Metzenbaum scissors are surgical scissors designed for cutting delicate soft tissue. The defining feature is the blade length to width ratio. The blades are long, thin, and narrow relative to the overall instrument length.
Blade length is typically 1.5 to 2.5 times the blade width. Compare this to Mayo scissors, where blade length is roughly equal to blade width. That ratio difference changes everything about how the scissors perform and what they can cut.
The scissors have a shank length that is shorter than the blade length on most patterns. The finger rings are proportionally larger than the blades, which gives the surgeon fine control with minimal hand force.
Total length ranges from 14 cm (5.5 inches) to 26 cm (10.25 inches). The most common lengths in general surgery are 18 cm and 20 cm. Pediatric surgeons use 14 cm. Cardiothoracic and thoracic surgeons use 23 cm and 26 cm for deep dissection.
The blades are thin. Typical blade thickness at the back edge is 1.2 mm to 1.8 mm for a 18 cm scissor. The cutting edge tapers to approximately 0.1 mm at the apex.
The blade cross section is flat on the inner surface and convex on the outer surface. This geometry allows the blades to slide past each other with minimal friction while maintaining edge contact along the entire cut.
Two blade shapes are available: straight and curved.
Straight blades cut in a direct line. They are used for superficial dissection where the target tissue is directly under the incision.
Curved blades have a curve along the blade axis. The curve is typically 15 to 30 degrees from the shank axis. The curve allows the surgeon to cut around corners or under tissue planes without repositioning the hand. Curved blades also improve visibility at the cut point because the surgeon's hand is not blocking the line of sight.
Curved Metzenbaum scissors are more common than straight. Many surgeons never order straight Metzenbaums. Some surgical instrument sets include both, but the curved pattern is the default.
The tip style is blunt on both blades. Blunt means the tip has a rounded or slightly flattened shape rather than a sharp point. The blunt tip reduces the risk of puncturing unintended structures during blind dissection. The surgeon spreads the closed tips to separate tissue planes. A sharp point would tear or puncture.
Some manufacturers offer a semi-blunt or slightly pointed tip for specific applications like dissecting around blood vessels. These are not standard Metzenbaum scissors. They are a variant often called Metzenbaum-type or Metzenbaum-style scissors.
The two blades join at a box joint or screw joint.
Box joint is the traditional construction. One blade has a rectangular tab that fits into a rectangular recess in the other blade. A pin passes through both. The joint distributes force across a larger area than a simple screw joint. Box joints stay tight longer and resist loosening during use.
Screw joint uses a single screw and nut. This is cheaper to manufacture and easier to adjust. The screw can loosen during use. Some surgeons prefer screw joints because they can adjust tension with a small wrench during a procedure. Most hospitals prefer box joints because they require less maintenance.
The joint tension determines cutting efficiency. Too loose, and the blades separate instead of shearing. Too tight, and the hand fatigues quickly and the blades bind. Correct tension allows the scissors to fall open slightly under their own weight when held vertically, but not so loose that they swing freely.
Metzenbaum scissors are made from martensitic stainless steel. The specific grade varies by manufacturer and price point.
Grade 410 stainless steel is the minimum acceptable. It contains 11.5% to 13.5% chromium and 0.15% carbon. Hardness after heat treatment is 38 to 42 HRC. This grade is common in lower-priced scissors. It holds an edge reasonably well but corrodes if not dried properly after sterilization.
Grade 420 stainless steel is the industry standard for quality surgical scissors. Chromium content is 12% to 14%. Carbon content is 0.15% minimum, up to 0.40% in some formulations. Hardness ranges from 48 to 55 HRC. Grade 420 holds a sharper edge and resists corrosion better than 410.
Grade 440C stainless steel is used in premium scissors. Chromium is 16% to 18%. Carbon is 0.95% to 1.20%. Hardness reaches 58 to 60 HRC. Edge retention is excellent. Corrosion resistance is superior to 420. The downside is brittleness. 440C can chip if dropped or used on hard material. It also costs significantly more.
Some manufacturers use proprietary steel alloys. These are variations of the 400 series with small additions of vanadium, molybdenum, or niobium to refine grain structure and improve edge retention. The clinical difference between a good 420 steel and a proprietary alloy is small. Marketing claims exceed actual performance differences in most cases.
The manufacturing sequence for reusable Metzenbaum scissors:
Forging or stamping the blank from bar stock. Forging produces stronger grain structure. Stamping is cheaper but introduces internal stresses.
Annealing to soften the steel for machining.
Milling the blade geometry. This includes cutting the blade profile, grinding the inner flat surface, and cutting the screw or box joint features.
Heat treatment: austenitizing at 980 to 1060 degrees Celsius, quenching in oil or air, then tempering at 150 to 350 degrees Celsius to achieve final hardness.
Grinding the cutting edge. This is done on wet belt grinders with progressively finer grits. Final edge is finished on a felt wheel with polishing compound.
Passivation: soaking in a nitric or citric acid bath to remove free iron from the surface. This forms a chromium oxide layer that resists corrosion.
Assembly and tensioning.
Final inspection and sharpness testing.
No single universal sharpness standard exists for surgical scissors. Different manufacturers use different test methods.
The most common test method uses a synthetic test material with known cutting resistance. The material is typically a silicone rubber or polyurethane sheet of specified thickness and durometer. The scissors must cut through the material cleanly for a specified distance without tearing or hanging.
Another test uses a stack of surgical gauze or suture material. The scissors must cut through a specified number of layers with a specified closing force.
Some quality systems use a sharpness gauge that measures the force required to cut a standard test filament. Force is measured in grams or newtons. Acceptable range varies by scissor type. For Metzenbaum scissors, cutting force below 50 grams is considered very sharp. Above 100 grams is dull and should be rejected.
AAMI (Association for the Advancement of Medical Instrumentation) has guidance documents on scissor sharpness testing, but these are not mandatory standards. They are recommended practices.
Most hospitals do not perform quantitative sharpness testing. They rely on qualitative inspection: the scissors should cut a single layer of surgical gauze without pulling or tearing. If they snag or require multiple tries, they are dull.
The primary use of Metzenbaum scissors is blunt dissection in soft tissue planes.
The technique: insert the closed scissors into a tissue plane. Open the blades to spread the tissue apart. This separates fascial layers or loosens adhesions without cutting. Then close the blades partially and advance them to cut any remaining connective tissue bridges.
The scissors cut only when closed. The cutting action occurs at the point where the blades cross. This point moves from the joint toward the tips as the scissors close. The surgeon controls the length of cut by controlling how far the blades close.
Metzenbaum scissors are never used to cut:
Suture material of any kind
Surgical drains (latex, silicone, or rubber)
Gauze or any fabric
Heavy fascia
Muscle
Cartilage
Bone
Wire sutures or surgical steel
Any plastic or metal implant material
Adhesive tape or dressings
Cutting any of these materials dulls the blades immediately. A single cut through a silk suture can leave a visible nick in the cutting edge. That nick creates a gap between the blades. The gap causes tissue to slip between the blades instead of being cut. The scissors become useless for their intended purpose.
Some surgeons ignore this rule. They cut a quick suture with the Metzenbaums because the suture scissors are on the other side of the drape. Those surgeons are the reason OR managers order replacement scissors every 6 months instead of every 3 years.
After use, the scissors go through a cleaning process before sterilization.
Point of use treatment happens in the OR. The scrub nurse wipes visible debris from the scissors with a damp sponge. The scissors are placed in a container of enzymatic detergent or water to prevent drying of organic material. Blood and tissue that dry onto the instrument are difficult to remove later.
Transport to central sterile processing. The scissors are kept moist during transport. Dried material requires manual scrubbing.
Manual cleaning: the scissors are fully opened and scrubbed with a soft brush and neutral pH detergent. The box joint and serrations (if any) receive extra attention. The cleaning person uses a brush with bristles that fit into the joint space.
Automated cleaning: the scissors are placed in an instrument washer with appropriate detergents and rinse cycles. The washer must have a cycle that reaches 70 degrees Celsius for at least one minute to denature proteins. Some washers use ultrasonic cleaning for the first stage. Ultrasonic cleaning is effective for removing material from joints and crevices.
After cleaning, the scissors are inspected for visible soil. Any remaining soil sends them back through cleaning.
Rinsing must be thorough. Detergent residue causes corrosion and can irritate tissue if not removed.
Drying is done with clean, lint-free cloths or heated drying cabinets. Air drying promotes water spots and corrosion.
Metzenbaum scissors tolerate most sterilization methods.
Steam sterilization (autoclave) is the most common. Typical cycle: 121 degrees Celsius at 15 psi for 15 to 20 minutes for gravity displacement. Pre-vacuum cycles: 132 to 135 degrees Celsius for 4 to 5 minutes. The scissors must be fully open during sterilization to allow steam contact with all surfaces. Closed scissors may not get steam into the joint space, leaving that area non-sterile.
Ethylene oxide (EtO) sterilization is used for scissors that cannot tolerate steam heat, but Metzenbaum scissors can tolerate steam. EtO adds cost and cycle time. No advantage for this instrument.
Hydrogen peroxide plasma (Sterrad) is acceptable. Cycle times are shorter than EtO and there are no toxic residues. Some low-temperature plasma systems require specific packaging materials.
Dry heat sterilization is acceptable but slow. Typical cycle: 160 to 170 degrees Celsius for 60 to 120 minutes. Dry heat does not corrode scissors the way steam can, but cycle times are long.
The sterilization method affects corrosion risk. Steam cycles with impure water leave mineral deposits. These deposits create galvanic corrosion cells. Use distilled or reverse-osmosis water for steam generators to minimize this risk.
Each scissor is inspected after cleaning and before sterilization.
Visual inspection with magnification (2x to 5x) or a lighted magnifier:
No rust, pitting, or discoloration
No cracks at the box joint or screw hole
No bent or warped blades
No burrs on the cutting edges
No nicks or chips in the cutting edges
Tip condition: both tips intact, no hooks or bends
Surface finish: no scratches that could trap soil
Screw or pin: tight, no wobble
Functional inspection:
Open and close the scissors several times. Motion should be smooth.
No grinding or binding at any point in the range.
Blades should contact each other along the entire cutting edge when closed.
No gap between the blades visible against a light source.
Tip alignment: tips should meet precisely, not cross over or leave a gap.
Tension test: hold the scissors by one ring. The other blade should fall open slightly under its own weight. If it does not move, the joint is too tight. If it swings freely, the joint is too loose.
Sharpness test: cut a single layer of surgical gauze or a test material. The cut should be clean with no tearing. The scissors should cut with light hand pressure. If they require force or the gauze tears, the scissors are dull.
The only routine maintenance is tension adjustment and lubrication.
Tension adjustment for screw joint scissors: use a small wrench or pliers designed for instrument repair. Turn the screw incrementally. Check tension after each quarter turn. Over-tightening damages the threads or the blade.
Tension adjustment for box joint scissors: tap the pin slightly to increase tension. This requires a pin punch and small hammer. Most hospitals do not perform this adjustment in-house. They send the scissors to a repair vendor.
Lubrication: water-soluble instrument lubricant is applied after cleaning and before sterilization. Do not use oil-based lubricants. Oil interferes with steam penetration and leaves residue. Water-soluble lubricants evaporate or rinse away during sterilization.
Sharpening is controversial. Each sharpening removes metal from the cutting edge. After 3 to 5 sharpenings, the blade geometry changes enough that the scissors no longer function properly. The inner flat surface no longer contacts the opposite blade correctly. Gap develops.
Some hospitals never sharpen Metzenbaum scissors. They use them until dull, then discard and replace. This is cost-effective for medium-priced scissors ($50 to $80). Premium scissors ($150 to $200) may be worth sharpening once or twice.
Sharpening requires specialized equipment: a sharpening machine with guides that maintain the correct blade angle. Hand sharpening with a stone is not acceptable. The angle must be consistent across the entire edge.
Vendors who offer scissor sharpening services typically charge $5 to $15 per scissor. They also replace loose screws, adjust tension, and passivate the surface.
Replace Metzenbaum scissors when:
The blades have a visible gap when closed
The cutting edges have nicks or chips larger than 0.5 mm
The tips are bent or broken
The box joint is loose and cannot be tightened
The scissors have been sharpened 4 or more times
There is pitting corrosion that cannot be removed
The scissors fail the gauze cutting test after cleaning and adjustment
Expected useful life depends on quality and care:
Economy grade (410 steel, stamped): 50 to 100 uses
Standard grade (420 steel, forged): 200 to 500 uses
Premium grade (440C, precision forged): 500 to 1000 uses
Poor care cuts these numbers in half. Cutting sutures reduces life to one use.
Prices as of 2025 for reusable Metzenbaum scissors:
Economy: $25 to $45 per scissor
Standard (major brands like Sklar, Miltex, Week): $60 to $110
Premium (Aesculap, KLS Martin, Scanlan): $150 to $250
German or Pakistani imported (no brand): $15 to $30
Single-use Metzenbaum-style scissors:
$2 to $8 per unit
Sold sterile, individually wrapped
Material: typically 410 or 420 steel, sometimes lower grade
Not intended for reuse. Do not attempt to clean and resterilize.
Cost per use calculation for reusable:
Assume $80 purchase price, 400 uses, $5 per sharpening at 200 uses (one sharpening), $0.50 per sterilization cycle.
Total cost: $80 + $5 + (400 x $0.50) = $285
Cost per use: $285 / 400 = $0.71
Compare to single-use at $4 per unit: $4.00 per use.
Reusable is cheaper after approximately 20 uses. The break-even point varies by local reprocessing costs.
FDA (United States): Product Code LRW (Scissors, General, Surgical). Regulation number 21 CFR 878.4820. Class I device, generally exempt from premarket notification (510(k)) except for scissors with specific claims or features.
Most Metzenbaum scissors are Class I, exempt. No 510(k) submission required for basic design. Manufacturers must still register and list the device, follow quality system regulation (21 CFR 820), and report adverse events.
EU: Class I (non-sterile, no measuring function) or Class I sterile (if sold sterile). Under EU MDR 2017/745, reusable surgical instruments are Class I. Notified body involvement required only for sterile versions or instruments with measuring function. Metzenbaum scissors have no measuring function.
UK: Same classification after Brexit. UK MDR 2002 as amended.
Canada: Class I under Medical Devices Regulations SOR/98-282. Not required to obtain a license. Must have establishment license.
What a hospital buyer should specify in a request for proposal:
Steel type: 420 stainless minimum, 440C preferred
Hardness: 48 to 55 HRC for 420, 55 to 60 HRC for 440C
Construction: forged preferred over stamped
Joint type: box joint preferred
Blade shape: curved (specify degrees) or straight
Length: 14, 18, 20, 23, or 26 cm
Tip style: blunt (standard)
Surface finish: satin or mirror
Passivation: yes, per ASTM A967
Corrosion resistance test: pass per ASTM F1089
Sharpness test method: specify method and acceptable force range
Tensile strength of joint: minimum force to separate (ASTM F1079)
Sterilization compatibility: steam, EtO, hydrogen peroxide plasma
Warranty: against defects, typically 1 year
Expected useful life in cycles: vendor should provide data
Dull edge from normal use or misuse on sutures. Most common failure. Solution: sharpen or replace.
Loose joint. Second most common. Solution: adjust tension. If box joint pin cannot be tightened, replace.
Corrosion at the joint or on the blade faces. Caused by incomplete drying, saline residue, or damaged passivation layer. Solution: remove rust with abrasive if superficial. If pitted, replace.
Cracked blade at the joint. Caused by over-tightening or metal fatigue. Solution: replace. Cracked blades can break during surgery.
Bent tip. Caused by dropping or using as a retractor. Solution: straighten if minor. Replace if severe.
Gap between blades. Caused by uneven sharpening or worn joint. Solution: if from sharpening, replace. If from joint wear, replace.
Mayo scissors: shorter, wider blades. Cut heavy tissue, muscle, fascia. Can cut sutures in emergency. Not for delicate dissection.
Spencer scissors: longer, thinner than Mayo but shorter than Metzenbaum. Sometimes called suture scissors. Blunt-blunt tips. Originally designed for cutting sutures. Do not use on tissue.
Iris scissors: very small, 10 to 12 cm total length. Fine tips, often sharp-sharp. Used in ophthalmology and microsurgery. Not for general dissection.
Tenotomy scissors: similar to Metzenbaum but smaller. Often have a small hook on one blade. Used in tendon surgery and plastic surgery.
Operating scissors (general purpose): heavy, short blades. Can cut a wider range of materials. Not as precise as Metzenbaum for delicate work.
Use Metzenbaum scissors only for soft tissue dissection. Do not cut sutures, drains, gauze, or heavy tissue. Clean immediately after use. Dry thoroughly before storage. Inspect before each sterilization. Test sharpness on gauze. Replace when dull or damaged. Do not sharpen more than 3 times. Do not use bent or cracked scissors. Do not drop.