[Multicentre study of infection incidence in knee prosthesis]

Methods of alignment in total knee arthroplasty, systematic review

Introduction

Although total knee arthroplasty (TKA) is a very frequent surgery, one in five patients is not completely satisfied. Mechanical alignment (MA) is the most popular technique for implanting TKA. However, to improve clinical outcomes, new techniques that aim to rebuild the native alignment of the knee have been developed.

Objective

The aim of this study is to perform a systematic review of the available clinical trials and observational studies comparing clinical and radiological outcomes of different methods of alignment (kinematic, anatomic, functional) to MA.

Methods

A systematic review is performed comparing results of patient reported outcome measures (PROMs) questionnaires (WOMAC, OKS, KSS, KOOS, FJS), radiological angles (HKA, mLDFA, MPTA, JLOA, femoral rotation and tibial slope) and range of motion (ROM).

Results

Kinematic and functional alignment show a slight tendency to obtain better PROMs compared to mechanical alignment. Complication rates were not significantly different between groups. Nevertheless, these results are not consistent in every study. Anatomic alignment showed no significant differences compared to mechanical alignment.

Conclusion

Kinematic alignment is an equal or slightly better alternative than mechanical alignment for patients included in this study. However, the difference between methods does not seem to be enough to explain the high percentage of dissatisfied patients. Studies implementing lax inclusion and exclusion criteria would be needed to resemble conditions of patients assisted in daily surgical practice. It would be interesting to study patient's knee phenotypes, to notice if any method of alignment is significantly better for any constitutional deviation.

Risk factors for periprosthetic joint infection after total knee arthroplasty

INTRODUCTION

Periprosthetic joint infection (PJI) is the most serious and feared complication in total knee arthroplasty (TKA) and can have catastrophic consequences. The number of total knee arthroplasties is increasing, so infections could also be greater in the future. The aim of this study is to identify the most relevant risk factors associated with infection after a total knee arthroplasty.

METHODS

This is a case-control study of patients who underwent total knee arthroplasty at the University Hospital of Salamanca. We included 66 TKA PJI patients and 66 control TKA patients. Demographic and clinical variables were collected. A descriptive and inferential analysis was performed by logistic regression and attributable risk fraction assessed.

RESULTS

Prolonged operative time (> 90') and tourniquet time (> 60') were the most relevant risk factors described (OR 40.77, AFE 0.97, p > 0.001 and OR 37.14, AFE 0.97, p < 0.001, respectively). The use of non-antibiotic-laded cement (OR 3.62), obesity (BMI > 30, OR 8.86), diabetes (OR 2.33), high ASA grade (III-IV, OR 15.30), and blood transfusion requirement (OR 4.60) were also statistically significant risk factors for TKA PJI.

CONCLUSIONS

Our study provides evidence concerning that operative time, tourniquet time, cement type, diabetes, obesity, ASA grade, and blood transfusion requirement as independently associated risk factors for TKA PJI. Modifiable risk factors were specifically relevant, so we should be able to reduce the infection rate.

Three dimensional gait analysis in patients with symptomatic component mal-rotation after total knee arthroplasty

PURPOSE

Purpose of the present cohort study was the determination of lower body function and rotation in patients with symptomatic component mal-rotation after total knee arthroplasty using instrumented 3D gait analysis.

METHODS

A consecutive series of 12 patients (61.3 years ± 11.4 years) were included suffering under remaining pain or limited range of motion at least six months after total knee arthroplasty. A CT-scan according to the protocol of Berger et al. and instrumented 3D gait analysis were carried out including clinical examination, videotaping, and kinematic analysis using a Plug-in Gait model. Outcome variables were temporospatial parameters as well as kinematics in sagittal and transversal plane. Data for reference group were collected retrospectively and matched by age and gender.

RESULTS

Temporospatial parameters of the study group showed decreased velocity, cadence, and step length as well as increased step time. Single limb support was reduced for the affected limb. In sagittal plane, maximum knee flexion during swing phase was reduced for the replaced knee joint. In transverse plane, there was hardly any difference between affected and non-affected limb. Compared to the reference group, both limbs show significant increased internal ankle rotation and external hip rotation. There were significant strong linear correlations between ankle rotation and hip rotation as well as ankle rotation and radiological tibial mal-rotation.

CONCLUSIONS

Patients with symptomatic component mal-rotation after total knee arthroplasty showed typically functional deficits. The affected and non-affected limb showed significant increased internal ankle rotation and external hip rotation, while only the affected, replaced knee showed reduced internal knee rotation. Identification of rotational abnormalities of hip and ankle joints seems to be mandatory in TKA to identify the patient group with external hip rotation, internal ankle rotation, and an elevated risk for symptomatic rotational TKA component mal-alignment.

Economical analysis on prophylaxis, diagnosis, and treatment of periprosthetic infections

The economic burden of periprosthetic infections is enormous, but the number of economic studies dealing with this issue is very scarce. This review tries to know the economic literature existing, assess the value of current data, and recognize the less costly and more effective procedures for prevention, diagnosis and treatment of periprosthetic infections. Forty five studies meeting the inclusion criteria and adhering to the quality criteria used were carefully analyzed to extract the economic data of relevance in evaluating the magnitude of problem and the more cost-effective solutions. However, because the heterogeneity and the low-quality of most of these studies meta-analytical technique has not been possible. Instead, the studies have been reviewed descriptively. Optimizing the antibiotic use in the prevention and treatment of periprosthetic infection, combined with systemic and behavioral changes in the operating room; detecting and treating the high-risk groups; a quick, simple, reliable, safe, and cost-effective diagnosis, and the rationale management of the instituted infection, specifically using the different procedures according to each particular case, could allow to improve outcomes and produce the highest quality of life for patients and the lowest economic impact. Nevertheless, the cost effectiveness of different interventions to prevent and to treat the periprosthetic infection remains unclear.