Anderson Orthopaedic Research Institute

Excellence in Research Through the Decades

Our Research


“As a surgeon-scientist, I enjoy the study of hip and knee replacements. I enjoy research because it allows me to study what I produce and makes me critically think about ways I can improve hip and knee replacements, it allows me to learn what works and what may not work as well.”

Dr. Kevin B Fricka, MD, Clinical Investigator

  2016 Otto Aufranc Award

A Multi-Center, Prospective, Randomized Study of Outpatient versus Inpatient Total Hip Arthroplasty
Goyal N, Padgett SE, Chen AF, Tan TL, Kheir MM, Hopper, RH Jr, Hamilton WG, Hozack WJ.

This award winning study found hip replacement surgery just as satisfying for outpatients as for those patients staying a minimum of one night in the hospital. Dr. Nitin Goyal, and Dr. William Hamilton of AORI and colleagues from The Rothman Institute in Philadelphia, compared patient’s overall satisfaction with their hip replacement and their next day pain levels. Over two hundred randomly chosen patients were assigned to the either go home the same day or stay at least one night. The study also compared the number of follow up calls, doctor visits and post-surgical problems. Patients who went home the same day experienced slightly higher pain levels on the day after surgery compared to those who had at least one-night hospital stay. But the outpatients had a higher overall satisfaction with their surgery. Neither group exceeded the other in calls to the doctor or follow-up issues. The results of this study suggest outpatient total hip replacements work well for some patients.

Read more: Clin Orthop Relat Res. 2016 Jun 10. 2013.

March 28, 2016

Clinical Faceoff: Where Are We Going With Femoral Stem Fixation in THA?
Moskal JT, Capps SG, Engh CA Jr, Troelsen A.

Dr. Andy Engh of AORI, Alexandria, VA, and Dr. Anders Troelsen of Dept. of Orthopaedic Surgery, Copenhagen University Hospital alternately discuss the different trends in femoral stem fixation comparing the various methods of fixation in the US and Europe. Dr. Andy Engh states research shows cementless femoral implants are more durable for younger total hip replacement patients while cemented implants seem to work better with less fractures in older patients. Dr. Andy also remarks about the fact that North American doctors are generally not teaching how to cement so the practice is being used less. Dr. Anders suggested that the use of cement is still more common in Europe and that the practice of doing so needs to continue to be taught to the new generations of clinicians.

Read more:

March 26, 2016

Severely Obese Patients Have a Higher Risk of Infection After Direct Anterior Approach Total Hip Arthroplasty.
Purcell RL, Parks NL, Gargiulo JM and Hamilton WG

Anderson Orthopaedic Research Institute’s clinical and scientific investigators: Dr. Rick Purcell, Nancy Parks, Jeanine Gargiulo and Dr. Bill Hamilton, reported that obese patients with a Body Mass Index of greater than 35, (≥35kg/m2), are at a substantially increased risk for a postoperative infection warranting revision surgery when the anterior surgical approach is used. This is likely due to the deep abdominal folds overlaying the incision. The investigators suggest comparative studies should be done using other surgical approaches with obese individuals to determine if the infections were primarily due to the approach or if significant increase in body mass increases overall risk of infections in hip patients.

Read more: J Arthroplasty. 2016 Mar 26. pii: S0883-5403(16)00326-0. doi: 10.1016/j.arth.2016.03.037.

February 2016

No Difference in Reoperations at 2 Years Between Ceramic-on-metal and Metal-on-metal THA: A Randomized Trial
Ench CA Jr, Sritulanondha S, Korczak A, Whalen TD, Naudie DDR, McCalden, RW, MacDonald SJ.

Anderson Orthopaedic Research Institute investigators and fellow collaborators from Division of Orthopaedic Surgery, Joint Replacement Institute, London Health Sciences Centre, London, Ontario, Canada, participated together in a prospective randomized trial comparing Ceramic-on-metal, (CoM), with Metal-on-metal, (MoM), bearings, the adjoined surfaces between the ball replacement on the top of the femur, and the cup insertion into the socket joint, or the acetabulum. Three hundred and ninety patients were enrolled in the trial at 11 different centers. Of the 390, 194 received ceramic-on-metal bearing surfaces while 196 received metal-on-metal bearings in their hip replacements. The short term follow-up for both groups showed successful performance of the hip implants. However, while the MoM group had a higher level of metal ions, the researchers decided that the CoM would need longer studies to see if it continued to perform well over time.

Read more: Clinical Orthopaedics and Related Research®, February 2016, Volume 474, Issue 2, pp 447-455.

February 1, 2016

CORR Insights ® : Is There a Benefit to Modularity in ‘Simpler” Femoral Revisions?
Engh, CA

Dr. Andy Engh of AORI comments on the article with the same name by Huddleston and colleagues. In his commentary, Dr. Andy shares the importance of using the best method for each individual patient so the patient returns to maximal functional ability and best quality of life.

Read more: Clinical Orthopaedics and Related Research. DOI: 10.1007/s11999-105-4524-2.


“AORI has a database tracking hip and knee patients since the late 70's. Our surgeons operate on thousands of hip and knee joints a year. The high volume allows a much sooner observation of their outcomes.”

Henry Ho, Senior Project Director

August 2015

Short-term Results of Birmingham Hip Resurfacing in the United States.
Nam D, Nunley RM, Ruh EL, Engh CA Jr, Rogerson JS, Brooks PJ, Raterman SJ, Su EP, Barrack RL.

This group of collaborative investigators from 5 US centers including AORI were seeking information on success rates of Birmingham Hip Resurfacings done on 1271 patients between 2006-2008 in a 2 to 4 year follow up. Of the 1144 contacted either by phone or follow up appointments, only 16 patients needed revisions to total hip replacements. It appears the Birmingham Hip Resurfacing patients, 75% of whom were male were fairing as well as patients who had regular total hip replacements.

Read more: Orthopedics. 2015 Aug;38(8):e715-21. doi: 10.3928/01477447-20150804-60.

May 2015

Greater Trochanteric Fragmentation After Failed Metal-on-Metal Hip Arthroplasty.
Panichkul P, Fricka KB, Hopper RH Jr, Engh CA Jr.

The AORI investigators take a clinical and scientific look at bone loss of the greater trochanter in two patients after hip revision surgeries for failed metal-on-metal (MoM) hips. Both patients had revision surgeries replacing the failed metal-on-metal with polyethylene bearings. Yet 1-2 years later, both of these patients developed greater trochanteric fragmentation. This study warns that necrotic tissues may include bone as well as soft tissue. Orthopaedic doctors may wish to become mindful of this and pay attention for symptoms in potential hip revision patients.

Read more: Orthopedics. 2015 May;38(5):e447-51. doi: 10.3928/01477447-20150504-93.


“Research is the eyesight for better patient care and the future of medicine.”

Neone Smith, Scientific Investigator

April 29, 2014

The functional assessment test: a method of evaluating improvement in function after knee arthroplasty.
Engh GA, Sheridan MJ, Ammeen DJ.

Dr. Jerry Engh and research colleagues developed an easily administered timed test called the Functional Assessment test to determine if knee replacement patients improved their daily activity skills. The test included standing, walking and climbing stairs. The researchers concluded the FA test would be practical in a clinical environment.

Read more: J Arthroplasty. 2014 Apr;29(4):712-8. doi: 10.1016/j.arth.2013.06.038. Epub 2013 Aug 1.

March 19, 2014

Metal ion levels after metal-on-metal total hip arthroplasty: a five-year, prospective randomized trial.
Engh CA Jr, MacDonald SJ, Sritulanondha S, Korczak A, Naudie D, Engh C.

Fellow investigators from Anderson Orthopaedic Research Institute in Alexandria, VA and London Health Sciences Centre-University Hospital Orthopaedics, Ontario Canada studied a randomized group of patients undergoing total hip arthroplasty. The 105 patients did not know which of three categories of implant they would receive. The three types of implants used were as follows: 28-mm metal-on-polyethylene, 28-mm metal-on-metal or 36-mm metal-on-metal. The U.S. Food and Drug Administration desired follow-up data for these after-market devices. Metal levels were tested in all patients. The outcome of the tests showed the metal-on-metal hip patients and particularly the 36-mm patients had higher levels of metal ions in their blood at the five-year follow up. The metal-on-polyethylene group had appreciably lower metal ions in their blood. The investigators indicate watching the metal-on-metal group closely.

Read more: J Bone Joint Surg Am. 2014 Mar 19;96(6):448-55. doi: 10.2106/JBJS.M.00164.


  2013 OREF/CCJR Clinical Practice Award

Patient Specific Instruments do not Shorten Surgical Time: A Prospective, Randomized Trial
Hamilton WG, Parks NL, Saxena A.

AORI’s Dr. Bill Hamilton won the 2013 OREF/CCJR Clinical Practice Award for his research comparing the amount of time it took to perform total knee replacements using patient-specific instrumentation (PSI) compared to using traditional instrumentation (TI). The PSI group’s surgeries actually took an average of 4 minutes longer compared to the TI group. However, the TI surgeries required more instrument trays. In conclusion, surgery with patient specific instruments did not shorten the operation time.

Read more: J Arthroplasty. 2013 Sep;28(8 Suppl):96-100. doi: 10.1016/j.arth.2013.04.049.

  2013 AAHKS Dorr Award

Do you have to remove a corroded femoral stem?
Goyal N, Ho H, Fricka KB, Engh CA Jr.

Drs Fricka, Goyal and Anderson, of AORI discuss leaving securely placed femoral stems in the bone even if some corrosion exists. This retrospective study looked at 86 retrieved femoral heads from metal-on-polyethylene total hip replacements. The heads were evaluated after they were replaced with new components in living, healthy patients. Out of the 86 patients only 7 needed hip re-revisions. None of the re-revisions were due to corrosion of the stem. Since corrosion of the stems did not create a need for additional surgery, the AORI researchers recommend leaving well-attached stems in place.

Read more: J Arthroplasty. 2014 Sep;29(9 Suppl):139-42. doi: 10.1016/j.arth.2014.03.055.

September 28, 2013

Radiographically measured total knee wear is constant and predicts failure.
Engh CA Jr, Collier MB, Hopper RH Jr, Hatten KM, Engh GA

Drs. Jerry and Andy Engh, high volume orthopaedic joint replacement surgeons, look at the wear of knee implants over 10 years of follow-up visits with their patients. Working together with the scientists at AORI, they found that wear of the prosthetic knees is constant over time in most cases. Compared to knees with lower rates, knees with higher wear rates are more likely to need revision at some point in the future.

Read more: J Arthroplasty. 2013 Sep;28(8):1338-44. doi: 10.1016/j.arth.2013.04.047.


  2012 Chitranjan Ranawat Award

Efficacy of Postoperative Intra-articular Analgesia Following Total Knee Arthroplasty: A Randomized, Double Blinded, Placebo-Controlled, Prospective Study.
Goyal N, McKenzie, J, Sharkey PF, Parvizi J, Hozack WJ, Austin MS.

Dr. Goyal, clinical investigator at AORI and colleagues from Thomas Jefferson University Hospital & The Rothman Institute in Philadelphia were awarded the Ranawat Award for this study on the effect of using pain pumps with bupivacaine, a local anesthesia, for post-operative patients having total knee replacements. They found that using a pain pump near the surgery area significantly decreased patients’ pain as well as their use of narcotics.

Read more: Clin Orthop Relat Res. 2013 Jan; 471(1): 64–75.


  2011 AAHKS Dorr Award

A Prospective, Randomized Study of Crosslinked and Non-Cross-linked Polyethylene for Total Hip Arthroplasty at 10-Year Follow-Up.
Engh CA Jr, Hopper RH Jr, Huynh C, Ho H, Sritulanondha S, Engh CA Sr.

Drs. Charles and Andy Engh and a team of AORI scientific investigators won the AAHKS Dorr award for this randomized study following up on patients with either cross-linked or non-cross-linked polyethylene liners in their total hip arthroplasties after ten years. The results show that the cross-linked liners had longer wear and fewer bone loss related problems.

Read more: J Arthroplasty. 2012 Sep;27(8 Suppl):2-7.e1. doi: 10.1016/j.arth.2012.03.048.


February 2010

Survivorship of a low-stiffness extensively porous-coated femoral stem at 10 years.
Hartzband MA, Glassman AH, Goldberg VM, Jordan LR, Crowninshield RD, Fricka KB.

Over one hundred patients were studied in follow up visits who had been a part of an original prospective study using a new femoral implant with greater flexibility and extra porous coating to determine how well the implants were serving the patients. In the 86 living patients who were followed this particular femoral implant was still yielding an excellent Harris Hip Score of 98 at the ten-year mark. The researchers suggest that this particular type of component has very good long term function and wear.

Read more: Clinical Orthopaedics and Related Research, 468(2), 433-440.