Early Mechanical Failure Increases Risk of Infection

Patients who must return to the operating room for mechanical failure after total hip arthroplasty (THA), especially in the first two weeks after surgery, are at higher risk to develop an infection or wound complication requiring a subsequent operation, according to the authors of Paper 026.

Their retrospective study of 16,203 patients from a single institution who underwent primary THA from 2010 to 2016 found that patients who underwent surgery for mechanical failure within 14 days after the initial THA had the highest rate of subsequent infection and wound complications, nearly five times higher than that of patients who had revision surgery 90 days or more after primary THA.


“Infection and wound complications following THA occur more frequently in a previously operated joint, most likely due to the vulnerability of surrounding soft tissues,” noted the authors. “Unfortunately, unavoidable mechanical complications, such as periprosthetic fracture, instability, hardware failure, or subsidence may sometimes require an early return to the operating room at a time in which patients are at the highest risk for subsequent complications.”

Their study had the following goals:

  • to determine whether patients requiring an early return to the operating room for a mechanical complication during the acute recovery phase after primary THA are at an increased risk for infection and wound complications compared to patients requiring a similar reoperation after an initial period of convalescence
  • to identify both the time interval during which the risk for infection and wound complications is greatest and after which the risk hits a plateau

A retrospective analysis

The study included all patients who required reoperation for an aseptic mechanical etiology (periprosthetic fracture, instability, hardware failure, loosening, subsidence, or polyethylene wear) within two years postoperatively and who did not require an earlier reoperation for an alternative etiology. THA patients who did not require reoperation, revision, or conversion THA, those who underwent THA for an acute fracture, and those who required a return to the operating room for a nonmechanical etiology prior to mechanical failure (infection, wound complications, corrosion, metallosis, patellar clunk, and vascular or nerve exploration) were excluded.

Out of 16,203 patients, 187 patients met the study inclusion criteria. Researchers collected demographic and surgical variables on all patients, including age, gender, year of index surgery, and revision arthroplasty or open reduction and internal fixation (ORIF) (arthrotomy/no arthrotomy). The primary outcome was reoperations for infection or wound complications, including hematoma or dehiscence, within the 90-day period after reoperation. Study group patients were an average of 69 years old, predominantly female, and underwent revision surgery an average of 162 days after their primary THA. Of the 187 patients, 37 underwent either an ORIF or an ORIF and a revision.

For the study, statistical significance was set at P < 0.05. Chi square tests and Fischer’s exact tests were used to analyze results.

Interpreting the data

Thirty-four patients underwent mechanical reoperation within 14 days after the initial THA. The rate of subsequent infection and wound complications in this group was 11.8 percent. The 60 patients who underwent mechanical operation less than 30 days after the initial THA had a slightly lower rate of subsequent infection and wound complications (8.3 percent). The 102 patients who underwent revision THA within 90 days after the initial surgery had a cumulative rate of subsequent infection and wound complications of 7.8 percent.

Researchers found that the longer the period between initial and revision THA, the lower the rate of infection and wound complications. After 90 days (Fig. 1), the rates of infection and wound complications dropped significantly (to 2.35 percent for revision surgery more than 90 days after primary THA, and to 1.5 percent for revision surgery a year or more after the initial surgery).

“The cumulative rate of infection among all 187 patients included in the study within the two-year cutoff period of time difference between primary and revision THA was 5.3 percent,” the authors wrote. “The cumulative rate of periprosthetic joint infections in all patient participants was 2.14 percent.” Surgical site infections and wound complications each had a rate of 1.60 percent.

“Wound complications and deep infections are more likely to occur after mechanical revisions following THA, as the body is in a more vulnerable state and there is poorer soft tissue healing,” they noted. “The highest rate of infection and wound complications occurred in the first two weeks after the index procedure, with decreasing rates of infection and wound complications as the time between the initial surgery and revision surgery increased.”


The authors identified the following limitations to the study:

  • small sample size of patients undergoing reoperation for mechanical failure, thus preventing further extrapolation to a larger population
  • use of an arbitrary cutoff of less than or greater than 90 days (future studies may be able to stratify risk over smaller time intervals)
  • failure to account for other comorbidities—such as smoking status, body mass index, hypertension, prolonged operative time, hemodynamic and electrolyte issues—that may influence patient outcomes

Nonetheless, they advised taking proper precautions to aggressively prevent the development of infection after primary THA. “Patients with early mechanical complications after primary THA should be warned of the increased likelihood of complications after surgery even up to 180 days after the initial surgery,” they suggested. “In cases of mechanical failure after hip replacement, it may be prudent to delay surgical intervention if possible to allow the tissues time to heal and be less vulnerable to possible complications.”

The authors of Paper 026, “Early Reoperation for Mechanical Complications After Primary TJA Predisposes to Infection and Wound Complications,” are Andrew Fleischman, MD; Jordan Wohl, BS; Tristan Fried, BS; Antonia F. Chen, MD, MBA; and Richard H. Rothman, MD, PhD. Their presentation is scheduled for today at 8 a.m.


Fig. 1 Cumulative rate of reoperation for wound complication or infection versus days from primary THA to mechanical reoperation for less than 90 days and greater than 90 days.

Courtesy of Andrew Fleischman, MD; Jordan Wohl, BS; Tristan Fried, BS; Antonia F. Chen, MD, MBA; and Richard H. Rothman, MD, PhD.