The DIAM (Device for Intervertebral Assisted Motion) Spinal Stabilization of Minnesota before he gave up his studies to focus on Medtronic. An FDA advisory panel last week reportedly recommended against approval for the DIAM spinal stabilization system made by Medtronic. The FDA’s orthopedic and rehabilitation devices advisory panel unanimously recommended rejection of Medtronic’s Diam spinal stabilization.
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FDA advisory panel votes against recommending approval of Medtronic spine implant | FierceBiotech
Editor who approved publication: Internal disk disruption IDDan early event of lumbar disk degeneration, is the most common cause of low back pain. Since increased intradiskal pressure IDP is associated with symptoms and progression of disk degeneration, unloading a painful disk with an interspinous process device IPD is a rational treatment option.
The goal of this study was to evaluate the effectiveness of dynamic stabilization with an IPD in the treatment of symptomatic IDD of the lumbar spine. Diagnosis of IDD was based on typical MRI finding of posterior annular high-intensity zone and positive provocative test on discography.
IDP was analyzed intraoperatively. Axial back and leg pain was evaluated with visual analog scale, functional status with Oswestry Disability Index, and final clinical outcomes with Odom criteria. All 34 patients reported symptom relief.
Mddtronic status at the DIAM-implanted segments remained stable. No proximal or distal adjacent segment degeneration was observed. Internal disk disruption IDD has been found to be the most prevalent cause of chronic low back pain LBPsurpassing facet joint and sacroiliac joint pain.
IDD is regarded medtronlc an early event of disk degeneration. Because mechanical strains and elevated intradiskal pressure IDP have been shown to be closely associated with the progression of lumbar disk degeneration, 10 — 12 unloading a painful disk in its early stage of degeneration would theoretically medtonic pain and even stop or slow down the degenerative process.
A recent development in the surgical treatment of lumbar degenerative diseases is the application of interspinous process devices IPDs. Twenty-six patients had also received one or more diqm of injection or radiofrequency therapy. The treated sites were sacroiliac joints in 17, disks in eight, facet joints in five, and unknown in three patients. All patients felt that their mertronic of life was significantly affected by the symptoms, and they actively sought for more aggressive measures.
None of them had history of malignancy, psychiatric disorders, or previous spinal trauma, infection, or surgery. Corresponding neurologic deficits were detected in 13 cases, manifested as motor weakness with or without sensory impairment. None of the patients had intermittent claudication typical of lumbar spinal stenosis or symptoms and physical findings suggestive of hip joint or sacroiliac joint arthropathy.
The diagnosis of IDD was based on imaging studies and provocative discography. Excluding five patients who refused discography and nine who showed negative discographic findings or reported no concordant pain on provocative tests, a total of 34 patients 14 men and 20 women with a mean age of 38 years range 24—51 were included in this retrospective study Table 1. Images were analyzed by the operating surgeon and by an independent neuroradiology specialist.
MR findings of dark signal with a high-intensity zone in the posterior annulus were regarded as diagnostic of IDD. Excluded were patients who showed image findings of disk extrusion or sequestered herniation, advanced disk degeneration with Modic changes, disk space collapse Pfirrmann grades IV or Vdefects of pars interarticularis, spondylolisthesis, lumbar stenosis, or disease at the L5-S1 level.
Direct decompression with or without fusion was our option of choice for such patients. All operations were performed by the same surgeon KL. After midline skin incision, the paraspinal muscles were dissected and retracted to expose the target rostral and caudal spinous processes and laminae.
The interspinous and the interlaminar ligaments were removed, while the supraspinous ligament was preserved. Epidural fat, if present, was kept as intact as possible. The DIAM implant was placed between the two spinous processes and laminae under the supraspinous ligament.
The implant was firmly anchored in place by the two tethers passed around the two adjacent spinous processes, and fixed with crimps. Written informed consent was obtained from patients to participate in the study. After removing the interlaminar ligament, a limited laminotomy was performed under an operating microscope to expose the nerve root.
The nerve root was gently retracted medially. The tip of the microsensor was inserted through the annulus into the center of the disk. A baseline resting IDP reading was obtained first, and then subsequently at three different time points, including distracting between the spinous processes and laminae with a distractor, inserting trial templates, and after DIAM implantation Figure 1.
The sensor was removed before wound closure. Figure 1 Intraoperative IDP recording using a microsensor for intracranial pressure monitoring. The monitoring was done at a resting state Aon distraction between the two spinous processes with a distractor Ba template Cand after DIAM implantation D.
Final clinical outcomes were evaluated with the Odom criteria. Radiographs were obtained at each follow-up to evaluate the implant position, status of the disk, segmental mobility at the DIAM-implanted level, and the proximal and distal adjacent disk levels. IDP monitoring was successfully done in eleven patients and abandoned in three patients.
The reasons for aborting pressure monitoring included failure to pass the sensor through the annulus and mechanical problems of the sensors or monitors. The mean resting pressure before any interspinous distraction was Distraction between spinous processes with the distractor caused an abrupt drop of pressure mean The pressure rebounded on replacing the distractor with a template mean 0.
The mean final pressure after securing the DIAM implant was As the pattern of intraoperative IDP changes was so distinctive and constant, pressure monitoring was not performed in the rest of the cases.
The pain was dull and persistent. Soreness was felt on her buttocks and posterior thighs. The pain did not radiate to lower legs. There was no numbness on the legs. Her tolerance to upright positions, including standing and sitting, was poor. Her ability to walk was normal. Her VAS was 6—8, depending on the time of day. Her ODI was She showed normal posture and gait pattern. Neurological examination disclosed no motor or sensory deficits.
Both sessions gave her temporary pain relief, but symptoms soon recurred. Radiographs showed that she had a sixth lumbar vertebra, and that there was a loss of L disk height Figure 3A—C. She reported relief of the LBP and leg pain immediately after surgery. She remained symptom-free at the 3-year follow-up. Preoperative radiographs showed presence of a sixth lumbar vertebral and loss of L disk height A—C.
MRI showed a dark disk with a posterior high-intensity zone D, E. All 34 patients reported improvement of pain and functional status at the first follow-up 1 week after surgery. The back pain in the first case, a year-old man who underwent L, L DIAM implantations, started after a fall in a motor vehicle accident. It soon subsided with medical treatment. Imaging and electrophysiological studies did not show any abnormalities. Medications and physical therapy failed to relieve the pain.
Meanwhile, she had sleep disorder and menstrual irregularity and visited other specialists for narcotics frequently. The cause of her pain was suspected as psychiatric. A consultation with a psychiatrist was proposed, but refused by the patient.
Interspinous implants: are the new implants better than the last generation? A review
This was the only case who reported poor clinical outcome. Axial sections through the L disk B, E showed widened bilateral neuroforamens for exiting nerve roots. At the DIAM-implanted segments, follow-up radiographs showed no progression of disk height loss, endplate changes, appearance of vacuum clefts, or segmental instability.
At the final follow-up, this was preserved in 27 cases, but restricted in two, and lost in one case. There was no radiographic evidence of degeneration at any proximal or distal adjacent segments next to the DIAM-implanted segments. Repeated MRI was obtained in the three aforementioned cases experiencing recurrent pain. Consistently, all the MR images showed increased neuroforaminal widths and resolution of annular fissures at the DIAM-implanted segments Figure 5.
No fracture of spinous processes or dural tear occurred during the surgical procedures. No patient developed neurologic deficit after surgery. Superficial wound infection occurred in one patient, which subsided with proper wound care. All patients were ambulatory in a lumbar corset on the day of surgery or the next day. Different from more advanced lumbar disk degeneration, IDD lacks obvious image findings to justify any aggressive treatment.
Even if a patient suffers from severe symptoms, many would not view them as candidates for surgery. However, IDD may cause chronic disabling symptoms, and may progress to more advanced degeneration. We excluded patients with advanced disk degeneration Pfirrmann grades IV and Vovert lumbar stenosis, spondylolisthesis, and instability. The rationale was the belief that the DIAM implant provides axial distraction but does not relieve anteroposterior or circumferential compression from hypertrophic ligamentum flavum and facet joints present in advanced disk degeneration and lumbar stenosis.
Moreover, such cases often have associated disk space collapse and ankylosis of the facet joints, which would significantly limit the applicability of the DIAM implant and its mobility after implantation. It is arguable whether an intervertebral disk in its early stage of degeneration should not be treated surgically at all. One of the major findings of this study is that in IDD, the symptoms can be severe enough to affect quality of life badly, even though the disk may appear only mildly degenerated.
In addition, there is the risk of progressive degeneration and dysfunction of the disk and facet joints over time to a state where dynamic stabilization with a DIAM implant would no longer be optimal, and fusion might become the only choice. The patterns of IDP changes were strikingly similar among the measured cases.