Clinical Orthopaedics and Related Research ®

A Publication of The Association of Bone and Joint Surgeons ®

Symposium: Retrieval Studies 13 articles

Articles

Surface Damage Versus Tibial Polyethylene Insert Conformity: A Retrieval Study

Markus A. Wimmer PhD, Michel P. Laurent PhD, Jeannie D. Haman PhD, Joshua J. Jacobs MD, Jorge O. Galante MD

Surface damage of the tibial polyethylene insert in TKA is thought to diminish with increasing conformity, based on computed lower contact stresses. Added constraint from higher conformity may, however, result in greater forces in vivo.

Knee Wear Measured in Retrievals: A Polished Tray Reduces Insert Wear

Daniel J. Berry MD, John H. Currier MS, Michael B. Mayor MD, John P. Collier DE

Polyethylene wear is often cited as the cause of failure of TKA. Rotating platform (RP) knees show notable surface damage on the rotating surface raising concerns about increased wear compared to fixed bearing inserts.

Does Using Autograft Bone Chips Achieve Consistent Bone Ingrowth in Primary TKA?

Roy D. Bloebaum PhD, Karyn E. Koller MD, MPH, Bettina M. Willie PhD, Aaron A. Hofmann MD

Cementless fixation remains controversial in TKA due to the challenge of achieving consistent skeletal attachment. Factors predicting durable fixation are not clearly understood, but we presumed bone ingrowth could be enhanced by the quantity of host bone and application of autograft bone chips.

Constrained Cups Appear Incapable of Meeting the Demands of Revision THA

Philip C. Noble PhD, Salim K. Durrani MD, Molly M. Usrey BS, Kenneth B. Mathis MD, Nikolaos V. Bardakos MD

Failure rates of constrained cups for treating recurrent dislocation in revision THA range from 40% to 100%. Although constrained liners are intended to stabilize the hip by mechanically preventing dislocation, the resulting loss of range of motion may lead to impingement and, ultimately, implant failure.

Pseudotumors Are Common in Well-positioned Low-wearing Metal-on-Metal Hips

Ashley K. Matthies BSc, John A. Skinner FRCS(Orth), Humza Osmani BSc, Johann Henckel MRCS, Alister J. Hart MD, FRCSG(Orth)

Pseudotumors are sterile inflammatory lesions found in the soft tissues surrounding metal-on-metal (MOM) and metal-on-polyethylene hip arthroplasties. In patients with MOM hip arthroplasties, pseudotumors are thought to represent an adverse reaction to metal wear debris. However, the pathogenesis of these lesions remains unclear. Currently, there is inconsistent evidence regarding the influence of adverse cup position and increased wear in the formation of pseudotumors.

Which Radiographic Parameters Are Linked to Failure of a Dynamic Spinal Implant?

Eike Hoff MD, Patrick Strube MD, Antonius Rohlmann PhD, Christian Groß MD, Michael Putzier MD

Knowledge about factors leading to failure of posterior dynamic stabilization implants is essential to design future implants and establish surgical indications. Therefore, we analyzed an implant for single-level or hybrid configuration (adjacent to spondylodesis), which was recalled due to high failure rates.

Is Monocyte Chemotactic Protein 1 Elevated in Aseptic Loosening of TKA?: A Pilot Study

Vinod Dasa MD, Jill M. Kramer DDS, PhD, Sarah L. Gaffen PhD, Keith L. Kirkwood DDS, PhD, William M. Mihalko MD, PhD

Failure of TKA from aseptic loosening is a growing concern, as TKA is performed with increasing frequency. Loosening is multifactorial and may be associated with elevated inflammatory cytokines in addition to biomechanical failure.

In Vivo Oxidation and Surface Damage in Retrieved Ethylene Oxide-sterilized Total Knee Arthroplasties

Daniel MacDonald MS, Josa Hanzlik MS, Peter Sharkey MD, Javad Parvizi MD, Steven M. Kurtz PhD

Gas sterilization (eg, ethylene oxide [EtO] and gas plasma) was introduced for polyethylene to reduce oxidation due to free radicals occurring during radiation sterilization. Recently, oxidation has been observed in polyethylenes with undetectable levels of free radicals, which were expected to be oxidatively stable. It is unclear whether in vivo oxidation will occur in unirradiated inserts sterilized with EtO.

Proximal Component Modularity in THA—At What Cost?: An Implant Retrieval Study

A. M. Kop PhD, C. Keogh DipAppSci, E. Swarts BSc

While modular femoral heads have been used in THA for decades, a recent innovation is a second neck-stem taper junction. Clinical advantages include intraoperative adjustment of leg length, femoral anteversion, and easier revision, all providing flexibility to the surgeon; however, there have been reports of catastrophic fracture, cold welding, and corrosion and fretting of the modular junction.

Gamma-irradiation Sterilization in an Inert Environment: A Partial Solution

Daniel J. Berry MD, Barbara H. Currier MChE, Michael B. Mayor MD, John P. Collier PhD

In the mid to late 1990s, to sterilize UHMWPE bearings, manufacturers changed from gamma-irradiation-in-air (gamma-air) sterilization, which initiated oxidation leading to bearing fatigue, to gamma-irradiation sterilization in an inert environment (gamma-inert). The change to gamma-inert sterilization reportedly prevented shelf oxidation before implantation but not in vivo oxidation.

How Do CAD Models Compare With Reverse Engineered Manufactured Components for Use in Wear Analysis?

Matthew G. Teeter BSc, Douglas D. R. Naudie MD, Robert B. Bourne MD, David W. Holdsworth PhD

To accurately quantify polyethylene wear in retrieved arthroplasty components, the original geometry of the component must be estimated accurately using a reference geometry such as a computer-aided design (CAD) model or a never-implanted insert. However, differences may exist between the CAD model and manufactured inserts resulting from manufacturing tolerances.

Posterior Cruciate Mechanoreceptors in Osteoarthritic and Cruciate-retaining TKA Retrievals: A Pilot Study

Kelly Zhang BS, William M. Mihalko MD, PhD

Although normal cruciate ligaments and those in patients with osteoarthritic (OA) knees contain mechanoreceptors, it is unclear whether they are present after functioning in a cruciate-retaining total knee arthroplasty (TKA).