SYMPOSIUM: PAPERS PRESENTED AT THE HIP SOCIETY MEETINGS 2010
Ceramic-on-Ceramic Total Hip Arthroplasty
Incidence of Instability and Noise
David Schroder MD, Lindsey Bornstein BA,
Mathias P. G. Bostrom MD, Bryan J. Nestor MD,
Douglas E. Padgett MD, Geoffrey H. Westrich MD
Published online: 18 September 2010
? The Association of Bone and Joint Surgeons1 2010
been developed to reduce the incidence of osteolysis.
Alumina-on-alumina bearings exhibit extremely low wear
rates in vitro, but concerns exist regarding component
impingement with the potential for dislocation and the
occurrence of noise.
We determined generation of squeak-
ing and the relationship between squeaking and component
We prospectively entered 436 alumina-on-alu-
mina, cementless, primary THAs in 364 patients into our
institutional database. All procedures were performed with
the same surgical technique and the same implant. We
obtained Harris Hip scores and a noise questionnaire and
assessed radiographic component position and loosening.
We determined the difference in abduction angle between
squeakers and nonsqueakers. Minimum followup was
2 years (average, 3.5 years; range, 2.0–6.2 years).
Alternative bearing materials in THA have
preoperatively to 94.4 at latest followup. Six hips under-
went reoperation: four hips (1.1%) for dislocation and two
(0.53%) for periprosthetic fracture after trauma. The inci-
dence of noise of any type was 11%, with the most
common type of noise being clicking or snapping.
Squeaking was reported by 1.9% of patients, with no
patient being revised for this phenomenon. We found no
association between component position and squeaking.
At average 3 years followup, 98% of
ceramic-on-ceramic THAs did not require a revision, with
1.1% of hips having been revised for dislocation. Fewer
than 2% of patients reported hearing an audible squeak,
with no association found between component position and
Level of Evidence
Level IV, therapeutic study. See
Guidelines for Authors for a complete description of levels
The mean Harris hip score increased from 51.9
Wear- and particle-driven osteolysis remain a major long-
term failure mode of total joint arthroplasty . Strategies
to reduce wear have focused on improvements of the
bearing surface, including the use of enhanced polyethyl-
ene and the introduction of alternative bearings such as
metal-on-metal and ceramics. In vitro testing has confirmed
ceramic-on-ceramic bearings have the lowest wear rates of
all tested couples  and would seem best suited to the
high-activity patient in whom long-term wear is a concern.
The use of ceramic bearings in THA was introduced in
the 1970s . The initial studies reported instances of
bearing chipping and fractures [10, 20, 24]. Improvements
in ceramic manufacturing, namely hot isostatic pressing,
One of the authors (GW) has received funding from Stryker
Orthopaedics for a partial research assistant for this study and is a
consultant for Stryker Orthopaedics (Mahwah, NJ).
Each author certifies that his or her institution approved the human
protocol for this investigation, that all investigations were conducted
in conformity with ethical principles of research, and that informed
consent for participation in the study was obtained.
D. Schroder, L. Bornstein
Department of Orthopaedic Surgery, Hospital for Special
Surgery, New York, NY, USA
M. P. G. Bostrom, B. J. Nestor, D. E. Padgett,
G. H. Westrich (&)
Department of Orthopaedic Surgery, Hospital for Special
Surgery, Weill Cornell Medical College, 535 East 70th Street,
New York, NY 10021, USA
Clin Orthop Relat Res (2011) 469:437–442
resulted in decreased grain size and yielded a noticeable
decrease in the rate of material fracture and chipping .
Early to intermediate clinical followup studies of
1–5 years with these newer ceramic bearings have reported
low revision rates and few reports of wear, periprosthetic
bone loss, or lysis [14, 15, 18, 19, 31]. Reported dislocation
rates with ceramic bearings have been low (ie, 1.1% to 3%)
[4, 7]. Some authors have reported problems unique to
these hard-on-hard bearings, such as clicking and squeak-
ing, as well as instances of chipping, despite these new
manufacturing techniques for ceramics [14, 16, 19, 23,
28, 30]. However, few reports exist investigating the
presence of squeaking during specific daily activities and
how this may relate to patient satisfaction.
We determined the incidence of noise, specifically
squeaking, how and when squeaking most affected
patients, and the relationship between squeaking and
component position of ceramic-on-ceramic THAs; we also
sought to confirm previous reports of function, and revi-
sion, osteolysis, and dislocation rates.
Patients and Methods
We reviewed the records of all 364 patients who underwent
436 primary ceramic-on-ceramic THA with a metal backed
socket between January 2003 and December 2006. The
only exclusion criterion was having less than 2 years of
followup. During this time we performed a total of 1,865
primary THAs in 1,640 patients. The indications for the use
of this implant were younger and/or more active patients.
Relative contraindications for the use of this implant were
elderly low-demand patients. Of the 364 patients, four died,
one of whom had bilateral THAs, leaving 360 patients and
431 THAs available for review. Clinical followup was
available for 317 patients (88%) with 375 THAs. There
were 117 women and 200 men. The diagnosis at time of
primary THA was osteoarthritis in 298 hips (80%), avas-
cular necrosis in 46 (12%), posttraumatic osteoarthritis in
16 (4%), developmental dysplasia in 13 (4%), and rheu-
matoid arthritis in 2 (0.53%). The average age of patients at
the time of surgery was 54 years (range, 21–80 years).
Minimum followup was 2 years (average, 3.5 years; range,
2.0–6.2 years). The remaining 43 patients with 56 THAs
were lost to followup. Attempts were made to contact these
patients over the phone and through the mail. However,
they either did not return our calls or their phone numbers
and/or addresses were no longer valid. No patients were
recalled specifically for this study; all data was obtained
from medical records and radiographs. This study was
approved by our institutional review board.
All procedures were performed with the same surgical
technique via a posterior approach with the patients in the
lateral decubitus position. The acetabulum was reamed to
the size of the acetabular component that was selected,
since the actual components are slightly larger to achieve a
press fit. Femoral preparation involved axially reaming and
then broaching until the proper press fit was achieved.
Components for all cases were the Trident1 PSL1
(Stryker Orthopaedics, Mahwah, NJ) or hemispherical
cementless cup and the SecurFit1 stem, a hydroxyapa-
tite-enhanced uncemented stem (Stryker Orthopaedics,
Mahwah, NJ). The ceramic components used in this study
were alumina (Ceramtec AG, Plochingen, Germany). After
the final reduction, posterior short external rotators and pos-
terior capsular repair were performed in all cases. Femoral
component head sizes were 28 mm in 41 cases (11%),
32 mm in 254 cases (68%), and 36 mm in 80 cases (21%).
The postoperative physical therapy protocol was stan-
dardized. Patients were mobilized on the day of surgery if
the surgery was performed in the morning; if the surgery
was performed in the afternoon, patients were mobilized
the following day. Patients were instructed on ROM and
strengthening exercises and all therapy was supervised.
Patients were weight bearing as tolerated, starting with a
walker and then moving to a cane when able to (typically
postoperative day 1) and were able to achieve stair
climbing before hospital discharge. Physical therapy was
performed for about 30 minutes, two times a day.
All patients consented to enter our implant registry
and data were prospectively collected and entered in the
registry. Patients were seen preoperatively, 6 weeks post-
operatively, and then yearly thereafter. At each office visit
(both preoperatively and postoperatively), AP pelvic and
frogleg lateral hip radiographs were performed. At each
of these visits, patients also completed a packet of sur-
veys, which included both the Harris Hip Survey  and a
self-reported noise questionnaire (Appendix 1). In addition
to these questionnaires, information on patient demo-
graphics, primary diagnosis, revision, and dislocation was
entered into the registry. The noise questionnaire was
added to the packet of surveys given to each patient after
some patients had already returned for followup. There-
fore, the noise questionnaire was completed by 306 of
360 patients (85%).
One of us (DS), who was not a treating surgeon, eval-
uated the AP pelvic and frogleg lateral hip radiographs for
signs of osteolysis, component position, and loosening.
Osteolysis was assessed at the acetabulum according to the
classification of DeLee and Charnley  and at the femoral
component as described by Gruen et al. . Component
position was assessed by measuring cup abduction angle on
the PACS digital x-ray system using the methods described
by Visser and Konings . Using digital software to
measure hip implant radiographs within PACS reportedly
has intraobserver and interobserver Kappa values of
438Schroder et al.Clinical Orthopaedics and Related Research1
0.9–0.97 and 0.74–0.83, respectively . Bony ingrowth
was described according to criteria of Engh et al. .
Statistical analysis was performed using SAS Version
9.1 (SAS Institute Inc., Cary, NC). A Wilcoxon rank sum
test was used to determine differences in abduction angle
between squeakers and nonsqueakers. Patients who did not
complete the noise questionnaire were eliminated from
this comparison. Raw percentages were calculated to
determine the incidence of noise, squeaking, revision rate
and dislocation rate. Patients who did not complete the
questionnaire were not included in any incidence calcula-
tion based on data collected using that questionnaire.
The self-reported incidence of noise of any type was 11%
(41 of 362). The majority of patients reported that they
rarely heard this noise (Table 1). Patients reported clicking
as the most common type of noise (Table 2). Some patients
experienced the noise during more than one type of activity
(Table 3). The incidence of patient-reported audible
squeaking was 1.9% (seven of 362). Audible squeaking
was defined as a squeak that the patient said other people
could hear. Of those audible squeakers, three patients heard
the squeak rarely (43%), two heard it occasionally (29%),
and two heard it frequently (29%). Patients most com-
monly experienced the squeak while squatting (N = 2,
28.6%), walking (N = 2, 29%), or bending (N = 2, 29%).
Patients also experienced the squeak while sitting (N = 1,
14%), moving one’s leg (N = 1, 14%), and going up and
down stairs (N = 1, 14%). No patients reported the
squeaking substantially affected their quality of life, which
was defined as a score greater than or equal to 6 on a
10 point scale (mean = 2, range, 1–5). No patient reported
that the noise was associated with pain. Of the seven hips
with reported audible squeaking, no patient had a revision
The average abduction angle of the entire cohort was
46.0? (± 6.2). No difference (p = 0.0743) was found
between the abduction angle of patients with squeaking
(median 52, mean 50.1, standard deviation 10.3) and those
without (median 46.3, mean 46.0, standard deviation 6.0).
The mean Harris hip score for the entire cohort
increased from 51.9 preoperatively to 94.4 at last followup.
Overall, six of 375 (1.6%) hips underwent revision. The
time to revision averaged 1 year and 5 months after pri-
mary THA. Reasons for revision included instability in
four and posttraumatic periprosthetic fracture in two.
Another patient experienced thigh pain with a positive
bone scan showing increased uptake at the tip of the stem
(stress concentration) for which a strut allograft was
placed. There were no infections. All surviving implants
had radiographic evidence of stable bony ingrowth. No
Trident1 acetabular component had any evidence of
loosening, and no SecureFit1 stem had any evidence of
loosening. No osteolysis was noted on any hip at either the
cup or stem. No hip sustained a fracture of the alumina
components at followup evaluation.
Revision for instability in our case series occurred in
only four cases (1.1%). An additional patient experienced
subjective instability and was treated nonoperatively with
physical therapy directed at hip strengthening. With one of
the hips revised for instability, the patient did not even
realize the dislocation had occurred and this was thought to
be a neuropathic joint.
The long term issue with total hip arthroplasty is related to
wear. Strategies aimed to reduce wear and lysis are cur-
rently focused on improving the bearing surface. Clinical
investigation into the use of alternative bearings such as
cross linked polyethylenes, metal on metal bearings, and
Table 1. Frequency of noise
Frequency of noiseIncidence
Rarely (n = 23)56.1%
Occasionally (n = 12)29.3%
Frequently (n = 6) 14.6%
Always (n = 0)0%
Table 2. Type of noise
Type of noiseIncidence
Squeak (n = 9)31.0%
Click (n = 19)46.3%
Snap (n = 2)4.9%
Grind (n = 4)9.8%
Pop (n = 2)4.9%
Other (n = 5)12.2%
Table 3. Activities during which patients experienced noise
Walking (n = 11)26.8%
Exercising/sports (n = 8)19.5%
Bending down (n = 5)12.2%
Stairs (n = 5)12.2%
Squatting (n = 4)9.8%
Sex (n = 4)9.8%
Volume 469, Number 2, February 2011Ceramic-on-Ceramic THA: Instability and Noise 439
ceramic-on-ceramic are therefore timely and appropriate.
The purpose of our study was to evaluate the incidence of
squeaking in a large series of ceramic-on-ceramic total hip
replacements at short term followup and the relationship
between squeaking and component position. Noise, spe-
cifically squeaking, has emerged as a concern for both
patients and clinicians, and although not unique to ceramic
bearings, the incidence of squeaking following ceramic-on-
ceramic THA may be more prevalent than in other implant
systems, potentially affecting patient quality of life . We
also reviewed rates of revision and instability following
There are several limitations of this study. First, our
assessment of the incidence of noise was based on self-
reported patient data, and patients may have different
thresholds for what they consider an audible noise or
specifically a squeak. Also, it has been noted that some
patients may not notice implant noise until specifically
prompted or asked by a healthcare professional. Second,
our incidenceof instability
squeaking, was low and therefore we could not establish
relationships between patient factors, surgical factors, and
implant specific factors. Third, our center is a large joint
replacement center and the findings may not be general-
izable to the general community.
At an average followup of 3.5 years, 98% of hips were
functioning well. We found an overall incidence of any
patient reported noise of 11% with squeaking reported in
1.9% of hips. Noise after total hip arthroplasty is not
unique to ceramic bearings, but the occurrence of noise,
especially squeaking, has become a particularly important
issue with ceramic bearings [23, 28, 30]. The reported
incidence of squeaking ranges from 1% to 21% [14, 16, 23,
30] (Table 4). Therefore, the low incidence of squeaking
observed in our study across multiple surgeons compares
favorably with literature. Additionally, a majority of
audible squeakers experienced squeaking rarely or occa-
sionally, and squeaking was mostly limited to during
squatting, walking, and bending. No patient reported that
the squeak was associated with pain, and no patient
reported that the squeaking substantially affected their
quality of life. Although squeaking remains a concern
following ceramic-on-ceramic THA, squeaking had little
effect on postoperative patient function and satisfaction in
our cohort at short term followup.
The etiology of squeaking is still unclear. Walter et al.
 suggest a series of events resulting from edge loading
of components, especially when components are malposi-
tioned. These authors suggest that the friction created by
fluid film lubrication breakdown with edge loading results
in some form of resonance at parts of the total hip con-
struct, specifically the metal portions (stem and shell), with
frequencies in the audible range . Others have sug-
gested metal transfer and deposition onto the femoral head
may be responsible for this phenomenon . While com-
ponent malposition has been suggested as a cause ,
others have noted squeaking in well-positioned compo-
nents [14, 23]. We were unable to demonstrate any
difference between the median abduction angle of patients
with squeaking (528) and those without (46.38); however,
there was a trend towards significance and only a small
cohort of patients reported a squeak (n = 7). Therefore,
our study does not support improper component position as
a cause of implant squeaking.
In addition to the incidence of noise, we analyzed the
rates of revision and instability following THA to confirm
previous reports of implant performance at short term
followup. There were six revisions in our patient cohort:
four for instability and two for periprosthetic fracture.
There were no cases revised for infection, bearing fracture
or aseptic loosening of either the socket or stem. The
revision rate of this series is consistent with that of prior
reports. The original investigational device exemption
study for the US Food Drug Administration reported sur-
vival at 5 years of 99% . Case series with third-
generation alumina components show excellent functioning
at 7.5 years’ followup with 96% survival when all causes
of revision are considered . A recent report of data
collected as part of the Australian Orthopaedic Association
Joint Replacement Registry revealed ceramic-on-ceramic
THAs had the lowest cumulative rate of revision at 7 years
(3%) compared to metal-on-metal (4%) and metal-on-
polyethylene (3%) .
The dislocation rate for our cohort was 1.1% (4 of 375
hips). This incidence compares favorably to other pub-
lished reports regarding dislocation after THA from both
the Mayo Clinic as well as our own institution [2, 21]
(Table 5). All patients were operated upon by four expe-
rienced surgeons using a standard posterolateral approach.
The lower rates of instability may be related to two factors.
During the time frame of this study, all patients had the
posterior capsule and rotators reattached using the method
described by Pellicci et al. . In addition, the vast
majority of patients (89%) had either a 32 or 36 millimeter
diameter bearing surface. Either of these factors or a
combination of the two may explain our low rate of
Table 4. Incidence of squeaking with ceramic bearings
Jarrett et al. 14/131 (10.7%)
Keurentjes et al. 9/43 (20.9%)*
Restrepo et al. 28/999 (2.7%)
Schroder et al. [current study] 7/362 (1.9%)
* Squeak defined as reproducible sound of squeaking, clicking or
440 Schroder et al.Clinical Orthopaedics and Related Research1
instability. The observation of low rates of instability with
ceramic on ceramic bearings is not new. D’Antonio et al.
observed a higher instability rate with their metal-on-
polyethylene cohort (4%, largely 28 millimeter head
diameters) than with their ceramic group (3%, 32 milli-
meter) . Capello et al. described a multicentered
experience with a combined instability rate of 1.1%,
although the posterolateral approach was not used at all
centers . While larger head diameter is implicit in the
decreased rate of instability, what role the ceramic on
ceramic bearing itself plays is not clear. It should be noted
that instability occurred in five patients in this series and
that four of the five were revised. Due to concerns
regarding possible damage to the ceramic bearing surface
as a consequence of dislocation and reduction, our bias was
to revise sooner than not. Retrieval analyses of ceramic
bearings have demonstrated severe patterns of damage in
cases revised for instability with extensive metal transfer
and material loss of the ceramic component [1, 28]. Based
upon this observation, we believe it is appropriate to con-
sider revision for the unstable ceramic-on-ceramic total hip
Our data on the low incidence of implant noise and the
negligible effect of squeaking on patient quality of life
following ceramic-on-ceramic total hip arthroplasty sup-
ports the continueduse
Improvements in Harris Hip Score as well as the low rates
of early revision and instability further confirm the safety
and efficacy of this procedure in the younger patient in
whom longer term use is a concern. Further studies are
required to investigate possible causes of and ways to
prevent squeaking, as no relationship between squeaking
and component position was found. Whether the use of this
newer bearing couple will result in the reduction of wear
and osteolysis will need to be reported at longer term
ofthis implant system.
data collection for this study.
We thank Kristin Foote for her assistance with
Table 5. Dislocation rates in primary total hip arthroplasty
Authors Implant Type Dislocation Rate
Berry et al.  Variable4.1% (868/21,047)
Capello et al.  Ceramic1.1% (18/1635)
D’Antonio et al. Polyethylene4.2% (10/349)
Padgett et al. Variable4.8% (12/254)
Schroder et al. [current study] Ceramic1.1% (4/375)
Does your hip replacement make a noise?
a. Never b. Rarely c. Occasionally d. Frequently e. Always
How would you describe this noise?
a. Squeak b. Click c. Snap d. Grind e. Pop f. Other_______
Can other people hear it?
a. Yes b. No
Is this noise associated with pain?
a. Yes b. No
With which activity do you experience this noise? (mark all that apply)
a. Walking b. Stairs c. Sporting activities d. Other ___________
How much does this noise affect your quality of life?
1 2 3 4 5 6 7 8 9 10
Never Occasionally Always
Appendix 1: Total Hip Replacement Questionnaire
Volume 469, Number 2, February 2011Ceramic-on-Ceramic THA: Instability and Noise441
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442Schroder et al.Clinical Orthopaedics and Related Research1