Fig. 11.1
Vancouver B2 femoral fracture 5 months following total hip arthroplasty with subsequent stem subsidence
Case 2: A 45-year-old male with a history of slipped capital femoral epiphysis of his left hip that was treated with in situ pinning presented with end-stage arthritis of the hip (Fig. 11.2a). He is 6 ft tall and weighs 245 lbs. He had retained hardware from a previous failed attempt at removal. During his total hip arthroplasty, the hip was dislocated with the screw in place. The screw had previously been stripped. The neck cut was made, exposing the distal end of the threaded end of the screw, which was then extracted in a retrograde fashion. The femoral canal was then broached for a flat wedge tapered stem and the final implant was press-fit into the canal. In the recovery room, postoperative X-ray demonstrated a periprosthetic femur fracture at the tip of the femoral component (Fig. 11.2b). This had not been noticed intraoperatively.
Fig. 11.2
(a) Preoperative radiograph demonstrating hip osteoarthritis following slipped capital femoral epiphysis . (b) Intraoperative femoral fracture in the diaphyseal region discovered postoperatively
Background
The earliest case report of a periprosthetic femur fracture after total hip arthroplasty (THA), in 1954, was of a female who suffered an intertrochanteric fracture around the stem of a cemented hemiarthroplasty. The fracture was fixed using transfixing bolts and wire loops, and the prosthesis was reinserted [1]. In 1964, Parish and Jones [2] reported nine cases of femur fractures around Austin-Moore and Thompson prostheses . The authors classified the fractures according to the location of the fracture to intertrochanteric, proximal, mid-shaft, and distal fractures. Two years later, Sir John Charnley [3] described a periprosthetic femur fracture around a cemented Thompson prosthesis. She was treated with balanced traction and the fracture healed after 3 months [4].
Incidence
Periprosthetic femoral fractures may occur intraoperatively, or early or late postoperatively following THA. Depending on the femoral fixation method used, differences in the incidence of intraoperative fractures have been reported. An incidence of 0.1–3.5% has been reported with cemented stems [4, 5]; however, an increase of intraoperative fractures has been reported with the introduction of uncemented stems [4, 6]. Schwartz et al. [7] studied 1318 consecutive uncemented total hip replacement arthroplasties and found 39 intraoperative fractures of the femur (3%), only half of which were diagnosed intraoperatively. A recent study from the Mayo Clinic registry [8] showed an intraoperative fracture incidence of 0.2% in 15,178 primary cemented and 3% in 17,466 uncemented THAs. The 20-year cumulative probability of postoperative periprosthetic femoral fractures was 2.1% after placement of a cemented stem and 7.7% with uncemented stems. In revision surgery, an even higher incidence has been reported. In 1999, Berry [9] reported an intraoperative fracture incidence of 3.6% in cemented and 20.9% in uncemented revision THAs. A review of the Swedish registry showed late femoral periprosthetic fracture to be the third most frequently reported cause for reoperations after THA (9.5% of the reoperations), after aseptic loosening and recurrent dislocation [10].
Etiology and Risk Factors
In a retrospective review of 93 periprosthetic fractures, Beals et al. [11] found that the most common mechanism of late fracture was a ground-level fall (84%). Several potential risk factors for periprosthetic fractures around THA have been studied including primary diagnosis, age, osteolysis, aseptic loosening, revision, and implant design type.
Primary Diagnosis
A matched case-control study of the Finnish registry showed that patients who had fracture as primary diagnosis for arthroplasty had a 4.4 times higher risk of periprosthetic fracture than those operated on for other reasons [12]. Similarly, analysis of 321 periprosthetic fractures reported to the Swedish registry showed that an index diagnosis of hip fracture was significantly more common than an index diagnosis of osteoarthritis or inflammatory arthritis in the fracture group (p < 0.001) [10].
Age
Cook et al. [5] examined a cohort of 6458 primary cemented femoral prostheses implanted from 1983 to 1999. Patients older than 70 years had a 2.9 times greater risk of sustaining a subsequent fracture. It is likely that increased age is associated with increased incidence of periprosthetic fractures due to a number of factors including osteoporosis, increased risk of falls, lower body mass index, higher incidence of osteolysis and loose stems, and a higher likelihood of having had a revision surgery [13].
Osteolysis
Late periprosthetic fracture associated with osteolysis has been recognized as a growing problem in arthroplasty [14]. The greater trochanter is a common area for osteolytic fractures because it is a large cancellous bone surface in proximity to the source of particle generation. The high stress imparted by the abductors in combination with the frequency of osteolytic lesions not infrequently leads to fracture in this area [14].
Aseptic Loosening
Loose implants have been demonstrated to be risk factors for periprosthetic fracture in several studies [10, 15–17]. In a review of 321 periprosthetic fractures reported to the Swedish National Hip Arthroplasty Register, Lindahl et al. [10] found that a high number of patients had a loose stem at the time of the fracture (66% in the primary THA group and 51% in the revision THA).
Revision Surgery
Revision total hip arthroplasty is frequently associated with bone loss and challenging implant fixation. Wear debris and resultant osteolysis can reduce available bone stock for fixation at the time of revision [13]. In a study of 215 Medicare beneficiaries who had periprosthetic femoral fracture between 2006 and 2008, a greater risk of periprosthetic fracture was associated with having had a revision total hip replacement [18]. In a study of 64 patients who sustained an intraoperative fracture of the femur during revision hip arthroplasty with a diaphyseal fitting cementless stem, risk factors associated with an intraoperative fracture were a substantial degree of preoperative bone loss , a low femoral cortex-to-canal ratio, under-reaming of the cortex, and use of a large-diameter stem [19].
Implant Design Type
Little is known about how the design features of cementless implants affect a patient’s risk for subsequent periprosthetic fracture. In a study of 111,899 uncemented femoral stems reported to the Nordic Arthroplasty Register from 1995 to 2009, the authors demonstrated an increased risk of fractures with the ABG II stem (anatomic design) and a decreased risk for the Corail stem (wedge design). Given that a wedge-shaped stem could be expected to more frequently act as a stress riser with its comparatively sharp corners compared with a rounded design, the authors concluded that these results were difficult to interpret [6]. Another study of 3964 primary THAs in which an alumina grit-blasted, proximally hydroxyapatite-coated femoral component with an exaggerated proximal taper angle was compared to five cementless, proximally fixed stems of different design showed an increased risk of early and late postoperative femoral fractures in hips implanted with that particular stem design. The stem was subsequently discontinued by the manufacturer [20]. In cemented stems, some studies have shown increased risk of fracture with a polished stem designed to subside in the cement mantle [6, 12, 21]. An inadequate cement mantle, with implant contact with the inner and distal femoral cortex, has been correlated with long-term loosening, femoral osteolysis, and subsequent risk for fracture [21].
Evaluation
Since the fixation status of the implant is a critical aspect to the treatment algorithm, it is essential that the examiner elicit any signs and symptoms that may suggest implant loosening prior to the injury, such as start-up thigh pain. The injured limb’s neurovascular status and soft-tissue condition should be carefully documented. Preoperative planning should include identification of previous surgical scars, review of previous operative reports, and appropriate workup for infection in patients with previously symptomatic implants. Synovial fluid WBC count and neutrophil percentage are the best tests for diagnosing prosthetic joint infection and have similar cutoff values as when used for detecting infection in patients without a periprosthetic fracture [22]. High-quality standard anteroposterior and lateral radiographs of the affected hip and femur as well as any previous radiographs, if available, should be reviewed in an attempt to determine the stability and fixation status of the implant if possible [23].
Classification
The Vancouver Classification (Table 11.1) is currently the most widely used and accepted and is based on fracture location with subtypes in the B-type fractures based on implant fixation status and bone loss [24].
Table 11.1
Vancouver classification of periprosthetic femur fractures after total hip arthroplasty
Vancouver classification of periprosthetic femur fractures | ||
|---|---|---|
Type | Fracture location | Subtype |
A | Trochanteric region | AG: fractures that involve the greater trochanter |
AL: fractures that involve the lesser trochanter | ||
B | Around the stem of the femoral component, or extend slightly distal to it | B1: the implant is stable |
B2: the implant is loose and the bone stock around the femoral component is adequate | ||
B3: the implant is loose and the bone stock around it is inadequate to support traditional femoral implants | ||
C | Well distal to the stem | |
Prevention
Prevention of periprosthetic femur fractures around total hip arthroplasty begins with careful preoperative planning and identifying patients who are at risk of such a complication. Attention to preventing and identifying small intraoperative fractures is critical so that they can be addressed intraoperatively. Prevention of late periprosthetic femoral fractures is best accomplished through routine clinical and radiographic follow-up [13]. Regular monitoring of patients allows for early detection of osteolysis and aseptic loosening, and thus facilitates timely revision surgery.
In a review by Tsiridis et al. [16], several preventive measures for periprosthetic femur fractures were identified. Preoperatively, attention to careful component templating and identifying at-risk patients is of paramount importance. Intraoperatively, fractures could be prevented by careful dislocation of the hip and by following proper technique of femoral canal preparation and careful insertion of the final prosthesis.
In revision settings, it is important to obtain adequate surgical exposure, which may involve various peri-trochanteric osteotomies to aid with prosthetic alignment and component or cement removal. Both careful reaming and avoidance of eccentric or varus directions when using the reamers are important and may be facilitated by judicious use of radiographs during femoral preparation and implant insertion. It may be of value to strengthen the femur prophylactically by using cerclage wires prior to femoral preparation and implant insertion, and it is the authors’ practice to place a prophylactic cerclage wire just distal to the osteotomy site if an extended trochanteric osteotomy is used to prevent iatrogenic fracture propagation. If a fracture has already occurred, cerclage wiring can be used to prevent it propagating further and should be placed sufficiently past the most distal extent of the fracture to protect the intact femoral canal. Cement removal is most safely achieved by splitting it radially and at several levels or by using ultrasound. Cortical defects and osteolytic lesions should be bypassed when possible. Cortical strut grafts may be used prophylactically to reinforce cortical defects and other stress risers. Postoperatively, good-quality anteroposterior and lateral radiographs of the entire length of prosthesis should be obtained before weight bearing to exclude unrecognized fractures.
Treatment of Late Periprosthetic Femur Fractures
Treatment of periprosthetic fractures after total hip arthroplasty is summarized in Table 11.2.
Table 11.2
Treatment of femur fractures after total hip arthroplasty
Type A (trochanteric) | |
• AG | • Trochanteric plate fixation for large, markedly displaced fractures |
• Nonoperative treatment for late, osteolysis-related fractures | |
• AL | Nonoperative treatment |
Type B (stem region or slightly distal) | |
• B1 | Confirm implant stability, reduction, and internal fixation of displaced fractures using a locked plate-cable system |
• B2 | Stem revision, bypass with a long-stem prosthesis by minimum of two cortical diameters, supplemental cerclage cables as needed |
• B3 | • Reconstruction with a long, fluted modular stem that engages any remaining isthmus, cable fixation of the fracture pieces around the proximal body of the implant |
• Allograft-prosthetic composite versus proximal femoral replacement in cases where fluted stem fixation is not possible | |
Type C (well distal to the stem) | Fixation according to the fracture type, making sure that the fixation construct overlaps the tip of the femoral stem to avoid leaving weak segments of bone |
Type A Fractures
Type AG fractures are stable when minimally displaced because they are securely positioned by the tendons of the vastus lateralis and the abductors, which prevent further displacement and proximal migration. This fracture is usually related to wear-debris osteolysis of the greater trochanter (Fig. 11.3) [25]. Nonoperative treatment for several months to allow bone healing or stable fibrous union before revision for osteolysis is typically recommended. A hip abduction brace may help reduce pain while the fracture is healing [14].
Fig. 11.3
Extensive trochanteric osteolysis and fracture around a well-fixed cylindrical stem
If the greater trochanteric fragment is large and markedly displaced, and the remaining bone is satisfactory to gain fixation, then early revision to restore abductor mechanism continuity with internal fixation of the greater trochanter to its bed or to an advanced position may be considered [14]. Type AL fractures as an isolated injury can usually be ignored unless there is a distal extension involving the medial cortex that has destabilized the fixation status of the femoral stem [25].
Type B Fractures
Nonoperative treatment has been practiced in the past [3, 26], but because of its high morbidity, surgical treatment of these fractures has been established as the preferred treatment. Internal fixation may be used either alone or in combination with stem revision. The stability of the original implant, amount of bone loss, and configuration of the fracture itself are the basic factors that influence the decision-making process. Lindahl et al. [27] found that a major risk of failure in the treatment of these fractures is misinterpretation of the stability of the stem and misclassifying type B2 fractures as type B1, resulting in treatment with plate fixation without revision of the stem . This fact necessitates a careful assessment of the fixation status of the femoral stem in every type B periprosthetic femur fracture with additional confirmation intraoperatively.
Type B1 Fractures
Due to the femoral component being well fixed, the principal strategy of type B1 fractures is internal fixation of the periprosthetic bone without femoral revision. Different fixation techniques were tested and compared in an in vitro study by Schmotzer et al. [28]. The authors compared allograft struts with wire cerclage (18-gauge Vitallium, Howmedica), allograft struts with multifilament cable cerclage (Dall-Miles, 2 mm stainless steel, Howmedica), bypassing the fracture with a long stem (PCA, Howmedica), long stem with allograft struts and cerclage, plate (Synthes, Paoli, PA) with cables proximally and bicortical screws distally, and plate with unicortical screws (4.5 mm, Synthes) proximally and bicortical screws distally. The authors concluded that cables were significantly stronger and more appropriate than standard cerclage wiring and that compression plating with combined proximal cables and unicortical screws should be preferred over proximal wire fixation alone [28].
Cable-Plate System
In an early effort to provide rigid fixation around the femoral construct of a THA, Berman and Zamarin [29] introduced the Dall-Miles plate-cable system (Stryker Howmedica, Mahwah, NJ) in a case report in 1993. The system included 1.6 and 2.0 mm braided Vitallium alloy cables, small and medium sleeves, medium and large grips, and plates of varying length. Cable tensioners were used to tighten the cables. It also allowed unicortical screw fixation with cable augmentation proximal to the fracture, in addition to bicortical screws distal to the fracture.
Four years later, Haddad et al. [30] documented their use in a small series of four periprosthetic fractures that all had excellent clinical outcomes. The study of Sandhu et al. [31] reported the outcome of 20 fractures treated with this system. All of the fractures united with no fixation failures over a postoperative period of 1–4 years. However, two type B1 fractures later collapsed into varus, and both of these cases were treated with a plate fixed only with cables. Based on these results, the authors recommended that fixation of the plate with cables alone should be avoided because of the torsional instability of the construct [32]. Similarly, Dennis et al. [33] in a biomechanical study showed that plate constructs with proximal unicortical screws and distal bicortical screws or with proximal unicortical screws, proximal cables, and distal bicortical screws were significantly more stable in axial compression, lateral bending, and torsional loading than a plate with cables alone , plate with proximal cables and distal bicortical screws, or two allograft cortical strut grafts with cables. Tsiridis and colleagues [34] reported failure by fracture of the Dall-Miles plate in two out of three B1 fractures. The plates were stabilized with cables proximally and bicortical screws distally below the tip of the femoral component.
Compression Plating
The first description of compression plating of periprosthetic femoral fractures was by French authors [35]. In 1992, Serocki et al. [36] treated ten periprosthetic femur fractures with 4.5 mm broad dynamic compression plates. The authors identified one limitation of these plates, which only allowed 7° and 25° of screw angulation when trying to avoid the stem. A prospective study of plate fixation of Vancouver B1 fracture types was published in 2005 by Ricci et al. [37] who evaluated 37 cases. Indirect reduction techniques were applied in all cases, sometimes preserving a soft-tissue bridge over the fracture site to minimize the operative trauma to the soft-tissue envelope, and reduction was achieved using fluoroscopy and traction. Fixation was accomplished with a standard 4.5 mm broad DCP in 27 of the 37 cases, which was secured on the bone via unicortical or bicortical screws and cables. No strut allografts or cancellous bone grafts were used to augment the osteosynthesis and all fractures united at an average of 3 months. The authors emphasized that the plate must be of sufficient length to bypass the implant by a minimum of six screws and that soft-tissue dissection should be minimized to preserve blood supply and facilitate osteosynthesis.
Related posts:
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
