Application of Indocyanine Green Angiography for Closed Operative Calcaneus Fractures

Fractures of the calcaneus comprise 2% of all adult fractures. These fractures make up 60% of all tarsal injuries, the majority of which are closed, displaced intra-articular fractures. Despite the injury's prevalence, dispute over the appropriate method of treatment remains ongoing. Several studies have shown that an open, surgical approach is superior to either a non-surgical or percutaneous approach with regard to restoring proper alignment and structure of the hindfoot, depending on the severity of the displacement, and provided that certain patient conditions do not preclude surgery. Adequately restoring hindfoot structure is paramount to good clinical outcome; not only is proper alignment integral for fully recovering physiological functionality, but also in preventing further complications such as subtalar arthritis that present commonly in malunited calcaneal fractures.

Though literature may show that open reduction and internal fixation (ORIF) techniques provide a better long term outcome of severely displaced intra-articular fractures, proponents of both non surgical and percutaneous approaches argue that the superiority of the outcome may be mitigated by the fact that open surgical procedures are laden post operatively with numerous wound complications. These complications include, but are not limited to, both deep and superficial infections resulting in slough, dehiscence, necrosis, and erythema in and around the surgical site. Managing infections of the surrounding soft tissue and vasculature of the calcaneus following operative treatment indeed seems to present a great challenge to treating physicians, with wound healing complications present in 2-25% of cases.

A necessity for surgical wound repair is adequately vascularized tissue, which can be difficult to come by during closure of the wound due to the undermining and displacement of soft tissue during surgery. Sufficiently perfused soft tissue can also be difficult to differentiate from tissues that are inadequately vascular based on traditional clinical criteria such as color, warmth, and dermal bleeding. The degree of this avascularity can depend on many factors relating to the patient, necessitating studies be conducted identifying what factors place a prospective patient at a higher risk for developing wound healing problems post operatively. Studies of this nature thus far have noted that factors such as age, sex, height, weight, Bohler's angle, tobacco usage, and pre-existing conditions such as diabetes, vascular disease, and immune deficiencies may be indicative of increased likelihood for developing post surgical complications. Another risk factor of particular interest is the timing of surgery after the incidence of injury. Current literature regarding treatment of hindfoot injuries shows a moderate degree of uniformity, advocating a delay in operative measures until the soft tissue swelling around the injury has had time to subside: a window of approximately 7-14 days after injury. Additionally, in their investigation of Bohler's angle as a predictor for wound healing complications, Shuler and colleagues noted the pre and post operative Bohler's angle differential to be a significant predictor of developing infections, postulating that the increase in heel height during surgery may concomitantly increase soft tissue tension substantially enough to disrupt proper blood supply to the surgical site during healing. These findings lend tremendous support to the idea that blood perfusion in soft tissue plays a significant role in predicting wound healing complications. However, to our knowledge, the use of angiography to correlate pre and post operative soft tissue perfusion patterns with post operative complication in patients undergoing ORIF of fractured calcanei has never been investigated.

Indocyanine green (ICG) angiography has been utilized in a myriad of other fields of medicine to evaluate perfusion in different tissues. It has been used in cardiac surgery to asses bypass patency, in microsurgery to assist in free tissue transfers, and in plastic surgery to assess areas of future necrosis during mastectomy operations. Recently, ICG angiography has been used in general surgery to detect ischemic tissues and aid surgeons in determining the appropriate extent of debridement necessary prior to wound closure in laparotomy procedures. Though its utility in other disciplines of medicine are currently being further developed and understood, the implications of ICG angiography in orthopaedic surgery have gone unrecognized. We postulate that soft-tissue perfusion patterns elucidated by ICG angiography in the heels of patients that have incurred calcaneal fractures may be predictive of wound healing complications that develop after surgery. This information could allow surgeons to greatly reduce the complication rate of open reduction procedures on calcaneus fractures by early utilization of appropriate, patient specific prophylactic measures, and could provide an additional contraindication to this operation for patients whom otherwise were not aware they are at an elevated risk.