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Background: Ceramic implant breakage (CIB) in total hip replacement (THR) is a rare incident. A confusion exists between the fragile mechanical behaviour of ceramic materials (brittleness) and fragility in the common sense (easy to break), leading to the misconception that trauma is to blame for these breakages. Trauma has been reported as a cause of breakage by several authors and it is debated whether the burst force can be reached in one single trauma in-vivo. We did a retrospective investigation aiming to determine the risk of CIB associated with a major trauma defined as a periprosthetic femoral fracture (PPFF) or a traumatic loosening of the acetabular shell (TLAS) in ceramic-on-ceramic (CoC) THR., Hypothesis: The impact forces responsible of PPFF and TLAS, which are probably the most important impact forces sustained by patients, are not sufficient to induce immediate or delayed CIB., Material and Methods: We conducted a retrospective study on 31 patients (62 ceramic implants, 31 acetabular liners and 31 femoral heads) with a PPFF or TLAS between January 2010 and January 2022. We reviewed the records and X-rays at the time of the major trauma and at the last follow-up. We searched for simultaneous CIB, and those occurring on the non-explanted ceramic implants at last follow up (delayed CIB). These major traumas occurred in 9 men and 22 women. Median age was 75 years old [20-97years old]. There were 28 PPFF and 3 TLAS. Mean time from THR to trauma was 91.2±67months [2.4-240months]., Results: On X-rays and after intraoperative confirmation, we do not report any simultaneous CIB on the 62 ceramic implants. Treatment consisted of internal fixation for 20 patients with preservation of both ceramic implants for Vancouver A, B1 and C fractures, 8 stem revisions with preservation of acetabular liner for Vancouver B2 and B3 fractures and 3 acetabular shell revisions to dual mobility and ceramic head change for TLAS. Thus, a total of 48 ceramic implants remained implanted (28 acetabular liners and 20 femoral heads). At last follow-up after the index revision (median=36 months [6-100months]), no patient had a delayed CIB., Discussion: Major trauma resulting in a PPFF or TLAS in patient withs a CoC THR did not result in simultaneous CIB. The impact forces during these traumas are not sufficient to induce immediate breakage of the ceramic implants. At a median 3years follow-up we found no delayed CIB. Because CIB is a rare event, longer follow up and larger cohort study is needed to determine if a single high impact trauma can initiate and favour the spread of a crack in the ceramic material leading to a breakage. Considering the high mechanical resistance of the ceramic implants and the absence of CIB during or after a major trauma in our study, patients with CoC bearings should not be restricted in their daily activity to prevent CIB., Level of Evidence: IV, retrospective cohort study., (Copyright © 2022 Elsevier Masson SAS. All rights reserved.)

Background: Ceramic-on-ceramic (COC) total hip replacements (THR) have exhibited less instability and late dislocation. Hip capsule plays an important role in hip stability. Different surrounding soft tissue reactions have been observed according to the bearing material used but no study compared these data using MRI investigation. Therefore, we performed a retrospective case control study to compare hip capsule thicknesses according to the bearing materials in THR and in native hips., Hypothesis: Hip capsule is thicker after COC THR compared to ceramic- or metal-on-polyethylene (PE) bearings, or native hips., Materials and Method: Magnetic resonance imaging (MRI) images, combined with a multi acquisition variable resonance image combination (MAVRIC) sequence, was used to measure the hip capsule thickness in 16 patients (29 hips) who had either COC (13 hips, median age at surgery: 64.8 years old, median follow-up at imaging: 2482 days), PE bearings (11 hips, median age at surgery: 48.4 years old (significantly different from COC THR), median follow-up at imaging: 1860 days (NS)), or a native hip with no implant (5 hips). Two independent radiologists measured capsular thicknesses in 4 different zones and were blinded regarding the bearing components. The imaged hips were classified into three groups: native, COC and PE., Results: The COC THR group had the thickest capsules (median 7.0mm, range 2.9-15.5mm). This result was statistically significant (p<0.0001) when compared to PE THR (median 4.9mm, range 2.2-10.5mm), and to native hips (median 4.1mm, range 2.7-6.9mm) measurements, respectively. Furthermore, painful hips had thinner capsules (4.6mm, range 2-10.5) compared to not painful hips (6.8mm, range 2.3-15.5) (p=0.0006)., Discussion: This is the first in-vivo study measuring capsular thickness in THR with the objective of measuring variations according to the hip implant materials used. The results revealed a significantly thicker capsule for the COC bearing compared to either PE or native hips, and a thinner capsule in painful hips., Level of Evidence: III, retrospective non-consecutive cohort study., (Copyright © 2019 Elsevier Masson SAS. All rights reserved.)