Cloward, R. B. (1953). The treatment of ruptured lumbar intervertebral discs by vertebral body fusion. I. Indications, operative technique, after care. J Neurosurg, 10(2), 154–168.
Ralph Cloward is credited for the technical innovation of posterior lumbar interbody fusion, or PLIF.
Following the report by Mixter and Barr in 1934, discectomy became a standard operation for sciatica due to a ruptured intervertebral disc. Ralph Cloward's philosophy went against the prevailing treatment for lumbar disc herniation — he believed discectomy alone did not address low back pain, and that removal of the nucleus pulposus led to instability of the motion segment that caused back pain. In 1944, he audited his patients operated on for a ruptured disc with discectomy alone: of 162 patients, 70% had symptoms related to the surgery (back pain or recurrence of sciatica), and 20% subsequently required a fusion surgery. He initially tried a posterior fusion as described by Hibbs, but was unsatisfied with the results due to pseudarthrosis.
Cloward performed the first PLIF in 1943:
"The operation of vertebral body fusion devised by the writer consists of a subtotal removal of the intervertebral disc, including the cartilaginous plates, through a partial bilateral laminectomy. The cortical surfaces of the vertebral bodies are removed with a chisel and three or more large full-thickness bone grafts obtained from the iliac crest are driven forcibly into the interspace."
Cloward applied his fusion technique to all ruptured discs. The only way to diagnose a ruptured disc in 1943 was a myelogram. His rationale:
"It is true that many patients apparently remain asymptomatic for a long time following a simple disc removal. But others with exactly the same clinical picture may continue to have incapacitating low-back pain and/or develop a recurrence of the sciatica within a short time after the operation. Because of this difficulty in determining which operation a given individual may require, I have made my treatment uniform for every patient... a vertebral body fusion has been done in practically every case of ruptured lumbar disc operated upon since 1944."
Today we may disagree with his indications for PLIF, as we have become more selective. Cloward also maintained that compensation-claim patients did better with PLIF than discectomy:
"The most gratifying group of patients treated by this operation has been that of the industrial accident and insurance cases... My experience with the vertebral body fusion in compensation cases has been much more gratifying."
Cloward's claims made him controversial, and he met significant resistance throughout his career. When he presented his first 100 cases at the Harvey Cushing Society Meeting reporting a 94% success rate, the paper was received with disbelief. James Watts, a neurosurgeon from Virginia, commented: "We are neurosurgeons, and as such we should restrict our activities to the trephine and the rongeur, and leave the hammer and the chisel to the orthopaedic surgeons."
Later, as evidence accumulated, surgeons realized the benefits of this operation, and it remains popular to this day. Dr. Paul Lin wrote: "Dr. Cloward was so far ahead of his time in technical skill that he made others appear inferior."
The PLIF was a revolutionary technical innovation that changed the course of spine surgery.
The essential steps of Cloward's PLIF were:
- Removal of the interspinous ligament
- Insertion of a powerful interlaminar spreader at the base of the spinous processes
- Removal of the lower one-third of the inferior facet and the medial two-thirds of the superior facet, and undercutting of the upper lamina
- The nerve root and dural sac retracted to the midline, held, and protected by a self-retaining nerve-root retractor
- Posterior half of the disc cut out
- Cartilaginous plates stripped from adjacent bodies
- Subtotal discectomy
- A thin layer of the cortical endplate of adjacent vertebral bodies removed with straight and curved osteotomes down to the anterior longitudinal ligament under direct vision
- Three full-thickness iliac grafts fashioned to fit perfectly into the prepared disc space, ensuring maximum bone-to-bone contact. Initially autografts were used; by 1947, refrigerated cadaver bone was used when possible — making Cloward one of the first to use banked bone for fusion.
Dr. Ralph Cloward, MD (1908–2010)
- Born in Salt Lake City, Utah, USA
- Medical School: University of Utah and Rush Medical College (University of Chicago). Graduated 1934
- Internship: St. Luke's Hospital (1934–1935)
- Neurosurgery residency: Billings Memorial and University of Chicago Clinics, 1935–1938, under Prof. Percival Bailey
- Started practice in 1938; was Chief of Staff (Neurosurgery) at Queen's, St. Francis, and Kuakini Hospitals, Honolulu, Hawaii, USA
Contributions to Spine Surgery
- PLIF (posterior lumbar interbody fusion): First performed in 1943, reported in 1945 to the Hawaii Territorial Medical Association. (Cloward, R. B. (1953). J Neurosurg, 10(2), 154–168.)
- ACDF (anterior cervical discectomy and fusion): Developed the technique also known as the Cloward procedure. (Cloward, R. B. (1958). J Neurosurg, 15(6), 602–617.)
- Designed over 100 surgical instruments.