Joint Replacements

• Causes: – Trauma – Osteoarthritis – Reumatoid Arthritis • Indication for Surgery – Severe Pain – Severe Deformation (knee in particular) • Risks: – Infection, – Mechanical Failure (loosening etc.)

Joint Replacements

• The Joint Surface Problem (tribology) • The lubrication problem – Synovial fluid has to be the lubricant • Artificial joint does not employ the same hydrodynamic mechanism • How does a bearing work (hydrodynamics) • The wear debris and their consequences • The interface problem

Hip Mechanics and Standing Posture

Shock Absorption of the Joint

• Strictly essential in the lower limb joints, to protect the bone implant interface • Cartilage + Hydrodynamics in the Biological joint • Metal-UHMWPE (plastic) Cartilage

Bone Morphology

Hip Mechano-Morphology

Bone Disease: Osteoporosis Normal Bone Osteoporosis

Osteoporotic Femoral Head Normal Hip Osteoporotic Hip

Hip Fractures

(From Howmedica) O ver 250,000 hip fractures occur in the United States annually. 90% of these are in patients over 50 years old. With the growing aging population, the number of hip fractures is expected to

double

in less than 50 years. Types of hip fractures include: femoral neck fractures and fractures of the intertrochanteric and subtrochanteric regions. Femoral neck and intertrochanteric fractures occur with equal frequency and account for over 90% of all hip fractures. The remainder are subtrochanteric fractures. Treatment options range from internal fixation to total joint replacement.

Severity Based on Fracture Site

Subcapital v. Per-Trochanteric

Garden’s Classifications of Hip Fractures Type

I

fractures have the best outcome. The bone ends are impacted into one another, which facilitates vascular re growth.

HIP FRACTURE SOLUTIONS

OMEGA PLUS COMPRESSION FEMORAL SCREW SYSTEM The Complete System for Faster, Easier Surgery.

T he Omega Plus CHS System includes such features as sideplates made of superstrong alloy material, improved instrumentation, and the unique 98 o ergonomically designed Supracondylar Plate which conforms to distal condyles with minimal contouring. Omega Plus plates and lag screws are available in sterile or non-sterile packaging for customer preference and convenience.

The Austin Moore Hip Implant

Nailing the Head-Neck

Hip Replacement If there is damage to the acetabulum the patient may require a

Complete hip replacement

.

Hip Joint Prosthesis

The Bone-Prosthesis Interface • Long stem in hip and elbow prostheses • Short stem in knee • Method of fixation – Acrylic bone cement – Simple contact (contour congruency) – Porous technology

Composite Beam (two materials)

• For the beam to bend as one it should transmit shear • If one material is much more rigid it bears most of the stress • Preference in prosthetics is to have materials with rigidity similar to bone

Criteria to be Observed • Minimal bone removal • Mechanical compatibility (adjustment of compliance, Young’s moduli etc.) • Avoid stress concentration • Avoid stress shielding • Provide for easy extraction?? In case of revision surgery Anything else??

Fracture Fixation Examples of Fractures

• Simple fracture • Displaced fracture • Comminuted fracture • Long bone fracture • Vertebral fracture • Rib fracture • Clavicular fracture • Pelvic fracture • Radial fracture • Finger fracture

Bone-Plate Fixation • Dynamic loading required • Double plating may produce stress shielding • Care is needed with the periosteum • In some cases, compression plate is preferred

Bone Plates Cont

.

• In the epiphyseal region more screw support is needed • Nail-Plate combination

Intramedullary Nailing • Femoral nail vs. plating

Intramedullary Nailing http://www.smithnephew.com/orthopaedics/products .

Knee Arthrodesis

The Knee Goes Bad

Radical Solution: Tibio Femoral Fusion

Anatomical Constraints

Total Knee Arthroplasty

Bone Preparation for Total Knee Arthroplasty

Procedure of Total Knee Arthroplasty

Cemented versus Cementless Total Knee Arthroplasty

Radiographic Imaging of Total Knee Arthroplasty

Prosthetic Knee

Hinge Knee Joint

Artificial Knee

Knee

Hoffman External Fixator B ased on the long-standing tradition of the original Hoffmann Fixator, the new Hoffmann II design provides today's surgeon with advanced technology and ease of application. The new spring loaded snap fit mechanism allows the easy connection of 8mm connecting rods or pins providing versatile intraoperative frame management and excellent stability. The system allows independent pin placement of 4 or 5mm

Apex

Pins and is ideally suited for proximally or distally located fractures. The system is designed with versatile and simple instruments with a single wrench that fits all screws. A multi pin clamp is designed to accept the same pin placement as the original Hoffmann with single or bi-lateral torx connections allowing 12 angular positions for a compact frame design. http://www.howmedica.com/

External Fixator

Monotube External Fixator http://www.howmedica.com/

Fracture Fixation http://www.howmedica.com/

Bone Lengthening

Arm Fractures Fixation Radial Fracture Bridging http://www.howmedica.com/

Pelvic Fracture External Fixation

Ligament Rupture

Bioresorbable Materials Stimulan™, medical grade calcium sulfate dihydrate and stearic acid, is an osteoconductive material used to fill bone voids in non weight bearing applications that resorbs and is replaced with bone during the healing process. Stimulan is indicated for uses in cases where there is a bony defect or void in the boneTraumaSpinal fusions Revision SurgeryInfected JointsCore DecompressionsOsteoporosis Advantages of Stimulan: Predictable, consistent resorption ratesEliminates need for second surgical site and added pain for patient that occurs with traditional autograft techniqueCost and time savings per procedure over autograftOsteoconductive material that acts as scaffolding for new bone to formEliminates risk of disease transmission and availability of quality bone present with traditional allograft techniqueProven dissolution rates

Bioabsorbable ACL Cross Pin

Bioabsorbable Screws

Femoral Neck Fracture Fixation Proximal Femur

The Shoulder Bones

Coracoid Process Acromion Clavical Humerus Scapula Glenoid Cavity

Ligaments of the Shoulder

Acromioclavicular Joint / Coracoclavicular Ligaments Acromion Clavicle

Supraspinatus Subclavius

Subscapularis

Lattisimus Dorsi Teres Major Deltoid Muscles (Posterior | Anterior)

Supraspinatus Infraspinatus Teres Minor

Teres Major Deltoid

Noel Pins Inter Trochanteric Nail

Supracondilar Plate

Proximal Tibia

Carpal and Finger Plates

The Spinal Segment

Harrington Rod

Spine Posterior

Spinal Implants

Isobar® TTL Posterior Spinal System

System allows the use of either "U" Screws or Hemispherical Screws with Offset Clamps Unique Claw Hooks provide firm and secure fixation The Monobloc Clamps allow the screws to be positioned according to the anatomy Screws are available in multiple sizes to accommodate all patient anatomy Rigid and Semi-Rigid Rod options are available to cover a wide variety of surgical indications A unique instrument prevents cross threading of the Blocker Nut when applied on the "U" Screws or Hook http://www.encoreortho.com/products.html

Spinal Implants QuickTime™ and a GIF decompressor are needed to see this picture.

Intervertebral Cage

CC Lumbar Intervertebral Cage System

The material, PEEK, has a modulus of elasticity close to that of bone, improving the biomechanical interface The radiolucent design allows direct visualization of the osteogenesisThe superior and inferior surfaces of the device are notched to achieve stabilization of the implants within the vertebral endplatesThe cages are available in straight and lordotic designs in order to replicate the normal anatomic lordosis of the lumbar spineCages are available in five thicknesses to accommodate a wide range of anatomy This product is not yet approved to sell in the United States.

http://www.encoreortho.com/products.html

Spinal Interbody Fusion

Zigomatic Fracture Fixation

Distal Tibia

Proximal Radius-Ulna Fracture Plates

Distal Radius and Distal Ulna

Distal Humerus

See you next time