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 Table of Contents  
ORIGINAL ARTICLE
Year : 2015  |  Volume : 28  |  Issue : 4  |  Page : 971-977

Intraoperative periprosthetic hip fractures


Department of Orthopaedics and Trauma, Shebeen El-Kom Medical School, Menoufia University, Shebeen El-Kom, Menoufia Governorate, Egypt

Date of Submission28-Dec-2014
Date of Acceptance19-Apr-2015
Date of Web Publication12-Jan-2016

Correspondence Address:
Ahmed E. E. Ahmed
6th Floor, No. 7, Dr Lasheen St. off King Faysal St., Haram, Giza, 12814
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/1110-2098.173691

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  Abstract 

Purpose
The aim of this work was to study the risk factors, clinical results, particularly the functional outcome, and radiological results for intraoperative periprosthetic fractures (PPFs) around hip arthroplasties through a retrospective analysis.
Materials and methods
We conducted a retrospective study based on hospital records. Patients with intraoperative PPFs around hip arthroplasties who underwent follow-up for at least 9 months were enrolled in the study. For each patient, preoperative and intraoperative risk factors were analyzed; the functional outcome in terms of the Harris hip score was compared before fracture and at the last follow-up.
Results
Fifteen cases were enrolled in this study. Six male and nine female patients were included with a mean ± SD age of 57.2 ± 8.5 years. A mean follow-up of 15.2 months was achieved. The average Harris hip score at the last follow-up was 85.7 points. All cases obtained primary bony union. The mean time from surgery to bony union was 8.3 months, ranging 3-12 months.
Conclusion
Female patients are at a higher risk of intraoperative PPF; in addition, significant femoral deformity and osteopenia are estimated risk factors. Cortical perforations and bone defects along with previously existing osteotomies are the other risk factors. Revision surgeries, cementless components, straight long stem, and vigorous manipulation of the femur are the surgery-related risk factors detected. Component stability is the most important factor for intraoperative decision-making. Extended trochanteric osteotomy is a safe and useful procedure, especially when using long straight stems. In addition, the use of supplementary cerclage fixation of fracture fragments for Vancouver B fractures yields better results.

Keywords: arthroplasty, periprosthetic fractures, risk factors, Vancouver


How to cite this article:
ElSerwi BM, Hassan BZ, Ahmed AE. Intraoperative periprosthetic hip fractures. Menoufia Med J 2015;28:971-7

How to cite this URL:
ElSerwi BM, Hassan BZ, Ahmed AE. Intraoperative periprosthetic hip fractures. Menoufia Med J [serial online] 2015 [cited 2020 Sep 21];28:971-7. Available from: http://www.mmj.eg.net/text.asp?2015/28/4/971/173691


  Introduction Top


First mentions of periprosthetic fractures (PPFs) were published in the 70s by McElfresh, and later in the 80s and the 90s of the last century [1] . Since then, the incidence has increased steadily as the indications for total hip arthroplasty (THA) have broadened and the life expectancy of the population has increased.

Haidukewych et al. [2] reported an intraoperative acetabular fracture during 0.4% of 5359 cases performed with a cementless acetabular component. Berry [3] reported an incidence of 0.3% in 20 859 primary cemented THAs and 5.4% in 3121 cementless THAs. They also reported an intraoperative fracture rate of 3.6% in cemented and 20.9% in cementless revision THAs.

The Vancouver classification is the most widely used system for the classification of PPFs. It takes into account the three important factors in management: the site of the fracture, the stability of the femoral component, and the quality of the surrounding femoral bone stock [4] .

Many different treatment options have been described in the literature and no single treatment has been shown to be the gold standard; also, risk factors have received little attention in the literature.

The purpose of this work was to study the risk factors, clinical results, particularly the functional outcome, and radiological results for intraoperative PPFs around hip arthroplasties through a retrospective analysis.


  Materials and methods Top


Our study was a retrospective analysis based on radiographs and medical records of all patients with a discharge diagnosis of intraoperative PPF at the Menoufia University Hospital during the period from January 2007 to December 2010. Six male and nine female patients were included, with a mean ± SD age of 57.2 ± 8.5 years (range 50-65 years). A mean follow-up of 15.2 months (range 9-24 months) was achieved. The study was approved by the Ethics Committee of our institute.

Patient characteristics

Patients' age, sex, reason for hip arthroplasty, type of hip arthroplasty, cause of periprosthetic femoral fracture, and postoperative follow-up period were recorded. Preoperative radiographs were examined for bone defects and bone quality. In addition, for revision cases, radiographs were reviewed to assess the bone stock and the position and the status of the stem.

Operative data

Treatment methods and clinical results were investigated by reviewing the medical charts with particular note of any sign of missed fractures. All procedures were performed using the posterolateral approach to the hip joint with the patient in the lateral decubitus position on a standard radiolucent operating table. Fracture was defined as any fissure or fracture of the femur that was noticed intraoperatively. Fractures were identified and treated intraoperatively.

Treatment methods were either conservative or surgical. Surgical treatments comprised prophylactic cerclage, osteosynthesis, or intraoperative revision with a long-stem prosthesis. One patient with 'type A' fracture was managed conservatively. Cerclage fixation was used for five patients. Plate osteosynthesis was utilized for five patients with femoral fractures and one case of acetabular fractures. Long-stem prosthesis was used for three patients.

Radiological assessment

The fractures were checked by reviewing radiographs, and also classified according to the Vancouver classification. A diagnosis of loosening was necessary for the Vancouver classification. Fractures disrupting the three-point fixation of the stem were diagnosed as leading to a loose stem. Bony union, loss of reduction, malunion, and implant-related complications were assessed.

Radiographic evaluation at follow-up included an anteroposterior view of the pelvis and both hips, and a frog-leg lateral of the operative hip for obvious subsidence, failure of ingrowth, or extensive mechanical failure. Lack of subjective subsidence or failure of ingrowth was assumed to be indicative of fracture healing.

Patient charts and postoperative radiographs were reviewed by an independent observer who did not participate in any of the operative procedures.

Union was defined as the ability of patients to bear weight without pain at the fracture site and the presence of evidence of callus bridging across the fracture on both the anteroposterior and the lateral radiographs.

Malunion was defined as a greater than 2 cm shortening, a greater than 5° varus/valgus malalignment, or more than 10° of coronal plane malalignment.

Nonunion was defined as a painful fracture that after 6 months of follow-up did not show evidence of healing on three consecutive radiographs taken at 1-month intervals.

Metalwork failure was defined as a plate or screw fracture or the pull out of screws.

Loosening comprised fractures disrupting the three-point fixation of the stem that were diagnosed as leading to a loose stem.

Clinical outcome

The postoperative mobility status compared with the preoperative mobility status, hip range of movements at the last follow-up, and the incidence of complications, namely refracture, nonunion, and failure of metalwork were assessed for all patients. Harris hip score (HHS) was performed by an independent physician preoperatively and postoperatively, which consisted of eight questions and a physical examination. Scores from each section were simply added together to make a maximum possible score of 100 (indicating the best possible outcome).

Statistical analysis

Univariable logistic regression was used to assess the association between intraoperative PPF and measured covariates. Data were recorded and analyzed in Excel spreadsheets. A direct comparison between the patients included was not attempted owing to their different preoperative situations, types of fractures, and management.


  Results Top


Seven cases of primary THA and eight cases of revision THA were included. Three of the eight revision cases had revision due to septic loosening, whereas five had revision due to aseptic loosening. One patient with intraoperative acetabular PPF was included. Femoral PPFs were classified by the Vancouver classification into two cases of type A1, one case of type A2, one case of type B1, three cases of type B2, three cases of type B3, two cases of type C2, and two cases of type C3.

Among the study group, there was a considerably higher percentage of PPF among female patients (60%) compared with male patients (40%). In addition, interestingly, there was a higher risk of PPF when the left hip was operated (73.3%). More patients developed PPF while receiving a cementless stem (66.7%). Five of the eight revision cases had revision due to aseptic loosening (33.3%) compared with three patients (20%) due to septic loosening. Preoperatively, three patients were recognized to have acetabular bone deficiency with variable degrees; also, five patients had femoral bone deficiencies ([Table 1]).
Table 1 Patient demographics


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Concerning the timing of fracture occurrence, three fractures occurred during cement removal, four during canal preparation, three fractures during stem insertion, and three fractures during the reduction of the final implant. Two fractures were missed intraoperatively ([Table 2]).
Table 2 The evaluation of risk factors for intraoperative periprosthetic fracture during hip surgery: a univariate analysis


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In A fractures, out of three patients, two of them were treated by cerclage fixation and one was missed intraoperatively and managed conservatively. Patients achieved good results with a mean score of 88.77 according to HHS (±SD = 5.6), with a mean time to consolidation of 6 months.

In B1 fractures, one patient treated by cerclage wire fixation achieved 88.1 points on HHS; the time to consolidation was 7 months. In B2 fractures, out of three patients, two of them were treated with intraoperative stem lengthening supplemented with cerclage wiring. According to HHS, they achieved a good result of a mean of 84.4 ± SD 1.85 points, with a mean time to consolidation of 8.5 months. One of the B2 patients was managed with cerclage wire fixation only due to the unavailability of a long stem intraoperatively. Although this patient achieved consolidation after 10 months, HHS was 74.6, indicating fair results. In B3 fractures, out of three patients, two of them were managed with plate osteosynthesis, achieving a mean HHS of 89.55 points and a mean time to consolidation of 8 months. One patient with a missed B3 fracture was revised a month later with a long stem augmented with cerclage wiring, achieving 89.7 points on HHS. The time to consolidation was 10 months ([Figure 1] and [Figure 2]).
Figure 1 An intraoperative photograph after ORIF of the femoral periprosthetic fracture (PPF) utilizing a 12-hole-broad dynamic compression plate (DCP) for osteosynthesis (case 2).

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Figure 2 A postoperative radiograph shows the utilization of a long femoral stem along with a lateral locked plate for the management of a complex B3 fracture (case 4).

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In C2 fractures, out of two patients, one was managed with cerclage wiring, achieving an HHS of 77 points and the time to consolidation was 11 months. The other patient was managed with plate osteosynthesis achieving 87.6 points on HHS, and the time to consolidation was 8 months. In C3 fractures, two patients were managed with plate osteosynthesis, achieving a mean of 84.95 ± SD 1.85 points. The mean time to consolidation was 9 months ([Figure 3]). The acetabular fracture (case 3) was managed with ORIF using a reconstruction plate fixation ([Table 3]).
Table 3 An overall view of patients' characteristics and outcomes


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Figure 3 ORIF for type C3 intraoperative fractures using a broad DCP and screw construct. (a) An immediate postoperative radiograph; (b) The 12-month follow-up radiograph (case 2).

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All cases obtained primary bony union. The mean time from surgery to bony union was 8.3 months, ranging from 3 to 12 months. There were no cases with either loss of reduction and malunion, or implant-related complications. The average HHS at the last follow-up was 85.7 points, with a range of 74.6-94.7 points.


  Discussion Top


As with most complications, an understanding of risk factors can assist the surgeon in preventing the complication of interest. [Table 4] shows the estimated risk factors in our study cases.
Table 4 Estimated risk factors for the study cases


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The probability of PPF in women was almost two to three times greater than that in men in our study. Our findings are in accordance with studies that emphasize the higher incidence of such complications in women [5],[6],[7] . There were studies that contradicted these results, but they were limited to postoperative fractures only [8] . However, one has to keep in mind that the influence of the sex on the fracture risk is probably multifactorial. One of them might be poor bone quality related to osteoporosis, frequently in women. The higher incidence of femoral fractures in women and the higher prevalence of secondary osteoarthritis contribute to a higher percentage of women undergoing THA [9] .

Another important risk factor for PFF is the occurrence of cortical perforations and bone defects that may occur after the removal of the implant used for stabilization of the primary fracture, or in the fracture line itself [10],[11],[12] . This was a predisposing factors in two of our cases. One of them had undergone a failed trial of fixation of an intertrochanteric fracture, which was later converted to THA. The other case was undergoing revision after a failed cerclage wiring for PPF during the primary procedure.

The periprosthetic osteolysis shown in almost all revision cases in this study is another local risk factor associated with PPF and it has become increasingly more frequent [4] .

Several elements of the surgical process may contribute to the occurrence of intraoperative PPF. The fixation method of either the femoral stem or the acetabular cup is a relative risk factor. The data collected from this study revealed that the PPFs complicated uncemented THA procedures two times more than cemented THAs. These findings are supported by other studies [13] .

The operative technique for an uncemented THA requires more aggressive reaming of the medullary canal and tight fixation of the stem, which allows for bone ingrowth at the bone/implant interface [14] .

Revision THA has a high incidence of intraoperative PPFs. In this study, eight cases were found to have intraoperative PPF during revision THA. This can be explained by the increasing number of revision procedures in older patients, which introduces the effect of bone defects and cortical defects associated with component or cement removal as well as the presence of stress-raisers related to previous procedures. Under-reaming of the femoral cortex, the use of a large-diameter femoral stem, and a low ratio between the diameters of the femoral cortex and canal have been associated with a greater risk of intraoperative fracture [15],[16] .

Among the cases in our study, three intraoperative PPFs occurred while using revision cementless long straight stems (cases 1, 4, 14). The explanation for this finding lies in the fact that the very design of the anatomic stem implies that it is well matched to the proximal femur shape unlike straight stems. The use of extended trochanteric osteotomy can decrease the incidence of such fractures with long straight stems. Lerch et al. [17] concluded in their study that the extended trochanteric osteotomy should be discussed in special cases to prevent femoral fractures during stem and cement removal.

In the whole study group, any surgery of the left hip was related to a 2.75 times greater risk of PFF. Nowak and colleagues found that the left hip required revision surgery more often, and during the procedure, the incidence of fracture was more likely to happen. One possible explanation is related to the domination of the right side among most people, both in surgeons and in patients. The left inferior extremity, as a nondominant one, results in worse quality of the bone and may lead to a fracture. In contrast, if the surgeon is right-handed, he/she makes the external rotation in the glenohumeral joint (forehand stroke) while driving the stem into the bone on the left side. Stem fixation in the left hip is more comfortable. A surgeon with a forehand stroke can transfer too much of kinetic energy into a tool [18] .

Previous studies [19],[20],[21] demonstrated that an intraoperative fracture occurs with exposure, during cement removal, or while inserting the new component. The most common instance during revision surgery for an intraoperative fracture to occur, with cementless implants, is while obtaining a tight 'scratch fit' at implant insertion. This can also be concluded from the results of this study, where 53.4% of the femoral PPF occurred during femoral canal preparation and stem insertion.

The goals of treatment of periprosthetic femoral fractures include a united fracture in acceptable alignment, a stable prosthesis, and early mobilization, with rapid return to prefracture function [22] .

Our group of type A fractures was managed either nonoperatively (33.3%) or by cerclage wiring, plate osteosynthesis, or a long stem, with good results that are in line with the ones reported in the literature [23],[24] .

The subdivisions of type B fractures are very important for decision making regarding management. For the management of B1 fractures, various plate devices and cerclage cables, either alone or combined with bone grafts, can be used [25] . Patients in this study obtained good results with these techniques.

In type B2 fractures, the femoral stem is unstable; thus, a long stem is the treatment of choice. In our cases, surgeons preferred supplementary cerclage fixation of fracture fragments ([Figure 4]), as recommended in the literature [25],[26] . Only one case of B2 fracture was managed with cerclage wires only due to an unavailable long stem intraoperatively and the query of stem stability; this highlights the ongoing debate regarding the differentiation of stable against unstable stems in type B fractures [26] .
Figure 4 Anteroposterior radiograph follow-up after revision with a long stem and ORIF with a long locked plate for the periprosthetic fracture (PPF) augmented with multiple cerclage wires showing adequate consolidation.

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Type B3 fractures are one of the most challenging fracture patterns with the urge to obtain adequate distal fixation of the implant to provide axial and rotational stability. Bone grafting is usually recommended in this type of fracture, but a recent study advocates treatment by revision arthroplasty and internal fixation, without bone grafting [27] .

Vancouver C fractures can sometimes be treated as a standard femoral fracture using plate osteosynthesis bicortically fixed above and below the line of fracture. If the plate is in the proximal part and extends up to the stem of the cemented prosthesis, it is preferable to fix the plate with cerclage to prevent damage to the cement mantle and release of the prosthesis [28] .

Little attention has been paid in the literature to the treatment and the outcome of intraoperative acetabular PPFs. Della Valle et al. [29] offered recommendations for the treatment of intraoperative acetabular fractures. The single case with intraoperative PPF included a postcolumn fracture treated intraoperatively with plate fixation [30] .

At last, there are several limitations inherent to this type of study including different biases towards treatment over the study period and the limited number of study patients.


  Conclusion Top


Female patients are at a higher risk of intraoperative PPF; more importantly, certain disease processes are associated with significant femoral deformity and osteopenia. Cortical perforations and bone defects that may occur after the removal of the implant used for the stabilization of the primary fracture, or in the fracture line itself, along with previously existing osteotomies are other risk factors. Revision surgeries, cementless components, straight long stem, and vigorous manipulation of the femur are the surgery-related risk factors detected.

In the event of an intraoperative fracture, direct visualization and radiographic analysis will help guide the classification and the treatment. Component stability is the most important factor for intraoperative decision-making. Extended trochanteric osteotomy is a safe and useful procedure, especially when using long straight stems. In addition, the use of supplementary cerclage fixation of fracture fragments for Vancouver B fractures yields better results.


  Acknowledgements Top


The authors did not receive any outside funding or grants in support of their research or for the preparation of this work. Neither they nor any member of their immediate families received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

1.
Pleva L, Se M, Madeja R. Our experiences with the treatment of periprosthetic fractures of femur. Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub 2004; 148 :75-79.  Back to cited text no. 1
    
2.
Haidukewych G, Jacofsky D, Hanssen A, Lewallen D. Intraoperative fractures of the acetabulum during primary total hip arthroplasty. J Bone Jt Surg Amesterdam 2006; 88 :1952-1956.  Back to cited text no. 2
    
3.
Berry DJ. Epidemiology: hip and knee. Orthop Clin North Am 1999; 30 : 183-190.  Back to cited text no. 3
    
4.
Duncan CP, Masri BA. Fractures of the femur after hip replacement. Instr Course Lect 1995; 44 :293-304.  Back to cited text no. 4
    
5.
Tower SS, Beals RK. Fractures of the femur after hip replacement: the Oregon experience. Orthop Clin North Am 1999; 30 :235-247.  Back to cited text no. 5
    
6.
Schwartz JJTJ, Mayer JJG, Engh CCA. Femoral fracture during noncemented total hip arthroplasty. J Bone Jt Surg Am 1989; 71 :1135-1142.  Back to cited text no. 6
    
7.
Moroni A, Faldini C, Piras F, Giannini S. Risk factors for intraoperative femoral fractures during total hip replacement. Ann Chir Gynaecol 2000; 89 :113-118.  Back to cited text no. 7
    
8.
Sarvilinna R, Huhtala HS, Sovelius RT, Halonen PJ, Nevalainen JK, Pajamain KJ. Factors predisposing to periprosthetic fracture after hip arthroplasty: a case (n = 31)-control study. Acta Orthop Scand 2004; 75 :16-20.  Back to cited text no. 8
    
9.
Franklin J, Malchau H. Risk factors for periprosthetic femoral fracture. Injury 2007; 38 :655-660.  Back to cited text no. 9
    
10.
Kelley SS. Periprosthetic femoral fractures. J Am Acad Orthop Surg 1994; 2 :164-172.  Back to cited text no. 10
    
11.
Huo M, Jay P, Buly R. Total hip replacement following prior surgeries. In: Bono JV, McCarthy JC, Thornhill ThS, Turner RH. Revision total hip arthroplasty. New York, NY: Springer Verlag; 1999. p. 477-491.  Back to cited text no. 11
    
12.
Talab YA, States JD, Evarts CM. Femoral shaft perforation: a complication of total hip reconstruction. Clin Orthop Relat Res 1979; 141:158-165.  Back to cited text no. 12
[PUBMED]    
13.
Johansson JE, McBroom R, Barrington TW, Hunter GA. Fracture of the ipsilateral femur in patients wih total hip replacement. J Bone Joint Surg Am 1981; 63 :1435-1442.  Back to cited text no. 13
[PUBMED]    
14.
Cameron HU. Intraoperative hip fractures: ruining your day. J Arthroplasty 2004; 19 (Suppl 1): 99-103.  Back to cited text no. 14
    
15.
Lindahl H. Epidemiology of periprosthetic femur fracture around a total hip arthroplasty. Injury 2007; 38 :651-654.  Back to cited text no. 15
    
16.
Meek RM, Garbuz DS, Masri BA, Greidanus NV, Duncan CP. Intraoperative fracture of the femur in revision total hip arthroplasty with a diaphyseal fitting stem. J Bone Joint Surg Am 2004; 86-A : 480-485.  Back to cited text no. 16
    
17.
Lerch M, von Lewinski G, Windhagen H, Thorey F. Revision of total hip arthroplasty: clinical outcome of extended trochanteric osteotomy and intraoperative femoral fracture. Technol Health Care 2008; 16 :293-300.  Back to cited text no. 17
    
18.
Nowak M, Kusz D, Wojciechowski P, Wilk R. Risk factors for intraoperative periprosthetic femoral fractures during the total hip arthroplasty. Pol Orthop Traumatol 2012; 77 :59-64.  Back to cited text no. 18
    
19.
Egan KJ, Di Cesare PE. Intraoperative complications of revision hip arthroplasty using a fully porous-coated straight cobalt-chrome femoral stem. J Arthroplasty 1995; V Suppl :45-51.  Back to cited text no. 19
    
20.
Lawrence JM, Engh CA, Macalino GE, Lauro GR. Outcome of revision hip arthroplasty done without cement. J Bone Joint Surg Am 1994; 76 : 965-973.  Back to cited text no. 20
    
21.
Zalzal P, Gandhi R, Petruccelli D, Winemaker MJ, de Beer J. Fractures at the tip of long-stem prostheses used for revision hip arthroplasty. J Arthroplasty 2003; 18 :741-745.  Back to cited text no. 21
    
22.
Garbuz DS, Masri BA, Duncan CP. Periprosthetic fractures of the femur: principles of prevention and management. Instr Course Lect 1998; 47 :237-242.  Back to cited text no. 22
    
23.
Pop T, Gergely I, Roman C, Nagy O. Periprosthetic femoral fractures after total hip arthroplasty. ASORIS 2011; 4 :53-60.  Back to cited text no. 23
    
24.
Pritchett JW. Fracture of the greater trochanter after hip replacement. Clin Orthop Relat Res 2001; 390 :221-226.  Back to cited text no. 24
    
25.
Schwarzkopf R, Oni JK, Marwin SE. Total hip arthroplasty periprosthetic femoral fractures: a review of classification and current treatment. Bull Hosp Jt Dis (2013) 2013; 71 :68-78.  Back to cited text no. 25
    
26.
Marsland D, Mears SC. A review of periprosthetic femoral fractures associated with total hip arthroplasty. Geriatr Orthop Surg Rehabil 2012; 3 :107-120.  Back to cited text no. 26
    
27.
Wang JQ, Gao YS, Mei J, Rao ZT, Wang SQ. Revision hip arthroplasty as a treatment of Vancouver B3 periprosthetic femoral fractures without bone grafting. Indian J Orthop 2013; 47 :449-453.  Back to cited text no. 27
    
28.
Parvizi J, Rapuri VR, Purtill JJ, Sharkey PF, Rothman RH, Hozack WJ. Treatment protocol for proximal femoral periprosthetic fractures. J Bone Joint Surg Am 2004; 86-A: Suppl 2 :8-16.  Back to cited text no. 28
    
29.
Della Valle CJ, Chang D, Sporer S, Berger RA, Rosenberg AG, Paprosky WG. High failure rate of a constrained acetabular liner in revision total hip arthroplasty. J Arthroplasty 2005; 20(Suppl 3) :103-107.  Back to cited text no. 29
    
30.
Masri BA, Meek RMD, Duncan CP. Periprosthetic fractures evaluation and treatment. Clin Orthop Relat Res 2004; 42 :80-95.  Back to cited text no. 30
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]



 

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