Purpose of the study: The survival of a total hip arthroplasty (THA) depends mainly on the choice of the implant and the quality of the implantation. Mini-incisions have been criticised because of the increased risk of complications and the uncertainty concerning implant position. The main objective of this work was to assess this later feature.

Material and method: This was a prospective series of consecutive patients attending different centres from January 2008 to January 2009 comparing 100 THA implanted via the reduced Watson-Jones approach (2 centres) and 520 THA implanted in a third centre via the anterior hemimyotomy. Objective assessment (PMA, Harris) and early functional outcome (WOMAC, SF12), biological aggression (myoglobinaemia, CPK, blood loss), complications, and scanographic position of the implants were analysed.

Results: For the mini-Watson-Jones arthroplasties, there was a longer operative time (p< 0.0001), smaller scar, less consumption of analgesics the first postoperative day (p=0.003), and better objective and functional recovery at six weeks (PMA: p < 0.0001; Harris: p = 0.004; WOMAC: p < 0.0001; SF12: p = 0.007). Conversely, there was no significant difference for intraoperative or postoperative blood loss, intraoperative and early postoperative complications, elevation of serum muscle markers, or duration of hospital stay. Regarding implant position, significantly greater acetabular and cumulated anteversion was observed with the mini-incision (p=0.03 and p=0.002 respectively). Nevertheless, the proportion of well positioned implants (Lewinnek criteria) was not significantly different.

Discussion: This series confirms the contribution of the mini-incision to more rapid recovery. We did not find any difference in implant malposition related to approach. The first analyses did however show that the position of the implants is more reproducible with the conventional approach.

Purpose of the study: The purpose of this study was to assess traumatic damage to muscles using biological markers. Two approaches were evaluated: a modified Hardinge approach (anterior hemimyotomy) and a reduced anterolateral approach (Rottinger).

Material and method: This was a multicentric prospective study conducted in three centres in 2008. The first 50 patients in each centre were included. Total creatinine phosphokinase (CPK) and serum myoglobulin levels were used to evaluate muscle damage. Blood samples were taken ten hours after surgery for myoglobulaeia and at one and two postoperative days for CPK. Student’s t test was used for the statistical analysis.

Results: There was no statistically significant difference in serum myoglobulin levels 10 hours postoperatively (p=0.25) or for CPK level at day 1 (p=0.098) and day 2 (p=0.105). Objective clinical recovery (Postel-Merle-d’Aubigné, Harris) and function (WOMAC and SF-12) were better at six weeks with the reduced anterolateral approach.

Discussion: These findings show that muscle aggression after mini-incision is to the same order as with the standard approach. The damage is however different: section for the Hardinge type approaches, stretching and contusion for the mini-incisions.

Conclusion: Use of biological markers specific for muscle tissue appears to be a simple way of quantifying muscle damage. However, adjunction of an imaging technique (MRI) might provide a more precise assessment of muscle injury.

Purpose of the study: Radiographs of 24 patients who underwent surgery for total hip arthroplasty (THA) with a locked stem were reviewed at 38 months mean follow-up using a dedicated software. This software enables digital analysis of standard radiographs with semiquantitative evaluation of bone density.

Material and method: Good quality postoperative AP views of the femur and the same view at last follow-up were selected using the same criteria. These images were digitalised then analyses with the software. Bone density was established along a horizontal line 1 cm below the lesser trochanter perpendicular to the femur shaft. Computer analysis of bone density established three categories of patients as a function of cortical density: no cortical modification (n=5 hips), modification of only one cortical (n=11) and modification of both corticals (n=8).

Results: Bone density increased, suggesting improve cortical bone stock as has been reported by most authors using the transfemoral approach and a non-cemented locked stem.

Discussion: This result confirms the data in the literature; data which, unlike our series, were established on qualitative or subjective evaluations. The method presented here has the advantage of a semi-quantitative analysis, simple use, applicable to plain x-rays, and good reproducibility since all measures are made by the software. This study demonstrated the notion of cortical quality since it was not limited to a simple measurement of width, but also bone density, closer to real intraoperative observations.

Conclusion: Use of this method enables longitudinal study to establish the kinetics of bone remodelling, compare results between surgical methods, and search for factors explaining observed variations.

Purpose of the study: Survival of a total hip arthroplasty (THA) mainly depends on the choice of the implant and the quality of the implantation. Use of minimally invasive approaches remains a subject of controversy due to the uncertain implant position and questions concerning increased perioperative complications. The purpose of this work was to assess these two elements in a consecutive series of patients who underwent THA implanted via the minimally invasive anterolateral approach described by Rottinger.

Materials and Methods: This was a consecutive series of 130 patients (84 female, 46 male, mean age 69 years, age range 46–91) operated by the same surgeon. Mean follow-up was twelve months (range 6 – 24 months). The clinical parameters studied were: the pre–and post-operative Postel-Merle-d’Aubigné (PMA) score, mean operative time, presence of perioperative surgical complications. Radiographic parameters studied were lucent lines (De Lee and Gruen), homogeneous cementing of the femoral piece, axial position of the femoral implant, angle of acetabular inclination, acetabular anteversion (Hassan), and any leg length discrepancy.

Results: Intraoperative complications were: one intraoperative mobilisation of a press-fit cup, one trochanter fracture. Postoperatively, the rate of dislocation was 2.3%. In 3.8% of the patients developed skin lesions or a local haematoma but none with infection. Mean operative time was 107 minutes (range 80–210). Mean postoperative PMA score was 17.4 versus 12.4 preoperatively. Patients were able to walk without limping 3.3 months postoperatively (range 0.5–12 months). Mean cup inclination and anteversion were 46.1° (28–60°) and 12.3° (0–35°) respectively. Leg length discrepancy was +4.8mm on average (operated side). Femoral alignment was ±3° relative to the femoral axis in 83% of hips. Homogeneous cementing of the femoral stem was noted in 84%. There was a learning curve with an 11% complication rate for the first twenty hips versus 4% for the remainder of the hips in this series.

Discussion: In our hands, the minimally invasive anterolateral approach described by Rottinger enables proper reproducible THA implantation. The rate of intraoperative complications is low. There is a learning curve which was an estimated twenty cases in our series. This method has become our first-intention option for implantation of THA.