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1
The Zimmer Institute
The Zimmer® MIS™ Anterolateral Hip Procedure
A Muscle-Sparing Approach to THA
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The Zimmer Institute
Objectives
• Discuss the history of minimally invasive surgery in terms of evolution, definitions, approaches, and classification schemes
• Identify the unique characteristics of the Zimmer MIS Anterolateral THA procedure
• Discuss in detail the stages and key elements of the Zimmer MIS Anterolateral THA surgical procedure
• Define the Five Acts of leg positioning and describe how they relate to the various stages of the surgical procedure
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The Zimmer Institute
Objectives (cont.)
• Discuss clinical data obtained from procedure to date
• Define the advantages and disadvantages of the Zimmer MIS Anterolateral THA procedure as they relate to THA in general
• Identify and discuss key concerns in the overall continuum of care related to the Zimmer MIS Anterolateral THA procedure
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The Zimmer Institute
Minimally Invasive Surgery: History, Evolution, Definitions, and Approaches
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The Zimmer Institute
Minimally Invasive Surgery:Evolution in THA Procedures
• Maximally invasive 60s/70s
• Moderately invasive 80s/90s
• Minimally invasive Turn of the century
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The Zimmer Institute
Maximally Invasive Surgery
• Typically Provides:
Wide Exposure
Neurovascular protection
Confident implant placement
With this incision I can do every hip:I can expose it,
I can see it,I can teach it
(C. S. Ranawat, CCJR 2003)
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The Zimmer Institute
What is the Minimally Invasive THA?
• Length of Incision?
• Length of capsule incision.
• Amount of muscle trauma!
• Amount of bone loss!
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The Zimmer Institute
Minimally Invasive THA Classification
Eponymous
• Modified Watson Jones
• Modified Smith Peterson
• Modified Moore
• Keggi/Mears/Röttinger
…does not connote much meaning
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The Zimmer Institute
Minimally Invasive THA Classification
Proposal
• Direction
• Number of incisions
• Method of deep dissection
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The Zimmer Institute
Minimally Invasive THA Classification
Direction is the key
• Gluteus Medius is the signpost
• Anterior
• Anterolateral
• Lateral
• Posterior
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The Zimmer Institute
Minimally Invasive THA Classification
Number of incisions
• Single Incision – acetabular/femoral preparation through one incision
• Two incisions – acetabular preparation through anterior incision and femur preparation through posterior incision
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The Zimmer Institute
Minimally Invasive Surgery THA
Method of Deep Dissection is key
• Do you divide or go between the muscles and tendons?
Traditional – Cut
Mini Anterolateral – Cut less
MIS Anterolateral – Spare
• Spare: to refrain from doing harmMerriam Webster’s Dictionary
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The Zimmer Institute
Minimally Invasive THA Classification
Method of Deep Dissection
• Anterior - Muscle Sparing
• Anterolateral - Muscle Sparing
• Lateral - Muscle Cutting
• Posterior - Muscle Cutting
• Two-incision - Muscle Sparing
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The Zimmer Institute
Introduction to the Zimmer MIS Anterolateral THA Procedure
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The Zimmer Institute
The MIS Anterolateral Approach
• A single incision
• Muscle sparing approach to the hip
• Interval between the anterior border of the gluteus medius and the posterior border of tensor fascia lata.
• Minimally invasive modification conceived by Heinz Röttinger, M.D. from the Orthopädische Chirurgie München (O.C.M.) Munich, Germany in 2003
Tensor Fascia Lata
Gluteus Medius
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The Zimmer Institute
The MIS Anterolateral Approach – Overview
• Interval between Gluteus Medius and Tensor Fascia LataNo division of any muscle or tendon
• Acetabulum and femur directly visualized
• 8-10 cm incision
• Posterior capsule intact → lower risk of dislocation
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The Zimmer Institute
The MIS Anterolateral Approach – Overview (cont.)
• Extensile - bail out is full Watson Jones exposure
• Acceptable learning curve
• Familiar lateral positioning
• Clear of neurovascular hazards
• Compatible with most contemporary Zimmer implants
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The Zimmer Institute
The MIS Anterolateral Key Principles
• Identification of interval
• Anatomical referencing
• Retraction and mobile window
• Femoral exposure/Extensibility of capsular incision
• Leg positioning
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The Zimmer Institute
MIS Anterolateral Procedure
The Five Leg Positions
1. Skin and Capsular Incisions/Closure
2. Transcapital Neck Cut
3. Definitive Neck Cut
4. Acetabulum
5. Femur
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Leg Positioning
IncisionsFemoral Side
Acetabular Side
Definitive Osteotomy
1st Femoral Cut
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The Zimmer Institute
Surgical Technique for the Zimmer MIS Anterolateral THA Procedure
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The MIS Anterolateral Surgical Considerations
• Pre-op Templating
• Table
• Positioning
• Draping
• Incision
• Dissection
• Capsule
• Referencing (intra-operative measurements)
• Neck Osteotomies
• Acetabulum
• Femur
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The Zimmer Institute
Templating
• Measure down from the “Saddle”• Other anatomical references • Lesser trochanter can usually be palpated for cross reference
Greater Trochanter
“Saddle”
Lesser Trochanter
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Surgical Technique
• Table set up Trumpf Jupiter table or Maquet Skytron table attachments Local custom modification
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Patient and Table Preparation
• Patient in direct lateral position• Securely held on table• Leg support modified to allow posterior leg
positioning• Surgeon works on anterior side
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Draping
• Drape can become unstable
• Sterile bag
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Team Positioning
• Surgeon Anterior
• 1st Assistant Distal/Posterior
• 2nd Assistant Posterior
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Skin Incision and Intermuscular Interval
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The Zimmer Institute
Skin Incision
• Identify greater trochanter and anterior superior iliac crestExtend incision from anterosuperior aspect of greater
trochanter about 8cm to a point 2-4cm posterior to the ASIS
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The Interval
Tensor FasciaLata
Gluteus Medius
Approximate incision location
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The Interval
Tensor Fascia Lata
Gluteus Medius
Head
ASIS
GreaterTrochanter
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Capsular Exposure• The Instruments
Retractors numbered for ease of use Optimized radius to be gentle to muscle
Retractor 1 Retractor 2
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The Interval
Gluteus Medius
Tensor Fascia Lata
Capsule
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Capsulotomy
• A “Z” shaped capsular incision with two flaps is created
Slight internal hip rotation
Neutral to slight hip abduction
Ability to extend lateral capsular incision can be critical to obtaining adequate femoral exposure
T or H shaped capsular incisions are certainly viable options
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The Zimmer Institute
Femoral Neck Exposure
• Retractors are replaced inside the capsule
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Referencing
• The “Saddle”
• Other anatomical references
• Lesser trochanter can usually be palpated for cross reference
“Saddle”
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First Neck Osteotomy
• Femoral head and neck are taken out in two pieces
• First “neck” cut is in articular portion of femoral head
• Direct blade inferior
• Externally rotate maximally to approximately 60 or to allowable range of motion
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The Zimmer Institute
Neck-Head Disassociation
• Place Cobb elevator in the first neck cut
• Move leg into extension and external rotation and lever with Cobb elevator to disassociate femoral neck from residual head and deliver neck into incision
• Neck will now be parallel to the floor
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Definitive Femoral Neck Cut(s)
• Hip and leg are rotated 90 externally with thigh parallel to the floor
• Slight hip flexion may help and saw must be adjusted accordingly
• Retractors placed more distal on neck
• Osteotomy - Identify referencesOblique portion based on
preoperative plan for angle and position
Horizontal portion medial to trochanter
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Femoral Head Removal
• Proximal positioned first osteotomy facilitates easier removal
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The Zimmer Institute
Acetabular Exposure
• The Instruments Retractors
Retractor 1 Retractor 3
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The Zimmer Institute
Acetabular Exposure
• Retractor Placement 4 o’clock and 8 o’clock positions
Retractor 1
Retractor 3
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The Zimmer Institute
Acetabular Preparation
• The Instruments
Offset reamer handle, low profile reamers and offset cup positioner
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The Zimmer Institute
Acetabular Preparation• Reaming
Position handle superiorly with flat portion of low profile reamer resting on superior rim of acetabulum
Rotate reamer handle distally and position reamer Hip flexion and abduction can facilitate insertion
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The Zimmer Institute
Acetabular Preparation
• Acetabular implant
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The Zimmer Institute
Femoral Exposure - Leg Position
• Foot and leg in a bag on the posterior table
• Deliver the proximal femur into the incision for instrumentation
• 20 Extension• 40 Adduction• 90 External Rotation
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Femoral Preparation
• The Instruments: Angled/offset rasp handles
400 Rasp Handle 300 Rasp Handle
CLS® Rasp Handle
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Femoral Preparation
• Retractor placementRetractor 3 inferior and
medial to cut femoral neck―Elevates femur―Retracts tensor &
capsule
Retractor 1 lateral to posterior, superior tip of greater trochanter―Retracts abductors
• Remove any residual anterior and lateral capsule at top of neck to deliver femur
Retractor 1
Retractor 3
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Wound closure
• Adapting capsule suture• Deep drain 6 – 24 hours• Closure of fascia• Subcutaneous suture• Intracutaneous suture
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The Zimmer Institute
Surgical Recap: The Five Acts of Leg Positioning
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The Zimmer Institute
MIS Anterolateral Procedure
The Five Leg Positions
1. Skin and Capsular Incisions/Closure
2. Transcapital Neck Cut
3. Definitive Neck Cut
4. Acetabulum
5. Femur
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The Zimmer Institute
Leg Positioning
IncisionsFemoral Side
Acetabular Side
Definitive Osteotomy
1st Femoral Cut
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The Zimmer Institute
Skin and Capsular Incision
• Assistant holds leg in neutral to slight hip abduction
• Relaxes abductors to achieve maximum exposure
• Mayo Stand
• Arm Elevator
Position 1
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Transcapital Neck Cut
• Assistant holds leg in
neutral ab/adduction slight hip flexion external rotation that anatomy
allows
• Foot in bag
• Relaxes iliopsoas
• Provides improved visualization of femoral neck
Position 2
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Definitive Neck Cut
• Assistant moves leg into
90 External Rotation
• Foot in bag
• Femur parallel to floor
• Tibia perpendicular to floor
• Positions femoral neck parallel to floor to visualize cut
Position 3
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Acetabulum
• Assistant moves leg into
Full knee extension Slight external hip rotation
• Slight hip abduction and hip flexion can help insertion and extraction of reamers
Position 4
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Femur
• Assistant moves leg into
90 External Rotation 20 Extension 40 Adduction
• Foot in bag
• Tibia perpendicular to floor
• Elevates femur
Position 5
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Closure
• Assistant moves leg back to initial position
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Clinical Data Associated With the Zimmer MIS Anterolateral THA Procedure
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Clinical data
• 2 surgeons (03/03 – 2/05)
• >700 THA
• Bodyweight 74.5 kg (min. 43 kg, max. 134 kg)
• BMI 26 (maximum 42)
• Surgery time 46 minutes
• Retransfusion volume 302 ml (intraoperative to 6 hrs. postop.)
Röttinger, 2005
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The Zimmer Institute
Clinical Experience – Early Results
• >700 patients
Excellent early mobilization
Decreased pain
Excellent abductor function
Excellent standard approach (also for revisions)
Acceptable learning curve
2 days Post-op
Röttinger, 2005
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The Zimmer Institute
Clinical Experience—Complications
• >700 patients
5 postop. periprothetic fractures ― Caused by a particular femoral component
6 greater trochanter fractures― Asymptomatic
2 dislocations of the acetabular component
3 anterior dislocations ― Increased anteversion of acetabular
component (2 revisions)
Röttinger, 2005
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The Zimmer Institute
Greater Trochanteric Fractures
• No dislocation
• No muscle insufficiency
• Likely related to insufficient lateral superior capsular release
Röttinger, 2005
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The Zimmer Institute
Discussion: Advantages, Disadvantages, and the Continuum of Care With the
Zimmer MIS Anterolateral THA Procedure
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Where does this new approach fit?
Great alternative for surgeons who prefer anterior approaches
• Advantages
Theoretically better early abductor muscle function
Lateral femoral cutaneous nerve and lateral femoral circumflex vessel not in operative field
Acceptable surgical time
No intraoperative x-ray necessary
Acetabulum and femur directly visualized
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Where does this new approach fit?
• More Advantages
Familiar lateral positioning
Compatible with many Zimmer implants
Performed through small incision (patient preference)
Viable bail out
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Where does this new approach fit?
• For surgeons who prefer posterior approach
Many of the aforementioned features with
New view of hip
Low dislocation rate
Time, experience and well designed studies will tell
Röttinger, 2005
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Where does this new approach fit?
• Potential Challenges
New surgeon positioning
May require two surgical assistants
Expect a variable learning curve
Initial risk of complications ―Excessively anteverted cup― Insufficient capsular release
– Varus stem– Greater trochanteric fracture
Obese and very muscular patients still difficult
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Discussion
• Post-Op Care
• Anesthesia
• ChallengesLeg Position IntervalCapsular IncisionAcetabulumFemur
• Patient Outcomes
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Conclusions
• This MIS anterolateral approach is intermuscularPotentially little to no delay in rehabPotentially little to no abductor weakness
• Clinical results are encouraging
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