SYMPOSIUM: ABJS CARL T. BRIGHTON WORKSHOP ON HIP PRESERVATION SURGERY
Early Experience With a Comprehensive Hip Preservation
Service Intended to Improve Clinical Care, Education,
and Academic Productivity
Christopher L. Peters MD, Stephen K. Aoki MD,
Jill A. Erickson PA-C, Lucas A. Anderson MD,
Andrew E. Anderson PhD
Published online: 28 August 2012
? The Association of Bone and Joint Surgeons1 2012
grown substantially over the past decade. Although open
hip procedures reportedly relieve pain and restore function,
arthroscopic treatment has increasingly become a reason-
able alternative. In 2008, we formed a comprehensive hip
preservation service (HPS) to address clinical, educational,
and research needs.
We compared (1) volume, type, and
corresponding improvement in pain and function of open
and arthroscopic treatments; (2) orthopaedic resident test
performance; and (3) academic productivity before and
after creation of the HPS.
undergoing 220 open procedures from 1996 to 2007
(Group 1) and 260 patients undergoing 298 procedures
(153 open, 145 arthroscopic) from 2008 to May 2010
(Group 2). At each clinic visit, we recorded Harris hip
score (HHS) and conversion to THA. Minimum followup
was 1 year for Group 1 (mean, 4 years; range, 1–13 years)
and Group 2 (mean, 1.5 years; range, 1–3 years). We
The field of hip preservation surgery has
compared orthopaedic resident performance on two stan-
dardized tests and the number of academic works
(publications, book chapters, electronic media) and peer-
reviewed grants funded before and after creation of the
Mean HHS improved from 63 to 90 in Group 1
and from 76 to 91 in Group 2. Rate of conversion to THA
was similar between groups despite expansion of surgical
volume. Standardized orthopaedic resident test perfor-
mance improved. Academic productivity as measured by
publications and grant funding was facilitated by the HPS.
Early experience with a multidisciplinary
HPS was positive; it facilitated clinical volume expansion
while maintaining improvement in pain and function in
young adults. Additional benefits included educational and
academic productivity gains.
Level of Evidence
Level IV, therapeutic study. See
Instructions for Authors for a complete description of
levels of evidence.
The field of hip preservation surgery has grown substan-
tially over the past decade, coincident with the recognition
that most hip problems in young adults are associated with
altered hip morphology [5, 25, 30, 34]. Although open hip
procedures, such as surgical dislocation [10, 13, 29, 34] for
femoroacetabular impingement (FAI) and periacetabular
osteotomy (PAO) [8, 23, 28, 35] for acetabular dysplasia,
reportedly improve pain and function [8, 13], arthroscopic
treatment has become a reasonable alternative to open hip
approaches [7, 11, 16, 17, 20, 24, 30, 32, 33]. Arthroscopic
treatment of hip disorders, such as labral injury and FAI,
has increased dramatically over the past 5 years, and
results indicating improvement in pain and function, as
The institution of the authors has received, during the study period,
funding from NIH (RO1AR053344).
All ICMJE Conflict of Interest Forms for authors and Clinical
Orthopaedics and Related Research editors and board members are
on file with the publication and can be viewed on request.
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.
C. L. Peters (&), S. K. Aoki, J. A. Erickson,
L. A. Anderson, A. E. Anderson
Department of Orthopaedic Surgery, University of Utah School
of Medicine, 590 Wakara Way, Salt Lake City, UT 84108, USA
Clin Orthop Relat Res (2012) 470:3446–3452
and Related Research®
A Publication of The Association of Bone and Joint Surgeons®
measured predominately with the Harris hip score (HHS),
have been reported [7, 11, 16, 20, 24, 30]. Nevertheless, the
question of whether early surgical treatment of structural
hip abnormalities delays or prevents hip osteoarthritis
remains largely unanswered.
Additional questions regarding the indications and cor-
responding improvement in pain and function of open
versus arthroscopic procedures for specific intra- and
extraarticular hip abnormalities are of current interest to
hip preservation surgeons. Moreover, the rapid growth of
hip preservation surgery has motivated questions regarding
effective models of clinical care, education, and academic
activity. Traditional clinical care models have consisted of
institutions or surgeons providing only one specific oper-
ative approach for most hip preservation indications. More
recently, others have utilized a multidisciplinary approach
based on the extent or severity of hip pathomorphology or
surgeon skill set. In 2008, our center established a com-
together surgeons with specific skill and interest in open
and arthroscopic treatment of the hip. The clinical goal of
the HPS was to refine operative indications via creation of
a treatment algorithm and measurement of clinical out-
comes. Additional goals of the HPS were to provide a more
structured forum (weekly conference) for didactic and
case-based education of orthopaedic trainees and to foster
clinical research and basic science research related to
experimental engineering mechanics and motion analysis
of the hip.
To measure the effectiveness of the HPS in terms of
clinical care, education, and academic productivity, we
determined the following: (1) type and volume of operative
interventions, (2) improvement in pain and clinical func-
tion and failure rate (defined as conversion to THA)
resulting from operative treatments (open and arthro-
standardized tests, and (4) amount of academic produc-
tivity specific to hip preservation in terms of publications
and grant funding or submission before and after creation
of the HPS.
Patients and Methods
All clinical data were collected prospectively in a com-
puterized database (Filemaker Pro, Santa Clara, CA, USA).
We reviewed all patients who underwent hip preservation
operations with complete clinical data before creation of
the HPS (1996 to 2007) (Group 1). A wide range of
pathology, including acetabular dysplasia, FAI, labral
injury, Legg-Calve ´-Perthes disease, slipped capital femoral
epiphyses, and other sequelae of pediatric hip disease, was
treated. During this period, the primary treatment methods
were open techniques, such as surgical dislocation, open
anterior hip de ´bridement, PAO, and femoral osteotomy.
Hip arthroscopy was used sparingly during this time period
and not included in this data set. In 2008, hip arthroscopy
was formally incorporated into the HPS, and we reviewed
all patients who underwent either open or arthroscopic
treatment of the hip after creation of the HPS (2008
through May 2010) (Group 2). We evaluated 472 patients
with 518 surgical procedures: 212 patients undergoing 220
open procedures (Group 1) and 260 patients undergoing
298 procedures (153 open, 145 arthroscopic) (Group 2).
Patient demographics were generally similar for the two
groups (Table 1). Eleven patients who underwent surgical
dislocation, 14 patients who underwent PAO, and seven
patients who underwent hip arthroscopy were lost to fol-
lowup. Reasons for loss to followup were loss of contact
information due to relocation or failure to return for or
communicate followup with outside referring physicians.
Given our practice location, many patients travel for sur-
gical care from neighboring states. Minimum followup was
1 year for Group 1 (mean, 4 years; range, 1–13 years) and
Group 2 (mean, 1.5 years; range, 1–3 years). No patients
were recalled specifically for this study; all data were
obtained from medical records and radiographs.
Clinical outcome of operatively treated patients was
assessed with the HHS [14, 18]. Failure, as defined by
conversion to THA, was determined in both groups. In
general, patients were seen in followup 2 to 6 weeks after
surgery, at 6 months, and annually thereafter. At each
followup visit, patients were assessed clinically using the
HHS and radiographically with AP pelvic and multiple
lateral radiographs. A team member other than the oper-
ating surgeon performed the clinical outcome measures.
A weekly multidisciplinary indications conference was
also initiated in 2008, in which all potentially operative hip
preservation cases were formally presented and discussed
and literature review of salient hip preservation articles was
undertaken. Surgeons, fellows, residents, physician assis-
tants, nurses, and researchers attending the conference
Table 1. Demographic information
VariableGroup 1Group 2p value
Number of patients212 (45%)260 (55%)
Number of hips220 (42%)298 (58%)
Sex (number of hips)0.19
Male92 (42%)142 (48%)
Female128 (58%)156 (52%)
Age (years)*28 ± 928 ± 110.53
26 ± 6 25 ± 50.76
4 (1–13)1.5 (1–3)
* Values are expressed as mean ± SD;
mean, with range in parentheses.
?values are expressed as
Volume 470, Number 12, December 2012Comprehensive Hip Preservation Service3447
represented various orthopaedic subspecialties, including
adult reconstruction, sports medicine, pediatric orthopae-
musculoskeletal medicine. The five goals of the conference
were to (1) establish a consistent protocol for the assess-
ment of the nonarthritic painful hip (history, physical
examination, imaging, etc); (2) ensure the appropriate
diagnosis leading to a surgical intervention; (3) discuss
treatment options and select the appropriate treatment
methodology based on the pathomorphology of the indi-
vidual hip; (4) foster hip preservation education for
residents, fellows, allied health providers, and researchers;
and (5) provide a forum for community participation such
that surgeons from surrounding hospitals could present
challenging cases and receive feedback. There were gen-
erally 12 to 20 patients discussed at each conference. The
discussion was focused on identifying the underlying hip
structural abnormality, associated chondrolabral damage in
the hip, appropriate clinical workup, including imaging,
and appropriate treatment methodology.
To assess the educational benefit of the HPS, we retro-
spectively reviewed the orthopaedic resident performance
on the lower extremity (pelvis, hip joint, femur) domain
from the American Board of Orthopaedic Surgery (ABOS)
Part I examination and in their final year of training on the
Orthopaedic In-Training Examination (OITE) before and
after creation of the HPS.
To assess the academic benefits of the HPS, we deter-
mined the number of academic works (publications, book
grants funded before and after creation of the HPS.
Independent two-tailed t-tests were used to compare
continuous variables between the groups. Dichotomous
variables were analyzed with Fisher’s exact test. To verify
for a provider effect, a modified Poisson regression was
performed. Kaplan-Meier survivorship analysis was per-
formed with failures defined as conversion to THA. We
used a log-rank survival test to analyze survivability from
index hip preservation procedure to THA. Potential con-
founders were identified as age, sex, BMI, diagnosis,
procedure, procedure type (open versus arthroscopic),
provider, and To ¨nnis grade. The OITE scores for residents
were evaluated for variance with an F test, after which an
independent two-tailed t-test for equal variances was per-
formed. We analyzed the data using STATA1Version 12
Station, TX, USA).
The two cohorts were similar in age, sex, and BMI
(Table 1) but varied in diagnosis (p\0.001), procedure
(p\0.001), and procedure type (p\0.001) (Table 2) and
To ¨nnis grade (p = 0.003) (Table 3). Of the 154 patients in
Group 1 with To ¨nnis grades available, 97 were classified as
having either To ¨nnis Grade 1 (n = 74) or 2 (n = 23)
arthritic changes, while only 37 of the 90 patients in
Table 2. Surgical procedures and diagnoses
VariableGroup 1Group 2 p value
(number of hips)
repair or de ´bridement
86 (39%) 190 (64%)
Periacetabular osteotomy116 (52%) 64 (21%)
Other18 (9%)44 (15%)
Primary diagnosis (number of hips)
Impingement 86 (39%)259 (87%)
With labral injury 10 75
Without labral Injury 76184
Dysplasia 95 (43%) 37 (12%)
Other39 (18%)2 (1%)
Table 3. Clinical and radiographic outcomes
VariableGroup 1 Group 2p value
Time to THA
3 ± 31 ± 1
Mean HHS total (points)
Postoperative 89 7889 77
Mean HHS pain (points)
Preoperative 26 30NA0.43
Postoperative 4040NA 1.00
Mean HHS function (points)
To ¨nnis grade
* Values are expressed as mean ± SD;?To ¨nnis grades were missing
for some patients; HHS = Harris hip score; NA = not available.
3448Peters et al. Clinical Orthopaedics and Related Research1
Group 2 with To ¨nnis grades available had a To ¨nnis grade
of 1 (n = 26) or 2 (n = 11) (Table 3). There was also a
provider effect in Group 2 (p\0.001) for diagnosis and
procedure. Additionally, five of eight patients in Group 2
had undergone arthroscopic intervention as their index
In Group 1, the HHS for all open procedures improved
from a preoperative value of 63 to a postoperative value of
90 (Table 3). In Group 2, the HHS for open and arthro-
scopic procedures improved from a preoperative value of
76 and 61, respectively, to postoperative values of 91 and
86, respectively (Table 3).
The survival rates at 1-year followup for Groups 1 and 2
were 95% and 94%, respectively (Fig. 1). Interestingly, the
survivor rates at 2 years were 89% and 94%, respectively.
There was no difference (p = 0.68) in the number of
patients converting to THA between Group 1 (n = 25) and
Group 2 (n = 8) (Table 3).
The OITE scores revealed residents in Group 2 achieved
a higher percentile ranking (p = 0.02) than those in Group
1 (87% versus 72%). In addition, the lower extremity
(pelvis, hip joint, femur) domain of the ABOS Part I
examination scores revealed a positive trend beginning in
2008 to one SD above the mean in 2010 (Fig. 2).
From 1996 to 2007, six original peer-reviewed manu-
scripts specific to hip preservation were published and five
grants in hip preservation were funded over 12 years for a
rate of 0.4 grants/year. After creation of the comprehensive
HPS, 15 original peer-reviewed manuscripts, four book
chapters, and five published electronic media topics were
published. Twenty additional active projects are awaiting
completion for publication (totaling 44 projects). Five
additional grants were funded in 3 years (2008–2010), a
rate of 1.7 grants/year.
As the field of hip preservation has undergone rapid
expansion, establishing improved clinical care, research,
and education models has been important to the community
of physicians providing care to young adult patients with
painful hip conditions. Our aim was to describe the positive
effects derived from the development of a comprehensive
HPS and an organized didactic conference focusing on hip
preservation. Specifically, we determined the following:
(1)type and volumeof
(2) improvement in pain and clinical function and failure
rate (defined as conversion to THA) resulting from oper-
ative treatments (open and arthroscopic), (3) orthopaedic
resident performance on standardized tests, and (4) amount
of academic productivity specific to hip preservation in
terms of publications and grant funding or submission
before and after creation of the HPS.
Because we examined the implementation effects of a
new care model from a clinical, research, and educational
perspective, there were a number of limitations. First, and
perhaps most importantly, in terms of impact on clinical
care, because our report is limited to observations from two
different time periods, we cannot directly prove pain and
Fig. 1 Kaplan-Meier survival rates and their corresponding 95% CIs,
with failure defined as conversion from index hip preservation
procedure to THA, are shown for Groups 1 and 2. The number of
patients available for followup at the corresponding intervals for
conversion to THA can be found under the graph.
Fig. 2 A graph shows the SDs of the mean scores of the orthopaedic
residents in the lower extremity (pelvis, hip joint, femur) domain from
the ABOS Part I examination by year.
Volume 470, Number 12, December 2012 Comprehensive Hip Preservation Service3449
clinical function improvement was related to the HPS. We
demonstrated mean improvement in HHS postoperatively
for both groups before and after creation of the HPS
(Table 3). Nevertheless, the fact that mean clinical out-
come improvement was maintained while the service was
substantially expanded with the addition of arthroscopic
interventions is, in and of itself, an encouraging finding.
Second, although we have demonstrated an improvement
in orthopaedic resident test performance specific to the hip
and pelvis knowledge domain after institution of the HPS,
we do not account for confounding variables such as
improvement in individual resident aptitude and interest
over time and overall educational improvements in our
residency program. Also, we have not demonstrated similar
measurable knowledge improvement at the fellow or non-
surgical physician level although our clear impression is
that conference attendees at all levels have benefited from
the increased hip preservation exposure provided from the
conference. Third, the demonstration of increased aca-
demic productivity after creation of the hip service is
confounded by the fact that recruitment of motivated
researchers (both clinical and basic science) occurred
simultaneously with development of our program; thus, the
productivity gains are likely multifaceted in nature.
Before 2008 at our institution, hip conditions such as
developmental hip dysplasia and FAI were treated with
predominantly open techniques. During this time, improve-
ment in hip pain and clinical function, as measured by the
HHS, was demonstrated (Table 3). Hip arthroscopy was for-
have demonstrated continued pain and function improve-
ments for both groups, indicating at least, despite service
expansion, clinical outcome improvement has been main-
tained. Based on multiple clinician input, a treatment
individual cases and focused on the underlying hip structural
abnormality rather than labral injury alone. This concept has
been associated with improved clinical outcomes [1, 5, 9, 12,
suggests hip preservation survivability may be improving
afterimplementationof the HPS. However, this is limited by
followup at this time and further research is needed to
monitor this trend (Fig. 1). Expansion of clinical volumes
may have indicated tailoring operative treatment to the type
and extent of hip pathomorphology and chondrolabral
damage is a valid concept [1, 4, 6, 21, 22, 26, 31, 36].
activityrelated tothe field of hippreservation. Although it is
difficult to directly measure the educational benefit of the
HPS to all participants, we found improvement in ortho-
paedic resident performance on the OITE and the lower
extremity domain of ABOS Part I examination. Given the
Fig. 3 A flowchart illustrates our general hip preservation treatment
algorithm. FAI = femoroacetabular impingement; OA = osteoarthri-
tis;PAO = periacetabularosteotomy;
femoral epiphysis; MHE = multiple hereditary exostoses. Simple
SCFE = slippedcapital
morphology = femoral cam deformity limited to anterolateral femur,
anterior focal acetabular overcoverage. Complex morphology = fem-
oral cam deformity with lateral/posterior extension, global acetabular
3450 Peters et al. Clinical Orthopaedics and Related Research1
current rapid expansion of hip preservation surgery, partic-
ular emphasis on improving educational curricula related to
key component of this has been creation of a multidisci-
plinary hip preservation conference. Presentation of clinical
information between other treating and collaborating phy-
sicians. Additionally, the scheduled meeting provided
dedicated time for clinicians and researchers to meet. This
venue facilitated exchange of ideas and enhanced the
development and execution of translational research.
An additional goal of the comprehensive HPS was to
facilitate clinical and basic science research collaboration.
An established clinical and basic science research relation-
ship focusing on the principles of computational and
experimental engineering mechanics, motion analysis, and
imaging to solve unique problems related to hip pathomor-
phology was similarly improved [2, 3, 15, 27]. We observed
an increase in research activity, including an increase in
research grants, in the 3 years after creation of the HPS. We
believed creating an educational environment focusing on a
relatively new and exciting field of orthopaedics energized
clinicians and researchers to ask important questions and
think about strategies to test clinically relevant hypotheses.
In summary, the experience of creating a comprehensive
service to address the new and growing demand for joint
preservation has raised as many questions as it has answered.
and operative indications is needed. Similarly, defining better
for advancement of the field. Our experience has shown a
multidisciplinary approach to caring for young adult patients
who desire symptom improvement and preservation of the
native hip is positive and associated with the added benefits of
enhanced trainee education and group academic productivity.
Anderson MS ATC, for their contributions to this study.
The authors thank Chris Pelt MD, and Mike B.
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