Lumbar Spinal Stenosis (LSS) is a condition involving any type of narrowing of the spinal canal or nerve root canals. The most common form of LSS is degenerative stenosis, which occurs as a result of the natural process of ageing. Stenosis patients usually present with pain, numbness and tingling in their lower extremities. These symptoms are relieved in flexion or sitting and are exacerbated in extension.
As the disease progresses, a patient's quality of life becomes increasingly compromised. Patients develop chronic low back pain and weakness in the legs which limit walking to a brief duration and short distance, restricting their ability to carry out the basic activities of daily life.
CURRENT TREATMENT OPTIONS
Once the diagnosis of LSS has been confirmed, treatment begins with a regimen of non-operative care, consisting of conservative therapy and epidural steroid injections. Non-operative modalities represent the standard of care for patients with mild to moderate symptoms of LSS.
Decompressive surgery is the next therapeutic option and may be considered for patients with more severe symptoms or those patients who are dissatisfied with the outcome of non-operative therapies. Decompressive surgery is absolutely indicated in patients at risk of irreversible neurological damage from canal compromise. However, this represents a very small percentage of LSS patients.
Conservative treatment typically consists of bed rest and controlled physical activity, physiotherapy, anti-inflammatory drugs, heat packs, ice packs and massage. Bed rest for short periods of time, interspersed with light activity, is often advised. The rationale for decreasing physical activity is to allow any inflammation to subside, sometimes resulting in temporary relief from symptoms.
Exercises that encourage lumbar flexion can be beneficial. Non-Steroidal Anti-Inflammatory medications (NSAIDs) are often recommended to reduce inflammation, thereby reducing pain.
Epidural steroid injections: have been reported to be
helpful in pain relief. The local anti-inflammatory effect of epidural injections is increasingly accepted as the probable mechanism of pain relief in patients suffering from LSS.
Decompressive laminectomy: lumbar laminectomy is the surgical procedure most commonly performed to treat LSS. The laminae and ligamentum flavum at the affected levels are removed, relieving the pressure on the nerve roots. The neuroforamina may also be enlarged.
Outcomes for non-operative therapy are typically reported as the proportion of patients whose symptoms are worse, stable or improved. Patients whose symptoms are either stable or improved are generally considered treatment successes.
Approximately 30%–45% of patients treated with non-operative therapy experience some improvement in either pain relief or physical function. The proportion of patients who elect to undergo a laminectomy after failure to achieve satisfactory relief of symptoms from non-operative therapy ranges from 18%–29.5%, depending on the length of follow-up.
Results of surgical decompression for LSS vary widely. Turner's metaanalysis of the surgical literature reported good to excellent results ranging from 26 to 100%. Amundsen reported improvement of symptoms in 63% in a prospective study. However, progressive deterioration over time has been reported, with many patients undergoing repeat surgery.
As an adjunct to decompressive laminectomy, spinal fusion appears to be increasing in frequency to mitigate the effects of spinal instability, when present. Spinal fusion, however, is associated with an increased incidence of morbidity and complications.
While aspirin and other nonsteroidal agents have been associated with acute gastrointestinal bleeding, nonoperative therapy represents minimal risk to a patient. The major risks of epidural steroid injections are related to the technical and procedural aspects of the treatment.
The reported complications from decompressive laminectomy include death, pain, infection, dural tears, bleeding, neurological deficit, reoperations and functional disability. The incidence of morbidity and mortality from surgery increases with the presence of co-morbid conditions, which are frequently present in elderly patients at risk for LSS.
Patients with mild to moderate symptoms from LSS thus have two treatment options:
- They may continue with non-operative treatment - approximately 30%–45% of patients may expect to experience at least some improvement in either pain or function
- They may elect to undergo a laminectomy - approximately 60% of patients electing to proceed with surgery may expect to experience some improvement in symptoms - the risks of the surgery, however, are significant
X STOP SOLUTION
The X STOP was developed to treat patients suffering from mild to moderate symptoms of LSS as an alternative to non-operative therapy. Made from titanium alloy, the X STOP is placed between the spinous processes of the symptomatic disc levels. The principle behind the X STOP is that, by preventing full extension at the affected spinal segment, the symptoms of lumbar spinal stenosis are relieved.
The design of the X STOP allows it to be easily and quickly implanted, yet ensures it will remain in place without fixation to bones or ligaments. The advantages of the X STOP procedure over decompressive laminectomy are significant.
The minimally invasive procedure can be performed under local anaesthesia in around 50 minutes. As there is no extensive surgery or general anaesthesia involved, most patients return home the same day as surgery and they recover in a matter of weeks.
Following a ten-patient pilot study, an investigational device exemption for the X STOP was granted and a randomised, controlled, multi-centre pivotal clinical trial was initiated in June 2000. A total of 191 patients were treated. A total of 100 received the X STOP, and 91 received an epidural steroid injection as part of a regimen of non-operative therapy.
The primary outcomes measure chosen for the trial was the Zurich Claudication Questionnaire (ZCQ). There were no significant differences in the preoperative demographics or baseline symptom severity and physical function between the two patient groups.
Results of the pivotal clinical trial confirm the safety of the X STOP. The implant resulted in a low percentage of complications, which resolved without significant clinical sequelae, and no neurological injuries occurred in the study.
The efficacy of the X STOP was demonstrated by outcomes at the 24-month follow-up. A significantly greater proportion of X STOP patients achieved clinically significant improvement in symptom severity and physical function compared with control patients.
A significantly greater proportion of X STOP patients were also satisfied with their treatment compared with control patients. Mean improvement scores, calculated as mean change scores over baseline as a percentage of the complete outcomes scale, confirm the magnitude of the effect of the X STOP treatment.
At the 24-month follow-up:
- 60.2 % of X STOP patients achieved clinically significant improvement in symptoms compared with 18.5% of patients in the control group. Mean improvement was 24.8% for X STOP patients, compared with 4.3% for control patients.
- 57% of X STOP patients achieved clinically significant improvement in physical function compared with 14.8% in the control group. The mean improvement in function was 19.0% for X STOP patients, compared with 2.0% for control patients.
- 73.1% of X STOP patients were satisfied with their treatment, compared with 35.9% of control patients.
When patients were required to meet all success criteria as defined in the study protocol, 45.7% of X STOP patients were treatment successes, compared with 4.9% of control patients. X STOP outcomes are comparable to results for laminectomy surgery.
The procedure to implant the X STOP is minimally invasive and can be performed under local anaesthesia in less than an hour. Patients can return home the same day as surgery. Patients in whom general anaesthesia is contraindicated may particularly benefit from X STOP treatment.
Considering the continuum of treatment options available to generally older LSS patients, who frequently suffer from significant co-morbid conditions, the X STOP offers an attractive alternative after non-operative therapy and epidural injections are no longer effective. The X STOP provides a conservative, safe and effective treatment option for patients with mild to moderate symptoms of lumbar spinal stenosis.