Osteonecrosis of tarsal navicular bone in an adult

Clinical History

A 59-year-old man with no history of previous trauma reported pain in the right ankle and medial foot, which worsened with walking and was associated with walking difficulties. Physical examination revealed flattening of the medial arch. The orthopaedic surgeon requested an X-ray.

Imaging Findings

Our patient underwent weight-bearing X-rays (anterior-posterior and lateral views), computed tomography (CT) and magnetic resonance imaging (MRI).
The tests revealed comma-shaped and medial extrusion of the navicular bone associated to loss of width of the bone on the lateral view. They also showed irregular margins and sclerosis of both navicular bones as well as degenerative changes in the talonavicular joint. Both feet showed similar findings.
Hypo-intensity of navicular bone marrow on T1 weighted images and hyper-intensity in liquid sensitive sequences (both T2 and PD) is seen (MRI). All these findings are strongly suggestive of bone marrow oedema.

Discussion

Spontaneous osteonecrosis of the tarsal navicular bone in adults is called Müller-Weiss syndrome. It is a different entity than Köhler disease, which is an osteochondrosis of the tarsal navicular bone that occurs in children [1].
Müller-Weiss syndrome is thought to develop as a result of excessive mechanical strain, both compressive and tensile, affecting the bone's vascular supply [1, 2]. Patients should also be questioned about nutritional deficiencies in childhood, tooth loss before the third decade, endocrinopathies, or other systemic diseases, as the condition's aetiology is still unclear and theories about a nutritional origin have been proposed [3, 8].
It commonly affects women and it shows bilateral distribution. However, Köhler’s disease occurs in children and tends to be unilateral in presentation [4].

X-ray reveals a comma-shaped or wedge-shaped navicular bone on the anteroposterior view which corresponds to deformity and collapse on the lateral aspect of the bone caused by lateral compression. Irregularity, sclerosis, fracture and fragmentation may be also present [4, 5]. Subtalar varus is commonly associated, with a lateral shift of the head of the talus that compress the lateral half of the navicular against the lateral cuneiforms. A short first metatarsal bone also favours this abnormal force distribution pattern [3].
On CT similar findings to plain radiographs may be recognized. Also, CT can be helpful to precisely define the site(s) of fragmentation, which can be difficult to see on routine radiography alone [5].
MR features show a homogeneous decrease in the signal intensity of the navicular bone on T1 -weighted images [5]. STIR/PD fat-sat images reveal bone marrow oedema and small joint effusion when present. Intravenous contrast is not required for the diagnosis. The main advantage of MR is the increased sensitivity in depicting the early changes compared to plain radiographs and CT.
Differential diagnosis of Müller-Weiss syndrome includes neuropathic arthropathy, gout, rheumatic conditions, fractures and post-traumatic conditions, osteochondral lesions, iatrogenic surgery, atypical accessory navicular, etc. [5, 6].

Treatment of Müller-Weiss syndrome generally consists of non–weight-bearing cast immobilization and the use of oral anti-inflammatory and analgesic medications [7].
Surgical treatment may be indicated when pain and dysfunction persist in spite of the correct orthotic and rehabilitation treatment [6]. There is no consensus on the appropriate surgical treatment of Müller-Weiss syndrome.
Multiple surgical techniques have been used: pinning of the navicular, excision of the dorsal extruded fragment, talonavicular arthrodesis, naviculocuneiform arthrodesis,
talonaviculocuneiform fusion, etc.

Differential Diagnosis List

Final Diagnosis

Müller-Weiss syndrome

URL:	https://www.eurorad.org/case/12944
DOI:	10.1594/EURORAD/CASE.12944
ISSN:	1563-4086