The Efficacy and Safety of Opioids in Total Joint Arthroplasty: Systematic Review and Direct Meta-Analysis

How-To Create an Orthopaedic Systematic Review: A Step-by-Step Guide Part I: Study Design

Systematic reviews are conducted through a consistent and reproducible method to search, appraise, and summarize information. Within the evidence-based pyramid, systematic reviews can be at the apex when incorporating high-quality studies, presenting the strongest form of evidence given their synthesis of results from multiple primary studies to level IV evidence, depending on the studies they incorporate. When combined and supplemented with a meta-analysis using statistical methods to pool the results of 3 or more studies, systematic reviews are powerful tools to help answer research questions. The aim of this review is to serve as a guide on how to: (1) design; (2) execute; and (3) publish an orthopaedic arthroplasty systematic review and meta-analysis. In Part I, we discuss how to develop an appropriate research question as well as source and screen databases. To date, commonly used databases to source studies include PubMed/MEDLINE, Embase, Cochrane Library, Scopus, and Web of Science. Although not all-encompassing, this paper serves as a starting point for those interested in performing and/or critically reviewing lower extremity arthroplasty systematic reviews and meta-analyses.

Comparative safety of tramadol and other opioids following total hip and knee arthroplasty

BACKGROUND

Tramadol is increasingly used to treat acute postoperative pain among older adults following total hip and knee arthroplasty (THA/TKA). However, tramadol has a complex pharmacology and may be no safer than full opioid agonists. We compared the safety of tramadol, oxycodone, and hydrocodone among opioid-naïve older adults following elective THA/TKA.

METHODS

This retrospective cohort included Medicare Fee-for-Service beneficiaries ≥ 65 years with elective THA/TKA between January 1, 2010 and September 30, 2015, 12 months of continuous Parts A and B enrollment, 6 months of continuous Part D enrollment, and no opioid use in the 6 months prior to THA/TKA. Participants initiated single-opioid therapy with tramadol, oxycodone, or hydrocodone within 7 days of discharge from THA/TKA hospitalization, regardless of concurrently administered nonopioid analgesics. Outcomes of interest included all-cause hospitalizations or emergency department visits (serious adverse events (SAEs)) and a composite of 10 surgical- and opioid-related SAEs within 90-days of THA/TKA. The intention-to-treat (ITT) and per-protocol (PP) hazard ratios (HRs) for tramadol versus other opioids were estimated using inverse-probability-of-treatment-weighted pooled logistic regression models.

RESULTS

The study population included 2,697 tramadol, 11,407 oxycodone, and 14,665 hydrocodone initiators. Compared to oxycodone, tramadol increased the rate of all-cause SAEs in ITT analyses only (ITT HR 1.19, 95%CLs, 1.02, 1.41; PP HR 1.05, 95%CLs, 0.86, 1.29). Rates of composite SAEs were not significant across comparisons. Compared to hydrocodone, tramadol increased the rate of all-cause SAEs in the ITT and PP analyses (ITT HR 1.40, 95%CLs, 1.10, 1.76; PP HR 1.34, 95%CLs, 1.03, 1.75), but rates of composite SAEs were not significant across comparisons.

CONCLUSIONS

Postoperative tramadol was associated with increased rates of all-cause SAEs, but not composite SAEs, compared to oxycodone and hydrocodone. Tramadol does not appear to have a superior safety profile and should not be preferentially prescribed to opioid-naïve older adults following THA/TKA.

How-To Create an Orthopaedic Systematic Review: A Step-by-Step Guide. Part III: Executing a Meta-Analysis

At the top of the evidence-based pyramid, systematic reviews stand out as the most powerful, synthesizing findings from numerous primary studies. Specifically, a quantitative systematic review, known as a meta-analysis, combines results from various studies to address a specific research question. This review serves as a guide on how to: (1) design; (2) perform; and (3) publish an orthopedic arthroplasty systematic review. In Part III, we focus on how to design and perform a meta-analysis. We delineate the advantages and disadvantages of meta-analyses compared to systematic reviews, acknowledging their potential challenges due to time constraints and the complexities posed by study heterogeneity and data availability. Despite these obstacles, a well-executed meta-analysis contributes precision and heightened statistical power, standing at the apex of the evidence-based pyramid. The design of a meta-analysis closely mirrors that of a systematic review, but necessitates the inclusion of effect sizes, variability measures, sample sizes, outcome measures, and overall study characteristics. Effective data presentation involves the use of forest plots, along with analyses for heterogeneities and subgroups. Widely-used software tools are common in this domain, and there is a growing trend toward incorporating artificial intelligence software. Ultimately, the intention is for these papers to act as foundational resources for individuals interested in conducting systematic reviews and meta-analyses in the context of orthopaedic arthroplasty, where applicable.

Correlation of Patient-Reported Preoperative Narcotic Use and Postoperative Requirements in Total Joint Arthroplasty

Preoperative narcotic use is associated with diminished outcomes and increased complications in patients undergoing primary total joint arthroplasty (TJA). The goal of this study was to compare self-reported and state database identified preoperative narcotic use and correlate it with perioperative narcotic requirements in patients undergoing primary arthroplasty. A total of 788 patients undergoing unilateral TJA from a single institution were examined using self-reported preoperative narcotic use questionnaires and were verified using the Massachusetts Prescriber Awareness Tool (MassPAT). Demographic data, perioperative morphine milligram equivalents, and postdischarge refills were recorded and analyzed. Of the total population, 16.4% of patients undergoing TJA had verified MassPAT narcotics prescriptions preoperatively. Of these patients, 55% accurately reported use to their surgeon. Patients with verified MassPAT narcotic prescriptions required more morphine milligram equivalents than patients without MassPAT prescriptions, regardless of their preoperative self-report at all time points in the study. Patients who accurately reported use required more narcotics than those who did not. Patients with MassPAT prescriptions required more postdischarge refills than patients without MassPAT prescriptions. These data suggest that state-run narcotics databases may be more useful than self-reports for identifying which patients may require more opioids both immediately postoperatively and after hospital discharge. [Orthopedics. 2024;47(1):34-39.].

Successful implementation of a quality improvement bundle to reduce opioid overprescribing following total hip and knee arthroplasty

BACKGROUND

Opioid overprescribing is commonplace after total hip (THA) and total knee arthroplasty (TKA). Preliminary data demonstrated that approximately 32% of the opioids prescribed at discharge from our hospital following THA and TKA remain unused. This is a concern given that unused prescribed opioids are available for diversion and may result in misuse and abuse.

METHODS

Pre-intervention data were collected between 1 November 2018 and 10 December 2018. An intervention bundle was then introduced, including education of patients and providers, a standardised pain management algorithm and an autopopulated discharge prescription. The aim of this quality improvement initiative was to reduce the amount of opioid (average oral morphine equivalents (OME)) dispensed (based on the discharge prescription provided) following THA and TKA at our institution by 15% by 1 April 2019.

DESIGN

Using an interrupted time series design, the outcome measure was the amount of opioid (OME) dispensed from the discharge prescription provided. Process measures included the percentage of autopopulated discharge prescriptions, the percentage of patients receiving education at discharge and the percentage of nurses and residents receiving standardised education. Balancing measures included patient satisfaction with postoperative pain management, and the percentage of patients filling the second half of the part-fill or requiring a subsequent opioid prescription.

RESULTS

With 600 patients identified, mean OME dispensed at discharge was reduced by 26.3% (from 522.2 to 384.9 mg) after our interventions started. Utilisation of autopopulated part-fill prescriptions was 95.8%. There was no change in patient satisfaction nor in the proportion of patients requiring an additional opioid prescription post-intervention. Only 39% of patients filled the second half of the part-fill prescription post-intervention.

CONCLUSIONS

Mean OME dispensed at discharge per patient was reduced with no change in patient satisfaction after introduction of the intervention bundle.

Analgesic efficacy of anterior iliopsoas muscle space block combined with local infiltration analgesia after total hip arthroplasty: A prospective, double-blind, placebo-controlled study

BACKGROUND

The present study aimed to evaluate the efficacy of ultrasound-guided anterior iliopsoas muscle space block (AIMSB) combined with local infiltration analgesia (LIA) for pain management and recovery in patients who have undergone total hip arthroplasty (THA) via a posterolateral approach.

METHODS

In this prospective, double-blind, placebo-controlled study, 80 patients undergoing primary THA under general anesthesia were included in the final analysis between March 22, 2022, and June 1, 2022. All patients were randomly assigned to receive AIMSB combined with LIA (AIMSB group, n = 40) or sham AIMSB and LIA (Sham group, n = 40). The primary outcome was cumulative morphine consumption (mg) within 24 h after surgery. Secondary outcomes were pain scores on a visual analog scale (VAS) at rest or during motion after surgery, time to first rescue analgesia, cumulative morphine consumption during hospitalization, intraoperative consumption of opioids, postoperative recovery, and postoperative adverse effects.

RESULTS

Patients in the AIMSB group consumed significantly less morphine than the Sham group within the first 24 h and throughout hospitalization, as well as smaller amounts of intraoperative opioids. Also, significantly lower pain scores were recorded at rest or during motion within 24 h after surgery in AIMSB patients. Patients in the AIMSB group recovered more quickly than Sham patients. No significant difference was observed in quadriceps strength and postoperative complications between the two groups.

CONCLUSIONS

Compared to treatment with LIA alone, ultrasound-guided AIMSB combined with LIA can provide better postoperative pain relief, decrease opioid consumption, promote motor sparing, and enhance the recovery of THA patients.

Prognostic Factors for Postoperative Chronic Pain after Knee or Hip Replacement in Patients with Knee or Hip Osteoarthritis: An Umbrella Review

Knee and hip osteoarthritis are highly prevalent in the older population. Management of osteoarthritis-related pain includes conservative or surgical treatment. Although knee or hip joint replacement is associated with positive outcomes, up to 30% of patients report postoperative pain in the first two years. This study aimed to synthesize current evidence on prognostic factors for predicting postoperative pain after knee or hip replacement. An umbrella review of systematic reviews was conducted to summarize the magnitude and quality of the evidence for prognostic preoperative factors predictive of postoperative chronic pain (>6 months after surgery) in patients who had received knee or hip replacement. Searches were conducted in MEDLINE, CINAHL, PubMed, PEDro, SCOPUS, Cochrane Library, and Web of Science databases from inception up to 5 August 2022 for reviews published in the English language. A narrative synthesis, a risk of bias assessment, and an evaluation of the evidence confidence were performed. Eighteen reviews (nine on knee surgery, four on hip replacement, and seven on both hip/knee replacement) were included. From 44 potential preoperative prognostic factors, just 20 were judged as having high or moderate confidence for robust findings. Race, opioid use, preoperative function, neuropathic pain symptoms, pain catastrophizing, anxiety, other pain sites, fear of movement, social support, preoperative pain, mental health, coping strategies, central sensitization-associated symptoms, and depression had high/moderate confidence for an association with postoperative chronic pain. Some comorbidities such as heart disease, stroke, lung disease, nervous system disorders, and poor circulation had high/moderate confidence for no association with postoperative chronic pain. This review has identified multiple preoperative factors (i.e., sociodemographic, clinical, psychological, cognitive) associated with postoperative chronic pain after knee or hip replacement. These factors may be used for identifying individuals at a risk of developing postoperative chronic pain. Further research can investigate the impact of using such prognostic data on treatment decisions and patient outcomes.

Preoperative Versus Perioperative Risk Factors for Delayed Pain and Opioid Cessation After Total Joint Arthroplasty: A Prospective Cohort Study

INTRODUCTION

The evolution of pre- versus postoperative risk factors remains unknown in the development of persistent postoperative pain and opioid use. We identified preoperative versus comprehensive perioperative models of delayed pain and opioid cessation after total joint arthroplasty including time-varying postoperative changes in emotional distress. We hypothesized that time-varying longitudinal measures of postoperative psychological distress, as well as pre- and postoperative use of opioids would be the most significant risk factors for both outcomes.

METHODS

A prospective cohort of 188 patients undergoing total hip or knee arthroplasty at Stanford Hospital completed baseline pain, opioid use, and emotional distress assessments. After surgery, a modified Brief Pain Inventory was assessed daily for 3 months, weekly thereafter up to 6 months, and monthly thereafter up to 1 year. Emotional distress and pain catastrophizing were assessed weekly to 6 months, then monthly thereafter. Stepwise multivariate time-varying Cox regression modeled preoperative variables alone, followed by all perioperative variables (before and after surgery) with time to postoperative opioid and pain cessation.

RESULTS

The median time to opioid and pain cessation was 54 and 152 days, respectively. Preoperative total daily oral morphine equivalent use (hazard ratio-HR 0.97; 95% confidence interval-CI 0.96-0.98) was significantly associated with delayed postoperative opioid cessation in the perioperative model. In contrast, time-varying postoperative factors: elevated PROMIS (Patient-Reported Outcomes Measurement Information System) depression scores (HR 0.92; 95% CI 0.87-0.98), and higher Pain Catastrophizing Scale scores (HR 0.85; 95% CI 0.75-0.97) were independently associated with delayed postoperative pain resolution in the perioperative model.

CONCLUSIONS

These findings highlight preoperative opioid use as a key determinant of delayed postoperative opioid cessation, while postoperative elevations in depressive symptoms and pain catastrophizing are associated with persistent pain after total joint arthroplasty providing the rationale for continued risk stratification before and after surgery to identify patients at highest risk for these distinct outcomes. Interventions targeting these perioperative risk factors may prevent prolonged postoperative pain and opioid use.

Management of perioperative pain after TKA

Postoperative pain is the prime obstacle to recovery of motion and return to activity after total knee arthroplasty (TKA). Combating pain is a key point in enhanced recovery after surgery (ERAS) protocols. Outcome depends on the efficacy of pain relief, making it a major issue. The pain originates locally in the knee and also remotely via neural pathways. Regression can be slow, over several months. Pain may sometimes be definitive, to a varying degree. Pain should be managed at each step of ERAS, from the preoperative period to the last follow-up consultation, and most especially during the perioperative phase. Pain needs to be anticipated and limited for as long as necessary. The impact of analgesics should be enhanced by means of potentiators. Some are administered by general route, sometimes preoperatively; others are applied locally, directly in the surgical site by local injection, or close to the nerves, to reduce painful stimuli. The two main principles of pain management are preventive analgesia and multimodal analgesia associating various molecules and routes.

Chronic opioid use before and after exercise therapy and patient education among patients with knee or hip osteoarthritis

OBJECTIVE

To investigate changes in opioid use after supervised exercise therapy and patient education among knee or hip osteoarthritis patients with chronic opioid use.

METHOD

In this cohort study, we linked data from the Good Life with osteoArthritis in Denmark register (GLA:D®; standardised treatment program for osteoarthritis; January 2013 to November 2018) with national health registries. Among 35,549 patients, 1,262 were classified as chronic opioid users based on amount and temporal distribution of dispensed opioids the year before the intervention. We investigated changes in opioid use, measured as mg oral morphine equivalents (OMEQs), from the year before the intervention to the year after using generalized estimating equations.

RESULTS

We found a 10% decrease in mg OMEQs from the year before to the year after the intervention (incidence rate ratio [IRR]: 0.90, 95% confidence interval [CI]: 0.86, 0.94). Additional analyses suggested this decrease to be mainly attributable to regulatory actions targeting opioid prescribing during the study period (IRR among patients participating in the intervention before: 0.98 [95% CI: 0.89, 1.07] vs after: 0.83 [0.74, 0.93] regulatory actions). In a random general population sample of matched chronic opioid users, a similar opioid use pattern was observed over time, further supporting the impact of regulatory actions on the opioid use in the study population.

CONCLUSION

Among patients with knee or hip osteoarthritis and chronic opioid use, a standardised treatment program did not change opioid use when regulatory changes in opioid prescribing were taken into account.

Reduced Narcotic Utilization in Total Joint Arthroplasty Patients in an Urban Tertiary Care Center

Background

Opioid use after total joint arthroplasty must be balanced against the risks of opioid dependence and diversion. This study sought to define the baseline patient characteristics and discharge opioid use after the initiation of a preoperative and postoperative institutional opioid prescription protocol in a population with a high prevalence of opioid dependence and substance use.

Methods

Data on 1004 patients undergoing total joint arthroplasties from July 1, 2017, to June 30, 2019, were retrospectively reviewed. Demographics were collected, and data were grouped into high- and low-discharge opioid groups based on 1 standard deviation above or below the mean. Patient characteristics of the high and low groups were compared using one-way analysis of variance and Pearson chi-square test.

Results

The prevalence of preoperative opioid dependence was 21.8%. The mean discharge opioid prescription was 264 morphine milligram equivalents (MMEs). The cutoffs of high- and low-use groups were above 424 MMEs and below 104.5 MMEs. The high-discharge opioid group was more likely to be male, younger, to have a history of preoperative opioid use, to undergo general anesthesia, and to be uninsured. The lower-discharge opioid group was more likely to be older, female, to have Medicare, and to stay approximately 1 day longer in the hospital. Body mass index, intraoperative opioid requirement, American Society of Anesthesiologists Classification score, race, total knee vs total hip arthroplasty, or surgical approach for total hip arthroplasty did not affect discharge opioid prescriptions.

Conclusions

Reduction of opioid prescriptions at discharge in total joint arthroplasty patients may be possible with the use of preoperative and postoperative protocols, optimizing patient risk factors for opioid use and utilizing a patient-specific opioid taper regimen.

Evaluation of Low-Dose Versus High-Dose Opioid Pathway in Opioid-Naïve Patients After Total Knee Arthroplasty

Background

Pain control after total knee arthroplasty (TKA) remains challenging. Tramadol is a weak opioid with potentially lower side effects and risk for dependency than stronger opioids. The purpose of this study was to evaluate efficacy and safety of tramadol after TKA in opioid-naïve patients compared with stronger opioids.

Methods

A retrospective review of patients who underwent primary TKA was performed. In September 2018, opioid-naïve patients were prescribed tramadol instead of oxycodone. Patients receiving tramadol (low-opioid group) were matched to patients discharged with oxycodone before this transition (high-opioid group). We compared morphine milligram equivalent (MME) consumption and outcomes up to 3 months postoperatively.

Results

Two-hundred and five patients underwent TKA, with 126 receiving tramadol. Fourteen patients were converted to stronger opioid (11.2% conversion rate). Seventy patients from the low-opioid group were matched to 70 patients in the high-opioid group. Average daily inpatient MME consumption was higher in the high-opioid group (40.0 ± 27.4 vs 16.3 ± 10.9, P = .000). Outpatient prescribed MME was significantly higher in the high-opioid group (135.5 ± 71.5 vs 75.3 ± 51.3, P = .000) along with a higher number of refills (0.53 ± 1.1 vs 0.886 ± 0.94, P = .041). Knee range of motion was not statistically different at any timepoint postoperatively. There was higher adverse event rate in the low-opioid group (8.6% vs 5.7%) but not statically significant.

Conclusions

Low opioid regimen following TKA showed lower MME consumption than high opioid regimen with no effect on outcomes up to 3 months. Use of low opioid regimen should be considered for TKA surgery.

Efficacy of Quadratus Lumborum Block for Pain Control in Patients Undergoing Hip Surgeries: A Systematic Review and Meta-Analysis

BACKGROUND

Several studies have reported the use of anterior, posterior and lateral quadratus lumborum block (QLB) for pain control in hip surgeries. However, high-quality evidence is lacking. The current review aimed to summarize data on the efficacy of QLB for pain control in patients undergoing hip surgeries.

METHODS

PubMed, Embase, and Google Scholar databases were searched up to August 5, 2021 for randomized controlled trials (RCTs) or non-RCTs assessing the efficacy of QLB for any type of hip surgery.

RESULTS

Thirteen studies were included (nine RCTs and four non-RCTs). On pooled analysis, there was a statistically significant reduction of 24-h total opioid consumption in patients receiving QLB as compared to the control group (MD: -9.92, 95% CI: -16.35, -3.48 I 2 = 99% p = 0.003). We noted a statistically significant reduction of pain scores in the QLB group as compared to control group at 2-4 h (MD: -0.57, 95% CI: -0.98, -0.17 I 2 = 61% p = 0.005), 6-8 h (MD: -1.45, 95% CI: -2.09, -0.81 I 2 = 86% p < 0.00001), 12 h (MD: -1.12, 95% CI: -1.89, -0.34 I 2 = 93% p = 0.005), 24 h (MD: -0.71, 95% CI: -1.27, -0.15 I 2 = 89% p = 0.01) and 48 h (MD: -0.76, 95% CI: -1.37, -0.16 I 2 = 85% p = 0.01) after the procedure. There was a statistically significant reduction in the risk of nausea/vomiting (RR: 0.40, 95% CI: 0.18, 0.88 I 2 = 62% p = 0.02) in patients receiving QLB but no difference in the risk of pruritis (RR: 0.46, 95% CI: 0.17, 1.24 I 2 = 16% p = 0.13) and urinary retention (RR: 0.44, 95% CI: 0.19, 1.02 I 2 = 0% p = 0.06).

CONCLUSION

QLB as a part of a multimodal analgesic regimen reduces opioid consumption and pain scores in patients undergoing hip surgeries. The certainty of evidence based on GRADE was moderate. Despite the statistically significant results, the clinical relevance of the analgesic efficacy of QLB is debatable due to the small effect size.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero/, identifier: CRD42021267861.

[Opioids in primary total joint arthroplasty: Interpretation of 2020 AAHKS/ASRA/AAOS/THS/TKS clinical practice guidelines]

In 2020, the American Association of Hip and Knee Surgeons (AAHKS), the American Society of Regional Anesthesia and Pain Medicine (ASRA), the American Academy of Orthopaedic Surgeons (AAOS), the American Hip Society (THS), the American Knee Society (TKS) have worked together to develop clinical practice guidelines on the use of Opioids in primary total joint arthroplasty (TJA). This clinical practice guideline formulates recommendations for common and important questions related to the efficacy and safety of Opioids in primary TJA. This article interprets the guideline to help doctors make clinical decisions.

Postoperative outcomes of total knee arthroplasty across varying levels of multimodal pain management protocol adherence

We examined the effect of varying multimodal pain management (MMPM) combinations on oral morphine milligram equivalents (OMME) and length of stay (LOS) after total knee arthroplasty (TKA). Five groups were compared based on the combination of multimodal analgesics ranging from no MMPM to full MMPM with acetaminophen, gabapentinoids, and celecoxib. After risk adjustment, MMPM was associated with decreased odds of LOS ≥2 days and OMME ≥75th percentile. MMPM protocols are effective at reducing LOS and postoperative narcotic requirements post-TKA. Patients appear to derive similar benefit from receiving all three medications, as well as various combinations of these drugs.

Changes in opioid discharge prescriptions after primary total hip and total knee arthroplasty affect opioid refill rates and morphine milligram equivalents : an institutional experience of 20,000 patients

AIMS

Due to the opioid epidemic in the USA, our service progressively decreased the number of opioid tablets prescribed at discharge after primary hip (THA) and knee (TKA) arthroplasty. The goal of this study was to analyze the effect on total morphine milligram equivalents (MMEs) prescribed and post-discharge opioid repeat prescriptions.

METHODS

We retrospectively reviewed 19,428 patients undergoing a primary THA or TKA between 1 February 2016 and 31 December 2019. Two reductions in the number of opioid tablets prescribed at discharge were implemented over this time; as such, we analyzed three periods (P1, P2, and P3) with different routine discharge MME (750, 520, and 320 MMEs, respectively). We investigated 90-day refill rates, refill MMEs, and whether discharge MMEs were associated with represcribing in a multivariate model.

RESULTS

A discharge prescription of < 400 MMEs was not a risk factor for opioid represcribing in the entire population (p = 0.772) or in opioid-naïve patients alone (p = 0.272). Procedure type was the most significant risk factor for narcotic represcribing, with unilateral TKA (hazard ratio (HR) = 5.62), bilateral TKA (HR = 6.32), and bilateral unicompartmental knee arthroplasty (UKA) (HR = 5.29) (all p < 0.001) being the highest risk for refills. For these three procedures, there was approximately a 5% to 6% increase in refills from P1 to P3 (p < 0.001); however, there was no significant increase in refill rates after any hip arthroplasty procedures. Total MMEs prescribed were significantly reduced from P1 to P3 (p < 0.001), leading to the equivalent of nearly 500,000 fewer oxycodone 5 mg tablets prescribed.

CONCLUSION

Decreasing opioids prescribed at discharge led to a statistically significant reduction in total MMEs prescribed. While the represcribing rate did not increase for any hip arthroplasty procedure, the overall refill rates increased by about 5% for most knee arthroplasty procedures. As such, we are now probably prescribing an appropriate amount of opioids at discharge for knee arthroplasty procedure, but further reductions may be possible for hip arthroplasty procedures. Cite this article: Bone Joint J 2021;103-B(7 Supple B):103-110.