CASE 24: Revision of a well-fixed femoral stem with adverse reaction to metal debris from modular neck corrosion, using a non-modular stem
The Story
“Inderpal presented to my clinic with severe pain and restricted movement in his left hip. Previously, he had undergone bilateral hip replacement surgery with modular necked femoral stems (titanium stems and cobalt-chromium neck segment with ceramic on ceramic bearings).
Revision was needed due to the inflammatory response of the hip tissues, caused by the metal debris released by corrosion between the stem and the neck segments (two different metals).
When planning revision hip surgery, which required removal of the well fixed stem due to the corroded modular neck junction, we were keen to preserve Inderpal’s femoral bone stock. With careful removal of the stem, our first choice was a primary femoral component, and our second choice was a longer revision stem.”
The Investigation
On examination in clinic, Inderpal had a severely reduced range of motion in his left hip secondary to pain. He struggled to walk across my clinic room and had a marked antalgic gait.
The Evidence
Anteroposterior plain radiograph demonstrating bilateral hip replacements with modular necks. There is no radiographic evidence of stem loosening on either side
MARS MRI demonstrated an adverse reaction to metal debris surrounding both of Interpal’s total hip replacements. In this case, the source of the adverse reaction to metal debris was not the bearing, this was ceramic on ceramic; it was instead the corrosion between the modular neck and the femoral stem. The left hand side was worse, so we opted to revise the left initially, with the plan to revise the right at a later date.
The Diagnosis
Adverse reaction to metal debris, worse on the left hand side, secondary to corrosion of the junction between the modular neck and the femoral stem. This corrosive process would have been accelerated by alloy coupling due to different alloys being used to produce the modular neck and femoral stem.
The Plan
We planned to use a standard primary Corail stem for Inderpal’s revision procedure. To avoid the need for an extended femoral osteotomy, we planned to remove his well fixed stem by using flexible osteotomes.
The objective of this approach is to preserve surrounding femoral bone stock allowing us to use smaller primary components over revision components.
Corail Stem
The Operation
We used a posterior approach to access Inderpal’s hip and sent off five samples for culture. The acetabular side was prepared and reamed to 53mm to accept a 54mm press fit Gription socket. A single screw was used to improve fixation and a polyethylene liner inserted.
The femoral side was then prepared. A crucial step was the use of flexible osteotomes, a Midas rex drill with pencil reamer and a solid stem extractor. A primary, uncemented and collared Corail stem was implanted. A single cerclage wire was used to protect the femoral bone (insulted during removal of the stem) during impaction of the well fitting primary stem. After testing the left leg for stability, range of motion and leg length discrepancy, a ceramic head was selected. The surgical site was extensively washed and closed.
The Outcome
Anteroposterior plain radiograph of Inderpal’s pelvis demonstrating a left sided Corail stem in situ with a cable to protect the femur during impaction of a well fitting, uncemented stem into potentially vulnerable bone (after removal of a well-fixed stem).
Anteroposterior plain radiograph of the pelvis taken two years after the left revision procedure. Note that the right side has been revised. There is radiographic evidence of osseointegration surrounding the left sided Corail stem in Gruen zones 1, 2, 6 and 7.
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Inderpal was very happy at his 6-week follow-up appointment. He was able to walk without pain and return to his normal daily activities. The use of a primary stem helped to preserve Inderpal’s bone stock and led to an excellent post-operative result.
The Verdict
“At 2-years after his procedure, Inderpal had a well-functioning left hip and an excellent appearance on the plain radiograph of the implant (see above). Bone conservation with a primary stem was a good option for him.”
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Please see these other cases that feature the techniques used for femoral stem extraction:
