ArticlePDF Available

The Durom Acetabular Component. A Concise Follow-Up of Early Revision Rates at a Minimum of 2 Years

Authors:

Abstract and Figures

We report our experience with 143 Durom acetabular components. Our data show a survivorship of 99.2% at 5 years, (95% CI 94.8-99.9), which is not consistent with other reports in the literature of high early failure rates. The true natural history of this component is yet to unfold completely.
Content may be subject to copyright.
© 2012 Wichtig Editore - ISSN 1120-7000
Hip Int (2012 ;:05 ) 562 - 56522
562
The Durom acetabular component. A concise follow-up
of early revision rates at a minimum of 2 years
Jonathan Hutt 1, Matthew Dodd 2, Nikolai Briffa 2, Henry Bourke 2, Alexandra Hazlerigg 2, David Ward 2
1 Epsom and St. Helier NHS Trust, Epsom - UK
2 Department of Trauma and Orthopaedics, Kingston Hospital, Kingston-Upon-Thames, Surrey - UK
AbstrAct: We report our experience with 143 Durom acetabular components. Our data show a survi-
vorship of 99.2% at 5 years, (95% CI 94.8-99.9), which is not consistent with other reports in the litera-
ture of high early failure rates. The true natural history of this component is yet to unfold completely.
Key words: Uncemented, Durom, Survivorship, Revision
Accepted: May 21, 2012
ORIGINAL ARTICLE
DOI: 10.5301/HIP.2012.9743
INTRODUCTION
Large diameter metal on metal bearings in hip replacement
surgery are attractive options due to their wear and sta-
bility characteristics. The Durom acetabular component,
(Zimmer, IN, US), is a monoblock, flattened hemispherical
implant made of CoCr alloy with a Metasul Bearing. Initial
fixation is via press fit augmented by three cutting fins on
the peripheral rim: The component has a 0.3 mm thick-
ness pure titanium plasma sprayed porous coating without
hydroxyapatite. Initial reports of its use produced worrying
early revision rates with little demonstrable bony ongrowth
on explanted prostheses (1, 2). This led to a suspension
of activity in the US, where a number of class action law-
suits are currently in preparation. Other recent publications
have raised concerns about high early revision rates (3, 4),
but not all reported series have demonstrated such signifi-
cant problems (5, 6). We undertook a review of the Durom
acetabular components implanted at our institution.
MATERIALS AND METHODS
A retrospective review was undertaken to identify all
Durom acetabular components implanted for either total
hip replacement or hip resurfacing as a primary procedure
between March 2003 and June 2008. The senior author
performed all procedures. An anterolateral approach was
used for both total hip replacement and hip resurfacing, in
a theatre with vertical laminar flow.
Acetabular preparation was performed according to the
manufacturers guidelines and reaming was line to line. In-
traoperative seating of the acetabular component was a
priority in the senior surgeon’s operative technique. The
femoral component was either a Durom cemented femo-
ral resurfacing component or an uncemented CLS stem
coupled with a large metal bearing, (both Zimmer, IN, US).
The clinical outcome was established by reviewing the
patient notes and radiographs. Those patients without
documented follow-up of at least two years were con-
tacted by telephone to establish their clinical status and
whether they had undergone revision surgery.
Statistical methods
Survival curves were constructed using the life table meth-
od with 95% confidence intervals calculated according to
Rothman (7, 8). Three curves were constructed, with failure
defined as revision for any reason, or revision for aseptic
loosening with a best and worst case scenario. Patients
© 2012 Wichtig Editore - ISSN 1120-7000 563
Hutt et al
lost to follow-up were censored at the latest time point at
which the outcome of their acetabular component was
known.
RESULTS
143 hips in 139 patients were identified between March
2003 and June 2008, consisting of 84 total hip replace-
ments, (THR), and 59 resurfacings. The average age at
surgery was 59 (Range 28-84) with a male to female ratio
of 75:64. The mean follow up was 4.3 yrs (range 2-7 yrs).
Nine patients (9 Hips) were uncontactable despite signifi-
cant efforts, and were lost to follow-up.
There were 4 acetabular component revisions in 3 hips.
One was revised for component malposition 3 years after
initial surgery. At this revision, the cup was well fixed. Fur-
ther revision was required a year later for infection. There
was 1 further revision for deep infection. One patient with
a THR underwent revision for thigh pain at 6 years and
both components were noted to be loose at surgery. One
patient is being monitored for potential adverse metal re-
action with an elevated chromium level. Further imaging
has not revealed any evidence of pseudotumour and the
patient is currently under annual review. All other patients
were functioning well with no significant symptoms.
Fig. 1 - Sur vivorship cur ve - revision for any reason. Fig. 2 - Sur vivorship cur ve - revision for aseptic loosening (Best Case).
Survivorship at 5 yrs was 99.2% (95% CI 94.8-99.9) with
revision for any reason as the endpoint (Fig. 1). Figure 2
and Figure 3 show survivorship with revision for aseptic
loosening as the endpoint in a best and worst case sce-
nario respectively. For the worst case, all patients lost to
follow-up are assumed to have failed at a time point just
after their last known status, and in this setting, survivor-
ship for aseptic loosening at 5 years would fall from 100%
(95% CI 96.2-100) to 93.4% (95% CI 87.6-96.8). The full
survivorship curves with confidence intervals are shown
for completeness, but we have used the 5 year survival
rates as the study was about establishing early revision
rates and after this time period the estimated number at
risk falls below 50% of our total cohort numbers.
DISCUSSION
Uncemented hemispherical acetabular components with a
porous coating have a good pedigree. With revision for loos-
ening or evidence of radiographic loosening as an endpoint,
survival rates of 96% at twenty years for some components
have been reported (9), and are considered as a benchmark
for new designs (10). The Durom acetabular component,
however, is the subject of some controversy, and the pub-
lished success of this particular implant in the literature varies.
© 2012 Wichtig Editore - ISSN 1120-7000
564
The Durom acetabular component. A concise report of early revision rates
Long et al reported high levels of revision in a series of
206 hips, predominately implanted in female patients (2).
At two years, 15% (30 hips) of implanted cups had been
revised for loosening, including one case of deep infection.
12 further patients had clinical failure, and of the 176 hips
remaining in the study, a further 29 had radiographic evi-
dence of failure at last follow-up. Analysis of the 13 cups
removed in the second postoperative year showed no
evidence of bony ongrowth on the porous surface of any
cups. In this series, preparation of the acetabular bed was
modified to account for the shape of the cup, with reamers
not fully seated. The size was initially reamed line-to-line.
If this did not provide stability of a trial cup, then over or
under-reaming was performed to allow a stable fit.
Berton et al reported on a series of 100 hips at a mean
follow-up of 43 months (3). In all these cases, the acetabu-
lum was under-reamed by 2 mm according to the manu-
facturer’s instructions, but 7 acetabular components had
been revised, 2 for deep infection, 1 for metallosis, and
4 for aseptic loosening. Analysis of these 14 components
showed no bony growth on the porous coating.
Not all published results are so concerning. The latest
report from the Swedish Hip Arthroplasty Register records
a survival of 99.7% at 7 yrs of 326 Durom acetabular com-
ponents (11). Of the published series, similar good results
were reported by Panousis et al (6), with no acetabular
revisions at a mean of 4.6 yrs in a consecutive series of
200 hips. Vendittoli et al had no failures of the acetabular
component at a mean follow-up of 32 months (5).
Notwithstanding the variation in results, the reports of a
lack of bony ongrowth on the surface of the cups at revi-
sion are concerning. Neither of the series above report-
ing a high revision rate could attribute the poor results to
problems of orientation. The single acetabular component
revised in our series for aseptic loosening ‘popped free’ in
the manner described initially by Dorr, and did not show
any significant bony ongrowth.
There are a number of features of this implant that may
affect its success. Although hemispherical reamers are
used, the cup itself is not a hemisphere, with a sector an-
gle of 165 degrees and a peripheral flare at the rim (2). In
addition, the rim has 2 mm sharp circumferential fins for
rotational stability to be embedded in the bone. Because
of these features, when combined with seated hemispheri-
cal reamers for acetabular preparation, it is not possible
to fully seat the prosthesis even if the fins are embedded,
and gaps remain between the contact surfaces (2, 3). The
surface is a porous plasma spray coating, with a pore size
of 20-60 um. Porous surfaces have shown good fixation to
bone both in the laboratory (12, 13) and clinically (9, 10).
Pore sizes between 50 and 400 um give the best fixation
strength within the shortest time period (12), whilst a pore
size in the range of the Durom cup gives lower strengths
of fixation. The bony ongrowth will be further affected by
the surface contact problems associated with the shape of
the implant. In addition, without this contribution to initial
stability, the inevitable movement between the implant and
surrounding bone that will ensue will further compromise
bone formation at the implant surface (14).
The problems with the series of cups paper by Long et al
were reported in an earlier letter to members of the Ameri-
can Association of Hip and Knee Surgeons (1). In 2008,
Zimmer announced a voluntary suspension of US market-
ing and distribution whilst the company undertook a review
of labelling and surgical training, citing poor surgical tech-
nique as a cause for failure. The product was relaunched
later that year, with a new surgical training programme
initiated. This included a change to line to line reaming,
use of trials in every case, correct cup positioning and ap-
propriate impaction techniques with no repositioning of the
cup. Sales were not suspended in Europe. The same year,
Zimmer published a letter saying that the implants used
in Europe and the US were identical apart from indicating
Fig. 3 - Sur vivorship cur ve - revision for aseptic loosening (Worst Case).
© 2012 Wichtig Editore - ISSN 1120-7000 565
Hutt et al
tive probability of survival in life table analysis. J Chronic Dis.
1978;31:557-60.
8. Murray DW, Carr AJ, Bulstrode C. Survival analysis of joint
replacements. J Bone Joint Surg Br. 1993;75:697-704.
9. Della Valle CJ, Mesko NW, Quigley L, Rosenberg AG,
Jacobs JJ, Galante JO. Primary total hip arthroplasty with a
porous-coated acetabular component. A concise follow-up,
at a minimum of twenty years, of previous reports. J Bone
Joint Surg Am. 2009;91:1130-5.
10. Huo MH, Parvizi J, Bal BS, Mont MA. What’s new in total hip
arthroplasty. J Bone Joint Surg Am. 2009;91:2522-34.
11. Kärrholm J, Garellick G, Herberts P. Annual Report 2008:
Swedish Hip Arthroplasty Register 2008. Available at: http://
www.jru.orthop.gu.se/. Accessed December 3, 2011.
12. Bobyn JD, Pilliar RM, Cameron HU, Weatherly GC. The op-
timum pore size for the fixation of porous-surfaced metal
implants by the ingrowth of bone. Clin Orthop Relat Res.
1980;150:263-70.
13. Welsh RP, Pilliar RM, Macnab I. Surgical implants. The role of
surface porosity in fixation to bone and acrylic. J Bone Joint
Surg Am. 1971;53:963-77.
14. Cameron HU, Pilliar RM, MacNab I. The effect of movement
on the bonding of porous metal to bone. J Biomed Mater
Res. 1973;7:301-11.
that the plasma spray coating in the US was modified by
increasing its thickness by 0.1 mm to meet FDA abrasion
testing requirements.
Our findings of 99.2% survivorship at 5 years for revision
for any reason with a minimum 2 year follow-up of all cases
are not consistent with the findings of high rates of early
failure. However, as a result of the problems reported else-
where and the ongoing controversy regarding large metal
on metal bearings, this prosthesis is no longer in use by
the senior author and all patients have been contacted to
continue annual follow-up. The full natural history of the
Durom acetabular component is yet to unfold.
Financial support: This paper has received no external funding.
Conflict of interest: The authors have no significant financial interest or
other conflict of interest relating to this paper.
Address for correspondence:
Jonathan Hutt
6 Nevis Road
Tooting
London SW17 7QX, UK
drhutt@hotmail.com
REFERENCES
1. Dorr LD. Memo to American Association of Hip and Knee
Surgeons. Available at: http://www.csengerilaw.com/drDor-
rLetter.html. Accessed 3 December, 2011.
2. Long WT, Dastane M, Harris MJ, Wan Z, Dorr LD. Failure
of the Durom Metasul acetabular component. Clin Orthop
Relat Res. 2010;468:400-5.
3. Berton C, Girard J, Krantz N, Migaud H. The Durom large
diameter head acetabular component: early results with a
large-diameter metal-on-metal bearing. J Bone Joint Surg
Br. 2010;92:202-8.
4. Illgen RL 2nd, Heiner JP, Squire MW, Conrad DN. Large-
head metal-on-metal total Hip arthroplasty using the Durom
acetabular component at minimum 1-year nterval. J Arthro-
plasty. 2010;25 (6 suppl):26-30.
5. Vendittoli P-A, Mottard S, Roy AG, Dupont C, Lavigne M.
Chromium and cobalt ion release following the Durom high
carbon content, forged metal-on-metal surface replacement
of the hip. J Bone Joint Surg Br. 2007;89:441-8.
6. Panousis K, Meek R, Roberts P, Grigoris P. The Durom hip
resurfacing - results at an average follow up of 4.6 years. J
Bone Joint Surg Br. 2010;92 (SUPP_II):307.
7. Rothman KJ. Estimation of confidence limits for the cumula-
... This advantage of using femoral heads measuring at least 36 mm in diameter has also been reported with other bearing couples such as ceramic-on-ceramic and metal-on-polyethylene [22]. Our 4.5% rate of failure due to the Durom TM cup is slightly lower than previously reported rates, which range from 0.8% to 31% (mean, 11%; median, 8.7%) after shorter mean follow-ups [11][12][13][14][15][22][23][24][25] (Table 6). With other cups, surgical revision is also required in some cases. ...
... Our data obtained after 80 months show a steady decline in survival over time with no Table 6 Comparison of cup revision rates in published studies of Durom TM cup total hip arthroplasty. sudden drop, in contradiction to results reported by Ng et al. [24] and Hutt et al. [25]. None of the factors assessed in our study was significantly associated with revision surgery or ARMD. ...
Article
Background: Large-diameter metal-on-metal hip prostheses are no longer used, but their outcomes after more than 5 years are unknown. We conducted a retrospective study with a 6.8-year mean follow-up to assess clinical outcomes after Durom™ cup implantation, including the dislocation rate, comparatively to the reference metal-on-polyethylene bearing. We determined the rate of failure ascribable to Durom™ cup use. We also looked for a sharp drop in the implant survival curve during the follow-up period and for factors associated with adverse reactions to metal debris (ARMDs). Hypothesis: We hypothesised that clinical outcomes after Durom™ cup implantation were similar to those seen with a metal-on-polyethylene bearing, except for a lower rate of dislocation. Patients and methods: We included 177 consecutive THA procedures that were performed between 2005 and 2008 in 165 patients with a mean age of 57.6 ± 9.4 years (range, 31-76 years) and involved the implantation of a Durom™ cup, a femoral head greater than 36mm in diameter, and a PF(®) femoral stem (Zimmer, Etupes, France). The mini-posterior approach was used, with 2mm of acetabular overreaming in 82% of cases, a short femoral neck in 75% of cases, and a mean cup inclination of 34 ± 5° (range, 21-50°). Results: Outcomes were assessed for 156 THA procedures in 146 patients after a mean follow-up of 6 years 8 months. The mean Postel-Merle d'Aubigné score improved from 9.7 ± 2.7 (range, 4-14) to 17.4 ± 1.7 (range, 15-18) and the mean Harris hip score from 45.2 ± 15.3 (range, 9-83) to 96.3 ± 7 (75-100). No episodes of dislocation were recorded. We identified 7 failures ascribable to the Durom™ cup including 6 due to ARMD and 1 to aseptic loosening. Implant survival after a mean of 80months was 95.5% (95% CI, 93.1-99.2), with no sharp drop in the survival curve. Conclusion: The Durom™ cup eliminates the risk of hip dislocation and produces similar functional outcomes to those seen with metal-on-polyethylene bearings after a mean follow-up of 80 months. Nevertheless, given the difficulty in predicting ARMD and hypersensitivity reactions, the Durom™ cup has been discarded and patients carrying it are monitored closely.
Article
Background: Hard bearings, metal on metal (MOM) and ceramic on ceramic (COC), have been developed to overcome polyethylene wear-related osteolysis, but comparisons between these 2 hard bearings are limited. We performed a meta-analysis to determine revision rates for (1) any reason, (2) aseptic loosening, (3) periprosthetic joint infection (PJI), and (4) recurrent dislocation between MOM and COC bearings in cementless total hip arthroplasty. Methods: This analysis included 3 studies comparing COC and MOM bearings and 56 studies reporting outcomes of MOM or COC bearings. We conducted a comparison meta-analysis (with a fixed-effects model) on the 3 comparative studies and a proportional meta-analysis on the data from the 59 articles to determine a consensus. Results: In the comparison meta-analysis, MOM showed higher revision rate than COC for any reason (odds ratio = 2.39, P = .046) and PJI (odds ratio = 6.21, P = .015). In the proportion meta-analysis, the MOM group showed significantly higher revision rate than COC group for any reason, aseptic loosening, and PJI. Conclusion: MOM bearings were associated with a higher risk of revision for any reason and PJI than COC bearings after cementless total hip arthroplasty.
Article
Résumé Introduction Les prothèses à couple métal–métal en grand diamètre ont été abandonnées mais leur devenir à un recul de plus de 5 ans n’est pas connu. Aussi nous avons mené une étude rétrospective au recul de 6,7 ans afin de préciser : (1) les résultats cliniques de la cupule Durom™ et son taux de luxation par rapport au couple de frottement de référence métal–polyéthylène ? (2) le taux d’échec imputable à cet implant ? (3) L’existence éventuelle d’une cassure de sa courbe de survie à un tel recul ? (4) La possibilité de déterminer des facteurs associés à la survenue de réactions adverses aux débris métalliques ? Hypothèse Notre hypothèse était que cette cupule présenterait des résultats cliniques comparables à ceux du couple de frottement de référence métal–polyéthylène, avec un taux de luxation moindre. Patients et méthodes La série était composée de 165 patients (177 prothèses totales de hanche [PTH]) âgés en moyenne de 57,6 ± 9,4 ans (31–76), opérés de manière continue entre 2005 et 2008 d’une PTH comportant une cupule Durom™ avec des têtes fémorales de diamètre supérieur à 36 mm et une tige fémorale PF® (Zimmer, Étupes, France). La prothèse était implantée par voie postérieure réduite avec « sur-fraisage » de l’acétabulum de 2 mm dans 82 % des cas, utilisation d’un col court dans 75 % des cas et inclinaison moyenne de la cupule de 34° ± 5° (21°–50°). Résultats Les résultats portent sur 146 patients (156 PTH) revus avec un recul moyen de 6 ans et 8 mois. Le score PMA moyen est passé de 9,7 ± 2,7 points (4–14) à 17,4 ± 1,7 points (15–18) et le score de Harris moyen de 45,2 ± 15,3 points (9–83) à 96,3 ± 7 points (75–100). Aucun épisode de luxation n’est à déplorer. Sept échecs imputables à la cupule Durom™ ont été dénombrés dont 6 réactions adverses aux débris métalliques et 1 descellement aseptique. Le taux de survie de cet implant à 80 mois de recul moyen est de 95,5 % (IC 95 %, 93,1–99,2) et la courbe de survie ne présente pas de point de rupture. Conclusion La cupule Durom™ permet d’écarter le risque de luxation et présente des résultats fonctionnels comparables au couple de frottement métal–polyéthylène à 80 mois de recul moyen. Il n’en reste pas moins que les phénomènes de réaction aux débris métalliques et allergiques sont difficiles à anticiper, ce qui a motivé l’abandon de cet implant et une surveillance rapprochée des patients qui en sont porteurs. Niveau de preuve IV Étude rétrospective.
Article
Background: Use of large-diameter metal-on-metal (MoM) articulations in THA increased, at least in part, because of the possibility of achieving improved joint stability and excellent wear characteristics in vitro. However, there have been subsequent concerning reports with adverse reactions to metal debris (ARMD), pseudotumors, and systemic complications related to metal ions. Questions/purposes: The purpose of this study was to determine at a minimum of 2 years' followup (1) the proportion of patients who experienced a dislocation; (2) the short-term survivorship obtained with these implants; (3) the causes of failure and the proportion of patients who developed ARMD; and (4) whether there were any identifiable risk factors for revision. Methods: We reviewed the results of 1235 patients who underwent 1440 large-diameter MoM primary THAs at our institution using two acetabular devices from a single manufacturer with minimum 2-year followup. Large-diameter MoM devices were used in 48% (1695 of 3567) of primary THAs during the study period. We generally used these implants in younger, more active, higher-demand patients, in patients considered at higher risk of instability, and in patients with adequate bone stock to achieve stable fixation without use of screws. Clinical records and radiographs were reviewed to determine the incidence and etiology of revision. Patients whose hips were revised were compared with those not revised to identify risk factors; Kaplan-Meier survivorship analysis was performed as was multivariate analysis to account for potential confounding variables when evaluating risk factors. Minimum followup was 2 years (average, 7 years; range, 2-12 years); complete followup was available in 85% of hips (1440 of 1695). Results: Dislocation occurred in one hip overall (<1%; one of 1440). Kaplan-Meier analysis revealed survival free of component revision was 87% at 12 years (95% confidence interval, 84%-90%). The two most common indications for revision were ARMD (48%; 47 of 108 hips revised) and loosening or failure of ingrowth (31%; 34 of 108). Risk factors for component revision were younger age at surgery (relative risk [RR] 0.98 per each increased year; p=0.02), higher cup angle of inclination (RR 1.03 per each increased degree; p=0.04), and female sex (RR 1.67; p=0.03). Conclusions: Large-diameter MoM THAs are associated with a very low dislocation rate, but failure secondary to ARMD and loosening or lack of ingrowth occur frequently. Patients with MoM THA should be encouraged to return for clinical and radiographic followup, and clinicians should maintain a low threshold to perform a systematic evaluation. Early diagnosis and appropriate treatment are recommended to prevent the damaging effects of advanced ARMD. Level of evidence: Level IV, Therapeutic study.
Full-text available
Article
Unlabelled: Large-diameter metal-on-metal articulations reportedly provide better stability and range of motion than smaller diameter bearings. We therefore asked whether a large-diameter (44- to 50-mm) metal-on-metal articulation (Durom) would eliminate dislocation and provide similar functional scores and clinical and radiographic failure rates as those with 28-mm articulation. We prospectively followed 181 patients (207 hips) who had a large-diameter articulation implanted between May 2006 and November 2007. We compared these patients with a historical control of 54 patients who had a small-diameter (28-mm Metasul) articulation. All patients had a Harris hip score and a self-assessment of outcome and radiographic followup. The minimum followup was 1 year (mean, 1.6 years; range, 1-2 years). During the followup period, we performed revisions on 29 patients (30 hips [15%]) with 21 of 29 (72%) having radiographic criteria of loosening. Thirteen retrieved cups and acetabular tissue were examined histologically. Twenty-eight of 151 unrevised patients had radiographic impending failure; 12 without revision had clinical failure. Eight patients (nine hips) had both clinical failure and impending radiographic failure. Cup inclination was 41.3 degrees +/- 5.4 degrees and anteversion was 20.2 degrees +/- 7 degrees. The revision rate and quality of clinical results were unacceptable as compared with our historical controls. We do not recommend use of the Durom implant. Level of evidence: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
Article
Survival analysis is a powerful tool for analysing the results of total joint replacement, but it has major drawbacks when the failure rates are very low. We have reviewed 35 recent survival analyses of joint replacements to assess the magnitude of these problems and make recommendations as to how they may be avoided.
Article
Large-head metal-on-metal total hip arthroplasty represents novel technology, and outcome data are lacking. We prospectively compared the performance of a nonmodular metal-on-metal acetabular component (Durom; Zimmer, Warsaw, IN) with a modular titanium component (Trilogy, Zimmer). All Durom components placed at our institution with minimum 1-year follow up (n = 63) were compared with an age- and sex-matched Trilogy control group (n = 100). Failure defined as revision or persistent moderate/severe groin pain was significantly higher for the Durom (11.1%) compared with the Trilogy group (0%) (P = .002). Although all acetabular components in both groups appeared radiographically stable, no significant bone ingrowth was noted at the time of Durom revisions. We could not identify any patient/surgical-related factors predictive of failure. Further study is needed to determine the scientific basis for these observations.
Article
Implantation of a large-diameter femoral head prosthesis with a metal-on-metal bearing surface reduces the risk of dislocation, increases the range of movement, minimises the risk of impingement and, in theory, results in little wear. Between February 2004 and March 2007 we implanted 100 consecutive total hip replacements with a metal-on-metal bearing and a large femoral head into 92 patients. There were 51 men and 41 women with a mean age of 50 years (18 to 70) at the time of surgery. Outcome was assessed using the Western Ontario McMaster University osteoarthritis index and the Harris hip score as well as the Devane activity score. These all improved significantly (p < 0.0001). At the last follow-up there were no cases of dislocation, no impingement, a good range of movement and no osteolysis, but seven revisions, two for infection and five for aseptic loosening. The probability of groin pain increased if the other acetabular component inclination exceeded 50° (p = 0.0007). At 4.8 years of follow-up, the projected survival of the Durom acetabular component, with revision for any reason, was 92.4% (sd 2.8) (95% confidence interval 89.6 to 95.2). The design of the component made it difficult both to orientate and seat, which when combined with a poor porous coating, produced unpredictable fixation and a low survival at five years.
Article
It has been nearly a decade since the introduction of this Specialty Update section in The Journal. We have covered many topics that were considered to be contemporary and controversial. In the current update, we have elected to include reviews on (1) the outcomes of primary total hip arthroplasty, (2) the outcomes of revision hip arthroplasty, (3) hip resurfacing arthroplasty, (4) complications, and (5) practice management. The major new information in the past year is in epidemiology and hip resurfacing arthroplasty. ### Epidemiology Total joint arthroplasty volume is projected to continue to increase. Kurtz et al. used the Nationwide Inpatient Sample (NIS) to make projections and to analyze population-based outcomes of total joint arthroplasty. They projected that >50% of all joint arthroplasties will be performed in patients less than sixty-five years of age by 2011. Moreover, younger patients will account for 52% of all total hip arthroplasties and 55% to 62% of all primary and revision total knee arthroplasties by 2030. This projection may have implications for the private sector with regard to insurance coverage and reimbursement for joint arthroplasty procedures in the future. ### Clinical Outcome #### Femoral Stem Hip resurfacing arthroplasty has become increasingly popular worldwide. One of the proposed advantages of resurfacing is that the outcome and durability are superior to those of conventional total hip arthroplasty, especially in younger patients. Springer et al. conducted a systematic review of three databases of published results of total hip arthroplasties performed with use of contemporary designs and cementless fixation in young patients. The meta-analysis included 5907 patients (6408 hips) less than fifty-five years of age. These patients were compared with 3002 patients with 3269 hip resurfacing arthroplasties. The pooled failure rate for the femoral stem was 1.3% at a mean of 8.4 years, compared with a failure rate of 2.6% at a mean of 3.9 years for …
Article
We previously reported the seven and fifteen-year results of the use of a porous-coated acetabular metal shell inserted without cement in a consecutive series of 204 primary total hip arthroplasties. In the present study, we evaluated the longer-term outcomes of these arthroplasties at a minimum follow-up time of twenty years. One hundred and fourteen (92%) of the 124 hips available for study had retained the original acetabular metal shell. A total of five acetabular components had been revised for aseptic loosening or had radiographic evidence of definite loosening. Fourteen hips with well-fixed acetabular shells required a change of the modular acetabular liner because of excessive wear and/or for the treatment of osteolysis, and liner changes have been recommended for another eight hips. The twenty-year rate of survival of the metal shell, with failure defined as revision because of loosening or radiographic evidence of loosening, was 96% (95% confidence interval, 94% to 98%). Cementless acetabular reconstruction continues to provide durable fixation at twenty years postoperatively. Wear-related complications continue to be the major mode of failure.
Article
An attempt has been made to define the conditions with respect to movement under which porous metal will bond to bone. It has already been shown that bone will grow into the pore of porous Vitallium under static conditions and under conditions of micromovement, as when stressed by the pull of a tendon. An experiment is described in which porous Vitallium staples were inserted across an unstable osteotomy site. No bonding occurred indicating that bone ingrowth will not occur in the presence of movement of this order of magnitude. The implication of this observation in the design of porous coated endoprostheses is that some form of initial mechanical fixation is required, and this fixation must remain rigid for four months to allow bone ingrowth.