Die-Punch Fractures

Definition. A die-punch fracture is a depressed articular fracture of the lunate facet of the distal radius. The name is borrowed from metalworking: under axial load the lunate is the punch and the radius the die, and the hard lunate is driven into the softer cancellous bone beneath the facet, leaving a depressed articular fragment. It is the hidden fracture of the distal radius, easily missed on plain films.

How common. Die-punch fragments occur in approximately 20-30% of intra-articular distal radius fractures, and are often part of a complex distal radius fracture pattern. The age distribution is bimodal: young adults after high-energy trauma, and the elderly with osteoporotic bone.

Mechanism. A direct axial load, which is what distinguishes the injury from rotational mechanisms. It is most often high-energy:

• Fall from height, motor vehicle accident, motorcycle crash
• Sports with an axial load on the wrist - wakeboarding, snowboarding, contact sports

The lunate facet. The ulnar half of the distal radius articular surface, concave in both the sagittal and coronal planes, articulating with the proximal pole of the lunate. It carries approximately 60% of the axial load crossing the wrist. Its medial border is the sigmoid notch, which articulates with the ulnar head.

The scaphoid facet. The radial half of the articular surface: triangular, slightly convex in the sagittal plane, articulating with the proximal pole of the scaphoid. The interfacet ridge separates the two facets.

Why a depressed facet matters. A surface carrying 60% of the wrist's load cannot be left with a step in it. Depression of the lunate facet leads to:

• Altered radiocarpal biomechanics
• Concentrated stress at the margins of the step-off
• Progressive cartilage degeneration
• Post-traumatic radiocarpal arthritis

Beneath the cartilage. The cancellous bone under the lunate facet is organised in layers: a dense subchondral plate supporting the cartilage, a trabecular network oriented to resist axial compression, a metaphyseal transition zone of less dense bone, and a watershed zone of reduced vascularity that is prone to necrosis. It is into this metaphyseal cancellous bone that the punched fragment is driven, and from which it must later be levered back up.

Blood supply. The radial artery supplies the volar and dorsal surfaces and the ulnar artery contributes to the ulnar aspect; the anterior interosseous artery feeds the palmar metaphysis and the posterior interosseous artery the dorsal metaphysis. An extensive periosteal anastomotic network around the metaphysis gives the region generally good healing potential, although comminuted fragments may have a compromised supply.

The volar side. The volar radiocarpal ligaments may be disrupted in severe injuries. Pronator quadratus overlies the volar surface, flexor carpi radialis passes radially and flexor pollicis longus centrally.

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The dorsal side. The extensor compartments pass dorsally over the radius, the dorsal radiocarpal ligaments provide carpal stability, and Lister's tubercle is the landmark for extensor pollicis longus.

History. The mechanism is an axial load, and the energy behind it is the first thing to establish. The answers that change management:

• Energy of the injury - height of the fall, speed of the vehicle
• Position of the wrist at impact
• Associated injuries suggesting polytrauma
• Hand dominance and occupational demands
• Pre-existing wrist pathology

Inspection and palpation. The wrist can look deceptively benign. Swelling over the distal radius is often less dramatic than with a displaced fracture, there is minimal deformity, and ecchymosis may be delayed. Tenderness is diffuse over the distal radius with point tenderness over the dorsal lunate facet; palpate the DRUJ as well.

Movement. Range of motion is significantly limited by pain in the acute setting. Loss of forearm rotation suggests DRUJ involvement.

Neurovascular assessment. Document median nerve sensation in the radial three and a half digits, because carpal tunnel symptoms may develop as the wrist swells. The radial pulse is usually preserved; check capillary refill in the digits.

Special tests. The Watson test (scaphoid shift) looks for scapholunate ligament injury, a common association in high-energy wrist trauma. The piano key test assesses ulnar head stability at the DRUJ, compared with the other side. Grip strength is usually not assessable acutely because of pain, but it is the baseline for rehabilitation.

Differential diagnosis. A die-punch fragment can be subtle and is easily confused with, or coexists with, other distal radius and carpal injuries. Examination alone will not separate them; the discriminating tests are in the table.

Radiographs. The PA view may show only subtle articular irregularity, the lateral can reveal dorsal cortical comminution, and oblique views add another perspective on the fracture lines. Three signs should make you look harder:

• Double cortical sign - the depressed and non-depressed articular surfaces overlap
• Loss of the normal concavity - the lunate facet appears flattened
• Associated fracture lines - sagittal or coronal splits

Why radiographs are not enough. Plain films underestimate the depression, often by several millimetres. They miss pure articular injuries where the fragment is depressed without a cortical break, and overlapping fragments obscure the degree of comminution.

The standard parameters, and why they are the wrong ones here. Measure and quote these on every distal radius film, because an examiner will ask and because you cannot describe a malunion without them:

CT. Mandatory for any suspected articular involvement or high-energy mechanism, for preoperative planning in every operative case, and to assess the reduction afterwards. Ask for slices of 1mm or less with sagittal, coronal and 3D reconstructions, and compare the contralateral wrist for subtle depressions. Four things come off the scan:

• Step-off - the articular incongruity, measured
• Fragment size - which decides the fixation options
• Degree of comminution - which predicts the need for bone graft
• Dorsal versus volar location - which determines the surgical approach

Look for an associated scapholunate ligament injury on the axial cuts while you are there.

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MRI. For suspected ligamentous injury, scapholunate assessment when arthroscopy is unavailable, and TFCC evaluation. It shows ligament disruption, the bone marrow oedema pattern and cartilage injury.

Arthroscopy. The gold standard for ligament assessment: it shows the articular surface reduction directly and evaluates the TFCC and intercarpal ligaments. It is also therapeutic, assisting reduction under vision, debriding loose bodies, and allowing ligament repair or pinning.

Algorithm

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The decision. Depth of the step on CT, the pattern of the fracture around it, and what the patient needs from the wrist. The table is the short version; the tabs below give the detail.

Dorsal ApproachVolar Approach

Set-up. Supine with an arm table, tourniquet on the upper arm at 250-300 mmHg, and a traction tower if it will help.

Incision. A dorsal longitudinal incision over Lister's tubercle, approximately 5-6 cm centred on the wrist and extended proximally as needed for fragment access. Then:

1. Incise the extensor retinaculum between the third and fourth compartments
2. Identify and protect the EPL tendon
3. Retract EDC ulnarly and EPL radially
4. Elevate the capsule as an L-shaped flap, ligament-sparing if possible

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Reduction. The dorsal approach gives a direct view of the lunate facet articular surface: assess the depth of the depression and the fragment size, and look for loose osteochondral fragments. Then elevate:

1. Use a small periosteal elevator or dental pick
2. Lever the fragment through a metaphyseal window if needed
3. Reduce it to the level of the adjacent cartilage
4. Confirm the reduction with direct vision and fluoroscopy

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Bone graft. Elevation leaves a metaphyseal void, so assess it and pack cancellous graft, autograft (iliac crest or distal radius) or a synthetic substitute, immediately after elevation. The graft is the subchondral support that stops the elevated fragment collapsing.

Fixation. K-wires of 1.1 or 1.25 mm capture the reduced fragment to the metaphysis; use two or three for rotational control. A low-profile dorsal plate with subchondral screws supports the articular fragment; consider locking screws for osteoporotic bone.

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Closure. Repair the capsule, close the retinaculum loosely to allow tendon glide, standard skin closure, and a splint in neutral.

Who. A volar die-punch component, a combined fracture that needs volar plating, or surgeon preference when the dorsal approach is not required.

Set-up and incision. Supine with an arm table, the arm supinated and a tourniquet on the upper arm. The incision runs over the FCR tendon from the wrist crease to 5-6 cm proximal, with a curvilinear extension distally if needed. Then:

1. Incise the FCR sheath and retract the tendon radially
2. Identify and protect the radial artery
3. Incise pronator quadratus along its radial border
4. Elevate PQ subperiosteally from ulnar to radial

Reducing a volar die-punch. Direct visualisation is possible from this side: elevate the fragment to the articular level and graft the void before plating.

The dorsal die-punch from the volar side. You cannot see the dorsal articular surface, so the reduction is judged on fluoroscopy, and the fragment may have to be elevated through a volar cortical window.

The volar locking plate. A standard volar distal radius plate. The distal row of screws must capture the die-punch fragment, aimed subchondrally to support it, and the lateral fluoroscopic view must confirm that no screw has penetrated the joint.

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The volar lunate facet - the critical corner a standard plate does not reach

The commonest catastrophic failure after volar plating of a lunate-facet injury is not failure of the plate, but failure to have captured the fragment in front of it. The volar ulnar corner of the lunate facet, the "critical corner", is a small marginal fragment that carries the short radiolunate ligament and therefore the volar restraint of the entire carpus. It usually lies distal to the watershed line, and a volar locking plate must be seated proximal to that line to avoid flexor tendon attrition. The two requirements are in direct conflict: the plate cannot be where the fragment is.

What happens when it is missed is rapid and unmistakeable. The carpus subluxes volarly with the fragment over the first two weeks, the lateral film shows the lunate no longer centred under the radial shaft axis, and by the time it is recognised the salvage is far harder than the original operation. It typically presents as "early loss of reduction" on a routine two-week film in a case that looked perfect on the table.

How to avoid it:

• Look for it on the pre-operative sagittal CT, specifically on the ulnar-most sagittal cuts. It is easily invisible on plain films.
• Measure it. If the fragment is too small for the distal screw row to engage - broadly, under about a centimetre in its dorsal-volar dimension - assume a standard plate will not hold it.
• Buttress it separately: a small hook plate over the volar rim, a dedicated volar-ulnar fragment-specific plate, a spring wire, or a tension-band suture through the volar ligament. Adding a second, smaller implant is the correct answer, not lengthening the screws.
• Check it before leaving theatre: a true lateral confirming the carpus is centred, and stress the wrist under fluoroscopy.

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Plate position and the Soong grade. Having pushed the plate proximally to clear the volar rim, you now have to prove it. Soong grading measures exactly that, and it is the accepted way to describe plate prominence on a post-operative lateral. Draw a line tangential to the most volar extent of the volar rim, parallel to the volar cortex of the radial shaft; then:

• Grade 0 - the plate does not extend volar to that line
• Grade 1 - the plate is volar to the line but remains proximal to the volar rim
• Grade 2 - the plate lies directly on or distal to the volar rim

In the original two-cohort study, the institution using a more prominent plate had Grade 2 prominence in 46 of 73 wrists (63%) and three flexor tendon ruptures (4%), two of which were Grade 2. The comparison institution, using a lower-profile design, had no Grade 2 plates and no ruptures across 95 wrists.

State the Soong caveat as well as the grade

The honest reading is the one the authors themselves gave: "further studies are needed before recommending one plate over another", and the two groups differed by institution and surgeon as well as by implant. So the finding to quote is not that a particular plate is dangerous, but the principle: prominence at the watershed line is where the flexor tendons, flexor pollicis longus first, lie closest to metal, and that is what should be avoided. A Grade 2 plate is a reason to consider elective removal once the fracture has united, particularly in a patient reporting volar wrist ache on resisted thumb flexion, because the alternative presentation is an attritional FPL rupture that presents late and repairs poorly.

Note the tension with the critical corner above: the same watershed line that you must stay proximal to for tendon safety is the line the volar lunate facet fragment sits distal to. When both problems coexist, the answer is a proximally seated plate plus a separate low-profile buttress for the corner, not one plate pushed distally to do both jobs.

Closure. Repair pronator quadratus if possible, close in layers, and apply a volar splint.

Combined fixation. Uncommon, but appropriate when a dorsal fragment cannot be reduced or supported from the volar side, and the volar approach is often combined with other techniques when the die-punch is part of a larger fracture pattern.

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On the table. Three things go wrong intraoperatively. Iatrogenic fracture during fragment elevation is avoided by gentle technique and the right instruments, and managed with additional fixation if it happens. Screw penetration of the joint causes arthritis, so measure carefully and check on fluoroscopy; a penetrating screw is removed and replaced with a shorter one. In the dorsal approach the EPL is the tendon most at risk; retract carefully, protect it with vessel loops, and repair primarily if it is injured.

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Early. Infection runs at 1-3% and is treated with intravenous antibiotics, with debridement if deep; dehiscence is more common dorsally and is managed with local wound care; a significant haematoma is evacuated. Hardware problems declare themselves early: a K-wire that is backing out is removed, screws loosen more often in osteoporotic bone, and loss of reduction may need revision surgery. Nerve problems are the median nerve (carpal tunnel syndrome, decompressed if needed), the superficial radial nerve (paraesthesiae, which usually resolve) and the posterior interosseous nerve (motor weakness, observed).

Late. Post-traumatic arthritis is the most significant long-term complication, related to a residual step-off greater than 2mm, and may end in a salvage procedure (fusion or arthroplasty). Articular malunion causes the arthritis; an extra-articular component may limit function, and a corrective osteotomy is considered if it is symptomatic. Dorsal plates often require removal, prominent hardware causes extensor tenosynovitis, and a second operation should be planned for. CRPS follows 5-10% of distal radius fractures, and needs early recognition, treatment and a multidisciplinary approach.

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The first two weeks. A volar resting splint with the wrist in neutral, including the forearm, and the fingers moving from day one. The hand stays above heart level when resting, on pillows or in a sling when sitting, which matters most in the first 72 hours; multimodal analgesia and ice control pain and swelling. Neurovascular checks run every 4 hours initially, watching for compartment syndrome and the early signs of infection. Radiographs, AP and lateral, are taken before discharge to confirm the reduction and implant position.

The wound. The first dressing change is at 48-72 hours by the surgeon, with attention to any K-wire sites. Sutures or staples come out at 10-14 days, earlier if the wound is well healed, with steri-strips for support.

Follow-up. Rehabilitation is tailored to the fracture pattern, the stability of the fixation and the patient, but the review schedule is standard:

What recovers. Wrist flexion reaches 80-90% of the contralateral side by 6 months and extension 85-95%; forearm rotation usually recovers fully; grip strength reaches 80% of the contralateral side by 12 months. DASH scores typically return to near-normal by 12 months, and 80-90% of well-treated patients return to their previous level of activity. Satisfaction correlates with the quality of the articular reduction.

What predicts it. The quality of the articular reduction is the key predictor, and the rest of the list is the patient and the injury:

• Favourable - step-off under 1mm achieved at surgery, younger patient, isolated injury, compliance with rehabilitation, good bone quality
• Unfavourable - residual step-off greater than 2mm, significant comminution, associated ligamentous injury, osteoporotic bone, high-energy mechanism with soft tissue injury

Arthritis. The risk is directly related to the residual articular incongruity, and so is how soon it arrives:

Salvage. The options once arthritis is established:

• Wrist arthroscopy - debridement for early arthritis
• Partial wrist fusion - four-corner fusion preserving some motion
• Total wrist fusion - reliable pain relief at the cost of motion
• Proximal row carpectomy - motion-preserving salvage
• Total wrist arthroplasty - selected patients

Return to work and sport. Sedentary work at 2-4 weeks and light manual work or light duties at 6-8 weeks; full duties at 12 weeks, with heavy manual work at 12-16 weeks. Non-contact sport at 8-12 weeks, contact sport at 4-6 months with a protective splint initially, and high-impact activities at 6 months or more.

Global Epidemiology

Distal radius fractures are among the most common fractures worldwide, with a bimodal distribution affecting children and the elderly while remaining significant in young adults. Reported population data over recent decades show an overall rising prevalence in both paediatric and elderly groups (Nellans, Kowalski and Chung, Hand Clin 2012, PMID 22554654). Die-punch (lunate-facet depression) patterns cluster in the high-energy, axial-load young-adult subgroup and within complete intra-articular (AO 23-C) fractures. Knirk and Jupiter studied 43 such intra-articular fractures in 40 young adults (mean age 27.6 years) and reported radiographic post-traumatic arthritis in 65% overall (PMID 3722221).

Major Guidelines, Side by Side

The single highest-quality message across guidelines is that for operatively treated distal radius fractures, fixation technique should follow the fracture pattern rather than any one implant, because randomised evidence shows no clinical or radiographic difference between techniques beyond 3 months.

Registry & Outcome Evidence

There is no dedicated international registry for die-punch fractures specifically; high-level outcome data derive from intra-articular distal radius fracture cohorts and randomised trials feeding the guidelines above. The enduring registry-equivalent evidence remains the dose-response relationship between residual articular incongruity and arthritis first quantified by Knirk and Jupiter (91% arthritis with incongruity vs 11% with a congruous joint, PMID 3722221), reinforced by imaging studies showing CT changes the operative plan (Harness et al., JBJS Am 2006, PMID 16757766).

Practice Variation

• Imaging access: CT with sagittal/coronal and 3D reconstruction is routine in high-resource centres for any suspected articular involvement; in limited-resource settings reliance on plain films persists and risks underestimating depression.
• Implant availability: fragment-specific systems, low-profile dorsal plates and volar locking plates are widely available in high-income settings; elsewhere a single volar locking plate or K-wire constructs predominate, which may inadequately support an isolated dorsal die-punch.
• Rehabilitation: hand-therapy-led early mobilisation is standard where services exist; regional and rural patients may depend on telehealth or staged review.
• Surgical threshold: the under-2mm articular step-off threshold is near-universally cited, but the operative-versus-nonoperative decision is increasingly individualised by patient age and functional demand rather than radiographic parameters alone, consistent with the AAOS/ASSH 2020 CPG.

Understanding these key concepts will help with exam success.

The evidence supports anatomic reduction with stable fixation and bone grafting as needed, with imaging and implant selection driven by the articular fracture pattern.