PTTD (Posterior tibial tendon dysfunction) insufficiency is the most common cause of adult acquired flatfoot deformity. Failure of the tendon affects surrounding ligamentous structures and will eventually lead to bony involvement and deformity. The extent this disease progression will be explained in this review. PTTD is a progressive and debilitating disorder, which can be detrimental to patients due to limitations in mobility, significant pain, and weakness.[rx] Risk factors for the disease have been studied and may include hypertension, obesity, diabetes, previous trauma, or steroid exposure.[rx]
Posterior tibialis tendon dysfunction is a primary soft tissue tendinopathy of the posterior tibialis that leads to altered foot biomechanics. Although the natural history of posterior tibialis tendon dysfunction is not fully known, it has mostly been agreed that it is a progressive disorder. While clinical examination is important in diagnosing adult acquired flat-feet; further investigation is often required to delineate the different aetiologies and stage of the disease. The literature describes many different management choices for the different stages of posterior tibialis tendon dysfunction.
Staging of PTTD
Stage 1
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Normal radiographs, able to perform single-heel raise, and mild tenosynovitis
Stage 2A
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Arch collapse on a radiograph, unable to perform single-heel raise, and a flexible flatfoot deformity
Stage 2B
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Arch collapse and talonavicular uncoverage (over 40%) on a radiograph, unable to perform single heel raise, flexible flatfoot deformity, and characteristic forefoot abduction or “too many toes” sign[rx]:
Stage 3
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Subtalar arthritis on a radiograph, unable to perform single heel raise, flatfoot deformity with rigid forefoot abduction and hindfoot valgus
Stage 4
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Valgus deformity of talus in the ankle mortise visualized on AP radiograph of the ankle – talar tilt due to deltoid ligament compromise, subtalar arthritis on radiographs, unable to perform single heel raise, flatfoot deformity with rigid forefoot abduction and hindfoot valgus[rx]
Causes of PTTD
Researchers have proposed numerous mechanisms for the degeneration of the posterior tibial tendon (PTT). Most commonly the cause for PTT degeneration is credited to a repetitive loading causing microtrauma and progressive failure. A trimalleolar, hypovascular region does exist and may also contribute to the disease. In a study by Manske et al., cadaver specimens showed a region of decreased blood supply from 2.2 +/- 0.8cm proximal to the medial malleolus to a region 0.6 +/- 0.6cm proximal to the medial malleolus.[rx]
The anatomic course of the posterior tibial tendon also likely contributes as the tendon does make an acute turn around the medial malleolus. This location puts a significant amount of tension on the tendon in the region distal and posterior to the medial malleolus. The adjacent tendons, namely the flexor hallucis longus and the flexor digitorum longus, do not take this sharp turn.[rx]
Other potential culprits include constriction beneath the flexor retinaculum,[rx] abnormal anatomy of the talus,[rx] degenerative changes associated with osteoarthritis,[rx] and preexisting pes planus.[rx]
Symptoms of PTTD
The symptoms of PTTD may include pain, swelling, a flattening of the arch and an inward rolling of the ankle. As the condition progresses, the symptoms will change.
- Pain over the tendon in the inner part of your hindfoot (rear portion of your foot) and midfoot is the first common symptom.
- A deformity in the foot may develop, and this can make it difficult for you to walk. A common deformity is for the foot to sag downward and inward toward the opposite foot.
- As the tendon degenerates and loses its function, ligaments on the same inner side of the foot will also deteriorate and fail. Ligaments are soft tissues that hold bones in place. When they fail, those bones shift out of place, leading to a deformity. This deformity causes malalignment of the foot bones, which leading puts more stress on the already failing ligaments. This snowball effect of degeneration can significantly affect how you move.
- For example, when PTTD initially develops, there is pain on the inside of the foot and ankle (along the course of the tendon). In addition, the area may be red, warm and swollen.
- Later, as the arch begins to flatten, there may still be pain on the inside of the foot and ankle. But at this point, the foot and toes begin to turn outward and the ankle rolls inward.
As PTTD becomes more advanced, the arch flattens even more and the pain often shifts to the outside of the foot, below the ankle. The tendon has deteriorated considerably, and arthritis often develops in the foot. In more severe cases, arthritis may also develop in the ankle.
Diagnosis of PTTD
History and Physical
- The majority of posterior tibial tendon dysfunction patients will demonstrate medial ankle and foot pain, especially in the early stages of the disease. At later stages, lateral pain can be seen as well, due to sub-fibular impingement or peroneal tendon injury.[rx]
- A thorough physical examination can help to determine the grading and severity of the disease. Attention should first be turned to the gross inspection of the feet while standing. A weight-bearing examination is of importance as a flexible deformity may present normally, while the patient is non-weight bearing.
- The medial longitudinal arch collapse leads to pes planus, an easily visualized condition. While inspecting the patient, one will also commonly see a “too many toes” sign, which is visible when looking from behind the patient. Due to the valgus alignment of the foot, you will see flaring out of more than two toes from the lateral hindfoot. Equinus contracture is also a common finding, which can limit ankle dorsiflexion.
- Single-limb heel raise is an important clinical test that can differentiate stage 1 disease from stage 2 and higher. A patient in stage 1 disease should be able to perform this test without pain. In stage 2 disease, patients may be able to perform the test but will likely have pain. In later stages, the rigid deformity may prevent the patient from completing the test. The flexibility of the foot also requires evaluation on an exam.[rx]
Evaluation
Imaging is critical in determining the severity of disease and subsequent treatment.
- Anteroposterior (AP) and lateral radiographs are necessary. Increased talonavicular uncoverage and increased talo-first metatarsal angle (or Simmons angle) will present on the AP foot radiograph. The normal talo-first metatarsal angle is around 7 degrees, and angles over 16 degrees indicate flatfoot deformity.[rx]
- The talonavicular coverage expresses itself as the amount of the talus that is not in contact with the navicular medially, with values over 30 to 40% typically indicated forefoot abduction seen in stage II-IV PTTD.[rx]
- On the weight-bearing lateral radiograph, one should evaluate for increased talo-first metatarsal angle (or Meary angle) which normally measures 0 degrees +/- 4 degrees but typically measures over 20 degrees in flatfoot deformity.[rx]
Special tests for PTTD/AAFD include
- The too many toes sign – the foot should be inspected from behind and above. The too many toes sign is a manner of inspection from behind. In this manner, they can establish if there is abduction of the forefoot and a valgus angulation of the hindfoot. It is based on how many toes you can see from behind. By an affected foot, it will be more than one and a half to two toes see also Foot Posture Index
- Double leg heel rise – to go with both feet from a flatfoot stance to standing on the toes. Patients in stage I dysfunction can do this, but it’s painful. Patients with stage II, III or IV dysfunction are unable to do a heel raise. When a patient stands on tiptoes the heel of the affected foot will not bend inwards; the normal foot will stay into inversion while the affected hindfoot will stay in valgus.
- A single-leg heel raise – patients can’t do a single heel raise with the affected foot;
- The first metatarsal rise sign – the patient stands on both feet, the shin of the affected foot is taken with a hand and rotated externally. When the patient has PTTD, the head of the metatarsal I is lifted, while normal metatarsal I stay on the ground;
- Plantarflexion and inversion of the foot against resistance – to test the power of the tibialis posterior
Treatment of PTTD
In many cases of PTTD, treatment can begin with non-surgical approaches that may include:
- Orthotic devices or bracing – To give your arch the support it needs, your foot and ankle surgeon may provide you with an ankle brace or a custom orthotic device that fits into the shoe.
- Immobilization – Sometimes a short-leg cast or boot is worn to immobilize the foot and allow the tendon to heal, or you may need to completely avoid all weight-bearing for a while.
- Physical therapy – Ultrasound therapy and exercises may help rehabilitate the tendon and muscle following immobilization.
- Medications – Nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, help reduce pain and inflammation.
- Shoe modifications – Your foot and ankle surgeon may advise changes to your shoes and may provide special inserts designed to improve arch support.
Treatment for posterior tibial tendon dysfunction is a complicated subject, so this review will attempt to simplify by each stage for the reader:
All Stages initially
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Conservative management with NSAIDs and activity modification. Also meant for non-surgical candidates or low demand, elderly patients.[rx]
Stage 1
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Conservative management through immobilization in a walking boot or cast for up to 3 to 4 weeks to allow for healing of the posterior tibial tendon may be warranted followed eccentric strengthening with physical therapy.[1]
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If immobilization and physical therapy are successful, transitioning into custom-molded orthotics or AFO is appropriate to maintain relief. Emphasis on medial forefoot posting is critical. University of California Biomechanics Laboratory (UCBL) orthoses are a form of a custom insert with a lace-up component that can help maintain midfoot height.[rx]
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Conservative therapy should be for 3 to 4 months, and if it fails, then surgical intervention may be warranted. A tenosynovectomy, with tubularization, may be indicated.
Stage 2A
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Conservative immobilization and physical therapy with orthotics or ankle-foot orthosis (AFO) as recommended in stage 1
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Surgical treatment involves medial calcaneal osteotomy with posterior tendon debridement and repair. Ancillary procedures may include any or all of the following: flexor digitorum tendon (FDL) transfer, spring ligament reconstruction, or Achilles tendon lengthening.[rx]
Stage 2B
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All of the previously listed procedures in Stage 2A +/- lateral column lengthening, or isolated subtalar joint arthrodesis
Stage 3
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Conservative therapies, as mentioned above.
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Surgical treatment is often warranted as it involves rearfoot arthritic changes and a medial double arthrodesis or triple arthrodesis common (subtalar, calcaneocuboid, and talonavicular arthrodesis) is indicated with or without deltoid ligament repair.[rx]
Stage 4
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Conservative therapies, as mentioned above.
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Surgical treatment is often necessary as it involves arthritic changes in the ankle, as well as rearfoot. Surgical options include any combination of Triple arthrodesis with Achilles tendon lengthening, deltoid ligament reconstruction, and total ankle arthroplasty with replacement.[rx] Medial double arthrodesis, deltoid ligament reconstruction, and total ankle arthroplasty with a replacement if ankle deformity is reducible. If the patient is a candidate for total ankle arthroplasty, then it is recommended to stage procedure by performing rearfoot arthrodesis and soft tissue balancing followed by a second stage 4 to 8 weeks later for total ankle arthroplasty
Surgical Techniques
FDL transfer
- indications
- FDL is synergistic with tibialis posterior and therefore transfer can augment function of deficient PT
- Stage II disease
- relative contraindications
- rigidity of subtalar joint (<15 degrees of motion)
- fixed forefoot varus deformity (>10-12 degrees)
- technique
- find FDL and FHL at knot of Henry
- insert FDL into navicular near insertion of PT
- vs. FHL transfer
- FHL is more complicated to mobilize and has not shown improved results
- in the midfoot, FHL runs under FDL
Calcaneal osteotomy
- indicated to correct hindfoot valgus
- techniques include medial displacement calcaneal osteotomy (MDCO) used in stage IIA (insignificant forefoot abduction) Evans lateral column lengthening osteotomy
- used in stage IIB (significant forefoot abduction)
- may require additional MDCO to correct the deformity
- overlengthening may be corrected by a first TMT fusion or medial cuneiform osteotomy
- TAL or gastrocnemius recession
- indicated for equinus contracture
- Forefoot correction osteotomy
- indicated for fixed forefoot supination/varus (stage IIC)
- plantarflexion (dorsal opening-wedge) medial cuneiform (Cotton) osteotomy used with a stable medial column (navicular is colinear with first MT) corrects residual forefoot varus after hindfoot correction is made surgically medial column fusion (isolated first TMT fusion, isolated navicular fusion, or combined TMT and navicular fusions) used with an unstable medial column (plantar sag at first TMT and/or naviculocuneiform joint)
- Spring ligament repair
- indicated with spring ligament rupture in some cases
- PTT debridement
- may also be required
- Triple arthrodesis
- triple arthrodesis includes calcaneocuboid, talonavicular, subtalar joints
- additional medial column stabilization may be required
Physical Therapy Management
The key to a successful outcome is early detection of the dysfunction and conservative management to prevent chronicity.
The goals of nonoperative treatment include the
- Elimination of clinical symptoms,
- Improvement of hindfoot alignment, and the
- Prevention of progressive foot deformity.
- Patient education re: Activity restriction and modification
- Providing relief through prescriptions for medial arch support insoles or custom orthotics (necessary in many cases).
Conservative management with physiotherapy and orthotics for Stage I and II is the first option. [rx]. Options include:
- Orthotic devices or bracing – to support the arch.
- A walking cast or CAM boot – can be used to immobilize the foot. If this brings relief, the patient can have shoe inserts or modifications, orthotics or an ankle-foot orthosis (AFO) fitted.
- Achilles tendon stretching – and tibialis posterior strengthening, concentric/eccentric training of the posterior tibialis. along with nonsteroidal anti-inflammatories[rx]
- Immobilization – a short-leg cast or boot, it allows the tendon to heal, or avoid all weight-bearing.
- Shoe modifications – advise changes such as special inserts designed to improve arch support. [rx]
- Toe Pick-Ups – The exercise consists of picking up small objects such as pebbles, marbles or tiny toys with your toes and depositing them in a bucket or other container.
- Arch Strengthening Caterpillar – the arch strengthening caterpillar exercise begins by lying on your back with your knees bent and your feet flat on the floor about two feet from your butt. Lift both foot arches and pull your toes back toward your heels. Relax your arches and slide your feet slightly back toward your butt. Repeat the process, allowing your feet to inch closer and closer to your glutes in a caterpillar motion. Once your feet are nearly touching your butt, repeat the sequence in reverse, slowly moving your feet away from your butt in the same caterpillar motion.
- Arch Raises – Sit in a chair with your back straight, your knees bent in a 90-degree angle and your feet flat on the floor. Raise the arch of one foot off the floor without curling your toes or lifting your heel. (It’s much harder than it sounds!) When done properly, you should feel muscle strain in your foot, lower leg and thigh.
- Alphabet Writing – You can strengthen your entire foot by imagining a pencil in between your toes, pointing the toes outward and “writing” the alphabet in the air in front of you.
Up to 4 months of nonoperative treatment should be trialed; if there is no improvement after this period, a tendon synovectomy or debridement may be indicated.
Orthotics
Optimization of foot loading management by means of foot orthoses and adequate footwear is the most important aspect in therapy. Depending on the progression of the pathology, this can be progressively managed with over-the-counter non-individualized foot orthoses, then with individualized foot orthoses and finally with semi-rigid ankle-foot orthoses. For stage, I disease, nonsurgical treatment should be tried for at least 3 to 4 months. A short walking cast or removable cast boot immobilization is indicated for patients with acute tenosynovitis. If symptoms are improved after immobilization, then a custom orthotic or ankle-foot orthosis (AFO) may be fitted to the patient. The orthotic should be a full-length, semirigid, total contact insert with medial posting. The primary function of the orthotic is to provide arch support and correct the flexible component of the deformity.
Differential Diagnosis
Although posterior tibial tendon dysfunction is the most common cause of adult-acquired flatfoot deformity, there are many other related conditions. Diagnoses listed below can present very similarly to PTTD and should merit consideration during evaluation [rx]:
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Tarsal coalition
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Inflammatory arthritis
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Charcot arthropathy
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Neuromuscular disease
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Traumatic disruption of midfoot ligaments
Complications
General complications include thromboembolic events, infection, wound dehiscence, neurologic injury, and/or painful hardware. Reports exist of wound healing complications in up to one-third of patients undergoing flatfoot reconstruction, so proper wound care is paramount.[rx]
References