Groin pain in athletes is a common and challenging entity. The differential diagnosis includes adductor longus dysfunction, osteitis pubis, sports hernia (sportsman's hernia, pre-hernia complex, and Gilmore groin), and hip joint pathology (femoroacetabular impingement and disorders of the labrum, the chondral surfaces, and the capsular structures).
Our definitions of the three extra-articular causes of athletic groin pain are (1) adductor dysfunction, which is considered to be present if the physical examination demonstrates tenderness at the adductor enthesis as well as pain on passive adductor stretching and on resisted adduction; (2) osteitis pubis, which is inflammation of the pubic symphysis manifesting as a tender symphysis and which can be identified on magnetic resonance imaging; and (3) sports hernia, which is a clinical diagnosis confirmed at surgery and consists of any combination of a torn external oblique aponeurosis, a torn conjoined tendon, and dehiscence between the conjoined tendon and the inguinal ligament1-4 (Table I).
Of the four adductor muscles, the adductor longus is the one chiefly implicated in groin pain in athletes4,5. The adductor longus enthesis is a fibrocartilaginous structure6. Entheses are sites of stress concentration and hence prone to injury, damage, and inflammation—known as enthesopathy6,7. This manifests clinically with the triad of tenderness, pain on passive stretching of the affected muscle, and pain on resisted muscle activation.
We previously defined a magnetic resonance imaging protocol to identify adductor enthesopathy8. We also evaluated a group of competitive athletes with adductor dysfunction, in whom we demonstrated the source of pain to be the adductor enthesis and evaluated the efficacy of pubic cleft injections9. Magnetic resonance imaging predicted which of those competitive athletes would respond to the pubic cleft injection. We are not aware of any previous reports on recreational athletes with adductor enthesopathy. The aim of the present study was to investigate the nature of adductor enthesopathy in recreational athletes, defined as individuals who participate in sports fewer than four days per week and do not have a coach.
Between 2005 and 2006, twenty-eight consecutive recreational athletes presented to our sports medicine clinic with groin pain attributed to adductor longus dysfunction. All patients presenting to the clinic with groin pain were assessed in the same way—with use of the techniques for groin examination described and validated by Hölmich et al.10, with a standard hip examination, and on the basis of a true pelvic plain anteroposterior radiograph. Only patients with pure adductor longus dysfunction (i.e., no clinical or radiographic evidence of hip joint pathology and no clinical evidence of sports hernia or osteitis pubis) were included in this study (Table II).
The inclusion criteria, based on our clinical criteria for the diagnosis of adductor dysfunction (Table I), were threefold: tenderness localized to the adductor longus origin, pain on passive stretching of the adductors, and pain on adduction of the thigh against resistance. All three tests were positive for all patients included in this study. Athletes were included only if they had failed to respond to a period of treatment that included rest, application of ice, use of analgesics and/or nonsteroidal anti-inflammatory medications, and physiotherapy. The physiotherapy consisted of a progressive rehabilitation program with adductor stretching, closed-chain adductor strengthening, open-chain adductor strengthening, and a function and/or sports-specific exercise program. Patients were excluded if they exhibited clinical evidence of osteitis pubis or sports hernia or clinical or radiographic evidence (on plain radiographs or a magnetic resonance arthrogram) of hip joint pathology. The recreational athletes competed in a variety of sports, including soccer (fourteen patients), rugby (six), golf (three), squash (two), cycling (one), swimming (one), and triathlon (one).
All twenty-eight athletes met the criteria for a diagnosis of unilateral adductor dysfunction and were enrolled into the study. All were subsequently managed in the same way, and none were lost to follow-up.
Pain was categorized as either acute (beginning immediately after a discrete event) or gradual in onset and scored according to the 4-point functional pain classification scale of Puffer and Zachazewski11 (Table III).
All patients had a magnetic resonance imaging scan, performed with a Philips Intera 1.5-T system (Philips Medical Systems, Best, The Netherlands), within one week after presentation to the clinic. Imaging was performed according to our previously described protocol9 and included axial T2-weighted fast-spin-echo and coronal short tau inversion recovery (STIR) sequences of the entire pelvis, performed with the use of a body coil (5-mm slice thickness, 256 × 256 matrix, and 37.5-cm field of view). Oblique axial T2-weighted fast-spin-echo fat-suppressed and oblique axial and sagittal T1-weighted conventional-spin-echo and T1-weighted conventional-spin-echo fat-suppressed post-intravenous dimeglumine gadopentetate (Magnevist; Schering, Berlin, Germany) sequences of the anterior aspect of the pelvis (all with a slice thickness of 4 mm with 0.4-mm spacing and a field of view of 22 cm) were performed with use of a flexible surface coil (Synergy; Philips Medical Systems) (Figs. 1-A and 1-B). The magnetic resonance imaging scans were evaluated by a musculoskeletal radiologist (P.R.) for the presence or absence of adductor longus enthesopathy, which was defined as abnormal enhancement of the adductor longus enthesis on the postgadolinium sequences. The radiologist was provided with full clinical details. Patients with no evidence of enthesopathy on magnetic resonance imaging were assigned to Group 1, and those with a finding of enthesopathy on magnetic resonance imaging were assigned to Group 2.
All twenty-eight athletes received a pubic cleft injection within one week after presentation (and following the magnetic resonance imaging scan). The injection was performed under image intensification or ultrasound guidance. The pubic hair was shaved, and the area was aseptically prepared. A 21-gauge needle was inserted into the pubic cleft and directed toward the adductor longus enthesis. The enthesis was located through ultrasound or by utilizing image intensification to visualize the osseous landmarks—i.e., the angle between the pubic crest and the pubic symphysis (Fig. 2). The image intensification technique relies on the surgeon integrating what he or she sees on the image with tactile feedback from the needle. The needle is first directed into the pubis and then moved a few millimeters into the fibrocartilaginous enthesis, where the injection is sited. If the needle is withdrawn too far laterally, a "give" is felt as it encounters the lower resistance of the soft tissues. The injections contained triamcinolone acetonide (80 mg in 2 mL) mixed with Marcaine (bupivacaine; 3 mL of a 0.5% solution). Reassessment was performed five minutes after the injection, and consisted of palpation over the adductor longus insertion site, passive stretching of the adductors, and active adduction against resistance.
The patients were then provided with a program of closed and open-chain adductor strengthening and stretching exercises. They were advised to return to full training one week following the injection as comfort allowed, with no limitations or precautions. The patients were seen in the clinic at least three times during the year following the pubic cleft injection: at approximately six weeks, six months, and one year. They were sent a questionnaire, which was reviewed with the patient at the one-year follow-up appointment. The aim of this observational study was to assess the results of an investigation (magnetic resonance imaging) and treatment (injection) in a group of recreational athletes with enthesopathy.
Statistical Methods
Chi-square and t tests were used to compare the characteristics of the two groups. P values of <0.05 were considered significant.
Source of Funding
No funding was received in support of this project.
Radiographic
All plain radiographs of the hip joint showed normal findings, with no evidence of femoroacetabular impingement. On the basis of the findings on the magnetic resonance imaging performed within one week after presentation to the clinic, we divided the athletes into two groups. Group 1 consisted of fifteen patients with a negative finding for enthesopathy, and Group 2 consisted of thirteen patients with a positive finding for enthesopathy. The patients in Group 1 ranged in age from eighteen to forty-nine years (mean, thirty-two years). One athlete had type-1 pain; five, type-2; seven, type-3; and two, type-4. The mean duration of symptoms was sixty-five weeks (range, one to 200 weeks). The patients in Group 2 ranged in age from twenty-five to fifty years (mean, thirty-five years). Nine patients had type-3 pain, and four had type-4 pain. The mean duration of symptoms was seventy-eight weeks (range, sixteen to 200 weeks).
Activity-Related Symptoms (Table IV)
Seven of the fifteen athletes in Group 1 and five of the thirteen in Group 2 had pain on kicking. Twelve of the fifteen athletes in Group 1 and all thirteen in Group 2 had pain on sprinting. Five athletes in Group 1 and four in Group 2 had contralateral radiation of pain.
Statistical Comparison of the Groups
Higher grades of pain were associated with magnetic resonance imaging evidence of enthesopathy (p = 0.04); this was consistent with the results of logistic regression analysis. With the numbers studied, patient age and the time in weeks since the onset of pain had no significant effect on the pain grade either independently or in a multivariate logistic model. The effect of the sex of the athlete on the pain grade was not evaluated, as there were only two women in the series. Use of a t test to compare the variables in the two groups revealed a significant difference in the duration of symptoms since the onset (t = 3.0, p = 0.005). In Group 1, the mean pain score was 2.6 and the mean duration of symptoms was sixty-five weeks. In Group 2, the mean pain score was 3.3, and the mean duration of symptoms was seventy-eight weeks.
Post-Injection Results
Immediate
All twenty-eight patients reported resolution of the pain when they were clinically reassessed with respect to adductor dysfunction five minutes following the injection of the local anesthetic and corticosteroid. All athletes had negative results on all three tests for adductor dysfunction at the five-minute reassessment.
Six-Week Follow-up
No complications related to the pubic cleft injections were reported. At six weeks after the injection, one athlete in Group 1 and two athletes in Group 2 reported a recurrence of symptoms.
One-Year Follow-up/Overall Results
Nineteen athletes had a good result, with no recurrence of their symptoms, and were playing at their premorbid level, free of pain. Nine athletes reported a transient response to the injection with a recurrence of the pain at an average of nine weeks (range, two to twenty weeks) after the injection.
In Group 1, five of the fifteen patients had a recurrence of the symptoms, at a mean of fourteen weeks (range, seven to twenty weeks) following the injection. Two of the five had mild recurrent symptoms (type-1 unilateral pain), which resolved after another injection. In Group 2, four of the thirteen patients had a recurrence, at a mean of eight weeks (range, two to nineteen weeks) after the injection.
There was no significant difference in the rate of symptom recurrence between the two groups. According to a test of equality of proportions, the recurrence rate in Group 1 was 33.3% (95% confidence interval, 9.5% to 57.2%) compared with 30.8% (95% confidence interval, 5.7% to 55.9%) in Group 2. With the numbers studied, magnetic resonance imaging evidence of the enthesopathy was not associated with recurrence.
In the majority of athletes who have pain in the groin, the condition is transient and is successfully treated with nonoperative means. Historically, groin pain has been attributed to one of four broad etiological categories: adductor longus dysfunction, osteitis pubis, sports hernia, or hip joint pathology1-5. We believe that adductor enthesopathy is a potential source of adductor-related groin pain; our previous study of competitive athletes with adductor-related groin pain established that the adductor enthesis was the source of the pain9. To our knowledge, no one has studied recreational athletes with adductor-related groin pain, and we believe that we are the first to evaluate the response of recreational athletes with adductor-related groin pain to entheseal pubic cleft injections.
All patients in this study had painful adductor dysfunction. At five minutes following an entheseal injection of a local anesthetic, all reported that provocation maneuvers caused no pain. This finding mirrors that reported in competitive athletes9. Thus, the adductor enthesis appears to be a source of adductor-related groin pain in both recreational and competitive athletes.
In our previous study9, there were significant differences between competitive athletes with a positive finding for enthesopathy on magnetic resonance imaging and those with a negative finding. Competitive athletes without evidence of enthesopathy on magnetic resonance imaging were likely to be pain-free at one year following an entheseal pubic cleft injection. In contrast, those with evidence of enthesopathy on magnetic resonance imaging were likely to be in pain and unable to resume sports activity at one year after the injection. In the present study of recreational athletes, a finding of enthesopathy on magnetic resonance imaging was not associated with recurrence of the pain. While our previous study demonstrated that evaluation with magnetic resonance imaging was essential for competitive athletes, it was not for the recreational athletes in the present study. While definitive statements cannot be made and each patient must be assessed on a case-by-case basis, we suggest that most recreational athletes with adductor enthesopathy be treated empirically with an entheseal pubic cleft injection. However, we believe that magnetic resonance imaging certainly has a role for some recreational athletes, such as when there is diagnostic uncertainty or the possibility of dual pathology.
There were three main differences between the recreational athletes in this study and the competitive athletes in the previous study9: (1) the recreational athletes were older, (2) they presented later, and (3) they were more likely to have a good result following the entheseal pubic cleft injection. Entheseal injections produced a good result in twenty-one of the twenty-eight recreational athletes, irrespective of the findings on magnetic resonance imaging. It seems paradoxical that older patients with a longer duration of symptoms (as was seen in the recreational group) would have a better outcome following the injection. This may be explained to some extent by the fact that recreational athletes tend to have lower demands than their competitive counterparts and are more able to rest, particularly as a return to their sport does not equate a return to their livelihood for these patients. Also, we suggest that recreational athletes may be able to resume a similar level of activity with an altered technique (thereby avoiding repetitive microtrauma) more easily than their competitive counterparts.
Two athletes in Group 1 (no enthesopathy seen on magnetic resonance imaging) had a mild recurrence with type-1 unilateral pain, and they had a successful repeat injection. Therefore, we believe that repeat injection can be considered for recurrence in recreational athletes, especially those with negative findings on magnetic resonance imaging and mild pain.
Shortfalls of the present study are its retrospective design and the limited number of subjects. Furthermore, no system was available for scoring the outcome of treatment of adductor-related or groin injuries in athletes.
To our knowledge, there has been no differentiation, in the literature, between the levels of performance of athletes with adductor-related groin pain. This study was performed to assess recreational athletes and identify differences or similarities between them and competitive athletes. Perhaps the important similarity between the two groups is that the adductor enthesis is the pain source. However, recreational athletes are usually older, present with more chronic symptoms, and as a group do better following an entheseal injection. We suggest that it is reasonable to employ an entheseal pubic cleft injection as a diagnostic and potentially therapeutic procedure in recreational athletes with adductor dysfunction, even in the absence of a magnetic resonance imaging scan. 