Why Total Knees Fail?
Aaron G. Rosenberg, M.D. Professor of Orthopaedic
Surgery Arthritis &
Orthopaedic Institute Rush Medical College Rush-Presbyterian –St.
Luke Medical Center Chicago, Illinois Total
knees may fail “prematurely” for one of many reasons but they can all be
organized into one of several basic problems: 1) Component design errors 2) Material property inadequacies 3) Inappropriate patient selection criteria 4) Surgical technique and instrumentation errors 5) Postoperative decision making 1) Component Design Errors A) Patella 1) Inadequate poly
thickness combined with metal backing 2) Inadequate ingrowth
designs B) Femur 1) Inadequate trochlear
sulcus a)
symmetrical non-anatomic designs b) inadequate trochlear depth b)
inadequate trochlear length (in deep flexion) c)
excessive lateral shoulder height (causing soft
tissue irritation) C) Tibia 1) Inadequate poly locking
mechanisms 2) tibio-femoral
articulation problems a) edge loading b) lift off c) exceeding
yield stresses 2) Material Property
Inadequacies A) Polyethylene 1) Oxidation a) Sterilization
Techniques b) Storage
excesses c) manufacturing
process 1) heat
pressing 2) ram
extrusion and machine finishing 2) Raw material
inadequacies a) inclusions b) variation in
material properties 3) Patient Selection
Problems A) Workmen's compensationitis B) Expectation result mismatch C) Lack of appropriate underlying pathology D) Multiply operated-never satisfied
patient E) Depressed, sleep disordered
patients 1) Chronic fatigue syndrome 2) Fibromyalgia 3) Etc. 4) Surgical Errors A) Poorly placed incisions 1) Skin sloughs, wound
healing problems B) Inadequate soft tissue releases 1) Persistent malalignment 2) Instability D) Mismatched flexion/extension gaps 1) Recurvatum or flexion
contracture 2) Inadequate flexion E) Failure to achieve appropriate
PCL tension 1) Instability 2) Stiffness in flexion F) Rotational malpositioning 1) Stiffness 2) Patellar
Subluxation/Dislocation G) Inadequate debridement 1) Recurrent Hemarthrosis 2) Persistent joint line
pain 3) Meniscal symptoms H) Extensor mechanism details 1) Failure to resurface 2)
Sloping patellar cuts 3)Overstuffing the
compartment with inadequate bone cuts 5) Post operative Errors A) Wound healing problems 1) Failure to intervene a) stop motion b) raise pO2 ` c) debride and flap B) Failure to achieve adequate motion 1) CPM for failure to
progress 2) Manipulate early for
failure to achieve motion  Previous Lecture |
