Pathology of the posterior tibial tendon in posterior tibial tendon insufficiency

Stage IV posterior tibial tendon insufficiency: the tilted ankle

Stage IV PTTD is the most challenging of the posterior tibial tendon deficiencies. The combination of a flattened longitudinal arch and a tilted ankle make successful management unpredictable. Conservative management universally fails and surgical options have been limited to pantalar and tibiotalocalcaneal arthrodesis. Alternatives to surgical management included herein are unproven, but provide a potential solution beyond that of arthrodesis.

Controversies in surgical reconstruction of acquired adult flat foot deformity

There is a wide variety of approaches to the surgical treatment of acquired adult flat foot deformity. There are controversies in several areas, including disagreement over the cause of the condition, the structures that are involved, and what is the most appropriate surgical procedure or combination of procedures to successfully treat this condition. Trends in the orthopedic foot and ankle community include an attempt to preserve the hindfoot joints to allow for more normal biomechanics, the correction of bony deformities so that soft tissues are not overloaded, and an attempt to address the underlying cause so that the propensity for the deformity to recur is lessened.

Medial-sided bony procedures: why, what, and how?

The adult acquired flat foot deformity is a common clinical entity; rupture or incompetence of the posterior tibial tendon is a frequent cause. The natural history is characterized by progressively worsening deformity and early recognition is important. Nonoperative treatment can alleviate symptoms and control progression in nearly all stages of the disease. Should this fail to control symptoms or prevent progression of deformity, operative intervention should be considered. In stage I disease, exploration and debridement, with or without FDL tendon transfer, is a viable option. In stage II disease, the PTT becomes elongated and the medial soft tissues become attenuated. Exploration and debridement of the PTT is performed, but frequently a FDL tendon transfer or side-to-side anastomosis is required. It has been shown that soft tissue procedures alone may fail to correct deformity and this can lead to deterioration of results over time. Combined procedures, including soft tissue reconstructions to restore PTT function and bony procedures to correct deformity, have become popular. When the PTT is intact and degeneration or elongation is minimal, as in stage I or early stage II disease, reconstruction of the medial column with advancement of an osteoperiosteal flap based on the PTT insertion, combined with selective arthrodeses of the medial column, may be considered. These procedures have been well described for the treatment of symptomatic flexible flat foot in children and adolescents but experience in adults is lacking. Although it may be theoretically possible to passively correct hindfoot valgus with these procedures, it seems prudent to limit the indications to patients who have early disease accompanied by an isolated midfoot sag. In more advanced stage II disease, correction of deformity with a tendon transfer combined with a medial displacement calcaneal osteotomy or a lateral column lengthening is currently recommended. This allows for correction of deformity while sparing the hindfoot joints, which may be particularly important in young or active patients. Short-term studies showed excellent results, but long-term results are lacking. In stage III disease, in which the deformity is fixed, arthrodesis is the procedure of choice. Isolated talonavicular arthrodesis has been shown to correct nearly all aspects of the deformity with long-lasting results. This procedure results in nearly complete lack of hindfoot motion and may predispose the patient to adjacent joint arthrosis. In a patient who has stage III disease with arthrosis confined to the talonavicular joint, isolated talonavicular arthrodesis may be considered. This clinical situation is rare, and, in most patients, a triple arthrodesis is probably preferred. If residual deformity is present after these procedures, it must be addressed. Residual medial column instability may be addressed by adding a selective arthrodesis of the naviculo-cuneiform or first metatarsocuneiform joint, whereas residual forefoot varus or supination may be addressed with selected midfoot fusions with or without a cuneiform osteotomy.

Intermediate term follow-up of calcaneal osteotomy and flexor digitorum longus transfer for treatment of posterior tibial tendon dysfunction

Twenty-three patients with stage II posterior tibial tendon dysfunction who had failed non-surgical therapy were treated with flexor digitorum longus transfer and calcaneal osteotomy. At latest follow-up averaging 35 +/- 7 months (range, 24 to 51 months), 22 patients (96%) were subjectively "better" or "much better." No patient had difficulty with shoe wear; however, four patients (17%) required routine orthotic use consisting of a molded shoe insert. AOFAS scores were available on 21 patients and improved from a preoperative mean of 50 +/- 14 (range, 27 to 85) to a postoperative mean of 89 +/- 10 (range, 70 to 100). Our experience, at an intermediate date follow-up is that calcaneal osteotomy and flexor digitorum longus transfer is a safe and effective form of treatment for stage II posterior tibial tendon dysfunction.

Changes in collagen matrix composition in human posterior tibial tendon dysfunction

OBJECTIVE

To investigate whether tendon degeneration in posterior tibial tendon dysfunction syndrome is associated with changes in extracellular matrix collagen composition.

METHODS

Specimens from grossly abnormal tendon regions from 9 patients with posterior tibial tendon dysfunction syndrome were prepared for routine histology. Collagens I, III and V were typed by immunoblotting and quantified by densitometry after SDS-PAGE. Proline and hydroxyproline residues were determined by liquid chromatography. Four other samples from grossly normal homologous tendon regions and one surgical specimen from a healthy patient undergoing arthrodesis of the ankle after an accident were included as control.

RESULTS

In the grossly abnormal surgical posterior tibial tendon specimens we observed three types of histopathologic conditions present to varying degrees: increased mucin content, fibroblast hypercellularity and neovascularization. Analysis of degenerate tendons demonstrated a 79.3% increase in total proline and a 32.4% increase in 4-hydroxyproline. In addition, damaged tissue contained a higher proportion of collagen type III (mean increase: 53.6%) associated with a concomitant increase in type V collagen (mean increase: 26.4%). These alterations were accompanied by a reduction in type I collagen (mean decrease: 41.4%).

CONCLUSIONS

In posterior tibial tendon dysfunction syndrome, the degenerative process results from marked changes in both structural organization and molecular composition of matrix collagens. The higher proportion of type V and type IlI collagens in degenerated tendons is likely to contribute to a decrease in the mechanical resistance of the tissue.

Tibialis posterior insufficiency occurring in a patient without peronei: a mechanical etiology

A patient presented with a painful flatfoot deformity, which developed after the onset of a drop-foot secondary to a herniated lumbar disk. On examination, the only functioning muscles were her gastrocnemius-soleus complex and her intrinsic toe flexors. Her affected foot had taken the classic deformity seen with tibialis posterior dysfunction--a valgus heel, midfoot collapse and an abducted forefoot. Peroneus brevis was not functioning and therefore could not be implicated as part of the etiology of this patient's acquired flatfoot deformity. The mechanism in which the ground reaction force produces the foot deformity in a tibialis posterior insufficient foot will be presented.

Intermediate follow-up on the double osteotomy and tendon transfer procedure for stage II posterior tibial tendon insufficiency

26 patients with 28 pes planovalgus feet secondary to Johnson stage 2 posterior tibial tendon insufficiency were treated with flexor digitorum longus tendon transfer, lateral column lengthening, medial displacement calcaneal osteotomy, and heel cord lengthening. The mean patient age at surgery was 48.5 years. The AOFAS ankle-hindfoot scale was applied postoperatively to assess clinical outcome. Preoperative and postoperative standing radiographs of the foot and ankle were analyzed to determine radiographic correction of the pes planovalgus deformities. The mean follow-up to date is 5 years. The mean ankle-hindfoot score was 90 postoperatively. The medial cuneiform to fifth metatarsal distance improved from -0.2 mm preoperatively to 7.6 mm postoperatively. Similarly, the talonavicular distance improved from 19.4 mm preoperatively to 10.9 postoperatively. There were no nonunions. Four feet (14%) displayed radiographic signs of calcaneocuboid arthritis at follow-up. Only one was symptomatic requiring calcaneocuboid joint fusion. The double osteotomy technique provides symptomatic relief and lasting correction of the pes planovalgus deformity associated with stage 2 posterior tibial tendon insufficiency at intermediate follow-up. It has a high patient satisfaction based on the AOFAS ankle-hindfoot scale and radiographic measurements demonstrate maintenance of correction of the adult acquired flatfoot.

Operative treatment of the difficult stage 2 adult acquired flatfoot deformity

In the flexible pes planovalgus deformity of stage 2 posterior tibial tendon dysfunction, osteotomies appear to have a significant role in operative management by restoring more normal biomechanics, allowing tendon transfers to function successfully. The options when considering osteotomies for stage 2 disease include lateral column lengthening, medial displacement calcaneal osteotomy, and combined double osteotomy technique. The tight Achilles tendon should be lengthened as well. Lateral column lengthening has been used extensively for treatment of flexible flatfeet. It has been shown clinically and radiographically to address all 3 components of the pes planovalgus deformity present in stage 2 posterior tibial tendon dysfunction. Lateral column lengthening is used in combination with a medial soft tissue rebalancing procedure. The mechanism of action is still speculative but clearly is not owing to tensioning of the plantar fascia as previously thought. Despite the excellent correction of foot posture obtained by use of lateral column lengthening for adult acquired flatfoot, many clinicians have reservations about its use because of reported secondary increases in the calcaneocuboid joint pressures. This increase in pressure has been shown to occur experimentally, increasing the potential risk of calcaneocuboid joint arthrosis. This experimental evidence is supported by Phillips' study of the original Evans procedure, which resulted in a 65% incidence of calcaneocuboid joint arthrosis at 13-year follow-up. Mosier-LaClair et al reported a 14% incidence of calcaneocuboid joint arthritis at 5-year follow-up after double osteotomy for stage 2 posterior tibial tendon dysfunction. This incidence has not been proved true in the remainder of the literature surrounding this procedure and its use for flexible flatfoot. To address the concern regarding potential calcaneocuboid arthrosis secondary to lateral column lengthening, calcaneocuboid joint distraction arthrodesis has been explored as an alternative technique. The results show good initial correction, but the follow-up is extremely limited, and one study reported loss of correction over time. Longer follow-up is needed to determine whether or not this technique would provide the lasting correction seen with the Evans procedure. Calcaneocuboid joint lengthening arthrodesis does result in some limitation of adjacent hindfoot motion. Although this limitation is significantly less compared with talonavicular and subtalar joint fusion, this procedure may result in increased local pressures and arthrosis of the midfoot or hindfoot. For the above-mentioned reasons, longer follow-up studies are needed to determine whether calcaneocuboid joint distraction arthrodesis would prove to be a reliable and safe alternative for lateral column lengthening in the treatment of adult acquired flatfoot. Medial displacement calcaneal osteotomy has been used for correction of the pes planovalgus foot in posterior tibial tendon dysfunction. It has been used extensively for the surgical treatment of flexible flatfoot throughout the literature. Medial displacement osteotomy, in combination with flexor digitorum longus tendon transfer, can address all 3 components of adult acquired flatfoot. It does not recreate the medial longitudinal arch in all patients, however. Although the mechanism of action of medial displacement calcaneal osteotomy is unknown, it has been proved that it is not through the tightening of the plantar fascia in a windlass effect as previously thought. In contrast to lateral column lengthening, however, medial displacement calcaneal osteotomy does address the deforming valgus force of the Achilles tendon. Functionally transferring the insertion of the Achilles tendon medially removes a constant valgus-deforming force. The osteotomy can then act as a double tendon transfer with the flexor digitorum longus tendon to aid in foot inversion. For stage 2 posterior tibial tendon insufficiency, the authors favor the combination double osteotomy technique with a flexor digitorum longus tendon-to-medial cuneiform tendon transfer, débridement or removal of the posterior tibial tendon, and percutaneous heel cord lengthening. Early results were positive at 1.5 years after surgery with respect to maintenance of correction and functional improvement with no evidence of calcaneocuboid arthrosis. More recently, the intermediate 5-year follow-up has been assessed for this combination of procedures, and similar results were found. There was a high rate of patient satisfaction and functional improvement, and surgical correction of the flatfoot deformity was maintained and compared favorably with the contralateral normal foot. Although the intermediate follow-up found a 14% incidence of calcaneocuboid arthrosis, 50% of these patients had preoperative evidence of calcaneocuboid joint arthritis. (ABSTRACT TRUNCATED)

Treatment of stage 3 adult acquired flatfoot

Stage 3 adult acquired flatfoot occurs when chronic posterior tibial tendon insufficiency results in fixed hindfoot valgus or fixed forefoot abduction and supination. Nonoperative management results in limited success. Corrective fusion is the treatment of choice. Although a variety of arthrodeses have been employed, triple arthrodesis remains the gold standard.

Pathoanatomy and etiology of posterior tibial tendon dysfunction

Posterior tibial tendon dysfunction is a cause of painful acquired flatfoot in adults. It is associated with progressive collapse of the medial longitudinal arch, hindfoot valgus, and forefoot abduction deformities. The clinical manifestations and surgical treatment have been well documented in the literature. Epidemiologic studies have not shown any clear predisposing factors to the disease. Numerous etiologies have been proposed to explain the clinical evidence of tendon degeneration found at the time of surgery including trauma, anatomic, mechanical inflammatory, and ischemic factors. Although previously thought to be secondary to an inflammatory process resulting in acute and chronic tendinitis, more recent histopathologic evidence has revealed a degenerative tendinosis with a nonspecific reparative response to tissue injury characterized by mucinous degeneration, fibroblast hypercellularity, chondroid metaplasia, and neovascularization. These pathologic changes result in marked disruption in collagen bundle structure and orientation. This may compromise the tendon and predispose it to rupture under physiologic loads. However, it cannot be determined whether these changes precede or postdate posterior tibial tendon dysfunction. It seems that there are many contributing factors to the etiology of posterior tibial tendon dysfunction all culminating in a common disease process with resulting tendon degeneration and an insufficient repair response.