Ulnar trochlear notch articular surface has three morphological patterns: a neglected major anatomical feature
- 49 Downloads
The typical anatomical illustration of the trochlear notch articular surface includes a transverse rough non-articular ridge which separates the olecranon and coronoid part of the joint. This transverse ridge, the “bare area”, is not covered by cartilage and represents the optimal entry point for olecranon osteotomies. Aim of the present study was to encounter the anatomical variations in the morphology of the trochlear notch articular surface.
Two-hundred seventy-three dried ulnae were inspected and a qualitative classification of the variations of the trochlear notch articular surface was done. Correlation to gender and side was examined.
Three distinct morphological patterns were observed. Separate olecranon and coronoid facets (Type I) were the most common pattern (165/273, 60.4%). Partial fusion of olecranon and coronoid facets (Type II) was observed in 75 out of 273 bones (27.5%), while a single olecranon and coronoid facet (Type III) was present in 33 out of 273 bones (12.1%). The occurrence of Type II and III was significantly more common in females (p < 0.001).
The most common morphological pattern of the proximal ulna articular surface was the olecranon and coronoid facets separated by the transverse ridge, which is considered as the typical anatomical pattern. The partial fusion of olecranon and coronoid facets was the second most common pattern (27.5%) and the single olecranon and coronoid facet with no transverse ridge present was the rarest one (12.1%). These variations affect the area covered by cartilage. They are noticeable in an elbow MRI and they may have implications on olecranon osteotomy. Absence of the transverse ridge may confuse the surgeon during elbow arthroscopy.
KeywordsProximal ulna Sigmoid notch Bare area Elbow anatomy Anatomical variations Elbow arthroscopy
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
- 1.Barel PD, Hanel PD (2011) Fractures of the distal humerus. In: Green DP, Wolfe SW (eds) Green’s operative hand surgery. Elsevier/Churchill Livingstone, Philadelphia, pp 745–782Google Scholar
- 2.Canale ST, Beaty JH (2013) Fractures and dislocations in children. In: Canale ST, Beaty JH, Campbell WC (eds) Campbell’s operative orthopaedics. Elsevier/Mosby, Philadelphia, pp 1365–1522Google Scholar
- 3.Keats TE, Anderson MW (2006) The forearm. In: Keats TE, Anderson MW (eds) Atlas of normal roentgen variants that may simulate disease. Mosby, St. Louis, pp 546–576Google Scholar
- 5.Milz S, Eckstein F, Putz R (1997) Thickness distribution of the subchondral mineralization zone of the trochlear notch and its correlation with the cartilage thickness: an expression of functional adaptation to mechanical stress acting on the humeroulnar joint? Anat Rec 248:189–197CrossRefGoogle Scholar
- 10.Standring S, Gray H (2008) Elbow. In: Standring S, Gray H (eds) Gray’s anatomy: the anatomical basis of clinical practice. Churchill Livingstone/Elsevier, Edinburgh, pp 1507–1522Google Scholar
- 11.Standring S, Gray H (2008) Forearm. In: Standring S, Gray H (eds) Gray’s anatomy: the anatomical basis of clinical practice. Churchill Livingstone/Elsevier, Edinburgh, pp 1523–1556Google Scholar
- 12.Tillmann B (1978) A contribution to the functional morphology of articular surfaces. Norm Pathol Anat (Stuttg) 4:1–50Google Scholar
- 13.Wang AA, Mara M, Hutchinson DT (2003) The proximal ulna: an anatomic study with relevance to olecranon osteotomy and fracture fixation. J Shoulder Elb Surg 12:293–296. https://doi.org/10.1016/mse.2003.S1058274602868033 CrossRefGoogle Scholar