CASE 8: Revision of a metal-on-metal hip for adverse reaction to metal debris (ARMD) using a bearing exchange

The Story

“Gail was having awful pain in her right hip which had been worsening for 4 years - to the point where she was using a walking stick to mobilise. Bilateral metal-on-metal Pinnacle S-ROM total hip replacements had been in situ for 8-years on the right and 6-years on the left.

For Gail, the greatest challenge was working out the source of her pain. We had to consider loosening, an infection and an adverse reaction to metal debris. This required a detailed work-up.”

The Investigation:

On clinical examination:

• Very painful right hip movements

• Reduced range of movement on the right

• Able to straight leg raise on the right but this caused considerable discomfort

Her oxford hip scores were 17/48 and 29/48 for the right and left hips respectively.

Blood inflammatory markers demonstrated a normal ESR (26mm/Hr) and a borderline CRP (10mg/L). Blood metal ion levels demonstrated a normal level (for a patient with bilateral metal on metal hip implants) of cobalt (2.8ppb) and chromium (3.5ppb). Greater than or equal to 7ppb of either cobalt or chromium is defined as concerning by the MHRA (for a unilateral MOM hip). Due to her borderline raised inflammatory markers, an aspiration of the right hip was performed however no growth was seen after extended cultures, so infection was unlikely.

The Evidence

Anteroposterior plain radiograph of the pelvis demonstrates bilateral well fixed and well positioned S-ROM Pinnacle MOM hip replacements. Both cups and stems appear stable and well positioned.

Metal artefact reduction sequence (MARS) MRI demonstrating a large pseudotumour posterior to her right hip. This is an area of inflammation secondary to metal debris which can mimic an infective process in the absence of infection (including raised inflammatory markers, despite no infection in some cases).

The Diagnosis

Gail had an adverse reaction to metal debris (ARMD) as a result of the metal on metal (MOM) bearing in used in her right hip replacement.

The Plan

In the presence of the well fixed Pinnacle cup and SROM stem on the right side, we planned to perform an isolated liner exchange, changing the bearing from metal-on-metal to ceramic-on-polyethylene. As part of the same operation, we aimed to excise Gail’s pseudotumour, as fully as possible (but inevitably some will be left behind).

The Operation

We used a posterior approach to access the right hip and the pseudotumour. We excised as much of the joint lining and the pseudotumour as possible. As with all of our procedures where a possible infection may be the cause, we sent 5 samples of the hip capsule for extended microbiological culture.

We then extracted the femoral head. With an SROM stem this is normally a straightforward task. With other stems, there can be cold welding of the stem to the femoral head (such as the Biomet Magnum head and Taperloc stem) in which case, stem extraction is required. The metal liner was then extracted from the Pinnacle cup using a Depuy “alternate bearing extractor” but it is also possible to extract the liner using a sucker and two simultaneous cup impactors that repeatedly impact the cup rim and vibrate the liner loose from the shell.

We completed the procedure by inserting a 52mm polyethylene liner and a 36mm ceramic head with a titanium sleeve. The joint was relocated and then washed out before the musculature, fascia and skin were sutured.

The Outcome

Anteroposterior plain radiograph demonstrating the new liner of the right THR. The head bearing surface is visible on the right side because the right acetabular liner is now made of polyethylene.

EOS imaging taken 18-months after Gail’s operation. When compared to the post-operative image, there is no migration of either implant and her legs remain the same length.

The Verdict

“Components such as the acetabular shell and femoral stem, can be retained if they are well fixed to bone, well orientated and not infected.”

• In closer detail

  Bergiers S, Hothi HS, Henckel J, Eskelinen A, Skinner J, Hart A. Wear performance of retrieved metal-on-metal Pinnacle hip arthroplasties implanted before and after 2007. Bone Joint Res. 2018;7(11):595-600.

  Colen S, Kuiper JW, Thys P, De Schuyffeleer S, Mulier M. Pinnacle(R) modular metal-on-metal articulation in primary total hip arthroplasty: mid-term results of 195 cases. Acta Orthop Belg. 2018;84(4):407-14.

  Hothi HS, Eskelinen AP, Berber R, Lainiala OS, Moilanen TP, Skinner JA, et al. Factors Associated With Trunnionosis in the Metal-on-Metal Pinnacle Hip. J Arthroplasty. 2017;32(1):286-90.

  Hothi HS, Whittaker RK, Meswania JM, Blunn GW, Skinner JA, Hart AJ. Influence of stem type on material loss at the metal-on-metal pinnacle taper junction. Proc Inst Mech Eng H. 2015;229(1):91-7.

  Langton DJ, Sidaginamale RP, Avery P, Waller S, Tank G, Lord J, et al. Retrospective cohort study of the performance of the Pinnacle metal on metal (MoM) total hip replacement: a single-centre investigation in combination with the findings of a national retrieval centre. BMJ open. 2016;6(4):e007847.

  Matharu GS, Nandra RS, Berryman F, Judge A, Pynsent PB, Dunlop DJ. Risk factors for failure of the 36 mm metal-on-metal Pinnacle total hip arthroplasty system: a retrospective single-centre cohort study. The bone & joint journal. 2017;99-B(5):592-600.

• Evidence for this treatment

  Bozic KJ, Kurtz SM, Lau E, Ong K, Vail TP, Berry DJ. The epidemiology of revision total hip arthroplasty in the United States. J Bone Joint Surg Am. 2009;91(1):128-33.

  Patel A, Pavlou G, Mujica-Mota RE, Toms AD. The epidemiology of revision total knee and hip arthroplasty in England and Wales: a comparative analysis with projections for the United States. A study using the National Joint Registry dataset. The bone & joint journal. 2015;97-B(8):1076-81

• Related Cases

  Please see our other cases of revision surgery for metal debris disease (due to cobalt-chromium debris arising from metal on metal bearing surfaces, metal on titanium taper junction surfaces, cemented stem surfaces)