From OT Europe

Factors in the risk of revision for PJI after hip and knee replacement: Evidence from England and Wales

EFORT

Prosthetic joint infection is a rare, but devastating complication that affects about 1% to 4% of the patients who receive a primary hip or knee replacement. Treating prosthetic joint infection is expensive and regimes are protracted. The infection and the treatment have profoundly negative effects on patients and their families.

As hip and knee replacements have become more common, there has been a nearly threefold increase in the number of revision operations for infection between 2005 and 2013 in England and Wales. More than 1,000 revision procedures are now performed annually for prosthetic joint infection (PJI) of the hip and similar numbers for PJI of the knee that are captured by the National Joint Registry for England, Wales, Northern Ireland and the Isle of Man (NJR). The risk of developing infection after any form of arthroplasty is influenced by both modifiable and non-modifiable patient, surgical and health care system factors.

Using data from the NJR and linkage to the Hospital Episodes Statistics database in England, researchers from the Musculoskeletal Research Unit at the University of Bristol identified 623,253 primary hip and 679,010 primary knee replacements performed in England and Wales and 2,705 hip and 3,659 knee procedures subsequently revised for an indication of PJI between 2003 and 2014.

Risk factors

Their analyses confirmed an increased risk of revision for PJI in patients with a higher BMI, diabetes or chronic pulmonary disease, which is a surrogate marker for smoking status. They also found younger patients, men and those with liver disease were at increased risk of PJI revision. Hip replacements performed via a posterior surgical approach and performed for a hip fracture were at higher risk of revision for PJI. For knee replacements, the risk of revision varied according to the type of procedure, implant fixation and constraint/bearing, with more extensive and complex procedures associated with an increased risk. Interestingly, the experience of the surgeon and the size of the orthopaedic center had no or only small effects on risk of revision for infection.

Uniquely, this research identified that these important factors have a different effect according to the postoperative time period considered. Liver diseases or inflammatory arthropathy specifically increased the risk of long-term revision for PJI. For hip patients, dementia increased early revision for PJI, while the long-term risk of revision was increased for patients with hips in which metal-containing bearings or cement fixation was used, but was reduced for implants containing ceramic bearings. Knee patients receiving patellofemoral, unicondylar or uncemented total knee replacements had a lower risk of long-term revision for PJI.

Advise patients of their risk

Mr. Michael Whitehouse, Reader and Consultant in Trauma and Orthopaedic Surgery in the Musculoskeletal Research Unit of the Bristol Medical School: Translational Health Sciences and EFORT Basic Science Task Force member, said: “The results of this work are very useful to me as a surgeon and to my patients. It gives me the information I need to accurately advise patients about their risk of this devastating complication when undergoing hip or knee replacement. The study also enables me to plan my surgery to minimize the risk for patients, for example using the posterior approach and ceramic heads in hip replacement. It will also provide information for the development of new patient resources to provide patients with better information to make decisions about their treatment and follow-up.”

Dr. Erik Lenguerrand, co-author of the study, a statistician at the University of Bristol, added: “We have shown that certain types of patients, such as those with liver disease, are at particular risk of long-term infection and they would benefit from extra surveillance and tailored information following their discharge from hospital to reduce this risk.”

The findings are concordant between hip and knee, suggesting they may be generalizable to a wide body of patients undergoing implant surgery of various types.

The research team is now comparing the outcomes of surgical treatment for infection to identify best outcomes for patients using data from the NJR and are conducting a large multinational, randomized, controlled trial to generate the best evidence possible in this area.

This article presents independent research funded by the National Institute for Health Research (NIHR) Programme Grants for Applied Research programme (grant number: RP-PG-1210-12005) and supported by the NIHR Comprehensive Clinical Research Network. This study was supported by the NIHR Biomedical Research Centre at the University Hospitals Bristol NHS Foundation Trust and the University of Bristol. The views expressed in this publication are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health.

Written by Erik Lenguerrand, PhD; and Michael Whitehouse, PhD, FRCS (Tr&Orth) on behalf of Mr. A.D. Beswick; Dr. S.K. Kunutsor; Mr. B. Burston; Mr. P. Foguet; Mr. Martyn L. Porter; and Prof. A.W. Blom

EFORT

Prosthetic joint infection is a rare, but devastating complication that affects about 1% to 4% of the patients who receive a primary hip or knee replacement. Treating prosthetic joint infection is expensive and regimes are protracted. The infection and the treatment have profoundly negative effects on patients and their families.

As hip and knee replacements have become more common, there has been a nearly threefold increase in the number of revision operations for infection between 2005 and 2013 in England and Wales. More than 1,000 revision procedures are now performed annually for prosthetic joint infection (PJI) of the hip and similar numbers for PJI of the knee that are captured by the National Joint Registry for England, Wales, Northern Ireland and the Isle of Man (NJR). The risk of developing infection after any form of arthroplasty is influenced by both modifiable and non-modifiable patient, surgical and health care system factors.

Using data from the NJR and linkage to the Hospital Episodes Statistics database in England, researchers from the Musculoskeletal Research Unit at the University of Bristol identified 623,253 primary hip and 679,010 primary knee replacements performed in England and Wales and 2,705 hip and 3,659 knee procedures subsequently revised for an indication of PJI between 2003 and 2014.

Risk factors

Their analyses confirmed an increased risk of revision for PJI in patients with a higher BMI, diabetes or chronic pulmonary disease, which is a surrogate marker for smoking status. They also found younger patients, men and those with liver disease were at increased risk of PJI revision. Hip replacements performed via a posterior surgical approach and performed for a hip fracture were at higher risk of revision for PJI. For knee replacements, the risk of revision varied according to the type of procedure, implant fixation and constraint/bearing, with more extensive and complex procedures associated with an increased risk. Interestingly, the experience of the surgeon and the size of the orthopaedic center had no or only small effects on risk of revision for infection.

Uniquely, this research identified that these important factors have a different effect according to the postoperative time period considered. Liver diseases or inflammatory arthropathy specifically increased the risk of long-term revision for PJI. For hip patients, dementia increased early revision for PJI, while the long-term risk of revision was increased for patients with hips in which metal-containing bearings or cement fixation was used, but was reduced for implants containing ceramic bearings. Knee patients receiving patellofemoral, unicondylar or uncemented total knee replacements had a lower risk of long-term revision for PJI.

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Advise patients of their risk

Mr. Michael Whitehouse, Reader and Consultant in Trauma and Orthopaedic Surgery in the Musculoskeletal Research Unit of the Bristol Medical School: Translational Health Sciences and EFORT Basic Science Task Force member, said: “The results of this work are very useful to me as a surgeon and to my patients. It gives me the information I need to accurately advise patients about their risk of this devastating complication when undergoing hip or knee replacement. The study also enables me to plan my surgery to minimize the risk for patients, for example using the posterior approach and ceramic heads in hip replacement. It will also provide information for the development of new patient resources to provide patients with better information to make decisions about their treatment and follow-up.”

Dr. Erik Lenguerrand, co-author of the study, a statistician at the University of Bristol, added: “We have shown that certain types of patients, such as those with liver disease, are at particular risk of long-term infection and they would benefit from extra surveillance and tailored information following their discharge from hospital to reduce this risk.”

The findings are concordant between hip and knee, suggesting they may be generalizable to a wide body of patients undergoing implant surgery of various types.

The research team is now comparing the outcomes of surgical treatment for infection to identify best outcomes for patients using data from the NJR and are conducting a large multinational, randomized, controlled trial to generate the best evidence possible in this area.

This article presents independent research funded by the National Institute for Health Research (NIHR) Programme Grants for Applied Research programme (grant number: RP-PG-1210-12005) and supported by the NIHR Comprehensive Clinical Research Network. This study was supported by the NIHR Biomedical Research Centre at the University Hospitals Bristol NHS Foundation Trust and the University of Bristol. The views expressed in this publication are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health.

Written by Erik Lenguerrand, PhD; and Michael Whitehouse, PhD, FRCS (Tr&Orth) on behalf of Mr. A.D. Beswick; Dr. S.K. Kunutsor; Mr. B. Burston; Mr. P. Foguet; Mr. Martyn L. Porter; and Prof. A.W. Blom