Novel Radiographic Indexes for Elbow Stability Assessment: Part A—Cadaveric Validation

Abstract

Introduction Elbow bony stability relies primarily on the high anatomic congruency between the humeral trochlea and the ulnar greater sigmoid notch. No practical tools are available to distinguish different morphotypes of the proximal ulna and herewith predict elbow stability. The aim of this study was to assess inter-observer reproducibility, evaluate diagnostic performance and determine responsiveness to change after simulated coronoid process fracture for three novel elbow radiographic indexes. Methods Ten fresh-frozen cadaver specimens of upper limbs from human donors were available for this study. Three primary indexes were defined, as well as two derived angles: Trochlear Depth Index (TDI); Posterior Coverage Index (PCI); Anterior Coverage Index (ACI); radiographic coverage angle (RCA); olecranon–diaphisary angle (ODA). Each index was first measured on standardized lateral radiographs and subsequently by direct measurement after open dissection. Finally, a type II coronoid fracture (Regan and Morrey classification) was created on each specimen and both radiographic and open measurements were repeated. All measurements were conducted by two orthopaedic surgeons and two dedicated musculoskeletal radiologists. Results All three indexes showed good or moderate inter-observer reliability and moderate accuracy and precision when compared to the gold standard (open measurement). A significant change between the radiographic TDI and ACI before and after simulated coronoid fracture was observed [TDI: decrease from 0.45 ± 0.03 to 0.39 ± 0.08 (p = 0.035); ACI: decrease from 1.90 ± 0.17 to 1.58 ± 0.21 (p = 0.001)]. As expected, no significant changes were documented for the PCI. Based on these data, a predictive model was generated, able to identify coronoid fractures with a sensitivity of 80% and a specificity of 100%. Conclusion New, simple and easily reproducible radiological indexes to describe the congruency of the greater sigmoid notch have been proposed. TDI and ACI change significantly after a simulated coronoid fracture, indicating a good responsiveness of these parameters to a pathological condition. Furthermore, combining TDI and ACI in a regression model equation allowed to identify simulated fractures with high sensitivity and specificity. The newly proposed indexes are, therefore, promising tools to improve diagnostic accuracy of coronoid fractures and show potential to enhance perioperative diagnostic also in cases of elbow instability and stiffness. Level of evidence Basic science study. Clinical relevance The newly proposed indexes are promising tools to improve diagnostic accuracy of coronoid fractures as well as to enhance perioperative diagnostic for elbow instability and stiffness.

Clinical Presentation and Characteristics of the Upper Extremity in Patients with Musculocontractural Ehlers–Danlos Syndrome

“…A shallow trochlear notch may be caused by coronoid process fractures; however, since coronoid process fractures may be overlooked, parameters are measured on plain radiographs of the elbow joint to reduce these oversights. In a study using fresh-frozen cadaver specimens of upper limbs from human donors, Luceri et al found that the ACI decreased from 1.90 prior to a fracture to 1.58 following a fracture of the coronoid process, and the TDI decreased from 0.45 prior to a fracture to 0.39 following a fracture [ 10 ]. A study by Kilgus et al reported that the elbow instability group showed a significantly larger opening angle (94.1° vs. 88.5°) [ 11 ].…”

“…Two primary indices and two derived angles comprising the Anterior Coverage Index (ACI), Trochlear Depth Index (TDI), Proximal Ulnar Bow (PUB), and Radiographic Opening Angle (ROA) were measured on lateral elbow radiographs ( Figure 1 ) [ 10 , 11 ].…”

Morphological and radiological study of the shoulder and elbow joints of the giant anteater (Myrmecophaga tridactyla)

“…For radiographic evaluation of shoulder joint and elbow joint, the craniocaudal, caudocranial, mediolateral, and lateromedial positions were proposed to this study (Aryana et al, 2021; Knox et al, 2003; Luceri et al, 2021; Vandevelde et al, 2006). Upon consideration, the lateromedial and caudocranial positions were not considered for further analysis, as it was difficult to position the organism in these positions.…”

Novel Radiographic Indexes for Elbow Stability Assessment: Part B—Preliminary Clinical Study

“…This was confirmed in our study by the moderate ICC for the RCA measurements and the low strength of the correlation between TDI and RCA (expected r value = 1). The authors recommend, therefore, to rely on linear measurements and, if needed, to obtain derived angles to describe GSN coverage or sigmoid notch opening by mathematical operations, such as RCA = 4 • arctang (2 • BD / AC) = 4 • arctang (2 • TDI) and sigmoid notch opening angle = RCA / 2 [31].…”