CREST: Capsular Repair During Hip Arthroscopy

Background Femoroacetabular impingement (FAI) is a well-described condition that causes hip
pain in young to middle age adults. Cross sectional studies have estimated that the
prevalence of hip impingement ranges from 14-17% among asymptomatic young adults and nearly
95% among competitive athletes. FAI occurs as a result of a size and shape mismatch between
the femoral head and the acetabulum. There are two subtypes of FAI: Cam type and Pincer type.
Cam type is caused by a misshaped femoral head and pincer is caused by an over coverage of
the acetabular rim. Most patients have a mixed type of Cam and pincer impingement that
involves some degree of an abnormally shaped femoral neck and over coverage of the
acetabulum. Arthroscopic treatment for FAI has demonstrated promising results. It has been
shown to alleviate pain and improve function with good return to sport rates in young
athletes with FAI.

Although arthroscopic treatment for FAI has provided promising results, there is much debate
over treatment of the capsule after arthroscopic surgery. Surgeons usually either choose to
perform a capsulotomy or a partial capsulectomy during arthroscopic surgery to increase their
viewing space in order to perform procedures to address intra-articular pathologies.

The hip capsule is made up of four components: The iliofemoral, pubofemoral, and
ischiofemoral ligaments and the zona orbicularis. The iliofemoral has been shown to be the
strongest of these ligaments and the most important stabilizer in resisting anterior
translation and hip dislocation. During arthroscopic hip surgery, surgeons often use an
interportal cut made between the mid-anterior and anterolateral portal to allow visualization
of the joint. Surgeons may choose to either leave the capsule open or repair it. As
techniques have evolved, more interest has been placed on repairing the capsule in order to
improve stability following arthroscopic hip surgery. Frank et al. recently reported that
patients undergoing T-capsulotomy with complete closure had improved outcomes compared to
patients who received only partial closure. Wylie et al. recently showed improved
post-operative patient reported outcomes (PROs) following revision hip arthroscopy in order
to repair the capsule.

The goal of the CREST is to evaluate functional stability and patient reported outcome scores
following capsular repair after arthroscopic hip surgery for FAI.

Overview of study design

Patients are recruited by experienced hip surgeons for inclusion. Patients will either be
randomized to have their capsule repaired upon completion of arthroscopic hip surgery or will
have it left unrepaired. Surgeons will measure pre-operative pain and function. Over a 24
month period patients will be evaluated for pain, functional impairment, and activity level.

Patient recruitment and screening The CREST study will be performed at the Mayo Clinic
(Rochester, MN and Arizona campus), the American Hip Institute (Chicago, IL). The surgeons
coordinating this study have performed over 5,000 hip arthroscopies collectively. They have
shown the ability to recruit patients to perform these procedures and demonstrated the
ability to follow these patients for 2 years or longer in order to assess outcomes. They are
planning to start enrolling patients in January of 2017 and continue the enrollment process
on an ongoing basis. Patients will be classified based on three categories: 1) Included in
the study and randomized 2) excluded if they do not meet the inclusion criteria, or 3) Missed
(patients that were eligible but not included in the study due to an error or limited staff
availability at the time of presentation).

Study Follow-Up

Patients will undergo standard of care evaluation at baseline with follow-up at 6 weeks, 3
months, 6 months, 12 months, and 24 months after surgery. Patients who are unable to attend
the follow-up appointments will be contact by email via OBERD to complete questionnaires and
if this fails they will be contacted by phone.

Minimizing Crossovers

It is very unlikely that there will be crossover between the two groups because both groups
will have intra-articular pathology that is causing pain addressed during surgery. Any
patient who does crossover, will be analyzed with the group they were randomized (intention
to treat analysis).

Protecting against sources of bias

Multiple methods will be implemented to protect against bias. There will be concealment of
the randomization, investigators will maximize possible blinding, investigators will utilize
strategies to limit loss to follow-up and crossovers, and investigators will objectively
adjudicate patient outcomes.

Maximizing Patient Follow-Up

Both sites involved have used OBERD to collect outcomes for the past three years. They have
shown the ability to follow patients for many years after surgery using this system. Both
sites will have patients complete the PROs on iPads while waiting to be seen before clinical
visits to the surgeons. For patients who are unable to come in for clinical visits, OBERD has
the capability of sending reminders via email to patients who have not filled their PROs out
at the correct follow up time. If both of these strategies fail, then the patients will be
contacted on every phone number available in order to achieve maximum follow-up.

Sample size calculation Based on a pilot data previously collected by one of the
participating surgeons, investigators used sample size estimation to calculate that 240 total
patients (120 patients in each group) would be required to demonstrate a difference in
subjective patient reported outcome scores (mHHS and HOS-ADL and HOS-Sports) of the two
groups with an effect size of 0.8 with an alpha level of 0.05 and power of 80%. Investigators
added a potential 20% loss to follow-up in our calculations, which is very conservative. This
would leave 100 patients in each group at final follow-up and 200 patients in the study
overall. This was powered to detect a clinically significant difference of 2.0 points in mHHS
scoring and 3.84 points in HOS-ADL and HOS-Sports. This is well within previously reported
minimal clinically important differences between these three outcome scores.

In addition, investigators will also include equal groups of male and female hips (60 males
and 60 females in each group). In this manner, differences between gender will be powered to
detect a difference of 4 points for mHHS and 7.72 points for HOS score.

Data Management

Data will be collected in OBERD at both sites. Upon entering data into OBERD, personnel from
each site will ensure its accuracy and will discuss and correct all missing, inconsistent, or
inaccurate data.

Data Safety and Monitoring Committee

All data will be stored safely at each site and on the OBERD server which has been verified
to have the appropriate safe guards for patient privacy. All patients that are exchanged
between institutions will have all identifying information removed (name and clinic number)
in order to ensure privacy of the patients as well.

Ethics and Institutional Review Board (IRB) Approval

The CREST trial patients will sign an IRB approved consent form that describes this study and
provides sufficient information for patients to make an informed and educated decision about
their participation in the study. All participating institutions will obtain IRB approval
from the institution for study protocol, the consent form template, the PROs, and any
additional protocol items. Any amendments to the protocol will be communicated to the head
site (Mayo Clinic) primary investigator (Dr. Aaron Krych).

All study and patient information will be kept private and only be accessed by staff involved
in the study. All paper charts will be kept in secure, locked cabinets and all electronically
stored documents will be stored on secure databases that have received approval from both
institutions software security advisors. Information exchanged between sites involving
patient information will have all identifiers removed to preserve privacy.

Discussion

The CREST trial is necessary because as hip arthroscopy continues to grow in popularity as
the primary treatment for FAI there will be continued debate on how to handle the hip capsule
after surgery, unless studies like this are performed. There is still no compelling evidence
on the importance of hip capsule repair following arthroscopic hip surgery. Randomized
controlled trials like the CREST trial are the only feasible way to determine its importance
and determine if there is a difference in clinical outcomes following hip arthroscopy in
patients who receive a capsular repair versus those who do not.

The CREST trial is the first RCT to evaluate the difference in outcome in patients who
receive capsular repair versus those who do not following hip arthroscopy. This trial will
help overcome many of the biases that currently drive the literature and current evidence for
capsular repair. The study will be designed to have significant power to determine a
clinically important difference between the two groups in regards to clinical and functional
outcomes. The surgeons involved in the study have already shown the ability to recruit
patients to trials and the ability to follow these patients, having a collective 5,000
patients with outcomes stored in a shared database already.

This trial, like all surgical RCTs, have some limitations that cannot be avoided. First,
although all surgeons are fellowship trained and considered to be experts in hip arthroscopy
and the treatment in FAI, there are differences in surgical techniques and intra-operative
decision making that cannot be normalized. However, this also makes the results of this RCT
more generalizable. Also, as with any RCT, the surgeons cannot be blinded to the treatment
allocation.

The vast increase in surgical treatment of FAI has mainly consisted of retrospective studies
assessing its efficacy. Even fewer studies have looked at hip capsular repair and its role
following hip arthroscopy for FAI. The CREST trial will be the first randomized controlled
trial to assess clinical and functional outcome differences in patients who have their hip
capsule repaired versus unrepaired following hip arthroscopy for symptomatic hip pathology.

Criteria: Inclusion Criteria:

1. Adults aged 18 to 50 (men or women)

2. Hip pain for greater than 3 months that has failed non-operative treatment (physical
therapy, NSAIDS, rest)

3. FAI documented on X-Ray or Magnetic resonance imaging (MRI) or magnetic resonance
arthrogram (MRA)

4. Intraoperative labral repair or intact labrum

5. Informed consent from the participant

6. Ability to comprehend and speak English and the study design.

Pre-operative exclusion criteria are the following:

1. Hypermobility/Ehlers-Danlos syndrome

2. Evidence of hip dysplasia (Center edge angle less than 20)

3. Previous surgery or trauma of the affected hip

4. Severe acetabular deformities such as circumferential labral ossification, acetabular
protrusion20

5. Inflammatory/ autoimmune disease

6. Immunosuppressant medication

7. Significant medical co-morbidities such as uncontrolled diabetes, hypertension,
congestive heart failure, etc.

8. Severe mental or physical disability requiring assistance in daily living

9. History of pediatric hip disease with previous operation (developmental dysplasia,
Legg-Calve-Perthes, Slipped capital femoral epiphysis)

10. Presence of advanced hip osteoarthritis (Tonnis grade 2 or 3)18

11. Worker's compensation status

12. Intraoperative microfracture, or other procedure that would alter postoperative
rehabilitation

13. Intraoperative labral debridement or labral reconstruction

14. Peri-trochanteric or deep gluteal space arthroscopy

15. Avascular necrosis

Intra-operative exclusion criteria are the following:

1. Labral debridement

2. Labral reconstruction

3. Poor quality capsular tissue

4. Hyperlaxity based on excessive subluxation of the joint greater than 2 cm with
standard 50 pounds of traction

5. Concomitant procedures such as MFX and iliopsoas lengthening will be included