Calling All Harrington Rod, Spinal Fusion People
Do you have a harrington rod? There were thousands of us in the ’80′s getting these things in hospitals. An event, actually, that I’ve never really fully processed (although I hope I’ve accepted it?). At the time (I was 14), my mother sought the opinions of three New York City surgeons, and they all said the same thing: only surgery will stop the progression of this scoliosis.
28 years later, I am revisiting this steel rod situation. Studies prove that metals, even those touted as inert, corrode inside the body.
Corrosion of spinal implants retrieved from patients with scoliosis
Spinal implants retrieved from 11 patients with scoliosis were examined. All the implants were posterior instrumentation systems made of 316L stainless steel and composed of rods, hooks, and crosslink connectors. Corrosion was classified into grades 0 to 3 based on macroscopic findings of the rod surface at the junction of each hook or crosslink connector. Grade 0 was defined as no sign of corrosion, grade 1 as surface discoloration, grade 2 as superficial metal loss, and grade 3 as severe metal loss. The depths and characteristics of metal loss areas were examined. Spinal implants showed more corrosion after long-term implantation than after short-term implantation. Corrosion was seen on many of the rod junctions (66.2%) after long-term implantation, but there was no difference between the junction at the hook and those at the crosslink connector. It is thought that intergranular corrosion and fretting contributed to the corrosion of implants. The current study demonstrated that corrosion takes place at many of the rod junctions in long-term implantation. We recommend removal of the spinal implants after solid bony union.
Here’s a study that looked at chromium levels in blood and urine. If you’re wondering how they know whether corrosion took place, it’s almost always from ‘retrieved instrumentation.’ Those with metal implants had higher chromium levels. And “corrosion significantly raised metal levels, including nickel and chromium in serum and urine when compared to patients with no radiological signs of corrosion and to volunteers without metallic implants”.
Metal levels in corrosion of spinal implants
Corrosion affects spinal instrumentations and may cause local and systemic complications. Diagnosis of corrosion is difficult, and nowadays it is performed almost exclusively by the examination of retrieved instrumentations. We conducted this study to determine whether it is possible to detect corrosion by measuring metal levels on patients with posterior instrumented spinal fusion. Eleven asymptomatic patients, with radiological signs of corrosion of their stainless steel spinal instrumentations, were studied by performing determinations of nickel and chromium in serum and urine. Those levels were compared with the levels of 22 patients with the same kind of instrumentation but without evidence of corrosion and to a control group of 22 volunteers without any metallic implants. Statistical analysis of our results revealed that the patients with spinal implants without radiological signs of corrosion have increased levels of chromium in serum and urine (P < 0.001) compared to volunteers without implants. Corrosion significantly raised metal levels, including nickel and chromium in serum and urine when compared to patients with no radiological signs of corrosion and to volunteers without metallic implants (P < 0.001). Metal levels measured in serum have high sensibility and specificity (area under the ROC curve of 0.981). By combining the levels of nickel and chromium in serum we were able to identify all the cases of corrosion in our series of patients. The results of our study confirm that metal levels in serum and urine are useful in the diagnosis of corrosion of spinal implants and may be helpful in defining the role of corrosion in recently described clinical entities such as late operative site pain or late infection of spinal implants.
I am writing this post to see if any readers can share their experience, or maybe answer these questions. How long have you had a spinal fusion/rod? Do you have any health issues (possibly mysterious)? Have you had any metal allergy blood tests done? Have you ever considered looking into rod removal?