A Case of Severe Systemic Cobalt Toxicity in THA
A 61-year-old female patient presents with worsening groin pain and symptoms suggesting cobalt toxicity – including vision and hearing loss – following revision of a fractured ceramic-on-ceramic bearing surface to a cobalt-chrome-on-polyethylene bearing surface.
Michael Feldstein MD, MS; Max Greenky MD; Lindsay McAlpine; and Matthew S. Austin, MD
The authors have no disclosures relevant to this article.
Cobalt toxicity is a well-documented complication of total hip arthroplasty (THA) when cobalt-chrome implants are utilized.  Although it is most commonly associated with metal-on-metal bearing surfaces, there are multiple reports of cobalt toxicity following revision of a fractured ceramic head or liner to a metal-on-polyethylene bearing surface secondary to third body wear from retained ceramic particles. [2–11]
Cobalt levels are often found to be an order of magnitude higher in cases in which a previous ceramic component failed when compared with cases related to metal-on-metal articulations, modular metal-on-metal components, or trunion wear.
Exposure to high cobalt levels is known to have local and systemic manifestations, including but not limited to: 
- Pseudotumor formation
- Adverse tissue reaction
- Visual deficits
- Weight loss
- Pancreatic insufficiency
This case report illustrates the severe and rapid systemic manifestations of cobalt poisoning secondary to ceramic particulate third body wear of a cobalt-chrome head after revision THA.
A 61-year-old female underwent left THA with a ceramic-on-ceramic bearing surface in 2004 at another hospital. This THA served her well for 11 years. In early 2015, however, she began having groin pain after a subluxation episode.
The pain increased over the course of the year and eventually became intractable, with an associated crunching sensation within the joint. Radiographs revealed a fractured ceramic acetabular liner and evidence of radio-dense material around the hip joint.
The patient was subsequently revised at another hospital in May 2015. At the time, the surgeon noted diffuse ceramic particles throughout the joint space. The cobalt-chrome backing of the ceramic liner showed evidence of wear, and metallosis was present intraoperatively.
The surgeon attempted to remove all ceramic debris and performed an extensive synovectomy before implanting a cobalt chrome-on-polyethylene articulation. Postoperative X-rays in June 2015 showed no evidence of wear of the cobalt-chrome head and a small amount of residual radio-dense material present.
In July 2015, the patient began to experience hearing loss followed by blurry vision, sustained sinus tachycardia, new onset diabetes insipidus, and peripheral neuropathy. A month later, she had a dislocation during physical therapy that requiring closed reduction in the operating room. No wear of the cobalt-chrome head was noted at the time of reduction.
By September 2015, however, X-rays of the left THA showed marked wear of the cobalt-chrome head and extensive deposition of radio-opaque debris in the effective joint space extending down the thigh. At that point, she had also experienced an explained 41-pound weight loss; the weight loss had begun shortly after the revision surgery.
An esophagogastroduodenoscopy (EGD) in October 2015 showed that she had developed gastritis. Her condition deteriorated such that she could no longer walk without assistance because of pain and neuropathy, and she could no longer drive because of marked visual impairment.
She saw an outside neurologist who tested her whole blood cobalt level and found it to be 2128 mcg/L, with normal being < 3 mcg/L, and she was referred to our institution for evaluation. She was admitted in November 2015 with progressive worsening of her symptoms.
- Height: 5 feet, 5 inches; weight: 125 pounds; BMI: 20.8 kg/m2
- Well-healed incision on left hip without signs of infection
- Moderate limp; cane used to aid ambulation
- Hip range of motion painful and limited to 90° flexion, 20° internal rotation, and 30° external rotation
- Tenderness at the greater trochanter
- Bilateral sensori-neural hearing loss
- Bilateral lower extremity burning, paraesthesias, and diffuse decreased sensation to pinprick and light touch; more apparent in the lower than the upper extremities
- Thyroid-stimulating hormone level elevated to 20.35 UIU/mL (normal, 0.3-5 UIU/mL)
- Erythrocyte sedimentation rate: 10mm/hr (within normal range)
- C-reactive protein level: 0.60mg/dL (within normal range)
- Serum cobalt level: 1,997mcg/L (normal, <2.8)
- Serum chrome level: 55.7mcg/L (normal, <1.8)
- Deformity of the cobalt-chrome head
- Radiopaque material surrounding the prosthesis, extending throughout the effective joint space (Figure 1)
Figure 1. Preoperative radiographs showing radio-opaque material extending throughout the effective joint space and down the thigh. The femoral head has been deformed.
CT scan and MRI
- Show close proximity of metal debris to sciatic nerve (Figure 2)
- Components well fixed with no subsidence
Figure 2. Preoperative axial CT showing proximity of metal debris to sciatic nerve (left). Coronal MRI showing metal artifact around the metal particulate debris indicating that the radio-dense material is metallic in origin and not heterotopic ossification (right).
- Cardiomyopathy with mild left ventricular diastolic dysfunction and mild right ventricular enlargement and dysfunction
- Systemic cobalt toxicity from third body wear of the cobalt chrome femoral head secondary to ceramic particulate embedded in the polyethylene liner
- Associated diagnoses
- Optic neuritis with partial blindness
- Sensori-neural hearing loss
- Diffuse Peripheral Neuropathy
- Unexplained weight loss
- Diabetes insipidus
In these cases, the primary treatment is removal of the cobalt source by revision THA.
- The patient was medically optimized for surgery. Continuous veno-venous hemodialysis and plasmapharesis was attempted preoperatively to lower the patient’s cobalt levels, but was not effective. This was discontinued because the literature lacked strong guidance to warrant continued attempts. Levothyroxine sodium (Synthroid) was prescribed for hypothyroidism and pregabalin (Lyrica) was prescribed for neuropathy.
- In November 2015 the patient was taken to the operating room for revision of the head/liner to a ceramic-on-polyethylene articulation.
- Extensive irrigation and debridement was performed. Entry through the fascia revealed 300 mL of blackened fluid (Figures 3 and 4). Extensive metal debris and blackened ceramic particulates were found embedded in the polyethylene liner. The head was damaged/malformed (Figure 5).
- The liner, cup, and head ware exchanged for a titanium cup with a polyethylene liner and a ceramic head.
- Pressured saline with suction was utilized to aid in debridement of the necrotic tissue.
- Repeat irrigation and debridement were planned due to high metal load and metallosis.
Figure 3. Metallosis was evident on entry into the hip joint.
Figure 4. Intraoperative photo shows the extent of metallosis down the thigh.
Figure 5. The removed femoral head shows eccentric wear caused by third body particle ceramic debris (left). Close-up of the polyethylene liner with embedded ceramic particulate debris and metallosis (right).
The patient was admitted to the surgical intensive care unit (SICU) for stabilization due to blood loss and her rising lactate level from the extensive surgery and debridement. She had an estimated blood loss of 1000 mL, necessitating transfusion of 4 units of packed red blood cells.
Postoperatively, she developed a Fanconi-like syndrome that was treated with supportive measures and eventually resolved spontaneously. Her diabetes insipidus worsened initially after surgery, was treated with desmopressin, and then resolved.
One week later, the patient was returned to the operating room for repeat irrigation and debridement. Additional necrotic tissue was debrided, with retention of the liner and head. Estimated blood loss from this procedure was 500 mL.
Postoperative images demonstrated a well-fixed revision acetabular component with ceramic-on-poly articulation. The previously noted radio-opaque material surrounding the hip and femur was much reduced (Figure 6).
Figure 6. Postoperative radiograph after the second debridement.
Samples taken during the revision surgery and during the repeat irrigation and debridement were sent for culture and were found to be negative at 14 days following the procedure.
The patient was discharged to a rehabilitation facility. She was allowed only toe touch weight-bearing for 6 week due to weak bone stock, and she was advised to maintain hip precautions for life because of soft tissue deficiency and abductor deficiency found intraoperatively. Enoxaparin was prescribed for 4 weeks as deep vein thrombosis prophylaxis.
At discharge, the patient’s cobalt level was 246 mcg/L and her chrome level was 9.8mcg/L (normal levels are < 1.8 and < 1.2, respectively). One month later, the cobalt and chrome levels had decreased to 141.5 mcg/L and 7.2 mcg/L, respectively, still well above normal.
At the 1-month follow-up, the patient’s wound was well healed. Her vision, hearing, neuropathy issues had improved but were not yet at baseline. Her hypothyroidism and Fanconi-like syndrome had also improved.
When a patient has a fractured ceramic bearing, consideration should be given to revision to either a ceramic-on-ceramic bearing or a ceramic-on-polyethylene bearing instead of cobalt-chrome bearing surfaces. In this case, ceramic-on-polyethylene was chosen for 2 reasons:
- The patient’s original articulation was ceramic-on-ceramic and the liner had a cobalt-chrome backing that had already been worn down by the ceramic head, causing metallosis and cobalt exposure noted at the first revision surgery.
- The patient had poor abductor integrity during her second revision surgery, and because she only had a 50-mm cup, a ceramic liner would not have allowed for a larger-diameter head.
A downside of the use of a ceramic-on-polyethylene articulation after a ceramic failure is that there is a potential for ceramic particulate to embed in the polyethylene and cause rapid wear of the polyethylene. As such, these patients require monitoring for signs of early polyethylene wear.
During revision for metallosis, thorough debridement should be performed. Osteolysis can occur and should be treated accordingly. It may be necessary to repeat irrigation and debridement.
Instability may be an issue due to extensive soft tissue damage from prolonged exposure to toxic metal ion levels. Appropriate components should be chosen to maximize stability.
Michael Feldstein, MD, is an orthopaedic surgery fellow at The Rothman Institute at Thomas Jefferson University, Philadelphia, Pennsylvania. Max Greenky, MD, is an orthopaedic surgery resident at Thomas Jefferson University Sidney Kimmel Medical College, Philadelphia, Pennsylvania. Lindsay McAlpine is a medical student at the Thomas Jefferson University Sidney Kimmel Medical College, Philadelphia, Pennsylvania. Matthew S. Austin, MD, is a Professor of Orthopaedic Surgery at The Rothman Institute at Thomas Jefferson University, Philadelphia, Pennsylvania.
Adult Reconstruction Section Editor, Rothman Institute Grand Rounds
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