Related Experiment Video
Updated: Jan 13, 2026
Author Spotlight: Fu's Subcutaneous Needling for Knee Osteoarthritis Pain
Published on: March 24, 2023
Minimal Clinically Important Difference After Triamcinolone Acetonide Injection for Knee Osteoarthritis
Jesse M Galina1, Meghan L Morley2, Sibtain Mustafa2
1Department of Orthopaedic Surgery, Maimonides Medical Center, Brooklyn, New York; and.
Objective:
This study aimed to define the minimal clinically important difference (MCID) after triamcinolone acetonide (TA) injections for knee osteoarthritis, see if the value changes over time, and report the proportion of patients achieving MCID monthly for 6 months.
Study Design:
Retrospective case series; level of evidence, 4.
Setting:
One large university-affiliated practice (13 providers).
Patients Or Participants:
Two hundred seventy-seven patients receiving TA (40 mg) with 4cc 1% lidocaine for knee osteoarthritis (OA) were retrospectively reviewed.
Intervention:
Patients receiving TA (40 mg) with 4cc 1% lidocaine for knee OA.
Main Outcome Measure:
Knee Injury and Osteoarthritis Outcome Score (KOOS) preinjection and monthly for 6 months. MCID values, representing moderate clinical improvement, were calculated as 0.5 standard deviations from preinjection scores.
Results:
Of 277 injections (116 men, 161 women; mean age 61.3 years), MCID values varied across KOOS subscales (7.98-12.35). At the 1-month through 6-month follow-ups, the proportion of patients reaching the MCID on the KOOS pain scale was 50.5%, 47.7%, 36.2%, 37.1%, 44.8%, and 39.4%, respectively. Twenty-three percent of patients received a repeat injection within 6 months. Patients who did not meet the calculated MCID for pain by 1 month had a 2.19 times higher odds ratio of receiving a repeat injection within 6 months.
Conclusions:
This study establishes MCID values for KOOS subscales in patients with knee OA receiving TA injections using a distribution-based method, which are similar regardless of duration of follow-up within 6 months. Patients can expect significant pain improvement within the first month, with declining effects thereafter. Lack of early pain improvement correlates with a higher likelihood of repeat injection, supporting the need for follow-up assessments to guide ongoing treatment.
Insights
Minimal clinically important difference (MCID) for triamcinolone acetonide (TA) injections in knee osteoarthritis (OA) was established. Early pain improvement within one month is key, as lack of it predicts repeat injections.
Area of Science:
- Orthopedics
- Rheumatology
- Pharmacology
Background:
- Knee osteoarthritis (OA) significantly impacts patient quality of life.
- Intra-articular corticosteroid injections, such as triamcinolone acetonide (TA), are common treatments for OA.
- Defining the minimal clinically important difference (MCID) is crucial for evaluating treatment efficacy.
Purpose of the Study:
- To define the MCID for TA injections in knee OA patients.
- To assess if MCID values change over a 6-month period.
- To determine the proportion of patients achieving MCID monthly post-injection.
Main Methods:
- Retrospective case series of 277 patients with knee OA receiving TA injections.
- Knee Injury and Osteoarthritis Outcome Score (KOOS) was administered pre-injection and monthly for 6 months.
- MCID was calculated as 0.5 standard deviations from preinjection KOOS scores.
Main Results:
- MCID values varied across KOOS subscales (7.98-12.35).
- The proportion of patients achieving MCID for pain ranged from 36.2% to 50.5% across the 6-month follow-up.
- Patients not achieving MCID for pain by 1 month had a 2.19 times higher odds of receiving a repeat injection within 6 months.
Conclusions:
- Distribution-based MCID values for KOOS subscales in knee OA patients receiving TA injections were established.
- Significant pain improvement is expected within the first month, with diminishing effects over time.
- Lack of early pain improvement is a predictor for repeat injections, highlighting the importance of follow-up assessments.
