Classification:
Acute injuries: due to extreme, unbalanced, eccentric muscular contractions; associated with avulsed bone fragments
Subacute injuries: aggressive appearance of mixed lysis and sclerosis
Chronic injuries: due to repetitive microtrauma or overuse, may be associated with protuberant mass of bone
Imaging:
Plain radiographs: for avulsion fracture
CT: if equivocal radiographs
MR: evaluation of injuries to muscles, tendons, ligaments
Pelvis:
Iliac crest: abdominal muscles
ASIS: sartorius, tensor fascia lata
AIIS: rectus femoris
Inferior pubic ramus: adductiors, gracilis
Ischial tuberosity: hamstrings
Femur:
Greater trochonter: hip rotators
Lesser trochonter: iliopsoas
Around knee:
Lateral tibial plateau: lateral collateral ligament
Fibular head: lateral collateral ligamnet, biceps
Tibial eminence: ACL
Inferior pole of patella: patellar tendon
Tibial tuberosity: patellar tendon
Posterior tibial plateau: PCL
Gerdy tubercle: iliotibial band
Around ankle:
Posterior tibial avulsion: posterior capsular disruption
Base of 5th metatarsal: Peroneal tendon
Around shoulder:
Greater tuberosity: supraspinatus
Lesser tuberosity: subscapularis
Around elbow:
Avulsion of medial epicondyle = Little League elbow
References:
Stevens MA et al. Imaging Features of Avulsion Injuries. Radiographics. 1999;19:655-672
Image Gallery:
1. Right ASIS avulsion injury in 12 year old
