Osgood-Schlatter Disease 

Background

Osgood-Schlatter (OS) disease is more appropriately described as a disorder or a condition. Osgood, in the English literature, and Schlatter, in the German literature, independently described this condition in 1903. The etiology and treatment of OS condition have been disputed since its original description.

OS condition is a traction phenomenon resulting from repetitive quadriceps contraction through the patellar tendon at its insertion upon the skeletally immature tibial tubercle. This occurs in preadolescence during a time when the tibial tubercle is susceptible to strain. OS condition should be distinguished from overuse of the patella-patellar tendon junction, which is referred to as Sinding-Larsen-Johansson syndrome (the adolescent equivalent of jumper's knee).^{[1, 2]}

The onset of Osgood-Schlatter disease is usually gradual, with patients commonly complaining of pain in the tibial tubercle and/or patellar tendon region after repetitive activities. Typically, running or jumping activities that significantly stress the patellar tendon insertion upon the tibial tubercle aggravate the patient's symptoms. A sudden onset of pain with no antecedent symptoms in the region of the tibial tubercle should alert the clinician to assess for a possible tibial tubercle avulsion rather than OS condition.

Osgood-Schlatter disease is the most frequent cause of knee pain in children aged 10-15 years. This condition can cause loss of time from athletics; however, it is rarely a cause of permanent impairment or disability.

The natural history of this condition is self-limiting. In the Krause study, 90% of patients treated with conservative care were relieved of all of their symptoms approximately 1 year after onset of symptoms.^[3] After skeletal maturity, patients may continue to have problems kneeling or may have tenderness over an unfused tibial tubercle ossicle or a bursa that may require resection. Minimal association seems to exist between residual anterior knee pain after OS condition and patellar stability, as was noted in the Krause study. The authors also noted no cases of recurvatum from premature closure of the proximal tibial physis.

Frequency

The true incidence of Osgood-Schlatter disease is unknown. Kujala reviewed 412 athletes who presented to a sports clinic with 586 complaints.^[4] Sixty-eight patients, with an average age of 13.1 years, were diagnosed with OS condition. These patients did not participate in their sports activities for approximately 3 months because of the condition. Most individuals resumed full activity by 7 months.

Kujala also questioned 389 students and found that 12.9% claimed to have had OS condition. In this group, patients who had not participated in sports had a lower incidence of the condition (4.9%) than those who had played sports.

The etiology of Osgood-Schlatter disease is controversial. Several causes have been hypothesized. The most likely cause is that the apophysis is subject to traction during the adolescent years, which can result in microfractures. The tibial tubercle apophysis appears in children aged 7-9 years. Usually, an apophysis develops proximally toward the epiphysis as the epiphysis grows distally toward the apophysis. Repeated traction from the patellar tendon can cause microfractures in the apophysis, as demonstrated by Lazerte and Rapp when they examined resected operative specimens from patients with OS condition.^[5] These specimens showed avulsion fractures of portions of the distal tibial tubercle.

Ehrenborg histologically examined bone excised from the tibial tubercle and found that viable cancellous bone exists without evidence of necrosis or inflammation.^{[6, 7]} Woolfrey believed this was due to changes in the lower end of the patellar tendon and secondary new bone formation.^[8] Ogden showed that the tibial apophysis changes from fibrocartilage to hyaline cartilage, making it susceptible to injury.^[9] Rosenberg et al reviewed 16 nuclear scans, 34 CT scans, and 27 MRIs in patients with this diagnosis.^[10] They found that 100% percent of these patients had a normal tendon size, decreased attenuation, and an increased signal. Thirty-two percent of the patients had an ossicle. Rosenberg believed the findings were most consistent with patellar tendinitis.

The individual's history and physical examination are usually sufficient to make a diagnosis of Osgood-Schlatter disease.

OS condition is the most frequent cause of knee pain in children aged 10-15 years. Patients present with a history of pain inferior to the patella at the insertion of the patellar tendon. Typically, individuals report a sport or other activity that aggravates the pain, which generally is improved with rest and worsened with activity. While any activity may be involved, sports involving jumping or running are a common cause.

Physical findings are limited to the area of the tibial tubercle and patellar tendon. Generally, there is a prominence and soft-tissue swelling over the tibial tubercle. Tenderness of the patellar tendon may be present. The remainder of the knee examination usually is normal. Attempted flexion against resistance may produce pain. Patients may resist knee flexion because of inflammation and pain from pull on the patellar tendon. Tight hamstrings and/or quadriceps may also be noted when compared with the uninvolved side.

Surgery to treat Osgood-Schlatter disease is rarely indicated. Occasionally, adults have a large ossicle and an overlying bursa, which may cause pain with kneeling. If so, treatment consists of excision of the bursa, ossicle, and any prominence.^[11] Surgical treatment is rarely, if ever, indicated in children. See Treatment.

Ossification of the tibial tubercle normally begins in children aged 7-9 years. Ossification of the tubercle begins distally and advances toward the extension of the physis that is ossifying distally. The patellar tendon attaches into the unossified distal portion. Strong forces exerted on the patellar tendon during the adolescent years can produce microfracture of the tibial tubercle at its insertion into the tibial diaphysis.

The real question is whether or not surgery is ever indicated in the growing child, as Osgood-Schlatter disease is self-limiting. Trail reviewed 2 groups of symptomatic patients with this condition with 4-5 years of follow-up.^[12] One group was treated surgically with tibial sequestrectomy, and the other was managed conservatively. Surgery was found to offer no significant benefit over conservative care. In addition, a significant complication rate was identified with tibial sequestrectomy.