Cureus: Polyethylene Wear Causes Metallosis After Hemiarthroplasty

A 54-year-old man suffering from severe right hip pain four years after a bipolar hemiarthroplasty faced extensive metallosis caused by complete wear-through of a concealed polyethylene liner, Cureus reported. The case highlights how hidden bearing failure can progress to direct metal-on-metal articulation, bone loss, and prosthetic failure even when standard inflammatory markers remain entirely normal.

Progressive Pain Four Years After Fracture Surgery

The patient originally underwent right bipolar hemiarthroplasty to treat a transcervical fracture of the femoral neck. Four years later, he developed a six-month history of worsening hip pain that severely restricted his daily movement. Routine blood tests showed completely normal results, with a hemoglobin level of 13 g/dL, a total leukocyte count of 8,000 cells/µL, an erythrocyte sedimentation rate of 10 mm/h, and a C-reactive protein level of 2 mg/L. Despite the absence of infection markers, plain radiographs and computed tomography scans revealed eccentric positioning of the femoral head inside the bipolar cup alongside periprosthetic osteolysis and a 2 x 2 cm supra-acetabular bone defect.

Worn Liner Causes Metal Debris and Requires Revision Surgery

Surgeons performing the revision discovered extensive blackish discoloration across the periprosthetic tissues. Examination of the extracted bipolar head assembly showed that the inner polyethylene liner had completely worn through. This failure forced the inner femoral head and the outer metallic shell into a direct metal-on-metal grinding action, generating heavy metallic debris. Because the femoral stem was tightly fixed amid surrounding bone loss, doctors performed an extended trochanteric osteotomy to remove it safely. After thorough debridement, an antibiotic cement spacer was placed. Eight weeks later, the team used an iliac crest bone graft to repair the acetabular defect before switching the joint to a cementless total hip arthroplasty.

Contrasting Revision Realities in Hip Arthroplasty

While the Cureus case details a bipolar hemiarthroplasty failure driven by inner liner wear, similar destructive events occur in standard joint replacements. A parallel case documented on PubMed Central described a 45-year-old male patient who suffered progressive right hip pain and limb shortening a decade after undergoing a total hip arthroplasty. Much like the bipolar hemiarthroplasty patient, that individual exhibited normal systemic parameters while radiographs showed proximal and medial migration of the metal femoral head. During surgery for that total hip replacement, specialists noted capsular hypertrophy and blackish soft tissue pigmentation where the intact metal head had eroded straight through the polyethylene liner and acetabular cup. Both clinical encounters demonstrate that metal ion accumulation and adverse local tissue reactions can destroy surrounding bone and soft tissue long before clinical suspicion of catastrophic wear is raised.