Preoperative planning for total hip arthroplasty includes templating on anteroposterior radiographs. It is necessary to consider radiographic magnification in order to scale templates accurately. Studies dealing with hip templating report different values of radiographic magnification. It is not clear if the observed difference in magnification between the studies is caused by variability in studied groups, methodology or instrumentation. We hypothesize that there is a difference in magnification between clinical workplaces. Within this study, radiographic magnification was estimated on 337 radiographs of patients after total hip surgery from five orthopaedic departments in the Czech Republic. Magnification was determined for each patient as a ratio between diameter of implanted femoral head measured on radiogram and its true size. One-way ANOVA revealed significant differences in magnification between workplaces (F(4,332) = 132, p≤0.001). These results suggest that radiographic magnification depends on the workplace where it is taken or more precisely on radiographic device. It indicates potential limits in generalizability of results of studies dealing with preoperative planning accuracy to other institutions.

The potential of novel scaffold containing sodium hyaluronate, type I collagen, and fibrin was investigated in the regeneration of osteochondral defects in miniature pigs. Both autologous chondrocyte-seeded scaffolds and non-seeded scaffolds were implanted into two defects located in the non-weight-bearing zone of the femoral trochlea (defect A was located more distally and medially, defect B was located more proximally and laterally). Control defects were left untreated. Twelve weeks after the operation, the knees were evaluated in vivo using MRI. Six months after the implantation, the defects were analyzed using MRI, histological, and immunohistochemical analysis. In the A defects of chondrocyte-seeded scaffold group, hyaline cartilage and fibrocartilage was formed, containing type II collagen, acidic and neutral glycosaminoglycans while the non-seeded scaffold group was predominantly filled with fibrocartilage. Defects in the control group were predominantly filled with fibrous tissue. Histomorphometric analysis of photomicrographs revealed a significantly higher amount of hyaline cartilage in the cell-seeded scaffold group in A defects than in other groups. Both scaffold groups in A defects showed significantly less fibrous tissue than cell-seeded defects B and the control group. Both histological and MRI analysis proved that the novel composite scaffold has a potential to regenerate osteochondral defects within six months.

Purpose The aim of the present study was to introduce a novel oblong revision cup type TC for use in revision total hip arthroplasty (THA), and to evaluate mid-term results in terms of bone tissue remodelling in the immediate area of the implant. Methods The results of 31 patients that underwent revision THA between 2004 and 2008 are presented. The mean followup interval was 7.1 years (range 5.3-9.3 years, minimum of five years following revision). Osteointegration of the implant and bone tissue remodelling around the implant and ribs were assessed by X-ray and computed tomography (CT). Results The average Harris hip score increased from 39.8 to 85.3. Excellent results were achieved in nine patients, good in 16, fair in three and poor in three. According to X-ray results, 25 hips had a well-fixed, bone-ingrown cup and five had a stable fibrous union in the middle and the distal third of the implant. Proximal migration of the cup was noted in one case. Pelvic CT was additionally performed in ten patients. In all cases, we detected bone remodelling in the space between the implant ribs. Kaplan-Maier survivorship of the acetabular components was 94.2 % at 7.1 years. Conclusions Our results show that the novel oblong revision cup type TC is relatively simple to implant, and is associated with reliable primary fixation and documented osteointegration and bone remodelling in the immediate area.