Theme Sports injuries around the hip joint in children and adolescents. K. Corten, J. Bellemans, N. Arnout, J-P. Simon, A. Van Campenhout, P. Moens, G. Molenaers ([email protected]) The Orthopaedic Surgery Department, University Hospitals Pellenberg Keywords: groin, athlete, hip, femoro-acetabular impingement Abstract “Groin” or “hip” pain can represent a difficult differential diagnostic problem in young athletes. Differentiation between intra- and extra-articular problems will allow the clinician to develop a simple algorithm to come to the correct diagnosis. As a rule of thumb, the limping athlete has got an intra-articular problem until proven otherwise because the immature athlete can also present with intra-articular pediatric pathologies of the hip joint that are not directly related to the sports activities. Prevention is the most important treatment option for extra-articular problems such as strains, tendinitis and apophysitis. I. Introduction As more and more children participate in sports and recreational activities, there has been an increase in acute and overuse injuries. A painful hip or groin region is not very common in the pediatric population of athletes but can pose difficult differential diagnostic problems. On top of pathologies that are typically associated with sports activities such as apophysitis or strains, the young athlete can also present with groin pain that is induced by a typical pediatric problem such as Legg-Calve-Perhes disease (LCPD) or a slipped capital femoral epiphysis (SCFE). It is the aim of this paper to provide an overview of the most common pathologies that can be associated with groin pain in the young athlete. “Groin” or “hip” pain can be caused by intra- and extra-articular pathologies. Intra-articular problems should always be excluded. Intra-articular causes of hip pain As a golden rule of thumb one could state that a limp is the most important sign pointing to a possible hip problem. Non-traumatic limping is rarely caused by foot or knee problems. Therefore, every insidious onset of a limp or knee pain should be treated as an intra-articular hip problem until proven otherwise. The most important and most common intra-articular problems of the hip joint are primarily determined by age. sification and follow-up systems are based upon plain radiographs of the pelvis but a pinhole technetium scan allows for assessment of the revascularization status of the lateral pillar of the head, which is prognostic. Immobilization in a wheelchair for up to 6 months aims to prevent excessive flattening of the femoral head in the initial necrotic phase. After this phase, the treatment is directed towards “containment” with a restoration of the concentric position of the femoral head in the acetabulum [2]. Slipped capital femoral epiphysis Slipped capital femoral epiphysis (SCFE) is seen in the pre-adolescent and early adolescent age groups (from 10 to 15 years), especially in overweight boys. SCFE necessitates urgent surgical intervention. A relative insufficiency of the growth plate has been postulated as the cause for the anterior and upward displacement of the metaphysis on the femoral epiphysis, which remains in the acetabular socket. Trauma induced by a sports injury can be associated but is only rarely the cause for the slip. Anteroposterior and Lauenstein radiographs should be taken of both hips. Weight bearing is not allowed until surgical treatment with stabilization of the epiphysis. Despite the awareness of this disease, it still takes by average 3 months prior to the correct diagnosis of a SCFE because the limp has been misdiagnosed as a muscle strain and the symptoms can disappear for several weeks [2]. However, substantial and sometimes irreversible damage of the cartilage and the Figure 1 (a) Legg-Calvé-Perthes disease In the age group of 4 to 10 years, a diagnosis of transient synovitis or Legg– Calvé–Perthes disease (LCPD) should be considered. The etiology of a transient synovitis remains unknown, but it appears to be most frequently associated with a viral infection of the upper respiratory tract or the gastrointestinal system. If the symptoms linger for more than 2 weeks, a new radiograph should be taken to exclude a LCPD. An acute onset of symptoms can occur but should not be associated with fever or an abnormal serology. This would be highly indicative for septic arthritis. In case of doubt, an experienced clinician should conduct an aspiration of the hip joint followed by drainage if required. Eight to ten days of rest with an antiphlogistic should suffice in case of a transient synovitis and a radiograph at 8 weeks can exclude LCPD, which is 3 to 5 times more frequent in boys [1]. The etiology of the avascular necrosis in LCPD remains unknown. During the first weeks of the disease, radiographs can remain normal and magnetic resonance imaging (MRI) or technetium scan can detect early signs of necrosis. Most clas- Tijdschrift van de Belgische Kinderarts • 2011 - Vol. 13 - Nr.3 18 Theme Figure 1 (b) labrum has been found already after several weeks of a slipped epiphysis [3]. This is caused by the repetitive abutment of the metaphyseal bump against the acetabular rim, the cartilage and the labrum (Figure 1). Therefore, a high index of suspicion for SCFE is always indicated in a limping athlete with a limited internal rotation of the hip joint at clinical examination. It has been suggested that the intra-articular damage should be assessed and treated either arthroscopically or with an open procedure (Figure 1) [3]. Figure 1 (c) Femoro-acetabular impingement Femoro-acetabular impingement (FAI) can either be caused by a femoral “cam” deformity (i.e. an insufficient “waist” between the femoral head and neck (Figure 1), an acetabular “pincer” deformity (i.e. a local or general overcoverage of the head by the acetabular rim (Figure 2) or a combination of both. Both deformities cause abutment of one side to the other thereby leading to labral tears and (mainly) acetabular cartilage damage. Figure 1 (a) This 13-year old boy presented with groin pain following skiing. He had been treated elsewhere with in situ pinning for a SCFE. An attempt of reducing the epiphysis on the metaphysis has been associated with an increased risk for avascular necrosis and is therefore not recommended. However, this implies that the metaphyseal bump will abut or impinge against the acetabular rim, particularly in flexion and internal rotation (black circle). This will not only lead to a decreased range of motion but also to cartilage an labral damage, even at short term intervals. He was referred to our department for residual pain in the groin region with a decreased range of motion, particulary in internal rotation. (b) An open reduction of the epiphysis on the metaphysis was conducted with a capital realignment procedure. The metaphyseal bump is obvious. This represents the most distinct form of cam impingement. (c) The post-operative radiograph shows a good reduction of the epiphysis on the metaphysis with a distinct clearance of the head-neck offset (black circle). This solved the impingement problem and a normal range of motion was achieved. Note the small anchor on the acetabular side. This was used for the labral refixation because of the labral tear. The cartilage damage was debrided and an ice-pick procedure was conducted. - epiphysis: thin black arrow - metaphyseal flare: thick black arrow - black circle: impingement zone The labrum is the fibrocartilaginous extension of the acetabulum over the femoral head. Its function is to provide an adequate sealing of the hip joint. This increases the stability of the joint and provides an adequate load distribution over the articular cartilage. This sealing function is disrupted when the labrum is torn. The underlying etiology of FAI is not well understood. However, it is clear that FAI results from a combination of a bony geometry that does not allow for an impingement free range of motion during normal daily living or in certain sports activities. In other words, whether a bony geometry will lead to symptomatic FAI in the young athlete is also highly dependent of the demands of the hip joint in that particular athlete. Particularly pivoting or twisting maneuvers of the hip, such as in tennis, ballet, golf, football, soccer and hockey, can result in injuries to the labrum even in the absence of an abnormal bony morphology of the hip joint. Labral tears are a well-documented source of groin pain with an estimated incidence of 20% in athletes presenting with groin pain [4-6]. Tears most frequently occur anteriorly Journal du Pédiatre Belge • 2011 - Vol. 13 - Nr.3 19 Theme Figure 2 (a) Figure 2 (c) with a typical groin pain at clinical examination induced by a combined flexionFigure 2 (b) adduction-internal rotation maneuver (i.e. the FADIR-test). Patients complain of pain with pivoting maneuvers during sports or when getting in and out the car. They can also present with a clicking sensation in the groin region often irradiating to the lateral side (trochanter region). This indicates a positive C-sign. Properly taken pelvic radiographs (Figure 2a), bilateral Dunn (Figure 2b) and false profile views (Figure 3) allow for assessment of bony abnormalities that can cause FAI thereby leading to labral tears [7]. In our practice, a diagnostic intra-articular infiltration with a local anesthetic is always conducted for the differential diagnosis with extra-articular sources of groin pain or clicking. Painful internal clicking can occur in the presence of a tear but this should be differentiated from “internal psoas tendon snapping” that is caused by the psoas tendon, which roles over the ileo-pectineal eminence when the leg is actively flexed-abducted-external rotated and then brought back to neutral. This is a rather rare cause of hip pain in the pediatric population. MRI or CT arthrography allows for further evaluation of the extent and location of the labral tear. The pediatric and adolescent hip has only recently become better characterized for arthroscopic procedures for septic arthritis, labral disorders, SCFE, and LCPD [8-10]. In case the tear is located anteriorly (as in 90% of the cases) (Figure 2 and 3), then it is accessible with a hip arthroscopy and an arthroscopic refixation of the tear is conducted. In case the acetabular rim has not yet maturated in growth, we tend not to conduct an extensive acetabular rim trimming. A femoral cam lesion in the young athlete is often caused by a mild or undiagnosed SCFE. This can be treated with an arthroscopic osteochondroplasty after the epiphysiolysis has been stabilized or even an open procedure can be required in more severe cases (Figure 1). An open surgical dislocation is required in the rare case Figure 2 A 15-year old high-level hockey player presented at the paediatric multi-disciplinary sports clinic with groin pain. (a) All clinical tests were suggestive for FAI, which was confirmed on plain radiographs as a pincer type impingement (thin black arrow) with a bilateral acetabular center-edge angle of 45°. This should be <39°. The pelvic radiograph was well taken because both obturator foramens are symmetric, the middle of the sacrum is in line with the symphysis pubis and the distance of the tip of the coccyx to the proximal edge of the symphysis is 1-3 cm. (b) The 45° Dunn view of the femur, taken in 45° of flexion and 20° of abduction, showed a normal femoral head-neck offset (thick black arrow) indicating that there was no evidence for cam-type impingement. (c) Arthroscopic evaluation of the hip joint revealed a labral tear at the 12 to 1 o’clock posistion anteriorly which was associated with cartilage damage. (d) A minimal rim trimming with a labral refixation was done. - black circle: impingement zone Figure 2 (d) where the labral tear is located posteriorly as can sometimes be found in ballet dancers or other sports with extreme ROM exercises such as mountain climbers or gymnasts (Figure 4). Developmental dysplasia of the hip Developmental dysplasia of the hip is frequently associated with labral tears (in up to 30% of the cases) (Figure 3). The athlete can present with mild to even moderate acetabular dysplasia that has become symptomatic due to the increased load on the articular surfaces. As a simple rule of thumb, a centre-edge (CE) angle of >25° represents a non-dysplastic hip joint whereas a CE-angle of 20-25° is considered as a mild dysplasia. In the latter cases, shoe modification with a contralateral slight heel lift and an arthroscopic intervention with labral refixation can be sufficient. The labrum should never be debrided and refixed instead. A peri-acetabular osteotomy is conducted in those cases with a CE-angle <20° (Figure 3). Tijdschrift van de Belgische Kinderarts • 2011 - Vol. 13 - Nr.3 20 Theme Figure 3 (a) Figure 3 A 16-year old recreational tennis player complained of groin pain during twisting maneuvers. (a) She presented with clinical findings suggestive for labral pathology. The plain pelvic radiograph showed a moderate dysplasia of the hip with a lateral CE-angle of 17° (normal >25°). The false profile view of Lequesne showed that the anterior coverage of the femoral head was insufficient with an anterior center edge angle of 10° (normal 20-25°). (b) There was an inflamed labrum with a tear. Intensive physiotherapy for approximately 1 year could not improve her symptoms and a peri-acetabular osteotomy was conducted. (c) This showed a post-operative improvement of the lateral and anterior CE-angle. Figure 3 (b) Figure 3 (c) Journal du Pédiatre Belge • 2011 - Vol. 13 - Nr.3 23 Theme The hamstrings insert on the ischial tuberosity and can also pull off the apophysis with forcefull eccentric contraction or sudden excessive passive lengthening such as during a sprint, in dancers or gymnasts. The problem with displaced ischial tuberosity avulsions is the potential development of a fibrous union. Therefore, the lesion is treated with bed rest, restricted activity and return to athletic activity over 6 to 12 weeks. Care should be taken to avoid early vigorously stretching of the involved muscle group. Figure 4 Figure 5 (a) Figure 4 A 17-year old ballet dancer presented with left trochanter and buttock pain that could be exacerbated in hyperextension-external rotation. There was no pain with the FADIR test. A posterior tear (thin black arrow) of the labrum (thick black arrow) was confirmed on CT-arthrography. These tears are not accessible during a hip arthroscopy and are preferably treated with an open surgical dislocation procedure. Figure 5 (b) Extra-articular problems A strain is an injury caused by stretching or exerting a muscle beyond its limits. Muscle strains can occur in any athlete, but especially in runners and in children participating in sports where running is part of the game, such as soccer and basketball. Strains at the apophysis or apophysitis are more common in early adolescence. Tendinitis can occur at any age but most frequently occurs during adolescence. Injuries of the pelvic apophysis Apophyseal injuries or apophysitis typically occur during adolescence between 11 and 15 years of age. The apophysis is then the “weakest link” in the musculoskeletal system when rapid bone growth exceeds soft tissue development during the growth period. Injury to the iliac crest apophysis can result from acute or chronic stresses exerted by the abdominal muscles. In an acute injury, the partially ossified apophysis, which usually is the anterior portion of the bone, is separated and displaced from the underlying iliac crest [11]. This is most often caused by an abrupt change of direction such as during tennis with power serves and ground strokes (particularly with a two-handed play). Chronic stress from repeated submaximal muscular pull will result in little or no displacement of the tender apophysis [12]. The resultant 3-5mm physeal widening is often missed on radiography but can be seen on MRI with accompanying oedema. Treatment with antiphlogistics, activity modification and rehabilitation of the trunk and abdominal muscles is often successful. The direct head of the rectus femoris tendon and the sartorius insert to the anterior inferior and superior iliac spine, respectively. A forceful pull of the tendon with flexion of the hip (i.e. a kick or a sprint) can induce an avulsion injury of the spine. In tennis, these lesions can occur due to a relative overpull of the sartorius or rectus femoris muscle respectively during jumping or running or a sudden acceleration motion. This can be most often treated conservatively with rest, ice and functional rehabilitation over 3-4 weeks. After a painless hip ROM has returned, lateral abdominal and hip abduction exercises may begin. However, in some rare cases a refixation procedure is required due to the risk of extra-articular impingement or in case of a non-union (Figure 5). Figure 5 A 13-year old high level soccer player sustained an avulsion of the anterior inferior iliac spine. (a) This was documented on plain pelvic radiographs but was best notable on the false profile view (thick black arrow) on which it was also clear that the spine was displaced in the caudal direction. (b) Rest and anti-inflammatory physiotherapy could not improve the symptoms after 4 months and the MRI revealed that there was oedema at the apophysis. Note the small interval between the spine and the hip joint. (c) Because the apophysitis remained symptomatic and the displaced spine could lead to sub-spine impingement, it was decided to conduct an open reduction of spine with a cranial refixation. Note the clearance of the space between the inferior spine and the hip joint. The sub-spine impingement has been treated. Tijdschrift van de Belgische Kinderarts • 2011 - Vol. 13 - Nr.3 24 Theme movements such as hockey or soccer players [15]. Insufficiency fractures of the pubic rami or the femoral neck occur from excessive and repetitive loading of the bone, usually in high-level athletes. Although male patients can be affected, a higher incidence is found in female athletes with predisposing factors such as poor conditioning prior to training, amenorrhea, low calcium levels and distorted nutrition habits (i.e. the “female athlete triad”: distorted eating, amenorrhea and osteoporosis) [17,18]. Bone lesions such as e.g. an osteofibroma should also be excluded. A periosteal reaction is a common radiographic finding around the pubic bone (“periostitis”). MRI is the most sensitive assessment method for early detection of these stress fractures [19]. These patients can be treated with relative rest guided by the symptoms, calcium intake and nutrion advice. Figure 5 (c) Isolated adductor injuries can also occur, typically in sports with repetitive adduction such as breaststroke swimmers, ice hockey or soccer players [20-22]. Several risk factors have been identified such as previous injury and a greater abductor to adductor strength ratio [22]. Specific post-injury exercises focused on prevention of groin strain injury and restoring the abductor-adductor strength ratio are thus important [22]. Restoration of the stabilizing role of the pelvis by abdominal contraction may thus be important in athletic injury management and prevention. Finally, pre-season sport specific training has been shown to be associated with a subsequent decrease in groin injury [22]. Miscellaneous pathologies Iliopsoas tendinitis Activities involving hip flexion, extension and adduction such as soccer, rowing and running can be associated with a painful sensation in the groin, which is caused by an inflamed psoas tendon and bursa. An ultrasound or fluoroscopic guided percutaneous injection can obviate the need for a surgical tendon release [13]. The tendon can move over the pectineal eminence thereby causing an audible snap during movements from flexion-abduction-external rotation to neutral such as is often done in karate or ballet (internal snapping) [14]. Although the patient often perceives this, it does not require treatment unless it is associated with a painful tendinitis. Surgical release is only -and rarely- conducted when all conservative measures including physical therapy and steroid injections failed. The differential diagnosis with other problems that cause a clicking sensation such as external snapping (i.e. movement of the iliotibial band over the greater trochanter), labral tears or intra-articular loose bodies should be made. Athletic pubalgia Athletic pubalgia is most frequently seen in athletes that rely on quick acceleration, rapid directional changes, kicking, and side-to-side movements [15]. The conjoined insertion of the abdominal musculofascial structures and the adductor muscles of the thigh around the pubic symphysis can cause an acute or progressive groin pain that is also called “sports hernia” [15]. Injury to the insertion of the rectus abdominis muscle alone or in combination with adductor tendon injury is the most frequent pattern of injury identified on MRI [16]. Most commonly, the injuries are initially unilateral but the repetitive unbalanced contractions may lead to extension of the injury to adjacent areas [16]. It is very uncommon to find a true hernia. Pain can be reproduced with resisted hip adduction or sitting up and there can be focal tenderness over the pubis or the immediately adjacent external inguinal ring. The conservative treatment of the imbalance between the abdominal and adductor muscles is often difficult and the recurrence rate is high, often requiring surgical intervention [15]. Osteitis pubis or stress fractures of the pubis should be considered in the differential diagnosis of a painful symphysis pubis region. These injuries are particularly found in long distance runners and athletes that kick, twist and undergo lateral It is important to consider non-sport-related causes of groin pain in athletes. The differential diagnosis for groin pain should include appendicitis, Crohn’s disease, nephrolithiasis, inguinal hernia, pelvic inflammatory disease, menstrual cramps, and ovarian cysts [23]. Finally, hip arthritis and enthesitis are frequently seen in juvenile-onset spondylarthritis disease [24]. Spondyloarthritis in children is often undifferentiated at onset, and is less likely to involve the axial skeleton but more likely to affect hips and peripheral entheses. It should therefore be considered in the differential diagnostic algorithm of atraumatic or insidious onset hip and groin pain. Bone or soft tissue tumours around the hip joint should not be missed. Malignant tumours such as the osteosarcoma or the Ewing sarcoma are rare. More common are the benign tumours originating from cartilage such as the enchondroma and cartilagineous exostoses. Solitary bone cysts and fibrous dysplasia of bone can be easily diagnosed by their typical appearance in radiographs and MRI. Osteoid osteoma is a benign bone tumour, which typically leads to exacerbation of pain during the night that is often -but not always- relieved by aspirin. Clinical and radiological signs of this small (usually 0.5 cm in diameter) benign tumour may mimic many other diseases. Repeated clinical and radiographic examination in defined time intervals is the treatment of choice for most benign bone tumours. Finally, nerve entrapment syndromes (i.e. the lateral femoral cutaneous nerve, the ilioinguinal nerve and the pririformis syndrome) and bursitis (i.e. trochanter, pectineal or ischial tuberosity bursitis) can occur but are in general less frequent in young athletes. Conclusion Young athletes can present with various problems around or in the hip joint. Differentiation between intra- and extra-articular problems will allow the clinician to develop a simple algorithm to come to the correct diagnosis. The limping athlete has got an intra-articular problem until proven otherwise. This can most often be diagnosed with a good clinical examination and standard radiographs. An intra-articular diagnostic injection can be very helpful in chronic cases. 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