293 Table 2. Cement mantle integrity according to Barrack Barrack classification Antero-lateral n (%) Table 3. Stem alignment on AP radiograph 40 (30) 93 (69) 2 (2) 0 Antero-lateral n (%) 121 (90) 7 (5) 7 (5) Antero-lateral n (%) 104 (77) 5 (4) 26 (19) Posterior n (%) 44 (33) 84 (62) 7 (5) 0 Posterior n (%) 111 (82) 21 (16) 3 (3) Posterior n (%) 102 (76) 19 (14) 14 (10) Acta Orthopaedica 2010; 81 (3): 292–295 Table 1. Demographic data of study group Anterolateral approach Posterior approach (n = 135) (n = 135) Patients (bilateral) Mean age (range) Male/female Left/right Diagnosis OA RA Post-traumatic OA DDH Other BMI (range) 115 (20) 67 (31–90) 38/97 68/67 120 (89%) 0 2 (2%) 7 (5%) 6 (5%) 29 (17–34) 122 (13) 68 (46–82) 51/84 68/67 114 (85%) 2 (2%) 3 (2%) 10 (8%) 6 (5%) 28 (21–32) BMI only available for 204 patients: 101 patients in the antero-lateral group, 103 patients in the posterior group. formed with third-generation cementing techniques (distal femoral cement restrictor, pulsatile lavage, retrograde cement application via gun, and cement pressurization with a proximal femoral silicon seal). All procedures were carried out either by a consultant arthroplasty surgeon or a trainee under the direct supervision of a consultant arthroplasty surgeon. Our practice is to remove the prominent posterior calcar femorale to permit posterior canal entry. The stem size corresponding to the last broach inserted allowed for a nominal minimal cement mantle of 2 mm. Radiographs with standard anterior-posterior (AP) views were taken 2 days after surgery. No lateral views were obtained at this stage, due to difficulties in positioning the patient in the early postoperative period. Lateral radiographs were obtained 1 year postoperatively at routine follow-up. Radiographic analysis was done by CH and MS, who were not involved with the surgical procedures. The analysis included comparison of early postoperative AP radiographs and AP and lateral radiographs taken 1 year postoperatively. The measurements were taken with a calibrated sliding ruler using the femoral head size as a reference. The integrity of the cement mantle was graded according to Barrack et al. (1992) and cement mantle thickness was mea- sured in all 14 Gruen zones. Varus/valgus and lateral malalign- ment of the stem was defined as a deviation from the longitu- dinal axis of 3 or more degrees (Joshi et al. 1998). The femoral diaphysis was used as the reference on the lateral radiographs. Statistics Chi-squared tests using SPSS version 12.0 software were used for unadjusted comparisons between the two groups, and mixed-model logistic regression using MLwiN software was used to test the effect of approach after adjusting for the potential confounding effects of age, BMI, sex, diagnosis, stem alignment on AP, and lateral views. This method also allowed for the lack of independence of results from patients undergoing bilateral operations. A B C D Alignment Neutral Varus Valgus Alignment Neutral Anterior Posterior Table 4. Stem alignment on lateral radiograph Results Cement mantle quality (Table 2) Chi-squared testing did not reveal any statistically significant differences in cement mantle quality between the groups (p = 0.1). Stem alignment (Tables 3 and 4) There was no statistically significant difference in stem align- ment between the two groups on AP (p = 0.06) and lateral radiographs (p = 0.5). Cement mantle thickness (Table 5) In the antero-lateral approach group, only 47% had a cement mantle of at least 2 mm in all 14 zones, compared to 62% in the posterior approach group. This difference was statistically sig- nificant (OR = 1.8, 95% CI: 1.1–3.0; p = 0.03). After adjusting for age, sex, diagnosis, cement mantle quality, and stem align- ment, the surgical approach remained significant (OR = 2.5, 95% CI: 1.4–4.6; p = 0.002). The highest incidence of reduced cement mantle thickness in both groups was seen antero-proxi- mally on lateral radiographs (Gruen zones 8 and 9). In the antero-lateral approach group, only 68% had a cement mantle thickness of ≥ 2 mm in Gruen zone 8. In the posterior approach group, 79% had a ≥ 2-mm cement mantle in the same