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Updated: Apr 24, 2026
In Vivo Quantification of Hip Arthrokinematics during Dynamic Weight-bearing Activities using Dual Fluoroscopy
Published on: July 2, 2021
Development of the D-FLLIP classification for ipsilateral floating hip and knee injuries
M A Altamirano-Cruz1, F Hernández-Aceves2, S Q Rodríguez-Lara3
1UMAE Centro Médico Nacional de Occidente IMSS, Encargado del Módulo de Politrauma, Pelvis y Acetábulo, Guadalajara, Jalisco, Mexico.
Introduction:
Ipsilateral "floating lower limb" (FLL) - coexisting pelvic/acetabular, femoral, and tibial fractures - presents rare, high-energy trauma with complex limb-threat physiology. A standardized diagnostic framework could improve early triage and operative sequencing.
Objective:
To develop and preliminarily evaluate the Diagnostic Floating Lower Limb Ipsilateral Protocol (D-FLLIP) as an ordinal severity classification and early decision-support tool for FLL.
Methods:
Retrospective, single-center case series at a tertiary trauma referral hospital (January 2018-December 2023); n=28 consecutive patients meeting FLL criteria. Study design characteristics: retrospective, informal, single-center, consecutive, exposure-based sampling (clinical); level of evidence IV. Patients were graded I-V with D-FLLIP from itemized domains (pelvis, femur, tibia, and soft-tissue/high-risk features). Primary analyses used Kruskal-Wallis and Fisher's exact/χ2 to compare variables across grades. An exploratory univariable logistic regression assessed discrimination of an acute-complication composite (ICU stay >0 days, amputation, early wound infection <30 d, or significant vascular injury) with ROC/AUC estimation. Ethics approval: R-2024-1301-106; Declaration of Helsinki compliant.
Results:
Grade distribution: I=7 (25.0%), II=11 (39.3%), III=6 (21.4%), IV=2 (7.1%), V=2 (7.1%). Across grades, ICU length of stay and peak lactate increased stepwise (p=0.0357 and p=0.0128); MESS differed by grade (p=0.0264). Vascular injury and amputation were more frequent at higher grades (p=<0.01), whereas early wound infection was not significant (p=0.0832). The acute-complication composite rose with grade but was not statistically significant (p=0.5505). Discrimination was moderate (AUC≈0.69); a pragmatic threshold grade ≥3 yielded sensitivity 0.45 and specificity 0.875.
Conclusions:
D-FLLIP provides a pragmatic, standardized early-severity framework for FLL, aligning with clinical gradients in ICU use, metabolic derangement, and limb-threat events. Given small, unbalanced strata - especially grades IV-V - findings are exploratory/hypothesis-generating. Prospective multicenter validation, interobserver reliability studies, and cut-off calibration are warranted to refine clinical implementation.
