Posttraumatic Reconstruction of the Hip Joint







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 https://expertconsult.inkling.com :



  • 56-1.

    Treatment of premature arthrosis and femoroacetabular impingement.


  • 56-2.

    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.


Preoperative Evaluation


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 ).




Figure 56-1


Anterior-posterior (AP) image of the pelvis demonstrating a reverse obliquity intertrochanteric fracture in a patient with a history of femoral head avascular necrosis (AVN) ( A ) treated with a long cephalomedullary nail ( B ). Unfortunately, the patient went on to a mechanical failure with screw cutout and subsequent cavitary erosion of the acetabulum ( C ). This was treated with conversion to a total hip arthroplasty with bone grafting of the defect ( D ). A fully coated cylindrical stem was used for fixation distal to the previously violated metaphysis and a dual-mobility bearing surface was selected secondary to abductor weakness from the previous intramedullary (IM) nail placement and associated partial trochanteric avulsion.

(Images courtesy of Dr. Ryan Nunley, Department of Orthopaedic Surgery, Washington University, St. Louis, MO.)



Figure 56-2


Anteroposterior radiograph of a 35-year-old woman with persistent groin pain 1 year after internal fixation of a displaced femoral neck fracture ( A ) and computed tomography scan demonstrating persistence of a vertical fracture line, confirming nonunion ( B ).


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 ).




Figure 56-3


Valgus osteotomy for ununited femoral neck fracture. A, Pauwels (1976) pointed out that the resultant force (R) across the hip was due to body weight and the muscular force (M) of the abductors. He showed that this force was directed approximately 16 degrees from the vertical plane and approximately 25 degrees from the anatomic axis of the femoral shaft. B, Pauwels demonstrated that the typical femoral neck nonunion was oriented vertically and thus subject to significant shear force produced by the normal hip joint load. He proposed a valgus-producing osteotomy to reorient the nonunion so that it would be subject to compressive instead of shearing forces. C, Note that this osteotomy has obtained compression of the nonunion. However, it has significantly medialized the femoral shaft, which interferes with gait, reduces femoral offset, and produces knee joint malalignment. Current osteotomy techniques try to keep the femoral shaft lateral, principally by using a double-angled fixation device.

(Source: A, Modified from Müller ME: Indications, localization, and pre-operative planning of proximal femoral osteotomies in posttraumatic states. Chapter 7 . In Hierholzer G, Müller KH, editors: Corrective osteotomies of the lower extremity after trauma, Berlin, Heidelberg, New York, 1985, Springer-Verlag. B and C, From Pauwels F: Biomechanics of the normal and diseased hip, New York, 1976, Springer-Verlag, p 83.)



Figure 56-4


Follow-up radiograph after valgus-producing intertrochanteric osteotomy demonstrating femoral neck fracture and osteotomy site union.


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 ).




Figure 56-5


This illustration shows Maurice Müller’s planning of a 50-degree valgus osteotomy for a femoral neck nonunion. The illustrated nonunion is inclined 75 degrees from the perpendicular to the anatomic axis of the femur. Pauwels showed that the resultant force through the hip joint makes an angle of 25 degrees with the femoral axis. Thus, a perpendicular to the resultant force will cross a perpendicular to the femoral axis at 25 degrees. Therefore, the angle of correction (to make the nonunion perpendicular to the resultant force) should be 25 degrees less than the nonunion’s angle relative to the perpendicular, as determined in step b . In this example, the angle of correction is 50 degrees (75 – 25 degrees). The fixation shown is with a 120-degree double-angle Arbeitsgemeinschaft für Osteosynthesefragen (AO) osteotomy blade plate. This plate helps avoid excessive medialization and shortening of the femoral shaft. Compared with Figure 56-2, A, note the lateralization of the femoral shaft. The osteotomy is based on a transverse cut, just above the lesser trochanter. Wedges resected from the lateral portion, proximally and distally, combine to provide a closing wedge configuration. For stable healing, at least one-third of the osteotomy surface must be in contact after fixation. This plate is designed to be inserted with its blade low in the femoral head and parallel to the eventual osteotomy cut of the proximal femoral segment. It should lie at least 15 mm proximal to the osteotomy surface, to preserve a bone bridge of sufficient strength. If the blade is placed this way into the proximal segment, the plate will make an angle with the femoral shaft that equals the desired repositioning angle. The steps of the plan, done with an internally rotated anteroposterior radiographic view, are the following: a. Draw the anatomic axis of the femur, and a line perpendicular to it. b. Determine the orientation of the nonunion, draw a line to represent it, and measure the angle this makes with a perpendicular to the femoral axis. As explained earlier, this angle, less 25 degrees, yields the angle of correction, through which the nonunion plane must be rotated into valgus to match the goal of the osteotomy (in this case, 75 – 25 degrees = 50 degrees). c. Draw the osteotomy baseline, perpendicular to the femoral axis, at a level where it crosses the calcar just proximal to the lesser trochanter. d. Has the femoral head “slipped caudally”? This can be measured on either the superior or inferior surface of the femoral neck, as shown. If so, the resulting deformity can be corrected by displacing the osteotomy planes laterally along the transverse osteotomy baseline a similar distance (d′) . e. From the lateral end of d′, draw a line at an angle of 30 degrees below the transverse osteotomy baseline. This is determined by the plate’s 120-degree angle less 90 degrees, so that the blade’s final position will be parallel to the planned osteotomy. f. On the proximal fragment, and from the same point, draw a line angled 20 degrees upward from the transverse osteotomy baseline. This is calculated by subtracting 30 degrees (see step e ) from the chosen angle of correction. g. Place a guidewire (to orient the seating chisel and blade) as far cranial as possible, and parallel to the proximal osteotomy plane, drawn in step f. A separate extraosseous guidewire is first placed along the anterior femoral neck. The intraosseous wire (g) must be parallel to this and sufficiently anterior to mark the proper intraosseous path of the seating chisel. h. Now draw the seating chisel (h) more distally, also parallel to f, leaving at least 15 mm of bone between the chisel and the osteotomy plane, to ensure good fixation of the blade in the proximal femoral segment. The tip of the seating chisel should extend as far as possible into the lower half of the femoral head. Its length corresponds to the length of the blade to be chosen using acetate implant templates (give available values). During the operation, the seating chisel will be placed, and loosened, for easy removal before the osteotomies are carried out. i. Although fluoroscopic targets can be planned for both guidewire (g) and seating chisel (h) from the drawing as described earlier, further help with orientation of the seating chisel is provided by calculating the angle it must make with the femoral axis (180 – 120 degrees = 60 + 50 degrees repositioning angle = 110 degrees). It is also important to remember that the blade must lie parallel to the anteverted axis of the femoral neck and anteriorly enough so that it does not pass through the posterior cortex of the neck, potentially to injure the blood supply to the femoral head. j. Check the drawing by placing the acetate template of a 120-degree double-angle plate (k) over it, with the blade lying over the seating chisel. The angle between the plate and the femoral shaft should be that of the 50-degree repositioning angle, so that once the osteotomy is completed and the plate is fixed to the femoral shaft, the desired correction is achieved. At this stage, one should make, and check, a tracing of the completed osteotomy, positioning proximal and distal femoral segments as intended and then drawing the plate into its intended position. It is important to remember that proper application of the blade plate is essential to achieve secure interfragmentary fixation.

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Jun 11, 2019 | Posted by in ORTHOPEDIC | Comments Off on Posttraumatic Reconstruction of the Hip Joint

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