Download June 2014 Case Study

June 2014 Case Study
Author: Sarah Kinsella, MD, Ann & Robert H. Lurie Children’s Hospital of Chicago
CC: Right hip mass
HPI: A 15 year old male presents for evaluation of a right hip mass. He remembers two injuries 9
months ago during soccer. He describes feeling pain and a possible pop after kicking a soccer ball. Two
days later he recalls an episode where he slid during a game, did the splits and hyperextended his right
leg behind him. Since these injuries he has continued to play soccer and now notices only achy anterior
hip pain after running. One month ago he noticed an area of swelling in his right groin and the inability
to fully flex his hip. He denies bruising, continued popping, grinding, catching, instability or pain in other
joints.
Past Medical History, Surgical History, Medications and Allergies are unremarkable.
Physical Exam:
Inspection: Visible, palpable mass in right groin
Palpation: Tenderness over the palpable mass around the AIIS and slight tenderness in the right groin
ROM: Hip flexion 80 degrees on right (patient abducts his hip at flexion > 80) compared to 145 degrees
on left. Prone external rotation 60 degrees and prone internal rotation 0 degrees on the right
(compared to 60 and 10 degrees on left).
Strength: 5/5 bilaterally in hip flexion, abduction and adduction. Some mild pain with resisted hip
flexion.
Special Tests: Positive FABER and FADIR on right with pain in the groin
Abdominal: Soft, non-tender, no organomegaly
Neurologic: 2+ symmetric reflexes and normal sensation
Vascular: good dorsalis pedis and posterior tibial pulses bilaterally
Differential Diagnosis:
AIIS avulsion fracture
Hip Flexor strain
Muscle hematoma
Abdominal Hernia
Bone or Soft Tissue Tumor
Myositis Ossificans
Imaging:
AP and Frog-leg lateral X-rays revealed a chronic avulsion of the right anterior/inferior iliac spine with
heterotopic bone formation or myositis ossificans.
MRI without contrast revealed a large heterogenous mass with patchy enhancement extending from the
right anterior/inferior iliac spine most likely representing a heterotopic osseous lesion related to prior
avulsion injury.
Diagnosis:
Myositis ossificans related to prior pelvic avulsion injury
Outcome:
The patient was referred to a pediatric orthopedic hip surgeon for a discussion of surgical resection.
Given that the patient has only minimal pain and minimal loss of function and is able to participate fully
in soccer he decided to wait and return in the future if he desires operative management.
Discussion:
Pelvic apophyseal avulsion fractures are rare, but occur most frequently in the adolescent athlete with a
mean age of 13.8 – 15.2 (1). The mechanism of injury is the same as a muscle strain with a forceful
eccentric pull of the musculotendinous unit, however, in the pediatric patient these injuries result in
displacement of an unfused apophysis at the site of a tendon attachment instead of a muscle or tendon
injury. These injuries occur in boys more frequently than girls, and are most common in soccer and
gymnastics, followed by track, baseball and football.
The ischial tuberosity is the most common pelvic location making up around 30-50% of cases, according
to various case series in the literature. Injuries to the anterior superior iliac spine (ASIS) and the anterior
inferior iliac spine (AIIS) occur around 20% of the time each (1). The ASIS is the origin of the sartorius
tendon and tensor fascia lata, while the AIIS is the origin of the rectus femoris tendon. Patients with
ASIS or AIIS avulsion fractures usually report hearing a “pop” during a sports related injury and are
unable to continue playing. Common mechanisms include sprinting and kicking. Surgical fixation is
usually not necessary unless the fracture is avulsed more than 2 cm. Nonunion and exostosis formation
is rare but possible and radiographic findings post-avulsion may mimic a neoplasm.
Myositis ossificans is the most common bone-forming lesion of soft tissue and results from a calcified
hematoma. Osteoblasts replace fibroblasts in a healing hematoma starting around one week post injury
and these lesions can be detected on radiographs three to six weeks after the injury. Bone growth stops
around six or seven weeks and then resorption occurs, however, some bone can remain. It is most
common in the musculature of the anterior thigh and arm. Incidence rates after a thigh contusion range
from 9% to 20%, and it is more likely to develop after more severe contusions (2). However, around
40% of patients with myositis ossificans have no history of trauma (3). Symptoms include pain with
activity, and night pain. There are very few reports of myositis ossificans after a pelvic avulsion fracture.
To prevent the development of myositis ossificans after an injury, especially a quadriceps contusion, it’s
important to begin treatment in the first 24 hours. Treatment includes rest, icing and light stretching of
the injured muscle. Early, gentle range of motion is also important. If myositis ossificans has formed,
treatment is largely conservative as well and includes NSAIDs to reduce swelling and possibly physical
therapy for stretching and strengthening. Athletes with myositis ossificans may return to play if they are
pain free with full strength and functional range of motion. Surgery is rarely needed and is reserved for
bony lesions that are very painful or interfering with an athlete’s range of motion. Surgery shouldn’t be
considered until the lesion is mature, at least 6-12 months, to prevent re-growth of the lesion.
References:
1. Moeller JL. Pelvic and Hip Apophyseal Avulsion Fractures in Young Athletes. Current Sports
Medicine Reports. 2003; 2: 110-115.
2. Brukner P. Clinical Sports Medicine. Australia: McGraw Hill, 2012.
3. Walker E, et al. Dilemmas in Distinguishing Between Tumor and the Posttraumatic Lesion with
Surgical or Pathologic Correlation. Clin Sports Med. 2013; 32: 559-576.
4. Sarwark JF and LaBella CR. Pediatric Orthopaedics and Sports Injuries. Elk Grove Village, IL: AAP,
2010.