Aseptic Revision Total Knee Surgical Techniques. Andrew Ehmke, DO Chicago, IL May 5, 2018

Transcription

1 Aseptic Revision Total Knee Surgical Techniques Andrew Ehmke, DO Chicago, IL May 5, 2018

2 I have no disclosures relevant to this talk

3 3 Phases of Revision 1. Exposure Key to the case!! 2. Component Removal 3. Joint Reconstruction

4 Planning Understand mode of failure!!!! Advanced imaging to eval malrotation or osteolysis Exploratory surgery or revision without diagnosis have much worse outcomes Proper equipment in room ALWAYS RULE OUT INFECTION

5 Phase 1 - Exposure KEY TO CASE Use prior incision Extend proximal and distal to find subcutaneous plane MIS revision extremely difficult! Aggressive MCL release All the way around proximal tibia allows subluxation of tibia

6 Phase 1 - Exposure Remove scar/adhesions from medial and lateral gutter Free up Extensor Mechanism Retropatellar scar Debulk Quad Tendon Quad snip? Lateral release RARELY need more ( TTO, Quad Turndown)

7 Phase 1 Exposure Video

8 Phase 2 - Removal Sequence of Removal 1. Polyethylene insert 2. Femoral component 3. Tibial component 4. Patella

9 Phase 2 Removal Poly opens up working space ability to flex and extend to remove excess scar tissue and work at implants Drive Osteotome into the poly-implant interface Remove any locking pin prior Beware of screw in medium constraint constructs (eg LCCK)

10 Phase 2 Removal Femur Power Saws Very fast with minimal bone loss Sagital or Recip saw Heats up and melts cement Vibrations at implant-cement interface loosen bond Osteotomes Extraction Tools from manufacturer Back slaps Bone tamp or disimpactor Remove component with axial blows

11 Phase 2 Removal Femur Video

12 Power saws Osteotomes Extraction Tools/Bone Tamp for removal Phase 2 Removal Tibia Sublux tibia forward Flexion/External rotation Get Posterior!!! Lateral release can help to access the posterior lateral corner

13 Phase 2 Removal Tibia

14 Phase 2 Removal Patella Usually not done in aseptic revision unless gross malposition Removal with Short wide blade, saw through pegs Burr around remaining pegs

15 Phase 3 - Reconstruction 1. Flexion gap larger then extension gap 2. Joint line raised due to implant removal and subsidence of femur GOALS Restore flexion stability Restore joint line Tibia affects both gaps symmetrically Restore gaps by shifting femur as necessary Distalizing femur with augments *joint line 25mm from medial condyle* Posteriorizing femur with offset and upsizing component

16 Contained or Segmental? Metaphyseal fixation? Cone vs Sleeve Tibial and/or Femoral Phase 3 Reconstruction Assess bone loss Stem cemented or pressfit? Stem length? Bypass segmental defects or increase fixation strength

17 Phase 3 - Reconstruction Cementless Stem Fixation Must engage diaphysis with cementless! Short metaphyseal cementless stems FAIL Ream until no longer advances May need offset due to engagement of diaphysis and bow Easier to get out Don t cement in offset

18 Phase 3 Reconstruction Cemented Stem Fixation No offset Can position where needed Easy preparation Strong initial fixation No end of stem pain Antibiotic delivery Difficult to remove!

19 Phase 3 Reconstruction Metaphyseal Fixation Cone Placed independent of component Can be used with different systems (off label use) Prepared with burr or reamer Wide variety to accommodate small to large defects Sleeve Linked to component via Morse taper Good long term data Ease of preparation with broach Ability to do cementless revisions? Can fracture sclerotic bone Ability to accommodate large defects?

20 Why important? Phase 3 Reconstruction Metaphyseal Fixation Allows Ingrowth in zone 2 Large surface area for biologic ingrowth Better long term fixation? Rich vascular blood supply Morgan-Jones R. (2015) Bone Loss in Revision Total Knee Arthroplasty. In: Rodríguez-Merchán E., Oussedik S. (eds) Total Knee Arthroplasty. Springer, Cham

21 Phase 3 Reconstruction Tibial Cone Preparation

22 Phase 3 Reconstruction Femoral Cone Preparation

23 Phase 3 Reconstruction Tibial Sleeve Preparation Orthopedics Sep;29(9 Suppl):S Broach until rotationally stable Cement in real tibial construct Pressfit sleeve hold in place while cement dries Can start working on femur

24 Phase 3 Reconstruction Femoral Sleeve Preparation

25 Phase 3 Reconstruction Tibial Cuts Based off intramedullary guidance perpendicular to mechanical axis Skim cut to give flat solid platform to reference the rest of case Correct previous alignment errors and avoid new ones to tibia Effects both flexion and extension gap

26 Phase 3 - Reconstruction Distal Femur Cuts Distal Cut Freshen cut for flat platform Correct varus/valgus alignment Evaluate joint line Measure from joint line 25 mm from medial epicondyle Evaluate need for augments

27 Phase 3 Reconstruction 4 in 1 cuts Size femur Typically upsize to fill flexion gap Rotation Set rotation off epicondylar axis Set rotation of spacer block Offset Posterior to fill flexion gap Evaluate need for augments Often need posterior augments due to posterior offset of femur.

28 Phase 3 - Reconstruction Gap / Soft Tissue Balance 1. Fill flexion gap first Start with 2-4 mm posterior offset on femur Go up one size from previous component Wedge osteotome or cobb in à 1-2mm play Palpate MCL 2. Evaluate extension gap If tight à aggressive posterior capsule release àextra distal femur resection Beware excessive joint line elevation à patella baja More posterior offset or upsize component if room 3. Evaluate patella tracking

29 Phase 3 Reconstruction Balancing a Hinge When can t get control of flexion gap without grossly elevating joint line Gross medial instability Balance in Extension only Make sure no patella baja (raised joint line) Adequate external rotation to avoid patella tracking issues Number one complication of hinge Femoral and tibial metaphyseal fixation due to high implant stresses

30 Thank You!