(iii) Entrapment neuropathies of the foot and ankle

Anatomical study and branching point of neurovascular structures at the medial side of the ankle

Nerve entrapment and blood circulation impairment associated with the medial side of the ankle are not uncommon. The purpose of this study was to describe the anatomical basis of neurovascular structures of the medial ankle which comprised the number, origin, branching pattern, and branching point. Forty feet of fresh cadavers were examined by using 2 reference lines: the malleolar-calcaneal (MC) and navicular-calcaneal (NC) axes. We recorded number, origin, length of the 2 axes, the locations and widths of neurovascular structures on MC and NC axes, the branching point of neurovascular structures, and the branching pattern of neurovascular structures was recorded and was separated into 5 types. The posterior tibial nerve (PTN) bifurcated to plantar and calcaneal nerves and branched proximally to the tarsal tunnel (TT). The posterior tibial artery bifurcated to plantar and calcaneal arteries and branched inferiorly to PTN and within the TT. The calcaneal nerves and arteries had more variation of number and origin. The most common branching point of calcaneal nerves and arteries is within the TT, except the medial calcaneal nerve. It branched proximally to the TT. The anatomical knowledge from this study is important for the diagnosis and treatment of clinicians.

The clinical diagnosis of symptomatic forefoot neuroma in the general population: a Delphi consensus study

BACKGROUND

There is limited evidence for defining what specific method or methods should be used to clinically influence clinical decision making for forefoot neuroma. The aim of this study was to develop a clinical assessment protocol that has agreed expert consensus for the clinical diagnosis of forefoot neuroma.

METHODS

A four-round Delphi consensus study was completed with 16 expert health professionals from either a clinical or clinical academic background, following completion of a structured literature review. Clinical experience ranged from 5 to 34 years (mean: 19.5 years). Consensus was sought on the optimal methods to achieve the clinical diagnosis of forefoot neuroma. Round 1 sought individual input with an open ended question. This developed a list of recommendations. Round 2 and 3 asked the participants to accept or reject each of the recommendations in the list in relation to the question: "What is the best way to clinically diagnose neuroma in the forefoot?" Votes that were equal to or greater than 60% were accepted into the next round; participant's votes equal to or less then 20% were excluded. The remaining participant's votes between 20 to 60% were accepted and placed into the following round for voting. Round 4 asked the participants to rank the list of recommendations according to the strength of recommendation they would give in relation to the question: "What is the best way to clinically diagnose neuroma in the forefoot?" The recruitment and Delphi rounds were conducted through email.

RESULTS

In round 1, the 16 participants identified 68 recommendations for the clinical diagnosis of forefoot neuroma. In round 2, 27 recommendations were accepted, 11 recommendations were rejected and 30 recommendations were assigned to be re-voted on. In round 3, 36 recommendations were accepted, 22 recommendations were rejected and 11 recommendations were assigned to be re-voted on. In round 4, 21 recommendations were selected by the participants to form the expert derived clinical assessment protocol for the clinical diagnosis of forefoot neuroma. From these 21 recommendations, a set of themes were established: location of pain, non weight bearing sensation, weight bearing sensation, observations, tests and imaging.

CONCLUSION

Following the identification of 21 method recommendations, a core set of clinical diagnostic methods have been prepared as a clinical assessment protocol for the diagnosis of forefoot neuroma. Based on expert opinion, the core set will assist clinicians in forming a clearer diagnosis of forefoot neuroma.

Fine dissection of the tarsal tunnel in 60 cases

The fine dissection of nerves and blood vessels in the tarsal tunnel is necessary for clinical operations to provide anatomical information. A total of 60 feet from 30 cadavers were dissected. Two imaginary reference lines that passed through the tip of the medial malleolus were applied. A detailed description of the branch pattern and the corresponding position of the posterior tibial nerve, posterior tibial artery, medial calcaneal nerve and medial calcaneal artery was provided, and the measured data were analyzed. Our results can be summarized as follows. I. A total of 81.67% of the bifurcation points of the posterior tibial nerve, which was divided into the medial and lateral plantar nerves, were located within the tarsal tunnel, not distal to the tarsal tunnel. II. The bifurcation points of the posterior tibial artery were all located in the tarsal tunnel. Almost all of the bifurcation points of the posterior tibial artery were lower than those of the posterior tibial nerve. The bifurcation point of the posterior tibial artery situated distal to the tarsal tunnel was not found. III. The number and the origin of the medial calcaneal nerves and arteries were highly variable.

Tarsal tunnel syndrome-A narrative literature review

BACKGROUND

Tarsal tunnel syndrome is classified as a focal compressive neuropathy of the posterior tibial nerve or one of its associated branches individually or collectively. The tunnel courses deep to fascia, the flexor retinaculum and within the abductor hallucis muscle of the foot/ankle. The condition is rare and regularly under-diagnosed leading to a range of symptoms affecting the plantar margins of the foot. There are many intervention strategies for treating tarsal tunnel syndrome with limited robust evidence to guide the clinical management of this condition. The role of conservative versus surgical interventions at various stages of the disease process remains unclear, and there is a need for a structured, step-wise approach in treating patients with this syndrome based on derived empirical evidence. This narrative review attempts to scrutinize the literature to date by clarifying initial presentation, investigations and definitive treatment for the purpose of assisting future informed clinical decision and prospective research endeavours.

PROCESS

The literature searches that have been incorporated in compiling a rigorous review of this condition have included: the Cochrane Neuromuscular Group's Specialized Register (Cochrane Library 2013), the databases of EMBASE, AMED, MEDLINE, CINAHL, Physiotherapy evidence database (PEDRO), Biomed Central, Science Direct and Trip Database (1972 to the present). Reference listings of located articles were also searched and scrutinized. Authors and experts within the field of lower-limb orthopaedics were contacted to discuss applicable data. Subject-specific criteria searches utilizing the following key terms were performed across all databases: tarsal tunnel syndrome, tibial neuralgia, compression neuropathy syndromes, tibial nerve impingement, tarsal tunnel neuropathy, entrapment tibial nerve, posterior tibial neuropathy. These search strategies were modified with differing databases, adopting specific sensitivity-searching tools and functions unique to each. This search strategy identified 88 journal articles of relevance for this narrative literature review.

FINDINGS

This literature review has appraised the clinical significance of tarsal tunnel syndrome, whilst assessing varied management interventions (non-surgical and surgical) for the treatment of this condition in both adults and children. According to our review, there is limited high-level robust evidence to guide and refine the clinical management of tarsal tunnel syndrome. Requirements for small-scaled randomized controlled trials in groups with homogenous aetiology are needed to analyse the effectiveness of specific treatment modalities.

CONCLUSIONS

It is necessary that further research endeavours be pursued for the clinical understanding, assessment and treatment of tarsal tunnel syndrome. Accordingly, a structured approach to managing patients who have been correctly diagnosed with this condition should be formulated on the basis of empirical evidence where possible.

Entrapment of the superficial peroneal nerve: an anatomical insight

Entrapment of the superficial peroneal nerve is an uncommon neuropathy that may occur because of mechanical compression of the nerve, usually at its exit from the crural fascia. The symptoms include sensory alterations over the distribution area of the superficial peroneal nerve. Clinical examination, electrophysiologic findings, and imaging techniques can establish the diagnosis. Variations in the superficial peroneal sensory innervation over the dorsum of the foot may lead to variable results during neurologic examination and variable symptomatology in patients with nerve entrapment or lesions. Knowledge of the nerve's anatomy at the lower leg, foot, and ankle is of essential significance for the neurologist and surgeon intervening in the area.

Fascial entrapment of the sural nerve and its clinical relevance

Sural nerve presents great topographic variability and it is responsible for sensory innervation of the posterolateral side of the distal third of the leg and lateral aspect of the foot. Entrapment of the nerve could be caused by compression due to fascial thickening, while the symptomatology includes sensory alterations and deficits at the nerve distribution area. We report a cadaveric case of a variant sural nerve that presented a distinct entrapment site. A supernumerary sensory branch was encountered originating from the common peroneal nerve, while the peroneal component of the sural nerve was observed to take a course within a fibrous fascial tunnel 3.1 cm in length that caused nerve fixation and flattening. The tension applied to the aforementioned branch was shown to worsen during passive forcible foot plantaflexion and inversion. The etiology, diagnosis and the treatment options are discussed comprehensively.