陶对陶与陶对聚乙烯假体在全髋关节置换术中的中期随访分析

目的：比较陶对陶（ceramic-on-ceramic,COC）与陶对聚乙烯假体（ceramic-on-polyeth-ylene,COP）在全髋关节置换术中应用的可靠性和耐用性。方法对77例接受初次全髋关节置换的患者进行回顾性研究,比较 COC 与 COP 两种不同假体术后髋关节功能及并发症。结果COC组与 COP 组术后髋关节 Harris 评分分别为92．6±5．1和91．3±4．2,差异无统计学意义（P ＞0．05）;两者在翻修、脱位、陶瓷破碎、异响、松动、骨溶解、深部感染、异化骨化发生率的比较,差异无统计学意义（P ＞0．05）。结论COC 与 COP 假体均能获得较好的临床疗效,两者术后在髋关节功能及并发症方面疗效相当。     

A Study for a retrieved implant of ceramic-on-ceramic total hip arthroplasty

A Mittelmeier-type ceramic on ceramic total hip arthroplasty (THA) was retrieved because of aseptic loosening 17 years after implantation. The extent of wear was assessed by scanning electron microscopy. The synovial fluid and the tissue surrounding the implant were also examined. Scanning electron microscopy analysis of the ball head showed that the main wear zone had grade IV wear. The stripe wear zones showed grain pullout regions (grade 5 wear). Pathologically, chronic inflammation was observed in the surrounding tissue. The debris particles in the synovial fluid were polygonal and approximately 3 x 4 microm. Thus, the Mittelmeier-type THA proved excellent wear resistance. Further longevity of ceramic on ceramic THA may indeed become a reality with improvement of the design and quality of alumina.     

Instability and wear of total hip prostheses determined with roentgen stereophotogrammetry

A roentgen stereophotogrammetric analysis of hip prostheses was made in four patients with rheumatoid arthritis during a postoperative period of 2 years. Implanted tantalum balls, prosthetic femoral head, and ends of the wire in the acetabular socket were used as measurement points. The migration of the prosthetic head and the acetabular socket in relation to the pelvic bone was determined. The difference between the cranial migration of the head and the socket is a measure of the postoperative instability of the hip joint and deformation of the prosthetic components. This deformation occurs in the plastic acetabular socket and is mainly due to wear. The roentgen stereophotogrammetric method can be applied to standard hip orostheses with a metal femoral head and a plastic or metal acetabular socket to study migration or loosening of the prosthesis in relation to the supporting bone, prosthesis instability, and deformation of the prosthetic components.     

Instability and wear of total hip prostheses determined with roentgen stereophotogrammetry

Summary A roentgen stereophotogrammetric analysis of hip prostheses was made in four patients with rheumatoid arthritis during a postoperative period of 2 years.Implanted tantalum balls, prosthetic femoral head, and ends of the wire in the acetabular socket were used as measurement points.The migration of the prosthetic head and the acetabular socket in relation to the pelvic bone was determined. The difference between the cranial migration of the head and the socket is a measure of the postoperative instability of the hip joint and deformation of the prosthetic components. This deformation occurs in the plastic acetabular socket and is mainly due to wear.The roentgen stereophotogrammetric method can be applied to standard hip prostheses with a metal femoral head and a plastic or a metal acetabular socket to study migration or loosening of the prosthesis in relation to the supporting bone, prosthesis instability, and deformation of the prosthetic components.     

The long-term wear of retrieved McKee-Farrar metal-on-metal total hip prostheses

Twenty-four cobalt-chrome alloy McKee-Farrar matching acetabular and femoral components were retrieved at revision total hip arthroplasty. The average time in situ was 16 years. Wear and loss of sphericity was very low. Polishing wear (type 1), fine abrasive (type 2), multidirectional dull abrasive (type 3), and unidirectional dull abrasive wear (type 4) of the articulating surfaces were identified. The mean percent area of femoral heads occupied by types 2, 3, and 4 wear was 18%, 5%, and 2%, respectively. There was no association between the type and distribution of wear and the time in situ. Impingement damage was evident on 9 implant pairs. The extent and types of wear described in this paper will be useful when analyzing the patterns of surface damage of newer designs of metal-on-metal articulations.     

The role of patient factors and implant position in squeaking of ceramic-on-ceramic total hip replacements

We investigated factors that were thought to be associated with an increased incidence of squeaking of ceramic-on-ceramic total hip replacements. Between June 1997 and December 2008 the three senior authors implanted 2406 primary total hip replacements with a ceramic-on-ceramic bearing surface. The mean follow-up was 10.6 years. The diagnosis was primary osteoarthritis in each case, and no patient had undergone previous surgery to the hip. We identified 74 squeaking hips (73 patients) giving an incidence of 3.1% at a mean follow-up of 9.5 years (4.1 to 13.3). Taller, heavier and younger patients were significantly more likely to have hips that squeaked. Squeaking hips had a significantly higher range of post-operative internal (p = 0.001) and external rotation (p = 0.003) compared with silent hips. Patients with squeaking hips had significantly higher activity levels (p = 0.009). A squeaking hip was not associated with a significant difference in patient satisfaction (p = 0.24) or Harris hip score (p = 0.34). Four implant position factors enabled good prediction of squeaking. These were high acetabular component inclination, high femoral offset, lateralisation of the hip centre and either high or low acetabular component anteversion. This is the largest study to date to examine patient factors and implant position factors that predispose to squeaking of a ceramic-on-ceramic hip. The results suggest that factors which increase the mechanical forces across the hip joint and factors which increase the risk of neck-to-rim impingement, and therefore edge-loading, are those that predispose to squeaking.     

Arthrosynovial cyst of the hip after total hip arthroplasty with a ceramic-on-ceramic interface

An inguinal arthrosynovial cyst of the hip joint developed after total hip arthroplasty leading to compression of the femoral vein. This complication occurred after implantation of a non-cemented prosthesis with a ceramic-on-ceramic interface inserted in a polyethylene sandwich. Multiple foreign bodies composed of both ceramic and polyethylene particles were visualized microscopically. Later, rupture of the joint interface required implant replacement. This cyst was a precursor sign of a deteriorating prosthesis surface.     

不同股骨头颈直径比与髋臼角对人工髋关节活动的影响

目的：探讨不同股骨头颈直径比和髋臼安置方位对人工全髋关节活动范围的影响。方法：应用计算机模拟技术建立人工全髋关节三维计算机模型，模拟测试三种不同头颈直径比全髋假体在体外不同安置方位的活动范围。结果：全髋关节置换术后的活动范围不仅取决于假体设计的某些参数，如头颈直径比，还取决于假体安置的某些参数，如臼杯的外展角和前倾角，假体柄的前倾角，以及臼杯和柄的相互方向等等。人工全髋关节在合适的安置方位内产生最佳的活动范围。头颈比越大，同一安置方位同一方向的活动范围越大。结论：人工全髋关节相对较大的头颈直径比在合适的安置方位内产生最佳的活动范围，可减少全髋关节置换术(THA)后假体撞击机会。国产镁硅玉全髋假体由于头颈比太小，在任何安置方位内其活动范围都较小，将难于满足日常生活需要。     

Effect of distal stem geometry on interface motion in uncemented revision total hip prostheses.

In this study, we compared differences in motion at the bone-prosthesis interface in femora in which a fluted, tapered, or cylindrical distal stem design had been implanted in a revision total hip arthroplasty model. Paired, fresh-frozen, cadaveric femora underwent resection of the proximal femur to simulate the proximal femoral bone loss often present during revision total hip arthroplasty and implantation with either a fluted, tapered stem or a clinically proven cylindrical stem. Specimens were then preloaded and subjected to a synchronous axial and torsional load with continuous monitoring of axial displacement and rotation. For the fluted, tapered stem, mean axial and rotational displacements were 13.33 microm and 9.81 microm, respectively, compared with 18.37 microm and 13.40 microm for the cylindrical stem (both Ps < .05). Therefore, the fluted, tapered stem design that was tested demonstrated superior initial biomechanical stability compared with that of the clinically proven cylindrical design tested. However, both stems demonstrated motion below the threshold necessary for bony ingrowth. Knowledge of the initial biomechanical properties of different stem designs may assist the revision joint surgeon in choosing the optimal prosthesis for implantation.     

Rate of wear in total hip replacement.

The wear of high molecular weight polyethylene sockets was measured on radiographs, over a period of 9 to 10 years, in a group of patients whose ages averaged 73.3 years at the end of the period. The average rate of wear was 0.15 mm/year and 68 per cent of patients followed this pattern. Wear more than 2.5 mm in 10 years occurred in 15 per cent. There was a diminution in the rate of wear with the passage of time; in the second 5 years the rate of wear was approximately 40 per cent less than in the first 5 years. Body weight and physical activity did not appear to have any relationship to the final amount of wear. In a second series of very disabled subjects under 30 years of age (33 patients, 59 hips, followed only for an average of 38.4 months) the wear was rather more than in the previous series. Most remarkable was the performance of 4 patients, below the age of 50, who were considered completely normal for their age (category A); three of these wore less than the average for the main series.     

Intrapelvic migration of total hip prostheses. Operative treatment

We describe a safe operative approach for removal of a prosthesis that has migrated into the pelvis, and we recommend that a two-stage reconstruction be done when revising the total hip-replacement arthroplasty. The first stage consists of the removal of the femoral component and cement through a lateral transtrochanteric approach, followed by removal of the acetabular component through an abdominal-retroperitoneal approach to permit exposure of the major intrapelvic structures and to ascertain their relationship to the acetabular component and cement. After the acetabular component has been removed, bone grafts are applied to the pelvis. Postoperatively, the patient is placed in traction for a time and then is allowed to walk with non-weight-bearing. The second stage of reconstruction, consisting of hip replacement, is performed nine to twelve months after the first stage. A satisfactory result was obtained in the four patients for whom we followed this operative regimen. In one patient, the first-stage procedure yielded a satisfactory result and the second stage was not done.     

Effect of distal stem geometry on interface motion in uncemented revision total hip prostheses

In this study, we compared differences in motion at the bone-prosthesis interface in femora in which a fluted, tapered, or cylindrical distal stem design had been implanted in a revision total hip arthroplasty model. Paired, fresh-frozen, cadaveric femora underwent resection of the proximal femur to simulate the proximal femoral bone loss often present during revision total hip arthroplasty and implantation with either a fluted, tapered stem or a clinically proven cylindrical stem. Specimens were then preloaded and subjected to a synchronous axial and torsional load with continuous monitoring of axial displacement and rotation. For the fluted, tapered stem, mean axial and rotational displacements were 13.33 microm and 9.81 microm, respectively, compared with 18.37 microm and 13.40 microm for the cylindrical stem (both Ps < .05). Therefore, the fluted, tapered stem design that was tested demonstrated superior initial biomechanical stability compared with that of the clinically proven cylindrical design tested. However, both stems demonstrated motion below the threshold necessary for bony ingrowth. Knowledge of the initial biomechanical properties of different stem designs may assist the revision joint surgeon in choosing the optimal prosthesis for implantation.     

The influence of acetabular component position on wear in total hip arthroplasty

Our experience has implicated cup inclination as an important factor in wear, whereas others have suggested that the hip center of rotation (COR) must be closely reestablished to reduce wear. We conducted a retrospective study to determine the relative importance of these 2 factors. One hundred thirty-nine total hip arthroplasties were studied after a mean follow-up of 9.2 years (range, 6-3 years). Forty-nine of 139 operated hips had a contralateral normal hip, which allowed the most accurate measurement of the influence of change in the COR. Wear was related to the inclination of the cup but not to a change in the COR. Secondarily, wear was less with a ceramic-polyethylene polyarticular surface than with metal-polyethylene. The importance of this data is related to cup implantation techniques. The hip COR can be moved superiorly and/or medially to permit cup inclination below 45 degrees with correct cup coverage.     

Long-term effects of alumina components in total hip prostheses.

Six pairs of alumina components of Ceraver-Ostéal total hip prostheses, which were implanted from nine to 12 years, were studied. In the load-bearing areas, the wear takes the form of relief polishing. The depth of wear, after a running-in period, is less than 0.3 microns and then reaches an equilibrium. In four cases, there was no displacement of the sockets and wear tracks were formed on the femoral heads, the sockets being worn on their periphery, never on the apex. In the case of two persons weighing more than 90 kg, two wear tracks were observed on the heads, corresponding to walking and raising from a seated position. In the worst case, the depth of the wear track was 44 microns and the weight of alumina debris was estimated to be 18 mg.     

Factors associated with early loosening of cemented total hip prostheses

Patient data and radiograms from a series of 237 consecutive total hip replacements were evaluated by means of a computer programme in an attempt to study factors correlated with early loosening. We found that the loosening rate was significantly influenced by several factors. The CAD-prosthesis (Computer Assisted Design, Howmedica) was found to be superior to the Charnley-Müller-prosthesis. The viscosity of the cement seemed to be an important factor in that low viscosity was positively correlated to loosening whereas high viscosity showed a negative correlation. Several technical details in the performance of the operations as well as loosening correlated with the surgeon. Males who preoperatively had fairly unrestricted physical activity and high body weight were more prone to early loosening. No correlation was found with the diagnosis, previous hip surgery, age, osteoporosis or cortisone treatment preoperatively. We wish to underline the importance of a thorough technique and suggest that total hip replacement should be performed by specialized surgeons.     

The influence of material and design on total knee replacement wear

It is difficult for surgeons to make the decision on which design or material to use given the different options available. Marketing claims and direct-to-consumer advertising certainly complicate this further. One company may claim a higher percentage of wear reduction with their bearing surfaces compared with those of another manufacturer. If the percentage of wear reduction is lower, it is unclear as to whether this creates a more effective technology for reducing wear in the clinical situation. The relative contribution and relationship of design and materials to wear performance must be considered before making that important judgment. To examine the overall influence of implant design on wear reduction, a knee simulator study was undertaken. This simulator study compared the Oxinium Genesis II system with the Triathlon Conventional and Triathlon X3 knee systems under physiologic stair-climb loading and motion profiles. This allows a similar comparison of material effect within one design but also a global comparison across designs. Test results show the Triathlon Conventional and Triathlon X3 knee systems have superior wear resistance compared with that of the Genesis II Oxinium system under stair-climbing simulation. This finding indicates that implant design plays a more significant role in knee wear reduction than material. Although material technology may improve a given knee system's ability to wear, design geometry has a first-order effect and should be addressed before materials. This study represents an effort to differentiate design effect from two different approaches to material enhancement. The results of this study support the predominance of design in knee replacement wear performance. Ultimately, only clinical evidence such as published studies or outcomes reported in the available joint registries will establish whether any material or design can achieve a 30-year outcome.     

Alumina ceramic-on-ceramic hybrid total hip arthroplasty. A median of 15 years follow-up

European Journal of Orthopaedic Surgery & Traumatology - The optimum choice of bearing surfaces in total hip replacement (THR) in the younger and active patient remains controversial. The aim...