Laser-assisted Fluorescent Angiography to Assess Tissue Perfusion in the Setting of Traumatic Elbow Dislocation

Introduction. In the surgical setting, the most accepted technique for measuring tissue perfusion includes subjective identification, with visual and tactile inspections of the tissue, performed by a surgeon. Recently, fields such as ophthalmology, plastic surgery, and other surgical specialties, such as cardiac, vascular, and transplant surgery, have seen the emergence of laser-assisted fluorescent angiography (LAFA) to visualize real-time tissue perfusion during procedures. Case Report. The case of an 80-year-old woman, who presented with a wound over the left medial elbow following a subacute recurrent elbow dislocation, illustrates the use of this technology in the field of orthopedics. Initially, the patient was treated at an outside facility where the dislocation was reduced, and she was placed in a long arm splint. With concern of recurrent dislocation and wound development, she presented to the authors with a complex wound measuring about 9 cm x 5 cm with variable thickness ranging from 0 mm to 5 mm in depth.  Her initial emergent irrigation and debridement and wound management was assisted by LAFA and the administration of indocyanine green to guide debridement and determine viable wound margins.  After staging with external fixation and a negative pressure wound dressing, she later returned for skin grafting and healed uneventfully. Conclusions. In conjunction with plastic surgeons, the orthopaedic team utilized LAFA for debridement that led to both a successful wound repair and skin grafting procedure.

As technology continues to progress, it brings new advancements that improve positive outcomes in surgery. As part of the wound healing process, an affected area can be overcome with necrotic tissue, thus necessitating wound debridement (such as surgery to remove devitalized and necrotic tissue, foreign materials, and bacteria) to promote healing. Dead or dying tissue inhibits the development of new tissue as it spatially limits tissue expansion and unnecessarily diverts vital resources from the immune response. Necrotic tissue can offer an anaerobic environment that is primed for infection, creating potential spaces where collections or abscesses can develop. The loss of skin flaps due to ischemia and necrosis following surgery can lead to a larger tissue deficit that requires additional repair.^1,2

Currently, the adequacy of debridement relies on clinical judgement, which is the most accepted method for evaluating tissue perfusion at the local or microvascular level.³ This method typically involves subjectively assessing the tissue color, capillary refill, and dermal bleeding¹; however, this approach has been shown to be unreliable for the determination of skin flap perfusion.^4,5 Even experienced surgeons can lack accuracy in their clinical judgment, potentially leading to poor outcomes. There is a need for the development of improved methods to assess the adequacy of surgical debridement in a quantifiable manner. Multiple other modalities have been tested (eg, Doppler devices, tissue oximetry, and fluorescein), but none have become an accepted standard.¹

Literature in the plastic surgery field^6-19 has demonstrated the use of laser-assisted fluorescent angiography (LAFA) to visualize real-time tissue perfusion using the plasma protein dye indocyanine green (ICG). This dye has been commonly used in ophthalmologic procedures,^20,21 but more recently, it has been adapted for use in cardiac, vascular, and transplant surgeries.^22-26 Indocyanine green has an excellent safety profile with adverse effects at the rate of 1 in 42 000 patients.^27,28 In addition to safety, unlike many other fluorescents, ICG has a short half-life of 3 to 5 minutes, allowing for multiple evaluations throughout the procedure.²⁹

There are several LAFA cameras available for intraoperative use. This technology allows surgeons with access to a near-infrared camera to clearly visualize microvascular blood flow and perfusion in tissue intraoperatively with very little background emission from biological tissues and fluids. The possibility of real-time analysis adds valuable information that assists in decision-making, leading to fewer complications and lower health care costs.^30,31 Fast and accurate decision-making for tissue viability is essential for all surgeons, including those in the orthopedic field, but LAFA has limited use and review within the orthopedic literature.

In this paper, intraoperative fluorescent detection was used to identify vascular flow in a patient with a traumatic elbow dislocation.

An 80-year-old Caucasian woman presented with a large wound on the medial aspect of her left elbow. She reported having sustained an elbow dislocation the previous week. The dislocation was reduced at an outside facility and placed into a long arm splint. She followed up with her primary care physician and then referred to Ruby Memorial Hospital, West Virginia University Medicine (Morgantown, WV), via the emergency room for further evaluation and concern of recurrent dislocation and subsequent wound development.

Radiographs demonstrated an obvious elbow dislocation (Figure 1A, 1B). Her dressings were removed to reveal a large, irregular, fibrinous wound over the medial aspect of the elbow (Figure 1C) measuring 3.5 cm x 3.5 cm and exposing the articular surface; however, the entire complex wound measured about 9 cm x 5 cm with variable thickness ranging from 0 mm to 5 mm in depth. The patient received intravenous (IV) antibiotics (cefazolin 1 g at presentation and then continued every 8 hours for 48 hours postoperatively) and treatment options were discussed with the patient and her family. The patient agreed to proceed to the operating room (OR) and was taken within 6 hours of presentation for an emergent irrigation and debridement and open reduction and external fixation of her elbow.

The procedure began with excision of the obviously necrotic tissue on the medial elbow (Figure 1D), then the wound and exposed joint were debrided. The joint was irrigated copiously and reduced with manual in-line traction with fluoroscopic assessment. A medium external fixation device was placed to stabilize the joint.

Intraoperatively, plastic surgery was consulted for assistance with the critical-sized wound. The authors used the SPY Elite Fluorescence Imaging System (Stryker, Kalamazoo, MI) to assess the vascularity of the remaining tissue defect.

In this case, a total of 25 mg of ICG powder was diluted in 10 mL of normal saline, yielding a concentration of 2.5 mg/mL. A 3-mL injection of this solution was administered by the anesthesiologist into a peripheral IV line followed by a 10-mL saline flush. The charge-coupled device (CCD) fluorescent imaging system was used to detect the ICG (Figure 2A). This dye, when excited by an 805-nm laser, emits fluorescence; the intensity of emission is recorded by a camera that shows real-time perfusion. The SPY-Q (Stryker) computer embedded in this fluorescent imaging systemgives a percentage perfusion score comparing the most viable area to adjacent areas.

In the present case, most of the tissue appeared well perfused and healthy with the lowest relative perfusion level reaching 66%. One more proximal triangular area demonstrated full necrosis with a relative perfusion of < 10% and was subsequently further debrided (Figure 2B). The medial capsule and tissue were closed over the exposed joint, and preliminary closure with a negative pressure dressing (NPWT; V.A.C. Therapy; KCI, an Acelity Company, San Antonio, TX) was obtained.

Five days later, after her initial debridement including the use of the imaging device, the patient was taken back to the OR for washout and placement of Integra Matrix Wound Dressing (Integra Lifesciences, Plainsboro, NJ) as a substitute graft and NPWT set at -100 mm Hg for 5 weeks. She was discharged on the first postoperative day to a skilled nursing facility for rehabilitation with follow-up appointments with the authors’ upper extremity specialists and plastic surgery.

After 6 weeks of progressing her elbow from flexion to approximately 25° short of full extension slowly through a range of motion, the external fixation device was removed. During placement of a full-thickness skin graft (FTSG), the wound was irrigated and healthy granulating tissue was evident over the previously placed matrix overlying the initially exposed joint and muscle. At that time, the wound measured 7 cm x 4 cm, with healthy granulating tissue to the level of the subcutaneous tissue. The FTSG was harvested from the lower abdomen, measuring 7 cm x 4 cm, and sutured to the wound bed.

At the 6-month follow-up from her initial surgery, the patient’s wound healed uneventfully. At present, her elbow is ligamentously stable and has had no further episodes of recurrent dislocation. Given the degree of injury, she has excellent range of motion; she lacks 15° of full extension and can flex her elbow to about 110°. Her skin graft has healed with no evidence of tissue failure or infection (Figure 3).

In any surgical procedure, skin perfusion must be significant and adequate to avoid further wound complications. Currently, the standard for determining tissue perfusion is highly subjective. It takes experience to detect the changes in tissue color, flap temperature, or other parameters necessary to determine local perfusion. Surgical fields such as ophthalmology and plastic and reconstruction surgery have used LAFA to reduce the necessity of this subjectivity. There currently are no set standards in the orthopedic literature as to the threshold indicating viability. However, studies in the plastic surgery literature have shown that skin perfusion ≤ 25% is indicative of skin flap necrosis; the resection of these areas will lead to a lesser likelihood of remaining nonviable tissue.^10,11

To date, LAFA has had limited use in orthopedics. In 2015, Wyles et al³² evaluated the perfusion borders and ischemia to guide wound management in a series of knee reconstructions. Later, the same group³³ used LAFA to measure the effectiveness of different wound closure techniques following total knee arthroplasty.These cases support the initial use of this technology in the field of orthopedics for assessment of vascularity and wound closure.

The fluorescence imaging system consists of a CCD camera, a laser light source, and a distance sensor. The laser operates at a power density of 40 mW/cm², below the threshold of 200 mW/cm² known to cause tissue damage. The camera is attached to the mobile processing computer through an articulating arm that allows for intraoperative positioning and calibrated to recognize the fluorescence of ICG. The ICG is water soluble with an excitation range of 750 nm to 800 nm and an emission range of 800 nm to 810 nm in blood. It binds with plasma proteins and is rapidly distributed throughout the vasculature. Indocyanine green imaging can show perfusion in the dermis and superficial tissues with a depth of 1 cm. The typical ICG dose of 0.15 mg/kg to 0.30 mg/kg (usually 7.5 mg/injection) allows for repetitive dye administration.³⁰

The timing of dye administration is important and should be administered through IV access followed by a 10-cc flush. The use of additional dyes such as methylene blue, certain patient characteristics (smoking, chronic vascular changes), and the use of modalities such as vasoconstrictors (epinephrine) may impact the ability to detect perfusion. In addition, repeated administration of ICG may lead to residual background signal, especially in the setting of venous congestion.¹

There is limited literature available relating the fluoroscopic intensity with the risk for developing postoperative complications. Since this is the first case utilizing LAFA in the setting of a subacute trauma, a limitation to the study is the lack of clinical guidance for intraoperative use of the fluorescence imaging system. There are no data demonstrating the relative fluorescent intensities that will lead to reperfusion and what intensities will result in necrosis. Using the current literature, some researchers have developed procedural and technical recommendations for the use of LAFA in many reconstructive surgical procedures.¹

Although these recommendations are not intended to be authoritarian, they provide general principles for the evaluation of tissue perfusion during reconstructive procedures. No such guidelines exist in the field of orthopedics. Also, the results and success stemming from the subacute traumatic setting may differ from an acute traumatic experience. Further research needs to examine the use of LAFA in the acute traumatic orthopedic setting.

This case demonstrates the importance and potential benefits of using intraoperative fluorescent detection of microvascularity in an orthopedic case. In conjunction with plastic surgeons, this case utilized LAFA for debridement in a traumatic elbow dislocation with significant tissue loss along the medial elbow. After the ICG was administered, local perfusion assessments guided the debridement in the OR, leading to successful wound treatment and skin graft procedure.

The authors would like to thank Suzanne Danley for her assistance and support in the preparation of this manuscript.

Authors: Matthew J. Dietz, MD¹; Joseph T. Hare, MS II¹; Cristiane Ueno, MD²; Bonhomme J. Prud’homme, MD¹; and Jonathan W. Boyd, PhD¹

Affiliations: ¹Department of Orthopaedics, West Virginia University School of Medicine, Robert C. Byrd Health Sciences Center, Morgantown, WV; and ²Department of Surgery, Division of Plastic and Reconstructive Surgery, West Virginia University School of Medicine, Robert C. Byrd Health Sciences Center

Correspondence: Matthew J. Dietz, MD, Assistant Professor, West Virginia University, Department of Orthopaedics, PO Box 9196, Morgantown, WV 26506; mdietz@hsc.wvu.edu

Disclosure: The authors disclose no financial or other conflicts of interest.