| What We Treat
Patella Sleeve Fracture
A fracture unique to children, easily missed on X-ray, where delayed diagnosis has real consequences.
Overview
What It Is
A sleeve fracture is an avulsion in which a sleeve of cartilage pulls off the kneecap, taking only a small fragment of bone with it. It occurs almost exclusively in children between eight and twelve, typically during a jump or forceful straightening. Because most of the avulsed tissue is cartilage, it barely shows on X-ray, and it is frequently missed.
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A Cartilage Sleeve Avulsion
A sleeve of cartilage pulls off the kneecap during a jump or forceful straightening, almost exclusively between eight and twelve.
Symptoms
How It Tends to Feel
These are the features that point towards this diagnosis rather than another:
Inability to Straighten the Knee
Loss of active extension is the key finding.
Sudden Onset
During a jump, a fall or a forceful kick.
Marked Swelling
A large effusion developing rapidly.
High-Riding Kneecap
The patella sitting higher than on the other side.
Palpable Gap
Sometimes felt below or above the kneecap.
Severe Pain on Weight Bearing
Usually preventing walking.
Causes & Risk Factors
What Drives It
The usual contributors, in rough order of how often they turn out to matter:
Forceful Quadriceps Contraction
Against a bending knee, during jumping or landing.
Age Eight to Twelve
The period when the growing cartilage is the weakest link.
Sport
Football, gymnastics and trampolining feature prominently.
Direct Trauma
Less commonly, a direct blow.
How We Can Help You
Treatment & Management
Treatment is built around what the assessment finds, but generally follows this shape:
When to Seek Help
Red Flags — Don’t Ignore These
Most presentations are straightforward. These features are the exceptions, and warrant prompt assessment:
⚠ Seek Medical Advice If You Notice
- Any child unable to actively straighten the knee after an injury — assess urgently
- A normal X-ray does not exclude this injury
- Marked swelling with inability to weight bear
- Numbness, coldness or a pale foot
If any of these apply, contact your GP or seek urgent medical care rather than waiting for a physiotherapy appointment.
Common Questions
Frequently Asked Questions
The X-ray was normal, so is it just a sprain?
Not necessarily. The avulsed sleeve is mostly cartilage and does not show. A child who cannot actively straighten the knee needs further assessment regardless of the X-ray.
Does it need surgery?
Almost always. The extensor mechanism has been disrupted and needs restoring for the knee to function.
Will they get back to sport?
Yes, in the great majority, with appropriate fixation and a full rehabilitation programme.
Not Sure If This Is What You Have?
An assessment will tell you what is actually going on and what to do about it. I see everyone myself, and you will leave with a plan rather than a leaflet.
Book Your Initial AssessmentThis page is for general information only and isn’t a substitute for individual medical advice. If you’re experiencing any of the warning signs above, contact your GP or seek emergency medical care as appropriate.