Sequential Ipsilateral Avulsion of the AnteriorInferior Iliac Spine and the Anterior Superior

Iliac Spine in an Adolescent PatientA Case Report

Waleed Kishta, MD, Tricia S. Lane, NP, and Ron El-Hawary, MD, MSc, FRCS(C)

Investigation performed at the IWK Health Centre, Halifax, Nova Scotia, Canada

The patient and his parent were informed that data con-cerning the case would be submitted for publication, andthey provided consent.

Case Report

Athirteen-year-old boy presented to the Emergency De-partment after injuring the left hip. He had been playing

soccer, twisted the hip, felt a ‘‘snap,’’ and experienced pain inthe anterior aspect of the hip and groin; however, he was able tobear weight with a limp. Initial treatment included remainingnon-weight-bearing with the use of crutches and ibuprofenfor analgesia. He presented to the orthopaedic clinic four dayspostinjury, at which time he had tenderness over the anteriorinferior iliac spine (AIIS). The pain increased with active hip

Fig. 1-A

The anteroposterior (Fig. 1-A) and lateral

(Fig. 1-B) radiographs demonstrate a minimally

displaced fracture of the AIIS.

Disclosure: None of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support ofany aspect of this work. One or more of the authors, or his or her institution, has had a financial relationship, in the thirty-six months prior to submission ofthis work, with an entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work.No author has had any other relationships, or has engaged in any other activities, that could be perceived to influence or have the potential to influencewhat is written in this work. The complete Disclosures of Potential Conflicts of Interest submitted by authors are always provided with the online versionof the article.

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JBJS Case Connect 2014;4:e50 d http://dx.doi.org/10.2106/JBJS.CC.M.00239

flexion, active knee extension, and passive knee flexion. He didnot have swelling or deformity at the level of the pelvis. Theremainder of the hip and knee examinations was normal. The

gait was observed to be antalgic on the left side. Other thanweakness in ipsilateral knee extension, the bilateral motor andsensory neurological evaluation from L2 to S1 was normal.Anteroposterior and lateral radiographs of the pelvis revealed aminimally displaced avulsion fracture of the left AIIS (Figs. 1-Aand 1-B).

The patient underwent six weeks of treatment that con-sisted of oral analgesia and rest, as well as avoidance of contactsports, running, and jumping. After that period of treatment,he was pain-free, and there was no swelling, tenderness, ordeformity through the hip, thigh, or knee. Specifically, therewas no tenderness over the AIIS. He had no pain with resistedhip flexion or knee extension. Gait examination was grosslynormal. Anteroposterior and lateral radiographs revealed ahealing fracture of the AIIS. He returned back to sports ona gradual basis and was fully functional ten weeks after theinjury.

Twenty-one months later, at the age of fifteen, the patientexperienced another left pelvic injury. He felt a ‘‘pop’’ while hewas lunging during gym class. He was seen in the EmergencyDepartment and was treated with crutches and with oral an-algesia until he was assessed by the orthopaedic team one weekpostinjury. On examination, he had an antalgic gait on the leftside. He had weakness in hip flexion (grade 1 of 5) and kneeextension (grade 2 of 5). Other than this ipsilateral weakness,the remainder of the bilateral lower-extremity neurologicalevaluation was grossly normal. Anteroposterior and lateralradiographs of the pelvis demonstrated an avulsion fractureof the left anterior superior iliac spine (ASIS) (Figs. 2-A and2-B). Treatment was nonoperative. The patient remained

Fig. 1-B

Fig. 2-A

The anteroposterior (Fig. 2-A) and lateral

(Fig. 2-B) radiographs demonstrate that the

AIIS fracture had healed; however, a minimally

displaced fracture of the ASIS was evident.

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non-weight-bearing with the use of crutches, was treated withoral analgesia, and avoided sporting activity for six weeks.After that period of treatment, he was able to walk without

crutches and had full range of motion of the hip. He had nopain with passive hip extension or knee flexion or with re-sisted hip flexion or knee extension. He then returned back tosports on a gradual basis as tolerated, and he was able toreturn to full activity ten weeks after the second injury. Bloodtests, including complete blood count, metabolic screening,and thyroid-stimulating hormone screening, were performedto rule out any underlying medical abnormality. The labo-ratory tests were all normal, with the exception of a slightlylow phosphorus level.

The last clinic visit was approximately fifteen monthsafter the second injury, at which time the patient had no painand was comfortably performing all activities. On examination,he walked without a limp and had full range of movement ofthe hip and the knee. Radiographic examination revealed thatthe each fracture had healed in an acceptable position and withsatisfactory alignment (Fig. 3).

Discussion

Avulsion fractures of the pelvis are common injuries in theadolescent population and generally occur during ath-

letic activities1. Isolated avulsions of either the AIIS or theASIS are the most common locations1-3. Although bilateralsimultaneous avulsion fractures and ipsilateral avulsionfractures of the AIIS and ischial tuberosity have been reportedby Rossi and Dragoni1, and simultaneous avulsion of the AIISand ASIS with and without hip dislocation also has been re-ported4,5, to the best of our knowledge, this is the first reportof sequential ipsilateral avulsion fractures of the AIIS and theASIS.

Fig. 2-B

Fig. 3

Thirty-six months postinjury to the AIIS and fifteen

months postinjury to the ASIS, the anteroposterior

radiograph demonstrates that both fractures

had healed in an acceptable position.

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The AIIS ossifies around fourteen years of age and fusesabout four years later; the ASIS ossifies at fifteen years of ageand fuses with the ilium about four years later. The sartoriusmuscle and the tensor fasciae latae muscle both originate fromthe ASIS, while the direct head of the rectus femoris muscleoriginates from the AIIS. Each muscle spans two joints, whichmay produce substantial loads during muscle contraction6.These sudden and substantial muscle contractions may be toopowerful for the immature cartilaginous apophysis and mayresult in avulsion fractures in the skeletally immature po-pulation. Most injuries occur in boys because of their delayedphyseal closure; the mean age for these fractures is 13.8years1,2,7.

Apophyseal avulsion fractures of the pelvis in adolescentsare common during sports such as soccer and gymnastics.Etiologic data support that these injuries are the result ofindirect trauma secondary to sudden, violent concentric oreccentric muscle contraction1. The distribution related to thetype of athletic activity undertaken reveals that soccer andtennis are the most common sports in which participants maysustain AIIS lesions, while soccer and gymnastics are the mostcommon sports that produce ASIS lesions. When the totalnumber of lesions in each sport was compared with the overallnumber of radiographic examinations performed on partici-pants in that sport, soccer and gymnastics had the highestprevalence of these injuries1. Injuries to the ASIS and AIIS insoccer generally result from a superiorly directed movement ofthe lower extremity while ‘‘kicking the air’’ or from a strike atthe goal with maximum flexion of the hip and extension of theknee. Despite injuring the pelvis while playing soccer, our pa-tient was not in the process of swinging the lower extremity inorder to kick the soccer ball. The injury occurred in the stancephase and was likely similar to the mechanism of injury thatcan occur during the push-off for a sprint. At the beginning of asprint, there is simultaneous hip extension, knee flexion, andankle plantar flexion. The ensuing eccentric muscle activationcan stress both the AIIS and the ASIS. The second injury fromlunging occurred during the swing phase of the lunge and mayhave been the result of the sudden, forceful concentric con-traction of the anterior thigh muscles in order to flex the hipand extend the knee.

Another predisposing factor contributing to these in-juries is the repetitive stresses that are produced while inten-sively training for these sports. In the skeletally immature, theseforces may weaken the epiphyseal plate so that it may not beable to withstand the powerful forces produced by muscles thatare hypertrophied by training. The contribution of physealmaturity to pelvic fracture patterns is evident as these patternsof injury change with skeletal maturity8. As a result, adolescentswith open triradiate cartilage are prone not only to avulsionfractures, but to iliac wing and pubic rami fractures as well. Incontrast, adults are more likely to sustain high-energy injuriesto the acetabulum and the pelvic ring8.

The diagnosis of acute AIIS or ASIS avulsion is usuallymade clinically and then confirmed radiographically. Thehistory is often consistent with an acute pain that was pre-

cipitated by a certain maneuver during a sporting activity.The pain is often severe, sharp, and localized to the buttocksfor ischial tuberosity injuries and to the anterior aspect ofthe pelvis for ASIS and AIIS injuries. The pain is aggravatedby stretching or by actively contracting the involved mus-cle(s). This hip and lower-extremity pain is generally ac-companied by restricted range of motion, and the area overthe avulsed fragment can be swollen and tender9. In a reviewof twenty cases of pelvic avulsion fractures, Fernbach andWilkinson found that AIIS avulsions were less painful thanASIS avulsions10.

Chronic injuries secondary to repetitive loading at thetendinous origin often are more difficult to diagnose. Radio-graphs of the pelvis may demonstrate both lytic and scleroticlesions at the site of injury1,7. Computed tomography andmagnetic resonance imaging may be necessary to confirm thediagnosis of an avulsion injury9. Nontraumatic avulsions of thepelvis may be related to an underlying weakness of the sur-rounding tissues (e.g., with a malignancy)11.

The literature has suggested that symptomatic care withearly weight-bearing for the majority of ASIS and AIIS injuriesgenerally results in full recovery without any sporting limita-tions by two months postinjury12-14. The most commonly re-ported complication related to nonoperative treatment ofpelvic avulsion injuries has been exostosis formation15,16. In-dications for open reduction and internal fixation of a pelvicavulsion injury have included substantial fragment displace-ment of more than 3 cm and fracture nonunion; open reduc-tion and internal fixation has also been indicated in athletes,who may require a shorter convalescent period17-19. Com-plications related to open reduction and internal fixation ofthe AIIS or ASIS have included injury to the lateral femoralcutaneous nerve with resultant meralgia paresthetica, intra-articular screw penetration, and substantial blood loss14. Be-cause of the low potential for complications, complete recoveryand return to athletic activities have been reported for mostcases, regardless of whether they were treated operatively ornonoperatively2,7,14,18.

Sequential ipsilateral avulsion fractures of the AIIS andASIS are an uncommon occurrence. In our patient, the se-quential ipsilateral avulsion fractures of the AIIS and the ASIShad typical features on history, physical examination, radio-graphic imaging, and prognosis; the results of the nonoperativetreatment were the same as would be expected with either ofthese injuries in isolation. n

Waleed Kishta, MDTricia S. Lane, NPRon El-Hawary, MD, MSc, FRCS(C)IWK Health Centre,5850 University Avenue,P.O. Box 9700,Halifax, NS,B3K 6R8, Canada.E-mail address for R. El-Hawary: ron.el-hawary@iwk.nshealth.ca

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References

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10. Fernbach SK, Wilkinson RH. Avulsion injuries of the pelvis and proximal femur.AJR Am J Roentgenol. 1981 Sep;137(3):581-4.11. Bui-Mansfield LT, Chew FS, Lenchik L, Kline MJ, Boles CA. Nontraumatic avul-sions of the pelvis. AJR Am J Roentgenol. 2002 Feb;178(2):423-7.12. Gomez JE. Bilateral anterior inferior iliac spine avulsion fractures. Med SciSports Exerc. 1996 Feb;28(2):161-4.13. Fernbach SK, Wilkinson RH. Avulsion injuries of the pelvis and proximal femur.AJR Am J Roentgenol. 1981 Sep;137(3):581-4.14. Saluan PM, Weiker GG. Avulsion of the anterior inferior iliac spine. Orthopedics.1997 Jun;20(6):558-9.15. Irving MH. Exostosis formation after traumatic avulsion of the anteriorinferior iliac spine: report of two cases. J Bone Joint Surg Br. 1964 Nov;46:720-2.16. Watts HG. Fractures of the pelvis in children. Orthop Clin North Am. 1976Jul;7(3):615-24.17. Aksoy B, Ozturk K, Ensenyel CZ, Kara AN. Avulsion of the iliac crest apophysis.Int J Sports Med. 1998 Jan;19(1):76-8.18. Smith J, Mears DC. Children. In: Mears DC, Rubash HE, editors. Pelvic andacetabular fractures. Thorofare, NJ: Slac. 1986; p. 497-501.19. Veselko M, Smrkolj V. Avulsion of the anterior-superior iliac spine in athletes:case reports. J Trauma. 1994 Mar;36(3):444-6.

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