Gregersen MG, Fagerhaug Dalen A, Nilsen F, Molund M. The Anatomy and Function of the Individual Bands of the Deltoid Ligament—and Implications for Stability Assessment of SER Ankle Fractures.
FOOT & ANKLE ORTHOPAEDICS 2022;
7:24730114221104078. [PMID:
35722175 PMCID:
PMC9201323 DOI:
10.1177/24730114221104078]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Background:
Deltoid ligament injury occurs often with supination-external rotation (SER)
ankle trauma. SER fibula fractures with concomitant deltoid ligament injury
are considered unstable—requiring operative fixation. Recent studies have
questioned this general practice with emphasis on better defining the medial
side ankle ligamentous injury. The function of the individual bands of the
deltoid ligament, and the interplay between them, are not fully understood.
We undertook this study to develop a better understanding of these complex
ligamentous structures and ultimately aid assessment and treatment choice of
SER ankle fractures with concomitant deltoid ligament injuries.
Methods:
Ten fresh-frozen cadaveric foot and ankle specimens were studied. We
identified the various ligament bands and did a functional analysis by
assessment of ligament length and tension at predefined angles of ankle
dorsi-plantarflexion combined with valgus/varus and rotation. The results
were determined by manual evaluation with calipers and goniometers, manual
stress, and direct visualization.
Results:
We recorded primarily 5 different bands of the deltoid ligament: the
tibionavicular (TNL; 10/10) tibiospring (TSL; 9/10), tibiocalcaneal (TCL;
10/10), deep anterior tibiotalar (dATTL; 9/10), and deep posterior
tibiotalar (dPTTL; 10/10) ligaments. The tibiospring ligament was tense in
plantarflexion, while the tibiocalcaneal and deep posterior tibiotalar
ligaments were tense in dorsiflexion. The superficial layer ligaments and
the deep anterior tibiotalar ligament length and tension were largely
affected by changes in varus/valgus and rotation. The deep posterior
tibiotalar ligament length and tension was altered predominantly by changes
in dorsi-plantarflexion; varus/valgus positioning had a minor effect on this
band.
Conclusions:
We confirmed the finding of previous studies that dorsi-plantarflexion
affects the tensile engagement of the separate ligament bands differently.
Likewise, combined movements with varus/valgus and rotation seem to affect
the separate ligament bands differently. Our results suggest that the TNL,
TSL, and dATTL are at risk of injury, whereas the TCL and particularly the
dPTTL are protected in the event of an SER-type ankle fracture mechanism of
injury.
Level of Evidence
Level V, cadaveric study.
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