Perspectives on metaphyseal conservative stems
Tóm tắt
Total hip replacement is showing, during the last decades, a progressive evolution toward principles of reduced bone and soft tissue aggression. These principles have become the basis of a new philosophy, tissue sparing surgery. Regarding hip implants, new conservative components have been proposed and developed as an alternative to conventional stems. Technical and biomechanical characteristics of metaphyseal bone-stock-preserving stems are analyzed on the basis of the available literature and our personal experience. Mayo, Nanos and Metha stems represent, under certain aspects, a design evolution starting from shared concepts: reduced femoral violation, non-anatomic geometry, proximal calcar loading and lateral alignment. However, consistent differences are level of neck preservation, cross-sectional geometry and surface finishing. The Mayo component is the most time-tested component and, in our hands, it showed an excellent survivorship at the mid-term follow-up, with an extremely reduced incidence of aseptic loosening (partially reduced by the association with last generation acetabular couplings). For 160 implants followed for a mean of 4.7 years, survivorship was 97.5% with 4 failed implants: one fracture with unstable stem, 1 septic loosening and 2 aseptic mobilizations. DEXA analysis, performed on 15 cases, showed a good calcar loading and stimulation, but there was significant lateral load transfer to R3–R4 zones, giving to the distal part of the stem a function not simply limited to alignment. Metaphyseal conservative stems demonstrated a wide applicability with an essential surgical technique. Moreover, they offer the options of a “conservative revision” with a conventional primary component in case of failure and a “conservative revision” for failed resurfacing implants.
Từ khóa
Tài liệu tham khảo
Pipino F, Keller A (2006) Tissue-sparing surgery: 25 years’ experience with femoral neck preserving hip arthroplasty. J Orthop Traumatol 7(1):36–41
Carlson L, Albrektsson B, Freeman MA (1988) Femoral neck retention in hip arthroplasty. A cadaver study of mechanical effects. Acta Orthop Scand 59(1):6–8
Pipino F, Calderale PM (1987) Biodynamic total hip prosthesis. Ital J Orthop Traumatol 13(3):289–297
Jasty M, Krushell R, Zalenski E, O’Connor D, Sedlacek R, Harris W (1993) The contribution of the nonporous distal stem to the stability of proximally porous-coated canine femoral components. J Arthroplasty 8(1):33–41
Whiteside LA, White SE, McCarthy DS (1995) Effect of neck resection on torsional stability of cementless total hip replacement. Am J Orthop (10):766–770
Morrey BF (1989) Short-stemmed uncemented femoral component for primary hip arthroplasty. Clin Orthop Relat Res (249):169–175
Morrey BF, Adams RA, Kessler M (2000) A conservative femoral replacement for total hip arthroplasty. A prospective study. J Bone Joint Surg Br 82(7):952–958
Swanson TV (2005) The tapered press fit total hip arthroplasty: a European alternative. J Arthroplasty 20[4 Suppl 2]:63–67
Meldrum RD, Willie BM, Bloebaum RD (2003) An assessment of the biological fixation of a retrieved Mayo femoral component. Iowa Orthop J 23:103–107
Albanese CV, Rendine M, De Palama F et al (2006) Bone remodelling in YHA: a comparative DXA scan study between conventional implants and a new stemless femoral component. A preliminary report. Hip Int 16:9–15
Roth A, Richartz G, Sander K et al (2005). Periprosthetic bone loss after total hip endoprosthesis. Dependence on the type of prosthesis and properative bone configuration. Orthopade 34(4):334–344
Berger RA (2004) The technique of minimally invasive total hip arthroplasty using the two-incision approach. Instr Course Lect 53:149–155