SRI SIDDHARTHA MEDICAL COLLEGE,TUMKUR DEPARTMENT OF
ORTHOPAEDICS
SRI SIDDHARTHA MEDICAL COLLEGE,TUMKUR DEPARTMENT OF
ORTHOPAEDICSTopic:DYNAMIC MEDIAL PATELLOFEMORAL LIGAMENT
RECONSTRUCTION IN RECURRENT PATELLAR INSTABILITY:A surgical
technique
Moderator:Prof. Dr. J.K ReddyDept. of Orthopaedics
Presenter:Dr. Jaipalsinh MahidaJr. Resident M.S Ortho Dept. of
Orthopaedics
Introduction:Recurrent patellar instability is common after a
primary episode of traumatic patellofemoral dislocation. There is
damage to the MPFL in almost all cases of traumatic patellofemoral
dislocationDislocation is a result of anatomical abnormalities
and/or insufficient soft tissue restraints. 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.
Anatomy:Static stabilizers: Are primary stabilizers of patella
shape of patella, femoral sulcus, patellar tendon of appropriate
length, and normally tensioned medial capsule reinforced byMedial
patellofemoral ligament and patellotibial ligaments. Dynamic
stabilizer vastus medialis obliquus stabilizes the patella against
lateral pull of vastus lateralis.
Biomechanics: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 dislocation. With the greater
knee flexion, the bony confines of the lateral femoral condoyle and
trochlear groove captures the patella and patellar stability.
PathoAnatomy: 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
factorsTrochlear dysplasiaPatella alta Patella tilt TT-TG
distance(q angle quantification by CT scan)Secondary instability
factorsExcessive external femoral rotation / Excessive femoral ante
versionExcessive external tibial rotationGenu valgumGenu
recurvatum
Evaluation:
We evaluate the following features:-Integrity of medial patello
femoral ligamentHeight of patella on physical and radiographic
examinationLength of patellar tendonPosition of patella in
relationship to trochlea
Physical examination:
gaitstanding alignmentQ angle:- for males : mean Q angle is 10 -
for females : mean Q angle is 155 - q angle leads to relative
lateral shift of patella Q angle results from - femoral external
rotation - external rotation - genu valgum - tibia vara
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
Qangle.
Apprehension test : Patella pushed laterally in 200 - 300 of
flexion
Laxity: 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.
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
tightness.
rotational malalignment:Measured by the relationship of the
transmalleolar axis to the Coronal axis of the proximal tibia, is
typically neutraltibial torsion also may be assessed through
measurement of the thigh-foot angle, average values are 5internalIt
leads to Increase Q angle and Increase TT-TG distance
excessive femoral ante version:measured by hip rotations with
the patient in prone position with hips extended and knees at 90of
flexionNormal 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
Radiographic evaluation:long standing weight bearing
hip-to-ankle, A.P view: helps in assessing the angular deformity of
knee i.e. genu varum and genu valgum
Lateral view with 30 of knee flexion:Insall-salvati ratio:
normal value: 1.0 to 1.2value 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 instability.
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
femoral cortex.
Merchants view: tangential axial view of patellofemoral joint
obtained with knee in 45 of flexion.Sulcus angle: normal angle :
140, if > 140 : trochlear dysplasia
Congruence Angle: normal : -8 to +14, if >14 indicates
lateral subluxation.
Lateral Patello Femoral Angle(Laurin Angle): normal: angle opens
laterally, abnormal: angle opens medially or lines become
parallel.
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 0to60
of flexion in 10 of increments. Is quantification of Q angle. TT-TG
distance : normal measures are 2to 9 mm , borderline measures are
10to 19 mm, pathological > 20Sulcus angleCongruence
angleTrochlear depth
MANAGEMENT OF PATELLO FEMORAL INSTABILITY:
Types of patellar dislocationsAcute 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 ligament (MPFL). most
acute dislocations are treated non-operatively unless associated
with an osteochondral injury. When surgery is needed MPFL is
repaired / reconstructed
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 three months. 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:Proximal Realignment
Of Extensor Mechanism:Lateral retinacular releaseMedial plication/
reefingVastus Medialis Obliquus advancementMedial PatelloFemoral
Ligament reconstructionDistal Realignment Of Extensor
Mechanism:Medial or antero medial displacement of tibial
tuberosity
MEDIAL PATELLO FEMORAL LIGAMENT RECONSTRUCTION:
The procedures like medial plication, vastus medialis obliquus
advancement, and lateral retinacular release are non anatomic
procedures. They dont 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
MPFL arises from medial surface upper two thirds of patella
above equator and inserts into a groove between adductor tubercle
and medial epicondyle
25
Indication: 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.
2 perpendicular lines drawn to line 1. Line 2 is medial
condyleLine 3 is blumensaat line.26
PostOperative Care: knee joint is immobilized in extension with
a simple knee brace for 3 days after surgery. 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 surgery. 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 is
encouraged. Jogging is allowed after 3 months, and participation in
the original sporting activity is allowed 6 months after surgery,
depending on the patient.
Present study:based on the fixation techniques MPFL
reconstruction procedures can be broadly classified into: Static:on
either side graft is fixed rigidly at isometric points of parent
MPFL with staples or interference screws or anchors in bony
tunnelsDynamic: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.
Operative procedure:
A diagnostic arthroscopy was performed in all patients before
starting reconstruction. The ipsilateral gracilis and
semitendinosus tendon is freed from its attachment distallyCare
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 control. 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.
Postoperatively: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 bracelocked
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.
Discussion:
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 final outcome.
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 tunnel healing. 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 weeks. 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.
Conclusion: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 life. Further clinical studies are needed to confirm
these early results
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