Failure of the first step of two-stage revision due to polymicrobial prosthetic joint infection of the hip

Background

The unsuccessful treatment of prosthetic joint infection (PJI) with two-stage revision leads to infection recurrence. The objectives of the study were to assess the clinical and demographic characteristics of patients with polymicrobial PJI, and to evaluate the role of the microbial profile involved in PJI in the risk of infection recurrence after the first step of two-stage revision surgery.

Materials and methods

A retrospective analysis of 189 cases of culture-positive PJI following total hip replacement over a 5-year period was performed. The demographic characteristics of patients, clinical symptoms, microbiology cultures of intraoperative biopsies, laboratory values of C-reactive protein (CRP), white blood cell count and erythrocyte sedimentation rate were analyzed. Patients were divided into two groups—135 with monomicrobial and 54 with polymicrobial infection.

Results

Of all patients, 68.9 % in the monomicrobial and 83.3 % in the polymicrobial group had a body mass index >25 kg/m² (p = 0.05). The median CRP values were 5.7 mg/L (IQR 4.0–10.0 mg/L) in the monomicrobial compared to 8.8 mg/L (IQR 5.0–27 mg/L) in the polymicrobial group (p = 0.01). The percentage of successful outcomes was 27.8 % in patients with microbial associations (p < 0.0001). Gram-negative pathogens caused polymicrobial PJI in 61.5 % of cases with infection recurrence (OR 4.4; 95 % CI 1.18–16.37; p = 0.03).

Conclusions

Overweight and obese patients or those with elevated CRP had a greater risk of polymicrobial PJI. They were predisposed to recurrence of infection after the first step of two-stage revision. An unsuccessful outcome was more likely in cases with polymicrobial infection compared to those with monomicrobial infection. In addition, the presence of multidrug-resistant strains of Gram-negative bacteria substantially increased the risk of PJI treatment being unsuccessful.

Level of evidence

Level III, therapeutic study.

     

Longitudinal Model of Periprosthetic Joint Infection in the Rat

The majority of periprosthetic joint infections occur shortly after primary joint replacement (<3 months) and require the removal of all implant components for the treatment period (~4 months). A clinically relevant animal model of periprosthetic infection should, therefore, establish an infection with implant components in place. Here, we describe a joint replacement model in the rat with ultrahigh molecular weight polyethylene (UHMWPE) and titanium components inoculated at the time of surgery by methicillin-sensitive Staphylococcus aureus (S. aureus), which is one of the main causative microorganisms of periprosthetic joint infections. We monitored the animals for 4 weeks by measuring gait, weight-bearing symmetry, von Frey testing, and micro-CT as our primary endpoint analyses. We also assessed the infection ex vivo using colony counts on the implant surfaces and histology of the surrounding tissues. The results confirmed the presence of a local infection for 4 weeks with osteolysis, loosening of the implants, and clinical infection indicators such as redness, swelling, and increased temperature. The utility of specific gait analysis parameters, especially temporal symmetry, hindlimb duty factor imbalance, and phase dispersion was identified in this model for assessing the longitudinal progression of the infection, and these metrics correlated with weight-bearing asymmetry. We propose to use this model to study the efficacy of using different local delivery regimens of antimicrobials on addressing periprosthetic joint infections. Statement of clinical significance: We have established a preclinical joint surgery model, in which postoperative recovery can be monitored over a multi-week course by assessing gait, weight-bearing, and allodynia. This model can be used to study the efficacy of different combinations of implant materials and medication regimens. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:1101-1112, 2020     

A systematic review of irreversible electroporation in localised prostate cancer treatment

Irreversible electroporation is a treatment option used for focal therapy. In this systematic review, we summarise data on irreversible electroporation outcomes in patients with localised prostate cancer. We performed a literature search in 3 databases and included articles with own data on irreversible electroporation results in patients with localised prostate cancer. Primary outcome was procedure efficacy measured as the absence of cancer in the treatment area on the follow-up biopsy. Secondary outcomes were the absence of prostate cancer recurrence in the treatment area on MRI, out-of-field recurrence, complications and functional outcomes (erectile function and micturition). In-field recurrence rate was 0%–39% and out-field 6.4%–24%. In all studies, PSA level decreased: twice lower than baseline after 4 weeks and by 76% after 2 years. Most of the authors noted sexual and urinary toxicity during the first half year after surgery. However, functional outcomes recovered to baseline after 6 months with mild decrease in sexual function. Complication rates after irreversible electroporation were 0%–1% of Clavien–Dindo III and 5%–20% of Clavien–Dindo I–II. Irreversible electroporation has promise oncological outcomes, rate of post-operative complications and minimal-to-no effects on erectile and urinary function. However, medium and long-term data on cancer-specific and recurrence-free survival are still lacking.     

Predicting Psychosocial Outcomes Using a Brief Measure of Quality of Life in a Sample of People with Spinal Cord Injury

Background:

Spinal cord injury (SCI) significantly impacts an individual’s quality of life (QOL). A brief and subjective measure of QOL is necessary to monitor the progress and outcomes of SCI rehabilitation.

Objective:

To determine whether this measure of QOL was associated with clinically important physical and psychosocial outcomes in a sample of people with SCI, to determine how people with SCI scored on this measure of QOL, and to determine whether people with SCI scored differently than nondisabled individuals on the QOL scale.

Methods:

Participants were 134 people with SCI (65% male; 35% female) and 227 nondisabled people (35% male; 65% female). Participants were assessed on a number of psychosocial and physiological variables at a large urban university and rehabilitation center. Variables examined were QOL, life satisfaction, depression, social interaction, pain, fatigue, and level of functioning.

Results:

Participants with SCI reported more low QOL scores and fewer high QOL scores than the nondisabled group. For participants with SCI, QOL was positively related to life satisfaction and social interaction and negatively related to pain, fatigue, and depression.

Conclusions:

Participants with SCI scored lower on the QOL measure than those without a disability, although the difference was not clinically significant. QOL was unrelated to level of functioning; people may still experience a high QOL despite their physical limitations. Depression and social interaction were significantly related to QOL and should be secondary targets for intervention following SCI rehabilitation.Key words: depression, disability, life satisfaction, pain, quality of life, social interaction, spinal cord injuriesQuality of life (QOL) can be defined as the quality of a person’s overall experiences of living. Individuals differ on what values they place on work, leisure activities, relationships with other people, intimacy with a spouse or partner, or participation in sports. Perhaps no other impairment impacts a person’s QOL as much as a spinal cord injury (SCI).¹ After the medical and functional problems are addressed in rehabilitation, individuals begin to think about how they can regain much of their previous lifestyle and QOL. There are substantial barriers in the physical and social environments that stand in the way of higher QOL, including medical issues; difficulties in constructing a suitable home environment; and challenges in keeping the family together, supporting oneself, and dealing with the subtle and not-so-subtle attitudes of others.² These problems and barriers can result in psychological issues, the most common of which is depression.³ It is not surprising that individuals find it difficult to regain a positive level of QOL after SCI.Considering that there are approximately 270,000 people currently living with SCI in the United States, with 12,000 new cases of SCI each year,⁴ the topic of QOL is important to the persons with SCI, their families, and to the clinicians who treat them. However, there is little agreement on the definition of QOL and therefore on its measurement. Most measures of QOL are either too long for clinicians to use in practice or are not measures of QOL itself, but rather are measures of life satisfaction, health status, or well-being. For example, The World Health Organization’s⁵ QOL measure, WHOQOL-BREF, is primarily a life satisfaction measure, and it takes more than 1 hour to administer. Even the SF-36,⁶ which many people inaccurately accept and use as a measure of QOL, is actually a measure of health status, according to the author.Experts in both QOL and SCI, including Dijkers⁷ and Tate,⁸ have argued that there is a need for a subjective measure of QOL that can be used to monitor a person’s progress of rehabilitation and as a measurable outcome of rehabilitation programs. Clinical practice requires brief measures that are reliable and valid and that can be incorporated into progress notes about the patient. This clinically oriented article addresses the issue of whether a brief measure of QOL can stand up to the rigors of scientific standards while still predicting clinically important outcomes of SCI and whether it is suitable for the practitioner as well as for persons with SCI.This article addresses 3 objectives. The first objective was to determine whether this measure of QOL was associated with clinically important physical and psychosocial outcomes in a sample of people with SCI. The second objective was to determine how people with SCI scored on this measure of QOL. The third objective was to determine whether people with SCI scored differently than nondisabled individuals on a subjective, single-item QOL scale.