SPINAL DEFORMITIES

Scoliosis

Lateral or sideways curvature of the spine, occurs most often just before puberty during growth spurts, but also can be caused by cerebral palsy and muscular dystrophy.

The condition of sideways spinal curve is called “scoliosis.” From the back, the spine of someone with scoliosis looks similar to an “S” or a “C” shape, instead of a straight line. This can make the person’s shoulders or waist seem uneven. Some vertebrae may also be slightly rotated, making one shoulder blade jut out more than the other.

In more than 80% of cases, a specific cause is unknown. This is called “idiopathic” scoliosis, meaning “undetermined.” It is particularly common in adolescent girls, but can occur in both sexes at any time from birth into adulthood. Known causes include congenital spine abnormalities present at birth (congenital scoliosis), neurologic disorders (neuromuscular scoliosis), genetic conditions, and many other causes.

Surgery is performed for curvatures greater than 50 degrees for adolescent patients and adults. Surgery also can be performed for smaller curvatures if they are bothersome to the patient or if other symptoms are present as a result. The goals of treatment are to correct the curve and to prevent further progression. Common methods include placing metal implants onto the spine, which are attached to rods which correct the curvature and hold it in place until fusion (or knitting) of the spine elements together.

Kyphosis

A forward, exaggerated rounding of the back, most common in older women due to osteoporosis, but can also occur in infants and teens.

Infants can be born with congenital spine problems due to failure of formation or failure of segmentation on the front part of one or more vertebral bodies and discs.

Scheuremann’s kyphosis occurs when the front areas of the vertebrae grow slower than the back areas. This produces wedge-shaped vertebrae. This process happens during rapid bone growth, usually between the ages of 12 and 15 years in males, or a few years earlier in females.

Surgery allows significant correction to be achieved, usually without needing post-operative bracing. Pedicle screws are inserted and connected with two rods, which allows gentle straightening of the spine.

Spondylolisthesis

Occurs when one vertebra slips forward onto the vertebra below it, causing numbness or pain in the back or legs.

Normally, a part of the Lumbar-5 vertebra called the pars interarticularis stabilizes a bony hook that keeps the L5 vertebra from sliding downward onto the sacrum. If a fracture removes this stability, the bone may move forward to varying degrees.

For a majority of patients, fusing the L5 vertebra to the sacrum is the first choice. The procedure involves removing any loose fragments and placing a bone graft that will help fuse the two vertebra together while also removing any pressure on the nerves.

Revision Surgery

Additional surgery to correct a problem that is worsening or did not heal properly after previous procedures. Post-surgical deformities can occur in patients who have previously undergone spinal surgery either for scoliosis or for other conditions.

At times, especially after extensive surgery, the spine will lose its ability to support itself in a normal position. Also, every fusion procedure has a small chance that the bones will not join together. Patients can develop scoliosis or even suffer arthritis.

Instrumentation and osteotomy techniques allow repositioning the spine. Posterior osteotomy and pedicle subtraction osteotomy are two techniques commonly used to correct these post-surgical deformities.

Flatback Deformity

Forward posture usually due to a flattened lumbar spine from postoperative or degenerative changes. When viewed from the side, the patient’s head may be several centimeters in front of their hips.

The lower back has lost its normal inward curvature or lordosis. As a result, patients with this condition are unable to stand upright and usually tilt forward.

This occurs in patients who had previously undergone spinal surgery either for scoliosis or for degenerative low back conditions.

Surgical remedies include anterior osteotomies, posterior fusion and instrumentation to restore normal curvature of the lower back, enabling a patient to stand upright.

SURGICAL PROCEDURES

Anterior Release

Sometimes performed in cases of several scoliosis. This involves removal of the disc from the front, by approaching the front of the spine either through an open incision or with a scope (thoracoscopic technique) and releasing the disc space.

After the discs at the appropriate levels of the spine have been removed, bone (either the patient’s own bone and/or cadaver bone) is added to the disc space to allow it to fuse together.

Posterior Spinal Fusion

Posterior fusion provides permanent stabilization in the corrected position and is achieved by removing the joints between the vertebrae to be fused, usually all the vertebrae which are involved in the curve. Bone graft — either from the pelvis, ribs, or from the bone bank — is placed in each joint space which has been removed. Over time (4-6 months), the graft incorporates to the vertebral bone, and the operated portion of the spine heals into a solid block of bone which cannot bend, thus eliminating further progression of the curve.

Surgery allows significant correction to be achieved, usually without needing post-operative bracing. Pedicle screws are inserted and connected with two rods, which allows gentle straightening of the spine.

Osteotomy

Vertebral Column Resection
This is the most powerful procedure of all spinal osteotomies. It is necessary when there is a severe bend in a small area. It involves essentially dislocating the spine in a controlled manner and realigning it in the proper direction. Additional bone is removed beyond a pedicle subtraction osteotomy, and a strut graft or cage is placed between the cut vertebra.

Pedicle Subtraction
Surgeons use this procedure to cut through kyphotic segments. It is referred to as a “closing wedge osteotomy” because a triangle of bone is removed so the bone can angle backward. The procedure is particularly powerful, especially in the lumbar spine where the bones are bigger, and small corrections can lead to large improvements in posture. It is similar to placing a wedge between bricks, creating a sudden backward bend in the spine. The surgery requires the support of instrumentation above and below the osteotomy.

EQUIPMENT & IMPLANTS

Hooks

There are many types of hooks — such as pedicle, sublaminar, or infralaminar hooks — named to describe where they anchor on the spine. Hooks may be used alone or to secure rods or wires in place.

Wires

Medical grade wire is flexible and strong. The surgeon can sequentially tighten or loosen the wire to apply a precise amount of tension to a particular area of the spine. Special tools assist the surgeon to measure and apply tension, and to cut and crimp the wire prior to securing into place.

Rods

Some rods are rounded and smooth; others are threaded. Rods are usually used in pairs and are available in many pre-cut lengths. In some cases, the spine specialist will modify the length to fit the patient’s anatomy, which may include contouring the rod to match the curve of the spine.

Screws

Screws are used to secure rods in place. Bone screws are available in different lengths, widths, and at fixed or variable angles.