Session III - Clinically Relevant Research

Metal Sensitivity in Patients with Orthopedic Injuries

Marc Swiontkowski, MD, Julie Agel, ATC, John Schwappach, MD, Patrick McNair, MD

Harborview Medical Center, Seattle, Washington, USA

Purpose: We endeavored to document the incidence of metal sensitivity and conversion to sensitivity in a group of trauma patients. Implant manufacturers are moving to titanium implants due, in part, to a perceived high risk of allergy to the components of stainless steel.

Materials and Methods: Since October 1, 1995, patients 18 years of age and older with no history of prior implant placement, admitted to Harborview Medical Center (Seattle, Washington) via the emergency department and with the potential to receive a stainless steel implant were eligible to participate in this project. A metal sensitivity patch (Finn Chambers, Allerderm Laboratories) was placed on the patients' skin for a minimum of 3 days. The metals tested were: Chromium, Cobalt, Nickel, Aluminum and Molybdenum. After three days the patch was removed by one of the authors. This test was repeated at a minimum of three months post surgical intervention. The second patch was either placed on the patient during a follow-up visit or sent to the patient by mail. All second readings were done by the patient and reported over the telephone.

Reactions were rated on a four point scale standardized by photographic images. The scale was: no reaction, a mild reaction (redness, induration), a moderate reaction (formation of small blisters), and a severe reaction (formation of large blisters).

Results: Five hundred fifty-three patients had a patch placed prior to operative intervention. Four hundred forty-five still had a patch on at the initial three day follow-up. Initial patches were primarily lost due to accidental removal by ancillary staff or the patient. Four hundred sixty-eight patients with initial results are displayed in Table 1.

Table 1:

Metal	Chromium	Nickel	Cobalt	Aluminum	Molybdenum
No Reaction	431	424	424	444	443
Mild	14	19	20	0	1
Moderate	0	1	1	1	1
Severe	0	1	0	0	0

The mean age of these patients was 38.93 s.d. 15.08 (range 18-84). There were 303 males and 142 females. Of these 445 patients, 185 had placement of a second patch. This group's initial and follow-up results are displayed in Table 2.

Table 2: Follow-up patch response.

Initial response/(follow-up response)

Metal	Chromium	Nickel	Cobalt	Aluminum	Molybdenum
No Reaction	184/(179)	174/(171)	177/(177)	185/(184)	185/(184)
Mild	1(6)	10(11)	8(7)	0(1)	0(1)
Moderate	0(0)	0(3)	0(1)	0(0)	0(0)
Severe	0(0)	1(0)	0(0)	0(0)	0(0)

The mean age of these patients was 38.54 s.d. 14.08 (range 18-79). There were 130 males and 55 females. The length of follow-up was 167.69 (90-464) days.

Chromium: Five patients who had no allergy to chromium at time 1 had a mild reaction at time 2. One patient had a mild reaction at both time 1 and time 2.

Nickel: Six patients who had no reaction to nickel at time 1 had a mild reaction at time 2. One patient had a moderate reaction. Four patients who had a mild reaction at time 1 had no reaction at time 2. Five patients had mild reactions at both time 1 and time 2 and 1 patient had moderate reactions at both time 1 and time 2.

Cobalt: Six patients with no reaction to cobalt at time 1 had a mild reaction at time 1, one patient with no reaction at time 1 had a moderate reaction at time 2. Seven patients with a mild reaction at time 1 had no reaction at time 2. One patient had a mild reaction at both times.

Aluminum/Molybdenum: One patient had a mild reaction to both aluminum and molybdenum at time 1 and time 2.

Discussion/Conclusion: Metal sensitivity does not seem to be prevalent in this population of patients. Furthermore, it does not seem apparent that allergies to the components of stainless steel or allergic conversion based on exposure is a common problem. Skin reactivity may be a different biologic response than deep tissue sensitivity, however.