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Fig. 1 A 64-year-old male patient 4 weeks after a TAR procedure with a major wound that required débridement.
Courtesy of Christopher Gross, MD

AAOS Now

Published 10/1/2016
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Terry Stanton

Study: Longer Surgical Times Linked to Wound Complications in TAR

A study examining surgical and demographic characteristics in patients with and without wound complications after undergoing total ankle replacement (TAR) identified a correlation between surgical time and major wound issues requiring surgical intervention.

Christopher E. Gross, MD, of the Medical University of South Carolina, presented the study at the annual meeting of the American Orthopaedic Foot & Ankle Society (AOFAS) in Toronto. Investigators hypothesized that increased surgical times, along with increased tourniquet time, are controllable intraoperative factors that may negatively correlate with wound healing secondary to prolonged tissue ischemia. Their results demonstrated that patients with major wound issues had a significantly longer mean surgery time and trended toward a longer median tourniquet time, compared to patients without wound complications (control group). The researchers also found that patients without wound complications were more likely to have an etiology of posttraumatic arthritis, whereas those with wound complications were more likely to have osteoarthritis.

The study reviewed a consecutive series of 762 primary TAR procedures performed over 14.5 years. Demographic and patient information was recorded for age, sex, race, American Society of Anesthesiologist (ASA) score, body mass index (BMI), smoking history, previous surgical history, and etiology of arthritis. Surgical information including surgical implant, surgical time, tourniquet time, and intraoperative complications was collected. Only primary arthroplasty procedures were included. Patients whose wound required only local wound care or in-office minor wound débridement were also excluded.

Clinical outcomes, including wound healing and implant failure rates, were recorded. AOFAS hindfoot-ankle score, Short Musculoskeletal Function Assessment (SMFA), Foot and Ankle Disability Index (FADI), and Foot and Ankle Outcome Score (FAOS) were used to evaluate preoperative and final postoperative function. Baseline demographics, surgical characteristics, and failure rates for the two patient groups were compared.

Of the patients in the study, 26 underwent a total of 49 surgical procedures (3.4 percent of all procedures) to treat wound healing complications (Fig. 1). Of these, 18 patients had flaps and 14 had split-thickness skin grafts; the median time to surgically treat the wound was 1.9 months after the index TAR procedure. Median follow-up was 13.2 months after TAR and 12.7 months after the final wound procedure. Of the patients with wound complications, a deep space infection developed in 8 patients (30.8 percent), requiring a total of 14 incision and drainage procedures with 5 polyethylene exchanges. Two patients eventually underwent below-knee amputation, and two patients required a two-stage revision for infection.

Surgical time was defined as the point from incision to when the cast was placed. Tourniquet time was defined as the time the thigh tourniquet was consecutively inflated. Prior to closure, the surgical site was copiously irrigated with a dilute antibiotic solution. The surgical site was also closed in layers, including the deep ankle capsule, the tibialis anterior or extensor hallucis longus tendon sheath, the subcutaneous tissue layer, and the skin, with 4-0 nylon vertical mattress sutures. 

After surgery, patients were placed into non–weight-bearing short leg casts. Two weeks postoperatively, the cast was removed and the wound inspected. If the wound skin edges were clean, dry, and intact, the sutures were removed and the patient was allowed to bear weight as tolerated in a CAM walker boot. If the skin edges were macerated or evidence of drainage, erythema, or other signs of delayed healing was found, the sutures were left in place and the ankle was recast for an additional 7 days. If the surgical site continued to be concerning (ie, ongoing drainage, erythema, or dehiscence), the patient was sent for an immediate evaluation by plastic surgery staff. 

Longer times = more complications
The mean surgery time was significantly longer in patients with major wound issues, compared to patients without wound complications (214.8 minutes versus 189.3 minutes; P = 0.041). Patients with major wound issues also had a longer median tourniquet time (151 minutes versus 141 minutes; P = 0.060). The control group had a higher incidence of preoperative posttraumatic etiology for ankle arthritis than the wound group (70.4 percent versus 42.9 percent), and the wound group had a higher rate of osteoarthritis (42.9 percent versus 13.7 percent; P = 0.006).

Preoperatively, patients with major wound complications had significantly lower AOFAS hindfoot (32.3 versus 40.7; P = 0.018) and FADI scores (0.46 versus 0.55; P = 0.014), whereas the preoperative FAOS, Short Form-36 (SF-36), SMFA, and visual analog scale (VAS) scores were similar. Postoperatively, patients with wound complications had worse FAOS pain subset scores compared to the control group (68.3 versus 81.6; P = 0.044), as well as worse SMFA function scores (67.0 versus 57.8; P = 0.047).

The mean age and percentage of males were similar in patients with and without wound complications. Patients without wound complications trended toward having a larger mean BMI (P = 0.056). Both groups had similar preoperative health comorbidities, including diabetes, coronary artery disease, hypertension, smoking history, and ASA score. No implant type had a significantly higher rate of operative wound complications (P = 0.361). 

Regarding the trending association seen between tourniquet time and wound complications, the authors commented that although tourniquet time has not been implicated in serious foot and ankle wound complications to date, "it is feasible that local tissue ischemia in an already tenuous soft-tissue envelope can adversely affect the healing of an ankle arthrotomy," and "a reperfusion injury may occur in the local soft tissues." Furthermore, they observed, increased surgical time and the use of retractors may stifle local blood flow and delay healing. In view of these issues, they wrote, "we advocate limiting tourniquet time."

On the finding that the patients with wound complications had a significantly greater preoperative diagnosis of osteoarthritis than the control group, Dr. Gross noted that posttraumatic patients might be expected to have a soft-tissue envelope that is scarred and unpliable, which could lead to more wound complications. "Perhaps patients with osteoarthritis had a higher rate of ankle corticosteroid injections prior to surgery, which could potentially lead to wound complication or deep infection," the authors wrote.

Limitations of the study include being a retrospective review of a nonrandomized patient population; thus selection bias may have been a factor. Also, the authors note, the database did not record who had minor wound complications that were treated with in-office care. "These wounds may have led to deeper wounds and larger soft-tissue defects if the natural history played out," the authors state. "Therefore, we could be missing a different subset of patients who could have been analyzed."

Dr. Gross told AAOS Now that he and his colleagues, having had experience with patients requiring flaps after TAR surgery, undertook this study to assess the surgical time, demographics, and other factors affecting patients with wound complications "to see if there were any factors that surgeons could control in order to reduce serious wound complications." He said he was not surprised to see that increased surgical times were associated with increased wound complication rates, but the finding that a higher BMI was almost significant in protecting the wound from a complication was "a little unexpected."

In addition to the recommendation to limit tourniquet time, Dr. Gross said, the data indicate that "we should be mindful of doing several procedures at the same time as performing a total ankle and thought should be given to staging the TAR if multiple pathologies are to be addressed at the time of surgery, so as to limit surgical time. For instance, if we are reconstructing a cavovarus or pes planus foot, perhaps we should stage these procedures."

Although the study did not detect a statistically significant correlation between smoking and wound complications, Dr. Gross said his clinic does follow a protocol for patients who smoke. "We advise them not to smoke for 1 month prior to and 3 months after this procedure," he said. "Personally, I wait for a negative nicotine test before I will perform a serious elective procedure on someone."

In future research, Dr. Gross said he would like to see "what are the surgical characteristics of people with minor wound problems—erythema, wound dehiscence, need for oral antibiotics after surgery—and compare that to the patient population with total ankles without wound complications."

Dr. Gross's coauthors are Kamran Hamid, MD; Cynthia L. Green, PhD; Samuel B. Adams, MD; Mark E. Easley, MD; James K. DeOrio, MD; and James A. Nunley II, MD.

The authors' disclosure information can be accessed at www.aaos.org/disclosure

Terry Stanton is the senior science writer for AAOS Now. He can be reached at tstanton@aaos.org

Bottom Line

  • Longer surgical times for TAR procedures were associated with a higher rate of wound complications, and longer tourniquet times showed a trending association with more complications.
  • Factors such as age and diabetes were not significantly associated with major wound complications, but diabetes was associated with minor wound problems and patients without wound complications trended toward a greater BMI.
  • Patients with surgical wound complications had a greater incidence of a preoperative etiology of osteoarthritis versus a greater prevalence of posttraumatic arthritis in the control group.
  • The results indicate that surgeons should be mindful of tourniquet time and should consider staging surgery for multiple procedures.