ANATOMY AND BIOMECHANICS PART 1 -

THE ANATOMY AND BIOMECHANICS RELATING TO GROIN INJURY

By Seonaid Airth, MSc, MCSP, SRP

INTRODUCTION Have you ever seen a patient with chronic groin pain penciled in your diary and felt your heart sink? The chances are you are not alone. Groin pain constitutes one of the greatest challenges in sports medicine (1). Successful management of a patient with chronic groin pain depends on a correct diagnosis but the clinical symptoms are difficult to differentiate and the possible diagnoses are numerous (2).

We can probably all think of an athlete who has struggled with groin pain for some time and who has been everywhere and seen everyone! Groin symptoms are often difficult to explain and an athlete can become extremely frustrated when it takes time for a final diagnosis to be made. Differential diagnosis requires experi- ence and accuracy in the clinical examination, and often requires a multidisciplinary approach (2). Incorrect diagnosis initially can lead to inappropriate treatment, which allows the injury to become chronic.

The incidence of chronic groin pain in rugby and soccer is very high in comparison to the general sporting population and has risen in recent years. Until recently groin pain commonly present- ed as an acute injury to the adductor muscles after a forceful movement such as a tackle or a collision (3). In 1966, a study reported the rate of groin injury in soccer players to be as low as 0.5% of all soccer injuries (4). More recent literature reports the rate of groin injury in soccer players to be greater than 20% (5).

INCREASING INCIDENCE The increased rate of groin injury in soccer and rugby in recent years is due to several factors related to the nature of the sports. In addition, rugby union has seen many players turn professional since 1995 when the sport ceased being entirely amateur. Rugby union is a highly competitive sport which involves the players kicking and carrying the ball, in addition to physical contact in attack and defense. The high velocity kicking involved in both soccer and rugby undoubtedly contributes to groin injury. When a player kicks a ball it is thought a traction force on the kicking leg results in an abnormal lengthening of the contracting adductor muscles which may induce trauma in the muscle (6) as well as shearing forces on the pubic symphysis.

Kicking the ball may not present the greatest risk of sustaining strain in the adductor region however. Rugby union and soccer both involve repetitive changing of direction during training drills and in matches. These side-to-side movements are combined with acceleration and deceleration both forwards, backwards and diagonally.

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These multidirectional and multiplanar movements are thought to be one of the primary mechanisms of injury in regional groin pain (7). Additionally slippery, muddy, wet surfaces compound the problem.

Over recent years there has been an increase in the number of rugby and soccer players who have become professional ath- letes and this is undoubtedly a contributing factor to the increase in chronic injuries. An increase in the length of each playing season is not allowing the players enough time to recover from their injuries and this is an area of growing concern to coaches.

With increasing professionalism in these sports, injuries are also an important issue for the players in terms of their livelihoods. Following injury these players are keen to return for trial games and selection opportunities despite ongoing injuries. If a player returns to sport too early they are at risk of aggravating the injury which may recur and become chronic. It is not uncommon for a player to carry an injury from one season to the next without it being fully rehabilitated and this is a problem for the player and the sports medicine team.

INJURIES TO THE GROIN Clinically the groin is hard to define and symptoms of pathology of the groin may be complex and non-specific (8).

The possible causes of groin pain have been reported in the liter- ature as single pathologies for example osteitis pubis. However in an athlete presenting with chronic groin pain, several diagnoses may be required to adequately describe all of an athlete’s symp- toms (2).

It is beyond the scope of this article to consider all the possible pathologies that may cause groin pain. This article will therefore focus on one of the most common injuries, adductor muscle strain, and examine the factors affecting healing and recovery which may result in recurrence of injury.

ANATOMY The groin is the interface between the pelvis and the lower limb. The primary biomechanical function is to transmit forces from the trunk to the lower limb and vice versa.

In order to fully understand the complexity of the groin area it is essential to have a sound knowledge of the anatomy of the region and of the structures which may produce pain. Groin pain may originate from joints, muscles, bursa, nerves, fascia and internal organs. It may be local or referred and can often radiate distally to the lower limbs or proximally to the abdomen (10).

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