October 2017 Edition. Volume XVII

(Usually Referred To As “Fusion”)

What It Has Been and Where It Is Going

Hibbs1911JPEG200Albee1911JPEG200Leon Wiltse, in his chapter on the history of lumbar spine stabilization (Lumbar Spine Surgery, Editors White AH et al, St. Louis: C.V. Mosby, 1987) identified Drs. Fred Albee and Russell Hibbs, orthopedic surgeons from New York City as the first surgeons to employ autogenous bone for the purpose of bone arthrodesis in 1911.

Albee used tibial grafts between spinal processes to stabilize the spine.  Hibbs, on the other hand, did not use tibial grafts but created a “feathered fusion” (his own description) in which, he “feathered”  the lamina and decorticated the facet joints and then added morsalized bone derived from the local  dorsal spinous processes. Hibb’s technique represented the very first documented example of flexible stabilization utilizing autologous local bone for reconstructive purposes.  From the work of Albee and Hibbs posterior spinal stabilization utilizing autologous bone became surgical standard procedures.

Until recently all spine stabilizations have been incorrectly referred to as “fusions.” This situation changed in 2004 when the American Medical Association in its Current Procedural Terminology publication eliminated the term and replaced it with the comprehensive term “arthrodesis.”

Burns in 1933 (Anterior Lumbar Interbody) and Briggs and Milligan, Cloward and Jaslow (Posterior Lumbar Interbody Arthrodesis) added the interbody approach and in the 1930s metallic implants were first introduced.  The pioneers in the development of metallic internal fixation hardware have been Harrington, Knodt, Larrick, Luque, Judet, Roy-Camille, Louis, Magerl, Kraag, Zielke, Strempel, Cotrel, Dubousset, Steffe, Wiltse, Selby, Bagby, Kuslich, Ray, and Michelson.

MayoBoneFus200GIF

Illustration from the June 2 2000 Mayo Clinic Health Letter

The  classic intent behind Albee’s “fusion” was to create a rigid union between vertebral segments in order to correct segmental dysfunction or instability.  While rigid stabilization has been a blessing for many patients disabled by trauma or destructive disease (i.e. cancer, tuberculosis, scoliosis, deformity etc.) it has been the cause of many failed back surgery patients when applied in the management of multi-level degenerative disease.   Shown to the left is an example of an “arthrodesis, posterior technique” utilizing the 2004 American Medical
Association, Current Procedural Terminology.

Because disc herniation was recognized as usually being associated with a dysfunctional, or hypermobile vertebral segment it became, in the 1940s, standard practice, at the Mayo Clinic, in Rochester, Minnesota (as well as some other institutions in the United States) to routinely perform posterior arthrodesis following routine discectomy.  These autologous bone grafts were regularly harvested from the patients iliac bone crest (the pelvic rim). Routine bone “fusion” with discectomy was used for many years but “fell into disuse” when studies showed that the patients with this did not appear to fare any better than those with discectomy alone.

IleumGraft200GIFThe reason for harvesting bone from the sacral iliac crest area (shown in red) was that it was the most readily available autogenous donor bone available to surgeons in the large quantity required. The “down-side” of using the ileum as a harvest site for autogenous bone has been the creation of additional problems for the patient.  These have included:
Routine
Post-Incisional Pain
Complex  Regional Pain Disorders due to Possible Neuroma
Formation
Possible Infection
Possible Post-Operative Local Hematoma
Possible Injury to the Sacro-Iliac Joint
Possible Injury to Pelvic Ligaments
Possible Pelvic Soft Tissue Problems i.e. Tissue Hernia Through
Inner Table Defect
Possible Gait Disturbances (Usually Seen in Older Patients)

The classic non-instrumented spinal bone “fusion” has always been a relatively crude and bloody procedure involving significant tissue disruption and long periods of hospitalization, immobilization and prolonged recovery .  In the 1950s-1970s these patients were often hospitalized for weeks and then discharged on bed rest, in body casts and braces, for many months of continued bed rest. If rigid bone union did not occur the procedure was considered to be a failure and this alone often led to additional surgical procedures to achieve a “solid fusion.”   What has been the success of this procedure?  The incidence of non-union through the years has been variously reported as being 0-68%.  Metallic instrumentation was introduced as a means of creating faster, and better, solid fixation. It was found, in the early attempts of instrumentation use, that the devices being applied were less-than-ideal in establishing rigidity and that the spinal forces being brought to bear on these devices were far greater than anticipated.  As a result of these data the instrumentation was progressively strengthened. This was particularly true for the pedicle screw systems.

In the same way that after Drs. Dandy, Mixter and Barr documented the concept of the herniated disc (often to the exclusion of considering another diagnosis such as lateral spinal stenosis) it was, and in some case continues to be, accepted that rigid and solid arthrodeses were good and anything less was bad. It did become apparent, in time, that “hard” fusions placed significant stress on adjacent segments.  Sometimes the effects of this could be dramatic. More often these effects were less dramatic and consisted of stress related segmental degeneration above (or below) the rigid arthrodesis.  In fact the term “transitional syndrome” was adopted to describe this common complication.  Not infrequently, this syndrome requires additional surgery. Information regarding this potentially serious situation is only rarely communicated to patients prior to surgery.

As the curtain descended on the twentieth century spine stabilization technology finally began to advance.  The greatest benefactor of rigid spine instrumented fixation has been the patient experiencing spinal trauma, scoliosis and deformity.  Those who have benefited the least from rigid spine stabilization have been those with multi-level degenerative changes throughout the spine (i.e. multi-level degeneration from genomic and geriatric conditions producing neurologic involvement).  In the latter group of patients rigid instrumented fixations as a means of treating discogenic pain have been finally identified as a “means of producing failed back surgery patients at an alarming rate”(The Lippincott Williams & Wilkins BackLetter, Vol. 19, Number 7, July, 2004, pp. 79) and the medical profession is only now coming to this realization.

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