Posttraumatic hip degenerative joint disease due to acetabular or proximal femoral fracture is multifactorial in etiology. There are three primary reasons that a patient might develop posttraumatic arthritis: (1) articular damage of the hip joint, (2) osteonecrosis, and (3) malunion. The direct anterior approach (DAA) was rarely used historically for open reduction and internal fixation of acetabular and proximal femoral fractures. The primary concerns after acetabular and proximal femur fracture include soft tissue loss and injury, preexisting hardware, infection, bone loss, and heterotopic ossification. There are many theoretical advantages to DAA THA for these patients, but techniques of hardware removal and prophylaxis against future fracture are of particular concern and difficulty when using the DAA. In addition, the posttraumatic patient will often face recovery challenges due to their polytrauma, including reconstructed injuries to other extremities and amputations along with the psychological effects of trauma limiting the recovery potential.

The conversion of prior proximal femur or acetabular fracture to THA is associated with 19% greater costs, increased surgical times, and perioperative complications.^1,2 To mitigate risk, a careful preoperative evaluation of the PTOA hip patient should include a thorough history and physical including the soft tissues, the neurologic status, infection as an underlying confounding variable, bone loss associated with prior fracture, nonunion, and malunion. If possible, the original injury radiographs and operative reports should be attained and carefully interpreted. The patient will often be able to recall if they had a period of extended wound care or infection following a trauma and if the injury was open or closed and be able to tell the surgeon about residual concomitant injuries that might affect their outcome from arthroplasty. They should specifically be asked to recall any history of wound healing difficulties, oral antibiotic prescriptions, or frank infection.

Soft tissue evaluation includes visualization of all incisions on the extremity. Although the radiographs may suggest a particular surgical approach, it is not uncommon for the sentinel surgeon to have done multiple procedures and to have performed osteotomies and/or tenotomies that allow for the placement of hardware at the time of injury that can make removal quite difficult. An example of this is an acetabular fracture repaired through an extended iliofemoral approach in which hardware will not be visualized well through either an anterior or posterior approach to the hip. If neither approach provides adequate exposure without osteotomy or tenotomy, the reconstructive surgeon should consider the possibility of hardware retention (Figure 34.1).

The appearance of the surgical incisions will often provide clues as to how difficult it was for the patient to heal their incisions at the time of the trauma. An incision that healed either invaginated or stretched suggests that they might have had an extended period of drainage, putting them at higher risk of having local bacterial colonization that might never have manifested a significant infection.

Neurovascular injury is not uncommon in acetabular and pelvic ring injuries. This can include sciatic or femoral palsies along with gluteal nerve injuries. This may manifest itself as distal neurologic compromise including muscular or sensory dysfunction, which can complicate postoperative mobilization. In addition, if a patient uses an ankle-foot orthosis or similar device for a foot drop, they might have significant difficulty with increased leg length imparted at the time of joint reconstruction. This can lead to difficulties clearing their toe and be predictive of future falls that can compromise their reconstruction.

Other challenges include gluteal atrophy due to neurologic dysfunction, which can manifest with a Trendelenburg stance or gait during gait evaluation. If there is any question as to the neurologic function of the posttraumatic patient, consideration should be made for an electromyogram or functional gait analysis. Particular attention should be paid to the patient with a lower extremity amputation. This will affect the ability or method by which a specialty table can be used if desired, and also the alteration of leg length will have a significant impact on the prosthesis and potentially the patient might need a new device, which can be prohibitively expensive if not covered by insurance. Utilization of care coordination is critical to ensure a good outcome for the patient.

The most critical part of the preoperative evaluation is the evaluation for infection. The typical workup is quite similar to that done for the revision total joint patient. The decision tree includes conversion of prior hip surgery to total hip replacement with retained hardware, removal of hardware in a staged fashion and subsequent treatment for infection before replantation, or even excisional arthroplasty with an antibiotic spacer when suspicion of intra-articular or periarticular infection or history thereof exists. A preoperative complete blood count; erythrocyte sedimentation rate; C-reactive protein; and an aspiration of the hip joint for alpha defensin, cell count, and culture and sensitivity are also obtained. When any of these tests are elevated or culture positive, staged care should be discussed with the patient. Caution is taken when excisional arthroplasty is undertaken because bone loss associated with acetabular fixation can compromise the joint, making an articulated antibiotic spacer exceedingly difficult and at higher risk for dislocation.

Bone loss is common following both acetabular and femoral fractures. Most commonly, it will be associated with acetabular wall fractures, but it is also a component part of the removal of hardware associated with total joint
replacement. Preoperative evaluation with a computed tomographic (CT) scan is moderately helpful along with the evaluation of the hardware-bony interface to search for areas of lucency, suggesting aberrant motion. Around the acetabulum, it is not uncommon for parts of the posterior wall to remain ununited. In addition, acetabular patterns that include significant impaction will oftentimes have intra-articular bone loss that will require a larger acetabular component to supplement the soft nonunited articular and subchondral elements. In our institution at Yale, much work is underway towards creating 3D renderings of complex bony defects and deformities, work that intends to both improve the preoperative planning process for surgeons and improve the outcomes for patients following complex injuries and reconstructions.

Proximal femoral bone loss is less common but can be significant in the patient with osteoporosis who undergoes conversion and needs cannulated screws or cephalomedullary devices removed. This leaves a defect that is not present preoperatively but is intraoperatively. Careful planning should be carried out to have all backup supplementary plates, cables, and screws available if needed. Malunion of the pelvis, acetabulum, and proximal femur should be carefully considered. This is most complex when evaluating a pelvic fracture that has healed. Oftentimes, these patients have a stiff lumbopelvic junction that can increase the risk of dislocation after THA as discussed in a prior chapter on the spine-hip relationship. In addition, sometimes the malunited pelvic bone will not easily accommodate a malpositioned acetabular component. Lateral compression injuries often heal with a flexion and internal rotation deformity, which increases offset for the proximal femur and can create the need for significantly more anteversion than otherwise expected. Anterior column posterior hemitransverse and associated both column fractures heal in a medialized position when malunited, which can lead to decreased offset.

Femoral head fractures are often treated with subchondral screws, which are easily extracted during removal of the femoral head as a unit. If the femoral head fracture was repaired from a prior DAA, heterotopic bone can often be encountered in the tensor fascia lata or rectus origin, especially if a rectus tenotomy had been previously performed. If a femoral head fracture is repaired from a posterior approach, a digastric trochanteric osteotomy from a surgical hip dislocation might be encountered with small fragment screws in place from a lateral approach. Accessory percutaneous or mini-open incisions can be used to extract the screws that were applied to the proximal femur for osteotomy repair, or the DAA incision can be extended in a “lazy S” along the lateral femur and dissection carried under the tensor fascia lata with the femur internally rotated.

Stable femoral neck fractures (Garden 1 and 2) have been operatively stabilized with cannulated screw fixation or with the Femoral Neck System (DePuy Synthes, Warsaw, IN, USA) in more recent years. The conversion rate of open reduction and internal fixation of osteoporotic femoral neck fractures to total hip or hemiarthroplasty is 10%.³ Young patients with femoral neck fractures demonstrate an increased predilection toward conversion to arthroplasty across their lifetime.⁴ Conversion of these patients is quite amenable to the DAA. The challenges that are encountered during removal can be predicted preoperatively. The preoperative radiographs often demonstrate a significant defect on the lateral cortex when the screws are placed in a clustered pattern. This can predict both a malunion of the femoral neck and also create a stress riser in the proximal femur that should be stabilized using a trochanteric claw plate at the time of arthroplasty (Figure 34.2).

Removal of the Femoral Neck System involves the use of proprietary devices from a counterincision of the lateral aspect of the femur. The derotation screw should be extracted first followed by the shaft screws and then backing out of the bolt with the plate. The plate should not be turned during removal because this is not a screw-type system. Patients who have undergone multiple surgeries for their femoral neck fracture including valgus intertrochanteric osteotomy present a malunited deformed problem for the reconstructive surgeon (Figure 34.3). The DAA allows for intraoperative evaluation of leg length and avoidance of posterior soft tissue releases that can result in a need for increased offset and length that might be untenable to the middle-aged patient.

Femoral neck and pertrochanteric fractures present the greatest difficulty on the femoral side. The pathways of bone that are filled with hardware can leave large voids in critical areas and might require prophylactic stabilization or bone grafting to deal with defects.⁵ Identification of the type of hardware encountered is helpful because there are proprietary removal devices that can aid in removal. However, caution must be maintained because many times fixation constructs that are designed for elderly osteoporotic bone might be used for young patients, therefore resulting in hardware that might be nearly impossible to remove without deconstructing the femur. The use of cephalomedullary devices can significantly hinder removal attempts because the lag screw can be incarcerated within good bone and screws used in these devices often have no reverse cutting capability. We recommend the removal of hardware before any other part of the arthroplasty (dislocation) in order to ensure safe removal before committing to the definitive surgery.

When performing the removal of intramedullary hardware concurrent with DAA total hip replacement, the ipsilateral arm should be prepared across the chest to facilitate nail removal (Figure 34.4). The use of a radiolucent table is helpful in localizing the screws and nails because they are often covered by bone and the DAA will not allow for easy visualization of the top of the nail. The surgeon might consider not performing the DAA when an extensive amount of heterotopic bone covers the lateral access point to the proximal femur. Percutaneous accessory incisions should be made along the lateral thigh; the set screw is backed out or removed depending on the manufacturer’s recommendations and the available nail removal devices. The lag screw or spiral blade is removed, the selected extraction bolt is engaged, the distal interlock is removed, and the nail is backed out. Be sure to remove all bone on the lateral femur that could prevent lag screw motion and possibly use a trephine to open the bone lateral to the nail.