Pes Planus M21.40 734

synonyms: flatfoot, flexible acquired flatfoot deformity, rigid flatfoot deformity, adult-acquired flafoot deformity

Flatfoot ICD-10

• M21.40:Flat foot [pes planus] (acquired), unspecified foot
• M21.41: Flat foot [pes planus] (acquired), right foot
• M21.42: Flat foot [pes planus] (acquired), left foot
• Q66.50: Congenital pes planus, unspecified foot
• Q66.51: Congenital pes planus, right foot
• Q66.52: Congenital pes planus, left foot

Flatfoot ICD-9

• 734 (flat foot)

Flatfoot Etiology / Epidemiology / Natural History

• May be caused by rupture of the posterior tibial tendon, degenerative arthritis of the midfoot or hindfoot, diabetic Charcot neuroarthropathy, or inflammatory arthritis of the hindfoot.
• Etiology: obesity, diabetes, accessory navicular, inflammatory arthritis, and steroid injections

Flatfoot Anatomy

• Posterior tibial tendon insufficiency, the most frequent cause of flatfoot deformity, leads to attenuation of the medial supporting structures of the foot, lowering of the longitudinal arch, heel valgus alignment, and ultimately hindfoot and ankle arthritis.
• Spring ligament (calcaneonavicular) extends from the anterior aspect of the sustentaculum tali to the plantar medial surface of the navicular.  Supports the plantar medial margin of the talar head. Two main components: superomedial calcaneonavicular ligament and inferior calcaneonavicular ligament.
• Superomedial calcaneonavicular ligament (one of the tow main portions of the Spring ligament) is commonly attenuated or torn in adult-acquired flatfoot deformity. 
• Distal portion of the deltoid ligament blends into the spring ligament and is also frequently attenuated in adult-acquired flatfoot deformity.

Flatfoot Clinical Evaluation

• inability to perform a single leg heel rise with the affected limb.
• Late symptoms: lateral calcaneofibular impingement with collapse of the arch and difficulty with ambulation.
• Variable amounts of forefoot abduction occur, leading to the "too many toes" sign.

Flatfoot Xray / Diagnostic Tests

• Weight-bearing A/P, lateral and oblique xrays indicated: generally show lowering of the longitudinal arch, decrease in calcaneal pitch, increase of the talometatarsal angle, and uncovering of the talonavicular joint with increasing forefoot abduction.
• Advanced cases, attenuation of the deltoid ligament leads to valgus tilting of the ankle mortise.

Flatfoot Classification/Treatment

• Stage I:pain and swelling of the medial ankle region, with pain progressing into the arch. Treatment: Immobilization and nonsteroidal antiinflammatory drugs (NSAIDs). Custom-molded orthotic insoles or a University of California Biomechanics Laboratory type orthosis also may be useful. Surgical treatment is indicated if nonsurgical measures have failed.
• Stage II:dynamic hindfoot valgus deformity, attenuation of the spring ligament, and progressive flattening of the longitudinal arch.
• Stage III: fixed hindfoot valgus deformity.  Dysfunction of the posterior tibial tendon, rigid valgus deformity of the hindfoot, and arthritic changes of the hindfoot joints.  Treatment = arthrodesis.  If degenerative changes affect the subtalar and Chopart joints treatment = triple arthrodesis.
• Stage IV: secondary changes of the ankle joint and stretching of the deltoid ligament.
• Flexible (arch reconstitutes with NWB)-RX=shoe with supportive arch or molded arch support of both, +/- gastroc/soleus stretching
• Rigid-subtalar and midtarsal joints cannot reach neutral.  Forefoot pronated.  Can be undiagnosed tarsal coalition.  RX=medial sole and heel wedges (1/8-3/16”).  Semirigid molded insoles. Gastroc-soleus stretching.  If severely painful-double-upright brace with a locked ankle, inside T-strap, and rigid rocker sole (or similar AFO).  Subtalar vs triple arthrodesis.
• Surgical treatment options: posterior tibial tendon débridement or flexor digitorum longus transfer alone in patients with tenosynovitis and preserved architecture of the hindfoot. Once the heel has progressed into valgus deformity, a flexor digitorum tendon transfer to the navicular along with a medial calcaneal slide osteotomy to shift the axis of the Achilles tendon medially. Consider lengthening of the Achilles tendon if contracture is present. In patients with a rigid deformity and arthritis of the hindfoot, arthrodesis is indicated. Fusion of the subtalar, talonavicular, calcaneocuboid joints, or combinations of these are used to stabilize the hindfoot. Lateral column lengthening through an osteotomy of the calcaneal neck or calcaneocuboid fusion may also be useful in conjunction with flexor digitorum longus tendon transfer

Flatfoot Associated Injuries / Differential Diagnosis

Flatfoot Complications

Flatfoot Follow up  care

Flatfoot References

• Myerson MS, Badekas A, Schon LC. Treatment of stage II posterior tibial tendon deficiency with flexor digitorum longus tendon transfer and calcaneal osteotomy. Foot Ankle Int. 2004 Jul;25(7):445-50.
• Pinney SJ, Lin SS. Current concept review: acquired adult flatfoot deformity. Foot Ankle Int. 2006 Jan;27(1):66-75. 
• Sammarco GJ, Hockenbury RT. Treatment of stage II posterior tibial tendon dysfunction with flexor hallucis longus transfer and medial displacement calcaneal osteotomy. Foot Ankle Int. 2001 Apr;22(4):305-12. 
• Sands AK, Tansey JP. Lateral column lengthening. Foot Ankle Clin. 2007 Jun;12(2):301-8
• Evans D: Calcaneo-valgus deformity.  J Bone Joint Surg 1975;57B:270-278.
• Horton GA, Olney BW: Triple arthrodesis with lateral column lengthening for treatment of severe planovalgus deformity.  Foot Ankle Int 1995;16:395-400.
• Mosca VS: Calcaneal lengthening for valgus deformity of the hindfoot: Results in children who had severe, symptomatic flatfoot and skewfoot.  J Bone Joint Surg 1995;77A:500-512.
• Pomeroy GC, Pike RH, Beals TC, Manoli A 2nd. Acquired flatfoot in adults due to dysfunction of the posterior tibial tendon. J Bone Joint Surg Am. 1999 Aug;81(8):1173-82.
• Pfeffer G, Easley M, Frey C, Hintermann B, Sands A, eds. Operative Techniques: Foot and Ankle Surgery. Philadelphia, PA: Saunders Elsevier; 2010:622-652
• Gazdag AR, Cracchiolo A 3rd. Rupture of the posterior tibial tendon. Evaluation of injury of the spring ligament and clinical assessment of tendon transfer and ligament repair. J Bone Joint Surg Am. 1997 May;79(5):675-81