Can a knee injection be performed from the medial aspect in an adult patient with osteoarthritis (OA) or rheumatoid arthritis (RA)?

Knee Injection via Medial Approach

Yes, knee injections can be safely and effectively performed from the medial aspect, specifically using the anteromedial joint line (AMJL) approach, which may be particularly beneficial for patients with medial compartment pathology. 1

Evidence Supporting Medial Approach

Efficacy of Anteromedial Technique

• The ultrasound-guided anteromedial joint line approach achieved 98.7% immediate symptomatic relief in patients with medial knee pain, with 92.3% maintaining positive response at 11-week follow-up. 1
• This approach specifically targets the medial compartment where pain-generating pathologies such as synovitis, medial meniscal injury, and medial collateral ligament injury are located. 1
• The AMJL approach was particularly effective in patients who had previously failed superolateral knee injections, with 51.3% of patients having attempted unsuccessful superolateral injections before receiving the medial approach. 1

Comparative Accuracy Considerations

• While multiple anatomical approaches exist for knee injection, accuracy of intra-articular placement varies considerably with the approach used, with up to 20% of injections failing to achieve accurate intra-articular placement. 2
• There is no evidence that a medial approach is inherently more or less accurate than other approaches. 2
• A recent comparison of medial infrapatellar (MIP) versus lateral infrapatellar (LIP) approaches for hyaluronic acid injection showed equal effectiveness in pain reduction and functional outcomes, with no significant differences in efficacy. 3

Clinical Application Algorithm

When to Choose Medial Approach

• Primary indication: Patients with confirmed medial compartment pathology (medial meniscal tears, medial collateral ligament injury, medial compartment osteoarthritis). 1
• Secondary indication: Patients who have failed prior superolateral or suprapatellar injections. 1
• Consider in obese patients, as the medial approach may provide better access in this population. 1

Technique Considerations

• Ultrasound guidance is strongly recommended for hip joint injections but not required for knee injections, though it may improve accuracy when available. 4
• The medial infrapatellar approach can be performed with or without ultrasound guidance. 3

Safety Profile

Adverse Events

• The medial infrapatellar approach showed a mildly higher incidence of local bruising compared to lateral approach (statistically significant, p=0.034), though these were transient and minor. 3
• Only one steroid flare was reported (1.3%) in a series of 76 knees receiving anteromedial injections. 1
• The overall incidence of serious infectious complications following knee joint injections ranges from 1 in 3,000, though this may be higher in high-risk patients. 2

Patient Selection Caveats

• Older age, lower BMI, and higher comorbidity burden (measured by Charlson Comorbidity Index) were associated with poorer response to medial approach injections. 1
• Strict screening should be performed before injecting prosthetic joints, as infection risk exists (0.6% in one series). 4

Medication Considerations

While the question addresses injection approach rather than medication choice, the available guidelines indicate:

• Intra-articular corticosteroid injections are strongly recommended for knee osteoarthritis with short-term efficacy demonstrated. 4
• The evidence for corticosteroid efficacy is inconclusive according to AAOS guidelines, though ACR provides strong recommendation. 4
• Hyaluronic acid is not recommended by AAOS (strong recommendation against), though it continues to be used clinically. 4