Copyright 2002
Coaching Pitchers
By Michael G. Marshall, Ph.D.

     Chapter Eight:   Growth and Development of the Adolescent Male Elbow

     Child Growth and Development researchers provide X-rays for the appearance and union sequences for the epiphyses of the hand and wrist.   In 1955, S. Idell Pyle and Norman L. Hoerr published X-rays that show the appearance and union sequences for the epiphyses of the knee.   However, no one has reported on the appearance and union sequences for the epiphyses of the elbow.

     By adolescence, diaphysial centers spread almost to the ends of the long bones.   The epiphysial centers appear in their cartilaginous locations and readily enlarge towards the diaphysial ossification center.   Consequently, X-rays show open areas only between diaphysial and epiphysial ossification centers.   These are metaphysial growth plates.   Long bone growth in length occurs on the diaphysial edge of these metaphysial growth plates.   When metaphysial growth plates ossify, long bone length growth stops.   However, bones are living tissue and, depending on the frequencies, directions and intensities of the mechanical stresses with which they must contend, continue to grow (hypertrophy) or shrink (atrophy).

         a.   Evaluation Procedure

     Because the olecranon process epiphysis obstructs the view, anterior/posterior (A/P) X-rays cannot evaluate the trochlear epiphysis.
01.   The A/P view examines the medial epicondyle growth plate.
02.   The A/P view examines the capitulum growth plate.
03.   The A/P view looks for the lateral epicondyle epiphysis and, after it appears, examines its growth plate.
04.   The A/P view examines the radial head growth plate.
05.   The lateral view looks for the olecranon process epiphysis and, after it appears, examines its growth plate.

         b.   Elbow Epiphysial Muscle Attachments

     While evaluating epiphyses growth and development, remember that muscles attach to them.   The pronator teres, flexor carpi radialis, palmaris longus, flexor carpi ulnaris and a slip of the flexor digitorum superficialis muscles attach to medial epicondyle epiphyses.   During forearm accelerations, these muscles exert tremendous stresses.   The extensor carpi radialis longus and extensor carpi radialis brevis muscles attach to lateral epicondyle epiphyses.   During decelerations, these muscles exert tremendous stresses.   The triceps brachii I and II muscles attach to the olecranon process epiphysis.   During forearm accelerations, these muscles exert tremendous stresses.

         c.   Adolescent Male's Bi-Lateral Elbow X-Rays

     Bi-lateral elbow X-rays taken on the tenth through sixteenth birthdates demonstrate elbow skeletal growth and development.   One subjectís elbow X-rays cannot represent all adolescent males.   Birthday elbow X-rays from large adolescent male samples would establish norms for elbow epiphyses appearance and union.

             1.   Ten Year Old

     This bi-lateral elbow X-ray shows:
01.   The medial epicondyle growth plate is very clearly open.
02.   The capitulum growth plate is very clearly open.
03.   The lateral epicondyle epiphysis is not present.
04.   The radial head growth plate is very clearly open.
05.   The olecranon process epiphysis is not present.

             2.   Eleven Year Old

     The bi-lateral elbow X-ray shows:
01.   The medial epicondyle epiphysis has enlarged slightly, but its growth plate is still very clearly open.
02.   The capitulum growth plate has narrowed slightly, but remains open.
03.   The lateral epicondyle epiphysis is still not present.
04.   The radial head growth plate is still very clearly open.
05.   The olecranon process epiphysis recently appeared.

             3.   Twelve Year Old

     The bi-lateral elbow X-ray shows:
01.   The medial epicondyle growth plate has narrowed slightly, but remains open.
02.   The capitulum growth plate has closed, but its trabeculae is not contiguous with its diaphysis.
03.   The lateral epicondyle epiphysis recently appeared.
04.   The radial head growth plate has narrowed, but remains open.
05.   The olecranon process center has enlarged slightly.

             4.   Thirteen Year Old

     The bi-lateral elbow X-ray shows:
01.   The medial epicondyle growth plate is still open.
02.   The capitulum growth plate closed, but its trabeculae is still not contiguous with its diaphysis.
03.   The lateral epicondyle epiphysis is full size, but its growth plate is clearly open proximally.
04.   The radial head growth plate is still open.
05.   The olecranon process epiphysis has enlarged considerably, but its growth plate is very clearly wide open.

             5.   Fourteen Year Old

     The bi-lateral elbow X-ray shows:
01.   The medial epicondyle growth plate has narrowed considerably, but a faint line remains and its trabeculae are still not contiguous with its diaphysis.
02.   The capitulum growth plateís trabeculae is contiguous with its diaphysis.
03.   The lateral epicondyle growth plate has narrowed considerably, but a faint line remains and its trabeculae is still not contiguous with its diaphysis.
04.   The radial head growth plate has narrowed considerably, but a faint line remains and its trabeculae is still not contiguous with its diaphysis.
05.   The olecranon process growth plate has narrowed considerably, but it is still clearly open posteriorly.

             6.   Fifteen Year Old

     The bi-lateral elbow X-ray shows:
01.   The medial epicondyle growth plate has narrowed considerably, but two faint lines remain even though its trabeculae is almost contiguous with its diaphysis.
02.   The capitulum has contiguous mineralized bone.
03.   The lateral epicondyle's trabeculae is contiguous with its diaphysis.
04.   The radial head growth plate is nearly closed and its trabeculae is nearly contiguous with its diaphysis.
05.   The olecranon process's trabeculae is contiguous with its diaphysis.

             7.   Sixteen Year Old

     The bi-lateral elbow X-ray shows:
01.   The medial epicondyle growth plateís trabeculae is almost contiguous with its diaphysis.
02.   The capitulum has contiguous mineralized bone.
03.   The lateral epicondyle has contiguous mineralized bone.
04.   The radial head's trabeculae is contiguous with its diaphysis.
05.   The olecranon process has contiguous mineralized bone .

     Four adolescent pitching arm epiphyses are subject to irreparable injuries.   During forearm accelerations, the medial epicondyle's epiphysis receives considerable traction stresses from the pronator teres, flexor carpi radialis, palmaris longus, flexor carpi ulnaris and flexor digitorum superficialis muscles.   During recoveries, the capitulum's epiphysis receives a rebound collision stresses from the radial head's epiphysis.   During forearm accelerations, the olecranon process's epiphysis receives considerable traction stresses from the triceps brachii I and triceps brachii II muscles.



FREE BOOK!!!                          Chapter Nine