Apophyseal avulsion fractures of the pelvis typically occur during a sudden, forceful muscle contraction ^[1]. In these instances, the force exerted during contraction is translated through musculotendinous units to the apophysis in which they attach and, consequently, separate the apophysis from the rest of the bone. This occurs most frequently in young athletes, as their apophyseal growth plates are still cartilaginous and thus more susceptible to damage from mechanical forces compared to skeletally mature athletes ^[2]. While pelvic avulsion fractures (PAF) can also result from blunt trauma – such as in the case to be presented – this is far less common. The most prevalent activities associated with PAF are running and kicking, thus making soccer the most frequently associated sport (38.1%) ^[3]. Further epidemiologic data reveals that males between the ages of 14 and 15 years old are at the greatest risk of experiencing a PAF [3-5]. Moreover, the anterior inferior iliac spine (AIIS), anterior superior iliac spine (ASIS), and ischial tuberosity (IT) are the most common fracture sites [3, 5]. In contrast, the iliac crest (IC) and the superior corner of the pubic symphysis are among the rarest locations for a PAF [4, 5]. Each zone has muscle originations that, when forcefully contracted, can cause a pelvic avulsion fracture at that site. The rectus femoris originates at the AIIS, and the sartorius originates at the ASIS, the hamstring muscles at the IT, the rectus abdominis muscle at the pubic symphysis, and the abdominal muscles at the IC. Patients who have experienced a PAF commonly report hearing a “crack” at the time of injury, followed by sudden pain ^[6]. Clinical examination typically reveals localized tenderness, swelling, and limited range of motion [7, 8]. Depending on the location of the fracture, additional site-specific findings can be seen; numerous reported cases of ASIS avulsion fractures have presented with pain and/or paresthesia on the anterolateral aspect of the thigh [9-12]. This condition is better known as meralgia paresthetica (MP), a neuropathy due to entrapment of the lateral femoral cutaneous nerve (LFCN) ^[9]. In the setting of PAFs, this condition is usually specific to the ASIS due to its close proximity to the LFCN and is hardly ever seen in the case of IC avulsion fractures ^[10]. Treatment includes conservative treatment for 4–6 weeks for most patients with avoidance of high-impact activities. Depending on the source, surgical intervention is recommended based on location and displacement of 15 mm or greater [5, 12, 13]. The purpose of this case report is to discuss a PAF at a rare location, the IC, that uncharacteristically presented with MP in the absence of ASIS involvement.

A 15-year-old male presented to the clinic with his mother for evaluation of a right IC avulsion that occurred 1 week prior. The patient initially presented to the emergency department and was diagnosed with a single AP hip/pelvis bilateral radiograph (Fig. 1). The AP pelvic view demonstrated an acute 2–3 mm displaced avulsion fracture of the right anterior IC. The patient was at football practice when a teammate’s helmet collided with his right pelvic area. He felt an immediate “pop” and felt pain. The emergency department recommended pediatric orthopedic follow-up, gave him crutches, and instructed him not to bear weight. The patient endorsed pain in his right hip area for a few days after the injury that had since subsided and intermittent numbness in his right anterolateral thigh. The patient’s examination resulted in mild point tenderness over the fracture site and an antalgic gait. There was also numbness on palpation on the anterolateral thigh, consistent with LFCN distribution. There was no obvious deformity, normal range of motion of lower extremities without pain, and no pain with abdominal or oblique crunches. No further radiologic studies were obtained this visit. The patient and his mother were instructed to bear weight as tolerated, avoid high-impact activities, use crutches as needed, and return to the clinic in 4–6 weeks for a repeat examination and AP hip/pelvis radiograph. At the 1-month follow-up, the patient reported no pain or numbness. His examination was normal, with resolution point tenderness and numbness. There was also no pain with crunches. The AP hip/pelvis radiograph showed a healing avulsion fracture of the right anterior IC (Fig. 2). The patient was told to resume all activities as tolerated with no plan to follow up unless needed.

This case report presents a rare instance of an IC avulsion fracture in a 15-year-old male, which was further complicated by the presentation of MP despite no involvement of the ASIS. The patient achieved a full recovery with conservative treatment within 1 month of the initial injury. Among PAF, IC involvement is seen in only 6.7% of cases and rarely presents with MP ^[5]. Typically, MP is associated with ASIS avulsion fractures due to the LFCN traversing near this pelvic landmark ^[14]. However, the exact etiology of MP in the context of an IC avulsion fracture is challenging to determine without visualization of the nerve. Literature suggests that a small percentage of the population (approximately 4%) has an anatomical variant in which the LFCN traverses across the IC posterior to the ASIS ^[14]. This anatomical anomaly may explain the MP experienced by this patient in the absence of ASIS involvement. The resolution of symptoms with conservative treatment suggests that nerve entrapment was likely secondary to local inflammatory processes rather than direct mechanical forces on the nerve by the avulsed apophysis. However, as previously stated, the etiology cannot be definitively determined without visualization of the nerve relative to the fracture. Prompt and accurate diagnosis of PAFs is crucial for appropriate management. While most PAFs, including those with minimal displacement, respond well to conservative management, there is ongoing debate regarding the indications for surgical intervention. Current guidelines are not definitive, but surgical fixation is generally considered for avulsion fractures with significant displacement (over 15 mm) due to the higher risk of non-union [5, 13, 15]. This case, with only a 2–3 mm displacement, appropriately followed a conservative approach, leading to a successful outcome. The rarity of IC avulsion fractures, especially those presenting with MP, underscores the importance of thorough clinical evaluation and consideration of less common anatomical variations. Clinicians should maintain a high index of suspicion for nerve involvement, even in atypical presentations. Conservative management remains the cornerstone of treatment for minimally displaced avulsion fractures, but careful monitoring for complications such as heterotrophic ossification, loss of strength, and excessive callus formation is essential ^[16]. Further studies are necessary to establish more precise guidelines for the management of PAFs in pediatric patients. This includes determining the optimal thresholds for surgical intervention and better understanding the long-term outcomes of conservative versus surgical treatments. In addition, further research into the anatomical variations of the LFCN could provide valuable insights into the mechanisms behind atypical presentations of MP, which may further guide treatment protocols.

This case highlights a rare presentation of an IC avulsion fracture with associated MP, successfully managed with conservative treatment. It emphasizes the need for awareness of anatomical variations and careful clinical assessment in managing PAFs. Ongoing research is essential to solidify treatment guidelines and improve outcomes for young athletes experiencing these injuries.

This case highlights the need for awareness of rare anatomical variations and their impact on clinical presentation, reinforcing the importance of a thorough physical examination. Prompt diagnosis is crucial, and while conservative management is effective for minimally displaced fractures, ongoing debates exist regarding surgical intervention criteria.