Müller-Weiss Disease

Müller-Weiss disease, described by Müller in 1927 and Weiss in 1929, is a spontaneous, adult-onset deformity of the tarsal navicular. The bone is compressed laterally, fragments and is extruded dorsomedially, and the peritalar joints follow it into malalignment and arthritis.

Who gets it. Patients present in the fourth to sixth decades, with a female predominance in most published series. The disease is frequently bilateral, though often asymmetric in severity and symptoms, and it is commonly misdiagnosed for years as "midfoot osteoarthritis" or tibialis posterior dysfunction. Reported prevalence is higher in populations with childhood nutritional deprivation or heavy barefoot childhood loading, which supports a developmental origin.

Maceira's developmental theory. The navicular is the last tarsal bone to ossify, at around age 3 (chronologically earlier in girls), and delayed ossification leaves it vulnerable. Maceira and Rochera proposed that delayed ossification in childhood, from nutritional, socioeconomic or mechanical stress, leaves a soft, cartilaginous lateral navicular exposed to asymmetric compressive load. A short first ray (index minus), or any forefoot morphology that shifts load laterally, concentrates force on the lateral navicular between the talar head and the lateral cuneiform.

Over decades the lateral pole is compressed and effectively "extruded" medially and dorsally. The bone becomes comma-shaped, the talar head migrates dorsolaterally past the deficient lateral navicular, and the subtalar joint rotates into varus. On this reading Müller-Weiss is a dysplasia with secondary mechanical failure, not a primary vascular event.

The osteonecrosis theory. The alternative view is primary spontaneous osteonecrosis of the adult navicular. The bone has a watershed central third, supplied peripherally by dorsalis pedis and medial plantar branches, the same vascular vulnerability that underlies navicular stress fracture, and its sclerosis, fragmentation and MRI signal change resemble osteonecrosis elsewhere. Critics note that histology from fusion specimens often shows viable bone with degenerative and reparative change rather than classic necrosis, and that the stereotyped lateral-compression morphology is better explained mechanically.

The synthesis. Most modern authors accept a combined model: a developmentally vulnerable, dysplastic lateral navicular fails under chronic asymmetric load, with secondary ischaemic change superimposed in the compressed, fragmented segments. In the exam, present both theories and credit Maceira's mechanical model for explaining the characteristic pes planovarus.

The arch is not always flat. Do not call the planovarus pathognomonic; Maceira's own paper does not. He writes that the plantar arch "may correspond to that of a normal, cavus, or flat foot". What is constant is the squeezed, laterally compressed navicular and the inverted subtalar joint driven by the laterally protruding talar head; the flat arch is the commonest of three possible consequences, not a diagnostic requirement. A normal-looking arch does not exclude Müller-Weiss, and a frankly cavus foot can still be it.

This is the single most examinable concept in the topic, and it can be derived rather than memorised.

The mechanism. The lateral half of the navicular collapses, shortening the lateral side of the talonavicular articulation. The talar head, losing its lateral support, slides dorsally and laterally relative to the navicular remnant; that lateral migration effectively abducts the talus over the calcaneus, and the subtalar complex compensates by rotating into inversion, which is hindfoot varus. At the same time the medial longitudinal arch flattens, because the medial column has lost navicular height and the talus sits dorsiflexed or plantarflexed abnormally relative to the first metatarsal, so the Meary line breaks.

The rule. Flat arch plus varus heel equals pes planovarus, the mirror image of tibialis posterior dysfunction, the far commoner pattern, which gives a flat arch with a valgus heel, an abducted forefoot and the "too many toes" sign. Recognising the varus heel behind a flat foot should immediately trigger the diagnosis; mistaking the two leads to the wrong orthosis and the wrong operation.

History. The complaint is insidious, chronic dorsomedial midfoot pain, often present for years before the diagnosis is made. It is worse on uneven ground, prolonged standing and push-off, and better in stiff-soled shoes. There is no single traumatic event, which separates it from stress fracture and Lisfranc pathology. Ask about childhood nutrition and illness, an occupation with prolonged loading, and contralateral symptoms.

Standing inspection. From behind, with the patient standing feet at shoulder width, compare the heel axis with the tibial axis: in Müller-Weiss the heel sits in varus despite a flattened medial arch. A Coleman-block-style assessment can follow; if a lateral forefoot block corrects the heel towards neutral the varus is forefoot-driven and flexible, and a fixed varus implies structural subtalar change. From the side, look for loss of the medial longitudinal arch and a dorsolateral prominence over the talar head as it subluxes past the collapsed navicular.

View larger

Palpation. With the patient seated, place a thumb over the talonavicular joint dorsally and dorsomedially: there is focal tenderness, and sometimes a palpable, medially protruding navicular fragment. Distinguish this from the "N spot", the dorsal central navicular tenderness of stress fracture, and from naviculocuneiform tenderness, which signals adjacent-joint arthritis in advanced stages.

Rigid or flexible. With the patient seated and the knee flexed, grasp the heel in one hand and the midfoot in the other; passively invert and evert the subtalar joint, then adduct and abduct through the transverse tarsal joints. Record whether the hindfoot varus and the midfoot deformity correct passively, because flexibility guides whether osteotomy adjuncts or in-situ fusion positioning will be needed.

Neurovascular examination is mandatory, to exclude the neuropathy of the Charcot differential: monofilament testing, vibration sense and pulses. Gait is antalgic with reduced push-off, and the varus heel may leave lateral border overload callosities under the fifth metatarsal.

Köhler disease is a different disease. It is the childhood navicular osteochondrosis, treated with symptomatic care or a short period of casting, and it heals with normal ossification; Müller-Weiss is the adult disease with permanent structural collapse. The other causes of dorsomedial midfoot pain with navicular change are set out below, and the Charcot foot is the one that must never be missed, because a fusion in unrecognised Charcot fails.

Related pages. The one it is confused with, in a different decade: Köhler Disease — the self-limiting childhood navicular osteochondrosis. The other navicular diagnoses to exclude: Navicular Stress Fracture, Navicular Fractures and Accessory Navicular. The deformity it mimics and inverts: Adult Flatfoot Deformity and Tibialis Posterior Anatomy — flat arch with a valgus heel, against the varus heel here — plus Cavovarus Foot for the arch Maceira says some of these feet have. The joints that end up fused: Talonavicular Arthritis, Midfoot Arthritis and Subtalar Arthritis. The destructive midfoot differentials: Charcot Neuroarthropathy and Lisfranc Injuries.

• Global epidemiology: the disease is described worldwide but with striking regional clustering — higher reported prevalence in southern Europe (notably Spain, where Maceira's series originated) and in populations with historical childhood nutritional deprivation, consistent with the developmental theory. In many regions it remains under-recognised and coded simply as midfoot osteoarthritis.
• Society guidance: no major society (AAOS, NICE, BOA, EFORT) publishes a disease-specific guideline for Müller-Weiss; practice is guided by expert consensus and case series, principally Maceira's framework. General midfoot arthritis and arthrodesis principles from foot and ankle society consensus documents apply to fixation and aftercare.
• Registries: joint registries do not capture midfoot fusion outcomes in a disease-specific way, so evidence remains limited to institutional series — a fair point to make in a viva about the quality of evidence.
• Resource-setting variation: in well-resourced systems, weightbearing CT increasingly refines staging and fusion planning; in resource-limited settings, weightbearing plain films plus clinical assessment remain fully adequate for diagnosis and staging, and prolonged high-quality orthotic/footwear management is the mainstay — appropriately so, given that most patients do well without surgery. Access to custom rigid orthoses, rather than surgery, is the key resource determinant of outcome.

• Dysplasia versus osteonecrosis: histological studies from fusion specimens often show viable degenerative bone, undermining a pure osteonecrosis model, yet MRI necrosis-like change is common — most authors now accept a combined mechanical–ischaemic model.
• Extent of fusion: isolated talonavicular versus talonavicular-cuneiform versus triple fusion for the same stage remains surgeon-dependent; the trend favours extended medial column fusion because of naviculocuneiform involvement and non-union risk through the diseased navicular, but comparative data are absent.
• Role of joint-sparing surgery: calcaneal osteotomy with or without percutaneous procedures as stand-alone treatment in early flexible disease has advocates but lacks robust supporting series; fusion remains the standard for structural disease.
• When to operate: because non-operative care is so often durable, the threshold and timing for fusion — and whether earlier surgery prevents progression to stage 5 — are unresolved.
• Biologic adjuncts: vascularised grafting and orthobiologics for the sclerotic navicular are described anecdotally without comparative evidence.