Mechanical stability of porous-coated acetabular components in total hip arthroplasty.

Five different porous-coated acetabular prosthetic configurations underwent in vitro testing to assess mechanical stability in embalmed cadaver hemipelves: Harris Galante II cup with three cancellous screws, Biomet Universal cup, Whiteside cup with peripheral pegs, Whiteside cup with two cancellous screws, and plain Whiteside cup. Following implantation in a neutral frame, cyclic load testing was done using 33 specimens at 100-kg load for 100,000 cycles using an MTS machine (MTS Systems Corp., Minneapolis, MN). Subsequently, static load-to-failure testing was done in all specimens. Subsidence and micromovement were determined for each specimen using linear variable differential transformers. With cyclic testing, overall cup subsidence revealed a significant increase, from 500 to 100,000 cycles. Overall cup micromovement revealed a significant decrease, and all cup groups demonstrated less than 125 microns (.125 mm) of average mean micromotion at the completion of cyclic testing. The best cup configuration was a 1-mm, oversized, press-fit cup using two 6.5 cancellous screws for additional fixation, which revealed an average mean of 60 microns (.06 mm) of micromovement. Static load testing revealed unacceptable micromovement over 150 microns (.150 mm) in most cups with 300-kg loads.     

Trabecular metal acetabular components in primary total hip arthroplasty

Background and purpose — Trabecular metal (TM) cups have demonstrated favorable results in acetabular revision and their use in primary total hip arthroplasty (THA) is increasing. Some evidence show that TM cups might decrease periprosthetic infection (PPI) incidence. We compared the survivorship of TM cups with that of other uncemented cups in primary THA, and evaluated whether the use of TM cups is associated with a lower risk of PPI.

Patients and methods — 10,113 primary THAs with TM cup and 85,596 THAs with other uncemented cups from 2 high-quality national arthroplasty registries were included. The mean follow-up times were 3.0 years for the TM cups and 3.8 years for the other uncemented cups.

Results — The overall survivorship up to 8 years for TM cups and other uncemented cups was 94.4% and 96.2%, respectively (p = < 0.001). Adjusting for relevant covariates in a Cox regression model the TM cups had a persistently higher revision risk than other uncemented cups (HR =1.5, 95% CI 1.4–1.7, p = < 0.001). There was a slightly higher, though not statistically significant, revision rate for PPI in the TM group (1.2, 95% CI 1.0–1.6, p = 0.09).

Interpretation — Risk of revision for any reason was higher for the TM cup than for other uncemented cups in primary THA. In contrast to our hypothesis, there was no evidence that the revision rate for PPI was lower in the TM cup patients. Regardless of the promising early and mid-term results for TM cups in hip revision arthroplasty, we would like to sound a note of caution on the increasing use of the TM design, especially in uncomplicated primary THAs, where uncemented titanium cups are considered to provide a reliable outcome.     

广泛微孔涂层非骨水泥假体在股骨翻修的应用

目的报告采用广泛微孔涂层非骨水泥股骨假体对失败的骨水泥固定股骨假体翻修的近期效果。方法1998年至2003年,对20例骨水泥固定型人工髋关节置换后无菌性松动的股骨假体采用广泛微孔涂层假体进行翻修。翻修前使用国产假体18例,进口假体2例;全髋关节置换14例,人工股骨头置换6例。所有假体均为骨水泥固定,早期骨水泥技术固定18例,第二代骨水泥技术固定2例。原始疾病为股骨头无菌性坏死14例,股骨颈骨折6例。从初次关节置换到翻修手术的时间最短5年,最长17年,平均11.5年。其中4例患者为再次翻修。根据Paprosky分型,Ⅰ型3髋,Ⅱ型6髋,ⅢA型11髋。翻修假体,AML(DePuy)5髋,Solution(DePuy)7髋,Full-coated(Zimmer)6髋,Perfecta延长柄(WrightMed)2髋。翻修时患者平均年龄64岁(41～77岁),术后平均随访时间40个月(18～60个月)。结果Harris评分从术前平均34分改善为术后平均85分。根据Engh骨长入分级标准评定,术后X线表现骨性固定17例,稳定性纤维固定3例。无一例因松动需要再翻修的病例,骨皮质密度和厚度均明显增加。结论广泛微孔涂层假体在股骨干骺端和股骨髓腔同时存在缺损时,可以在相对正常的股骨远端髓腔获得轴向及抗旋转初始稳定,为骨长入和生物学固定创造条件。     

Noncemented porous-coated anatomic total hip arthroplasty

In 1984, as an alternate to the acrylic fixation of the components of total hip arthroplasty, the use of an uncemented porous-coated anatomic (PCA) hip system with a beaded porous coating to achieve biologic fixation was initiated. Since then, 44 patients with cementless acetabular components and 35 patients with cementless femoral components have been followed for a minimum of 24 months and an average of 37 months. Harris hip scores averaged 90.5 at most recent follow-up intervals. No reoperations were necessary for failures of fixation or change in position of the acetabular component. Ominous roentgenographic signs such as progressive bead shedding, progressive radiolucencies, or progressive component migration have not occurred. Two femoral component revisions have been necessary: one for intractable pain and one for pain and roentgenographic loosening. Although thigh pain has been prevalent (20%), all patients have been accommodated and have retained stable hip scores. Progressive radiolucencies and progressive implant subsidence have been rare occurrences. The authors continue to use the cementless acetabular component in all cases of total hip arthroplasty in which initial stability can be obtained. It is their preference to cement the femoral component in patients over 65 or when initial stability cannot be achieved.     

Use of custom triflanged acetabular components in revision total hip arthroplasty

Difficulty persists in consistently treating massive acetabular defects in revision total hip arthroplasty. A relatively new treatment option for these complex cases is a custom triflanged acetabular component created from anatomic data derived from a computed tomography scan of the pelvis. The custom triflanged acetabular component achieves fixation on the remaining ilium, ischium, and pubis with multiple fixation screws while the acetabular defect is filled with cancellous allograft bone. A retrospective review was done of 26 hips (26 patients) with massive periacetabular bone loss (Paprosky Type 3B) reconstructed with a custom triflanged acetabular component. Twenty-three of 26 patients (88.5%) were considered clinically successful at short-term followup (average, 54 months; range, 24 to 85 months), with stable fixation and reconstruction of periacetabular bone. Three failures occurred from loss of ischial fixation in two patients with a preoperative pelvic discontinuity and one patient with severe osteopenia. These devices should be used with caution in patients with a preoperative pelvic discontinuity unless additional column plating is done.     

Impingement in total hip arthroplasty a study of retrieved acetabular components

Impingement can damage the acetabular liner, create polyethylene wear, and cause dislocation. We determined the prevalence of impingement, its relation with dislocation, and the influence of patient, surgical, and design factors in 162 components randomly selected from a larger group retrieved between 1990 and 1999. Impingement arc, severity, and wear damage were measured; patient data were obtained from medical records, and component position was determined from radiographs. More than half (56%) showed impingement, including 94% of those removed for dislocation. The occurrence of impingement was significantly increased if the revision diagnosis was dislocation, if the component had a large outer diameter or an elevated rim, and if the femoral component had an extended flanged neck. Implant design, in particular head/neck ratio, can help reduce the prevalence of impingement.     

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.     

Threaded acetabular components for primary and revision total hip arthroplasty

A clinical and radiographic review of 48 total hip arthroplasty patients with threaded acetabular components was undertaken at 24-44 months of follow-up study. Twenty-five patients had primary hip arthroplasties and 23 had revision procedures. Clinical scores revealed good to excellent results in 60% of primary and 30% of revision procedures. Radiographic analysis revealed stable acetabular components in 88% of primary and 61% of revision procedures. Potentially loose acetabular components were noted in 8% of primary and 4.3% of revision procedures and loose acetabular components in 4% of primary and 34.7% of revision procedures. The rate of acetabular component loosening was considered unacceptably high in revision cases and an area of concern in primary cases. Discretionary use of these components is advised.     

钽金属臼杯重建髋臼骨缺损的近期疗效

 目的 探讨应用钽金属臼杯对不同类型髋臼骨缺损进行重建的近期疗效。方法 回顾性分析2009年8月至2012年4月在全髋关节置换术中使用钽金属臼杯重建髋臼骨缺损的连续21例患者的病例资料,男6例,女15例;年龄24~78岁,平均(53.7±16.2)岁。初次全髋关节置换5例：Crowe Ⅳ型髋关节发育不良2例、髋关节感染后遗高位脱位畸形2例、类风湿关节炎1例;全髋关节翻修16例：全髋关节置换术后感染二期翻修2例、髋臼金属炎性假瘤3例、假体无菌性松动11例。骨缺损Paprosky分型Ⅰ型9例,Ⅱa型4例,Ⅱb型5例,Ⅱc型1例,Ⅲa型1例,Ⅲb型1例。观察术后髋臼假体周围透光线、假体位置、生存率、并发症及Harris髋关节评分。结果 全部病例随访6~40个月,平均20.1个月。末次随访时PaproskyⅠ型患者的Harris髋关节评分(87.2±7.4)分,高于术前(41.1±6.3)分;Ⅱ型(79.8±11.8)分,高于术前(38.4±12.5)分;Ⅲ型为79分,高于术前24分。随访期间钽金属臼杯固定良好,未出现松动及移位,假体生存率100%。按照Anderson骨长入影像学评价标准,髋臼杯均出现不同程度骨长入。1例于DeLee-Charnley髋臼3区出现透光线,4个月后消失;1例于髋臼1区出现假体周围间隙,随访6个月未进展。1例于术后4周出现后脱位。结论 应用钽金属臼杯重建PaproskyⅠ、Ⅱ型髋臼骨缺损,能实现早期与宿主骨整合,近期疗效好。     

Using intraoperative pelvic landmarks for acetabular component placement in total hip arthroplasty

Dislocation after total hip arthroplasty is frequently due to acetabular malpositioning. Positioning of the acetabular component using anatomical landmarks may reduce the incidence of dislocation from improper acetabular orientation. The pelvis provides 3 bony landmarks (ilium, superior pubic ramus, and superior acetabulum), which, when used to define a plane, allows cup orientation in abduction and version. Landmarks evaluated in 24 cadaveric acetabuli allowed slightly increased abduction and anteversion of the cup, compared with native acetabuli. Six hundred seventeen primary total hip arthroplasties were performed between 1996 and 2003 using this technique. Mean cup abduction was 44.4 degrees with 13.2 degrees of anteversion. This technique allows satisfactory reproducible cup orientation based on individual pelvic morphology. Review of patient outcome data suggest high patient satisfaction and lower dislocation rate without additional equipment, time, or cost.     

Bilobed oblong porous coated acetabular components in revision total hip arthroplasty

Thirty-eight oblong bilobed noncustom uncemented, porous-coated titanium acetabular components were used to reconstruct failed hip arthroplasties with large superior segmental acetabular bone deficiencies. No structural bone grafts were used. All patients were followed up for 2 to 5 years (mean, 3 years) after the operation. One patient (whose socket rested primarily on a structural bone graft from a previous procedure) had revision surgery for acetabular loosening. No other patients have had revision surgery or had another ipsilateral hip operation. At latest followup, 35 patients had no or mild pain and two patients had moderate pain. Two implants migrated more than 2 mm in the first year, then stabilized. On the latest radiographs, two implants had bead shedding, but there was no measurable migration or change in position. For selected patients with large superolateral acetabular bone deficiencies, this implant facilitated a complex reconstruction, provided good clinical results, and showed satisfactory stability at early to midterm followup in most patients.     

Prospective study of porous-coated anatomic total hip arthroplasty

Seventy-five uncemented porous-coated total hip prostheses were implanted in 64 patients. The results were reviewed after a mean follow-up period of 47 months (range, 40-64 months). The mean preoperative rating was fair, and the mean postoperative rating was excellent. There were six dislocations. Ten patients had mild thigh pain at one year; by two years, the pain had resolved in six patients. Neither moderate nor severe limp nor significant loosening of beads was observed. Only one patient had progressive radiolucent lines. The high rate of dislocation may be related to a compromise of acetabular position to obtain bony fixation in acetabula early in the series. The clinical results were encouraging.     

Fate of cementless acetabular components retained during revision total hip arthroplasty

BACKGROUND: Removal of a well-fixed cementless acetabular component can result in increased operative time and postoperative morbidity. The objectives of this retrospective study were to determine whether retention of a well-fixed acetabular component at the time of isolated femoral revision was compatible with long-term socket survival. METHODS: The records of eighty-three consecutive patients (ninety hips) in whom a well-fixed cementless socket had been retained during revision of a femoral component were reviewed. The mean age of the patients was 48.7 years at the time of the primary arthroplasty and 54.1 years at the time of femoral revision. The radiographic analysis was based on anteroposterior radiographs and was performed by a single independent reviewer. The intraoperative criterion for stability of the socket was the absence of movement at the bone-implant interface during the application of direct pressure to the edges of the socket in four quadrants with use of a metallic pusher. RESULTS: At the time of the isolated femoral revision, no socket demonstrated a radiolucent line measuring >1 mm in any two zones and forty of the ninety hips had periacetabular osteolysis. The mean size of the osteolytic lesions was 5.71 cm(2) (range, 0.4 to 24.2 cm(2)), and twenty-eight of the forty hips underwent bone-grafting. The mean duration of follow-up was 9.7 years after the isolated femoral revision and 14.9 years after the primary arthroplasty. Five acetabular sockets were revised at a mean of 6.8 years after the femoral revision. Only one of these sockets had failed because of aseptic loosening. With revision of the acetabular component for any reason as the end point, the survival rate was 98.7% at five years and 93.5% at ten years after the femoral revision and 100% at ten years and 93.9% at fifteen years after the primary arthroplasty. No hip showed recurrence or expansion of periacetabular osteolysis. The prevalence of dislocation was 16% (fourteen of ninety). CONCLUSIONS: Revision of a stable, cementless acetabular component solely on the basis of its duration in vivo or the presence of periacetabular osteolysis does not appear to be warranted. Retention of the socket with grafting of larger periacetabular osteolytic lesions appears to be consistent with satisfactory socket longevity.     

Osteointegration of bone graft in porous-coated total hip arthroplasty

Since 1983, 19 patients have had bone grafting of acetabular defects in association with a porous-coated acetabular prosthesis. The defects were defined by anatomic location to assess the rates of incorporation at different sites. The average time to incorporation was 12 months, judged by trabecular continuity. Superolateral grafts showed a greater degree of rarefaction than medial grafts. Nonprogressive migration of the graft was seen in only two cases before full incorporation of the graft. Developing lucency was seen up to 2 mm at the prosthesis-graft interface but not at the graft-ilium level. Roentgenograms suggested that integration of porous acetabular prostheses into bone may improve results of reconstructive surgery of the acetabulum.     

Cementless total hip arthroplasty using porous-coated Biomet acetabular cups (Hexloc and Ringloc types)

This study examined the mid-term (more than 5 years) results of cementless total hip arthroplasty (THA) using Biomet acetabular cups (locking mechanism: Hexloc type or Ringloc type). A series of 58 patients (70 hips) who had undergone cementless THA at our department were available for inclusion in this study. The average age at surgery was 55.2 years, and the average follow-up was 6 years 10 months. Osteolysis occurred in five cases. In the group with osteolysis, the average annual linear wear was 0.18mm/year, and in the group without osteolysis it was 0.10mm/year. The higher linear wear rate in the osteolysis group was statistically significant compared to that in the nonosteolysis group. The age of the patient was closely related to polyethylene (PE) wear in the Hexloc group but not in the Ringloc group. In the Ringloc group there was no close correlation between the thickness of the PE liner and the average annual linear wear, whereas in the Hexloc group the thicker liner had significantly less annual linear wear. It was thought that PE wear of the Hexloc cup was more susceptible to the age of the patient at surgery and the PE thickness than that of the Ringloc cup owing to several structural differences, such as rotational stability and conformity between the metal cup and the PE liner.     

高位全髋关节置换治疗CroweⅡ和Ⅲ型成人髋臼发育不良

[目的]观察全髋关节置换术(total hip arthroplasty, THA)中髋臼高位放置治疗CroweⅡ型、Ⅲ型髋关节发育不良(developmental dysplasia of the hips, DDH)的临床疗效。[方法]回顾性分析2014年2月~2016年10月本院收治的行THA治疗的21例(28髋) CroweⅡ型和Ⅲ型DDH患者(高位放置组),以同期19例(26髋)接受THA治疗的CroweⅠ型DDH患者为对照(解剖位放置组)。采用Trendelenburg征和Harris髋关节评分评价临床效果,拍摄双髋关节正侧位X线片,测量髋关节旋转中心距泪滴的垂直距离和水平距离、下肢长度差异。[结果]高位放置组手术时间和术中出血量均低于解剖位放置组,差异有统计学意义(P<0.05)。术后2年时,CroweⅠ型、CroweⅡ型和CroweⅢ型DDH患者Harris评分的差异无统计学意义(P>0.05)。术后所有患者步态良好,无跛行发生,Trendelanburg征均为阴性。所有患者X线片均未见放射性透亮线和假体下沉,高位放置组和解剖位放置组双下肢长度差值比较差异无统计学意义。CroweⅡ型和Ⅲ型患者髋关节旋转中心距泪滴的垂直距离均高于CroweⅠ型患者(P<0.05),而组间水平距离的比较差异无统计学意义(P>0.05)。[结论] THA术中髋臼高位放置治疗CroweⅡ型、Ⅲ型DDH的效果较好,未来需要扩大样本量,并进行长期随访,以证实本研究结论。     

In vitro initial fixation of porous-coated acetabular total hip components. A biomechanical comparative study

Two-phase in vitro testing was performed to determine the initial mechanical stability of uncemented but fixed porous coated acetabular components. Six each of three-screw fixation, two-peg fixation, and three-spike fixation porous acetabular components were implanted into fresh and embalmed human cadaver acetabula. Measurement of prosthesis-bone displacement at a load of 100 kg did not show a significant difference among the three methods of fixation. However, torque testing showed that three-screw fixation failed at significantly higher loads (46 N-m) than two-peg fixation (32 N-m) or three-spike fixation (32 N-m).