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    Severe Acetabular Bone Loss Following a Failed Custom Triflange Reconstruction

    A 68-year-old male patient has progressive groin pain and is unable to ambulate 2 years after revision total hip arthroplasty with a custom triflange prosthesis. Radiographs show the prosthesis has loosened and dislocated. What other reconstructive options are available for this patient?

    Authors

    Chad A. Krueger, MD; Matthew J. Grosso, MD; Erik Zachwieja, MD; and P. Maxwell Courtney, MD

    Introduction

    Acetabular bone loss presents a unique dilemma for the orthopaedic surgeon, as the optimal treatment is still debated in the literature. Achieving biologic fixation and restoring hip biomechanics is challenging but paramount for long-term success in these patients.

    For Paprosky IIA and IIB acetabular defects, a multihole, porous metal hemispherical shell with screws has been shown to provide excellent outcomes. [1,2] The unsupportive anterior or posterior acetabular columns of larger defects, such as Paprosky IIIB defects and pelvic discontinuity, make it difficult to achieve biologic fixation, as cementless cups require a stable construct for ingrowth. [3,4]

    Many surgeons attempt to use a jumbo cup to manage large defects. Even if the surgeon can obtain a column fit, these large cups elevate the hip center, offer limited options for screw fixation, and are often placed too vertical and retroverted to maximize coverage.

    Although early cage constructs had high failure rates, modern cup-cage constructs have shown reasonable success in Paproksy IIIB defects, with higher failure rates in pelvic discontinuity. A large porous cup can achieve biologic fixation; however, concerns exist about mechanical failure of the cage at longer-term follow-up. [5-6]

    Custom triflange prostheses have become a popular option for managing these difficult cases. [7-8] Although mid-term results demonstrate high survivorship, concerns exist regarding cost, lag time for manufacturing, changes in bone loss pattern after prosthesis removal, and high rates of instability.

    Porous metal augments have been developed to manage massive bone loss and to help revision surgeons reconstruct acetabular columns. [9-11] Augments may be used intracavitary or within the defect, as primary support or extracavitary, outside the defect, as supplemental fixation. For Paprosky IIIB defects, porous metal augments help reconstruct the anterior column with biologic fixation, bring down the hip center to its anatomic position, and allow for appropriate cup positioning. Customization can be achieved intraoperatively. Augments are then unitized to the acetabular cup with cement.

    In this article, we present a case of a failed triflange prosthesis and discuss reconstructive options with multiple cups and porous metal augments.

    Case Presentation

    A 68-year-old male patient who had undergone left total hip arthroplasty (THA) nearly 2 decades earlier presented to another surgeon in 2017 with a 9-month history of progressive limb length discrepancy and groin pain. After being fitted with a shoe lift, he had noted marked limitation in range of motion of his hip. He also had prostate cancer treated with pelvic radiation 5 years prior to presentation. Imaging obtained by the surgeon showed failure of the original THA (Figure 1).

    Figure 1. Anteroposterior pelvis and frogleg lateral radiographs show catastrophic wear and osteolysis, loosening of the acetabular component, and a Paprosky IIIB acetabular defect.

    The patient underwent acetabular reconstruction with a custom triflange prosthesis (Figure 2). He did well for nearly a year, but then had progressive groin pain and ambulatory dysfunction. By the time he was sent to our clinic, he could no longer ambulate and had been in wheelchair for 3 months.

    Figure 2. Immediate postoperative anteroposterior pelvic and frog-leg lateral radiographs of the patient following acetabular reconstruction with a custom triflange prosthesis and femoral revision with a modular tapered titanium stem in 2017.

    Physical Exam

    • Height: 6 feet, 0 inches; weight: 225 pounds; BMI: 30.5
    • Well-healed posterolateral incision
    • 3-cm limb length discrepancy
    • Hip range of motion limited to 90° of flexion, 40° of external and internal rotation with pain
    • Normal distal lower extremity neurovascular exam

    Laboratory Tests

    • Serum erythrocyte sedimentation rate: 16 mm/hour
    • Serum C-reactive protein: 1.4 mg/L

    Imaging

    Radiographs obtained at our clinic showed broken screws, loosening of the triflange prosthesis, and a chronic dislocation of his left revision THA (Figure 3). Repeat inflammatory markers were mildly elevated; however, an aspiration revealed only 1100 white blood cells with 74% neutrophils and a negative alpha-defensin.

    Figure 3. Anteroposterior and frog-leg lateral radiographs show loosening and failure of the patient’s custom triflange prosthesis with a chronic dislocation of his left hip.

    Diagnosis

    • Aseptic loosening and early failure of a custom triflange prosthesis with a Paprosky IIIB acetabular defect

    Treatment Options

    We had several considerations for the management of this patient:

    • He has already failed a custom triflange prosthesis and has a history of pelvic radiation for prostate cancer. Will there be enough bone and biology to achieve stable fixation and bony ingrowth?
    • Given anatomic and biologic concerns regarding acetabular reconstruction, will a resection arthroplasty be the best option?
    • What will be the best option if we attempt acetabular reconstruction: a revision triflange prosthesis, a cup-cage construct, or porous metal augments?

    We discussed all treatment options with the patient, including a resection arthroplasty (Girdlestone) procedure. Given his relatively younger age, he wished to proceed with acetabular reconstruction despite the high risks of infection, failure of ingrowth, and instability.

    We felt that porous metal augments and multiple acetabular cups would give us the best chance to:

    • Restore hip biomechanics
    • Achieve stable, biologic fixation
    • Reconstruct his acetabular columns

    Surgical Procedure

    • Utilizing the prior posterolateral incision, dissection was taken down and deep to the fascia and the gluteus maximus muscle fibers were split.
    • We sent a total of 4 specimens for synovial culture, which were negative.
    • We cautiously extended our dissection proximally along the ilium and removed the screws and triflange prosthesis, which was grossly loose.
    • The patient had a Paprosky IIIB acetabular defect with more than 3 cm of proximal migration and unsupportive anterior and posterior acetabular columns (Figure 4).
    • There was extensive metalosis throughout the wound, and this was thoroughly debrided

    Figure 4. Intraoperative photograph show a Paprosky IIIB acetabular defect following removal of the loose triflange prosthesis.

    • We first attempted to reconstruct the anterior column. We placed a 54-mm Continuum cup (Zimmer Biomet; Warsaw, Indiana) in the defect in the ilium to bring down the hip center. We then used a 66-mm x 30-mm acetabular augment as an intracavitary augment for primary support of the anterior column. We placed 2 50-cm x 10-mm augments together to address the superior anteromedial defect. This was described by Paprosky as the dome technique.
    • We used a 48-mm Continuum cup to reconstruct the posterior column, securing it to the ischium with 2 screws. All augments were unitized to the 68-mm trabecular metal acetabular revision shell with cement; we also added 5 supplementary screws. We then placed a posterolateral buttress augment and unitized this to the construct for supplemental fixation.
    • Using a dual-mobility bearing articulation to reduce the incidence of instability, we cemented a 51-mm Polarcup (Smith & Nephew; Memphis, Tennessee) into the acetabular shell.
    • The stem was well fixed; however, we changed the proximal Arcos (Zimmer Biomet) body to a +60 and high offset. We then placed a 28-mm + 6 ceramic femoral head with the femoral dual-mobility bearing articulation.
    • Immediate postoperative radiographs (Figure 5) show the acetabular reconstruction with multiple cups and porous metal augments as both primary support and supplemental fixation.

    Figure 5. Radiographs obtained in the immediate postoperative period show the final acetabular reconstruction.

    Postoperative Follow-up

    • The patient was made toe-touch weight-bearing postoperatively, with posterior hip precautions.
    • He unfortunately sustained a dislocation after a fall at 10 weeks postoperatively. Closed reduction in the emergency department was unsuccessful and he was taken back to the operating room. The Polarcup was removed with a burr and a cemented constrained liner was placed. The acetabular construct was found to have excellent fixation intraoperatively.
    • Cultures were positive for methicillin-sensitive Staphylococcus aureus. The patient received intravenous antibiotics while in the hospital and was prescribed lifelong suppressive oral antibiotics.
    • At 1 year after surgery, he was ambulating pain free with a walker and occasionally a cane (Figure 6).

    Figure 6. Radiographs at 1-year follow-up. The patient did return to the operating room for early instability and placement of a cemented constrained acetabular liner but had excellent ingrowth of the prosthesis and was functioning well at 1 year.

    Conclusion

    Massive acetabular bone loss continues to be a challenge for arthroplasty surgeons. Custom triflange prostheses are an option for Paprosky IIIB defects and pelvic discontinuity, but complications can occur during a revision procedure and surgeons should be prepared to manage them.

    Although data support the use of triflange prostheses, these implants can lateralize the hip center and increase joint reactive forces across the hip. Instability rates have also been reported as high as 21% due to the inability to change the version of the acetabular cup.

    The use of porous metal augments and a stepwise approach to acetabular reconstruction in these difficult cases can provide for intraoperative customization, stable column fixation, and biologic ingrowth.

    Surgical Pearls

    • Custom triflange prostheses are an option in massive Paprosky IIIB and pelvic discontinuity cases; however, surgeons must be prepared to deal with potential complications.
    • Porous metal augments can act as intracavitary, primary support to reconstruct acetabular columns, or as extracavitary, secondary support for supplemental fixation.
    • Augments do not require the same long waiting period as a custom prosthesis, and they provide for intraoperative customization, stable column fixation, and biologic ingrowth.

    Author Information

    Chad A. Krueger, MD; Matthew J. Grosso, MD; Erik Zachwieja, MD; and P. Maxwell Courtney, MD, are from The Rothman Institute at Thomas Jefferson University Hospital, Philadelphia, Pennsylvania.

    Adult Reconstruction Section Editor, Rothman Institute Grand Rounds

    P. Maxwell Courtney, MD

    Disclosures: The authors have no disclosures relevant to this article.

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