Revision Arthroplasty for Periprosthetic Femoral Fracture




Introduction


Periprosthetic femoral fracture complicating hip arthroplasty is relatively common. The reported incidence is just below 1% after primary reconstruction and up to 4.2% after revision surgery. These cases present a challenge to the orthopedic surgeon because the fracture is often complicated by significant osteopenia, bone loss, and multiple medical comorbidities that make the patient intolerant of a physiologically taxing surgical procedure and prolonged postoperative weight-bearing restrictions.


Optimal treatment remains unclear, although conventional teaching advocates surgical reduction and fixation of fractures with a well-fixed stem and revision arthroplasty bypassing the fracture in cases of total hip implant instability. The Vancouver classification has proved valuable in guiding the surgeon because it has high interobserver and intraobserver reliability. Treatment can be implemented based on this classification, which takes into account the fracture location and stem stability. This premise has been challenged recently, and superior results have been reported with stem revision compared with open reduction and internal fixation, even in cases with well-fixed femoral components.


The decision to use fixation or revision arthroplasty is based on fracture- and patient-related factors. We present a technique for revision arthroplasty that is applicable in all scenarios in which there remains an intact isthmus distal to the fracture.




Surgical Technique


Most periprosthetic femoral fractures are low-energy injuries with only modest displacement that often is partially splinted by the femoral stem. The fractures may be initially managed with adequate analgesics and bed rest while awaiting definitive care. High-energy fractures with significant displacement and ongoing fracture motion are best managed initially with balanced skeletal traction if surgical intervention is delayed.


Examination and Imaging


The preoperative medical evaluation is routine. Although not urgent, the time to definitive surgical care should be minimized to avoid the well-documented increase in morbidity and mortality in the hip fracture population. The previous operative reports and implant record should be obtained if feasible.


Standard radiographic evaluation includes an anteroposterior radiograph of the pelvis, anteroposterior and cross-table lateral radiographs of the affected hip, and full-length views of the femur. Occasionally, computed tomography may help in assessing the fracture morphology, particularly a minimally displaced Vancouver B fracture pattern.


Preoperative Planning


The importance of surgical experience cannot be overstated when revision arthroplasty for periprosthetic fracture is contemplated. This type of revision requires a large exposure and involves considerable blood loss, even when performed with utmost efficiency. To minimize operative time and complications, preoperative planning is essential.


Every effort is made to identify existing implants for ease of removal and to have an appropriate modular liner available for exchange. Surgical exposure is planned based on the fracture pattern. Radiographic templating assists in determining the appropriate length and diameter of femoral stem needed to bypass the fracture. Vertical length from the fracture to the hip center of rotation may be measured, which can be useful for crosschecking intraoperative measurements.


Planning adjunctive fracture fixation techniques preoperatively enables faster operative decision making and ensures the appropriate materials are readily available ( Box 72.1 ). The following technique is described for a modular, tapered, fluted stem and conical proximal body. We have found this construct to be superior based on several factors:




  • Secure distal fixation (axial and rotational) with even a short length of intact isthmus (1-2 cm)



  • A modulus of elasticity resembling bone that minimizes thigh pain and allows proximal fracture remodeling



  • A conical proximal body that allows anatomic fracture fixation with femoral version not limited by proximal femoral geometry



  • Proximal modularity that allows fine-tuning of the length and offset after implanting the definitive distal segment



Box 72.1


Acetabular Side





  • Modular liner for existing cup



  • Acetabular explant system



  • Revision acetabular cup



  • Cemented polyethelene liner (if cementing liner into well-fixed cup is a consideration)



Femoral Side





  • Revision stem of adequate length



  • Cerclage cable system



  • Allograft femoral strut



  • Trochanteric cable and plate system



  • Large bone-holding or bone-reduction clamps



  • Allograft cancellous graft



Preoperative Checklist




Procedure


Mechanical and chemical prophylaxis for deep venous thrombosis is initiated on presentation if surgery will be delayed longer than 24 hours, and preoperative antibiotic prophylaxis is routine. Antiseptic preparation and draping are performed to allow exposure of the entire length of the femur. Blood-conservation techniques are used, and allogenic blood should be readily available.


A peg board or equivalent positioning table is used. Although not routine, acetabular revision may be indicated based on intraoperative findings, and appropriate pelvic positioning aids in determining the cup position and functional range of motion after reconstruction.


A lateral approach to the femur allows visualization of the fracture. Great care is taken to ligate perforating vessels. At this point, distal dissection is limited to the fracture site to minimize ongoing blood loss as proximal preparation proceeds.


Step 1. Prophylactic Cable


After exposing the fracture, a cerclage cable is placed at the most proximal aspect of the intact distal femur. This minimizes the risk of fracture propagation distally and the potential loss of an intact isthmus that could compromise stem fixation ( Fig. 72.1 ).




FIGURE 72.1


A, Radiographs demonstrate a Vancouver B2 fracture pattern in this 82-year-old female presenting with pain after a ground level fall. Note the intact isthmus distal to the fracture visualized on the anteroposterior hip and lateral femur projections. B, After surgical exposure of the fracture, a cerclage cable has been placed on the most proximal aspect of intact distal femur to minimize the risk of fracture propagation during femoral preparation.


Step 2. Proximal Exposure


Preoperative planning based on the fracture pattern and stem stability and the decisions made intraoperatively dictate the next phase of exposure. If the fracture pattern has left the proximal segment as an intact tube and it is anticipated that the stem can be removed with relative ease (i.e., loose stem or well-fixed stem with adequate proximal bone to allow removal without excessive destruction), a posterior exposure is performed. If the initial reconstruction was done through a posterior approach, a single-layer posterolateral peel is performed off the femur and carried proximally to include the capsulotomy.


The hip is then dislocated posteriorly. A large bone-holding forceps is required to effect flexion and rotation of the short proximal segment. A bone hook around the femoral neck lessens the force required through the short proximal femoral segment. The stem is then removed, working proximally and distally through the fracture. Care is taken not to create an uncontrolled fracture of the proximal segment, particularly in the greater trochanter. If difficulty is encountered, converting to a controlled femoral osteotomy can better manage removal. Exploiting a proximal fracture or creating a femoral window through an extended trochanteric osteotomy allows much easier stem removal in a controlled setting.


In the case of a Vancouver B pattern, the typical spiral fracture line is followed proximally and if necessary completed posterolaterally. The plane between gluteus minimus and capsule is defined and carried anteriorly. The trochanteric segment is reflected anteriorly through the fracture, and an anterolateral arthrotomy is performed, leaving the posterior soft tissue hinge intact to the proximal femur. The exposed stem may then be removed ( Fig. 72.2 ).




FIGURE 72.2


The limb is prepared and draped to allow exposure of the length of the femur. A, Lateral exposure of the femur has been performed to the level of the fracture. Proximally, the spiral fracture has been exploited, and the greater trochanteric segment is reflected anteriorly. B, An anterolateral arthrotomy has been performed, leaving the capsule and rotators intact to the posterior aspect of the proximal femur.

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May 29, 2019 | Posted by in ORTHOPEDIC | Comments Off on Revision Arthroplasty for Periprosthetic Femoral Fracture
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