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- It is located in the second layer of the medial knee
- MPFL attaches from the medial patella to the area between the adductor tubercle and medial epicondyle
- Acts as a "check-rein," guiding the patella into the trochlear groove at 0–30°
- Provides 50% of restraining force from 0–30° flexion
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- More than one location is most common (34%), Patellar side only (31%), Femoral side only (14%)
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- Look for valgus and scars
- Have patient lie down, perform knee exam and special tests
- J-sign: When patient extends knee from flexed position, patella moves superolaterally in an inverted J
- Apprehension test
- Assess Patella mobility by Quadrants [< 2 quadrants]
- Beighton Score (> 6)
- Q angle measurement
- Angle between two lines:
- 1st line from ASIS to midpoint of patella
- 2nd line from midpoint of patella to tibial tubercle
- [Males 10–12°, females 15–18°]
- Assess Rotational Profile
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- Observe patient walking
- [-5° to 20°]
- Increased femoral anteversion → Intoeing gait
- Examination proper - 3 components: Femoral anteversion, tibial torsion, foot metatarsus adductus
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- Position patient prone, knee flexed to 90°
- Place one hand over GT; slowly internally rotate the hip (drop the foot outwards)
- Angle from vertical to palpation of GT at its MOST prominent point = anteversion angle [20–60°]
- Anteversion is about 40° at birth and decreases to 16° by age 16
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- Position patient prone with knee flexed to 90° [10–20°]
- Measure angle between transcondylar axis of proximal tibia and bimalleolar axis
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- Normally passes through 2nd web space
- Mild = through 3rd toe
- Moderate = 3rd/4th web space
- Severe = 4th/5th web space
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- When femur is highly anteverted, the body compensates by internally rotating the lower limb to maximize the gluteus medius length-tension relationship
- This increases the Q angle
- External tibial torsion - In this condition, the tibial tubercle shifts laterally, increasing the Q angle and TTTG distance
- *Note: Persistent femoral anteversion can lead to compensatory external tibial torsion
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- Bilateral double osteotomy is indicated only for severe torsional malalignment cases, as described in the literature
- The procedure involves ipsilateral outward femoral and inward tibial osteotomies
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- XR - AP, Lateral, and Skyline views to look for loose bodies (which can originate from the lateral femoral condyle)
- Consider MRI if there is suspicion of loose bodies, meniscal tears, or ACL injury
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- If no loose body → conservative treatment with physiotherapy for VMO strengthening is generally accepted, though controversial.
- If loose body → arthroscopic removal or fixation based on size (2cm threshold)
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- Controversial. Risk of recurrence is assessed using the validated Patellar instability severity score, published by Peter Balcarek in KSSTA in 2013 (based on 61 patients).
- Score evaluates: age <16, bilateral instability, trochlea dysplasia, patella height, TTTG, patellar tilt. Total score out of 7
- 4 or more points indicates 5× higher odds ratio than <4
- Patient and parent counseling is essential for informed decision-making
- Systematic review by Erickson et al. 2015 showed lower re-dislocation rates with surgery (24% vs 34%) but similar outcomes
PISS.pdf208.8KB
erickson-doe-operative-treatment-first-time-patellar-dislocations-lead-increased-stability-arhtroscopy-2015 (2).pdf536.7KB
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- Occurs either on the medial patellar facet or lateral femoral condyle
RECURRENT DISLOCATOR
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- CT scan - TTTG distance > 20mm
- MRI - Looking for MPFL, TRO ACL, TRO Meniscus
- XR long film - assess valgus
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- Many methods but I use the Caton-Deschamps Method because it is independent of knee flexion.
- Length of Articular surface of patella divided by Distance between inferior articular surface of patella to anterior articular surface of tibia
- Normal 0.6-1.3
- Insall-Salvati: Length of patellar tendon divided by length of patella [~1]
- Blackburne-Peel
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- Dejour Classification - can be assessed on lateral XR and MRI/CT axial
- SFCC
- Type A = Crossing sign (CT shows shallow trochlea < 145°)
- B = Crossing + Supratrochlear spur (CT shows flat trochlea)
- C = Crossing + double contour (CT shows medial hypoplasia convex trochlea)
- D = All 3 (CT shows a cliff from lateral trochlea)
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- Normally, the LFC and MFC coincide on lateral XR
- Crossing sign: Deepest point of the trochlear sulcus crosses the anterior border of the femoral condyles
- Supratrochlear spur: Prominence of the trochlea on the anterior aspect of the femoral cortex
- Double Contour: Hypoplastic medial facet
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- Wiberg Classification on skyline XR
- Type 1 = Symmetrical lateral and medial facets
- Type 2 = Lateral facet larger than medial facet
- Type 3 = Medial facet markedly smaller
- Type 4 = Absent medial facet
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- No consensus exists on the optimal treatment
- Treatment follows an à la carte approach based on patient-specific anatomical risk factors
- 5 main procedures
- 3 bony procedures: Tibial tuberosity transfer, trochleoplasty, and distal femoral osteotomy (DFO) for severe genu valgum
- 2 soft tissue procedures: MPFL reconstruction (acts as a checkrein) and lateral release
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- 1st line = Posterior cortex of femur
- 2nd line = Perpendicular line at transition of curve of posterior condyle
- 3rd line = Perpendicular line at posterior aspect of Blumensaat's line
- Patellar tunnel - multiple configurations
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- While controversial, evidence shows it is sufficient regardless of TTTG, patella alta, or trochlear dysplasia (all-comers) (Erickson et al. Cohort study of 90 patients)
Erickson MPFL.pdf341.0KB
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- Isolated lateral release remains controversial
- Recent meta-analysis by Tan et al. 2020 showed good outcomes but emphasized patient selection. Patients with > 5 dislocations or ligamentous laxity have high failure rates
- Current consensus recommends performing it only as part of a secondary procedure
tan2019.pdf231.3KB
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- Fulkerson - AM
- Macquet - anterior only
- Elmsie-Trillat - medialize only
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- Roux-Goldthwait technique = Transfer of lateral patella tendon to medial aspect to change force vector
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- It was an older procedure that produced poor outcomes
- The procedure involved removing the patella tendon with a small bone block of 2 x 2cm and reinserting it 1cm medially and distally
- The tendon is then sutured down, and the patient is immobilized in plaster for 4-6 weeks before starting flexion exercises
juliusson1984.pdf404.4KB
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