Sinding-Larsen-Johansson SyndromeSinding-Larsen-Johansson syndrome is a stress injury to the growing patella (kneecap) at its inferior pole, or bottom, where the patellar tendon attaches. This area of the growing patella is relatively weak and can be injured by repetitive stress during vigorous exercise and activity.
It is usually a temporary condition and is uncommon after age 16 or when growth is complete. It is the children’s equivalent of patellar tendinitis, also called jumper’s knee.
What Is Sinding-Larsen-Johansson Syndrome?
Sinding-Larsen-Johansson syndrome affects the lower part of the growing patella where the patellar tendon begins. This area experiences traction from the powerful quadriceps (thigh) muscle and during deep bending of the knee.
Stress to the developing bone may cause pain and can involve inflammation of the cartilage of the growing patella, injury to tendon cells from repeated stress, or pulling away of the lining of the patellar bone.
Causes and Risk Factors
Sinding-Larsen-Johansson syndrome results from stress, either from a single sudden incident or repeated activity, that overstresses the developing lower patella.
Risk factors include:
- Overzealous conditioning routines involving running, jumping, or jogging
- Being overweight
- Boys between ages 10 and 15
- Rapid skeletal growth
- Poor physical conditioning, including strength and flexibility
Symptoms
Common signs and symptoms include:
- A slightly swollen, warm, and tender bump below the kneecap
- Pain with activity, especially when straightening the leg against resistance
- Pain with stair climbing, jumping, deep knee bends, or weightlifting
- Pain following an extended period of vigorous exercise
- In more severe cases, pain during less vigorous activity
Treatment
Initial treatment consists of medications and ice to relieve pain, stretching and strengthening exercises, and activity modification.
Activities such as kneeling, jumping, squatting, stair climbing, and running on the affected knee should be avoided. Exercises may be performed at home for acute cases. Chronic cases often require referral to a physical therapist or athletic trainer for further evaluation or treatment.
If symptoms are severe, the affected leg may uncommonly be temporarily immobilized. A patellar band, worn between the kneecap and tibial tubercle over the patellar tendon, may help relieve symptoms.
Surgery is rarely needed in a growing patient if conservative treatment fails. Surgery may also be necessary after skeletal maturity if an ossicle, or bony fragment, becomes painful.
Recovery and Outcomes
Mild cases may resolve with a slight reduction in activity, stretching, and regular cold therapy. Moderate to severe cases may require significantly reduced activity and even temporary immobilization.
Potential complications include:
- Continuation of the condition into adulthood with symptomatic bone fragments below the affected knee
- Persistent prominence or bump below the kneecap
When to See Dr. Chudik
If you are concerned about Sinding-Larsen-Johansson syndrome or your symptoms worsen, schedule an evaluation with Dr. Chudik.
Call 630-324-0402, request an appointment online, or email contactus@chudikmd.com.