprosthetic Joint Infection: Frequency, Outcome, and Risk Factors.

BACKGROUND: Currently, the largest available series of hip disarticulation (HD) procedures performed for periprosthetic joint infection (PJI) includes only 6 patients. Given the lack of data on this dreadful outcome, we sought to determine the frequency of and risk factors for HD performed for a primary diagnosis of PJI. METHODS: The National Inpatient Sample from 1998 to 2016 was used to estimate the annual incidences of HD associated with PJI, elective primary total joint arthroplasty (control group 1), and other surgical procedures associated with PJI (control group 2) using National Inpatient Sample trend weights. RESULTS: One-hundred forty-eight HDs for PJI, 2,378,313 primary total joint arthroplasty controls, and 51,580 PJI controls were identified. Median length-of-stay (11 days), proportion of patients with ≥5 comorbidities (22.8%), and median hospital costs ($25,895.60) were all greater for patients with HD compared with both control groups. The weighted frequency of HD hospitalizations increased by 366%, whereas the frequency of cases in control groups 1 and 2 increased by 93% and 310%, respectively, during the same timeframe. Upon multivariable logistic regression, age <65 years without private insurance (reference group: age ≥65 years without private insurance, odds ratio [OR]: 1.55; 95% confidence interval [CI]: 1.08-2.24), diabetes with chronic complications (OR: 1.91; 95% CI: 1.12-3.26), and peripheral vascular disease (OR: 2.59; 95% CI: 1.49-4.48) were significantly associated with increased risk of HD among all patients with PJI. CONCLUSION: While the overall frequency of lower extremity amputations may be decreasing, our study documents an alarming increase in the frequency of HD for PJI during the study period. Patients under age 65 years without private insurance were at significantly higher risk of HD among patients with PJI.

Evidence of Pent-Up Demand for Total Hip and Total Knee Arthroplasty at Age 65.

BACKGROUND: Despite efforts to curtail the economic burden of total joint arthroplasty (TJA), utilization of these successful procedures continues to increase. Previous studies have provided evidence for pent-up demand (delaying necessary medical care until financially feasible) in health care as insurance status changes. We sought to determine whether evidence exists for pent-up demand in the TJA population when patients become eligible for Medicare enrollment. METHODS: The 2014 Nationwide Readmission Database was used to determine the incidence of TJA. The observed increase in incidence from age 64 to 65 was compared to the expected increase. Pent-up demand was calculated by subtracting the expected from the observed difference in frequency of TJA, and excess cost was determined by multiplying this value by the median cost of a primary TJA. The Medicare Expenditure Panel Survey Household Component was used to compare out-of-pocket (OOP) costs, access to care, and insurance coverage among patients aged 60-64 (group 1) and 66-70 (group 2). RESULTS: The expected and observed increases in TJA procedures from age 64 to 65 were 595 and 5211, respectively, resulting in pent-up demand of 4616 joint arthroplasties (1273 THA and 3343 TKA), and an excess cost of $55 million (range, $33 million-$70 million). Mean total OOP expenses for patients in group 1 were significantly greater ($1578.39) than patients in group 2 ($1143.63, P < .001). Despite spending more money OOP, the proportion of patients who were unable to obtain necessary medical care was significantly higher in group 1 than group 2 (4.9% vs 2.4%, P < .0001). This discrepancy was most prominent among patients with public insurance (10.6% vs 2.5%, P < .0001). CONCLUSION: The findings of this study suggest that patients with hip and knee osteoarthritis likely delay elective TJA until they are eligible for Medicare enrollment, resulting in significant additional financial burden to the public health system. As the population ages, it will become increasingly important for stakeholders and policy-makers to be aware of this pent-up demand for TJA procedures. LEVEL OF EVIDENCE: Therapeutic level IV.

What Is the Role of Repeat Aspiration in the Diagnosis of Periprosthetic Hip Infection?

BACKGROUND: The American Academy of Orthopedic Surgeons clinical practice guideline currently recommends repeat joint aspiration when workup of periprosthetic joint infection (PJI) reveals conflicting data. This guideline is based on a single study of 31 patients published 25 years ago. We sought to determine the correlation between first and second aspirations and factors that may play a role in variability between them. METHODS: Sixty patients with less than 90 days between aspirations and no intervening surgery were identified at our institution and classified by Musculoskeletal Infection Society (MSIS) criteria as infected, not infected, or not able to determine after both aspirations. Culture results from both aspirations were recorded. The rates of change and correlation in clinical diagnosis and culture results between aspirations were determined. RESULTS: Repeat aspiration changed the diagnosis in 26 cases (43.3%, 95% confidence interval 31.6-55.9, kappa coefficient 0.32, P < .001), and the culture results in 25 cases (41.7%, 95% confidence interval 30.1-54.3, kappa coefficient 0.27, P < .01). Among patients initially MSIS negative, the proportion who changed to MSIS positive was greater for those with a history of prior PJI compared to those without (66.7% vs 0%, P < .05), and the first aspiration mean volume was higher for those changed to MSIS positive compared to those that remained MSIS negative (12.0 vs 3.0 mL, P < .01). Among patients initially MSIS positive, the proportion of patients who changed to MSIS negative was greater for those with a history of adverse local tissue reaction (ALTR) to metal debris compared to patients without suspicion of ALTR (100% vs 7.7%, P < .05). CONCLUSION: Repeat aspiration is particularly useful in patients with conflicting clinical data and prior history of PJI, suspicion of ALTR, or with high clinical suspicion of infection.

Two-Stage Debridement With Prosthesis Retention for Acute Periprosthetic Joint Infections.

BACKGROUND: Historically, infection control rates with debridement and component retention have been poor in the management of acute prosthetic joint infections. We previously described a 2-stage debridement with prosthesis retention protocol for acute periprosthetic joint infection and reported a 90% success rate in a sample of 20 patients. METHODS: A retrospective review of 83 patients who underwent a 2-stage debridement with implant retention with a minimum 1-year follow-up was performed. Patient data were primarily analyzed to determine infection control rates. Infections were considered controlled when patients had not undergone a reoperation for infection, and demonstrated lack of any clinical signs or symptoms of infection (a well healed wound, diminishing swelling and warmth, absence of erythema, improvement in baseline pain symptoms) A secondary goal of this study was to examine the effects of symptom duration on infection control rate. RESULTS: Average patient follow-up was 41.8 months (range 12-171) for all patients. The overall protocol success rate was 86.7% (72/83): 82.9% in hips and 89.6% in knees. Additionally, protocol success was observed in 45 of 48 primary joints (93.8%) and 27 of 35 (77.1%) revision joints (P = .046). Average time from onset of symptoms to surgery was 6.2 days for successfully treated patients (range 0-27 days) compared to 10.7 days for those who failed treatment (range 1-28 days, P = .070). CONCLUSION: This 2-stage retention protocol resulted in a higher likelihood of infection control compared to prior reports of single stage debridement and modular part exchange.

Mosaic-pattern dedifferentiation in liposarcoma and chondrosarcoma: imaging features of an uncommon form of dedifferentiation.

The term "dedifferentiation" was classically used in sarcoma pathology to refer to tumors in which a high-grade, undifferentiated sarcoma, or a high-grade sarcoma showing heterologous differentiation, arises from a pre-existing neoplasm of borderline or low-grade malignancy. The best recognized examples of this include dedifferentiated liposarcoma, arising from atypical lipomatous tumor/well-differentiated liposarcoma, and dedifferentiated chondrosarcoma, arising from grade 1 hyaline chondrosarcoma of bone. In the overwhelming majority of cases, this dedifferentiated, high-grade sarcoma presents as a macroscopically visible mass, adjacent to and clearly distinct from the pre-existing low-grade lesion. It is less well appreciated that dedifferentiation may also occur in a so-called "mosaic pattern,' in which the high-grade component is intimately admixed with elements of the precursor lesion, forming only microscopically apparent foci. This mosaic or co-mingling pattern of dedifferentiation is also reflected in the MR imaging appearance. In contrast to the classic pattern of dedifferentiation in which there are two distinct juxtaposed masses with different signal intensities and enhancement patterns, such changes are not seen in mosaic dedifferentiation. The imaging features of this pattern of dedifferentiation have not been described. In this report we describe the imaging features of two patients with mosaic pattern dedifferentiation, one with liposarcoma and one with chondrosarcoma. In both cases the precursor lesion was correctly diagnosed by pre-biopsy imaging, but the presence of high-grade sarcoma was not recognized.

Does Intraoperative Fluoroscopy Improve Limb-Length Discrepancy and Acetabular Component Positioning During Direct Anterior Total Hip Arthroplasty?

BACKGROUND: One potential benefit of the direct anterior approach (DAA) for total hip arthroplasty is the ability to use intraoperative fluoroscopy for acetabular cup positioning and limb-length evaluation. Previous studies comparing the use of fluoroscopy with an anterior approach to a posterior approach have reported conflicting results. To our knowledge, no prior study has compared acetabular cup position and limb-length discrepancy (LLD) using a DAA with and without fluoroscopy. METHODS: We retrospectively reviewed the charts of 298 patients who underwent direct anterior total hip arthroplasty with or without intraoperative fluoroscopy. All procedures were performed by 2 surgeons who use DAA as their primary approach. Preoperative and 6-week postoperative low anteroposterior pelvis and cross-table lateral radiographs were reviewed by 3 independent surgeons. Acetabular cup inclination, anteversion, and LLD were measured and compared. RESULTS: Thirty-three patients were excluded for inadequate imaging, leaving 125 patients in the fluoroscopy group and 140 patients in the nonfluoroscopy group. Mean inclination, anteversion, and LLD were 39.4° (95% confidence interval [CI], 38.5°-40.2°), 30.2° (95% CI, 29.2°-31.2°), and 1.1 mm (95% CI, 0.1 mm-2.2 mm) for the fluoroscopy group and 39.9° (95% CI, 39.3°-40.5°), 31.1° (95% CI, 30.0°-32.2°), and 0.8 mm (95% CI, -0.1 mm to 1.6 mm) for the nonfluoroscopy group. There was no significant difference in acetabular inclination (P = .35), anteversion (P = .22), or postoperative LLD (P = .64) between groups. CONCLUSION: This study found no clinically or statistically significant difference in acetabular inclination, anteversion, or LLD between the fluoroscopy and nonfluoroscopy groups. Both surgeons achieved a similar mean acetabular cup position and an equivalent mean LLD.

Does Tibial Slope Affect Perception of Coronal Alignment on a Standing Anteroposterior Radiograph?

BACKGROUND: A standing anteroposterior (AP) radiograph is commonly used to evaluate coronal alignment following total knee arthroplasty (TKA). The impact of coronal alignment on TKA outcomes is controversial, perhaps due to variability in imaging and/or measurement technique. We sought to quantify the effect of image rotation and tibial slope on coronal alignment. METHODS: Using a standard extramedullary tibial alignment guide, 3 cadaver legs were cut to accept a tibial tray at 0°, 3°, and 7° of slope. A computed tomography scan of the entire tibia was obtained for each specimen to confirm neutral coronal alignment. Images were then obtained at progressive 10° intervals of internal and external rotation up to 40° maximum in each direction. Images were then randomized and 5 blinded TKA surgeons were asked to determine coronal alignment. Continuous data values were transformed to categorical data (neutral [0], valgus [L], and varus [R]). RESULTS: Each 10° interval of external rotation of a 7° sloped tibial cut (or relative internal rotation of a tibial component viewed in the AP plane) resulted in perception of an additional 0.75° of varus. CONCLUSION: The slope of the proximal tibia bone cut should be taken into account when measuring coronal alignment on a standing AP radiograph.

Fall Risk Score at the Time of Discharge Predicts Readmission Following Total Joint Arthroplasty.

BACKGROUND: Readmission among Medicare recipients is a leading driver of healthcare expenditure. To date, most predictive tools are too coarse for direct clinical application. Our objective in this study is to determine if a pre-existing tool to identify patients at increased risk for inpatient falls, the Hendrich Fall Risk Score, could be used to accurately identify Medicare patients at increased risk for readmission following arthroplasty, regardless of whether the readmission was due to a fall. METHODS: This study is a retrospective cohort study. We identified 2437 Medicare patients who underwent a primary elective total joint arthroplasty (TJA) of the hip or knee for osteoarthritis between 2011 and 2014. The Hendrich Fall Risk score was recorded for each patient preoperatively and postoperatively. Our main outcome measure was hospital readmission within 30 days of discharge. RESULTS: Of 2437 eligible TJA recipients, there were 226 (9.3%) patients who had a score ≥6. These patients were more likely to have an unplanned readmission (unadjusted odds ratio 2.84, 95% confidence interval 1.70-4.76, P < .0001), were more likely to have a length of stay >3 days (49.6% vs 36.6%, P = .0001), and were less likely to be sent home after discharge (20.8% vs 35.8%, P < .0001). The effect of a score ≥6 on readmission remained significant (adjusted odds ratio 2.44, 95% confidence interval 1.44-4.13, P = .0009) after controlling for age, paralysis, and the presence of a major psychiatric disorder. CONCLUSION: Increased Hendrich fall risk score after TJA is strongly associated with unplanned readmission. Application of this tool will allow hospitals to identify these patients and plan their discharge.

Patient Perception of Value in Bundled Payments for Total Joint Arthroplasty.

BACKGROUND: A central concern for providers in a bundled payment model is determining how the bundle is distributed. Prior studies have shown that current reimbursement rates are often not aligned with patients' values. While willingness-to-pay (WTP) surveys are perhaps useful in a fee-for-service arrangement to determine overall reimbursement, the percentage of payment distribution might be as or more important in a bundled payment model. METHODS: All patients undergoing primary total joint arthroplasty by a single surgeon were offered participation in a preoperative WTP survey. At a minimum 3 months postoperatively, patients were mailed instructions for an online follow-up survey asking how they would allocate a hypothetical bonus payment. RESULTS: From January through December 2014, 45 patients agreed to participate in the preoperative WTP survey. Twenty patients who were minimum 3 months postoperative also completed the follow-up survey. Patients valued total knee and hip arthroplasty at $28,438 (95% confidence interval [CI]: $20,551-36,324) and $39,479 (95% CI: $27,848-$51,112), respectively. At 3 months postoperatively, patients distributed a hypothetical bonus payment 55.5% to the surgeon (95% CI: 47.8%-63.1%), 38% to the hospital (95% CI: 30.3%-45.7%), and 6.5% (95% CI: -1.2% to 14.2%) to the implant manufacturer (P < .001). CONCLUSION: The data suggest that total joint arthroplasty patients have vastly different perceptions of payment distributions than what actually exists. In contrast to the findings of this study, the true distribution of payments for an episode of care averages 65% to the hospital, 27% to the implant manufacturer, and 8% to the surgeon. While many drivers of payment distribution exist, this study suggests that patients would allocate a larger proportion of a bundled payment to surgeons than is currently disbursed. This finding may also provide a plausible explanation for patients' consistent overestimation of surgeon reimbursements.