Resumo

LOPREITE, Fernando A; MANA PASTRIAN, Diego; GARABANO, Germán  e  DEL SEL, Hernán. Initial performance of a cemented polished stem. Rev. Asoc. Argent. Ortop. Traumatol. [online]. 2010, vol.75, n.2, pp.157-163. ISSN 1852-7434.

Since the early 70s, the use of polished cemented stems in total hip replacement has proven successful in the long term. The purpose of this study was to prospectively assess the short-term mechanical behavior of a triple cone cemented polished stem. Methods: Forty three polished cemented stems were clinically and radiologically evaluated in 43 consecutive patients operated by the same surgeon (FAL), between October 2002 and May 2005. Three patients were excluded. Forty patients were finally evaluated. Twenty-four women (60%) and 16 men (40%). Average age was 61 years, average weight 79.8 kg, and average height 1.69 meters. Patients were grouped according to their body mass index (BMI). The average follow-up was 40 months (range: 24-55 months). In each case the following was determined: cement mantle quality, stem subsidence and femoral bone changes. The stem behavior was assessed by the same observer in all cases. Results: the stem subsidence was statistically analyzed, by gender, body mass index and work activity. The cement mantle, evaluated according to Barrack's classification, was: A in 36 cases (90%), B in 3 (7.5%) and D in 1 (2.5%). General stem collapse was on average 1.28 mm (range 0.5-3.5 mm) at a maximum of 3 years. In the first year subsidence was 1.16 mm (0.3-2.4 mm), in the second year 0.32 mm (0-1 mm), and in the third 0.045 mm (0-0.5 mm). There were no significant differences in the total collapse by sex, previous activity or BMI. Radiological changes on the proximal femur were seen in 94.7% of the cases. Conclusions: The geometry of polished cemented stems (without collar and conical) results in a higher survival rate. The controlled collapse within the cement mantle not only seals the interface, but improves the implant stability not only axially but in the torsional plane. This reduces synovial fluid circulation with the consequent decrease in metal particles and acrylic migration.

Palavras-chave : Polished cemented stem; Total hip replacement; Subsidence.

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