Posterior Tibialis Tendon Dysfunction

Patients describe progressive medial ankle and midfoot pain along the course of the PTT, posterior to and below the medial malleolus, extending to the navicular insertion. Onset is gradual over months to years. Other features include progressive flattening of the foot (often first noticed by family or via uneven medial sole wear), difficulty pushing off, and difficulty with stairs and slopes. Lateral ankle or sinus tarsi pain develops in advanced stages from subfibular impingement. Bilateral involvement is common with inflammatory arthritis or systemic risk factors.

Examination focuses on three findings:

• •Single heel raise test (the most useful functional test): the patient stands on one leg and rises onto tiptoe. Normally the heel inverts and the arch heightens. From Stage II onward the patient cannot perform a single heel raise; the heel fails to invert and the arch does not reconstitute
• •Too many toes sign: viewed from behind in standing, more than one or two toes are visible lateral to the heel because of forefoot abduction
• •Flexible versus rigid (the critical distinction): does the hindfoot valgus correct passively when non-weight-bearing? Flexible is Stage II; rigid is Stage III

Additional findings include medial tenderness and swelling along the PTT, weakness on resisted inversion with the foot plantarflexed (isolating PTT from tibialis anterior), gastrocnemius tightness on Silfverskiold testing, and asymmetric medial sole wear on the shoes. Key differentials include spring ligament injury, tarsal coalition (rigid flatfoot in younger patients), inflammatory arthritis, and Charcot neuroarthropathy - a critical safety consideration in any diabetic patient presenting with a new hot, swollen, or rapidly deforming foot per BOFAS guidance.

PTTD is primarily a clinical diagnosis. Imaging confirms it, stages the disease, and guides management.

Weight-bearing plain radiographs (AP and lateral foot, AP ankle) are the most important initial imaging. Non-weight-bearing films underestimate the deformity. Key findings on the lateral view include loss of Meary angle (talo-first metatarsal angle) and reduced calcaneal pitch. The AP foot view shows talonavicular subluxation and forefoot abduction. The ankle AP shows valgus tilt in Stage IV.

Ultrasound is the practical first soft-tissue assessment in many UK pathways. It demonstrates tendinosis, partial tears, complete rupture, and tenosynovitis, and is also useful for spring ligament assessment.

MRI is the most detailed investigation, reserved for surgical planning, unclear clinical pictures, or cartilage and bone marrow assessment. CT is used for bony alignment in rigid deformity and for identifying tarsal coalition. Routine bloods are not required; consider inflammatory markers if RA is suspected.

Management is stage-dependent. UK practice follows BOFAS guidance.

Stage I (tendinosis without deformity):

• •Activity modification and supportive footwear with a firm heel counter
• •Prefabricated medial arch support initially, escalating to custom moulded orthoses with medial posting if symptoms persist
• •Short-term walking boot for 4 to 6 weeks during acute flares
• •Oral NSAIDs or paracetamol for short-term relief. Corticosteroid injection around the PTT should generally be avoided because of rupture risk
• •Address modifiable risk factors: obesity, gastrocnemius tightness

Stage II (flexible deformity):

• •Custom moulded orthoses with medial posting are the conservative mainstay; an ankle-foot orthosis (Arizona or Richie brace) provides more support
• •Structured rehabilitation and weight management
• •If conservative care fails: FDL tendon transfer with medial displacement calcaneal osteotomy is the workhorse procedure. Adjuncts include spring ligament repair, Cotton osteotomy, lateral column lengthening (Evans osteotomy), and gastrocnemius recession

Stage III (rigid deformity with arthritis):

• •Triple arthrodesis (subtalar, talonavicular, and calcaneocuboid) is the standard procedure. Selective fusion (double arthrodesis) is occasionally used
• •AFO or CROW walker for patients unfit for surgery or declining it

Stage IV requires specialist tertiary input. Refer early in Stage II to prevent progression. Urgent referral is required if a diabetic patient develops a new hot, swollen, or rapidly deforming foot to exclude Charcot neuroarthropathy.

Rehabilitation is most effective in Stage I and early Stage II. It cannot reverse established structural deformity but can slow progression and improve function alongside orthotic management.

• •Phase 1 (acute, 0 to 6 weeks): short-term immobilisation in a walking boot if needed, isometric inversion with the foot in slight plantarflexion to isolate the PTT, non-weight-bearing cardiovascular work (cycling, swimming)
• •Phase 2 (progressive strengthening, 6 to 12 weeks): resisted inversion with a band (foot plantarflexed), seated then standing double-leg heel raises, heel raises with a tennis ball between the heels to force hindfoot inversion and target the PTT, towel scrunches and short-foot exercise for intrinsic foot muscles, calf strengthening and gastrocnemius stretching if tight, hip abductor and external rotator work, single-leg balance and wobble board
• •Phase 3 (functional, 12+ weeks): single-leg heel raises as the functional goal, step-ups, lunges, single-leg squats, walking on varied terrain, progressive return to activity. Long-term orthotic use is usually required

Post-operative (FDL transfer with calcaneal osteotomy): non-weight-bearing for 0 to 6 weeks, progressive weight-bearing in a boot 6 to 12 weeks, transition to supportive footwear with orthoses 12 to 24 weeks, return to full activity at 6 to 12 months. Post-arthrodesis pathways are more prolonged and require lifelong supportive footwear.

• •BOFAS (UK) - adult acquired flatfoot guidance supports stage-dependent management; early referral in Stage II prevents progression to rigid deformity.
• •Johnson and Strom (1989), modified by Myerson - the standard four-stage classification that drives management decisions in UK practice.
• •Bluman, Title and Myerson (2007) - refinement of Stage II into IIa and IIb based on forefoot abduction, guiding choice of osteotomy.
• •Deland (2008) - review establishing the spring ligament and the broader ligamentous complex as central to the deformity, supporting the modern PCFD terminology.
• •BOFAS UK safety consensus - urgent assessment for Charcot neuroarthropathy in any diabetic patient with a new hot, swollen, or rapidly deforming foot.

• •PTTD is the leading cause of adult acquired flatfoot; the modern umbrella term is Progressive Collapsing Foot Deformity (PCFD), but PTTD remains widely tested.
• •The single heel raise test is the most useful functional clinical test; inability indicates Stage II or beyond.
• •Flexible versus rigid is the critical distinction: flexible (Stage II) responds to conservative care or joint-sparing surgery; rigid (Stage III) usually requires fusion.
• •FDL tendon transfer with medial displacement calcaneal osteotomy is the workhorse surgical procedure for Stage II; triple arthrodesis is the standard for Stage III.
• •Corticosteroid injection should generally be avoided around the PTT because of rupture risk; obesity is the strongest modifiable risk factor.
• •A diabetic patient with a new hot, swollen, or rapidly deforming foot requires urgent assessment for Charcot neuroarthropathy.