The Story

“Nala was unable to walk and struggling with severe night time pain in her left hip when she first came to see me. Her past orthopaedic history was not uncommon, with previous bilateral metal on plastic hip replacements which had lasted for about 20-years followed by a revision of the left hip secondary to osteolysis 3-years prior to us meeting.

She was having to take NSAIDs to try and stem the pain but unfortunately this was neither fully effective or sustainable. We started an extensive investigation to understand the cause of her pain.”

The Investigation

Clinical examination demonstrated a very painfull and stiff left hip. She had extreme difficulty straight leg raising on the left hand side and was only able to walk a few steps across my clinic room. She had previously been told that her left hip would not be reconstructable, so Nala thought this was the best her walking could be.

To rule out infection we performed a normal set of blood inflammatory markers, none of which were raised.

The Evidence

Anteroposterior plain radiograph of both hips showing bilateral hip replacements with polyethylene liners (it is difficult to distinguish ceramic from metal heads). The right hip stem is radiographically loose with radiolucent lines in all 7 Gruen zones.

Lateral plain radiograph of the left hip. The acetabular cage is loose and it is protruding into the pelvis. The stem on the left hand side is well fixed after her revision procedure.

  • Computer Tomography (CT) showed an intact posterior column.

The Diagnosis

This patient was diagnosed with loosening of the right stem and migration of the left acetabular component. She was offered revision of both sides, starting with the left as this was causing her more discomfort.

The Plan

We planned to retain the well fixed left sided femoral stem but remove all of the acetabular components. Our plan was to use an anti-protrusio cage (like the one below) to form a rigid base in which we could cement a new acetabular liner. Nala had very little bone stock remaining, so with the technology at the time, this was the best option to try and reconstruct her left hip joint.


Anti-protrusio cage - This image shows a left-sided cage. The inferior, spiked flanged is designed to be impacted into the ischium or lie on its outer surface. The superior flanges are designed to fix into ilium. The cages come in a range of sizes. The flanges are difficult to shape to the bone and there is a no fixation into the pubis. A polyethylene cup or dual mobility metal liner is cemented into the cage.

The Operation

To be completed by ROB

  • In 2014 she had bone grafting, a left-sided anti-protrusio cage and a cemented polyethylene cup to reconstruct the left acetabulum. The stem was retained.

The Outcome

Anteroposterior plain radiograph of the pelvis post-revision. This demonstrates a left-sided anti-protrusio cage surrounded with bone graft and a cemented polyethylene cup . The stem was retained as this was well fixed.

Anteroposterior plain radiograph of the pelvis taken three years after the left hip reconstruction. There has been no migration of the cup-cage construct. Note that the right side has been revised. 

Nala was very happy with the outcome of her left sided hip revision. After a revision to the right hip, Nala was able to walk several miles and was no longer requiring analgesics. We were both very happy with the outcome of her anti-protrusio cage.

The Verdict

To be completed by PROF

Evidence for this treatment

  • Needed

In closer detail

  • Needed

Related cases…

  • Needed