Lawson J P, Ogden J A, Sella E, Barwick K W
Skeletal Radiol. 1984;12(4):250-62. doi: 10.1007/BF00349506.
The accessory navicular is usually considered a normal anatomic and roentgenographic variant. The term may refer to two distinct patterns. First, a sesamoid bone may be present within the posterior tibial tendon (Type 1); this is anatomically separate from the navicular. Second, an accessory ossification center may be medial to the navicular (Type 2). During postnatal development this is within a cartilaginous mass that is continuous with the cartilage of the navicular. At skeletal maturity the accessory center usually fuses with the navicular to form a curvilinear bone. The Type 2 pattern may be associated with a painful foot, particularly in the athletic adolescent, and should not be arbitrarily dismissed as a roentgenologic variant in the symptomatic patient. The clinical, radiologic, pathologic, and surgical findings in ten cases are reviewed. Roentgenographically the ossicle is triangular or heart-shaped. 99mTc MDP imaging may be of value when the significance of the ossicle is uncertain. Even when the roentgenographic variant is bilateral, increased radionuclide activity occurs only on the symptomatic side. Histologic examination of surgically excised specimens reveals inflammatory chondro-osseous changes in the navicular-accessory navicular synchondrosis compatible with chronic trauma and stress fracture. Nonsurgical treatment with orthotics or cast immobilization produces variable results and resection of the accessory navicular may be the treatment of choice.
副舟骨通常被认为是一种正常的解剖和影像学变异。该术语可能指两种不同的类型。第一，在胫后肌腱内可能存在籽骨（1型）；这在解剖学上与舟骨分开。第二，一个副骨化中心可能位于舟骨内侧（2型）。在出生后的发育过程中，它位于与舟骨软骨连续的软骨块内。在骨骼成熟时，副中心通常与舟骨融合形成一个曲线形的骨头。2型可能与足部疼痛有关，尤其是在运动的青少年中，在有症状的患者中不应将其随意视为一种影像学变异。本文回顾了10例患者的临床、放射学、病理学和手术结果。在X线片上，小骨呈三角形或心形。当小骨的意义不确定时，99mTc MDP显像可能有价值。即使影像学变异是双侧的，放射性核素活性增加也仅发生在有症状的一侧。对手术切除标本的组织学检查显示，舟骨-副舟骨软骨结合处有与慢性创伤和应力性骨折相符的炎性软骨骨改变。使用矫形器或石膏固定进行非手术治疗效果不一，切除副舟骨可能是首选治疗方法。
