About 10% of surgical revision procedures for infected hip prostheses become reinfected within 2 years. Pooled estimates of reinfection outcomes with wide confidence intervals do not suggest that outcomes are worse after one-stage compared with two-stage revision.
Evidence on the relative effectiveness of one- and two-stage revisions in preventing reinfection of hip prostheses is largely based on interpretation of longitudinal studies. Reviews of longitudinal studies and particularly case series are limited by the possibility of publication bias and other sources of bias. We used systematic review methods to identify studies that described outcomes specifically after one- or two-stage revisions in consecutive and generally unselected patients.
Despite our aim to include only studies of unselected patients undergoing surgical revision, we recognise an earlier phase of selection related to management without further replacement. Different protocols, eligibility criteria and use of treatments with prosthesis retention may affect the representativeness of the study populations we included and may explain the high degree of statistical heterogeneity we observed. As is true of a review of treatment of infected knee prostheses by Jämsen and colleagues, however, we believe that it is important to attempt to include "only papers reporting a pure series of either one-stage or two-stage revision" [43
] (p. 72). This is supported by the somewhat different reinfection rates we observed when we included studies that included patients selected for a particular revision method on the basis of infection severity and other aspects of patient health.
In this overview of studies in unselected patients, we specified prevention of reinfection as the key aim of revision surgery. In discussions with our advisory group of patients with joint replacement, patients recognised that clearance of infection is of paramount importance. Achievement of a functional, painless hip is the aim of any revision hip replacement [44
], however, and the importance of patient-reported outcomes in assessing joint replacement outcome is widely recognised [45
]. In their review, Wolf and colleagues explored patient preferences for one- or two-stage revision in a Markov simulation model [18
]. In addition to outcomes reported in longitudinal studies, they used data collected from nonorthopaedic outpatients on trade-offs between impaired health versus full health with shortened life, as well as time with constant severe pain. They concluded that, compared to a two-stage procedure, one-stage revision was associated with greater benefit in terms of quality-adjusted life years.
One- and two-stage methods are perceived to have specific advantages and disadvantages. With a one-stage approach and a single major surgery, recovery is quicker. The advantages of two-stage treatment relate to the opportunity to apply an enhanced antimicrobial strategy between excision and reimplantation surgeries. The results of bacteriological samples obtained at surgery can be used to guide antibiotic treatment, and the period between stages is an opportunity for insertion of antibiotic-impregnated cement beads into the joint space. In two-stage revisions, however, patients experience considerable restriction of movement during the period between implant removal and replacement [4
]. Two-stage revision is often considered essential for more virulent infections. Nevertheless, Leung and colleagues reported a reinfection rate of 21% after two-stage revision in patients with resistant infections [46
To reduce long-term problems resulting from an extended period without an implant, an antibiotic-impregnated cement "spacer" may be used to maintain some function and a correct leg length and to reduce long-term problems associated with disuse. Although spacers improve patient mobility, complications can arise. For example, in 88 spacer implantations performed by Jung and colleagues, there were 15 spacer dislocations (17%), 9 spacer fractures (10%) and an overall complication rate of 58.5% [47
The economic implications of uncomplicated one- and two-stage revision differ considerably. Although a one-stage procedure may require a prolonged hospital stay to facilitate intravenous antibiotic therapy, the main determinant of cost is the requirement for additional surgery in a two-stage revision. In the United Kingdom, the cost to the NHS of each complicated hip procedure is over £8,000 [48
]. Klouche and colleagues estimated that the cost of managing a patient with an infected hip prosthesis is 3.6 times greater than that of a primary total hip replacement and that two-stage revisions cost 1.7 times more than one-stage revisions [14
Forty-three years of data collection do not conclusively support a specific treatment for prosthetic hip infection. The thoroughness of data collected over extended periods suggests the possibility of individual patient data synthesis with time-to-event analyses [49
]. We concur with Matthews and colleagues, however, that large, multicentre, randomised trials are needed to establish optimum management strategies [4
], and this is particularly apparent regarding surgical options. It could be argued that appropriate randomised trials are not feasible because of the limited opportunities of an individual surgeon to gain experience in using a particular technique. However, the surgical techniques familiar to surgeons operating with the more widely used two-stage strategy and with aseptic revision (a single-stage revision) include most of the skills required.
The acceptability to patients of methods and their evaluation is of overriding importance. It is notable that only two studies collected data regarding patient-centred outcomes. If reinfection rates are similar between methods, the possibility of a single major surgery, reduced overall hospitalisation and avoidance of a prolonged period without a permanent implant would make a one-stage procedure preferable. Conversely, it could be argued that the long-term, targeted antibiotic regimen associated with contemporary two-stage treatment should not be withheld.
Prosthetic hip infection is sufficiently rare to make a single, definitive randomised trial unlikely. Conducting multiple smaller trials in which patients' experiences and patient-reported outcomes are recorded, together with a systematic overview of infection outcome, may be a more valid approach, and this would also allow exploration of methodological variability and other sources of heterogeneity [50
]. Research into the patient experience of prosthetic hip infection and its treatment is urgently required. This will help in the development of studies that identify the best method for treatment of prosthetic joint infection.