Validity and reliability of the Unified Classification System applied to periprosthetic femur fractures: a comparison with the Vancouver system

Abstract

Objective: The Unified Classification System (UCS) presents itself as an evolution of the Vancouver Classification (VCS) for the evaluation of periprosthetic fractures of the proximal femur (PPF). The aim of our study was to evaluate the interobserver and intraobserver reliability, with the purpose of highlighting any loss of reproducibility or validity of the new classification system, compared to the previous one, when applied to the proximal femur. Material and Methods:We tested the interobserver and intraobserver agreement using 40 PPF clinical cases. Each classifying subtype of the UCS and VCS was present in at least two cases. Six experienced hip surgeons (Senior Surgeon, SS) and 5 surgeons in training (Junior Surgeon, JS) classified the clinical cases, twice using the VCS and twice with the UCS. The validity of both classifications was then tested with intraoperative surveys. Results:The mean κ value for interobserver agreement for the VCS in the JS group was 0.65 (CI 95% = 0.57-0.70) and 0.81 for the SS group (0.74-0.88). The mean κ value for interobserver agreement for the UCS in the JS group was 0.63 (0.57-0.67) and 0.65 for the SS group (0.59-0.73). The mean κ value for intraobserver agreement for the VCS in the JS group was 0.71 (0.66-0.75) and 0.73 for the SS group (0.65-0.80). The mean κ value for intraobserver agreement for the UCS in the JS group was 0.72 (0.67-0.76) and 0.7 for the SS group (0.65-0.75). The validity analysis showed a κ value of 0.56 (0.52-0.61) for the VCS (moderate agreement) and a κ value of 0.64 (0.58-0.7) for the UCS (good agreement). Conclusion:The UCS completes the Vancouver classification, expanding it. It is reliable, despite the increase in classification categories and number of parameters to evaluate, with a slightly higher validity.

Reply: RE: De Meo D, Zucchi B, Castagna V, et al. Validity and reliability of the Unified Classification System applied to periprosthetic femur fractures: a comparison with the Vancouver system. Curr Med Res Opin. 2020. DOI:10.1080/03007995.2020.1776232

“…In order to provide evidence about the safety and efficacy of UCS we compared the validity and reliability of both classification systems, evaluating their use on the same population sample. This study demonstrated how, in VCS and UCS, validity and reproducibility are at least equal 1 .…”

The race for the classification of proximal periprosthetic femoral fractures : Vancouver vs Unified Classification System (UCS) - a systematic review

“…Periprosthetic femoral fractures (PFFs) are one of the main causes for revision after hip arthroplasty, with an incidence ranging from 6.6-18% [1][2][3][4]. Furthermore, the incidence of periprosthetic femoral fractures is expected to increase by up to 4.6% per decade [1,[5][6][7][8] to a cumulative incidence of almost 5% [9]. PFFs can have detrimental consequences for the patient with a mortality rate of up to 11% within 1 year after surgical treatment [10].…”

“…"C" cases describe fractures distinct below the prosthesis stem, the prosthesis is considered stable [12]. It has been demonstrated to be valid and reproducible [1,14]. Finally, it also provides treatment recommendations [13].…”

RE: De Meo D, Zucchi B, Castagna V, et al. Validity and reliability of the Unified Classification System applied to periprosthetic femur fractures: a comparison with the Vancouver system. Curr Med Res Opin. 2020. DOI:10.1080/03007995.2020.1776232

“…The results showed it to be reliable and valid. More recently, De Meo et al 13 reassessed the reliability and validity of the UCS by comparing the results of the VCS in PPFF in 40 patients. The results showed that the UCS is reliable and had a slightly higher validity when compared with the VCS.…”

“…When applied to the proximal femur, however, the UCS fails to resolve the VCS controversy, linked to the difficulty of evaluating the stem's stability in type B fractures. Another limitation is the absence of some specific fracture pattern in PPFF [13][14][15] . Due to this reason, Huang et al 15 modified the UCS for PPFF by adding two new B2 subtypes and a new category to encompass stem fracture alone or accompanied by PPFF.…”