Orthopedics--  Foot
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þ Charcot Joint
 - Neuropathic repetitive trauma vs. poor vascular autoregulation
 - Diabetic most common.

 - Clinical findings include erythema, edema and increased temperature in the 
   affected joint. In neuropathic foot joints, plantar ulcers may be present. 
   Note that it is often difficult to differentiate osteomyelitis from a Charcot 
   joint, as they may have similar tagged WBC scan and MRI features (joint 
   destruction, dislocation, edema). Definitive diagnosis may require bone or 
   synovial biopsy. 

 - First, it is important to recognize that two types of abnormality may be 
   detected. One is termed "atrophic," in which there is osteolysis of the 
   distal metatarsals in the forefoot. The more common form of destruction is 
   "hypertrophic" joint disease, characterized by acute peri- articular fracture 
   and joint dislocation. According to Yochum and Rowe, the "6 D's" of 
   hypertrophy are: 1. Distended joint 2. Density increase 3. Debris production 
   4. Dislocation 5. Disorganization 6. Destruction
 
   The natural history of the joint destruction process has a classification 
   scheme of its own, offered by Eichenholtz decades ago:

   Stage 0: Clinically, there is joint edema, but radiographs are negative. Note 
   that a bone scan may be positive before a radiograph is, making it a 
   sensitive but not very specific modality.

   Stage 1: Osseous fragmentation with joint dislocation seen on radiograph 
   ("acute Charcot").

   Stage 2: Decreased local edema, with coalescence of fragments and absorption 
   of fine bone debris

   Stage 3: No local edema, with consolidation and remodeling (albeit deformed) 
   of fracture fragments. The foot is now stable.

   Destroyed TMT joints in the medial left foot, with fracture and dislocation 
   of fragments; these are classic findings. Also note loss of the foot arch and 
   acquired flat foot (pes planus) deformity

   Hypertrophic Features:

   Atrophic Features: 1. Resorbed articular surface 2. Tapered bone ends

þ Lisfranc Fracture-Dislocation:
 - Fracture/dislocation at tarso-metatarsal junction.  Subtle findings on
   x-ray, so easy to miss.  Best clue is widening of separation between first
   and second metatarsals.  Also look for small avulsion fractures from the
   medial base of the second or lateral base of the first metatarsal.

 - Classic mechanism:  Fall from horse with foot still in stirrup.  
   To test for tarsometatarsal or
   talonavicular instability:  stress x-rays with foot inverted and everted,
   or weight-bearing lateral films.

þ Fifth Metatarsal Fractures
 - Can use Reese shoe instead of cast shoe; slightly less clumsy.