Comparing Collared and Collarless Femoral Stems in Total Hip Arthroplasty
Phase: NA
Conditions: Primary Total Hip Arthroplasty
Sponsor: Medstar Health Research Institute

PROTOCOL TITLE: Comparison of clinical and radiographic results of collared and 
collarless femoral stems in total hip arthroplasty 
MOD00024127 
 
Page 1 of 18 
Revised: November 12, 2025IRB Approved 
12/18/2025 - 11/3/2026 
PROTOCOL TITLE: 
Comparison of clinical and radiographic results of collared and collarless femoral 
stems in total hip arthroplasty 
PRINCIPAL INVESTIGATOR: 
Brett Levine, MD, MS, FAOA 
Orthopaedic Surgery, MedStar Georgetown University Hospital 
202-444-8766 
Brett.R.Levine@medstar.net 
CO-INVESTIGATOR/SUB-INVESTIGATOR/STAFF: 
Mark T. Yamamoto 
Georgetown University School of Medicine 
424-535-9634 
mty11@georgetown.edu 
VERSION NUMBER/DATE: 
V1 07/10/2025 
V2 10/16/2025 
V3 11/12/2025 
REVISION HISTORY 
Revisio 
n # 
Version Date 
Summary of Changes 
Consent 
Change? 
1 
10/16/2025 
Added device and 510(k) information 
No 
2 
11/12/2025 
Added risk of randomization 
Yes 
3 
12/10/2025 
Included option for electronic consent with 
Interlace 
Yes 
 
 
 
 
 
 
 
 
Table of Contents 
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PROTOCOL TITLE: Comparison of clinical and radiographic results of collared and 
collarless femoral stems in total hip arthroplasty 
MOD00024127 
 
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1.0 
Study Summary 
Study Title 
Comparison of clinical and radiographic results of collared 
and collarless femoral stems in total hip arthroplasty 
Study Design 
Randomized controlled trial 
Primary Objective 
SA1: Prospectively assess clinical outcomes in patients 
undergoing primary total hip arthroplasty with a collared 
versus collarless femoral stem of the same design. 
 Secondary  
Objective(s) 
SA2: Evaluate serial radiographs to quantify differences in 
subsidence between collared and collarless implant groups. 
SA3: Report and compare incidence rates of intraoperative 
and postoperative periprosthetic fractures and aseptic 
loosening following primary total hip arthroplasty with use 
of either a collared or collarless stem. 
Research  
Intervention(s)/  
Investigational  
Agent(s)  
N/A 
IND/IDE #  
N/A 
Study Population 
Adults (≥18 years) undergoing primary total hip arthroplasty 
with use of collared or collarless femoral stem. 

PROTOCOL TITLE: Comparison of clinical and radiographic results of collared and 
collarless femoral stems in total hip arthroplasty 
MOD00024127 
 
Page 3 of 18 
Revised: November 12, 2025IRB Approved 
12/18/2025 - 11/3/2026 
Sample Size 
100 
Study Duration for  
individual 
participants 
Preoperative consent to completions of postoperative 
followup (up to 1 year per patient) 
Study Specific  
Abbreviations/  
Definitions  
THA – Total Hip Arthroplasty 
PPF  – Periprosthetic Fracture 
2.0 
Objectives* 
SA1: Prospectively assess clinical outcomes in patients undergoing primary total 
hip arthroplasty with a collared versus collarless femoral stem of the same design. 
SA2: Evaluate serial radiographs to quantify differences in subsidence between 
collared and collarless implant groups. 
SA3: Report and compare incidence rates of intraoperative and postoperative 
periprosthetic fractures and aseptic loosening following primary total hip 
arthroplasty with use of either a collared or collarless stem. 
Hypothesis: The addition of a collar to the same designed triple-taper primary hip 
stem will lead to a reduction in subsidence and incidence of perioperative and 
periprosthetic femur fractures. 
3.0 
Background* 
Total hip arthroplasty (THA) is a widely successful and common orthopedic 
intervention used to replace damaged hip joints with artificial components; 
however, femoral component-related complications such as early subsidence, 
aseptic loosening, and periprosthetic femoral fractures (PPFs) continue to 
challenge long-term outcomes. Recent attention has focused on femoral stem 
design modifications—particularly the addition of a collar—to enhance primary 
stability and reduce the risk of early failure. The rationale for collar usage lies in 
its theoretical ability to provide mechanical support at the calcar, thereby 
preventing stem migration and improving load transfer in uncemented femoral 
stems. 
The release of the ACTIS Hip Stem (DePuy Synthes, 2018) has contributed to a 
resurgence in the use of collared stems, prompting renewed clinical inquiry into 
their comparative performance. Despite encouraging early results, the current 
evidence remains incomplete. Notably, most data derive from retrospective series 
or registry-based analyses, which are inherently subject to selection bias and 
inconsistent reporting standards, particularly concerning intraoperative PPFs and 
stem revisions. Additionally, DePuy Synthes has recently released the exact same 
stem without a collar for similar use in primary THA. 

PROTOCOL TITLE: Comparison of clinical and radiographic results of collared and 
collarless femoral stems in total hip arthroplasty 
MOD00024127 
 
Page 4 of 18 
Revised: November 12, 2025IRB Approved 
12/18/2025 - 11/3/2026 
Recent studies suggest that collared stems may indeed reduce the incidence of 
PPFs. Favroul et al. observed a significantly lower 90-day PPF rate in the collared 
stem group (0.4%) compared to the collarless group (1.6%) in a cohort of 1,623 
THAs (p = 0.048). Aseptic loosening, a leading cause of THA failure, may also be 
mitigated by the use of a collared design. In a Swiss National Joint Registry study 
of over 30,000 THAs, collared Corail™ stems had a significantly lower revision 
rate for aseptic loosening (0.47%) than collarless stems (0.73%; p = 0.022). 
Perhaps most compelling is the growing body of evidence linking collared stems 
to reduced femoral stem subsidence—an early indicator of mechanical instability 
and a predictor of later aseptic loosening. A randomized controlled trial using 
radiostereometric analysis (RSA) found that collared stems exhibited significantly 
less subsidence than collarless stems at two weeks postoperatively (mean 
difference 2.23 mm; p = 0.023), although the difference diminished by one year. 
Additional studies using non-invasive EBRA (Ein-Bild-Röntgen-Analyse) 
confirm that collared stems consistently demonstrate lower average subsidence 
over 6 to 18 months. 
Despite promising preliminary data, several gaps in the literature persist. For 
example, intraoperative PPFs are typically treated intraoperatively and may lead 
to a change in the femoral component type that is utilized. Oftenly, this is not 
captured in retrospective reviews or during chart assessment even with 
prospectively collected data. Such arguments support the necessity of a 
controlled, prospective study directly comparing collared and collarless stems 
with standardized measurement of femoral stem subsidence and documentation of 
associated complications such as aseptic loosening and PPF. Furthermore, the 
clinical significance of early migration differences observed with various imaging 
modalities has not been fully elucidated, nor has their correlation with long-term 
outcomes been firmly established. 
This proposed randomized controlled trial seeks to address these gaps by 
comparing the clinical and radiographic outcomes of collared versus collarless 
femoral stems in THA, using femoral stem subsidence as the primary endpoint 
and incidence rates of PPF, aseptic loosening, and PROMs as key secondary 
endpoints. By employing standardized radiographic measurements and robust 
follow-up, this study will offer high-quality evidence to inform implant selection 
and optimize surgical outcomes. It will also contribute to the development of 
clinically relevant thresholds for subsidence that can serve as early predictors of 
implant failure. 
References:  
1) Nerys-Figueroa, J., Parsa, A., Curley, A., Charif, S., Domb, B. G., & Schinsky, M. 
F. (2024). Slightly reduced early subsidence with similar outcomes and 
complications rate in collared stems - A systematic review of randomized clinical 
trials. Journal of orthopaedics, 50, 170–176.  
https://doi.org/10.1016/j.jor.2024.01.013 

PROTOCOL TITLE: Comparison of clinical and radiographic results of collared and 
collarless femoral stems in total hip arthroplasty 
MOD00024127 
 
Page 5 of 18 
Revised: November 12, 2025IRB Approved 
12/18/2025 - 11/3/2026 
2) Favroul, C., Voirin, F., Foissey, C., Batailler, C., & Lustig, S. (2025). A collar is a 
protective factor against early periprosthetic fracture for cementless stems in total 
hip arthroplasty : a multivariate analysis in a single-centre cohort of 1,623 total 
hip arthroplasties. The bone & joint journal, 107-B(5 Supple A), 70–75. 
https://doi.org/10.1302/0301-620X.107B5.BJJ-2024-1104.R2 
3) Ricotti, R. G., Flevas, D. A., Sokrab, R., Vigdorchik, J. M., Mayman, D. J., 
Jerabek, S. A., Sculco, T. P., & Sculco, P. K. (2024). Changing practice to a 
newgeneration triple-taper collared femoral component reduces periprosthetic 
fracture rates after primary total hip arthroplasty. The bone & joint journal, 106-
B(3  
Supple A), 115–120. https://doi.org/10.1302/0301-620X.106B3.BJJ-20230846.R1 
4) Kelly, M., Chen, A. F., Ryan, S. P., Working, Z. M., De, A., Mullen, K., Porter, K. 
R., & Kagan, R. (2024). Femoral Component Design Is Associated With the Risk 
of Periprosthetic Femur Fracture After Cementless THA in Patients 65 Years or 
Older. Clinical orthopaedics and related research, 482(8), 1485–1493.  
https://doi.org/10.1097/CORR.0000000000002985 
5) Hamoudi, C., Debordes, P. A., Fils, J. F., Eberlova, L., Husmann, O., Fischer, J.  
F., & Lunebourg, A. (2025). Outcomes of collared uncemented stems in total hip 
arthroplasty for primary osteoarthritis: A Swiss National joint registry analysis. 
Orthopaedics & traumatology, surgery & research : OTSR, 104293. Advance 
online publication. https://doi.org/10.1016/j.otsr.2025.104293 
6) Perelgut, M. E., Polus, J. S., Lanting, B. A., & Teeter, M. G. (2020). The effect of 
femoral stem collar on implant migration and clinical outcomes following direct 
anterior approach total hip arthroplasty. The bone & joint journal, 102-B(12),  
1654–1661. https://doi.org/10.1302/0301-620X.102B12.BJJ-2019-1428.R1 
7) Dammerer, D., Blum, P., Putzer, D., Krappinger, D., Pabinger, C., Liebensteiner, 
M. C., & Thaler, M. (2022). Migration characteristics of the Corail 
hydroxyapatite-coated femoral stem-a retrospective clinical evaluation and 
migration measurement with EBRA. Archives of orthopaedic and trauma surgery,  
142(3), 517–524. https://doi.org/10.1007/s00402-021-03926-9 
8) Ries, C., Boese, C. K., Dietrich, F., Miehlke, W., & Heisel, C. (2019). Femoral 
stem subsidence in cementless total hip arthroplasty: a retrospective single-centre 
study. International orthopaedics, 43(2), 307–314. 
https://doi.org/10.1007/s00264018-4020-x 
4.0 
Study Endpoints* 
Study Endpoints 
● Primary: Measurement of femoral stem subsidence at 6 weeks, 6 months, 
and 1-year post-operation 

PROTOCOL TITLE: Comparison of clinical and radiographic results of collared and 
collarless femoral stems in total hip arthroplasty 
MOD00024127 
 
Page 6 of 18 
Revised: November 12, 2025IRB Approved 
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● Secondary: Incidence rates of periprosthetic fractures, incidence rates of 
aseptic loosening, and patient-reported outcome measures (PROMs)– 
collected in OBERD. 
Safety Endpoints – N/A 
5.0 
Study Intervention/Investigational Agent - N/A 
 
Applicable to: 
FDA Regulation 
IND Studies 
IDE studies 
Abbreviated 
IDE studies 
21 CFR 11 
X 
X 
 
21 CFR 54 
X 
X 
 
21 CFR 210 
X 
 
 
21 CFR 211 
X 
 
 
21 CFR 312 
X 
 
 
21 CFR 812 
 
X 
X 
21 CFR 820 
 
X 
 
The collared and collarless femoral stem implants that will be used in this study 
are FDA-approved for standard use in primary THA. The 510(k) number for the 
collared hip stem is K150862 and for the collarless version is K21058. Thus, both 
hip prosthetics are not HUDs and do not have IDE or HDE numbers. No other 
investigational drugs or devices will be administered. 
6.0 
Procedures Involved* 
This study is a prospective, randomized controlled trial comparing the clinical and 
radiographic outcomes of a collared versus collarless femoral stems of the same 
design in primary THA. A total of 100 participants undergoing elective, 
uncemented primary THA for degenerative hip disease will be enrolled. 
Participants will be randomized in a 1:1 ratio to receive either a collared femoral 
stem or a collarless femoral stem. All patients indicated for a cementless primary 
total hip arthroplasty will be offered enrollment. Once consented, they will be 
randomized into the collared or collarless stem groups. Study participants will be 
informed about the risk of randomization due to removing the elements of choice 
from the clinician, as outlined in the informed consent form. 

PROTOCOL TITLE: Comparison of clinical and radiographic results of collared and 
collarless femoral stems in total hip arthroplasty 
MOD00024127 
 
Page 7 of 18 
Revised: November 12, 2025IRB Approved 
12/18/2025 - 11/3/2026 
The primary endpoint is femoral stem subsidence, measured at postoperative 
6week, 6-month, and 1-year clinical visits, which coincide with standard of care 
routine follow-up. Secondary endpoints include the incidence of PPF and aseptic 
stem loosening within the first postoperative year. Again, all research procedures 
are designed to align with standard perioperative and postoperative care for THA, 
minimizing burden for study participants. Additionally, the ACTIS Hip Stem 
(DePuy Synthes, Warsaw, IN) is routinely used by the participating surgeons for 
the last 3-4 years. The following outlines the specific protocol steps and time 
points: 
Preoperative (Day -30 to 0): 
● Obtain written informed consent either in person or via Interlace. 
● Confirm eligibility criteria (inclusion/exclusion). 
● Record baseline demographic data, diagnosis, and Dorr classification (from preop 
imaging). 
● Randomization and group assignment. 
Operative Day (Day 0): 
● THA performed using the allocated femoral stem type (collared or collarless), via 
a standard surgical approach. 
● Per standard practice, intraoperative documentation of any complications, 
including intraoperative PPFs, will be recorded by the surgical team. 
Postoperative Follow-Up: 
● Routine anterior-posterior (AP) pelvic and lateral hip X-rays will be obtained at 6 
weeks, 6 months, and 1 year. 
● Subsidence will be quantified using standardized radiographic measurement 
techniques. Typically, radiographs are obtained at 6 weeks, 6 months and annually 
thereafter. Calibration will be performed with the known femoral head size and 
subsidence measured by standard techniques on these serial radiographs. 
Adverse Event Monitoring (Ongoing): 
● Any PPFs or aseptic loosening will be identified through clinical assessment, 
imaging review, and/or surgical reports, and reported by trained investigators or 
study staff. 
● Participants will be advised to report any fall or unusual hip symptoms. Any 
clinically indicated imaging or intervention will be reviewed for endpoint 
classification. 
Risk Minimization: 
● All surgeries will be conducted by experienced orthopaedic surgeons within the 
MedStar Health System (MedStar Georgetown University Hospital and MedStar 
Washington Hospital Center) to minimize procedural variability. 

PROTOCOL TITLE: Comparison of clinical and radiographic results of collared and 
collarless femoral stems in total hip arthroplasty 
MOD00024127 
 
Page 8 of 18 
Revised: November 12, 2025IRB Approved 
12/18/2025 - 11/3/2026 
● Standard sterile technique and perioperative protocols will be followed. 
● Follow-up visits coincide with routine care to minimize patient burden. 
● Radiographic measurements will be conducted by independent reviewers to 
reduce measurement error and bias. 
● There is no additional physical risk to participating in this study beyond standard 
of care. 
● The primary risk is a potential breach of confidentiality. To minimize this risk, all 
data will be de-identified and stored on password-protected, HIPAA-compliant 
platforms. Participants will be assigned a unique study ID (SID), and any linkage 
to identifiable information (e.g., MRN) will be stored separately in a secured, 
password-protected file. No patient names or identifiers will be recorded on any 
data collection forms. 
● Study participants will be made aware about the risk of randomization for the 
implant they will receive. By participating in the study, the surgeons will not be 
able to choose the implant. 
Devices Used: 
● Collared and collarless femoral stems, both commercially available and 
FDAcleared for primary THA use–the ACTIS Hip Stem that comes in both a 
collared and collarless variation, will be used. 
● Both stem types are used in current clinical practice and do not represent 
investigational use. 
Source Records: 
● Source documentation will include: 
o Electronic medical records (EMR) o Operative reports o Imaging records 
(X-rays) o Clinic visit notes 
o Patient-reported outcome forms–collected in OBERD, the standard 
platform at MedStar for collecting PROMs 
Data Collected: 
● Demographics and clinical variables: age, sex, BMI, comorbidities, Dorr 
classification. 
● Operative data: stem type, surgical approach, intraoperative complications. 
● Primary endpoint: femoral stem subsidence at 6 weeks, 6 months, and 1 year, 
measured in millimeters from standardized serial radiographs. 
● Secondary endpoints: 
o PPF incidence (confirmed radiographically or operatively). 
o Aseptic loosening (evidenced by radiolucent lines, implant migration, or 
revision surgery). 
● Other outcomes: functional scores (PROMs), adverse events, and reoperation 
rates. 

PROTOCOL TITLE: Comparison of clinical and radiographic results of collared and 
collarless femoral stems in total hip arthroplasty 
MOD00024127 
 
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Data Collection Methods: 
● Radiographic analysis performed by independent reviewers blinded to group 
allocation. 
● Adverse events recorded by research staff at each visit and during any interim 
visits. 
Long-Term Follow-Up —  Patients will follow standard protocol for follow-up, 
offering the possibility of more longitudinal reporting potentially 5-10 years 
postop.  
Humanitarian Use Device (HUD) — N/A 
This study does not involve any HUDs. All devices used (collared and collarless 
femoral stems) are FDA-approved for standard use in primary THA and do not 
require an Investigational Device Exemption (IDE). The 510(k) number for the 
collared hip stem is K150862 and for the collarless version is K21058.  
7.0 
Data and Specimen Banking – N/A 
This study does not involve the banking of specimens or long-term data storage 
for future unrelated research. 
8.0 
Sharing of Results with Subjects* 
Study results relating to the participant’s individual subsidence measurements or 
clinical outcomes may be shared at their discretion. This will be done privately 
and confidentially; results of any other participants will not be shared. 
9.0 
Study Timelines* 
Each participant will be involved in the study for approximately 1 year, from the 
time of surgery through standard postoperative care. Data will be collected at 
preop, 6 weeks, 6 months, and 1-year post-op, coinciding with already scheduled 
clinic visits. The anticipated amount of time to enroll all subjects is 1 year, with 
the total duration of the project estimated to be 2 years.  
10.0 Inclusion and Exclusion Criteria* 
Potential participants will be identified from the MedStar Orthopaedic Surgery 
clinics at MGUH and MWHC. Screening will occur during routine preoperative 
consultation visits for patients scheduled to undergo primary, uncemented THA 
due to osteoarthritis or other non-inflammatory degenerative joint disease. 
Patients will be screened by the study investigator or trained research coordinator. 
Screening will involve review of the EMR for clinical and radiographic eligibility, 

PROTOCOL TITLE: Comparison of clinical and radiographic results of collared and 
collarless femoral stems in total hip arthroplasty 
MOD00024127 
 
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verification of surgical plan, preoperative radiographic assessment, and 
assessment of patient capacity to provide informed consent. Patients who meet all 
inclusion criteria and none of the exclusion criteria will be approached for 
informed consent and formally enrolled after confirming eligibility. 
Inclusion Criteria: 
● Adults (≥ 18 years old) scheduled for primary, uncemented THA using a 
cementless femoral stem. 
● Diagnosis of primary osteoarthritis or other non-inflammatory degenerative joint 
disease. 
● Ability and willingness to comply with study procedures and follow-up schedule. 
● Ability to provide written informed consent. 
Exclusion Criteria: 

PROTOCOL TITLE: Comparison of clinical and radiographic results of collared and 
collarless femoral stems in total hip arthroplasty 
● 
MOD00024127 
 
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Patients not indicated for a cementless THA. 
● Prior surgery on the ipsilateral hip (e.g., prior THA, internal fixation, osteotomy). 
● Use of cemented or hybrid femoral components. 
● Revision THA or conversion THA. 
● Active or prior infection of the hip joint. 
● Severe osteoporosis (T-score ≤ −2.5) or known metabolic bone disease. 
● Inability to complete follow-up or anticipated relocation out of the area. 
Special Populations: 
The following special populations will be excluded from participation in this 
study: adults unable to provide consent, anyone under the age of 18, and pregnant 
women. 
11.0 Vulnerable Populations* - N/A 
12.0 Local Number of Subjects 
For this study we aim to enroll 100 participants (50 per group) undergoing 
primary, cementless THA across two MedStar sites, MedStar Georgetown 
University Hospital and MedStar Washington Hospital Center. All participants 
will be screened at the time of surgical scheduling and enrolled if they meet the 
criteria and consent to participate. This target number of 100 participants accounts 
for any dropouts throughout the study. Based on our power calculation (assuming 
80% power, significance of 0.05, and a SD of 0.45 mm based on prior studies), a 
sample size of at least 20 subjects per group (40 in total) would be needed to 
complete the research procedures. 
13.0 Recruitment Methods 
Recruitment will occur during standard preoperative clinic visits at the 
Department of Orthopedic Surgery at MGUH and MWHC. Potential subjects will 
be identified weekly by IRB-approved research staff by screening cinic 
appointments. Patients scheduled for primary, uncemented THA will be 
approached during these visits. Recruitment will begin after IRB approval and 
continue until the target enrollment of 100 participants is reached. Each potential 
participant will be approached in-person by a study investigator or trained 
research coordinator prior to surgery, typically 2–4 weeks in advance. 
The study will be described in detail, and eligible patients will be provided with a 
written informed consent form and ample time to ask questions. If interested, they 
may sign the consent form at that time or take it home and return it during a 
subsequent visit. Patients may also choose to complete an electronic consent form 

PROTOCOL TITLE: Comparison of clinical and radiographic results of collared and 
collarless femoral stems in total hip arthroplasty 
MOD00024127 
 
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that can be sent to their emails through a secure MedStar consenting platform, 
Interlace. 
All subjects will be under the routine clinical care of orthopaedic providers at the 
study institution and will be recruited without deviation from the standard clinical 
pathway for surgical planning and follow-up. Recruitment will occur entirely 
through face-to-face interaction during clinic visits, with no use of public 
advertisements, social media, or media broadcast. No posters or flyers regarding 
the study will be distributed.  
No monetary compensation will be provided to participants for their involvement 
in this study. 
14.0 Withdrawal of Subjects* 
A subject may choose to withdraw from the study at any time. Withdrawal of a 
subject will have no effect on their clinical care or clinical decision making. 
Subjects may also be withdrawn from the study without their consent under the 
following circumstances: 
● Intraoperative change in surgical plan, such as conversion to a cemented or hybrid 
femoral stem, revision THA, or significant intraoperative complications rendering 
the assigned study implant unusable. 
● Failure to attend postoperative follow-up appointments necessary for primary or 
secondary outcome data collection. 
● Medical conditions or complications (e.g., infection, stroke, malignancy) that 
significantly impact the participant’s ability to safely continue study participation 
or follow the protocol. 
● Protocol violation identified by the research team that invalidates study 
participation (e.g., unintentional enrollment of an ineligible subject). 
In all such cases, the reason for withdrawal will be documented in the subject’s 
research file and medical record. 
15.0 Risks to Subjects* 
Since this study aligns with standard of care for THA procedures, and no 
investigational devices or additional interventions are introduced beyond routine 
care, participation in the research carries minimal risk. However, the following 
potential risks and inconveniences apply: 
Physical Risks: 
● Radiation exposure from X-rays: Although all imaging is part of routine clinical 
follow-up and not performed solely for research purposes, participants will 

PROTOCOL TITLE: Comparison of clinical and radiographic results of collared and 
collarless femoral stems in total hip arthroplasty 
● 
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undergo three radiographic evaluations (6 weeks, 6 months, and 1 year). The 
radiation dose is low and well within accepted clinical safety standards. 
Standard surgical risks: These include pain, infection, dislocation, periprosthetic 
fracture, implant loosening, nerve or vascular injury, and deep vein thrombosis 
(DVT). However, these risks are inherent to any THA procedure and are not 
elevated by study participation. 
● Increased awareness of complications: Participation may involve increased 
attention to postoperative outcomes, which could potentially lead to increased 
anxiety regarding complications. 
● Risk of randomization: This study removes the elements of choice from the 
practicing surgeon. Currently, there is no definitive data based on prospective 
studies that suggests that one is better than the other. While improvement of 
symptoms is expected for both implants for all patients, there may be general 
differences in the clinical and radiographic results between the two. 
Psychological and Social Risks: 
● There are no direct psychological risks anticipated, but some participants may 
experience mild anxiety related to study participation, data monitoring, or 
followup imaging results. 
● Privacy risks are minimal due to the use of secure, HIPAA-compliant data 
systems and appropriate de-identification of research data. 
16.0 Potential Benefits to Subjects* 
There is no guaranteed direct benefit to participants for taking part in this research 
study. The primary goal of this study is to generate knowledge that may improve 
care for future patients undergoing THA. While this research study is designed 
primarily to gather knowledge on the comparative outcomes of collared versus 
collarless femoral stems in total hip arthroplasty (THA), there may be limited, 
indirect benefits to individual participants. These potential benefits include: 
● Increased clinical oversight: Study participants may experience enhanced 
monitoring through standardized radiographic follow-up and evaluation by trained 
research staff, which could aid in early identification of implant-related 
complications. 
● Educational benefit: Participants may gain a greater understanding of their 
surgical procedure and postoperative course through discussions with the study 
team. 

PROTOCOL TITLE: Comparison of clinical and radiographic results of collared and 
collarless femoral stems in total hip arthroplasty 
MOD00024127 
 
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17.0 Data Management* and Confidentiality 
Femoral stem subsidence will be the primary outcome, measured in millimeters at 
6 weeks, 6 months, and 1 year postoperatively. Differences in mean subsidence 
between the collared and collarless groups will be assessed using independent 
samples t-tests or nonparametric alternatives if assumptions of normality are not 
met. Incidence of PPF and aseptic loosening will be compared using chi-square 
tests or Fisher’s exact tests. Logistic regression or Cox proportional hazards 
modeling will be used to adjust for covariates such as age, BMI, Dorr 
classification, and surgical approach if sample size allows. A sample size of 20 
participants per group (40 total) provides 80% power to detect a difference of 0.4 
mm in mean stem subsidence, assuming a standard deviation of 0.45 mm (based 
on prior RSA-based studies), with α = 0.05. A proposed target enrollment of 100 
participants is set to account for unforeseen dropouts. 
All study team members will be trained in HIPAA compliance and Good Clinical 
Practice (GCP). Electronic data will be stored in a secure, password-protected, 
encrypted research database hosted on institutional servers. Subject identifiers 
(e.g., name, MRN) will be stored separately from study data and linked only via a 
unique coded identifier. Transmission of data between team members or 
collaborators will occur via encrypted institutional email or secure file-sharing 
platforms. No data will be shared externally without IRB and institutional 
approval. 
Information Included: 
● Demographic data, medical history, surgical details, implant type, radiographic 
images and measurements, and clinical outcomes (e.g., fracture, loosening, 
revision surgery). 
Storage Location and Method: 
● Data will be stored on secure, password-protected, encrypted institutional servers. 
● Only authorized members of the research team listed on the IRB application will 
have access. 
● The PI will oversee access and approve any data sharing requests. 
18.0 Provisions to Monitor the Data to Ensure the Safety of Subjects – 
N/A 
This proposed research study does not involve more than minimal risk to subjects, 
since it aligns with standard of care for THA procedures. 

PROTOCOL TITLE: Comparison of clinical and radiographic results of collared and 
collarless femoral stems in total hip arthroplasty 
● 
MOD00024127 
 
Page 15 of 18 
Revised: November 12, 2025IRB Approved 
12/18/2025 - 11/3/2026 
19.0 Provisions to Protect the Privacy Interests of Subjects 
The following steps will be taken to respect and protect the privacy interests of all 
participants: 
● Recruitment and consent discussions will occur in private clinic rooms during 
routine preoperative visits. Discussions will be conducted in a quiet, confidential 
setting to ensure that participants are comfortable and not overheard by others. 
● Personal and health-related information will be obtained only by authorized 
research staff who are trained in HIPAA and human subjects research protections. 
Subjects will be informed that their participation is entirely voluntary and that 
they may decline to answer any questions or withdraw at any time without 
affecting their care. 
● Only the minimum necessary identifiable information will be collected to achieve 
the study aims. 
● Identifiers will be removed or replaced with coded subject IDs during data 
analysis and publication to prevent disclosure of personal information. 
To help subjects feel comfortable and reduce any sense of intrusiveness during 
research interactions: 
● Study procedures are designed to align with routine clinical care, minimizing 
additional burden or deviation from normal patient experiences. 
● The research team will introduce themselves clearly, explain the purpose of the 
study, and emphasize that participation is optional and will not affect their 
surgical care or relationship with providers. 
● Written and verbal information will be provided in clear, respectful language. 
Ample time will be given for questions. 
● Subjects will be reminded that they can decline to answer any questions or stop 
participation at any time. 
● Follow-up assessments rely on clinical imaging and observations already 
performed as part of standard care, eliminating the need for sensitive questioning 
or intrusive examinations. 
The research team will access subject information through the following 
authorized and IRB-approved means: 
● MedConnect (EMR): Used to review demographic data, surgical details, imaging, 
clinical outcomes, and follow-up attendance. 
● Study-Specific Forms and Surveys: Any forms collected directly from subjects 
will be securely stored and managed by the study team. Access will be limited to 
IRB-approved personnel listed on the protocol, and all team members will be 
trained in HIPAA compliance and institutional data security protocols.  

PROTOCOL TITLE: Comparison of clinical and radiographic results of collared and 
collarless femoral stems in total hip arthroplasty 
MOD00024127 
 
Page 16 of 18 
Revised: November 12, 2025IRB Approved 
12/18/2025 - 11/3/2026 
20.0 Compensation for Research-Related Injury – N/A 
21.0 Economic Burden to Subjects – N/A 
22.0 Consent Process 
Written informed consent will be obtained from all study participants prior to 
enrollment in the research study. The consent process will take place in a private 
clinical examination room during a preoperative orthopedic clinic visit, prior to 
the subject’s scheduled THA procedure. Participants may also elect to sign 
consent forms electronically via Interlace. Participants will be given the 
opportunity to review the consent form during their clinic visit, with a minimum 
waiting period of 24 hours offered before they decide whether to participate. If a 
subject prefers, they may take the consent form home for further review and 
return at a subsequent visit to provide consent. 
At each study visit (6 weeks, 6 months, 1 year), the research staff will reaffirm the 
subject’s willingness to continue participation. Any changes to the study protocol 
or new risk information will be communicated to participants with an 
IRBapproved amended consent process if applicable. The research team will 
follow SOP: Informed Consent Process for Research (HRP-090) as required by 
the IRB and institutional policy. 
Only the PI or designated, IRB-approved study coordinators will conduct the 
consent process. Participation will be presented as completely voluntary, with 
emphasis that declining to participate will have no impact on clinical care or the 
surgeon-patient relationship. For the study we will only consent patients who 
speak English, are not cognitively impaired, and are able to provide consent on 
their own. 
23.0 Process to Document Consent in Writing 
Yes, this study will follow SOP: Written Documentation of Consent (HRP-091). 
Informed consent will be documented using an IRB-approved written consent 
form, which includes all required elements of informed consent per 45 CFR 
46.116. The consent form will be signed and dated by the participant and the 
member of the study team obtaining consent. 
Although this research study is minimal risk and aligns with standard clinical 
care, it involves allocation to different standard-of-care implants and radiographic 
assessments used to measure the primary endpoint. Therefore, written 
documentation of informed consent will not be waived. 
The study team believes that full written consent is appropriate and necessary for 
transparency and to maintain subject trust. A written consent document will be 

PROTOCOL TITLE: Comparison of clinical and radiographic results of collared and 
collarless femoral stems in total hip arthroplasty 
● 
MOD00024127 
 
Page 17 of 18 
Revised: November 12, 2025IRB Approved 
12/18/2025 - 11/3/2026 
submitted with this application using the institution's template consent document 
(HRP-502). 
24.0 HIPAA Authorization – N/A 
25.0 Setting 
All research activities will be conducted at MedStar Health-affiliated institutions 
specifically within the Department of Orthopedic Surgery at MGUH and MWHC. 
These institutions are fully equipped for conducting prospective clinical research 
involving surgical procedures and are HIPAA-compliant with IRB oversight. 
Subjects will be identified and recruited during preoperative orthopedic clinic  

PROTOCOL TITLE: Comparison of clinical and radiographic results of collared and 
collarless femoral stems in total hip arthroplasty 
MOD00024127 
 
Page 18 of 18 Revised: November 12, 2025IRB Approved 
12/18/2025 - 11/3/2026 
visits, which are part of routine care for patients scheduled to undergo primary 
uncemented THA. 
26.0 Resources Available 
We anticipate screening approximately 100 patients in order to enroll at least 50 
participants in adherence to our power calculation. MGUH and MWHC sees an 
ample number of patients for THA that should allow us to reach our target 
number within the stated timeframe (approximately 1 year). The total allotted 
timeframe we are devoting to conducting and completing this research is 2 years. 
Additional research members can be recruited as needed from the Georgetown 
School of Medicine and will be updated to the IRB. 
27.0 Multi-Site Research – N/A