DIP JOINT ARTHRITIS
Degenerative | Mucous Cyst | Heberden's Node | Joint Destruction
Eaton-Littler Classification
Critical Must-Knows
- Heberden's nodes are osteophytes at DIP joint - pathognomonic for OA
- Mucous cyst communicates with DIP joint in nearly all cases
- Arthrodesis is gold standard for painful end-stage DIP OA
- Nail deformity from mucous cyst pressure requires cyst excision + osteophytectomy
- Pin fixation for 6 weeks post-fusion is standard
Examiner's Pearls
- "Terminal tendon divides into lateral bands inserting on base of distal phalanx
- "Mucous cyst excision must include osteophyte debridement
- "Silicone arthroplasty has high failure rate - avoid in DIP
- "Fusion position: 10-20 degrees flexion for index, 30-40 for ring/small
Clinical Imaging
Clinical Photos
Radiographic Findings
Critical DIP Exam Points
Heberden's Node
Pathognomonic for OA (DIP). Distinguish from Bouchard's (PIP, Rheumatoid).
Mucous Cyst
Always check for nail deformity. The cyst communicates with the joint.
Fusion Angles
Index 10-20° (Pinch), Small 30-40° (Grip). Incorrect angle causes functional loss.
At a Glance
DIP joint arthritis is the most common site of primary osteoarthritis in the hand, affecting 70% of women over 60. Characterized by Heberden's nodes (dorsal osteophytes), it typically presents with pain, stiffness, and deformity. Mucous cysts arise from the joint and can cause nail deformity. Treatment is primarily conservative (90% respond to NSAIDs and splinting), with DIP arthrodesis reserved for refractory cases. Key decision: fuse in functional position (index 10-20° for pinch, small finger 30-40° for grip).
Key Facts
Quick Decision Guide - DIP Arthritis Management
| Scenario | Severity | Treatment | Key Pearl |
|---|---|---|---|
| Mild pain, minimal deformity | Grade I-II | NSAIDs + splinting | 90% respond to conservative management |
| Moderate pain, Heberden's node | Grade II-III | Procedures | Corticosteroid injection (3-6 mo relief) |
| Severe pain, bone-on-bone | Grade III | DIP arthrodesis | 90% fusion rate, excellent pain relief |
| Mucous cyst with nail deformity | Any grade | Cyst excision + Osteophytectomy | Must remove spur to prevent recurrence |
HEBERDENDIP Arthritis Features
Memory Hook:HEBERDEN nodes are the hallmark of DIP arthritis
Overview and Epidemiology
Overview/Epidemiology
Distal Interphalangeal (DIP) Joint Arthritis is the most common form of hand arthritis, predominantly affecting elderly women. It is approximately 10 times more common than rheumatoid arthritis affecting the DIP joint. The condition manifests as Heberden's nodes - bony enlargements at the DIP joints that are pathognomonic for osteoarthritis.
Exam Pearl
Why DIP Arthritis Matters Clinically: DIP arthritis significantly impacts fine motor function and can cause nail deformities when associated with mucous cysts. While many patients manage conservatively, those requiring surgery benefit from highly successful arthrodesis with 90% fusion rates and excellent pain relief. Recognition of mucous cyst-joint communication is critical for surgical planning.
Demographics
- Age: Predominantly over 60 years.
- Gender: 70% female predominance.
- Occupation: Repetitive manual labor increases risk.
- Genetic: Familial clustering in 40-50% (Hereditary HOA).
Pathophysiology
Anatomy and Biomechanics
- Joint Type: Ginglymus (hinge joint). Range of motion 0-80 degrees.
- Articular Surface: Bicondylar head of middle phalanx (P2) articulates with biconcave base of distal phalanx (P3).
- Capsule: Thin dorsal capsule, thicker volar plate which prevents hyperextension.
- Relationship to Nail Matrix: The germinal matrix of the nail fold extends proximally to within 1-2 mm of the insertion of the extensor tendon. This close proximity explains why dorsal osteophytes compress the matrix, causing nail deformities.
Tendons:
- Terminal Extensor: Formed by the convergence of lateral bands. Inserts on the dorsal lip of P3.
- Flexor Digitorum Profundus (FDP): Inserts on the volar base of P3.
Biomechanical Stability: Unlike the PIP joint, the DIP joint has relatively short collateral ligaments. Stability is provided significantly by the articular conformity ("Cup and Cone" geometry). Loss of cartilage leads to instability, often manifesting as radial or ulnar deviation. Because the DIP joint is the terminal link in the kinematic chain, its stability is crucial for precision pinch (index finger) and power grip locking (ulnar digits).
Pathogenesis
The pathophysiologic cascade begins with cartilage degradation from mechanical stress and aging. Chondrocyte apoptosis leads to matrix metalloproteinase release, causing progressive cartilage loss. Subchondral bone responds with sclerosis and osteophyte formation - the hallmark Heberden's nodes.
Formation of Mucous Cyst: Degeneration leads to osteophyte formation at the joint margin. This osteophyte can pierce the joint capsule, allowing synovial fluid to herniate dorsally. This herniated sac becomes encapsulated, forming a Mucous Cyst (Ganglion). The cyst sits between the extensor tendon and the nail matrix, causing nail grooving via direct pressure (longitudinal groove). The connection with the joint is often a tortuous stalk, acting as a one-way valve where fluid enters the cyst but cannot return to the joint, leading to cyst enlargement.
Primary vs Secondary DIP Arthritis
| Type | Mechanism | Features |
|---|---|---|
| Primary OA | Age-related cartilage degeneration | Multiple digits, symmetric |
| Post-traumatic | Intra-articular fracture | Single digit, history of trauma |
| Erosive OA | Inflammatory cascade | Rapid progression, 'Seagull' sign |
Differential Diagnosis
| Diagnosis | Key Differentiators | Imaging Features |
|---|---|---|
| DIP Osteoarthritis | Heberden's nodes, no systemic symptoms | Osteophytes, Sclerosis, Normal density |
| Psoriatic Arthritis | Nail pits, rash, dactylitis (sausage digit) | "Pencil-in-cup", Periostitis, Osteolysis |
| Gout | Acute flare, Tophi (white chalky deposit) | Punched out erosions with overhanging edges |
| Rheumatoid Arthritis | Spares DIP (usually), symmetric MCP/PIP | Juxta-articular osteopenia, erosions |
Note: Systemic review is mandatory.
Classification
Eaton-Littler Classification
Radiographic classification guiding treatment.
| Grade | Radiographic Features | Management |
|---|---|---|
| Grade I | Joint space narrowing, no osteophytes | Conservative (Splint/NSAID) |
| Grade II | Osteophytes present, sclerosis | Injection / Procedure |
| Grade III | Bone-on-bone, deformity, cysts | Arthrodesis |
Utility: This classification correlates well with symptoms.
Clinical Presentation
History
- Pain: Worse with activity (pinch), relieved by rest.
- Stiffness: Short duration (under 30 mins) morning stiffness.
- Deformity: "Knobby fingers" (Heberden's).
- Function: Difficulty with fine motor tasks (buttons, needles).
Examination
- Heberden's Nodes: Bony hard swellings at dorsolateral joint margin.
- Mucous Cyst: Translucent, fluid-filled mass dorsally (often between nail fold and joint).
- Nail Deformity: Longitudinal groove/ridge denotes cyst pressure on matrix.
- ROM: Crepitus, loss of flexion.
- Deviation: Often radially deviated or flexed.
Investigations
Imaging
Plain Radiographs are the gold standard.
- Views: PA, Lateral, Oblique.
- Findings:
- Joint space narrowing.
- Subchondral Sclerosis.
- Osteophytes (Heberden's).
- Subchondral Cysts.
- Alignment (Deviation).
Exam Pearl
No Need for MRI: Plain X-rays are sufficient for diagnosis and surgical planning. MRI is only indicated if tumor or infection is suspected (rare).
Management
CYSTMucous Cyst Management
Memory Hook:CYST excision needs osteophyte (Spur) removal
Surgical Technique
Step-by-Step: DIP Arthrodesis
Precise technique is required to prevent non-union.
1. Exposure
- Incision: H-shaped or T-shaped incision is best. The transverse limb should be distal to the DIP crease to allow good skin retraction.
- Tendon: Tenotomy of the terminal extensor tendon. It can be split longitudinally or transected (since it will be fused).
- Collaterals: Release collateral ligaments to allow full access.
2. Joint Preparation (The 'Cup and Cone')
- Principles: Maximize bone contact surface area.
- Distal Phalanx (Cup): Use a small high-speed burr or correct sized reamer to create a concave surface.
- Middle Phalanx (Cone): Shape the head of P2 into a convex cone.
- Fit: The two surfaces should lock together ("Morse Taper" effect) at the desired angle.
3. Fixation
- Headless Compression Screw:
- Insert guide wire retrograde through P3 to the tip.
- Reduce joint at desired angle.
- Drive guide wire antegrade into P2 isthmus.
- Measure and insert screw (e.g. Acutrak Mini or Micro).
- Pros: Compression, no external metalwork.
- Cons: Cost, difficult hardware removal.
- K-Wires:
- Use two 0.045 inch wires (parallel or crossed).
- Crossed wires provide better rotational control.
- Pros: Cheap, easy to remove in clinic.
- Cons: Pin tract infection risk, lack of compression.
4. Closure
- Check alignment under fluoroscopy.
- Repair tendon (optional).
- 5-0 Nylon for skin.
- Protective splint.
Video: Confirm reduction on screen.
FLIPFusion Position by Finger
Memory Hook:FLIP your finger position
Post-Operative Rehabilitation Protocol
Phase 1: Protection (0-6 Weeks)
- Goals: Protect fusion, wound healing.
- Immobilization: Pin-protecting splint (Stax or Thermoplastic).
- Activity: Keep dry. Gentle motion of PIP joint (isolation exercises).
- Follow-up: X-ray at 6 weeks. If union visible and K-wires present, remove wires.
Phase 2: Remobilization (6-12 Weeks)
- Goals: Desensitize tip, restore function.
- Activity: Begin using finger for light pinch.
- Therapy: Scar desensitization massage. Coban wrapping for edema control.
Phase 3: Strengthening (3 months+)
- Goals: Return to full unprotected use.
- Activity: Full manual labor allowed once radiographic union is solid.
Patient Education and Expectations
Patient Education
Managing patient expectations is critical for satisfaction.
What to Expect After Surgery
- Pain: Severe pain usually subsides within 3-4 days. Pivot to simple analgesia (Paracetamol) early.
- Swelling: The finger will remain swollen for 3-6 months. This is normal.
- Stiffness: The PIP joint may become stiff from disuse. Early motion of the PIP is mandatory.
- Hardware: If K-wires are used, they may protrude. Keep them clean and dry. Infection requires immediate removal.
Long Term Outcomes
- Fusion: Once fused, the pain is gone. The finger will not bend at the tip.
- Function: Most patients (90%) are very satisfied and would have the surgery again. Grip strength improves because the pain is gone.
- Complications: There is a small risk (5-10%) that the bone does not knit (Non-union). This may require a second surgery.
Disclaimer: Recovery timelines vary by patient comorbidity and compliance.
Future Directions
While fusion remains the standard, new technologies are emerging:
- Bio-absorbable Implants: Pins made of magnesium or polyphenyl which dissolve, eliminating the need for removal.
- Surface Replacement: Newer ceramic or pyrocarbon implants that preserve motion. Currently, these still have higher failure rates than fusion but may be appropriate for low-demand patients.
- Regenerative Medicine: Stem cell injections (BMAC) for early stage arthritis to regenerate cartilage. Evidence is currently Level IV/V.
Complications
| Complication | Incidence | Management |
|---|---|---|
| Non-Union | 5-10% | Revision fusion vs Accept (fibrous union) |
| Infection | 1-2% | Antibiotics / Pin removal |
| Nail Deformity | 5% | Nail plate removal / Matrix repair |
| Malunion | Rare | Corrective osteotomy |
| Cyst Recurrence | 5-30% | Re-excision + Osteophytectomy |
Recurrence Risk: Mucous cyst recurrence is almost exclusively due to failure to remove the osteophyte. The osteophyte acts as a "can opener" on the capsule. It must be debrided down to the shaft level.
Intraoperative Troubleshooting
- Bone too soft: Augment with K-wires if screw threads strip.
- Nail bed injury: Repair germinal matrix with 6-0 absorbable suture immediately to prevent nail ridge.
- Malrotation: Check finger cascade in flexion before final fixation. Clinical check is better than X-ray for rotation.
Evidence Base
DIP Fusion Outcomes
- Review of 120 DIP fusions
- Union rate of 90% achieved
- Pain relief was reliable in 95% of patients
- Functional loss was minimal
Silicone Arthroplasty Failure
- Long term review of silicone arthroplasty in DIP
- High rate of instability and lateral deviation
- Implant fracture common
- Recommended abandonment of procedure for DIP
Mucous Cyst Recurrence
- Retrospective review of cyst excision with and without osteophytectomy
- Recurrence 0% with osteophyte removal
- Recurrence over 20% without osteophyte removal
Fusion Fixation Techniques
- Comparison of Headless Compression Screws vs K-wires
- Screws had higher union rate and earlier mobilization
- K-wires had higher infection rate (exposed pins) but lower cost
- Both methods acceptable
Exam Viva Scenarios
Practice these scenarios to excel in your viva examination
The Standard Case
"A 68-year-old lady presents with a painful, deformed index finger DIP joint. X-rays show bone-on-bone arthritis. She asks about 'joint replacement' so she can keep moving it suitable."
Counseling: I would strongly advise against arthroplasty. Unlike the PIP joint, the DIP joint requires stability for pinch more than motion. Arthroplasty has high failure rates (instability, breakage). Fusion provides a painless, stable post for pinch with minimal functional loss.
Position: 0-10 degrees of flexion (essentially straight). This allows the pulp to meet the thumb for precision pinch.
Risks: Non-union (10%), Infection (pin track), Nail deformity, Cold intolerance.
Mucous Cyst Complication
"A 50-year-old female presents with a burst mucous cyst on her middle finger. The area is red and discharging."
Acute Management: This is an open joint (compound). Requires washout (oral antibiotics usually insufficient if joint communicates). I would treat as potential septic arthritis - washout in theatre or minor ops.
Surgery: Once infection settles, she needs definitive excision + osteophytectomy to prevent recurrence.
Risk: Septic arthritis leading to osteomyelitis and destruction of the distal phalanx (requires amputation).
DIP Arthritis
High-Yield Exam Summary
Key Concepts
- •**Heberden Node**: Osteophyte at DIP
- •**Bouchard Node**: Osteophyte at PIP (Also in OA)
- •**Mucous Cyst**: Ganglion + OA (Connects to joint)
Classification (Eaton)
- •**Grade I**: Narrowing
- •**Grade II**: Osteophytes
- •**Grade III**: Deformity
Fusion Angles
- •**Index**: 0-10 degrees
- •**Middle**: 20 degrees
- •**Ring/Small**: 30-40 degrees
References
- Stern PJ, Fulton DB. Distal interphalangeal joint arthrodesis: an analysis of complications. J Hand Surg Am. 1992;17(6):1139-45.
- Wilgis EF. Distal interphalangeal joint silicone interpositional arthroplasty of the hand. Clin Orthop Relat Res. 1997;(342):38-41.
- Fritz D, Kaplan FT, et al. Distal interphalangeal joint mucous cysts: an analysis of treatment and results. J Hand Surg Br. 1997;22(5):623-5.
- Eaton RG, Littler JW. A study of the basal joint of the thumb. Treatment of its disabilities by fusion. J Bone Joint Surg Am. 1969;51(6):1217-1218. (Classification Adapted).
- Villani F, Uezl P. Arthrodesis of the distal interphalangeal joint with the Acutrak screw. Plast Reconstr Surg. 2012;129(6):958e.
- Olivecrona H. DIP arthrodesis with the Headless Compression Screw: A clinical study. J Hand Surg Eur. 2010;35(9):763-9.