Testing and Treating the Athlete with Groin Pain
Competitive and recreational sports athletes can develop painful groin symptoms from a pulled muscle. The condition is called adductor enthesis. Adductor refers to the group of four leg muscles that attach to the pubic bone in the pelvic/groin area. Enthesis is the place where the tendon meets the bone. Usually this spot is a mixture of fibrous and cartilage soft tissue. Overuse from repeated kicking and/or sprinting sets up an inflammatory response that eventually becomes chronic with telltale changes in the soft tissue structures.
The condition is diagnosed through a combination of patient history, clinical tests, and MRIs. The groin pain may occur only after activity or it may be described as occurring with activity but without restricting movement. More severe pain will restrict activity; some athletes with adductor enthesis have chronic (constant) pain that may get marginally better but never goes away.
In this study, athletes evaluated and treated at a sports medicine clinic for groin pain were treated with a steroid injection combined with a numbing agent. To be included in the study, each athlete had to test positive for three tests: tenderness with palpation of the adductor longus where it inserts in the pubic bone, pain with stretching of the adductor muscles, and pain with resistance to the adductor muscles. The adductor muscles are the main muscles used to pull the leg toward the body. Stretching the adductors occurs when the leg is moved away from the body. When these tests are positive, it confirms that the pain isn't coming from inside the hip joint. That means the pain is extra-articular (outside the joint).
Before the injection was done, X-rays were taken to confirm normal hip structure and alignment. Anyone with hip problems was excluded from the study. An MRI of the groin was also obtained. A contrast dye was used to look for any pathology of the enthesis. Tears in the fibrous cartilage insertion of the adductor muscles can show up as an abnormal enhancement as the dye seeps into the open (damaged) fibers. Not everyone with groin pain and positive muscle/tendon tests had a positive MRI. Those who did were put in one group. Those with positive muscle/tendon tests but without obvious changes on MRI were placed in a second group. All were treated with the injection followed by a physical therapy rehab program. The only difference between the groups was whether or not the MRI was positive for adductor enthesis.
The key focus of this particular study was the fact that the patients were all recreational athletes. In a previous study, this same group of researchers performed the same study on competitive athletes. The aim of this study was to compare the two groups (competitive versus recreational athletes). Recreational athletes are defined as those individuals who participate in sports less than four days each week. They do not have a coach. Competitive athletes engage in sports activity at least four days a week under the supervision of a coach. Any type of sports involvement was acceptable and happened to include swimming, squash, cycling, rugby, golf, soccer, and triathlon.
Five minutes after the injection was given, the patients were re-evaluated using the same three tendon tests: palpation, stretching, and resistance. Results were recorded (pain or no pain) and the tests were repeated at six weeks, six months, and one year later. In every case, the pain was relieved immediately. That means even patients with no findings on MRI benefited from the injection.
Now, did these positive results last? Well, one-third of the patients in group one (no evidence of a problem on MRIs) had a recurrence of their groin pain during that first year. For some patients, the pain came back as early as seven weeks after the injection. For others, they had pain relief that lasted at least three months. What about group two (those who did have a positive MRI showing tendon pathology)? Same thing: about one-third of the group had another bout of groin pain anywhere from two weeks to 19 weeks after the injection.
And how did the results of the recreational athletes compare with the competitive athletes who had the same problem, same tests, and same treatment? Well, the MRI findings did predict results of injection. Patients with visible tendon enthesis damage were more likely to experience pain recurrence affecting their ability to play one year after the injection. Competitive athletes with a negative MRI who had the injection, got better and stayed pain free.
The authors summarized by saying that MRI findings do not predict treatment outcome for recreational athletes using steroid injection for adductor enthesis. Quite the opposite is true for competitive athletes whose MRI does predict the final results. Comparing the two groups, it looks like there were two main differences that might account for these findings. One, the recreational athletes were older and had their groin pain longer. And two, because their lives did not depend on competing in their sport, they could rest and take it easy during painful episodes and after the injection treatment.
The authors suspect that the recreational athletes also competed at a lower level of intensity. They could alter their technique to accommodate their symptoms without worrying about their competitive edge. The result is less repetitive microtrauma of the adductor enthesis. They also noticed the recreational athletes with negative MRI and mild pain seemed to have the best results with a second injection when the symptoms came back.
Steroid injections aren't routinely recommended for athletes with groin pain. Those who do not benefit from rest and/or physical therapy and who test positive for tendon pain with palpation, stretching, and resistance may be the best candidates for injection therapy. The surgeon can take into consideration the level of the playing athletes (recreational versus competitive) when ordering and interpreting contrast MRIs.
Ernest Schilders, MD, et al. Adductor-Related Groin Pain in Recreational Athletes. In The Journal of Bone and Joint Surgery. October 2009. Vol. 91-A. No. 10. Pp. 2455-2460.