Polio Paralysis

The Foot 15 (2005) 146–148

Post poliomyelitis invertor paralysis: Which tendon to transfer? Adnan A. Faraj ∗ The Teaching Hospital, Baghdad Medical School, Baghdad, Iraq

Abstract A prospective study was carried out on 14 patients mean age of 10 years; they were suffering from invertor muscle paralysis (both tibialis anterior and posterior) due to poliomyelitis. This study is showing the results of surgery after a follow up of 4 years (range 1–6 years). It is concluded that the peroneus brevis tendon transfer anterior to the ankle in to the base of the second metatarsal bone together with a proper sub-talar extra articular arthrodesis is consistent with good results. The outcome is poor transferring behind the medial malleolus and when peroneus longus tendon is used. © 2005 Elsevier Ltd. All rights reserved. Keywords: Poliomyelitis; Invertor paralysis; Tendon transfer

1. Introduction Paralytic valgus foot deformity develops as a sequel of poliomyelitis due to invertor weakness (both tibialis anterior and posterior) with normal evertors (peroneus longus and brevis). Associated various degrees of equinus deformity are not uncommon if there is associated weakness of the dorsiflexors. This valgus deformity of the foot is to start with a dynamic deformity caused by muscle imbalance when the evertors rotate the foot laterally with subsequent eversion at the sub-talar joint and pronation of calcaneocuboid joint (mid tarsal joint) [1]. Various procedures have been described to treat this deformity [1–6,8,9]. The present study was aimed to find out which tendon transfer is associated with the best outcome.

2. Material and methods Fourteen patients (12 females, 2 males) with an a mean age of 10 years (range of 6–14 years) presented to the Teaching Hospital related to Baghdad Medical School in the period between February 1987 till December 1990. The main complaint was difficulty in walking properly and in performing daily activities because of foot deformity. They were all ∗ Present address: 28 Colston Close, Crow Tree Lane, Bradford BD8 0BN, UK. Tel.: +44 1274481961; fax: +44 1535202098. E-mail address: [email protected].

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known to be in the residual stage of poliomyelitis. The left side was affected in 12 cases. The right side was affected in two. All cases had unilateral involvement except in one patient who had simultaneous evertor paralysis on the right side and invertor paralysis of the foot on the left side. Eight patients had associated various degrees of weakness affecting the paraspinous muscles, muscles acting around the ipsilateral hip and knee joints. All the patients had previous corrective operative procedures performed at the hip and knee joints; none however had previous surgery on the feet. The common features of presentation were limping, shoe problems, unstable foot during walking and shortening of the affected limb (range 1–3 cm). 2.1. On examination These patients had mobile planovalgus deformity of the foot with trophic changes of the skin on the medial side. All patients had complete paralysis of tibialis anterior and posterior with grade V motor power of peronei. There was a tendency for eversion at the sub-talar joint and pronation in mid tarsal joints during walking. Upon passive reduction of the subtalar joint to the neutral position a tight Achilles tendon was found in eight patients. Surgery was undertaken in all of the cases with the aim of restoring the hind foot alignment to improve the walking and to prevent skin problems. In 10 patients, there was a mild (grade III) weakness of ankle dorsiflexors (peroneus tertius

A.A. Faraj / The Foot 15 (2005) 146–148 Table 1 Axer’s grading scheme of results Grade

Criteria

Very good

The foot is stable, normal shape, movement in all or most joints is preserved, walks well without brace The foot is stable, normal shape, movement in most joints is preserved, walks with high laced shoes The foot is stable, normal shape, there may be over or under-correction of the foot deformity The foot is unstable and deformed (secondary to claw hallux)

Good Fair Bad

and toe extensors). Thirteen cases underwent peroneus brevis transfer and in one peroneus longus was transferred. Different techniques were used in order to deal with different problems (Table 1). All 14 patients also had extra-articular arthrodesis of the subtalar joint, in 13 cases performed simultaneously, and in one patient 5 months later. They all had a below knee cast for 6 weeks.

3. Results The clinical postoperative follow-up was based on the stability of the foot, the shoe wear, any special foot support, the amount of foot correction and any deformity. The grading of results was made at a mean follow up of 4 years (range 1–6 years) according to the criteria of Axer (1960) [1] (Table 1). In nine patients, subtalar arthrodesis was carried out together with peroneus brevis (PB) tendon transfer anterior to the ankle in to the medial tarsal bones was found to have been successful and rated good, according to Axer’s criteria, in nine patient. The valgus foot deformity was corrected and the power of foot dorsiflexion became stronger (grade IV) with the help of the transferred PB to the dorsum of the foot. The transferred tendon after physiotherapy started working as an ankle dorsiflexor; the PB in its normal insertion acts as an evertor (Table 2). In one case where there was mild foot dorsiflexion and invertor paralysis, the peroneus brevis was transferred to the first metatarsal, without subtalar extraarticular arthrodesis. The result of this was bad using Axer’s

147

criteria. The foot became unstable, and the valgus deformity increased, this happened as the transferred PB acted as an evertor, moving the foot outwards, as the subtalar joint was not fused, the excessive mobility in this joint encouraged the deformity. The surgery was revised; the peroneus brevis was detached and transferred to the base of the second metatarsal and the subtalar joint was fused. Following this, the foot became stable and the deformity remained corrected. The peroneus brevis was transferred in to the attachment of tibialis posterior attachment re-routed behind the ankle in three patients who tibialis posterior and anterior paralysis without the weakness of the toe extensors and the peroneus tertius. This operation was rated fair according to Axer’s rating (Table 1). We have noticed that when PB tendon is routed behind the ankle its power is not as strong (grade III) as when routed anterior to ankle (grade IV), this is why the result is fair rather than good. This I believe occurs because of the soft tissue interference where Peroneus brevis tendon passing behind the medial malleolus, where there are potential risks of tethering to the nearby structures. The transfer anterior to the ankle in contrary is in a straight path with less chance of tethering. In one case of tibialis (anterior and posterior), peroneus tertius and toe extensor weakness, the peroneus longus was transferred anterior to the ankle to the base of the second metatarsal. Although this transfer was useful improving ankle dorsiflexion and reducing heel valgus deformity, the result was rated fair according to Axer’s rating because the midand the fore-foot became unstable following this transfer as a result of the loss of the stabilising function of peroneus longus on the calcaneocuboid joint and the first metatarsal. In our cases, there was mild tightness of the Achilles’ tendon, this was however found not be a problem. The mild equinus deformity of the ankle was away of compensating for leg length discrepancy which some of our patients had.

4. Discussion The paralysis of tibialis anterior and posterior results in a medial and downward displacement of the talus, this is

Table 2 Showing the different procedures performed according to the group of muscles involved, and their outcome Case

Associated weakness

Operation

Aim of the operation

Result

10

Weakness of ankle dorsiflexors

Peroneus brevis (PB) was transferred underneath the deep fascia anterior to the ankle joint in nine to the base of the second metatarsal and in one to the base of the first PB was transferred posterior to the ankle joint, deep to tendo-achilles, into the tendon of tibialis near its insertion Peroneus longus was transferred anterior to the ankle joint to the base of the second metatarsal

Improve foot dorsiflexion and reduce eversion seven

Good in nine, bad in one

Aiming to restore the arch of the foot

Fair

Improve foot dorsiflexion and reduce eversion

Fair

3

Intact ankle dorsiflexors (peroneus tertius, extensor digitorium longus)

1

Weakness of ankle dorsiflexors

148

A.A. Faraj / The Foot 15 (2005) 146–148

initiated by the lateral displacement of the calcaneus, because of the unupposed action of peroneus longus, planterflexion of the talus is associated with pronation of the foot at the calcaneocuboid joint, abduction of the forefoot and dropping of the longitudinal arch [1]. Fried and Hindel recommended peroneus longus, flexor digitorium longus, or flexor hallucis transfer posterior to the ankle joint to the sheath of tibialis posterior near its insertion in an attempt to correct paralytic planovalgus foot deformity [2]. Our results show poor outcome when the transferred tendon is routed behind the ankle. The passage of a tendon between the superficial and deep compartments of the calf can be tethered or buckled which eventually leads to a mechanical failure [1–4]. Subcutaneous route is preferable, provided the tendon is passed underneath the deep fascia in order to avoid bow stringing. Our results suggest the transfer of peroneus brevis rather than peroneus longus to correct post polio-pes planovalgus for the following reasons: 1. In 10 out of 14 of our case, the results were good. This is we believe is because the main deforming force in invertor paralysis is the peroneus brevis, as it is the main foot evertor [7]. Its transfer overcomes the deforming mechanism. Additionally, there is spontaneous phasic conversion of peroneus brevis (in contrast to peroneus longus) after the transfer in to an ankle dorsiflexor, these makes, and this makes rehabilitation easier [8]. 2. When transferred, the loss of function of peroneus longus is associated with detrimental consequences. Pronation of the foot is carried out mainly by the peroneus longus, which also tightens the short planter ligament stabilises the transverse tarsal joints. Simultaneously, it tenses the planter apponeurosis resulting in locking the tarsal bones, tying the anterior and posterior pillars of the longitudinal arch. The peroneus longus is also the main planterflexor of the first metatarsal bone. It follows that the peroneus longus maintains the medial, lateral and transverse arches. In standing, peroneus longus, in company with other surrounding muscles, helps to maintain the erect position. It controls sideways sway by pressing the medial side of the foot on to the ground [7]. In one patient, the deformity was worse, when peroneus brevis was transferred to the first metatarsal anterior to the ankle and without subtalar arthrodesis. This, I believe, was because

of the alteration of he mechanical axis. In the presence of a mobile subtalar joint, and when the axis of pull of the transferred peroneus brevis became medial to the subtalar joint, the tendon had a longer lever when the fulcrum (subtalar joint) allowed eversion, therefore the valgus deformity was made worse. Arthrodesis of the unstable joint improves the function of the transferred tendon [9]. It is my belief that a simultaneous arthrodesis and tendon transfer is appropriate, but further randomised studies would be needed to prove this statement.

Acknowledgement I would like to thank the consultant orthopaedic surgeon in the Medical city, Baghdad Teaching Hospital, for allowing publishing the results of their patients and their guidance, in particular Mr. A. Abdulahassan, Mr. I. Alnaib, Mr. I. Sarsam and Mr. S. Akidiri.

References [1] Axer A. Into-talus transposition of tendons for correction of paralytic valgus foot after poliomyelitis in children. J Bone Joint Surg 1960;42A:1119–23. [2] Fried A, Hendel C. Paralytic valgus deformity of the ankle: replacement of paralysed tibilais posterior by peroneus longus. J Bone Joint Surg 1957;39-A:921–4. [3] Fried A, Moyseyev S. Paralytic valgus deformity of the foot. Treatment by replacement of paralyzed tibialis posterior muscle: a longterm follow-up study. J Bone Joint Surg Am 1970;52(8):1674–6. [4] Grice DS. Further experiences with extra-articular arthrodesis of the subtalar joint. J Bone Joint Surg 1955;36-A:246. [5] Grice DS. The role of subtalar fusion in the treatment of valgus deformities of the feet. American academy of orthopedic surgeons: instructional course lectures, vol. 16. St. Louis: The C.V. Mosby Co.; 1957. [6] Peabody CW. Tendon transposition in the paralytic foot. American academy of orthopedic surgeons: instructional course lectures, vol. 6. Ann Arbor, MI: J.W. Edwards; 1949. [7] Palastanga N, Filed D, Soames R. Anatomy and human movement. Oxford, London, Singapore, Nairobi, Ibadan, Kingston, Avon: Heinemann Medical Books, Bath Print; 1989. p. 385–7. [8] Ingram AJ. Paralytic disorders in campbell’s operative orthopaedics by A.H. Crenshaw. 7th ed. St. Louis, Washington, DC, Toronto: The C.V. Mosby; 1987. p. 2925–3060 [chapter 66]. [9] Faraj AA. Talonavicular arthrodesis for post-polio valgus foot deformity. J Foot Ankle Surg 1996;35(2):1–3.