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As the demand for total hip arthroplasty (THA) continues to increase, the burden of revision THA is also expected to increase. Although the quality of polyethylene has improved markedly, osteolysis continues to be a risk for older designs and younger, active patients. Although progressive but typically asymptomatic in early stages, osteolysis can result in component failure and complicate revision surgery. Serial radiographs are paramount for monitoring progression. Although select cases may be treated with observation, surgery should be considered based on age, activity level, and projected life span. Well-fixed, noncemented modular acetabular components may be treated with curettage and bone grafting, as well as having to bear liner exchange with retention of the acetabular shell. However, in the setting of osteolysis, it is controversial whether bone grafting and component retention is superior to cup revision. This review explores the pathophysiology of osteolysis after THA and provides a comprehensive analysis of the evaluation and treatment of patients with osteolysis.

Osteolysis around the knee following total knee arthroplasty continues to be a leading cause for revision total knee arthroplasty. Risk factors for periprosthetic knee osteolysis are associated with excessive polyethylene wear and include, but may not be limited to, malalignment of the mechanical axis, early-generation polyethylene sterilization techniques, excessive backside polyethylene wear, metal-backed patellar components, patient age, and an elevated body mass index. The initial diagnosis of osteolysis is frequently discovered on routine surveillance radiographs. The location, size, progressive nature, and associated symptomatology of the defect guides treatment. Surgical indications and timing are predicated on the risk of failure with continued observation. Advanced imaging helps to quantitate the size and location of osteolytic lesions as accurately as possible and aids in preoperative planning. When deciding whether surgery or management with continued radiographic surveillance is indicated, a global assessment of the character and progression of the osteolysis must be weighed with the risk factors associated with the patient., (Copyright 2015 by the American Academy of Orthopaedic Surgeons.)

During the past two decades, most total hip arthroplasties were performed with metal or ceramic heads on conventional polyethylene, an articulation associated with wear and limited life expectancy. Wear is associated with acetabular osteolysis. Isolated liner exchange has become a common surgical intervention when the acetabular component remains well-fixed. The purpose of isolated liner exchange is to prevent loosening of the components secondary to osteolysis and catastrophic mechanical failure caused by bearing wear-through. Treatment options for polyethylene wear include observation (in the asymptomatic hip), liner exchange, and more extensive revision procedures. Patients frequently present with asymptomatic but substantial polyethylene wear with or without associated osteolysis, the treatment of which is controversial. Other areas of debate include complete acetabular component removal to allow bone grafting and placement of an improved bearing surface, reuse of modular mechanisms, cementation into well-fixed shells, and whether to use periacetabular bone grafting.

Prospective, randomized clinical wear studies have shown significant wear reduction when highly cross-linked, e-beamed, melted polyethylene was compared with conventional polyethylene sterilized by gamma irradiation in air. More complete assessment of wear-induced osteolysis in the general total hip arthroplasty patient population must rely on registries with follow-up of large populations of patients through radiographic evaluation of wear-related factors, such as suboptimal placement of the implant components, osteolytic defects, and aseptic loosening. Follow-up radiographs should be obtained in the early postoperative period and at 1, 5, and 10 years postoperatively, and then every 1 to 5 years, thereafter depending on radiographic findings of osteolysis and its progression. When pathologic findings are present, further examinations, such as oblique Judet views and magnetic resonance imaging (MRI) with artifact minimization should be considered to provide a better determination of the extent of the osteolysis. Because conventional radiographs underestimate the prevalence and extent of osteolysis in many instances, diagnosis and surveillance should be performed with radiographic edge detection, spiral computed tomography (CT), MRI, radiostereometric analysis, and quantitation of wear and osteolysis, including bone and soft-tissue lesions. Helical CT has demonstrated excellent specificity in identifying and quantifying the extent of osteolysis. MRI can more accurately localize both osseous and soft-tissue particulate disease, and detect granuloma and compression on adjacent nerves and vessels.

Potential systemic markers of implant wear include products of the wear process (particles and ions) and mediators of the inflammatory reaction that can be induced by wear. Ions from polymers used in arthroplasty are not specific, but high metal ion levels may help identify patients with unexpectedly high wear of metal-on-metal implants. The kinetics of ion production, transport, and excretion are complex, however, so it is currently difficult to interpret the significance of mild elevations in metal ions. Indices of bone turnover (eg, collagen fragments) and mediators involved in the inflammatory reaction to particles (eg, osteoprotegerin, RANKL, interleukins) may be associated with osteolysis, but systemic disorders (eg, osteoarthritis) and the use of medications that influence bone remodeling limit the predictive value of these analytes with respect to the consequences of implant wear. Using genomic and proteomic methods to measure multiple analytes offers promise, but the challenge is to identify markers specifically associated with wear that are not elevated by other conditions that often coexist in this patient population.

Periprosthetic osteolysis is most often diagnosed by plain radiographs. Because these radiographs routinely underestimate the extent of the lesion, three-dimensional imaging should be used early in the evaluation process to confirm the presenting extent of disease. If the osteolytic process is asymptomatic, scheduled regular follow-up should be instituted until the lesion can be confirmed to be stable or until the decision is made to proceed with surgery. Nonsurgical management with pharmacologic agents has not proved to be effective. If surgery is contemplated, a three-dimensional evaluation with magnetic resonance imaging or helical computed tomography can assist in preoperative planning. Surgical intervention requires complete débridement of the lesional membrane and removal of the wear-generator--with or without component removal and with or without bone grafting, depending on the individual circumstances. A standardized follow-up evaluation mechanism for all patients should be a part of total joint arthroplasty management.

The acromioclavicular (AC) joint may be affected by a number of pathologic processes, most commonly osteoarthritis, posttraumatic arthritis, and distal clavicle osteolysis. The correct diagnosis of a problem can usually be deduced from a thorough history, physical examination, and radiologic evaluation. Asymptomatic AC joint degeneration is frequent and does not always correlate with the presence of symptoms. Selective lidocaine injection enhances diagnostic accuracy and may correlate with surgical outcome. Nonoperative treatment is helpful for most patients, although those with osteolysis may have to modify their activities. In appropriately selected patients, open or arthroscopic distal clavicle resection is necessary to relieve symptoms. Recent biomechanical and clinical data emphasize the importance of capsular preservation and minimization of bone resection; however, the optimal amount of distal clavicle resection remains elusive. Patients with AC joint instability have poor results after distal clavicle resection.