Trunnion fracture of femoral prosthesis following a large metal-on-metal uncemented total hip arthroplasty: a case report

Abstract

Background Trunnion fracture of the femoral prosthesis is an extremely rare complication following Total Hip Arthroplasty (THA). There are very few reports in literature on trunnion fracture. All previously reported cases are of prostheses with smaller heads, unlike the large metal-on-metal articulation in our case, which is unique. Case presentation A 29-year-old male patient with juvenile idiopathic arthropathy presented to us with a fracture of the trunnion of his left THA, with no history of trauma. He had undergone staged bilateral THA for avascular necrosis of the hips 10 years ago (with AML-A stem and large metal-on-metal articulation bilaterally). We revised the THA and exchanged both femoral and acetabular components. He had a good functional outcome at 3 years’ follow up. Conclusion The primary reason for the trunnion fracture in our case was the faulty stem design of the AML [with a small (9/10) taper, and a large head], causing excessive bending moment at the trunnion, worsening the cantilever effect and leading to subsequent cyclic fatigue failure. Whilst gross trunnion failure (GTF) with dissociation of the head from the taper is commonly reported, trunnion fracture per se is a rare and devastating complication. The AML-A stem has since been recalled by the company and there is a need to constantly monitor these patients for potential trunnion-related complications.

Gross Taper Failure and Fracture of the True Neck in Total Hip Arthroplasty: Retrieval Scanning Electron Microscope Analysis

“…The impairment of the trunnion, due to the high concentration of stress, might cause a fracture even without traumatic events [ 20 , 26 ]. The most striking cases of trunnionosis, often called gross trunnion failures (GTF), include fracture, the disassembly of the femoral head component, and a massive material loss from the trunnion [ 7 , 27 ]. Many situations can facilitate the occurrence of GTF, and the most important risk factors acknowledged in the literature are male sex, a body mass index (BMI) of >30, prosthetic implants with a high offset, long neck length or large CoCr femoral head (>36 mm), intraoperative damage of the components, and finally implant malpositioning [ 12 , 28 ].…”

Long-term outcomes of arthroscopic synovectomy and core decompression through multiple small bone holes for early-stage avascular necrosis of the femoral head

“…AVN of the femoral head is a condition where the blood supply to the femoral head is reduced. The condition might result from traumatic or non-traumatic factors and eventually leads to the collapse of the femoral head [ 1 , 23 , 24 ]. Furthermore, AVN of the femoral head is linked to pathological synovial reaction, hypertrophy, effusion, and an increase in intra-articular pressure [ 2 , 4 , 25 – 28 ].…”

Unusual Case of a Trunnion Fracture Following a Revision Hip Arthroplasty Surgery: A Brief Review of the Literature and Discussion About Causes of Failure

“…There have also been various case reports of trunnion failure with the use of the AML A plus (DePuy International, Leeds, England) implant, which was designed for use in Asian populations to cater to the smaller sizes needed in specific groups of patients [ 12 , 13 ]. This has been described both with a small, MoP construct, as well as with large, metal-on-metal constructs.…”

“…There are no previous Food and Drug Administration reports of similar failures with the femoral stem that was used in this patient. No known risk factors such as obesity, excessive activity, varus position of the stem, small taper size, or increased neck length or offset were present [ 2 , 6 , 7 , 9 , 12 , 13 , 17 , 19 ]. Our patient did have revision of the femoral head component 8 years prior to the fracture of the trunnion.…”