Reliability of acetabular bone defect classification systems in revision total hip arthroplasty

Three classifications for assessment of acetabular bone loss were evaluated for their reliability. The 3 systems assessed were the system described by Gross, the system described by Paprosky, and the classification of the American Academy of Orthopaedic Surgeons. In this study, we assessed their reliability based on the preoperative radiographs alone. Intraobserver agreement was measured by evaluating the classifications by the 3 innovators, 3 reconstructive orthopaedic surgeons, and 3 residents. Interobserver agreement was assessed among the reconstructive surgeons and the residents. The unweighted kappa statistic was used to establish levels of agreement. The innovators had better intraobserver agreement than the other 2 groups. Their agreement was only in the moderate range, however. For the noninnovators, intraobserver and interobserver agreement generally was poor for all 3 classifications assessed. Our results indicate that these classifications do not provide statistically reliable information for preoperative assessment of acetabular bone stock loss.     

Classifying failed hip arthroplasty: generalizability of reliability and validity

Interrater reliability and validity of a radiographic severity classification was evaluated in 81 patients having revision hip arthroplasty. Severity was rated separately on the femoral and acetabular sides using a five-level scale ranging from no significant loss of bone stock to uncontained loss of bone stock and discontinuity. Three academic orthopaedic surgeons rated preoperative anteroposterior radiographs taken within 6 weeks of surgery. Interrater reliability was 0.54 (weighted kappa) with 57% agreement on the acetabular side and 0.56 with 52% agreement on the femoral side. Rater to intraoperative findings agreed 45% of the time and weighted kappa was 0.41 on the acetabular side and agreed 38% of the time with weighted kappa of 0.39 on the femoral side. When radiographic and intraoperative ratings disagreed, 30% of the time no bony defect was found on the acetabular side. Fifty-eight percent of femoral radiographic ratings were upgraded intraoperatively. These results differ from previously reported results of high reliability from one institution with trained raters. A reliable and valid severity classification that is generalizable to multiple raters from different institutions is required to stratify patients for intervention studies, and to aid preoperative planning. Training in the classification system may improve generalizability.     

Analysis of validity and reliability of three radiographic classification systems for preoperative assessment of bone stock loss in revision total hip arthroplasty

AIM: It was the purpose of this prospective study to analyze validity and reliability of three different radiographic classification systems, which are used to assess bone stock loss prior to revision total hip arthroplasty. METHOD: Investigation was performed using the classification systems according to 1) Paprosky et al., 2) Hungerford et al., and 3) the German Society of Orthopaedics and Traumatology (DGOT). Twenty-eight consecutive patients with diagnosis of aseptic failure of total hip arthroplasty were enrolled in the study. Interrater agreement was analyzed by evaluating the classifications preoperatively by three investigators with different level of clinical experience using a blinded observer technique. Validity was analyzed by comparison of preoperative radiographic findings (n = 3) and an intraoperative control by visualization and palpation (n = 1). Spearman coefficient of correlation (r(s)) was used to establish levels of agreement among multiple ordinal variables. RESULTS: Interrater reliability testing using paired comparison between the three investigators revealed non-homogeneous coefficients of correlation (r(s): Paprosky femur: 0.45 - 0.67, acetabulum: 0.38 - 0.63; Hungerford: 0.46 - 0.66; DGOT femur: 0.38 - 0.59, acetabulum: 0.42 - 0.76). Paired analysis of correlation between preoperative and intraoperative findings again showed non-homogeneous coefficients of correlation (r(s): Paprosky femur: 0.59 - 0.68, acetabulum: 0.39 - 0.70; Hungerford: 0.39 - 0.74; DGOT femur: 0.44 - 0.60, acetabulum: 0.36 - 0.76). In general, defects were grossly underestimated preoperatively. The level of experience did not influence the validity of measurements. CONCLUSION: Our results indicate that these classifications do not provide valid and reliable assessment of femoral and acetabular bone stock loss prior to revision total hip arthroplasty.     

全髋翻修骨缺损分型的现状

全髋翻修中骨缺损的分型包括髋臼侧和股骨侧。髋臼侧的分型有美国骨科医师学会分型（AAOS）,Paprosky分型,Engh分型,Gross分型,Gustilo＆Pasternak分型和重庆髋臼骨缺损分型等。股骨侧的分型有美国骨科医师学会分型（AAOS）,Paprosky股骨缺损分型,Mallory分型,Taylor和Rorabeck的改良Mallory分型等。不同分型之间的术前评估不一致,导致了应用混乱,需要更多的研究。     

Reliability and intraoperative validity of preoperative assessment of standardized plain radiographs in predicting bone loss at revision hip surgery.

BACKGROUND: The most challenging aspect of revision hip surgery is the management of bone loss. A reliable and valid measure of bone loss is important since it will aid in future studies of hip revisions and in preoperative planning. We developed a measure of femoral and acetabular bone loss associated with failed total hip arthroplasty. The purpose of the present study was to measure the reliability and the intraoperative validity of this measure and to determine how it may be useful in preoperative planning. METHODS: From July 1997 to December 1998, forty-five consecutive patients with a failed hip prosthesis in need of revision surgery were prospectively followed. Three general orthopaedic surgeons were taught the radiographic classification system, and two of them classified standardized preoperative anteroposterior and lateral hip radiographs with use of the system. Interobserver testing was carried out in a blinded fashion. These results were then compared with the intraoperative findings of the third surgeon, who was blinded to the preoperative ratings. Kappa statistics (unweighted and weighted) were used to assess correlation. Interobserver reliability was assessed by examining the agreement between the two preoperative raters. Prognostic validity was assessed by examining the agreement between the assessment by either Rater 1 or Rater 2 and the intraoperative assessment (reference standard). RESULTS: With regard to the assessments of both the femur and the acetabulum, there was significant agreement (p < 0.0001) between the preoperative raters (reliability), with weighted kappa values of >0.75. There was also significant agreement (p < 0.0001) between each rater's assessment and the intraoperative assessment (validity) of both the femur and the acetabulum, with weighted kappa values of >0.75. CONCLUSIONS: With use of the newly developed classification system, preoperative radiographs are reliable and valid for assessment of the severity of bone loss that will be found intraoperatively.     

打压植骨结合金属网重建髋臼严重骨缺损

目的 评价打压植骨结合金属网重建严重骨缺损髋臼的中期临床效果,分析Paprosky骨缺损分型在评价骨缺损时的重要性.方法 1998年12月至2007年12月采用打压植骨技术结合使用金属网片和(或)金属网杯进行严重髋臼缺损重建63例(67髋),所有患者均为AAOS Ⅲ型混合型缺损.其中58例患者(61髋)获得了完整随访,平均63个月.Paprosky Ⅱ B 19例(20髋),Paprosky Ⅱ C 27例(28髋),Paprosky Ⅲ A 12例(13髋).术前Harris髋关节评分平均41.7分(21～52分).术后随访时进行临床疗效、影像学及并发症等评估.结果 58例(61髋)患者Harris髋关节评分术后平均89.2分(81～98分),术后优良率达93%,除3例发生聚乙烯髋臼从网杯中脱出外,其余55例患者髋臼无影像学松动.1例使用金属网杯患者髋臼旋转中心未能恢复正常.3例术后脱位患者,其中2例手法复位,1例切开复位,均获成功.术后发生感染1例(1.6%),经二期翻修打压植骨成功治愈.结论 异体骨打压植骨配合金属网是处理严重髋臼骨缺损的理想技术.建议在使用打压植骨技术对严重髋臼缺损重建时,采用AAOS分型结合Paprosky分型方法对缺损的严重程度进行评价.金属网杯不适用于严重髋臼骨缺损的打压植骨重建.     

The Inter-Observer and Intra-Observer Reliability of the Paprosky Femoral Bone Loss Classification System

The Paprosky classification provides a straightforward algorithm for defining bone loss and directing treatment for femoral revision. The purpose of this study was to test the inter-observer and intra-observer reliability of this system. Four arthroplasty surgeons reviewed radiographs of 205 consecutive femoral revisions. For each radiograph, the pattern of femoral bone loss was classified by Paprosky type on two separate occasions. A kappa value was used to calculate the reliability, which demonstrated an inter-observer reliability of 0.61, indicating substantial agreement between surgeons. The intra-observer reliability for each of the 4 participating surgeons was 0.81, 0.78, 0.76, and 0.75, indicating substantial to almost perfect agreement. There is substantial agreement among experienced arthroplasty surgeons when using the Paprosky Classification to characterize femoral bone loss.     

6 years follow-up of hip revision surgery

Revision total hip arthroplasty often presents surgeons with difficult bone loss problems. The purpose of this study was to evaluate the results of hip revision surgery according to bone stock We evaluated, in a retrospective study, 148 hip revision surgeries during 2004 to 2010. The Harris Hip Score (HHS), the acetabular cementation, the AAOS classification, the SOFCOT 99 bone loss grading and Barrack classification were used for clinical and radiological assessment. It can be observed significant improvement of HHS from a mean value of 45 preoperatively to 77.2 points postoperatively. Grade B acetabular cementation was observed in a significantly higher rate for situations that needed acetabular allograft reconstruction and where it cannot be performed because of allografts lack. Barrack grades C and D cementation were associated with 70% of SOFCOT 99 stage III and IV cases and only 5% of SOFCOT 99 stage 0-II cases.Using bone graft seems to be a reliable solution for restoring bone stock and stabilizing the cup in revision total hip arthroplasty with type II-IV acetabular defect according to the AAOS classification. Because SOFCOT 99 stages III-IV are often associated with poor cementation we prefer using uncemented distally fixed with screws revision stems for these cases.     

Revision total hip arthroplasty: analysis of the predictive value of a radiographic classification system for assessment of bone stock loss

AIM: The aim of this study was to evaluate the predictive value of a radiographic classification system concerning implant and bone graft in revision total hip arthroplasty. This classification is used to assess bone stock loss prior to surgery, thus hypothetically enabling an adequate choice of the implant and bone graft required. METHOD: 33 consecutive patients with the diagnosis of aseptic failure of total hip arthroplasty were included in the study. The investigation was performed using the classification system according to Saleh et al. The predictive value was analyzed by comparing the radiographically based recommendation concerning implant and bone graft and the intraoperative procedure according to a blinded observer technique. The Spearman coefficient of correlation (r (s)) was used to establish levels of agreement among multiple ordinal variables. RESULTS: Analysis of correlation between preoperative radiological estimations and intraoperative conclusions concerning implant and bone graft revealed coefficients of correlation (r (s)) of 0.53 (p < 0.01) for the acetabular and of 0.63 (p < 0.01) for the femoral classification. CONCLUSION: Our results indicate that the Saleh classification does not provide sufficient information for preoperative assessment of the revision implant and bone graft required concerning the acetabular side, whereas planning of the operative procedure regarding the femoral implant seems to be possible. These ambivalent findings should be taken into account prior to revision total hip arthroplasty.     

Ganz reinforcement rings in acetabular revision: indications and medium-term results

Metal reinforcement rings, systems used widely in the past for prosthetic revision surgery, are still effective, in that they allow us to restore the correct hip rotation center and protect the bone grafts used to increase acetabular bone stock. To provide a better definition of the current indications for use of reinforcement rings in acetabular revisions we conducted a retrospective study in a group of 25 patients in whom a Ganz reinforcement ring was used in association with autoclaved cancellous bone grafts. The Ganz ring is made of titanium and it has a lower hook that contributes to the mechanical stability of the implant. Mean age of patients was 72.5 years. Pre-revision acetabular bone defects were divided according to the Paprosky classification system: type 2A: 2 cases; type 2B: 6 cases; type 2C: 6 cases; type 3: 6 cases; type 3B: 5 cases. Clinical and radiographic results were evaluated after a mean follow-up of 4.6 years. Score based on the Harris evaluation form went from a mean preoperative value of 45 points to 92 points after revision. Overall, clinical results were excellent in 9 cases (36%), good in 12 cases (48%), fair in 3 cases (12%), poor in 1 case (4%). Radiographically, we observed a significant reduction (62%) in mean vertical distance of the hip rotation center after revision, that contributed to reduction in hypometria of the limb submitted to surgery, ranging from a mean preoperative value of 2.2 cm to 0.72 cm after surgery. Stability of the implant in time was evaluated based on the Gill criteria. None of the cases required further revision surgery; in 3 cases (12%) with type 3 preoperative defects, the implant was judged to be probably or possibly loosened because of the presence of radiolucent lines.     

Reinforcement of deficient femur with inlay strut grafts in revision hip arthroplasty: a small series

Failure of the femoral component due to severe loss of femoral bone is an important long-term complication of total hip arthroplasty. We treated four patients with a type IV femoral defect (Paprosky classification) because of aseptic and septic loosening. To enhance bone stock and create a stable prosthetic reconstruction we used femoral allografts as inlay strut grafts alone or combined with onlay strut grafts and impaction grafting. At a mean follow-up of 11 years all four patients presented good or excellent results with Harris Hip Score between 86 and 95 points. Radiologically, no migration of the stems were found and the struts showed signs of incorporation. Inlay strut grafts are a reliable method for bone reconstruction of deficient femoral bone stock in failed total hip replacement.     

植骨技术结合金属网杯重建髋臼骨缺损在全髋关节置换术中的应用

 目的 评估植骨技术结合金属网杯重建髋臼骨缺损在全髋关节置换术中的应用价值。方法 2008年1月至2011年11月,采用植骨技术结合金属网杯重建全髋关节置换术中髋臼骨缺损32例(32髋),男23例,女9例;年龄51~76岁,平均66岁。初次全髋关节置换6例,翻修26例。PaproskyⅡB型骨缺损12例,采用打压植骨结合钛网重建;ⅡC型骨缺损13例,采用打压植骨结合钛网重建7例、打压植骨结合金属加强杯重建6例;ⅢA型骨缺损7例,采用结构植骨+打压植骨结合带翼金属加强杯重建6例、双层打压植骨结合钛网及金属加强杯重建1例。疗效通过影像学Gill金属网杯松动评定标准和Harris髋关节评分进行评估。结果 全部病例获得随访,随访时间12~25个月,平均22个月。术后12个月Harris髋关节评分由术前(44.00±11.71)分提高至(78.41±9.32)分;优24例、良4例、可4例,优良率87.5%。3例出现髋臼旋转中心轻度移位,1例发生脱位,其余28例未发生固定物松动、下沉及植骨吸收。结论 根据髋臼缺损Paprosky分型选择钛网或金属加强杯结合打压植骨或结构性植骨技术,可以重建髋臼骨缺损,从而提高髋臼杯的稳定性。     

Characterizing Femoral and Acetabular Bone Loss in Two-Stage Revision Total Hip Arthroplasty for Infection

BackgroundThe process of infection and multiple procedure-related factors in 2-stage exchange arthroplasty may lead to severe bone loss that can complicate subsequent reimplantation. The primary purpose of this study is to quantitatively characterize the extent of bone loss on the femoral and acetabular side prior to reimplantation during 2-stage revision hip arthroplasty for infection.MethodsThis retrospective case series includes 47 patients with planned 2-stage exchange arthroplasty for treatment of infected total hip replacement. Demographic, clinical, and surgical information, and complications during the 2-stage process were collected on all patients. The radiographs of all patients were reviewed prior to first-stage explantation and post-reimplantation or latest follow-up to characterize bone loss using the Paprosky classification systems.ResultsOf the 47 patients with planned 2-stage exchange, 10 patients (21%) were not reimplanted. Following explant and spacer placement, 32 patients (68%) experienced progressive femoral bone loss, and 20 (43%) experienced progressive acetabular bone loss. Patients who experienced progression of both femoral and acetabular bone (14, 30%) had a longer time between resection and reimplantation (164 ± 128 vs 88 ± 26 days, P = .03). A reimplantation time of greater than 90 days was associated with an increased risk of combined bone loss progression (15% vs 53%, P = .01). For patients who underwent reimplantation (79%), increased bone loss led to high rates of diaphyseal femoral fixation (97%) and revision acetabular components (38%).ConclusionIncreased time to reimplantation in 2-stage exchange arthroplasty for prosthetic hip infections is associated with a high rate of acetabular and femoral bone loss, and increased complexity of reimplantation.     

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。     

Classifying femoral bone deficiency: Picking the right tool for the job

Femoral revision in total hip arthroplasty is challenging with much preparation required by surgeon in order to have the best outcomes. The Paprosky femoral classification system is the most commonly used, well-described, and successfully utilized classification system for periprosthetic femoral bone loss. It is based on the volume of supportive native bone in order to allow appropriate and durable fixation. This article presents an overview of the Paprosky femoral bone loss classification and the options for each type of defect.     

A prospective outcomes analysis of femoral component fixation in revision total hip arthroplasty

A prospective, surgeon-allocated, matched cohort analysis of patient outcomes compared cementless, modular metaphyseal and cemented femoral fixation used for revision total hip arthroplasty. First-time femoral revision operations (with and without acetabular revision) with Paprosky types I and II femoral bone stock were included. This series of 86 patients was matched for age, weight, diagnosis, Charnley class, Demand category, femoral bone stock, and outcome measures. At 8-year average follow-up (range, 4-13 years), there were no significant differences in visual analog pain scores (VAPS), Harris Hip Scores (HSS), and SF-36 Physical Function and Bodily Pain scores. One femoral rerevision (2.3%) occurred in the cementless group, and 2 (4.6%) occurred in the cemented group (P = .557). Five-year survivorship for femoral rerevision was 94% for patients with cementless, modular metaphyseal fixation and 92% for patients with cemented fixation. In this study, cementless, modular metaphyseal fixation and cemented femoral fixation were both successful at intermediate-term follow-up in Paprosky types I and II femoral bone (level of evidence: therapeutic study; level II, prospective comparative study).     

Classifying femoral bone deficiency: Picking the right tool for the job

The number of total hip arthroplasties continues to increase each year, and with it grows the demand for surgeons prepared to manage complicated revisions. To date, the Paprosky classification system is the most commonly used, well described, and successfully implemented classification system for periprosthetic femoral bone loss. In this review, the Paprosky femoral bone loss classification is presented in detail, using illustrative examples of cases encountered by the contributing authors.     

髋臼PaproskyⅢ型骨缺损髋臼加强杯翻修的中期疗效

目的 探讨髋臼Paprosky Ⅲ型骨缺损采用异体骨植骨结合髋臼加强杯翻修的中期临床疗效 方法 回顾性分析2002年1月至2009年12月采用髋臼加强杯翻修髋臼Paprosky Ⅲ型骨缺损患者的病历资料,19例(20髋)最终获得随访,男11例,女8例;年龄42～76岁,平均(57.4±6.4)岁.Paprosky ⅢA型7例(35％),ⅢB型13例(65％).平均随访(5.8±2.4)年.评价患者手术前后髋关节功能、术后髋臼加强杯的影像学稳定性和植骨效果.以髋臼加强杯失败为终点,采用Kaplan-Meier生存分析评价髋臼加强杯的五年生存率.结果 术前Harris髋关节评分为6～31分,平均(14.6±4.3)分,末次随访时为64～98分,平均(83.5±7.9)分.术前肢体平均短缩(26.3±9.1) mm,术后肢体平均短缩(1.2±3.4) mm.术前髋关节旋转中心相对于解剖旋转中心向上方平均移位(23.6±7.4) mm,向外平均移位(4.4±14.7)mm;术后关节旋转中心均恢复到Ranawat三角内.所有病例植入的异体骨均与宿主骨融合.无髋臼加强杯移位、螺钉断裂、进展性透亮线以及骨水泥断裂发生.3例(3髋)患者(15％)出现轻度骨吸收,未出现中度或重度骨吸收患者.髋形假体的五年生存率为100％(95％可信区间,0.95～1.0).结论 对于髋臼Paprosky Ⅲ型骨缺损采用异体骨植骨结合髋臼加强杯重建髋臼可获得较满意的中期翻修效果.     

Interobserver and intraobserver reliability of two classification systems for intra-articular calcaneal fractures

BACKGROUND: For a fracture classification to be useful it must provide prognostic significance, interobserver reliability, and intraobserver reproducibility. Most studies have found reliability and reproducibility to be poor for fracture classification schemes. The purpose of this study was to evaluate the interobserver and intraobserver reliability of the Sanders and Crosby-Fitzgibbons classification systems, two commonly used methods for classifying intra-articular calcaneal fractures. METHODS: Twenty-five CT scans of intra-articular calcaneal fractures occurring at one trauma center were reviewed. The CT images were presented to eight observers (two orthopaedic surgery chief residents, two foot and ankle fellows, two fellowship-trained orthopaedic trauma surgeons, and two fellowship-trained foot and ankle surgeons) on two separate occasions 8 weeks apart. On each viewing, observers were asked to classify the fractures according to both the Sanders and Crosby-Fitzgibbons systems. Interobserver reliability and intraobserver reproducibility were assessed with computer-generated kappa statistics (SAS software; SAS Institute Inc., Cary, North Carolina). RESULTS: Total unanimity (eight of eight observers assigned the same fracture classification) was achieved only 24% (six of 25) of the time with the Sanders system and 36% (nine of 25) of the time with the Crosby-Fitzgibbons scheme. Interobserver reliability for the Sanders classification method reached a moderate (kappa = 0.48, 0.50) level of agreement, when the subclasses were included. The agreement level increased but remained in the moderate (kappa = 0.55, 0.55) range when the subclasses were excluded. Interobserver agreement reached a substantial (kappa = 0.63, 0.63) level with the Crosby-Fitzgibbons system. Intraobserver reproducibility was better for both schemes. The Sanders system with subclasses included reached moderate (kappa = 0.57) agreement, while ignoring the subclasses brought agreement into the substantial (kappa = 0.77) range. The overall intraobserver agreement was substantial (kappa = 0.74) for the Crosby-Fitzgibbons system. CONCLUSIONS: Although intraobserver kappa values reached substantial levels and the Crosby-Fitzgibbons system generally showed greater agreement, we were unable to demonstrate excellent interobserver or intraobserver reliability with either classification scheme. While a system with perfect agreement would be impossible, our results indicate that these classifications lack the reproducibility to be considered ideal.