Vascular density of the posterior tibial tendon: a cadaver study

The tibialis posterior tendon footprint: an anatomical dissection study

BACKGROUND

The tibialis posterior tendon (TPT) is the main dynamic stabilizer of the medial longitudinal arch of the foot. Especially in adult acquired flatfoot deformity (AAFD) the TPT plays a detrimental role. The pathology and function of the tendon have been extensively investigated, but knowledge of its insertional anatomy is paramount for surgical procedures. This study aimed to analyze the complex distal footprint anatomy of the TPT.

METHODS

Forty-one human anatomical specimens were dissected and the distal TPT was followed to its bony footprints. After tendon removal the footprints were marked with ink. Standardized photographs were taken and consecutively analyzed by digital imaging measurements. Footprint length, width, area of insertion, location, and shape was studied regarding the main insertion at the navicular bone.

RESULTS

All specimens had the main TPT insertion at the navicular bone (41/41, 100%). Sixty-three percent of navicular TPT insertions were located at the plantar aspect. The mean navicular footprint measured 12.1 mm × 6.9 mm in length and width, respectively. The tendon further spread into several slips which anchored the tibialis posterior deep in the plantar arch. TPT insertions were highly variable with an involvement of up to eight distinct bony footprints in the mid- and hindfoot. The second most common additional footprint was the lateral cuneiform (93% of dissected feet), followed by the medial cuneiform (80%), the metatarsal bases [1-5] (80%), the cuboid (46%), the intermediate cuneiform (19%), and the calcaneus (12%).

CONCLUSIONS

The present study adds to current knowledge on the footprint anatomy of the TPT. Based on the findings of this study we advocate a plantar location of flexor digitorum longus tendon transfer in flexible AAFD in order to restore the anatomical lever and insertion of the TPT.

Biomechanics and Orthotic Treatment of the Adult Acquired Flatfoot

The adult acquired flatfoot deformity resulting from posterior tibial tendon dysfunction is the result of rupture of the posterior tibial tendon as well as key ligaments of the ankle and hindfoot. Kinematic studies have verified certain levels of deformity causing hindfoot eversion, lowering of the medial longitudinal arch and forefoot abduction. The condition is progressive and left untreated will cause significant disability. Bracing with ankle-foot orthoses has shown promising results in arresting progression of deformity and avoiding debilitating surgery. Various types of ankle-foot orthoses have been studied in terms of effects on gait as well as efficacy in treatment.

Posterior tibial tendinopathy: what are the risk factors?

BACKGROUND

Posterior tibial tendinopathy (PTT) is the most common cause of acquired (progressive) flatfoot deformity in adults. To date, PTT research has mainly focused on management rather than on causal mechanisms. The etiology of PTT is likely to be multifactorial because both intrinsic and extrinsic risk factors have been reported. We sought to critically evaluate reported etiologic factors for PTT and consider the concept of genetic risk factors.

METHODS

A detailed review of the literature published after 1936 was undertaken using English-language medical databases.

RESULTS

No clear consensus exists as to the relative importance of the risk factors reported, and neither has any consideration been given to a possible genetic basis for PTT.

CONCLUSIONS

To date, studies have examined various intrinsic and extrinsic risk factors implicated in the etiology of PTT. The interaction of these factors with an individual's genetic background may provide valuable data and help offer a more complete risk profile for PTT. A properly constructed genetic association study to determine the genetic basis of PTT would provide a novel and alternative approach to understanding this condition.

Arterial anatomy of the tibialis posterior tendon

BACKGROUND

Tibialis posterior tendon dysfunction is a common disorder leading to pain, deformity, and disability, although its pathogenesis is unclear. A vascular etiology has been proposed, but there is controversy regarding the existence of a hypovascular region that may render the tendon vulnerable. The purpose of this study was to provide a description of the arterial anatomy supplying the tibialis posterior tendon.

METHODS

Sixty adult cadaveric lower extremities were obtained from a university-affiliated body donation program. Thirty specimens obtained within 72 hours of death were used for microscopic analysis. Thirty specimens were previously frozen and used for macroscopic analysis. The tibialis anterior, tibialis posterior, and peroneal arteries were injected with India Ink and Ward's Blue Latex. The specimens used for macroscopic analysis were debrided with sodium hypochlorite to expose the extratendinous anatomy. For the microscopic analysis, the tendon was cleared using a modified Spälteholz technique to expose the intratendinous vascular anatomy.

RESULTS

Macroscopically, an average of 2.5 ± 0.7 vessels entered the tendon proximal to the navicular insertion. In all, 28/30 (93.3%) specimens had a vessel entering 4.1 ± 0.6 cm proximal to the medial malleolus and 24/30 (80.0%) specimens had a vessel entering 1.7 ± 0.9 cm distal to the medial malleolus. Microscopically, an average of 1.9 ± 0.3 vessels entered each tendon proximal to the navicular insertion. In total, 27/30 (90%) specimens had a vessel entering the tendon 4.8 ± 0.8 cm proximal to the medial malleolus and 30/30 (100%) specimens had a vessel entering the tendon 1.9 ± 0.8 cm distal to the medial malleolus. In all specimens, a hypovascular region was observed, starting 2.2 ± 0.8 cm proximal to the medial malleolus and ending 0.6 ± 0.6 cm proximal to the medial malleolus with an average length of 1.5 ± 1.0 cm. The insertion of the tendon was well vascularized both on microscopic and macroscopic specimens.

CONCLUSION

The tibialis posterior tendon was supplied by 2 vessels entering the tendon approximately 4.5 cm proximal and 2.0 cm distal to the medial malleolus. A retromalleolar hypovascular region was observed.

CLINICAL RELEVANCE

Improved understanding of the vascularity of the tibialis posterior tendon may be helpful in clinical practice and potentially provides a basis for further evaluation of the causative factors of tibialis posterior tendinopathy.

Posterior tibial tendoscopy

The posterior tibial tendon (PTT) helps the triceps surae to work more efficiently during ambulation. Disorders of the PTT include tenosynovitis, acute rupture, degenerative tears, dislocation, instability, enthesopathies, and chronic tendinopathy with dysfunction and flat foot deformity. Open surgery of the PTT has been the conventional approach to deal with these disorders. However, tendoscopy has become a useful technique to diagnose and treat PTT disorders. This article focuses on PTT tendoscopy and tries to provide an understanding of the pathomechanics of the tendon, indications for surgery, surgical technique, advantages, complications, and limitations of this procedure.

Association between leg length discrepancy and posterior tibial tendon dysfunction

BACKGROUND

Leg length discrepancy (LLD) is associated with a variety of orthopaedic disorders and biomechanical gait changes that involve possible overload of the posterior tibial tendon (PTT). In view of the biomechanical disturbances induced by LLD, an association may exist between LLD and PTT dysfunction (PTTD).

PURPOSE

To compare the frequency and magnitude of LLD between subjects with and without PTTD and ascertain whether associations exist between clinical features and presence of dysfunction.

STUDY DESIGN

Case-control study.

METHODS

A total of 118 patients with a diagnosis of PTTD were seen between January 2009 and September 2012 and compared with 118 gender-matched and race-matched volunteers. The frequency of LLD, the mean absolute LLD, and the mean relative LLD were measured by conventional (radiographic) or computed tomography scanography and compared between cases and controls.

RESULTS

The prevalence of LLD and mean absolute and relative LLD values were significantly greater in the case group (94.9%, 5.64 mm and 7.36%, respectively) than in the control group (79.7%, 3.28 mm and 4.18%, respectively) (P < .001).

CONCLUSION

The findings of this study demonstrate a relationship between LLD and PTTD. In light of the major biomechanical changes it induces, LLD may be a predisposing factor for development of PTTD.

Posterior tibial tendoscopy: Description of an accessory proximal portal and assessment of tendon vascularization lesion according to portal

BACKGROUND

Posterior tibial tendoscopy was codified in 1997 by Van Dijck, who described a portal between 1.5 and 2cm proximally and distally to the tip of the medial malleolus. However, this approach does not allow proximal exploration of the posterior tibial tendon (PTT). We here describe an accessory portal 7cm proximal to the medial malleolus, enabling complete PTT exploration.

METHODS

Posterior tibial tendoscopy was performed on 12 cadaver specimens, mapping PTT exploration and vascularization.

RESULTS

The accessory portal enabled the whole PTT to be explored, from the myotendinous junction to the entry into the retromalleolar groove. PTT observation quality was improved compared to using a submalleolar portal. Dissection confirmed systematic presence of a vincula on the posterior side of the tendon, connected to the flexor digitorum longus (FDL) tendon, containing collateral vessels of the posterior tibial artery. None of these elements were damaged by the tendoscopy as long and the scope and motorized instruments were not rotated on the posterior side of the supramalleolar part of the PTT.

CONCLUSIONS

This accessory entry portal provides complete PTT exploration without the risk of neurovascular bundle lesion.

Effect of extra-osseous talotarsal stabilization on posterior tibial tendon strain in hyperpronating feet

Posterior tibial tendon dysfunction is considered one of the most common causes of progressive adult acquired flatfoot deformity. The etiology leading to the dysfunction of posterior tibial tendon remains controversial. The purpose of this study was to quantify strain on the posterior tibial tendon in cadaver feet exhibiting hyperpronation caused by flexible instability of the talotarsal joint complex. We hypothesized that posterior tibial tendon strain would decrease after a minimally invasive extra-osseous talotarsal stabilization procedure. A miniature differential variable reluctance transducer was used to measure the elongation of posterior tibial tendon in 9 fresh-frozen cadaver specimens. The elongation was measured as the foot was moved from its neutral to maximally pronated position, before and after intervention with the HyProCure(®) extra-osseous talotarsal stabilization device. The mean elongation of the posterior tibial tendon (with respect to a fixed reference point) was found to be 6.23 ± 2.07 mm and 3.04 ± 1.85 mm, before and after intervention, respectively (N = 27; variation is ± 1 SD). The average elongation reduced by 51% and was statistically significant with p < .001. Strain on the posterior tibial tendon is significantly higher in hyperpronating feet. An extra-osseous talotarsal stabilization procedure reduces excessive abnormal elongation of the posterior tibial tendon by minimizing excessive abnormal pronation. This minimally invasive procedure may thus provide a possible treatment option to prevent or cure posterior tibial tendon dysfunction in patients exhibiting flexible instability of the talotarsal joint complex.

Posterior tibial tendon dysfunction: a review

Posterior tibial tendon dysfunction is a progressive deformity that can result in the development of a pathologic flatfoot deformity. Numerous publications have studied the effects of clinical interventions at specific stages of progression of posterior tibial tendon dysfunction, but there is still uncertainty regarding the clinical identification of the condition. It is clear that more information regarding the etiology, progression, and risk factors of posterior tibial tendon dysfunction is required. Clear evidence exists that suggests that the quality of life for patients with posterior tibial tendon dysfunction is significantly affected. Furthermore, evidence suggests that early conservative intervention can significantly improve quality of life regarding disability, function, and pain. This would suggest that significant cost burden reductions could be made by improving awareness of the condition, which would improve early diagnosis. Early conservative intervention may help reduce the number of patients requiring surgery. This review focuses on the etiologic factors, epidemiologic features, and pathogenesis of posterior tibial tendon dysfunction. It aims to analyze, discuss, and debate the current understanding of this condition using the available literature. In addition, there is a discussion of the evidence base surrounding disease characteristics associated with the different clinical stages of posterior tibial tendon dysfunction.

Estrogen receptor expression in posterior tibial tendon dysfunction: a pilot study

BACKGROUND

The pathophysiology of posterior tibial tendon dysfunction (PTTD) is poorly understood. It has been theorized that changes in hormone physiology may be a factor influencing tendon health. Estrogen's influence on the fibroblast has been studied in other musculoskeletal tissues. Gender differences in anterior cruciate ligament (ACL) injuries have been studied and it has been discovered that the Estrogen receptor (ER) as well as Progesterone receptor (PR) are expressed in the ACL.

MATERIAL AND METHODS

Eight patients with PTTD requiring surgery were enrolled in our pilot study. The mean patient age was 52.4 (range, 18 to 73) years. There were five female and three male patients. Tendon samples were harvested from diseased PTT. Tendon samples harvested from healthy PTT and healthy flexor digitorum longus (FDL) tendon were used as controls. Tendon samples were processed using specific protocols for total RNA isolation from hypocellular, dense connective tissues. ERα and ERβ transcripts were quantified using real time RT-PCR. Quantitative values were obtained from the threshold cycle (Ct) number at which the increase in fluorescent signal associated with an exponential increase of PCR products can be detected.

RESULTS

Transcripts of both ERα and ERβ were reproducibly detected in RNA samples isolated from our tendon samples. There was no difference in receptor expression between diseased and control tendon samples. There was no difference in receptor expression between male and female patients.

CONCLUSION

We found that the tenocyte of the PTT and FDL tendons express ERα and ERβ. Normal and diseased tendons of both male and female patients expressed both estrogen receptors.

CLINICAL RELEVANCE

Identifying ERα and ERβ gene expression in the fibroblast was an initial step in discovering whether tenocytes are targets for estrogen function. Estrogen receptors were identified indirectly by measuring receptor gene expression but we were unable to show a significant difference between diseased and control tendons.

[Tenocytes and the extracellular matrix : a reciprocal relationship]

The characteristic cells in tendons and ligaments are called tenocytes, which are responsible for the formation and turnover of the extracellular matrix. They react to external stimuli and facilitate the functional adaptation of the proteoglycan and collagen network to mechanical requirements. Via numerous cellular processes they form a complex communicating network which demonstrates coordinated directional reactions. As is common to all tissues in the human body, tendons are subject to age changes which influence the tenocytes, but additionally the structural organization and hence the function of the extracellular matrix. The function and organization of tendons are also affected by mechanical forces, as well as by various cytokines produced in the tissue and by the application of anti-inflammatory medication.

Effects of posterior tibial tendon augmented with biografts and calcaneal osteotomy in stage II adult-acquired flatfoot deformity

Adult-acquired flatfoot deformity (AAFD) is a well-known condition leading to flexible flatfoot deformity. However, only recently have the function and muscle strength for balancing opposing muscles been more appreciated in laboratory studies. With the advancements in collagen science in tendon structure, the rationale and concept of some of the most common procedures in tendon transfer have been challenged. The current availability of biograft technology has provided an alternative in augmentation procedures instead of sacrificing autologous tendons. This novel approach may offer a viable option in AAFD, delivering much-needed collagen in a degenerative tendon. These biografts have shown ease of use and tissue biocompatibility in many orthopaedic and plastic surgery procedures and may prove to be an adjunct in the surgical option for AAFD.

Revision of failed flatfoot surgery

Revision of failed flatfoot surgery presents a unique and challenging dilemma for the foot and ankle surgeon. Revision surgery is focused on establishing a plantigrade foot with correction of the hindfoot valgus, midfoot abduction, and forefoot varus. Successful reconstruction of failed flatfoot surgery begins with a proper evaluation. No treatment algorithm exists for the management of the malaligned flatfoot. Patient complaints, an understanding of the initial deformity and biomechanical problems, and surgeon experience play a role in correction of failed flatfoot surgery.

Structure-function relationships in tendons: a review

The purpose of the current review is to highlight the structure-function relationship of tendons and related structures to provide an overview for readers whose interest in tendons needs to be underpinned by anatomy. Because of the availability of several recent reviews on tendon development and entheses, the focus of the current work is primarily directed towards what can best be described as the 'tendon proper' or the 'mid-substance' of tendons. The review covers all levels of tendon structure from the molecular to the gross and deals both with the extracellular matrix and with tendon cells. The latter are often called 'tenocytes' and are increasingly recognized as a defined cell population that is functionally and phenotypically distinct from other fibroblast-like cells. This is illustrated by their response to different types of mechanical stress. However, it is not only tendon cells, but tendons as a whole that exhibit distinct structure-function relationships geared to the changing mechanical stresses to which they are subject. This aspect of tendon biology is considered in some detail. Attention is briefly directed to the blood and nerve supply of tendons, for this is an important issue that relates to the intrinsic healing capacity of tendons. Structures closely related to tendons (joint capsules, tendon sheaths, pulleys, retinacula, fat pads and bursae) are also covered and the concept of a 'supertendon' is introduced to describe a collection of tendons in which the function of the whole complex exceeds that of its individual members. Finally, attention is drawn to the important relationship between tendons and fascia, highlighted by Wood Jones in his concept of an 'ectoskeleton' over half a century ago - work that is often forgotten today.

Calcaneal osteotomies for the treatment of adult-acquired flatfoot

Calcaneal osteotomies are useful procedures for the treatment of stage 2 adult-acquired flatfoot. Often combined with adjunctive soft-tissue procedures, the posterior calcaneal displacement osteotomy and Evans procedure provide effective realignment of pes planovalgus deformity. Preoperative evaluation, indications, contraindications, surgical considerations and techniques are discussed.

Biomechanics and clinical analysis of the adult acquired flatfoot

The adult acquired flatfoot is a deformity that results from the loss of dynamic and static supportive structures of the medial longitudinal arch. The severity of the deformity is dependent upon the role of ligamentous disruption on the hindfoot that can be determined by careful clinical examination. Treatment of the adult flatfoot requires an understanding of the biomechanical effects of deforming forces, tendon dysfunction, ligament disruption, and joint sublaxation.