600 - A Twist in the Tale: Unraveling Ankle Pain

Case Diagnosis: Mueller Weiss Syndrome

Case Description:
A 15-year-old female presented for right anterolateral ankle pain which began two weeks prior while rock climbing. She inverted her ankle when landing from a jump, which resulted in immediate pain and swelling, and later bruising. She rated her pain 5/10 with weightbearing, and she had pain with passive dorsiflexion and inversion. On physical examination, she had diffuse tenderness about the ATFL, CFL, medial talus, and talar dome, and a positive anterior drawer for pain and mild laxity.


Radiographs showed a bony fragment along the medial talus concerning for an avulsion fracture. On later recall, the patient noted chronic medial ankle pain. Given the medial pain and the radiographic abnormality, she was put in a boot for protected weightbearing. MRI demonstrated an ATFL sprain and a dysplastic navicular. Findings were suggestive of a chronic nonunited stress fracture of the navicular midportion and significant marrow edema within the hypoplastic lateral fragment.

Discussions:
Given this chronicity in the setting of a stress fracture, she underwent an open reduction internal fixation of the navicular with calcaneus autograft bone grafting.


Mueller Weiss Syndrome is a collapse of the lateral navicular, with medial protrusion of the talar head. The pathophysiology is debated, however the current theory is delayed navicular ossification and lateral navicular compression for lateral weight transfer. The lateral talar head redistributes the compressive stress to the lateral navicular and the cuneiforms, as seen with hindfoot varus. Another contributor to the poor force pattern includes a short first metatarsal. Because of its relation to improper biomechanics, early intervention may prevent stress fracture formation.

Conclusions: Clinicians must maintain a broad differential for medial ankle pain.  If poor biomechanics are corrected early, there may be a role for preventing the development of Mueller Weiss Syndrome.