Anteromedial elbow approach for coronoid process fractures: a cadaveric study and case report

Abstract

Objective To provide an anatomical basis for treatment of coronoid process fractures through an anteromedial elbow approach and evaluate its clinical effects. Methods Forty cadaveric specimens of adult upper limb were dissected to evaluate the anatomical relationships between the median nerve branches and the nearby muscles in the field of the anteromedial elbow approach. On the basis of the anatomical study, 10 patients with coronoid fracture were treated from June 2014 to June 2015. They were 7 males and 3 females, from 17 to 63 years of age (average, 43 years). By the O’Driscoll classification, there were 2 cases of type Ⅰ1, 3 ones of type Ⅰ2, one of type Ⅱ1, 3 ones of type Ⅱ2 and one of type Ⅲ2. The anteromedial elbow approach through the intramuscular space between the pronator teres and the flexor carpi radialis was used to reduce and fixate the fractures of unlar coronoid process and to explore and repair the medial collateral ligaments in all the patients. The ranges of extension, flexion and rotation of the elbow joint were measured at the last follow-ups; the function of the elbow was evaluated according to Mayo elbow per-formance scores (MEPS). Results The main branch of the median nerve ran between the lateral and the medial epicondyles of the humerus, 27.34 mm away to the medial epicondyle of the humerus. The mean distance between the first pronator teres nerve branch and the coronoid process was 13.19 mm. The mean distance between the flexor carpi radialis nerve branch and the coronoid process was 47.02 mm. The mean distance from the medial epicondyle to the flexor carpi radialis nerve branch was 64.40 mm. All the patients were followed up for an average of 12 months (from 6 to 18 months). Fractures united after an average of 1.8 months (from 1.5 to 2.0 months). Deformity, instability, pain or limited motion of the elbow joint was not observed during the follow-ups. At the last follow-ups, the mean flexion-extension arc of the elbow was 133.0° (from 120° to 140°), the mean rotation was 144.5° (from 130° to 160°), and the mean MEPS was 98 points (from 95 to 100 points). Conclusions The anteromedial approach through the intramuscular space be-tween the pronator teres and the flexor carpi radialis is a reliable and safe access for coronoid process fractures, because it leads to less injury to the median nerve than the anterior approach, and exposes the coronoid more favorably than the medial approach to facilitate reduction and fixation of the fracture fragments. Key words: Ulna; Nerve; Anatomical study; Clinical application