1) A patient experienced a full-thickness burn on his proximal tibia after undergoing a unicompartmental knee arthroplasty and receiving electrical stimulation and interferential current therapy during physical rehabilitation. 2) The burn likely occurred because the electrodes for the interferential current were placed directly over the patient's proximal tibia, in close proximity to the metal tibial implant and an insensate area of skin. 3) While electrical modalities can be useful in rehabilitation after knee arthroplasty, electrodes should be placed away from metal implants and insensate skin areas to avoid potential burns.

1. The Journal of Arthroplasty Vol. 20 No. 7 2005
Case Report
Full-thickness Burn Formation After the Use of
Electrical Stimulation for Rehabilitation of
Unicompartmental Knee Arthroplasty
Kerry S. Ford, MD, Michael W. Shrader, MD, Jay Smith, MD,
Timothy J. Mclean, PT, and Diane L. Dahm, MD
Abstract: Electrical stimulation and interferential current are commonly used
modalities in the physical rehabilitation of patients who have undergone joint
arthroplasty surgery. Sparse data are available in the literature regarding potential
complications from using these modalities. We report on a patient who underwent a
unicompartmental knee arthroplasty with a subsequent full-thickness skin burn
over the metal implant after electrical stimulation and interferential current
modalities in physical therapy. Key words: electrical stimulation, interferential
current, case report, joint arthroplasty, burn.
n 2005 Published by Elsevier Inc.
Electrical modalities, including electrical stimula- Case Report
tion and interferential current, are commonly used
treatments in the physical therapy setting to assist A.M. is a 57-year-old man who first presented to
with swelling control, muscle activation and our sports medicine clinic in February of 2003 with
strengthening, and pain control. To date, very little right knee pain. Plain films of the right knee
information on possible side effects and compli- showed moderate to severe degenerative arthritis,
cations from the use of electrical modalities has primarily of the medial compartment. A trial of
been reported in the literature. We report a case nonoperative therapy was prescribed, including the
of a full-thickness burn over the anterior tibia use of an unloader brace, an exercise program,
after the use of interferential current in a patient activity modification, and the use of anti-inflam-
with a unicompartmental knee arthroplasty. matory medication. He continued to have signifi-
cant medial-sided knee pain, and he elected to
proceed with a unicompartmental arthroplasty in
November 2003. His medical history includes
hyperlipidemia. There was no history of diabetes
or peripheral vascular disease. The patient’s only
From the Mayo Clinic, SW, Rochester, Minnesota. medication was nabumetone. There was no history
Submitted July 28, 2004; accepted October 13, 2004.
No benefits or funds were received in support of the study. of corticosteroid use. He had no known allergies
Reprint requests: Diane Dahm, MD, Mayo Clinic E-14, 200 and was a nonsmoker.
1st Avenue Northwest, Rochester, MN 55901. A unicompartmental arthroplasty was performed
n 2005 Published by Elsevier Inc.
0883-5403/05/1906-0004$30.00/0 without complication; the patient had an un-
doi:10.1016/j.arth.2004.10.018 remarkable early postoperative course and was
950

2. Electrical Stimulation for Unicompartmental Knee Arthroplasty ! Ford et al 951
discharged on postoperative day 3 (Fig. 1). At his 2-
week postoperative visit, his wound was healing
well. He was ambulating with assistance and had a
range of motion from 08 to 1108. He also had a trace
effusion in the knee.
At his 4-week postoperative visit, he presented
with continued pain and swelling. He denied any
other symptoms. Physical examination revealed no
erythema or warmth. His incision was healed.
Range of motion was À28 to 908. A moderate
effusion was present. Moderate quadriceps atrophy
and poor quadriceps activation were noted. Radio-
graphs showed satisfactory component position
and fixation. An aspiration was performed, and
the aspirate was negative for infection or inflam-
matory process. At that time, more physical
therapy was prescribed. Modalities, including elec-
trical stimulation for edema control, quadriceps
activation and strengthening, and interferential
current for pain control, were ordered. During Fig. 2. Configuration of electrodes over the proximal
subsequent physical therapy sessions, the electro- tibia as they were placed on the patient for inter-
des for electrical stimulation were placed over the ferential therapy.
distal thigh, whereas the electrodes for interferen-
tial current were placed over the proximal tibia
(Fig. 2). activation and strength with range of motion
Five weeks postoperatively, the patient pre- from 08 to 1108. There was no longer any
sented with redness and a 2.5 Â 2 cm full- effusion. Because of the wound proximity to his
thickness eschar slightly lateral to the incision arthroplasty, he was placed prophylactically on
over the distal patellar tendon (Fig. 3). The patient Keflex and monitored closely for any signs of
stated the eschar developed shortly after using infection. Plastic surgery was consulted, and
interferential current during a physical therapy the patient was instructed in appropriate wound
session. The characteristics of the eschar were care, including moist to dry saline gauze 3 times
consistent with that of an electrical burn. The daily. The burn continued to heal well, and at
patient did exhibit markedly improved quadriceps his 6-month follow-up, the burn eschar was
Fig. 1. Postoperative anteroposterior and lateral radio- Fig. 3. View of the full-thickness burn over proximal
graphs of the right knee showing unicompartmental tibia. Note correlation of electrode placement over this
arthroplasty. area and proximity to the metal implant.

3. 952 The Journal of Arthroplasty Vol. 20 No. 7 October 2005
implant to the current led to an increase in local
skin temperature which was not recognized by the
patient because of his relative lack of sensation.
Similarly, the 2 burn complications Balmaseda et al
[1] published were in insensate patients.
Electrical stimulation and interferential current
are thought to be helpful in patients recovering
from knee surgery, including arthroplasty, to assist
with quadriceps activation and pain control. In this
patient, the goals of decreased swelling, decreased
pain, and improved quadriceps activation and
strength were achieved. We feel that there is still
a role for use of electrical stimulation and interfer-
ential current in the rehabilitation of patients with
knee arthroplasties; however, to avoid similar
complications, we suggest avoiding placing electro-
des directly over a metal implant and also suggest
placing electrodes only over areas of skin with
normal protective sensation.
In this patient, the interferential current electro-
des were placed directly over the proximal tibia,
hence over an insensate area and in direct proximity
to the metal tibial component (Fig. 2). We suggest
the use of an alternative electrode configuration,
away from the insensate area of the infrapatellar
Fig. 4. View of the healed area 6 weeks after the ini- branch of the saphenous nerve distribution as well
tial burn. as the metal implant (Fig. 5) to minimize the risk of
complications such as reported here.
We are reporting the complication of a full-
thickness skin burn from the use of electrical
completely healed, without sequelae (Fig. 4). The
patient was noted to be asymptomatic, with a
well-functioning arthroplasty.
Discussion
Sparse data have been reported in the literature
regarding burns after treatment with electrical
modalities in physical therapy. Balmaseda et al [1]
reported 2 cases of tissue burns in spinal cord
patients receiving electrical stimulation therapy. In
a retrospective questionnaire study, Nadler et al [2]
reported on complications encountered by athletic
trainers, with burns accounting for 40% of com-
plications caused by electrical stimulation. To our
knowledge, this is the first report in the literature of
a burn attributable to the use of electrical modal-
ities in the setting of knee arthroplasty.
Potential contributing factors to this complica-
tion include the proximity of the metal tibial
implant to the skin and the patient’s decreased
sensation in the distribution of the infrapatellar
branch of the saphenous nerve, which occurs
commonly with the incision necessary for knee Fig. 5. Suggested electrode configuration for electrical
arthroplasty. It was felt that the proximity of the modalities.

4. Electrical Stimulation for Unicompartmental Knee Arthroplasty ! Ford et al 953
modalities for the treatment of pain and swelling References
after unicompartmental knee arthroplasty. This
report should not discourage orthopedic surgeons
1. Balmaseda Jr MT, Fatehi MT, Koozekanani SH, et al.
from ordering this treatment regimen for appropri- Burns in functional electrical stimulation: two case
ate indications; in fact, our patient had a significant reports. Arch Phys Med Rehabil 1987;68:452.
decrease in pain and increase in range of motion 2. Nadler SF, Prybicien M, Malanga GA, et al. Compli-
and quadriceps activation as a result of his therapy. cations from therapeutic modalities: results of a
However, we do suggest an alternate electrode national survey of athletic trainers. Arch Phys Med
placement to minimize the risk of skin complica- Rehabil 2003;84:849.
tions in arthroplasty patients.