Fun with the Gun! – Workshop on Cementing technique

Dr Vaibhav BagariaMBBS, MS, FCPS

Origyn Health Care, Nagpur & Delhi

CARE Hospital, Nagpur

Cementing Synopsis Cement Basics Bone bed preparation - Clean bone bed Mixing & Delivery Pressurization - Good cement filling Safe working environment Expecting unexpected & dealing with it!

Cement – Other uses

Good Cementing Triangle

Cement - Basics

Two primary component – PMMA powder and a liquid monomer – MMA.

Mixed in ratio of 2 :1 to form PMMA cement.

To make it radioopaque: zirconium dioxide (ZrO2) or barium sulphate (BaSO4)

Contents

Powder (pouch)

Content Liquid (Ampoule)

Content

Polymer PMMA Monomer MMA

Starter BPO Initiator DmpT

Radiopacifier

ZrO2/BaSO4

Inhibitor HQ

Antibiotic

Colouring Agent

Chlorophyll

Process of Polymerization Four Phases: Mixing, Pickup, working and Final set.

Important Factors – temperature, humidity, type of mixing and type of cement.

Manual handling of the cement and body temperature will reduce the final setting time.

Variation in setting time over the cement’s shelf life can be minimized by storing the cement under the recommended conditions.

Different Types Low viscosity: Long-lasting liquid, or mixing phase, which makes for a short working phase. Requires strict adherence to application times but gives time for filling Delivery syringe

High viscosity: Short mixing phase, loose their stickiness quickly. Longer working phase, giving the surgeon more time for application.

Commercially available preparations

CMW1, 2, 3: Depuy Inc Palacos: Heraeus Medical

GmbH Simplex: Stryker Cobalt GV, HV Biomet cement:

Biomet Smart Set: Depuy

Different Types

Bone Bed Preparation

Effective micro-interlock between the bone - cement is essential.

Use of Pressure Pulse lavage and brush have shown to reduce the incidence of aseptic loosening.

Curettes, knives can be used but not as effective.

Bone Bed Preparation

Reaming Brushing Lavage Cement Restrictor Anchorage hole Key – To preserve the cancellous bone.

Aim – Good microlock

Reaming

Shape the femoral canal and acetabular cavity for even cement mantle.

Preoperative planning helps. Preserve the cancellous bone. Preserve the transverse acetabular ligament.

Pre Operative Plan Acetabular Reaming Femoral Reaming

Brushing and lavage Brushing – both acetabular and femoral reduce the loose cancellous bone and soft tissue.

High pressure pulse lavage produce clean surface. Also prevents circulatory changes.

Both reduce the risk of lamination in the cement that can decrease the strength of mantle by 8 -16%

Brushing

Pulse lavaging Canal

Brushing and Lavage

Cement Restrictor/Anchorage holes

5 -8; Improve fixation; Drilled or Impacted

For good filling and pressurization; Re-absorbable plugs also available

Mixing Entire liquid to polymer powder. Initial 30 sec – insufficient liquid. Hairy strands, glistening liquid. Strands no longer form, shine disappear, soft dough like consistency, can be scarped – beginning of working phase.

Vaccum Mixing -prevents air entrapment in cement, reduces cement porosity, unbounded particles - strength!

Vacuum Mixing

Delivery Hand packing – made into rough cylindrical mass and then packed.

Gun: ensures delivery under pressure. Inject the cement in retrograde fashion, letting the cement gun work its own way out of the femur.

Swedish Hip Registry has shown that retrograde cement filling using a cement gun in the femur reduces risk of revision.

Cement Gun

Pressurization Involves use of Cement Gun, special pressurizers, and centralizers.

Afford greater penetration into cancellous bone ensuring micro – lock.

Optimal viscosity is key to good pressurizing.

Femur -Marrow extrusion in the greater trochanter (the so-called sweating trochanter sign).

Pressurization

Pressurization-technique

Cement Other uses

Hip SpacerAntibiotic Beads

Knee SpacerTumor Cases

Safety First! Liquid monomer is highly volatile, flammable, powerful lipid solvent.

Avoid contact of the liquid with surgical gloves, skin or mucous membranes.

Fumes -irritation of the respiratory tract, eyes, liver; hypersensitivity, contact dermatitis.

Contact Lenses: reactions between monomer vapors and soft contact lenses.

Word of Caution! Premature insertion of bone cement -> drop in BP, arrhythmias or ischemia.

Expulsion of bone marrow –PE; esp Osteoporotic, NF # & overpressurization.

Inform Anaesthetist prior to cementing – Hypotensive episode lasts between 30 sec to 5 min.

Expecting the unexpected

“You can handle anything if you think you can. Just keep your cool and your sense of

humor."

Smiley Blanton

Work Shop

8 stations – 4 cement guns, 4 hand packing.

Both hand mixing and use of gun.

Allocate jobs – mixing, insertion of cement restrictor, cement delivery, pressurization.