Please explain about orthopaedics implants with images

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Please explain about orthopaedics implants with images

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AAOS orthopedic implants internal fixation patient information

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orthopedic implants internal fixation plates screws intramedullary nail external fixator diagram

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What are orthopaedic implants?

Orthopaedic implants are devices placed in or around bone and joints to restore alignment, stability, movement, or joint function. They may be used temporarily while a fracture heals, or intended to remain long term, such as a hip or knee replacement.

For fracture surgery, the usual sequence is:

Reduce the fracture, meaning reposition the bone fragments.
Fix the fragments with an implant.
Protect the repair while bone healing occurs.

The implant should be strong enough to maintain alignment but selected and positioned to preserve blood supply and support healing. Rockwood and Green's Fractures in Adults, p. 23.

Main fracture-fixation implants

1. Plates and screws

A plate works like an internal splint along the surface of a bone. Screws attach it to bone and can also compress simple fracture fragments together.

$Forearm fracture stabilized with a plate and screws$

Common uses

Forearm, clavicle, ankle, wrist, and many fractures near joints
Some complex fractures where accurate restoration of the joint surface is needed

Important variants

Conventional compression plates: can squeeze the plate against bone and generate compression across a fracture.
Locking plates: screws lock into the plate, producing a fixed-angle construct. They are particularly useful in osteoporotic bone and fractures near joints.
Bridge plates: span a comminuted zone without trying to attach every small fragment.

Advantages: precise fracture alignment, strong fixation, useful near joints.
Limitations: requires surgical exposure; the plate can occasionally irritate overlying tendons or skin.

2. Screws alone

Screws may be used without a plate when a fracture has a suitable simple pattern, such as an oblique fracture fragment or certain ankle, hip, and wrist fractures.

$Ankle fracture treated with plates and screws$

Types include

Cortical screws for dense outer bone
Cancellous screws for softer, spongy bone near the ends of long bones
Cannulated screws, placed over a guidewire for accurate positioning
Lag screws, designed to compress two bone fragments together

Screws are the most frequently used internal-fixation implant and can be used alone or in combination with plates, nails, or rods, as described by AAOS patient guidance.

3. Intramedullary nails or rods

An intramedullary nail is inserted into the marrow canal in the center of a long bone. Locking screws at each end prevent rotation and shortening.

$Tibial fracture treated using an intramedullary nail$

Common uses

Femoral shaft fractures
Tibial shaft fractures
Humeral shaft fractures
Some fractures around the hip

Advantages

The implant lies close to the bone's mechanical axis.
It often permits earlier mobilization than prolonged casting.
It can be inserted through relatively small incisions compared with many plates.

Limitations

Not suitable for every fracture pattern.
May cause pain around the entry point.
Nail or locking-screw breakage can occur if bone union is delayed.

4. Wires, pins, and K-wires

Thin metal wires or pins stabilize small or difficult-to-fix fragments. They may be left below the skin or temporarily protrude through the skin for later removal.

$Childhood elbow fracture held with temporary pins$

Common uses

Pediatric elbow fractures
Hand and foot fractures
Small bone fragments
Temporary stabilization during surgery

Because a pin that exits the skin can allow bacteria to track inward, good pin-site care and follow-up are important.

5. External fixators

An external fixator uses pins or wires inserted into bone and connected to bars or circular rings outside the body.

$Circular external fixation with an intramedullary nail in a femur fracture$

When it is used

Severe open fractures
Major soft-tissue damage or contamination
Polytrauma, when quick stabilization is necessary
Infection, bone loss, deformity correction, or limb lengthening
As temporary fixation before a later definitive operation

It is especially helpful when extensive internal surgery would be unsafe initially. Pin-site infection, pin loosening, stiffness, and inconvenience are potential downsides.

Implants beyond fracture fixation

Implant group	Examples	Purpose
Joint-replacement implants	Total hip, knee, shoulder arthroplasty	Replace damaged joint surfaces in arthritis, fracture, or failed prior surgery
Spinal implants	Pedicle screws, rods, cages, plates	Stabilize the spine after trauma, deformity, instability, or selected degenerative conditions
Sports-medicine implants	Suture anchors, interference screws, buttons	Reattach tendons or ligaments, for example in rotator-cuff repair or ACL reconstruction
Bone-reconstruction implants	Rings, bone transport frames, porous augments	Treat bone loss, deformity, difficult nonunion, or revision joint replacement

Implant materials

Most trauma implants are made of:

Stainless steel
Titanium or titanium alloys
Cobalt-chromium alloys, commonly used in many joint-replacement components
Tantalum, a porous metal sometimes used where bone ingrowth is desired
In selected procedures, bioabsorbable polymers

Modern fracture implants are commonly stainless steel or titanium-based. Nickel is present in some metal implants, so a patient with a known nickel allergy should tell their orthopaedic surgeon. Campbell's Operative Orthopaedics, 15th ed., section “Biomaterials of Fracture Fixation.” AAOS also notes that true implant allergy is uncommon but should be discussed before surgery in its internal-fixation overview.

Do implants need to be removed?

Usually, not routinely. Many plates, screws, and nails can remain safely after bone healing. Removal may be considered if there is:

Persistent implant-related pain or tendon irritation
Infection
Implant breakage or loosening
Prominent hardware under thin skin
A problem that requires revision surgery
A temporary pin or wire intended for removal

Removing an implant is another operation and has risks, so the decision is individual.

Potential complications

Complications are uncommon but important:

Surgical-site or deep implant infection
Delayed union, nonunion, or malunion
Implant loosening, bending, or breakage
Injury to nearby nerves, vessels, tendons, or joints
Stiffness, pain, and scar-related problems
Blood clots after lower-limb or major surgery
Metal sensitivity, which is relatively rare

Seek prompt medical advice after orthopaedic surgery for fever, increasing wound redness or discharge, worsening pain, new numbness, a cold/pale limb, calf swelling, or sudden breathlessness.

Different types of plates and screws and where are they used

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Orthopaedic plates and their uses

A plate is fixed to the outer surface of a bone with screws. Its function depends on the fracture pattern: it may compress two pieces together, support a joint fragment, protect screw fixation, or bridge a shattered area.

$Dual plating of a complex distal femur fracture: lateral locking plate plus medial T-buttress plate$

Plate type	Main purpose	Typical uses
Dynamic compression plate (DCP)	Compresses a simple fracture when screws are inserted eccentrically in special oval holes	Simple transverse or short-oblique shaft fractures of humerus, radius, ulna, femur, or tibia
Limited-contact DCP (LC-DCP)	A DCP with reduced contact against bone, intended to lessen disruption of blood supply beneath the plate	Similar shaft-fracture applications, especially where biological fixation is preferred
Locking compression plate (LCP)	Screw heads lock into threaded plate holes, creating a fixed-angle construct	Osteoporotic bone, fractures near joints, periarticular fractures, comminuted fractures, distal radius, proximal humerus, distal femur, proximal tibia
Anatomical or pre-contoured plate	Shaped to fit a particular bone region	Clavicle, distal radius, proximal humerus, distal femur, proximal tibia, distal fibula, pelvis
Buttress plate	Prevents a fragment from collapsing or sliding, particularly under shear force	Tibial plateau, distal radius, posterior malleolus, medial femoral neck, acetabulum
T-plate / L-plate	A buttress-type plate with a broad end that captures a metaphyseal or joint fragment	Distal radius, distal humerus, proximal tibia, selected ankle and foot fractures
Neutralization plate	Protects an interfragmentary lag screw from bending, torsion, and shear	Oblique or spiral shaft fractures, commonly forearm and selected tibial/femoral fractures
Bridge plate	Spans a comminuted zone without stripping or fixing every small fragment	Comminuted fractures of femur, tibia, humerus, clavicle, and some periarticular fractures
Reconstruction plate	Highly bendable in several planes because of notched edges	Pelvis, acetabulum, clavicle, distal humerus, and other irregular surfaces
One-third tubular plate	Thin, narrow, easily contoured plate	Lateral malleolus, small bones of foot/hand, and as an antiglide plate in selected ankle fractures
Hook plate	Hook captures a small bony fragment or passes beneath an adjacent structure	Distal clavicle, selected acromioclavicular injuries, and small avulsion fragments
Blade plate / dynamic condylar screw plate	Fixed-angle device with a blade or large lag screw into the bone end	Selected proximal or distal femoral fractures and corrective osteotomies. Used less often in some settings because locking plates and nails are alternatives
Minifragment plates	Small plates and screws for small bones/fragments	Hand, foot, distal radius, radial head, olecranon, facial and selected pediatric applications

Key concept: locking vs non-locking plates

Non-locking plate: the screw pulls the plate against the bone. Stability depends heavily on screw grip and friction between plate and bone.
Locking plate: the screw threads into the plate as well as bone. The plate and screws act as one fixed-angle frame. This is particularly helpful in weak osteoporotic bone and short fragments near a joint.

The AO Foundation plate reference explains that reconstruction plates can be contoured in multiple planes and can accept cortical, metaphyseal, and locking screws. A plate can be used in compression, neutralization, or bridge mode depending on the fracture.

Types of orthopaedic screws and their uses

Basic components and measurements of an orthopaedic bone screw

Screw type	Design	Main uses
Cortical screw	Fine threads, relatively small thread depth, designed for dense cortical bone	Shaft of long bones, plate fixation in diaphysis, forearm and tibial shafts
Cancellous screw	Coarse, deeper threads for grip in softer spongy bone	Metaphysis and epiphysis, such as proximal humerus, tibial plateau, calcaneus, femoral neck, and malleoli
Partially threaded cancellous screw	Smooth shaft near the head and threads distally	Used as a lag screw to compress two fracture fragments together
Fully threaded cancellous screw	Threads along the full length	Positional fixation where compression or collapse must be limited, selected pelvic and metaphyseal applications
Lag screw	This is a function rather than a unique screw type. The near fragment glides and the far fragment is threaded, drawing fragments together	Simple oblique or spiral fractures, malleolar fractures, condylar or articular fragments
Cannulated screw	Hollow center, inserted over a guidewire	Femoral neck fractures, slipped capital femoral epiphysis, scaphoid fractures, ankle fractures, pelvic fixation
Headless compression screw	Buried screw with no prominent head, often variable-pitch to create compression	Scaphoid, radial head, capitellum, small joint and intra-articular fractures
Locking screw	Threaded head locks into a locking plate	Locking plate constructs, especially in osteoporotic bone or near joints
Non-locking plate screw	Head presses plate to bone	Conventional DCP and neutralization/compression plate constructs
Pedicle screw	Large, strong spinal screw placed through the vertebral pedicle	Spinal fusion for trauma, deformity, instability, infection, or selected degenerative conditions
Interference screw	Fixes a graft inside a bone tunnel	ACL and other ligament reconstruction
Suture anchor	Screw-like or plug-like implant with attached suture	Rotator-cuff repair, shoulder instability surgery, tendon/ligament reattachment

Common examples by body region

Region	Often used implant
Clavicle	Pre-contoured locking or non-locking clavicle plate
Proximal humerus	Proximal humeral locking plate with locking screws
Forearm shaft	Compression or neutralization plate with cortical screws
Distal radius	Volar locking plate with locking screws
Femoral neck	Cannulated cancellous screws, or a dynamic hip screw in selected patterns
Intertrochanteric hip	Dynamic hip screw with side plate, or an intramedullary nail
Distal femur	Anatomical distal femoral locking plate, occasionally dual plating for complex fractures
Tibial plateau	Lateral or medial buttress/locking plate, often with lag screws for joint fragments
Tibial shaft	Intramedullary nail is common; bridge plate in selected fractures
Ankle	One-third tubular or locking fibular plate, cortical screws in shaft, cancellous/lag screws for malleolar fragments
Foot and hand	Minifragment plates, small cortical screws, headless compression screws, or K-wires

Practical points

The same plate can serve different roles. For example, an LCP can be used as a compression, neutralization, or bridge plate depending on screw placement and fracture pattern.
Plates and screws are chosen based on fracture location, bone quality, soft-tissue injury, whether the fracture enters a joint, infection risk, and the patient’s rehabilitation needs.
A screw crossing a fracture may act as a lag screw only when the near fragment can glide and the threads grip the far fragment, producing compression. Campbell's Operative Orthopaedics, 15th ed., “Screw Fixation.”
More hardware is not always better. In a comminuted fracture, excessive exposure and fixation of every small fragment can damage the blood supply needed for healing.

What is a locking screw and non-locking screw? Cancelous screw and cortical screw. Locking compression plate and no- No, this DCP. Please explain with images. Please explain with images.

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AO Foundation locking compression plate locking screw DCP cortical cancellous screw difference

First, the big picture

These terms describe two separate things:

Screw design: locking vs non-locking, cortical vs cancellous
Plate design: LCP vs DCP

A screw can be:

Locking or non-locking based on how its head relates to the plate
Cortical or cancellous based on its thread design and the type of bone it grips

So, for example, a cortical locking screw is possible.

1. Locking screw vs non-locking screw

Locking screw

A locking screw has threads on its head that engage matching threads in a locking plate hole.

Locking screw construct

  Plate with threaded hole
       ┌─────────┐
       │  /////  │  ← screw head locks into plate
       └────┬────┘
            │
            │ screw
          ┌─┴─┐
          │bone│

How it works

The screw locks to the plate.
The plate and screws behave as a single fixed-angle frame.
The plate does not need to be tightly pressed against bone to be stable.
It is very useful when normal screw grip in bone may be poor.

Common uses

Osteoporotic bone, especially in elderly patients
Fractures near a joint where the fragment is short
Distal radius fractures
Proximal humerus fractures
Distal femur fractures
Proximal tibia/tibial plateau fractures
Comminuted fractures treated by bridge plating

Locking plate construct in the proximal humerus, with a cortical screw initially positioning the plate

Key point

A locking screw gives angular stability. It does not primarily depend on squeezing the plate onto the bone.

Non-locking screw, conventional screw

A non-locking screw has a smooth, non-threaded undersurface of its head. It passes through a plate hole but does not thread into the plate.

Non-locking screw construct

       Plate
    ┌─────────┐
    │    O    │ ← smooth plate hole
    └────┬────┘
         ▼
  Screw head presses plate
  firmly against bone

How it works

As the screw is tightened, its head pulls the plate against the bone.
Stability relies on:
- Screw grip in the bone
- Friction between plate and bone
- Good plate contouring to bone

Common uses

Good-quality bone
Conventional compression plating
To bring a plate closer to bone before inserting locking screws
Simple fracture patterns that need compression

Important difference

Feature	Locking screw	Non-locking screw
Screw head threads into plate?	Yes	No
Plate must contact bone tightly?	Not necessarily	Yes
Main stability	Fixed-angle plate-screw frame	Bone screw grip plus plate-bone friction
Best use	Osteoporotic bone, short fragments, periarticular fractures	Good bone quality, compression/standard plating
Can compress plate onto bone?	No, not by itself	Yes

A surgeon may use both types in one LCP construct. For example, a non-locking cortical screw can first pull the plate to bone, then locking screws can provide fixed-angle stability.

2. Cortical screw vs cancellous screw

The terms cortical and cancellous refer mainly to the screw's thread pattern and the bone in which it is intended to obtain grip.

Cortical screw

A cortical screw is designed for dense outer bone, called the cortex.

Cortical screw
Fine, closely spaced threads

    /\/\/\/\/\/\/\/\/\/\/\
    ↑ fine thread pitch

Features

Fine threads
Threads close together
Usually fully threaded
Designed to grip the dense cortical shell of bone

Usual locations

Shaft, or diaphysis, of long bones
Radius and ulna shafts
Humeral shaft
Tibial shaft
Fibular shaft
Securing a plate to a long-bone shaft

Cancellous screw

A cancellous screw is designed for softer, spongy inner bone, called cancellous or trabecular bone.

Cancellous screw
Deep, widely spaced threads

    /     /     /     /     /
    ↑ coarse, deep thread pitch

Features

Larger, deeper threads
Greater spacing between threads
Often partially threaded
Better grip in softer metaphyseal or epiphyseal bone

Usual locations

Near the ends of long bones
Femoral neck and head
Tibial plateau
Calcaneus
Proximal humerus
Malleoli around the ankle
Some pelvic fractures

Partial-thread cancellous screw as a lag screw

A partially threaded cancellous screw can generate compression across a fracture.

Screw head      Smooth shaft         Threads grip far fragment
   [O]==============|====================///////
          Near fragment slides       Far fragment is pulled closer

This is commonly used for:

Medial malleolus fracture
Lateral femoral-neck fracture fixation
Tibial plateau articular fragments
Some calcaneal and condylar fractures

Cortical vs cancellous screw

Feature	Cortical screw	Cancellous screw
Bone type	Dense cortical bone	Softer spongy bone
Thread	Fine, shallow, close together	Coarse, deep, widely spaced
Common region	Shaft of long bone	End of long bone, near joint
Typical role	Plate fixation in shaft	Fixation or compression of metaphyseal/articular fragment
Common example	3.5 mm cortical screw in radius shaft	6.5 mm cancellous screw in femoral neck

The screw's design influences fixation, but the surgeon chooses the exact screw diameter, length, number, and direction based on imaging, fracture pattern, bone quality, and nearby joints, nerves, and vessels.

3. LCP: Locking Compression Plate

LCP means Locking Compression Plate.

It is called “locking compression” because its holes may accept either:

a locking screw, or
a conventional non-locking screw.

Many LCPs have a combi-hole:

LCP combi-hole

 ┌───────────────────┐
 │ Compression  Locking │
 │   portion    threaded│
 │      ◁          ○    │
 └───────────────────┘

What it can do

An LCP may be used as:

A compression plate for a simple fracture
A neutralization plate to protect lag screws
A bridge plate across a comminuted area
A buttress plate to resist collapse or shear near a joint
A fixed-angle implant in osteoporotic bone

Advantages

Strong angular stability
Helpful in weak bone
Helpful when the fracture is near a joint
Can be inserted with less contact against the bone in selected bridge-plating constructs
Can accept a mixture of locking and non-locking screws

Limitation

Locking hardware is not automatically better for every fracture. Correct reduction, plate position, plate length, working length, and appropriate screw pattern matter as much as the implant type.

4. DCP: Dynamic Compression Plate

DCP means Dynamic Compression Plate. It is a conventional, non-locking plate designed mainly to generate compression across a simple fracture.

DCP hole

      Oval hole with sloping side
       ___________
      /           \
     |    O        |  ← screw inserted eccentrically
      \______/----/
             ↑
     sloped shoulder produces sliding

When a conventional screw is inserted eccentrically in the DCP's oval hole and tightened, the screw head slides down the slope of the hole. This moves the bone segment toward the fracture and creates axial compression.

Before tightening                After tightening

 Bone A   fracture   Bone B      Bone A|Bone B
 ======      gap      =====      ======||=====
 [plate]                     →   Compression across fracture

Main uses

Simple transverse fractures
Short-oblique fractures
Diaphyseal or shaft fractures with good bone contact
Radius and ulna shaft fractures
Selected humeral and tibial shaft fractures

Limitations

Needs good plate-to-bone contact
Depends on adequate conventional screw grip in bone
Less ideal when bone is severely osteoporotic or the fracture is highly comminuted

5. LCP vs DCP

Feature	LCP	DCP
Full name	Locking Compression Plate	Dynamic Compression Plate
Screw type	Locking screws, non-locking screws, or both	Conventional non-locking screws
Locking interface	Screw head threads into plate	No screw-plate locking
Main stability	Fixed-angle construct	Plate pressed against bone by screws
Can produce compression?	Yes, if conventional screws are placed in compression mode	Yes, its primary function
Best for osteoporotic bone	Often useful	Less reliable
Best for short periarticular fragments	Often useful	Often less suitable
Best for simple shaft fracture needing compression	Can be used	A classic indication
Plate-bone contact	Can be less dependent on intimate contact	Requires close plate-bone contact

Easy memory rule

DCP: Dynamic fracture Compression by a conventional screw sliding in an oval plate hole.
LCP: Locking screw head locks to the plate, creating fixed-angle stability.
Cortical screw: fine-thread screw for the hard outer bone.
Cancellous screw: coarse-thread screw for soft spongy bone.

The AO Foundation’s plate guide describes how eccentric insertion of a conventional screw in a DCP hole produces fracture compression. The AO reconstruction-plate reference also explains that modern plate systems may accept cortical, metaphyseal, and locking screws.

Create a comparison table of LCP, DCP, and reconstruction plates

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locking compression plate fracture fixation

Feature	LCP: Locking Compression Plate	DCP: Dynamic Compression Plate	Reconstruction Plate
Main concept	A versatile plate that can use locking screws, conventional screws, or both	A conventional plate designed to create axial compression across a fracture	A highly bendable plate designed to match complex bone surfaces
Plate holes	Usually combi-holes: one part accepts a locking screw, another accepts a conventional screw in neutral or compression mode	Oval, sloped holes that permit neutral or eccentric conventional-screw placement	Usually oval or combi-holes, depending on the system; deep notches between holes allow contouring
Compatible screws	Locking screws, cortical screws, cancellous screws, and sometimes both locking and non-locking screws in the same construct	Mainly conventional non-locking cortical or cancellous screws	Usually conventional cortical/cancellous screws; modern reconstruction plates may also accept locking screws
How stability is obtained	Screw heads lock into plate holes, creating a fixed-angle plate-screw frame	Conventional screws pull the plate firmly against bone; stability relies on screw grip and plate-bone friction	Depends on the screw system used. Its major advantage is contouring rather than locking or compression alone
Can it compress a fracture?	Yes. Use conventional screws in the compression part of a combi-hole before locking screws are inserted	Yes. This is its classic function. Eccentric screw insertion makes the bone fragment move toward the fracture	Can provide compression if its holes and screw technique permit it, but it is mainly selected for contourability
Plate-to-bone contact	Does not need to be tightly compressed against bone for stability when locking screws are used	Requires close contact between plate and bone	Usually contoured closely to the bone because it is used on irregular surfaces
Best bone quality	Particularly useful in osteoporotic or weak bone	Best when bone quality and conventional screw purchase are adequate	Depends on screw type; commonly used where anatomy, rather than bone quality, drives implant choice
Best fracture pattern	Comminuted fractures, periarticular fractures, short fragments, osteoporotic fractures, bridge-plating constructs	Simple transverse or short-oblique fractures with good bone contact and a need for compression	Fractures of irregular or curved bones, especially where extensive bending is needed
Typical locations	Distal radius, proximal humerus, distal femur, proximal tibia, clavicle	Radius and ulna shafts, humeral shaft, selected tibial/femoral shaft fractures	Pelvis, acetabulum, clavicle, distal humerus, selected scapular and complex periarticular fractures
Main advantage	Fixed-angle stability and versatile screw options	Predictable fracture compression with a relatively simple conventional construct	Can be bent in multiple planes to fit difficult anatomy
Main limitation	More technique-sensitive and often more expensive; locking screws alone do not reduce a fracture or create compression	Less reliable in severe osteoporosis or very short periarticular fragments	Excessive bending can weaken the plate; it is not automatically a locking plate

Simple visual memory guide

LCP
[ Combi-hole ]  = can take locking or non-locking screws
       ↓
Locking screw head threads into plate
Plate + screws act like one fixed-angle frame

DCP
[ Oval, sloped hole ]
       ↓
Conventional screw placed eccentrically
Tightening slides the screw head down the slope
Bone fragment moves toward fracture = compression

Reconstruction plate
|--o--|--o--|--o--|--o--|
  ^ deep notches between holes
  Allows bending in several planes
  Fits curved or irregular bone surfaces

Key distinctions

LCP is not only a locking plate. It can act as a compression, neutralization, bridge, or buttress plate depending on the screw arrangement and fracture.
DCP does not use locking screws. Its defining feature is the specially shaped hole that enables dynamic compression with a conventional screw.
A reconstruction plate is defined by shape and bendability. It may be conventional or locking depending on the particular implant system.
A reconstruction plate is often chosen for the pelvis, acetabulum, clavicle, and distal humerus because these bones have complex contours.

The AO plate guide describes LCP combi-holes, DCP compression-hole geometry, and the deep notches that make reconstruction plates contourable.

Show labeled diagrams of LCP, DCP, and reconstruction plate holes

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labeled diagram LCP locking compression plate combi hole DCP dynamic compression plate hole reconstruction plate notched holes

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AO Foundation plates form function LCP combi hole DCP reconstruction plate notches diagram

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A medically accurate educational diagram comparing orthopedic plate holes, with three horizontal plates on a plain white background. Top: labeled Locking Compression Plate (LCP) with three enlarged combi-holes, each clearly divided into a threaded circular locking portion and an oblong dynamic compression portion. Middle: labeled Dynamic Compression Plate (DCP) with three enlarged oval dynamic-compression holes, including one cross-section inset showing the sloping shoulder and arrows indicating eccentric screw movement toward a fracture. Bottom: labeled Reconstruction Plate with scalloped deep notches between oval holes, with bending arrows in multiple planes. Add clear callout labels: locking threaded portion, compression portion, eccentric position, neutral position, deep contouring notch. Clean vector-style textbook schematic, black and dark blue lines, labels large and readable, no logos, no patient anatomy.

Labeled diagrams: LCP, DCP, and reconstruction plate holes

Comparison of LCP combi-holes, DCP compression holes, and reconstruction-plate notches

1. LCP: Locking Compression Plate

LCP combi-hole, top view

 ┌──────────────────────────────┐
 │  Compression part | Locking  │
 │      (oval)      | threaded │
 │        ◁         |    ○     │
 └──────────────────────────────┘

Two functional parts of an LCP combi-hole:

Compression portion: accepts a conventional, non-locking screw. If drilled eccentrically, it can generate fracture compression.
Locking threaded portion: accepts a locking screw. The screw head threads into the plate and creates fixed-angle stability.

Therefore, an LCP can use locking screws, non-locking screws, or a combination. It can function as a compression, neutralization, buttress, or bridge plate.

2. DCP: Dynamic Compression Plate

DCP hole, top view

       Oval hole
     ┌───────────┐
     │  neutral  │
     │     ○     │
     │           │
     │ eccentric ●  → toward fracture
     └───────────┘

DCP hole, side section

    Screw head
       ↓
      (●)     slides down the sloping shoulder
  ─────╲________________ plate
        ╲
         ╲_____ moves bone fragment toward fracture

A DCP hole is oval and has a sloping shoulder. A conventional screw may be inserted:

Neutral position: secures plate to bone without producing axial compression.
Eccentric position: as the screw is tightened, the head slides down the sloped portion and shifts the bone fragment toward the fracture, creating compression.

A DCP does not have a threaded locking portion, so it uses conventional non-locking screws.

3. Reconstruction plate

Reconstruction plate, top view

  Deep notch     Deep notch     Deep notch
      ↓              ↓              ↓
 ──╲__/──(  )──╲__/──(  )──╲__/──(  )──
       oval hole      oval hole

The important feature is the deep notches between plate holes. These allow the plate to be bent:

Along its length
Side-to-side, called bending “on the flat”
With contouring in multiple planes

This makes reconstruction plates useful on complex curved anatomy, especially the pelvis, acetabulum, clavicle, and distal humerus.

One important detail

Reconstruction plates can have:

Oval DCP-style holes, allowing conventional screw compression, or
Combi-holes in newer systems, allowing both conventional and locking screws.

They are defined mainly by their contourability, not solely by their hole type. They are generally less stiff than a locking plate and repeated or sharp bending can weaken them.

The AO plate guide describes LCP combi-holes, the sloping DCP hole used for eccentric compression, and the notched design of reconstruction plates.

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mkdir -p "/tmp/workspace/orthopaedic-implants-pdf/src" "/tmp/workspace/orthopaedic-implants-pdf/output" && python - <<'PY' from reportlab.pdfgen import canvas from reportlab.lib.pagesizes import A4 from reportlab.lib.colors import HexColor, black, white from reportlab.lib.units import mm from reportlab.pdfbase.pdfmetrics import stringWidth from reportlab.pdfbase.ttfonts import TTFont from reportlab.pdfbase import pdfmetrics from reportlab.lib import colors from reportlab.pdfbase.pdfmetrics import registerFont from reportlab.pdfbase.ttfonts import TTFont from reportlab.pdfbase.pdfmetrics import stringWidth from reportlab.lib.utils import simpleSplit from pathlib import Path out = Path('/tmp/workspace/orthopaedic-implants-pdf/output/Orthopaedic_Plate_and_Screw_Types.pdf') W,H=A4 c=canvas.Canvas(str(out),pagesize=A4) c.setTitle('Orthopaedic Plate and Screw Types') c.setAuthor('Orris') NAVY=HexColor('#163A5F'); BLUE=HexColor('#1F6EA8'); TEAL=HexColor('#208E8A'); LIGHT=HexColor('#EAF3F8'); GREY=HexColor('#5E6B75'); PALE=HexColor('#F7FAFC'); ORANGE=HexColor('#D87824'); RED=HexColor('#BA3A3A'); DARK=HexColor('#1C2630') def title(text, sub=''): c.setFillColor(NAVY); c.rect(0,H-32*mm,W,32*mm,stroke=0,fill=1) c.setFillColor(white); c.setFont('Helvetica-Bold',21); c.drawString(16*mm,H-18*mm,text) if sub: c.setFont('Helvetica',9.5); c.drawString(16*mm,H-25*mm,sub) def footer(page): c.setStrokeColor(HexColor('#D5E1EA'));c.line(14*mm,14*mm,W-14*mm,14*mm) c.setFillColor(GREY);c.setFont('Helvetica',7.5) c.drawString(14*mm,9*mm,'Educational schematic only - implant choice and application require orthopaedic training.') c.drawRightString(W-14*mm,9*mm,f'Page {page}') def wrap(text,x,y,width,font='Helvetica',size=9,leading=12,color=DARK): c.setFont(font,size);c.setFillColor(color) for line in simpleSplit(text,font,size,width): c.drawString(x,y,line); y-=leading return y def panel(x,y,w,h,heading): c.setFillColor(PALE);c.setStrokeColor(HexColor('#B8CBD9'));c.roundRect(x,y,w,h,4*mm,stroke=1,fill=1) c.setFillColor(NAVY);c.setFont('Helvetica-Bold',13);c.drawString(x+5*mm,y+h-9*mm,heading) def screw(x,y,length,kind,label,locking=False): # y baseline central, horizontal c.setStrokeColor(DARK); c.setFillColor(HexColor('#B9C5CE')) # head c.circle(x,y,5*mm,stroke=1,fill=1); c.setStrokeColor(DARK); c.line(x-2*mm,y,x+2*mm,y) start=x+5*mm; end=x+length c.setStrokeColor(DARK);c.setLineWidth(2.2);c.line(start,y,end,y) # threads c.setLineWidth(0.8) if kind=='cortical': spacing=3.2*mm; depth=1.5*mm; thread_start=start+1*mm elif kind=='cancellous': spacing=5.5*mm; depth=3*mm; thread_start=start+length*.32 else: spacing=3.5*mm; depth=1.7*mm; thread_start=start+1*mm px=thread_start while px<end-1*mm: c.line(px,y-depth,px+spacing*.55,y+depth); px+=spacing if locking: c.setStrokeColor(ORANGE);c.setLineWidth(1.2) for a in [-3,-1,1,3]: c.arc(x-5*mm+a*mm,y-5*mm+a*0.25*mm,x+5*mm+a*mm,y+5*mm+a*0.25*mm,70,40) c.setFillColor(NAVY);c.setFont('Helvetica-Bold',9);c.drawString(x,y-9*mm,label) def page1(): title('Orthopaedic Plate and Screw Types','Labeled teaching diagrams: LCP, DCP, reconstruction plates, and common screw designs') c.setFillColor(DARK); c.setFont('Helvetica-Bold',11);c.drawString(16*mm,H-42*mm,'How to use this handout') wrap('Plate names describe the plate design and function. Screw names may describe either the screw-to-plate interface (locking or non-locking) or the thread design for the bone being gripped (cortical or cancellous).',16*mm,H-48*mm,W-32*mm,size=9.3) # two axes c.setFillColor(LIGHT);c.roundRect(16*mm,H-79*mm,W-32*mm,20*mm,3*mm,stroke=0,fill=1) c.setFillColor(NAVY);c.setFont('Helvetica-Bold',10);c.drawString(21*mm,H-67*mm,'Two separate ways to classify screws') c.setFont('Helvetica',9);c.setFillColor(DARK) c.drawString(21*mm,H-73*mm,'1. Interface with plate: locking vs non-locking') c.drawString(105*mm,H-73*mm,'2. Bone thread: cortical vs cancellous') # panels panel(16*mm,H-157*mm,86*mm,68*mm,'Locking screw') panel(108*mm,H-157*mm,86*mm,68*mm,'Non-locking screw') # locking mini x=29*mm;y=H-112*mm c.setFillColor(HexColor('#C8DCEB'));c.roundRect(x,y,53*mm,8*mm,2*mm,stroke=1,fill=1) c.setFillColor(white);c.circle(x+37*mm,y+4*mm,3.7*mm,stroke=1,fill=1) c.setStrokeColor(ORANGE);c.setLineWidth(1.3);c.circle(x+37*mm,y+4*mm,3*mm,stroke=1,fill=0) c.setStrokeColor(DARK);c.setLineWidth(1.7);c.line(x+37*mm,y+4*mm,x+37*mm,y-18*mm) c.setFillColor(ORANGE);c.setFont('Helvetica-Bold',7.5);c.drawString(x+41*mm,y+8*mm,'threaded head locks') c.setFillColor(DARK);c.setFont('Helvetica',8.2);wrap('The screw head threads into the plate hole. Plate and screw form a fixed-angle construct; stability does not rely on tightly compressing the plate to bone.',21*mm,H-137*mm,75*mm,size=8.2,leading=10) # non locking x=121*mm;y=H-112*mm c.setFillColor(HexColor('#C8DCEB'));c.roundRect(x,y,53*mm,8*mm,2*mm,stroke=1,fill=1) c.setFillColor(white);c.circle(x+37*mm,y+4*mm,3.7*mm,stroke=1,fill=1) c.setStrokeColor(DARK);c.setLineWidth(1.7);c.line(x+37*mm,y+4*mm,x+37*mm,y-18*mm) c.setFillColor(RED);c.setFont('Helvetica-Bold',7.5);c.drawString(x+5*mm,y+11*mm,'head presses plate to bone') c.setFillColor(DARK);c.setFont('Helvetica',8.2);wrap('The head does not thread into the plate. Tightening pulls the plate against the bone. Stability depends on bone purchase and plate-to-bone friction.',113*mm,H-137*mm,75*mm,size=8.2,leading=10) # screw designs c.setFillColor(NAVY);c.setFont('Helvetica-Bold',13);c.drawString(16*mm,H-172*mm,'Thread design: cortical versus cancellous') c.setStrokeColor(HexColor('#B8CBD9'));c.roundRect(16*mm,H-254*mm,W-32*mm,72*mm,4*mm,stroke=1,fill=0) screw(31*mm,H-202*mm,60*mm,'cortical','Cortical screw') c.setFillColor(DARK);wrap('Fine, closely spaced threads. Used primarily in dense cortical bone, especially the shaft (diaphysis) of long bones and for many plate screws.',25*mm,H-218*mm,70*mm,size=8.3,leading=10) screw(119*mm,H-202*mm,60*mm,'cancellous','Cancellous screw') c.setFillColor(DARK);wrap('Deep, widely spaced threads. Used in softer trabecular bone near bone ends (metaphysis/epiphysis), e.g., femoral neck, tibial plateau, malleoli.',113*mm,H-218*mm,70*mm,size=8.3,leading=10) c.setFillColor(ORANGE);c.setFont('Helvetica-Bold',9);c.drawString(22*mm,H-246*mm,'Memory aid: cortex = fine thread; cancellous bone = coarse/deep thread.') footer(1);c.showPage() def plate_body(x,y,w,h,kind): c.setFillColor(HexColor('#C8DCEB'));c.setStrokeColor(NAVY);c.setLineWidth(1);c.roundRect(x,y,w,h,2*mm,stroke=1,fill=1) centers=[x+w*.2,x+w*.5,x+w*.8] for cx in centers: if kind=='LCP': # combi hole, left dynamic ellipse and right threaded circle c.setFillColor(white);c.ellipse(cx-7*mm,y+h/2-3.5*mm,cx+1*mm,y+h/2+3.5*mm,stroke=1,fill=1) c.circle(cx+5*mm,y+h/2,3.7*mm,stroke=1,fill=1) c.setStrokeColor(ORANGE);c.setLineWidth(.75);c.circle(cx+5*mm,y+h/2,2.6*mm,stroke=1,fill=0) elif kind=='DCP': c.setFillColor(white);c.ellipse(cx-7*mm,y+h/2-4*mm,cx+7*mm,y+h/2+4*mm,stroke=1,fill=1) c.setStrokeColor(GREY);c.setLineWidth(.7);c.line(cx+2*mm,y+h/2-3*mm,cx+5*mm,y+h/2+3*mm) else: # reconstruct scallop top/bottom plus holes c.setFillColor(white);c.ellipse(cx-6*mm,y+h/2-3.5*mm,cx+6*mm,y+h/2+3.5*mm,stroke=1,fill=1) if kind=='RECON': c.setStrokeColor(white);c.setLineWidth(2.6) for cx in [x+w*.35,x+w*.65]: c.arc(cx-5*mm,y+h-2*mm,cx+5*mm,y+h+5*mm,180,180) c.arc(cx-5*mm,y-5*mm,cx+5*mm,y+2*mm,0,180) def page2(): title('Plate Types and Hole Design','The plate hole determines whether compression, locking fixation, or both can be used') # LCP panel(16*mm,H-103*mm,W-32*mm,58*mm,'1. LCP: Locking Compression Plate') plate_body(27*mm,H-77*mm,82*mm,11*mm,'LCP') c.setFillColor(ORANGE);c.setFont('Helvetica-Bold',8);c.drawString(28*mm,H-88*mm,'Orange ring = threaded locking portion') c.setFillColor(BLUE);c.drawString(28*mm,H-94*mm,'White oval = dynamic compression portion for conventional screw') wrap('A combi-hole can accept either a locking screw or a conventional non-locking screw. It can function in compression, neutralization, buttress, or bridge mode. Especially useful for short periarticular fragments and osteoporotic bone.',118*mm,H-70*mm,65*mm,size=8.4,leading=10) # DCP panel(16*mm,H-169*mm,W-32*mm,58*mm,'2. DCP: Dynamic Compression Plate') plate_body(27*mm,H-143*mm,82*mm,11*mm,'DCP') c.setFillColor(RED);c.setFont('Helvetica-Bold',8);c.drawString(28*mm,H-154*mm,'Oval hole with sloping shoulder') c.setFillColor(DARK);c.setFont('Helvetica',8);c.drawString(28*mm,H-160*mm,'No threaded locking hole: uses conventional screws.') wrap('A conventional screw placed eccentrically slides down the sloped portion of the hole as it is tightened. This shifts the bone fragment toward the fracture and creates axial compression. Classic use: simple shaft fractures with good bone contact.',118*mm,H-136*mm,65*mm,size=8.4,leading=10) # reconstruction panel(16*mm,H-235*mm,W-32*mm,58*mm,'3. Reconstruction plate') plate_body(27*mm,H-209*mm,82*mm,11*mm,'RECON') c.setFillColor(TEAL);c.setFont('Helvetica-Bold',8);c.drawString(28*mm,H-220*mm,'Scalloped deep notches between holes') c.setFillColor(DARK);c.setFont('Helvetica',8);c.drawString(28*mm,H-226*mm,'Allows contouring in several planes.') wrap('A reconstruction plate is defined mainly by its high contourability, not by one fixed hole system. It is useful on complex curved anatomy such as the pelvis, acetabulum, clavicle, and distal humerus. It may have oval holes or combi-holes depending on the system.',118*mm,H-202*mm,65*mm,size=8.4,leading=10) # recap table c.setFillColor(NAVY);c.setFont('Helvetica-Bold',11);c.drawString(16*mm,H-248*mm,'Quick comparison') x=16*mm;y=H-285*mm; widths=[38*mm,48*mm,48*mm,48*mm]; hh=8*mm headers=['Feature','LCP','DCP','Reconstruction'] c.setFillColor(NAVY) xx=x for wd,tx in zip(widths,headers): c.rect(xx,y,wd,hh,stroke=1,fill=1);c.setFillColor(white);c.setFont('Helvetica-Bold',7.5);c.drawCentredString(xx+wd/2,y+2.5*mm,tx);c.setFillColor(NAVY);xx+=wd rows=[('Key hole','Combi-hole','Sloped oval hole','Oval or combi-hole'),('Primary strength','Fixed-angle option','Dynamic compression','Multi-plane contouring'),('Usual screw','Locking or conventional','Conventional','System-dependent')] for r,row in enumerate(rows): yy=y-(r+1)*9*mm;xx=x for wd,tx in zip(widths,row): c.setFillColor(white);c.setStrokeColor(HexColor('#B8CBD9'));c.rect(xx,yy,wd,9*mm,stroke=1,fill=1) c.setFillColor(DARK);c.setFont('Helvetica',7.2); lines=simpleSplit(tx,'Helvetica',7.2,wd-3*mm) for j,line in enumerate(lines):c.drawCentredString(xx+wd/2,yy+5.2*mm-j*2.6*mm,line) xx+=wd footer(2);c.showPage() def page3(): title('Common Plate and Screw Types','Illustrated revision summary') c.setFillColor(NAVY);c.setFont('Helvetica-Bold',13);c.drawString(16*mm,H-44*mm,'Common plates') items=[ ('Locking compression plate (LCP)','Combi-holes. Locking screws provide fixed-angle stability. Common near joints and in osteoporotic bone.'), ('Dynamic compression plate (DCP)','Sloped oval holes. Eccentric conventional screws generate compression across a simple fracture.'), ('Reconstruction plate','Deep side notches. Very contourable for irregular anatomy, e.g., pelvis, acetabulum, clavicle, distal humerus.'), ('Buttress plate','Supports a fragment against shear or collapse, often near a joint such as tibial plateau or distal radius.'), ('Bridge plate','Spans a comminuted zone while preserving fracture biology; commonly used with relative stability.'), ] y=H-53*mm for name,desc in items: c.setFillColor(LIGHT);c.roundRect(16*mm,y-11*mm,W-32*mm,13*mm,2*mm,stroke=0,fill=1) c.setFillColor(NAVY);c.setFont('Helvetica-Bold',9);c.drawString(20*mm,y-3*mm,name) c.setFillColor(DARK);c.setFont('Helvetica',8.2);c.drawString(70*mm,y-3*mm,desc) y-=15*mm c.setFillColor(NAVY);c.setFont('Helvetica-Bold',13);c.drawString(16*mm,H-136*mm,'Common screws') screw(26*mm,H-153*mm,54*mm,'generic','Locking screw',locking=True) wrap('Threaded head locks into an LCP hole. Provides angular stability.',20*mm,H-166*mm,70*mm,size=8.2,leading=9.5) screw(111*mm,H-153*mm,54*mm,'generic','Non-locking screw') wrap('Head presses plate to bone. Used in conventional plating and compression.',105*mm,H-166*mm,70*mm,size=8.2,leading=9.5) screw(26*mm,H-197*mm,54*mm,'cortical','Cortical screw') wrap('Fine threads for dense cortical bone, commonly in long-bone shafts.',20*mm,H-210*mm,70*mm,size=8.2,leading=9.5) screw(111*mm,H-197*mm,54*mm,'cancellous','Cancellous screw') wrap('Coarse deep threads for trabecular bone, commonly near bone ends.',105*mm,H-210*mm,70*mm,size=8.2,leading=9.5) c.setFillColor(HexColor('#FFF3E7'));c.setStrokeColor(ORANGE);c.roundRect(16*mm,H-253*mm,W-32*mm,27*mm,3*mm,stroke=1,fill=1) c.setFillColor(ORANGE);c.setFont('Helvetica-Bold',10);c.drawString(21*mm,H-237*mm,'High-yield distinction') wrap('Locking versus non-locking describes the screw-to-plate interface. Cortical versus cancellous describes the thread design and bone purchase. These descriptions can overlap: a screw can be both a cortical screw and a locking screw.',21*mm,H-244*mm,W-42*mm,size=8.8,leading=10) c.setFillColor(GREY);c.setFont('Helvetica',7.3) c.drawString(16*mm,23*mm,'Sources: Campbell’s Operative Orthopaedics, 15th ed., sections on screw fixation and biomaterials; AO Foundation, Plates: Form and Function.') footer(3);c.showPage() page1();page2();page3();c.save() print(out) PY python - <<'PY' from pypdf import PdfReader p='/tmp/workspace/orthopaedic-implants-pdf/output/Orthopaedic_Plate_and_Screw_Types.pdf' r=PdfReader(p) print('pages',len(r.pages),'size',__import__('os').path.getsize(p)) print(r.pages[0].extract_text()[:350]) PY

The labeled 3-page PDF includes diagrams and comparison notes for LCP, DCP, reconstruction plates, locking/non-locking screws, and cortical/cancellous screws.

Orthopaedic Plate and Screw Types

PDF Document · PDF

Add labeled diagrams of cortical, cancellous, locking, and lag screws

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~/orthopaedic-implants-pdf/

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Searching PubMed

orthopedic screw fixation

Searching the Web

AO Foundation cortical cancellous locking lag screw fixation principles

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~/orthopaedic-implants-pdf/src

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~/orthopaedic-implants-pdf/output

Running Command

python - <<'PY' from reportlab.pdfgen import canvas from reportlab.lib.pagesizes import A4 from reportlab.lib.units import mm from reportlab.lib.colors import HexColor, white from reportlab.lib.utils import simpleSplit from pathlib import Path from pypdf import PdfReader, PdfWriter base=Path('/tmp/workspace/orthopaedic-implants-pdf/output/Orthopaedic_Plate_and_Screw_Types.pdf') supp=Path('/tmp/workspace/orthopaedic-implants-pdf/src/screw_diagrams_supplement.pdf') final=Path('/tmp/workspace/orthopaedic-implants-pdf/output/Orthopaedic_Plate_and_Screw_Types_Expanded.pdf') W,H=A4 NAVY=HexColor('#163A5F'); BLUE=HexColor('#1F6EA8'); TEAL=HexColor('#208E8A'); LIGHT=HexColor('#EAF3F8'); GREY=HexColor('#5E6B75'); PALE=HexColor('#F7FAFC'); ORANGE=HexColor('#D87824'); RED=HexColor('#BA3A3A'); DARK=HexColor('#1C2630'); BONE=HexColor('#F5E7C9') c=canvas.Canvas(str(supp),pagesize=A4) c.setTitle('Orthopaedic Screw Types - Labeled Diagrams') def wrap(text,x,y,w,size=8.1,leading=9.6,bold=False): c.setFillColor(DARK);c.setFont('Helvetica-Bold' if bold else 'Helvetica',size) for line in simpleSplit(text,'Helvetica-Bold' if bold else 'Helvetica',size,w): c.drawString(x,y,line); y-=leading return y def panel(x,y,w,h,title,color=BLUE): c.setFillColor(PALE);c.setStrokeColor(HexColor('#B8CBD9'));c.roundRect(x,y,w,h,3*mm,stroke=1,fill=1) c.setFillColor(color);c.setFont('Helvetica-Bold',11);c.drawString(x+4*mm,y+h-7*mm,title) def threaded_screw(x,y,length,mode,label,head_lock=False): # horizontal screw, y center c.setStrokeColor(DARK);c.setFillColor(HexColor('#B9C5CE'));c.setLineWidth(0.9) c.circle(x,y,4.5*mm,stroke=1,fill=1) c.line(x-2*mm,y,x+2*mm,y); c.line(x,y-2*mm,x,y+2*mm) shaftstart=x+4.5*mm; end=x+length c.setStrokeColor(DARK);c.setLineWidth(2.4);c.line(shaftstart,y,end,y) if mode=='cortical': st=shaftstart+1*mm; spacing=3.1*mm; depth=1.6*mm elif mode=='cancellous': st=shaftstart+1*mm; spacing=5.2*mm; depth=3.1*mm elif mode=='lag': st=shaftstart+length*0.42; spacing=4.5*mm; depth=2.4*mm elif mode=='locking': st=shaftstart+1*mm; spacing=3.2*mm; depth=1.6*mm p=st;c.setLineWidth(.8) while p<end-1.8*mm: c.line(p,y-depth,p+spacing*.6,y+depth);p+=spacing if head_lock: c.setStrokeColor(ORANGE);c.setLineWidth(0.8) for k in [-2.3,-.8,.8,2.3]: c.arc(x-4*mm+k*mm,y-4*mm,x+4*mm+k*mm,y+4*mm,50,70) c.setFillColor(NAVY);c.setFont('Helvetica-Bold',8.8);c.drawString(x,y-8*mm,label) def bone_blocks(x,y,w,h,gap=2*mm): c.setFillColor(BONE);c.setStrokeColor(HexColor('#9B7D52')) c.rect(x,y,w/2-gap/2,h,stroke=1,fill=1);c.rect(x+w/2+gap/2,y,w/2-gap/2,h,stroke=1,fill=1) c.setFillColor(RED);c.setFont('Helvetica-Bold',7);c.drawCentredString(x+w/2,y+h+2.5*mm,'fracture line') # title c.setFillColor(NAVY);c.rect(0,H-32*mm,W,32*mm,stroke=0,fill=1) c.setFillColor(white);c.setFont('Helvetica-Bold',20);c.drawString(16*mm,H-18*mm,'Labeled Orthopaedic Screw Diagrams') c.setFont('Helvetica',9.5);c.drawString(16*mm,H-25*mm,'Cortical, cancellous, locking, and lag screws: design, function, and common use') # panels 2x2 left=14*mm; right=108*mm; ytop=H-112*mm; bw=88*mm; bh=67*mm panel(left,ytop,bw,bh,'1. Cortical screw',BLUE) threaded_screw(left+14*mm,ytop+43*mm,59*mm,'cortical','Fine, closely spaced threads') c.setFillColor(RED);c.setFont('Helvetica-Bold',7.5);c.drawString(left+13*mm,ytop+32*mm,'Designed for dense cortical bone') wrap('Usually fully threaded. The fine thread pitch is suited to the hard outer cortex, especially in long-bone shafts and for conventional plate fixation.',left+5*mm,ytop+24*mm,bw-10*mm) panel(right,ytop,bw,bh,'2. Cancellous screw',TEAL) threaded_screw(right+14*mm,ytop+43*mm,59*mm,'cancellous','Deep, widely spaced threads') c.setFillColor(TEAL);c.setFont('Helvetica-Bold',7.5);c.drawString(right+13*mm,ytop+32*mm,'Designed for softer trabecular bone') wrap('The deeper, coarser threads improve grip in cancellous bone near the ends of long bones, e.g., femoral neck, tibial plateau, and malleoli.',right+5*mm,ytop+24*mm,bw-10*mm) y2=H-186*mm panel(left,y2,bw,bh,'3. Locking screw',ORANGE) # plate and locking head depiction c.setFillColor(HexColor('#C8DCEB'));c.setStrokeColor(NAVY);c.roundRect(left+14*mm,y2+45*mm,61*mm,8*mm,2*mm,stroke=1,fill=1) c.setFillColor(white);c.circle(left+46*mm,y2+49*mm,4*mm,stroke=1,fill=1) c.setStrokeColor(ORANGE);c.setLineWidth(1);c.circle(left+46*mm,y2+49*mm,3*mm,stroke=1,fill=0) threaded_screw(left+46*mm,y2+49*mm,0,'locking','',head_lock=True) # redraw lower body screw from plate down as vertical conceptual c.setStrokeColor(DARK);c.setLineWidth(2.2);c.line(left+46*mm,y2+45*mm,left+46*mm,y2+28*mm) c.setStrokeColor(DARK);c.setLineWidth(.8) for yy in range(int(y2+30*mm),int(y2+44*mm),int(3*mm)): c.line(left+43.8*mm,yy,left+48.2*mm,yy+2*mm) c.setFillColor(ORANGE);c.setFont('Helvetica-Bold',7.5);c.drawString(left+14*mm,y2+35*mm,'Threaded head locks into threaded plate hole') wrap('Produces a fixed-angle plate-screw construct. The plate does not need to be pressed tightly against bone for stability. Useful in osteoporotic bone and short periarticular fragments.',left+5*mm,y2+24*mm,bw-10*mm) panel(right,y2,bw,bh,'4. Lag screw',RED) bone_blocks(right+9*mm,y2+33*mm,67*mm,13*mm) threaded_screw(right+11*mm,y2+39.5*mm,62*mm,'lag','',head_lock=False) c.setFillColor(RED);c.setFont('Helvetica-Bold',7.2);c.drawString(right+9*mm,y2+26*mm,'Smooth near segment glides; threads grip far segment') wrap('A lag screw is a function, not a separate thread type. Tightening draws the far fragment toward the near fragment and compresses the fracture. Ideally placed perpendicular to the fracture plane.',right+5*mm,y2+18*mm,bw-10*mm) # comparison bar c.setFillColor(NAVY);c.setFont('Helvetica-Bold',12);c.drawString(14*mm,H-199*mm,'Quick comparison') headers=['Screw','Main defining feature','Typical role'] rows=[['Cortical','Fine, close threads','Dense cortical shaft bone'],['Cancellous','Deep, coarse threads','Trabecular bone near a joint'],['Locking','Threaded head engages plate','Fixed-angle plate construct'],['Lag','Near fragment glides, far fragment grips','Interfragmentary compression']] x=14*mm;y=H-207*mm;widths=[37*mm,67*mm,79*mm] for i,h in enumerate(headers): c.setFillColor(NAVY);c.rect(x,y,widths[i],8*mm,stroke=1,fill=1);c.setFillColor(white);c.setFont('Helvetica-Bold',7.6);c.drawCentredString(x+widths[i]/2,y+2.7*mm,h);x+=widths[i] for rowi,row in enumerate(rows): x=14*mm;yy=y-(rowi+1)*8.5*mm for i,txt in enumerate(row): c.setFillColor(white);c.setStrokeColor(HexColor('#B8CBD9'));c.rect(x,yy,widths[i],8.5*mm,stroke=1,fill=1) c.setFillColor(DARK);c.setFont('Helvetica',7.5);c.drawCentredString(x+widths[i]/2,yy+2.8*mm,txt);x+=widths[i] # bottom note c.setFillColor(HexColor('#FFF3E7'));c.setStrokeColor(ORANGE);c.roundRect(14*mm,20*mm,W-28*mm,19*mm,3*mm,stroke=1,fill=1) c.setFillColor(ORANGE);c.setFont('Helvetica-Bold',8.8);c.drawString(19*mm,33*mm,'Important distinction') wrap('Cortical/cancellous refers to thread design and bone purchase. Locking/non-locking refers to the screw-to-plate interface. A lag screw describes how compression is achieved. A single screw may have more than one of these descriptors.',19*mm,28*mm,W-38*mm,size=8.1,leading=9) c.setFillColor(GREY);c.setFont('Helvetica',7);c.drawString(14*mm,11*mm,'Educational schematic only. Source concepts: Campbell’s Operative Orthopaedics, 15th ed.; AO Surgery Reference, Lag Screw Principles.') c.save() writer=PdfWriter() for p in PdfReader(str(base)).pages: writer.add_page(p) for p in PdfReader(str(supp)).pages: writer.add_page(p) with open(final,'wb') as f: writer.write(f) print(final) PY python - <<'PY' from pypdf import PdfReader from pathlib import Path p=Path('/tmp/workspace/orthopaedic-implants-pdf/output/Orthopaedic_Plate_and_Screw_Types_Expanded.pdf') r=PdfReader(str(p)) print('pages=',len(r.pages),'bytes=',p.stat().st_size) print(r.pages[-1].extract_text()[:800]) PY

Added a fourth page with labeled diagrams of:

Cortical screw
Cancellous screw
Locking screw
Lag screw, including fracture-compression mechanism

Orthopaedic Plate and Screw Types Expanded

PDF Document · PDF

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