InfraPatellar Bursa Injection

Acute or chronic bursitis

Causes and findings:
• Overuse -long distance running or prolonged kneeling
• Trauma - direct blow or fall
• Pain anterior knee below patella
• Painful: resisted extension of knee passive flexion of knee
• Tenderness at mid-point of patella tendon

Equipment:
Syringe - 2ml
Needle - 23G 1.25 inches (30mm) blue
Kenalog 40 - 20 mg
Lidocaine - 1.5 ml 2%
Total volume - 2 ml

Anatomy:
There are two infrapatellar bursae - one lies superficial and one deep to the tendon. In a small study it was found that the infrapatellar bursa consistently lay posterior to the distal third of the tendon and was slightly wider; a fat pad apron extends from the retropatellar fat pad to partially compartmentalize the bursa. The technique described is for the deep bursa, which is more commonly affected.

Technique:
• Patient sits with leg extended and knee supported
• Identify and mark tender area at mid-point of tendon
• Insert needle horizontally at the lateral edge of the patellar tendon just proximal to the tibial tubercle. Ensure that the needle does not enter the tendon
• Deposit solution as bolus

Aftercare:
The patient must avoid all overuse of the knee for at least 1 week. When the cause is occupational, such as in carpet layers, a pad with a hole in it to relieve pressure on the bursa should be used. Graded stretching and strengthening exercises are then begun.

Comments:
It would be tempting to believe that pain found at mid-point of the patella tendon is caused by tendinitis, but in the experience of the authors this is virtually unknown. Infrapatellar tendinitis is found consistently at the proximal teno-osseous junction on the patella, or rarely at insertion into the tibial tubercle. Pain here in an adolescent boy should be considered to be Osgood Schlatter's disease and should not be injected. A similar approach can be used for the superficial bursa and for the prepatellar bursa.