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MPFL arises from medial surface upper two thirds of patella above equator and inserts into a groove between adductor tubercle and medial epicondyle
2 perpendicular lines drawn to line 1. Line 2 is medial condyle Line 3 is blumensaat line.
Dynamic medial patellofemoral ligament reconstruction in recurrent patellar instability
SRI SIDDHARTHA MEDICAL COLLEGE,TUMKUR
DEPARTMENT OF ORTHOPAEDICS
DYNAMIC MEDIAL PATELLOFEMORAL LIGAMENT RECONSTRUCTION IN
RECURRENT PATELLAR INSTABILITY:
A surgical technique
Prof. Dr. J.K Reddy
Dept. of Orthopaedics
Dr. Jaipalsinh Mahida
Jr. Resident M.S Ortho
Dept. of Orthopaedics
Recurrent patellar instability is common after a primary episode of traumatic
There is damage to the MPFL in almost all cases of traumatic patellofemoral
Dislocation is a result of anatomical abnormalities and/or insufficient soft tissue
Medial patellofemoral ligament (MPFL) is the main soft tissue restraint to
lateral patellar translation.
Non-surgical approaches have been advocated to treat acute patellar dislocation ,
while many operative procedures proximal realignment, distal realignment,
combined realignment, lateral retinacular release and MPFL reconstruction are
designed to treat chronic / recurrent patellar dislocations.
Graft anchorage, viability and anisometry of reconstruct play an
important role in outcomes of the procedure.
MPFL reconstruction has been recommended in adults over the past
decade after recurrent patellar instability.
In present study MPFL reconstruction using hamstring graft in a
dynamic pattern performed successfully in four patients.
Kujala score and Crosby and Insall outcome rating scale used to
evaluate outcome with follow up upto 24 months.
Static stabilizers: Are primary stabilizers of patella
1. shape of patella,
2. femoral sulcus,
3. patellar tendon of appropriate length, and
4. normally tensioned medial capsule reinforced by
a. Medial patellofemoral ligament and
b. patellotibial ligaments.
vastus medialis obliquus stabilizes the patella
against lateral pull of vastus lateralis.
Stability and normal tracking of the patella with knee flexion requires
a complex coordination of static and dynamic stabilizers.
From 0° to 30° of the knee flexion, medial patellofemoral ligament
and other soft tissue are primary restraints to lateral patellofemoral
With the greater knee flexion, the bony confines of the lateral femoral
condoyle and trochlear groove captures the patella and patellar
H. dejour classification
These underlying pathologies predispose to an acute over load of soft tissue stabilizers
and rupture of MPFL with patellar dislocation following minimal trauma.
Primary instability factors
I. Trochlear dysplasia
II. Patella alta
III. Patella tilt
IV.↑ TT-TG distance(‘q’ angle quantification by CT scan)
Secondary instability factors
I. Excessive external femoral rotation / Excessive femoral ante version
II. Excessive external tibial rotation
III. Genu valgum
We evaluate the following features:-
1. Integrity of medial patello femoral ligament
2. Height of patella on physical and radiographic
3. Length of patellar tendon
4. Position of patella in relationship to trochlea
b. standing alignment
c. ‘Q’ angle:
- for males : mean ‘Q’ angle is 10͔°
- for females : mean ’Q’ angle is 15°±5°
- ↑’q’ angle leads to relative lateral shift of patella
↑’Q’ angle results from
- ↑femoral external rotation
- ↑external rotation
- genu valgum
- tibia vara
d. J sign:
Observe the movement of the patella during active knee extension, lateral subluxation of the
patella as the knee approaches full extension is indicative of j sign positive.
Positive j sign indicates Increase lateral force or Increase ‘Q’angle.
e. Apprehension test : Patella pushed laterally in 200 - 300 of flexion
patellar translation is assessed by passively moving
patella medially and laterally with knee at 0° and 30°
of flexion, the amount of translation is quantified in
quadrants. Normal glide is one but more than two
quadrants indicates laxity.
g. Patellar tilt:
it is done with knee in full extension normally patella
can be tilted so that the lateral edge is well anterior
to the medial edge.
Inability to do this indicates lateral retinacular
h. rotational malalignment:
Measured by the relationship of the transmalleolar axis to the Coronal axis of the proximal
tibia, is typically neutral
tibial torsion also may be assessed through measurement of the thigh-foot angle, average
values are 5°internal
It leads to Increase ’Q’ angle and Increase TT-TG distance
i. excessive femoral ante version:
measured by hip rotations with the patient in prone position with hips
extended and knees at 90°of flexion
Normal range of hip rotations are about 45°. With ↑ femoral antevertion range
of internal rotation increases and range of External Rotation reduced.
It leads to Increase ’Q’ angle and Increase TT-TG distance
1. long standing weight bearing hip-to-ankle,
helps in assessing the angular deformity
of knee i.e. genu varum and genu
2. Lateral view with 30° of knee flexion:
normal value: 1.0 to 1.2
↑value indicates: patella alta: When
patella alta is present, the patella
becomes engaged with greater degrees
of knee flexion, where the patella is not
captured and it is at increased risk for
3. Lateral view with 30° of knee flexion:
For trochlear dysplasia:
Crossing sign: When anterior cortical outline of condyle intersects
trochlear outline, indicates dysplastic sulcus.
Double contour(Trochlear bump) : When trochlear line extends anterior to
4. Merchants view: tangential axial view of patellofemoral joint obtained with knee in 45° of
a. Sulcus angle: normal angle : 140°, if > 140° : trochlear dysplasia
b. Congruence Angle: normal : -8° to +14°, if >14° indicates lateral subluxation.
c. Lateral Patello Femoral Angle(Laurin Angle): normal: angle opens laterally, abnormal:
angle opens medially or lines become parallel.
5. CT scan evaluation:
Helps in assessing the bony anatomy and architecture of patellofemoral joint at different
angles of knee flexion.
The protocol includes mid-axial images obtained from 0°to60° of flexion in 10° of
increments. Is quantification of ‘Q’ angle.
a. TT-TG distance : normal measures are 2to 9 mm , borderline measures are 10to 19 mm,
pathological > 20°
b. Sulcus angle
c. Congruence angle
d. Trochlear depth
MANAGEMENT OF PATELLO FEMORAL
Types of patellar dislocations
a. Acute patellar dislocations:
Results from high energy transfer, where anatomy of joint is normal.
Results from internal rotation of femur on a fixed externally rotated tibia.
Major sequelae of acute patellar dislocation is tear of medial patellofemoral
most acute dislocations are treated non-operatively unless associated with an
When surgery is needed MPFL is repaired / reconstructed
b. Chronic / recurrent patellar dislocations:
condition where patellar dislocation had occurred at least twice, or where
patellar instability following initial dislocation had persisted for more than
A large number of procedures have been described to treat recurrent patellar
dislocations. No single surgery is universally successful in correcting the
chronic patellar instability.
We need to customize surgery based on the knee problem. Our approach is
to identify the underlying problem that cause the patellofemoral instability
and systemically correct them.
The surgical procedures are classified into:
a. Proximal Realignment Of Extensor Mechanism:
i. Lateral retinacular release
ii. Medial plication/ reefing
iii. Vastus Medialis Obliquus advancement
iv. Medial PatelloFemoral Ligament reconstruction
b. Distal Realignment Of Extensor Mechanism:
i. Medial or antero medial displacement of tibial tuberosity
MEDIAL PATELLO FEMORAL LIGAMENT
The procedures like medial plication, vastus medialis obliquus advancement,
and lateral retinacular release are non anatomic procedures.
They don’t address the principle of pathology in recurrent patellar dislocation.
MPFL is the primary soft tissue passive restraint to pathologic lateral patellar
dislocation, and MPFL is torn when patella dislocates,
hence reconstruction of MPFL is done in an attempt to restore its function.
Anatomy of medial patellofemoral ligament
skeletally mature patient,
excessive lateral laxity normal trochlea,
‘Q’ angle is normal,
TT-TG distance is < 20mm,
low grade trochlear dysplasia.
Contraindications: skeletally immature patients.
Scottle radiographic landmark:
for femoral tunnel placement on MPFL reconstruction.
knee joint is immobilized in extension with a simple knee brace for 3 days
Range-of-motion exercises and gait with weight bearing on two crutches are
started and gradually progressed.
Weight bearing is allowed as tolerated immediately after surgery.
Walking with full weight bearing usually is possible 2 or 3 weeks after
Extension during walking is maintained with a knee brace for 6 weeks.
Achieving at least 90 degrees knee flexion by the end of postoperative week 3
Jogging is allowed after 3 months, and participation in the original sporting
activity is allowed 6 months after surgery, depending on the patient.
based on the fixation techniques MPFL reconstruction procedures can be broadly classified into:
on either side graft is fixed rigidly at isometric points of parent MPFL with staples or
interference screws or anchors in bony tunnels
graft is secured to soft tissue at isometric points either on one or both sides with sutures.
Advantage of dynamic reconstructs over static
greater chances of accommodation in length all through the range of motion of knee thus
bringing down the peak pressure on patellofemoral joint during flexion.
The drawbacks of dynamic reconstruction:
weak anchorage leading to chances of failure and other complications of their own
depending on the procedure.
In present study they performed MPFL reconstruction procedure in four
consecutive patients with chronic patellar instability following trauma.
MPFL reconstruction was done with hamstring tendons detached distally and
secured to patellar periosteum after being passed through a bony tunnel in the
patella without an implant and using the medial collateral ligament as a pulley.
In all 4 knees, the MPFL reconstruction was isolated and was not associated with
any other realignment procedures.
A diagnostic arthroscopy was performed in all patients before starting reconstruction.
The ipsilateral gracilis and semitendinosus tendon is freed from its attachment distally
Care must be taken not to detach the tendon from its muscle and not to strip the
periosteum of the proximal tibial tubercle.
The distal ends of tendons are to be reefed for control to redirect the tendons.
The coupled tendon diameter is to be measured with a graft sizer.
Medial collateral ligament pulley:
In 30°-45° of knee flexion, a 2-3 cm longitudinal skin incision was made in the area of the
medial epicondyle and the adductor tubercle.
The proximal attachment of the medial collateral ligament (MCL) was identified and its
posterior one-third of the superficial layer was elevated without disturbing its attachment
distally or proximally.
The free ends of both the tendons were passed subcutaneously beneath the fascia but
superficial to the joint capsule and then redirected from underneath this MCL sling gaining a
pulley effect [Figure 6(a)].
Fixation of graft to patella:
2 cm anterior skin incision was made over the central part of the medial border of the patella.
A small periosteal flap was cut to expose the medial border of the patella.
A guide wire was passed through the patella directing superolaterally under fluoroscopic
Approximate reamer size of graft diameter was passed over the guidewire to drill a tunnel
through the thickness of the patella.
The two free ends were passed subcutaneously beneath the fascia and into the patellar tunnel
medio-laterally with the patella reduced into the trochlea at 30° of knee flexion.
The appropriate tension in graft was gained in this position; the grafts were then sutured to the
fascia and periosteum over the patella [Figure 6(b)].
Before completing the procedure, the patellar tracking and stability was judged clinically and
arthroscopically through the range of motion of the knee.
knee brace locked in extension and weight bearing as tolerated
with crutches until pain and swelling had resolved. Use of the
brace was continued until the quadriceps strength returned to
Grade 4 (usually first 2 weeks postoperatively).
From 2nd - 5th week, early range of motion by use of physical
therapy and continuous passive motion was prescribed. During this
period full weight bearing with a hinged brace
locked between 0° and 90° was advised. After 6 weeks, free
activity was allowed without brace. Controlled sports activities
after 3 months and contact sports after 6 months were allowed.
In this series, gracialis and semitendinosis are used in a dynamic
fashion. By preserving the proximal attachments other major issues
such as viability, anisomery and optimal tension in various positions
through the range of motion can be achieved which finally judge the
Deie et al in his series used single hamstring graft without disturbing
its distal attachment for reconstruction by passing it through posterior
one-third of superficial part of MCL at its proximal attachment,
patellar attachment was secured by fixing the graft into the tunnel at
level of superiomedial pole of the patella with a biotenodesis screw.
Fink et alzl used quadriceps tendon after stripping its
proximal attachment at desirable length, the graft is then
fixed on femoral isometric point with an interference screw
after dissecting the tendon distally over the patella keeping it
attached to the patella and rotating it 90° medially
underneath the medial prepatellar tissue.
Panagopoulos et al in his series used similar technique used
by Deie et al. but used medial intermuscular septum at the
adductor magnus insertion at pulley on the femoral side
instead of MCL.
Rehabilitation protocol was designed keeping in mind tendon to bone
The initial graft to fascia suturing heals in 2-3 weeks hence knee
range of motion exercises are started.
The bone to tendon incorporation starts at 2 weeks, takes
reasonable good loads at 12 weeks and is completed by 26
In present cases, sports activities were allowed at 3 months and
activities resembling contact sports causing greater loads on
patellofemoral joint were started at 6 months so as not to
compromise graft anchorage.
Preliminary results indicate that MPFL reconstruction
using an autologous hamstring graft is a simple, implant
free, cost effective procedure with little associated donor
site morbidity and good preliminary outcomes; it greatly
helps in preventing further episodes of patellar
subluxations or dislocations and in improving quality of
Further clinical studies are needed to confirm these early