Artificial cervical joint improves patient outcome, reduces healthcare costs worldwide and benefits business
Submitting InstitutionUniversity of Bristol
Unit of AssessmentPsychology, Psychiatry and Neuroscience
Summary Impact TypeTechnological
Research Subject Area(s)
Medical and Health Sciences: Clinical Sciences
Summary of the impact
An artificial cervical joint, designed by Mr Steven Gill, honorary Chair
in the University of Bristol
and consultant in Neurosurgery at Frenchay Hospital, is widely used for
the treatment of
degenerative cervical disc disease. Patients who have received the device
have retained neck
mobility and have experienced less neck pain and better neurological
function than patients who
have undergone conventional treatment involving fusion of the vertebrae.
The device has also
yielded substantial long-term savings as far fewer patients require
secondary surgery. Gill's device
was the first artificial cervical joint approved by the US Food and Drug
Administration (FDA), in
2007. In early 2008, the global medical technology company Medtronic
launched the device
commercially in the US. The device is now used in 60 countries and has so
far generated more
than $137 million in sales.
The discs between the vertebrae act as natural shock absorbers and
provide flexibility in the spine.
When these discs degenerate — through natural wear and tear or as a result
of impact or other
injury — the result can be marked discomfort, reduced mobility of the head
and neck and numbness
and/or weakness in the extremities as a consequence of compressed or
irritated nerves in the
cervical region. It is estimated that 60% of people over the age of 40
have some degree of
degenerative disc disease. Degeneration of these discs in the neck region
is known as cervical
degenerative disc disease (cDDD). Since the 1950s, the prevailing surgical
treatment of cDDD was
to remove the disc, partially or fully, and fuse the vertebrae together —
a procedure known as
anterior cervical decompression and fusion (ACDF). However, by the early
1990s it was
recognised that fusion of the vertebrae accelerated the degeneration of
adjacent discs: ACDF
altered the biomechanics of the spine to the extent that 25% of patients
were exhibiting symptoms
of adjacent-level disease within ten years of their operation and having
to undergo additional
surgery. Devices were designed to replace intervertebral discs and to
mimic natural vertebral
movement but were largely unsuccessful. Most devices were directed at the
lumbar spine rather
than the cervical spine, and very few made it to clinical trials.
In 1993, Mr Steven Gill was appointed Honorary Senior Lecturer in the
University of Bristol and
Consultant in Neurosurgery at Frenchay Hospital. Gill worked with Mr Brian
Consultant Neurosurgeon at Frenchay Hospital, to place an artificial
cervical joint (ACJ) — known
as the Cummins joint — in 20 eligible patients. Though adjacent segment
degeneration was not
observed in any of the patients , there were complications with the
device. Gill subsequently
designed a new device which allowed more physiological motion, and made
significant changes to
the screw locking mechanism to address complications associated with the
Cummins joint. This
new ACJ became known as the Frenchay artificial cervical joint and a
patent for the design was
filed in October 1998, with Gill listed as one of the inventors and
Sofamor Danek Holdings Inc (now
Medtronic) holding the patent (US patent no. 6,113,637; published
September 5, 2000).
In 1998, Gill (by now Head of the Functional Neurosurgery Research Group
in the University of
Bristol) and his colleagues placed the new joint in 15 patients. In a
two-year pilot study, Gill and his
colleagues established the safety of their surgical technique, proved the
stability of the implanted
device and confirmed the ability of the joint to maintain natural
intersegmental motion at the level of
the ACJ without causing excessive motion at adjacent intervertebral
levels, in contrast to the
effects of intervertebral fusion [2, 3].
In 2000, the first prospective, randomized trial to compare cervical
arthroplasty (using the Frenchay
ACJ) with ACDF was conducted in centres in Belgium, the UK, Switzerland
and Australia. In 2004,
Gill and his colleagues presented the data on 47 of the patients involved
in the trial , which
showed significantly greater improvement in the neck disability index six
weeks after the operation
in the arthroplasty group (as well as slightly shorter operating times and
blood loss) .
This research, which provided evidence of the efficacy of Gill's ACJ
design in the treatment of
degenerative cervical disc disease, led to the Frenchay joint becoming the
ACJ, sold commercially by Medtronic as the PRESTIGE® Cervical Disc System.
adoption of this device in 2007 and its widespread subsequent use has
improved clinical outcome
and quality of life for patients with cDDD.
References to the research
 Wigfield, C.C., Gill, S.S., Nelson, R.J., Metcalf, N.H. &
Robertson, J.T. (2002) `The new
Frenchay artificial cervical joint: results from a two year pilot study',
Spine, 27(22): 2446-2452.
doi: 10.1097/01.BRS.0000032365.21711.5E. Citations=166.
 Wigfield, C., Gill, S., Nelson, R., Langdon, I., Metcalf, N. &
Robertson, J. (2002) `Influence
of an artificial cervical joint compared with fusion on adjacent-level
motion in the treatment
of degenerative cervical disc disease', Journal of Neurosurgery:
Spine, 96 (1): 17-21.
 Brotchi, J., Gill, S., Kahler, R., Lubansu, A., Nelson, R., McCombe,
P. & Porchet, F. (2004)
`A multicenter, prospective, randomized, study of an artificial cervical
disc versus fusion for
primary cervical disc surgery', Journal of Bone & Joint Surgery,
British Volume, SUPP I: 85-86.
*All citation values from Google Scholar as of September 6th,
Details of the impact
Patients benefit from improved clinical outcomes and improved quality
Several studies (cited in [a]), including a five-year randomised control
trial comparing the outcomes
of 541 patients across 32 investigational sites and showing improved
outcomes for those patients
who had received a PRESTIGE disc (276 patients) versus those who had the
ACDF (265 patients)
[b], confirmed the clinical benefit of the artificial joint and
underpinned changes in NICE guidance.
The following outcomes were reported:
Neurological function as evaluated through tests of motor
function, sensory function and
deep tendon reflexes was consistently significantly higher for the ACJ
Neck disability index improved for both patient groups, but
those that had received the ACJ
consistently had lower scores (i.e., less pain and disability) than
those that had ACDF. At
both three and five years after the operation, the differences between
these two treatment
groups were significant.
Neck pain after the operation was consistently less among those
that had received the ACJ
(though the differences between groups were not significant after five
Mean angular motion in the spine at the site of operation was
maintained in the ACJ group
five years after the operation, whereas it was greatly restricted in the
ACDF group, as
Reduced number of secondary surgeries and interventions at the
original site of operation
among those that had received the ACJ. There were 11 secondary surgeries
with the ACJ group and 32 associated with the ACDF group.
For people living with debilitating neck pain, replacement of the
cervical disc with an ACJ is a
viable treatment option that will not compromise future mobility. One
patient reported that after
having the PRESTIGE disc surgery, "the neck pain [she] had come to think
of as normal was gone.
[She] went back to work within a week and did a 25-mile bike ride within
two weeks" [c, pg 16].
Changes to National Institute for Health and Clinical Excellence
The most recent (May 2010) guidance from NICE is that "current evidence on
the efficacy of
prosthetic intervertebral disc replacement in the cervical spine shows
that this procedure is as least
as efficacious as fusion in the short term and may result in a reduced
need for revision surgery in
the long term" [a]. This represents a shift from the NICE guidance issued
in November 2004, which
stated that there was sufficient evidence regarding the safety and
efficacy of the prosthetic
intervertebral disc replacement procedure to support its use, but that
"there is little evidence on
outcomes beyond 2-3 years" [d].
Economic benefits to society associated with ACJ
There are substantial cumulative long-term healthcare savings associated
with the use of an ACJ
rather than ACDF. Though in-patient cervical arthroplasty is initially
more costly, there is a reduced
need for subsequent surgeries, resulting in a mean net benefit of $431 per
patient [e]. When
considering only outpatient single-level procedures, ACJ is 62% less
costly than ACDF [f]. Patients
who received an ACJ also had fewer days off work post-surgery (a mean of
38 work days) than
patients who had fusion surgery [e]. Based on the occupations and wages of
the study group
participants, this resulted in a mean societal benefit of $6,547 (2007
figures) per patient over two
years post-surgery due to reduced wage loss [e]. The long-term reduction
in healthcare costs
associated with cervical arthroplasty will have an ongoing positive
economic impact on society.
Medtronic benefits from the commercialisation of the ACJ developed in
Medtronic is the world's largest medical technology company, reaching more
than 120 countries.
The ACJ developed by Medtronic in 1998, known as PRESTIGE I, used Gill's
design that improved
upon Cummins' original device to allow translational and rotational motion
[Gause, Gill et al.
(2006). United States patent No. 6,113,637, cites 1]. Medtronic
subsequently invested in several
more adaptations of the PRESTIGE ACJ and the final version, developed in
2002, was approved
by the FDA in July 2007 [g]. This enabled Medtronic to launch the PRESTIGE
® Cervical Disc
System in the US in the first quarter of 2008. The unit sold for $4,450
USD (2010 pricing) [h]. Since
its launch, 31,000 Prestige units have been sold in 60 countries (personal
Dace, Director of Product Development at Medtronic Spine & Biologics).
This amounts to more
than $137million in sales for Medtronic since 2008. Medtronic's net sales
of core spinal devices,
including the PRESTIGE, in the 2008 fiscal year were $1.869 billion USD —
an increase of 9% over
the prior fiscal year [i]. Medtronic attributed this increase to
"continued acceptance of our products
for the thoracolumbar and cervical sections of the spine" [i, pg 24].
Looking ahead in its 2008
annual report, Medtronic singled out the "continued growth and acceptance
of our PRESTIGE ®
Cervical Disc System" as an area of growth for future sales [i, pg 25].
The trend for increased growth in Medtronic's core spinal sales has
continued since 2008 [i-k]. In
2012, sales were $2.467 billion USD [k], an increase of 32% from 2008,
with much of the growth
occurring in international markets [k]. Spinal restorative therapies
constituted 20% of Medtronic's
annual revenue of $16 billion in 2012 [k].
Sources to corroborate the impact
[a] NICE (May 2010) Prosthetic intervertebral disc replacement in the
Interventional procedure guidance 341.
[b] Burkus, J.K., Haid, R.W., Traynelis, V.C. & Mummaneni, P.V.
(2010) `Long-term clinical and
radiographic outcomes of cervical disc replacement with the Prestige disc:
results from a
prospective randomized controlled clinical trial', Journal of
Neurosurgery: Spine 13:308-
318. [cites 1-3]
[c] Medtronic (2010) Innovating for life: 2010 Annual Report.
quote from an ACJ patient that has experienced improved quality of life.
[d] NICE (November 2004) Prosthetic intervertebral disc replacement,
[e] Menzin, J., Zhang, B., Neumann, P.J., Lines, L.M., Polly, D.W.,
Barnett-Myers, S., Fontes,
R. & Traynelis, V.C. (2010) `A health-economic assessment of cervical
compared with allograft fusion', Techniques in Orthopaedics, 25
10.1097/BTO.0b013e3181de5769. Independent evidence of financial benefit of
cervical arthoplasty procedure over ACDF
[f] Wohns, R. (2010) `Safety and cost-effectiveness of outpatient
cervical disc arthroplasty',
Surgical Neurology International, 1:7. doi:
evidence of financial benefit of `out-patient' cervical arthroplasty
procedure over ACDF.
[g] U.S. Food and Drug Administration 'PRESTIGE ® Cervical Disc System —
Medical Devices, Device Approvals and Clearances [website], (7
9 May2013. Letter from FDA approving the PRESTIGE ACJ.
[h] Mendenhall Associates Inc. (2010) 2010 Spinal Implant Price
Network News 21 (4):11-14.
2010 pricing of the
PRESTIGE Cervical Disc System.
[i] Medtronic (2008) Expanding Our Role: 2008 Annual Report.
Gives annual sales figures for core spinal
devices, including the PRESTIGE ACJ.
[j] Medtronic (2009) Better Healthcare: 2009 Annual Report.
of continued growth in the sale of core spinal devices, including the
[k] Medtronic (2012) Transforming for Growth: 2012 Annual Report.
Further support for financial benefits and growth in the sale of
core spinal devices, including the PRESTIGE ACJ.