This case report describes a 21-year old female patient with a 10-year history of habitual left patellar dislocation. Examination found lateral subluxation of the patella in flexion and reduced range of motion. X-rays showed patella baja on the left side and lateral dislocation of the patella. The patient underwent a proximal and distal soft tissue realignment procedure involving lateral release, medial reinforcement, and partial medialization of the patellar tendon. Post-operatively, the patella was centrally located with improved range of motion and stability. Habitual patellar dislocation is rare in adults and can be treated with soft tissue realignment surgery to reinforce the medial structures and release tight

1. Case Presentation
Habitual Dislocation of Patella
Dr Sushil Sharma
First Year MS Orthopaedic Resident

2. An Interesting Case

3. Patient Particulars
• Name : Amrita Pun
• Age : 21
• Sex : F
• Address : Salyan-3,Yang
• Date of Admission : 2014 July 28

4. History
• Chief Complaints
– Difficulty in walking
– Giving way of left knee for past 10 years
• History of Present Illness
– Fall injury 10 years back, sustained injury to left
knee following which she had pain in left knee &
difficulty in walking. Giving way of left knee.

5. Clinical Examination
• Gait : Normal
• Inspection
– No swelling, discoloration,
scar marks
– Wasting of left quadriceps
muscle
– Position of patella: Centrally
placed (In extension) &
laterally dislocated in flexion
– Size of patella : Left appears
small than right
– Attitude of leg: B/L varus

6. Clinical Examination
• Palpation:
– No rise in superficial temperature
– No superficial & joint line tenderness
– No tenderness over patella
– Patellar movement restricted medially
– No patello femoral tenderness and crepitus

7. Clinical Examination
• Movement
– Range of movement
• Flexion
– Left Knee : 0-135
– Right Knee : 0-135
• Loss of Extension : Not present
• Internal rotation : 10 degree
• External rotation : 10 degree

8. Clinical Examination
• Measurement
LEFT RIGHT
Q angle 25 degree 20 degree
Size of Patella 2.5 X3.5 cm 3 X 4 cm
Thigh Foot Angle 30 30

9. Clinical Examination - Special Tests
– Apprehension test :
Negative
– Patellar grinding test:
Negative
– Patellar tracking : Positive J
Sign (Lateral subluxation of
patella in flexion)
– Patellar glide test:
• 1 quadrant medially
• 3 quadrant laterally
– Patellar tilt test : Negative

10. Investigation
• Pre-operative investigation:
– CBC (Within normal limit)
– Serum Na, Serum K, Serum Urea, Serum
Creatinine (Within normal limit)
– Serology : Non reactive
– RBS : Normal
– Urine RME : Normal

11. X-Ray B/L Knee AP
• Both leg in varus
position

12. X-Ray B/L Knee Lateral
• Blumensaat line : Lower
pole of patella on line
with intercondylar
notch.
• Insall-Salvati Ratio (N : 1)
• Right: 1
• Left: 0.8 (patella baja)

13. X-ray B/L Knee Skyline
• Left patella dislocated
laterally out of the
trochlear notch
• Left trochlear sulcus
shallower than right.

14. SPECIAL AXIAL VIEWS OF PATELLA
HUGHSTON MERCHANT LAURIN
•Patellar Index : 14
(N: M – 15, F – 17)
•Sulcus angle : 120
(N : 118)
•Patellofemoral Index: 2.6
(N:1.6)
•Sulcus angle : 145
(N:138)

15. Management
• Surgical realignment is the treatment of choice.
• Principle :
– Medialization of Patella
– Maintenance of proximal & distal alignment
• Surgery performed
– Insall (Suprapatellar realignment)
– Roux Goldthwait operation (Infrapatellar soft-tissue
realignment)

16. Management - Operative
• Proximal realignment
• Release of tight lateral
patellar retinaculum & vastus
lateralis completely
• Plication of medial capsule &
patellar retinaculum to
strengthen the lax medial
structures.
• Vastus medialis obliqus (VMO)
was advanced & sutured to
lateral border of patella &
quadriceps, after locating
patella in trochlear notch in
70 degree flexion.
LATERAL
MEDIAL

17. Management - Operative
Distal realignment
• Lateral third of patellar
ligament was released
from tibial tubersoity
and passed underneath
medial portion of
patellar tendon &
sutured upwards &
medially to pes
anserinus tendon
LATERAL
MEDIAL

18. Post Operative
• Above knee posterior slab with knee in 5 degree
of flexion was given for first 5 days
• A long-leg hinged knee brace was applied later
with the knee in 20° of flexion
• Partial weight bearing with crutches for four
weeks was advised, during which the patient was
encouraged to do static quadriceps strengthening
exercises
• Knee mobilization and full weight bearing was
started after four weeks.

19. Post Operative Results
• Position of patella : Centrally placed
& no lateral dislocation on flexion.
• Q angle : 20
• Range of movement : 0 - 135
• Extensor Lag : Not Present

20. Discussion

21. Anatomy

22. Introduction
• Habitual dislocation of the patella is a rare condition
among adults, where the patella dislocates during
flexion and relocates during extension without pain
and swelling unlike the recurrent patellar dislocation.
• Predisposing factors
– ligamentous laxity (in women, connective tissue disorder)
– contracture of the lateral patellar soft tissues
– patella alta
– quadriceps contractures
– hypoplasia of the lateral femoral condyle
– genu valgum

23. Patho Anatomy
• Q angle
– Male (8-10)
– Female (15±5)
• Lateral pull : Vastus
lateralis, Iliotibial band
• Medial pull : Vastus
medialis obliqus (VMO)
• Increased Q angle :
Patellar dislocation

24. Patho Anatomy
• Genu valgum
• Increased femoral
anteversion
• External tibial torsion
• Internal femoral torsion
• Tight lateral retinaculum

25. Types of Patellar Dislocation
Type Dislocation Pain Swelling
Acute Dislocation In response to trauma Present Present
Recurrent Isolated episode in response to trauma Present Present
Habitual Everytime when knee is flexed Absent Absent
Congenital Since birth Absent Absent

26. Pathology
First episode of traumatic dislocation
Tear of capsule on medial side of patella
If improper healing
Persistent laxity
Recurrent dislocation
Damage to contiguous surface of patella & fem.
Condyles
Flattening & then further dislocation

27. Clinical Features
• Symptoms
– Feeling of insecurity in knee (Giving way of knee)
• Signs
– Patellofemoral crepitus
– Postive J sign
– Increased Q angle

28. Management
• Proximal realignment
– Lateral release
– Reconstruction of vastus medialis obliquus
• Distal realignment
– partial medialization of the ligamentum patella
– Medialization of tibial tuberosity.
• always lateral release is combined with medial
augmentation

29. Typical Procedure

30. Acknowledgement
• Prof Dr S.K. Biswas (HOD, Dept of Orthopaedics)
• Asst Prof Dr Niraj Ranjeet
• Dr Krishna Sapkota
• Dr Pratyunta Raj Onta
• Dr Alind Kishore
• Dr Pabin Thapa
• Dr Upendra Jung Thapa
• Dr Manoj Prasad Gupta
• Dr Prakash Dware
• Department of Anesthesiology
• Operation Theatre Staffs

31. References
• Campbell’s Operative Orthopaedics, 12th
Edition
• Apley’s System of Orthopaedics & Fractures,
9th Edition
• Post Graduate Companion in Orthopaedics
• Handbook of Fractures, 4th Edition

32. Thank You
Happy Dashain 2071