Patterns of Motor Activity

Limb motions are complex and are not the result of isolated contraction of a single muscle. The functions of many muscles are integrated and coordinated in the execution of a movement and are controlled by the automatic reflexes of the CNS. In dorsiflexion of the ankle, for example, the anterior tibial muscle, the toe extensors, and the peroneus tertius are the prime movers that execute the desired movement, whereas the triceps surae and the toe flexors are the antagonist muscles that become relaxed because of the reciprocal innervation of the agonist and antagonist muscles. The synergist and fixation muscles also contract while the prime mover acts.

In the presence of muscle weakness, the tendency is to use a strong group of muscles that can perform the action more easily and readily, thus excluding the weaker muscles from the pattern of motor activity. A muscle that has been temporarily paralyzed will be left out of the pattern of motion permanently if other muscles substitute for its action during the period of its recovery. In the convalescent stage, these muscular substitutions and abnormal patterns of motor activity should be avoided.

Some neuromuscular units often remain intact in the paralyzed muscles; they act as “guiding contractile units,” and in the performance of active exercises, these functioning neuromuscular units should be used to guide the body part in execution of normal motion.

For example, in reeducation of a poor anterior tibial muscle, the ankle joint is first passively dorsiflexed through its full arc of motion to stretch any contracture of the triceps surae muscle. The limb is then placed in a side-lying position to eliminate the force of gravity, and the ankle joint is again passively dorsiflexed in some inversion through its full range. The therapist assists the patient to localize the action of the anterior tibial muscle and emphasizes that substitution by the toe extensors and peroneus tertius muscle should be avoided.

Next the patient is asked to produce an active, sustained contraction of the anterior tibial throughout its full arc of motion, first with and then without assistance. As the muscle becomes stronger, the limb is placed in the supine position to make the muscle work against gravity, and gradually increasing manual resistance is applied. The active exercises are graduated on the basis of performance. Muscles that are overworked lose strength.

In poliomyelitis, reciprocal innervation between agonist and antagonist muscles is often disturbed, with resultant loss of synergistic muscular action and the normal pattern of motor activity.

Fatigue

A paralyzed muscle is easily fatigued. This is readily shown by its rapid loss of power and inability to function after several effective contractions. Forcing a weak muscle beyond its point of maximal action does not increase its strength; on the contrary, it inhibits recovery of the paralyzed muscle. It is important to observe the level of functional activity of a weak muscle so that it is not forced to exceed its capability.

Contractural Deformity and Progressive Loss of Function

Flaccid paralysis is the chief cause of functional loss. Muscular action is also inhibited by pain, sensitivity, and spasm. When a muscle is maintained in a shortened position for a prolonged period, myostatic contracture develops. Muscle imbalance and increased stress secondary to abnormal patterns of activity are other factors producing deformity. Growth is an important consideration in the management of poliomyelitis in children. The contour of bony structures is influenced by paralysis and dynamic muscle imbalance. For example, when the triceps surae muscle is weak and the ankle dorsiflexors are of normal motor strength, a progressive calcaneus deformity of the hindfoot results. If the child is permitted to walk without support and protection, the loss of power of the triceps surae muscle will be greater because the muscle is working against gravity. Figure 37-1 shows the vicious cycle of factors causing progressive loss of function in poliomyelitis.

Principal factors involved in the progressive loss of function in the residual stage of poliomyelitis.

(Redrawn from Green WT, Grice DS: The management of chronic poliomyelitis, Instr Course Lect 9:86, 1952.)

In the asensitive stage, proper alignment of the limbs and full range of joint motion must be restored and maintained. Passive stretching exercises are performed vigorously. In the presence of muscle imbalance and a tendency to develop contracture, bivalved casts should be used at night to maintain the part in correct position. When a deformity is fixed, wedging casts or traction may be applied.

Active exercises are performed to integrate recovering motor units into the normal pattern of motion; their primary objective is not to produce hypertrophy of muscles that are already functioning normally. Hydrotherapy and active exercises in a pool are prescribed for patients with extensive paralysis. Motion of the hips, shoulders, and trunk is greatly facilitated in the pool because the buoyant effect of the water facilitates coordinated motion of the parts. Strict supervision by the therapist is mandatory, however, to prevent substitution of strong muscles for those that are weak. Excessive exercises and overwork should be avoided. Patients with extensive paralysis are initially instructed to ambulate in the pool; when adequate control of the trunk and lower limbs is achieved, this is no longer necessary. Standing balance should be developed first, followed by walking with the help of crutches. The gait pattern should be a reciprocal four-point gait, with the amount of body weight borne depending on the degree of paralysis. The physical therapist assists in locomotion so that abnormal mechanisms do not develop. During the convalescent period, use of an orthosis should be kept to a minimum because it increases the workload on the paralytic levels and tends to produce abnormal gait patterns. In severe paralysis of the lower limbs and trunk, however, locomotion may be impossible without the support of an adequate orthosis. General activities of the patient are gradually increased. During the first few minutes of locomotion the gait may be effective, but with fatigue it may become poor. Random, purposeless activity should be discouraged.

Active Hypertrophy Exercises

Active hypertrophy exercises are performed primarily for the benefit of marginal muscles, to elevate or maintain their functional level. (There is little to be gained by exercising zero or “trace” muscles that remain unchanged after 18 months, and the same is true of muscles that have a “good” or “normal” rating.) For example, when the anterior tibial and toe extensor muscles are “fair” in motor strength and the triceps surae muscles are “normal,” active exercises of the ankle dorsiflexors should be performed to maintain them at the antigravity functional level. Progressive resistance exercises entail the use of activity graded in proportion to the strength of the involved muscles. These exercises are recommended in the residual stage of poliomyelitis to increase the strength and improve the endurance of such individual muscles or groups of muscles as a “fair” quadriceps or triceps surae or a “fair plus” hip abductor muscle to maximum capacity. Whether progressive resistive exercises are of any permanent value when the motor strength of a muscle is less than “fair minus” is doubtful; a “poor” quadriceps muscle cannot, through hypertrophy exercises, be improved to “fair” strength so that it can lift the leg against gravity. Correction of flexion deformity of the knee, however, may provide added strength by eliminating the need for the quadriceps muscle to work against deformity.

Passive Stretching Exercises

Prevention of contractural deformity is much simpler than correction of such deformity. When a limb is continuously maintained in one position, contracture and fixed deformity develop as a result of the effects of gravity and dynamic imbalance of muscles. An ankle joint held in plantar flexion because of weak dorsiflexors and a strong triceps surae is susceptible to the development of progressive equinus deformity if the ankle is not passively stretched into dorsiflexion every day. The calf muscles should also be passively stretched to prevent the development of equinus deformity; this is implemented by the use of a bivalved night cast to hold the foot out of equinus and in neutral position. Passive stretching exercises should be performed gently several times a day. In the presence of muscle imbalance, however, these exercises are not adequate to prevent deformity, and other measures should be undertaken, such as the use of a removable bivalved long-leg night cast to hold the foot in neutral position and wearing of a below-knee dorsiflexion-assist spring orthosis during the day.

Functional Training

The purpose of a functional training program is to enable the patient to overcome the handicaps imposed by the physical disability. The residual deficit in function varies, depending on the extent and severity of paralysis. The needs of a growing child progressively change. In the residual stage the patient is taught how to use all available muscles to accomplish a task successfully. This is in contrast to the convalescent stage, when the patient is not allowed to substitute stronger muscles for weaker ones. For example, when the anterior tibial is “poor” in motor strength in the convalescent stage, the child is not permitted to use the toe extensors to dorsiflex the foot when active exercises are performed with the anterior tibial. In the chronic stage, however, if anterior tibial function is still “poor,” the child is taught how to dorsiflex the foot by using the toe extensors and peroneal muscles.

At times the activity of stronger muscles is suppressed to prevent the development of deformity. For example, an individual with “normal” sartorius, biceps femoris, and peroneal muscles but “poor” iliopsoas, medial hamstring, and anterior tibial muscles walks with a marked external rotation deformity of the foot and leg. It is important to supervise such a patient’s gait and teach the patient to suppress the eversion power of the peroneals and the externally rotating power of the biceps femoris and the sartorius to prevent the development of an external rotation deformity of the lower limb.

To teach a child merely to walk with crutches and orthoses is not satisfactory. The child should be instructed in activities of daily living, such as how to get in and out of chairs, open doors, and enter an automobile.

General Principles

Certain general principles should be followed regarding the use of an apparatus in patients with poliomyelitis. Whenever satisfactory recovery of function is expected, an orthosis should be used with caution on the lower limbs because it is likely to produce an abnormal gait pattern. Thus during the early convalescent period, use of an orthosis should be deferred until after maximum recovery of muscle function has taken place. Locomotion without an orthosis but with the support of crutches should be attempted to stimulate active muscular function through the exercise of walking. Use of an orthosis should not, however, be postponed if deformities appear likely to develop from the stress of weight bearing. The needs of each patient are different, and the use of a lower limb orthosis depends on the severity of the muscle weakness and the degree of dynamic imbalance of the muscles. If the patient has extensive paralysis of the lower limbs, use of an orthosis may be the only means of achieving stance and locomotion.

In general, use of an orthosis should be as minimal as the condition permits. For example, if a patient with paralysis of both lower limbs were to be fitted with two above-knee orthoses, he or she would also need to use two crutches to walk. If the patient were to use two crutches, he or she could do as well with an above-knee orthosis on one leg only because only minimal motor strength is required of the other leg to walk without an orthosis. During the stance phase on the leg without the orthotic support, the tripod base is completed by the two crutches; the knee is stabilized by being locked in hyperextension. “Fair” motor strength in the ankle dorsiflexors and hip flexor muscles allows clearance of the lower limb in the swing phase.

It is imperative to explain to the patient the reasons for using an orthosis. The patient should understand clearly that wearing the orthosis will help in the early convalescent stage of the disease and that the orthosis may be discarded later, after training or reconstructive surgery. For example, the use of a dorsiflexion-assist below-knee orthosis may be unnecessary after a successful anterior transfer of the peroneal tendons, or an opponens splint may be discarded after a satisfactory opponens tendon transfer. In addition, when the child becomes an adult, he or she may no longer need an above-knee orthosis to prevent genu recurvatum.

The continued use of an orthosis should be reevaluated regularly. Before advising that use of an orthosis be discontinued, the clinician should be certain that no possibility for the development of progressive deformities exists and that the level and quality of functional performance will not deteriorate.

Specific Applications

Lower Extremity.

When the toe extensor and anterior tibial muscles are paralyzed and the triceps surae muscle is normal, a dorsiflexion-assist spring orthosis (which acts as an active substitute for the weak ankle dorsiflexors) is preferable to a below-knee caliper orthosis with a posterior stop that prevents plantar flexion of the ankle beyond neutral position. In paralysis of the gastrocnemius and soleus muscles, a plantar flexion–assist spring below-knee orthosis with a dorsiflexion stop at neutral position is prescribed ( Fig. 37-2 ). In the presence of a flail ankle and foot, a double-action ankle joint (both plantar flexion–assist and dorsiflexion-assist) is provided, and a varus or valgus T -strap is added to the shoe as necessary. In addition, inside or outside wedges are prescribed for the shoe depending on the deformity of the foot.

Plantar flexion–assist below-knee orthosis with a dorsiflexion stop at neutral position.

When the muscles controlling the knee are paralyzed, an above-knee orthosis with a drop-lock knee joint is prescribed. This type of orthosis provides knee stability for walking and can be unlocked during sitting. If genu recurvatum results from paralysis of the triceps surae in the presence of some strength of the quadriceps femoris, it can be controlled by an above-knee orthosis with a free knee joint constructed so that complete extension of the orthosis at the knee is prevented. Proper positioning of the thigh and calf bands also checks genu recurvatum. Genu varum or knock-knee pads are added as necessary. When flexion deformity of the knee is present as a result of dynamic imbalance between the hamstrings and quadriceps femoris muscles, a well-padded anterior knee component is prescribed. An Engen extension knee orthosis is worn at night to correct flexion deformity of the knee.

Principles of Tendon Transfer

Tendon transfer entails shifting the insertion of a muscle from its normal attachment to another site to replace the active muscular action that was lost by paralysis and to restore dynamic muscle balance. The procedure was originally described by Nicoladoni in 1882. Many surgeons have devised various types of tendon transfers and established their usefulness. Lange, Velpeau, Vulpius, Codivilla, Mayer, Biesalski, Goldthwait, Ober, Steindler, Bunnell, and Green are some who may be mentioned. * The term tendon transplantation should not be used interchangeably with tendon transfer because the two are not synonymous. Tendon transplantation refers to the excision of a tendon and its use as a free graft. In muscle transplantation both the origin and the insertion of a muscle are detached, and the entire muscle with its intact neurovascular supply is transplanted to a completely new site.

* References .

• 1.
  

  The muscle to be transferred must have adequate motor strength to carry out the new function. As a rule, the motor rating of the muscle should be good or normal to warrant transfer. The function that the transferred muscle is intended to perform is another consideration. In the lower limb, for example, in the presence of footdrop, anterior transfer of the peroneus longus is adequate to produce effective ankle dorsiflexion, whereas in calcaneus limp, posterior transfer of the peroneus longus alone to the os calcis is not sufficient to substitute for action of the gastrocnemius-soleus, and the additional action of two or three motors such as the flexor digitorum communis and the anterior tibial muscles is required. Ordinarily, one grade of motor power is lost after a muscle is transferred.

  
  
• 2.
  

  The range of motion of muscles on contraction is an important consideration. This range must be similar to that of the muscles for which they are being substituted; furthermore, whenever muscles are transferred in combination, their range of contraction should not differ significantly. The transfer of antagonistic muscles is not ordinarily as effective as the transfer of muscles having similar function or corollary activity. However, with meticulous postoperative care, antagonistic muscles may be transferred effectively with good results. Posterior transfer of the anterior tibial to the os calcis and transfer of the hamstring muscles to the patella are common examples of such antagonistic transfers.

  
  
• 3.
  

  In choosing the muscles for transfer, the surgeon must weigh the loss of original function that will result from the tendon transfer against the gains to be obtained. For example, in the presence of hip flexor weakness, the hamstring muscles should not be transferred to the patella for quadriceps paralysis because loss of active knee flexion added to the lack of hip flexion will be a greater disability. Whenever possible, muscle balance must be restored. Ideally, a deforming muscle force must be shifted so that it substitutes for an essential weakness. In the foot and ankle, for example, the muscles of inversion and eversion and those of plantar flexion and dorsiflexion should be balanced. A common pitfall is transfer of the peroneus longus muscle posteriorly to the os calcis in the presence of a strong anterior tibial muscle. Normally, the anterior tibial muscle dorsiflexes the first metatarsal and the peroneus longus opposes this action. With posterior transfer of the peroneus longus, the unopposed anterior tibial gradually causes the first metatarsal to ride up and produces a dorsal bunion. Thus the peroneus longus should not be transferred to the os calcis unless the anterior tibial is shifted from its insertion on the first metatarsal to the midline of the foot.

  
  
• 4.
  

  The joints on which the transferred muscle is to act should have functional range of motion. All contractural deformity should be corrected by wedging casts or soft tissue release before tendon transfer. An anterior transfer for footdrop, for example, should not be performed in the presence of equinus deformity of the ankle.

  
  
• 5.
  

  A smooth gliding channel with adequate space must be provided for excursion of the tendon in its new location. The paratenon and synovial sheath are preserved over the tendon surface during dissection. It is preferable to pass the tendon beneath the deep fascia through tissues that permit free gliding rather than subcutaneously. A wide portion of the intermuscular septum is excised whenever muscles are passed from one muscle compartment to another. Sufficient space should be provided for the tendon so that adhesions will not form. An Ober tendon passer of appropriate size should be used to redirect the tendon to its new insertion; the tendon passer spreads the tissues and prevents binding.

  
  
• 6.
  

  The neurovascular supply of the transferred muscle must not be damaged while transferring the tendon. The surgeon must be careful to avoid denervating the muscle while freeing it for redirection. When the tendon is pulled up from the distal wound into the proximal incision, traction should not be applied to the origin of the muscle. Stretching of the motor nerve can be prevented by using a double-hand technique: the proximal segment of the tendon is held steady with a moist sponge while traction is applied on its distal segment with another sponge. Acute angulation or torsion of the neurovascular bundle is another cause of injury. Gentle handling is imperative to preserve innervation and function of the transferred muscle.

  
  
• 7.
  

  In rerouting of the tendon, a straight line of contraction must be provided between the origin of the muscle and its new insertion. Angular courses and passages over pulley systems should be avoided. To allow adequate freeing of the muscle toward its origin, the incision over the belly of the muscle must be long and proximally located.

  
  
• 8.
  

  The tendon should be reattached to its new site under sufficient tension so that the transferred muscle will have a maximal range of contraction. The transferred muscle should be tested during the operation to ensure that it will hold the part in optimal position. In the lower limb, where weight-bearing forces are involved, the tendon is ordinarily attached to bone, whereas in the upper limb it is sutured to the tendon. An important technical detail is scarification of the distal segment of the tendon that is to be anchored to a bone or tendon; this is achieved by excising the sheath and paratenon and “roughening” the tendon by scraping and crosshatching it with a knife. To diminish any tension on the tendon while it is healing, the position of immobilization in a cast should allow the transferred tendon to be in a relaxed attitude. For example, when the flexor carpi ulnaris is transferred to the extensor carpi radialis longus, the tension on the tendon should be sufficient to hold the wrist in 30 degrees of dorsiflexion. However, when the cast is applied, the wrist is immobilized in the overcorrected position of 45 to 50 degrees of dorsiflexion.

Postoperative Care and Training

Postoperative care and training are fundamental to achieving a good result. The following principles, given by Green, should be followed meticulously.

The age of the patient at the time of tendon transfer is an important preoperative consideration. The child should be old enough, preferably older than 4 years, to cooperate in training of the transfer. A delay in tendon transfer in the presence of muscle imbalance leads to progressive deformity. Usually, conservative measures should be undertaken to control deforming factors, but early surgery may be indicated when a delay in tendon transfer would result in increasing structural deformity. A common example is the rapid development of progressive calcaneus deformity of the foot with paralysis of the gastrocnemius-soleus muscles and strong ankle dorsiflexors. An early posterior transfer prevents the development of a deformed foot.

Support of the part in an overcorrected position should be continued until the muscle has assumed full function and there is no tendency for the deformity to recur. A bivalved cast or an orthosis holds the transferred tendon in a relaxed position.

It is best to teach the patient preoperatively to localize active contraction in the muscle to be transferred. Active exercises are continued postoperatively as soon as the reaction to surgery and pain have subsided. The surgeon should assist the physical therapist during the initial exercises. When tendon transfer is combined with arthrodesis, muscle reeducation is delayed until adequate bony union has taken place.

The patient is instructed to contract the transferred muscle voluntarily by moving the part through the arc of motion that was the original normal action of the muscle while the therapist manually guides the part to move in the direction that is intended to be provided by the transfer. For example, when the peroneus longus muscle is transferred anteriorly to the base of the second metatarsal, the active motion called for is eversion in combination with guided dorsiflexion, or if the anterior tibial muscle has been transferred posteriorly to the os calcis, active inversion is combined with guided plantar flexion of the ankle. In anterior transfer of the hamstrings to the patella for quadriceps femoris paralysis, the patient is placed in a side-lying position and asked to extend the hip actively (using the hamstrings) as the knee is guided into extension. If the flexor carpi ulnaris has been transferred to the extensor carpi radialis longus, the wrist is gently guided into extension as the patient turns it in the ulnar direction. With one hand the therapist should palpate the belly and tendon of the transferred muscle to ensure its contraction. In the beginning the exercises are performed in the bivalved cast. Motion of the concerned joint is executed slowly, steadily, and smoothly through as full a range as possible. Soon the limb is taken out of the cast and is properly positioned, and measures are taken to prevent stretching of the tendon out of its resting position.

Occasionally the patient is unable to contract the transferred muscle actively and has difficulty “finding” it. To enable the patient to use the transfer actively and to help in acquiring the feeling desired, the therapist may exert gentle mild tension on the transferred tendon, have the patient shift positions during attempts at active contraction, or advise the patient in the use of corollary motions. If difficulty finding the transfer persists after 2 weeks, electrical stimulation may be used to initiate contraction as the patient attempts to use the muscle. After a few sessions the patient begins to feel the transfer and to contract it voluntarily.

As soon as the patient is able to contract the transferred muscle actively, exercises in the direction of the original action of the muscle are discontinued and only motions in the new function provided by the transfer are performed.

When poor motor strength develops in the transferred muscle—that is, it can carry the part through the full range of motion with gravity eliminated—the physical therapist instructs one of the parents to perform the exercises with the child. The exercise regimen is supervised by the physical therapist and the surgeon, who check it at weekly or biweekly intervals.

Initially the limb should be retained in the bivalved cast for support, except during the exercise periods. As soon as the motor strength of the transfer becomes “fair,” use of a bivalved cast during the day is gradually discontinued. Controlled activities are permitted to develop function. These activities are permitted sooner in the upper than in the lower limb. The age and dependability of the patient are other considerations. Resistive exercises to develop power are begun whenever the transfer has a normal range of action and is “fair” in strength. It is also important to exercise the antagonistic muscles to prevent disuse atrophy.

The next stage of training is incorporation of the transfer into the new functional pattern. This is particularly important in the lower limb, in which the muscles are concerned with gait. For example, the action of a peroneus transfer may be good in that it can dorsiflex the ankle through a full range and take moderate resistance, yet during locomotion, voluntary control over the transfer may be lost and the patient may walk with a footdrop gait. The transition to walking requires diligent supervision. Of particular importance is the use of crutches, which protect the limb from undue strain and at the same time allow the patient to be taught to use the transfer and to become accustomed to it. First the patient is asked to take a single step, and the therapist ensures that the muscle contracts and dorsiflexes the ankle. As soon as the transfer functions throughout all the phases of a single step, the walking periods are gradually increased until the normal gait pattern becomes a conditioned reflex.

Orthoses should be used in the postoperative period judiciously and for specific reasons. Orthotic support protects the part and allows early activity. This is indicated particularly when paralysis is extensive, as in myelomeningocele. In a posterior transfer to the os calcis, for example, a plantar flexion–assist orthosis with a dorsiflexion stop at right angles and crutches may be used to assist in developing function in the transfers and prevent stretching. However, standing and walking exercises are also performed without the brace to stimulate function in the transfer. Prolonged use of a bivalved night cast is important to prevent the development of a contractural deformity that would oppose the action of the transfer (e.g., equinus deformity of the ankle in the setting of anterior transfer for dorsiflexion).

From the beginning, daily stretching exercises should be a part of the exercise regimen. Stretching and night support are continued over a long period until full strength has developed in the muscle and balanced function is observed between agonistic and antagonistic muscles with no tendency for recurrence of the original deformity. In fact, the use of stretching and active exercises should be a simple rule of daily living.

Arthrodesis to provide stability and correct osseous deformity may be indicated, particularly in the foot. However, if dynamic balance is established before the development of structural deformity, arthrodesis may be unnecessary. When it is necessary to combine arthrodesis with tendon transfer, muscle reeducation must be delayed until adequate bony union has taken place.

Flexion, Abduction, and External Rotation Contracture of the Hip

The shortened iliotibial band, which is in a plane anterior and lateral to the hip joint, draws the femur into flexion and abduction at the hip, with the pelvis as the fixed point. External rotation deformity results from maintenance of the malposture of the frog-leg position. The related muscles—the tensor fasciae latae, reflected head of the rectus femoris, sartorius, and external rotators of the hip—will undergo myostatic contracture if the fascial contracture is not corrected. The fixed soft tissue contracture causes anteversion of the proximal end of the femur.

Flexion and Valgus Deformity of the Knee and External Torsion of the Tibia

The iliotibial band crosses lateral to the axis of the knee. When it is contracted, a force is exerted on the lateral aspect of the joint and the tibia is gradually abducted on the femur. Its deforming action resembles that of a taut string on the concavity of an archer’s bow. Irwin proposed that flexion deformity of the knee develops as a result of the location of the band in a plane posterior to the axis of motion of the knee joint. However, subsequent studies did not support this observation. The short head of the biceps takes its origin in part from the intermuscular septum, which in turn is attached to the iliotibial band. Flexion deformity of the knee develops as a result of spasm and subsequent myostatic contracture of the short head of the biceps. Prolonged maintenance of the knee in flexion causes contracture of the patellar retinacula and soft tissues behind the knee.

External Torsion of the Tibia and Subluxation of the Knee Joint

The pull of the laterally located iliotibial band and the short head of the biceps femoris gradually rotates the tibia and fibula externally on the femur. When the contracture is not controlled, the deforming forces cause posterolateral subluxation of the knee with displacement of the fibular head into the popliteal space.

Positional Pes Varus

Positional pes varus results from an ill-fitted orthosis that fails to compensate for the external tibial torsion. The axes of the knee and ankle joints do not occupy the same horizontal plane in external torsion of the tibia. When an above-knee orthosis manufactured with these joints in the same horizontal plane is fitted to a limb with external tibial torsion, the appliance forces the foot into varus position so that the ankle is in line with the knee joint. Initially, the varus deformity is purely functional (the foot assumes normal alignment when the lateral upright of the orthosis is allowed to rotate externally on the thigh); it later becomes fixed because of permanent shortening of the soft tissues and adaptive osseous changes in the tarsal bones.

Pelvic Deformity, Lumbar Scoliosis, and Subluxation of the Contralateral Hip

In abduction deformity of the hip secondary to contracture of the iliotibial band, the pelvis is level with or at a right angle to the vertical axis of the trunk as long as the affected hip is maintained in abduction; however, when it is brought parallel to the vertical axis of the body in the weight-bearing position, the pelvis is forced to assume an oblique position. This pelvic obliquity results from contracture below the iliac crest. Lumbosacral scoliosis, convex to the low side of the pelvis, simultaneously develops. The contralateral hip subluxates.

Exaggerated Lumbar Lordosis

Exaggerated lumbar lordosis is produced by bilateral flexion contracture of the hips. It is a compensatory response to the increased pelvic inclination when the trunk assumes an upright position.

Pelvic Obliquity

Fixed pelvic obliquity is a common deformity after poliomyelitis and may be caused by suprapelvic, intrapelvic, or infrapelvic abnormalities. In an extensive study conducted in Korean patients, pelvic obliquity was classified into two major types and four subtypes relative to the resultant scoliosis. In major type I, the pelvis is lower on the short-leg side and we recommended ipsilateral abductor fasciotomy and, at times, contralateral lumbodorsal fasciotomy to correct the deformity. In type II deformities, the pelvis is high on the short-limb side as a result of adduction contracture of the ipsilateral hip, abduction contracture of the contralateral hip, or ipsilateral lumbodorsal fascial contracture.

Bivalved Casts

Static malpostural deformities of the lower limbs in the acute and subacute stages of poliomyelitis can be prevented by the use of bivalved casts to maintain the joints in neutral position. A horizontal bar in the posterior half of the cast or a rotational strap controls malrotation at the hips. The knees should be in slight flexion to prevent genu recurvatum. Passive exercises are performed to maintain full range of joint motion.

Passive Stretching Exercises

Minimal contracture of the iliotibial band can be corrected by passive stretching exercises, which follow the same steps as in the Ober test. These exercises can also be performed with the patient supine and the hip that is to be stretched hanging over the edge of the bed. In an older patient the iliotibial band can be stretched by the following exercise: the patient should stand sideways approximately 2 feet away from the wall with the hip that is to be stretched placed facing it. With the feet on the ground and the legs together, the hip is brought toward the wall to the count of 10 and is then returned to the original position. This exercise should be performed for 20 repetitions, 3 times a day.

Ober and Yount Fasciotomies

When the iliotibial band is contracted to such a degree that fixed deformity at the hip and knee with tilting of the pelvis has resulted, correction cannot be obtained by manipulative stretching or application of a series of plaster casts. The pelvis cannot be locked securely enough to permit stretching forces to be exerted on the shortened iliotibial band; instead, the pelvis is tilted into an oblique and hyperextended position, thereby stretching the lateral and anterior abdominal muscles on the side of the contracture.

Surgical intervention is the only way to correct the deformity. The shortened soft tissues must be sectioned proximally as well as distally by combining the Ober fasciotomy with the Yount procedure. As stated previously, the primary cause of the deformities is contracture of the intermuscular septa, the enveloping fascia, and the fibrosed muscular tissue in the partially involved muscles. Normal muscle tissue should not be divided.

Both lower limbs and hips are prepared and draped in sterile fashion. The Ober fasciotomy is performed through an incision that starts at the junction of the posterior and middle thirds of the iliac crest and then extends distally to the anterior superior iliac spine, where it swings posterolaterally for a distance of 10 cm. The wound flaps are mobilized to expose the sartorius, rectus femoris, tensor fasciae femoris, and gluteus medius and minimus muscles. The enveloping fascia of these muscles, the intermuscular septa, the intervening fibrosed muscular tissue, and the iliotibial band are sectioned as far back as the greater trochanter. The Ober and Thomas tests are performed to determine by palpation the occurrence of any tight bands, which are divided if present. Normal muscle tissue and the anterior capsule of the hip joint should not be divided. The contracted fibers of the Bigelow ligament can be released without entering the hip joint.

The Yount procedure consists of excision of a segment of the iliotibial band and the lateral intermuscular septum in the distal part of the thigh. A midlateral longitudinal incision is made beginning immediately above the knee joint line and extending cephalad for a distance of 10 cm. The subcutaneous tissue is divided and the wound flaps are mobilized by blunt dissection to expose the anterolateral aspect of the thigh in its distal fourth. Next a 7-cm block of the iliotibial band, the fascia lata covering the vastus lateralis muscle, and the lateral intermuscular septum are excised. It is important to divide the lateral intermuscular septum down to the femur. If it is contracted and contributing to flexion deformity of the knee, the lateral patellar retinaculum is also divided.

In severe cases with lateral rotatory subluxation of the knee, the biceps femoris muscle is lengthened by the fractional method, with extreme care taken not to injure the common peroneal nerve ( Plate 37-1 ). This lengthening can be performed through the same incision. An attempt at reduction is then made by forcibly extending and internally rotating the knee. Often, Z -lengthening of the fibular collateral ligament is necessary to achieve reduction.

Both the hip and the thigh wounds are closed routinely. Bilateral long-leg casts are applied with the knees held in full extension. Metal rings are anchored to the cast on both its anterior and posterior aspects so that the patient can be placed in suspension traction. One set of rings is placed in the distal fourth of the leg and another set in the proximal fourth. Rotational straps can be added to the plaster cast if necessary. The patient is placed on two or three half-mattresses so that the lower limbs can hang free at the edge of the mattress and the hips can be hyperextended or flexed by suspension ( Fig. 37-4 ). An infant or small child can be placed on a bent, hyperextended Bradford frame to achieve the same result. The opposite lower limb is flexed at the hip to obliterate the lumbar lordosis. The affected limb is gradually hyperextended, adducted, and internally rotated at the hip to stretch out all remaining contractural deformity. The same position of the hips can be achieved with the patient prone or supine. In patients with bilateral cases the hips are alternated several times a day. Manipulative stretching exercises are performed three times a day. Meticulous observation of circulation and sensation in the toes is imperative, especially if excessive shortening of neurovascular structures was observed at surgery.

Method of suspension traction after an Ober-Yount release of the iliotibial band.

In patients with myelomeningocele who have impaired sensation, stretching by the method described may cause pressure sores. The atrophied bones of these children may also be fractured easily by vigorous manipulations or stretching procedures.

Passive stretching by the suspension-traction method is continued for 3 weeks. As the child grows, with progressive longitudinal growth of the femur, contracture of the iliotibial band will recur unless passive stretching exercises and proper positioning of the joints in bivalved casts are continued during periods of growth.

Muscle Transfer

Dynamic balance about the hip is restored by appropriate muscle transfers. If the age at onset of paralysis and muscle imbalance is younger than 2 years, iliopsoas transfer to restore power of hip abduction is performed when the child is 4 or 5 years of age. If the coxa valga deformity is less than 150 degrees, a preliminary varization osteotomy is unnecessary; the valgus deformity will correct itself with growth once hip abductor power is restored. If the coxa valga deformity is greater than 150 degrees, it is best to correct the deformity and obtain a femoral neck-shaft angle of 110 degrees before iliopsoas transfer.

If at the time of paralysis the patient is older than 2 years, iliopsoas transfer may be postponed and the stability of the hip monitored periodically with radiographs. When the coxa valga exceeds 160 degrees and the femoral head starts to subluxate laterally, varization osteotomy is performed. In patients younger than 6 years, the femoral neck-shaft angle is reduced to 105 degrees; in older patients the angle is corrected to 125 degrees. Often, if dynamic muscle imbalance persists, valgus deformity will recur with growth. The procedure should be followed in 6 months to a year by transfer of the iliopsoas.

Varization Osteotomy

The operative technique of varization osteotomy follows the same principles as those of valgus osteotomy, as described in Chapter 35 . Any adduction contracture of the hip should be passively stretched and corrected by split Russell traction, with the hips gradually brought into wide abduction. Adductor myotomy of the hip should be avoided whenever possible. The anterolateral surface of the subtrochanteric region of the femur is subperiosteally exposed, as described in Plate 37-3 . The line of osteotomy is shaped like a modified dome with a lateral buttress of cortical bone in the proximal segment to lock the upper end of the distal segment while the femoral shaft is adducted. This procedure is the reverse of valgus osteotomy. Rotational malalignment can be corrected at the same time. I use Crow pins or threaded Steinmann pins and a Roger Anderson apparatus to fix the fragments together. Other surgeons may use a bone plate with four screws, a blade plate, or two staples. It is a matter of personal preference and depends on past experience. Blundell Jones exposed the trochanteric region of the proximal end of the femur posterolaterally with the patient in the prone position and corrected the valgus deformity by excising a wedge of bone with its base medially.

When the hip is completely dislocated, the hip joint capsule is stretched out and lax. Paralytic hip dislocation is easily reduced. In the beginning the femoral head can be relocated into the acetabulum by simple abduction of the hip. Later, however, soft tissue contracture may develop, and an initial period of skin or skeletal traction is then indicated. Prolonged immobilization of the hip in a spica cast after reduction is not recommended. Once the cast is removed, the dislocation will recur. The use of a solid hip spica cast does not correct the etiologic factors, and it has the additional disadvantage of causing disuse atrophy of muscles and bone. To stimulate normal proximal femoral growth, weight bearing should be restored as soon as possible.

Reefing and repair of the capsule are essential. These procedures are described and illustrated in Plate 16-3 . An iliopsoas transfer is performed at the same time to restore power of hip abduction and muscle balance about the hip. If the acetabulum is shallow and maldirected, the procedure may be combined with a Salter innominate osteotomy.

Indications and Contraindications

Several muscles have been transferred to restore knee extension power, namely, the biceps femoris, semitendinosus, sartorius, tensor fasciae latae, and adductor longus. ^† When the hamstring muscles are normal, they can be transferred anteriorly to the patella and ligamentum patellae to provide extension and stability of the knee. This procedure is advised when instability of the knee interferes with ordinary walking or when the patient will be able to dispense with an orthosis after such a transfer. Each case, however, must be considered individually. When the hip flexors are less than “fair” in motor strength, anterior transfer of the hamstrings is absolutely contraindicated. After surgery the patient will be unable to clear the limb from the floor, and consequently the disability will be greater. The triceps surae muscle must be at least “fair” in strength; if not, with loss of all dynamic posterior knee support, marked genu recurvatum will develop. It is preferable to have adequate strength of the gluteus maximus and hip abductor muscles. Before tendon transfer, any flexion contracture of the knee and equinus deformity of the ankle should be fully corrected by wedging casts. The mechanics of the patellofemoral articulation should be normal. Any significant malalignment of the lower limb, such as marked genu valgum, should also be corrected preoperatively.

† References .

Surgical Technique

The operative technique of transfer of the biceps femoris and semitendinosus muscles, as described by Crego and Fischer and Schwartzmann and Crego, is as follows ( Fig. 37-9 ). The patient is placed supine with a large sandbag under the ipsilateral hip so that the patient is tilted 45 degrees to the opposite side and the knee to be operated on is in semiflexion. A longitudinal incision is made over the posterolateral aspect of the thigh, starting immediately above the head of the fibula and extending proximally to terminate at the junction of the proximal and middle thirds of the thigh. The subcutaneous tissue and deep fascia are incised in line with the skin incision. The common peroneal nerve, located posteromedial to the biceps tendon, is identified and gently retracted posteriorly with moist umbilical tape. The biceps femoris tendon is dissected free of its surrounding soft tissues and retracted anterolaterally. At its point of attachment to the fibular head the lateral collateral ligament adheres to the biceps tendon; great caution must be exercised to protect and not divide it. Next the biceps tendon is detached from its insertion on the head of the fibula. Using sharp and blunt dissection, the surgeon frees the muscle bodies of the short and long heads of the biceps muscle proximally as high as possible while taking care to preserve their nerve and blood supply. The new direction of the line of pull of the transfer must be as nearly vertical as possible; if the transferred tendons run horizontally, the muscles will pull the patella in a posterior direction.

Transfer of the semitendinosus and biceps femoris tendons to the patella to restore knee extension.

Next a transverse incision is made over the anterior aspect of the knee, centered over the distal third of the patella. The subcutaneous tissue and deep fascia are divided. The wound flaps are undermined to expose the patella and patellar tendon. During a large Ober tendon transfer, a wide subcutaneous tunnel is made extending from the patella incision to the incision on the lateral aspect of the thigh. A 10- to 15-cm-long segment of the intermuscular septum and the iliotibial band is excised to allow free gliding of the transferred muscle belly.

The sandbag is next removed and placed under the opposite hip so that the patient is positioned semilaterally, turned to the ipsilateral side. A longitudinal incision is made over the posteromedial aspect of the thigh, beginning 3 cm proximal to the popliteal crease and extending to the junction of the middle and proximal thirds of the thigh. The subcutaneous tissue and deep fascia are divided. The semitendinosus tendon is isolated, and through a separate small incision over the anteromedial aspect of the proximal part of the leg it is detached from its insertion on the tibia. It is easy to identify the semitendinosus tendon in the distal leg wound by pulling on it in the proximal thigh wound; anatomically at its insertion the semitendinosus tendon is located posterior to the sartorius tendon and inferior to the tendon of the gracilis. The semitendinosus tendon is then delivered into the proximal wound and dissected free to the middle third of the thigh. Through a wide subcutaneous tunnel from the anterior transverse knee incision to the posteromedial thigh incision, the semitendinosus tendon is rerouted and delivered into the prepatellar area. Again the deep fascia is widely incised to avoid angulation and to permit free gliding of the semitendinosus tendon.

Next the prepatellar bursa is reflected and retracted to one side and an I -shaped incision is made through the quadriceps tendon and periosteum over the anterior surface of the patella. These tissues are stripped and reflected medially and laterally. With a -in drill, oblique longitudinal tunnels are made through the patella, starting at the superolateral and superomedial poles of the patella and emerging on each side of the patellar tendon. The tunnels are enlarged with progressively increasing sizes of hand drills and curets. The operator must be careful not to damage the articular surface of the patella.

With braided silk whip sutures on their ends, the biceps femoris tendon and the semitendinosus tendon are each pulled through their respective tunnels in the patella and sutured to the patellar tendon under tension. Additional interrupted sutures are placed proximally and distally to fix the biceps and semitendinosus tendons to the rectus femoris and patellar tendons. The soft tissues are sutured over the anterior aspect of the patella and the wounds are closed. A long-leg cast that holds the knee in neutral position but not in hyperextension is applied.

Postoperative Care and Functional Training

Meticulous postoperative care is important to obtain a satisfactory result. Tension on the transferred hamstring is prevented by avoiding flexion of the hip. The patient is kept supine in bed for 3 weeks, and it should be strongly emphasized to personnel that the patient is not to sit.

Functional training of the transfer is begun 3 to 5 days after surgery or as soon as the patient is comfortable. The patient is placed on his or her side to eliminate the force of gravity. The knee and hip are slightly flexed, and the patient is asked to extend the hip and knee. Active contraction of the hamstrings as knee extensors is initiated by having the patient execute his or her former action of hip extension. Active guided knee extension exercises are then performed from starting positions of greater knee flexion and decreasing hip flexion; the patient should soon be encouraged to divorce the two movements of knee and hip extension. The active exercise of knee extension is performed with the hip in the partially flexed position of the normal pattern of locomotion without, however, extending the hip.

The function of the antagonistic muscles should not be ignored. Active knee flexion exercises are carried out (through a limited range initially) while making sure that the transferred muscle is not used for both extensor and flexor functions.

As soon as the transferred muscle is “fair minus” in motor strength, the patient, while still supine in bed, is asked to go slowly through the motions of walking: namely, ankle-foot dorsiflexion and hip flexion, followed by knee extension (using the transfer), hip extension, and ankle plantar flexion. The same exercises are performed standing, first in parallel bars and then in crutches. During the stance phase, hyperextension of the knee should be avoided. A bivalved cast is worn at night for 8 to 12 months to prevent stretching of the transferred muscles. Orthotic devices to support the knee are not usually necessary unless their use is indicated for control of the foot and ankle.

Complications

Genu recurvatum is a not infrequent complication; it occurs in 10% to 20% of reported cases and is a natural consequence of an operation in which the hamstring muscles that normally provide dynamic support to the knee posteriorly are removed and transferred anteriorly. Other factors contributing to its pathogenesis are (1) pes equinus, (2) selection of patients with inadequate (less than “fair”) strength in the triceps surae muscle, (3) immobilization of the knee in hyperextension in the postoperative period, (4) lack of an adequate and diligent postoperative exercise regimen with resultant failure to develop active knee flexion against gravity, and (5) improper use of orthotic support after surgery. The development of genu recurvatum can be minimized if the preceding factors are circumvented.

Lateral instability of the knee often results from inadvertent operative division of the tibial or fibular collateral ligaments while detaching the semitendinosus and biceps tendons from their insertion.

Lateral dislocation of the patella commonly occurs when the biceps femoris alone is transferred. This complication can be prevented by transfer of both the biceps and the semitendinosus muscles.

Failure of transfer may result from denervation of muscles during proximal dissection, inadequate postoperative training, or binding down of the transfer by adhesions in sharp angular pathways to the patella.