Keywords
metallosis - metallosis treatment
The advent of joint replacement surgery has allowed patients with joint pathologies
to return to being pain-free and functional in the effected site to a level not previously
possible. As the number of patients seeking orthopedic intervention grows, joint arthroplasty
is becoming more common.
A potential risk of joint replacement surgery is metallosis, caused by the release
of metallic debris secondary to hardware failure. Metallosis can be either local or
systemic and has been observed at an estimated incidence of up to 5% in metal joint
replacement patients. Metallosis may present locally with pain, instability, and metallic
debris staining the local tissue. Systemically, metallosis has been linked to neurologic
complications (visual, hearing, and cognitive deficits), cardiac failure, and hypothyroidism.
Importantly, metallic debris can also have superficial manifestations of periarticular
skin tattooing, due to an adverse local tissue reaction. Although the structural component
of failed joint arthroplasty can be revised to improve pain, stability, and functioning,
any skin tattooing secondary to metallosis presents the treating physician with clinical
challenge.
Two factors determine the survivorship of an implant: metallurgy and implant design.
Both factors are interrelated and help to determine biological responses to the implantation
of a prosthesis.[1] Metallurgy refers to the physical and chemical behavior of metallic elements. The
most common materials used for orthopedic prostheses include stainless steel, chromium-cobalt
alloy, and titanium alloy, each of which may contain nickel, cobalt, chromium, titanium,
molybdenum, aluminum, iron, manganese, copper, tungsten, or vanadium.[2] Implant design and loading vectors associated with that design also contribute to
implant survivorship.
This study presents a review of pertinent medical literature on the subject of metallosis.
Case Study
Jayasekera et al reported a 74-year-old woman who presented to her general practitioner
after experiencing 2 years of worsening metallic skin tattooing, pain, and swelling
to her left knee ([Fig. 1]).[3] Six years earlier, the patient had left total knee replacement, with a metal-backed
implant to resurface her patella, and an anterior knee midline scar.
Fig. 1 Skin discoloration and joint effusion (arrow) after knee arthroplasty failure, prior
to revision surgery.
The patient underwent joint revision, where periarticular stained soft tissues of
the knee were debrided (primarily joint capsule/synovium), and the patella component
of the prosthesis was replaced with an alternative. The patient remained pain-free
with good function at 5-year follow-up, but had ongoing concern about cosmesis of
her persistent skin tattooing, which remained untreated.
Materials and Methods
A comprehensive literature search was performed, following the PRISMA 27-point checklist,
and taking into consideration the guidance offered by the Cochrane Collaboration.
We completed a systematic review of PubMed, Embase, MEDLINE, and the Cochrane Library,
from 1975 to June 2015. We used the search terms “metallosis,” “treatment of metallosis,”
“traumatic tattooing,” “tattoo removal,” and “tattoo treatment,” which returned 1,806
articles. Screening of the title and abstract was performed by two of the authors
(S.T. and C.G.), which helped identify the relevant articles. From these, an additional
search was performed through reference lists of the retrieved articles. Our search
yielded 10 articles for our review of the treatment of skin discoloration following
metallosis.
Results
Twelve studies matched the search criteria and were included in our review. Four studies
dealt with clinical cases of metallosis. Three different studies dealt with the histopathology
of the condition, and the remaining five studies were related to assessing treatment
of skin tattooing.
Metallosis Post–Joint Arthroplasty
Babis et al reported a 70-year-old woman with a right total hip replacement, with
a history of developmental dysplasia of the hip from childhood, who presented with
severe pain and periarticular skin metallic staining.[4] On joint revision, the porous tantalum acetabular component of the hip replacement
had failed. Serum levels of tantalum had increased 2,000 fold and subsequently dropped
by 25% 6 months after re-revision (tantalum implants were reused).
Munro-Ashman and Miller patch-tested 35 patients who suffered metal-to-metal prosthesis
failures.[5] A total of 35 patients in this unsatisfactory group were patch-tested; 16 were positive
to metals, 13 to cobalt, 4 to nickel, and 2 to chromate. Only two patients showed
any skin lesions—one a localized dermatitis around the knee joint from nickel sensitivity,
and one with widespread scattered circular erythematous lesions suggestive of a generalized
allergic vasculitis from cobalt exposure.
The authors recognized that roughly half of arthroplasty failures may be related to
metal sensitivities (particularly cobalt) and suggested taking a careful history for
metal sensitivity and patch-testing high-risk patients with the metals. Titanium 318
was suggested as a satisfactory substitute for cobalt chrome alloy if reactions were
encountered or anticipated.
Bradberry et al systematically reviewed toxicities attributed to metals released from
hip implants, surmising that high circulating concentrations of cobalt from failed
hip replacements could cause neurologic damage, hypothyroidism, and/or cardiomyopathy,
which may fail to reverse after joint revision or removal.[6]
Metallosis can lead to osteolysis and subsequent implant failure, which may be seen
in noninvasive plain radiography. An often nonspecific radiographic sign observed
is periprosthetic osteolysis; more specific signs that have been reported are the
“bubble,” “cloud,” and “metal-line” signs.[7]
[8] Serologic testing for metallic ions reveals elevated levels. A normal serum cobalt
level is around 0.19 μg/L, with levels greater than 5 μg/L posing risk of neurologic
and cardiac abnormalities.[9]
Histopathology of Metallosis
Asahina et al reported a 59-year-old woman with a background of rheumatoid arthritis
who experienced metallosis tracking to the distal end of the forearm, several centimeters
beyond the prosthesis location, several months after elbow arthroplasty.[10] The joint remained fully functional; she was pain-free and had no lymphadenopathy.
Histopathology showed fine brown-black particles dispersed in the dermis, phagocytosed
by macrophages, or else accumulating around eccrine glands and capillaries, indicating
an adverse reaction to metal debris. X-ray analysis of the tissue showed high levels
of iron, nickel, and chromium.
The authors theorized that problematic metallic particles in metallosis follow a random
diffusion throughout soft tissue. Macrophages then attempt to phagocytose these foreign
bodies following failure of the mechanism to remove them from dermal tissue. It was
also suggested that the origin of the metallic staining was secondary to precipitation
of the metallic particles from the instruments used during the arthroplasty procedure.
Matziolis et al noted a case of metallosis following a total hip replacement, where
histopathology showed numerous histiocytes and foreign body giant cells containing
fine metal (cobalt-chromium) particles and moderately dense lymphoplasmacytic infiltrates.[11] The metal particles appear as extracellular metal deposits or as debris in the cytoplasm
of histiocytes and foreign body giant cells (hematoxylin and eosin staining, ×400
focus).
Akimoto et al noted an 80-year-old woman, who presented with metallosis mimicking
a malignant skin tumor 6 years after right total hip arthroplasty.[12] Histology showed diffuse granulomatous inflammation, large lymphatic spaces, and
fine brown-black granules within the histiocytes (likely originating from the titanium
acetabular cup and screws). The authors considered that in this case, the granulomatous
tumorlike reaction was possibly a more severe immunologic reaction to the inflammatory
metallic debris products.
Treatment of Skin Tattooing with Laser Therapies
No articles were located assessing treatment of metallosis. However, articles assessing
treatment of other forms of cosmetic and traumatic skin tattooing were found.
Apfelberg et al compared treating decorative tattoos using argon laser with using
CO2 laser and mechanical debridement.[13] He found similar results, complication rates, and consequential histologic studies
between the two groups.
Bernstein et al treated a 60-year-old woman with a traumatic tattoo from a residual
deep dermal white braided suture (Polysorb, Covidien),[14] which presented as a green discoloration along the length of an elliptical surgical
scar from a basal cell carcinoma excision on the right upper lip. A 3-mm punch biopsy
showed green, vertically oriented pigment within the reticular and papillary dermis,
without any histologic evidence of a foreign body reaction. The discoloration was
treated with Q-switched ruby laser (694 nm for 28 nanoseconds) over two treatments
and cleared.
Troilius assessed the use of the Q-switched neodymium:yttrium aluminum garnet (Nd:YAG)
1,064-nm laser for treatment of 12 patients with traumatic tattoos after accidents.[15] It was found cosmetically successful for gravel, mascara, or high explosives in
two to five treatments. Asphalt, amalgam, and metal took 6 to 11 treatments for successful
treatment.
Gorouhi et al looked at the treatment of traumatic tattoos with Q-switched Nd:YAG
1,064 nm with spot size 4 mm, fluence of 7.96 J/cm2.[16] One 54-year-old man with sand and asphalt tattooing on his face following a bomb
explosion 15 years prior received the laser treatment. After a test area was performed,
one treatment gave excellent outcomes. No pigmentary or textual changes were noted.
Gorouhi et al theorized that these lasers may optimize tattoo removal either by increased
phagocytosis or through transepidermal elimination.[16] It was noted that multiple treatments with Q-switched lasers were required for deeper
traumatic tattoos.
Sunde et al looked further at the treatment of established traumatic tattoos.[17] The authors developed an animal model for traumatic tattoos where two levels of
wounds were made (shallow and deep). Each group consisted of five guinea pigs with
one consistent level of wounding. Four treatment methods were applied, including carbon
dioxide laser, argon laser, overgrafting, and dermabrasion. The results were evaluated
by trained observers on a gross basis. Although no statistically significant differences
were found within these small groups, clinical experience in a small group of patients
suggested that carbon dioxide laser may prove to be useful in the delayed treatment
of traumatic tattoos. Eight patients were treated over a 4-year period. Satisfactory
total or subtotal foreign body removal of various agents (road tar, cement, cooper
particles) was largely achieved.
Discussion
Metallosis is an uncommonly encountered complication of joint arthroplasty. The orthopedic
surgeon can provide initial management, including investigations for systemic involvement,
appropriate joint revision and tissue debridement, and referral to necessary specialties.
The surgeon should consider referral to the dermatologist for assistance in managing
the patient's cosmetic expectations after optimal surgical management has failed.
The orthopedic surgeon should also be cautious to recognize patients at increased
risk of sensitivity-based prosthetic failure and should consider use of the appropriate
compounds when initially assessing the patient.
Histologically, metallosis involves metallic particles migrating from the deeper periarticular
tissues superficially to the dermis, with varying immunologic reactions. There is
little in the current literature to recommend an optimal laser treatment; current
research looks at treatment of tattoo particles introduced superficially and less
likely to be concentrated in deeper tissues (as in metallosis).
Adequate treatments with the fractionated CO2 ablative laser, or the Q-switched Nd:YAG 1,064-nm laser, capable of either allowing
the particles to be released from the dermis (transepidermal elimination) or breaking
up the particles at least in the dermis, are likely to be successful. Although particles
deeper than the dermis would fail to be treated with laser, it is our view that the
dermal particles likely contribute greater to the appearance, increasing the probability
of laser treatment to be effective.
Because no current research into laser or other treatment of metallosis has been conducted,
clinical trials would be of benefit. This would help guide the physician toward optimal
therapy when addressing this condition.
Conclusion
We conclude that for successful management of skin metallosis, the orthopedic surgeon
must revise the arthroplasty, addressing all relevant factors, and seek referral to
the dermatologist as appropriate. Although pain and mechanical symptoms can be addressed
with joint revision, cosmesis is also important when considering the patient's best
interests and long-term outcomes. Although dermatologic literature regarding metallosis
treatment was not found, deduction from treating similar conditions can guide the
physician toward optimal management. Possible limitations to our review may include
the restrictions of the MEDLINE-based search, the lack of statistical analysis, and
the small number of studies considered. Given the relatively few studies assessed,
it is our opinion that a statistical analysis would not influence the findings of
our review.
Although other dermatologic treatment options exist (including dermabrasion, local
excision, and overgrafting), these modalities are likely suboptimal and require a
further evidence basis before being utilized to manage metallosis. We hope this review
stimulates further research, guiding future dermatologic investigation and trial of
treatment.
