Association of designing internal fixator and prosthesis for the distal end of humerus with the anatomical parameters

Youhua WANG; Jiangchuan MA; Ju WU; Jian ZHAO; Fan LIU

ABSTRACT

BACKGROUND:

The anatomical morphology of the distal end of humerus is an important factor for restricting the treatment of fracture at the site, also for designing and improving of internal fixator and prosthesis. It is very significant to determine the anatomical parameters of the distal end of humerus for correcting the deformation, fixation of internal fixator and replacement of prosthesis.

OBJECTIVE:

To measure 17 anatomical parameters of the angles and structural width or depth related to the distal end of the humerus, verify their fitness with bone after implantations of internal fixator and prosthesis, and identify the association between the characteristics and the mechanical properties of the internal fixator and prosthesis.

DESIGN:

A repetitive measurement and comparative observation.

SETTING:

Affiliated Hospital of Nantong University.MATERIALS The experiments were carried out in the Trauma Research Room, Affiliated Hospital of Nantong University from October 2005 to February 2006. Fifty-four pairs of humerus samples from adult antisepsis corpses were randomly selected (provided by the Department of Human Anatomy, Medical College of Nantong University), including 30 pairs from males and 24 pairs from females, while those with deformation and degeneration of elbow joint were excluded.

METHODS:

The soft tissues adhered to the humerus samples were all rejected, and the anatomical parameters of the distal end of humerus were measured with slide gaud (0.01 mm in precision, produced by Shanghai Measuring and Cutting Tool Works), calipers and goniometer. ① Measurement of angles related to the distal end of humerus The measured parameters included the anteverted angle of the distal humerus, the lateral rotation angle of humerus trochlea,the anteverted angulation of humerus capitulum, the anteverted angulation of humerus trochlea, the condyle-shaft angle of humerus, and the internal rotation angle of the line of lateral-medial humerus epicondyle. ② Measurement of structural width and depth related to the distal end of humerus The measured parameters included the horizontal diameter of the anterior end of humerus trochlea, the horizontal diameter of the inferior end of humerus trochlea, the sagittal diameter of humerus trochlea, the width between medial epicondyle and external epicondyle, the width between medial trochlea and lateral capitulum, the width of olecranon fossa, the depth of olecranon fossa, the width of medial epicondyle, the depth of sulcus for ulnar nerve, the width of humerus capitulum, and the sagittal diameter of humerus capitulum..MAIN OUTCOME

MEASURES:

Results of the angles and structural width or depth related to the distal end of the humerus.males and females in the anteverted angle of the distal humerus [(35.62±5.21)°, (96.22±5.29)°], the lateral rotation angle of humerus trochlea [(5.22±1.15)°, (5.46±1.33)°], the anteverted angulation of humerus capitulum [(48.35±8.78)°,(49.65±9.12)°], the anteverted angulation of humerus trochlea [(33.08±7.15)°, (34.45±7.52)°], the condyle-shaft angle of humerus [(80.12±5.22)°, (80.17±5.45)°], and the internal rotation angle of the line of lateral-medial humerus humerus There were no significant differences between males and females in the horizontal diameter of the anterior end of humerus trochlea [(21.40±4.21), (21.12±4.34) mm], the horizontal diameter of the inferior end of humerus trochlea [(23.54±4.52), (23.31±4.43) mm], the sagittal diameter of humerus trochlea [(23.91 ±4.85), (23.55±4.63) mm], the width between medial epicondyle and external epicondyle [(58.23±6.44), (55.32±6.55) mm], the width between medial trochlea and lateral capitulum [(45.36±5.21), (42.15±5.03) mm], the width of olecranon fossa [(24.56±4.25), (25.34±4.42) mm],the depth of olecranon fossa [(13.43±2.52), (12.95±2.13) mm], the width of medial epicondyle [(14.35±3.32), (13.02±2.96) mm], the depth of sulcus for ulnar nerve [(8.53±2.96), (7.90±2.54) mm], the width of humerus capitulum [(18.05±2.87), (16.51±2.75) mm], and the sagittal diameter of humerus capitulum [(19.59±3.84), (19.12±3.55) mm] (P＞0.05).

CONCLUSION:

The anatomical parameters of the distal end of humerus should be considered in performing correction of elbow joint, internal fixation and prosthesis replacement in order to get better recovery of elbow joint function.