Summary

Cleft sign and bone marrow edema of the pubis are significantly associated with sports activity. A FAI-related bony abnormality could contribute to increase the risk of cleft sign and bone marrow edema in athletes, especially in the contact-sport players.

Abstract

Background

The cleft sign (CS) of the pubic synthesis comprises superior cleft sign (SCS) and inferior cleft sign (ICS). SCS indicates a tear at the attachment of rectus abdominis/adductor longus, and ICS indicates a tear at the attachment of the short adductors to the inferior margin of the inferior pubic ramus. The CS and bone marrow edema (BME) of the pubis are associated with hip and groin pain in athletes; however, it remains elusive regarding the relationship between the CS/BME and bone morphology including femoroacetabular impingement (FAI), and the CS/BME and specific sports activities. A recent study reported that the arthroscopic FAI correction surgery for soccer players resulted in significant improvement of BME of pubis.

Purpose

To clarify whether the presence of the CS/BME is associated with FAI-related bone morphology and sports specific activities.

Hypothesis

The CS/BME is more frequently observed in soccer players with FAI-related bony morphology.

Methods

From 2015 to 2018, 631 hips undergoing hip arthroscopic surgery for acetabular labral injury were enrolled in this study. Hips with osteoarthritis (Tönnis grade > 1, 50 patients, 51 hips) were excluded, and 580 hips of 506 patients were investigated. All patients (100%) were examined by single 3-tesla magnetic resonance imaging preoperatively, and SCS, ICS, and BME of ipsilateral side of the pubis were screened. Lateral center edge (LCE) angle, Sharp angle, Tönnis angle, vertical center anterior (VCA) angle, and alpha angle were measured using plain radiographs. All radiographic measurements were manually performed by 2 authors using a picture archiving and communication system. The relationship between the presence of the CS or BME and patient characteristics including sports activity and radiographic measurements were analyzed by Student t-test, chi-square test, or Fisher’s exact test.

Results

580 hips (292 males 288 females, mean age 35.8±15.7 years, mean LCEA28.4±8.7° [<18°: 12.7%, 18°-25°: 21.6%, 25°<: 64.5%]) were included. SCS, ICS, and bone marrow edema of the pubis were seen in 18 hips (3.1%), 13 hips (2.2%), and 36 hips (6.2%), respectively. SCS was not seen in the patients with LCEA less than 18° (0%). Patients with positive SCS had significantly higher VCA angle (positive v negative, 37.1±8.7° vs 30.2±12.5°, p = 0.03). The rate of soccer players among positive SCS, ICS and BME were 56%, 54%, and 53%, respectively (p < 0.001). Among soccer players, SCS, ICS, and BME were more frequently seen (16.4%, 11.5%, 31.1%, respectively) compared to the other kind of athletic activities / non-athletes (1.5%, 1.2%, 3.3%, p < 0.001, respectively).

Conclusion

The CS and BME of the pubis were significantly associated with sports activity. SCS was not seen in dysplastic patients, and was correlated to acetabular anterior over coverage. These results provide a significant hypothesis of the mechanism of the CS and BME of the pubic synthesis; high frequency of the impacts between the acetabulum and femoral head related to sports activities can be one of the most important mechanisms of the CS and BME of the pubic synthesis.