Current Insights in the Evaluation and Treatment of Infected Total Knee Arthroplasty.

Total knee arthroplasty is a widely successful procedure, but a small percentage of patients have a postoperative course complicated by periprosthetic joint infection (PJI). PJI is a difficult problem to diagnose and to treat, and the management of PJI differs, depending on the acuity of the infection. This paper discusses the established and newer technologies developed for the diagnosis of PJI as well as different treatment considerations and surgical solutions currently available.

What is the Level of Evidence Substantiating Commercial Payers' Coverage Policies for Total Joint Arthroplasty?

BACKGROUND: The prevalence of total joint arthroplasty (TJA) in the United States has drawn the attention of health care stakeholders. The payers have also used a variety of strategies to regulate the medical necessity of these procedures. The purpose of this study was to examine the level of evidence of the coverage policies being used by commercial payers in the United States. METHODS: The references of the coverage policies of four commercial insurance companies were reviewed for type of document, level of evidence, applicability to a TJA population, and success of nonoperative treatment in patients with severe degenerative joint disease. RESULTS: 282 documents were reviewed. 45.8% were primary journal articles, 14.2% were level I or II, 41.2% were applicable to patients who were candidates for TJA, and 9.9% discussed the success of nonoperative treatment in patients who would be candidates for TJA. CONCLUSION: Most of the references cited by commercial payers are of a lower level of scientific evidence and not applicable to patients considered to be candidates for TJA. This is relatively uniform across the reviewed payers. The dearth of high-quality literature cited by commercial payers reflects the lack of evidence and difficulty in conducting high level studies on the outcomes of nonoperative versus operative treatment for patients with severe, symptomatic osteoarthritis. Patients, surgeons, and payers would all benefit from such studies and we encourage professional societies to strive toward that end through multicenter collaboration.

Resorbable Pins to Enhance Scaffold Retention in a Porcine Chondral Defect Model.

OBJECTIVE: Cartilage repair strategies have seen improvement in recent years, especially with the use of scaffolds that serve as a template for cartilage formation. However, current fixation strategies are inconsistent with regards to retention, may be technically challenging, or may damage adjacent tissues or the implant itself. Therefore, the goal of this study was to evaluate the retention and repair potential of cartilage scaffolds fixed with an easy-to-implement bioresorbable pin. DESIGN: Electrospun hyaluronic acid scaffolds were implanted into trochlear groove defects in 3 juvenile and 3 adult pigs to evaluate short-term retention (2 weeks; pin fixation vs. press-fit and fibrin fixation) and long-term repair (8 months; scaffold vs. microfracture), respectively. RESULTS: For the retention study, press-fit and fibrin fixation resulted in short-term scaffold dislodgment (n = 2 each), whereas pin fixation retained all scaffolds that were implanted (n = 6). Pin fixation did not cause any damage to the opposing patellar surface, and only minor changes in the subchondral bone were observed. For long-term repair, no differences were observed between microfracture and scaffold groups, in terms of second-look arthroscopy and indentation testing. On closer visualization with micro computed tomography and histology, a high degree of variability was observed between animals with regard to subchondral bone changes and cartilage repair quality, yet each Scaffold repair displayed similar properties to its matched microfracture control. CONCLUSIONS: In this study, pin fixation did not cause adverse events in either the short- or the long-term relative to controls, indicating that pin fixation successfully retained scaffolds within defects without inhibiting repair.

Lower Extremity Total Joint Arthroplasty Has Minimal Effect on Golf Handicap.

Although the vast majority of arthroplasty surgeons allow patients to return to participation in golf following total knee arthroplasty (TKA) and total hip arthroplasty (THA), there is relatively little published data regarding how TKA or THA affects a patient's golfing ability. The purpose of this study was to determine how golfers' handicaps change following TKA and THA. We mailed a questionnaire to patients who had underwent primary TKA or THA at our institution and asked whether they played golf and for their golf handicap information network (GHIN) number. We then obtained handicap data for each patient that provided a GHIN number. Handicap increased 0.9 strokes 1 year following THA; however, this difference was not statistically significant (p = 0.20). Handicap increased 0.3 strokes 1 year following TKA; however, this difference was not statistically significant (p = 0.29). Our study demonstrates that despite improved implants, surgical techniques, and rehabilitation protocols that golf handicap does not change significantly following lower extremity total joint arthroplasty (TJA). (Journal of Surgical Orthopaedic Advances 29(4):216-218, 2020).

Can an arthroplasty risk score predict bundled care events after total joint arthroplasty?

BACKGROUND: The validated Arthroplasty Risk Score (ARS) predicts the need for postoperative triage to an intensive care setting. We hypothesized that the ARS may also predict hospital length of stay (LOS), discharge disposition, and episode-of-care cost (EOCC). METHODS: We retrospectively reviewed a series of 704 patients undergoing primary total hip and knee arthroplasty over 17 months. Patient characteristics, 90-day EOCC, LOS, and readmission rates were compared before and after ARS implementation. RESULTS: ARS implementation was associated with fewer patients going to a skilled nursing or rehabilitation facility after discharge (63% vs 74%, P = .002). There was no difference in LOS, EOCC, readmission rates, or complications. While the adoption of the ARS did not change the mean EOCC, ARS >3 was predictive of high EOCC outlier (odds ratio 2.65, 95% confidence interval 1.40-5.01, P = .003). Increased ARS correlated with increased EOCC (P = .003). CONCLUSIONS: Implementation of the ARS was associated with increased disposition to home. It was predictive of high EOCC and should be considered in risk adjustment variables in alternative payment models.

Diagnosing Infection in Patients Undergoing Conversion of Prior Internal Fixation to Total Hip Arthroplasty.

BACKGROUND: Criteria for diagnosis of infected internal fixation implants at the time of conversion to total hip arthroplasty (THA) are not clear. The purpose of this study is to identify risk factors for infection in patients undergoing conversion to THA. METHODS: We retrospectively reviewed patients at a single institution who underwent conversion to THA from 2009 to 2014. Patients were diagnosed with infection preoperatively using Musculoskeletal Infection Society criteria or postoperatively if they were found to have positive cultures intraoperatively at the time of conversion surgery. Medical comorbidities and preoperative inflammatory markers were compared between infected and noninfected groups. Univariate and multivariate logistic regression analysis were performed to identify independent risk factors for infection. Receiver operating characteristic curves were generated to determine test performance of erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). A post hoc power analysis was performed. RESULTS: Thirty-three patients were included in the study. Six patients (18%) were diagnosed with infection. We found no association between comorbidities and infection in this cohort. The mean ESR and CRP were higher in infected (ESR = 41.6 mm/h, CRP = 2.0 mg/dL) vs noninfected (ESR = 19.3 mm/h, CRP = 1.3 mg/dL) groups (both P < .01). ESR >30 mm/h (odds ratio 28.8, 95% confidence interval 2.6-315.4, P = .001) and CRP >1.0 mg/dL (odds ratio 11.5, 95% confidence interval 1.6-85.2, P = .01) were strongly associated with infection. Receiver operating characteristic curves for ESR (area under the curve [AUC] = 0.89) and CRP (AUC = 0.89) demonstrated good fit. CONCLUSION: We report a high incidence of infection in patients who underwent conversion to THA. Preoperative ESR and CRP are effective screening tools though occult infections may still be missed. Patients with borderline or elevated inflammatory markers should raise strong suspicion for infection.

Are Bundled Payments a Viable Reimbursement Model for Revision Total Joint Arthroplasty?

BACKGROUND: Alternative payment models, such as the Centers for Medicare & Medicaid Services (CMS) Bundled Payment for Care Improvement (BPCI) initiative, aim to decrease overall costs for hip and knee arthroplasties. QUESTIONS/PURPOSES: We asked: (1) Is there any difference in the CMS episode-of-care costs, hospital length of stay, and readmission rate from before and after implementation of our bundled-payment program? (2) Is there any difference in reimbursements and resource utilization between revision THA and TKA at our institution? (3) Are there any independent risk factors for patients with high costs who may not be appropriate for a bundled-payment system for revision total joint arthroplasty (TJA)? METHODS: Between October 2013 and March 2015, 218 patients underwent revision TKA or THA in one health system. Two hundred seventeen patients were reviewed as part of this study, and one patient with hemophilia was excluded from the analysis as an outlier. Our institution began a BPCI program for revision TJA during this study period. Patients' procedures done before January 1, 2014 at one hospital and January 1, 2015 at another hospital were not included in the bundled-care arrangement (70 revision TKAs and 56 revision THAs), whereas 50 revision TKAs and 41 revision THAs were performed under the BPCI initiative. Patient demographics, medical comorbidities, episode-of-care reimbursement data derived directly from CMS, length of stay, and readmission proportions were compared between the bundled and nonbundled groups. RESULTS: Length of stay in the group that underwent surgery before the bundled-care arrangement was longer than for patients whose procedures were done under the BPCI (mean 4.02 [SD, 3.0 days] versus mean 5.27 days [SD, 3.6 days]; p = 0.001). Index hospitalization reimbursement for the bundled group was less than for the nonbundled group (mean USD 17,754 [SD, USD 2741] versus mean USD 18,316 [SD, USD 4732]; p = 0.030). There was no difference, with the numbers available, in total episode-of-care CMS costs between the two groups (mean USD 38,107 [SD, USD 18,328] versus mean USD 37,851 [SD, USD 17,208]; p = 0.984). There was no difference, with the numbers available, in the total episode-of-care CMS costs between revision hip arthroplasties and revision knee arthroplasties (mean USD 38,627 [SD, USD 18,607] versus mean USD 37,414 [SD, USD 16,884]; p = 0.904). Disposition to rehabilitation (odds ratio [OR], 5.49; 95% CI, 1.97-15.15; p = 0.001), length of stay 4 days or greater (OR, 3.66; 95% CI, 1.60-8.38; p = 0.002), and readmission within 90 days (OR, 6.99; 95% CI, 2.58-18.91; p < 0.001) were independent risk factors for high-cost episodes. CONCLUSIONS: Bundled payments have the potential to be a viable reimbursement model for revision TJA. Owing to the unpredictable nature of the surgical procedures, inherent high risks of complications, and varying degrees of surgical complexity, future studies are needed to determine whether bundling patients having revision TJA will result in improved care and decreased costs. LEVEL OF EVIDENCE: Level IV, economic and decision analysis.

Chronic diet-induced hyperhomocysteinemia impairs eNOS regulation in mouse mesenteric arteries.

Hyperhomocysteinemia (HHcy) impairs endothelium-dependent vasodilation by increasing reactive oxygen species, thereby reducing nitric oxide (NO.) bioavailability. It is unclear whether reduced expression or function of the enzyme that produces NO., endothelial nitric oxide synthase (eNOS), also contributes. It is also unclear whether resistance vessels that utilize both NO.and non-NO.vasodilatory mechanisms, undergo alteration of non-NO.mechanisms in this condition. We tested these hypotheses in male C57BL/6 mice with chronic HHcy induced by 6-wk high methionine/low-B vitamin feeding (Hcy: 89.2 +/- 49.0 microM) compared with age-matched controls (Hcy: 6.6 +/- 1.9 microM), using first-order mesenteric arteries. Dilation to ACh (10(-9)-10(-4) M) was measured in isolated, cannulated, and pressurized (75 mmHg) arteries with and without N(G)-nitro-l-arginine methyl ester (l-NAME) (10(-4) M) and/or indomethacin (10(-5) M) to test endothelium-dependent dilation and non-NO.-dependent dilation, respectively. The time course of dilation to ACh (10(-4) M) was examined to compare the initial transient dilation due to non-NO., non-prostacyclin mechanism and the sustained dilation due to NO.. These experiments indicated that endothelium-dependent dilation was attenuated (P < 0.05) in HHcy arteries due to downregulation of only NO.-dependent dilation. Western blot analysis indicated significantly less (P < 0.05) basal eNOS and phospho-S1179-eNOS/eNOS in mesenteric arteries from HHcy mice but no difference in phospho-T495-eNOS/eNOS. S1179 eNOS phosphorylation was also significantly less in these arteries when stimulated with ACh ex vivo or in situ. Real-time PCR indicated no difference in eNOS mRNA levels. In conclusion, chronic diet-induced HHcy in mice impairs eNOS protein expression and phosphorylation at S1179, coincident with impaired NO.-dependent dilation, which implicates dysfunction in eNOS post-transcriptional regulation in the impaired endothelium-dependent vasodilation and microvascular disease that is common with HHcy.

Age-related changes in conducted vasodilation: effects of exercise training and role in functional hyperemia.

Conducted vasodilation may coordinate blood flow in microvascular networks during skeletal muscle contraction. We tested the hypotheses that 1) exercise training enhances conducted vasodilation and 2) age-related changes in the capacity for conduction affect muscle perfusion during contractions. To address hypothesis 1, young (4-5 mo), adult (12-14 mo), and old (19-21 mo) C57BL6 male mice were sedentary or given access to running wheels for 8 wk. Voluntary running distances were significantly different (in km/day): young = 5.8 +/- 0.1, adult = 3.9 +/- 0.1, old = 2.2 +/- 0.1 (P < 0.05). In gluteus maximus muscles, conducted vasodilation was greater in adult than in young or old mice (P < 0.05) and greater in young sedentary than in old sedentary mice but was not affected by exercise training. Citrate synthase activity was greater with exercise training at all ages (P < 0.05). mRNA for endothelial nitric oxide synthase did not differ among ages, but endothelial nitric oxide synthase protein expression was greater in adult and old mice with exercise training (P < 0.05). Connexin 37, connexin 40, and connexin 43 mRNA were not affected by exercise training and did not differ by age. To address hypothesis 2, perfusion of the gluteus maximus muscle during light to severe workloads was assessed by Doppler microprobe at 3-26 mo of age. Maximum perfusion decreased linearly across the lifespan. Perfusion at the highest workload, absolute and relative to maximum, decreased across the lifespan, with a steeper decline beyond approximately 20 mo of age. In this model, 1) exercise training does not alter conducted vasodilation and 2) muscle perfusion is maintained up to near maximum workloads despite age-related changes in conducted vasodilation.