Texture analysis of trabecular bone around RM-Pressfit cementless acetabulum in a series of 46 patients during a 5 year period.

BACKGROUND: Cementless total hip arthroplasty (THA) is a common procedure producing excellent clinical results. Their long-term survival is nevertheless burdened by loosening of the acetabular part caused by changes in the distribution of strains around the cup. In this context the RM-Pressfit® cup has been developed, resulting in a more harmonious distribution of the strains. HYPOTHESIS: Texture analysis of X-ray films can evaluate the evolution of trabecular bone micro-architecture during the five years following THA with a RM-Pressfit® cup. MATERIAL AND METHOD: A monocentric series of 46 hips was reviewed regularly within five years post- surgery. Radiographic evaluation of the operated hip was done on frontal digitized radiographs of the pelvis to follow evolution of bone micro-architecture in the #2 zone of De Lee and Charnley. Texture analysis using fractal algorithms was done at D0, 6 months, 1, 2 and 5 years post-THA. The fractal methods used included the skyscrapers and the dynamic blanket methods with 3 different structuring elements (a cross, a horizontal and a vertical vector). RESULTS: The RM-Pressfit® caused significant changes in the distribution of strains around the acetabulum that preserved the bone volume over a 5-year period post-surgery. This corresponds to an improvement of the trabecular micro-architecture around the acetabular cups. CONCLUSION: A statistically significant increase in the four fractal dimensions considered corresponded to an improved trabecular bone micro-architecture revealed by texture analysis, a non-invasive method that can be used on digitized X-ray images. LEVEL OF EVIDENCE: IIIb, Case control study, retrospective design.

A rare case of Prosthetic Joint Infection associated with Coxiella burnetii.

We report here the case of a Prosthetic Joint Infection (PJI) associated with Coxiella burnetii in a 62-year-old man with a revised total hip arthroplasty. The diagnosis was performed first by 16S rDNA sequencing on hip fluid aspirate, and confirmed by specific qPCR. Q fever has been reported in few cases of Prosthetic Joint Infections, often associated with chronic evolution and iterative surgeries. This case report alerts about such an unexpected diagnosis in a patient with no known risk factors.

Total hip arthroplasty after failed fixation of a proximal femur fracture: Analysis of 59 cases of intra- and extra-capsular fractures.

INTRODUCTION: The indications for total hip arthroplasty (THA) after failed internal fixation of a proximal femur fracture vary. Published studies on this topic are broad-ranging and do not distinguish between intracapsular and extracapsular fractures. This led us to conduct a retrospective analysis comparing the clinical outcomes, radiological outcomes, technical problems and complications between these two types of fractures. HYPOTHESIS: The functional outcomes of THA after an extracapsular fracture will be worse than the ones after an intracapsular fracture. MATERIAL AND METHODS: This was a retrospective, single-center study of 59 THA cases performed after internal fixation of a proximal femur fracture. These procedures were performed between 2002 and 2013 in 58 patients (22 men, 36 women). There were 40 intracapsular fractures and 19 extracapsular fractures. The initial fracture fixation involved a screw-plate (n=50), intramedullary nail (n=6) or screws (n=3). The mean patient age at the time of THA was 67 years [22-94]. The THA was performed an average of 2.8 years [0.2-28] after the fracture. The posterolateral approach was used in 55 cases (93%). Ten patients (17%) had the fixation hardware removed before the THA procedure, on average at 30 months [1-240] after the fracture. During the THA procedure, a cemented stem was used in 31 cases (53%) and a cementless stem in 28 cases (47%). A cementless press-fit cup was used in 56 cases (95%), of which 35 were dual mobility cups (60%), and a cemented cup was used in the other 3 cases (5%). All patients were reviewed by a physician not involved in the surgical procedures who performed a clinical and radiological examination. RESULTS: No patients were lost to follow-up; two patients died. Ten patients suffered an intraoperative femur fracture (17%) and four suffered a dislocation (2 early, 2 late) (6.8%). Nine hips had to be reoperated (15%), of which five required an implant change (8.5%). There were significantly more intraoperative fractures and postoperative complications in the THA cases after extracapsular fracture. With a mean follow-up of 38 months [12-149], the mean PMA and Harris scores were 14.6 [3-18] and 74 [10-100], respectively; these scores were significantly lower in the THA cases after extracapsular fracture (p<0.05). With an endpoint of revision with implant change, the overall 40-month survival was 94% (95% CI: 0.25-0.55); it was 97% (95% CI: 0.62-0.85) for the intracapsular fracture cases and 84% (95% CI: 0.39-0.75) for the extracapsular fracture cases (p<0.05). CONCLUSION: Secondary THA after failed fixation of proximal femur fractures has more complications than primary THA. Subgroup analysis identified more technical problems in the THA cases after extracapsular fracture and a higher number of complications, particularly dislocation and periprosthetic fractures. LEVEL OF EVIDENCE: IV - Retrospective study.