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Featured researches published by Richard L. Illgen.


Journal of Arthroplasty | 2008

Highly Crosslinked vs Conventional Polyethylene Particles—An In Vitro Comparison of Biologic Activities

Richard L. Illgen; Todd M. Forsythe; J. Wesley Pike; M.P. Laurent; Cheryl Blanchard

Highly cross-linked polyethylenes (HXPEs) have been introduced to reduce wear after hip arthroplasty. The improved wear characteristics of HXPEs are well documented, but the relative biologic activity of HXPE and conventional polyethylene (CPE) particles remains unclear. Longevity (Zimmer, Warsaw, Ind; HXPE) and GUR 1050 (Zimmer; CPE) particles were isolated and characterized from a hip simulator and their in vitro inflammatory responses (tissue necrosis factor *, interleukin 1*, and vascular endothelial growth factor levels) were compared using macrophages. The average diameter of Longevity particles (0.111 microm) was smaller than CPE particles (0.196 microm), and both were predominantly round (granular appearance). The inflammatory response to HXPE and CPE was concentration-dependent. No statistically significant differences were noted at low (0.1 surface area ratio [SAR]) and intermediate (0.75 SAR) doses. At the highest dose tested (2.5 SAR), HXPE was significantly more inflammatory than CPE based on relative tissue necrosis factor alpha and vascular endothelial growth factor secretion levels. Further study is needed to determine if similar findings would be noted in vivo over a broad concentration range.


Journal of Arthroplasty | 2009

Highly Crosslinked Vs Conventional Polyethylene Particles: Relative In Vivo Inflammatory Response☆

Richard L. Illgen; Lia M. Bauer; Bryan T. Hotujec; Sarah E. Kolpin; Aleem Bakhtiar; Todd M. Forsythe

Crosslinked polyethylenes have been introduced to reduce wear and osteolysis. The osteolysis rate depends on many factors including the biologic activity of the wear particles. This study examines the relative inflammatory potential of highly crosslinked and non-crosslinked polyethylene particles. Polyethylene particles were crosslinked and characterized. Dose-response curves were generated for endotoxin-positive and endotoxin-negative particles at each degree of cross-linking using an in vivo model. The 10-MRad crosslinked polyethylene was more inflammatory than an identical dose (25 mg/mL) of non-crosslinked polyethylene (P = .05). Endotoxin increased the inflammatory response to crosslinked and non-crosslinked polyethylene in a similar fashion. These data suggest that the improved wear characteristics of highly crosslinked polyethylenes may be offset somewhat by the modestly increased inflammatory profile of the highly crosslinked compared with non-crosslinked particles.


PLOS ONE | 2012

Coating with a Modular Bone Morphogenetic Peptide Promotes Healing of a Bone-Implant Gap in an Ovine Model

Yan Lu; Jae Sung Lee; Brett Nemke; Ben K. Graf; Kevin Royalty; Richard L. Illgen; Ray Vanderby; Mark D. Markel; William L. Murphy

Despite the potential for growth factor delivery strategies to promote orthopedic implant healing, there is a need for growth factor delivery methods that are controllable and amenable to clinical translation. We have developed a modular bone growth factor, herein termed “modular bone morphogenetic peptide (mBMP)”, which was designed to efficiently bind to the surface of orthopedic implants and also stimulate new bone formation. The purpose of this study was to coat a hydroxyapatite-titanium implant with mBMP and evaluate bone healing across a bone-implant gap in the sheep femoral condyle. The mBMP molecules efficiently bound to a hydroxyapatite-titanium implant and 64% of the initially bound mBMP molecules were released in a sustained manner over 28 days. The results demonstrated that the mBMP-coated implant group had significantly more mineralized bone filling in the implant-bone gap than the control group in C-arm computed tomography (DynaCT) scanning (25% more), histological (35% more) and microradiographic images (50% more). Push-out stiffness of the mBMP group was nearly 40% greater than that of control group whereas peak force did not show a significant difference. The results of this study demonstrated that mBMP coated on a hydroxyapatite-titanium implant stimulates new bone formation and may be useful to improve implant fixation in total joint arthroplasty applications.


Hip International | 2015

Precision of acetabular cup placement in robotic integrated total hip arthroplasty.

Leah Elson; Jon Dounchis; Richard L. Illgen; Robert C. Marchand; Douglas E. Padgett; Charles R. Bragdon; Henrik Malchau

Aims The aim of this study was to assess the efficacy of stereotactic-arm assisted acetabular component placement during total hip arthroplasty (THA). Methods 120 patients underwent primary THA at 4 different medical centres. A preoperative pelvic CT protocol was used to plan socket placement followed by robotic-arm assisted acetabular preparation and cup insertion. Intraoperative cup position was recorded and postoperative placement measured using Martell suite analysis software. Results Using a 95% predictive intervals, robotic-arm cup placement was within +/-4 degrees of planned position in 95% of cases. Applying these data to the so-called safe zone, 96% of sockets were within the defined safe zone. Our data confirms that intraoperative robotic assistance improves the precision of preparation and position of the acetabular cup during total hip arthroplasty.


Journal of Arthroplasty | 2012

Low Rates of Heterotopic Ossification After Resurfacing Hip Arthroplasty With Use of Prophylactic Radiotherapy in Select Patients

Tim J. Kruser; Kevin R. Kozak; Donald M. Cannon; Christopher S. Platta; John P. Heiner; Richard L. Illgen

Recent reports have noted higher rates of heterotopic ossification (HO) with surface replacement arthroplasty (SRA) than with traditional total hip arthroplasty in the absence of postoperative HO prophylaxis. This study reports rates and grades of HO in 44 SRA patients with at least 1 year of follow-up. Heterotopic ossification prophylaxis was used in 32 (73%) of 44 cases. Heterotopic ossification prophylaxis consisted of radiotherapy (22/32), nonsteroidal anti-inflammatory drugs (8/32), or both (2/32). One case of clinically significant HO was documented in the no-prophylaxis group. This strategy of selective HO prophylaxis in patients felt by orthopedic surgeons to be at high risk of HO resulted in low rates of clinically relevant HO after SRA (1/44, 2.3%). Further study is needed to establish optimal selection criteria for HO prophylaxis after SRA.


Archive | 2018

Preclinical Analysis to Assess Aseptic Loosening of Orthopaedic Implants

Heidi-Lynn Ploeg; Anthony G. Au; Ameet Aiyangar; Nipun Yamdagni; Kristopher K. Biegler; Matthew W. Squire; Richard L. Illgen

Although it is long accepted that aseptic loosening is the main reason for revision of total joint replacements, preclinical assessment methods of primary fixation are not well developed. Reasons for aseptic loosening are multifactorial including the patient, surgical approach, biological reactions, wear, micro-motion at the implant–bone interface, load transfer from the joint to the host bone, and bone adaptation. The objective of this study was to highlight a few preclinical methods to investigate orthopaedic implant primary fixation relative to the transfer of loads and displacements at the implant–bone interface. The last generation of metal-on-metal hip prostheses used a high-precision low clearance bearing to provide a low friction ball and socket joint. During implantation the acetabular component deforms under a press-fit; however, excessive deformation of the acetabular component can lead to premature failure of the joint replacement. It is therefore important to establish an accurate method of quantifying cup deformation and develop finite element models to better understand the effects of the press-fit. Methods to measure press-fit deformation of monoblock acetabular cups for metal-on-metal total hip arthroplasty and resurfacing were investigated. The purpose of the present study was to compare cup deformation with two experiments simulating press-fit of an acetabular cup into the pelvis. Rim deformation and cup strain were measured for two common tests: (1) a two-point pinching of the cup rim and (2) a press-fit implantation into a cavitated polyurethane foam block. In the pinch test, the rim displaced linearly and symmetrically with force. The press-fit test, ostensibly a closer representation of surgical procedure, produced more complex displacement and strain responses due to the foam block shape, and the cup surface-foam block interaction. The current study demonstrated two methods to measure real-time hip cup deformation and strain during press-fitting that may be used for preclinical assessment of primary fixation.


Journal of Arthroplasty | 2004

Hybrid total knee arthroplasty ☆: A retrospective analysis of clinical and radiographic outcomes at average 10 years follow-up

Richard L. Illgen; Jonathan Tueting; Timothy Enright; Ken Schreibman; Andrew A. McBeath; John P. Heiner


Journal of Arthroplasty | 2006

The Diagnostic and Predictive Value of Hip Anesthetic Arthrograms in Selected Patients Before Total Hip Arthroplasty

Richard L. Illgen; Nicholas J. Honkamp; Marty H. Weisman; Mary Ellen Hagenauer; John P. Heiner; Paul A. Anderson


Journal of Arthroplasty | 2006

Prospective Analysis of a Novel Long-acting Oral Opioid Analgesic Regimen for Pain Control After Total Hip and Knee Arthroplasty

Richard L. Illgen; Teresa A. Pellino; Debra B. Gordon; Sheryl Butts; John P. Heiner


Journal of Arthroplasty | 2018

Trends in the Use of High-Viscosity Cement in Patients Undergoing Primary Total Knee Arthroplasty in the United States

Mick P. Kelly; Richard L. Illgen; Antonia F. Chen; Denis Nam

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John P. Heiner

University of Wisconsin Hospital and Clinics

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Mary Ellen Hagenauer

University of Wisconsin-Madison

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Todd M. Forsythe

University of Wisconsin-Madison

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Aleem Bakhtiar

University of Wisconsin-Madison

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Anthony G. Au

University of Wisconsin-Madison

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Antonia F. Chen

Thomas Jefferson University

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Ben K. Graf

University of Wisconsin-Madison

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Brett Nemke

University of Wisconsin-Madison

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Bryan T. Hotujec

University of Wisconsin-Madison

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