1. Karuppal R. Biological fixation of total hip arthroplasty:
facts and factors. J Orthop. 2016; 13(3):190-2.
2. 12th annual report. National Joint Registry for
England, Wales, Northern Ireland and the Isle of Man.
bone. Undersizing of the Corail stem has been shown
to be associated with aseptic loosening by Magill et
al, and they highlight the trend away from the smaller
sizes in their series which they attribute to preoperative
templating and a learning curve (8). Both of our stems
which were revised for aseptic loosening were revised
to larger Corail stems and post-operative x-rays
demonstrate that they were undersized at the time of
the original surgery which indicates that the cause of
revision was surgeon related and not prosthesis related.
With experience and digital pre-operative templating
undersizing may be avoided.
The is a wide variation in types of femurs, but in
particular computed tomography studies have shown
women and small femurs tend to be narrower in cross
section (9). These narrower femurs tend to have a higher
fracture rate, and the Corail stem size was statistically
smaller in those with fracture than without (9). Only
one of the 4 stems revised in our cohort was in a female.
However, surgeons using this particular stem should
be familiar with these potential problems and have
strategies to combat them. Due to the unavailability
of the dysplasia stem during our period of review, the
senior author utilised alternative stems with increased
modular options for potentially problematic narrow
femurs in our unit.
It is interesting in our cohort that all revisions were
associated with collarless stems. Since 2011 the senior
author has evolved his practice to use exclusively collared
stems. No failures have been noted since this change in
practice which represents 18.8% of the study population.
The collar provides useful short term benefits and projects
against early subsidence and fracture (10). Although
there is no evidence showing a long-term difference
between outcomes of collared or non-collared Corail
stems, it has been proposed that collared uncemented
stems have significantly greater immediate stability than
collarless stems, and can withstand greater vertical and
horizontal forces before the initiation of subsidence and
subsequent fracture (11).
Metal-on-metal bearing surface complications are a
well-recognised reason for revision arthroplasty and
is observed in our small cohort with 2 out of 6 patients
(33%) undergoing revision surgery, and one of the 4
stems revised due to loosening secondary to ALVAL.
Multiple reports in the literature support the risk of
revision associated with metal-on-metal bearing surfaces
with increased metal ion levels, excessive bearing and
taper wear, local soft tissue complications and possible
risk of systemic issues all being reported (12). Stemmed
metal-on-metal total hip replacements perform poorly in
registry data and have not been shown to be superior to
metal-on-polyethylene in comparison studies (13, 14).
Weaknesses of this study include that it is based on a
single surgeon practice from a single institution dealing
with elective arthroplasty, and that our numbers are
low compared to data from joint registers therefore
it is not possible to extrapolate our findings. However,
the smaller size of the study and its single institution
remit allows a more qualitative review of the reasons for
failure, which is not possible when parsing the registry
data alone. The Mean medullary canal cross-section in
the population is unknown and may be smaller than the
registry, which would account for the smaller mean size,
however both populations are similar in ethnicity and
geographically related.
In conclusion, our findings do not reflect the findings of
Jameson in terms of the increased failure rate in smaller
Corail stems (6). Four stems out of 53 stems had to be
revised for aseptic loosening, fracture and metal-on
metal complications. Though this represents a revision
rate of 7.5%, only two cases required revision for aseptic
loosening (3.8%). The other revision cases represent
trauma and MOM complication which can be considered
unrelated to the size of the femoral stem. Thus, a revision
rate of 3.8% is more in keeping with the international
published literature with an average time to revision
of 101.5 months. We could not find any evidence of an
increased revision rate related to the use of small sized
Corail stems. Smaller femurs are often associated with
challenging proximal femoral morphology, and sizing
can be particularly difficult in Dorr A femurs, coxa vara
femurs and in smaller female patients, who often have
dysplastic hips. When templating pre-operatively, the
surgeon who finds smaller sizes indicated must be wary
of these potential difficulties and sequela, and have
strategies ready if difficulties are encountered.
The authors report no conflict of interest concerning
the materials or methods used in this study or the
findings specified in this paper.
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3. Annual report. Norwegian National Advisory Unit
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4. Annual report. Australian Orthopaedic Association
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5. ODEP product ratings. Orthopaedic Data Evaluation
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6. Jameson SS, Baker PN, Mason J, Rymaszewska M,
Gregg PJ, Deehan DJ, et al. Independent predictors
of failure up to 7.5 years after 35 386 single-brand
cementless total hip replacements: a retrospective
cohort study using National Joint Registry data. Bone
Joint J. 2013; 95-B(6):747-57.
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8. Magill P, Blaney J, Hill JC, Bonnin MP, Beverland DE.
Impact of a learning curve on the survivorship of
4802 cementless total hip arthroplasties. Bone Joint
J. 2016; 98-B(12):1589-96.
9. Bonnin MP, Neto CC, Aitsiselmi T, Murphy CG, Bossard
N, Roche S. Increased incidence of femoral fractures
in small femurs and women undergoing uncemented
total hip arthroplasty-why? Bone Joint J. 2015; 97-
B(6):741-8.
10. Selmi TAS, Semay JM, Barbour V, Fessy MH, Bonnin M,
Fary C, et al. Basic Science. In: Vidalain JP, Selmi TA,
Beverland D, Young S, Board T, Boldt J, editors, The
Corail® Hip System: a practical approach based on
25 years of experience. Berlin, Heidelberg: Springer
Science & Business Media; 2011. P. 7-51.
11. Demey G, Fary C, Lustig S, Neyret P, si Selmi TA. Does a
collar improve the immediate stability of uncemented
femoral hip stems in total hip arthroplasty? A
bilateral comparative cadaver study. J Arthroplasty.
26(8):1549-55.
12. Haddad FS, Thakrar RR, Hart AJ, Skinner JA, Nargol AV,
Nolan JF, et al. Metal-on-metal bearings: the evidence
so far. J Bone Joint Surg Br. 2011; 93(5):572-9.
13. Smith AJ, Dieppe P, Vernon K, Porter M, Blom AW. Failure
rates of stemmed metal-on-metal hip replacements:
analysis of data from the National Joint Registry of
England and Wales. Lancet. 379(9822):1199-204.
14. Sedrakyan A, Normand SL, Dabic S, Jacobs S, Graves
S, Marinac-Dabic D. Comparative assessment of
implantable hip devices with different bearing
surfaces: systematic appraisal of evidence. BMJ. 2011;
343(1):d7434.
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