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.     

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.     

全髋股骨头假体无骨水泥翻修术的中期疗效

目的 报道采用长柄全干式或半干式多孔表涂股骨头假体加自体植骨行无骨水泥翻修术(RTHA)20例20髋的中期疗效。方法 均为首次RTHA的20例中诊断股骨头假体骨水泥固定后松动11髋，无骨水泥固定后松动9髋，其中3例伴假体干端骨折。骨缺损(Mulliken 分类)：Ⅱ期8例，Ⅲ期12例。手术采用国产仿AML长柄半干式表涂和进口长柄全干式表涂股骨头假体各10例，后者包括Bi-Metric(Biomet．uSA)3例、AML(Depuy，uSA)4例，REF(Lima，Italy)3例，并取自体髂骨剪成火柴梗状植入假体周围间隙。结果 平均随访7年，功能优13例(65％)，良6例(30％)，尚可l例(5％)。X线表现：所有病例股骨近段骨缺损植骨区修复良好，表现为骨皮质增厚，致密。假体呈骨性固定16例，纤维性稳定4例，无1例松动，至今无1例再翻修。术后第1年内，骨性固定组假体下沉均＜3mm，纤维性稳定组假体下沉均＞3mm，下沉最多达6mm．以后未继续下沉。远段假体髓内充填率在骨性固定组均＞90％，而纤维性稳定组均＜80％。结论 采用植骨修复结构性骨缺损，并选用长柄多孔表涂全髋股骨头假体施行翻修术，是获得显著疗效的关键。     

The relative cost of cemented and uncemented total hip arthroplasties

The use of uncemented femoral stems in primary total hip arthroplasty (THA) has been slow to develop in the UK because of the lack of encouraging published long-term follow-up data, the continued success of the cemented primary THA, and the perceived excessive relative cost of the uncemented THA. In this article, we argue that the total costs of 3 "proven" uncemented stems are comparable with commonly used cemented femoral components, when all necessary materials are taken into consideration. In addition, we will also discuss other potential benefits and drawbacks for considering the use of uncemented stems.     

Eradication of infection,survival, and radiological results of uncemented revision stems in infected total hip arthroplasties

Background and purpose — The use of uncemented revision stems is an established option in 2-stage procedures in patients with periprosthetic joint infection (PJI) after total hip arthroplasty (THA). However, in 1-stage procedures, they are still rarely used. There are still no detailed data on radiological outcome after uncemented 1-stage revisions. We assessed (1) the clinical outcome, including reoperation due to persistent infection and any other reoperation, and (2) the radiological outcome after 1- and 2-stage revision, using an uncemented stem.

Patients and methods — Between January 1993 and December 2012, an uncemented revision stem was used in 81 THAs revised for PJI. Patients were treated with 1- or 2-stage procedures according to a well-defined algorithm (1-stage: n = 28; 2-stage: n = 53). All hips had a clinical and radiological follow-up. Outcome parameters were eradication of infection, re-revision of the stem, and radiological changes. Survival was calculated using Kaplan-Meier analysis. Radiographs were analyzed for bone restoration and signs of loosening. The mean clinical follow-up time was 7 (2–15) years.

Results — The 7-year infection-free survival was 96% (95% CI: 92–100), 100% for 1-stage revision and 94% for 2-stage revision (95% CI: 87–100) (p = 0.2). The 7-year survival for aseptic loosening of the stem was 97% (95% CI: 93–100), 97% for 1-stage revision (95% CI: 90–100) and 97% for 2-stage revision (95% CI: 92–100) (p = 0.3). No further infection or aseptic loosening occurred later than 7 years postoperatively. The radiographic results were similar for 1- and 2-stage procedures.

Interpretation — Surgical management of PJI with stratification to 1- or 2-stage exchange according to a well-defined algorithm combined with antibiotic treatment allows the safe use of uncemented revision stems. Eradication of infection can be achieved in most cases, and medium- and long-term results appear to be comparable to those for revisions for aseptic loosening.     

Revision of failed total hip arthroplasties with uncemented porous-coated anatomic components

This series represents a relatively short follow-up study of patients who were treated with cementless revisions for failed previous arthroplasties. Many of these cases required extensive bone grafting to the acetabulum and often to the femur. Despite extensive bone grafting, there were no infections. There has been but a single graft resorption after a hemiarthroplasty conversion for recurrent dislocations. To date, all other grafts have remained intact and have shown signs of union. Even though the acetabular components were not anchored in place by adjuvant fixation devices such as screws, migration of the acetabular component has not been a problem. All other components have remained stable, and the supporting grafts appear to have united successfully. Femoral revision has been more technically demanding because the largest stem possible should be placed within the femur to prevent subsidence and provide good stabilization in the proximal metaphyseal area. These short-term results compared favorably with similar series of cemented revisions. Patient selection is important and there are definite candidates for cemented femoral components, particularly with first-time revisions in elderly patients. If there is massive osteolysis in the femur, cemented revision is probably not indicated. Long stems should not be used unless necessary. Cortical defects at the tip of the standard stem obviously would require bypassing the stress riser with a longer stem. If, however, the cortex is intact in this region and stability can be achieved, revision should be carried out with a relatively short stem. Techniques for cementless revision are demanding, but with meticulous attention to detail and technical perfection, the method has a most encouraging prognosis. Longer follow-up evaluations will be necessary to make an accurate evaluation of graft incorporation, but short-term results are encouraging to both surgeons and patients.     

Results of revision total knee arthroplasties using condylar prostheses. A review of fifty knees

Revisions of total knee arthroplasties for aseptic failure have provided varied results. In this review of fifty revisions in which a condylar prosthesis was used in carefully selected knees, the results were rated good or excellent in 76 per cent after an average length of follow-up of 4.8 years. At the follow-up examination, radiolucent lines were seen in 17 per cent of the knees. The complications included loosening of one or both prosthetic components in three knees (of which two were revised again); a hematoma in one knee; and a piece of loose cement, which had to be removed, in one knee. There were no deep infections. On the basis of these results, we concluded that revision total knee arthroplasty using a condylar prosthesis will have infrequent complications and will provide a satisfactory result in properly selected patients.     

Extra-large uncemented hemispherical acetabular components for revision total hip arthroplasty

BACKGROUND: Extra-large uncemented components provide several advantages for acetabular revision, but limited information is available on the results of their use. The purpose of this study was to evaluate, at a minimum of five years, the results associated with the use of an extra-large uncemented porous-coated component for acetabular revision in the presence of bone loss. METHODS: Eighty-nine extra-large uncemented hemispherical acetabular components were used for revision after aseptic failure of a total hip arthroplasty in forty-six men and forty-three women (mean age at revision, fifty-nine years; range, thirty to eighty-three years). The revision implant (a Harris-Galante-I or II cup fixed with screws) had an outside diameter of > or = 66 mm in men and > or = 62 mm in women. Seventy-nine patients had a segmental or combined segmental and cavitary acetabular bone deficiency before the revision. Particulate bone graft was used in fifty-four hips and bulk bone graft, in nine. RESULTS: One patient died with the acetabular component intact and two patients were lost to follow-up within five years after the operation. At the time of the last follow--up, four acetabular components had been removed or revised again (two for aseptic loosening). All of the remaining patients were followed clinically for at least five years (mean, 7.2 years; range, 5.0 to 11.3 years). In the hips that were not revised again, only two sockets had definite radiographic evidence of loosening. All four of the sockets that loosened were in hips that had had combined cavitary and segmental bone loss preoperatively. In the hips that were not revised again, the mean modified Harris hip score increased from 56 points preoperatively to 83 points at the time of the most recent follow-up. The most frequent complication, dislocation of the hip, occurred in eleven patients. The probability of survival of the acetabular component at eight years was 93% (95% confidence interval, 85% to 100%) with removal for any reason as the end point, 98% (95% confidence interval, 92% to 100%) with revision for aseptic loosening as the end point, and 95% (95% confidence interval, 88% to 100%) with radiographic evidence of loosening or revision for aseptic loosening as the end point. CONCLUSIONS: This study demonstrates that extra-large uncemented components used for acetabular revision in the presence of bone loss perform very well and have a low rate of aseptic loosening at the time of intermediate-term follow-up.     

Promising mid-term results of total hip arthroplasties using an uncemented lateral-flare hip prosthesis: a clinical and radiographic study

The clinical results after total hip replacements using noncemented stems have shown considerable variability over the years; the design and characteristics of the implant seemed to play a role in explaining this fact. The purpose of this paper is to report the clinical, radiographic and densitometry results of total hip arthroplasties using a stem designed for noncemented implantation and to engage and load the femur proximally. Fifty-eight consecutive patients (62 hips) followed for an average of 4.3 years (range 36-70 months) were clinically and radiographically followed up at three weeks, three months, six months, one year, and yearly thereafter. The average pre-operative Harris hip score was 49 increasing to 98 at the latest follow-up. There were no cases of aseptic or septic loosening. The average subsidence at three years was 0.45 mm (SD +/- 0.36 mm). Radiographically all hips were classified as stable, and evident changes compatible with new bone apposition were observed in 64% of the cases. The extended proximal geometry of the device seems to favour initial and secondary stability as reflected by the low subsidence values over time. The maintenance of periprosthetic bone stock and the absence of stress shielding can be explained by the predominantly proximal loading pattern of the stem.     

Cemented revision of failed uncemented femoral components of total hip arthroplasty

BACKGROUND: The long-term results of revision of failed primary cemented femoral components with use of cement have been reported, but there is little information about the results of revision of failed uncemented femoral components with use of cement. The purpose of the present study was to examine the minimum five-year results for patients in whom a failed uncemented primary femoral component was revised with use of modern cementing techniques. METHODS: Forty-eight consecutive hips (forty-seven patients) in which a failed primary uncemented femoral component was revised with use of cement at one institution from 1985 to 1992 were followed prospectively and reviewed retrospectively. The mean age of the patients at the time of revision was sixty-seven years. Only seven revisions were performed with a long-stem femoral component. The postoperative cement mantle was classified, according to the system of Mulroy and Harris, as grade A in four hips, grade B in twenty-five, grade C1 in seven, grade C2 in twelve, and grade D in none. RESULTS: Eleven femoral components were removed or revised because of aseptic loosening (ten) or deep infection (one). An additional four unrevised femoral components had evidence of probable or definite loosening at the time of the final radiographic follow-up. Thus, fourteen (29%) of the forty-eight femoral implants demonstrated aseptic loosening during the study period. Five of the twenty-nine hips in which the postoperative cement mantle was classified as grade A or B had mechanical failure at the time of the final follow-up, compared with nine of the nineteen hips in which the postoperative cement mantle was classified as grade C1 or C2 (p < 0.05). Among the hips with surviving prostheses, 79% had had moderate or severe pain preoperatively whereas 25% had moderate or severe pain at the time of the final follow-up. The six-year rate of survival of the femoral component was 72% with revision for aseptic loosening as the end point and 67% with mechanical failure (revision for aseptic loosening or radiographic loosening) as the end point. CONCLUSIONS: While revision of a failed uncemented femoral implant with use of cement provided pain relief and improved function for most patients, the rate of loosening at the time of intermediate-term follow-up was higher than that commonly reported after revision of failed cemented implants with use of cement and also was higher than that commonly reported after revision with use of uncemented extensively porous-coated implants. Bone removal at the time of the initial implantation of the stem and bone loss due to subsequent failure of the uncemented implant often left little intramedullary cancellous bone, which may explain the high rate of loosening observed in the first decade after revision in this series.     

髋关节翻修术若干问题探讨

髋关节置换术(total hip arthroplasty, THA)是20世纪最成功的手术之一,它能够减轻关节疼痛,改善功能和纠正畸形,从而提高患者生活质量.随着接受髋关节置换人数的增加,THA术后失败需要翻修的患者数量也在不断增加.相对于西方国家,我国THA开展相对较晚,目前一些文献报道5年随访效果满意,假体生存率达到100%[1-2],但尚需大宗病例中、长期随访来反映国内情况.髋关节翻修是关节外科医生面临的挑战之一,面临的困难主要有假体取出、骨缺损重建、假体与固定方法选择等,每一步都与手术成功与否密切关系,需要认真考虑.下面分别就髋关节翻修的相关问题进行简要阐述.     

284 press-fit Kinemax total knee arthroplasties followed for 10 years: poor survival of uncemented prostheses

BACKGROUND AND PURPOSE: Our institution began using the Kinemax total knee arthroplasty system in 1988, both with and without cement fixation. We report 10-year survival figures. METHODS: Theater records showed that 284 Kinemax total knee arthroplasties had been performed 1988 through 1993. Life-table survival estimates were used to determine the probability of survivorship 10 years after surgery for the total group and by age, sex, diagnosis, and mode of fixation. Median follow-up was 11 (0.8-15) years for unrevised knees in patients who were still alive. RESULTS: The 10-year cumulative survivorship was higher (93%, 95% CI: 81-97) when both components had been cemented than if either, or both, were uncemented (77%, CI: 67-83; p < 0.001). There was an increased incidence of failure in patients who were less than 60 years of age at the time of surgery (p = 0.004). INTERPRETATION: The smooth-backed Kinemax knee without cement was found to be associated with a high failure rate at 10 years. The 10-year cumulative survival results of the cemented prosthesis are acceptable.     

More failures of uncemented acetabular screw-rings than of cemented polyethylene cups in total hip arthroplasties

The results of 498 total hip arthroplasties were prospectively studied. In 329 patients a cemented acetabular polyethylene cup was inserted. In 169 patients a threaded socket without cement was introduced. Follow-up ranged from 6 to 8 years and follow-up rate was over 90%. Of the 169 threaded sockets 8 required revision (4.7%), and 3 acetabular components were seen to be loose on X-ray. Of the cemented cups, only 2 (0.6%) required revision and none were considered loose on X-ray.     

Fatal pulmonary embolism and mortality after revision of failed total hip arthroplasties

To assess the effect of extensive surgery and delayed mobilization on postoperative incidence of fatal pulmonary embolism, we reviewed the mortality rate in 1,294 patients undergoing 1,483 revisions of failed total hip arthroplasties, in which mobilization of the patients was delayed for up to 3 weeks. There were 6 deaths (mortality rate, 0.4%). All were submitted to autopsy; only 1 death was the result of pulmonary embolism. The results of our review do not support the view that more extensive surgery and delayed mobilization of the patient, as in revision of failed total hip arthroplasties, carries a high incidence of fatal pulmonary embolism.     

Long-term clinical results of cemented revision of primary cemented total hip arthroplasties

Seventy-six patients who had undergone revision of a cemented total hip replacement were reviewed with an average follow-up of almost ten years. The average age at primary total hip replacement (PTHR) was 63.3 years. The average time between primary total hip replacement and revision was 62.5 months. Revision surgery was performed without using special techniques such as acetabulum reconstruction or femoral bone grafting. We evaluated patients pre- and postoperatively using the Merle d'Aubigné-Postel(M d'A) hip score. Clinically we observed an improvement of the hip score after total hip revision, particularly regarding pain. Thirty hips required a second, and six a third revision. If re-revision is used as an end-point, our results are unsatisfactory, as we had a cumulative failure rate of 54% after 12 years. This is mainly due to not using special techniques adapted to revision situations.     

Failure rates for 4762 revision total hip arthroplasties in the Norwegian Arthroplasty Register

We present the results for 4762 revision total hip arthroplasties with no previous infection in the hip, which were reported to the Norwegian Arthroplasty Register between 1987 and 2003. The ten-year failure rate for revised prostheses was 26% (95% CI 25 to 26). Cox regression analyses were undertaken separately for acetabular and femoral revision components. Cemented revision components without allograft was the reference category. For acetabular components, we found a significantly reduced risk of failure for uncemented revisions both with (relative risk (RR) = 0.66; 95% CI 0.43 to 0.99) and without (RR = 0.37; 95% CI 0.22 to 0.61) allograft. For femoral components, we found a significantly reduced risk of failure for uncemented revisions, both with (RR = 0.27; 95% CI 0.16 to 0.46) and without (RR = 0.22; 95% CI 0.11 to 0.46) unimpacted allograft. This reduced risk of failure also applied to cemented revision components with allograft (RR = 0.53; 95% CI 0.33 to 0.84) and with impaction bone grafting (RR = 0.34; 95% CI 0.19 to 0.62). Revision prostheses have generally inferior results when compared with primary prostheses. Recementation without allograft, and uncemented revision with bone impaction, were associated with worse results than the other revision techniques which we studied.     

全髋关节翻修术中髋臼骨缺损的重建

目的探讨全髋关节置换术（THA）后，翻修术中髋臼骨缺损重建的方法及疗效。方法对81例（84髋）在THA翻修术中处理的髋臼骨缺损患者进行回顾性分析，根据AAOS分型法，Ⅰ型7髋，Ⅱ型56髋，Ⅲ型17髋，Ⅳ型4髋。分别采用大直径非骨水泥假体臼、非骨水泥假体臼＋松质颗粒植骨、骨水泥假体臼＋Cage＋松质颗粒植骨和骨水泥假体臼＋定制型假体＋松质颗粒植骨等方法，对不同类型骨缺损的患者进行修复。术后定期随访，采用Harris方法评估髋关节功能，根据X线片判断假体是否有松动，移植骨是否愈合。结果对本组患者进行术后随访，平均随访45个月（13～118个月）。术后Harris评分平均86．2分，较术前平均改善40．6分。2髋因脱位需进行再翻修，其余效果良好，X线片无假体松动下沉，可见移植骨一宿主骨交界处有连续性小梁骨通过。结论在THA翻修术中，大部分髋臼骨缺损可使用较大型号非骨水泥假体或加松质颗粒植骨进行修复；对于影响假体稳定性的较大缺损，使用骨水泥假体臼＋Cage＋松质颗粒植骨的方法可获得良好效果；定制型假体在处理严重髋臼骨缺损中有独特优势，具有良好的临床应用前景。