Special problems of cementless fixation of total hip-joint endoprostheses with reference to the PM type

The success of cement-free hip endoprosthetics is largely dependent on precise surgical techniques and primary stability of the anchorage, in which favorable biomechanical conditions as well as the quality of the stabilizing bone are of considerable importance. Information gathered from more than 1500 cementless hip-joint endoprosthesis implantations is presented with biomechanical solutions and indications regarding operating techniques, and a correlation between clinical symptoms and radiological signs of complications is discussed. In close coordination with material-specific factors, design and surface characteristics are decisive in the function and quality of anchorage of the endoprosthetic replacement. In the case of the PM total hip endoprosthesis, these widely variable values were governed strictly by biomechanical considerations, with particular reference to the resulting bone reactions. Results so far, including those relating to stable integration of the implant, must be regarded as absolutely positive and confirm the design characteristics on which this model was based. Avoiding the disadvantages of bone cement, cementless hip-joint replacement, particularly in operations for the exchange of cemented prostheses after loosening, can be regarded as a step forward in hip-joint surgery.     

Shaft fissures due to implantation of cementless total endoprostheses of the hip joint

Summary Since 1982, at the Orthopedic Department of the Pulmologic Center of the City of Vienna we have used the Zweymüller shaft system and the pyramidal threaded socket by Schwdgerl when implanting cementless hip endoprostheses. Some patients repeatedly complained about pains in the shaft region within the first postoperative months, though these complaints could not be explained clinically or radiographically. On 15 human cadavers we implanted a total of 20 Zweymüller shafts and examined the femurs for ruptures of the shaft. Our special interest was the course of the fracture lines, their location, and their display on roentgenograms. It appeared that fissures of shaft are easily caused by the forced driving-in of the prosthesis. In about half of all cases the fissure cannot be seen on roentgenograms because of the site is covered by the implant itself. The fracture lines do not always begin intertrochanterally or from the calcar femoris; theorefore, they cannot be recognized during surgery. This problem should be considered during implantation as well as during postoperative remobilization.     

Shaft fissures due to implantation of cementless total endoprostheses of the hip joint. An experimental study

Since 1982, at the Orthopedic Department of the Pulmologic Center of the City of Vienna we have used the Zweymüller shaft system and the pyramidal threaded socket by Schw?gerl when implanting cementless hip endoprostheses. Some patients repeatedly complained about pains in the shaft region within the first postoperative months, though these complaints could not be explained clinically or radiographically. On 15 human cadavers we implanted a total of 20 Zweymüller shafts and examined the femurs for ruptures of the shaft. Our special interest was the course of the fracture lines, their localization, and their display on roentgenograms. It appeared that fissures of the shaft are easily caused by the forced driving-in of the prosthesis. In about half of all cases the fissure cannot be seen on roentgenograms because of the site is covered by the implant itself. The fracture lines do not always begin intertrochanterally or from the calcar femoris; therefore, they cannot be recognized during surgery. This problem should be considered during implantation as well as during postoperative remobilization.     

Initial experiences with the cementless PM endoprosthesis

A follow up of 40 cementless fixed endoprostheses type PM showed good results, similar to cement fixed prostheses. In cementless fixation seem to be more early complications and less late complications, so these results are encouraging what concerns cementless fixation.     

A comparison of cemented and cementless fixation with the Miller-Galante total knee arthroplasty

This study demonstrates the comparability of cemented and cementless fixation in total knee arthroplasty at short-term follow-up. While some differences in pain, limp, and support were noted, knee scores were equivalent. Roentgenographic analysis as well as implant retrieval studies demonstrate that porous ingrowth is a viable method of fixation of total knee components. Further long-term follow-up studies will be required to determine both the long-term clinical results and the longevity of the fixation interface.     

非骨水泥假体在全膝关节置换术中的应用进展

全膝关节置换术(TKA)是治疗膝关节终末期骨关节炎及风湿性关节炎的有效手段,传统的骨水泥假体在TKA中应用一直占据主流地位。针对年轻患者(≤60岁)和有运动需求的患者而设计的非骨水泥假体在早期由于设计和技术上的限制,未能获得较好的预后,因此没有得到广泛推崇。随着设计理念及材料技术的提升,新型非骨水泥假体优势突显,逐渐受到关节科医生的青睐。本文就非骨水泥假体的设计初衷、发展历程、新技术特点、临床预后以及目前研究的不足等角度出发,对非骨水泥假体在TKA中的应用进行全面的综合评述。     

Fixation of the NexGen HA-TCP-coated cementless,screwless total knee arthroplasty: comparison with conventional cementless total knee arthroplasty of the same type

We performed a 12-month prospective study on 59 patients (92 knees) who underwent NexGen (Zimmer Inc, Warsaw, IN) cruciate-retaining total knee arthroplasty. In the control group, uncoated components were fixed using screws, whereas the hydroxyapatite-tricalcium phosphate (HA-TCP) group underwent screwless fixation of coated components. At 12 months postoperatively, there was a radiographic clear zone around the femoral and tibial components of 56.5% and 32.6% of the knees in the control group. The HA-TCP group showed a clear zone at the medial aspect of the tibial component in only 1 knee. These results suggested that HA-TCP-coated articular components show good initial fixation without using screws. The NexGen coated knee arthroplasty may be useful for solving the problems of cementless fixation.     

Survivorship of cementless total knee arthroplasty without tibial plateau screw fixation

Seventy-two cementless tricompartmental total knee arthroplasties were performed in 47 patients using a porous-coated prosthesis without screw fixation for the tibial components between 1984 and 1986. These individuals were observed at regular intervals for a minimum of three years. Their Hospital for Special Surgery pain and function scores as well as roentgenographic signs of anatomic alignment and subsidence were evaluated at six months, one year, and three years postoperatively. The roentgenographic evaluation for subsidence looked at a measurable difference in the anteroposterior roentgenograph on the medial and lateral plateaus and on the lateral roentgenograph anteriorly and posteriorly. Early postoperative interpretations have suggested pain and knee scores to be much lower than scores in the cemented prosthesis. Reassessment after three years, however, revealed no further deterioration of the noncemented prosthesis in respect to knee scores and survival analysis. Roentgenographic analysis showed no correlation between subsidence and alignment alterations, subsidence and time, or subsidence and pain. It appears that after an initial period of discomfort, the noncemented knee can achieve a functional, clinical, and roentgenographic result much better than previously anticipated. The consequences beyond this time period still remain unknown.     

Treatment of periprosthetic femoral fracture after cementless total hip arthroplasty with Ilizarov external fixation

A 72-year-old woman with periprosthetic femoral fracture after cementless total hip arthroplasty (THA) underwent external fixation using the Ilizarov method. Although open reduction and internal fixation with a condylar plate system were initially attempted, deep infection with methicillin-resistant Staphylococcus aureus at the fracture site occurred 2 weeks postoperatively. Six weeks after removal of the plating system, the fracture was stabilized with external fixation using the Ilizarov method and went on to successful fusion at 3 months. To our knowledge, this is the first report in which Ilizarov external fixation has been used for periprosthetic femoral fracture after THA. Although this is a rare situation, where periprosthetic fracture and infection coexist, Ilizarov external fixation is a safe and reliable method for periprosthetic femoral fracture with infection.     

Failure of cementless fixation of the femoral component in total hip arthroplasty.

The basic concepts involved in cementless fixation of the total hip arthroplasty femoral component have been controversial. Some clinicians advocate fixation only of the proximal portion of the stem so that weight-bearing loads will be transferred proximally, and proximal stress shielding will be avoided. Others advocate distal fixation to ensure rigidity of fixation but concede that it will lead to proximal stress shielding and bone loss. However, clinical evidence suggests that the design of the implant is one important factor in determining stress shielding. When the stem is smooth and cylindrical distally, proximal stress relief does not occur, even when the stem is fixed tightly distally. Because femoral component loosening is the most common clinical problem with cementless total hip arthroplasty, every effort should be made to achieve fixation of the implant. Proximal and distal fixation can be achieved with most of the available implants. For tight proximal fixation, a good proximal implant design and a precise line-to-line preparation technique are critical, but aggressive broaching and interference-fit techniques result in a high rate of proximal femoral fracture during preparation and implantation. When the conditions are good for excellent proximal fixation, a flexible stem should be selected to apply a large amount of stress proximally. The stress transferred through distal fixation will be small in this situation, and the reaming technique of the femoral diaphysis does not need to be very aggressive. Approximately 10 to 20 mm of tight distal fit combined with the 0.5-mm underreaming technique provides sufficient distal fixation, and the chance of distal femoral fracture during insertion of the stem is minimum with this technique. When conditions are unfavorable for excellent proximal fixation, such as in revision hip arthroplasty, or when a proximal deformity or osteoporosis is present, a relatively rigid stem should be selected to avoid overloading proximal fixation and, thus, generating large proximal micromotion. The stress transferred through distal fixation will be large in this situation, and a relatively aggressive but well-controlled reaming technique of the diaphysis is required. Approximately 20 to 40 mm of tight distal fit combined with a 0.5-mm underreaming technique is adequate to obtain sufficient distal fixation and still avoid distal femoral fracture. Implant design features that improve proximal fixation and instrumentation features that improve bone preparation and decrease the risk of failure will broaden the indications for cementless fixation. As fixation and instrumentation improve, more flexible implants can be developed to improve bone preservation and avoid proximal stress relief.(ABSTRACT TRUNCATED AT 400 WORDS)     

Stability of initial fixation of the tibial component in cementless total knee arthroplasty

This study measured the vertical displacement of three kinds of cementless tibial components [Porous Coated Anatomical (PCA), Tricon, and Whiteside], under eccentric loading up to 2,225 N. Displacement between the tibial tray and the proximal tibia was measured with linear variable differential transformers at the anterior and posterior side when anteriorly or posteriorly loaded, and at the medial and lateral side when medially or laterally loaded. The general pattern of motion was sinking at the loaded side and lift-off at the opposite side. Lift-off opposite the loaded side was fairly small for all components at all measurement sites. Among the three components, the Whiteside showed the smallest displacements. The Tricon (when anteriorly or posteriorly loaded), and the PCA (when medially or laterally loaded) showed sinking at the loaded side. Anterior screw fixation of the PCA was not effective in preventing anterior lift-off. The tilting motion of the tibial components observed in this study implies instability of the initial fixation, which could possibly compromise bony ingrowth. Furthermore, this tilting could cause uneven distribution of load, and potentially result in fracture of the underlying bone.     

Radiographic and clinical analysis of cementless acetabular fixation in total hip arthroplasty

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Long-term followup of cementless versus hybrid fixation for total knee arthroplasty.

In a prospective trial, 99 patients (100 knees) with osteoarthritis were randomized to either cementless or hybrid fixation of cruciate-retaining Miller-Galante-I total knee arthroplasties between January 1987 and December 1988. Thirty-one patients died during the study period and two additional patients were lost to followup, leaving 67 total knee arthroplasties for analysis. Thirty-nine patients underwent revision surgery at an average of 6.9 years postoperatively. The main reason for revision surgery was failure of metal-backed patellas with 25 knees revised at an average of 7.4 years, and the second most common reason was tibial polyethylene failure. Survival curves showed 60% survival at 14 years for all knees, and 85% survival at 14 years when failures for metal-backed patellas and infection were excluded, with no significant difference between the two groups. Failure of metal-backed patellas was significantly higher in the cementless group. Tibial polyethylene failure occurred in five of the hybrid group and none of the cementless group, but this was not a significant difference. Surviving prostheses were assessed at an average of 12.8 years (range, 11.5-13.5 years). Average clinical scores were 94.8 points preoperatively, and 143 points at the latest followup, with significantly higher scores in the hybrid group. Differences in outcome between the two groups were not sufficiently significant to recommend one method of fixation over another. With elimination of poor design features related to the patellofemoral articulation and thin tibial polyethylene, cruciate-retaining total knee arthroplasties can yield good durable results, whether cementless or hybrid fixation is used.     

The optimal fixation of the cementless acetabular component in primary total hip arthroplasty.

The optimal fixation of the acetabular component in primary total hip arthroplasty remains controversial. Long-term follow-up studies show that significant loosening rates occur with cemented acetabular components and that these problems persist despite attempts to improve cementing technique. Cementless acetabular components that rely on biologic fixation can have lower rates of radiographic loosening at 10 years compared with cemented acetabular components. Although revision rates for both modes of fixation are largely equivalent at 10 years, the superior radiographic performance of cementless acetabular components at 10 years suggests that biologic fixation through bone ingrowth may provide more durable long-term implant survival compared with cemented fixation. Osteolysis is the major obstacle to long-term cementless acetabular component survival. Potential future options that may inhibit osteolysis include decreasing bone resorption that results from debris-stimulated foreign body response through the use of medications; decreasing the number of particles generated by using alternative bearing surfaces; and improving bone ingrowth, particularly through the use of growth factors and improved implant materials and designs.     

Follow up study of 997 total hip endoprostheses with special reference to late results 9-11 years after operation

81.1% of a total of 1230 total hip arthroplasties could be reviewed by means of questionaries between 4 and 11 years after the operation. There was clear evidence for wors results in the long term group (between 9 and 11 years postoperatively) as to pain and ability to walk. In the short-term group of 1972-76 8.4% are not satisfied with the results of the operation, but in the long term group of 1970 this refers, as to be expected, to 23.5%. The same trend has been stated what aseptic complications are concerned: 42.7% clinically relevant ectopic ossifications and non-infectious implant loosenings in the long term group as compared with only 5.6% in the short term group. 1131 Müller prostheses were implanted. In this group 61 reoperations because of aseptic complications were necessary. Of all implanted Müller prostheses models the one with the middle neck length revealed the lowest rate of loosenings. Postoperative infections (both early and late) indicated a re-operation in 0.5%.     

Fractures of the proximal femur in patients with total hip endoprostheses

Between October 1982 and October 1983 three patients were admitted to the Orthopedic Clinic of the University of Vienna who had suffered complicated fractures of the proximal femur, with concomitant loosening of previously implanted total hip endoprostheses. To replace them we used the KMFTR Endoprosthesis. The Kotz Modular Femur and Tibia Reconstruction Endoprosthesis was originally developed for the surgical management of bone tumors. The implantation followed the principle of intramedullary splinting and transfer of force. Fragments of bone adhering to the surrounding muscles were positioned around the endoprosthesis and the periosteum was carefully reconstructed. After a follow-up period of 1 year on the average the patients were very content with the results and were essentially not restricted in their scope of activities. Walking capacity and mobility were satisfying at last checkup. Radiographically, a consolidation of the femur with solid bony incorporation and a firm fit of the prosthesis were observed.