Total Hip Arthroplasty: Past, Present, and Future. What Has Been Achieved? / 대한고관절학회지

In the 1960s, Sir John Charnley introduced to clinical practice his concept of low-friction total hip arthroplasty (THA). Although early designs were plagued by poor performance and even failure, there have been steady advances in implant designs, biomaterials, surgical techniques and an understanding of the biomechanical restoration of the hip; these advances have contributed to improvements in implant survival and clinical outcomes of THA in the past three decades. With improved wear resistance and mechanical reliability, a potential to last for at least 25 to 30 years are now available for THA. In this review, we focus on the evolution of THA and review current controversies and future directions of this procedure based on a single surgeon's 29-year of experience at a single institution.

Cementless Total Hip Arthroplasty Using Ceramic Femoral Head on Cross-Linked Ultra-High-Molecular Weight Polyethylene Liner in Patients Older than 65 Years: Minimum Five-Year Follow-Up Results / 대한정형외과학회잡지

PURPOSE: To evaluate the utility of ceramic-on-polyethylene articular bearing surface when cementless total hip arthroplasty is performed in patients older than 65 years through an analysis of the minimum five-year follow-up results using the ceramic femoral head and cross-linked polyethylene liner. MATERIALS AND METHODS: From March 2010 to September 2012, 51 patients (56 hips) who were older than 65 years were enrolled in this retrospective study. The mean age at surgery was 70.9±5.1 years old. A clinical assessment was analyzed using the Harris hip score. For the radiographic assessment, the cup inclination and anteversion, stem alignment, and wear amount were measured. The postoperative complications were also determined. RESULTS: The mean Harris hip score was improved from preoperative 48 points to postoperative 87 points (p < 0.05). The mean cup inclination was 40.9°±6.4° and the mean cup anteversion was 20.3°±8.1°. The mean cup anteversion of the elevated liner-used group (16 cases) was 14.3°±7.9° and the mean cup anteversion of the neutral liner used group (40 cases) was 22.4°±9.1° (p < 0.05). The mean stem alignment angle was 0° (range, varus 4°–valgus 4°). The mean linear wear amount was 0.458±0.041 mm and the average annual linear wear rate was 0.079±0.032 mm/yr. Six cases (10.7%) of intraoperative periprosthetic femoral fractures were encountered. CONCLUSION: Based on these results, the use of a ceramic-on-polyethylene articular bearing surface in elderly patients with cementless total hip arthroplasty is beneficial. On the other hand, careful effort is needed to prevent intraoperative periprosthetic femoral fractures.

Future Bearing Surfaces in Total Hip Arthroplasty

One of the most important issues in the modern total hip arthroplasty (THA) is the bearing surface. Extensive research on bearing surfaces is being conducted to seek an ideal bearing surface for THA. The ideal bearing surface for THA should have superior wear characteristics and should be durable, bio-inert, cost-effective, and easy to implant. However, bearing surfaces that are currently being implemented do not completely fulfill these requirements, especially for young individuals for whom implant longevity is paramount. Even though various new bearing surfaces have been investigated, research is still ongoing, and only short-term results have been reported from clinical trials. Future bearing surfaces can be developed in the following ways: (1) change in design, (2) further improvement of polyethylene, (3) surface modification of the metal, (4) improvement in the ceramic, and (5) use of alternative, new materials. One way to reduce wear and impingement in THA is to make changes in its design by using a large femoral head, a monobloc metal shell with preassembled ceramic liner, dual mobility cups, a combination of different bearing surfaces, etc. Polyethylene has improved over time with the development of highly crosslinked polyethylene. Further improvements can be made by reinforcing it with vitamin E or multiwalled carbon nanotubes and by performing a surface modification with a biomembrane. Surface modifications with titanium nitride or titanium niobium nitride are implemented to try to improve the metal bearings. The advance to the fourth generation ceramics has shown relatively promising results, even in young patients. Nevertheless, further improvement is required to reduce fragility and squeaking. Alternative materials like diamond coatings on surfaces, carbon based composite materials, oxidized zirconium, silicon nitride, and sapphire are being sought. However, long-term studies are necessary to confirm the efficacy of these surfaces after enhancements have been made with regard to fixation technique and implant quality.

Total Hip Arthroplasty using a Ceramic on Ceramic Bearing Surfaces / 대한정형외과학회잡지

PURPOSE: To evaluate the clinical and radiological results of total hip arthroplasty using a ceramic on ceramic bearing surfaces. MATERIALS AND METHODS: From April 1999 to April 2005, 53 hips had total hip arthroplasty with a ceramic on ceramic bearing surfaces in our hospital. Causes of total hip arthroplasty were avascular necrosis of femoral head in 47 hips, osteoarthritis in 3 hips and ankylosing spondylitis in 3hips. We used three kinds of acetabular cup and two kinds of femoral stem in this study. Follow-up period was an average of 55months (24-92). Clinical results were evaluated with Harris hip score and squeak sound. Radiological results included liner wear rate, breakage of ceramic, component loosening and osteolysis. RESULTS: Mean Harris hip scores improved from 58 to 88.3. No breakage of ceramic liner or head occurred. No acetabular or femoral osteolysis was seen. Audible squeak sound or sensation was detected in 10 hips (18%). Revision was done in three cases (5.7%), the cause of one of them was acetabular cup loosening. CONCLUSION: Total hip arthroplasty with a ceramic on ceramic bearing surfaces showed satisfactory clinical and radiological results in an average of 4.6 years follow-up. However, we have to study causes and adverse effect of squeaking on the total hip arthroplasty.

Local compressive strength at the middle of the weight-bearing surface of the femoral head and talar dome: A biomechanical study.

Objective: To compare the local compressive strength at the middle of the weight bearing surface of the femoral head and talar dome. Design: Cadaveric and comparative experimental study. The compressive strength of the talar dome and the femoral head were measured and compared. Background: The prevalence of late collapse of femoral head from avascular osteonecrosis is higher than that of the talar dome. The femoral head and acetabulum form a hip joint with monoarticulation whereas the talus itself has several articulations with several bones, so the talar dome distributes load more effectively from it the surroundings than does the femoral head. Compressive strength of the weight bearing surface of the femoral head and talar dome, however, may play a role in late collapse. Methods: Ten fresh cadaveric normal adult femoral heads and tali were obtained. A compressive load was applied through an indenter at the middle of the superior quadrant of the femoral head and talar dome by using a universal testing machine until a maximum load was obtained. The maximum load and depth of depression at maximum load were recorded. Results: The middle of the weight bearing surface of the femoral head could withstand an average maximum pressure of 30.42 MPa. Its stillness was 929.04 N/mm and its depth of depression was 1.11 mm. The corresponding figures for the talar dome were 49.64 Mpa, 1631.65 N/mm, and 0.96 mm respectively. Conclusion : This study showed that local compressive strength at the middle of the weight bearing surface of the talar dome was 1.63 times greater than that of the femoral head. Relevance : This finding may explain the higher prevalence of late collapsing avascular necrosis of the femoral head than that of the talar dome.