and Iain McNamara1
(1)
Trauma & Orthopaedics, Norfolk & Norwich University Hospital, Norwich, United Kingdom
A 20-year-old female university student presented complaining of right knee instability. She had had two patellar dislocations in the last year which were spontaneous in onset on a background of knee instability for over 10 years. She was nonsporting.
Past Medical History
There was no significant past medical history.
Family History
Her younger sister also had an unstable kneecap, but no one else in the family.
On Examination
Her BMI was normal and a normal rotational profile to the lower limb. Her Beighton score was 5/9. She had patellar apprehension +++ with an ML glide of a minimum of +++ (restricted by apprehension), slight J-shaped tracking, full range of knee movements, very poor balance on each leg, and difficulty with a single-leg squat.
Kujala score 60
Norwich Patellar Instability score 22 %
X-rays
Question 1
From the plain image:
- (a)
How is the patellar height measured and what is it here?
- (b)
How would you classify the trochlea here?
Question 2
How would you now manage this person and why?
Follow-Up
She returned to the clinic 6 weeks later with the results of her MRI scan.
Question 3
What does the MRI show?
The scan was reported measuring a TTTG of 20 mm and a patellar tilt angle of 34°.
Question 4
How would you stabilise this patella operatively?
Operation
She underwent a patellar stabilisation. At operation a fluoroscopic image was taken:
Question 5
What does the intraoperative image show?
Question 6
What post-operative instructions would you write in the operation note and why?
Question 7
What does the post-operative X-ray show?
Answers
Question 1a
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