OARSI initiative to develop classification criteria for early-stage symptomatic knee OA (EsSKOA): What conditions should be considered in the differential diagnosis of EsSKOA?

OBJECTIVE

Classification criteria for early-stage symptomatic knee osteoarthritis (EsSKOA) should discriminate individuals with EsSKOA from those with other causes of knee symptoms. We sought to identify conditions in the differential diagnosis of EsSKOA in adults with knee symptoms.

DESIGN

We conducted an online survey of clinicians. Those consulting monthly on at least five people with undiagnosed knee symptoms were eligible. From qualitative work and clinical experience, we developed three case scenarios representing possible EsSKOA: 1. 40-year-old with 1 month of knee stiffness and swelling; 2. 50-year-old with 8 months of knee discomfort while walking; and 3. 60-year-old with intense knee discomfort getting out of a car 1 week ago. For each scenario, participants indicated conditions on a pre-defined list that they would consider in the differential diagnosis, and the top three diagnoses based on clinical experience. The proportions that considered each condition and among the top three diagnoses for each scenario were summarized overall and by clinical discipline.

RESULTS

127 clinicians responded (43% female, 48% in practice ≤15 years, 50% university-affiliated practice, 7 clinical disciplines). Knee OA and meniscal injuries were among the top three conditions in the differential diagnosis for all three scenarios, followed by immune-mediated and crystal-induced inflammatory arthritis (scenario 1), patellofemoral pain syndrome (scenario 2), and collateral ligament injuries (scenario 3).

CONCLUSION

The differential diagnosis for EsSKOA in adults presenting with undiagnosed knee symptoms includes symptomatic established radiographic knee OA, patellofemoral pain syndrome, meniscal and collateral ligament injuries, and immune-mediated and crystal-induced inflammatory arthritis.