**5.3 Patient selection**

The final outcome of THA depends on a large number of factors including the design of the implant, surgical technique, and patient selection. Currently there are no scientifically proven criteria for matching individuals to particular implant. At the time of surgery, the decision should involve the *age of the patient***,** *his/her local bone status and overall health condition* enabling rough estimation of time in use for the THA. Based on current best evidence, younger more active patients have several options to minimize wear, loosening and osteolysis, and thereby optimize implant longevity. These alternatives include ceramic-onceramic bearings or ceramic head or highly polished cobalt-chrome femoral heads articulating with highly-cross linked polyethylene.

Another concern relates to *primary diagnosis* and the expecting of worse prognosis especially in patients with osteoarthritis after developmental dysplasia in comparison with those with idiopathic osteoarthritis. This may be associated at least partially with severity of dysplasia (Chougle et al. 2005). In fact, experienced surgeon and choice of implant could also play a role. Recent analysis from the Danish Hip Arthroplasty Registry failed to reveal substantial differences in revision risk between the above groups with follow-up of from 0.5 to 12 years postoperatively (Thillemann et al. 2008). Low revision rate has been observed in both cemented and cementless THA (Sochart and Porter 1997; Rozkydal et al. 2005). Rheumatoid arthritis does not require a special approach even in young patients. Regarding the choice of implant in these patients, a higher risk of revision was found for THAs with uncemented cups and cemented stems according in the Finnish Arthroplasty Registry (Eskelinen et al. 2006). However, the difference in survivorship between cemented and uncemented THAs disappeared in patients older than 55 years old (Makela et al. 2011).

### **5.4 Operative procedures**

Surgically-related variables are those related to wear rate and those that influence the strength of implant-bone fixation. Wear rate can be influenced primarily by *appropriate choice of implant and experienced surgical technique* especially in terms of positioning of the cup and

Aseptic Loosening of Total Hip Arthroplasty as a Result of Local Failure of Tissue Homeostasis 353

HLA Human Leukocyte Antigen (HLA DR+ is a MHC II class II cell surface receptor)

ALVAL Aseptic Lymphocyte-dominated Vasculitis-Associated Lesions ARF Activation-Reversal-Formation cycles (bone remodelation)

GM-CSF Granulocyte Macrophage Colony Stimulating Factor

**7. List of abbreviations used in the chapter** 

BMP Bone Morphogenetic Protein BMU Bone Multicellular Unit CD Cluster of Differentiation CoC Ceramic on Ceramic

DTH Delayed-Type Hypersensitivity

HXLPE Highly Cross-Linked PolyEthylene ICAM InterCellular Adhesion Molecule

IRAK Interleukin-1-Receptor-Associated Kinase

PAMPs Pathogen-Associated Molecular Patterns PMMA PolyMethylMethAcrylate (bone cement)

RANK Receptor Activator of Nuclear factor Kappa beta

SLIM Synovial membrane-Like Interface Membrane

UHMWPE Ultra-High Molecular Weight PolyEthylene

RANKL Receptor Activator of Nuclear factor Kappa beta Ligand

MCP-1 Monocyte Chemoattractant Protein-1 M-CSF Macrophage Colony-Stimulating Factor MHC Major Histocompatibility Complex MIP Macrophage Inhibitory Protein

ECM ExtraCellular Matrix FBGCs Foreign Body Giant Cells FGF Fibroblast Growth Factor

HIF Hypoxia-Induced Factor

IFN-γ Interferon gama IL-1β, 2 .. Interleukins

MoM Metal on Metal MoP Metal on Polyethylene MPa Megapascal (pressure unit) MSCs Mesenchymal Stromal/Stem Cells

NF-κβ Nuclear Factor kappa beta NK cells Natural Killer cells OPG Osteoprotegerin

PRRs Pattern-Recognition Receptors

SNP Single-Nucleotide Polymorphism SOCS Suppressor Of Cytokine Signalling TGF Transforming Growth Factor THA Total Hip arthroplasty TLRs Toll-Like Receptors

TNF-α Tumor Necrosis Factor alpha TREG T-REGulatory lymphocytes

VCAM Vascular Cell Adhesion Molecule VEGF Vascular Endothelial Growth Factor

ROS Reactive Oxygen Species

LPS LipoPolySaccharide

stem, assuming both the inappropriate bearing surfaces and/or incorrect positioning of the implants contribute to increased wear rate and risk of osteolysis development (Little et al. 2009). Surgical technique can also influence the strength of implant-bone interface. In this connection, any mistake during cementation can increase the risk of premature failure (Barrack, Mulroy et al. 1992). In support, it seems that high-volume surgeons can achieve lower revision rates than low-volume surgeons especially during the early period after the surgery (Losina et al. 2004).
