56-year-old man with right THA and acute onset of pain, inability to ambulate
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A 56-year-old male automotive mechanic with a BMI of 41.4 kg/m2 and bilateral total hip arthroplasties performed at another institution presented to the ED with acute right hip pain and inability to ambulate.
The patient had a history of poorly controlled type 2 diabetes mellitus, hypertension and hyperlipidemia. His previous THAs were performed 12 years ago (right) and 6 years ago (left).
About 3 days prior to presentation, he began to notice increasing right hip pain, specifically with ambulation. On the day of presentation, he crossed his right leg over his left and felt a “pop” in the right hip with acute worsening of his pain. On exam, the patient had a well-healed incisional scar over the posterior aspect of his right hip without signs of infection. He was otherwise neurovascularly intact with intact plantar and dorsiflexion and intact sensation distally. His C-reactive protein was mildly elevated at 11.1 mg/L and his sedimentation rate was normal at 14 mm/hr. He had a mild leukocytosis with a white blood cell count of 11.9 K/µL, afebrile, and was otherwise medically stable. Radiographs revealed complete failure of the patient’s right S-ROM (DePuy Synthes) THA femoral component at the proximal aspect of the implant (Figure 1). The hip joint was appropriately reduced without evidence of dislocation. There was no evidence of implant loosening.
Source: Shankar Narayanan, MD.
What are the treatment options?
See answer below.
This young automotive mechanic with an acute failure of his right THA femoral component, which has a metal-on-metal (MoM) bearing surface, now requires a revision arthroplasty. In a young active patient who may still yet require another revision in his lifetime, removing the implant without causing more damage to the surrounding bone is imperative. Furthermore, preoperative planning so that the necessary equipment is available to successfully remove the implant is crucial. An attempt can be made to remove the implant primarily without osteotomy, but the surgeon should be prepared to use an extended trochanteric osteotomy or a sliding trochanteric osteotomy, as needed.
When identifying the revision implant of choice, the surgeon should consider the method of failure of the previous implant. In modular implants, the literature has demonstrated that a combination of an implant’s offset and stem diameter plays an important role in fracture resistance. In addition, the forces that act upon the implant are influenced by a patient’s body weight, activity level and offset. The surgeon’s options include the same or different modular implant, or consideration of a non-modular design for the femoral side of the THA revision. On the acetabular side, there is a MoM bearing surface, which has been documented as an independent contributor to implant failure. The position of the acetabular component is satisfactory, and the patient had no previous complaints of instability. Therefore, it may not be necessary to revise the acetabular side. Exchanging the metal liner for another one is not typically advised, but it may be exchanged for a polyethylene liner if the implant design allows for that.
Infection must also be considered as a contributing factor to implant failure. The literature suggests that unrecognized prosthetic joint infection during arthroplasty revision for aseptic failure (ie, implant loosening, instability and polyethylene wear) is a rare occurrence. However, if infection is being considered, the surgeon should decide whether the joint should be aspirated prior to revision surgery and whether intraoperative cultures should be sent for analysis. Also, the surgeon should decide whether to send a specimen for frozen pathology to determine number of white blood cells per high-power field. Furthermore, if any of these findings are positive, the patient may be indicated for a Girdlestone-type procedure with local antibiotics, a single-stage revision or a two-stage revision must be considered.
Operative technique
The decision was made to proceed with revision right THA with infection considered unlikely given reassuring lab values. The patient was placed on the OR table in a lateral position using a Wixson Hip Positioner (Innomed) under general anesthesia. The prior incision was utilized for a classic posterolateral approach to the hip. The short external rotators were identified and tagged. During deep dissection, a moderate amount of soft tissue metallosis was encountered and a capsulectomy was performed down to healthy tissue. The hip was dislocated posteriorly and the proximal broken component including the metal ball, was removed easily (Figure 2). The proximal sleeve was well-fixed, so flexible osteotomes, a diamond-cutting burr and a pencil-tip burr were used to free the sleeve from the bone. The broken surface of the stem could be visualized through the proximal sleeve, but there was not enough stem exposed to fit a universal stem extractor around the implant. The decision was made to create an extended trochanteric osteotomy using drill holes, a thin oscillating saw, K-wires and osteotomes. K-wires were used to perforate the cortex through the coronal slot, without perforating the far cortex on the other side, and to free the slot from the bony ingrowth. Flexible osteotomes, a Gigli saw, slap hammer, osteotomes and intraoperative imaging were utilized to free the implant from the surrounding bone (Figure 3).
Trial, final stem placement
Two 18-gauge Luque wires (Zimmer Biomet) were circumferentially placed around the femoral diaphysis distal to the osteotomy site to prevent propagation of the osteotomy or intraoperative fracture during reaming and placement of the revision stem. The diaphysis was reamed sequentially using flexible reamers followed by the rigid Wagner reamer (Zimmer Biomet). The trial 16-mm x 225-mm stem with a 36 mm, +7 trial head was stable without subluxation.
The metal liner was then revised by disengaging it from the shell and a new, appropriately sized polyethylene liner was inserted in its place. The final stem was impacted into the diaphysis of the femur. Five additional wires were circumferentially placed to repair the trochanteric osteotomy. Final implants were impacted and the hip was reduced and found to be stable. The wound was irrigated, the short external rotators were repaired and the wound was closed in layers in a typical fashion. The patient was given standard posterior hip precautions to follow for 6 weeks and made weight-bearing as tolerated.
Intraoperative cultures were taken at the surgical procedure as a precaution. On postoperative day 9, these intraoperative cultures, unfortunately, were positive for Staphylococcus pasteuri (coagulase-negative Staphylococcus). Infectious disease was consulted and recommended 6 weeks of IV vancomycin. At his 2-week postoperative follow up, the patient was doing well (Figure 4). The incision was healing well without overt signs of infection.
Discussion
Fracture of a modular THA stem is a rare complication and seems to occur more often in patients with a higher BMI and smaller stem diameter. This particular implant has a fully porous-coated sleeve through which a fluted femoral stem can be inserted and rotated. MoM bearing surfaces are associated with adverse soft tissue reactions and increased risk for implant failure, which became more apparent in the mid-2010s. It is feasible that the presence of a MoM construct may have contributed to this implant’s failure given the extensive amount of metallosis present intraoperatively.
Revising a well-fixed implant continues to be a challenge despite the use of multiple instruments including flexible osteotomes, pencil-tip burrs, metal-cutting burrs, back-slap hammers and K-wires. There are situations where an osteotomy is unavoidable and the surgeon should consider an extended trochanteric osteotomy. However, these osteotomies carry their own risks of persistent pain, nonunion and symptomatic hardware.
Understanding why a construct has failed can provide a surgeon with important insights to avoid future complications and help direct decision-making. In this patient, there were multiple factors at play, including a modular construct, MoM bearing and the presence of a PJI.
- References:
- Borton ZM, et al. J Arthroplasty. 2019;doi:10.1016/j.arth.2019.03.067.
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- For more information:
- Kathryn L. Fideler, MD, MPH, a PGY4 resident, orthopedic surgery; Mengnai Li, MD, PhD, an adult reconstruction surgeon in the department of orthopedic surgery; and Shankar Narayanan, MD, a PGY5 resident, orthopedic surgery, at The Ohio State University Wexner Medical Center, can be reached at Suite 6081, 241 11th Ave., Columbus, OH 43201. Fideler’s email: kathryn.fideler@osumc.edu. Li’s email: mengnai.li@osumc.edu. Narayanan’s email: shankar.narayanan@osumc.edu.
- Edited by Travis Frantz, MD, and Ian Savage-Elliott, MD. Frantz is a sports medicine and shoulder fellow at TRIA Orthopaedic Center in Minneapolis. He completed his orthopedic surgery residency at The Ohio State University Wexner Medical Center in Columbus, Ohio. Savage-Elliott is a chief resident in the department of orthopedic surgery at Tulane University Medical Center in New Orleans. He will pursue fellowship training in foot and ankle and sports medicine following residency completion. For information on submitting Orthopedics Today Grand Rounds cases, please email: orthopedics@healio.com.
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