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Dr. Maloney is Elsbach-Richards Professor of Surgery, and Professor and Chairman, Department of Orthopaedic Surgery, Stanford University, Stanford, CA. Dr. Rosenberg is Professor of Surgery, and Director and Fellowship Director, Adult Reconstructive Orthopedics, Rush Medical College, Chicago, IL.
*The Implant Wear Symposium 2007 Clinical Work Group included John J. Callaghan, MD, John M. Cuckler, MD, Jorge O. Galante, MD, DMSc, Alejandro González Della Valle, MD, Stuart B. Goodman, MD, PhD, James I. Huddleston, MD, Lynne C. Jones, PhD, David G. Lewallen, MD, Henrik Malchau, MD, PhD, William Maloney, MD, Amanda Marshall, MD, Wayne Paprosky, MD, Hollis G. Potter, MD, Michael D. Ries, MD, Aaron Rosenberg, MD, Thomas P. Sculco, MD, Bernard N. Stulberg, MD, Audrey K. Tsao, MD, and Timothy Wright, PhD.
Dr. Maloney or a member of his immediate family has received research or institutional support from DePuy, Medtronic, Synthes, and Zimmer; has received royalties from Zimmer and Wright Medical Technology; and is a consultant to or an employee of Wright Medical Technology. Dr. Rosenberg or a member of his immediate family has received research or institutional support, has received royalties, has stock or stock options held in, and serves as a consultant to Zimmer.
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Abstract |
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 Top Abstract Osteolysis About the HipOsteolysis Around Total Knee...Future Directions for ResearchReferences |
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Osteolysis About the Hip |
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TopAbstractOsteolysis About the HipOsteolysis Around Total Knee...Future Directions for ResearchReferences |
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In the femur, the factors that affect the outcome of surgical management of osteolysis are similar, including fixation of the implants and the ability to retain the stem, and the degree of femoral bone loss. Osseointegrated implants do not require postoperative activity restriction, and recovery is relatively quick. When femoral stem revision is required, a small but significant percentage of revision stems will not osseointegrate. With substantial proximal femoral bone loss and progressive widening of the diaphyseal canal, the ability to reliably obtain implant fixation is compromised.
Well-fixed Cementless Implants
Impaction grafting of osteolytic defects around well-fixed cementless implants can be successful, provided specific guidelines are followed.1-7 For the acetabulum, relative contraindications for débridement, grafting, and bearing component exchange include a malpositioned socket, a severely damaged locking mechanism and/or shell, poor implant design, and ongrowth fixation surfaces. A malpositioned socket increases the risk for dislocation after liner exchange. Severe damage may compromise the stability of a new liner, even when it is cemented. Some designs preclude insertion of a new liner of adequate thickness and quality. Ongrowth fixation surfaces, as opposed to three-dimensional ingrowth surfaces, are more likely to loosen in the presence of large osteolytic defects and are at potential risk for socket breakout.
In the femur, the relative contraindications for implant retention include diaphyseal osteolysis, severe taper corrosion, and area of osseointegration insufficient to provide long-term implant stability. Diaphyseal osteolysis indicates a pathway between the joint space and the endosteal canal. These lesions are difficult to débride and graft with the femoral stem in place. In addition, these defects put the patient at risk for periprosthetic fracture. Severe taper corrosion is a source of biologically active particulate debris that can also lead to third-body wear. Taper corrosion also weakens the neck of the femoral component and can result in component fracture. In the presence of femoral osteolysis, proximally coated cementless femoral components with a limited area of bone ingrowth surfaces are at risk for loosening.
When the aforementioned criteria are met, the surgeon may consider granuloma débridement and grafting of the osteolytic defect with an exchange of the bearing surface component. Typically, allograft bone chips are used. A variety of other bone void fillers have been used to fill defects; however, no data exist as to their efficacy for this application. At the time of surgery, implant osseointegration must be confirmed, and hip stability must be carefully assessed. Isolated liner exchanges are at higher risk for postoperative dislocation.2,5,6 Implant position, femoral component head size and neck diameter, and surgical approach affect the risk for dislocation.
Follow-up studies evaluating treatment of pelvic and proximal femoral osteolytic lesions demonstrate that lytic defects either decrease in size or resolve after surgery. Maloney et al1 reported on 35 patients who underwent liner exchange for polyethylene wear and osteolysis. Seventy-four percent of the lesions were grafted. At final follow-up, one third had resolved and the remaining two thirds had decreased in size regardless of whether they were filled with bone graft. None of the sockets that were deemed well-fixed at surgery subsequently loosened. O’Brien et al5 reported on 23 patients treated with isolated liner exchange for wear and osteolysis. Accessible lesions were grafted with allograft bone chips. In 18 hips, a computer-assisted method was used to measure lesion area. Seventeen of the 18 lesions either regressed or resolved postoperatively. At maximum follow-up of 100 months, two patients required rerevision. The authors concluded that in selected patients, isolated liner exchange is effective for treating wear and associated osteolysis. In a similar study, Terefenko et al6 demonstrated that débridement and modular component exchange slowed the progression of osteolysis; over a mean follow-up period >6 years, none of the sockets had loosened.
Treatment of proximal femoral osteolysis in association with a well-fixed femoral component has also been successful. Benson et al7 reported on 17 patients who underwent bone grafting of proximal femoral lytic defects. Stable cementless stems were retained. At follow-up ranging from 2 to 6 years, 15 of 17 lesions regressed. No stems loosened. In a minimum 5-year follow-up study of 15 patients, Maloney4 reported similar results. None of the stems (seven extensively coated stems, five proximally coated stems, and three modular femoral components) loosened over time.
Removal of well-fixed cementless implants that do not meet the guidelines for implant retention should be considered. Following implant removal and granuloma débridement, bone defects can be assessed, and the reconstruction performed following the same principles used for revision of loose implants.
Simple exchange of the bearing surface is less common in patients who have cemented hip components. This is because the pathophysiology of the osteolytic process commonly affects cemented implant fixation so that managing osteolysis in association with cemented hip replacement more commonly requires complete component revision.
Loose Implants
When evaluating the outcome of treatment of osteolysis in association with loose implants, the surgeon must examine the ability both to restore bone stock and to obtain rigid implant fixation. In 90% to 95% of acetabular revisions, the lytic process results in cavitary (contained) defects and/or minor column defects. These defects can be treated by reaming the socket to contour the acetabulum and packing the contained defects with allograft bone chips. The graft can be compacted using the reamer in reverse. The reconstructions can be performed using a hemispheric acetabular component. Screws are typically used to enhance initial stability and maximize the chance of bone ingrowth. Follow-up studies demonstrate a high degree of success for these cases. Bone graft appears to incorporate and remodel over time.
Leopold et al8 reported on 138 cementless acetabular revisions fixed with screws at an average of 10.5 years after the revision procedure. Only two sockets were loose radiographically. Five patients underwent late acetabular revision; however, none of the revisions were for loosening. Weeden and Paprosky9 reported on 134 acetabular revisions using hemispheric porous-coated sockets fixed with peripheral screws in patients who had "severe acetabular deficiencies" that did not require structural grafts. At a mean follow-up of 13.2 years, 95% of the sockets were stable radiographically. Seven sockets (5%) failed, with five cases of infection and two instances of loosening. The authors concluded that severe acetabular defects, provided they were cavitary or minor column defects (ie, Paprosky type 1 or type 2),10 could be addressed with a porous-coated acetabular component fixed with peripheral screws.
Techniques that provide initial socket stability to permit bone ingrowth can be employed when the implant is unstable intraoperatively after socket preparation but there is >50% contact with viable host bone and the posterior column is intact (ie, Paprosky 3A defect). Historically, a distal femoral allograft has been used. Sporer et al11 reported on 31 patients who had a type 3A defect that was treated with a distal femoral allograft and a porous-coated acetabular component fixed with screws. Patients were followed for an average of 10.3 years. Five acetabular components were rerevised for aseptic loosening at a mean of 5.3 years after the index operation. One additional socket was loose radiographically, for an overall mechanical failure rate of 21%. Allograft resorption was seen around 6 of the 17 stable components.
More severe defects (ie, Paprosky type 3B defects) have been commonly managed with a large structural allograft and a cage to unload the graft. Bostrom et al12 reviewed 29 patients undergoing 31 acetabular revisions with a Contour cage; two were Paprosky type 2B, seven were type 3A, and 22 were type 3B. At a mean 30-month follow-up evaluation, two hips had been revised (7%) and five were radiographically loose (16%), for an overall failure rate of 23%. This report highlights the limitations of current methods available for treating patients with extensive acetabular bone loss. These operations should be potentially viewed as staged procedures. When graft resorption occurs, the cage may lose bony support, undergo fatigue, and break. Because the allograft often incorporates with host bone, rerevision can sometimes be performed with a porous-coated socket. Custom triflanged implants have also been used to treat these severe defects. Dennis13 reported on 24 patients with Paprosky type 3B defects who were treated with a custom triflanged component. At a follow-up ranging from 48 to 78 months, 21 of 24 of the implants (87.5%) were stable.
More recently, porous tantalum augments have been used to address these more severe defects. Weeden and Schmidt14 reported on 33 type 3A and 10 type 3B defects. In 26 cases, tantalum augments were used to stabilize the cup. At a mean follow-up of 2.8 years, the overall success rate was 98%. Longer-term follow-up using tantalum augments will be required to determine their suitability compared with structural allografts.
Although the degree of osteolysis in the femur affects the complexity of a femoral revision and has a negative impact on outcome, bone stock is not typically restored in revision surgery. Proximal bone loss is generally bypassed, and stem fixation is obtained in the femoral diaphysis. With stabilization of the femoral component, bone quality often will improve radiographically. Strut allografts are being used less frequently and are now primarily used to reinforce the femur to address a potential stress riser in the diaphysis or to stabilize an intraoperative fracture. Proximal femoral allograft composites have been less commonly utilized in recent years, but they can be used to address extensive proximal femoral bone loss. In femurs with insufficient endosteal bone to provide support for a cementless device, impaction grafting of fresh-frozen allograft bone chips continues to be performed and has been shown to restore bone.
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Osteolysis Around Total Knee Arthroplasty |
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TopAbstractOsteolysis About the HipOsteolysis Around Total Knee...Future Directions for ResearchReferences |
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Frequent clinical monitoring is appropriate when surgical intervention is not anticipated in the near future. Radiographs taken at regular intervals can determine the rate of progression; patients without significant progression or symptoms must be cautioned that continued regular surveillance is essential.19-26 However, patients with significant life expectancy should be forewarned that surgical intervention will likely become needed at some point, and both patient and clinician should fully understand that neglect of wear and significant osteolysis only delays the need for what may become more difficult surgery, as lesions progress in size and/or complete failure of the bearing with metal-on-metal contact precludes simple bearing exchange.
Surgical Treatment of Periprosthetic Osteolysis
Indications for surgical intervention for periprosthetic osteolysis about the knee include (1) first-time presentation of advanced osteolysis in the presence of an identifiable cause of wear particle production or in the presence of associated bone loss that places the structural integrity of the bone or fixation of the components at risk, (2) bearing surface wear in the presence of impending wear-through or related mechanical symptoms, (3) progressive osteolysis in an active individual, and (4) symptoms of wear debris–related synovitis that are refractory to conservative treatment.15,21-23,25-29
The goals of surgery are to reduce particle debris load, restore bone, and either exchange the polyethylene bearing or revise one or all components. Isolated component revision remains controversial because clinical data relating to isolated tibial bearing exchange, as opposed to revision of otherwise well-fixed and well-functioning components, remains limited. In a review of 48 isolated tibial bearing exchanges for advanced wear or osteolysis in the presence of otherwise stable components, Engh et al21 found a 15% failure rate at an average 54-month follow-up as a result of accelerated wear of the revised inserts. This early repeated polyethylene failure may reflect the quality of the material used at the time of revision, as well as specific attributes of implant design. The outcome of 56 isolated polyethylene exchanges for a variety of problems was reviewed by Babis et al;27 24 were for wear, 16 (67%) of which survived at an average of 4.6 years. These authors concurred with Engh et al21 that isolated polyethylene exchange should not be performed within 10 years of index surgery.
Griffin et al28 reported similar results for isolated polyethylene exchange for wear and/or osteolysis in 68 press-fit condylar total knee arthroplasties (TKAs). At an average of 44 months (range, 4 to 83 months), they noted 11 failures (16%), including aseptic loosening in 10 and infection in 1. Ninety-seven percent of the TKAs demonstrated no progression of osteolysis. Although the rate of clinical failure was similar to that reported by Engh et al,21 these authors reached a different conclusion, stating that
we believe the 84% success rate with modular polyethylene exchange for wear and osteolysis and the lack of progression of osteolytic lesions in the majority of the knees are encouraging.
The conclusions reached appeared to reflect a risk-benefit ratio analysis of the alternative procedure:
full revision of well-fixed total knee components can lead to substantial bone loss, particularly in the face of osteolysis, and we therefore consider modular polyethylene exchange in press-fit condylar knees a reasonable option for wear and osteolysis.
Similar findings were reached by Jensen et al,22 who found an 80% survival at 34 months in 27 isolated tibial polyethylene exchanges and commented that
the short-term survival ... was similar to that of a total knee revision with exchange of all components. Since [isolated polyethylene exchange] is a much smaller operation with fast rehabilitation, we recommend it in elderly patients with a well-fixed and well aligned prosthesis without surface damage of the components.
In a striking example of adherence to this clinical philosophy, Whiteside and Katerberg30 performed isolated liner exchange for wear in 49 knees. Although two of the knee designs being revised allowed for simple polyethylene exchange in the standard locking mechanism, three other designs (in 36 of the knees) required fabrication of a locking mechanism with roughening of the tibial base plate with a carbide bit, followed by cementing of a new tibial polyethylene insert. The fabricated locking mechanism had outperformed the standard locking mechanism in laboratory mechanical studies, and no knees with a fabricated mechanism failed clinically at short-term follow-up.
Revision surgery with retention of components remains controversial. Mackay and Siddique31 reviewed the results of revision at 4 years in two groups—25 knees with a stable and normally aligned original femoral component, with minimal bone loss, in which the original component was therefore retained, and 42 knees that did not fulfill retention criteria and underwent revision of both components. Re-revision for loosening was required in 28% of the retained group and in only 7% of the other group. However, cases clearly exist in which the choice of component revision is not critical or obvious. For instance, in the setting in which component removal is not specifically indicated and would potentially exacerbate severe osteolytic bone loss, component retention may be the most reasonable choice.
Complete Revision
The burden of revision in the TKA with severe osteolysis was demonstrated by Robinson et al.25 The authors reviewed the challenges involved in 17 cases, reflecting the degree of difficulty often encountered in revising the TKA with severe lysis. Exposure was generally difficult, requiring rectus snip, V-Y quadricepsplasty, tibial tubercle osteotomy, or lateral release in half of the cases. Bone defects were consistently underestimated radiographically and were manageable with cement only in 47%, with allograft required in 30%, metallic augments in 35%, and constrained condylar devices in 30%. Performing this surgery requires knowledge of and attention to the principles of revision knee replacement: thorough exposure; component removal with minimal bone damage; and reestablishing flexion and extension gaps, the joint line, limb alignment, and appropriate component rotation with implants that are intrinsically stable and supported as needed by augments and/or structural graft.15-17,26,29,31-45 Supplemental stem extensions have long been considered important for the success of both augments and grafts, and they are recommended for implants with increased prosthetic constraint.16,17,31,32,34,37-40 Knowledge of their use is essential for the surgeon who is undertaking revision of a TKA with significant osteolysis.
Small and moderate defects are now well managed by metallic augments.17,29,35,37 Yet in massive defects, construct stabilization may require supplemental bone graft. Engh et al16 reported on 54 consecutive revisions at a minimum of 5 years; 89% required augments, and 48% needed additional structural graft. Interestingly, revisions requiring graft failed at less than half the rate of those that did not (19% versus 43%). The authors noted that "augments did not effectively address the bone loss and instability encountered in many instances at revision surgery."
The use of a structural graft has been reported, with variable outcomes. In a recent review of 68 structural grafts in 61 revision TKAs evaluated at a mean 5.4-year follow-up,15 13 knees failed because of graft-related complications. The authors reported one nonunion, three loosenings, three periprosthetic fractures, four infections, and two revisions to correct instability. Bezwada et al33 reviewed a series of 11 knees in 10 patients undergoing revision of failed modular PFC (DePuy Orthopaedics, Raynham, MA) TKAs requiring distal femoral allograft and long-stemmed revision. At 3 and 4 years postoperatively, no cases of loosening were found, and graft incorporation was demonstrated in all 11 cases. These improved results may reflect improved surgical technique and revision implant design, as well as a focus on a particularly well-defined population of patients requiring revision.
Particulate allograft has traditionally been used in small contained defects, but more recently, it has been reported in managing larger uncontained defects by appropriately configuring the defect and containing the graft by mesh augments.26,34,36,37,41-43 Lotke and colleagues37,38,45 recently reported the results of 41 of 48 consecutive revisions with substantial bone loss treated with impaction grafting. At average follow-up of 3.8 years, no mechanical failures had occurred, and all radiographs demonstrated incorporation and remodeling of the graft. Recent work on combining particulate grafting with augment support by massive metaphyseal augments of porous metal has shown great promise (at short-term follow-up) in simplifying the management of massive defects. This may be applicable in cases in which modular oncologic-type implants might otherwise be required for treatment of massive defects.
Over the past decade, increased experience with massive osteolysis after TKA has led to better understanding of the technical requirements and the development of more sophisticated techniques for successful revision. Revision in the setting of advanced osteolysis is technically challenging, and surgeons should be armed with the knowledge of a variety of reconstructive techniques for managing bone loss, including the use of allograft, augments, and appropriate components for fixation and joint stability. The increased burden of failure from osteolysis in specific poor implant designs may have affected the trend toward polyethylene exchange. The development of new methods for bone defect restoration is promising but as yet unproven.
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Future Directions for Research |
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TopAbstractOsteolysis About the HipOsteolysis Around Total Knee...Future Directions for ResearchReferences |
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References |
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TopAbstractOsteolysis About the HipOsteolysis Around Total Knee...Future Directions for ResearchReferences |
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| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
