Arthroplasty for Pertrochanteric Hip Fractures




The mainstay of treatment of pertrochanteric fractures is internal fixation using a sliding hip screw or a cephalomedullary device. However, in patients with ipsilateral hip osteoarthritis or avascular necrosis of the femoral head, or inflammatory arthritis, arthroplasty should be considered as the primary treatment modality to reduce the likelihood of a secondary procedure. Unstable fracture patterns with concomitant poor bone quality represent a challenge for internal fixation, with high rates of lag screw cut-out and hardware failure. Prosthetic replacement for unstable pertrochanteric fractures has therefore been considered as an alternative primary treatment option. Further prospective randomized trials are required.


Key points








  • The mainstay of treatment of pertrochanteric fractures is internal fixation using a sliding hip screw or a cephalomedullary device.



  • Arthroplasty should be considered as a primary treatment modality in patients with ipsilateral hip osteoarthritis or avascular necrosis of the femoral head, inflammatory arthritis, unstable fracture patterns with poor bone quality, or neglected fractures.



  • Trochanteric slide osteotomy preserves the abductor mechanism and the posterior structures of the hip.



  • Cemented stems with or without calcar replacement, uncemented extensive porous-coated cylindrical stems, or uncemented tapered stems can be used to reconstruct the femur.



  • Arthroplasty is associated with higher postoperative blood transfusion rates, but a shorter time to weight bearing and a lower failure rate.






Introduction


Hip fractures remain a leading cause of morbidity and mortality in an aging population and are projected to reach 289,000 cases/y in the United States by 2030. Hospital and rehabilitation needs and loss of patient mobility and independence account for a significant burden to the health care system. Pertrochanteric fractures account for half of all hip fractures in the elderly. Compared with femoral neck fractures, pertrochanteric fractures tend to occur in older patients with worse baseline function and greater medical comorbidities. Approximately 50% to 60% of pertrochanteric fractures are considered unstable, increasing the technical difficulty of internal fixation. Despite significant advances in internal fixation methods and implants there remains a significant failure rate of fixation in unstable pertrochanteric fractures ( Fig. 1 ). Failed pertrochanteric fracture fixation is associated with significant loss of mobility with additional morbidity, mortality, and costs. The goals of care for patients with pertrochanteric fractures include expeditious and safe surgical stabilization to enable rapid mobilization and avoidance of medical complications. Arthroplasty may be considered an effective alternate treatment to internal fixation and may be associated with improved early mobilization and lower failure rates.




Fig. 1


Preoperative radiograph ( A ) of an unstable pertrochanteric hip fracture (reverse oblique) treated with cephalomedullary nail. Fixation went on to fail with lag screw cut-out ( B ).




Indications


Arthroplasty should be considered as a primary treatment option in a carefully selected and small patient population with pertrochanteric fractures ( Box 1 ). Patients with preexisting hip osteoarthritis, inflammatory arthritis, or avascular necrosis are good candidates for total hip arthroplasty even at younger ages because it reduces the likelihood of subsequent reoperations. In these patients, the diminished range of motion of the hip joint increases the loads at the fracture site, possibly increasing the failure rate of internal fixation. In low-functioning elderly patients (age >75 years) with unstable fracture pattern and poor bone quality, arthroplasty may be particularly useful to avoid the extended periods of protected weight bearing required when there is tenuous internal fixation. Appropriate fracture features include grossly unstable fracture patterns, marked fracture comminution, poor bone quality shown by thin cortices and wide intramedullary canal, and significant fracture displacement indicating a more severe insult to surrounding soft tissue structures.



Box 1





  • Ipsilateral hip osteoarthritis



  • Ipsilateral avascular necrosis of the femoral head



  • Inflammatory arthritis



  • Unstable fracture pattern with poor bone quality



  • Complications of internal fixation (ie, lag screw cut-out)



  • Neglected fractures



Indications for arthroplasty in pertrochanteric fractures




Identification of unstable fractures


Identifying a fracture pattern as unstable is of great importance because these fractures have a high failure rate with internal fixation. Although often impractical in the preoperative setting, an anteroposterior view with internal rotation and gentle traction offers the best assessment of ease of reduction and instability. Computed tomography scan of the hip may provide further information on the number and displacement of fracture fragments. Multiple classifications systems have been devised to guide treatment. Evans (1949) was the first to classify pertrochanteric fractures based on stability. The orthopaedic trauma association (OTA) classification system, based on the arbeitsgemeinschaft für osteosynthesefragen (AO) comprehensive classification, is probably the most commonly used classification for pertrochanteric fractures ( Fig. 2 ). This system classifies fractures based on number and orientation of fracture lines but does not account for displacement or fracture alignment. Unstable OTA fracture types are those with extensive posteromedial comminution and reverse oblique or subtrochanteric fracture lines (ie, AO/OTA types A2.2, A2.3, A3.1, A3.2, and A3.3). Other fracture features indicating instability and high rate of internal fixation failure are varus alignment and gross displacement. The hallmarks of poor bone quality in plain radiographs include thin cortices and cylindrical shape of the femoral canal.




Fig. 2


AO/OTA classification of unstable pertrochanteric hip fractures. Types A2.2, A2.3, A3.1, A3.2, and A3.3 are considered as unstable fractures.




Surgical techniques


Surgical Approach


Surgeon preference and experience as well as fracture pattern are important considerations when deciding on an approach for arthroplasty in the setting of an unstable pertrochanteric fracture. The most commonly used hip arthroplasty approaches, direct lateral (or modified Hardinge) and posterior approaches are acceptable choices and carry the advantage of familiarity to the surgeon. Each of these approaches has its own distinct disadvantages in the setting of an unstable fracture pattern: the direct lateral approach may cause further insult to the injured abductor musculature, whereas the posterior approach may be complicated by postoperative instability. A modified trochanteric slide osteotomy is an alternative approach that is useful when the greater trochanter is fractured, and carries advantages of preserved abductor mechanism and posterior structures. Regardless the approach selected, the patient is positioned in the lateral decubitus position and prepped such that the contralateral knee can be palpated through the drapes to give a reference for leg lengths. Our protocol has been to use a trochanteric slide osteotomy unless the greater trochanter and lateral wall of the femur remains intact (ie, type A1 and A2.1 fractures), in which case we use a transgluteal approach.


Modified Trochanteric Slide Osteotomy


Unstable pertrochanteric fractures with fracture lines running to or below the rough line of the greater trochanter (AO/OTA types A2.2, A2.3, and A3.1–3.3) are particularly amenable to approach with a modified trochanteric slide osteotomy. Popular in revision hip arthroplasty and complex primary hip arthroplasty, a trochanteric slide osteotomy uses existing fracture lines while maintaining the continuity of the abductors, greater trochanter, and vastus lateralis. This technique uses a laterally based approach to the hip with a coronal oriented osteotomy commencing lateral to the insertion of the posterior capsule and external rotators ( Fig. 3 A). In most cases, the trochanter is fractured off as a separate fragment, so an osteotomy may not be required. The piriformis is easily palpated and remains medial to the osteotomy, thereby preserving the external rotators. The osteotomized trochanter with attached glutei and vastus lateralis are retracted anteriorly after reflection of minimus off the hip capsule (see Fig. 3 B). The remaining femoral shaft is externally rotated and an anterior capsulotomy is performed, providing excellent access to the fractured femoral head and neck ( Fig. 4 A). The femoral head and neck is then removed from the acetabulum by releasing its capsular attachments and the ligamentum teres (see Fig. 4 B).




Fig. 3


Trochanteric slide osteotomy with fascia lata and gluteus maximus removed. Osteotomy ( dotted red line ) is performed superficial to the insertion of the piriformis and short external rotators ( A ). The trochanteric osteotomy with attached gluteus medius and vastus lateralis is retracted anteriorly to expose the hip capsule ( B ).



Fig. 4


The leg is externally rotated and placed in a sterile leg bag to provide excellent visualization of the fractured femoral head and neck ( A ). The fractured head and neck may be removed from the acetabulum with the greater trochanter retracted anterior and the femoral shaft retracted posterior ( B ).


Implant Choice


Cemented and uncemented prostheses are available and have both been used with success for unstable pertrochanteric fractures. Cemented implants offer the advantage of immediate stability without the need for bone ingrowth and show acceptable middle-term to long-term results with modern cementing techniques. Cemented stems are recommended in patients with very thin cortical bone in the femoral diaphysis, making insertion of uncemented diaphyseal fitting stems difficult and increasing the risk of periprosthetic fracture ( Fig. 5 A). Comminuted pertrochanteric fractures generally have significant proximal femoral bone loss and therefore we favor a cemented implant with a calcar-replacement option (see Fig. 5 B).




Fig. 5


Preoperative radiograph of an unstable pertrochanteric hip fracture (reverse oblique) with thin femoral cortices ( A ). Postoperative radiograph showing treatment with a cemented calcar replacing femoral stem ( B ). A trochanteric slide osteotomy was used for the approach and the osteotomy was repaired using cerclage wires.


The major disadvantage of cemented prostheses is bone cement implantation syndrome, which is characterized by perioperative events such as hypotension, hypoxia, and confusion. Cement implantation syndrome occurring in the setting of cemented hemiarthroplasty for pertrochanteric fractures has an intraoperative mortality of 1.6%. Patients with impaired cardiopulmonary function are at particular risk of complications from cementing procedures. Cement fixation also generally adds 20 to 30 minutes to the procedure. Furthermore, healing of the trochanteric fracture or osteotomy may be compromised by the presence of cement within the proximal femur.


Uncemented femoral stems have been used extensively in the treatment of Vancouver B2 and B3 periprosthetic femoral fractures. Uncemented fixation has gained popularity for the treatment of hip fractures in general, and offers the advantage of avoiding cement-related complications in this vulnerable patient population. Other advantages include reduced operative time and blood loss. Several recent randomized controlled trials studying intracapsular hip fractures report excellent short-term results and equivalency to cemented hemiarthroplasty with regard to functional outcome, complications, and mortality. Common concerns regarding the use of uncemented components in the fracture setting include thigh pain and higher risk of periprosthetic fracture ( Box 2 ).


Oct 6, 2017 | Posted by in ORTHOPEDIC | Comments Off on Arthroplasty for Pertrochanteric Hip Fractures
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