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    A Case of Periprosthetic Fracture 15 Years after THA

    A 75-year-old patient presents after a fall at home, and she is diagnosed with a Vancouver B1 periprosthetic femur fracture. She had also been diagnosed 3 months earlier with a stress fracture of the left thigh. What is the appropriate treatment for this patient – and why did it fail?

    Author

    Brandon J. Yuan, MD

    Patient Presentation

    A 75-year-old female patient with a history of rheumatoid arthritis, aortic stenosis, and hypertension presents with a closed periprosthetic femur fracture of the left hip she had sustained in a fall at home. Her surgical history is notable for a previously well-functioning uncemented left total hip arthroplasty performed at another institution 15 years prior.

    The patient reports that she had developed left thigh pain 3 months ago and had been told by her local physician that she had a stress fracture in the left thigh. She had been using a cane for ambulation before this fall. Of note, she has not been treated for osteoporosis with bisphosphonates.

    Previous radiographs of the implant were not available for comparison, but current radiographs (Figure 1) show no evidence of implant subsidence, femoral osteolysis, or radiolucent lines about the femoral component. They do show, however, a Vancouver B1 periprosthetic fracture, or a fracture at the tip of a well-fixed stem of a hip arthroplasty. Appropriate treatment for a periprosthetic femoral fracture about a well-fixed stem is open reduction and internal fixation (ORIF), whereas Vancouver B2 or B3 fractures – periprosthetic femur fractures with a subsided or loose stem – require femoral component revision.

    Figure 1. Radiographs showing a Vancouver B1 periprosthetic fracture 15 years after the initial total hip arthroplasty.

    Initial Treatment and Follow-Up

    I performed ORIF of the fracture with placement of a laterally based locked plate. Proximal fixation included 2 braided cables, 2 unicortical locking screws, and 1 bicortical locking screw. A long precontoured distal femoral plate was utilized to protect the entire femur, given the history of a stress fracture (Figure 2).

    Figure 2. Radiographs showing the construct for fixation of the periprosthetic fracture.

    The choice of proximal fixation in Vancouver B1 periprosthetic fractures is controversial. However, biomechanical studies have demonstrated superiority of unicortical locked screws over cables alone, and at least 2 studies have shown that the addition of cables to unicortical locked screws shows minimal benefit in rigidity. It is important to note that in many of these studies, at least 4 unicortical locking screws were used in the proximal fragment.

    Bicortical locked or unlocked screws also have shown a benefit in rigidity over unicoritical locked screws or cables. Some plates allow for application of locking screws at multiple angles so that they can be directed around a medullary implant, such as the most proximal screw in this case.

    My preference is for placement of bicoritical non-locked screws directed around the implant in the proximal fragment. Non-locked screws have the advantage of allowing:

    • Use of the plate as a reduction aid (compressing the plate to the bone)
    • Application through a small incision, with minimal soft tissue insult
    • Creation of a more rigid construct than with cables alone

    Cables are utilized as a reduction aid in the area of the femur that will not accommodate a bicortical screw due to the presence of the medullary implant, as seen in this case. Locking screws (bicortical or unicortical) should be applied only after all non-locking screws and cables have been placed and tightened, as placement of the locking screw will prevent subsequent compression of the plate to the bone by the cable or non-locking screw.

    Following surgery, the patient initially did well, but she subsequently developed recurrent left thigh pain and presented back at 3 months postoperatively. Radiographs demonstrated failure of the initial construct by pull-out of the proximal screws and mechanical failure of the braided cables (Figure 3). For this patient, the proximal fixation was inadequate to allow for stability until osseous union occurred.

    Figure 3. Radiographs showing failure of the initial fracture fixation procedure.

    What Went Wrong?

    The bending forces on a fracture in the proximal femur are substantial, and in this case, the tension on the lateral side (the side of plate application) was clearly enough to wear through 2 cables and to pull out 3 screws, with 1 screw pulling through the plate itself.

    This fracture ideally would have benefited from medial buttressing in addition to plating the tension side of the fracture. This is rarely – if ever – performed, however, due to the inaccessibility of the medial femur and the amount of severe soft tissue stripping that would be required. In addition, the history of this fracture starting as a stress fracture likely implies some abnormal healing response, which may have delayed the healing process.

    The anterior side of the fracture, which is also in tension due to the bow of the femur, can be reinforced, however, through application of a strut allograft. These allografts should be used judiciously in an acute fracture, as their application requires significant stripping of the anterior and lateral femur, which devascularizes the fracture site. However, a strut allograft may be utilized in selected cases that require increased rigidity beyond what a laterally based plate alone can provide or in fractures with severe bone loss.

    In any case of failed fixation of a periprosthetic fracture, a standard preoperative workup is obtained. Serial radiographs are scrutinized to ensure that the femoral stem is not loose and that the reason for failure of fixation is not due to failure to recognize a loose femoral component. Laboratory studies are obtained, including a C-reactive protein, erythrocyte sedimentation rate, and white blood cell count to rule out infection, as well as a panel of endocrine labs that includes vitamin D, thyroid-stimulating hormone, parathyroid hormone, alkaline phosphatase, calcium, and phosphorus levels. For this patient, lab results were unremarkable.

    Revision Surgery and Outcome

    The need for revision surgery was explained to the patient, she agreed to the procedure, and surgery was planned. To increase the rigidity of the construct, a longer plate was placed. The plate was contoured around the greater trochanter to allow for more opportunities for screw fixation in the proximal fragment. Compression was applied to the fracture through the plate. In addition, a strut allograft was placed on the anterior aspect of the femur and fracture site. The allograft was secured with 2 cables (Figure 4).

    Figure 4. Radiographs showing use of a longer plate, compression, and a strut allograft in the revision procedure.

    Due to the patient’s history of stress fracture and failed fixation, the biology of the fracture site was augmented as well. Iliac crest autograft bone was placed at the fracture site to help stimulate new bone formation.

    The patient’s weight-bearing was protected for 6 weeks, followed by transition to full weight-bearing. Her fracture went on to uneventful union, and the strut allograft showed signs of incorporation into the native femur (Figure 5).

    Figure 5. Radiographs showing union following the revision procedure.

    The patient now walks with a normal gait, without the use of any gait aids. She has mild pain over the greater trochanter due to implant prominence, but this does not affect her gait. Due to the history of stress fracture, the patient was not offered implant removal.

    Key Points

    • Careful analysis of the preoperative radiographs (and preinjury radiographs if available) is critical to ensure that there are no signs of subsidence of the femoral stem or loosening of the implant. A periprosthetic fracture about a well-fixed stem should be treated with ORIF; those with loose or subsided stems should be treated with femoral component revision.
    • During ORIF, proximal fixation around a well-fixed stem may include cables, bicortical non-locking or locking screws, and unicortical locking screws. Cables should be used only in cases in which reduction of the plate to the bone is important, or application of bicortical non-locked screws is not possible due to the medullary implant. In biomechanical studies, several unicortical locking screws create a more rigid construct than cables used in isolation. The addition of cables to a construct of unicortical locked screws shows little benefit.
    • The use of strut allografts in ORIF of acute periprosthetic femur fractures should likely be limited to cases requiring extra rigidity (beyond that which a laterally based implant can provide) or in cases of severe bone loss.
    • Adding biologic supplementation to selected non-unions is an important consideration. Options include use of iliac crest, proximal tibia, or calcaneus bone. Bone graft may also be harvested from the medullary canal of long bones with the use of the reamer-irrigator-aspirator.

    Author Information

    Brandon J. Yuan, MD, is an Assistant Professor in the Division of Orthopedic Trauma, Mayo Clinic, Rochester, Minnesota.

    Disclosure

    The author has no disclosures relevant to this article.

    References

    1. Konstantinidis L. et al. Treatment of periprosthetic femoral fractures with two different minimal invasive angle-stable plates: Biomechanical comparison studies on cadaveric bones. Injury, Int. J. Care Injured 41 (2010) 1256–1261.
    2. Lochab J. et al. Do transcortical screws in a locking plate construct improve the stiffness in the fixation of Vancouver B1 periprosthetic femur fractures? A biomechanical analysis of 2 different plating constructs. J Orthop Trauma 2017;31:15–20.
    3. Lewis G. et al. Tangential bicortical locked fixation improves stability in Vancouver B1 periprosthetic femur fractures: a biomechanical study. J Orthop Trauma. 2015 Oct;29(10):e364-70.