FIGURE 121.7 CT views (axial, coronal, sagittal) of intra-articular air in anterior and posterior knee joint following penetrating injury sustained from fall on edge of stone General therapy for these injuries must emphasize several points Rest is crucial for the specific area involved until pain has completely resolved The athlete should be actively encouraged to use alternative activities to maintain conditioning during this time The role of inflammation in overuse injuries is controversial, but the application of ice and use of anti-inflammatory agents is generally recommended Directed stretching as well as strengthening exercises reduce tension on affected areas Biomechanics should be assessed and corrected when necessary When returning to full activity, an appropriate training regimen should emphasize a slow gradual buildup in intensity and duration and should include explicit limits The sudden increase in intensity and duration of training that occurs with a change of sporting season is a major culprit in overuse injuries Numerous overuse syndromes have acquired popular eponyms Among the most common overuse syndromes in children are Osgood–Schlatter disease, Little Leaguer elbow, and Sever disease The diagnosis of apophysitis is made clinically Imaging may show nonspecific changes, but is only indicated in the presence of acute or severe symptoms to exclude avulsion fractures Osgood–Schlatter Disease Osgood–Schlatter disease is an apophysitis of the tibial tubercle Repetitive stress imposed by the patellar tendon on its site of insertion results in a series of microavulsions of the secondary ossification center and underlying cartilage The condition is most common in running and jumping athletes between the ages of 11 and 15 years prior to closure of the tibial growth plate Boys are most commonly affected, but the rising incidence among girls may be because of increased participation in sports that have previously involved mostly boys Findings of Osgood–Schlatter are bilateral in a quarter of cases, although symptoms are commonly asymmetric The physical examination is notable for localized tenderness at the tibial tubercle Any action that applies tension to the patellar tendon elicits pain Placing the patient prone and flexing the knee so the heel contacts the buttocks will typically trigger pain at the tibial tubercle Additional maneuvers that are likely to cause pain include forced extension of the knee, jumping, squatting, or direct pressure as when kneeling In advanced cases, callus formation occurs, resulting in further prominence of the tubercle Some experts have suggested a relationship between Osgood–Schlatter disease and acute avulsion fractures of the tibial tubercle ( Fig 121.8 ) The diagnosis is based on the clinical features Radiographs are not necessary in typical cases Atypical presentations including pain at night, pain unrelated to activity or sudden onset of pain should undergo imaging to rule out bony disorders that may mimic Osgood–Schlatter disease In the early stages of the disease, radiographs are normal Fragmentation of the tibial tubercle can be a normal finding in the adolescent and must be correlated with clinical findings In advanced stages of the disease, avulsions from the secondary site of ossification may form ossicles that are visible on a lateral radiograph of the knee FIGURE 121.8 Acute tibial tubercle avulsion fracture in a child with history of Osgood– Schlatter disease Management consists first and foremost of avoiding activities that place stress on the tibial tubercle This is perhaps the most difficult instruction to enforce in young athletes A brief period of immobilization or nonweight bearing is recommended by some as a means of ensuring compliance Application of ice for 20 minutes at least twice daily will reduce pain and swelling Nonsteroidal antiinflammatory medications are commonly recommended Activity may be resumed when the patient is free of pain Flexibility exercises concentrate on stretching the quadriceps and hamstrings to alleviate stress on the tubercle and avoid recurrences A neoprene sleeve on the knee or patellar tendon strap will reduce forces on the tubercle Over 90% of cases resolve within 12 to 24 months with conservative treatment Sinding-Larsen–Johansson Disease The tension in the infrapatellar tendon that causes Osgood–Schlatter disease is also transmitted proximally to the inferior pole of the patella A traction apophysitis at this site results in pain and localized tenderness, and is known as Sinding-Larsen–Johansson disease The predisposing factors for this injury are the same as those for Osgood–Schlatter disease, and include running and jumping activities Sinding-Larsen–Johansson disease and Osgood–Schlatter disease can occur simultaneously Provocative maneuvers that produce discomfort in Osgood–Schlatter disease produce pain at the distal patella Radiographs are nonspecific but may show fragmentation or a small avulsion at the distal pole of the patella ( Fig 121.9 ), which must be differentiated from an acute sleeve fracture of the patella or a bipartite patella Treatment emphasizes rest, application of ice, stretching exercises, and oral anti-inflammatory agents Resolution occurs over a period of 12 to 18 months