Clinics is mild soft tissue swelling at

Clinics in diagnostic
imaging

Case Presentation

A 14 year old male
presented with anterior left knee pain of 2 weeks duration with no history of
trauma. The knee pain was aggravated by exercise and relieved  by rest. On physical examination, there was
focal tenderness at the left tibial tuberosity and the pain was reproducible on
forced extension of the knee. The rest of the knee examination did not reveal
any joint instability. A radiograph of the knee was performed (see fig 1). What does the image show and
what is the diagnosis? As his pain persisted, a MRI of the Knee was
subsequently performed (see fig 2). What do the images show?

Image interpretation

Knee X-ray: There is
bony irregularity with fragmentation at the tibial tubercle. A  small well corticated bony fragment is noted superior
to the tibial tuberosity (see arrow in Fig. 1). There is mild soft tissue
swelling at the expected patellar tendon insertion site. There is however, no significant joint effusion.

MRI Knee: There is a
small ossicle in the distal pre-insertional part of the left patellar tendon
which shows well-defined corticated margins and no identifiable marrow oedema
(see Fig. 2a). The adjacent left tibial tuberosity shows mild marrow oedema
just deep to the articulation with the ossicle (see Fig. 2b). The rest of the
patellar tendon shows normal thickness and signal characteristics.

Diagnosis

Osgood-Schlatter disease (OSD)

Clinical course

He was treated conservatively
with administration of a short course of oral analgesics along with rest and modification
of exercise. The symptoms subsequently resolved with no further functional
impairment or pain.

Discussion

Osgood-Schlatter disease (OSD) is a traction
osteochondritis involving the tibial tubercle, first described in 1903
separately within the same year by Dr Robert Osgood and Carl Schlatter 1,2.
It is characterized clinically by the presence of pain and swelling of the
tibial tuberosity in the adolescent patient 3.

It is widely accepted
as a traction apophysitis involving the tibial tubercle and the distal aspect
of the patellar tendon. There is chronic and repetitive injury to the distal
patellar tendon and avulsions of the cartilaginous attachment of the patellar
tendon to the secondary ossification centre of the tibial tubercle. Foci of
heterotopic ossification may occur when the avulsed
cartilage fragments ossify. 4,5

Incidence and epidemiology: Typically,
it occurs in the adolescent due to recurrent avulsion and microtrauma of the
developing tibial tuberosity. More commonly occur in males from ages 11 to 18
and earlier for females at ages 8 to 16, due to the earlier onset of the pubertal
growth spurt however, it may manifest bilaterally in 20-30% of the patients 5,
8. Higher incidences of OSD is observed in those who are active in sport
compared to those who are inactive, 21% vs 4.5%, respectively 7.

A review of 794
published cases in the literature revealed that 72% of all cases of OSD are
males 6. The male predominance has been attributed to the greater
participation in sports and faster skeletal growth in the male adolescent.

 

 

Clinical presentation: Patients with OSD usually
presents with pain over the anterior aspect of the knee and tenderness with
application of pressure on the tibial tubercle. 
Any activity requiring contraction of the quadriceps mechanism
aggravates the pain which improves by rest. There may be enlargement of the
tibial tuberosity, thickening of the patellar tendon or joint swelling. On
physical examination, tenderness is elicited on palpation or application of
pressure on the tibial tubercle and patellar tendon. As in our patient, pain is
reproducible by resisted active extension of the knee 9.

Investigations: The diagnosis of is
based on clinical examination, with additional radiographic investigations to
exclude fractures or bony tumours. 3

Radiological findings/modalities: Plain radiographs of the knee may demonstrate fragmentation,
increased density, irregularity or enlargement of the tibial tubercle (see fig
3 and 4).

On
MRI imaging, the normal patellar tendon should be homogeneously low signal on
T1, T2 and proton density weighted images. The normal thickness of the patellar
tendon increases proximally to distally, but should not exceed 7 mm in
thickness 11. The presence of either focal or
diffuse thickening and/or presence of intermediate T1W and T2W signal may
represent pathology 12.

Sagittal MR images in OSD
may reveal enlargement of the distal aspects of the patellar tendon, low signal
intensity foci of heterotopic ossification and irregularity or enlargement of
the tibial tuberosity. Distention of the deep infrapatellar bursa may be due to
the presence of fluid between the deep surface of the patellar tendon and
anterior cortex of the tibia. There may be increased signal on T2W images
demonstrating oedema at the tibial tuberosity and tibial epiphysis. 4, 5, 8
(see Fig. 5)

Ultrasound findings may
show a normal appearing mid portion of patellar tendon with the distal aspect
of the patellar tendon appearing thickened and hypoechoic. Sometimes, heterotopic
ossification may be visualized 4.

Treatment: Conservative
measures by local application of ice packs and oral administration of analgesia
comprise the mainstay of therapy. Modification of exercise is suggested with
avoidance of strenuous activities. Strengthening and stretching exercises may
help. Protective pads which are worn over the tibial tubercle may help avoid
direct trauma to the tibia tubercle, although cast immobilization is not
advised as wasting of the quadriceps muscle may occur. Surgical management may
be considered in patients where conservative measures have failed and after fusion
of the tibial growth plate 5, 13. Rarely, surgical management is required for
unresolved OSD. In cases where there are persistent symptoms after skeletal
maturity, surgical treatment may be advocated with good outcome and without long
term deleterious effects 14. One of the studies showed promising results for
hyperosmolar dextrose injection together with lidocaine over the apophysis and
patellar tendon origin with subsequent improvement of symptoms although more
research is needed before routine recommendation of this procedure can be
recommended 15. In general, OSD tends to be self-limiting with resolution of
symptoms in more than 90% of patients, and good overall prognosis with non-operative
treatment.

 

 

 

 

 

 

 

 

 

Singapore
Medical Council Category 3B CME Programme

Questions:

1. Regarding
Osgood-Schlatter disease

It is a chronic apophysitis of the tibial tubercleIt is a traction apophysitis involving the inferior pole of the
patellaIt is a fracture of the tibial tuberosityThere is rupture of the  
patellar tendon2.
In the imaging of the knee,

The patellar tendon decreases in thickness
from its proximal to distal extent.The patellar tendon thickness typically does
not exceed 7 mm in thickness.On MR Imaging, the normal patellar tendon
demonstrates heterogeneous signal intensity on T1, T2 and proton
density-weighted images.On MR imaging, the normal patellar tendon is
low signal intensity on T1, T2 and proton density-weighted images.

3. Findings of
Osgood-Schlatter disease on a plain radiograph include:

Thickening of the quadriceps tendonThickening of the patellar tendonFragmentation/Irregularity of the tibial tubercleOssicle within the patellar tendon4. Findings of
Osgood-Schlatter disease on MRI include:

Enlargement of the distal patellar tendonLow signal intensity ossification of the patellar tendonDistention of the infrapatellar bursaIncreased marrow signal at the patellar tendon insertion at the
tibial tuberosity 5.  The management of Osgood-Schlatter disease includes:

Corticosteroid injectionsSurgical management when conservative measures fail, after fusion of
the proximal tibial growth plateModification of physical activityWearing of a protective pad to prevent trauma to the tibial tubercle
 ABSTRACT:A 14 year old male
presented with left anterior knee pain which was aggravated by exercise and
relieved by rest. On clinical examination, there was tenderness at the tibial
tuberosity with reproducible
pain on resisted active extension of the knee. Plain radiographs showed
heterotopic ossification of the patellar tendon with irregularity and
fragmentation of the tibial tubercle. Clinical and radiological findings are consistent
with Osgood-Schlatter disease (OSD) which is a traction apophysitis of the
tibial tubercle, commonly occur in adolescent. The clinical presentation and
imaging features are discussed.