Additional videos related to the subject of this chapter are available from the Medizinische Hochschule Hannover collection. The following videos are included with this chapter and may be viewed at expertconsult.inkling.com :
Treatment of premature arthrosis and femoroacetabular impingement.
Hip joint arthroscopy in the treatment of a degenerative hip joint.
Salvage of failed hip fixation is becoming a more common occurrence, as the absolute number of fractures involving the hip joint continues to increase. Although most fractures of the femoral neck and pertrochanteric region heal with contemporary methods of internal fixation, those that do not require advanced reconstruction techniques and demand a high level of technical acumen from the treating surgeon. Obstacles including osteopenia, elevated infection risk, potential for instability, altered anatomy, retained hardware, and medical comorbidities complicate patient care in this clinical setting. Salvage options for failed hip fixation can be subclassified based on two major variables: patient age and fracture location. Other important considerations include femoral head viability, patient activity level, and bone stock availability. This chapter reviews the preoperative evaluation, treatment algorithm, and reported results of salvage options for failed hip fixation.
The preoperative evaluation of failed internal fixation must begin with an investigation as to why the initial fracture management failed. Infection must foremost be ruled out as a means of early failure. A history of wound problems, prolonged postoperative antibiotics, or washout procedures should be sought. Inflammatory markers including C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) are obtained routinely. In patients who present with a suspicious history or have elevated laboratory markers, an aspirate of the hip is obtained and sent for a cell count with differential, Gram stain, and cultures. If prosthetic replacement is the planned salvage strategy, tissue for frozen section analysis is also obtained intraoperatively to rule out acute inflammation prior to implantation of arthroplasty components. In instances when an infection is encountered, a staged approach is favored by the authors with irrigation, débridement, and resection of the infected tissues and bone; placement of an antibiotic spacer; and staged arthroplasty procedure to be performed following a course of culture and sensitivity directed antibiotic therapy.
Mechanical failure secondary to poor implant selection, placement, or osteopenia requires additional consideration. Most cases of failed fixation do not represent a diagnostic challenge. Excessive fracture settling with hardware penetration into the joint, fracture migration, and broken hardware often present as obvious indicators in the setting of pain ( Fig. 56-1 ). More subtle findings, such as a persistent limb or difficulty with weight-bearing, in the absence of these classic radiographic findings, may warrant advanced imaging with computed tomography (CT) or magnetic resonance imaging (MRI) (in the case of titanium implants) ( Fig. 56-2 ).
In young patients, additional diagnostic attention must be paid to femoral head viability. Efforts to preserve bone stock and a native joint are paramount in the younger population. Radiographic evidence of collapse may require treating surgeons to alter their approach to joint salvage. MRI or bone scintigraphy can be helpful in assessing the articular cartilage and femoral head viability in cases where obvious collapse is absent and joint preservation is being considered.
Finally, medical optimization must be performed prior to the salvage procedure. A nutritional assessment should be performed to ensure the best chances for wound healing. Medical comorbidities including tobacco use, obesity, and diabetes should be addressed, and preoperative intervention strategies should be implemented when timing permits.
Salvage of the Young Hip
Failed Femoral Neck Fixation
The main goal of salvage procedures for failed fixation in the setting of femoral neck nonunion occurring in a young patient is preservation of the native hip joint, thereby avoiding early prosthetic replacement. Salvage options often involve optimizing fracture biomechanics or biology through osteotomy and revision fixation or bone grafting, respectively.
Valgus-Producing Osteotomy: Overview and Historic Results
Increased fracture line verticality and the resultant shear forces impair construct stability and detract from compressive forces that would otherwise contribute to osteosynthesis. Pauwels classification for femoral neck fractures focuses on this aspect of fracture morphology and studies have shown that an increased Pauwels angle is best addressed mechanically with a fixed-angle construct.
Failed femoral neck fracture fixation in a young patient with an increased Pauwels angle should undergo a valgus-producing osteotomy, thus transforming shear forces to compressive forces across the fracture site ( Fig. 56-3 ). Marti and colleagues reported a series of 50 patients with a mean age of 53 years treated with valgus intertrochanteric (IT) osteotomy for femoral neck nonunion. Eighty-six percent of nonunions united in a mean of 4 months. Of the 22 patients who had radiographic evidence of osteonecrosis (without collapse) at the time of osteotomy, only 3 (14%) showed progressive collapse of the femoral head, necessitating hip replacement. Anglen reported a series of 13 patients who were followed a mean of 25 months after valgus osteotomy for failed internal fixation of a femoral neck fracture. All fractures healed, and 11 of 13 had good to excellent results. Two patients (15%) later were converted to arthroplasty caused by osteonecrosis. Ballmer and coworkers reported a series of 17 patients with nonunions of the femoral neck treated with valgus-producing osteotomies. Twelve of seventeen (70%) healed with one procedure. Three patients required revision fixation but eventually healed, increasing the overall union rate to 88%. Three patients (17%) had progressive avascular necrosis and required hip arthroplasty. Thus, even with areas of osteonecrosis, the results of salvage of the femoral head can be good ( Fig. 56-4 ).
Valgus-producing osteotomies can also be useful when nonunion has led to shortening of the femur and additional length is needed. Wu and associates compared the use of a sliding compression screw with and without subtrochanteric valgus osteotomy for femoral neck nonunions in 32 patients with a mean age of 38 years. All of the nonunions healed at a mean of 4.6 months. Although there were fewer complications in the nonosteotomy group, the author recommended valgus osteotomy for patients with shortening of more than 1.5 cm, because the valgus osteotomy helps gain leg length.
Valgus-Producing Osteotomy: Author’s Preferred Technique
In the senior author’s experience, most femoral neck nonunions in younger patients are caused by mechanical rather than biologic reasons. The original fractures, and subsequent nonunions, typically have high shear angles (Pauwels type III), are shortened, and are aligned in varus. Thus, the author’s preferred salvage operation is the valgus-producing IT osteotomy.
The technique of valgus-producing IT osteotomy has been well described, particularly by Maurice Müller. The principles involve converting a vertically oriented fracture to a more horizontally oriented fracture, thus minimizing the shear forces at the fracture site and promoting union. To be perpendicular to the joint reaction force resultant, the nonunion plane should make an angle of 20 to 30 degrees perpendicular to the femoral axis. Thus, the angle of the laterally based IT wedge to be removed is the difference between the angle the nonunion makes with such a perpendicular and its desired orientation after osteotomy (the repositioning angle). For example, a patient with a 75-degree nonunion would need a 50-degree wedge resected from the IT region to properly reorient the nonunion ( Figs. 56-5 and 56-6 ).