First Metatarsophalangeal Joint Arthrodesis
First metatarsophalangeal joint (MTPJ) arthrodesis is indicated for end-stage hallux rigidus, severe hallux valgus, and inflammatory arthropathy when conservative management fails, with plate fixation being the preferred technique due to superior stability, lower complication rates, and reliable functional outcomes.
Indications
First MTPJ arthrodesis should be performed for:
- End-stage hallux rigidus (primary indication) with severe pain and functional limitation 1, 2
- Severe hallux valgus deformity 1
- Inflammatory arthropathy affecting the first MTPJ 1
- Failed previous first ray surgery requiring revision 3
The procedure is indicated only after conservative measures have been exhausted, including topical NSAIDs, oral NSAIDs for limited duration, exercises for joint mobility and muscle strength, and orthoses 4.
Surgical Technique
Positioning and Alignment
The fusion sagittal angle must be positioned between 20° to 30° of dorsiflexion from the first metatarsal axis (corresponding to 10° to 15° off the weightbearing axis) 1. This is critical for postoperative function.
Use the Artificial Floor Technique (AFT) for accurate positioning:
- Place the entire foot flat on a rigid, sterile surface to simulate weightbearing position
- Measure 1 cm elevation of the plantar soft tissue at the distal proximal phalanx off the artificial floor using a sterile ruler
- This technique achieves the target fusion angle in 91% of cases without fluoroscopy 1
- The AFT is valid regardless of foot size (no correlation between foot length and fusion angle achieved) 1
Joint Preparation
Employ the cup-and-cone technique for joint preparation, which provides excellent bone-to-bone contact 5.
Fixation Method
Plate fixation is the preferred technique based on multiple outcome measures 2:
- Union rate: 95.2% at mean 92 days 2
- Lowest complication incidence among modern fixation methods 2
- Provides superior stability allowing early ambulation 2
- Low-profile titanium plates specifically designed for first MTPJ arthrodesis achieve 98% union rates 5
Alternative fixation methods show:
- Staples: 98.2% union rate at 84 days (highest union rate but other outcomes less favorable) 2
- Screws: 94.9% union rate at 71 days (fastest union but less stable) 2
Postoperative Management
Immediate Postoperative Period
- Full weightbearing on heels immediately in a rigid-soled postoperative shoe 1
- Short immobilization period (typically until clinical union) 5
Follow-up Timeline
- Obtain weightbearing radiographs at minimum 3 months postoperatively to confirm union 1
- Mean union time is 83.5 days across all fixation techniques 2
- Remove internal fixation construct once union is confirmed (typically 3-4 months) 1
Expected Outcomes
- Overall union rate: 95.7% with modern fixation techniques 2
- Complication incidence: 5.8% 2
- High patient satisfaction with reliable functional outcomes 5, 2
- Short rehabilitation period compared to historical techniques 5
Common Pitfalls
Avoid malposition: The most critical technical error is improper fusion angle. Too little dorsiflexion causes difficulty with shoe wear and gait; too much causes transfer metatarsalgia. The AFT prevents this complication 1.
Hardware removal may be necessary: Approximately 6% of cases require plate removal, and rare cases need tenolysis 5. Plan for this possibility during patient counseling.
Nonunion risk: While modern techniques achieve >95% union rates, the 5% nonunion rate necessitates patient education about revision surgery options 3, 2.