Lumbar Flat Back Syndrome
The human spine has natural curvatures. In the frontal plane (looking at the patient from behind) the spine should be straight. Flat back syndrome affects the sagittal plane (looking at the patient from the side view). When looking from the side, the spine has normal curvatures. In the neck (cervical spine) and low back (lumbar spine) there is normally an inward curvature or sway back known as lordosis. In the thoracic spine there is an outward curvature known has kyphosis or hunchback. These curves normally balance out each other so that when the patient stands they are well balanced with their head straight above their hips when viewed from the side. Standing in this position minimizes the effect of gravity and allows the patient to stand with the best posture and use the least energy when moving or walking [Figure 1].
Flat back syndrome is a condition that leads the normal curvatures of the spine to become imbalanced, causing the patient to lean forward. Flat back syndrome refers to a loss of the normal lumbar lordosis or swayback appearance. Patients with flat back syndrome typically notice difficulty with standing upright or have ongoing back or leg pain. Symptoms usually worsen as the day goes on and the patient will feel they lean further and further forward the longer they try to stand erect. The severity of the symptoms usually depends on the amount of curvature the patient develops and difficulties with standing erect [Figure 2].
Figure 2: In patients with flat back syndrome, a loss of normal lumbar curvature causes an imbalance of the spine. The patient’s head begins to lean forward, away from the body and they may have trouble standing upright. This imbalance can cause muscle fatigue and pain.
Flat back syndrome was first noted in patients who had received a specific type of spinal instrumentation for the treatment of scoliosis. The earliest types of implants allowed the surgeon to straighten the spinal curvature when viewed from the back but also to decrease the spine's normal curvature when viewed from the side. This instrumentation has a tendency to flatten the normal lordosis of the lumbar spine. The Harrington instrumentation system was utilized from the 1960s to the early 1980s. Many patients treated with Harrington rods did very well for years or even decades after their surgery. However, the unnatural position of the spine led to the remaining discs below the fusion to degenerate over time, ultimately leading to an even greater loss of lumbar lordosis and symptoms [Figure 3].
Figure 3: This patient is a 37-year-old woman who had scoliosis correction surgery as a teenager. At that time, the rods used to correct the scoliosis were straight and as a result, the patient has developed a loss of normal spinal alignment when viewed from the side.
Current scoliosis implant systems and surgical techniques allow for surgeons to correct the spine in multiple planes, thereby decreasing the risk of developing lumbar flat back syndrome [Figure 4].
Figure 4: Modern spinal instrumentation techniques allow for correction of spinal alignment in all dimensions. By fusing the spine in a natural position, the risk of flat back syndrome is greatly decreased. This x-ray, taken from the side of a patient who has had scoliosis correction surgery, demonstrates the ability to contour the rods and avoid flat back deformity.
Flat back syndrome may also occur as the result of number of other conditions. The term flat back syndrome has been broadened to include any patient with a decrease in lumbar lordosis causing symptoms. Flat back syndrome can occur as a result of any condition that shortens the front portion of the spine, causing the patient to lean forward. Flat back syndrome may develop as the result of the following cause.
DEGENERATIVE DISC DISEASE:
For some patients, progressive degeneration of the intervertebral discs or the shock absorbers of the spine may lead to a loss of height in the front part of the spine. As the disc degenerates the spine begins to lean forward and lumbar lordosis decreases. The patient may develop pain as a result of the degenerative disc disease or as a result of the spinal imbalance that occurs [Figure 5].
Figure 5: Degeneration of the discs in the lumbar spine causes a loss of height in the front part of the spine. As a result, the normal lumbar lordosis (red arrow) decreases and flat back syndrome may develop.
LUMBAR POST LAMINECTOMY SYNDROME:
Lumbar flat back syndrome may develop for some patients who have previously been treated with laminectomy or other lumbar surgery to decompress the spinal nerves to treat stenosis. These procedures can lead to a decrease in lumbar lordosis and in some cases spinal instability may occur. Ultimately this decrease in lumbar lordosis may lead to the symptoms of lumbar flat back syndrome.
VERTEBRAL COMPRESSION FRACTURES:
Compression fractures are often the result of weakening of bones of the spinal bones due to osteoporosis. This can lead to loss of height of the bone in the thoracic and lumbar spine. This may occur in a single bone or in multiple bones throughout the spine. The loss of disc height associated with these fractures may decrease the normal lordosis of the lumbar spine, resulting in flat back syndrome [Figure 6].
Ankylosing spondylitis is a chronic inflammatory disease that causes stiffness and arthritis throughout the entire spine. Some patients with ankylosing spondylitis will notice an increasing forward posture of the spine, including an increase in the thoracic kyphosis or decrease in lumbar lordosis leading to symptoms of lumbar flat back syndrome.
The diagnosis of lumbar flat back syndrome is made based on the patient's history and x-rays of the spine. The patient typically has difficulty standing upright and may complain of pain in the back or legs. Previous surgical history is important, including the specific details of any procedures performed. It is important to determine if the flat back syndrome is the result of a stable spinal structural abnormality or spinal instability. It is also important to determine if there is continued pressure on the nerves where spinal stenosis is present.
Many patients with lumbar flat back syndrome may be treated without surgery. Initial treatment typically includes an appropriate exercise routine to include aerobic fitness, weight bearing exercise, and core muscle strengthening. Physical therapy and spinal manipulation may also be beneficial depending on the patient's symptoms. Medications are commonly used to manage the symptoms of lumbar flat back syndrome. For many patients conditioning and endurance programs may provide enough strength that the symptoms are improved. For patients with joint arthritis or pinched nerves, spinal injections can also help to provide relief.
Some patients with structural problems or severe curvature may ultimately require surgical reconstruction. The goal of lumbar flat back syndrome surgery is to improve the patient's pain and improve their spinal alignment. The team of experts at the Virginia Spine Institute work to restore a more normal alignment of the spine to decrease the stress on the supporting muscles of the back, hips, and legs.
Surgery to correct flat back syndrome may be an option for the patient if the nonsurgical treatments do not relieve their symptoms. Surgery may also be needed for patients whose deformity is getting worse over time, or who have curvatures that are leading to nerve compression and are causing symptoms such as numbness, weakness, or pain. Surgical reconstruction for flat back syndrome involves some correction of the curvature. The goals of the surgery are to relieve pain and to prevent the curvature from getting worse in the future [Figures 7, 8, 9].
Figures 7,8,9: This patient is a 64-yea- old female who had lumbar fusion surgery in the past. She did well for years, but then she began leaning forward and to her left side. She developed severe pain that kept her from walking and even standing. Her x-rays revealed flat back deformity with a loss of normal lumbar lordosis and also a new scoliosis. She underwent spinal reconstruction surgery with Dr. Good. During her surgery, a portion of bone was removed (osteotomy) to allow for realignment of her spine and the spine was held in the new alignment using pedicle screw implants. Her X-rays and clinical photographs show excellent correction of her flat back deformity and she has returned to normal activity including working at a greenhouse.
Surgery to correct flat back deformity may be performed from the back of the spine (posterior approach) or the front or side of the spine (anterior or lateral approach) or some combination of anterior and posterior surgery together. The surgical approach utilized depends on the type of curvature that is present, the patient's symptoms, and what type of surgery the patient may have had previously. Before deciding on the approach for surgery, the doctors at VSI review the patient's x-rays, imaging tests, and clinical examination multiple times to formulate the surgical plan. The final recommendation for each patient is based on the desire to formulate the least invasive and safest procedure for each patient.
Adult flat back correction surgery utilizes spinal implants (rods and screws) to hold the spine stable in that position while the spine fuses or mends. When the spine fuses, those segments of the spine heal together and are no longer mobile. Spine fusion is achieved using bone graft taken from the patient's spine intra-operatively in the area of surgery and for some patients bone morphogenetic protein is utilized to increase the chance that the spine will fuse correctly.
The expert team at the Virginia Spine Institute do NOT routinely take bone graft from the patient's hip or iliac crest. Iliac crest bone graft is used by many surgeons to achieve spine fusion, however, this increases the patient's pain and lengthens recovery time. The physicians at the Virginia Spine Institute are proud to have worked to pioneer the use of bone morphogenetic protein, a genetically engineered substance that improves the success of spinal fusion and avoids the pain of hip graft harvest for the patient. The physicians at the Vrginia Spine Institute have a long-standing track record using bone morphogenetic protein in a safe and effective manner.
Correction of lumbar flat back syndrome may also involve a spinal osteotomy. An osteotomy is a procedure in which the surgeon cuts into a bone, usually taking out a wedge of bone in order to allow for correction in spinal alignment. There are a number of different types of osteotomy. The specific osteotomy used in any surgery case depends on the location of the spinal deformity to be corrected as well as the amount of correction that is needed. Spinal osteotomies are used as part of a spinal reconstructive procedure in order to achieve spinal balance and stability.
Smith-Peterson osteotomy, or SPO, (posterior column osteotomy) [Figure 10] is a procedure where a portion of the bone in the back portion of the spine may be removed. When this bone is removed it creates a space and when this space is closed down it allows the bones in the back of the spine to come closer together, therefore "leaning" the spine more toward the back. Smith-Peterson osteotomy may be performed at one location or multiple locations along the spine to allow the surgeon to restore lordosis in the area of the osteotomy. SPO refers to an osteotomy where the posterior ligament and facet joints are removed to allow for correction through this area. This procedure requires motion through the mobile anterior portion of the spine or the discs for correction.
Figure 10: Smith-Peterson Osteotomy (posterior column osteotomy)
A pedicle subtraction osteotomy (PSO) [Figure 11] is also known as a transpedicular wedge osteotomy. A PSO is performed by removing the posterior element and facet joints similar to a Smith-Peterson osteotomy. The PSO then involves removing the remaining posterior elements and pedicles of the vertebral body, and then working around the nerves of the spine into the front portion of the spine and a portion of the vertebral body is removed, usually in a wedge [Figure 12]. This osteotomy involves all three columns of the spine (posterior, middle, and anterior). During a posterior subtraction osteotomy (PSO) resection of more bone is performed than during a single Smith-Peterson osteotomy. Therefore, the correction of the lordosis with this osteotomy is greater.
Figure 11: A pedicle subtraction osteotomy (PSO) also known as a transpedicular wedge osteotomy.
Vertebral column resection (VCR) [Figure 13] allows the largest correction of any spinal osteotomy. During the vertebral column resection, one entire segment of the spine is removed. This procedure was initially described through an anterior and posterior combined approach. More recently the VCR has been performed through a posterior only approach and is shown to be safe and effective for many patients [Figure 14].
Figure 13: Vertebral column resection (VCR)
Figure 14: An x-ray taken from the side (lateral view) of a patient who has undergone a thoracic VCR. The spine is supported in the front by a cage which restored the height of the spine, and pedicle screws and rods in the back. Spinal fusion is performed over these levels.
Spinal deformity correction surgery with osteotomy is an option for the patient if the nonsurgical treatments do not relieve their pain or symptoms. Surgery is also needed for patients whose deformity is getting worse over time or who have curvatures that are leading to nerve compression causing symptoms such as numbness, weakness, or pain. Surgical reconstruction involves some correction of the curvature, with the goal of the surgery being to relieve pain and to prevent the curvature from getting worse in the future.
Determining if an osteotomy is needed and which type is most appropriate for any given patient depends on multiple factors, as well as the location of the spinal deformity to be corrected. The surgeons at Virginia Spine Institute will perform x-rays to determine the magnitude of the spinal deformity as well as the flexibility of the spine to determine the extent of the correction that may be necessary. Once the spinal deformity reconstruction surgery is indicated, careful preoperative assessment of the curve is needed to help determine the optimal spinal alignment of the spine after surgery.
Spinal deformity surgery with vertebral osteotomy is a challenging but safe procedure and can be performed with a relatively low complication rate; however, complication rates are higher with more complicated surgeries. Published studies have shown good results following spinal osteotomy surgery. The decision to perform surgery to correct spinal deformity with an osteotomy should be made carefully and after a thorough discussion with your spinal specialist.