Transcript Injuries to the Patella and Extensor Mechanism

Patella Fractures & Extensor
Mechanism Injuries
Lisa K. Cannada, MD
Revised: October 2008; May 2011
Anatomy
• Largest sesamoid bone
• Thick articular
cartilage proximally
• Articular surface
divided into medial
and lateral facets by
longitudinal ridge
• Distal pole
nonarticular
Anatomy
• Patellar Retinaculum
– Longitudinal tendinous
fibers
– Patellofemoral
ligaments
• Blood Supply
– Primarily derived from
geniculate arteries
Biomechanics
• The patella undergoes approximately 7 cm
of translation from full flexion to extension
• Only 13-38% of the patellar surface is in
contact with the femur throughout its range
of motion
Biomechanics
• The patella increases
the moment arm about
the knee
– Contributes up to 30%
improvement in lever
arm
• Patella withstands
compressive forces
greater than 7X body
weight with squatting
Biomechanics
• 2 X Torque:
– Extend final 15°
– Than to extend from a
fully flexed position to
15 degrees of flexion
Physical Examination
• Pain, swelling, contusions, lacerations
and/or abrasions at the site of injury
– Can determine timing of operative intervention
• Palpable defect
• Assessment of ability to extend the knee
– Cannot perform a straight leg raise with no
extensor lag
Radiographic Evaluation
• AP & Lateral
– Note patella height (baja or alta)
– Note fracture pattern
• Articular step-off, diastasis
• Marginal impaction
• Special views
– Axial or sunrise
• CT Scan
- Occult Fractures
- Complex or Marginal Impaction
Fractures
Radiographic Evaluation
• Bipartite Patella:
• Don’t get fooled!
– Obtain bilateral views
– Often superolateral corner
(Saupe Classification, 1923)
– Accessory ossification center
– Occurs 1-2% of patients
Etiology
• Direct trauma
– Direct blow to flexed knee (dashboard)
– Increasing cases with penetrating trauma
– Comminution & articular marginal impaction
• Indirect trauma
– Flexion force directed through the extensor
mechanism against a contracted quadriceps
– Simple, transverse fracture
Classification
• Allows guidance with
treatment
• Types
–
–
–
–
–
–
Transverse
Marginal
Vertical
Comminuted
Osteochondral
Avulsion (not pictured)
Tip: Vertical fractures may not result in disruption of extensor mechanism
OA/OTA
Classification
Nonoperative Treatment
• Indicated for minimally or nondisplaced fractures
– < 2mm of articular step-off & < 3mm of diastasis with an
intact extensor mechanism (extensor retinaculum)
– If difficulty assessing, consider intra-articular injection of
local anesthetic to better assess ability to extend
• Consider for minimally displaced fractures in low
demand patients (evaluate comorbidities & function)
• Patients with a extensive medical comorbidities
Nonoperative Treatment
• Long leg cylinder cast for 4-6 weeks
– May consider a knee immobilizer or hinged
knee brace for the elderly/low demand
• Immediate weight-bearing as tolerated
• Rehabilitation includes range of motion
exercises with gradual quadriceps
strengthening
• Protect eccentric contraction 3 months
Operative Treatment
• Goals
– Preserve extensor function
– Restore articular congruency
• Preoperative Setup
– Tourniquet (debatable)
• Prior to inflation, gently flex the knee
• Approach
– Longitudinal midline incision
recommended
– Transverse approach alternative (dotted
lines) – potentially higher risk wound
problems, can limit initiation of ROM
– Consider future surgeries!
Procedure
Longitudinal
Incision
Clean Fracture
Site
Torn
Retinaculum
Procedure
Reduce & Compress Fracture
Operative Techniques
• K-wires w/ tension band wiring (TBW)
• Lag-screw fixation
• Cannulated lag-screw with TBW (tension
band screw – TBS)
• Partial patellectomy
• Total Patellectomy
Tension Band Wiring
• Transverse, non-comminuted
fractures
• Reduce and clamp, then place
two parallel 1.6mm K- wires
placed perpendicular to the
fracture
• 18 gauge wire passed behind
proximally and distally
• Double Figure-8 wire for equal
compression
Tension Band Wiring
• Wire converts anterior distractive
forces to compressive forces at the
articular surface
• Two twists are placed on opposite
sides of the wire
– Tighten simultaneously to achieve
symmetric tension
• Retinacular Injury
– Keep open until the end
– Window to assess articular reduction
– Repair the retinacular injury last
Lag-Screw Fixation
• Indicated for stabilization
of comminuted fragments
in conjunction w/ cerclage
wires if necessary
• May also be used as an
alternative/adjunct to
TBW for transverse or
vertical fractures
Example
Example
Lag-Screw Fixation
• Contraindicated for extensive comminution and
osteopenic bone
• Small secondary fractures may be stabilized with
2.0mm, 2.7mm or 3.5mm cortical screws
• Reduce out of plane fragments to main fragments
superiorly and inferiorly
• Transverse or vertical fractures require 3.5mm,
4.0mm, or 4.5mm cortical screws
– Retrograde insertion of screws may be technically
easier
Cannulated Lag-Screw With
Tension Band (TBS)
• Partially threaded
cannulated screws
(4.0mm)
• Wire through screws
and across anterior
patella in figure of
eight tension band
• Make sure tip of
screw remains buried
in bone so it will not
compromise wire
Cannulated Lag-Screw With
Tension Band
• More stable construct
– Screws and tension band wire combination
eliminates both possible separation seen at the
fracture site with K wire/TBW and screw
failure due to excessive three point bending
Suture vs. Wire Tension Band
Gosal et al Injury 2001
• Wire v. #5 Ethibond
• 37 patients
• Reoperation 38% wire
group vs. 6%
• Infection 3 pts wire
group vs. 0
Patel et al, Injury 2000
McGreal et al, J Med
Eng Tech, 1999
• Cadaveric models
• Quality and stability
of fixation comparable
to wire
• Conclude suture an
acceptable alternative
Partial Patellectomy
• Indicated for fractures involving
extensive comminution not amenable
to fixation
• Larger fragments repaired with screws
to preserve maximum cartilage
• Smaller fragments excised
– Usually involving the distal pole
Partial Patellectomy
• Tendon is attached to fragment with
nonabsorbable suture passed through drill
holes in the fragment
– Drill holes should be near the articular surface
to prevent tilting of the patella
• Load sharing wire passed through drill
holes in the tibial tubercle and patella may
be used to protect the repair and facilitate
early range of motion
Total Patellectomy
• Indicated for displaced, comminuted
fractures not amenable to reconstruction
• Bone fragments sharply dissected
• Defect may be repaired through a variety of
techniques
• Usually results in extensor lag (30°) and
loss of strength (30%) – H Kaufer, JBJS
Postoperative Management
• Immobilization with knee brace, WBAT in extension
• Early range of motion
– Based on intraoperative assessment of repair & bone quality
– Active flexion with passive extension
• Quadriceps strengthening
– Begin when there is radiographic evidence of healing,
usually around 6 weeks
• Modify depending upon fracture, osteoporosis,
comorbidities, tenuous fixation and/or wounds at risk
Complications
• Knee Stiffness
– Most common
complication
• Infection
– Rare, depends on soft
tissue compromise
• Loss of Fixation
– Hardware failure in up
to 20% of cases
• Osteoarthritis
– May result from
articular damage or
incongruity
• Nonunion < 1% with
surgical repair
• Painful hardware
– Removal required in
approximately 15%
Nonunion
Loss of Fixation
Malunion
Extensor Tendon Ruptures
• Patients are typically males in
their 30’s or 40’s
– Patellar < 40 yo
– Quadriceps > 40 yo
• Mechanism
– Fall
– Sports “The weekend warrior”
– MVA
– Tendonopathies, Steroids, Renal
Dialysis
Quadriceps Tendon Rupture
• Typically occurs in patients > 40 years old
• Usually 0-2 cm above the superior pole
• Level often associated with age
– Rupture occurs at the bone-tendon junction in
majority of patients > 40 years old
– Rupture occurs at midsubstance in majority of
patients < 40 years old
Quadriceps Tendon Ruptures
• Risk Factors
–
–
–
–
–
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Chronic tendonitis
Anabolic steroid use
Local steroid injection
Inflammatory arthropathy
Chronic renal failure
Systemic disease
History
• Sensation of a sudden pop while stressing
the extensor mechanism (eccentric load)
• Pain at the site of injury
• Inability to extend the knee
• Difficulty weight-bearing
Physical Exam
• Effusion
• Tenderness at the
upper pole
• Palpable defect above
superior pole
• Loss of extension
• With partial tears,
extension will be
intact
Quadriceps Tendon Rupture
Radiographic Evaluation
• X-ray- AP, Lateral, and
Tangential (Sunrise,
Merchant)
– Distal displacement of
the patella (patella baja)
• MRI
– Useful when diagnosis
is unclear
Treatment
• Nonoperative
– Partial tears and strains
• Operative
– For complete ruptures
Operative Treatment
• Reapproximation of tendon to bone using
nonabsorbable sutures with tears at the
muscle-tendon junction
– Locking stitch (Bunnel, Krakow) with No. 5
ethibond passed through vertical bone tunnels
– Repair tendon close to articular surface to avoid
abnormal patellar tilting
Operative Treatment
• Midsubstance tears may
undergo end-to-end repair
after edges are freshened
and slightly overlapped
– May benefit from
reinforcement from distally
based partial thickness
quadriceps tendon turned
down across the repair site
(Scuderi Technique)
Treatment
• Chronic tears may
require a V-Y
advancement of a
retracted quadriceps
tendon (Codivilla VY-plasty Technique)
Postoperative Management
• Knee immobilizer, Hinged Knee Brace, or
cylinder cast for 5-6 weeks
• Immediate weight-bearing as tolerated
• At 2-3 weeks, hinged knee brace starting
with 45 degrees active range of motion with
10-15 degrees of progression each week
Complications
• Rerupture
• Persistent quadriceps
atrophy/weakness
• Loss of motion
• Infection
Patellar Tendon Rupture
• Less common than
quadriceps tendon
rupture
• Associated with
degenerative changes
of the tendon
• Rupture often occurs
at inferior pole
insertion site
Patellar Tendon Rupture
• Risk Factors
– Rheumatoid arthritis
– Systemic Lupus
Erythematosus
– Diabetes
– Chronic Renal Failure
– Systemic
Corticosteroid Therapy
– Local Steroid Injection
– Chronic tendonitis
Anatomy
• Patellar tendon
– Averages 4 mm thick but widens to 5-6 mm at
the tibial tubercle insertion
– Merges with the medial and lateral retinaculum
– 90% type I collagen
Blood Supply
• Fat pad vessels supply posterior aspect of tendon
via inferior medial and lateral geniculate arteries
• Retinacular vessels supply anterior portion of
tendon via the inferior medial geniculate and
recurrent tibial arteries
• Proximal and distal insertion areas are relatively
avascular and subsequently are a common site of
rupture
Biomechanics
• Greatest forces are at 60 degrees
of flexion
• 3-4 times greater strain are at the
insertions compared to the
midsubstance prior to failure
• Forces through the patellar tendon
are 3.2 times body weight while
climbing stairs
History
• Often a report of
forceful quadriceps
contraction against a
flexed knee
• May experience and
audible “pop”
• Inability to weightbear
or extend the knee
Physical Examination
• Palpable defect
• Hemarthrosis
• Painful passive knee
flexion
• Partial or complete
loss of active
extension
• High riding patella on
radiographs (patella
alta)
Radiographic Evaluation
• AP and Lateral X-ray
– Patella alta seen on lateral view
• Patella superior to Blumensaat’s line
• Ultrasonagraphy
– Effective means to confirm diagnosis by determining
continuity of tendon
– Operator and reader dependant
• MRI
– Effective means to assess patellar tendon, especially if
other intraarticular or soft tissue injuries are suspected
– Relatively high cost
Classification
• No widely accepted means of classification
• Can be categorized by:
– Location of tear
• Proximal insertion most common
– Timing between injury and surgery
• Most important factor for prognosis
• Acute: < 2 weeks
• Chronic: > 2 weeks
Treatment
• Surgical treatment is
required for restoration
of the extensor
mechanism
• Repairs categorized as
early or delayed
Early Repair
• Better overall outcome
• Primary repair of the tendon
• Surgical approach is through a midline incision
– Incise just lateral to tibial tubercle as skin thicker with
better blood supply to decrease wound complications
• Patellar tendon rupture & retinacular tears are exposed
• Frayed edges and hematoma are debrided
Early Repair
• With a Bunnell or Krakow
stitch, two ethibond sutures or
their equivalent are used to
repair the tendon to the patella
• Drill holes in patella in midsagittal plane to prevent cut out
of suture
• Sutures passed through three
parallel, longitudinal bone
tunnels and tied proximally
Early Repair
• Repair retinacular tears
• May reinforce with wire,
cable or umbilical tape
• Assess repair
intraoperatively with knee
flexion
Postoperative Management
• Maintain hinged knee brace which is gradually increased
as motion increases (tailor to the patient)
• Immediate vs. delayed (3 weeks) weightbearing as
tolerated
• At 2-3 weeks, hinged knee brace starting with 45 degrees
active range of motion with 10-15 degrees of progression
each week
• Immediate isometric quadriceps exercises
• All restrictions are lifted after full range of motion and
90% of the contralateral quadriceps strength are obtained;
usually at 4-6 months
Delayed Repair
• > 6 weeks from initial injury
• Often results in poorer outcome
• Quadriceps contraction and patellar migration are
encountered
• Adhesions between the patella and femur may be
present
• Options include hamstring and fascia lata
autograft augmentation of primary repair or
Achilles tendon allograft
Postoperative Management
• More conservative when compared to early
repair
• Bivalved cylinder cast for 6 weeks; may
start passive range of motion
• Active range of motion is started at 6 weeks
Complications
•
•
•
•
•
Knee stiffness
Persistent extensor weakness
Rerupture
Infection
Patella baja (Insall-Salvati ratio of < 0.8)
References Patella Fractures:
New
• Hughes SC, Stott PM, Hearnden AJ, Ripley LG: A
new and effective tension band braided polyester
suture technique for transverse patellar fracture
fixation. Injury 2007:38:212-222.
• Luna-Pizarro D, Amato D, Arellano F, Hernandez
A, Lopez-Rojas P: Comparison of a technique
using a new percutaneous osteosynthesis device
with conventional open surgery for displaced
patella fractures in a randomized controlled trial. J
Orthop Trauma 2006; 20:529-535.
References Patella Fractures:
Classic
• Carpenter JE, Kasman R. Matthews LS: Fractures
of the patella. Instr Course Lect 1994: 43:97-108.
• Burvant JG, Thomas KA, Alexander R, Harris
MB. Evaluation of methods of internal fixation of
transverse patella fractures: A biomechanical
study. J Orthop Trauma 1994;8:147-153.
• Einola S, Aho AJ, Kallio P. Patellectomy after
fracture: long term follow-up results with special
reference to functional disability. Acta Orthop
Scand 1976:47:441-447.
References:
Extensor Mechanism Injuries
• Siwek CW, Rao JP. Ruptures of the extensor
mechanism of the knee joint. J Bone Joint Surg
Am 1981; 63:932-937.
• Bhargava SP, Hynes MC, Dowell JK. Traumatic
patella tendon rupture: early mobilization
following surgical repair. Injury 2004;35:76-79.
• Konrath GA, Chen D, Lock T et al. Outcomes
following repair of quadriceps tendon ruptures. J
Orthop Trauma 1998;12:273-279.
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