Towards understanding Müller-Weiss disease: a universal platform

J. Wong-Chung, R. McKenna, M. Lynch-Wong, A. Walls, A. Wilson

Background: The only existing classification of Müller-Weiss Disease (MWD), based solely on Méary’s angle, serves neither as guide for prognosis nor treatment. This accounts for lack of gold standard in its management.

Methods: Navicular compression, medial extrusion, Kite’s angle and metatarsal lengths were measured on all radiographs of 95 feet with MWD. Joints involved, presence and location of navicular fracture were recorded.

Results: We identified three distinct groups. Group 1 comprises 11 “early-onset” MWD feet, aged 9 to 29 years. These had the greatest compression and medial extrusion, and lowest Kite’s angles. All except 1 were index minus and had a lateral navicular fracture. None has required surgery to date. Only 1 has moderate talonavicular joint (TNJ) degeneration. Group 2 comprises 23 “Müller-Weissoid” feet with radiologically normal navicular in their fifties and developing MWD, on average, 4.5 years later. These had the lowest compression and extrusion, and highest Kite’s angles. None had complete fracture. All had TNJ arthritis, with early changes at lateral naviculocuneiform joint (NCJ) in 43%. Group 3 “late-onset” MWD, presenting in the sixth decade, is subdivided into 3 sub-groups. Only TNJ is involved in group 3A (16). Group 3B denotes affection of TNJ more than NCJ (20). In group 3C “reverse Müller-Weiss disease”, which affects NCJ more than TNJ (25), second metatarsal overlength is highest of all groups. No difference in age, compression, extrusion and Kite’s angle exists among the 3 subgroups. No fracture occurred in group 3A compared to 65% and 32% in groups 3B and 3C, respectively.

Conclusions: With a need to compare like-for-like pathology, the proposed classification provides a common platform for reporting outcomes of different treatment modalities, operative or nonoperative. We theorize pathogenetic pathways in the different groups and propose systematic surgical approaches for each category.