Periprosthetic Fracture Below Hip Arthrodesis: Fusion Takedown and Conversion to THA
A 51-year-old male with a history of a right hip arthrodesis fell and sustained a periprosthetic fracture below his fusion plate. What is the best approach to manage this patient: revision fixation or conversion to arthroplasty?
Amy Wasterlain, MD, P. Maxwell Courtney, MD
Hip arthrodesis has historically been performed for the management of severe hip arthritis in young patients who would be at high risk for multiple revisions if they underwent total hip arthroplasty (THA). The cobra head plate was a common implant choice for this procedure, with a successful fusion rate of approximately 64%. 
The literature is sparse on management of subtrochanteric femur fractures in patients with prior hip arthrodesis. Some surgeons have managed this complication with retrograde femoral nailing,  while others have performed open reduction and internal fixation (ORIF) using plates. 
Conversion from hip arthrodesis to THA is generally associated with positive clinical outcomes. Harris hip scores increased by 22 points in a systematic review of 27 studies,  and by over 41 points (P<0.01) in a retrospective review.  Conversion to THA can also alleviate pain in adjacent joints such as the lumbar spine and knee. One study reported that 95% of converted patients had successful surgery without revision at an average of 7 years after surgery. 
However, patients undergoing conversion from hip arthrodesis to THA are at greater risk for complications (9% to 48%) than patients undergoing primary THA.  Risks include: 
- Limb length discrepancy
- Sciatic or femoral nerve palsy (5%)
- Infection (5%)
- Instability (3%)
- Abductor insufficiency (13%)
- Need for revision surgery (12%)
Celiktas et al  found that 30% of patients who were converted from arthrodesis to THA had a persistent Trendelenburg sign postoperatively. 
A 51 year-old male patient presents to the emergency department with pain, inability to bear weight, and deformity of his right proximal femur after a fall down a flight of stairs. He had sustained a motor vehicle accident nearly 3 decades earlier, developed post-traumatic osteoarthritis from an acetabular fracture, and underwent right hip arthrodesis at age 23.
He had done well since his fusion and had been mobile and ambulatory without any assistive devices before this fall, although over the past 2 years, he had experienced some mild back pain for which he occasionally took anti-inflammatory drugs. His past medical history is significant only for hypertension and hyperlipidemia.
- Height: 5 feet, 9 inches; weight: 265 pounds; body mass index: 39 kg/m2
- Well-healed posterolateral incision
- Obvious deformity of the right proximal femur
- Knee range of motion 0° to 120°
- 2-cm leg length discrepancy
- Normal distal right lower extremity motor and sensory exam
- Palpable pedal pulses
- Erythrocyte sedimentation rate: 22 mm/hour
- C-reactive protein: 1.2 mg/L
Figure 1. Radiographs on presentation to the emergency department show a periprosthetic femur fracture below a cobra hip arthrodesis plate. The anteroposterior pelvic radiograph demonstrates approximately a 2–cm leg length discrepancy from the arthrodesis.
- Acute periprosthetic femur fracture below a well-consolidated hip arthrodesis
There are several considerations for the management of this patient:
- Is there enough proximal bone stock and an intramedullary canal to support a retrograde femoral nail?
- If attempting revision ORIF, will extensive proximal dissection be necessary to remove the entire cobra plate?
- Will revision fixation with an additional large fragment plate with a large mechanical lever arm put him at risk for fixation failure?
- Should we consider taking down the fusion and converting to THA at this stage?
We carefully discussed the risks and benefits of surgical treatment with the patient. He had been considering conversion to THA due to his back pain, but he had wanted to wait another 1 to 2 years. He did not want a fusion takedown after we explained the high risks of complications, including sciatic nerve palsy, infection, persistent limp, and dislocation. We also did not feel there was enough proximal bone stock to support 2 5.0-mm interlocking screws, and we did not want to violate his native knee with a retrograde femoral nail.
After much discussion, we decided to proceed with revision ORIF with an additional anterolateral 4.5-mm narrow LCP plate.
- Using the old posterolateral incision, dissection was taken down to the fascia and a subvastus approach to the femur was performed.
- Significant bone growth over the plate was removed with a series of small osteotomes.
- We removed the distal screws and decided not to extend the dissection proximally onto the ilium to remove the entire cobra plate.
- We achieved reduction by using distal femoral skeletal traction and a series of point-to-point reduction clamps. Reduction was confirmed on fluoroscopic imaging.
- Using a narrow, 4.5-mm LCP plate on the anterolateral femur, we achieved fixation with 4 bicortical screws proximal and distal to the fracture.
The patient was made toe-touch weight-bearing for 6 weeks to allow for healing of the periprosthetic fracture (Figure 2). Unfortunately, while ambulating 3 weeks postoperatively, he felt a “pop” in his hip (Figure 3).
Figure 2. Postoperative radiographs demonstrate revision ORIF using a second large fragment plate placed anterolaterally on the femur.
Figure 3. Radiographs at 3 weeks postoperatively show failure of the fixation, with broken hardware.
At this point, we had a long discussion with the patient about treatment options. With failure of fixation, we felt the best option at this point would be a takedown of his arthrodesis and conversion to a long-stem THA.
- Using the old posterolateral incision, dissection was taken down to the fascia and extended proximally to the ilium.
- The cobra plate and the large fragment plate were removed.
- Three sets of cultures and a frozen section were taken, all of which were negative for acute inflammation.
- The abductors were completely atrophied beneath the cobra plate and non-functional.
- We performed an osteotomy and placed a small reamer to identify the hip center and then reamed medially (Figure 4).
Figure 4. Intraoperative radiographs show a small 42–mm reamer identifying the hip center (left) and the final reamer at the medial wall (right).
- After reaming to a size 57 mm, we impacted a size 58-mm multi-hole shell into the plate. We chose to use a dual mobility bearing articulation because of the patient’s abductor insufficiency.
- After removing all broken hardware, we placed 1 prophylactic cable distally and began reaming for a monoblock, fluted, tapered titanium stem.
- We then trialed and with great stability, impacted the actual stem into place with the dual mobility bearing articulation.
- We cabled the remaining fracture fragments to the stem (Figure 5). A press-fit proximal femoral replacement was available and also would have been a reasonable option for this case.
Figure 5. Final postoperative radiograph shows a long monoblock, tapered, fluted titanium stem and a dual mobility bearing articulation.
- The patient was made toe-touch weight-bearing for 6 weeks and was given 81-mg aspirin by mouth twice daily for 1 month for prophylaxis of deep vein thrombosis.
- He had clinically equivalent leg lengths, intact sciatic nerve function, and no episodes of instability at the 6-week follow-up visit.
- He was walking with a painless limp and was told this may be permanent because of his abductor insufficiency.
- Hip arthrodesis takedown and conversion to THA is a very technically demanding procedure with a high complication rate including infection, dislocation, and sciatic nerve neuropraxia.
- Use of intraoperative radiographs or fluoroscopy is a must to determine appropriate cup placement.
- A dual mobility bearing articulation may help reduce the incidence of instability in patients with abductor insufficiency from a prior arthrodesis.
Amy Wasterlain, MD, is an adult reconstruction fellow at The Rothman Institute and Thomas Jefferson University, Philadelphia, Pennsylvania. P. Maxwell Courtney, MD, is an Assistant Professor of Orthopaedic Surgery at Thomas Jefferson University Hospital and attending surgeon at The Rothman Institute, Philadelphia, Pennsylvania.
The authors have disclosures relevant to this article.
Adult Reconstruction Section Editor, Rothman Institute Grand Rounds
- Klemme WR, James P, Skinner SR. Results of hip arthrodesis in adolescents by using the cobra-head plate for internal fixation. J Pediatr Orthop, 1998. 18(5): p. 648-50.
- Tan KG, Sathappan SS. Operative fixation of a subtrochanteric fracture in a patient with previous spontaneous hip fusion. Singapore Med J, 2010. 51(6): p. e107-10.
- Asakawa S, Mammoto T, Hirano A. Proximal femoral fracture in hip arthrodesis treated with double reconstruction plates. Case Rep Orthop, 2017. 2017: p. 5246080.
- Jauregui JJ, et al. Hip fusion takedown to a total hip arthroplasty-is it worth it? A systematic review. Int Orthop, 2017. 41(8): p. 1535-1542.
- Celiktas M, et al. Conversion of hip fusion to total hip arthroplasty: clinical, radiological outcomes and complications in 40 hips. Arch Orthop Trauma Surg, 2017. 137(1): p. 119-127.
- Morsi E. Total hip arthroplasty for fused hips; planning and techniques. J Arthroplasty, 2007. 22(6): p. 871-5.