RESUMO
Total hip arthroplasty stem fracture is an important contributor to morbidity rate and increases the cost of revision surgery. Failure is usually caused by issues related to overload, inadequate stem support, inappropriate stem design or dimensions and material processing. In this study, the role of the relationship between material characterization and biomechanical performance in the fracture of retrieved stems was explored. The stems were manufactured with forged stainless steel, had the same length, 12/14 trunnion, and 28-mm head. These stems were evaluated by macroscopic and microscopic examination to identify the causes of premature failure. Each stem was sectioned into four regions, and the cross-sections were used for the microhardness and grain size analysis. Finite element analysis (FEA) was carried out, considering the stem positioned at the femur, a musculoskeletal model, and biomechanical loading. All stems had fractured through a fatigue mechanism, mainly a unidirectional bending loading condition, with crack nucleation on the lateral side and propagation on the medial side. The numerical analysis revealed maximum mechanical stress on the lateral side of the stem neck, but this was below the yield stress calculated via the hardness. The use of a shorter head neck length could reduce the maximum mechanical stress at the neck. At a cross-section near the plane of the stem fracture, the hardness was lower than that normally reported by the ASM, and there were heterogonous and coarse grain sizes on the lateral side. The main cause of failure of the two stems analyzed was a combination of low hardness and coarse grain size, due to inappropriate materials processing, worsen by a high level of stress on the lateral side of the neck due to the large stem-head offset selected by the orthopedic surgeon.
Assuntos
Artroplastia de Quadril , Prótese de Quadril , Artroplastia de Quadril/efeitos adversos , Fêmur/cirurgia , Humanos , Desenho de Prótese , Falha de Prótese , ReoperaçãoRESUMO
OBJECTIVE: To synthesize available evidence about diagnostic accuracy of clinical tests and imaging examinations for femoroacetabular impingement (FAI) syndrome. DESIGN: Umbrella review. SETTING: N/A. PARTICIPANTS: N/A. INTERVENTIONS: N/A. MAIN OUTCOME MEASURES: Systematic reviews (SR) indexed in Embase, LIVIVO, PubMed, SCOPUS, the Cochrane Library, and Web of Science were searched in a 2-phase process. SR assessing diagnostic accuracy were considered eligible. RESULTS: From 1520 studies, 6 SR were included, which evaluated 24 primary studies related to FAI syndrome. Of these, 5 SR assessed clinical tests, and a substantial heterogeneity was found concerning reference standards adopted across primary studies, which included arthroscopy, clinical examination (associated or not with imaging exams), intra-articular injections, and open surgery. Most clinical tests presented higher values of sensitivity compared with specificity, although evidence was considered limited because the same primary studies were often included across SR. Nonetheless, evidence around the flexion adduction internal rotation (FADIR) test was considered stronger and its use as a screening tool was consistently supported. Only one SR assessed the accuracy of imaging examinations, which adopted open surgery as the sole reference standard. Most imaging exams presented considerably high values of sensitivity, although specificity values were notably lower. CONCLUSIONS: No robust recommendations can be provided for most clinical tests, although the FADIR test, in particular, was consistently supported as a screening tool. Moreover, although imaging examinations showed considerably high sensitivity values, evidence was considered sparse and further research is strongly recommended to validate its use as reference standards for diagnostic accuracy data.
Assuntos
Impacto Femoroacetabular , Humanos , Artroscopia , Impacto Femoroacetabular/diagnóstico por imagem , Exame Físico/métodos , Amplitude de Movimento Articular , Sensibilidade e Especificidade , Revisões Sistemáticas como AssuntoRESUMO
BACKGROUND: Hip osteoarthritis is one of the major causes of disability worldwide, and although total hip arthroplasty is considered effective in the management of this condition, its effects on postural balance remain unclear. RESEARCH QUESTION: What are the effects of total hip arthroplasty for primary hip osteoarthritis on the postural balance compared to preoperative status and/or to healthy controls?. METHOD: A systematic review was conducted, and the Embase, Latin American and Caribbean Health Sciences (LILACS), PubMed, Scopus, The Cochrane Library, and Web of Science databases were searched. Randomized and non-randomized studies were considered eligible for inclusion. The risk of bias of included studies was assessed using the Joanna Briggs Institute critical appraisal tools. RESULTS: Among the 41 potentially eligible studies, 13 studies were included for qualitative synthesis-8 studies had low risk of bias and 5 had moderate risk of bias. Ten studies compared the effects of total hip arthroplasty on the postural balance in healthy controls. Meanwhile, the remaining 3 studies compared such effects to the preoperative status only. Comparable results on the postural balance between the intervention and control groups were observed in 5 studies, whereas 3 studies showed better scores among healthy controls. The other 2 studies reported that postural balance could still be impaired at 6 months to 3 years postoperatively. All 3 studies with no healthy controls reported an improvement in the postural balance compared to the preoperative status. CONCLUSIONS: Major post-surgical improvements were consistently observed compared to preoperative status, although postural balance impairment was still noted compared to healthy controls. SIGNIFICANCE: The results of this study might be a useful guide for clinicians on the extent of the therapeutic effects of hip arthroplasty on postural balance. Furthermore, the standardization of balance assessment tools could strengthen the certainty of cumulative evidence in future studies.