Abstract / Summary
Abstract Total knee arthroplasty volumes continue to rise, particularly in younger patients with advanced osteoarthritis who lack durable joint-preserving alternatives. Evidence for bone marrow aspirate concentrate (BMAC) beyond four years, and reliable predictors of response, have been lacking. We prospectively followed 50 knees with Kellgren-Lawrence grade II-IV knee osteoarthritis in 35 patients after a single intra-articular BMAC injection using the reorientation technique; 49 knees entered analysis. IKDC improved from 57.0 ± 13.4 to 74.1 ± 14.9 and WOMAC from 36.8 ± 23.9 to 16.3 ± 19.5 at seven years (both p < 0.001), with gains achieved within the first year and maintained thereafter. Eleven knees were converted to arthroplasty, giving a 7-year TKA-free survival of 64%. Baseline symptom severity did not distinguish failures from successes (WOMAC p = 0.494; IKDC p = 0.143). Two readily assessable baseline variables did: extension deficit (7.2° ± 5.6° vs 1.1° ± 2.6°; p = 0.002) and BMI (27.1 ± 4.7 vs 24.4 ± 3.9 kg/m²; p = 0.05). In the 36 knees without these features, 7-year TKA-free survival reached 80%. One minor, self-limiting complication occurred. This longest reported follow-up for intra-articular BMAC demonstrates a durable, low-risk effect governed by patient selection rather than disease severity.