NTRK1 and osteoarthritis: Zhu et al. found that sensory nerves and osteoclasts were increased in the subchondral bone as early as the first week after anterior cruciate ligament transection (ACLT) surgery, that is, at the early stage of osteoarthritis (OA).44 However, Hao et al.8 found that the number of osteoclasts was not altered in the mouse models of sensory denervation (TrkA Avil-/- or adult iDTR Avilfl-/- mice injected with 1 μg·kg−1 diphtheria toxin).