Untreated wrist instability – a torn scapholunate ligament or an unhealed scaphoid fracture – can slowly lead to a predictable pattern of arthritis called SLAC or SNAC wrist. Once arthritis sets in, the two main operations, proximal row carpectomy (PRC) and four-corner fusion (4CF), relieve pain about equally well; PRC tends to keep more movement with fewer complications, while 4CF is needed when the midcarpal joint is worn. Catching instability early may avoid arthritis altogether.
This guide from the hand and wrist team at Sports Orthopedics Institute explains how these conditions develop, the options at each stage, and what the comparative studies and trials show.
Key takeaways
- Early instability can often be treated with ligament repair or reconstruction before arthritis develops.
- Once SLAC/SNAC arthritis is established, PRC and 4CF both reliably reduce pain.
- The largest meta-analysis (3,174 wrists) found PRC gave better wrist extension and pain scores, with 5.2% of PRC wrists vs 11% of 4CF wrists later needing total wrist fusion.
- An earlier meta-analysis including two small randomised trials found no significant difference between the operations.
- No high-quality randomised trial exists yet; the Finnish PROOF trial is under way.
- PRC requires healthy cartilage on the capitate and lunate fossa; when the midcarpal joint is arthritic, 4CF is usually chosen.
- Age alone should not decide: a Mayo Clinic series in patients under 45 found similar long-term survival with both.
From Instability to Arthritis: SLAC and SNAC Wrist
Both conditions start with the scaphoid – the key link between the two rows of wrist bones – losing its connection to the rest of the wrist.
- SLAC (scapholunate advanced collapse): the scapholunate ligament, which binds the scaphoid to the lunate, is torn by a fall or wears out. The scaphoid and lunate drift apart and move abnormally.
- SNAC (scaphoid nonunion advanced collapse): a scaphoid fracture fails to heal. The two fragments move separately, with a similar effect.
In both, abnormal loading wears the cartilage in a predictable sequence, while the joint between the radius and lunate (radiolunate joint) is usually spared until very late.
|
Stage |
Where the arthritis is |
Typical options |
|---|---|---|
|
I |
Tip of the radius (radial styloid) and scaphoid |
Radial styloidectomy, with ligament or scaphoid treatment where possible |
|
II |
Whole radioscaphoid joint |
PRC or 4CF |
|
III |
Plus the capitolunate (midcarpal) joint |
4CF; PRC usually avoided |
|
IV |
Rare widespread arthritis, including the radiolunate joint |
Total wrist fusion or replacement |
Treating Instability Before Arthritis Sets In
If the scapholunate ligament tear or scaphoid fracture is treated before the cartilage wears, the wrist can often be saved without a salvage operation.
Scaphoid fractures
A scaphoid fracture that has not healed (nonunion) can usually be treated with bone grafting and fixation with a screw. Healing the fracture removes the cause of SNAC.
Scapholunate ligament injuries
- Acute tears (within a few weeks) may be repaired directly, often with arthroscopic assistance.
- Chronic tears without arthritis are treated with ligament reconstruction. Techniques include capsulodesis (using a strip of the joint capsule), tenodesis such as the three-ligament tenodesis (3LT, using a strip of a wrist tendon), and bone–ligament–bone grafts.
What the evidence shows: no single technique is clearly best. A meta-analysis of 40 studies (978 wrists) found tenodesis corrected the gap and angle between the scaphoid and lunate better than capsulodesis, with some improvement in grip and function (Hand, 2020). In a multicentre study of 203 patients after 3LT, about four in five had substantial improvements in pain and function at one year, but 11% were worse than before surgery (Mass General summary).
Once arthritis is present, ligament reconstruction is no longer suitable, and a salvage procedure is considered.
The Salvage Operations
Salvage operations remove or bypass the worn joints while keeping part of the wrist's movement.
Proximal row carpectomy (PRC)
The surgeon removes the scaphoid, lunate and triquetrum. The capitate bone then sits directly in the lunate fossa of the radius, forming a new joint. No fusion or hardware is needed, and movement can start early. Requirement: healthy cartilage on the head of the capitate and in the lunate fossa.
Scaphoid excision and four-corner fusion (4CF)
The surgeon removes the scaphoid and fuses the lunate, capitate, hamate and triquetrum into one block with screws or a circular plate. Load is transferred through the healthy radiolunate joint. Advantage: it can be used when the capitolunate joint is arthritic. Trade-off: the bones must fuse, which needs longer immobilisation, and hardware can cause problems.
Other partial fusions
Two-corner (capitolunate) and three-corner fusions and radioscapholunate fusion with distal scaphoid excision are used in selected cases, with less evidence than PRC and 4CF.
Modifications
When the capitate cartilage is mildly damaged, some surgeons add an interposition layer (such as joint capsule or graft) to PRC, or use capitate resurfacing. Long-term data on these modifications are limited.
PRC vs Four-Corner Fusion: What the Trials and Meta-Analyses Show
Both operations work; the evidence slightly favours PRC on movement and complications, but the quality of the evidence is limited.
Randomised trials
Only small randomised trials exist. A Brazilian trial of 20 patients with healthy midcarpal joints found both operations reduced pain, with no significant difference in function or movement between them (Clinics, 2011). The Finnish PROOF trial – a double-blinded, multicentre randomised trial of 84 patients with SLAC/SNAC stage II–III – is now recruiting to test whether PRC is non-inferior to 4CF, with follow-up to 10 years (Trials, 2023).
Meta-analyses
|
Study |
Wrists |
Main findings |
|---|---|---|
|
3,174 (61 studies) |
PRC: better extension, ulnar deviation and pain scores. No difference in grip. Later total wrist fusion: 5.2% PRC vs 11% 4CF. 4CF non-union 8.9%; hardware removal 2.2% |
|
|
7 studies, ≥5-year follow-up |
PRC better overall for range of motion and complications; no difference in conversion, grip, pain or function scores |
|
|
15 studies (incl. 2 RCTs) |
No significant difference in any outcome; high risk of bias across studies |
|
|
1,066 PRC, 2,771 4CF |
Larger flexion-extension arc with PRC; similar grip; authors preferred PRC for its lower complication rate |
Large registry-type studies
- In 1,168 patients with stage II SLAC/SNAC, there was no difference in conversion to total wrist fusion at 10 years, but PRC was much less likely to need a secondary operation (Healio, 2020).
- A large matched database analysis found higher one-year infection and conversion-to-fusion rates after 4CF than PRC (AAOS 2025 abstract).
Bottom line: for stage II disease with healthy capitate cartilage, PRC gives at least equivalent pain relief and function, more movement and fewer secondary operations. Grip strength is similar.
Long-Term Durability and the Question of Age
PRC lasts well in most people, but younger patients and heavy manual workers have a higher risk of later failure – though recent evidence suggests 4CF does not clearly do better in these groups.
PRC at 20 years
In a study of 17 wrists followed for a minimum of 20 years (average 24), 65% needed no further surgery. Those who kept their PRC had a flexion-extension arc of 68° and grip strength of 72% of the other side, and all returned to their original jobs. Arthritic changes on X-ray did not correlate with satisfaction. The risk of failure was higher in younger patients, levelling off at about age 40 (Wall et al., J Hand Surg 2013).
Not all long-term series are as favourable: a study of 81 patients followed for an average of almost 20 years reported that many still needed daily pain medication and could not return to manual labour (Ali et al., Hand 2012). A systematic review concluded PRC is durable long term, with poorer results in heavy manual workers (J Wrist Surg, 2012).
Young patients
A Mayo Clinic series of patients under 45 followed for a mean of 15 years found similar survival free of total wrist fusion, complications, pain and function after PRC and 4CF; 4CF had slightly higher grip strength (65% vs 53% of the other side), which did not reach statistical significance (AAHS, 2016). Arthritis developed over time after both: radiocapitate after PRC and radiolunate after 4CF.
What this means: age matters, but it should be one factor in a wider discussion, not the deciding rule.
Which Operation for Which Patient?
|
Factor |
Favours PRC |
Favours four-corner fusion |
|---|---|---|
|
Stage |
Stage II |
Stage III (capitolunate arthritis) |
|
Capitate head and lunate fossa cartilage |
Healthy |
Worn on the capitate (lunate fossa must be healthy for either) |
|
Priority |
Maximum movement; avoiding hardware and fusion healing |
Preserving carpal height; when PRC is not suitable |
|
Recovery |
Wants earlier movement and return to activity |
Can accept longer immobilisation |
|
Age and work |
Generally over 35–40; lower physical demands, though younger patients are not excluded |
Younger heavy manual workers are often considered for 4CF, though evidence of better durability is limited |
|
Previous surgery |
– |
Can salvage a failed PRC |
Wrist arthroscopy before or at the time of surgery is often used to inspect the cartilage directly and confirm which operation is suitable.
Recovery and Rehabilitation
PRC allows earlier movement because there is no fusion to wait for; 4CF needs the bones to unite first.
|
|
Proximal row carpectomy |
Four-corner fusion |
|---|---|---|
|
Splint or cast |
About 2–4 weeks |
About 6–8 weeks or until X-rays show fusion |
|
Start of movement exercises |
Around 2–4 weeks |
Once fusion is progressing |
|
Strengthening |
From about 6–8 weeks |
From about 8–12 weeks |
|
Return to most activities |
About 3–4 months |
About 4–6 months |
|
Full strength |
6–12 months |
6–12 months |
Hand therapy is essential after both. Expect a wrist that moves less than normal – roughly half the normal range is common – but is much less painful. Grip strength usually recovers to around 60–75% of the other side.
Other Options
Non-surgical care
Splints, activity modification, anti-inflammatory medicines and hand therapy can control symptoms for years in some people. A steroid injection can give temporary relief and also help confirm that the wrist joint is the source of pain. These measures do not stop the arthritis progressing.
Wrist denervation
Cutting the small sensory nerves to the wrist (such as the posterior and anterior interosseous nerves) can reduce pain without changing wrist mechanics. Results vary and relief may be partial. It can be done alone or combined with another operation.
Total wrist fusion
Fusing the whole wrist gives reliable pain relief and strength but removes wrist bending. It is the usual fallback when a motion-preserving operation fails, or for advanced (stage IV) arthritis.
Total wrist replacement
A joint replacement preserves some movement and may suit selected lower-demand patients, but durability in younger, active people remains a concern, and lifting restrictions apply.
Questions to Ask Your Surgeon
- Is my wrist unstable without arthritis, or is arthritis already present? What stage?
- Can the ligament or scaphoid still be repaired?
- What does the cartilage on my capitate and lunate fossa look like? Will you check it arthroscopically?
- Do you recommend PRC or four-corner fusion for me, and why?
- How many of these operations do you perform each year?
- What are the options if the operation does not work?
- How long will I be in a splint, and when can I return to work?
How Sports Orthopedics Institute Can Help
Our hand and wrist team treats the full range of wrist instability and arthritis, from early ligament injuries to salvage surgery.
- Detailed assessment with X-rays, CT, MRI and, where needed, diagnostic wrist arthroscopy
- Scaphoid fracture fixation and scapholunate ligament repair and reconstruction
- Proximal row carpectomy, four-corner fusion, denervation and total wrist fusion
- Specialist hand therapy throughout recovery
Persistent wrist pain after a fall or an old scaphoid fracture? Book a consultation with our wrist specialists in Bengaluru.
Frequently Asked Questions
What is the difference between SLAC and SNAC wrist?
SLAC follows a torn scapholunate ligament; SNAC follows a scaphoid fracture that did not heal. Both lead to the same pattern of arthritis and are treated in similar ways.
Can wrist instability be fixed before arthritis develops?
Often, yes. Acute ligament tears can be repaired, chronic tears without arthritis can be reconstructed, and scaphoid nonunions can be grafted and fixed – which may prevent SLAC or SNAC.
Is proximal row carpectomy better than four-corner fusion?
For stage II disease with healthy capitate cartilage, the largest meta-analysis favours PRC for movement, pain scores and fewer later fusions, with similar grip. Other reviews found no significant difference. When the midcarpal joint is arthritic, 4CF is usually needed.
Has a randomised trial compared them?
Only small ones so far, showing similar results. A larger double-blinded trial (PROOF) is under way in Finland.
Am I too young for PRC?
Younger patients have a higher risk of later failure after PRC, levelling off at around 40. However, a Mayo Clinic series in patients under 45 found similar long-term results with PRC and 4CF, so age should be weighed alongside cartilage condition and work demands.
How long is recovery?
About 3–4 months to most activities after PRC and 4–6 months after 4CF, with strength continuing to improve for up to a year.
Will I get my full movement back?
No. Both operations trade some movement for pain relief; roughly half the normal range is typical, with PRC usually keeping a little more extension.
Will arthritis come back?
X-ray changes often develop over time – at the new radiocapitate joint after PRC and the radiolunate joint after 4CF – but many people with these changes remain comfortable.
Can I return to manual work?
Many people do, though heavy manual work is associated with poorer long-term results after PRC. Discuss your job demands with your surgeon.
What if the operation fails?
A failed PRC can be converted to four-corner or total wrist fusion; a failed 4CF can be converted to total wrist fusion. Wrist replacement is an option for selected patients.
References
- Hones KM, et al. Four-corner fusion versus proximal row carpectomy for SLAC and SNAC wrist: a systematic review and meta-analysis. 2024.
- The never-ending battle between proximal row carpectomy and four corner arthrodesis: a systematic review and meta-analysis. Journal of Plastic, Reconstructive & Aesthetic Surgery, 2022.
- Chammas PE, et al. Proximal row carpectomy generates better mid- to long-term outcomes than four-corner arthrodesis for post-traumatic wrist arthritis: a meta-analysis. OTSR, 2022.
- Systematic review of PRC vs FCA in post-traumatic wrist osteoarthritis.
- França Bisneto EN, et al. Comparison between proximal row carpectomy and four-corner fusion: a prospective randomized study. Clinics, 2011.
- Alanen M, et al. PROOF trial protocol: proximal row carpectomy versus four-corner fusion. Trials, 2023.
- Wall LB, et al. Proximal row carpectomy: minimum 20-year follow-up. Journal of Hand Surgery (Am), 2013.
- Ali MH, et al. Long-term outcomes of proximal row carpectomy: a minimum of 15-year follow-up. Hand, 2012.
- Long-term outcomes of proximal row carpectomy: a systematic review. Journal of Wrist Surgery, 2012.
- Wagner ER, et al. A comparison of proximal row carpectomy and four-corner fusion in patients under 45. AAHS Annual Meeting, 2016.
- Garcia BN, et al. PRC vs FCA for stage 2 SLAC/SNAC wrist (Healio summary), 2020.
- Daly LT, et al. Chronic scapholunate interosseous ligament disruption: a systematic review and meta-analysis of surgical treatments. Hand, 2020.
- Outcomes of three-ligament tenodesis at one year (Mass General).
Disclaimer: This article is for general information and does not replace a consultation with a qualified hand and wrist surgeon.