The introduction of ceramic materials in total hip arthroplasty (THA) has marked a significant advancement, notably by reducing wear and associated osteolysis due to the favorable mechanical and biological properties of this bioinert material ^[1,2]. Nevertheless, ceramic femoral heads are not without complications. The most frequently reported issues are noise phenomena known as squeaking and, more seriously, ceramic head fracture ^[1,3,4]. This risk is particularly well documented in ceramic-on-ceramic bearings and, to a lesser extent, in ceramic-on-polyethylene configurations, with only a few case reports documenting fractures ^[5,6,7,8]. To date, only one case of ceramic head fracture has been reported in the setting of a modular dual mobility THA (DM-THA) ^[9]. We report an unusual case involving two successive ceramic head fractures in a dual mobility hip implant in the same patient.

We present the case of a 66-year-old active male with no significant medical history and a body mass index (BMI) of 30.6 (176 cm height and 95 kg weight). He underwent right THA in 2018 for primary osteoarthritis at an outside institution, with an uncomplicated post-operative course. In July 2023, he underwent contralateral THA for the same indication, also performed in another institution. The implants used consisted of a 55 mm NOVAE® Sunfit TH acetabular shell combined with a size 11 CORAIL® High Offset 135° (DEPUY SYNTHES) collared femoral stem. The bearing surface included a 28 mm BIOLOX Delta® ceramic head (+8.5 mm head length) articulating with a polyethylene insert (outer diameter 55 mm, inner diameter 28 mm). The head was impacted into the polyethylene insert using a head–liner press provided by the manufacturer, which applies standardized force and has been used in multiple prosthetic implantations. The assembly was then impacted onto the taper in a standard manner. The taper was in a pristine condition. Post-operative radiographs were satisfactory (Fig. 1) and the early recovery was uneventful. On post-operative day 10, the patient presented to the emergency department of the same institution where the surgery was performed, reporting mechanical pain and audible noises from the operated hip, without any reported trauma or excessive rehabilitation. Radiographs revealed dissociation of the femoral head from the trunnion (Fig. 2).

Figure 2: Radiographic evidence of femoral head dissociation from the trunnion at post-operative day 10. Anteroposterior pelvis radiograph at post-operative day 10 showing dissociation of the 28-mm ceramic head from the femoral trunnion, without traumatic history. The acetabular component remains in place.

An urgent revision surgery was performed. Intraoperatively, a ceramic head fracture was confirmed, along with taper damage and acetabular liner scratches from trunnion impingement. The acetabular component was revised to a 57 mm NOVAE® Sunfit TH, and the femoral stem to a size 12 CORAIL® KHO (DEPUY SYNTHES). A new 28 mm BIOLOX® Delta ceramic head (+8.5 mm) was implanted (Fig. 3). Head impaction was performed according to standard practice. The post-operative course was uneventful, and the patient showed satisfactory recovery at the 4-month follow-up. A 1-year follow-up was scheduled.

Figure 3: Post-operative radiograph following first revision surgery with complete implant exchange and reimplantation of a new ceramic head. Anteroposterior pelvis radiograph following urgent revision with exchange of the acetabular shell and femoral stem and implantation of a new 28-mm (+8.5 mm) ceramic head. Alignment and fixation are satisfactory, with no immediate complication detected.

However, 22 months post-operatively, the patient was referred to our institution for sudden hip pain and functional impairment of the left hip, occurring during a torsional trunk movement while the foot remained fixed. Radiographs revealed a second ceramic head fracture (Fig. 4). Revision surgery was planned to replace the head and insert, with intraoperative assessment of the acetabular shell and femoral stem.

Figure 4: Radiograph and computed tomography-scan demonstrating the recurrent ceramic femoral head fracture 22 months after the initial revision surgery. Anteroposterior pelvis radiograph and computed tomography performed 22 months after the first revision, confirming a recurrent ceramic femoral head fracture after a low-energy torsional movement. No loosening of the acetabular shell or of the femoral stem is identified.

Revision surgery was performed, during which fragmented ceramic material was found (Fig. 5). There were no signs of damage to the acetabular shell or the trunnion, and both components remained well-fixed. The fractured ceramic head was replaced with a 28 mm cobalt-chromium head along with a compatible polyethylene insert (Fig. 6). A decision was made to change the type of prosthetic head bearing.

Figure 5: Intraoperative retrieval of fractured ceramic head fragments. Intraoperative image showing multiple fragments of the fractured ceramic femoral head retrieved during the second revision surgery.

Figure 6: Post-re-revision radiograph after exchange to cobalt chromium head and polyethylene insert. Post-operative radiograph after second revision surgery with replacement of fractured ceramic head by a 28 mm Cobalt-Chromium head and a compatible polyethylene insert.

Extensive irrigation of the joint space was performed to remove residual ceramic debris. Eight months after surgery, the patient demonstrated excellent functional recovery, with a clean and well-healed surgical incision, pain-free ambulation, return to normal activities, and full restoration of the revised hip range of motion.

Fracture of ceramic femoral heads remains one of the most feared complications in hip ceramic-on-ceramic arthroplasty. Although alumina offers excellent compressive strength, its tensile and flexural strength are relatively limited. Fracture rates with third-generation ceramics (BIOLOX® Forte) have been reported at approximately 0.021% ^[10]. To overcome the mechanical limitations of pure alumina, fourth-generation composite ceramic (BIOLOX® Delta) has been developed. These ceramics incorporate 17% zirconia, 0.6% strontium, and 0.3% chromium oxide, and have significantly reduced the incidence of fractures down to 0.003% according to the French National Agency for Safety of Drugs and Medical Products ^[9,10]. Beyond material composition, several risk factors for ceramic head fracture have been identified in the literature. Patient-related factors include elevated BMI, high activity levels, and trauma. Mechanical risk factors include the use of small (28 mm) heads, short neck lengths, manufacturing defects, or suboptimal implant positioning ^[7,11,12,13]. The type of bearing couple is also implicated; ceramic-on-polyethylene configurations appear to carry a lower risk than ceramic-on-ceramic ^[14]. One case of intraoperative ceramic head fracture has been reported during revision surgery, attributed to trunnion damage and component mismatch ^[15]. Fractures generally occur within the first 2 years following surgery ^[10]. However, delayed fractures without any history of trauma have been increasingly reported, raising the possibility of low-temperature degradation of zirconia in hybrid ceramic bearings ^[16,17]. However, this mechanism was not identified, and no fractures were reported in mid- to long-term follow-up in several series evaluating hybrid ceramic bearings ^[18,19]. The present case is notable in that the fracture occurred in a DM THA, a configuration not commonly associated with this complication, as in a conventional prosthesis. To our knowledge, no case series of ceramic head fractures in dual mobility implants has been published. Only one isolated case, described by Mickaël Patetta, involved a traumatic fracture occurring 4.5 years post-operatively ^[9]. It is noteworthy that, in this case, a modular dual mobility acetabular component was implanted. Modular dual mobility acetabular components are recognized for offering intraoperative flexibility and a theoretical reduction in the risk of post-operative instability ^[20,21]. Nevertheless, these advantages come with potential disadvantages, including mechanical issues, such as accelerated wear and fretting corrosion, as well as biological risks related to increased metal ion release and adverse local tissue reactions ^[21,22]. In contrast, the implant used in our case was a monoblock dual mobility cup. What makes our case particularly noteworthy is not only the use of a dual mobility constructs, but also the occurrence of two successive ceramic head fractures in the same hip. The first fracture occurred in the absence of any traumatic event, while the second followed a minor, low-energy incident. This unusual recurrence raises concerns about underlying mechanical or biomaterial-related factors that remain poorly understood in DM THA. Upon analyzing the potential contributing factors in our case, several classic causes can be excluded. The use of a short head length was not an issue, as both heads were +8.5 mm. A manufacturing defect seems unlikely to have affected two consecutive implants in the same patient. Component positioning was confirmed as satisfactory on CT scans. Moreover, no trunnion wear was observed intraoperatively, and compatibility between head and trunnion was confirmed. We hypothesize that the fracture of the ceramic head was caused by excessive mechanical stress at the head-trunnion interface, resulting from a significant increase in medio-lateral offset. This increase was due to the combined utilization of an extended femoral head (+8.5 mm) and a high-offset femoral stem in a patient presenting an elevated BMI. The impact of increased offset on the head–trunnion junction has previously been explored in the literature, with most studies indicating that greater medio-lateral offsets and extended neck moment arms correlate with elevated stress and increased taper damage at modular interfaces ^[23,24]. Del Balso et al., in their analysis of 56 retrieved femoral heads, documented greater trunnion corrosion and fretting damage predominantly affecting the central bore in cases involving elongated heads paired with high-offset stems ^[25]. Similarly, Martin et al. identified increased femoral offset as a primary factor significantly associated with elevated serum cobalt concentrations ^[26]. However, other studies have not validated these findings ^[27,28]. A biomechanical study would have been valuable to better understand the cause of the fracture. However, this is not feasible, as the ceramic head was fragmented into multiple small pieces. It is important to note that the majority of existing studies examining the effects of increased offset on taper performance primarily involve cobalt-chrome femoral heads. Few studies have specifically addressed the consequences of high offset in ceramic heads, which are known to exhibit lower fretting and corrosion rates compared to metal heads ^[29,30]. Indeed, Kurtz’s study, which analyzed fretting across various generations of ceramic components, found no direct correlation with increased femoral offset ^[30]. Given the conflicting data in the present literature, definitively confirming our hypothesis remains challenging. In this case, it appeared important to change the bearing of the prosthetic head for a metal head to avoid any risk of a third ceramic head fracture. Careful consideration should be given to implant selection in prosthetic surgery. While the patient has currently been followed for 8 months, this relatively short follow-up period can be considered a limitation. Continued follow-up is planned at 12 months after the past revision and at 24 months.

This case challenges the presumed mechanical reliability of ceramic femoral heads in dual mobility THA. The recurrence of ceramic head fracture within the same implant, occurring without major trauma and despite confirmed implant compatibility and correct positioning, highlights the potential biomechanical vulnerability of ceramic heads in the dual mobility context. The combination of a high-offset femoral stem, an extended ceramic head, and patient-specific risk factors, notably elevated BMI, may have resulted in excessive localized mechanical stress at the head–trunnion junction, precipitating these fractures. Given the rarity and severity of this complication, further biomechanical and clinical investigations specifically focusing on ceramic heads within dual mobility systems are warranted. Pending more definitive evidence, clinicians should carefully consider patient and implant-related factors before selecting ceramic heads for dual mobility constructs, particularly in scenarios with increased mechanical demand.

Dual mobility constructs do not eliminate the risk of ceramic head fracture. When using extended heads and high-offset stems in patients with elevated BMI, clinicians should consider the mechanical stresses imposed at the head–trunnion interface.