Overview & History
The Kirschner wire (K-wire) is one of the most versatile and widely used implants in orthopaedic surgery. Named after Martin Kirschner, the German surgeon who introduced it in 1909, the K-wire is a smooth or threaded stainless steel pin used for temporary or definitive fixation of fractures, as a guide wire for cannulated screw systems, for provisional reduction during plating, for traction (via a Steinmann pin — the larger-diameter equivalent), and as part of the tension band wiring construct. Despite its apparent simplicity, effective use of the K-wire requires a thorough understanding of its biomechanical properties, appropriate wire selection, correct insertion technique, and awareness of its substantial complication profile when misused. K-wires are used across virtually every subspecialty of orthopaedic surgery — from paediatric supracondylar fractures to adult hand and wrist surgery, ankle fractures, and complex reconstruction.
- Comparison with Steinmann pins: K-wires are defined as smooth stainless steel pins with a diameter of 0.7–2.0 mm (most commonly 1.0–1.6 mm in hand surgery; 1.6–2.0 mm in larger bones); Steinmann pins are larger diameter smooth pins (>2.0 mm — typically 3.0–6.0 mm) used primarily for skeletal traction (distal femoral traction pin, calcaneal traction pin, olecranon traction pin) and occasionally for temporary large bone fixation; the principles governing their use are identical but the applications and associated complications differ in scale
- Materials: standard K-wires are manufactured from 316L stainless steel (the same grade used for most orthopaedic implants); they are biocompatible and MRI-compatible (produce artefact but do not generate clinically significant heating at standard MRI field strengths); titanium K-wires are available and produce less MRI artefact but are more expensive and less commonly used; the wire is typically trocar-tipped (sharp three-faceted point for bone penetration) or diamond-tipped; smooth wires provide no intrinsic rotational stability; threaded wires (half-threaded or fully threaded) provide additional purchase but are harder to remove and risk iatrogenic fracture if the thread engages across a fracture line
Wire Sizes & Selection
| Wire Diameter | Common Applications | Key Considerations |
|---|---|---|
| 0.7–0.9 mm | Fingertip and phalangeal fixation; DIP joint arthrodesis; small bone fragment fixation in paediatric hand surgery; temporary fixation of small carpal fragments | Very fine — bends and breaks easily under load; use only for small bones with low mechanical demands; not suitable where functional loading will occur; adequate for immobilisation but not load-sharing |
| 1.0–1.2 mm | Metacarpal and phalangeal fractures; PIPJ and MCPJ fixation; small carpal bone fixation; paediatric lateral condyle fixation (smaller children); DIP and PIP joint arthrodesis; nail bed repairs (to splint the distal phalanx) | Standard small hand wire; versatile; adequate stiffness for metacarpals and phalanges; commonly used in hand surgery as the `standard` small wire |
| 1.4–1.6 mm | Supracondylar humerus fractures in children (most commonly 1.6 mm); metacarpal fractures; carpal fixation (scaphoid provisional, hamate); ankle and hindfoot provisional fixation; paediatric femoral neck (Delbet Type IV — distal fragment); radial styloid avulsion; lateral condyle humerus fractures; tension band wiring constructs | The MOST COMMONLY USED wire in orthopaedic practice; sufficient stiffness for provisional fixation of medium-sized bones; the standard wire for paediatric supracondylar humerus fractures (Gartland II/III) — typically two or three crossed or lateral 1.6 mm wires provide adequate provisional stability |
| 1.8–2.0 mm | Larger paediatric bones; adult wrist (carpal fixation — DRUJ stabilisation, radiocarpal provisional); olecranon tension band wiring; patella tension band wiring; provisional fixation during adult plating (humerus, forearm, tibia); guide wires for cannulated screw systems | Stiffer and stronger; sufficient for larger adult bones in a provisional role; the 2.0 mm wire is commonly used as the K-wire component of the tension band wiring construct for olecranon and patella fractures |
| >2.0 mm (Steinmann pins) | Skeletal traction (distal femoral — 4.0–6.0 mm; calcaneal — 4.0 mm; olecranon — 3.0–4.0 mm); temporary large bone fixation; external fixator half-pins (technically a different category but overlapping principle) | Steinmann pins for traction must pass through cancellous bone at a safe distance from neurovascular structures; distal femoral traction pin: 3–4 cm proximal to the lateral femoral condyle, lateral to medial to protect the popliteal vessels; olecranon traction pin: through the olecranon at the level of the tip, medial to lateral (medial insertion risks the ulnar nerve) |
Biomechanical Principles of K-Wire Fixation
- Load-sharing vs load-bearing: K-wires are NOT designed to be load-bearing implants; they provide provisional stability and maintain reduction while biological healing occurs, but they cannot resist the full mechanical loads of weight-bearing or unprotected mobilisation; the bone and soft tissues must share the load during healing; this is fundamentally different from plates (which are load-bearing in absolute stability constructs) and intramedullary nails (load-sharing within the medullary canal); K-wire fixation therefore REQUIRES post-operative immobilisation (splinting or casting) to protect the construct
- Modes of failure: K-wires fail by three principal mechanisms: (1) MIGRATION — smooth K-wires lack threads and can back out along the wire track under repeated loading (particularly parallel wires subjected to cyclic bending forces); migration is the most common mechanical complication; (2) BENDING — a single K-wire subjected to bending loads will deform plastically and then fail; the bending stiffness of a wire is proportional to the fourth power of its diameter (Euler`s beam bending formula) — doubling the wire diameter increases stiffness 16-fold; this is why two wires provide far greater rotational and bending stability than one; (3) BREAKAGE — fatigue failure from cyclic loading, most commonly at the bone-air interface at the skin surface; bending a wire repeatedly at the same point (during reduction manoeuvres) creates a stress riser and predisposes to breakage
- Divergent vs parallel wire configurations: TWO DIVERGENT wires (diverging at an angle from each other) provide superior resistance to rotational forces and translation compared to two parallel wires; the crossed-wire configuration (crossing inside the bone, diverging at the entry points) provides the greatest construct stability; parallel wires provide translational control but poor rotational stability; in supracondylar humerus fracture fixation, the optimal configuration is debated — crossed medial and lateral wires provide better rotational stability but the medial wire risks the ulnar nerve; two or three lateral divergent wires are safer (no medial wire) but provide slightly less rotational stability; three lateral divergent wires provide equivalent stability to crossed wires without the ulnar nerve risk
- Cortical purchase: a K-wire provides best fixation when it achieves bicortical purchase — passing through both cortices of the bone; unicortical wires (engaging only one cortex) are significantly less stable and more prone to migration and failure; in oblique fracture fixation (e.g. metacarpal or phalangeal spiral fractures), the wire should ideally cross the fracture perpendicular to the fracture plane to maximise compression and resistance to shear
- Wire-bone interface: smooth K-wires rely entirely on FRICTION between the wire surface and the bone for purchase; this friction is generated by the tight fit of the wire within the bone tunnel; the tighter the wire fits (appropriate wire-to-bone diameter ratio), the more friction and the less migration; threaded wires generate mechanical interlocking with the bone cancellous architecture in addition to friction, providing superior pull-out resistance; however, threaded wires are more difficult to reposition or remove and risk stripping the bone on removal
Insertion Technique
- Power insertion vs hand insertion: K-wires are most commonly inserted using a power drill (battery-powered or pneumatic); high-speed power insertion generates significant heat at the bone-wire interface from friction — this is the primary cause of THERMAL OSTEONECROSIS (heat-generated bone death around the wire track, leading to pin loosening, pain, and predisposition to pin tract infection); to minimise thermal necrosis: (1) use an appropriate drill speed — SLOW SPEED for dense cortical bone, faster speed for cancellous bone; (2) use SHARP wires (blunt wires generate more heat); (3) use an INTERMITTENT drilling technique (advance in short bursts, withdrawing to allow heat dissipation rather than continuous advance); (4) use IRRIGATION (saline lavage) during insertion through dense cortical bone; (5) avoid excessive pressure (let the drill do the work); hand chucks (Jacob`s chuck or T-handle) allow slower, more controlled insertion and generate less heat — preferred for fine wires and digital fixation
- Entry point and trajectory: the entry point should be planned fluoroscopically before insertion; the intended trajectory should be visualised on both AP and lateral views; a small stab incision is made at the entry point to avoid skin tenting (skin draped over a wire at an angle becomes ischaemic and necroses — a significant cause of pin site problems); the wire tip should be positioned carefully — in paediatric fixation, the wire must not pass across an open physis (growth plate) in an oblique direction, as this can cause physeal arrest
- Depth of insertion and wire protruding outside bone: after confirming correct position on fluoroscopy, the wire is cut leaving 5–10 mm protruding above the skin surface (if intended for later removal); this small protrusion allows later identification and retrieval; alternatively, the wire can be buried subcutaneously (bent back under the skin) — this reduces infection risk but requires a small incision for later removal; if the wire will be left for several weeks (e.g. after paediatric supracondylar fixation), burying the wire ends reduces pin tract infection rates in some series
- Cap application: after inserting the wire and confirming position, a small rubber or silicone cap is placed over the protruding wire end to prevent skin trauma, prevent snagging on dressings, and reduce pin tract contamination; the cap should be snug and should not be removed unnecessarily; daily pin site care (cleaning with chlorhexidine solution or sterile saline, changing the dressing) is standard practice to reduce pin tract infection rates during prolonged fixation
Clinical Applications by Region
| Region / Fracture | Wire Configuration | Key Technical Points | Duration of Fixation |
|---|---|---|---|
| Paediatric supracondylar humerus (Gartland II/III) | Two or three LATERAL divergent 1.6 mm wires (preferred — no ulnar nerve risk) OR crossed lateral + medial wires (better rotational stability but medial wire risks ulnar nerve); entry point for lateral wires at the lateral epicondyle | Lateral-only technique: all wires enter from the lateral side and diverge within the distal humerus — the wires must have sufficient DIVERGENCE (spread) to provide rotational stability; at least 2 mm separation at the fracture level; the most proximal lateral wire should engage the medial cortex for bicortical purchase; if medial wire used: flex the elbow to 90° and palpate the ulnar nerve before insertion; insert the medial wire through a small incision (NOT percutaneous) to directly visualise and protect the nerve; confirm position on AP and lateral fluoroscopy before cutting wires | 3–4 weeks in above-elbow backslab then wire removal in clinic (under LA or brief GA); early ROM immediately after removal |
| Paediatric lateral condyle humerus | Two divergent 1.6 mm lateral K-wires; entry point at the lateral condyle; wires diverge proximally into the lateral column of the distal humerus; do NOT cross the fracture with parallel wires (rotational instability) | The fracture must be anatomically reduced under fluoroscopy before wire insertion; the articular surface of the capitellum must be congruent; slight internal rotation of the forearm during reduction can help; wires must not enter the lateral joint space (capsule violation increases risk of avascular necrosis of the lateral condyle); confirm reduction on varus stress view fluoroscopy | 4–6 weeks in above-elbow backslab then wire removal; longer if delayed presentation (>7 days) |
| Metacarpal fractures (neck/shaft) | Transverse or oblique shaft: one or two 1.2–1.6 mm intramedullary (bouquet) wires OR crossed wires from the metacarpal head; neck fractures: retrograde intramedullary wires (bouquet pinning — two or three wires inserted retrograde from the metacarpal base into the medullary canal, impacting the fracture into reduction) | Bouquet pinning for metacarpal neck fractures: 1.2 mm wires introduced through a small cortical window at the metacarpal base; the wires are pre-bent slightly and rotate as they advance, filling the medullary canal; the wire ends splay at the metacarpal head and provide three-dimensional stability; a CAM (ceiling angle mount) of <30° for ring finger and <40° for little finger metacarpal neck fractures is acceptable without fixation; above these thresholds, fixation is indicated | 4–6 weeks; immediate finger mobilisation encouraged to prevent extensor tendon adhesion |
| Phalangeal fractures | Transverse proximal/middle phalanx: crossed wires (1.0–1.2 mm); longitudinal (intramedullary) wire (1.0 mm) for stable transverse fractures; oblique/spiral fractures: inter-fragmentary lag wires perpendicular to the fracture plane | Wires should be inserted with the MCPJ and PIPJ in the position of safe immobilisation (MCPJ 70–90° flexion; PIPJ in extension) to prevent collateral ligament contracture; avoid crossing the flexor tendon sheath with wires where possible; trans-articular wires (crossing a joint) must be removed before mobilisation | 3–4 weeks proximal phalanx; 3–6 weeks middle phalanx; early supervised mobilisation after removal |
| Mallet finger (bony mallet — distal phalanx avulsion) | Extension block pinning (Ishiguro technique): a 1.0 mm wire is inserted through the skin dorsal to the DIPJ in slight flexion, acting as a block that prevents the avulsed fragment from displacing further dorsally; a second wire is then passed longitudinally through the DIPJ to hold the joint in slight extension; the `blocking pin` prevents fragment displacement while the joint pin holds the reduction | Indicated for bony mallet with subluxation of the DIPJ (volar subluxation of the middle phalanx) or when the avulsion fragment involves >30–40% of the articular surface; the blocking wire must be positioned PROXIMAL to the avulsion fragment under fluoroscopy; this technique is technically demanding and requires careful fluoroscopic confirmation before tightening the reduction | 6 weeks fixation; wire removal under LA in clinic |
| Scaphoid (provisional fixation) | A 1.14 mm guidewire (the standard Herbert/Acutrak guide wire) is the K-wire equivalent used to provisionally hold the scaphoid in reduced position before cannulated screw insertion; placed from the distal pole along the central axis of the scaphoid under fluoroscopic guidance | The guidewire must be placed along the TRUE CENTRAL AXIS of the scaphoid on both AP and lateral fluoroscopy views; off-axis placement will result in eccentric screw positioning and inadequate compression; the guidewire provides provisional hold while the cannulated screw is advanced over it; the wire is removed after the screw is fully seated | Temporary only — removed intraoperatively after screw placement |
| DRUJ stabilisation (Galeazzi, distal radius) | A 2.0 mm K-wire is passed transversely across the DRUJ (from the distal radius into the distal ulna) with the forearm in the REDUCED position (supination for dorsal DRUJ dislocation) after ORIF of the radial fracture; the wire maintains the DRUJ in the reduced position while the TFCC heals | The wire is inserted parallel to the radiocarpal joint, passing through both the radius and the ulna; it must be confirmed on both AP and lateral fluoroscopy before cutting; the forearm is immobilised in supination; the wire is removed at 6 weeks; NO forearm rotation is permitted while the transfixation wire is in situ (the wire would break) | 6 weeks then removal; forearm rotation rehab immediately after |
| Ankle fractures (provisional/definitive) | Provisional: 1.6–2.0 mm wires to temporarily hold fracture reduction during plating (fibula, medial malleolus); Definitive (medial malleolus small avulsion): two 1.6 mm parallel wires with a tension band wire loop may be used when the fragment is too small for lag screws | Provisional wires should be placed to avoid the intended screw/plate trajectories; wire tips should not penetrate the articular surface; provisional medial malleolus wires are removed after lag screw insertion; never leave K-wires crossing a major weight-bearing joint as definitive fixation — the wire will fail under load | Provisional wires removed intraoperatively; small fragment definitive wires 6–8 weeks |
Tension Band Wiring — Principle & Applications
- The tension band wiring (TBW) principle: a fundamental biomechanical principle in orthopaedics; a fracture subjected to eccentric loading (where the muscle pull is applied on one side of the bone) experiences TENSION on one cortex and COMPRESSION on the opposite cortex; left unprotected, the tensile forces pull the fracture apart; the tension band wire is placed on the TENSION side of the fracture and converts this tensile force into COMPRESSION at the fracture site; as the patient contracts the muscle (e.g. triceps contracting the elbow — the tension is on the posterior aspect of the olecranon), the tension band wire on the posterior surface is loaded in tension — this tension is transmitted through the wire and converted into compressive force at the fracture articular surface; the fracture surfaces are pushed together with every muscle contraction, enhancing both stability and healing
- Where TBW applies in orthopaedics: (1) Olecranon fractures (Mayo Type IIA — non-comminuted, displaced, stable): two parallel 2.0 mm K-wires are inserted longitudinally through the olecranon (one in the medullary canal, one lateral); a figure-of-eight wire loop is passed through a transverse drill hole in the ulna distal to the fracture, looped around the proximal wire ends, and tightened; the muscle pull of the triceps generates the tensile force that the wire converts to compression; (2) Patella fractures (transverse, undisplaced or minimally displaced): two parallel wires through the patella + figure-of-eight wire through the quadriceps tendon and patellar tendon; quadriceps force (tending to distract the fracture) is converted to compression; (3) Medial malleolus avulsion fractures (when the fragment is too small for screws); (4) Greater tuberosity of humerus; (5) Lateral epicondyle avulsion
- Why TBW fails — and when NOT to use it: TBW is only biomechanically sound for TRANSVERSE fractures where the opposing cortex provides a stable fulcrum for the compression to act against; in COMMINUTED fractures, there is no intact opposing cortex — the TBW construct allows progressive collapse and varus rather than producing fracture compression; this is why comminuted olecranon fractures (Mayo Type IIB) require plate fixation rather than TBW; similarly, TBW applied to an oblique fracture does not produce pure compression — the oblique fracture plane converts the compressive force into a shear component, causing fracture displacement rather than compression; TBW is therefore specifically indicated for transverse fractures at the convex (tension) surface of a bone under eccentric muscle loading
- K-wire migration after TBW: the most common complication of TBW; the parallel K-wires in olecranon and patella TBW constructs tend to migrate PROXIMALLY (backing out through the triceps tendon or quadriceps tendon) under cyclic loading; this causes a painful subcutaneous prominence requiring removal; K-wire migration occurs in approximately 50–70% of TBW cases and is the primary reason for implant removal; techniques to reduce migration include burying the wire tips (folding the ends into the bone or bending them back), using a small flange on the wire end to act as a mechanical stop, and ensuring bicortical purchase of the wires
Complications of K-Wire Fixation
| Complication | Mechanism | Incidence | Prevention & Management |
|---|---|---|---|
| Pin tract infection | Bacterial colonisation of the pin-skin interface; bacteria travel along the wire into the bone; the most common complication of percutaneous K-wire fixation; incidence increases significantly with duration of pin in situ; superficial (cellulitis around the pin site) to deep (osteomyelitis) | 5–10% superficial pin tract infection for short-duration fixation (<4 weeks); up to 30% for prolonged fixation (>6 weeks); deep infection and osteomyelitis 1–3% | Prevention: daily pin site care (chlorhexidine cleaning); avoid loose wires (motion promotes bacterial ingress); minimise duration of fixation; use smallest adequate wire diameter; keep wire-skin angle perpendicular (tangential entry increases skin tenting and maceration); Management: superficial — oral antibiotics + increased pin site care; deep — wire removal, IV antibiotics, wound washout; osteomyelitis — wire removal, debridement, IV antibiotics, bone culture |
| Thermal osteonecrosis | Frictional heat generated during high-speed power insertion through dense cortical bone; temperatures >47°C for >1 minute cause osteocyte death; the resulting avascular bone ring around the wire track is a nidus for infection and wire loosening | Under-reported; clinical significance varies; most clinically significant when wires must remain in situ for prolonged periods | Prevention: use SLOW speed through cortical bone; use SHARP wires; intermittent drilling technique (advance then withdraw to dissipate heat); saline irrigation when drilling through dense diaphyseal cortex; hand chuck preferred for fine wires in digital surgery; do NOT hold wire during insertion (tactile feedback on heat transfer) |
| Wire migration | Smooth wires back out along the wire track under repeated loading; the wire moves proximally, distally, or rotates; intra-articular wire migration is the most serious variant | 10–30% for standard K-wire fixation; 50–70% for TBW constructs; higher with parallel wires than divergent configurations | Use divergent configurations where possible; ensure bicortical purchase; bend wire ends to act as a mechanical stop; consider buried technique; use threaded wires when prolonged fixation is anticipated (with awareness of removal difficulty); early removal once fracture united; intra-articular migration requires urgent wire removal and joint washout |
| Nerve injury | Direct injury to adjacent nerves during percutaneous insertion; the nerve most at risk depends on the wire location: ulnar nerve (medial wire in supracondylar humerus — see Gartland management); radial sensory nerve (dorsoradial hand/wrist wires); digital nerves and vessels (digital fixation); posterior interosseous nerve (proximal radius wires) | Ulnar nerve injury with medial K-wire in supracondylar fractures: 2–6% with percutaneous technique; reduced to <1% with mini-open technique; permanent nerve injury uncommon (<0.5%) | Thorough knowledge of regional anatomy before wire insertion; use mini-open technique (small incision to directly visualise nerve before inserting medial wire in supracondylar fractures); elbow flexion >90° when inserting medial supracondylar wire (moves ulnar nerve further posteriorly); stab incision and blunt dissection to bone before K-wire insertion for wires near neurovascular structures |
| Physeal arrest (paediatric) | A K-wire passed obliquely across an open physis (growth plate) can tether the physis and cause focal or complete growth arrest — particularly if the wire is left in situ for a prolonged period or if it is threaded (threaded wires should NEVER cross a physis) | Uncommon with smooth wires and short fixation duration; increased risk with oblique wire trajectory across the physis, large wire diameter, and prolonged fixation | Smooth wires cross the physis perpendicular (90°) if possible; threaded wires must NEVER cross a physis; remove wires as early as fracture stability permits (usually 3–4 weeks); post-fixation radiographic surveillance of the physis at 6 months to detect early arrest; physeal bar resection for small focal bars if detected early |
| Wire breakage | Fatigue failure of the wire from cyclic loading or from repeated bending at the same point (during reduction manoeuvres); broken wires within bone can be difficult to retrieve and may require open surgery; a broken wire in a joint requires urgent retrieval | Rare with appropriate technique; higher risk with: excessively thin wires for the application; wires that have been repeatedly bent during reduction attempts; retained wires beyond the expected duration; wires subjected to joint loading | Use appropriately sized wires for the application; avoid repeated bending of the same wire during reduction; replace wires that have been excessively manipulated; plan removal before mechanical failure; if broken wire is in a joint — urgent retrieval to prevent articular damage; if in bone and asymptomatic — may be observed; radiograph pre-operatively to locate broken fragments before removal attempt |
Wire Removal
- Timing: K-wires should be removed once the fracture has achieved sufficient healing to maintain reduction without the wire support; this varies significantly by bone, patient age, and fracture type: paediatric supracondylar humerus — 3–4 weeks (rapid paediatric healing); lateral condyle humerus — 4–6 weeks; phalangeal fractures — 3–4 weeks; metacarpal fractures — 4 weeks; TBW (olecranon, patella) — 6–12 months (after confirmed union) or earlier if symptomatic migration; DRUJ transfixation wire — 6 weeks; provisional wires during ORIF — intraoperatively, removed before wound closure
- Technique: protruding wires with a wire cap are removed by grasping the wire firmly with a wire-pulling pliers or heavy needle holder and extracting with a steady axial pull combined with a gentle rotating motion (to overcome the friction between the wire and bone); the rotating motion reduces the pull-out force required and reduces the risk of fracture displacement during extraction; for buried or subcutaneous wires, a small skin incision is required over the bent wire tip; for intramedullary wires (bouquet pinning), a small cortical window at the insertion site is used to grasp and extract the wire
- Resistance to removal: a K-wire that is difficult to remove has usually become incorporated into callus or has a threaded tip that has engaged the bone; excessively forceful removal risks: fracture at the original fracture site; periosteal avulsion; nerve injury from traction; if a wire cannot be removed by gentle pulling and rotation, obtain a fluoroscopic image to confirm the wire position and look for callus incorporation or thread engagement; consider operating theatre removal under GA if clinic removal is not possible safely
- Buried wires and permanent retention: in some applications, K-wires are deliberately left permanently (e.g. K-wire arthrodesis of small joints such as DIP joint arthrodesis for mallet finger; CMC joint arthrodesis; small joint fusions in rheumatoid arthritis); in these applications, the wire is buried subcutaneously with the tip bent back to prevent migration; broken wire fragments that are asymptomatic, not in a joint, and are stable may be observed rather than retrieved if removal poses greater risk than retention
Exam Pearls
- K-wire diameter and stiffness: bending stiffness is proportional to the FOURTH POWER of the radius (r⁴); doubling the wire diameter increases stiffness 16-fold; this is why using the correct wire size for the application is critical — too thin = insufficient stability; too thick = unnecessary trauma and thermal risk
- Divergent vs parallel: two DIVERGENT wires provide superior rotational stability compared to two parallel wires; the crossed-wire configuration provides the greatest 3D stability; three lateral divergent wires for supracondylar fractures provide equivalent stability to crossed wires without ulnar nerve risk
- TBW principle: placed on the TENSION side of an eccentrically loaded fracture; converts TENSILE force to COMPRESSIVE force; only works for TRANSVERSE fractures with an intact opposing cortex; fails in comminuted fractures (no fulcrum for compression); K-wire migration in 50–70% of TBW — most common complication requiring implant removal
- Thermal necrosis prevention: SLOW speed for cortical bone; SHARP wires; INTERMITTENT technique; SALINE irrigation; avoid continuous pressure; hand chuck for digital fixation
- Ulnar nerve and medial K-wire in supracondylar fracture: ulnar nerve injury 2–6% with percutaneous technique; MINI-OPEN technique for medial wire (small incision, direct nerve visualisation) reduces risk to <1%; alternatively, three lateral divergent wires avoid the medial wire entirely
- Pin tract infection: most common K-wire complication overall; 5–10% superficial; daily chlorhexidine pin care; remove wires at earliest safe opportunity; loose wires promote infection — a loose wire must be removed not just tightened
- Physeal arrest: threaded wires MUST NOT cross an open physis; smooth wires may cross a physis perpendicularly for short periods; remove smooth wires promptly; surveillance radiographs at 6 months post-removal to detect early physeal arrest
- Wire removal technique: steady axial pull combined with ROTATING motion reduces pull-out force and risk of displacement; if resistance encountered — fluoroscopy first; GA in theatre if clinic removal unsafe