Periprosthetic fractures can be discussed in many formats. In this article, epidemiology, classification, and treatment are divided into the following three categories of periprosthetic fracture: intraoperative fractures detected at the time of surgery; intraoperative fractures undetected at the time of surgery, but detected postoperatively; and postoperative fractures occurring late after the arthroplasty procedure.
Intraoperative fractures that are detected at the time of surgery have been reported in cementless femoral implantations, from 1% by Berry1 to 3% reported by Schwartz et al,2 and up to as high as 5.4%.1 The incidence is lower in primary implants using cement.1,3
Intraoperative femoral fractures commonly occur in the revision setting.1,4 In revision femurs, the incidence of fracture was higher in cementless components (21%) than protheses inserted with cement (3.6%).1
Intraoperative fractures to the acetabulum occur much less frequently than occur in the femur. Because very little stress is delivered to the acetabulum after reaming, reports of intraoperative fractures in cemented components are uncommon. Cementless acetabular reconstruction, however, depends on press-fit and can result in significant incidence of fractures.6-8
Intraoperative femoral fractures include many types and extents of fracture. Some fractures are recognized intraoperatively, while others are detected postoperatively with radiographic line or fracture displacement.2,4 Implant survival depends upon fracture pattern and, ultimately, implant stability.
Classifications by location, displacement, and implant stability have been reported. All classifications label location proximal to distal and complexity increases as fractures move distal. Most classification systems subclassify “A” as nondisplaced and “B” as displaced fractures.
Mallory et al9 described type 1 fractures in the proximal femur, type 2 around the stem, and type 3 at or below the tip of the prosthesis. Johansson et al4 outlined fractures in similar locations: type 1 fracture was proximal to the prosthesis tip; type 2 at the region of the tip of the prosthesis; and type 3 below the prosthesis. Stuchin10 described a type 1 fracture as proximal, type 2 as long spiral fractures near the tip, type 3 propagating from stress points in the femur, and type 4 as unclassified.
Although all femoral classification systems generally grade on location and displacement for description of fractures, the Vancouver system has been the most accepted.11 Modified to accommodate intraoperative fractures,11 the Vancouver system describes fractures in the same proximal-to-distal fashion with attention to configuration and stability of the fracture. Type A fractures are in the proximal femoral metaphysis, type B fractures extend or include the diaphysis but not distal diaphysis, and type C fractures extend distal and beyond long-stem fixation length. Each of these groups is further subdivided into types 1, 2, and 3. Type 1 includes perforations, type 2 represents linear nondisplaced fractures, and type 3 includes displaced and unstable fractures (Figure 1).
Reflecting the classification schemes, treatment is guided by location, configuration, and stability of the fracture. Results have not been universally good with intraoperative fracture. Johansson4 reviewed six femoral fractures proximal to the tip of the prosthesis, 15 fractures at the distal tip of the prosthesis, and two distal to the prosthesis. Some of the proximal fractures were treated with operative procedures, and some with nonoperative intervention. Of the six proximal fractures, two had satisfactory results — both treated operatively with fixation or long stem. All 15 fractures at the distal tip were treated with operative intervention. Eight of the 15 had satisfactory results. The remaining seven failed with malunion, loosening, or heterotopic ossification. Both fractures distal to the tip had unsatisfactory results secondary to refracture or loosening. Taylor3 reviewed 11 intraoperative fractures, most of which were in the proximal femur. The final outcome was not compromised, but morbidity and extended convalescence were noted.
Encouraging results were reported by Fitzgerald et al.12 This group reported on 40 fractures of 630 cementless femurs (6.3%). All but one was satisfactorily treated with Parham bands or wires and graft. The final fracture was noted postoperatively and treated successfully with cast.
Mallory et al9 reported on 56 intraoperative fractures. Of these, union occurred in 45 proximal fractures and nine fractures along the femoral component with no long-term prognostic hazard. The two fractures at the tip of the stem had analogous results, but the sample was too small to report on prognosis for distal fractures.
Figure 1: Intraoperative periprosthetic fractures of the femur – Vancouver classification.
Revision surgery involves complex bone quality and potential deformity. Intraoperative fracture is more common and difficult to treat in these situations. Paprosky et al13 reported on 15 of 170 fractures (8.8%) with an additional 10 cortical perforations during cement or component removal. No complicating events from fracture were noted in that series.
Proximal osteotomy or trochanteric slide helps to minimize distal fractures.14 These osteotomies led to higher incidence of proximal fractures at the osteotomy. Chen et al14 reported successful outcomes of these proximal fractures using cerclage wire with or without strut grafting.
The S-ROM proximally coated modular component provides many benefits in the instrumentation and implantation of revision femoral stems in complex, poor quality bone. The proximal-distal modularity and broad choices of proximal-distal size help prevent intraoperative fracture by sizing proximal and distal complex bone anatomy individually. In addition, the S-ROM uses a milling process instead of broaching in the proximal bone. This allows proper mill preparation of bone to reduce implantation stresses on bone and improve fit.
Figure 2: Intraoperative type A2 fracture treated with cerclage wires.
Summary recommendations can be guided according to the Vancouver-adapted classification.
Type A1 fractures denote simple proximal perforations and can be treated with simple local bone graft, and type A2 fractures describe proximal linear cracks, which may be amenable to cerclage wire fixation. Type A3 fractures reflect unstable fractures of the proximal bone and/or trochanter (Figure 2). These fractures necessitate a higher level of intervention. Distal diaphyseal fitting stems with cable, wire fixation, and, possibly, trochanteric clamps are necessary.
Type B1 fractures include diaphyseal cortical perforations. Strut graft with cerclage wire is recommended. Type B2 fractures denote diaphyseal undisplaced linear cracks (Figures 3 and 4). These can be treated with 6-12 weeks of limited weight bearing or cerclage wire with or without strut to bypass these fractures. Type B3 fractures indicate displaced diaphyseal fractures. Complexity of care is more pronounced with type B3 fracture types. Fracture reduction with cerclage, cable, and strut graft with well-fitted long stems is indicated.
Type C1 fractures denote distal perforations. These fractures are best treated with strut and cerclage. Type C2 fractures extend linear cracks almost to the knee. These fractures are best treated with cerclage and/or onlay strut. Displaced type C3 fractures require open reduction and internal fixation (ORIF) of the distal femur. Cerclage plate, locking plate, or retrograde nail with strut grafting is recommended.
Acetabular fractures are treated in accordance to fracture displacement and implant stability.15 If these fractures are nondisplaced and the component is stable, then acetabular component screw fixation can be used intraoperatively to stabilize. In addition, 8-12 weeks of toe-touch weight bearing is advised. If the fracture is displaced, then the component is removed. If the column is involved, then buttress plating is recommended. This is followed by gentle cementless acetabular placement (Figure 5). Touchdown weight bearing is recommended for a minimum of 12 weeks in these patients.
Figure 3: Intraoperative B1 fracture.
Figure 4: Intraoperative B1 fracture with strut and cerclage wires.
Figure 5: Intraoperative acetabular fracture treated with buttress plate.
Intraoperative Fractures Detected Postoperatively
Occasionally, intraoperative fractures are diagnosed in the immediate postoperative period. Full radiographic assessment is necessary. Late-recognized femoral fractures are usually nondisplaced and stable. Protected weight bearing with spica brace or cast is encouraged to successfully unite femoral fractures.2 Displaced fractures with femoral component instability are addressed with revision and ORIF as is to be outlined in late postoperative fractures.
Postoperatively, acetabular fractures that are immediately diagnosed can be treated nonoperatively in most patients. Nondisplaced fractures with radiographically stable components are treated with 12 weeks of touchdown weight bearing.15 Displaced fractures with component loosening require revision with wall or column fixation and revision cementless acetabular placement.15
The prevalence of postoperative fracture ranges from 1% in primary femoral components to 4% in revision femoral components.1 Postoperative fractures are often caused by minor trauma. Adolphson et al16 described 80% of fractures caused by minor trauma, whereas Beals and Tower17 concurred with 84% of fractures from minor trauma. Major trauma is considered the etiology in approximately 8.5% of reported cases.18 Acetabular postoperative fractures analyzed by the Mayo Clinic Total Joint Registry found 16 fractures in 23,850 (or 0.07%).19
Figure 6: Postoperative periprosthetic fractures – Vancouver classification.
Late postoperative femoral fractures are more common than acetabular fractures in hip arthroplasty. Generally, classifications of femoral fractures have been guided by location of the fracture with attention to implant stability. Many investigators including Morrey and Kavanagh,20 Whittaker et al,21 and Mont and Maar22 have introduced standards for periprosthetic fracture. All investigators have used a combination of prosthetic stability and location as identifiers for the fracture. The Vancouver classification, which is now accepted for detailing femoral prosthetic fractures,23 addresses the three most important factors: location, stability of the implant, and bone quality. In the Vancouver classification, the femur is divided into three locations: A, B, and C (Figure 6).
Type A fractures occur proximal to the bone. They are divided into type A-G fractures of the greater trochanter and type A-L fractures of the lesser trochanter. Type B fractures involve those that occur around or immediately below the prosthesis. Type B1 fractures designate fractures of the level of the prosthesis where the prosthesis is solidly fixed. Type B2 fractures are located at the prosthesis but with a loose prosthesis. Both B1 and B2 fractures also imply reasonable bone quality. Type B3 fractures occur at the level of the prosthesis but where compromised or osteopenic/osteolytic or comminuted bone is involved with the fracture. These implants are considered loose with poor bone quality. Type C fractures occur farther below the femoral component. These fractures include those distant to the femoral component, potentially even as far as the supracondylar or intercondylar area.
Acetabular periprosthetic fractures are divided broadly into two classification levels: fractures that are radiographically stable and fractures that are considered radiographically unstable.
Figure 7: Displaced type A-G fracture.
Figure 8: Type A-G fracture treated with trochanteric clamp.
Results – General Principles
Nonoperative treatment is reviewed in a historic sense. Protected weight bearing,24 traction,22 and casts22 have been used. Johansson et al4 described 37 fractures in 35 patients. Ten of the 37 were treated non-operatively using a combination of traction, traction with early mobilization and spica casting. Twenty-five of the fractures were treated operatively with plates and screws with or without long stem femoral component placement. These authors reported best results with the use of long stem prosthesis and fixation. The only satisfactory results seen in nonoperative treatment involved very proximal fractures with maintained prosthesis integrity. The best results were in patients revised to long-stem prostheses.17 Somers et al25 reported on 34 fractures treated nonoperatively. Thirty-three of the 34 healed but with prolonged treatment and high complication rates.
Surgical intervention is more frequently recommended than nonoperative treatment in the care of periprosthetic postoperative fracture. Full radiographic assessment is recommended. Serologic testing and aspiration may be important to evaluate patients for the potential of sepsis. Surgical treatment requires several general principles to be followed.26 A surgeon must be familiar with extensile femoral surgical approaches. Intraoperative cultures and antibiotics are recommended. Lateral exposure of the femur is combined with a modified lateral or posterior hip approach. When exposed, removal of debris and accentuating displacement for purposes of debridement may aid in later reduction. Generally, techniques for ORIF are used in the presence of well-fixed components. This can be accomplished with plate/wire combinations. Locking screw technology and the use of strut graft may also be effective.
Plates can be used exclusively or with strut graft augmentation.27 Another alternative is two strut grafts at 90°.28 Cable plate systems such as the Dall-Miles29 (Stryker Orthopaedics, Mahwah, NJ) or the Ogden plate27 (Stryker Orthopaedics) can be used effectively to stabilize fractures with implants. Venu et al29 described 12 periprosthetic fractures described with a Dall-Miles plate and cortical strut graft. Nine of the 12 united with three requiring further surgery for nonunion. Tadross et al30 reported seven fractures treated with Dall-Miles; three of the fractures healed and four failed. Failures were believed secondary to varus stem placement with altered biomechanics. Recommendations for additional allograft strut were noted. The use of cortical struts alone for stabilization has been reported by Chandler,28,31 who also reported 21 of 22 patients with fractures uniting when a metal plate on one cortex was combined with strut graft on the other cortex.
Revision for femoral periprosthetic fracture is necessary in loose or unstable components. Results for revision have reflected the challenges of this fixation. Beals and Tower17,32 reviewed 102 interventions in 93 periprosthetic fractures by 30 surgeons. Results were excellent in 32% and poor in 52%. Although high complication rates were seen in all groups, cementless revision components faired better than cemented components. The best results were seen in patients treated with long-stem cementless implants. Lawrence et al33 and Paprosky and Aribindi34 have used extensively porous-coated implants to bypass fractures. Springer et al35 reported best results with type B femoral fractures using an uncemented extensively coated long-stem prosthesis. Mont and Maar,22 in their review of 487 patients from 26 reports, reported that open reduction with cerclage plates or revision to long-stem cementless components was better than screw fixation or traction. Wagner-style prostheses have also been successful in geriatric patients.36 Ko et al36 reviewed 14 patients over 3 to 5 years. All prostheses appeared radiographically stable. Seven patients had excellent outcomes, and three patients had good outcomes.
Figure 9: Displaced type B1 fracture.
Figure 10: Type B1 fracture treated with revision to long-stem prosthesis.
Severe bone loss proximally with periprosthetic fractures can be treated with segmental allograft37 or proximal femoral replacement. Wong and Gross38 reported on 19 patients treated with proximal femoral allograft. Of the 15 patients available at follow-up, 13 patients had good results and two required additional surgery. Proximal femoral replacement may be useful in low-demand or elderly patients. Survivorship of the proximal femoral replacements has been reported to be 65% at 12 years.36,39,40
Acetabular fractures can be classified into displaced and nondisplaced. Peterson and Lewallen41 reported on 11 patients with postoperative acetabular fractures. Although of different fracture types, the categories were maintained as radiographically stable or unstable. Eight of 11 fractures were clinically and radio-graphically stable, and two fractures were unstable. One patient died of related injuries in the pelvis at the time of his trauma. Patients with unstable acetabulae were treated with revision and plate or cage, and patients with stable implants were treated nonoperatively with modified activities. Of the 10 surviving patients followed, eight of the patients (including four patients with stable implants that went on to union) went on to revision because of persistent pain. The investigators concluded that these fractures had a poor prognosis and may need later reconstruction, but union can be achieved and salvage revision can be successful.
Summary for postoperative fractures can be guided by the Vancouver classification of fracture type. Type A-L fractures reflect poor quality of bone and possible osteolytic or osteoporotic processes. In addition, type A-L fractures are difficult to reduce, difficult to adequately fix, and are treated symptomatically. In the case of nondisplaced type A-G fractures, nonoperative care is preferred. Protection for several weeks with a crutch or walker may avoid displacement and provide an environment for early healing. In type A-G fractures, displaced and bone stock is adequate, fixation may be recommended in the high-demand patient only to avoid pain, weakness, limp, and possible instability.26 Trochanteric clamp, wires, or cerclage with lateral plate extension may be used effectively (Figures 7 and 8). Limited bone purchases on trochanteric fragments or poor bone quality may compromise results.
A type B1 fracture, if nondisplaced, can be treated nonoperatively in a com promised patient. This treatment involves lengthy bracing and crutch and/or walker use. Activity limitations may be extended leading to complications of the sedentary function. The potential for displacement in nonoperative care is high and poor results have been reported. Type B1 fractures with any displacement should be treated with fixation or revision. With well-functioning, well-fixed implants, ORIF is considered. Distal plate fixation with proximal cerclage and/or allograft strut or modern locking plate technology with limited dissection locking plate technology can be used. If an S-ROM proximally coated modular stem of standard length is used at the index surgery, this can be converted to a longer stem with or without cerclage and strut to provide intramedullary fixation of the more distal fracture without interrupting proximal sleeve ingrowth (Figures 9 and 10).
Figure 11: Displaced type B2 fracture.
Figure 12: Type B2 fracture treated with revision to long-stem prosthesis.
Type B2 fractures necessitate revision of the loose femoral component in conjunction with femoral fixation treatment. Fractures must be individualized with bone quality, fracture pattern, and surgeon experience. Proximally coated long-stem modular components, long-stem distally coated stems, or long-stem cemented prostheses can be used in these situations depending on bone quality and patient demand. Cerclage wires, strut allografts, or locking brace can be used to supplement fixation (Figures 11 and 12). Comminuted type B3 fractures will require aggressive fixation considerations. Revision of the component is essential in type B3 fractures. Proximal bone will be unusable. Revision will necessitate an allograft composite; proximal femoral replacement, or a cementless, fluted, tapered, grit-blasted modular stem for successful stability. Reattachment of vital proximal tissue structures such as the greater trochanter, should be attempted (Figures 13 and 14).
Figure 13: Type B3 fracture displaced after attempted ORIF.
Type C fractures can be treated in a similar manner to any distal femoral fracture. Proximal femoral obstruction precludes antegrade nailing. Retro-grade nailing is a suitable option. Consideration for strut grafting over the unrodded, nonstress-sharing portion of the femur should be considered. Suprachondylar plates or distal femoral plating with additional strut grafting may encourage healing and maintain stability (Figure 15).
Late acetabular fractures are treated based on radiographic stability. If radio- graphically stable, conservative treatment may be indicated. Acetabular loosening may occur, in which case, revision may then be necessary.
If the socket is unstable radiographically, then revision is indicated. Column fixation with plate and revision of the cementless hemisphere may be adequate. In patients with compromised bone, osteolysis, or extensive fracture, cage fixation with plate augment may be necessary to secure the hemipelvis.
Periprosthetic fracture in primary and revision total hip arthroplasty will continue to affect outcomes in hip arthroplasty. Limited visualization in minimally invasive techniques and press-fit components will require care to be taken to prevent or at least address intraoperative fractures appropriately. The number of implants in the population combined with osteolysis from wear and osteoporosis from age predicts a trend toward future late periprosthetic fractures. Suitable advances and experienced treatment techniques will produce the best outcomes.
Figure 14: Type B3 fracture revised to distal fit Wagner style stem.
Figure 15: Type C fracture treated with ORIF plate and strut with cerclage wires.
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- Johansson JE, McBroom R, Barrington TW, Hunter GA. Fracture of the ipsilateral femur in patients with total hip replacement. J Bone Joint Surg Am. 1981; 63:1435-1442.
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- Stiehl JB, MacMillan E, Skrade DA. Mechanical stability of porous-coated acetabular components in total hip arthroplasty. J Arthroplasty. 1991; 6:295-300.
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- Paprosky WG, Greidanus NV, Antoniou J. Minimum ten-year results of extensively porous-coated stems in revision hip arthroplasty. Clin Orthop. 1999; 369:230-242.
- Chen WM, McAuley JP, Engh CA Jr, Hopper RH Jr, Engh CA. Extended figure trochanteric osteotomy for revision total hip arthroplasty. J Bone Joint Surg Am. 2000; 82:1215-1219.
- Callaghan JJ. Periprosthetic fractures of the acetabulum during and following total hip arthroplasty. Instr Course Lect. 1998; 47:231-235.
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Dr Van Flandern is from the New England Baptist Bone & Joint Institute, Boston, Mass.