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Infection After Unicompartmental Knee Arthroplasty

A High Risk of Subsequent Complications

Hernandez, Nicholas M. MD; Petis, Stephen M. MD; Hanssen, Arlen D. MD; Sierra, Rafael J. MD; Abdel, Matthew P. MD; Pagnano, Mark W. MD

Clinical Orthopaedics and Related Research®: January 2019 - Volume 477 - Issue 1 - p 70–77
doi: 10.1097/CORR.0000000000000372

Background Unicompartmental knee arthroplasty restores function and improves pain in appropriately selected patients. Scant evidence exists regarding the treatment of periprosthetic joint infection (PJI) after unicompartmental knee arthroplasty (UKA).

Questions/purposes (1) What was the overall survivorship free from reinfection? (2) What is the survivorship free of all-cause revision? (3) What are the Knee Society scores (KSS) and complications after surgical treatment of UKA PJI?

Methods This retrospective study with data drawn from a longitudinally maintained institutional registry identified 15 UKA PJIs between 1992 and 2014. The median age at PJI diagnosis was 58 years (range, 41-82 years), nine of 15 were men, and the median body mass index was 29 kg/m2 (range, 23-36 kg/m2). Ten patients (10 of 15) satisfied major Musculoskeletal Infection Society diagnostic criteria. There were five patients (five of 15) with early postoperative infections, five (five of 15) with acute hematogenous infections, and five (five of 15) with chronic PJIs. Two-stage exchange was performed in four patients with PJIs (four of 15), and débridement, antibiotics, and implant retention (DAIR) was performed in 11 patients (11 of 15) with PJIs. We performed Kaplan-Meier survivorship analysis for reinfection and revision procedures. Thirteen patients had a minimum of 2 years’ followup and were included in the clinical analysis. Median followup was 4 years (range, 2-6 years). We calculated KSS.

Results Infection-free survivorship was 71% at 5 years (95% confidence interval [CI], 46%–96%). Treatment success was higher for patients undergoing two-stage exchange (100% at 5 years; 95% CI, 100%–100%) versus DAIR (61% at 5 years; 95% CI, 31%–92%). Four of 11 patients undergoing DAIR had developed a reinfection at final followup. Survivorship free of any revision was 49% at 5 years (95% CI, 19%–79%). One patient from the two-stage exchange cohort underwent femoral component revision for aseptic loosening 5 years after PJI treatment, and two patients from the DAIR group were converted to TKA for disease progression at a mean of 4 years. In patients with a minimum of 2 years’ followup, median KSS improved from 73 (range, 50-93) before index UKA to 94 (range, 55-100; p = 0.016).

Conclusions Treatment of UKA PJI with DAIR was associated with a lower infection-free survivorship at 5 years compared with two-stage exchange with conversion to TKA. Among those patients who were infection-free, a number needed reoperations for disease progression (in the DAIR group) or component loosening (in both groups). UKA PJI results in substantial morbidity, and patients with these infections should be followed closely for aseptic causes of failure in addition to infection recurrence.

Level of Evidence Level IV, therapeutic study.

Nicholas J. Hernandez MD, Stephen M. Petis MD, Arlen D. Hanssen MD, Rafael J. Sierra MD, Matthew P. Abdel MD, Mark W. Pagnano MD, Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA

M. W. Pagnano, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA, email:

One of the authors (MWP) received personal fees from DePuy Synthes (Warsaw, IN, USA) outside the submitted work. One of the authors (RJS) received a grant and personal fees from Zimmer Biomet (Warsaw, IN, USA) outside the submitted work. One of the authors (MPA) received personal fees from Stryker Orthopaedics (Kalamazoo, MI, USA) outside the submitted work.

All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research® editors and board members are on file with the publication and can be viewed on request.

Clinical Orthopaedics and Related Research® neither advocates nor endorses the use of any treatment, drug, or device. Readers are encouraged to always seek additional information, including FDA approval status, of any drug or device before clinical use.

Each author certifies that his institution approved the human protocol for this investigation and that all investigations were conducted in conformity with ethical principles of research.

Received January 08, 2018

Received in revised form April 18, 2018

Accepted May 21, 2018

© 2019 Lippincott Williams & Wilkins LWW
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