Conversion Total Knee Arthroplasty is Associated with Increased Post-Acute Care Costs

Cartilage Restoration Prior to Primary Total Knee Arthroplasty

Cartilage restoration procedures are effective for articular defects of the knee. However, studies suggest decreased clinical improvements after total knee arthroplasty (TKA). The purpose of this study was to compare patients who had a prior cartilage restoration undergoing TKA with patients who had TKA without a prior cartilage restoration procedure. We specifically assessed (1) 90-day and 1-year medical/surgical complications; (2) 90-day and 1-year revision rates; and (3) 90-day costs. A search using a national, all-payer database examined matched cohorts of patients who underwent cartilage restoration procedures prior to TKA (n=22,072) and controls who did not (n=220,364) between January 1, 2010, and April 30, 2020. Cartilage restoration procedures included autologous chondrocyte implantation, microfracture, osteochondral autograft transfer system operations, or open and arthroscopic osteochondral allograft transplantation. Outcomes studied included lengths of stay, 30-day readmission rates, 90-day costs, and medical and surgical complications to include 90-day and 1-year prosthetic joint infections, pathologic fractures, dislocations, knee manipulations, and revisions. Comparable rates of 90-day and 1-year medical and surgical complications were found for TKAs after cartilage restoration. Additionally, 90-day and 1-year revision surgery rates were similar. These patients were also found to have 90-day costs almost identical to those of patients who did not have cartilage restoration. This large analysis of patients with cartilage restoration procedures prior to TKA demonstrated that the complication rates may be similar to those of patients who do not have these operations before TKA. These findings provide valuable information to surgeons and patients when deciding to proceed with TKA after cartilage restoration. [Orthopedics. 2023;46(4):250-255.].

Concurrent Hardware Removal is Associated With Increased Odds of Infection Following Conversion Total Knee Arthroplasty

BACKGROUND

The optimal timing of removal of periarticular implants prior to conversion total knee arthroplasty (TKA) remains to be determined. The purpose of this study was to compare infection rates in conversion TKA when hardware removal was performed in either a staged or concurrent manner.

METHODS

We performed a retrospective study using a national insurance claims database of patients who underwent removal of hardware on the same day or within 1 year before their TKA. A total of 16,099 patients met the criteria. After matching, both final cohorts consisted of 4,502 patients. The 90-day and 1-year rates of prosthetic joint infection were calculated.

RESULTS

The rates of infection were 1.64% and 3.00% in the staged group and 2.62% and 3.95% in the concurrent group at 90 days and 1 year postoperatively, respectively (P = .001, P = .01). Logistic regression analyses demonstrated that patients who had hardware removal greater than 3 months prior to TKA had significantly lower odds of infection at 1-year postop (Odds Ratio 0.61 95% Confidence Interval 0.45-0.84; P = .003).

CONCLUSION

Removal of hardware performed concurrently or within 3 months of a TKA is associated with increased odds of prosthetic joint infection at 1 year postoperatively. Surgeons should consider removing periarticular hardware prior to TKA when possible.

Risk Factors for Nonunion of Distal Femur Fractures

OBJECTIVES

To determine patient, fracture, and construct related risk factors associated with nonunion of distal femur fractures.

DESIGN

Retrospective cohort study.

SETTING

Academic Level I trauma center.

PARTICIPANTS

Patients 18 years and older presenting with OTA/AO 33A and 33C distal femur fractures from 2004 to 2020. A minimum follow-up of 6 months was required for inclusion. OTA/AO 33B and periprosthetic fractures were excluded, 438 patients met inclusion criteria for the study.

MAIN OUTCOMES

The primary outcome of the study was fracture nonunion defined as a return to the OR for management of inadequate bony healing. Patient demographics, comorbidities, injury characteristics, fixation type, and construct variables were assessed for association with distal femur fracture nonunion. Secondary outcomes include conversion to total knee arthroplasty, surgical site infection, and other reoperation.

RESULTS

The overall nonunion rate was 13.8% (61/438). The nonunion group was compared directly with the fracture union group for statistical analysis. There were no differences in age, sex, mechanism of injury, Injury Severity Score, and time to surgery between the groups. Lateral locked plating characteristics including length of plate, plate metallurgy, screw density, and working length were not significantly different between groups. Increased body mass index [odds ratio (OR), 1.05], chronic anemia (OR, 5.4), open fracture (OR, 3.74), and segmental bone loss (OR, 2.99) were independently associated with nonunion. Conversion to total knee arthroplasty (TKA) ( P = 0.005) and surgical site infection ( P < 0001) were significantly more common in the nonunion group.

CONCLUSION

Segmental bone loss, open fractures, chronic anemia, and increasing body mass index are significant risk factors in the occurrence of distal femoral nonunion. Lateral locked plating characteristics did not seem to affect nonunion rates. Further investigation into the prevention of nonunion should focus on fracture fixation constructs and infection prevention.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Cost Analysis of Conversion Total Knee Arthroplasty: A Multi-Institutional Database Study

BACKGROUND

Total knee arthroplasty (TKA) after prior knee surgery, also known as conversion TKA (convTKA), has been associated with higher complications, resource utilization, time, and effort. The increased surgical complexity of convTKA may not be reflected by the relative value units (RVUs) assigned under the current U.S. coding guidelines. The purpose of this study was to compare the RVUs of primary TKA and convTKA and to calculate the RVU per minute to account for work effort.

METHODS

The American College of Surgeons National Surgical Quality Improvement Project (NSQIP) database was analyzed for the years 2005 to 2020. Current Procedural Terminology (CPT) code 27447 alone was used to identify patients who underwent primary TKA, and 27447 plus 20680 were used to identify convTKA. After 1:1 propensity score matching, 1,600 cases were assigned to each cohort. The 2023 Medicare Physician Fee Schedule RVU-to-dollar conversion factor from the U.S. Centers for Medicare & Medicaid Services (CMS) was used to calculate RVU dollar valuations per operative time. Complication rates were compared using a multivariate logistic regression model controlling for baseline characteristics.

RESULTS

The mean operative time for TKA was 97.8 minutes, with a corresponding RVU per minute of 0.25, while the mean operative time for convTKA was 124.3 minutes, with an RVU per minute of 0.19 (p < 0.0001). Using the conversion factor of $33.06 per RVU, this equated to $8.11 per minute for TKA versus $6.39 per minute for convTKA. ConvTKA was associated with higher overall complication (10.9% versus 6.5%, p < 0.0001), blood transfusion (6.6% versus 3.7%, p < 0.01), reoperation (2.3% versus 0.94%, p < 0.0001), and readmission (3.7% versus 1.8%, p < 0.001) rates.

CONCLUSIONS

The current billing guidelines lead to lower compensation for convTKA despite its increased complexity. The longer operative time, higher complication rate, and increased resource utilization may incentivize providers to avoid performing this operation. CPT code revaluation is warranted to reflect the time and effort associated with this procedure.

LEVEL OF EVIDENCE

Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

Is Conversion Total Knee Arthroplasty a Distinct Surgical Procedure? A Comparison to Primary and Revision Total Knee Arthroplasty

Conversion total knee arthroplasty (TKA) is suggested to incur similar complication rates to revision arthroplasties. However, current billing codes do not allow for the differentiation between this operation and primary TKAs. Therefore, the purpose of this study was to compare outcomes of these two surgeries, as well as revision TKAs. Specifically, we analyzed (1) medical complications, (2) surgical complications, and (3) revision rates at 90 days and 1 year. We queried a national, all-payer database to identify patients who underwent TKA without prior implants (n = 1,358,767), required conversion TKA (n = 15,378), and who underwent revision TKA (n = 33,966) between January 1, 2010, and April 30, 2020. Conversion TKA patients (prior implant removal) were identified using the Current Procedural Terminology (CPT) codes. Outcomes studied included 30-day readmission rates and 90-day, as well as 1-year, medical and surgical complications. Conversion TKAs had greater 30-day readmission rates and incidences of most of the complications studied when compared with primary TKAs. The majority of outcomes when comparing between primary, conversion, and revision TKAs were significantly different (p < 0.01). In contrast, conversion TKA complications were similar to revision TKA. Conversion TKAs have higher postoperative complications than primary TKAs and share more similarities with revision TKAs. Thus, the lack of billing codes differentiating conversion and primary TKAs creates a challenge for orthopaedic surgeons.

Conversion Total Knee Arthroplasty

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Conversion total knee arthroplasty (TKA) represents a heterogeneous group of procedures and most commonly includes TKA performed after ligamentous reconstruction, periarticular open reduction and internal fixation (ORIF), high tibial osteotomy (HTO), and unicompartmental knee arthroplasty (UKA).

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Relative to patients undergoing primary TKA, patients undergoing conversion TKA often have longer operative times and higher surgical complexity, which may translate into higher postoperative complication rates.

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There is mixed evidence on implant survivorship and patient-reported outcome measures when comparing conversion TKA and primary TKA, with some studies noting no differences between the procedures and others finding decreased survivorship and outcome scores for conversion TKA.

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By gaining an improved understanding of the unique challenges facing patients undergoing conversion TKA, clinicians may better set patient expectations, make intraoperative adjustments, and guide postoperative care.

Is Conversion TKA a Primary or Revision? Clinical Course and Complication Risks Approximating Revision TKA Rather Than Primary TKA

BACKGROUND

Conversion total knee arthroplasty (convTKA) is associated with increased resource utilization and costs compared with primary TKA. The purpose of this study is to compare 1) surgical time, 2) hospitalization length (LOS), 3) complications, 4) infection, and 5) readmissions in patients undergoing convTKA to both primary TKA and revision TKA patients.

METHODS

The American College of Surgeons National Surgical Quality Improvement Project database was queried from 2008 to 2018. Patients undergoing convTKA (n = 1,665, 0.5%) were defined by selecting Current Procedural Terminology codes 27,447 and 20,680. We compared the outcomes of interest to patients undergoing primary TKA (n = 348,624) and to patients undergoing aseptic revision TKA (n = 8213). Univariate and multivariate logistic regression was performed to identify the relative risk of postoperative complications.

RESULTS

Compared with patients undergoing primary TKA, convTKA patients were younger (P < .001), had lower body mass index (P < .001), and were less likely to be American Society of Anesthesiologist class III/IV (P < .001). These patients had significantly longer operative times (122.6 vs 90.3 min, P < .001), increased LOS (P < .001), increased risks for any complication (OR 1.94), surgical site infection (OR 1.84), reoperation (OR 2.18), and readmissions (OR 1.60) after controlling for confounders. Compared with aseptic TKA revisions, operative times were shorter (122.6 vs 148.2 min, P < .001), but LOS (2.91 vs 2.95 days, P = .698) was similar. Furthermore, relative risk for any complication (P = .350), surgical site infection (P = .964), reoperation (P = .296), and readmissions (P = .844) did not differ.

CONCLUSION

Conversion TKA procedures share more similarities with revision TKA rather than primary TKA procedures. Without a distinct procedural and diagnosis-related group, there are financial disincentives to care for these complex patients.

LEVEL OF EVIDENCE

II.

Traditional Risk Factors and Logistic Regression Failed to Reliably Predict a "Bundle Buster" After Total Joint Arthroplasty

BACKGROUND

The purpose of this study was to determine if we could identify patient factors that were predictive of Medicare and privately insured patients being "high-cost."

METHODS

Ninety-day episode-of-care insurance company payments along with collected demographics, comorbidities, and readmissions were reviewed for a consecutive series of primary total joint arthroplasty patients from 2015 to 2016 at our institution. High-cost patients were identified by determining those patients above the cutoff, where the cost data became demonstrably nonparametric and both univariate analysis and logistical regressions were performed to identify risk factors that lead to increased costs. Receiver operator curves were created to determine the predictive nature of these risk factors.

RESULTS

Univariate analysis showed that high-cost privately insured patients were significantly older, more likely to be readmitted and less likely to be discharged to home (P < .001) whereas high-cost Medicare total knee/total hip arthroplasty patients were more likely to have many of the comorbidities analyzed. Logistical regression did not find any predictive factors for privately insured patients and found that diabetes (OR 1.47 and 1.75, respectively), congestive heart failure (OR 1.94 and 3.46, respectively), cerebrovascular event (OR 2.20 and 2.20, respectively) and rheumatic disease (OR 1.78 and 1.78, respectively) were all predictive of being a high-cost Medicare patient.

CONCLUSION

Traditional risk factors for postoperative complications are not reliably associated with increased patient costs after total hip and total knee arthroplasty. Furthermore, the risk factors associated with increased costs vary greatly between privately insured and Medicare-insured patients. Further investigation is necessary to identify cost drivers in this patient subset to preventive higher costs.