Templating of total hip replacement (THR)

Templating of total hip replacement (THR)

• 1.
  Templating & Selectionof implants in THR Prof. Dr. V .S. Ravindranath
• 2.
  Malposition Component orientation Soft-tissue tension Failureto restore hip biomechanics Dislocation Excessive wear Fixation failure Limb length discrepancy Mechanical failure Multifactorial Materials Design Surface finish Position Bone quality Biologic response (wear debris) Infection Why should a THR fail?
• 3.
  History & clinicalexamination Bone quality… age, sex, pre-op diagnosis Level of activity Involvement of other joints Mental status Pre-op ambulation Patient’s expectations Limb length disturbance supra pelvic pelvic infra pelvic Pre operative planning Real LLD Functional LLD
• 4.
  Vocabulary in THR Teardrop Vertical offset Horizontal offset Inclination Version Combined offset JRF- joint reaction force ACR– Acetabular centre of rotation Medialization Lateralization Morse taper Skirted head or non skirted head Impingement TAL
• 5.
  What is templating? Atrial of the implants on the radiographs Why should you template? Precision of surgery Soft tissue balance Shorten the surgical procedure Decrease the post op complications Proper inventory … bone cut & offset
• 6.
  Why do youwant the radiographs? Structural integrity of the Acetabulum The inclination & version Bone stock Protrusio Periacetabular osteophytes Acetabular fractures Dysplasias Template the component Structural integrity of the Femur Medullary canal Off sets Version in lateral view Template the component Difficult to dislocate
• 7.
  Requirements for templating Standardradiograph in AP view Leg length Neck shaft Kohler’s line Acetabular coverage The lateral center-edge (CE) angle Femoral head extrusion index Acetabular inclination Acetabular version Acetabular depth Head sphericity & medulla of Femur Joint space width Ischial spine
• 8.
  Requirements for templating Standardradiographic views Antero posterior view Lowenstein lateral Dunn lateral Cross table view Internal rotation Femoral geometry Offset. External rotation RO Marker Groin medially
• 9.
  Femoral neck –head offset Cam deformity
• 10.
  Sequence of templating Acetabulum Femur Noimplant design or system… 100% A general knowledge of Components designs strengths weaknesses cost
• 11.
  Acetabular templating 40° ofAbduction Lateral bone coverage The medial border..ilioischial line Tear drop ACR Subchondral bone Inferior limit Protrusio Rim osteophytes Cement mantle Inclination,Version,Flush with native Acetabulum
• 12.
  Femoral templating (APview) Entry point Height of prosthetic head lengthening (short) shortening (long) Stem size proximal fitting or proximal coated distal fitting or fully coated Femoral offset increased decreased Femoral neck cut (width) valgus varus long short Distal centralizer plug size Depth of insertion Isthmus Cement mantle lateralization
• 13.
  Eccentric rasping Femoral perforation Noncircumferential cement mantle Entry point Femoral templating (lat. view)
• 14.
  Champagne flute FunnelCylindrical (Stovepipe) Osteoporotic Commonest Dorr. L.DProximal Femoral morphology Medial & posterior cortices
• 15.
  Acetabular components Cemented Liners /Polyethelenecup thin thick Subchondral bone Metal back Thick walled, all poly,a good subchondral bone 2-3mm cement mantle Un cemented Under size/eccentric stress centrally peripheral gap Oversize stress peripherally In growth metal shell Hydroxyapetite coated Poly liners Cross-linked polyethylene Alumina Ceramic-on-ceramic Metal-on-metal Postero-superior overhang
• 16.
  Offsets Vertical …25-50mm Horizontal ormedial modular neck modular head head diameter add skirt …32mm depth of insertion Anterior or version during implantation posterior bowing dual modular necks Femoral component
• 17.
  Femoral offset increase Reductionin Neck-shaft angle Medialization of the neck Abductor insufficiency
• 18.
  Rounded Rectangular neck Shorttaper Rounded increase range of motion. Neck & Morse taper
• 19.
  Femoral Acetabular impingement Nonskirted head Skirted head Range of motion Dislocation… jumping distance Poly debris
• 20.
  Femoral component Trapezoidal neck, without a skirt.Larger diameter head, Restoration of femoral neck offsets Affect polyethylene wear Abductor strength Limp (walking aids) Risk of postoperative dislocation Loosening of the components Short taper CPT
• 21.
  Algorithm for femoralcomponent selection
• 22.
  Algorithm for Acetabularcomponent selection
• 23.
  Thank you Best Wishes