INTRODUCTION

Groin pain in athletes is still one of the most confusing conditions in sports medicine for all medical professionals involved in diagnosis and treatment of professional and recreational athletes. It has been extensively researched during the last decades, but some questions are still far from answered. Groin pain usually affects athletes in sports involving kicking, twisting/turning, and explosive movements¹. In an epidemiological study it has been shown that groin pain in football players in a club during a season causing lost time in terms of training and matches in male and female football is 4-19% and 2-14% respectively².  In a study analysing groin pain prevalence in football across different levels of play, regardless of time loss, the authors reported that 59% of male players and 45% of female players experienced at least one episode of groin pain during a 6 weeks period³. In addition to creating a significant burden on athlete performance, groin pain is also a challenging field for sports medicine physicians, surgeons and physiotherapists, due to lack of understanding the pathology underneath, as well as inconsistency in terminology and definitions. A Consensus on terminology and definitions was held during the First World Conference on Groin Pain in Athletes in Doha, Qatar in 2014, with a paper published the year after with proposed main clinical entities in groin pain. The authors proposed adductor-related, iliopsoas-related, inguinal-related, and pubic-related groin pain as the main entities, with hip-related groin pain in athletes as a separate category, as well as u number of medical conditions not to be missed that might mimic activity related groin pain⁴.  Groin pain presents a significant burden for a football club, since it causes average time loss of 19-28 days, depending on the involved entity⁵.

PREVENTION AND EARLY DETECTION

Increasing the capacity of players to handle the load they are exposed to during sport has proven effective in reducing injuries across different injury types. Structured exercise programmes can reduce groin injuries in football. As a first step, a general warm-up programme is essential. The FIFA 11+ injury prevention programme  can reduce injuries by 39% across studies⁶. New research is developing the FIFA 11+  with easier implementation, where part of the programme can be performed after training⁷ or at home⁸, with the same effects. Structured warm-up is a basic element of most elite and sub-elite teams, but groin injury rates are still high. Therefore, additional options need to be considered.

Low adductor strength is the most consistent modifiable risk factor for groin pain⁹. The FIFA 11+ does not include an exercise targeting the adductors and does not improve adductor strength¹⁰, so adding an adductor resistance exercise to the training should therefore be relevant.  Performing just one simple adductor exercise, with a single set a few times a week in the preseason and once a week during the season, reduced the prevalence of groin problems in football players by almost 50%, and substantial groin problems by 30%¹¹.  The Copenhagen Adduction exercise is an easy choice, as it does not require equipment and can be performed by anyone anywhere¹².  Additionally, there could potentially be an even larger  preventative effect if players  would perform it more, as the strengthening effect increases considerably with a higher exercise volume¹³. Despite good effects, implementation in practice is still inadequate¹⁴. This unfortunately goes for most resistance exercises, which do not have a sufficiently clear or large performance improvement focus. Performance investigations are still lacking for specific resistance exercises for muscles in the groin area, so implementation strategies probably require more creative approaches related to the specific team contexts. Additional strategies beyond resistance exercises are also necessary.   

Previous injury is a risk factor for most injuries in football, and this is the case for groin pain⁹. Just looking at past injury is an insufficient predictor of who will experience pain during a season. Asking about the duration of symptoms in the previous season, can help detect which players which are more likely to be affected in the new season, and who could need closer monitoring. Continuous monitoring can provide a better insight into which players could need a higher focus. Whenever monitoring test are implemented, a key element is that they should be very quick to perform. A simple approach of asking four standardized questions related to problems influencing participation, training volume, performance, and pain, has been shown to have a decent predictive power of a subsequent time-loss injury¹⁵.  This can provide a quick and easy insight into which players need assessing with potential modification of their training. Quick and easy clinical testing can also provide relevant information. Pain on a 0-10 scale during a simple adductor squeeze correlated well the level of symptoms during sport. Players with a pain level of 0-2 can be considered to have normal function, a pain level of 3-5 indicates a moderate level of symptoms, that requires further assessment, and with a pain level of 6 or more indicates that a player has significant symptoms during football, to an extent where they probably should not be playing¹⁶. Adding a dynamometer to the squeeze test may provide even further information. There is some evidence that adductor strength  decreases in the weeks preceding a time-loss groin injury¹⁷. Implementing in-season strength monitoring is becoming more common in elite football. For example, a specific cut-off value for reductions in adductor strength of >15% have been used as part of an alert system leading to further assessment of individual players and potential intervention¹⁸.

LONGSTANDING AND ACUTE INJURIES

Despite prevention and early detection strategies, injuries are unavoidable part of the game of football. The Doha agreement clinical entities were developed for gradual onset long-standing groin pain. Clinical examination is the cornerstone in reaching the diagnosis, and it consists of palpation, stretching, and resistance testing¹⁹. It is important to understand that multiple entities are often simultaneously involved, so systematic examination is paramount in order not to miss overlapping problems. A study showed that adductor-related groin pain is the most prevalent with 61%, while multiple entities were involved in 44% of the cases²⁰.

For sudden onset pain (acute groin injuries), diagnoses are usually made for specific muscle injuries rather than clinical entities. If we consider a clinical entity approach for acute groin injuries, the classification could be a bit different with only three main clinical entities: adductor injuries, hip flexor injuries, and abdominal wall injuries. Adductor injuries are still the most common, and the adductor longus muscle is most frequently injured muscle, involved in 9 out of 10 adductor injuries²¹.  The diagnosis of an acute adductor injuries can be made using a clinical examination with adductor palpation, adductor stretching, and adductor resistance tests, like the methods described for long-standing adductor-related groin pain²². These tests have a high accuracy (compared to imaging), which means the diagnosis of an acute adductor injury can be made through clinical examination only, but the reality of professional football is that injuries usually require imaging, which will be discussed separately.

Around one third of acute groin injuries affect the hip flexor muscles, which includes both injuries in the iliopsoas and the proximal rectus femoris muscle. The reason these two muscle injuries are grouped together, due to the difficulties in differentiating between them during initial examination²³. There is often widespread ventral groin pain, which leads to specific clinical examination tests being positive for both locations. This results in general poor accuracy of the clinical examination tests²². A delayed clinical examination can be helpful, as pain usually decreases continuously in the days following injury²⁴, leading to clearer localisation of pain and injury. If a fast differentiation is required, imaging will be helpful. Iliopsoas and rectus femoris injuries almost never occur together²⁵.

Pain in the lower abdominal wall area is present in 10-20% of players with acute groin injuries, and is often part of a combination with a more severe injury in a different location (such as an adductor longus avulsion). Isolated acute lower abdominal wall or inguinal pain is rare, and even in combined injuries, positive imaging findings in the abdominal muscles are present in less than 5% of the cases²¹.

IMAGING

“We will know more about the injury after imaging” is a common expression in football when a player is injured. Unfortunately, this rarely applies to groin pain. In longstanding groin pain, imaging findings are rarely able to determine the cause of pain²⁶. Similarly, expectations on the duration of return to play will rarely be influenced by the imaging findings.

Imaging in longstanding groin pain often shows load-related changes. The challenge is to understand which findings may be related to the specific groin pain. When imaging of football players is compared to that of other athletes or sedentary people, there will often be findings that could be considered “abnormal”, but only few changes seem to be different between football players with groin pain and those without. There is evidence that the extent of pubic bone marrow oedema or a symphyseal disc protrusion are associated with adductor- and pubic-related groin pain²⁶ but these findings are both found in players without groin pain, and not all players with groin pain have them. This makes giving a specific diagnosis challenging. The scientific relevance of imaging findings has been hampered by poor descriptions of clinical examination findings and diagnosis, and by poor study methodology²⁷. As a result, the importance of specific imaging findings in players with groin pain is still unclear. Although it is unlikely that imaging will answer all the questions, there is still good potential for imaging to improve our understanding of the variance in groin pain diagnoses and prognosis. Currently, imaging of players with longstanding groin pain is most helpful to rule out other pathology.

For players with acute groin pain, the relevance of imaging findings in the diagnosis is clearer. When imaging is positive (muscle oedema or tear) for an acute muscle injury, it is generally accepted that this is a valid finding. MRI is slightly more sensitive than ultrasound for acute groin injuries²³. Imaging provides detailed information on injury location and extent, which can provide a specific diagnosis. There are several general classification systems for imaging muscle injury²⁸, but with a recent improved understanding of the variance in anatomy between commonly injured muscles, it has been suggested that there should be muscle-specific classifications²⁹. Detailed imaging descriptions of both acute adductor and hip flexor injuries have been provided^21,25. About 90% of acute adductor injuries involve the adductor longus, while other adductor muscles injuries are rarely isolated, and are often combined with an adductor longus injury. We see that there are three characteristic locations of adductor longus injuries: 1) the proximal insertion, 2) the musculotendinous junction (MTJ) of the proximal tendon, and 3) the MTJ of the distal tendon. In the MTJ injuries at both the proximal and distal insertion, there is rarely any injury to the tendon structure itself, whereas at the proximal insertion, most injuries are complete avulsions of the proximal tendon attachment. These avulsions do not involve a bony avulsion, just the tendon²¹.

Besides reaching the diagnosis, imaging findings often influence estimating the prognosis in terms of return to sports. This has u number of challenges because of significant variations in recovery times between players with similar injuries. Details of history, clinical examination, and MRI findings, for athletes with acute adductor injuries who performed a standardised criteria-based rehabilitation protocol were studied, finding that the strongest predictors of a longer time to return to sport after an acute adductor injury were palpation pain at the proximal adductor longus insertion, a palpable defect, and/or an injury at the bone-tendon junction on MRI. For athletes without any of these findings, even extensive clinical and MRI examination did not assist considerably in providing a more precise estimate of time to return to sport³⁰.

Athletes with an MRI grade 0-2 adductor injury were clinically pain-free after approximately 2 weeks and returned to full team training after approximately 3 weeks. Most athletes with an MRI grade 3 adductor injury (avulsion of the proximal tendon) were clinically pain-free and returned to full team training within 3 months³¹.

MANAGING THE INJURED PLAYER

Players can often still perform well for a considerable period despite having groin pain. Keeping the player on the pitch is often a key initial goal.  The pain can sometimes be controlled by just modifying training. There is also evidence that manual muscle treatments and wearing compression shorts can  give relevant reductions in pain level^32-34. Close monitoring of these players is essential for a successful outcome, as prolonged periods of playing with pain can create a more persistent injury that will be increasingly difficult to treat.

For players with long-standing groin pain, the evidence for specific treatment options is unfortunately limited by poor research methodology. For players with adductor-related groin pain, it has been shown that passive treatments alone are insufficient, and that a progressive increase in load and strengthening is essential³⁵. Additionally, it seems that recent treatment programmes have been able to reduce expected timelines from around 4-5 months^34,36 to around 2-3 months^37,38. There is still a considerable variation between individual players recovery timelines which has not been accounted for. Even groin pain experts struggle to provide a specific timeline for recovery for an individual player. In theory, the longer you set the expected timeline the more likely it is that the player will be fully recovered within expectations. In practice, setting a longer timeline will come with many challenges. Initially, it can be very difficult to understand that full recovery may be several months away, when the athlete was performing until recently. This will influence their trust in the provided advice and challenge the process. When timelines are uncertain, players will often seek several opinions. They will often be attracted to the clinicians who offer the shortest duration regardless of the approach. Opinions will also come from peers, who have had a similar injury or know of someone who has. So as a clinician it is essential to get a deeper understanding of how the individual player has been influenced, and what their expectations are. Early discussions about the pain, contributing factors, individual context (external pressure, relationships, previous treatment, etc.), and setting short term goals and realistic expectations is essential to success³⁹.

The variation in return to play times means that time-based rehabilitation approaches are not optimal. Previously, all players with groin pain would start at the same level: no football-specific drills, similar rehabilitation exercises, and identical progression timelines. Most players want to return to sport as fast as possible, and tailoring the program for an individual is one way to improve individual timelines. We have also experienced that many players can progress exercises relatively early in rehabilitation. Allowing or even pushing early progression according to exercise-specific ability rather than correlating clinical examination criteria has been key in optimizing recovery timelines. The alternative often focuses on players performing exercises completely pain free and that clinical examinations tests are pain free prior to progression. This can result in players being underloaded for a considerable period, and lead to steep increases in load in the end-stage rehabilitation, often with shorter periods of sports-specific training. This can lead to inadequate load adaptation and increased recurrence risk.

Rehabilitating players will have several focus areas apart from injury specific exercises. Players can often perform many exercises at or close to normal training levels even early in the rehabilitation, and progression may be different for different exercises. Allowing separate progression within different exercises/focus areas can also assist in returning the player at a higher level, and potentially reduce recovery time. For instance, a player may be able to perform high speed linear running, despite having considerable pain on isolated adductor exercises. Similarly, patients may be able to perform a deadlift at pre-injury load already in the beginning of the rehabilitation, despite not being able to run. As the key groin injury mechanisms in football are kicking and change of direction⁴⁰, these should have a strong focus both in terms of actual functional progression (e.g. from dribbling, to short passing to kicking, low to high intensity change of direction to reactive agility exercises) and progression of specific strength exercises, which will focus both an anterior and posterior muscle chain.

The main risk with this approach is that when players experience how much they can do at a relatively early stage, they can decide to return to normal football training prematurely without understanding the recurrence risk. Clear return to play criteria can be very helpful. 

SURGICAL TREATMENT

The majority of groin pain cases can be managed conservatively, but sometimes surgical treatment is indicated due to lack of progress during rehabilitation, or having an athlete with multiple pain recurrences. Although conservative treatment can be sufficient in majority of longstanding groin pain cases if given enough time, in modern football time itself might be the missing link. In a situation where every match is important for the club, positive results are influencing popularity, but even more important financial stability. For the injured athlete returning to play sooner, or minimizing the risk of pain recurrence, could mean another lucrative contract and better life for his family, and very often 4 to 6 months for proper rest and rehabilitation might be unrealistic. These are the times where more than ever paramedical reasons might be influencing medical decisions, making football players true gladiators of the contemporary era.

When it comes to longstanding adductor-related groin pain, in a landmark study on active training-based rehabilitation 79% of injured athletes returned to the same level of sport pain free at 18.5 weeks³⁴. In professional football we have time as an important factor, so the reality is that in some cases we must identify athletes with lower chance of successful conservative treatment and opt for more invasive modalities earlier. Research shows that patients with longstanding insertional adductor longus pain with failed conservative treatment, can benefit from selective adductor longus tenotomy with return to sport 9 to 10 weeks after surgery⁴¹.

Acute groin injuries have good prognosis without surgical treatment. In many cases surgeons who encounter acute adductor grade 3 proximal tendon tear choose to perform surgical reattachment, but a recent study has demonstrated that full recovery of these athletes can be achieved with conservative treatment, with return to play time within 3 months³¹. In rare cases with delayed or lower quality muscle/tendon loading during rehab there might be excessive scar tissue formation leading to ongoing discomfort and affected performance, where surgical debridement might be considered.

In cases with inguinal-related groin pain understanding inguinal anatomy, and especially inguinal nerves, is necessary in choosing the right treatment option. This is the area where lateral abdominal muscles connect with the pelvis, rectus abdominis muscle, and hip adductors, with iliopsoas located in proximity, just below the inguinal ligament. The inguinal canal is created by the external oblique aponeurosis anteriorly, inguinal ligament inferiorly, internal oblique and transversus abdominis superiorly, and fascia transversalis posteriorly. The spermatic duct in men and round ligament in women transverse the inguinal canal with accompanying blood vessels and nerves. This area is also where a lot of forces form the abdominal wall and lower limbs intersect during sporting activities, while the inguinal canal is one of the weak points in the abdominal wall.

The inguinal canal is crossed by three sensory nerves: ilioinguinal nerve, iliohypogastric nerve, and genital branch of genitofemoral nerve. All 3 nerves are not present always, as it was reported in a study that the ilioinguinal, iliohypogastric nerve and genital branch of genitofemoral nerve were present in 96, 94 and 90% respectively⁴². There are a lot of variations in the trajectory of these nerves, and a lot of sensory overlapping between them. In a study on emergence and distribution of the ilioinguinal nerve the authors reported 16 modes of division and 8 types distribution, with predominantly anterior scrotal topographic distribution, meaning that the genital branch of the genitofemoral nerve is not solely responsible for scrotal pain⁴³.

In another study authors reported that, in addition to the cutaneous branches from the ilioinguinal nerve in 90.7%, cutaneous branches originating from the genital branches of the genitofemoral nerve were found in the inguinal region in 35.2%, and in 13.0% the genital branch and the ilioinguinal nerve united in the inguinal canal⁴⁴. This is probably the reason that patient reported pain is not well defined, and it seems that there is not one structure that can be responsible for pain.

Multiple causes were proposed as the underlying pathology for inguinal-related groin pain, and they can be grouped into neuropathic (nerve entrapment by overlying aponeurosis or compression by bulging of posterior wall of inguinal canal) and nociceptive (musculoskeletal causes including aponeurotic tears and inguinal ligament enthesopathy), which could generate different pain qualities, with neuropathic pain being associated with electric, burning, and tingling sensations, and nociceptive pain with stabbing, and dull/aching pain^45,46. The main cause of pain seems to be located in the inguinal canal itself (with the ilioinguinal nerve crossing through the centre, and genital branch of the genitofemoral nerve positioned behind the funiculus), and not in the preperitoneal plane, which might have implications in choosing the right treatment modality.

There are currently different surgical procedures performed for athletes with inguinal-related groin pain, based on the surgeons’ approach to underlying aetiology. Inguinal surgery can be open (mesh or non-mesh procedures) or endoscopic. Endoscopic procedures that are commonly utilized in treating inguinal hernias are trans-abdominal pre-peritoneal (TAPP) and totally extra-peritoneal (TEP) approach, and aim to reinforce the inguinal canal by placing a mesh into the pre-peritoneal plane. A study on TEP surgery in treating inguinal-related groin pain in athletes showed 95% return to sports at 4 weeks following surgery⁴⁷. Another RCT study by the same author compared TEP surgery with conservative treatment, and published that 90% of athletes achieved pain free return to sports at 3 months, compared with 27% in conservative treatment group, pointing out that surgical treatment is more effective in treating this pathology⁴⁸. Other experts support an open approach in surgery, and the technique used is based on surgeons’ experience. A study on open surgery using mesh compared Lichtenstein technique (where mesh is placed in the inguinal canal in front of fascia transversalis), with open pre-peritoneal approach (where mesh is placed in pre-peritoneal plane), and the results showed no difference between the groups, and return to sport was achieved in all cases at 53 days postoperatively⁴⁹. Open non-mesh surgery that is commonly used is a modification of Shouldice repair (open minimal repair), with different surgeons achieving excellent results with this technique. A study reported that the main pathology was inguinal canal posterior wall weakness, with the bulge compressing the genital branch of genitofemoral nerve, so neurectomy was part of the procedure. In this series 75% of patients returned to preinjury sports activities at 18.5 days, and histology verified perineural fibrosis in 100% of the cases⁵⁰. A recent RCT compared TEP repair with open minimal repair, showing similar results regarding postoperative pain and return to sports activity⁵¹.

Considering the anatomy, proposed aetiology, and published surgical results for inguinal-related groin pain, it seems that using a mesh to reinforce the inguinal canal might be overshooting. Mesh inguinal repairs are valid surgical techniques for treating inguinal hernias, where a defect in the abdominal wall needs to be repaired, especially in large hernias and attenuation of musculoaponeurotic complex, with possible collagen deficiency⁵². However, in inguinal-related groin pain in athletes there is no hernia by definition and implanting prosthetic material that creates more fibrosis and scar tissue, and increases the risk of nerve entrapment, has no viable justification if similar results can be achieved by suture repairs without mesh. A study presenting intraoperative results reported evidence of nerve entrapment, with ilioinguinal, iliohypogastric nerve and genital branch of genitofemoral nerve involvement in 96.2%, 92.5% and 30.8% respectively⁵³. In cases of inguinal nerve compression and entrapment an open repair with nerve identification and neurectomy if needed, along with inguinal posterior wall suture reinforcement seems like a logical choice. f5

It has been reported that identification of all 3 nerves during hernia surgery has implication in reducing the risk of chronic postoperative pain in hernia surgery, and seems as important in performing surgeries for inguinal-related groin pain. Studies show that surgeons operating on hernia patients identify all 3 nerves in only 40% of the cases, compared to an expert group experience of identifying all 3 nerves in 70-90% of the cases⁴². This highlights the importance of having an experienced surgeon operating on athletes with inguinal-related groin pain when surgery is deemed necessary.

It is extremely important to point out that even in cases that end up having surgery for longstanding groin pain, early postoperative exercise-based rehabilitation is extremely important to achieve optimal results.

SUMMARY

If you work with football players, you need to have a good understanding of groin pain prevention, diagnosis, and management. The good news is that you can prevent many groin problems by implementing a single resistance exercise. For further prevention, the evidence is poor, but advances in our understanding of injury mechanisms and load management will hopefully allow further improvements. The bad news is that players will still get injured. Early detection and intervention are important to reduce the injury burden. When a player is out of play, a diagnostic classification using clinical entities is useful, and criteria-based progression of exercise-based treatment should be the first choice. Fortunately, if the groin pain does not resolve conservatively, surgical interventions have excellent results.

Zarko Vuckovic M.D.

Visiting Surgeon

Aspetar Orthopaedic and Sports Medicine Hospital

Doha,Qatar

VS Clinic

Belgrade, Serbia

Uroloski Centar

Belgrade, Serbia

Milos Bojovic MD

PM&R Specialist / Sports Medicine Physician

Aspetar Orthopaedic and Sports Medicine Hospital

Doha, Qatar

Contact: zarkovdr@hotmail.com

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