Squared ligament of the elbow: anatomy and contribution to forearm stability.
The present study describes the macroscopic and microscopic features of the squared ligament of the elbow (SLE). In addition, the SLE biomechanical behavior and contribution to the forearm stability were also examined.



Ten forearms from freshly frozen cadavers were used for this work. Each forearm was mounted in an experimental frame for quantification of longitudinal and transverse stability. Macroscopic features and biomechanical behavior were analyzed on dynamic videos obtained during forearm rotation. Then, the SLE was harvested from the 10 forearms for microscopic analysis on histological slices stained with hematoxylin-eosin-saffron.



Two main SLE configurations were identified. One in which the SLE had three distinct bundles (anterior, middle, posterior) and another in which it was homogeneous. The anterior part of the SLE had a mean length of 11.2 mm (±2.4 mm) and a mean width of 1.2 mm (±0.2 mm) while the posterior part had a mean length of 9.9 mm (±2.2 mm) and a mean width of 1 mm (±0.2 mm). Microscopic examination showed that the SLE is composed of a thin layer of arranged collagen fibers. During forearm rotation, the SLE progressively tightens upon pronation and supination by wrapping around the radial neck. Tightening of the SLE during forearm rotation provides transverse and longitudinal stability to the forearm, mainly in maximal pronation and supination.



The SLE is a true ligament and provides forearm stability when it is stretched in pronation and supination.
Department of Orthopaedic Surgery, Universitary Hospital of Bicetre (Public Assistance Hospital of Paris), Le Kremlin-Bicêtre, France.
Salma
S
Otayek
Faculty of Medecine Paris Sud, University Paris Sud, Le Kremlin-Bicetre, France.
Abd-el-Kader
AEK
Ait Tayeb
Department of Orthopaedic Surgery, Universitary Hospital of Bicetre (Public Assistance Hospital of Paris), Le Kremlin-Bicêtre, France.
Bouchra
B
Assabah
Department of Orthopaedic Surgery, Universitary Hospital of Bicetre (Public Assistance Hospital of Paris), Le Kremlin-Bicêtre, France.|Faculty of Medecine Paris Sud, University Paris Sud, Le Kremlin-Bicetre, France.
Brice
B
Viard
Department of Orthopaedic Surgery, Universitary Hospital of Bicetre (Public Assistance Hospital of Paris), Le Kremlin-Bicêtre, France.
Romain
R
Dayan
Department of Pathology, Universitary Hospital of Bicetre (Public Assistance Hospital of Paris), Le Kremlin-Bicêtre, France.
Thierry
T
Lazure
Department of Orthopaedic Surgery, Universitary Hospital of Bicetre (Public Assistance Hospital of Paris), Le Kremlin-Bicêtre, France. soubeyrand.marc@gmail.com.|Faculty of Medecine Paris Sud, University Paris Sud, Le Kremlin-Bicetre, France. soubeyrand.marc@gmail.com.
Marc
M
Soubeyrand
D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D002102:Cadaver; D004550:Elbow / Q000033:anatomy & histology*; D004551:Elbow Joint / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology; D005542:Forearm / Q000033:anatomy & histology / Q000502:physiology*; D006801:Humans; D008023:Ligaments, Articular / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology; D008853:Microscopy; D011403:Pronation / Q000502:physiology*; D011884:Radius / Q000033:anatomy & histology; D012399:Rotation; D013484:Supination / Q000502:physiology*
Elbow; Forearm instability; Forearm rotation; Forearm stability; Squared ligament of the elbow