Cory G. Couch
Michael J. Taunton
Osteolysis can have a number of etiologies including infection, tumors, and inflammatory reactions related to particulate debris. In joint replacement, non-infection-related osteolysis is most commonly caused by reactions to polyethylene debris, cement debris, or metal debris or metal ions.
Osteolysis may be asymptomatic or may lead to pain and decreased function (typically due to the associated particle generated synovitis), loosening of the femoral and/or acetabular component, and periprosthetic fracture.
In many cases, periprosthetic acetabular osteolysis can be treated with component retention in the case of a well-fixed acetabular shell with the benefit of reduced surgical time, blood loss, cost, and avoidance of additional bone loss.
Surgical treatment of osteolysis is recommended when there is imminent wear-through of the acetabular polyethylene, progressive expansile lesions that may cause implant loosening, or periprosthetic fracture.
Prior imaging, over the lifetime of the arthroplasty, is helpful for comparative purposes to evaluate for changes in osteolysis and radiolucent or reactive lines.
Basic Science of Osteolysis
The formation of particulate debris or corrosion products from total hip implants leads to an inflammatory response and macrophage activation that leads to osteolysis.
The particulate debris can be formed from any type of wear of the total hip arthroplasty (THA) implants. Particulate debris can be formed from polyethylene (particularly non-cross-linked polyethylene), either at the bearing surface or on the back side of the polyethylene. Cement debris may be created from a loosened cemented implant (due to abrasion of the cement by implant or bone). Metal wear particles may be created from metal-on-metal bearings. Additionally, modular metal junctions maybe subject to taper corrosion in which mechanically assisted crevice corrosion leads to release of cobalt and chromium ions that lead to osteolysis and tissue necrosis through other pathways.
It is important to first rule out infection in the setting of osteolysis as both may have similar presenting clinical pictures in regard to bone loss. This can be done with laboratory workup of erythrocyte sedimentation rate, C-reactive protein, and aspiration if warranted and intraoperative cultures.
Sterile Instruments and Implants
Routine hip retractors
Cup explant system
Femoral component explant system instruments and tools
High-speed burrs (short and long pencil-tip burrs, 6.5-mm round burr)
Osteotomes (straight, curved, flexible)
Cement removal instruments if cement is present
Ultrasonic cement removal device if available and if cement is present in femur
Drill, drill bits, threaded drill guides, depth gauge
Highly porous revision acetabular components
Various acetabular liner options: standard, dual mobility, constrained
Porous metal augments
Revision femoral components (with trial stems)
Femoral heads (with trial heads)
Cerclage cables and wires
Allograft bone chips
Lateral decubitus position
Typical position for most procedures
The operative limb should be sterilely prepared from the iliac crest to the foot and draped out to the distal thigh
Allows for intraoperative assessment of distal blood flow in emergency
Allows for management of distal femoral fracture intraoperatively
The operative approach is at the discretion of the surgeon and may be chosen based on the location of the osteolysis and the planned operative intervention.
For many cases the authors prefer the posterior approach as it may easily be made extensile if needed. Additionally, posterior column osteolysis is more readily approached posteriorly.
The senior author reserves the anterolateral approach in those with severe abductor damage seen at time of exposure or for cases in which cup retention is planned and there is relatively less prosthetic cup anteversion present.
The direct anterior approach, in expert hands, is useful for a minority of revision hip arthroplasties, but extensile exposure is more difficult.
The size, manufacturer, and brand of the femoral and acetabular implants should be identified for proper planning of removal. If some modular components will be retained, having compatible modular implants such as femoral heads or polyethylene inserts is essential and advance planning is necessary to ensure their availability at surgery.
Prior operative reports for determining the type of articulation and for determining the implant-specific (especially the polyethylene bearing) track record.
Implant stickers are essential.
Identifying features of the implant such as an extraction hole or threaded insertion for an extractor may aid in stem removal with a universal or stem-specific extraction device.
Assess for infection preoperatively with inflammatory markers and fluoroscopically guided hip aspiration as indicated.
If metal corrosion or wear is thought to be the etiology, obtain serum cobalt and chromium levels.
Evaluation and Treatment of Acetabular Osteolysis
Periodic screening of all patients with THA is recommended; more frequent screening is appropriate for patients who are young and active or have components known to be poor performers. This should be performed with anteroposterior (AP) pelvis, AP and lateral hip, and potentially Judet view radiographs.
Plain radiographs may inadequately detect the extent of osteolysis; however, there is increased sensitivity with computed tomography (CT) (and sometimes magnetic resonance imaging [MRI]). These modalities may be recommended in cases in which there is progressive wear and/or symptoms with little radiographic evidence of lysis. However, advanced imaging is not cost-effective for screening. Additionally, in settings of massive osteolysis or if pelvic discontinuity is suspected, CT may help the surgeon further investigate and perhaps plan further surgical intervention.
CT is more effective in assessing bone loss in the pelvis; however, MRI is particularly useful in assessing soft tissue reactions especially in situations of osteolysis in conjunction with metal reaction and soft tissue mass.
It is an important exercise to classify osteolytic bone loss in the setting of revision THA, as the classification systems may help guide treatment.
Paprosky Classification for Acetabular Bone Loss
Type 1: Completely supportive rim without significant bone loss or migration.
2A: Global cavitation of the acetabulum with direct superior hip center migration; sufficiently intact superior dome and teardrop prevent concomitant lateral or medial displacement.
2B: Deficient superior dome, allowing for superior and lateral component migration owing to the lack of a lateral stabilizing buttress.
2C: Deficient medial wall causing direct medial migration of the hip center.
3A: Acetabular rim is deficient from the 10- to 2-o’clock position, moderate to severe destruction of the acetabular walls and posterior column.
3B: Acetabular rim is deficient from the 9- to 5-o’clock position, destruction of all acetabular supporting structures including both walls and both columns, causing the hip center to migrate in a superior-medial direction.
Radiographic Signs of Fixed Acetabular Component (Figure 36.1A-C)
No radiolucent lines
Medial stress shielding
Radiographic Signs of Loose Acetabular Component (Figure 36.4A and B)
Appearance/progression of radiolucent lines >2 years postoperatively
Continuous radiolucent line in all 3 DeLee and Charnley zones
Radiolucent line >2 mm in any DeLee and Charnley zones
Component migration >2 mm, lack of osseous integration is indicated by motion of the acetabular component
The decision to proceed with surgical treatment often is a longitudinal one. Frequently, some patients may be followed for years with known modest polyethylene wear, modest osteolysis, and maybe some mild symptoms.
You may also need
WordPress theme by UFO themes