Background:Dislocation following total knee arthroplasty (TKA) is the worst form of instability. The incidence is from 0.15 to 0.5%. We report six cases of TKA dislocation and analyze the patterns of dislocation and the factors related to each of them.Materials and Methods:Six patients with dislocation of knee following TKA are reported. The causes for the dislocations were an imbalance of the flexion gap (n=4), an inadequate selection of implants (n=1), malrotation of components (n=1) leading to incompetence of the extensor mechanism, or rupture of the medial collateral ligament (MCC). The patients presented complained of pain, giving way episodes, joint effusion and difficulty in climbing stairs. Five patients suffered posterior dislocation while one anterior dislocation. An urgent closed reduction of dislocation was performed under general anaesthesia in all patients. All patients were operated for residual instability by revision arthroplasty after a period of conservative treatment.Results:One patient had deep infection and knee was arthrodesed. Two patients have a minimal residual lag for active extension, including a patient with a previous patellectomy. Result was considered excellent or good in four cases and fair in one, without residual instability. Five out of six patients in our series had a cruciate retaining (CR) TKA designs: four were revised to a posterior stabilized (PS) TKA and one to a rotating hinge design because of the presence of a ruptured MCL.Conclusion:Further episodes of dislocation or instability will be prevented by identifying and treating major causes of instability. The increase in the level of constraint and correction of previous technical mistakes is mandatory.

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Infection is one of the most devastating complications of total knee arthroplasty. It is also the leading cause of early revision after knee arthroplasty, ahead of instability and aseptic loosening [ ].Treatment of an infected total knee arthroplasty requires to times more hospital resources than a primary arthroplasty and times more than an aseptic revision [ ]. The goal of treatment is to eradicate infection and maintain joint function. Two-stage exchange remains the treatment of choice in cases of late infection, with good or excellent results in % to % of cases nevertheless, it is aggressive, costly, and long. It is also considered the treatment of choice in cases of fungal infection, infection by virulent organisms, inflammatory diseases, immunosuppression, and reinfection after reimplantation.Compared with direct replacement, -stage revision of infected arthroplasty has several disadvantages longer hospital stay, higher cost, longer surgical time, tissue retraction, instability, and functional limitation between procedures. From a technical standpoint, surgical reimplantation may be hampered by retraction of soft tissue and loss of tissue planes.Most authors agree that almost all of these problems can be minimized using antibiotic-loaded articulating cement spacers, although -stage exchange can be used to eradicate infection both with and without cement spacers.

BackgroundHip arthroplasties is one of the most frequent surgical procedures in Spain and are conducted mainly in elderly subjects. We aim to analyze changes in incidence, co-morbidity profile, length of hospital stay (LOHS), costs and in-hospital mortality (IHM) of patients undergoing primary total hip arthroplasty (THA) over an 8-year study period in Spain.MethodsWe selected all surgical admissions in individuals aged ≥40 years who had received a primary THA (ICD-9-CM procedure code 81.51) between 2001 and 2008 from the National Hospital Discharge Database. Age- and sex-specific incidence rates, LOHS, costs and IHM were estimated for each year. Co-morbidity was assessed using the Charlson comorbidity index.Multivariate analysis of time trends was conducted using Poisson regression. Logistic regression models were conducted to analyze IHM.ResultsWe identified a total of 161,791 discharges of patients having undergone THA from 2001 to 2008. Overall crude incidence had increased from 99 to 105 THA per 100.000 inhabitants from 2001 to 2008 (p < 0.001). In 2001, 81% of patients had a Charlson Index of 0, 18.4% of 1-2, and 0.6% > 2 and in 2008, the prevalence of 1-2 or >2 had increased to 20.4% and 1.1% respectively (p < 0.001). The mean LOHS was 13 days in 2001 and decreased to 10.45 days in 2008 (p < 0.001). During the period studied, the mean cost per patient increased from 6,634 to 9,474 Euros. Multivariate analysis shows that from 2001 to 2008 the incidence of THA hospitalizations has significantly increased for both sexes and only men showed a significant reduction in IHM after THA.ConclusionsThe current study provides clear and valid data indicating increased incidence of primary THA in Spain from 2001 to 2008 with concomitant reductions in LOHS, slight reduction IHM, but a significant increase in cost per patient. The health profile of the patient undergoing a THA seems to be worsening in Spain.

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