Prior Nonarthroplasty Surgery Increases Risk of Complication in Primary Total Knee Arthroplasty

BackgroundPrior ipsilateral knee surgery may increase the risk for complications after total knee arthroplasty (TKA). It remains unclear if the extent of previous surgery affects those risks disparately. The purpose of this study is to evaluate prior nonarthroplasty bony procedure (BP) and soft tissue only procedure (STP) as a potential risk factor for complications after TKA and determine the association with charges or reimbursement of the primary TKA.MethodsPatients who underwent primary TKA with previous knee surgery were identified using a national Medicare database and matched 1:5 to controls without prior knee surgery. Rates of postoperative medical and surgical complications were calculated in addition to hospital-associated charges and reimbursements. Logistic regression analysis was used to control for confounding factors.ResultsPatients who underwent BP (n = 835) had increased risk of readmission (58.6% vs 45.3%, odds ratio (OR) 1.72, 95% confidence interval (CI) 1.59-1.85, P < .001) and emergency room visits (14.5% vs 10.4%, OR 1.44, 95% CI 1.29-1.61, P = .001). Patients who underwent STP (n = 6766) had increased risk of readmission (58.1% vs 45.2%, OR 1.69, 95% CI 1.64-1.73, P < .001), emergency room visits (12.6% vs 0.7%, OR 1.33, 1.28-1.39, P < .001), revision (1.8% vs 1.4%, OR 1.33, 95% CI 1.21-1.47, P = .006), cerebrovascular accident (2.3% vs 1.7%, OR 1.33, 95% CI 1.22-1.46, P = .002), and venous thromboembolism (3.8% vs 3.2%, OR 1.21, 95% CI 1.13-1.29, P = .009). Prior surgery was associated with increased charges and reimbursements.ConclusionPrior ipsilateral knee surgery is associated with significantly increased risks of postoperative complications after primary TKA. Interestingly, previous STP but not BP increased the risk of short-term revision and venous thromboembolism.     

Increased Revisions in Conversion Total Knee Arthroplasty After Periarticular Open Reduction Internal Fixation Compared With Primary Total Knee Arthroplasty: A Matched Cohort Analysis

BackgroundPrior studies on conversion total knee arthroplasty (cTKA) have reported increased technical challenges and risk of complications compared with primary knee arthroplasty. The purpose of this study was to compare two-year postoperative complication/revision rates between patients undergoing cTKA after prior periarticular open reduction and internal fixation (ORIF) and those undergoing primary TKA.MethodsPatients who underwent cTKA after prior periarticular ORIF of the ipsilateral knee were identified in a national all-payer claims database from 2010 to 2018. This ORIF-cTKA cohort was propensity matched to participants undergoing primary TKA based on age, gender, Charlson comorbidity index, and obesity status. Univariate analysis was performed to analyze differences in two-year complication and revision rates.ResultsAfter propensity matching, 823 patients were included in the ORIF-cTKA cohort and 1640 patients in the primary TKA cohort. No differences in demographics or comorbidities existed between cohorts. Relative to the primary TKA cohort, the ORIF-cTKA cohort had significantly higher incidences of all-cause revision (5.47% vs 2.47%, P = .001), periprosthetic joint infection (PJI; 4.74% vs 1.34%, P < .001), and intraoperative or postoperative periprosthetic fracture (1.58% vs 0.55%, P = .01) at two years postoperatively. There was also a nonsignificant trend toward increased rates of aseptic loosening (1.82% vs 0.91%, P = .052) in the ORIF-cTKA.ConclusionRelative to primary TKA, cTKA after periarticular ORIF is associated with significantly increased rates of all-cause revision, PJI, and periprosthetic fracture at two years postoperatively. Surgeons should counsel these patients about the increased risks of these postoperative complications and consider treating them as high risk for PJI in the perioperative period.     

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

BackgroundAlternative 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.MethodsClaims 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.ResultsOf 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).ConclusionOur 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.     

Staged vs Concurrent Hardware Removal During Conversion Total Knee Arthroplasty

BackgroundConversion total knee arthroplasty (TKA) in the presence of periarticular hardware can be associated with increased resource utilization, complications, and revisions. However, little guidance exists on the optimal approach to hardware removal. The purpose of this study is to compare outcomes of conversion TKA with hardware removal performed in either a staged or concurrent manner.MethodsThis is a retrospective study of 155 TKA operations performed with staged (45) or concurrent (110) removal of hardware at the time of TKA. Differences in patient data, case data, complications, reoperations, and revisions were evaluated. Subgroup comparisons of cases involving major hardware (plates, nails, rods), minor hardware (screws, buttons, wires), and tibial plates were performed.ResultsThere were no differences in age, sex, body mass index, or comorbidities between patients who underwent staged or concurrent hardware removal. Rates of complications, reoperations, and revisions did not differ at multiple time points (90 days, 1 year, 2 years, 4 years). Patients who underwent staged hardware removal were more likely to have had prior surgery for fracture reconstruction (68% vs 33%, P < .001), to have had major hardware removed (84% vs 59%, P = .03), and were less likely to have had hardware removal performed through a single incision with TKA (50% vs 92%, P < .001). Subgroup analysis of major and minor hardware cases demonstrated comparable outcomes.ConclusionThere remains no established benefit to either a staged or concurrent approach to hardware removal at the time of TKA. This is true regardless of hardware burden. At this time, a case-by-case approach should be taken to conversion TKA in the presence of periarticular hardware.     

Prior Knee Arthroscopy Increases the Failure Rate of Subsequent Unicompartmental Knee Arthroplasty

BackgroundIn selected patients, knee arthroscopy is performed prior to unicompartmental knee arthroplasty (UKA) to treat symptomatic mechanical pathology, delay arthroplasty, and assess the knee compartments. The purpose of this study was to determine if knee arthroscopy prior to UKA is associated with increased rates of UKA failure or conversion to total knee arthroplasty (TKA).MethodsData was collected from the Humana insurance database from 2007-2017. Patients who underwent knee arthroscopy within two years prior to UKA were identified and matched with controls based on age, gender, Charlson Comorbidity Index, smoking status, and obesity. Rates of conversion to TKA and failure for various causes were compared between cohorts.ResultsPrior to propensity matching, 8353 UKA patients met inclusion criteria. Of these, 1079 patients (12.9%) underwent knee arthroscopy within two years of UKA and were matched to 1079 patients (controls) who did not undergo knee arthroscopy in the two years preceding UKA. No differences in demographics/comorbidities existed among cohorts. Compared to controls, the knee arthroscopy cohort was more likely to experience failure for aseptic loosening (2.4% vs 1.1%; OR 2.166; P = .044) and significantly more likely to require conversion to TKA (10.4% vs 4.9%; OR 2.113; P < .001) within two years of UKA.ConclusionKnee arthroscopy within two years of UKA is associated with an increased rate of UKA conversion to TKA and a higher rate of UKA failure from aseptic loosening. Although clinicians should be mindful of this association when performing knee arthroscopy in patients who may be indicated for future UKA, further research is needed to better characterize these findings.     

Unicompartmental Knee Arthroplasty: More Conversions,Fewer Complications Than Proximal Tibial Osteotomy in a Young Population

BackgroundPatients with isolated medial compartment osteoarthritis requiring surgical intervention generally have two surgical options: unicompartmental knee arthroplasty (UKA) and proximal tibial osteotomy (PTO). Outcomes of reoperation rates and survivorship are important for counseling patients on treatment options.MethodsA retrospective, comparative cohort study was performed for a consecutive series of patients in the Military Health System who underwent either UKA or PTO between 2003 and 2018. All patients were between 18 and 55 years old and diagnosed with isolated medial compartmental arthritis. Cases with concurrent meniscal or cartilage procedures were included, while cases with concurrent ligament reconstruction were excluded. A minimum 2-year follow-up was required. The primary outcome was conversion to total knee arthroplasty, and the secondary outcome was reoperation for any reason.ResultsA total of 383 procedures were performed for isolated medial compartment arthritis in 303 patients (UKA 270, PTO 113). A multivariate analysis showed that PTO was associated with decreased risk of conversion to TKA compared to UKA (P = .0364). However, the reoperation due to complications was significantly higher in the PTO group (21.2% vs 2.2%; P ≤ .01). The 5-year conversion rate was 13.7% for UKA and 3.5% for PTO (P = .0033) with an average time to conversion of 3.1 years for UKA and 2.9 years for PTO (P = .7805).ConclusionsIn young patients with isolated medial compartment arthritis, conversion rates to TKA are higher with UKA compared to PTO. However, overall reoperation rate is higher with PTO, secondary to complications and revision procedures. Overall survivorship is acceptable for both procedures.     

Outcome of Revision Surgery for the Idiopathic Stiff Total Knee Arthroplasty

BackgroundIdiopathic stiff total knee arthroplasty (TKA) represents one of the most challenging subsets of the stiff TKA, as the etiology is unknown and there is no consensus on the most appropriate surgical treatment modality. Therefore, the aim of this study is to report on postoperative outcomes of revision surgery for idiopathic stiff TKA.MethodsWe retrospectively reviewed 189 consecutive patients (202 knees) who underwent revision TKA for stiffness: (1) 101 knees in the idiopathic stiffness cohort and (2) 88 in the non-idiopathic stiffness cohort. In the idiopathic stiffness cohort, 42 knees underwent isolated tibial insert exchange and 59 knees underwent component revision. Perioperative knee range of movement and complications were analyzed.ResultsThe overall revision surgery outcomes of the idiopathic stiffness cohort were worse than those of the non-idiopathic stiffness cohort with regard to maximum flexion (91.7° vs 100.1°, P = .02) and flexion range of motion (ROM) (87.6° vs 97.1°, P = .01). In the idiopathic stiffness cohort, isolated tibial insert exchange demonstrated greater maximum flexion (96.8° vs 88.4°, P = .06) and flexion ROM (93.2° vs 83.9°, P = .07). In terms of re-revision rates, the isolated tibial insert exchange idiopathic stiffness cohort demonstrated lower re-revision rates compared to the component revision idiopathic stiffness cohort (16.7% vs 31.0%, P = .01).ConclusionThis study demonstrates that the overall revision surgery outcome of idiopathic stiff TKA is worse than non-idiopathic TKA stiffness. In idiopathic stiffness cohorts, isolated tibial insert exchange was associated with lower re-revision rates than component revision, with similar efficacy in improving ROM, suggesting that isolated tibial insert exchange may be a preferred surgical treatment option in TKA patients with idiopathic stiffness.     

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

BackgroundConversion 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.MethodsWe 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.ResultsOf 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).ConclusionConversion 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.     

High Bundled Payment Costs Following Total Hip and Knee Arthroplasty in African Americans

BackgroundConcerns exist that minorities who utilize more resources in an episode-of-care following total hip (THA) and knee arthroplasty (TKA) may face difficulties with access to quality arthroplasty care in bundled payment programs. The purpose of this study is to determine if African American patients undergoing TKA or THA have higher episode-of-care costs compared to Caucasian patients.MethodsWe queried Medicare claims data for a consecutive series of 7310 primary TKA and THA patients at our institution from 2015 to 2018. We compared patient demographics, comorbidities, readmissions, and 90-day episode-of-care costs between African American and Caucasian patients. A multivariate regression analysis was performed to identify the independent effect of race on episode-of-care costs.ResultsCompared to Caucasians, African Americans were younger, but had higher rates of pulmonary disease and diabetes. African American patients had increased rates of discharge to a rehabilitation facility (20% vs 13%, P < .001), with higher subacute rehabilitation ($1909 vs $1284, P < .001), home health ($819 vs $698, P = .022), post-acute care ($5656 vs $4961, P = .008), and overall 90-day episode-of-care costs ($19,457 vs $18,694, P = .001). When controlling for confounding comorbidities, African American race was associated with higher episode-of-care costs of $440 (P < .001).ConclusionAfrican American patients have increased episode-of-care costs following THA and TKA when compared to Caucasian patients, mainly due to increased rates of home health and rehabilitation utilization. Further study is needed to identify social variables that can help reduce post-acute care resources and prevent reduction in access to arthroplasty care in bundled payment models.     

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

BackgroundThe 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.MethodsWe 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.ResultsThe 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).ConclusionRemoval 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.     

Comparison of Modular Conventional and High-Flexion Posterior-Stabilized Total Knee Arthroplasties in the Same Patients at a Mean Follow-Up of 15 Years

BackgroundAs previous studies are limited to short-term clinical data on conventional and high-flexion total knee arthroplasties (TKAs), long-term clinical data on these TKAs remain unclear. Therefore, we evaluated long-term functional outcome, range of knee motion, revision rate, implant survival, and the prevalence of osteolysis after conventional and high-flexion TKAs in the same patients.MethodsThe authors evaluated a cohort of 1206 patients with a mean age of 65.3 ± 7 years (range: 22-70) who underwent bilateral simultaneous sequential TKAs. One knee received a conventional TKA and the other received a high-flexion TKA. The mean duration of follow-up was 15.6 years (range: 14-17).ResultsNo significant differences were found between the 2 groups at the latest follow-up with respect to Knee Society score (93 vs 92 points, P = .765), pain score (45 vs 44 points, P = .641), range of knee motion (125° vs 126°, P = .712), and radiographic and computed tomography scan results. Furthermore, no significant revision rate differences were found between the 2 groups (1.3% for conventional TKA vs 1.6% for high-flexion TKA; P = .137). There was no osteolysis recorded in either group. The rate of survivorship free of implant revision or aseptic loosening was 98.7% (95% CI = 91-100) for conventional TKA and 98.4% (95% CI = 91-100) for high-flexion TKA at 17 years.ConclusionAt the latest follow-up, we were not able to demonstrate any significant difference between conventional and high-flexion TKAs with respect to functional outcome scores, range of knee motion, revision rate, implant survival, and prevalence of osteolysis.     

Differences in Pain,Opioid Use,and Function Following Unicompartmental Knee Arthroplasty compared to Total Knee Arthroplasty

BackgroundWe sought to determine if immediate postsurgical pain, opioid use, and clinical function differed between unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA).MethodsA single-institution database was utilized to identify patients who underwent elective total joint arthroplasty between 2016 and 2019.ResultsIn total, 6616 patients were identified: 98.20% TKA (6497) and 1.80% (119) UKA. UKA patients were younger, had lower body mass index, and more often male than the TKA cohort. Aggregate opioid consumption (75.94 morphine milligram equivalents vs 136.5 morphine milligram equivalents; P < .001) along with the first 24-hour and 48-hour usage was significantly less for UKA as compared to TKA. Similarly, pain scores (1.98 vs 2.58; P < .001) were lower for UKA while Activity Measure for Post-Acute Care mobilization scores were higher (21.02 vs 18.76; P < .001). UKA patients were able to be discharged home on the day of surgery 37% of the time as compared to 2.45% of TKA patients (P < .0001). Notably, when comparing UKA and TKA patients who were discharged home on the day of surgery, no differences regarding pain scores, opioid utilization, or mobilization were observed.ConclusionUKA patients are younger, have lower body mass index and American Society of Anesthesiologists scores, and more often male than TKA patients. UKA patients had significantly shorter length of stay than TKA patients and were discharged home more often than TKA patients, on both the day of surgery and following hospital admission. Most notably, UKA patients reported lower pain scores and were found to require 45% lower opioid medication in the immediate postsurgical period than TKA patients. Surprisingly, UKA and TKA patients discharged on the day of surgery did not differ in terms of pain scores, opioid utilization, or mobilization, suggesting that our rapid rehabilitation UKA protocols can be successfully translated to outpatient TKAs with similar outcomes.Level III EvidenceRetrospective Cohort Study.     

Preoperative Diagnosis Can Predict Conversion Total Knee Arthroplasty Outcomes

Background

Compared to total knee arthroplasty (TKA) for primary osteoarthritis, conversion TKAs in the post-traumatic setting are associated with increased operative times, infection rates, and readmissions. We aim at determining how post-traumatic osteoarthritis and previous knee surgery influence postoperative outcomes in conversion TKA.

Anterior Knee Pain Following Primary Unilateral Total Knee Arthroplasty With Posterior-Stabilized Prosthesis and Patellar Resurfacing: Prevalence and Clinical Implications

BackgroundAnterior knee pain following total knee arthroplasty (TKA) is associated with patient dissatisfaction. Factors related to postoperative anterior knee pain and its impact on patient outcomes are poorly understood. The following are the aims of this study: (1) to report the prevalence of anterior knee pain before and after TKA using a posterior-stabilized prosthesis with routine patellar resurfacing; (2) to investigate the association of preoperative clinical factors with the presence of anterior knee pain after TKA; and (3) to explore the association of postoperative anterior knee pain with postoperative self-reported function and quality of life.MethodsThis retrospective study included 506 patients who had undergone elective primary unilateral TKA with a posterior-stabilized prosthesis and patellar resurfacing. Outcome measures prior to and 12 months after TKA included self-reported anterior knee pain, knee function, and quality of life.ResultsPrevalence of anterior knee pain was 72% prior to and 15% following TKA. Patients who had preoperative anterior knee pain had twice the risk of experiencing anterior knee pain after TKA than patients who did not have preoperative anterior knee pain (risk ratio: 2.37, 95% CI 1.73-2.96). Greater severity of preoperative anterior knee pain and worse self-reported function were associated with the presence of postoperative anterior knee pain (rho = 0.15, P < .01; rho = 0.13, P < .01, respectively). Preoperative age, gender, and quality of life were not associated with postoperative anterior knee pain. Greater severity of postoperative anterior knee pain was associated with worse knee function at 12 months postoperative (rho = 0.49, P < .01).ConclusionOne in 7 patients reported anterior knee pain 12 months following posterior-stabilized and patella-resurfaced TKA. The presence of preoperative anterior knee pain and worse self-reported function are associated with postoperative anterior knee pain.     

Comparison of Cruciate-Sacrificing vs Posterior-Stabilized Total Knee Replacement Using a Contemporary Total Knee System

BackgroundThe use of highly conforming polyethylene tibial inserts in cruciate-retaining total knee arthroplasty (TKA) often requires posterior cruciate ligament (PCL) release/sacrifice for balancing (CS TKA). The CS TKA relies on the posterior capsule, collateral ligaments, and articular conformity without a cam or post to achieve stability. Using prospectively collected data we compared clinical outcomes of CS TKA to posterior-stabilized (PS) TKA utilizing a contemporary TKA system.MethodsSixty-nine consecutive CS TKAs were compared to 45 consecutive PS TKAs at 2-year minimum follow-up. CS knees were balanced with the PCL released. Preoperative/postoperative range of motion (ROM), Knee Society Scores (KSS), stair function, and squatting ROM were analyzed.ResultsAt minimum 2-year follow up, CS and PS TKA demonstrated significant improvement in ROM (P < .001), KSS (Pain, P < .001; Function, P < .001), and KSS stair function (P < .001), with no revisions. There was no difference in preoperative to postoperative improvements for passive knee ROM (10° (0°-20°) vs 13° (5°-25°); P = .16), KSS Pain (34 (21-42) vs 38 (24-46); P = .22), KSS Function (35 (30-50) vs 35 (18-50); P = .34), and KSS stair function (10 (10-20) vs 10 (0-20); P = .37) for CS and PS TKA, respectively. CS TKA had higher squatting ROM (P = .02) at minimum 2-year follow-up compared to PS TKA.ConclusionBoth PS and CS TKA provided significant improvement in clinical outcomes, with no differences in passive ROM, KSS, or stair function postoperatively. Our data support that with proper articular conformity and balancing, cruciate-retaining TKA in a PCL-deficient knee (CS TKA) is appropriate. This may be design specific and further prospective randomized studies are needed to corroborate these findings.     

Clinical Outcomes of a Modern Total Knee Arthroplasty Prosthesis Compared to Its Predecessor at 5-Year Follow-Up: Matched Pair Analysis

BackgroundResidual pain is an important cause of patient dissatisfaction after total knee arthroplasty (TKA). A recent study at our institution found that a modern prosthesis was associated with less residual and anterior knee pain at 2-year follow-up when compared to its predecessor. The aim of this study is to evaluate these implants at 5-year follow-up.MethodsFrom July 2012 to December 2013, 100 consecutive modern TKAs were identified from our prospective Institutional Review Board approved database. All patients with 5-year clinical follow-up (n = 77) were matched in a one-to-one fashion based on age, gender, body mass index, and follow-up with a predecessor TKA. Clinical outcomes were assessed with a patient-administered questionnaire for specifically anterior knee pain, painless noise, painful crepitation, and satisfaction. Overall function was assessed using Knee Society Scores and Western Ontario and McMaster University Osteoarthritis Index.ResultsAt 5-year follow-up, there were no significant differences between the modern TKA and a predecessor TKA in the Knee Society pain or function scores (P = .24 and P = .54, respectively). The overall prevalence of residual pain was less with the modern TKA compared to its predecessor (19.5% vs 36.3%; P = .02), but the prevalence of isolated anterior knee pain was similar in both cohorts (11.7% vs 22.1%; P = .09). There was no difference in painless noise (19.5% vs 13.3%; P = .28) or satisfaction scores (7.9 ± 2.4 vs 7.6 ± 2.6; P = .25) between the modern and predecessor cohorts.ConclusionAt 5-year follow-up, we found that both the modern and predecessor prostheses provided excellent clinical outcomes. The modern TKA was associated with less residual pain compared to its predecessor, but we were unable to detect differences in the prevalence of isolated anterior knee pain, painless noise, Knee Society Scores, or radiographic evaluation.     

Effects of the Obesity Epidemic on Total Hip and Knee Arthroplasty Demographics

BackgroundHigher body mass index (BMI) is a well-known risk factor for the development of hip and knee osteoarthritis and predicts total hip arthroplasty (THA) and total knee arthroplasty (TKA) at an earlier age. The purpose of this study is to document the nationwide trends in age and obesity in primary THA and TKA throughout the obesity epidemic.MethodsA retrospective analysis of the National Inpatient Sample database was conducted on patients undergoing primary THA and TKA for primary OA between 2002 and 2017. Analysis of variance and chi-square tests were performed to examine changes in age and obesity percentage over time, respectively. Pearson correlations were used to assess the relationship between patient age, BMI, and year of surgery.ResultsA total of 688,371 THA and 1,556,651 TKA were identified over the sixteen-year period. Between 2002 and 2017, the proportion of obese patients increased for both THA (7.0% to 22.7%, P < .001) and TKA (10.7% to 30.4%, P < .001). Mean age significantly decreased for both THA (66.7 to 65.9 years, P < .001) and TKA (67.6 to 66.8 years; P < .001). Over time, BMI significantly increased (THA: r = 0.221 vs. TKA: r = 0.272) and patient age decreased (THA: r = -0.031 vs. TKA: r = -0.137) for both procedures (P < .001 for all).ConclusionTHA and TKA patients have become younger and increasingly more obese throughout the obesity epidemic, as obesity rates have tripled over this time period. The current investigation is the first to demonstrate significant trends in both age and obesity in the THA and TKA populations on a national level.Level of EvidenceIII.     

The Effect of Polyethylene Liner Thickness on Patient Outcomes and Failure After Primary Total Knee Arthroplasty

BackgroundThe effect of using thicker liners in primary total knee arthroplasty (TKA) on functional outcomes and aseptic failure rates remains largely unknown. As such, we devised a multicenter study to assess both the clinical outcomes and survivorship of thick vs thin liners after primary TKA.MethodsA search of our institutional databases was performed for patients having undergone bilateral (simultaneous or staged) primary TKA with similar preoperative and surgical characteristics between both sides. Two cohorts were created: thick liners and thin liners. Outcomes collected were as follows: change in Knee Society Score (ΔKSS), change in range of motion, and aseptic revision. Ad hoc power analysis was performed for ΔKSS (⍺ = 0.05; power = 80%). Differences between cohorts were assessed.ResultsAbout 195 TKAs were identified for each cohort. ΔKSS and change in range of motion in the thin vs thick cohorts were similar: 51.4 vs 51.6 (P = .86) and 11.1° vs 10.0° (P = .66), respectively. No difference in aseptic revision rates were observed between thin and thick cohorts: all cause (4.1%, 3.1%; P = .59), aseptic loosening (0.5%, 0.5%; P = 1.0), instability (0.5%, 0.5%; P = 1.0), all-cause revision for stiffness (3.1%, 2.1%; P = .52), manipulation under anesthesia (2.1%, 2.1%; P = 1.0), and liner exchange (0.5%, 0%; P = .32).ConclusionThe results of this study suggest that both rates of revision surgery and clinical outcomes are similar for TKAs performed with thick and thin liners. Preoperative factors are likely to play an important role in liner thickness selection, and emphasis should be placed on ensuring sound surgical technique.     

High-Quality Skilled Nursing Facilities Are Associated With Decreased Episode-of-Care Costs Following Total Hip and Knee Arthroplasty

BackgroundWith the increasing popularity of alternative payment models following total hip (THA) and knee arthroplasty (TKA), efforts have focused on reducing post-acute care (PAC) costs, particularly patients discharged to skilled nursing facilities (SNFs). The purpose of this study is to determine if preferentially discharging patients to high-quality SNFs can reduce bundled payment costs for primary THA and TKA.MethodsAt our institution, a quality improvement initiative for SNFs was implemented at the start of 2017, preferentially discharging patients to internally credentialed facilities, designated by several quality measures. Claims data from Centers for Medicare and Medicaid Services were queried to identify patients discharged to SNF following primary total joint arthroplasty. We compared costs and outcomes between patients discharged to credentialed SNF sites and those discharged to other sites.ResultsBetween 2015 and 2018, of a consecutive series of 8778 primary THA and TKA patients, 1284 (14.6%) were discharged to an SNF. Following initiation of the program, 498 patients were discharged to an SNF, 301 (60.4%) of which were sent to a credentialed facility. Patients at credentialed facilities had significantly lower SNF costs ($11,184 vs $8198, P < .0001), PAC costs ($18,952 vs $15,148, P < .0001), and episode-of-care costs ($34,557 vs $30,831, P < .0001), with no difference in readmissions (10% vs 12%, P = .33) or complications (8% vs 6%, P = .15). Controlling for confounding variables, being discharged to a credentialed facility decreased SNF costs by $1961 (P = .0020) and PAC costs by $3126 (P = .0031) per patient.ConclusionQuality improvement efforts through partnership with selective SNFs can significantly decrease PAC costs for patients undergoing primary THA and TKA.     

A Prospective Randomized Controlled Trial Comparing Medial-Pivot versus Posterior-Stabilized Total Knee Arthroplasty

BackgroundThe medial-pivot (MP) design for total knee arthroplasty (TKA) aims to restore more natural “ball-and-socket” knee kinematics compared to the traditional posterior-stabilized (PS) implants for TKA. The objective of this study is to determine if there was any difference in functional outcomes between patients undergoing MP-TKA vs PS-TKA.MethodsThis prospective randomized controlled trial consisted of 43 patients undergoing MP-TKA vs 45 patients receiving a single-radius PS-TKA design. The primary outcome was postoperative range of motion (ROM). Secondary outcomes included the Western Ontario and McMaster Universities Arthritis Index, Oxford Knee Score, Knee Society Score (KSS), and radiological outcomes. All study patients were followed-up for 2 years after surgery.ResultsPatients undergoing MP-TKA had comparable ROM at 1 year (114.6° ± 16.3° vs 111.3° ± 17.8° respectively, P = .88) and 2 years after surgery (114.9° ± 15.5° vs 114.9° ± 16.4° respectively, P = .92) compared to PS-TKA. There were also no differences in Western Ontario and McMaster Universities Arthritis Index (26.8 ± 19.84 vs 22.0 ± 12.03 respectively, P = .14), Oxford Knee Score (42.7 ± 8.1 vs 42.3 ± 6.7 respectively, P = .18), KSS clinical scores (82.9 ± 16.96 vs 81.42 ± 10.45 respectively, P = .12) and KSS functional scores (76.2 ± 18.81 vs 73.93 ± 8.53 respectively, P = .62) at 2-year follow-up. There was no difference in postoperative limb alignment or complications.ConclusionThis study demonstrated excellent results in both the single-radius PS-TKA design and MP-TKA design. No differences were identified at 2-year follow-up with respect to postoperative ROM and patient-reported outcome measures.