Of all the soft-tissue injuries the athlete can suffer, groin injuries are potentially the most debilitating and frustrating of all, especially in terms of time lost from competition and return to full competitive fitness. The co-existence of multiple pathologies is the most plausible explanation for this observed difficulty in management. It is common for athletes to shop around seeking different medical opinions for their ongoing groin pain, and to receive varying medical suggestions as to where the problem originates.
It is important to remember that groin problems often have more than one possible pathology existing. Groin injuries are notorious for ‘co-existing pathologies’.
The ‘big three’ when considering ongoing chronic groin pain are adductor tendinopathy, osteitis pubis and inguinal (sportsman’s) hernia. It is not uncommon to see two or even all three of these conditions co-existing at the same time. However, there still exists a myriad of other pathological conditions affecting the groin area.
It is beyond the scope of this article to discuss all the presenting signs and symptoms of all these differentials. That in itself takes up entire chapters in sports medicine textbooks, and if done well should take up whole textbooks. For those interested, review Peter Brukner and Karim Khan’s text Clinical Sports Medicine (McGraw-Hill Book Company). However, considering that the theme of this series is on muscle injuries, this article will limit its focus to tears/strains of the adductor muscles. Other pathologies will be mentioned in context of management difficulties with adductor muscle strains.
The adductor muscle group consists of the adductor longus/brevis/magnus, pectineus and gracilis. Of these, the adductor longus is the most superficial and easiest to palpate. Along with the gracilis, it is also the most easily injured. An interesting feature of the origin of the adductor longus is that it has fibres that arise from the pubic rami bilaterally and above and below the symphysis pubis. This may be one possible explanation of the migratory and sometimes bilateral nature of the symptoms with adductor longus pathologies.
In relation to the groin area, one must appreciate that within a hand’s breadth space, there exist a number of important anatomical structures that may present as a pathological entity. Above the pubic ramus (suprapubic groin pain) we have the conjoined tendon and its close cousin the inguinal canal. It is in and around the inguinal canal where inguinal hernias develop. Other rarer forms of hernias are umbilical hernias and Sprengel’s hernias. Around this area we also have the abdominal insertions (rectus is of prime importance) and more intimately associated with the pubic ramus is the pubic symphysis. Deep in the suprapubic area we also have the psoas muscle and high lumbar segmental nerves such as the ilioinguinal nerve and iliohypogastric nerve.
Below the pubic ramus (infrapubic groin pain) we have all the adductors and their respective tendons. The other dominant structure is the obturator nerve which has received a degree of recent interest, especially from the medical people at the Olympic Park Sports Medicine Centre in Melbourne, Australia.
Adductor muscles are more commonly strained in sports involving twisting, turning, stepping and kicking, such as all codes of football. They are less commonly injured in straight-line sprinting, with acceleration being the dominant mechanism of injury with this sort of running. Similarly with hamstring injuries, adductor muscle injuries come about because of excessively strong contraction or excessive stretch.
I mentioned before in my articles on hamstring injuries that one school of thought suggests that a muscle must have pre-existing increased tone in order to tear/strain. This rationale maintains that an increase in tone due to some sort of altered afferent input brings a normally healthy muscle closer to its tensile breaking point. Any excessive stretch or contraction may possibly cause the muscle to tear. This reasoning gains some weight in support when one considers how often a pre-existing pathology such as osteitis pubis or an inguinal hernia is soon followed by an adductor muscle tear or vice versa.
Another interesting consideration is the neurology of the ilioinguinal nerve. It is novel to suggest that irritation of the ilioinguinal nerve (which innervates the motor component of the transversus abdominus and lower abdominals, and sensory component of the groin area) may in fact be a precursor to the general groin syndromes we know as adductor tendinopathy/osteitis pubis/inguinal hernia. Repetitive sprinting, turning and kicking may excessively load and stretch the psoas and abdominal muscles. This may generate an interface problem with the ilioinguinal nerve so that irritation of the nerve develops and, as a cause and effect consequence, the groin becomes irritated and poor muscle control leads to weakening of the abdominal wall, poor stability of the symphysis pubis and altered adductor-abdominal synergy during ballistic movement. As a result, breakdown of the groin area ensues. This may then be a plausible explanation as to why pathologies very often co-exist with ongoing groin pain. If any reader has the time or inclination to research such a topic it would make for some ground-breaking and innovative material.
An athlete presenting with an adductor strain/tear will usually remember a definite episode leading to the injury, whether caused by sprinting, turning, stepping or kicking. Usually immediate pain is felt in the adductor attachment or in the two to three centimetres below the attachment. The athlete will demonstrate some degree of functional difficulty, whether it be inability to sprint or kick, and even walking may be hindered.
Often the adductor episode is preceded by abdominal or groin pain in the weeks leading up to the injury. For example, a posterior abdominal wall weakness may cause initial pain in the lower abdominal and/or referred into the groin. As mentioned above, due to possible reflex pathways the abdominal pain may then cause spasm and increased tone in the adductor group, leading to tightness and subsequent tearing.
The best way to test strength and inhibition of the adductor muscles is through the ‘Adductor Squeeze’ test. This is done with the patient lying on the table with the legs extended. The examiner places two clenched fists together between the patient’s knees and the patient then squeezes the knees onto the examiner’s fists. With acute injuries, it is advisable that the patient is instructed to slowly build pressure until maximum pressure is achieved. Pain and inhibition are then subjectively assessed. The same test is then done with the feet up on the table and the knees bent to 45 degrees. The third and final position is feet off bench with hips at 90 degrees. It is necessary to test all three positions, as acute tears may actually be pain-free in one of these testing positions.
The purpose of these tests is to qualify pain and inhibition at all testing positions and to gain some ‘asterix’ points for re-assessment in the near future.
It is important to gain an impression of where the majority of tenderness exists. When felt the adductor tubercle is in most healthy people usually tender. Do not confuse tenderness in this point as direct evidence of the source of the pain. Compare sides and qualify that the pain and tenderness correlates with the pain felt on functional movements and adductor squeezes. Carry on and palpate the entire proximal muscle bellies (longus, brevis, magnus, gracilis, pectineus) for areas of tenderness, accumulated swelling, obvious defects or soft tissue induration. Continue down the entire muscle feeling for reactive spasm and trigger points. Finally, don’t forget to turn the patient over and palpate the posterior fibres of the adductor magnus.
The hip joint, lumbar spine and sacroiliac joints (SIJ) are all related via the kinematic chain to the groin area.
Assessing hip joint internal rotation is probably the most important and significant rotation direction to feel in relation to adductor problems, measuring internal rotation in both 90 degrees flexion and prone lying hip neutral. Rotation at 90 degrees is the more important range to gauge when dealing with adductor problems.
Decreased internal rotation is a common finding in athletes with osteitis pubis, inguinal hernias and lumbar spine pathologies. Lack of internal rotation may lead to a compensatory increase in hip abduction with stepping and cutting manoeuvres. This may then lead to excessive force being placed on to the adductor muscles and an injury may result.
Lumbar spine mechanics may have a complex and important role in the development of adductor-muscle problems. Lack of intersegmental lumbar extension will lead to a compensatory increase in hip extension, external rotation and pelvic rotation during the terminal stance phase of gait. This may lead to extra stress being directed at the hip flexors and adductors while sprinting and kicking. This coupled with poor lower abdominal control of the pelvic girdle may then lead to poor force transfer from the thigh, across the pelvis and into the trunk. Lumbar spine rotation is also implicated in the kinematic chain patho-mechanics of the hip joint and adductor region. A lack of low lumbar rotation may lead to an obligatory increase in hip joint rotation while changing directions. This coupled with a relatively restricted hip joint may then predispose the groin area to excessive force accumulation and subsequent tearing.
It is interesting to note how often athletes complain of a tight and restricted lumbar spine (usually unilateral and usually left-sided) in the few days preceding an adductor muscle tear. This is purely an observed clinical finding and has no empirical evidence based backing. One could rationalise that a tight and restricted lower lumbar spine may then cause a relative increase in hip joint movement that places more force on the unprepared adductor muscles. It is also interesting that clinical observation suggests that most of this occurs on the left side. It is a common finding, as I’ve said before in SIB, that the most common pelvic pattern is to have a hypertonic right TFL and psoas and a hypertonic left gluteus medius and gracilis. This is not to suggest that the majority of adductor tears are left-sided. However, in my experience, the balance is certainly not 50-50 left and right. Left sided tears do seem to predominate. However one must appreciate that this is most likely very dependent on the sport involved.
For the same reasons mentioned above, a restricted SIJ may cause a compensatory increase in motion required at the hip joint and adductor region. Exponents from the osteopathic school of thought will highlight how often a tight and restricted SIJ glide (as measured subjectively on a SQUISH test) will precede an adductor muscle tear on the opposite side. That is, a restricted right SQUISH may be associated and precede a left-sided adductor tear. Again, the complex interplay of all the joints making up the kinematic chain must be addressed.
Controlling movement of the lumbar spine and pelvis is an essential component in providing a solid base from which the thigh muscles can function. Good activation and patterning of the deep stabilising muscles and the superficial ‘core’ muscles will reduce stress on the spine and minimise unwanted transfer of stress to the thigh muscles.
It is interesting to note that the Australian Rules Football Medical Committee is currently undertaking a large cohort study on the role Transversus Abdominus (TrA) has in the development of osteitis pubis. The biomechanical rationale is that poor TrA function leads to poor closure of the symphysis pubis during movement and thus the symphysis is subject to more shear force and subsequent breakdown. The role this has on the development of groin tears is more difficult to deduce.