292 Acta Orthopaedica 2010; 81 (3): 292–295 The posterior approach reduces the risk of thin cement mantles with a straight femoral stem design Gavin J Macpherson, Christian Hank, Michael Schneider, Morag Trayner, Robert Elton, Colin R Howie, and Steffen J Breusch Department of Orthopaedic Surgery, University of Edinburgh, The Royal Infirmary of Edinburgh, UK Correspondence: steffen.breusch@ukonline.co.uk Submitted 09-03-13. Accepted 09-12-13 Background and purpose The properties of the cement mantle around a prosthesis are important. We investigated whether the surgical approach to the hip influences the quality and thickness of the cement mantle when using a straight femoral stem design. Methods In a consecutive multi-surgeon series, we reviewed the radiographs of 270 patients after cemented Exeter total hip arthroplasty. 135 stems were introduced using an antero-lateral (transgluteal) approach and 135 stems were introduced using a posterior approach. Anterior-posterior and lateral radiographs were reviewed and cement mantle thickness was measured in Gruen zones 1–14. We graded cement mantle quality according to the Barrack classification. Results Barrack grading did not reveal any difference in cement mantle quality between the two groups. AP and lateral radiographs showed no difference in stem alignment between the groups. The risk of a thin cement mantle (< 2 mm) was lower with a posterior approach (OR = 1.8, 95% CI: 1–3; p = 0.03). The greatest risk of a cement mantle thickness of < 2 mm occurred in Gruen zones 8–9 regardless of the surgical approach used. Interpretation With a straight femoral stem design, the pos- terior approach to the hip joint appears to give a lower risk of a thin cement mantle. Irrespective of the approach, there was a risk of thin cement mantles in Gruen zones 8 and 9, which highlights the importance of lateral radiographs in the postoperative radio- graphic assessment of total hip replacements.  There is no data available that defines the optimal cement mantle thickness in total hip arthroplasty. There is, however, evidence that a cement mantle of 2–3 mm is associated with a better long-term radiographic outcome (Ebramzadeh et al. 1994, Joshi et al. 1998). Thin cement mantles are more prone to crack (Kwak et al. 1979, Kawate et al. 1998), thus open- ing the bone-cement interface to wear particles and fluid pres- sure (Bartlett et al. 2008). This has been documented to cause localized osteolysis (Huddleston 1988, Anthony et al. 1990, Schmalzried et al. 1997) and failure (Olsson and Jernberger 1981, Jasty et al 1991, Cristofolini et al. 2007). Several fac- tors influence the quality of the cement mantle: the cement- ing technique (Mulroy et al. 1990, Britton et al. 1996, Mal- chau and Herberts 1998), femoral anatomy (Crawford et al. 1999, Breusch et al. 2001), stem design and instrumentation (Garellick et al. 1999, Östgaard et al. 2001), centralizer usage (Berger et al. 1997), and stem size (Krismer et al. 1991, Mas- soud et al. 1997, Scheerlinck et al. 2008). Due to the anatomical shape of the proximal femur, there is a risk of producing thin cement mantles anterior-proximally (Garellick et al. 1999, Breusch et al. 2001, Valdivia et al. 2001). An antero-lateral surgical approach has been shown to adversely affect the orientation of the tip of the femoral com- ponent (Vaughan et al. 2007), but little else is known about the effect of the surgical approach to the hip with regard to stem alignment and cement mantle thickness or quality. We investigated the influence of surgical approach on cement mantle thickness and cement mantle quality using the straight Exeter femoral stem by comparison of posterior and antero-lateral approach in a multi-surgeon series. Patients and methods This was a prospective, consecutive, multi-surgeon series of 270 cemented primary total hip replacements performed in 2005 at our university teaching hospital (Table 1). Patients with a previous femoral osteotomy were not included. The Exeter stem (Stryker Orthopaedics, Mahwah, NJ) was used in all cases. All procedures were carried out with the patient in a lateral decubitus position. 135 patients were operated on using an antero-lateral approach to the hip joint and 135 patients using a posterior approach. Preoperative templating on AP radiographs was under- taken to determine the optimum femoral implant allowing for a cement mantle of at least 2 mm. All operations were per- Open Access - This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the source is credited. DOI 10.3109/17453674.2010.487239