In patients with developmental dysplasia of the hip (DDH) chronic joint dislocation induces remodeling of the soft tissue with contractures, muscle atrophy, especially of the hip abductors muscles, leading to severe motor dysfunction, pain and disability (1). The aim pf the present work is to explore if a correct positioning of the prosthetic implants through 3D skeletal modeling surgical planning technologies and an adequate customized rehabilitation can be beneficial for patients with DDH in improving functional performance.

The project included two branches: a methodology branch of software development for the muscular efficiency calculation, which was inserted in the Hip-Op surgical planning system (2), developed at IOR to allow surgical planning for patients with complex hip joint impairment; and a clinical branch which involved the use of the developed software as part of a clinical multicentric randomized trial. 50 patients with DDH were randomized in two groups: a simple surgical planning group and an advanced surgical planning with muscular study group. The latter followed a customized rehabilitation program for the strenghtening of hip abductor muscles. All patients were assessed before surgery (T0) and at 3 (T1) and 6 months (T2) postoperatively using clinical outcome (WOMAC, HHS, ROM, MMT, SF12, 10mt WT) and instrumental measures (Dynamometric MT). Pre- and post-operative musculoskeletal parameters obtained by the software (i.e., leg length discrepancy, hip abductor muscle lengths and lever arms) using Hip-Op during the surgical planning were considered.

One Way ANOVA for ROM measurement showed a significant improvement at T2 in patients included in experimental group, as well as WOMAC, HHS and SF12 score. The Dynamometric MT score showed significant differences between at T2 (p<0.009).

Spearman's rank correlation coefficients showed a significant correlation between both pre- and post-operative abductors lever arm (mm) and hip abductor muscle strength at T2 (ρ = −0.55 pre-op and ρ = −0.51 post-op, p p<0.012 and p<0.02 respectively) and between the operated pre-postoperative leg length variation (mm) and the hip abductor muscle strength (ρ = −0.55, p p<0.013).

Results so far obtained showed an improvement of functional outcomes in patients undergoing hip replacement surgery who followed therapeutic diagnostic pathway sincluding a preoperative planning including the assessment of the abductiors lever arm and a dedicated rehabilitation program for the strenghtening of abductios. Particularly interesting is the inverse relationship between the strength of the hip abductor muscles and the variation of the postoperative abductor lever arm.

Introduction. Polymethylmethacrylate(PMMA) bone cement has been used in joint reconstruction surgery and recently introduced for treatment of osteoporotic vertebral compression fracture. However, the use of PMMA bone cement in vertebroplasty leads to extensive bone stiffening and high rate of adjacent vertebrae fracture. Aim. The purpose of this study was to investigate the properties of PMMA bone cement augmented with collagen and assess its characteristics and relevance for the reduction of complication rate associated with vertebroplasty. Methods. Bone cement was produced using 2 types of PMMA based bone cement. Augmented groups were prepared using 40g of bone cement with 1% of rat tail liquid collagen. Mixing was conducted in controlled laboratory environment and at room temperature. The working and setting time and the mechanical properties were determined in accordance to ASTM standards for acrylic cements. The effect of ageing in simulated body fluid(SBF) on mechanical properties of these cements and the microstructure were studied. Results. Addition of collagen to bone cement has shown no marked effect on the working and setting time and produces bone cement with good injectability. The compressive strength is not affected but the modulus shows the material is less brittle than PMMA. Conclusion. Addition of liquid collagen to PMMA based bone cement does not necessarily compromise the properties of the cements and produce cement with good injectability and less brittle than PMMA based bone cement alone. However, bone cement augmented with different concentration of collagen need to be studied further in order to assess its clinical relevance especially in vertebroplasty

Summary Statement. The frictional torque of ceramic-on-ceramic bearings tended to increase with increasing the bearings size (32, 48, 56mm). However, the frictional torque was significantly lower than that measured on metal-on-metal bearings under well positioned and well lubricated conditions. Introduction. Larger head size in total hip replacement theoretically provides increased range of motion and enhanced stability. However, there are potential clinical concerns regarding increased frictional torques with large diameter metal-on-metal bearings causing loosening of the acetabular cups and corrosion at the taper. The aim of this study was to determine the frictional torques of large diameter BIOLOX® delta ceramic-on-ceramic bearings. Materials and Methods. The single-station pendulum friction simulator (SimSol, UK) was used to determine the frictional torque of three ceramic-on-ceramic bearing sizes: 32mm and 48mm (DeltaMotion®, DePuy Synthes Joint Reconstruction, Leeds, UK) and a 56mm prototype design. Four repeats were tested for each bearing size using 100% new-born calf serum, 25% new-born calf serum and water as lubricants. The input profiles were a simplified loading regime with a peak of 2kN and an angular motion of ±25° [1]. The frictional torque was determined under swing phase loads of 25N, 100N or 300N. The bearings were tested under standard conditions where the cup was positioned so the face was horizontal to the loading axis and at an inclination angle equivalent to 65° in vivo. Results. When lubricated with 100% serum, size 48mm bearings showed similar frictional toque to the 32mm bearings (1.5Nm and 1.7Nm respectively, p=0.28), however, the frictional torque of the 56mm prototype design bearings was significantly higher (2.2Nm, p=0.01). When using 25% serum, there was a trend of increased frictional torque (p=0.016) with increased head size; increasing from 1.2 Nm to 1.5 Nm to 1.9 Nm for the 32mm, 48mm, and 56mm bearings respectively. The frictional torque significantly decreased when water was used compared to using new-born calf serum as lubricant. There was no significant difference in the frictional torque between all bearings sizes with water as lubricant, however, there was a trend of increased frictional torque with increased swing phase load. Changing the swing phase load had no influence on the frictional torques obtained for all bearing sizes when using 100% or 25% new-born calf serum. Under a steep inclination angle, the frictional torque for all bearing sizes did not significantly change compared to the flat cup condition. Discussion and Conclusion. The frictional torque tended to increase with increased head size. The highest frictional torque measured in this study was 2.5Nm for the 56mm ceramic-on-ceramic bearing (25% serum, steep cup) compared to 5.3Nm maximum torque measured using the same method for well-positioned and well lubricated 54mm metal-on-metal bearings. The frictional torque for all ceramic-on-ceramic bearing sizes (32mm, 48mm, and 56mm) decreased as the concentration of protein decreased. This was consistent with previous work done on 28mm bearings and the understanding that for ceramic-on-ceramic bearings the adherence of proteins to the surface reduces the effectiveness of lubricant film thickness, thus resulting in higher frictional torques due to the force required to shear the proteins

Objectives

Evidence -based medicine (EBM) is designed to inform clinical decision-making within all medical specialties, including orthopaedic surgery. We recently published a pilot survey of the Canadian Orthopaedic Association (COA) membership and demonstrated that the adoption of EBM principles is variable among Canadian orthopaedic surgeons. The objective of this study was to conduct a broader international survey of orthopaedic surgeons to identify characteristics of research studies perceived as being most influential in informing clinical decision-making.