Reaming means enlarging or shaping a hole by scraping material from its inner walls. The term applies across several fields, from metalworking to surgery, but the core idea is always the same: a rotating tool passes through a channel to widen it, smooth it, or prepare it for something that needs to fit inside. If you came across this word in a medical context, it most likely refers to a surgical technique used to prepare the inside of a broken bone for a stabilizing rod.
The General Meaning
In everyday and industrial use, reaming is the process of finishing a drilled hole to make it more precise. A reamer is a cutting tool with sharp flutes along its length. It spins inside an existing hole, shaving off thin layers of material to achieve an exact diameter and a smooth interior surface. Machinists ream holes in metal parts when a standard drill bit can’t deliver the tight tolerances needed for pins, bolts, or bearings to fit correctly.
You’ll also hear “reaming” used informally (and colorfully) to mean criticizing someone harshly, as in “my boss reamed me out.” That usage borrows from the aggressive, scraping nature of the tool.
Reaming in Bone Surgery
The most technical use of “reaming” is in orthopedic surgery, specifically a procedure called intramedullary nailing. When a long bone like the femur or tibia breaks, surgeons often stabilize it by inserting a metal rod (a “nail”) down the hollow center of the bone. Before the rod goes in, the inside of that canal needs to be widened so the rod fits snugly. That widening step is the reaming.
A long, flexible reaming instrument is fed into the bone’s marrow canal and rotated. It shaves away the inner lining of bone tissue, creating a channel that matches the diameter of the nail. The process is done incrementally, with the surgeon using progressively larger reamers until the canal reaches the right size.
Why Reaming Helps Bones Heal
Reaming does more than just make space. The bone shavings produced during the process act as an internal bone graft. These tiny fragments contain cells and proteins that actively stimulate new bone growth at the fracture site. Orthopedic surgeon Roy W. Sanders has described reamer-harvested bone as biologically identical in volume and consistency to grafts taken from the hip, which is traditionally considered the gold standard source.
Reaming also triggers a healing response in the outer layer of bone (the periosteum). When the inner blood supply is temporarily disrupted by the reamer, the bone compensates by boosting blood flow through its outer surface. This “periosteal reaction” stimulates new bone formation around the fracture.
The clinical results bear this out. A meta-analysis of controlled trials comparing reamed versus unreamed nailing for femur fractures found that reaming led to significantly faster healing, an 86% lower rate of nonunion (bones that fail to heal), and an 81% lower rate of delayed healing. Patients who had reamed nailing were also 75% less likely to need a second surgery.
What Happens Inside the Bone
The reaming process creates significant pressure changes inside the bone canal. Normally, blood flows inward through the bone wall toward the marrow. As the reamer advances and pressure builds, that flow reverses, pushing marrow contents outward into the bloodstream through the blood vessels near the ends of the bone.
This pressure reversal is the main source of the procedure’s primary risk: fat embolism. Small globules of marrow fat can enter the bloodstream and travel to the lungs or brain. Surgeons manage this risk by using smaller-diameter reaming instruments, which can reduce the pressure inside the bone by 61% to 66% compared to larger ones.
The internal blood supply of the bone takes time to recover. Studies show the marrow circulation returns to its pre-surgery levels at roughly 11 to 12 weeks after the procedure, which aligns with the typical bone-healing timeline.
Heat and Newer Reaming Technology
Friction from the spinning reamer generates heat inside the bone. If temperatures climb above about 47°C to 55°C (117°F to 131°F) for even a minute, the surrounding bone cells can die, a problem called thermal necrosis. This is why surgeons ream carefully and incrementally rather than aggressively enlarging the canal all at once.
A newer device called the Reamer-Irrigator-Aspirator (RIA) addresses both the heat and pressure problems simultaneously. It pumps saline solution into the bone canal during reaming to cool the tissue and applies suction to pull out marrow debris as it forms. This reduces fat embolism risk and prevents overheating. As a bonus, the bone material collected by the suction can be reused as graft material to fill bone defects elsewhere in the body, with less pain for the patient than harvesting a graft from the hip.
Flexible Versus Rigid Reamers
Reamers come in two basic designs. Rigid reamers are stiff, straight instruments that cut predictably but require the surgeon to position the limb at extreme angles to get a straight path into the bone. Flexible reamers bend to follow the natural curve of the bone canal, which makes them easier to use in tight spaces and less dependent on patient positioning. The tradeoff is that flexible reamers can be harder to aim precisely and, in rare cases, may break when cutting through very dense bone.
Both types are used in fracture repair and ligament reconstruction. In ACL surgery, for example, flexible reamers create longer tunnels in the femur and keep the drill path farther from nearby nerves and ligaments, while rigid reamers offer more control over tunnel placement.