Tibialis Posterior Tendon Dysfunction (PTTD): Stages, Dia…

Stage	Deformity	Flexible?	Heel Rise Test	Treatment
Stage I	None visible; tendon inflamed but functional	Yes — arch present non-weight-bearing	Single-leg heel rise: painful but possible	CAM boot 4–6 weeks; PT; UCBL or custom medial arch orthotic; NSAIDs
Stage II	Flexible flat foot; “too many toes” sign positive; hindfoot valgus; forefoot abduction	Yes — deformity corrects non-weight-bearing	Single-leg heel rise: cannot complete; pain; collapses into valgus	Orthotic (UCBL or AFO); PT; medial calcaneal slide osteotomy + FDL transfer; lateral column lengthening for severe abduction
Stage IIb	Stage II + significant forefoot abduction (>40% uncoverage of talar head)	Yes	Cannot complete	Calcaneal osteotomy + lateral column lengthening + FDL transfer
Stage III	Rigid flat foot; fixed hindfoot valgus; no correction on tiptoe	No — deformity fixed	Cannot perform	Triple arthrodesis (subtalar + talonavicular + calcaneocuboid fusion)
Stage IV	Stage III + valgus tilt of ankle mortise; tibiotalar involvement	No	Cannot perform	Triple arthrodesis + deltoid repair or total ankle replacement

Clinical Sign	How to Test	PTTD Result	Significance
Single-leg heel rise test	Patient stands on one foot (affected side); attempts to rise onto tiptoe 10 times	Cannot rise, collapses into valgus, or painful	Most sensitive clinical test for PTTD; normal is 10 reps without pain
“Too many toes” sign	Examiner views patient from behind; counts visible lateral toes	More toes visible on affected side due to forefoot abduction	Indicates forefoot abduction; correlates with Stage IIb severity
Hindfoot alignment	Posterior view with patient weight-bearing; observe heel position relative to leg axis	Hindfoot valgus (heel tilts outward) on affected side	Quantifies collapse; >10° valgus = significant
Navicular drop test	Mark navicular tuberosity; measure height sitting vs. standing	Excessive drop (>10mm) with weight-bearing	Quantifies arch collapse; correlates with tendon dysfunction severity
Subtalar rigidity	Examiner moves subtalar joint passively; then asks patient to actively correct valgus	Stage II: corrects; Stage III: fixed, cannot correct	Distinguishes flexible (Stage II) from rigid (Stage III) flat foot; determines surgical approach

What Is Tibialis Posterior Tendon Dysfunction?

Tibialis posterior tendon dysfunction (PTTD), also called posterior tibial tendon dysfunction, is the most common cause of adult-acquired flat foot deformity in the United States. The tibialis posterior muscle — whose tendon runs behind the medial malleolus and fans out to attach to the navicular and multiple other midfoot bones — is the primary dynamic supporter of the medial longitudinal arch. When this tendon fails (from degeneration, tendinopathy, or rupture), the arch collapses progressively, the heel tilts outward (valgus), the forefoot abducts, and the patient develops a flat foot that is initially flexible and later becomes rigid. PTTD follows a predictable 4-stage progression; treatment is stage-specific, and delayed diagnosis commonly allows progression to a stage that requires much more invasive surgery.

Why PTTD Is Missed and Misdiagnosed

PTTD is commonly misdiagnosed as a medial ankle sprain or as “just flat feet” in its early stages. The classic patient is a middle-aged woman (female sex, obesity, hypertension, and prior steroid injections are the strongest risk factors) with pain and swelling behind the medial malleolus that is worse with activity. This is often attributed to a sprain when it is actually tendon degeneration. The critical distinguishing test is the single-leg heel rise: ask the patient to stand on the affected foot alone and try to rise onto their toes 10 times. Normal subjects complete this easily. PTTD patients cannot rise fully, the heel collapses into valgus rather than inverting during the rise, and the attempt is painful. A single-leg heel rise test that is clearly abnormal in a patient with medial ankle pain almost certainly indicates PTTD — not a sprain.

Conservative Treatment for Stage I and Early Stage II

Stage I PTTD — tendon inflammation without deformity — is treated with immobilization (CAM boot for 4–6 weeks to offload the tendon), followed by a custom UCBL (University of California Biomechanics Laboratory) orthotic that controls hindfoot valgus and supports the arch, combined with physical therapy focusing on eccentric tibialis posterior strengthening. Physical therapy for PTTD is stage-specific: in Stage I, eccentric inversion exercises against resistance strengthen the tendon; in Stage II, exercises focus on controlling collapse rather than maximally loading the tendon. NSAIDs reduce the inflammatory component. Corticosteroid injections around the posterior tibial tendon are generally avoided — the tendon is already weakened and steroid injection significantly increases rupture risk.

Surgery: What Stage II and Beyond Require

For Stage II PTTD that has failed 3–6 months of conservative care, the standard surgical reconstruction combines: (1) flexor digitorum longus (FDL) tendon transfer to augment or replace the failed posterior tibial tendon; (2) medial calcaneal slide osteotomy to correct hindfoot valgus by shifting the calcaneus medially; and when significant forefoot abduction is present (Stage IIb), (3) lateral column lengthening (Evans osteotomy) to restore arch height and correct talar head uncoverage. This combination achieves excellent outcomes: 85–90% patient satisfaction with correction of the deformity and pain relief. Stage III (rigid flat foot) requires triple arthrodesis (fusion of three hindfoot joints: subtalar, talonavicular, and calcaneocuboid), which eliminates motion but provides durable deformity correction. Stage IV adds deltoid ligament repair or total ankle replacement for the ankle valgus component.

At Balance Foot & Ankle, Dr. Tom Biernacki and Dr. Carl Jay evaluate and treat PTTD at all stages, from early orthotic management through reconstructive surgery, at both the Howell and Bloomfield Hills offices. Call (810) 206-1402.

For a complete clinical overview: Ankle Pain Conditions Guide — location-by-location ankle pain diagnosis and treatment