Study Guide

Poliomyelitis

Key Points:

Description:

Poliomyelitis is a viral illness that affects the central nervous system anterior horn cells which can ultimately result in a variety of orthopaedic deformities and functional problems. Presenting symptoms include fatigue, fever, vomiting, headache, neck stiffness, and limb pain (WHO online, 2018). The limb symptoms can range from pain and stiffness all the way to paralysis. (Sheth, 2007). Polio commonly affects the upper and lower limbs, as well as the spine. Polio tends to deteriorate later in life and some patients can develop post-polio syndrome (Houlden, 2007).
 

Epidemiology:

Although there is evidence of polio’s existence going back millennia, it was described by Jacob Heine in 1840 (Gucker, 1981). The last major US outbreak was in the 1950’s (Sheth, 2007). However, 22 cases of wild polio virus infection were reported in 2017. Endemic transmission continues in Pakistan, Nigeria and Afghanistan. As there is currently no cure, prevention strategies are critical. Access to vaccination may be limited especially in war zones (Sales de Gauzy 2017). According to the World Health Organization, polio mainly affects children under 5 years of age. Approximately 1 in 200 infections lead to irreversible paralysis (as well as a 5-10% mortality rate due to respiratory paralysis) (WHO online, 2018).  Due to adequate vaccination, the acute illness is not seen in the “developed” world; most cases encountered in developed countries are patients in later phases of the disease (Houlden, 2007).
 

Clinical Findings:

Poliomyelitis progresses through three traditionally described phases: There is also now a fourth distinct phase termed post-polio syndrome for those who had childhood polio and go on to demonstrate new neuromuscular symptoms years after the acute phase had subsided. Its symptoms include worsening muscle weakness, muscle pain, severe fatigue, and new onset weakness (Sheth, 2007). The cause is unknown, but there are several hypotheses including neural fatigue, mitochondrial disruption and damage to the reticular activating system. The theory that post-polio syndrome is due to reactivated polio has not been credited, as laboratory studies have been unable to identify the active polio virus in the body (Houlden, 2007). 

Watts has written on some key points during the assessment of a patient with poliomyelitis (Watts,1992).

Imaging Studies:

There are no specific imaging issues related to poliomyelitis aside from the standard imaging techniques for the anatomic areas of interest. Bending films of the spine have a more prominent role in polio scoliosis as mentioned in the spine section below.

Treatment:

The overall treatment approach generally can be subdivided into the acute paralysis, recovery, and permanent residual paralysis stages (Joseph, 2015).
Orthopedic deformity management intensifies in the recovery and residual phases. The overall goals of orthopaedic surgery may include treatment of pain, muscle force imbalance, and joint instability as well as deformity correction and allowing for more effective use of orthoses and braces. Surgery cannot improve muscle strength, and surgical interventions are mainly to optimize brace comfort and utility as opposed to obviating the need for bracing (Sheth, 2007).

Watts (1992) provides further framework for treatment with provision of these sequential priorities:
a. Get patient up and walking 
b. Correct the factors that will create deformity with growth 
c. Correct factors that will minimize need for lifetime external bracing 
d. Correct upper extremity problems
e. Treat scoliosis


Lower Extremity  
Gait: 
Full motion of the hip and knee are important for lower extremity function and efficient gait. Contractures should be corrected when possible to permit more effective gait. This may help prevent joint degeneration as well (Sheth, 2007).

To walk well one needs strength of gluteus maximus, quadriceps and gastrocnemius. Quadriceps paralysis is common and when quadriceps are weak this results in a classic hand on thigh gait. Walking is possible with mild equinus and delayed heel strike, even with bilateral quadriceps paralysis (Varghese, 2018).
For inadequate strength other options are floor reaction or knee ankle foot orthosis, and in older patients, a femoral supracondylar recurvatum inducing osteotomy (Joseph, 2015).

Those with flail lower extremities can stand with crutch assistance and a KAFO locked in knee extension and ankles in slight dorsiflexion. This relies on hyperextension through the hips and a robust anterior hip capsule for support. This may permit a swing through gait but the energy demands are high (Sheth, 2007).
Hamstring transfer to quads can restore some knee extension, but adequate hip extensor and ankle plantarflexor strength and absence of sagittal knee deformity are prerequisites (Joseph 2015).

Paralysis of gluteus maximus leads to characteristic lurch with lumbar spine arching backwards. The hip could be completely flail but often some muscles are spared. Iliopsoas, external oblique or free gracilis transfer may minimize Trendelenburg lurch due to loss of abductors (Joseph, 2015).   


Hip Deformity
Typical hip deformities are flexion, abduction, external rotation. Abduction and adduction deformities can lead to pelvic obliquity, lumbar scoliosis and hip dislocation. Soft tissue releases are the mainstay of treatment but osteotomy options exist.  Manual muscle testing is important when dealing with abduction contracture because leaving a bit of residual abduction can prevent Trendelenburg lurch (Joseph 2015).
Total hip arthroplasty is an option for hip arthritis but with many technical considerations (Sheth, 2007).

Knee Deformity
Both recurvatum and flexion deformity can occur.   Mild recurvatum and equinus may actually be helpful in the setting of quads paralysis (Joseph, 2015).

As the posterior knee joint capsule may continue to become stretched, painful recurvatum and degeneration of the knee can occur. KAFO can protect the knee and provide improved stability for walking. Reconstruction of the posterior knee capsule is not possible. Total Knee Arthroplasty (TKA) is an option in this setting as well as in the setting of a flexion contracture. Flexion contracture of the knee requires constant use of the quadriceps throughout the gait cycle resulting in excessive fatigue. Hamstring release and posterior capsulectomy are treatment options (Sheth, 2007). Supracondylar extension osteotomy is also an option (De Morraes Barros Fucs, 2005).

Another typical knee deformity is valgus, associated with iliotibial band (IT) contracture, hip abduction contracture, leg length discrepancy and valgus foot.
Surgical release or lengthening of the IT band can help correct the hip and knee, although complete release should be avoided. Varus knee deformity has also been described and is associated with osteoarthritis. KAFOs may be helpful but less so than with valgus than with other deformities. If severe, TKA should be considered (Sheth, 2007). Arthrodesis of the knee may be indicated in severe knee arthritis but never on both sides (Huckstep, 2000). Tibial rotation osteotomy is an option for significant external rotational deformity at that level and is particularly effective if combined with subtalar arthrodesis (Asirvatham, 1990).

Ankle Deformity
Ankle equinus is common leading to recurvatum at the knee. This can be accommodated by heel lift but places excessive stress on the calf to control the leg. Lengthenings are often needed to permit bracing (Sheth, 2007). 

Foot Deformity
Virtually any combination of cavus, planus, equinus, calcaneus, hindfoot varus/valgus and forefoot abduction/adduction are possible based on the distribution of muscles which are affected. Tendon lengthening and releases are performed for contractures and manual muscle testing should be performed before considering transfers. Younger children are often treated with tendon surgery whereas bony surgery can be used for older children. Extra articular surgery is preferred when possible. Tarsal wedge resection can be used and wedges can also be planned intraarticularly to perform variations of triple arthrodesis as needed (Joseph, 2015).

Upper Limb Deformity
Upper limb pain is common in polio. It may occur in the ‘polio-affected limb’ as well as be associated with mobility aids in the non-affected limbs (Koh, 2002).

Shoulder
Shoulder weakness affects a significant number of polio patients. Loss of strength can have a significant impact on the use of upper extremity aids. Consideration of adaptive equipment to remove as much strain on the shoulders as possible may help to avoid common problems such as rotator cuff tears.  With significant impairment, rotator cuff repair should be considered or debridement if irrepairable (Sheth, 2007). 
Glenohumeral arthrodesis may be helpful if there is sufficient strength in scapulothoracic muscles. Watts recommends the age of 6-8 for this procedure (Watts, 2018). Shoulder arthroplasty can give effective pain relief, but is at risk for instability (Werthel 2016).

Elbow
There are some options for supplementing elbow flexion such as the Steindler flexorplasty or a triceps transfer. The decision to proceed must be balanced with consideration for potential loss of elbow extension power. It would be contraindicated if extension power is required for crutch or wheelchair function (Joseph 2015).

Wrist/Hand
Chronic wrist pressure due to crutches and cane use can lead to an increased incidence of carpal tunnel syndrome. When there is carpal bone subluxation, arthrodesis can be effective in stabilization (Sheth, 2007).

The loss of opponens function has significant implications for eating and drinking as well as for ambulation. The treatment options are splinting and tendon transfers (FDS of ring finger), although due to high risk of the tendon transfer stretching out, treatment may ultimately require a 1-2 metacarpal fusion (Watts, 2018).

Spine
Joseph and Watts describe scoliosis in polio in 2 main groups:
1. Young Children who suffer extensive trunk muscle paralysis and develop scoliosis very early.
2. Those in whom it develops later in childhood, usually in lumbar region.

Although mobility assessment is a component of every orthopaedic spine assessment, there is added emphasis in polio regarding the degree to which mobility and alignment of the spine can greatly influence the ability to walk and thus must not be considered in isolation from the rest of the body. Loss of lumbar lordosis in the setting of weak hip extensors, and loss of lumbar spine mobility in marginal ambulators may be particularly problematic (Joseph, 2015).

Bending films may be used more in the ongoing monitoring of scoliosis as curve flexibility can continue to be quite substantial even with larger magnitudes, and may allow a delay in surgery.  There is little role for orthosis management. The surgical techniques are largely those utilized in other forms of scoliosis (Joseph, 2015).
There is some evidence that longer and more rigid curves benefit from anterior and posterior approaches, although this evidence precedes the modern era of pedicle screw techniques (Leong 1981).

Fixed pelvic obliquity, depending on severity, can be treated with combinations of paraspinal/pelvic area fascial releases or bony surgery in the form of hip stabilization or spinal fusion (Lee 1997).
 

Complications:

Post-polio survivors may develop fatigue, muscle and joint pain, as well as weakness in both previously affected and unaffected muscles. The median post-polio onset time of these symptoms is 30-40 years (Halstead, 1985). There is also frequent reporting of cold intolerance and insomnia (Festvag, 2016).

The most common long term orthopaedic problems in polio are brace issues, increasing weakness, knee recurvatum and ankle equinus. Many of these problems are found 30 years later, due to weak musculature and chronic mechanical strain on substituting ligaments (Perry, 1985).

The risk of falls in Poliomyelitis may be 4 times higher than the general population. Poliomyelitis has been cited as a risk factor for osteoporosis especially in the affected limb.  These combine for a cumulative incidence of fracture in the affected limb of approximately 40% (Gupta, 2016).

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Luke Gauthier, MD