Introduction

To evaluate the effect of hydroxyapatite coating, two same shape cementless stems were compared in this randomized control trial study.

Objectives

Our principle is to bring the socket back to the true acetabulum position. A large structural bone graft is required for severe subluxation. We obtained good long-term results with structural bone grafts. It is necessary to evaluate the bone graft 3 dimensionally, not 2 dimensionally.

The material properties of gamma irradiated Ultra High Molecular Weight (UHMW) polyethylene are known to degrade during exposure to air. Though gamma inert-sterilization has been developed to decrease free radicals, the rate of degeneration of UHMW polyethylene in vivo has not well known. This study aimed to compare the properties of gamma inert-irradiated highly-cross-linked UHMW polyethylene samples after exposure to air and the properties of gamma inert-irradiated highly-crosslinked UHMW polyethylene samples after exposure to liquid.

UHMW polyethylene samples were machined from heat-compressed sheet made of medical grade GUR 1050 (Ticona, Kelsterbach, Germany). Samples were rectangular, where the dimensions were 50mm in length, 5 mm in width and 2 mm in thickness. Samples were divided into four groups of 0, 60, 100 and 200 kGy irradiation in N2 gas. These samples were then exposed to air or Ringer’s solution for half a year. Dynamic vis-coelastic measurements and, Fourier Transform Infrared Spectrometry (FTIR) and Electron Spin Resonance (ESR) analyses were performed on samples immediately after inert-irradiation, after half-year-exposure to 25°C air (Air-exposure) and after half-year-exposure to 37°C Ringer’s solution (Liquid-exposure). Dynamic viscoelastic measurements were conducted over a temperature range of −150 to 350°C using a Dynamic Mechanical Spectrometer (Seiko Instruments, Osaka, Japan). FTIR analysis was conducted using a Perkin-Elmer Spectra BX (Norwalk, CT) with 100-μm thick slices. ESR analysis was also conducted using a JES-TE200 (Nippon-Denshi, Akishima, Japan).

Although the dynamic viscoelastic performance of 0 kGy irradiated storage sample was not different from that of original sample, the loss tangent value (tanδ, E”/E’) of 60, 100 and 200 kGy irradiated storage samples was different from that of original samples (Fig. 1). The difference of Liquid-exposure was larger than that of Air-exposure. Although a FTIR peak at 1718 cm-1 wave numbers was not observed in 0 kGy irradiated storage sample, obvious peak was observed in 100 and 200 kGy irradiated storage samples (Fig. 2). The peak of Liquid-exposure was larger than that of Air-exposure. The ESR analysis showed free radicals in storage samples.

The dynamic viscoelastic performance of 60, 100, 200 kGy irradiated storage sample was different from that of original sample, whereas the performance of 0 kGy irradiated storage sample was not different from that of original sample. The difference of Liquid-exposure was larger than that of Air-exposure. The storage modulus value of 60, 100, 200 kGy irradiated Liquid-exposure decreased and the reason for this was thought to be chain scission by oxidation for half-year exposure to Ringer’s solution. Obvious FTIR peak at 1718 cm-1 wave numbers was observed in 100 and 200 kGy irradiated storage samples. The peak of Liquid-exposure was larger than that of Air-exposure. This indicated that the oxidation of Liquid-exposure quickly progressed during half-year storage and the reason for this was thought to be chain scission by high liquid temperature. The results of the present study suggested that the properties of gamma irradiated UHMW polyethylene quickly degraded in vivo.

Introduction: We compared the discrepancies between postoperative femoral component and the preoperatively predicted postoperative femoral component anteversions from CT data in cases of cementless THA, in which custom-made femoral components prepared from CT data were inserted directly without reaming or broaching.

Materials and methods: The subjects were 44 females (51hips) and 11 males (11 hips) with an average age at surgery of 54 years (range, 21–74). The average duration of follow-up was 44 months (range, 24–75). The femoral component was designed from 2 circles showing the corner of the medial and lateral rims of the component along the medial and lateral inner cortex on each CT slice. The anterior and posterior rims of the component were designed as lines connecting the 2 circles. From a CT slice of the planned osteotomy site and a slice passing through the knee, the preoperative femoral neck anteversion was measured. The postoperative femoral component anteversion was measured from the CT slice passing through the center of the ball and the slice passing through the knee.

Results: The mean discrepancy between the postoperative femoral component anteversion and the preoperatively predicted postoperative anteversion was 1.9° (range, −29.5–38). The average preoperative Harris hip score was 44 points (range, 17–80). At the most recent follow-up, the score was 88 points (range, 51–98). Sixty-one hips were evaluated as bone-ingrown fixations and one hip was evaluated as a stable fibrous fixation. There were no loosed femoral components.

Discussion and conclusion: There were 22 hips whose discrepancy between the postoperative femoral component anteversion and the preoperatively predicted postoperative anteversion was over 10°. However, the rotational angle on insertion did not influence the stability of the custom-made femoral component in this short-term follow-up survey. This probably indicates the effectiveness of the non-reaming or non-broaching technique.