Computed tomography for managing periprosthetic femoral fractures. A retrospective analysis

Abstract

Background Periprosthetic fractures (PPF) present a common cause for revision surgery after arthroplasty. The choice of performing either an osteosynthesis or revision arthroplasty depends on the orthopedic implant anchored and loosening. Standard diagnostics include x-ray imaging. CT is usually performed to confirm implant loosening in case of ambiguous diagnosis on standard x-ray imaging. This study aimed to examine the role of CT as a diagnostic modality and its implications for treatment planning and outcome. Methods Patients treated for PPF from January 2010 to February 2018 were included. X-ray and CT reports were analyzed to assess implant loosening. The planning for surgery and the final surgical treatment were evaluated. In addition, patient characteristics were analyzed and compared between patients with and without additional CT as a preoperative diagnostic procedure. Results Seventy-five patients were eligible for the study. X-ray imaging was performed in 90.7% of cases. CT was performed in 60% of the cases as part of the preoperative diagnostic. A clear statement on implant stability or loosening could not be made in 69.1% after X-ray imaging and in 84.4% following CT imaging. Revision arthroplasty for loosened femoral prosthesis components was necessary in 40% of cases. No difference could be determined comparing patients with X-ray imaging to those with X-ray and additional CT. In both groups, operative treatment did not deviate from the preoperative planning. Discussion In two thirds of the conventional radiographic findings, no reliable evaluation of implant loosening was possible in femoral PPFs. Intriguingly, additional CT did not improve the evaluation of implant loosening. Nonetheless, CT scans are often performed if loosening assessment is unclear on regular radiographs. This fact can explain the bias CT results in comparison to regular radiography. However, software-supported CT diagnosis could help to adequately answer the question of loosened implants in PPF in the near future. Since the diagnosis of fracture and their morphology assessment is currently adequately performed using X-rays, CT shall not be considered as the gold standard.

Contribution of the remaining attachment index in the management of Vancouver B1 periprosthetic hip fracture

“…It should nevertheless be stressed that preoperative CT analysis of remaining attachment area, ruling out loosening there, did not diverge from the radiographic analysis in all the present B1 fractures. This confirms the findings of Rupp et al [3], that standard CT does not improve assessment of loss of stem attachment, further indicating the relative non-contributiveness of CT in Vancouver B1 fracture if initial X-ray is of good quality and interpreted by an experienced observer.…”

“…Implant fixation assessment in Vancouver B1 periprosthetic hip fracture with uncemented stem is a major decision factor in planning internal fixation and/or implant revision [1,2]. Loss of stem anchorage is difficult to assess on standard X-ray, whereas complete implant loosening in case of migration with or without osteolysis (Vancouver B2 and B3) is easy to diagnose for a trained observer [3]. Conventional CT is systematically artifacted and cannot reliably assess loosening in the remaining attachment area [3].…”

“…Loss of stem anchorage is difficult to assess on standard X-ray, whereas complete implant loosening in case of migration with or without osteolysis (Vancouver B2 and B3) is easy to diagnose for a trained observer [3]. Conventional CT is systematically artifacted and cannot reliably assess loosening in the remaining attachment area [3]. In internal fixation, moreover, intraoperative assessment of implant loosening is rarely performed as the hip approach is extra-articular [4][5][6].…”

Reliability and validity of the Unified Classification System for postoperative periprosthetic femoral fractures around cemented polished taper-slip stems

“…Previous reports suggest that even computed tomography (CT) scans offer little additional benefit in determining implant stability in PFF. 27 Our observations are likely due to the fact that PTS stem loosening in the context of PFF is poorly defined. PTS stems normally subside within their cement mantle and radiolucencies at the stem-cement interface may not necessarily indicate pathological stem loosening as ongoing subsidence is expected during the first decade after implantation.…”

Periprosthetic proximal femoral fractures in cemented and uncemented stems according to Vancouver classification: observation of a new fracture pattern

“…A paucity of Vancouver B3 fractures was identified in this series, and only in cemented stems. There is a variable rate of incidence of Vancouver B3 fractures in published series, and identification of strict B3 patterns may be subject to a high rate of inter-observer variability [22]. Identification of osteolysis in the setting of fracture is often a subjective assessment, particularly if prior Xrays are not available and the patient is asymptomatic prior to fracture [23].…”