The Viability of Short Stems in Total Hip Arthroplasty
Phase: NA
Conditions: Osteoarthritis of Hip
Sponsor: Northwestern University

 
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THE VIABILITY OF SHORT STEMS IN TOTAL HIP ARTHROPLASTY 
 
 
PRINCIPAL INVESTIGATOR:  
David Manning, MD 
                                                                        Department of Orthopaedic Surgery 
                                                                        676 N. St. Clair, Suite 1350 
                                                                        Chicago, IL 60611 
 
 
SUB-INVESTIGATORS: 
Farhad Yazdi 
 
Rosalind Franklin University  
 
 
Hasham Alvi, MD 
 
Northwestern University 
 
 
 
Rachel Mednick, MD 
 
Northwestern University 
 
 
Linda Suleiman, MD 
 
Northwestern University 
 
 
 
 
 
 
 
 
 
 
 
 

 
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Synopsis 
 
Title 
The Viability of Short Stems in Total Hip Arthroplasty 
Short Title 
Short Stems Study 
Protocol Date 
05/11/2015 
Study Duration 
3-3.5 years 
Study Center(s) 
Northwestern Memorial Hospital (NMH), Northwestern Memorial 
Faculty Foundation (NMFF) 
Objectives 
To determine the viability of short stems in THA 
Number of Subjects 
75 
Diagnosis and Main 
Inclusion Criteria 
Patients requiring total hip arthroplasty 

 
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TABLE OF CONTENTS 
 
 
Synopsis ...........................................................................................................................................2 
 
1.0  Introduction .............................................................................................................................4 
 
2.0  Study Objectives......................................................................................................................5 
 
3.0  Selection of Subjects ...............................................................................................................5 
3.1  Inclusion Criteria ...................................................................................................................5 
3.2  Exclusion Criteria ..................................................................................................................5 
 
4.0  Subject Registration ................................................................................................................5 
 
5.0  Study Design & Methods ........................................................................................................5 
 
6.0  Statistical Plan .........................................................................................................................5 
 
7.0  Data Collection & Record Keeping .......................................................................................6 
 
8.0  References ............................................................................................................................7, 8 
 
Appendices ......................................................................................................................................9 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
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1.0 
INTRODUCTION - BACKGROUND AND RATIONALE  
Porous-coated cementless stems were introduced in the late 1970s, in response to the high 
incidence of aseptic loosening associated with cemented stems (Judet et al 1978, 
Kavanagh et al 1989, Lord 1982, Stauffer 1982).  The stem’s porous surface achieves 
fixation via bony ingrowth at the endosteum (Engh et al 1987).  In an effort to mimic the 
femur’s natural stress distribution, many designs preferentially load the metaphysis (Joshi 
et al 2000).  One such design is the proximally coated titanium tapered wedge, which is 
widely used today (Pitto et al 2010).  Because loading is primarily dictated by bony 
ingrowth, the proximal porous coating avoids fixation at the diaphysis.  The flat, tapered 
geometry reduces stiffness compared to cylindrical stems, thereby propagating stress to 
the proximal femur, rather than down the stem’s axis (Engh et al 1987, Harvey et al 
1999), (Boehm 1998). Further contributing to decreased stiffness is titanium’s low elastic 
modulus, relative to that of cobalt-chromium (Harvey et al 1999, Mulliken et al 1996).  
Some contend the need for distal fixation in Dorr type C hips due to thin cortical bone at 
the metaphysis; however, proximally engaging stems have been shown to perform well in 
these patients (Kelly et al 2007, Reitman et al 2003). 
 
 
If a stem’s objective is to load proximally, then perhaps it need not extend into the 
diaphyseal canal.  The emergence of short stems has initiated an alternative means of 
proximal loading, without the disruption of diaphyseal bone stock.  The smaller incisions 
involved with short stem total hip arthroplasty (THA) reduce damage to muscle and soft 
tissue (Molli et al 2012).  This enables a faster, more complete recovery for the patient, as 
well as a cosmetically superior result (Sherry et al 2003).  Additionally, the preservation 
of bioavailable bone can be advantageous if a revision surgery is required (Toth et al 
2010).  Because short stems do not extend into the diaphysis, issues regarding proximal-
distal mismatch of the femur are avoided (Patel et al 2013).  This eases implantation and 
reduces the risk of intraoperative fracture (Azzam et al 2010, Cooper & Rodriguez 2010). 
The risk of intraoperative fracture is further mitigated because short stem THA does not 
require the use of reamers (Molli et al 2012, Scott et al 1975, Taylor et al 1978). 
 
Although the standard-length proximally coated titanium tapered wedge has a successful 
long-term track record, its design leaves room for improvement (Mallory et al 2001, 
Marshall et al 2004).  Standard length stems cause stress-shielding in Gruen zones 1 and 
7, suggesting that the diaphyseal portion of a stem may interfere with proximal loading 
(Gibbons et al 2001, Schmidt et al 2004).  Even proximally coated flat tapered stems are 
subject to diaphyseal loading (Cooper et al 2011).  The Accolade stem has been 
associated with significant early subsidence, especially in males with Dorr type A hips 
(Jacobs & Christensen 2009).  This suggests that the stem may wedge distally, thereby 
interfering with osseointegration (White et al 2012).  By achieving a purely metaphyseal 
fit, short stems can prevent excessive bone loss secondary to stress shielding (Gustke 
2012). We believe short stems are an equally effective alternative to traditional tapered 
stems in THA; however, long-term studies are essential to proving their efficacy. 
 
Long-term studies of short stems are lacking in current literature.  With respect to initial 
stability and bony ingrowth, short-term data is promising; however, there is still potential 

 
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for late aseptic failure (Capello et al 2009, Kroell et al 2009, Morales de Cano et al 2013, 
Schmidutz et al 2012).  By conducting a single blinded, prospective, randomized 
investigation of two stems of varying length with equal metallurgy, coating, and proximal 
geometry, we can identify the effects of stem length on long-term outcomes. 
 
2.0 
OBJECTIVES 
The goal of this study is to determine the viability of short femoral stems as an alternative 
to standard-length stems in total hip arthroplasty. 
 
3.0 
SELECTION OF SUBJECTS 
 
3.1 
INCLUSION CRITERIA  
 Must require a total hip arthroplasty.  
 Ages 18-85 years, regardless of gender, ethnicity, or pathology 
 
3.2 
EXCLUSION CRITERIA 
 This study excludes any populations at risk.   
 Minors, as well as any persons unable to consent, will not be eligible. 
 
4.0 
SUBJECT REGISTRATION  
The subjects will be recruited by the PI and co-investigator at the orthopaedic surgery 
clinic in 675 N. St. Clair, Galter 17-100. The study will be reviewed with the subjects and 
they will be consented by the PI, co-investigator, or other authorized study staff. 
 
5.0       STUDY DESIGN & METHODS 
50 patients will be recruited over 12-18 months.  Half of the patients will receive the 
Taperloc Microplasty short femoral stem, while the other half will receive the standard-
length Taperloc stem.  Patients will be randomized in the operating room through the 
opening of opaque, study-numbered envelopes during preparation of the femur.  
Immediate weight bearing will be allowed post-operatively.  Patient-reported outcomes, 
as well as x-ray analysis, will be administered immediately post-operatively, 6 weeks 
post-operatively, 3 months post-operatively, 6 months post-operatively, 12 months post-
operatively, and 2 years post-operatively.  X-ray analysis includes antero-posterior pelvis, 
and lateral hip radiographs.  The X-rays will be sent to Dr. Rainer Biedermann at the 
University of Innbruck, Austria for analyses using the EBRA-FCA software. Patient-
reported outcomes will be measured using the Harris Hip and SF-36 questionnaires. 
 
Procedures such as X-rays will be used during this research study to see how the patient is 
doing. The cumulative radiation exposure from these tests is considered small and is not 
likely to adversely affect the patient or their disease. However, the effects of radiation add 
up over a lifetime.  It is possible that having several of these tests may add to the patient’s 
risk of injury or disease. When deciding to enter this study, the patient should about your 
past and future contact with radiation. Examples of contact with radiation include x-rays 
taken for any reason or radiation therapy for cancer treatment.  
 
There are no other known risks involved in this study, aside from the minor 
inconvenience of completing questionnaires. One possible risk related with the patient’s 

 
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participation in this study is the loss of privacy. To reduce these risks, all of the 
information collected will be de-identified (the patient will be assigned a study number 
and all data will be linked to that number and not the patient’s name) and stored in a 
password protected file on a password protected computer. Some of the questions asked 
may be upsetting, or the patient may feel uncomfortable answering them. If the patient 
does not wish to answer a question, they may skip it and go to the next question.  
 
Additionally, both stems used in this study are standard surgical stems used by 
orthopaedic surgeons. Therefore, there are no additional risks involved in the use of these 
stems for this study. 
 
6.0       STATISTICAL PLAN  
This sample size is small enough to feasibly recruit over the given time period, yet large 
enough to correlate differences between the two groups.  Antero-posterior pelvis and 
lateral hip radiographs will show patterns of stress-shielding, and the EBRA-FCA method 
provides a non-invasive means of measuring the extent of implant migration (if any).  
Patient-reported outcomes will be used to determine the effect of each implant on the 
patients’ daily lives.  Routine follow-up over 2 years is necessary to determine the long-
term impact of each implant. 
 
7.0 
DATA COLLECTION & RECORD KEEPING 
All information regarding the nature of the proposed investigation provided to the 
investigator (with the exception of information required by law or regulations to be 
disclosed to the IRB, the subject, or the appropriate regulatory authority) will be kept in 
confidence by the principal investigator. All personal information will be treated as 
strictly confidential and not made publicly available.  All records are stored in a locked 
filling cabinet and password protected computers which are accessed only by the 
Principal Investigator and Study Coordinators. All identifiable data will be destroyed a 
year after the study is complete. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
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8.0 
REFERENCES 
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HE, 2nd ed, The Adult Hip, Volume 2, Lippincott-Raven Publishers, Philadelphia, p. 1497. 
Capello WN, D'Antonio JA, Geesink RG, Feinberg JR, Naughton M. 2009. Late remodeling 
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Cooper HJ, Jacob AP, Rodriguez JA. 2011. Distal fixation of proximally coated tapered stems 
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Cooper HJ, Rodriguez JA. 2010. Early Post-operative Periprosthetic Femur Fracture in the 
Presence of a Non-cemented Tapered Wedge Femoral Stem. HSS journal : the 
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Engh CA, Bobyn JD, Glassman AH. 1987. Porous-coated hip replacement. The factors 
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Gibbons CE, Davies AJ, Amis AA, Olearnik H, Parker BC, Scott JE. 2001. Periprosthetic bone 
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Gustke K. 2012. Short stems for total hip arthroplasty: initial experience with the Fitmore stem. 
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