Inguinal-related groin pain in athletes: a pathological potpourri.

Athletes who have pain in the inguinal canal region with no actual hernia present as a common challenge in clinical practice. While the differential diagnosis of groin pain is broad, our editorial focuses on musculoskeletal causes.

A survey of 23 international groin pain experts using the case of a male football player with pain in the inguinal region was performed in 2014. The experts were asked which term they would use to describe the diagnosis.1 The 23 experts used 22 different terms, including inguinal-related groin pain, sportsman’s hernia, incipient hernia, inguinal disruption, posterior wall weakness, Gilmore’s groin and core muscle injury to name but a few.

Following a subsequent expert consensus meeting on terminology and definitions, this group agreed on ‘inguinal-related groin pain’ as the preferred term.2 While there is debate about the appropriate terminology, there is even more uncertainty surrounding the underlying pathology. There are numerous hypotheses on the pathology of inguinal-related groin pain. This ‘pathological potpourri’ causes confusion in the literature and in clinical practice.

Some of the different theories reported in the literature are listed in table 1. We have included an illustration with some of the most prominent theories (figure 1).

Table 1

Theories on the underlying pathology of inguinal-related groin pain in athletes in chronological order divided into theories on nerve irritation and musculoskeletal (MSK) injuries

Nerve irritation theories	Year and authors
Nerve entrapmentPeripheral nerves may become entrapped after direct trauma or inflammatory conditions. The ilioinguinal nerve transmits sensation from the proximal part of the penis and the base of the scrotum. These sensations may be elicited by intensive abdominal muscle training leading to entrapment of the nerve, where it goes through the different layers of the abdominal muscles6	1980; Renstrom and Peterson6
Posterior abdominal wall weakness/bulge (‘incipient hernia’/‘sports hernia’) Insufficient strength of the fascia transversalis to withstand the repeated high intra-abdominal pressure generated by sports activities7 Distension of the peritoneum or stretching of the ilioinguinal nerve8 Bulge in the posterior inguinal wall consistent with an incipient direct inguinal hernia9 Posterior wall bulge with or without conjoint tendon tear or internal ring dilatation10 Distension of the posterior inguinal canal wall musculature, suggested by the site of maximal tenderness, painful cough impulse and operative findings (an early type of direct hernia/sports hernia)11 Nerve irritation of the ilioinguinal and the genital branch of the genitofemoral nerve within the inguinal canal caused by a ‘sports hernia’. Additionally, possible entrapment neuropathy12 A circumscribed weakness of the inguinal canal posterior wall causing a bulge compressing the genital branch of genitofemoral nerve during straining. Additionally, as the canal is widened, the rectus muscle is medially and cranially retracted. This retraction causes increased tension, leading to pubalgia13 During muscular contraction of the abdominal wall, the conjoint tendon lowers and closes the deep inguinal ring like ‘a curtain’, decreasing its diameter. A high insertion of the conjoint tendon leaves the inguinal ring wider and uncovered, thus more exposed to repeated sports-related microtrauma, in particular, the protrusion of preperitoneal fat in the deep inguinal orifice14	1985; Smedberg et al7 1989; Gullmo8 1992; Malycha and Lovell9 1991; Polglase et al10 1993; Hackney11 1999; Akita et al12 2010; Muschaweck and Berger13 2019; Bou Antoun et al14
Tear of the external obliqueNerve irritation caused by single or multiple tears in the external oblique aponeurosis at the site of the emergence of neurovascular bundles containing the terminal branches of the iliohypogastric nerve15 16	1995; Williams and Foster151999; Ziprin et al16

Figure 1

Potential causes of inguinal pain in athletes.

Single unifying theory of everything?

So how should we interpret all these different hypotheses?

It is tempting to turn it into a contest and declare a winner. There is a realistic probability that there are different causes between individuals. Trying to prove a single unifying underlying pathology is likely to be fruitless. Most theories are based on two main ideas or combinations of these ideas:

Nerve irritation (including posterior wall bulge causing compression or entrapment) of the ilioinguinal/iliohypogastric/genitofemoral nerve(s) in the inguinal region.

Musculoskeletal pathology (including aponeurotic tears and inguinal ligament enthesopathy).

These two groups may overlap through overload of several anatomical structures in the inguinal canal. Anatomical variations of the cutaneous branches of the ilioinguinal nerve and genital branch of the genitofemoral nerve should also be considered as a potential explanation for variations in pain distribution.3

Medical teams treating groin pain continue to see patients with inguinal-related groin pain who have different clinical presentations. Some patients present with brief pain only related to certain explosive movements, while others have pain for weeks or months following sporting activity. Patients also report different pain types (electric, burning, stabbing, etc). There may be tenderness of different structures during examination, while others are pain free in the clinic, and only precise history or sports-specific testing combined with appropriate imaging if needed (such as excluding inguinal hernia), leads us to the diagnosis.

Multiple theories can explain different treatment choices

The varying theories on pathoaetiology seem to have influenced treatments. Currently, the literature on inguinal-related groin pain is heavily focused on surgical treatment, with multiple options reported. Surgical approaches can be broadly categorised into two groups that mirror some of the proposed pathologies:

Anterior open mesh or non-mesh reinforcement of the posterior wall, with or without neurectomy.

Posterior endoscopic mesh reinforcement of the posterior wall, with or without inguinal ligament ‘release’.

A recent multicentre randomised controlled trial comparing open and endoscopic repair did not find clinically relevant differences in outcomes.4 Our previous systematic review on the management of groin pain in athletes found both a lack of high-quality studies, and an association where studies with worse methods showed better results.5

How do we advance?

We recognise that ‘inguinal-related groin pain’ is a vague term. However, if we embrace the current variation in pathological explanations, then we cannot support any further distinction in exact pathology. We, therefore, currently continue to recommend using ‘inguinal-related groin pain’.

To advance the field, we need a broad approach and embrace that there is uncertainty. It is a challenge to try and test the multiple hypotheses. We need to develop an encompassing approach, including:

Reliable tests of the suggested pathologies

Knowledge of normal findings in athletic populations

Acceptance that various pathologies may co-exist and are not mutually exclusive

Understanding that there is significant variation between individuals in anatomy and nerve distribution.

Open minds.

At present, these are lacking. It will be a complex and time-consuming process to sift through the various potpourri ingredients. We are more likely to progress if we collaborate on projects to improve study power and share ideas. It is important to recognise that the focus here is on underlying pathology, but as with all musculoskeletal pain conditions the biopsychosocial factors will play their role too. This is also something that needs to be explored further.

In summary, simplistic thinking about single pathologies in inguinal-related groin pain is preventing progress. Acknowledging the current pathological potpourri will allow progress and enable more encompassing approaches.