2.1 Clinical evaluation

A detailed assessment of the patient prior to treatment is essential to maximize the chances of a good outcome. The basic diagnosis of PPHF relies on:

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  Clinical history of the mechanism of injury (high-energy versus low-energy trauma)

  
  
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  Pain

  
  
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  Preinjury functional decline or joint pain. This may indicate loosening or infection. It is important to ask the patient about the function of the joint before the injury, was it a “happy joint” (ie, a joint that functions well with no pain) or not?

The initial examination should include:

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  General skin condition and location of previous scars

  
  
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  Examination of the knee

  
  
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  Assessment of leg lengths

  
  
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  Neurovascular status

2.2 Imaging

2.2.1 Plain x-rays

Images should be reviewed thoroughly to ascertain the type of fracture and the stability of the implant. It is one of the major challenges and tasks to find out if the implant is stable or not. Conventional x-rays should include the following high-quality views:

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  AP pelvis, centered over the symphysis

  
  
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  The affected hip joint in a second plane

  
  
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  The whole femur in two planes. It is important that the full length of the femur is imaged and the x-rays scrutinized (both the stem and cup) to fully appreciate the entire extent of the fracture, as well as the presence, status, and type of any associated knee implants.

The following details need to be assessed:

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  Total hip arthroplasty components for loosening. Careful assessment of the stability of implants in the femur and acetabulum

  
  
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  Fracture location in relation to the type of implant. Depending on the type of stem, fracture location may indicate loosing even without clear signs of loosening [12].

  
  
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  Acetabular wear signs

  
  
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  Available bone stock

High-quality x-rays are essential to look for radiolucent lines around the prosthesis or cement, indicating periacetabular osteolysis. The magnification of the image can be measured by placing a radiopaque calibration object of known dimension at the same plane as the hip joint. If the size of the previously implanted femoral head or cup is known and the border clearly detectable, it can be used also as a scaling marker.

Additional important assessment features include:

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  The fracture geometry and any change in implant positioning

  
  
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  Proximal femoral varus remodeling ( Fig 3.13-1 )

  
  
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  Femoral shaft deformity

  
  
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  Presence of an implant below the hip implant, eg, a total knee implant of the revision type

Important factors which may influence the decision making for fracture fixation versus revision arthroplasty include polyethylene wear, acetabular shell position, large osteolytic lesions [13, 14], significant osteoporosis [3, 7], as well as debonding of the cement from the implant and/or extensive cement fracture [15].

2.3 Chronic infection

Trauma and fracture can elevate inflammatory markers (ie, C-reactive protein, erythrocyte sedimentation rate, white blood cell count) making the positive predictive value of these tests for periprosthetic joint infection poor [16]. If the history or the x-ray is suspicious for a periprosthetic joint infection, further diagnostic tests such as bone scintigraphy or a joint aspiration should be performed. The joint aspiration needs to be done preoperatively under sterile conditions prior to skin incision, and may result in surgical delay. Joint aspiration results obtained after the patient has already received antibiotics need to be interpreted with caution as this may obscure identification of pathogens.

3.1 Vancouver Classification

The Vancouver Classification is the most widely accepted classification system of total PPHFs used today, based on the three most important factors for management: fracture location, stem stability, and quality of the remaining bone stock. This classification divides the femur into three anatomical zones: trochanteric region (A), diaphysis (B), including or just distal to the tip of the prosthesis, and diaphysis well distal to the tip of the prosthesis (C). The Vancouver Classification is both reliable and valid, shows good correlation between radiographic evaluation and intraoperative findings [22, 23], fits all common and uncommon fracture patterns, and has been recently extended to apply to all periprosthetic fractures, regardless of which joint or bone is involved [21].

3.2 Unified Classification System

The Unified Classification System (UCS) ( Fig 3.13-2 ) combines the original Vancouver Classification with the AO/OTA Fracture and Dislocation Classification with proven excellent agreement among independent observers [24]. The USC uses as standard coding scheme:

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  Roman numerals to represent joints, with the hip joint identified as number IV.

  
  
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  Numbers to represent the bone involved (pelvis 6, femur 3).

  
  
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  Letters to represent the type of fracture.

Fracture types are defined as follows:

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  Type A (apophyseal) are fractures of the greater trochanter (GT) or lesser trochanter (LT). Most often these fractures are associated with some localized osteopenia or osteolysis.

  
  
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  Distal of the GT to the prosthesis tip or just below is a type B fracture (around the implant). These fractures can further be divided into subtypes: B1 referring to a stable prosthesis suitable for an osteosynthesis, B2 is adjacent to a loose stem with sufficient bone stock for a straight-forward revision surgery, and B3 referring to loose stem and inadequate bone stock and marked osteopenia/osteolysis requiring complex revision with possible bone graft. The precise identification of postoperative femoral Vancouver type B1 fractures is an important step in fracture management [17, 25].

  
  
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  Those fractures that are located well below the prosthetic socket belong to the type C fractures (clear of or distant to the implant). Their treatment is independent of the THA with exception of some special techniques to fix the plate around the proximal stem. This type of fracture accounts for approximately 10% of the fractures around a hip prosthesis [4].

  
  
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  Type D fractures represent interprosthetic fractures, dividing two implants.

  
  
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  Type E fractures describe a floating joint with each of the two bones supporting one joint replacement.

  
  
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  Type F represents fractures articulating or facing a hemiarthroplasty.

5.1 Operative versus nonoperative treatment

Nonoperative treatment is no longer recommended for type B and type C fractures because of the patient′s inability to tolerate prolonged immobilization without a high risk of complications such as pulmonary infection, pressure ulceration, and death [14, 26, 27]. Moreover, the rates of nonunion after nonoperative management are high because of inadequate fracture stability and the variable presence of bone cement at the fracture site [27, 28]. With modern treatment strategies, nonoperative management is reserved only for patients who would not be able to tolerate surgery. Although operative intervention is thought to offer the best outcomes, controversy still exists regarding the preferred fixation technique and optimal management strategy, given the high stress location of these fractures and the prosthesis. Many types of implants are available to maintain the reduction, none of which has demonstrated superiority. It has become apparent that certain methods of internal fixation are unsuitable, such as the Mennen paraskeletal clamp, which can be associated with early catastrophic failure [29, 30] and the Parham bands which do not provide adequate fixation and can cause substantial bone resorption [14, 31].

5.2 Type B1 or B2?

Accurate assessment and confirmation of stem stability is the key to a good outcome after fracture fixation:

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  Plain x-rays should be carefully examined for signs of a loose stem, specifically looking to identify continuous lucency at the cemented stem and the bone-cement interface.

  
  
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  In acute fractures, a cement mantle fracture alone is not considered diagnostic of a loose stem. In contrast, fractures of the cement mantle before acute trauma are indicative of a loose stem.

  
  
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  If any doubt exists, routine intraoperative stem stability tests are recommended prior to fixation [32]. This approach, however, requires more exposure of the joint for plating of the femur, adding potential for postoperative dislocation.

  
  
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  If the distal aspect of the stem is exposed at the fracture site, it may be tested for instability by generation of shear force along the longitudinal axis between the prosthesis and the proximal bone fragment or cement. This can be performed with a pointed reduction forceps on the femur and a Kocher forceps grasping the stem tip.

  
  
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  If such a maneuver is not possible, a formal arthrotomy and dislocation is necessary to gain adequate exposure to exclude instability.

5.3 Can we fix type B2 fractures?

There is some discussion about fixation of type B2 fractures, taking into account a possible subsidence of 1–2 cm.

In general internal fixation of Vancouver B2 and B3 fractures result in a high reoperation rate [4, 33]. Although the Vancouver Classification has been proven to be a useful and reliable guide for the surgical planning of periprosthetic fractures, important factors like the patient physiology (medial comorbidities, physical status) and the surgeons’ experience are not reflected. Joestl et al [34] published the concept of internal “biological fixation” utilizing internal fixation as an alternative operative option for treatment of periprosthetic femoral fracture fixation with a loose stem. They reported no significant differences in the patient outcome measured by the Parker Mobility Score or operative time. However, most studies are retrospective case series with missing specific details like the type of the original implant used with missing information regarding the type of primary fixation. When treating fractures around cementless or cemented femoral prostheses the surgeon must understand the primary fixation principle, eg, in cementless stems if the primary fixation is proximal or distal and in cemented stems if the fracture occurred around a composite beam stem or shape-closed designs with bonding of the prosthesis-cement interface or a polished tapered or force-closed design with no bonding between the prosthesis and the cement. In case of a noncomminuted fracture around a polished tapered stem with an intact cement mantle, internal fixation following anatomical reduction can be a treatment option. A CT scan might help in these cases to analyze the fracture pattern and cement mantle integrity. Following internal fixation, the stem may subside a few millimeters until stability is reestablished in the intact cement mantle. In case of small cement deficiencies with no bone loss, a cement-in-cement revision technique is also an option. However, in both cases an anatomical reconstruction of the fracture is mandatory. Good results with this technique in fractures around a polished tapered stem have been reported [35, 36]. The literature nowadays is not absolutely conclusive as to which patients require stem revision and which ones will benefit from internal fixation only. Internal fixation of a loose stem is an option as a palliative procedure in immobile and severely ill patients except in case of a polished tapered stem with an intact cement mantle.

5.4 Should cortical strut allograft be used?

This is an ongoing discussion. Many arthroplasty surgeons still like to use cortical strut allograft but the incidence seems to be much lower than in the past. Technically, it works but there is significant soft-tissue stripping required. If surgeons think more stability is required, there are other methods available, such as double plating.

Historically, type B1 fractures were reduced using stainless steel cerclage wires with rigid dynamic compression plates, occasionally in combination with cortical allograft struts [18, 37–39]. The use of allograft struts is an alternative or adjunct fixation method. Strut grafts, in case of a stable prosthesis, may be used as the only means of stabilization with either a single strut or as a double strut complex in 90° or 180° to each other (or in combination with osteosynthesis). Strut grafts have the advantage of being a biological and osteo-conductive technique, providing reduced stress shielding due to similar modulus of elasticity as the native bone, augmenting the host bone stock and strength after union [39–43]. Placing two strut grafts with three fixation points above and below the fracture have been shown to yield good outcomes [44, 45]. Combined plating with proximal cable fixation augmented with an anterior or medial strut graft may provide better stability than an allograft strut alone [41]. The disadvantages of strut grafts are their high cost, limited availability, increased danger of infection, and potential for transmitting infection. In addition, remodeling occurs subsequent to the initial incorporation of the strut graft, leading in turn to biomechanical weakness during the first 4–6 months following grafting.

As an alternative, plates that can accommodate cables and screws have been designed, such as the Ogden plate (construct), secured to the proximal fragment by heavy-duty cables and to the distal fragment by (nonlocking) cortical screws [28]. This construct has proven to be significantly stronger than two allograft struts with cables [46]. The relative ease, minimal morbidity, and stability of the technique with the Ogden plate made it popular, but its disadvantages included the potential for stress risers as a result of the transcortical screws, fractures below the plate, prosthetic loosening, and nonunion [28].

7.1 General aspects

Treatment of PPHFs is dependent on characteristics of the fracture such as fracture location, bone stock, prosthesis stability, as well as patient′s age, medical comorbidities, and surgeon experience. Optimal management around a stable femoral prosthesis has not been conclusively established.

Historically, treatment has included nonoperative strategies such as protected weight bearing, traction, and casting or bracing. Nonoperative treatment of unstable fractures has resulted in prolonged inpatient admission and recumbency, which is associated with delayed mobilization and higher nonunion and malunion rate [47].

Modern operative fixation techniques have largely replaced nonoperative ones except for protected weight bearing in highly selected cases. Operative management through internal fixation provides optimal fracture reduction, and a superior biological local environment for healing due to biomechanical stability; this leads ultimately to early mobilization and shorter in-hospital stay [7], while also affording a reduction in systemic and local complications such as malunion and nonunion [48].

Fractures associated with a stable femoral stem can be managed effectively with osteosynthesis principles, which most orthopedic surgeons are familiar with, where stabilization of the fracture with plates, screws, cerclage wires, nails, strut grafts, or a combination is recommended. The goals of surgery should be fracture union, prosthetic stability, and anatomical alignment in terms of axis, rotation, and length, as well as return to preinjury function.

The patient′s final outcome depends on fracture union, implant stability, early functional recovery, and return to preinjury level of independence. Identifying the operative approach and confirming which implants are currently in situ, including the weight-bearing surface used, will facilitate preoperative planning.

Management of PPHFs includes some of the same core principles that apply to osteoporotic fracture fixation in general:

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  Adequate preoperative planning, acknowledging that the extent and stability of the fracture, the degree of bone loss, and bone quality may not be fully appreciated until directly visualized.

  
  
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  Operative approaches that minimize soft-tissue trauma, regardless of the fixation technique. Most important are attempts to preserve the blood supply to the fracture fragments and surrounding soft tissues by limiting operative dissection to the minimum needed for adequate reduction and fixation.

  
  
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  Accurate fracture reduction is helpful to optimize healing, through either open or indirect means. In a simple fracture pattern, the fracture should be reduced as anatomically as possible with a fracture gap of less than 1–2 mm and in comminuted fractures, the fracture zone should be bridged with a plate or nail.

  
  
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  Since the bone is almost always osteopenic/osteoporotic, fixation according to AO principles of relative stability as opposed to absolute stability is recommended, even in simple fractures with anatomical reduction.

  
  
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  The use of robust implants with sufficient length and mechanical fixation is imperative for successful bone healing.

  
  
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  Medical and nutritional therapy to optimize bone biology is essential (see chapter 1.10 Osteoporosis).