JBJS | Reliability and Intraoperative Validity of Preoperative Assessment of Standardized Plain Radiographs in Predicting Bone Loss at Revision Hip Surgery

The Journal of Bone & Joint Surgery, Volume 83, Issue 7

Articles | July 01, 2001

Reliability and Intraoperative Validity of Preoperative Assessment of Standardized Plain Radiographs in Predicting Bone Loss at Revision Hip Surgery

Khaled J. Saleh, MD, MSc(Epid), FRCSC; Jeremy Holtzman, MD, MS; Amiram Gafni, PhD; Lena Saleh, BScN, RN; Aileen Davis, PhD; Scott Resig, MD; Allan E. Gross, MD, FRCSC

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Investigation performed at the University of Toronto, Toronto, Ontario, Canada; the University of Minnesota, Minneapolis, Minnesota; and the Hospital for Special Surgery, Cornell Medical Center, New York, NY
Khaled J. Saleh, MD, MSc(Epid), FRCSC
Scott Resig, MD
Department of Orthopedics, University of Minnesota, Clinical Outcome Research Center, 492-420 Delaware Street SE, Minneapolis, MN 55455. E-mail address for K.J. Saleh: saleh002@tc.umn.edu

Jeremy Holtzman, MD, MS
Department of Medicine and Division of Health Services Research and Policy, University of Minnesota, 420 Delaware Street SE, Minneapolis, MN 55455

Amiram Gafni, PhD
Health Economics and Policy Analysis, Clinical Epidemiology and Biostatistics, McMaster University, 1200 Main Street West, Hamilton, Ontario L8N 3Z5, Canada

Lena Saleh, BScN, RN
Aileen Davis, PhD
Allan E. Gross, MD, FRCSC
Division of Orthopedics, Mount Sinai Hospital, University of Toronto, 600 University Avenue, Suite 476A, Toronto, Ontario M5G 1X5, Canada

One or more of the authors has received or will receive benefits for personal or professional use from a commercial party (Smith and Nephew) related directly or indirectly to the subject of this article. K.J. Saleh is supported by a career health services research award from the Orthopaedic Research and Education Foundation, and A. Davis is supported by a career health award from the Canadian Institute of Health Research. No funds were received in support of this study.

The Journal of Bone & Joint Surgery. 2001; 83:1040-1046

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Abstract

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.

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Introduction

Introduction | Materials and Methods | Results | Discussion | References

Approximately 170,000 total hip arthroplasty procedures are performed annually in the United States and, because of the aging of the population and an increase in the indications for the procedure, the demand is expected to double by the year 2030¹. As this number grows, the number of revisions of total hip arthroplasties will also grow. In a study from Ontario, the number of revision procedures was reported to have increased at an average annual rate of 4.7% between the fiscal year 1988/89 (875 revisions) and 1993/94 (1100 revisions; primary-to-revision ratio, 5:1)².

Despite the large number of revision procedures being performed, a number of fundamental questions remain unanswered. One very important factor is how to measure the severity of the failure of the primary arthroplasty.

Previously³, we used an expert-consensus-panel approach to define the dimensions that were important in measuring the severity of a failed arthroplasty, and we concluded that the one most important factor was the degree of bone loss.

Several classification systems for ascertaining bone loss from radiographs have been described in the literature^4-8. However, these measures have been largely developed without the use of scientific methods. We therefore elected to develop a measure of bone loss that can be applied to all modes of reconstruction as well as to specific types of treatment (such as femoral reconstruction with cement or bone-defect reconstruction without allografts). We tried to maintain an appropriate balance between the system being too complicated for general use and it being oversimplified and thus reducing meaningful variance in the severity of the failure of the hip arthroplasty. The purpose of this study was to assess the reliability and validity of our classification system and to report its possible applications.

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Fig. 1:: Schematic drawing of a type-II acetabulum, which has contained loss of bone stock consisting of cavitary enlargement of the acetabulum but no wall deficiency.

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Fig. 2:: Schematic drawing of a type-III acetabulum, which has uncontained loss of bone stock consisting of <50% segmental loss of the acetabulum.

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Fig. 3:: Schematic drawing of a type-IV acetabulum, which has uncontained loss of bone stock consisting of >50% segmental loss affecting both the anterior and the posterior column.

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Fig. 4:: Schematic drawing of a type-V acetabulum, which has uncontained loss of bone stock in association with pelvic discontinuity.

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Fig. 5:: Fig. 5 Schematic drawing of a type-II femur, which has contained loss of bone stock with cortical thinning. The canal is widened, but there is still an intact cortical sleeve.

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Fig. 6:: Fig. 6 Schematic drawing of a type-III femur, which has uncontained loss of bone stock that is noncircumferential or, if it is circumferential, that is proximal, <5 cm in length, and does not extend into the diaphysis.

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Fig. 7:: Fig. 7 Schematic drawing of a type-IV femur, which has uncontained circumferential loss of bone stock >5 cm in length and distal to the lesser trochanter.

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Fig. 8:: Schematic drawing of a type-V femur, which has a periprosthetic fracture with circumferential loss of bone stock proximal to the fracture.

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TABLE I: Scale for Assessment of Bone Loss in the Acetabulum

Type I	No notable loss of bone stock. Amount of bone loss is less than that which would require a revision component. There has been no migration of the primary component into the ilium, and both columns are largely intact.
Type II	Contained loss of bone stock. There is cavitary or volumetric enlargement of the acetabulum. If the cup does extend beyond the ilioischial line (protrusio), the defect can still be considered type II provided that the columns are intact.
Type III	Uncontained (segmental) loss of bone stock involving <50% of the acetabulum, primarily affecting either the anterior or the posterior column. Bone loss is considered uncontained if it is not amenable to treatment with morselized bone graft. The sum of all segments of bone loss in either the anterior or the posterior column allows 50% cup coverage by host bone (as assessed preoperatively with templates).
Type IV	Uncontained (segmental) loss of bone stock >50% of the acetabulum affecting both the anterior and the posterior column. Type IV is identical to type III except that the sum of the segmental bone loss in the columns exceeds 50%. There is no pelvic discontinuity.
Type V	Acetabular defect with contained loss of bone stock in association with pelvic discontinuity. Any pelvic discontinuity is considered a type-V defect regardless of the amount of bone loss.

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TABLE I: Scale for Assessment of Bone Loss in the Acetabulum

Type I	No notable loss of bone stock. Amount of bone loss is less than that which would require a revision component. There has been no migration of the primary component into the ilium, and both columns are largely intact.
Type II	Contained loss of bone stock. There is cavitary or volumetric enlargement of the acetabulum. If the cup does extend beyond the ilioischial line (protrusio), the defect can still be considered type II provided that the columns are intact.
Type III	Uncontained (segmental) loss of bone stock involving <50% of the acetabulum, primarily affecting either the anterior or the posterior column. Bone loss is considered uncontained if it is not amenable to treatment with morselized bone graft. The sum of all segments of bone loss in either the anterior or the posterior column allows 50% cup coverage by host bone (as assessed preoperatively with templates).
Type IV	Uncontained (segmental) loss of bone stock >50% of the acetabulum affecting both the anterior and the posterior column. Type IV is identical to type III except that the sum of the segmental bone loss in the columns exceeds 50%. There is no pelvic discontinuity.
Type V	Acetabular defect with contained loss of bone stock in association with pelvic discontinuity. Any pelvic discontinuity is considered a type-V defect regardless of the amount of bone loss.

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TABLE II: Scale for Assessment of Bone Loss in the Femur

Type I	No notable loss of bone stock. There may be erosion of the endosteal bone, but there is no involvement of the cortex.
Type II	Contained loss of bone stock with cortical thinning. The canal is widened, but there is still an intact cortical sleeve.
Type III	Uncontained loss of bone stock involving the calcar and the lesser trochanter. The defect fully perforates the cortex. It can be noncircumferential or circumferential, but it must be <5 cm in length and proximal to the diaphysis.
Type IV	Uncontained circumferential loss of bone stock >5 cm in length that extends into the diaphysis.
Type V	Periprosthetic fracture with circumferential loss of bone stock proximal to the fracture. Type V involves bone loss that would otherwise be classified as type IV except that there is a coexistent periprosthetic fracture. Fractures associated with lesser degrees of bone loss are not classified as type V and are not explicitly included in the rating system.

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TABLE II: Scale for Assessment of Bone Loss in the Femur

Type I	No notable loss of bone stock. There may be erosion of the endosteal bone, but there is no involvement of the cortex.
Type II	Contained loss of bone stock with cortical thinning. The canal is widened, but there is still an intact cortical sleeve.
Type III	Uncontained loss of bone stock involving the calcar and the lesser trochanter. The defect fully perforates the cortex. It can be noncircumferential or circumferential, but it must be <5 cm in length and proximal to the diaphysis.
Type IV	Uncontained circumferential loss of bone stock >5 cm in length that extends into the diaphysis.
Type V	Periprosthetic fracture with circumferential loss of bone stock proximal to the fracture. Type V involves bone loss that would otherwise be classified as type IV except that there is a coexistent periprosthetic fracture. Fractures associated with lesser degrees of bone loss are not classified as type V and are not explicitly included in the rating system.

Materials and Methods

Introduction | Materials and Methods | Results | Discussion | References

Measures: Two measures were devised with use of the Delphi group process^9,10: one was developed for the classification of acetabular bone loss (Table I) and the other, for the classification of femoral bone loss (Table II). With both measures, preoperative radiographs are used to predict the degree of bone loss that will be present at the time of revision surgery, after removal of the existing prostheses. The degree of bone loss from both the femur and the acetabulum is rated on a 5-point scale (type I [least severe] to type V [most severe]) (Figs. 1, 2, 3, 4, 5, 6, 7, and 8).

Reliability and validity: The reliability of the measures was tested by examining the agreement between two raters who examined the same preoperative radiographs. The validity of the measures was tested by examining the agreement between each of the two preoperative raters and a third rater who examined the bone loss intraoperatively.

Cases: Following approval by the institutional review board, all patients with a failed total hip prosthesis in need of revision surgery who presented, between July 1997 and December 1998, to the surgeon performing the intraoperative ratings were enrolled in the study, and informed consent was obtained. An anteroposterior radiograph of the pelvis and a frog-leg lateral radiograph of the affected hip were made in a standard fashion¹¹.

Raters: Three general orthopaedic surgeons attended a seminar about the new classification system. Two of the surgeons independently classified the preoperative radiographs with use of this system. The third surgeon assessed the bone loss intraoperatively, after the existing implants had been extracted. All three surgeons were blinded to the others’ ratings.

Analysis: Interobserver reliability was assessed by examining the agreement between the two preoperative raters (Rater 1 and Rater 2). Prognostic validity was assessed by examining the agreement between either Rater 1 or Rater 2 and the rater performing the intraoperative assessment. Intraobserver testing was deemed unnecessary since calculation of interobserver variation provides an upper limit of intraobserver variation; if this agreement is acceptable, the intraobserver agreement also is acceptable¹². Kappa statistics, both weighted and unweighted, were used to assess agreement. For the weighted kappas, quadratic weights were used as they are the most common coefficient employed to express agreement among multiple categorical variables¹³. Missing data were obtained by contacting the respondents again.

Assessment of sample size: The number of patients deemed necessary to test the classification was calculated to ensure that a significant correlation would be seen if the correlation were at least 0.6 with an alpha of 0.05 and a beta of 0.2. These assumptions produced an estimated sample size of thirty radiographs¹² for the femur and the same for the acetabulum.

Results

Introduction | Materials and Methods | Results | Discussion | References

Forty-five patients were enrolled in the study; both the acetabulum and the femur were rated in all of the participants. On the basis of the intraoperative findings, there were eleven type-I, eighteen type-II, seven type-III, four type-IV, and five type-V cases of acetabular bone loss. There were nine type-I, twenty-one type-II, five type-III, six type-IV, and four type-V cases of femoral bone loss.

Interobserver reliability: Kappa values for Rater 1 versus Rater 2 were 0.82 (unweighted) and 0.86 (weighted) (p < 0.0001) for the acetabular assessments and 0.6 (unweighted) and 0.77 (weighted) (p < 0.0001) for the femoral assessments.

Prognostic validity: For the acetabular assessments, kappa values were 0.84 (unweighted) and 0.9 (weighted) (p < 0.0001) for Rater 1 versus the intraoperative reference and 0.73 (unweighted) and 0.82 (weighted) (p < 0.0001) for Rater 2 versus the intraoperative reference. For the femoral assessments, kappa values were 0.82 (unweighted) and 0.9 (weighted) (p < 0.0001) for Rater 1 versus the intraoperative reference and 0.6 (unweighted) and 0.76 (weighted) (p < 0.0001) for Rater 2 versus the intraoperative reference. Disagreement was found to be randomly dispersed between Rater 1 and Rater 2.

Discussion

Introduction | Materials and Methods | Results | Discussion | References

We have described a new system for classifying bone loss in patients undergoing revision total hip arthroplasty. There was significant agreement (p < 0.0001) between the preoperative raters’ assessments (reliability) of both the femur and the acetabulum, with weighted kappa values of >0.75. There was also significant agreement (p < 0.0001) between each of the preoperative rater’s assessments and the intraoperative assessments (validity) of both the femur and the acetabulum, with weighted kappa values of >0.75. (Epidemiologists consider kappa values of 0.6 to 0.8 to be substantial and those between 0.8 and 1.0 to indicate near-perfect agreement¹².) Although additional studies are necessary, we believe that, given these findings, these measures may prove useful in future research addressing important questions regarding clinical outcomes and resource utilization related to revision arthroplasty.

A measure of bone loss has potential uses beyond research application. The management of bone loss is perhaps the most challenging aspect of revision hip surgery. Accurate preoperative assessment of such bone loss allows the surgeon to plan the procedure and to anticipate the resources (such as custom implants or allograft bone) needed intraoperatively. From the patients’ point of view, accurate preoperative assessment of bone stock will enable the surgeon to give them a more accurate outline of the postoperative rehabilitation course and may even facilitate the ability to predict the outcome of the revision surgery.

Implications for the Acetabulum

Type-I bone loss is usually limited to cement anchoring holes or focal areas of osteolysis. These defects are not associated with proximal or medial migration of the cup, and both columns are intact. The defects can be managed with a conventional cemented or uncemented acetabular component, and the cup will be largely covered by host bone^5,6,8,14-16.

Type-II bone loss is associated with either superior or medial migration of the cup. However, the columns remain intact. These findings are manifested radiographically by superior, medial, or superomedial migration of the hip center. Type-II bone loss can be managed on the acetabular side with a large uncemented cup^15,17, by creating a high hip center¹⁸, or by impaction grafting¹⁹.

Type-III bone defects involve both the dome and a column such that the new acetabular component will still have 50% contact with host bone and will most likely be uncovered superolaterally. These defects can be managed by creating a high hip center¹⁸ or by using a structural allograft^6,20 or an oblong cup²⁰.

Type IV is similar to type III except that the bone loss usually involves both columns and the sum of the segmental bone loss in the columns exceeds 50%. Type-IV defects require a structural allograft^6,20 with a protective plate or a reconstructive ring, as the new implant will have <50% contact with host bone. Another option is to use a saddle prosthesis²¹. A defect involving the medial wall without substantial involvement of the anterior or posterior column (such as occurs in rheumatoid arthritis or with a failed hemiarthroplasty) can be treated like a type-II defect in most cases because of the availability of the columns for reconstruction.

Type-V bone defects require restoration of bone stock, usually with a structural graft and a fixation device that bridges the defect, such as a reconstruction ring or a pelvic reconstruction plate. Pelvic discontinuity with minimal (contained) loss of bone stock is not common but may occur secondary to underreaming of a press-fit acetabular component. In this situation the defect is also classified as type V. The discontinuity must initially be stabilized with a plate or a ring, but a structural graft is usually not necessary.

Implications for the Femur

Type-I bone loss can be managed with a conventional cemented or uncemented femoral component^5,14,22-24.

Type-II bone loss is a contained defect, and the reconstructive options are proximal fixation with impaction grafting²⁵, a modular implant²⁶, a proximal porous coating^7,27 or distal fixation with cement²², press-fitting²⁸, or a long porous coating of the femoral component^5,29. We also classify periprosthetic fractures associated with a loose component as type-II femoral defects, provided that the proximal bone stock is of good quality. Although this category includes a large variety of bone defects, none require a structural allograft for reconstruction.

Type-III bone loss occurs in one of two patterns. The first is noncircumferential uncontained loss of bone stock (such as produced by a previous screw-hole), which can be managed with cortical strut allografts³⁰ or with bypassing of the defect with the femoral stem (as long as the remaining cortex can support a femoral prosthesis). The other pattern of type-III defect is proximal circumferential loss of bone stock of <5 cm in length involving the calcar. This defect can be reconstructed with a calcar-replacing prosthesis^30,31.

Type-IV bone loss can be managed with a structural allograft or a tumor implant^31,32.

Type-V bone loss includes periprosthetic fractures with circumferential loss of bone stock proximal to the fracture. These defects require a structural femoral allograft with fixation of the fracture by the femoral implant stem as well as an osteotomy (step-cut or oblique) at the allograft-host junction³². The other option is to use a tumor prosthesis³¹.

In conclusion, we developed a system to measure bone loss on standard radiographs made before revision of a failed total hip arthroplasty. That system was shown to be a reliable as well as a valid predictor of the bone loss that will be found intraoperatively. We believe that this system may be useful both for future research involving revision total hip arthroplasty and for preoperative planning in the clinical setting.

Note: The authors are grateful to the panel of experts for their involvement in this project over the last five years. They also thank Grzeogrz Jaroszynski, MD, FRCSC, and Ian Woodgate, MB, BS, FRACS, for their contributions.

References

Introduction | Materials and Methods | Results | Discussion | References

National Center for Health Statistics. . Am Acad Am Assoc Orthop Surgeons Bull., 1999.47: 14, 4714 1999

Coyte PC; Young W; and Williams JI: Devolution of hip and knee replacement surgery?. Can J Surg,1996.39: 373-8, 39373 1996 [PubMed]

Saleh KJ; Holtzman J; Gafni A; Saleh L; Jaroszynski G; Wong P; Woodgate I; Davis A; and Gross AE: Development, test reliability and validation of a classification for revision hip arthroplasty. J Orthop Res,2001.19: 50-6, 1950 2001 [PubMed][CrossRef]

D’Antonio JA; Capello WN; Borden LS; Bargar WL; Bierbaum BF; Boettcher WG; Steinberg ME; Stulberg SD; and Wedge JH: Classification and management of acetabular abnormalities in total hip arthroplasty. Clin Orthop,1989.243: 126-37, 243126 1989 [PubMed]

Engh CA, and Glassman AH: Cementless revision of failed total hip replacement: an update. Instr Course Lect,1991.40: 189-97, 40189 1991

Gross AE; Allan DG; Catre M; Garbuz DS; and Stockley I: Bone grafts in hip replacement surgery. The pelvic side. Orthop Clin North Am,1993.24: 679-95, 24679 1993 [PubMed]

Gustilo RB, and Pasternak HS: Revision total hip arthroplasty with titanium ingrowth prosthesis and bone grafting for failed cemented femoral component loosening. Clin Orthop,1988.235: 111-9, 235111 1988 [PubMed]

Paprosky WG; Perona PG; and Lawrence JM: Acetabular defect classification and surgical reconstruction in revision arthroplasty: a 6-year follow-up evaluation. J Arthroplasty,1994.9: 33-44, 933 1994 [PubMed][CrossRef]

Gustafson DH; Fryback DG; Rose JH; Yick V; Prokop CT; Detmer DE; and Moore J: A decision theoretic methodology for severity index development. Med Decis Making,1986.6: 27-35, 627 1986 [PubMed][CrossRef]

Gustafson DH; Shukla R; Delbecq AL; and et al: Comparative study of the differences in subjective likelihood estimates made by individuals, groups, Delphi groups, and nominal groups. Organ Behave Hum Perform,1973.9: 380-91, 9380 1973

Brand RA; Yoder SA; and Pedersen DR: Interobserver variability in interpreting radiographic lucencies about total hip reconstructions. Clin Orthop,1985.192: 237-9, 192237 1985 [PubMed]

Norman GR, Streiner DL.Biostatistics: the bare essentials. St. Louis: Mosby; 1994

Soeken KL, and Prescott PA: Issues in the use of kappa to estimate reliability. Med Care,1986.23: 733-41, 23733 1986 [CrossRef]

Engh CA, and Glassman AH: Cementless revision of failed total hip replacement. Orthop Rev,1990.19(suppl): 23-8, 19(suppl)23 1990

Padgett DE; Kull L; Rosenberg A; Sumner DR; and Galante JO: Revision of the acetabular component without cement after total hip arthroplasty. Three to six-year follow-up. J Bone Joint Surg Am,1993.75: 663-73, 75663 1993 [PubMed]

Raut VV; Siney PD; and Wroblewski BM: Revision of the acetabular component of a total hip arthroplasty with cement in young patients without rheumatoid arthritis. J Bone Joint Surg Am,1996.78: 1853-6, 781853 1996 [PubMed]

Tanzer M; Drucker D; Jasty M; McDonald M; and Harris WH: Revision of the acetabular components with an uncemented Harris-Galante porous-coated prosthesis. J Bone Joint Surg Am,1994.74: 987-94, 74987 1994

Russotti GM, and Harris WH: Proximal placement of the acetabular component in total hip arthroplasty. A long-term follow-up study. J Bone Joint Surg Am,1991.73: 587-92, 73587 1991 [PubMed]

Slooff TJ; Schimmel JW; and Buma P: Cemented fixation with bone grafts. Orthop Clin North Am,1993.24: 667-77, 24667 1993 [PubMed]

Saleh KJ; Jaroszynski G; Woodgate I; Saleh L; and Gross AE: Revision total hip arthroplasty with the use of structural acetabular allograft and reconstruction ring: a case series with a 10-year average follow-up. J Arthroplasty,2000.15: 951-8, 15951 2000 [PubMed][CrossRef]

van der Lei B; Hoekstra HJ; Veth RP; Ham SJ; Oldhoff J; and Schraffordt Koops H: The use of the saddle prosthesis for reconstruction of the hip joint after tumor resection of the pelvis. J Surg Oncol,1992.50: 216-9, 50216 1992 [PubMed][CrossRef]

Estok DM, and Harris WH: Long-term results of cemented femoral revision surgery using second-generation techniques. An average 11.7-year follow-up evaluation. Clin Orthop,1994.299: 190-202, 299190 1994 [PubMed]

Raut VV; Siney PD; and Wroblewski BM: Outcome of revision for mechanical stem failure using the cemented Charnley’s stem. A study of 399 cases. J Arthroplasty,1996.11: 405-10, 11405 1996 [PubMed][CrossRef]

Raut VV; Siney PD; and Wroblewski BM: Revision for aseptic stem loosening using the cemented Charnley prosthesis. A review of 351 hips. J Bone Joint Surg Br,1995.77: 23-7, 7723 1995 [PubMed]

Gie GA; Linder L; Ling RS; Simon JP; Slooff TJ; and Timperley AJ: Contained morselized allograft in revision total hip arthroplasty. Surgical technique. Orthop Clin North Am,1993.24: 717-25, 24717 1993 [PubMed]

Cameron HU: The two- to six-year results with a proximally modular noncemented total hip replacement used in hip revisions. Clin Orthop,1994.298: 47-53, 29847 1994 [PubMed]

Malkani AL; Lewallen DG; Cabanela ME; and Wallrichs SL: Femoral component revision using an uncemented, proximally coated, long-stem prosthesis. J Arthroplasty,1996.11: 411-8, 11411 1996 [PubMed][CrossRef]

Wagner H, Wagner M.Cortical stem fixation for cementless hip prosthesis for primary implantation and revisions. In: Morsher E, editor. Endoprosthetics. New York: Springer; 1995. p 258-70

Engh CA; Massin P; and Suthers KE: Roentgenographic assessment of the biologic fixation of porous-surfaced femoral components. Clin Orthop,1989.257: 107-28, 257107 1989

Head WC; Wagner RA; Emerson RH; and Malinin TI: Revision total hip arthroplasty in the deficient femur with a proximal load-bearing prosthesis. Clin Orthop,1994.298: 119-26, 298119 1994 [PubMed]

Malkani AL; Sim FH; and Chao EY: Custom-made segmental femoral replacement prosthesis in revision total hip arthroplasty. Orthop Clin North Am,1993.24: 727-33, 24727 1993 [PubMed]

Gross AE; Allan DG; Lavoie GJ; and Oakeshott RD: Revision arthroplasty of the proximal femur using allograft bone. Orthop Clin North Am,1993.24: 705-15, 24705 1993 [PubMed]

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Fig. 1:: Schematic drawing of a type-II acetabulum, which has contained loss of bone stock consisting of cavitary enlargement of the acetabulum but no wall deficiency.

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Fig. 2:: Schematic drawing of a type-III acetabulum, which has uncontained loss of bone stock consisting of <50% segmental loss of the acetabulum.

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Fig. 3:: Schematic drawing of a type-IV acetabulum, which has uncontained loss of bone stock consisting of >50% segmental loss affecting both the anterior and the posterior column.

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Fig. 4:: Schematic drawing of a type-V acetabulum, which has uncontained loss of bone stock in association with pelvic discontinuity.

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Fig. 5:: Fig. 5 Schematic drawing of a type-II femur, which has contained loss of bone stock with cortical thinning. The canal is widened, but there is still an intact cortical sleeve.

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Fig. 7:: Fig. 7 Schematic drawing of a type-IV femur, which has uncontained circumferential loss of bone stock >5 cm in length and distal to the lesser trochanter.

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Fig. 8:: Schematic drawing of a type-V femur, which has a periprosthetic fracture with circumferential loss of bone stock proximal to the fracture.

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TABLE I: Scale for Assessment of Bone Loss in the Acetabulum

Type I	No notable loss of bone stock. Amount of bone loss is less than that which would require a revision component. There has been no migration of the primary component into the ilium, and both columns are largely intact.
Type II	Contained loss of bone stock. There is cavitary or volumetric enlargement of the acetabulum. If the cup does extend beyond the ilioischial line (protrusio), the defect can still be considered type II provided that the columns are intact.
Type III	Uncontained (segmental) loss of bone stock involving <50% of the acetabulum, primarily affecting either the anterior or the posterior column. Bone loss is considered uncontained if it is not amenable to treatment with morselized bone graft. The sum of all segments of bone loss in either the anterior or the posterior column allows 50% cup coverage by host bone (as assessed preoperatively with templates).
Type IV	Uncontained (segmental) loss of bone stock >50% of the acetabulum affecting both the anterior and the posterior column. Type IV is identical to type III except that the sum of the segmental bone loss in the columns exceeds 50%. There is no pelvic discontinuity.
Type V	Acetabular defect with contained loss of bone stock in association with pelvic discontinuity. Any pelvic discontinuity is considered a type-V defect regardless of the amount of bone loss.

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TABLE I: Scale for Assessment of Bone Loss in the Acetabulum

Type I	No notable loss of bone stock. Amount of bone loss is less than that which would require a revision component. There has been no migration of the primary component into the ilium, and both columns are largely intact.
Type II	Contained loss of bone stock. There is cavitary or volumetric enlargement of the acetabulum. If the cup does extend beyond the ilioischial line (protrusio), the defect can still be considered type II provided that the columns are intact.
Type III	Uncontained (segmental) loss of bone stock involving <50% of the acetabulum, primarily affecting either the anterior or the posterior column. Bone loss is considered uncontained if it is not amenable to treatment with morselized bone graft. The sum of all segments of bone loss in either the anterior or the posterior column allows 50% cup coverage by host bone (as assessed preoperatively with templates).
Type IV	Uncontained (segmental) loss of bone stock >50% of the acetabulum affecting both the anterior and the posterior column. Type IV is identical to type III except that the sum of the segmental bone loss in the columns exceeds 50%. There is no pelvic discontinuity.
Type V	Acetabular defect with contained loss of bone stock in association with pelvic discontinuity. Any pelvic discontinuity is considered a type-V defect regardless of the amount of bone loss.

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TABLE II: Scale for Assessment of Bone Loss in the Femur

Type I	No notable loss of bone stock. There may be erosion of the endosteal bone, but there is no involvement of the cortex.
Type II	Contained loss of bone stock with cortical thinning. The canal is widened, but there is still an intact cortical sleeve.
Type III	Uncontained loss of bone stock involving the calcar and the lesser trochanter. The defect fully perforates the cortex. It can be noncircumferential or circumferential, but it must be <5 cm in length and proximal to the diaphysis.
Type IV	Uncontained circumferential loss of bone stock >5 cm in length that extends into the diaphysis.
Type V	Periprosthetic fracture with circumferential loss of bone stock proximal to the fracture. Type V involves bone loss that would otherwise be classified as type IV except that there is a coexistent periprosthetic fracture. Fractures associated with lesser degrees of bone loss are not classified as type V and are not explicitly included in the rating system.

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TABLE II: Scale for Assessment of Bone Loss in the Femur

Type I	No notable loss of bone stock. There may be erosion of the endosteal bone, but there is no involvement of the cortex.
Type II	Contained loss of bone stock with cortical thinning. The canal is widened, but there is still an intact cortical sleeve.
Type III	Uncontained loss of bone stock involving the calcar and the lesser trochanter. The defect fully perforates the cortex. It can be noncircumferential or circumferential, but it must be <5 cm in length and proximal to the diaphysis.
Type IV	Uncontained circumferential loss of bone stock >5 cm in length that extends into the diaphysis.
Type V	Periprosthetic fracture with circumferential loss of bone stock proximal to the fracture. Type V involves bone loss that would otherwise be classified as type IV except that there is a coexistent periprosthetic fracture. Fractures associated with lesser degrees of bone loss are not classified as type V and are not explicitly included in the rating system.