Proximal adductor avulsions are rarely isolated but usually involve injury to the PLAC and pectineus: descriptive MRI findings in 145 athletes

Abstract

Purpose: The purpose of the study is to review the MRI findings in a cohort of athletes who sustained acute traumatic avulsions of the adductor longus fibrocartilaginous entheses, and to investigate related injuries namely the pyramidalis-anterior pubic ligament-adductor longus complex (PLAC). Associated muscle and soft tissue injuries were also assessed.

Methods: The MRIs were reviewed for a partial or complete avulsion of the adductor longus fibrocartilage, as well as continuity or separation of the adductor longus from the pyramidalis. The presence of a concurrent partial pectineus tear was noted. Demographic data were analysed. Linear and logistic regression was used to examine associations between injuries.

Results: The mean age was 32.5 (SD 10.9). The pyramidalis was absent in 3 of 145 patients. 85 of 145 athletes were professional and 52 competed in the football Premier League. 132 had complete avulsions and 13 partial. The adductor longus was in continuity with pyramidalis in 55 athletes, partially separated in seven and completely in 81 athletes. 48 athletes with a PLAC injury had a partial pectineus avulsion. Six types of PLAC injuries patterns were identified. Associated rectus abdominis injuries were rare and only occurred in five patients (3.5%).

Conclusion: The proximal adductor longus forms part of the PLAC and is rarely an isolated injury. The term PLAC injury is more appropriate term. MRI imaging should assess all the anatomical components of the PLAC post-injury, allowing recognition of the different patterns of injury.

Level of evidence: Level III.

Keywords: Acute sports injuries; Adductor injuries; Adductor longus avulsion; Football; Groin pain; Magnetic resonance imaging; PLAC; Professional athletes; Pyramidalis; Sports.

Fig. 1

a Sagittal and b oblique axial T2 MR. Oblique axial image acquired perpendicular to adductor longus fibrocartilage (curved arrow) as indicated by solid white line. Note that the sagittal image is just to the left of midline and, therefore, includes the fibrocartilage

Fig. 2

Type 1 PLAC injury: Complete fibrocartilage (FC) avulsion–Pyramidalis separated from Adductor Longus–intact Pectineus. a Anatomical line drawing. b Coronal fat suppressed proton density MRI. The right adductor longus fibrocartilage has been avulsed and retracted (curved arrow). The pectineus muscle is normal (straight arrow). c Sagittal FSPD MRI. Pyramidalis is intact (broad arrow). The anterior pubic ligament origin is intact (small arrow). The adductor longus fibrocartilage is missing due to retraction and lateral displacement (curved arrow)

Fig. 3

Type 2 PLAC injury: Complete FC avulsion–Pyramidalis separated from Adductor Longus–partial Pectineus tear. a Anatomical line drawing. b Coronal FST2 MRI. Adductor longus fibrocartilage torn and retracted laterally (curved arrow). Left side of anterior pubic ligament bridge torn (arrowhead). Pectineus muscle with a strip of inguinal ligament/lacunar ligament partially torn from pubic attachment and displaced laterally (straight arrows)

Fig. 4

Type 3 PLAC injury: complete FC avulsion–Pyramidalis connected to Adductor Longus–intact Pectineus. a Anatomical line drawing. b Sagittal FST2 MRI. Pyramidalis is intact (arrowheads) and in continuity with anteriorly and inferiorly displaced adductor longus fibrocartilage (curved arrow). c Oblique axial FST2 MRI. The left adductor longus fibrocartilage is displaced anteriorly and laterally and separated by a fluid filled space (arrows) from the pubic attachment

Fig. 5

Type 4 PLAC injury: complete FC avulsion–Pyramidalis connected to Adductor Longus–partial Pectineus tear. a Anatomical line drawing. b Sagittal FSPD MRI. The pyramidalis muscle is in continuity with the adductor longus fibrocartilage (curved arrow) separated by a fluid space (arrowhead). The anterior pubic ligament is completely avulsed from the pubic bone (*). c Oblique axial FST2 MRI. Both adductor longus fibrocartilage are avulsed (arrowheads). Bilateral partial pectineus (P) tears are present with avulsion of the lacunar ligament (horizontal arrows). Centrally the internal tendon of the rectus abdominis (vertical arrow)

Fig. 6

Type 5 PLAC injury: complete FC avulsion–Pyramidalis partially separated from Adductor Longus–partial Pectineus tear. a Anatomical line drawing. b Sagittal FSPD MRI. There is a partial tear through the pyramidalis muscle (arrows). Note the lacunar ligament (arrowhead) and superior pubic ramus (*). The adductor longus fibrocartilage is avulsed and displaced inferiorly (curved arrow). c Oblique axial FSPD MRI. The left fibrocartilage is avulsed anteriorly (curved arrow) and the left pectineus muscle (P) and lacunar ligament is partially torn from the anterior margin of the pubis (arrow). There is a tear through the anterior pubic ligament bridge over the symphyseal joint on left side (arrowhead)

Fig. 7

Type 6 PLAC injury: partial FC avulsion–Pyramidalis connected to Adductor Longus–intact Pectineus. a Anatomical line drawing. b Sagittal FST2 MRI. The pyramidalis (arrowheads) and anterior pubic ligament (arrow) are intact and in continuity with the adductor longus fibrocartilage (curved arrow). c Oblique axial FST2 MRI. There is a partial tear of the right adductor longus fibrocartilage (curved arrow). The anterior pubic ligament is intact (arrows)