CHAPTER 8 POST:POLIO SYI{DROME, AND TENDON TRANSFER AS SURGICAL MANAGEMENT

Melissa Robrtaille, DPM, MS

Many patients who were diagnosed with innerwations (Figures 1,2'). Asymmetric, flaccid poliomyelitis 30 to 40 years ago are curently experi- paralysis occurs as well as other lower motor neu- encing increased muscle fatigue, new weakness, and ron symptoms. Only I to 20/o of all those infectecl pain. This decline in muscle function frequently with the poliovirus develop paralysis. Also, in chil- affects the patient's ability to ambulate and necessi- dren, paralysis occurs in 1/1000 case, whereas in tates additional bracing, assistive devices and possibly adults, the frequency increases to l/75.It is impor- surgical treatment. The characteristics of post-polio tant to note that patients retain normal syndrome (PPS) and tendon transfers for the afferent/sensory ancl central neurologic control.' ffeatment of weakness and joint instability will be The threat of poliomyelitis in developed discussed. countries is practically non-existent today thanks to In order to understand the possible causes of the development of the Salk vaccine in 7955 PPS and to provide the best plan for its treatment, and the Sabine oral vaccine in 1961. Polio still knowledge of acute polio is necessary. Acute continues to be a problem in third wodd countries anterior poliomyelitis is a viral infection localized in where mass immunizations are not always the anterior horn cells of the spinal cord and available. Many of those who contracted the cefiain brainstem motor nuclei. Initial invasion of clisease were able to recover from the resulting the vir-urs occurs through the gastrointestinal and paralysis and went on to lead active, normal respiratory tracts and spreads to the central nen/ous lifestyles. The potential for recovery of muscle system through a hematogenolls route. Once there, function depends on the recovery of damaged but neurologic and functional loss occurs as anterior not clestroyed anterior horn cells. Most clinical horn cells are damaged, destroying the efferent recovery occurs during the first month after the pathway, and thus the muscle fibers lose their acute illness and is almost complete within 6

Figure 1. Norm.ll anterior horn cell r,ith its Figure 2. In acute poliomyelitis. the :rnterior horn

nlot()f-nellfon - cells are clestroyed and the n-nscle fiber lose thek innen ations creating weakness or paralysis. 40 CHAPTER B months although limited recovery mav occur for In general, the patients most at risk for devel- about 2 years. oping new problems are those who experienced The extent of neurologic and ftinctional recov- more severe polio at onset, although some patients ery is determined in part by the phenomenon of with typical post-polio symptoms had seemingly terminai axon sprolrting were a motor neuron can mild polio with excellent clinical recovery. In re-inneruate muscles fibers which have lost their addition, persons who were older when they nerue supply. In addition to this re-inneruation, the contracted polio appear to be at an increased risk for remaining muscle fibers hyperlrophy to increase the new neurological symptoms. The onset of there new strength of the muscle group. As a result, the problems is most commonly insidious, but in many sulivors of acute polio may be left with a few, persons they are precipitated by specific events such significantly enlarged motor units doing the work as minor accident, period of bed rest, or weight previously performed by many units.' gain. Patients characteristically say ihat a similar A suruey in 1987 found there were more than event severzrl years earlier would not have caused 640,000 sulivors of paralyic polio in this country. the same decline in health and function. Likewise, Population based sulveys have indicated that as new problems may begin when coexisting medical many as 540/o of polio survivors develop new problems such as diabetes develop or worsen.2 symptoms. If we consider these estimates to be This seemingly new phenomenon was accllrate, over 400,000 people may experience the actually recognized over 100 years ago, with the late effects of polio. It is impofiant to realize that first descriptions of the disease reported in 1875 in there are many affected and the possibility of the French literature. Sporadic reports describing encountering this condition in the office setting is similar phenomenon appeared in the literature quite 1ike1y.3 thror-rghout much of the 20th century. It was not until the early 1980s, approximately 40 years after Post-Polio Syndrome the major epidemics of the 1940s and 1950s, that post-polio syndrome (PPS) became widely Today, many of those earlier polio surwivors are recognizecl.t developing new problenis ancl facing new chal- lenges. These problems typically occur about 30 to 50 years after their initial polio illness and inclucle new w-eakness, fatigue, pain, ftrnctional loss, and cold sensitivity.r The cause of these new symptoms is unclear, with many theories regarding the etiology of post-polio syndrome being proposed; hower.er, the pathologic changes that cause the symptoms of PPS have not been proven conclusively.' Although many of these etiologies continue to be the subject of debate, the most popular and consistent factors appear to be motor trnit dysfunction due to oveflise and /or premature aging of large motor units. Following anterior horn cell death, adjacent healthy zrnterior horn ce1ls assume the filnction of those ion cells. Subsequently, the metabolic demand placed on them is greater (Figure 3). It is hypothesizecl that these over-worked anterior horn cells succumb prematurely to the aging process due to greater than normal stress placed on them. Nthough this hypothesis is artrac- tive to many, it has not been supported by biopsy or Figure J. Folloning anterior horn cell death, direct, conclusive experiment al data.' adjacent healthy anterior horn cells assume the function of those ion cells. CHAPTER 8 4t

Criteia for the diagnosis of PPS Because of muscle weakness, gait characteris- tics in post-polio patients are predictably abnormal. The criteria for the diagnosis of PPS used by most A study by Perry et al found that impaired ankle investigators and clinicians were first described by plantarflexion due to weakness of tricep surae was Mulder et a1 in 7972. Theses criteria include 1) a the most significant indicator of abnormal gait documented history of polio (can be confirmed pattern in these patients. This led to a reduced through medical records, neurologic examinations velocity and stride length, which was amplified in and electromyography showing large polyphasic fast gait.5 The significance of this relates to the motor unit action potentials and a decrease in the increased demand of the plantar flexors during the number of motor units on maximum recruitment in single suppolt phase of stance, since this is when weak muscles with fibrillations); 2') a period (usu- the greatest demand is placed on these muscles. a1ly >15 yrs) of neurologic and functional stability Forward momentum of the body over the supporl- after recovery from acute illness; 3) the gradual or ing foot stimulates action of the gastrocnemius and rarely abrupt onset of new weakness. New neuro- soleus muscles to control the rate of tibial advance- genic weakness is essential for making the ment and maintain stability at the ankle. Likewise, diagnosis of PPS and presumably reflects continu- calf muscle action is the only mechanism used for ing dysfunction of previously injured motor units. It knee stability in normal gait after early mid-stance. is important to make a distinction between new The consequence is that a patient with weak plan- neurogenic weakness versus disuse weakness, tar flexors has poor tibial control and an unstable which is not always apparent. This can be inferred ankle joint. Therefore, when the stability of the by the onset of diminished function despite main- lower extremity is threatened during single limb taining the usual level and intensity of activity. stance, the velocity is limited to decrease the Fina1ly, 4) the criteria is the exclusion of all other chance of falling. Also, the heel cannot rise until conditions that might cause the weakness or other the contralateral limb is loaded, so a significant health problems.t't' As previously mentionecl, the portion of stride length is lost.;7 symptoms of fatig,-re, joint pain, muscle pain, new New muscle weakness usually appears in weakness, and cold sensitiviry are vague and can muscles previously affected with the initial attack, have a number of differentials. The major dif'feren- however muscles that were believed to be spared tial diagnosis include focal neurologic disease such can be affected as well. Because the mechanism of as a radiculopathy, focal compressive neuropathy, neurologic compensation, previously described, is or spinal cord lesion and medical causes of neu- so effective, a muscle can retain normal strength ropathy such as diabetes, thyroid disease, uremia, even after 50o/o of the original motor neurons have a1cohol, and hereditary neuromuscular disease. been lost. This is why manual muscle testing in Attempts must be made to ru1e out other causes of some patients may be normal. These patients man- disease since the management of different diseases age to function at an extraordinarily high level of can vary greatly. performance on relatively few sutwiving motor units.s'e The neurologic examination in PPS is char- Physical exam and gait evaluation acteristic of a lower motor neuron lesion. The patients will have intact sensorium, flaccid paraly- Muscles innervated by the cervical and lumbar sis, diminished reflexes and absence of clonus or spinal segments are most often affected, and babinsky. Intact sensation helps distinguish PPS paralysis occurs twice as often in the lower extrem- from other common differentials such as neuropathy. ity muscles as in upper extremity muscles. In the It is important for the podiatrist to be aware of lower extremity, the most commonly affected this condition, since the treatment differs greatly muscles are the quadriceps, glutei, tibialis anterior, from that of the initial polio experience. A team medial hamstrings, and hip flexors. The most approach with the physical therapist, primary care common deformities of the foot include clawtoes, physician, pedorthitist, and ofihopaedist is vital to cavovaftls foot, dorsal btinion, talipes equinovarus, the success of the treatment. and talipes calcaneus.' 42 CHAPTER 8

Conserv ativ e treatment orthosis is a dorsiflexion-stop ankle-foot orthosis (AFO) to supplement weak calf musculature. Once other causes are ruled out, a distinction To avoicl introducing additional strain on the between disuse versus overllse weakness needs to quadriceps, the orthosis also must have free be made so that appropriate recommendations plantar flexion. Persons with combined weakness regarding exercise and activity can be made. There and knee flexion contractures need a locked knee- has been a controversy about management of new ankle-foot orthosis (KAFO). Hip abductor and/or weakness with exercise in the post-polio patient extensor muscle weakness require the use of because the pathophysiology of pps remains crutches. If a patient also has insufficient upper unclear. Traditional therapy such as exercise rnay body strength, then that patient mllst progress to a callse further weakness, so it mllst be used wheelchair.t cautiously. There are fbur possible directions for patient managernent: muscle strengthening, short- Surgical Treatment ening the duration of effort, substitute clevices in the form of orthoses and walking aids, and Surgery shor-rlcl be used selectively when attempting reconstruCtive surgery.' to improve walking ability. Release or lengthening of Strengthening exercises have been the contracted muscles is straightforward and necessary traditional means of overcoming fatigue and when it presents; however, care must be taken not to weakness. \florkouts under the supervision of a be overzealous in correction as this may cause an trained physical therapist are absolutely essential iatrogenic muscle imbalance or instability. Tendon for developing and monitoring the best workour transfers may also be necessary in order to provide program tailored to a pafiicular patient. Muscle joint stability or supplement muscie loss or weak- pain is considelecl a contraindication to any ness. As with any other transfer, it is impofiant to therapetitic exercise. Lifestyle modification to establish the viability of the muscle to be transfered. reduce the demancl on symptornatic muscles For this reason, eiectrodiagnostic testing can be done including frequent rest periocls is aiso essentiai. to establish the erlent of disease and those muscle This may often require a change in vocation and/or groups aff'ected before any transfer is attempted, sllpport from family members. even in the setting of a "normal" physical exam. If a Orthoses, walking aids, ancl wheel chairs offer soft tissue procedure will not provide the necessary means a of reducing muscular demand while suppolt or stability, or if a tlred deformity is noted, a preseruing function. The most commonly needed joint arthrodesis will be required.s

Table L

MUSCLE IMBALANCE AND THEIR RESULTING DEFORMITY Muscle paralysis Deformity Tibialis Anterior Equino-Cavo,Varus Drop-Foot +/- Planovalgus Tibialis Posterior Rearfoot and Forefoot Eversion Tibialis Anterior and Posterior Rearfoot and Forefoot Equinovalgus Peroneal Rearfoot Varus Forefoot Adduction Dorsal Bunion Peroneals and Extensors Mild Equinovarlls Tibialis Anterior and Peroneal and Extensors Severe Equinovarus Triceps Cavus CHAPTER 8 43

Table 2

DEFORMITY WITH THEIR SUGGESTED TENDON TRANISFER PROCEDURE

Deformity Tendon transfer procedure Clawtoes/ EHL lengthening Hallux malleus PIPJ arthrodesis Hibbs and Jones tenosuspension Dorsal Bunion Jones tenosuspension Tibialis anterior transfer to the 2nd metatarsai STATT Dropfoot EHL transfer to navicular Peroneus longus transfer to 2nd metatarsal Tibialis posterior transfer through interosseus membrane Equino-Cavo-Varus Tibialis anterior transfer to middle cuneiform EDL transfer to lateral cuneiform Hibbs and Jones tenosuspension Tibialis posterior transfer through interosseus membrane to middle cuneifrom Tendo Achilles lengthening Plantar fasciotomy with Steindler stripping Posterior capsule release Calcaneal ca\us Tibialis anterior or tibialis posterior transfer posteriorly into the calcaneus Peroneus longus transfer to the calcaneus Rearfoot/ FDL or FHL transfer to tibialis posterior forefoot valgus Equino valgus Peroneus brevis or peroneus longus transfer to base 2nc1 metatarsal Talonavicular arthrodesis Any fixed cleformity Arthrodesis of isolated or mr:ltip1e joints

Isolated muscles may be paralyzed in patients Tibialis anterior muscle weakness or paralysis u,ith poliomyelitis, but more often combinations of results in the loss of dorsiflexion and inversion muscles are aff'ected. The specific muscle or power of the foot; therefore, it produces a slowly muscles involved and the resulting muscle progressive deformity of equinus, dropfoot and imbalance should be determined before treatment is carus or varying degrees of planovalgus that is first stafied. (Table 1).The exact pattern of muscle paral- evident in the swing phase of gait. Compensation ysis and specific defbrmity that occurs must also be by extensors for dorsiflexion causes hyperexten- carefully determined before any surgical interuen- sion of the proximal phalanges and depression of tion is undefiaken. An in-depth discussion of tendon the metatarsal heads. A cavovarus deformity transfers is beyond the scope of this paper, however occasionally results from the unopposed activity of to achieve a successful tendon transfer a plantigrade the peroneus longus combined with an active foot must be present before the tendon transfer. This tibialis posterior muscle. Therefore the treatment is can be created by performing a tendon lengthening dependent on the deformity and the treatment (e.g. Achilles tendon), release of a joint contracture, options consist of the following (Table 2); posterior or if necessary, a joint afihrodesis. Another principle tibial transfer through the interosseous membrane, that should be considered when contemplating a extensor digitorum longus transfer to the second or tendon transfer is that a transferred muscle usually third cuneifbrm, jones tenosuspension with a Hibbs loses one grade of muscle strength; therefore, if the tenosuspension, peroneus longus transfer to the muscle stren€lth is only good to fair, the transfer may second metatarsal base, plantar fasciotomy with not be successful. Steindler stripping, correction of clawtoes with 44 CHAPTER 8 arthrodesis of the PIPJ, arthrodesis of any rearfoot Tibialis anterioq toe extensor, and peroneal joint, release of soft tissue contractures (usually a muscle weakness results in progressively severe tendo-Achilles lengthening and posterior capsule equinovarus deformity due to the tibialis posterior release). These can be performed as an isolated and triceps surae being unopposed. Anterior transfer procedure or combination as indicated by the level of the tibialis posterior to the base of the of pathology. third metatarsal or middle cuneiform cat:- be Asirvathem et a110 published a report using an supplemented by anterior transfer of the long toe extensor haliucis longus coaptation to the tibialis flexors. This is done thror-rgh the interosseous anterior to correct drop foot deformity in eight membrane. A tendo-Achilies lengthening is almost post-polio patients. Early results were promising, as always indicated. all eight patients had improved ankle dorsiflexion; Isolated peroneal muscle weakness is rare in however, long-term follow-up revealed that 75o/o patients with poliomyelitis but can cause severe had lost the ability to actively dorsiflex the ankle hindfoot varus deformity because of the against gravity. They concluded that coaptation unopposed activity of the tibialis posterior muscle. alone was insufficient to give long-term support The calcaneus becomes inverted, the forefoot is and recommended EHL transfer to the navicular, adducted, and the varus deformity is increased by possibly with other procedures as warranted. the action of the invefior muscles during gait. The Tibialis posterior muscle paralysis is rare but unopposed tibialis anterior activity can cause a can result in hind foot and forefoot eversion. A dorsal bunion. In this situation, the tibialis anterior flexor digitorum longus or flexor hallucis longus can be transferred laterally to the second metatarsal transfer is usually done, similar to repair for a base. Jones tenosuspension is performed usually to posterior tibial tendon dysfunction. A tendo- prevent contracture of the ha1lux that is common Achilles lengthening is also commonly performed. after a tibialis anterior tendon transfer. Likewise, a \7hen both the tibialis anterior and posterior split tibialis anterior tendon transfer can be muscle are paralyzed, the development of hindfoot performed instead. and forefoot equino-valgus is more rapid and the In another repofi from Faraj," a Jones teno- deformity becomes fixed as the tendo-calcaneus suspension procedure was performed on and peroneal muscles shorten. A review of the post-polio patients with an increasing claw hailux recent literature revealed a small amount of deformity. His prospective study was performed on published reports for the specific correction of 12 patients with a mean fo11ow-up of three years. post-polio deformities using tendon-balancing Ten patients had good results with two patients procedures. Faraj" reported on a case of paralytic having recllrrence of deformity that was treated valgus deformity resulting from weakness of the with a combined EHL and tendo Achilles lengthen- anterior and posterior tibial muscles secondary to ing (TAL). His conclusion was that an equinus polio where the initiai treatment was a transfer of contracture of the Achilles tendon, which was the peroneus brevis tendon to the base of the present in both of the fair results, led to the second metatarsal. (If the peroneal muscles are recurrence of deformity. Subsequently, he recom- normal, the peroneus longus is transferred to the mended identification of any equinus deformiry base of the second metatarsal, because of its longer prior to any surgical correction, and if present, excursion). This had been performed in an attempt performing a simultaneous TAL in order to ensure to restore inversion and dorsiflexion strength to the success of any other transfer. foot. This was unsuccessful and resulted in a Peroneal and long toe extensor muscle laterally deviated forefoot. A talonavicular arthrode- paralysis causes a less severe equinovarus sis was performed in an attempt to stabilize and deformity that can be treated by transfer of the correct the midtarsal joint deviation. This case tibialis anterior to the base of the third metatarsal illustrates the need to accurately assess the amount or the middle cuneiform. of initiai deformity. Without the tibialis posterior to A triceps surae muscle paralysis causes a help support or brace the foot in inversion, the rapidly progressive ca\1ls deformity. Compensation peroneus brevis acted solely as an evertor of the by the plantarflexors results in a car,us deformity. forefoot accentuating the lateral dislocation at the Depending on the muscle function present, midtarsal joint. posterior transfer of the tibialis anterior tendon CHAPTER 8 45 through the interosseous septum into the calcaneus conservative treatment play a large role in the or posterior transfer of the peroneus longus or pos- rehabilitation of the PPS patient and as such have terior tibial tendon transfer is done. If possible, a dominated in regard to published literature. It is phasic transfer is more desirable, although the obvious that studies determining the effectiveness anterior tibial tendon has been shown to undergo of tendon transfer in the PPS are needed. Although phase conversion and function as a pTantar flexor tendon transfer have been used in conditions during gait. Plantar fasciotomy and intrinsic muscle similar to PPS for identicai reasons, it would be release are required before tendon transfer in fixed helpful to surgeons to have more than anecdotal forefoot ca\.Lrs deformity. evidence for the support of such procedures. As these reports show, it is important to perform a thorough evaluation prior to any References attempted muscle transfer. Additionally, it is important to recognize any other musculoskeletal 1. Canale ST. Campbell's Operative Orthopaedics, 9th ed., Neruous System, Parall,tic f)isorders, pp.3972-3994, Mosby-Year Book, St. deformities that could adversely affect the outcome Lonis, MO, 1998. and formulate the surgical plan accordingly. 2. Gawne A, Halstead L. Post-Polio syndrome: pathophysiology and Finally, one must recognize that arthrodes's might clinical management. Clin Rea Pbys Rehab Med 7995;7:741-88. 3. Jubelt B. Agre J. Characteristics and management of postpolio be necessary, either initially in order to provide for syndrome. JA.M A. 2000;284:412-4. optimum joint stability, or in the future, if the ten- 4. Nordgren B. Postpolio muscular dysfunction: relationships between muscle energy metabolism, subjective symptoms, mag- don transfer has not provided iong term success. netic resonance imaging, electromyography, and muscle .trength. /'4nvle Nen e I 09-:20: I J4 l-s L i. Perry J, Barnes G, Gronley J. The Postpolio syndrome: an Conclusion overuse phenomenon. C lin Ortbop 1988;233:1.45-62. 6. Tillett S, Monzena J. The reappearance of polio:postpolio syn- drome. J Am Padia*ic Llecl Assrc 7999;89:783-7. Post-polio syndrome is a neuromuscular disease 7. Hurmuzlu Y, Basdogan C, Stoinovici D. Kinematics and dynamic entity associated with symptoms of weakness, stability of the locomotion of post-polio patients. J Biamrb Eng 1996;718:405-7L. fatigue, and muscle and joint pain. Diagnosis is 8. Klein M, Whyte J, Keenan M, Esquenazi A, Polansky M. Changes made difficult by the large number of differentials, in Strength Over Time Among Polio Survivors. Arch Phys Med Because Rebab. 2000 : 87 :1059 -1064. which must be excluded. it is not a rare 9. PerryJ, Mulroy S, Rennick S. The Relationship of lower extrem- pathology, the podiatric physician must be diligent ity strength and gait parameters in patients with posfpolio and recognize the PPS patient. Treatment syndrome. Arth Pbys Med Rehab 1993;74:165-9. is largely i0. Asirwatham R, Watts H, Gillies H, Extensor Hallucis Longus coap- based on conservative measures including physical tation to tibialis anterior: a treatment for paralytic drop foot. Faar therapy, orthoses and lifestyle changes. If surgical Ankle lnt 1993;14:343-6 11", Faraj A. Talonavicular joint arthrodesis for paralytic post correction is necessary, a through physical poliomyelitis forefoot instability. / Foot Ankle Surg 1996;35:166-8 examination and appropriate testing need to be 12. Faraj A. Modified jones procedure for post-polio claw hallur deformrty . Foot Ankle Sarg 1997;36,356-9. performed. There is a scarcity of published J literature regarding PPS and tendon transfers. Although there are case repofis and small studies Additional References published large assessing , no trial the success of Mulder D$fl, et al. Late progression of poliomyelitis or forme fruste tendon transfer exits. The vast majority of recent amyotrophic lateral sclerosis. Mayo Clin Proc 1972; 47,756-61. literature regarding PPS deals with its identification, Trojan DA, Cashman NR. An open trial of Pyridostigmine in Post- Poliomyelitis syndrome. Can J Neurol $g1 l))J;22:223-7. etiology, and basic treatment. Physical therapy and