Outcomes of Metaphyseal Cones and Stem Fixation Following Rotating Hinge in Complex Primary and Revision Total Knee Arthroplasty.

BACKGROUND: Although hinged prostheses have been used successfully in complex revision total knee arthroplasty (TKA), concerns exist regarding early failure due to aseptic loosening and other mechanical complications. The use of metaphyseal cones and hybrid cement fixation have been studied in unlinked constrained primary or revision TKA, but their impact on the survivorship of hinged prostheses has yet to be investigated. METHODS: We identified a consecutive series of 164 hinged prostheses and collected data on demographics, indications, complications, and re-revisions in patients who had fully cemented versus hybrid stems, with and without metaphyseal cones. A multivariate analysis was performed to identify independent variables associated with re-revision as the primary end point. RESULTS: In total, 84 patients (51.2%) had fully cemented stems, and 80 patients (48.8%) had hybrid stems. Cones were used in 73 patients (44.5%). At a mean follow-up of 3.4 ± 2.2 years, 42 patients underwent re-revision (25.8%), most commonly for infection (12.2%), followed by loosening (6.7%) and periprosthetic fracture (3.7%). Patients who had fully cemented stems had lower re-revision rates than hybrid fixation constructs (19 versus 26%, P = .043). Using multivariable regression, a construct with hybrid fixation with cones (odds ratio = 2.39; P = .037) was an independent risk factor for failure. Utilization of cones alone did not have an effect on re-revision rates at 3.4-year follow-up. CONCLUSIONS: While we found no difference with the use of cones, patients undergoing revision TKA with a hinge prosthesis and fully cemented stems had better overall survivorship than hybrid stems.

Routine Preoperative Dental Clearance for Total Joint Arthroplasty: Is There a Benefit?

Background Periprosthetic joint infections (PJIs) place significant psychological and financial burdens on patients and healthcare systems. One measure to reduce the risk of PJIs is preoperative dental screening, for which there is no current consensus recommendation. This study aims to determine whether there is a difference in the rate of PJI and microorganism profile in patients who did and did not obtain preoperative dental clearance. Methodology A retrospective review was conducted among patients undergoing primary total hip arthroplasty and total knee arthroplasty from 2017 to 2021. A cohort of 8,654 patients who underwent routine dental clearance was matched with a cohort of patients who did not. Surgeons who changed their dental clearance protocol were also identified, and the rates of PJIs were compared before and after. Results No statistically significant difference was seen in the rate of PJIs between patients who did and did not undergo routine preoperative dental clearance. No statistically significant difference was seen in the rate of PJIs before and after for surgeons who changed their dental clearance protocol. The microorganism profile between the groups was also found to be without differences. Conclusions Eliminating dental clearance from routine preoperative clearance does not appear to increase the rates of acute PJIs following elective total joint arthroplasty (TJA) or to change the organism profile of the infections that did occur. It may be reasonable to not require routine preoperative dental clearance or to practice selective dental clearance in patients undergoing elective TJA, especially given the increased financial cost and delay in care experienced by patients.

The "Kots Wrap": A Technique To Avoid Skin Trauma Related to Isolation Drape Adhesive.

Patients of advanced age or medical diagnoses such as venous insufficiency are predisposed to skin tears when healthcare professionals handle the skin or apply adhesive to it. Isolation drapes are sometimes used to define the area of skin for sterilization prior to a procedure. Such drapes are designed to be secured to the skin with an adhesive edge. Removing such drapes at the end of the procedure can lead to skin tears, especially for patients at risk. We describe a simple technique known as the "Kots Wrap" for applying such an isolation drape in a manner that avoids applying the adhesive edge of the drape to the skin and also allows for removal of the drape in an efficient and atraumatic manner. The use of this technique may help minimize the risk of skin tears in this context and promotes a culture of patient safety.

Fracture of a Metal-Backed Ceramic Liner After Total Hip Arthroplasty: A Case Report.

Total hip arthroplasty (THA) is a common procedure that has become increasingly prevalent in a younger patient population. With improvements in prostheses and materials, the survivorship of implants has increased. Historically, the excellent wear characteristics of ceramic-on-ceramic (CoC) implants made them an appealing choice compared to other bearing options. Yet, the potential benefits of the bearing longevity related to the wear characteristics have been combated by their unique causes of failure such as implant fracture and squeaking. Metal-backed ceramic liners were developed to minimize impingement-related chipping at the periphery of the implant that may propagate to catastrophic implant fracture. We report a case involving a fracture of a metal-backed ceramic liner that presented with months of pain and crepitus with no overt signs of fracture on imaging.

Bilateral Patellar Tendon Rupture Following Total Knee Arthroplasty in a Patient With Alkaptonuria: A Case Report.

Alkaptonuria (AKU) is a rare hereditary disorder of tyrosine degradation. The disorder is characterized by the accumulation of a pigment called homogentisic acid. Its accumulation can lead to the breakdown of connective tissue, including tendons. This report presents a 46-year-old male with a history of bilateral total knee arthroplasty (TKA) who sustained bilateral patellar tendon rupture after an acute injury. A single-stage bilateral knee revision with direct repair of the extensor mechanism augmented with Achilles allograft was performed. The procedure was successful, and the patient had an excellent post-operative outcome at one year post-operatively. This case attempts to highlight the possible complications from AKU in order to better counsel patients with this condition who are undergoing TKA.

Local Anesthesia Approach for Percutaneous Screw Fixation of an Impacted Subcapital Femoral Neck Fracture: A Technique for High-Risk Patients.

Elderly, frail patients and those who have substantial medical co-morbidities who sustain hip fractures present a challenging problem for treatment as they are at very high risk for complications from surgical intervention. The functional outcomes, pain levels, and mortality rates all worsen when non-surgical treatment is used. The safety of administering general or spinal anesthesia may be a concern in certain cases. Other modalities, such as epidural or caudal anesthesia, may be an option; however, the use of local anesthesia may be advantageous for patients with non-displaced and impacted femoral neck fractures undergoing surgical intervention. We present a case report describing the successful treatment of an elderly male who had relative contraindications to spinal anesthesia and high risk for general anesthesia and was successfully treated with percutaneous screw fixation of a femoral neck fracture using local anesthesia with a light, monitored anesthetic.

Mechanical Complications of Hip and Knee Spacers Are Common.

Introduction Two-stage revision is frequently used for the treatment of periprosthetic joint infection (PJI). Because antibiotic-loaded cement spacers are constructed and implanted as temporary devices, mechanical complications are possible. The purpose of our study was to define the incidence of such mechanical complications, determine associated risk factors, and establish if such complications influence the subsequent success of PJI treatment. Methods We identified patients who received an antibiotic spacer for the treatment of PJI at a single center over a six-year timeframe. Medical records and all radiographs were collected and reviewed. Radiographic changes over time were recorded, and mechanical complications were noted. We used multivariate logistic regression analysis to assess risk factors for mechanical spacer complications and assess whether such complications influence the likelihood of subsequent reimplantation and ultimate component retention. Results A total of 236 patients were included in the study. There were 82 hip spacers (28% dynamic and 72% static) with a mechanical complication rate of 8.5% and 154 knee spacers (44% dynamic and 56% static) with a mechanical complication rate of 18.2%. Knee spacers were significantly more likely to have mechanical complications than hip spacers. Other risk factors for mechanical complications included bone loss and elevated body mass index (BMI). Bone loss and advanced age were found to be independent risk factors for failure to undergo second-stage reimplantation. Mechanical spacer failure was not an independent risk factor for the likelihood of subsequent reimplantation or ultimate component retention. Conclusions Mechanical complications of antibiotic spacers are common but do not appear to negatively impact the likelihood of subsequent reimplantation or component retention. In knee spacers and in patients with bone loss or elevated BMI, appropriate patient counseling and strategies to prevent such complications are recommended.

The Complication of a Retained Broken Distal Interlocking Screw Within a Cephalomedullary Nail During Conversion Hip Arthroplasty: A Case Report.

In patients who undergo femoral fracture fixation with a cephalomedullary nail, the breakage of one or more of the distal interlocking screws is a well-described phenomenon. The presence of a broken interlocking screw in patients who require the removal of their cephalomedullary nail presents a unique challenge. The broken interlocking screw may be retrieved, or the screw may be retained if it is not engaged within the nail and the nail can safely be removed while leaving the broken screw fragment behind. We report a hip conversion arthroplasty case with a broken interlocking screw where the nail was removed with ease and the broken screw was assumed to have been left behind. Cerclage wires were placed for an apparent proximal femoral fracture. Postoperative X-rays demonstrated a large lucency tracking from the prior location of the distal interlocking screw to the calcar region. This finding made it evident that the broken screw had been retained in the nail and was dragged up the femur upon nail removal, causing a large gouge spanning the entire femur.

A Video Teaching Tool Is Effective for Training Residents in Hip Arthroplasty Templating.

Work hour restrictions imposed on orthopedic surgery residents since the early 2000s have reduced educational opportunities at the workplace and encouraged alternative strategies for teaching outside the clinical setting. Preoperative templating is essential for safe and effective total hip arthroplasty (THA) and is accurate in predicting final implants. We sought to determine the effectiveness of a video tool for teaching orthopedic residents basic THA templating skills. We developed a video-based teaching tool with instructions on proper THA templating techniques. Ten cases were selected for testing, after excluding patients with severe hip deformities and poor-quality radiographs and only retaining those with concordance between templating by the senior authors and implanted components. The study subjects included three postgraduate year 1 (PGY-1), three PGY-2, and three PGY-5 residents, and three adult reconstruction fellows (PGY-6). Templating skills were assessed before and after watching the instructional video. The evaluation included the size and positioning of femoral and acetabular components, as well as the restoration of leg length. Each templating session was repeated twice. Variance was measured to evaluate consistency in measurements. A linear mixed model and F-test were used for statistical analyses. The number of years in training significantly affected performance prior to exposure to the instructional video. Post-exposure, there was a significant improvement in the accuracy of sizing and positioning of acetabular and femoral components for PGY-1, PGY-2, and PGY-5 residents. The results achieved were comparable to PGY-6 examiners, who did not gain substantial performance benefits from the instructional video. Limb length restoration was less affected by experience or exposure to the video. Component positioning and sizing, as well as leg length discrepancy (LLD), showed a significant decrease in variance after the intervention in all study groups. Video learning is reliable in teaching invaluable skills to orthopedic surgery residents without encroaching on work hours. We conceived a concise video to train orthopedic residents to perform THA templating with proper technique and demonstrated its efficiency and reproducibility.

Systemic Manifestation of Periprosthetic Joint Infection Is Associated With Increased In-Hospital Mortality.

Introduction Periprosthetic joint infection (PJI) is one of the most devastating complications of total joint arthroplasty. Systemic symptoms of infection may indicate a patient who is at a higher risk of serious complications. The goal of this study was to determine if systemic symptoms of infection in the setting of PJI were associated with greater in-hospital mortality. Materials and methods We used our institutional database to identify all patients urgently treated for deep PJI from 2002-2012. Records were reviewed to collect demographics, surgical data, vital signs prior to surgical intervention, blood and intraoperative culture results, preoperative intensive care unit (ICU) admissions, and deaths that occurred during the hospital admission. Patients were classified as having systemic inflammatory response syndrome (SIRS) based on the criteria established by the American College of Chest Physicians and the Society of Critical Care Medicine. Results During the 10-year timeframe of our study, 484 patients were treated emergently for deep infection, with 130 (27%) meeting SIRS criteria preoperatively and 31 (6%) of the patients with SIRS having positive blood cultures. Patients with positive blood cultures and SIRS demonstrated a higher in-hospital mortality rate (p < 0.001). Neither SIRS nor SIRS with positive blood cultures were associated with ICU admission. Discussion Occasionally, PJI can spread beyond the affected joint, showing physical symptoms of systemic illness and bacteremia. This study demonstrates that patients with SIRS and positive blood cultures are at an increased risk of in-hospital mortality. These patients should be monitored closely before definitive treatment in order to minimize their mortality risk.

Late Femoral Component Revision for Femoral Canal Perforation.

Femoral perforation during total hip arthroplasty is a rare complication. Most of the existing literature regarding the complication involves acutely recognized perforations. We report a case of femoral component revision for a symptomatic femoral perforation 12 years after a primary cementless total hip arthroplasty. The revision allowed for intramedullary component positioning, restoration of femoral length and offset, pain relief, and functional improvement. While management of this complication is debatable, we recommend revision in order to avoid future complications and optimize patient outcomes.

Gastrointestinal Complications Following Total Joint Arthroplasty Are Rare but Have Severe Consequences.

BACKGROUND: Gastrointestinal (GI) complications following total joint arthroplasty (TJA) are rare, but can result in substantial morbidity and mortality, especially when intervention is required. The purpose of this study is to identify modifiable risk factors for the development of GI complications and determine their impact on short-term outcomes following TJA. METHODS: We queried patients who underwent primary TJA at a single academic center from 2009 through 2018 and collected data on demographics, comorbidities, operative and perioperative details, and short-term outcomes. Patients who suffered at least one GI complication during the same hospitalization as their TJA were identified. The type of GI complication and intervention performed, if necessary, was recorded. Variables that independently affected the risk of GI complication were identified. Multivariate regression was performed to determine the effect suffering a GI complication had on outcomes. RESULTS: Of 17,402 patients, 106 (0.6%) suffered a GI complication. Constipation/obstruction, followed by diarrhea/malabsorption, hemorrhage, and Clostridium difficile were the most commonly reported complications. Patients suffering a GI complication were significantly older (68.5 vs 63.7, P < .001), less likely to use alcohol (49% vs 65%, P = .008), and had higher incidences of 8 of the 16 comorbidities analyzed (all P < .05). Patients with GI complications had greater lengths of stay (13.2 vs 2.3 days, P < .001), discharge to facility rates (58% vs 16%, P < .001), and in-hospital mortality rates (1.9% vs 0.1%, P = .002). CONCLUSION: Patients suffering a GI complication following TJA require longer hospital stays and greater post-acute care resources and have a substantially higher risk of mortality.

Randomized Trial of Static and Articulating Spacers for Treatment of the Infected Total Hip Arthroplasty.

BACKGROUND: The purpose of this randomized clinical trial is to compare perioperative and postoperative variables between static and articulating spacers for the treatment of chronic periprosthetic joint infection (PJI) complicating total hip arthroplasty (THA). METHODS: Fifty-two patients undergoing resection arthroplasty as part of a 2-stage exchange for PJI at 3 centers were randomized to either a static (n = 23) or articulating spacer (n = 29). The primary endpoint was operative time of the second-stage reimplantation and power analysis determined that 22 patients per cohort were necessary to detect a 20-minute difference. Seven patients were lost to follow-up, 4 were never reimplanted, and one died before discharge after reimplantation. Forty patients were followed for a mean 3.2 years (range 2.0-7.1). RESULTS: There were no differences in operative time at second-stage reimplantation (143 minutes static vs 145 minutes articulating, P = .499). Length of hospital stay was longer in the static cohort after stage 1 (8.6 vs 5.4 days, P = .006) and stage 2 (6.3 vs 3.6 days, P < .001). Although it did not reach statistical significance with the numbers available for study, nearly twice as many patients in the static cohort were discharged to an extended care facility after stage 1 (65% vs 30%, P = .056). CONCLUSION: This randomized trial demonstrated that the outcomes of static and articulating spacers are similar in the treatment of THA PJI undergoing 2-stage exchange arthroplasty. The significantly longer length of hospital stay associated with the use of static spacers may have important economic implications for the health care system.

A Randomized Trial of Static and Articulating Spacers for the Treatment of Infection Following Total Knee Arthroplasty.

BACKGROUND: There is no consensus whether the interim antibiotic spacer utilized in the 2-stage exchange arthroplasty should immobilize the joint or allow for motion. The purpose of this multicenter, randomized clinical trial was to compare static and articulating spacers as part of the 2-stage exchange arthroplasty for the treatment of chronic periprosthetic joint infection complicating total knee arthroplasty as defined with use of Musculoskeletal Infection Society criteria. METHODS: Sixty-eight patients undergoing 2-stage exchange arthroplasty were randomized to either a static (32 patients) or an articulating (36 patients) spacer. An a priori power analysis determined that 28 patients per group would be necessary to detect a 13° difference in range of motion between groups. Six patients were excluded after randomization, 6 died, and 7 were lost to follow-up before 2 years. RESULTS: Patients in the static group had a hospital length of stay that was 1 day greater than the articulating group after stage 1 (6.1 compared with 5.1 days; 95% confidence interval [CI], 5.3 to 6.9 days and 4.6 to 5.6 days, respectively; p = 0.032); no other differences were noted perioperatively. At a mean of 3.5 years (range, 2.0 to 6.4 years), 49 patients were available for evaluation. The mean motion arc was 113.0° (95% CI, 108.4° to 117.6°) in the articulating spacer group, compared with 100.2° (95% CI, 94.2° to 106.1°) in the static spacer group (p = 0.001). The mean Knee Society Score was higher in the articulating spacer cohort (79.4 compared with 69.8 points; 95% CI, 72.4 to 86.3 and 63.6 to 76.1, respectively; p = 0.043). Although not significantly different with the sample size studied, static spacers were associated with a greater need for an extensile exposure at the time of reimplantation (16.7% compared with 4.0%; 95% CI, 0.6% to 38.9% and 0.5% to 26.3%, respectively; p = 0.189) and a higher rate of reoperation (25.0% compared with 8.0%; 95% CI, 9.8% to 46.7% and 1.0% to 26.0%, respectively; p = 0.138). CONCLUSIONS: Articulating spacers provided significantly greater range of motion and higher Knee Society scores at a mean of 3.5 years. Static spacers were associated with a longer hospital stay following removal of the infected implant. When the soft-tissue envelope allows and if there is adequate osseous support, an articulating spacer is associated with improved outcomes. LEVEL OF EVIDENCE: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Accuracy and Validity of Computer Adaptive Testing for Outcome Assessment in Patients Undergoing Total Knee Arthroplasty.

BACKGROUND: Computerized adaptive test (CAT) questionnaires may allow standardization of patient-reported outcome measures and reductions in questionnaire burden. We evaluated the validity, accuracy, and efficacy of a CAT system in patients with end-stage osteoarthritis undergoing total knee arthroplasty. METHODS: CAT Knee Osteoarthritis Outcome Scores (KOOS) and CAT KOOS-JR questionnaires were applied to 1871 standard form KOOS and 1493 KOOS-JR patient responses, respectively. Mean, standard deviations, Pearson's correlation coefficients, interclass correlation coefficients (ICCs), frequency distribution plots, and Bland-Altman plots were used to compare the precision, validity, and accuracy between CAT scores and full-form scores. RESULTS: There was a mean reduction of 14 questions (33%) in the CAT KOOS and 1.4 questions (20%) with the CAT KOOS-JR version, compared with the standard KOOS and KOOS-JR surveys, respectively. There were no significant differences between KOOS and CAT KOOS scores with respect to pain (P = .66), symptoms (P = .43), quality of life (P = .99), activities of daily living (P = .68), and sports (P = .84). Similarly, there were no significant differences between the standard form KOOS-JR and CAT KOOS-JR scores (P = .94). There were strong correlations with minimal variability between the CAT KOOS and standard KOOS questionnaires for pain (r = 0.98, ICC: 0.98), symptoms (r = 0.97, ICC: 0.97), quality of life scores (r = 0.99, ICC: 0.99), activities of daily living scores (r = 0.99, ICC: 0.99), and sports scores (r = 0.99, ICC: 0.99). Similarly, there were strong correlations between the KOOS-JR and the CAT KOOS-JR scores (r = 0.99, ICC: 0.99). CONCLUSION: CAT KOOS and the CAT KOOS-JR versions are accurate and reduce questionnaire burden up to one-third compared with standard surveys. CAT versions may improve patient compliance and decrease fatigue.

Proximal tibial replacement in revision knee arthroplasty for non-oncologic indications.

Proximal tibial metaphyseal bone loss compromises the alignment and fixation of components during revision total knee arthroplasty. In massive, segmental defects with loss of collateral ligamentous support and lack of bone to support the use of prosthetic augments or metaphyseal cones or sleeves, a hinged proximal tibial replacement or a so-called "megaprosthesis" should be available. While proximal tibial replacement is the reconstructive method of choice in the setting of bone tumor resection, applications in non-oncologic joint arthroplasty are rare and may offer an opportunity for limb salvage in dire clinical scenarios with massive proximal tibial bone loss. This report reviews 6 cases of proximal tibial replacement.

Accuracy and Validity of Computer Adaptive Testing for Outcome Assessment in Patients Undergoing Total Hip Arthroplasty.

BACKGROUND: Probability-based computer algorithms that reduce patient burden are currently in high demand. These computer adaptive testing (CAT) methods improve workflow and reduce patient frustration, while achieving high measurement precision. In this study, we evaluated the accuracy and validity of the CAT Hip Disability and Osteoarthritis Outcome Score (HOOS) and the Hip Disability and Osteoarthritis Outcome Score Joint Replacement (HOOS-JR) by comparing them to the full version of these scoring systems in a subset of patients who had undergone total hip arthroplasties. METHODS: A previously developed CAT HOOS and HOOS-JR was applied to 354 and 1547 HOOS and HOOS-JR patient responses, respectively. Mean, standard deviations, Pearson's correlation coefficients, interclass correlation coefficients, frequency distribution plots, and Bland-Altman plots were used to compare the precision, validity, and accuracy between CAT scores and full-form scores. RESULTS: By modifying the questions to past responses, the CAT HOOS demonstrated a mean reduction of 30% of questions (28 vs 40 questions). There were no significant differences between the full HOOS and CAT HOOS with respect to pain (P = .73), symptoms (P = .94), quality of life (P = .99), activities of daily living (P = .82), and sports (P = .99). There were strong linear relationships between the CAT versions and the standard questionnaires (r > 0.99). The Bland-Altman plot showed that differences between CAT HOOS and full HOOS were independent of the overall scores. CONCLUSION: The CAT HOOS and HOOS-JR have high correlation and require fewer questions to finish compared to the standard full-form questionnaires. This may represent a reliable and practical alternative that may be less burdensome to patients and may help improve compliance for reporting outcome metrics.

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

BACKGROUND: Alternative payment models have been viewed as successfully decreasing costs following primary total knee arthroplasty (TKA) while maintaining quality. Concerns exist regarding access to care for patients who may utilize more resources in a bundled payment arrangement. The purpose of this study is to determine if patients undergoing conversion of prior surgery to TKA have increased costs compared to primary TKA patients. METHODS: Claims from Medicare and a single private insurer were queried for all primary TKA patients at our institution from 2015 to 2016. Ninety-day post-acute care costs were compared between primary and conversion TKA. Secondary endpoints included discharge disposition, complications, and readmissions. A multivariate regression analysis was performed to identify independent risk factors for increased post-acute care costs and short-term outcome metrics. RESULTS: Of 3999 primary TKA procedures, 948 patients (23%) underwent conversion TKA. Conversion TKA was associated with greater post-acute care costs in patients with commercial insurance ($4714 vs $3759, P = .034). Among Medicare beneficiaries, prior ligament reconstruction was associated with increased post-acute care costs ($1917 increase, P = .036), while prior fracture fixation approached statistical significance ($2402 increase, P = .055). Conversion TKA was an independent risk factor for readmissions (odds ratio 1.46, 95% confidence interval 1.00-2.17, P = .050), while patients with a prior open knee procedure had higher rates of complications (odds ratio 2.41, 95% confidence interval 1.004-5.778, P = .049). CONCLUSION: Our data suggest that conversion from prior knee surgery to TKA is associated with increased 90-day post-acute care costs and resource utilization, particularly prior open procedures. Without appropriate risk adjustment in alternative payment models, surgeons may be financially deterred from providing quality arthroplasty care given the reduced net payment and surgical complexity of such cases.

Conversion Total Knee Arthroplasty Needs Its Own Diagnosis-Related Group Code.

BACKGROUND: Conversion from a prior knee procedure has been demonstrated to require greater operative times and resources, but still lacks a separate procedural or facility code from primary total knee arthroplasty (TKA). The purpose of this study is to determine differences in facility costs between patients who underwent primary TKA and those who underwent conversion TKA. METHODS: We retrospectively reviewed a consecutive series of patients undergoing primary TKA at 2 hospitals from 2015 to 2017, comparing itemized facility costs between primary and conversion TKA patients. A multivariate regression analysis was performed to identify independent risk factors for increased facility costs, the need for additional implants, length of stay, and discharge disposition. RESULTS: Of 2447 TKA procedures, 678 (27.7%) underwent conversion TKA, which was associated with greater implant costs ($3931.47 vs $2864.67, P = .0120) and total facility costs in a multivariate regression ($94.30 increase, P = .0316). When controlling for confounding variables, patients with a prior ligament reconstruction ($402 increase, P = .0002) and prior open reduction and internal fixation ($847 increase, P = .0020) had higher costs and were more likely to require stemmed implants (P < .05). There was an increase in TKA implant cost by $538 in patients with implants from a prior procedure (P < .0001). CONCLUSION: Conversion TKA is associated with greater implant and inpatient facility costs than primary TKA, particularly those who had a history of an open knee procedure. A separate diagnosis-related group should be created for conversion TKA given the increased cost and complexity of these procedures compared to primary TKA.