Definitions
Corn
- accumulation of keratotic layers of epidermis
- thickened epithelium elevates prominence causing further pressure
Hard Corn
Due to extrinsic pressure from footwear
- most common on lateral aspect of 5th toe
- over head of proximal phalanx
Soft Corns
- on the condyle of proximal phalanx between the toes
- due to pressure between adjacent bony prominences
- DDx fungal infection
- soft due to moisture
- commonest is medial aspect 5th toe
- also common at base of web space overlying 4th proximal phalanx lateral condyle
Aetiology
Combination of Extrinsic or Intrinsic pressure
Extrinsic
- shoewear increasing compression
Intrinsic
- underlying prominent condyle of P1
X-ray
See on plain film with marker over corn
Non-operative Management
Usually not successful long term
- education re shoewear / wide shoe with extra depth toebox
- lambs wool dressing or foam pads
- trim hyperkeratosis
Operative Management
Isolated small keratosis over 5th PIPJ
- treat with condylar resection of 5th PIPJ alone
Keratosis over 5th PIPJ & base 4th web
- treat with resection of 5th condyle & lateral proximal phalangeal condyle of 4th toe
Intractable Plantar Keratoses
1. Resection Arthroplasty of Mann and DuVries 1973
Results
- 85-90% patient satisfaction
Technique
- dorsal Incision over MTP
- retract EDL
- divide transverse MT ligament
- severe collaterals and deliver head
- remove 2-3mm of distal MT head
- remove the plantar lip so approximately 50% of head has been excised
2. Giannestra Shortening Oblique MT Osteotomy
Best when long MT
- aim to shorten 5-6mm
- fix with screw
3. Dorsal Closing Wedge Osteotomy
Aim for dorsal wedge of 2-3mm
- fix with cross K-wires
- must pop for 6/52