by Martin Booe
Ossification of the posterior longitudinal ligament (OPLL) is a spinal condition generally regarded as affecting Asians, particularly Asian men. But John C. Liu, MD, professor of clinical neurological surgery at the Keck School of Medicine of USC, cautions diagnosing physicians against ruling it out too hastily in other populations.
“OPLL is fairly common in Asians, particularly among Japanese and Koreans,” says Liu, who is also the Co-Director of the USC Spine Center at Keck Medicine of USC. “However, we do see it in a certain percentage of Caucasians and African- Americans. OPLL really does cut across all the different races.”
When OPLL occurs, the ligament that runs almost the length of the spine thickens and loses flexibility. In cases where the symptoms are mild and otherwise stable, OPLL can be treated non-surgically with medications and physical therapy. However, surgery may be appropriate when there are signs and symptoms of spinal cord pressure.
It’s not uncommon for someone with OPLL to be free of symptoms, says Liu. However, because the ligament is situated directly in front of the spinal cord, calcification can lead to spinal cord or nerve root compression. Common symptoms such as arm and neck pain can be debilitating but spinal cord compression raises a much more serious concern because it can impair a patient’s ability to walk. “This is potentially a very big problem so being able to recognize OPLL is very important,” he says. “OPLL is progressive, so the earlier the diagnosis, the better.”
A related and somewhat more common disorder is known as diffuse idiopathic skeletal hyperostosis (DISH). DISH, which involves ossification of the anterior longitudinal ligament, is uncommon in Asians, but relatively common in Caucasians, manifesting in 15 to 30 percent in patients 65 or older. OPLL, DISH and several other diseases that involve abnormal ossification or abnormal fusing of ligaments or joints are regarded and treated as diseases on the rheumatic spectrum.
The goal of surgery is to make more room for the spinal cord and nerve roots, a technique that is patient specific. “It can be approached from a number of different angles and the ligament can be approached posteriorly or anteriorly,” says Liu. “Sometimes this involves removing some of the ligament’s ossification, which can be rather delicate. There can be some potential complications from doing that. So proper assessment and looking at a range of options appropriate for each individual is very important.”
Unfortunately, surgery for OPLL and similar problems involving ligament ossification are fairly invasive procedures, because room for the spinal cord has to be literally carved out. How much of the ossification should be removed is a common debate among surgeons, based on the risk/benefit ratio for the patient.
“There’s not a single operation that suits every case,” Liu says. “We really have to work at tailoring the operation to each patient’s particular needs.” Some operations may involve actually removing the ossified part of the ligament while others may hollow out more room for it.
There’s also a judgement call as to how far to go surgically. “Sometimes, you may want to just stop and fix the main area that's causing the patient's problem,” Liu explains. “This is where I think it’s important for surgeons and those looking at the images to have a fair amount of specific experience.”
Recovery time is quite variable, with hospital stays ranging from overnight to several days. Not surprisingly, much depends on the extent of the ossification. Those with associated neurological problems are, as one might expect, higher risk.
An important factor in the success of OPLL surgeries at Keck Medicine of USC is the multidisciplinary approach to spine treatment. All of Keck Medicine’s spine surgery specialists hold appointments and academic titles in both neurosurgery and orthopaedic surgery.
“What we're trying to form is a collaborative approach to treating patients with OPLL. Our success is based on our surgeons’ expertise in early diagnosis and treatment.” Liu continues, “A lot of the calls with OPLL are subjective, so taking a multi-disciplinary approach when we see an abnormal inflammation in the spine helps us improve our accuracy. Early diagnosis may allow us to work with our rheumatologic colleagues to treat this non-surgically in the future.”