History and exam

Key diagnostic factors

common

pain at the tibial tubercle

Worsened by forceful extension of the knee, such as during athletic participation and play.

Relieved by rest, ice, and anti-inflammatory medications.

localized tenderness

Palpation directly over the tibial tubercle elicits pain and helps distinguish this disorder from other causes of knee pain.

Other diagnostic factors

common

activity limitation

Young athletes often present complaining of inability to maintain the desired or expected level of athletic performance because of pain.

localized swelling

Typically easy to distinguish from a knee effusion, but may be confused with swelling that occurs with prepatellar bursitis.

Aggravated by activity and relieved by rest.

localized warmth

Typically localized directly over the tubercle, and not over the whole knee, thus distinguishing it from warmth that may occur with a septic joint.

prominence of the tibial tubercle

Commonly occurs later in the disease, as the apophysis matures and ossifies. May or may not be painful to palpation.

pain at the tubercle with resisted knee extension

Pain at the tibial tubercle is exacerbated by resisted knee extension, especially at the terminal 30°, where shear forces on the tibial tubercle are greatest.

Risk factors

strong

adolescent males

Occurs in adolescence.[1]

Males are affected more often than females.

athletic participation

Sports with highest risk for developing this disease are those that demand repeated forceful knee extension,​​ usually involving running, jumping, squatting and deep knee bending, such as track, football, rugby, basketball, baseball, and soccer.[1][6]

history OSD in the contralateral knee

The condition is frequently bilateral (20% to 30%).[1][4]

weak

high position of the patella (patella alta)

A prospective study compared radiographs of knees of patients with OSD and unaffected adolescent controls. Fifty-eight percent of OSD patients had high patellas, compared with 17% of the control group.[7] The authors of the study hypothesized that increase in patella height requires greater force of quadriceps contraction to achieve full extension, which in turn results in greater force being transmitted distally to the insertion of the patellar tendon at the tibial tubercle.

Another radiographic study found that a group of older OSD patients (20-year-old males) also had more high patellae than the group of normal controls. In addition, the patellae in the OSD group were more elongated, perhaps due to the effect of long-standing increased tension.[8]

An earlier retrospective review also recorded a high prevalence of patella alta (68% of knees) in patients with OSD.[9]

more proximal/broader tibial attachment of the patella tendon

A study using MRI to compare 20 patients with OSD with 15 normal controls found a more proximal and broader insertion of the patellar tendon in patients with OSD.[10] The significance of this finding is unknown, but it is hypothesized that the resultant shorter length of the patellar tendon imparts greater strain on the tibial tubercle. No further information exists on this topic.

increased external tibial torsion

Several studies have shown that patients with OSD have a significantly greater tibial torsion angle compared with those without OSD.[11][12]

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