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World J Orthop. Sep 18, 2021; 12(9): 629-639
Published online Sep 18, 2021. doi: 10.5312/wjo.v12.i9.629
Hip prosthetic loosening: A very personal review
Bengt Mjöberg
Bengt Mjöberg, Department of Orthopedics, Lund University, Lund SE-221 00, Sweden
Author contributions: Mjöberg B wrote this review.
Conflict-of-interest statement: The author declare that there is no any conflict of interest.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Bengt Mjöberg, BSc, MD, PhD, Associate Professor, Department of Orthopedics, Lund University, Box 117, Lund SE-221 00, Sweden. bengt.mj@telia.com
Received: January 20, 2021
Peer-review started: January 20, 2021
First decision: May 3, 2021
Revised: May 3, 2021
Accepted: August 3, 2021
Article in press: August 3, 2021
Published online: September 18, 2021
Processing time: 236 Days and 20.1 Hours
Abstract

Hip prosthetic loosening is often difficult to detect at an early stage, and there has been uncertainty for a long time as to when the loosening occurs and thus to the basic causes. By comparing different diagnostic methods, we found that loosening is best defined as prosthetic migration and measured by radiostereometric analysis. Convincing evidence indicates that poor interlock, poor bone quality, and resorption of a necrotic bone bed may initiate loosening during or shortly after surgery; this forms the basis of the theory of early loosening. Biomechanical factors do affect the subsequent progression of loosening, which may increase subclinically during a long period of time. Eventually, the loosening may be detected on standard radiographs and may be interpreted as late loosening but should to be interpreted as late detection of loosening. The theory of early loosening explains the rapid early migration, the development of periprosthetic osteolysis and granulomas, the causality between wear and loosening, and largely the epidemiology of clinical failure of hip prostheses. Aspects discussed are definition of loosening, the pattern of early migration, the choice of migration threshold, the current understanding of loosening, a less exothermic bone cement, cemented taper-slip stems, a new exciting computed tomography-based technique for simpler implant migration studies, and research suggestions.

Keywords: Hip prosthesis; Prosthesis failure; Radiostereometric analysis; Bone resorption; Bone cements; Radionuclide imaging

Core Tip: Much evidence indicates that prosthetic loosening is initiated during or shortly after surgery. The prosthetic micromovements may increase subclinically during a long period of time. Eventually, the loosening may be detected on standard radiographs and may be interpreted as late loosening but should to be interpreted as late detection of loosening. The discussion includes the definition of loosening, the pattern of early migration, the choice of migration threshold, the current understanding of loosening, a less exothermic bone cement, cemented taper-slip stems, a new exciting computed tomography-based technique for simpler implant migration studies, and research suggestions.