Ralph B. Cloward

Ralph Bingham Cloward, MD (September 24, 1908 – November 13, 2000) was an influential figure in the history of orthopaedic and neurological spine surgery, revered for pioneering Anterior Cervical Discectomy and Fusion (ACDF / The Cloward Procedure), inventing Posterior Lumbar Interbody Fusion (PLIF), establishing one of the earliest refrigerated surgical bone banks, and developing more than one hundred specialized spinal surgical instruments that defined the modern era of operative spine reconstruction.

1. The Shoulders of Giants: Historical Context & Significance

Throughout the first half of the twentieth century, operative intervention for spinal disorders was severely constrained by a dogmatic adherence to posterior surgical corridors. When patients presented with progressive cervical myelopathy, intractable radiculopathy, or incapacitating lumbar disc herniations, surgeons routinely performed extensive posterior decompressive laminectomies. In the cervical spine, however, the primary pathology (herniated disc material, calcified posterior longitudinal ligaments, and hypertrophic spondylotic osteophytes) invariably arose from the ventral aspect of the spinal canal. Reaching these anterior compressive masses from a posterior approach required surgeons to forcibly mobilize and retract the delicate cervical spinal cord and swollen nerve roots. This hazardous posterior manipulation carried a terrifying complication profile, frequently transforming an incomplete motor radiculopathy into irreversible quadriplegia or central cord syndrome.

“If I have seen further, it is by standing on the shoulders of giants.”

Sir Isaac Newton (1675) / Bernard of Chartres

Concurrently, in the lumbar spine, standard posterior discectomy without arthrodesis left an empty, collapsed intervertebral disc space. Deprived of anterior structural support, the operated segment succumbed to progressive disc space narrowing, secondary neuroforaminal stenosis, painful facet joint subluxation, and chronic mechanical instability. Ralph Bingham Cloward possessed the bold biomechanical vision and technical genius to overturn these foundational limitations. He recognized that anterior neural compression demanded direct anterior decompression, eliminating cord retraction entirely, and that durable spinal stability required restoration of the anterior load-bearing column through interbody bone grafting.

Modern spine surgeons stand directly upon the monumental achievements of Ralph Bingham Cloward. By conceiving Posterior Lumbar Interbody Fusion (PLIF) in the 1940s and pioneering Anterior Cervical Discectomy and Fusion (ACDF, universally remembered as the Cloward Procedure) in 1957, Cloward transformed spine surgery into a restorative discipline. His circular dowel grafting technique, calibrated vertebral drill system, and precision self-retaining retractors established the fundamental operative principles that govern modern spinal reconstruction. Today, anterior cervical discectomy and fusion remains the gold-standard operative benchmark across the globe, performed hundreds of thousands of times annually with exceptional safety and clinical success.

2. Early Life, Formative Education & Career Milestones

Education and Formative Surgical Training

Ralph Bingham Cloward was born on September 24, 1908, in Salt Lake City, Utah. Raised in the Intermountain West, Cloward developed early mechanical dexterity, craftsmanship, and an enduring fascination with biological structures and physical tools. He pursued his undergraduate studies at the University of Utah before traveling east to Chicago to enroll at Rush Medical College. At Rush, Cloward distinguished himself through rigorous scholastic discipline and clinical acuity, earning his Doctor of Medicine (MD) degree in 1934 during an era marked by transformative advances in surgical pathology and antisepsis.

Following graduation, Cloward completed postgraduate training and entered formal neurosurgical residency at the University of Chicago Clinics and Billings Hospital. During these formative years, Cloward trained under the direct mentorship of two intellectual titans of twentieth-century neurological surgery: Percival Bailey and Paul C. Bucy. Bailey, who had collaborated intimately with Harvey Cushing at Peter Bent Brigham Hospital to create the definitive histopathological classification of intracranial gliomas, instilled in Cloward an uncompromising respect for microanatomical tissue architecture. Bucy, internationally celebrated for his work on the motor cortex and the primate Kluver-Bucy syndrome, emphasized meticulous physiological observation and aggressive surgical craftsmanship. This dual exposure to foundational neuropathology and bold operative innovation provided the ideal crucible for Cloward’s inventive mindset.

Academic Appointments and Clinical Leadership

In 1938, at thirty years of age, Cloward made the adventurous decision to relocate to the Territory of Hawaii. Arriving in Honolulu, he established his practice as the very first board-eligible and practicing neurosurgeon in the Hawaiian Islands. He secured staff appointments at The Queen’s Hospital (later The Queen’s Medical Center) and St. Francis Hospital, introducing advanced intracranial and spinal diagnostics to the territory.

On the morning of Sunday, December 7, 1941, the tranquil morning in Oahu was shattered by the surprise aerial bombardment of Pearl Harbor. As the sole civilian neurosurgeon in the Hawaiian Islands, Cloward was thrust into the center of a catastrophic mass-casualty crisis. Rushing immediately to Queen’s Hospital, Cloward operated without interruption for four consecutive days and nights. Confronting severe cranial blast injuries, open depressed skull fractures, and penetrating shrapnel wounds, Cloward performed definitive neurosurgical debridements and dural repairs on forty-two critically wounded casualties. His calm fortitude, rapid surgical triage, and inventive cranial reconstructive techniques saved dozens of lives and formed the basis for seminal wartime neurosurgical protocols.

In the post-war era, operating from Honolulu, Cloward pursued a prolific program of surgical innovation. To support his pioneering interbody fusions, he established one of the first refrigerated surgical bone banks in the United States at Queen’s Hospital in the late 1940s. In 1957, Cloward performed his first anterior cervical discectomy and dowel fusion, presenting the method to the Harvey Cushing Society in Washington, D.C., in 1958. Recognizing that his clinical innovations required dedicated educational forums, Cloward served as a founding member of both the Cervical Spine Research Society (CSRS) in 1973 and the International Society for the Study of the Lumbar Spine (ISSLS) in 1974. He traveled the world demonstrating his techniques across North America, Europe, Latin America, and Asia. Cloward maintained an active clinical and academic presence until his retirement, passing away peacefully in Honolulu on November 13, 2000, at the age of ninety-two.

3. Core Orthopaedic Breakthroughs, Eponymous Signs & Innovations

Ralph Bingham Cloward transformed the landscape of musculoskeletal medicine and spinal reconstruction through the invention of novel surgical approaches, biomechanical principles, and over one hundred purpose-built surgical instruments.

Hallmark Anatomical, Diagnostic and Operative Contributions

• Anterior Cervical Discectomy and Fusion (ACDF / The Cloward Procedure): Pioneered in 1957 and published in 1958, this revolutionary operative technique utilizes an anterior medial-retropharyngeal approach to access the cervical spine, directly resecting the herniated disc and osteophytes without spinal cord retraction, followed by circular interbody dowel bone grafting under distraction to restore lordosis and achieve solid arthrodesis.
• Posterior Lumbar Interbody Fusion (PLIF): Conceived in 1943 and published in 1953, PLIF established the concept of anterior column load reconstruction through a posterior laminectomy corridor, placing structural bicortical or tricortical autologous iliac crest grafts into the evacuated disc space to restore disc height, decompress neuroforamina, and achieve circumferential stability.
• The Cloward Surgical Instrumentation System: Invention of more than one hundred specialized spinal surgical tools, including the Cloward self-retaining cervical retractor (with interchangeable blunt and toothed blades), the calibrated vertebral body drill with adjustable guard, circular dowel hole cutters (trephines), vertebral spreaders, and curved bone graft impactors.
• Pioneering Refrigerated Surgical Bone Bank (1940s): Establishment of one of the earliest clinical bone banks in the United States at Queen’s Hospital in Honolulu, developing sterile preservation techniques for cortical and cancellous allografts to ensure structural graft availability for spinal arthrodesis.
• Cervical Discography & “Cloward’s Areas” of Referred Discogenic Pain: Development of provocative cervical discography in the mid-1950s, demonstrating that intradiscal injection into degenerate cervical discs reliably produces specific patterns of interscapular and periscapular referred muscle pain mediated by the sinuvertebral nerve, distinguishing discogenic pain from pure radiculopathy.
• Pearl Harbor Mass-Casualty Trauma Protocols and Spinal Extradural Cysts: Formulation of emergency neurotrauma debridement and cranial reconstruction doctrines during the December 7, 1941 Pearl Harbor attack, alongside landmark early publications characterizing congenital spinal extradural cysts causing progressive spastic paraplegia (Annals of Surgery, 1937).

To appreciate the magnitude of Cloward’s surgical breakthroughs, one must understand the biomechanical dilemma that confronted spine surgeons in the mid-twentieth century. Following the seminal work of Mixter and Barr in 1934, posterior discectomy rapidly became the standard treatment for ruptured intervertebral discs. However, simple discectomy frequently resulted in collapse of the intervertebral disc height, leading to secondary neuroforaminal narrowing, impingement of the exiting spinal nerve root, and painful retrolisthesis. In 1943, Cloward recognized that long-term clinical success required restoring the structural integrity of the anterior column, which normally sustains 80% of axial compressive loads according to Wolffe’s law. In his PLIF technique, Cloward radically cleared the disc space from a posterior corridor, prepared the bleeding subchondral bone, and impacted dense cancellous-cortical bone blocks directly between the vertebral bodies. His 1953 publication in the Journal of Neurosurgery detailed high fusion rates and symptomatic relief, laying the groundwork for modern interbody reconstruction.

In 1957, Cloward addressed the even more hazardous dilemma of the cervical spine. While George W. Smith and Robert A. Robinson at Johns Hopkins were developing an anterior cervical fusion using an open rectangular horseshoe graft, Cloward approached the problem with mechanical engineering precision. Cloward recognized that cylindrical drilling across the intervertebral disc space into adjacent endplates would allow complete, direct visualization and resection of the posterior longitudinal ligament, soft disc herniations, and hard uncovertebral osteophytes. He designed a specialized circular hole saw to harvest a matching cylindrical dowel graft from the patient’s iliac crest. When tapped into the distracted disc space, the circular graft’s cortical shell resisted axial collapse, while its extensive cancellous core contacted bleeding subchondral endplate bone, driving rapid osteointegration and segmental lordosis.

Executing Cloward’s anterior cervical approach demands intimate mastery of several treacherous neurovascular danger zones. The surgical corridor traverses the natural anatomical plane between the carotid sheath laterally (containing the common carotid artery, internal jugular vein, and vagus nerve) and the visceral sheath medially (housing the esophagus and trachea). Medial retractor migration can lacerate or create ischemic pressure necrosis of the esophagus, resulting in catastrophic deep neck space infection and fatal mediastinitis. Laterally, excessive pressure on the carotid sheath can compromise cerebral perfusion or induce vagal bradycardia. The recurrent laryngeal nerve, coursing within the tracheoesophageal groove, is exceptionally vulnerable to stretch injury from retractor blades, particularly if endotracheal tube cuff pressure is not deflated and reinflated after retractor placement. On the anterior surface of the longus colli muscles lies the sympathetic trunk; placing retractor teeth directly beneath the elevated longus colli protects the sympathetic chain from transection or stretch that would otherwise produce Horner’s syndrome (ptosis, miosis, and anhidrosis). Finally, during deep bone reaming, the lateral boundaries are defined by the uncinate processes; drilling lateral to the uncovertebral joint risks lacerating the vertebral artery, while plunging past the posterior cortical wall risks direct transection of the dura and cervical spinal cord.

4. Master Class Pro-Tip

Successful anterior cervical discectomy and dowel interbody fusion depends upon obsessive calibration of depth and disciplined endplate preparation. Prior to initiating drill reaming, thoroughly expose both medial borders of the longus colli muscles and establish absolute midline orientation by identifying the anterior prominence of the uncinate processes symmetrically. Place the self-retaining retractor blades strictly beneath the mobilized longus colli muscles; never allow blades to rest upon the esophagus or carotid sheath.

When applying the Cloward vertebral body drill, lock the adjustable guard to a starting depth of no more than 10 to 12 millimeters, verified against pre-operative lateral imaging. As the drill approaches the posterior cortex, remove the power tool and complete decompression manually using fine Kerrison rongeurs and micro-curettes. Never drill through the posterior longitudinal ligament. Resect all compressive uncovertebral osteophytes out to the uncinate borders to ensure uncompromised foraminal decompression. Prepare the endplate surfaces by removing only the cartilaginous layer; preserving the bleeding subchondral cortical bone plate prevents graft subsidence and collapse. During circular dowel insertion, apply gentle intervertebral distraction and verify that the graft diameter matches the reamed hole within 0.5 millimeters. Counter-sink the graft 1 to 2 millimeters recessed beneath the anterior vertebral cortical margin to eliminate any risk of anterior graft extrusion into the visceral space or retropulsion into the spinal canal.

Master Class Surgical Pearl: Cervical Endplate Preparation, Calibrated Depth Gauging, and Stable Dowel Graft Seating

5. Primary Landmark Publications & Bibliography

The foundational contributions of Ralph Bingham Cloward are preserved in these original landmark monographs and peer-reviewed surgical literature:

• Cloward RB. The Treatment of Ruptured Lumbar Intervertebral Discs by Vertebral Body Fusion. Journal of Neurosurgery. 1953;10(2):154–168. doi:10.3171/jns.1953.10.2.0154. [DOI]
• Cloward RB. The Anterior Approach for Removal of Ruptured Cervical Disks. Journal of Neurosurgery. 1958;15(6):602–617. doi:10.3171/jns.1958.15.6.0602. [DOI]
• Cloward RB. The Anterior Surgical Approach to the Cervical Spine: The Cloward Procedure: Past, Present, and Future. Spine. 1988;13(7):823–827. doi:10.1097/00007632-198807000-00020. [DOI]
• Cloward RB. Multiple Ruptured Lumber Discs. Annals of Surgery. 1955;142(2):190–208. doi:10.1097/00000658-195508000-00004. [DOI]
• Cloward RB. SPINAL EXTRADURAL CYSTS. Annals of Surgery. 1937;105(3):401–417. doi:10.1097/00000658-193703000-00011. [DOI]

6. Biographical Provenance & Acknowledgments

This historical biography was synthesized for the OrthopaedicsOne Knowledge Network as part of A Who’s Who of Orthopaedics, adapted and expanded from the foundational biographical directory Who’s Who in Orthopedics (Springer-Verlag London) edited by Seyed B. Mostofi, BSc, MBBS, FRCS (Ed) (page 64).