How should I manage a 65-year-old patient with left knee pain, mild medial compartment osteoarthritis and patellofemoral joint space narrowing, and a small sclerotic proximal tibial lesion consistent with enchondroma or bone infarct?

Management of Knee Pain with Mild Osteoarthritis and Incidental Bone Lesion

Treat this patient's knee pain with conservative management focused on exercise therapy and weight loss, while the sclerotic tibial lesion requires no treatment as enchondromas and bone infarcts are benign incidental findings that do not cause pain. 1, 2

Addressing the Tibial Lesion

The small sclerotic lesion in the proximal tibia is not the source of your patient's knee pain and requires no intervention:

• Enchondromas and bone infarcts are benign, asymptomatic lesions that are commonly discovered incidentally on radiographs obtained for other reasons 3
• These lesions do not correlate with knee pain symptoms and should not distract from treating the actual pain source—the osteoarthritis 4, 2
• No further imaging or follow-up is needed for this lesion unless it changes in appearance or the clinical picture becomes atypical 3

Managing the Osteoarthritis (The Actual Pain Source)

Your patient has medial compartment and patellofemoral osteoarthritis, which is the most common cause of knee pain in this age group and the clear source of symptoms 1, 5, 2

First-Line Conservative Treatment

Exercise therapy is the cornerstone of treatment and should be initiated immediately:

• Quadriceps strengthening exercises are critical, as muscle weakness is both cause and consequence of knee OA 1
• Prescribe low-impact aerobic activity for 30-60 minutes daily at moderate intensity 1
• Add progressive strength training of major muscle groups 2 days/week at 60-80% of one repetition maximum for 8-12 repetitions 1
• Require 12 or more directly supervised physical therapy sessions for optimal outcomes (effect size 0.46 vs 0.28 for fewer sessions) 1

Weight management is essential if the patient is overweight, as obesity increases mechanical stress on the medial compartment which bears 70-80% of joint load during gait 1, 5, 6

Pharmacological Management

Start with topical NSAIDs as first-line for localized medial knee pain 1:

• Topical agents have fewer systemic side effects and are appropriate for this age group 1
• Acetaminophen up to 4g/day is an alternative if topical NSAIDs are insufficient 1

If topical agents fail, use oral NSAIDs cautiously:

• Prescribe at the lowest effective dose for the shortest duration 1
• COX-2 inhibitors have similar efficacy with better GI safety profile in elderly patients 1
• Avoid prolonged high-dose NSAIDs due to GI, renal, and platelet toxicity risk in this age group 1

When to Consider Advanced Imaging

MRI is not routinely indicated for straightforward osteoarthritis with typical presentation 3:

• The ACR Appropriateness Criteria state that MRI without IV contrast is indicated when pain persists despite conservative treatment or if there is unexpected rapid progression 3
• MRI can identify bone marrow lesions (BMLs) and synovitis that correlate with knee pain in OA patients 3
• However, meniscal tears are often incidental findings in patients over 65, with the majority having asymptomatic tears 3

Surgical Consideration

Total knee arthroplasty (TKA) is reserved for end-stage disease when conservative measures are exhausted and pain severely limits function 1:

• This patient has only mild degenerative changes, making surgery premature 1, 4
• If obesity is present, substantial weight loss before TKA is advisable as it increases technical difficulty and complication risk 1
• For tricompartmental disease (which this patient has with both medial and patellofemoral involvement), TKA is preferred over unicompartmental replacement 1

Long-Term Management Strategy

Continue physical therapy and exercise as long-term maintenance, even if pain improves 1:

• Exercise should be integrated into daily life after initial supervised sessions 1
• Ongoing weight management is essential with regular monitoring and treatment adjustment based on response 1

Common Pitfalls to Avoid

• Do not pursue the tibial lesion—it is a red herring that will lead to unnecessary imaging, referrals, and patient anxiety 3
• Do not order MRI prematurely—routine imaging in OA follow-up is not recommended unless there is unexpected rapid progression 3
• Do not refer for arthroscopy based solely on radiographic findings without failed conservative treatment 2
• Do not underestimate the importance of supervised exercise—unsupervised programs have significantly lower effect sizes 1