Tibialis Posterior Rupture - Chinmay Gupte 8/4/2002

Anatomy: T.P. tendon passes immediately behind medial malleolus and inserts into the navicular tuberosity. Acts as plantar flexor and inverter of ankle joint; antagonist to peroneus brevis.

Background

- often associated with rheumatoid hindfoot

- early in this condition there is painful swelling along posteromedial border of ankle, fatigue, & aching along medial longitudinal arch of foot;

- well into the disease process, patients may note lateral sided pain as well as pain in the sinus tarsi impingement between the lateral side of the foot and the fibula;

- degenerative tears usually occur distal to the medial malleolus, in a region which coincides with relative hypovascularity and the sharp turn of the tendon from a verticle to a horizontal position;

Pathology:

SM Mosier et al 1998: gross and histological exams were carried out on 15 normal cadavers and 15 surgical patients w/ posterior tibial tendon insufficiency (but no rupture);

- these authors noted that 12/15 cadavers had normal tendon appearance and histology, where as the surgical specimens demonstrated a degenerative tendinosis w/ increased mucin content, fibroblast hypercellularity, chondroid metaplasia, and neovascularization (the abnormal tendon segments were located between the medial malleolus and the navicular tuberosity)

- gross examination of the surgical specimens showed incomplete splitting on the deep surface;

Biomechanics : following rupture, talonavicular joint and subtalar joints collapse & hindfoot drifts into valgus, causing mid foot pronation & forefoot abduction;

- in addition, there is often injury or attenuation of the spring ligament;

- in the rheumatoid, rupture of the tibialis posterior leads to a collapsed pronated foot;

- in advanced stages, pain is present laterally, w/ an abutment between the calcaneus and the fibula;

- peroneus brevis, continues to function & pulls foot into a valgus configuration;

- in this case, flat foot may result from the peroneus brevis muscle; a natural antagonist to the tibialis posterior;

Classification

- tendinitis is present but tendon remains at its normal length;

- in a young patient consider accessory navicular

Non Operative Treatment:

- arch supports, rubber-soled shoe w/ quarter-inch medial heel, sole wedge, UCBL;

- immobilization in a short leg cast for 6 weeks;

- NSAIDS;

Surgical treatment:

- if tenosynovitis persists over several months, then consider tenosynovectomy;

- w/ intra-tendinous elogation, consider tendon advancement and reattachment to the navicular;

- w/ intra-substance elongation, it is necessary to restore the tendon to its proper tension;

Papers:

Posttraumatic posterior tibialis tendon insertional elongation with functional incompentency: A case report.

RM Marks MD and LC Schon MD. Foot and Ankle Internation. Vol 19. No 3. March 1998. p 180.

Surgical treatment of stage I posterior tibial tendon dysfunction.

Teasdall, R. D., and Johnson, K. A.: Foot and Ankle Internat.. 15:646-648, Jan., 1994. Abstract

Stage II

- inflammation causes tenosynovitis and elongation ;

- hindfoot remains supple and is reducible ;

- pt has flexible flat foot, & w/ removal of weight, foot resumes its normal arch;

- it is essential to distinguish the supple type II lesion from the the type III (fixed deformity), since the latter cannot be corrected w/ tendon transfers;

Radiographs:

- if there is medial and plantar subluxation of the talar head, then there must be failure/elongation of the spring ligament;

Management

- generally deformity will progress during this stage, even with non operative treatment;

- tendon transfer must be performed within weeks since fixed valgus deformity will occur w/ in several months;

- furthermore, tendon transfers will not correct any flat foot deformity that has already taken place;

FDL transfer

- if tendon is ruptured, joint is mobile, & no fixed deformity is present, a FDL transfer to the navicular is performed (alternatively, the surgeon may use the FHL for transfer);

S tage III

-following lengthening or rupture of tibialis posterior, pt will develop fixed hindfoot deformity w/ hindfoot valgus and forefoot in abduction;

Treatment: if site of maximal deformity is at talonavicular joint, then an isolated talonavicular or talonavicular & calcaneocuboid fusion may be performed;

- w/ more significant hindfoot valgus, subtalar arthrodesis may be indicated.

- note that complete correction of the hindfoot deformity may cause a relative supination deformity of the

forefoot (which in turn, decreases the relative amount of wt bearing of the first metatarsal);

- triple arthrodesis

- indicated only w/ severe midfoot collapse deformities;

- achilles tendon lengthening will often be required for equines deformity

Differential Diagnosis

- attenuation of the spring ligament;

- rheumatoid foot

- look for involvement in the hindfoot and talonavicular joints;

- synovitis and joint inflammation lead to weakening of these joints which results in

- hindfoot valgus deformity which resembles rupture of the tibialis posterior;

- tarsometatarsal degenerative arthitis

-relaxed pes planus

- old Lisfranc fracture dislocation

- neuroarthropathic (Charcot) involvement of the midfoot or hindfoot

- posteromedial talar osteochondral lesion

associated conditions:

- most patients will not have an associated condition;

- rheumatoid arthitis

- seronegative arthritis

Examination

- tenderness:

- w/ involvement of PT tendon tenderness will be along course of this tendon just posterior to

medial crest of distal tibia, posterior to the medial malleolus, or along undersurface of navicular;

- after the tendon has ruptured, medial sided pain may improve;

- w/ more advanced disease, lateral pain may occur from impingement of the the fibula against the calcaneus;

- this may be more severe than the medial sided pain;

- too many toes:

- when viewed from behind, affected patients may demonstrate excessive abduction of the foot, which therefore causes more toes to be seen on that side;

- this sign may not be very sensitive for posterior tib rupture (ie, some patients with documented rupture will not demonstrate this sign);

- heel rise:

- most important test;

- strength of tendon is assessed by a single heel rise test;

- this is done by asking the patient to rest his or her hands on wall while the physcian views the feet posteriorly;

- while one foot is raised, pt is first asked to go up on normal foot;

- the heel should go into inversion, following which the heel will come off the ground strongly;

- the affected heel will fail to invert, & longitudinal arch fails to rise during this maneuver;

- note that some patients will be unable to perform a correct heel rise because of a painful tibialis posterior

tendinitis (vs the inability to perform heel rise due to tendon rupture);

- motor strength:

- the foot is first positioned in plantar flexion (which eliminates the tibialis anterior as a potential foot invertor) as well as inversion;

- the examiner than attempts to evert the foot against resistance;

- evaluate for fixed deformity:

- assess for equinus contracture (w/ heel in varus)

- ROM of the ankle and subtalar joints;

- assess for relative supination deformity of the midfoot (which is revealed when the hindfoot is

placed in a corrected position);

Radiographs

- wt bearing lateral;

- talus moves into flexion when viewed laterally;

- talus will appear plantar flexed and there will be an increased angle between longitudinal axis of the talus and calcaneus;