Titanium (Ti) is well known in orthopedic implant materials such as total hip replacement arthroplasty. Osseointegration of orthopedic implants is defined as the formation of a direct interface between the implant and the bone without intervening soft tissue. Unmodified Ti is not sufficient to complete adhesion between Ti surface and host bone with subsequent implant loosening over time and ultimately implant failure. An effective approach to enhance the biological activity of orthopedic implants and improve post-implantation healing is to modify the implant surface. The aim of this study was to investigate the effect of functionalized titanium (Ti) with alendronate (Aln) and bone morphogenic protein-2 (BMP-2) for enhancement of osteoblast activity in vitro.

Aln and/or BMP-2 were sequentially immobilized to the heparinized-Ti (Hep-Ti) surface. The compositions of pristine Ti and Hep-Ti with or without Aln and/or BMP-2 were characterized by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). Osteoblast activities on all Ti substrates were investigated by cell proliferation assays, alkaline phosphate (ALP) activity, calcium deposition, gene expressions of osteocalcin and osteopontin.

The modified Ti surface with heparin, Aln, BMP-2 and Aln/BMP-2 showed similar morphologies compared to that of pristine Ti on scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). Aln or BMP-2 from Aln/Hep-Ti, BMP-2/Hep-Ti or Aln/BMP-2/ Hep-Ti substrates exhibited sustained release profiles up to 4 weeks. No significant cytotoxic effects were observed for incubation periods for up to 48 h. the ALP activity of MG-63 cells cultured on Hep-Ti was not significantly different compared to those cultured on pristine Ti for 7, 14, and 21 days. Alkaline phosphatase(ALP) activities of osteoblasts cultured on Ti groups immobilized with Aln, BMP-2, or Aln/BMP-2 were significantly increased when compared to pristine Ti(p < 0.05). Calcium deposition was markedly increased in Aln/BMP-2/Hep-Ti compared to Aln/Hep-Ti or BMP-2/Hep-Ti, respectively (p < 0.05). mRNA expressions of osteocalcin(OCN) and osteopontin(OPN) of osteoblasts grown on Aln/Hep-Ti, BMP-2/Hep-Ti, and Aln/BMP-2/Hep-Ti were significantly higher than of those grown on pristine Ti (p < 0.05).

Based on the results of the in vitro studies, we showed that co-delivery of alendronate and BMP-2 had an additive effect on osteoblast activity and mineralization when compared with pristine Ti as well as alendronate or BMP-2 alone. Functionalized Ti systems with alendronate and BMP-2 can give a good solution to solve the most common problems associated with orthopedic and dental implants. Furthermore, in vivo studies required to determine the optimal doses of alendronate and BMP-2 for clinical application.

The PowerPoint (2007 Version; Microsoft, Redmond, Wash) method is reported to have improved repeatability and reproducibility and is better able to detect differences in radiographs than previously established manual wear measurement methods. In this study, the PowerPoint method and the Dorr and Wan method were used to calculate the polyethylene liner wear volume. The wear volumes of retrieved polyethylene liners calculated from the 3D laser scanning method were compared with each method. This study hypothesized that the wear volume calculated by the PowerPoint method would correlate well with the wear volume measured by 3D laser scanning method.

Between March 2004 and June 2009, 22 polyethylene liners from 20 patients were collected during revision Total hip arthroplasty(THA). Exclusion criteria included (1) missing an early primary postoperative radiograph or prerevision radiograph, (2) evidence of acetabular loosening or migration, (3) existence of significant mismatch between early primary postoperative radiograph and prerevision radiographs on vertical axis, and (4) liner wear-through. After applying these exclusion criteria, 17 retrieved polyethylene liners from 16 patients were included in this study. Wear volumes were calculated using the PowerPoint, the Dorr and Wan methods by 3 independent experienced observers who were unaware of the study design, and 3-dimensional (3D) laser scanning methods.

Spearman correlation coefficients for wear volume results indicated strong correlations between the PowerPoint and 3D laser scanning methods (range, 0.89–0.93). On the other hand, Spearman correlation analysis revealed only moderate correlations between the Dorr and Wan and 3D laser scanning methods (range, 0.67–0.77).

The PowerPoint method is an efficient tool for the sequential radiologic follow-up of patients after THA. The PowerPoint method can be used to monitor linear wear after THA and could serve as an alternative method when computerized methods are not available.

A retrospective analysis of 63 primary total hip arthroplasty cases was done using repeated computed tomography scans to evaluate the pelvic osteolytic lesions in early stage. The progression rate of osteolysis of hips with small osteolytic volume less than 766.97 mm(3) in initial CT was 85.82 mm(3)/year, and that of hips with osteolysis more than 766.97 mm(3) was 456.3 mm(3)/year (P < 0.001). Younger patients less than 52 years old with good Harris Hip Scores (more than 80) frequently showed much faster progression in volume of osteolytic lesions. The rate of osteolysis was accelerated when the amount of osteolysis reached a certain threshold volume in active young patients in a cascade manner even in early stage.

The aim of this study was to evaluate the risk factors for dislocation of the bearing after a mobile-bearing Oxford medial unicompartmental knee replacement (UKR) and to test the hypothesis that surgical factors, as measured from post-operative radiographs, are associated with its dislocation

From a total of 480 UKRs performed between 2001 and 2012, in 391 patients with a mean age of 66.5 years (45 to 82) (316 female, 75 male), we identified 17 UKRs where bearing dislocation occurred. The post-operative radiological measurements of the 17 UKRs and 51 matched controls were analysed using conditional logistic regression analysis. The post-operative radiological measurements included post-operative change in limb alignment, the position of the femoral and tibial components, the resection depth of the proximal tibia, and the femoral component-posterior condyle classification.

We concluded that a post-operative decrease in the posterior tibial slope relative to the pre-operative value was the only significant determinant of dislocation of the bearing after medial Oxford UKR (odds ratio 1.881; 95% confidence interval 1.272 to 2.779). A post-operative posterior tibial slope < 8.45° and a difference between the pre-operative and post-operative posterior tibial slope of > 2.19° may increase the risk of dislocation.

Cite this article: Bone Joint J 2014; 96-B:914–22.

Introduction

Periprosthetic osteolysis following total hip arthroplasty is caused mainly by polyethylene wear particles and necessitates revision surgery at some stage even in the presence of well-fixed implants. Therefore, methods to estimate the polyethylene wear become important, with manual wear measurement methods as the main outcome measurement even in the presence of computer-assisted measurement methods on account of easy availability and simplicity in their use with reasonable accuracy. The purposes of this study were to quantify the accuracy and reproducibility of the slide presentation software method on clinical radiographs and to compare it with that of the previously described Livermore's method, and to determine the usefulness of the slide presentation software methods for highly cross linked polyethylene wear measurement.

Each in vivo wear measurement method for total hip arthroplasty (THA) has strengths and weaknesses. The authors have developed a new manual wear measurement method (PowerPoint [PP] method) and validated that the PP method was found to have better repeatability, reproducibility and pick up differences in the radiographs than the previously established manual wear measurement methods. The primary aim of this study was to evaluate the reliability of the PP method by retrieval study. 17 retrieved polyethylene (PE) liners (16 patients) were enrolled in this study. The wear volumes of retrieved PE liners from clinical radiographs were calculated by the PP and Dorr and Wan method and they were compared with the wear volume of retrieved PE liners calculated by the triangulation three-dimensional (3D) laser scan. Spearman correlation coefficients results between PP method and 3D laser scan revealed excellent correlations (0.89 to 0.93). The Intraclass Correlation Coefficients values of the PP method showed excellent correlations (0.95 to 1.00). We suggest that the PP method will be a viable new technique for measuring wear of THA and a supplement method when computerized methods are not available.

CLS Spotorno expansion acetabular cup is in use since 1984 for uncemented Metal-Polyethylene (PE) total hip arthroplasties (THA). Metal-PE articulations are notoriously known to wear and lead to failure of THA. However, catastrophic breakage of expansion acetabular cup is rare. Our 74-year-old male who was diagnosed with bilateral osteonecrosis of femoral head, underwent bilateral THA using CLS Spotorno metal expansion acetabular cups (Protek, AG, Bern) in 1991. He had irregular follow-up since then. In 2005, he presented with right hip pain and inability to walk without support. Anteroposterior (AP) hip radiographs established the diagnosis of catastrophic failure of right THA secondary to severe liner wear and acetabular osteolysis. Patient chose to postpone the revision surgery and opted for wheel chair ambulation. He presented 4 years later, when the right hip pain became unbearable. Anteroposterior as well as lateral hip radiographs showed worsening of cup breakage with superolateral migration of metal femoral head. Pelvic CT scans confirmed severe acetabular osteolysis in DeLee and Charnley's Zone 1, 2 & 3 with secondary loss of bony support to the expansion cup [Fig. 1]. A revision THA was strongly advised. However, patient sought for a pain-free rather than a fully ambulatory right hip and decided against a second THA. We performed resection arthroplasty of right hip with bone cement loading, respecting patient's decision. Intra-operatively, the metal femoral head was lying in the huge osteolytic defect in the roof of acetabulum. The 3 cranial wings of metal expansion shell were broken with corresponding wear of the cranial pole of polyethylene liner [Fig. 2]. We were able to gratify patient's expectations and patient is able to ambulate with the aid of one crutch at latest follow-up. However, it is clearly evident that a timely and regular follow-up would have identified the initial PE wear and secondary osteolysis. Additionally, it can avoid extensive procedures like a revision THA or resection arthroplasty by allowing simple procedures like modular PE liner and the femoral head exchange. A comprehensive review of literature for catastrophic acetabular component breakage revealed 10 such cases, although with different cup designs. To the best of our knowledge, this is the first case of CLS expansion cup breakage for metal-PE articulation. Majority of these cases have a presence of extensive liner wear and pelvic osteolysis along with a post-operative irregular follow up. This case stresses on importance of regular follow-up even after many years of index THA to identify early PE wear and prevent secondary catastrophic complications.

Purpose

In an effort to increase the durability of cemented total hip arthroplasties (THA), femoral stems were precoated using polymethlymethacrylate (PMMA). One such design is Harris precoat plus and centralign design (Zimmer, Warsaw, Indiana). The reports on these particular designs are variable, ranging from good survival to early failures, studied over short to medium term. Early failures have been attributed, most of the time to debonding at cement-bone interface. In view of lack of long term and variable results, we reviewed the results of primary hybrid THA performed during October 1990 to December 1995, using a PMMA coated, cemented femoral prosthesis and contemporary cementing techniques.