Periprosthetic Bone Loss in Total Hip Arthroplasty (THA)

Thirty-four hips in which there had been prosthetic replacement were selected for study because of the presence of linear (diffuse) or lytic (localized) areas of periprosthetic bone loss. In all hips, there was careful documentation of the anatomical location of the material that had been obtained for histological analysis, and the specific purpose of the removal of the tissue was for examination to determine the cause of the resorption of bone. Specimens from twenty-three hips were retrieved during an operation and from eleven hips, at autopsy. The area of bone loss was linear only in sixteen hips, lytic only in thirteen, and both linear and lytic in five. In allthirty-four hips, intracellular particulate debris was found in the macrophages that were present in the area of bone resorption. All thirty-four had intracellular particles of polyethylene, many of which were less than one micrometer in size. Thirty-one hips had extracellular particles of polyethylene as well. Twenty-two of the thirty-four hips had intracellular metallic debris; in ten, metallic debris was found extracellularly as well. Ten of the sixteen cemented specimens had intracellular and extracellular polymethylmethacrylate debris. In the mechanically stable prostheses cemented and uncemented polyethylene wear debris was identified in areas of bone resorption far from the articular surfaces. The number of macrophages in a microscopic field was directly related to the amount of particulate polyethylene debris that was visible by light microscopy. Although the gross radiographic appearances of linear bone loss and lytic bone loss were different, the histological appearance of the regions in which there was active bone resorption was similar. Regardless of the radiographic appearance and anatomical origin of *One or more of the authors has received or will receive benefits for personal or professional use from a commercial party related directly or indirectly to the subject of this article. In addition, benefits have been or will be directed to a research fund, foundation, educational institution. or other non-profit organization with which one or more ofthe authors is associated. Funds were received in total or partial support of the research or clinical study presented in this article. The funding source was the William H. Harris Foundation. tHarbor-University of California. Los Angeles. Medical Center. 1000 West Carson Street, Torrance. California 90509. jioint Replacement Institute. 2400 South Flower Street. Los Angeles. California 90007. §Orthopaedic Biomechanics Laboratory. Massachusetts General Hospital. Boston. Massachusetts 021 14. the specimen, bone resorption was found to occur in association with macrophages that were laden with polyethylene debris. In general, the number of macrophages present had a direct relationship to the degree of bone resorption that was seen. We believe that these findings indicate that joint fluid penetrates far more extensively than previously thought, even in a well fixed component, along the interface between the prosthesis and bone and in the periprosthetic tissues; it is often more extensive than is shown by arthrography. We therefore suggest the concept of the effective joint space to include all periprosthetic regions that are accessible to joint fluid and thus accessible to particulate debris. We also suggest that the difference between lytic (localized) bone loss and linear (diffuse) bone loss may be related to the local concentration or distribution of particulate wear debris; this may in turn depend on patterns of the flow of joint fluid (preferential flow) within the effective joint space. Before total hip arthroplasty became common, localized bone destruction was almost always secondary to tumor, infection, or metabolic disease and was rarely seen with endoprostheses #{176}. When peniprosthetic bone loss appears localized or scalloped, it has been called osteolysis or lysis”, to distinguish it from bone loss that is linear on more evenly distributed around the implant. Osteolysis was observed by Charnley early in the development of low-friction anthroplasty, but because of the frequent occurrence of infection early in his series, he attributed the osteolysis to the infection8. The discoveny of particulate polymethylmethacrylate in specimens from focal areas of lysis around both stable and loose prostheses, as well as from areas of more linear and uniform bone resorption, gave rise to the concept of so-called cement disease2527. One of the proposed advantages of fixation without cement is avoidance of this complication. However, lysis has been reported in association with both stable and loose uncemented femoral components, indicating that the problem is broaden in scope and is far from solved229. The observation of particulate metallic debris in histological sections from localized regions of aggressive lysis around uncemented implants has generated additional controversy about the best alloy fonjoint replaceDuration Mechanical jet Sini Symptoms Source Location Bone Loss Stability