Summary Outpatient total knee arthroplasty (TKA) is safe and effective in carefully selected patients Success rates for same-day discharge exceed 90%, with most failures due to non-surgical factors Requires rigorous patient selection and multidisciplinary protocols Outpatient arthroplasty offers significant cost savings while maintaining high patient satisfaction Safety & Outcomes Outpatient TJA complication rates 3-8%, comparable or lower than inpatient setting 30-day readmission rates approximately 2%, similar to inpatient procedures same-day discharge success rates exceed 90% in selected patients no increased risk of reoperation compared to inpatient arthroplasty most complications are wound discharge, urinary retention, and orthostatic hypotension low 30-day complication rates across large cohorts Quality metrics satisfaction rates 98-100% reporting good/great outcomes equivalent to inpatient at all timepoints Patient Selection Inclusion criteria age <75 years preferred ASA classification <3, but controversial primary arthroplasty, although some revisions may be well-tolerated adequate home support during the first postoperative days required patient willing and able to participate in program preoperative independent functional status and mobility Exclusion criteria bleeding disorders or history of venous thromboembolism poorly controlled or severe cardiac disease (heart failure, uncontrolled arrhythmia) severe pulmonary disease (respiratory failure, home O2 requirements) uncontrolled diabetes mellitus (type I or II) BMI greater than 30-40 kg/m² (varies by protocol) chronic opioid consumption or substance abuse functional neurological impairments or cognitive deficits end-stage renal disease hypoalbuminemia or malnutrition dependent functional status or inadequate social support Risk Stratification Outpatient Arthroplasty Risk Assessment (OARA) Score predicts same-day discharge (SDD) score <79 equates to PPV 98.8% and specificity 99.3% for SDD compared to ASA-PS classification with PPV of 56.4% enhanced by patient education and expectation-setting multicenter validation across 40 locations and >12,000 TJAs confirming external validity some centers have found the score to be overly restrictive Outpatient Arthroplasty Risk Assessment (OARA) Total comorbidities assessed 52 medical conditions across multiple organ systems Highest-risk comorbidities (odds ratio for failed SDD) history of postoperative confusion (12x OR) pacemaker dependence (12x OR) other cardiac/pulmonary conditions (3-10x) BMI >40 kg/m² (2.3x) BMI 30-39 kg/m² (no effect) Score range 0 to >100+ points (cumulative) Optimal cutoff for primary THA/TKA <59 points (original) <79 points (updated) Score interpretation OARA score 0-59 Low-moderate risk (2.6-2.7x more likely for SDD) OARA 0-79 Acceptable for outpatient with low complication risk (PPV 98.8% for SDD) OARA >80 not appropriate, SDD significantly less likely Hospital Frailty Risk Score (HFRS) outperforms Charlson Comorbidity Index for predicting complications best predictor for surgical complications (AUC 0.719 THA, 0.738 TKA) derived from administration data Other Tools PLAN score (preoperative) AM-PAC "6-Clicks" (postoperative) when PLAN and "6-Clicks" agree on home discharge: 98% success, 5-7% readmission Predictors of same-day discharge (SDD) female gender associated with 1.7x higher risk of failed SDD TKA 1.9x higher than THA for failed SDD previous contralateral arthroplasty protective factor for SDD Discharge Criteria Functional requirements ability to ambulate safely with assistive device adequate pain control with oral medications ability to void spontaneously without urinary retention stable vital signs without orthostatic hypotension minimal nausea/vomiting, able to tolerate oral intake patient and caregiver confidence in home management Timing considerations typically met at 6 hours postoperatively ambulation achieved at mean 235 minutes after surgery UKA patients ambulate earliest, then TKA, then THA motor blockade resolution averages 198 minutes with lidocaine-bupivicaine spinal Preoperative Optimization Medical conditions anemia screening and correction essential preoperative anemia increases transfusion rate 4-fold hemoglobin A1c <7% target fructosamine >292-293 better predictor of adverse outcomes than HbA1c tight glycemic control decreases risk of periprosthetic joint infection (PJI) risk) smoking cessation enhances wound healing and reduces complications nutritional optimization, including vitamin D deficiency hypoalbuminemia correction reduces postoperative complications staphylococcus aureus screening and nasal decolonization cardiovascular disease optimization with cardiology consultation when indicated proceed directly to surgery in asymptomatic patients with functional capacity >4 METs consider further evaluation in patients with <4 METs and revised cardiac risk index (RCRI) >1 obstructive sleep apnea management and CPAP compliance verification rheumatoid arthritis medication management obesity patient-centered approaches prioritized without strict BMI cutoffs weight loss recommended when feasible before surgery GLP-1 agonist may reduce complication rates increases surgical time, infection risk, and mechanical complications Patient preparation consider preoperative physical therapy (prehabilitation) home safety evaluation identifies fall risk and need for equipment education on expectations and recovery timeline multidisciplinary seminars covering all aspects of treatment course Anesthesia & Pain Management Anesthesia techniques neuraxial anesthesia preferred over general anesthesia for outcomes spinal anesthesia reduces intraoperative and postoperative opioid requirements lower pain scores postoperatively with spinal anesthetic lidocaine-bupivicaine spinal mixture provides 198-minute motor blockade duration mepivicaine spinal allows faster discharge than bupivicaine (206 vs 291 min) general anesthesia acceptable with multimodal analgesia in selected patients both spinal and general anesthesia achieve 98-100% same-day discharge short-acting local anesthetics critical for same-day discharge Multimodal analgesia Regional Anesthesia TKA single-shot adductor canal block plus periarticular infiltration recommended nerve-block improves postoperative knee ROM THA PENG block fascia iliaca block femoral nerve block or lumbar plexus block NOT recommended due to motor blockade surgeon-administered periarticular injection Other Considerations insufficient evidence to support routine use of liposomal bupivicaine epidural analgesia adverse effects outweigh benefits intrathecal morphine risks and side-effects outweigh benefits Core Medications Acetaminophen recommended preoperatively and continued postoperatively no difference between oral and IV acetaminophen despite higher cost for IV COX-2 selective inhibitors or NSAIDs reduce pain/opioid consumption reduce risk of heterotopic ossification (THA) and arthrofibrosis (TKA) Intravenous dexamethasone 8-10 mg intraoperatively improves pain control Pregabalin may reduce pain and opioid use Gabapentin inconsistent evidence as side-effects (fatigue, CNS depression) may outweigh benefits Ketamine IV ketamine decreases opioid use in first 24 hours Postoperative nausea & vomiting (PONV) Antiemetics Risk assessment female gender history of PONV or motion sickness opioids and tranexamic acid elevate risk Prophylaxis strategies PO dissolving pellicle ondansetron 16mg superior to 8mg PO ondansetron superior to IV ondansetron palonosetron reduces PONV in high-risk patients addition of dexamethasone opioid-sparing techniques Enhanced Recovery After Surgery (ERAS) Core components standardized anesthesia PONV prophylaxis avoidance of bowel prep local anesthetic infiltration tranexamic acid prevention of hypothermia early mobilization Preoperative phase education on expectations and recovery timeline minimal fasting protocols (clear fluids 2 hrs, solids 6 hrs) optimization of medical comorbidities carbohydrate loading may reduce insulin resistance and improve recovery Intraoperative phase neuraxial or regional anesthetic preferred TXA administration reduces blood loss and transfusion requirements goal-directed fluid therapy active warming (maintain >36 degrees C) avoid surgical drains Postoperative phase early mobilization within 4-6 hours early oral intake and nutrition Key benefits reduces 30-day mortality (OR 0.46) and transfusion rates (OR 0.40) improves pain scores, ROM, PROMs Blood Management Tranexamic acid (TXA) recommended for all TJA patients without contraindications reduces hemoglobin drop by 0.65-0.68 g/dL in both THA and TKA lowers transfusion odds by 28% in THA and 74% in TKA decreases VTE risk by 44% dosing regimens IV TXA dose before procedure, at least one additional dose postoperatively oral TXA 2g preoperatively, then 1g at 3hr, 9hr, and 15hr optimal topical TXA doses >2g more efficacious than lower doses combined IV and topical may provide superior blood loss reduciton Anemia 33.6% patients present with preoperative anemia increases transfusion rate 6.5% from 1.5% 81.5% develop postoperative anemia routine type and screen not necessary for primary TJA Postdischarge Therapy Supervised PT recommended for patients with safety, mobility, or environmental concerns Unsupervised home programs may be as effective as supervised PT Outpatient Postdischarge Therapy Stratification criteria over 50% of TKA patients can self-direct supervised PT indicated if knee flexion <90 degrees or knee extension lacks >10 degrees at 2 weeks average of 4 supervised sessions needed Specific interventions group-based and individual PT sessions show equivalent outcomes continuous passive motion (CPM) devices show no benefit for TKA cryotherapy devices have no benefit pedaling exercises show promising benefits as part of mulitdisciplinary program supervised teletherapy proven effective, especially for patients with transport barriers Complication Surveillance Follow-up protocols contact recommended 7-10 days after surgery minimizes ED visits at least one in-person follow-up at 5-6 weeks recommended annual or biannual radiographic evaluation in asymptomatic patients Median Timing of Complications Stroke Day 2 (IQR 1-10) Myocardial Infarction (MI) Day 3 (IQR 2-6) Pulmonary Embolism (PE) Day 3 (IQR 2-7) Deep Vein Thrombosis (DVT) Day 6 (IQR 3-14) DVT and PE occur earlier after TKA than THA Urinary Tract Infection (UTI) Day 8 (IQR 3-16) Sepsis Day 10 (IQR 5-19) ED visit Day 10 Readmission Day 12-13 Surgical Site Infection (SSI) Day 17 (IQR 11-23) Major TKA complication Day 84 (IQR 26-224) Major THA complication Day 29 (IQR 16-80) Venous Thromboembolism Prophylaxis Selection of prophylaxis agent balances efficacy and bleeding risk Aspirin (ASA) generally favored due to cost, ease of use, and efficacy for majority of patients similar VTE prevention to LMWH, rivaroxaban, and apixaban 30% lower bleeding risk (0.33% vs 1.05%) with aspirin versus other anticoagulants inexpensive generic, oral, no monitoring required versus injections or dose adjustments effective across all risk profiles, including high-risk patients with comorbidities per ICM-VTE 2022 consensus notable caveat: CRISTAL trial showed higher symptomatic VTE (3.27% vs 1.76%) with aspirin versus enoxaparin after TJA Economic Impact Average cost reduction $4000-$7000 per case versus inpatient perioperative savings approximately $3900 for both hip and knee outpatient procedures two-thirds cheaper than 2-day inpatient stays Reduced hospital resource utilization and bed occupancy