- This retrospective study evaluated the outcomes of 290 patients who underwent hip or knee arthroplasty: 58 with a history of injection drug use (IDU) and 232 matched patients who had no history of IDU
- The incidence of periprosthetic joint infection (PJI) was 29.3% in the IDU group and 3.4% in the control group
- 35% of PJI cases in the IDU cohort versus none in the matched cohort occurred more than 24 months after arthroplasty
- 35% of patients in the IDU cohort versus none in the matched cohort required amputation, resection arthroplasty, or arthrodesis
- Prior history of IDU was the risk factor most strongly associated with PJI (OR, 9.6; P<0.001)
The risk of periprosthetic joint infection (PJI) after total joint arthroplasty (TJA) is known to be increased in people who abuse drugs by injection. However, published rates come from small case series and vary widely, from 31% to 87%.
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Massachusetts General Hospital researchers conducted the largest study to date of PJI after TJA in people with a history of injection drug use (IDU), which was further strengthened by using a matched cohort. In The Journal of Arthroplasty, they report IDU was associated with a more than nine-fold increased risk of PJI.
The authors are Hany S. Bedair, MD, chief of the Hip and Knee Replacement Service of the Department of Orthopaedic Surgery, Kyle Alpaugh, MD, and Christopher Melnic, MD, orthopedic surgeons in the Service, and colleagues.
Using a Mass General registry, the team identified 58 adults with a history of subcutaneous, intramuscular, or intravenous drug use; who underwent primary total hip or knee arthroplasty between January 1, 2000 and March 31, 2020; and had at least two years of follow-up. The mean age was 53 (range, 18–75), 62% were male, average body mass index was 32 kg/m2, 67% had hip arthroplasty. The most common indication for arthroplasty was osteoarthritis, 69%.
The patients were matched by age, body mass index, sex, joint and arthroplasty indication with 232 controls who underwent TJA but did not have a history of IDU. The mean length of follow-up was seven years for both cohorts (range for both, 2–20 years).
Incidence of PJI
The PJI rate was 29.3% in the IDU group and 3.4% in the control group. 35% of PJI cases in the IDU group occurred more than 24 months after arthroplasty, suggesting hematogenous dissemination of organisms as opposed to direct inoculation. In the matched cohort, no cases of PJI occurred so late.
Methicillin-resistant Staphylococcus aureus was identified in 18% of patients in the IDU group, fungi in 18%, and Gram-negative organisms in 18%; none of these were found in the matched cohort. 24% of the infections in the IDU cohort were caused by multidrug-resistant organisms, compared with 13% in the matched cohort.
Risk Factors for PJI
Osteoarthritis as the indication for the primary arthroplasty was associated with decreased risk of PJI (OR, 0.3; P=0.028), although this result was potentially biased because the cohorts were matched on the indication.
Factors linked to significantly increased risk of PJI were:
- ASA physical score of 3 (vs. 2)—OR, 4.9 (P=0.023)
- Any history of IDU—OR, 9.6 (P<0.001)
Selected additional outcomes further illustrate the burden of IDU:
- Discharge to home with services—69% of the IDU cohort vs. 90% of the matched cohort
- Discharge to rehabilitation—17% vs. 5%
- Discharge to a skilled nursing facility—12% vs. 1%
- Presentation to ED within 90 days—33% vs. 10%
- Amputation, resection arthroplasty or arthrodesis—35% vs. 0%
The IDU cohort had a significantly lower infection-free joint survival rate (P<0.001) and a significantly lower joint retention rate (P<0.001).
Potential Benefits of Adjunctive Care
In studies of other IDU-associated infections, such as endocarditis, patients demonstrated improved engagement with care if they received addiction medicine consultation, medication-assisted treatment (e.g., methadone or buprenorphine/naloxone), or formal multidisciplinary care from surgeons, infectious disease and addiction medicine specialists, social workers, recovery coaches, and pharmacists.
This patient population is medically and socially vulnerable, and further work is needed to determine whether similar approaches will benefit people with a history of IDU who undergo TJA.
Learn more about the Hip and Knee Replacement Service at Mass General
Learn more about the Adult Reconstructive Surgery Fellowship at Mass General