3.9 Clinical presentation of spinal deformities

This chapter gives an overview of the spectrum of spinal deformity, its classification, and the broad principles of management.

Spinal deformity has been recognized at least since the Egyptian civilization. Various forms of external traction, bracing, and manipulation have been used to treat these deformities with doubtful benefit. It has been recognized that there are extraordinary deforming forces at work, particularly during growth.

Epidemics of tuberculosis and poliomyelitis in the developed world in the early part of the twentieth century precipitated considerable advances in the management of spinal deformity. Both poliomyelitis and tuberculosis are responsive to public health measures. This is not the case for other forms of scoliosis, despite school screening programmes in some countries. The cause or causes of adolescent idiopathic scoliosis, the most common form of scoliosis, remain elusive.

The convention is to describe the magnitude of curves by Cobb angle, and the direction of convexity (right or left). Scoliosis surgeons usually view erect radiographs as if seen from behind. Radiographs give a two-dimensional view of the spine. Scoliosis is a complex deformity involving rotation of the apical vertebrae out of the curve. This means that at the apex the vertebral body lies lateral to the tip of the spinous process. The experienced eye is familiar with this rotation, and it should be borne in mind when considering the nature and severity of the deformity.

A scoliosis is best seen with the patient bent forward sufficiently to place the apex of the curve on the skyline. If the spine is rotated, this is reflected in a rib hump in the thoracic spine or a loin hump in the lumbar spine (Figure 3.9.1). This is formalized into the Adams forward-bending test. Surface topography is useful for defining and monitoring the changing shape of the back during growth and after treatment. It can reduce the use of radiography, and may detect a deteriorating curve earlier than is the case with radiographs. A variety of commercial systems are in use, including ISIS2 (Figure 3.9.2), although there is no standard for data presentation. ISIS2 offers improved precision and sensitivity to change of rib hump measurements and truncal asymmetry.

Sagittal profile and the capacity to keep the head over the hips when standing still are crucial elements in understanding spinal deformity. The spine is usually lordotic at the apex of the curve. Some believe that the lordosis is the underlying cause of the curvature. Kyphosis is an important deformity which is sometimes more dangerous to the spinal cord than scoliosis (Box 3.9.1). The thoracic and sacral regions of the normal spine have physiological kyphosis, which in pathological situations can become excessive. The cervical and lumbar spines are normally lordotic. Loss of lordosis in both parts of the spine can be painful—the so-called flat-back syndrome. If any part of the spine becomes excessively kyphotic, without the capacity to compensate through lordosis, sagittal balance is affected. A localized kyphosis (kyphos or gibbus), for whatever reason, poses a particular threat to the spinal cord. Kyphosis can be assessed clinically by the same methods used for the assessment of scoliosis. Surgical treatment of kyphosis carries a higher risk to spinal cord function compared with surgery for scoliosis.

The history should establish the first identification of the deformity and its evolution. Family history is important. The obstetric history, childhood illnesses, and the onset of menarche (the first menstrual period), if relevant, should be reviewed. Many curves are painless, but night pain, rest pain, or fatigue pain should be identified. The patient should be checked for neurological and cardiopulmonary symptoms, and asked about analgesic usage and absence from school or work.

It is useful to establish how aware the patient is of the curve, as this may have a bearing on subsequent management. The distress that a curve causes to the patient and his or her family may be out of proportion to its severity.

The examination of scoliotic patients should be carried out with care. Adolescent females in particular are often unused to doctors and are embarrassed to undress. The parents or carers should be present if possible. Gowns may reassure the patient, but conceal vital signs.

Examine the undressed patient from behind while he or she is standing up. Then ask the patient to perform forward and side bending to review the shape of the rib hump and spinal mobility. Assess the level of the pelvis. If the pelvis is tilted, it is sometimes useful to use blocks to level it before assessing the spine. A plumb line from the vertebra prominens should fall through the natal cleft. Deviations from this should be recorded, with the direction measured in centimeters (trunk shift). Sagittal balance should be assessed to ensure the head is over the hips with knees extended.

Signs of puberty are useful for the assessment of growth potential. In girls, pubic hair and breast development occur at the start of the adolescent growth spurt, and menarche towards the end of it. In boys, pubic hair appears before the start of the growth spurt. Axillary hair appears at the end of growth in both sexes.

Note any deviations from the normal pattern of curve, and identify the site of any pain by asking the patient to point this out. It is important in the growing child to record height on a growth chart. Some also make regular records of sitting height and weight.

The whole skin should be seen to check for café au lait spots (neurofibromatosis type 1, Chapter 1.13) (Figure 3.9.3). Check for hairy patches, nevi, and dimples in the midline over the spine (present in spinal dysraphism). Note the presence and type of foot deformities, lower-limb asymmetries, truncal and breast asymmetries, skull/facial asymmetries, and handedness.

A neurological examination is important. Focus on evidence of long tract signs (reflexes and plantar responses), evidence of asymmetric muscle wasting, the presence of abnormal abdominal reflexes, posture, gait, and cranial nerve abnormalities.

Radiography should be used with caution, particularly in the growing child. Low-dose regimens, fast films, and rare earth screens should be used. Eos claims to involve 10% of this exposure only (http://www.biospacemed.com/). Gonadal shielding can be used after an initial unprotected film. Erect anteroposterior and lateral radiographs, using long plates where necessary, are taken at the first encounter. Supine lateral bending films are only indicated just before surgery to help define the curve for instrumentation. Bone age can be determined by an anteroposterior radiograph of the left wrist, but the Risser sign and the presence of a vertebral ring apophysis provide a good indicator of spinal growth potential.

Surface topography has been used to record the shape of the back. A variety of devices from simple to complex are available. The scoliometer measures tilt in degrees; the body contour formulator is a device to transfer shapes onto paper. Surface topography systems, such as Quantec and ISIS2, measure elements not seen on radiographs.

Magnetic resonance imaging (MRI) is used in patients with pain, where the aetiology is uncertain, and where there is suspicion of tumor or infection.

School screening is widely used in some countries. However, its value is questioned in other countries, including the United Kingdom. Detection depends on awareness of scoliosis amongst school doctors, physical education teachers, and ballet teachers, as well as parents. Parents often do not see their teenage children undressed, and so these ad hoc methods can result in late presentation of curves. School screening leads large numbers of teenagers and anxious parents overloading a busy service. Screening also depends on the value of and compliance with early bracing, as it is assumed that this treatment prevents progression of the more severe curves. These issues are discussed in Chapter 3.14.

Apart from bracing and plaster jackets, traction is sometimes used for preoperative correction of stiff or large curves. Many centres have abandoned these techniques, except for the most severe curves. Halo pelvic traction was a very powerful technique which has largely been abandoned. Halo femoral or halo chair traction is sometimes used in very severe curves. Preoperative Cotrel or dynamic traction is used still in some centres, but there is little evidence of efficacy.

Most techniques depend on obtaining a solid fusion. In posterior surgery, it is vital to destroy the apophyseal (facet) joints. Autologous bone graft is best, but allograft and artificial materials avoid problems with the bone donor site. Unfortunately there is a tendency for the rib hump to recur following fusion, whatever system is used, especially in the younger patient with growth potential. The common surgical techniques used in spinal deformity surgery are described in the rest of this section.

Epiphysiodesis has a limited place in the management of early-onset idiopathic scoliosis. It involves damaging convex growth plates with a view to preventing progression in the young child. Subcutaneous distraction rods can be distracted at regular operations, but there is a high incidence of complications. Other surgeons use a Luque ‘trolley’, where two rods are fashioned into a U-shape. These are placed with the bend at each end of the curve, and wired onto the laminae. In theory this allows the rods to slide on one another as the spine grows. Titanium ribs (VEPTR) are designed to serially distract the thorax to develop respiratory function.

These procedures are designed to reduce the size of the rib hump by resecting, transposing, or even transplanting ribs, and are often used at the end of growth. The excised ribs sections can be used as bone graft.

This is used where correction is likely to cause spinal cord damage. In the past, prolonged decumbency on a plaster bed was used. Now a well-fitting plaster cast is the norm. A fusion in situ may result if a plaster cast is used (but by no means always), implants are removed because of evidence of spinal cord damage intraoperatively.

The Harrington system is a distraction rod with hooks at each end (Figure 3.9.4) widely used from 1950 to 1980. Good corrections can be obtained, but these may be partially lost before the fusion becomes solid. This technique has not been very successful in derotating curves. It has been enhanced with sublaminar wires (Figure 3.9.5)

Eduado Luque of Mexico City was the first to promote the use of sublaminar wires. The rods can be contoured so that their lower ends are driven into the pelvis (Galveston technique, Mehdian technique). This is especially valuable in neuromuscular curves with pelvic obliquity. The Hartshill rectangle system uses sublaminar wires. This has been promoted for the fixation of all types of scoliosis, but it is difficult to use and fixation to the pelvis is unsatisfactoy. Now it used to supplement other systems particularly when bone quality is poor. A current sublaminar tape system (universal clamp) shows promise where bone quality is poor.

The Cotrel–Dubousset (CD) system was the first specifically designed for the treatment of adolescent idiopathic scoliosis. It depends on contouring a knurled rod in the concavity of the curve. This is secured by hooks and pedicle screws to the spine, and correction is obtained by rotating the rod so that its curve lies in the sagittal plane. A second rod is then placed on the convexity of the curve and secured to hooks and cross-links. This system is adaptable to a wide variety of applications. The Texas Scottish Rite Hospital (TSRH) and Isola systems uses similar techniques, but are engineered using a smooth rod.

The Universal Spine System (USS2) uses side-opening screws and hooks, and a smooth rod which allows the rod to be contoured into the shape required (Figure 3.9.6). The spine can then be pulled onto the rod, obtaining the correction (similar to the Luque method). Variations on these methods are constantly been developed but the extra gains in correction are obtained at high cost.

The Dwyer system was the first system designed for anterior surgery and was a most important development. It uses titanium screws and staples, which are crimped onto a titanium cable placed in tension around the convexity of the curve. It risks kyphosing the spine. Zielke (VDS) system uses a 4-mm threaded rod which allows selective tightening of each level (not possible with the Dwyer system once the screw head has been crimped onto the cable) and a derotation device which allows superior correction. The disadvantage of this system is that the threaded rods are fiddly and the rod-tightening process is tedious. The rod fracture rate was 10–20%. The Webb–Morley system used a soft rod which is placed in tension like the Dwyer cable, but each screw can be individually adjusted. The TSRH system and latterly the USS2 have also been adapted to the front of the spine (Figure 3.9.7). Here it is possible to use a rod-rotation manoeuvre to obtain correction, as well as pulling the implants onto a prebent rod.

Spinal surgery has become one of the leading specialities involved in litigation (second to obstetrics in the United Kingdom). Good practice and risk management should become second nature to a spine surgeon. Litigation often arises where patient’s expectations of the outcome of a procedure are not matched to reality. The surgeon should give a reasoned account of the possible natural history of the condition (not always easy to do) and a careful explanation of the risks as well as the benefits of a procedure. Careful and regular record-keeping is essential, especially where difficult decisions are involved and when things are going wrong. The consent process is often prolonged, and may be aided by counselling by non-medical practitioners (we use experienced physiotherapists) and contact with other patients who have had similar procedures.