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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 Reporttion and interferential current, are commonly usedtreatments in the physical therapy setting to assist A.M. is a 57-year-old man who first presented towith swelling control, muscle activation and our sports medicine clinic in February of 2003 withstrengthening, and pain control. To date, very little right knee pain. Plain films of the right kneeinformation 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 ofbeen reported in the literature. We report a case nonoperative therapy was prescribed, including theof 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
Electrical Stimulation for Unicompartmental Knee Arthroplasty ! Ford et al 951discharged on postoperative day 3 (Fig. 1). At his 2-week postoperative visit, his wound was healingwell. He was ambulating with assistance and had arange of motion from 08 to 1108. He also had a traceeffusion in the knee. At his 4-week postoperative visit, he presentedwith continued pain and swelling. He denied anyother symptoms. Physical examination revealed noerythema or warmth. His incision was healed.Range of motion was À28 to 908. A moderateeffusion was present. Moderate quadriceps atrophyand poor quadriceps activation were noted. Radio-graphs showed satisfactory component positionand fixation. An aspiration was performed, andthe aspirate was negative for infection or inflam-matory process. At that time, more physicaltherapy was prescribed. Modalities, including elec-trical stimulation for edema control, quadricepsactivation and strengthening, and interferentialcurrent for pain control, were ordered. During Fig. 2. Configuration of electrodes over the proximalsubsequent 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 anysented with redness and a 2.5 Â 2 cm full- effusion. Because of the wound proximity to histhickness eschar slightly lateral to the incision arthroplasty, he was placed prophylactically onover the distal patellar tendon (Fig. 3). The patient Keflex and monitored closely for any signs ofstated the eschar developed shortly after using infection. Plastic surgery was consulted, andinterferential current during a physical therapy the patient was instructed in appropriate woundsession. The characteristics of the eschar were care, including moist to dry saline gauze 3 timesconsistent with that of an electrical burn. The daily. The burn continued to heal well, and atpatient did exhibit markedly improved quadriceps his 6-month follow-up, the burn eschar wasFig. 1. Postoperative anteroposterior and lateral radio- Fig. 3. View of the full-thickness burn over proximalgraphs of the right knee showing unicompartmental tibia. Note correlation of electrode placement over thisarthroplasty. area and proximity to the metal implant.
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  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 infrapatellarFig. 4. View of the healed area 6 weeks after the ini- branch of the saphenous nerve distribution as welltial 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 electricalcompletely healed, without sequelae (Fig. 4). Thepatient was noted to be asymptomatic, with awell-functioning arthroplasty. Discussion Sparse data have been reported in the literatureregarding burns after treatment with electricalmodalities in physical therapy. Balmaseda et al reported 2 cases of tissue burns in spinal cordpatients receiving electrical stimulation therapy. Ina retrospective questionnaire study, Nadler et al reported on complications encountered by athletictrainers, with burns accounting for 40% of com-plications caused by electrical stimulation. To ourknowledge, this is the first report in the literature ofa 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 tibialimplant to the skin and the patient’s decreasedsensation in the distribution of the infrapatellarbranch of the saphenous nerve, which occurscommonly with the incision necessary for knee Fig. 5. Suggested electrode configuration for electricalarthroplasty. It was felt that the proximity of the modalities.
Electrical Stimulation for Unicompartmental Knee Arthroplasty ! Ford et al 953modalities for the treatment of pain and swelling Referencesafter unicompartmental knee arthroplasty. Thisreport 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 caseate 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 aHowever, we do suggest an alternate electrode national survey of athletic trainers. Arch Phys Medplacement to minimize the risk of skin complica- Rehabil 2003;84:849.tions in arthroplasty patients.