Biomechanical Evaluation of Circumtibial and Transmembranous Routes for Posterior Tibial Tendon Transfer for Dropfoot

Clinical practice guidelines for the diagnosis and management of Charcot-Marie-Tooth disease

INTRODUCTION

Charcot-Marie-Tooth (CMT) disease is classified considering the neurophysiological and histological findings, the inheritance pattern and the underlying genetic defect. In recent years, with the advent of next generation sequencing, genetic complexity has increased exponentially, expanding the knowledge about disease pathways, and having an impact in clinical management. The aim of this guide is to offer recommendations for the diagnosis, prognosis, monitoring and treatment of this disease in Spain.

MATERIAL AND METHODS

This consensus guideline has been developed by a multidisciplinary panel encompassing a broad group of professionals including neurologists, neuropediatricians, geneticists, rehabilitators, and orthopaedic surgeons.

RECOMMENDATIONS

The diagnosis is based in the clinical characterization, usually presenting with a common phenotype. It should be followed by an appropriate neurophysiological study that allows for a correct classification, specific recommendations are established for the parameters that should be included. Genetic diagnosis must be approached in sequentially, once the PMP22 duplication has been ruled out if appropriate, a next generation sequencing should be considered taking into account the limitations of the available techniques. To date, there is no pharmacological treatment that modifies the course of the disease, but symptomatic management is important, as are the rehabilitation and orthopaedic considerations. The latter should be initiated early to identify and improve the patient's functional impairments, including individualised exercise guidelines, orthotic adaptation, and assessment of conservative surgeries such as tendon transpositions. The follow-up of patients with CMT is exclusively clinical, ancillary testing are not necessary in routine clinical practice.

Charcot-Marie-Tooth Disease: A Surgical Algorithm

In Charcot-Marie-Tooth (CMT) cavovarus surgery, a regimented approach is critical to create a plantigrade foot, restore hindfoot stability, and generate active ankle dorsiflexion. The preoperative motor examination is fundamental to the algorithm, as it is not only guides the initial surgical planning but is key in the decision making that occurs throughout the operation. Surgeons need to be comfortable with multiple techniques to achieve each surgical goal. There is no one operation that works for all patients with CMT. A plantigrade foot is the most important of the surgical goals as hindfoot stability and ankle dorsiflexion can be augmented with bracing.

Evaluation and Management of Adult Footdrop

Footdrop is a common musculoskeletal condition defined by weakness in ankle joint dorsiflexion. Although the etiology varies, footdrop is characterized by specific clinical and gait abnormalities used by the patient to overcome the loss of active ankle dorsiflexion. The condition is often associated with deformity because soft-tissue structures may become contracted if not addressed. Patients may require the use of special braces or need surgical treatment to address the notable level of physical dysfunction. Surgical treatment involving deformity correction to recreate a plantigrade foot along with tendon transfers has been used with notable success to restore a near-normal gait. However, limitations and postoperative dorsiflexion weakness have prompted investigation in nerve transfer as a possible alternative surgical treatment.

Posterior Tibial Tendon Transfer for the Correction of Drop Foot

BACKGROUND

Drop foot is a crippling condition that often requires surgical intervention to restore functional dorsiflexion. Although transfer of the posterior tibial (PT) tendon has been well described for the treatment of drop foot, there is no consensus on whether tendon transfers affecting the ankle joint sufficiently restore functional status for daily activities. In addition, most studies have focused on drop foot caused by peripheral nerve disorders. The purpose of this study was to evaluate the functional outcomes and patient satisfaction following PT tendon transfer for the correction of drop foot resulting from both peripheral and central neurologic causes.

METHODS

Patients with drop foot who underwent a PT tendon transfer were followed for a minimum of 1 year and investigated retrospectively. Outcome measures included the American Orthopaedic Foot & Ankle Society ankle and hindfoot scoring system, a patient satisfaction questionnaire, postoperative ankle range of motion, and postoperative ambulatory status.

RESULTS

We evaluated 15 feet in 14 patients at a median follow-up of 50 months. The median postoperative American Orthopaedic Foot & Ankle Society ankle and hindfoot score was 85.0. Thirteen patients (92.9%) reported that they would undergo the procedure again. The median postoperative passive ankle dorsiflexion was 5.0°, and the median postoperative passive ankle plantarflexion was 30.0°. Thirteen patients (92.9%) were able to ambulate postoperatively. Ten (71.4%) ambulated without the use of an ankle-foot orthosis (AFO), and three (21.4%) ambulated with the use of an AFO. Overall, orthoses were able to be discontinued in 73.3% of the cases.

CONCLUSIONS

Our results suggest that the PT tendon transfer is an effective procedure for the treatment of drop foot that can improve the patient's functional status and ability to ambulate. The majority of patients were able to discontinue the use of their AFO postoperatively.

Palliative surgery for foot drop

Dysfunction of the common peroneal nerve is the most common mononeuropathy in the lower limb and a source of significant disability for patients. The nerve can be damaged at various levels for various reasons (direct or indirect trauma, extrinsic compression, anatomical variant, endocrine, rheumatological, or neurological disease). Clinical evidence of foot drop with steppage gait is very typical. Conservative treatment should be considered as a first step (avoidance of the contributing factors, functional rehabilitation, foot drop brace ± injection). If properly conducted conservative treatment is not successful, palliative surgery is indicated: either tendon transfer using the posterior tibial tendon or ankle arthrodesis.

Transfer of the Posterior Tibial Tendon for Chronic Peroneal Nerve Palsy

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The common peroneal nerve (CPN) is one of the most frequently injured nerves of the lower extremity.

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One-third of patients who develop CPN palsy proceed to chronic impairment without signs of recovery.

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Ankle-foot orthoses can provide improvement with respect to gait dysfunction and are useful as a nonsurgical treatment option.

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Severe cases of CPN palsy demonstrating no signs of recovery may require operative intervention with tendon transfer.

Current Concepts Review: Common Peroneal Nerve Palsy After Knee Dislocations

Dislocation of the native knee represents a challenging injury, further complicated by the high rate of concurrent injury to the common peroneal nerve (CPN). Initial management of this injury requires a thorough neurovascular examination, given the prevalence of popliteal artery injury and limb-threatening ischemia. Further management of a knee dislocation with associated CPN palsy requires coordinated care involving the sports surgeon for ligamentous knee reconstruction and the peripheral nerve surgeon for staged or concurrent peroneal nerve decompression and/or reconstruction. Finally, the foot and ankle surgeon is often required to manage a foot drop with a distal tendon transfer to restore foot dorsiflexion. For instance, the Bridle Procedure-a modification of the anterior transfer of the posterior tibialis muscle, under the extensor retinaculum, with tri-tendon anastomosis to the anterior tibial and peroneus longus tendons at the anterior ankle-can successfully return patients to brace-free ambulation and athletic function following CPN palsy. Cross-discipline coordination and collaboration is essential to ensure appropriate timing of operative interventions and ensure maintenance of passive dorsiflexion prior to tendon transfer.

Anterior Tibial Tendon Side-to-Side Tenorrhaphy after Posterior Tibial Tendon Transfer: A Technique to Improve Reliability in Drop Foot after Common Peroneal Nerve Injury

Common peroneal nerve injury is present in 40% of knee dislocations, and foot drop is the principal complication. Posterior tibial tendon transfer is a viable solution to replace the function of the anterior tibial tendon (ATT) in the mid-foot. Several techniques for posterior tibial tendon transfer exist today, with variable results reported. However, adding augmentation with side-to-side tenorrhaphy of ATT to the transferred posterior tibial tendon (PTT) enhances anterior tissue balance and load sharing stress between native ATT enthesis and PTT tenodesis, allowing early rehabilitation and improving functional outcomes. Side-to-side tenorrhaphy is performed after PTT tenodesis in the lateral cuneiform to improve reliability in foot drop. This technique allows shorter immobilization time (from 6 to 2 weeks), earlier rehabilitation, sooner weight-bearing, and decreased risk of arthrofibrosis, scar formation, and muscle atrophy.

Single versus double tendon transfer for foot drop due to post-traumatic common fibular nerve palsy

PURPOSE

To compare functional outcomes of single versus double tendon transfer for foot drop correction and toe drop prevention in posttraumatic common fibular nerve palsy.

METHODS

A retrospective study was conducted on data from patients with posttraumatic common fibular nerve palsy treated by tendon transfer between 2001 and 2018. In cases of single tendon transfer (STT) the tibialis posterior (TP) tendon was transferred anteriorly through the interosseous membrane to a new insertion on the lateral cuneiform. In cases of double tendon transfer (DTT), the same TP tendon transfer was combined with a transfer of the flexor digitorum longus to the extensor digitorum longus and extensor hallucis longus tendons. Functional assessment was based on the Carayon score to evaluate foot drop correction and on the Yeganeh score to evaluate toe drop prevention.

RESULTS

A total of 27 patients were included: 13 in the STT group and 14 in the DTT group. Functional results were comparable between groups in terms of reduction of foot drop, active range of ankle motion and Carayon score. Prevention of toe drop, active toe extension and Yeganeh score were significantly greater in the DTT group, however, active toe extension of was only restored in only 8 cases in the DTT group.

CONCLUSIONS

Double transfer of TP and FDL tendons is a reliable method to restore balanced ankle dorsiflexion and prevent toe drop. However, recovery of active toe extension was inconsistent and Carayon scores were not superior to those obtained with a single TP tendon transfer.

Posterior Tibial Tendon Transfer for Common Peroneal Nerve Injury

Common peroneal nerve dysfunction after a multiligament knee injury can be devastating. In patients with persistent foot drop, posterior tibial tendon transfer to the dorsum of the foot is a reliable and safe procedure to restore dorsiflexion. These authors favor passing the posterior tibial tendon through the interosseous membrane and docking it into the lateral/middle cuneiforms. A Strayer procedure or tendo-Achilles lengthening must be performed in patients unable to achieve at least 10° of passive dorsiflexion. Despite the operative limb having 30% to 40% of ankle dorsiflexion strength of the uninjured limb, short- and long-term functional outcomes are excellent.

A Consensus Statement on the Surgical Treatment of Charcot-Marie-Tooth Disease

BACKGROUND

Charcot-Marie-Tooth (CMT) disease is a hereditary motor-sensory neuropathy that is often associated with a cavovarus foot deformity. Limited evidence exists for the orthopedic management of these patients. Our goal was to develop consensus guidelines based upon the clinical experiences and practices of an expert group of foot and ankle surgeons.

METHODS

Thirteen experienced, board-certified orthopedic foot and ankle surgeons and a neurologist specializing in CMT disease convened at a 1-day meeting. The group discussed clinical and surgical considerations based upon existing literature and individual experience. After extensive debate, conclusion statements were deemed "consensus" if 85% of the group were in agreement and "unanimous" if 100% were in support.

CONCLUSIONS

The group defined consensus terminology, agreed upon standardized templates for history and physical examination, and recommended a comprehensive approach to surgery. Early in the course of the disease, an orthopedic foot and ankle surgeon should be part of the care team. This consensus statement by a team of experienced orthopedic foot and ankle surgeons provides a comprehensive approach to the management of CMT cavovarus deformity.

LEVEL OF EVIDENCE

Level V, expert opinion.

[Effectiveness of tibialis posterior tendon transfer for foot drop secondary to peroneal nerve palsy]

Objective

To investigate the effectiveness of tibialis posterior tendon transfer for foot drop secondary to peroneal nerve palsy.

Methods

The clinical data of 21 patients with unilateral foot drop secondary to peroneal nerve palsy between October 2009 and September 2016 was retrospectively analyzed. There were 12 males and 9 females with an average age of 32.1 years (range, 23-47 years). The causes of peroneal nerve injury were iatrogenic injury in 7 cases, tibiofibular fractures combined with compartment syndrome in 5 cases, nerve exploration surgery after stab or cut injury in 3 cases, direct violence in 4 cases, and the fibular head fracture in 2 cases. The average time from injury to operation was 5.6 years (range, 2-8 years). There was 1 case of hallux valgus and 5 cases of toe flexion contracture. The American Orthopaedic Foot and Ankle Society (AOFAS) ankle and hindfoot scores, Foot and Ankle Ability Measure (FAAM) scores, range of motion (ROM), and dorsiflexion strength of ankle joint were used to evaluated the ankle function. Radiographic evaluation for the changes of postoperative foot alignment included Meary angle, calcaneal pitch angle, and hindfoot alignment angle.

Results

All incisions healed by first intention. All patients were followed up 18-42 months (mean, 30.2 months). The dorsiflexion strength of ankle joint recovered from grade 0 to grade 3-4 after operation. There was no patient with a postoperative flat foot deformity and claw toe during follow-up. There was no significant difference in Meary angle, calcaneal pitch angle, and hindfoot alignment angle between pre- and post-operation ( P>0.05). The AOFAS score, FAAM score, and ROM of dorsiflexion significantly improved at last follow-up when compared with preoperative values ( P<0.05); while there was no significant difference in ROM of plantar-flexion between pre- and post-operation ( t=4.239, P=0.158). There were significant differences in AOFAS score, FAAM score, and ROM of dorsiflexion between affected and healthy sides ( P<0.05); but no significant difference in ROM of plantar-flexion was found ( t=2.319, P=0.538).

Conclusion

Tibialis posterior tendon transfer is an effective surgical option for foot drop secondary to peroneal nerve palsy. And no postoperative flat foot deformity occurred at short-term follow-up.

Extensor Tendon Transfers for Treatment of Foot Drop in Charcot-Marie-Tooth Disease: A Biomechanical Evaluation

BACKGROUND

In Charcot-Marie-Tooth (CMT) disease, selective weakness of the tibialis anterior muscle often leads to recruitment of the long toe extensors as secondary dorsiflexors, with subsequent clawing of the toes. Extensor hallucis longus (EHL) and extensor digitorum longus (EDL) tendon transfers offer the ability to augment ankle dorsiflexion and minimize claw toe deformity. The preferred site for tendon transfer remains unknown. Our goal was to quantify ankle dorsiflexion in the "intact" native tendon state, compared with tendon transfers to the metatarsal necks or the cuneiforms. We hypothesized that EHL and EDL transfers would improve ankle dorsiflexion as compared with the intact state and would produce similar motion when anchored at the metatarsal necks or cuneiforms.

METHODS

Eight fresh-frozen cadaveric specimens transected at the midtibia were mounted into a specialized jig with the ankle held in 20 degrees of plantarflexion. The EHL and EDL tendons were isolated and connected to linear actuators with suture. Diodes secured on the first metatarsal, fifth metatarsal, and tibia provided optical data for tibiopedal position in 3 dimensions. After preloading, the tendons were tested at 25%, 50%, 75%, and 100% of maximal physiologic force for the EHL and EDL muscles, individually and combined.

RESULTS

Transfers to metatarsal and cuneiform locations significantly improved ankle dorsiflexion compared with the intact state. No difference was observed between these transfer sites. Following transfer, only 25% of maximal force by combined EHL and EDL was required to achieve a neutral foot position.

CONCLUSION

Transfer of the long toe extensors, into either the metatarsals or cuneiforms, significantly increased dorsiflexion of the ankle.

CLINICAL RELEVANCE

The transferred extensors can serve a primary role in treating foot drop in CMT disease, irrespective of the presence of clawed toes. This biomechanical study supports tendon transfers into the cuneiforms, which involves less time, fewer steps, and easier tendon balancing without compromising dorsiflexion power.