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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.

Background: The purpose of this study was to examine the outcomes of repeat revision after failure of a constrained liner., Methods: We reviewed 1212 consecutive revisions and identified 74 (6%) revisions of a failed constrained liner in 46 patients with a mean age of 65 years. The most common reasons for revision of a constrained liner were recurrent instability (64.9%) and infection (25.7%)., Results: At a mean of 35 months, 42 of the 74 hips (57%) required repeat revision. Kaplan-Meier revision-free survival was 24% at 10 years. Thirty-two of the 74 revisions (43%) had a dislocation event after the index revision. Kaplan-Meier dislocation-free survival was 43% at 10 years. There was a higher failure rate among the 34 patients with abductor deficiency (hazard ratio 1.90, 95% confidence interval, 1.06-3.43; P = .032)., Conclusion: Patients undergoing revision of a failed constrained liner have a high likelihood of recurrent dislocation and repeat revision surgery., Level of Evidence: Level IV., (Copyright © 2018. Published by Elsevier Inc.)

Given the increasing number of total hip arthroplasty procedures being performed annually, it is imperative that orthopaedic surgeons understand factors responsible for instability. In order to treat this potentially complex problem, we recommend correctly classifying the type of instability present based on component position, abductor function, impingement, and polyethylene wear. Correct classification allows the treating surgeon to choose the appropriate revision option that ultimately will allow for the best potential outcome., (©2016 The British Editorial Society of Bone & Joint Surgery.)

Femoral bone loss is a complex problem in revision total hip arthroplasty. The Paprosky classification is used when determining the degree and location of bone loss. Meticulous operative planning is essential where severe bone loss is a concern. One must correctly identify the bone loss pattern, safely remove the existing components, and proceed with the proper reconstruction technique based on the pattern of bone loss. This article discusses the etiology and classification of bone loss, clinical and radiographic evaluation, components of effective preoperative planning, and clinical results of various treatment options with a focus on more severe bone loss patterns., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Background: Despite dislocation being the most frequent complication after revision THA, risk factors for its occurrence are not completely understood., Questions/purposes: We therefore (1) determined the overall risk of dislocation after revision THA in a large series of revision THAs using contemporary revision techniques, (2) identified patient-related risk factors predicting dislocation, and (3) identified surgical variables predicting dislocation., Methods: We performed 1211 revision THAs between June 2004 and October 2010 in 576 women and 415 men who had a mean age of 64.7 years (range, 25-95 years) at time of surgery. Forty-six (4%) were lost to followup and 13 died (1%), leaving 1152 hips followed for a minimum of 90 days (mean, 2 years; range, 90 days to 7.1 years). Multivariate logistic regression was performed to identify risk factors for dislocation. The model was also tested on patients followed for a minimum 1 year to assess any difference in longer followup., Results: One hundred thirteen patients dislocated over the followup period (9.8%). Factors that were different between patients who dislocated and those who remained stable included a history of at least one previous dislocation (odds ratio [OR] = 2.673), abductor deficiency (OR = 2.672), and Paprosky acetabulum class (OR = 1.522). Use of a constrained liner (OR = 0.503) and increased femoral head size (OR = 0.942) were protective against dislocation, while with longer followup a constrained liner was no longer significant., Conclusions: Dislocation remains a common problem after revision THA. Identifying these risk factors can assist in patient education and surgical planning. Recognition of these risk factors in both patient type and surgical strategy is important for the surgeon performing revision THA and for minimizing these risks., Level of Evidence: Level IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

A moderator and panel of five experts led an interactive session in discussing five challenging and interesting patient case presentations involving surgery of the hip. The hip pathologies reviewed included failed open reduction internal fixation of subcapital femoral neck fracture, bilateral hip disease, evaluation of pain after metal-on-metal hip arthroplasty, avascular necrosis, aseptic loosening secondary to osteolysis and polyethylene wear, and management of ceramic femoral head fracture.

Background: Corrosion at the modular head-neck junction of the femoral component in total hip arthroplasty has been identified as a potential concern, although symptomatic adverse local tissue reactions secondary to corrosion have rarely been described., Methods: We retrospectively reviewed the records of ten patients with a metal-on-polyethylene total hip prosthesis, from three different manufacturers, who underwent revision surgery for corrosion at the modular head-neck junction., Results: All patients presented with pain or swelling around the hip, and two patients presented with recurrent instability. Serum cobalt levels were elevated prior to the revision arthroplasty and were typically more elevated than were serum chromium levels. Surgical findings included large soft-tissue masses and surrounding tissue damage with visible corrosion at the femoral head-neck junction; the two patients who presented with instability had severe damage to the hip abductor musculature. Pathology specimens consistently demonstrated areas of tissue necrosis. The patients were treated with debridement and a femoral head and liner exchange, with use of a ceramic femoral head with a titanium sleeve in eight cases. The mean Harris hip score improved from 58.1 points preoperatively to 89.7 points at a mean of 13.0 months after the revision surgery (p=0.01). Repeat serum cobalt levels, measured in six patients at a mean of 8.0 months following revision, decreased to a mean of 1.61 ng/mL, and chromium levels were similar to prerevision levels. One patient with moderate hip abductor muscle necrosis developed recurrent instability after revision and required a second revision arthroplasty., Conclusions: Adverse local tissue reactions can occur in patients with a metal-on-polyethylene bearing secondary to corrosion at the modular femoral head-neck taper, and their presentation is similar to the adverse local tissue reactions seen in patients with a metal-on-metal bearing. Elevated serum metal levels, particularly a differential elevation of serum cobalt levels with respect to chromium levels, can be helpful in establishing this diagnosis.

Background: Hybrid revision knee component fixation, in which cement is placed in the metaphysis combined with a cementless diaphyseal engaging stem, provides ease of insertion, possibly improved component alignment, and easier removal if required, compared with fully cemented prostheses. The literature suggests the technique has a 2 to 5 year survivorship ranging from 81% to 94%., Questions/purposes: To confirm the literature we asked whether (1) a modified hybrid fixation technique is durable and reliable at an average 5-year followup, (2) this method of fixation provides clinical improvements as assessed by knee scores, (3) there are radiographic findings unique to this fixation technique, (4) the degree of knee constraint influences clinical performance or radiographic findings, and (5) end-of-stem pain is associated with this fixation method?, Patients and Methods: We retrospectively reviewed all 83 patients who had 88 both-component revision TKAs using our modified hybrid fixation technique. We assessed the Knee Society scores and evaluated radiographs for radiolucent and radiosclerotic lines. The minimum followup was 24 months (average, 65 months; range, 24-126 months)., Results: Kaplan-Meier survivorship free of aseptic loosening was 100% at 5 years and 90% at 10 years. Postoperatively, the mean Knee Society pain and function scores both improved. Partial radiolucent lines were rare; two components were loose. We commonly observed radiosclerotic lines adjacent to stem extensions but these did not affect clinical scores or implant stability at last followup. Neither knee scores nor radiographic findings differed based on knee constraint. End-of-stem pain occurred rarely and was transient., Conclusions: Modified hybrid fixation of revision knee arthroplasty using a diaphyseal engaging stem and cementation only in the metaphysis is durable at a mean 5 years followup., Level of Evidence: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Stable acetabular fixation cannot be reliably achieved with the use of a hemispherical porous coated component alone in patients with a Paprosky type IIIa defect. The purpose of the present study was to determine the short-term results of a tantalum porous coated hemispherical acetabular component supported with a modular tantalum augment in Paprosky type IIIa defects. A total of 28 patients (28 hips) were treated for a type IIIa acetabular defect between 2001 and 2003 with the use of a trabecular metal acetabular component supported with a modular, superiorly placed trabecular metal augment. At an average of 3.1 years follow-up, 1 patient required rerevision for recurrent instability. The remaining hips remain radiographically stable. Clinically, the patients' modified Postel Merle d'Aubigne score improved from 6.8 preoperatively to 10.6 postoperatively. The use of a trabecular metal acetabular component with a superiorly placed trabecular metal augment demonstrates encouraging short-term results for Paprosky type IIIa acetabular defects.

Considerable femoral bone loss can be encountered in the multiply revised total hip arthroplasty patient. Deficient proximal bone requires either a bulk allograft or a femoral component that allows stable distal fixation. Extensively coated stems have shown excellent results for many revisions but have shown higher rates of failure among patients with femoral remodeling in retroversion, an enlarged endosteal diameter, or an ectatic canal. A modular tapered stem is an alternative in this subset of patients. A modular tapered implant provides axial and rotational stability through the use of distal splines, and the proximal body segments can allow independent adjustment of leg length, offset, and anteversion.