Prognostic model predicts chances of failure after two-stage revision for PJI

Issue: October 2013

PHILADELPHIA — In their creation of a prognostic classification system for surgical treatment of periprosthetic joint infection in the hip, researchers found smoking, elevated body mass indices and culture negative infections were among the risk factors for failure of two-stage revision procedures.

Perspective from Wael K. Barsoum, MD; and Leonard T. Buller, BA

“[Prognostic classification] allows for better patient counseling moving forward and also allows you to concentrate some of these reversible factors that influence the outcome and perhaps correct them prior to subjecting the patient to surgical intervention for periprosthetic joint infection,” Javad Parvizi, MD, FRCS, of Rothman Institute in Philadelphia, said during his presentation at the Musculoskeletal Infection Society Meeting.

Two-stage revisions

Parvizi and colleagues retrospectively reviewed 181 patients who underwent two-stage revision for periprosthetic joint infection (PJI) and had a minimum 3.4 years follow-up. Of these, 71 patients required reoperation for PJI. The researchers defined a successful operation as one that eradicated infection, healed wounds without recurrences, required no additional surgical intervention and did not result in PJI-related death, according to Parvizi. They defined treatment failure as reoperation for infection.

Javad Parvizi

A univariate analysis identified no significant differences for failure according to patient age, body mass index (BMI) or Charlson Comorbidity Index scores. However, further analysis revealed elevated BMI, smoking, anemia, connective tissue disease or previous gram negative, polymicrobial or Methicillin-resistant Staphylococcus aureus infections were risk factors for failure. After nomogram analysis, the researchers calculated a low risk for failure category (17.8% chance of failure) that was two points or less, a medium risk category (35.8% chance of failure) with a score between three and five points and a high risk category (58.3% chance of failure) with a score between six and eight points.

“Smoking acts on the immune system and can lead to wound healing problems,” Parvizi, who is an Orthopedics Today Editorial Board member, said. “Patients who have wound healing problems have increased risk of failure due to poor soft tissue coverage.”

Limitations

The study was limited by its retrospective nature, and the researchers plan to study patients prospectively to validate their scores.

“This is the first study we are aware of that has looked at the prognostic factors that influence the outcome of exchange arthroplasty,” Parvizi said. “We are aware of some of the limitations including the fact this was retrospective. Hence, we are about to launch a prospective study to validate these scores in the future.” –by Renee Blisard Buddle

Reference:

Parvizi J. Surgical treatment of periprosthetic joint infection: Prognostic classification. Presented at: Musculoskeletal Infection Society Annual Meeting; Aug. 2-3, 2013; Philadelphia.

For more information:

Javad Parvizi, MD, FRCS, can be reached at Rothman Institute, 925 Chestnut St., Philadelphia, PA 19107; email: parvj@aol.com.
Disclosure: Parvizi receives grants and research support from Zimmer, Smith & Nephew, Contatech, TissueGene, Ceramtec, Emovi, Cadence, Medtronic and Pfizer, and owns stock in SmarTech.

Perspective

Wael K. Barsoum, MD; and Leonard T. Buller, BA

Commendable as one of the largest cohorts of hip perprosthetic joint infections (PJIs) treated with two-stage revision, the authors identified both patient and pathogen factors associated with treatment failure, which they defined as any reoperation for infection. The authors’ findings reaffirm a previous understanding of the importance optimizing comorbid conditions can have on the outcome of PJI treatment. Specifically, their study found elevated body mass index, smoking status, anemia and connective tissue disease to be associated with treatment failure, which is similar to the findings published by Sabry and colleagues, Cierny and colleagues, and Peersman and colleagues. Surgeons should seek to optimize these reversible variables prior to two-stage revision, and studies should be conducted to determine whether correction prior to definitive infection treatment improves outcomes.

Another interesting finding from the study by Parvizi and colleagues is that the overall infection-free survival rate was about 60% (110 cases out of 181 patients). This success rate is similar to that published by Sabry and colleagues, but lower than those previously published by Bejon and colleagues (83%), and Goldman and colleagues (77%). The difference in infection-free survival rates may be attributable to an overall sicker patient population or to an increase in antibiotic resistance. Regardless, with two-stage revision considered the gold standard for PJI treatment, this finding is alarming and justifies the need for additional investigation into strategies to increase infection eradication rates.

No study is without limitations, and this study’s retrospective nature and inclusion of patients from a single tertiary care medical center limits its generalizability. Ideally, collaboration between investigators at various institutions could generate a more heterogeneous pool of data capable of providing a more generalizable tool for use by the orthopedic community. There is no doubt a patient-specific approach to complex medical issues is superior to a one-size-fits-all remedy, and this study brings us closer to that goal. We applaud Dr. Parvizi and his colleagues for contributing valuable insight into the various factors associated with infection eradication using the two-stage revision procedure for PJIs and look forward to additional discoveries by their group.

References:

Bejon P. J Antimicrob Chemother. 2010;doi: 10.1093/jac/dkp469.
Cierny G 3rd. Clin Orthop Relat Res. 2002.
Goldman R. Clin Orthop Relat Res. 1996.
Peersman G. Clin Orthop Relat Res. 2001.
Sabry F. J Arthroplasty. 2013;doi:10.1016/j.arth.2013.04.016.

Wael K. Barsoum, MD; and Leonard T. Buller, BA

Department of Orthopaedic Surgery

The Cleveland Clinic

Cleveland

Disclosures: Barsoum receives royalties from Stryker Orthopaedics, Zimmer, Exactech and Shukla Medical; is a speaker for Stryker Orthopaedics; is a board member of KEF Healthcare; is a paid consultant for Stryker Orthopaedics; owns stock in OtisMed Corporation, Custom Orthopaedic Solutions and iVHR; and receives research support from Stryker Orthopaedics, Zimmer, CoolSystems, Orthovita, DJO, Active Implants, The Medicines Company and the State of Ohio. Buller has no relevant financial disclosures.