Adverse reaction to metal debris in a consecutive series of DUROM™ hip resurfacing: pseudotumour incidence and metal ion concentration

[The use of knee prostheses with a hypoallergenic coating is safe in the medium term : A randomized controlled study]

BACKGROUND

In Germany, patients with contact allergy to implant components usually receive coated joint arthroplasties. Whether the treatment using these hypoallergenic implants achieves comparable results to standard treatment with implants consisting of cobalt-chromium alloy (CoCr) implants is controversially discussed internationally and has rarely been investigated in the mid-term.

OBJECTIVES

Are there differences in blood metal ion concentrations, knee function, and patient-reported outcomes (PROM) between coated and standard implants?

MATERIAL AND METHODS

118 patients were randomized to receive either a coated or a standard implant. Knee function as well as patient-reported outcome measures were assessed. Metal ion concentrations in blood samples were additionally determined for chromium, cobalt, molybdenum, and nickel, preoperatively, one and five years after surgery.

RESULTS

After five years, it was possible to analyse the results of 97 patients. In metal ion concentrations, as well as PRO, consistently good results were seen, without any difference between the groups. While in 13 patients there was an increase in chromium concentration above 2 µg/l one year after surgery, there was no measured value above 1 µg/l after five years.

CONCLUSION

In our study, similar mid-term results were detected for coated (TiNiN) and standard (CoCr)TKA. With respect to metal ion concentrations and PRO there are no disadvantages in using coated TKA.

Large Soft-tissue Mass Formation After Revision Total Knee Arthroplasty: An Unusual Case of Adverse Reaction to Metal Debris and Review of the Literature

We report about the rare case of a patient who developed large soft-tissue mass formations related with revision total knee arthroplasty which was implanted 4 years prior. Owing to suspected periprosthetic joint infection, the prosthesis was removed and the lesions were resected, resulting in severe soft-tissue loss and temporary arthrodesis using a poly(methyl methacrylate) spacer. Histological analysis revealed a type VI periprosthetic membrane. The situation was further complicated by wound infection requiring multiple revision surgeries. After discussion and evaluation of the available treatment options, the decision for an above-the-knee amputation was made. The tissue reaction resulting in these soft-tissue lesions is referred to as an "adverse local tissue reaction." Wear-induced lesions after total knee arthroplasty, especially of this magnitude, are very rare and difficult to treat.

Metal Ion Release after Hip and Knee Arthroplasty - Causes, Biological Effects and Diagnostics

All metal implants in human bodies corrode which results in metal ions release. This is not necessarily a problem and represents for most patients no hazard. However, if a critical metal ion concentration is exceeded, local or rarely systemic problems can occur. This article summarizes the mechanisms of metal ion release and its clinical consequences. Several situations can result in increased metal ion release: metal-on-metal hip arthroplasties with increased wear, increased micromotion at taper interfaces, direct metal-metal contact (polyethylene wear, impingement), erroneously used metal heads after ceramic head fracture. Possible problems are in most cases located close to the concerned joint. Furthermore, there are reports about toxic damage to several organs. Most of these reports refer to erroneously used metal heads in revisions after a broken ceramic head. There is currently no evidence of carcinogenic or teratogenic effects of implants but data is not sufficient to exclude possible effects. Cobalt and chromium blood levels (favorably in whole blood) should be measured in patients with suspected elevated metal ions. According to current knowledge levels below 2 µg/l seem to be uncritical, levels between 2 and 7 µg/l are considered borderline with unknown biological consequences and levels above 7 µg/l indicate a local problem which should be further diagnosed. Metal ion levels always need to be interpreted together with clinical symptoms and imaging results.

Similar outcome during short-term follow-up after coated and uncoated total knee arthroplasty: a randomized controlled study

PURPOSE

Patients with known hypersensitivity to metals often require hypoallergenic TKA implants. Coating of a standard implant is a common solution, and although in vitro tests have demonstrated reduction of polyethylene wear for these coatings, it is still unknown whether these implants have any clinical benefit. This study was initiated to investigate metal ion concentrations, knee function and patient-reported outcome (PRO) after coated and uncoated TKA.

METHODS

One hundred and twenty-two (122) patients were randomized to receive a coated or a standard TKA and, after exclusions, 59 patients were included in each group. Knee function and PRO were assessed with validated scores up to 3 years after surgery. Metal ion concentrations in blood samples were determined for chromium, cobalt, molybdenum and nickel, preoperatively and 1 year after surgery.

RESULTS

Chromium concentrations in patient plasma increased from a median of 0.25 to 1.30 µg/l in the standard TKA group, and from 0.25 to 0.75 µg/l in the coated TKA group (p = 0.012). Thirteen patients (3 coated, 10 standard TKA) had chromium concentrations above 2 µg/l. The concentrations of cobalt, molybdenum and nickel did not change. Patient-reported outcome measures (PROM) demonstrated a substantial improvement after TKA, without any differences between the groups.

CONCLUSION

The increase in chromium concentration in the standard group needs further investigation. If surgeons use coated implants, they can be confident that these implants perform as well as standard implants.

LEVEL OF EVIDENCE

I.