Hohmann Retractor: Orthopaedic Bone Lever Sizes and Uses

The capsule is open, the femoral neck is exposed, and the assistant has to hold anterior soft tissue clear of the acetabular rim for the next twenty minutes without the tip skidding off bone. That single requirement — a tip that engages cortex and stays engaged — is the whole reason this instrument exists.

The Hohmann retractor is a lever, not a hook. It works by planting a narrow tip over the far cortex of a bone and using the bone itself as a fulcrum, so the blade lifts muscle and capsule out of the field with almost no pull on the surgeon’s hand. Understanding that mechanical difference is what stops people from ordering the wrong width and wondering why the tip keeps slipping.

Lever Mechanics: Why the Tip Shape Matters More Than the Blade

A conventional handheld retractor such as a Langenbeck or Volkmann distributes load across a broad blade and relies on the assistant’s arm to hold position. A bone lever inverts that. The tip is driven over the edge of the bone — around the femoral neck, over the acetabular rim, past the far tibial cortex — and the shaft is then levered against the near cortex. The soft tissue rides on the curved back of the blade.

The consequence: the tip carries the load, not the blade face. A 2 mm difference in tip width changes how the instrument behaves far more than a 10 mm difference in blade width. A tip that is too wide will not seat over a narrow neck and will ride up under tension. A tip that is too narrow on osteoporotic bone will punch through the cortex.

This is also why the bend angle is not cosmetic. Most patterns use a single bend of roughly 90 degrees between shaft and blade, but double-bend (offset) variants add a second bend that drops the handle away from the wound so the assistant’s hand is out of the surgeon’s line of sight. In a posterior hip approach with a deep wound, that offset is the difference between working comfortably and working around someone’s knuckles.

Blade Widths, Lengths and What Each Range Is For

Blade widths run from about 6 mm at the mini end to 70 mm on the widest acetabular patterns. Overall lengths cluster between roughly 150 mm and 260 mm. The table below maps the ranges we supply most often against where they actually get used.

Two practical notes on that table. First, the wide patterns above 40 mm are soft-tissue instruments — their tips are deliberately blunt and are meant to sit against bone rather than bite over it. Second, mini levers in the 6–8 mm range are frequently ordered in pairs, because small-fragment work almost always needs opposing retraction.

Pointed versus blunt tips

Pointed (sometimes called sharp or spiked) tips are for engaging over a cortical edge and holding under load. They are the default for femoral neck, tibial plateau and shaft work. Blunt tips are for bone surfaces where perforation is a real risk — osteoporotic acetabulum, paediatric bone, or anywhere the tip sits close to a neurovascular structure. The sciatic nerve behind a posterior acetabular rim is the classic reason surgeons specify blunt.

Narrow-neck and offset variants

Some patterns narrow the shaft immediately behind the blade so the instrument can pass through a small capsulotomy and then open into a full-width blade inside the joint. These are worth specifying for minimally invasive hip approaches, where the skin incision is the limiting dimension rather than the joint itself.

Placement in Hip, Knee and Trauma Exposures

In a posterior approach to the hip, a common configuration is one broad blunt lever over the anterior acetabular rim, one narrower pointed lever inferiorly under the transverse acetabular ligament, and a third over the posterior column. The anterior one carries most of the load and is the one that fails first if the width is wrong for the rim.

In total knee arthroplasty, a medium pointed pattern goes behind the tibia to protect the popliteal structures during the tibial cut, and a second lever holds the patella or extensor mechanism laterally. The behind-the-tibia lever is doing genuine protective work, not just exposure — a bent or blunted tip on that instrument is a safety issue rather than an inconvenience.

In diaphyseal trauma, levers are usually used in opposing pairs on either side of the fracture to lift the bone ends into the field for reduction and plating. If you are building a plating tray, the lever widths should be matched to the plate widths the tray supports; our guide to bone plate and screw instrumentation covers how the rest of that set fits together.

Steel Grade, Heat Treatment and Why Tips Bend

A bone lever is loaded in bending across its full length, which puts it in a different mechanical category from forceps or scissors. It needs stiffness and yield strength, not edge retention. We manufacture the standard patterns from martensitic stainless steel to AISI 420 (DIN 1.4021) conforming to ISO 7153-1, hardened and tempered to roughly 44–48 HRC through the shaft.

That hardness band is a deliberate compromise. Harder than about 50 HRC and the tip becomes brittle enough to chip when it is levered against cortical bone at an angle. Softer than about 42 HRC and the shaft takes a permanent set — the instrument comes back from theatre visibly bowed and never sits flat in the tray again. Permanent bowing after a handful of cases is the single most common quality complaint on cheap levers, and it is almost always an under-hardened shaft rather than a design fault.

Surface finish matters for a different reason. A satin or matt finish is standard on these instruments, partly to kill glare under theatre lights and partly because a bright mirror polish shows every scuff. Whichever finish you specify, the corrosion resistance comes from the passive chromium-oxide layer rather than the polish itself — see our explanation of passivation and corrosion resistance for why that distinction matters at reprocessing.

Inspection, Handling and Reprocessing

Three checks before an orthopaedic lever goes back into a set:

• Straightness. Lay the shaft on a flat surface. Any visible rock or gap means the shaft has yielded and the instrument should be withdrawn — a bowed lever transmits load unpredictably.
• Tip integrity. Look at the tip edge under magnification. Chips, rolled edges or flattening on a pointed tip all mean it will skid rather than engage.
• Marking legibility. Width and length markings live on the shaft and take abrasion from every cycle. If the tray depends on width markings for correct assembly, illegible marking is a set-integrity problem.

Reprocessing is unremarkable: enzymatic soak, brush the tip and any offset transition where bone debris collects, ultrasonic clean, rinse with deionised water and steam sterilise. Levers are heavy and should be laid flat in a bracketed tray rather than stacked loose, where they will batter lighter instruments during transport. If you are reviewing how a heavy orthopaedic set is loaded, our notes on autoclave loading patterns apply directly.

Specifying and Sourcing

When ordering, give four numbers rather than a pattern name alone: blade width in millimetres, overall length, tip style (pointed or blunt), and single or double bend. Pattern names for this family are inconsistent between catalogues, and “standard Hohmann” means different widths to different suppliers. The four numbers remove the ambiguity entirely.

Fizza Surgical manufactures the full width range in Sialkot under ISO 13485, CE marked, with material certificates traceable to the steel batch. The complete range sits in our bone surgery instrument catalogue, and our certifications page lists the current regulatory approvals. For related lever and elevator patterns used in spinal exposure, see the Cobb spinal elevator guide.