Can Orthopedic Surgery Be Performed with INR 1.8?
No, orthopedic surgery should not proceed with an INR of 1.8, as this level is associated with significantly increased bleeding risk, infection, and mortality in major orthopedic procedures.
Evidence-Based INR Thresholds for Orthopedic Surgery
The standard target INR for major surgical procedures, including orthopedic surgery, is <1.5 to minimize bleeding risk while allowing safe surgery 1. This threshold is supported by high-quality evidence specific to orthopedic procedures.
Specific Data from Total Knee Arthroplasty
A large analysis of 21,239 primary total knee arthroplasty cases demonstrated that:
- INR >1.25 to 1.5 was associated with increased bleeding (OR 1.29), infection rates, and mortality (OR 3.37) compared to INR ≤1.0 2
- INR >1.5 showed even higher risks: bleeding (OR 2.02) and infection (OR 5.34) 2
- Even modest elevations (INR >1.0 to 1.25) increased bleeding risk by 19% 2
Your patient's INR of 1.8 exceeds the safe threshold and falls into the high-risk category where complications are significantly elevated.
Preoperative Management Algorithm
Step 1: Delay Surgery and Reverse Anticoagulation
If the patient is on warfarin:
- Stop warfarin 5 days before surgery to allow INR to normalize to <1.5 1
- Check INR on the day before or day of surgery 1
- If INR remains >1.5 one to two days before surgery, postpone the procedure rather than routinely administering vitamin K 1
Step 2: Consider Vitamin K if Time-Sensitive
For semi-urgent cases where INR is 1.5-1.8:
- Administer low-dose oral vitamin K (1-2.5 mg) to achieve faster correction 1, 3
- Recheck INR within 24 hours before proceeding 1
- Avoid high-dose vitamin K (>5 mg) as this creates difficulty achieving therapeutic INR postoperatively 1, 3
Step 3: Emergency Surgery Protocol
If surgery cannot be delayed and is truly emergent:
- Administer 4-factor prothrombin complex concentrate (PCC) 25-50 U/kg IV plus vitamin K 5-10 mg by slow IV infusion 1, 3
- Target INR <1.5 before proceeding 1
- PCC achieves INR correction within 5-15 minutes versus hours with fresh frozen plasma 3
Special Considerations for High-Risk Patients
Patients Requiring Bridging Anticoagulation
High-risk patients include those with 1:
- Mechanical mitral valve or any mechanical valve with additional risk factors
- Recent venous thromboembolism
- Mechanical tricuspid valve replacement
For these patients:
- Use LMWH or unfractionated heparin bridging during warfarin interruption 1
- Stop LMWH 24 hours before surgery 1
- Resume anticoagulation 12-24 hours after surgery when adequate hemostasis is achieved 1
Critical Pitfalls to Avoid
Do not proceed with elective orthopedic surgery at INR 1.8 - the data clearly shows increased morbidity and mortality 2
Do not use high-dose vitamin K routinely - this creates warfarin resistance and makes postoperative anticoagulation difficult 1, 3
Do not assume INR will normalize quickly in hospitalized patients - underlying disease, comorbidities, and medications may prevent rapid response to warfarin cessation 4
For mechanical valve patients, never allow INR to fall rapidly with IV vitamin K without careful consideration, as this increases valve thrombosis risk 5
Postoperative Anticoagulation Resumption
Once surgery is completed with adequate hemostasis:
- Resume warfarin at the usual maintenance dose 12-24 hours postoperatively 1
- Avoid double-dosing, as evidence for accelerated dosing is weak 5
- For high-risk spinal procedures, delay resumption 48-72 hours 6
Bottom line: An INR of 1.8 is too high for safe orthopedic surgery. Delay the procedure, correct the INR to <1.5, and only proceed emergently with appropriate reversal agents if the surgery cannot wait.