Fractures of the hamate are usually one of two patterns....Body and Hook
Four types of body fracture are described:
• sagittal oblique
• dorsal coronal
• proximal pole
• medial tuberosity
Coronal fractures may be associated with 4th and 4th CMC subluxation
The pattern is usually dorsomedial to palmar lateral
A fracture of the distal ulnar margin can occur due to compression against the 4th and 5th metacarpals.
The hook of the hamate is formed from a separate ossification center
Failure of fusion leads to an accessory ossicle
Fractures are classified into 3, according to the location on the hook
Involvement of the base is most common
Non union is a potential complication
Fractures of the hook of the hamate are more often the consequence of an impaction injury.
Wrist impaction injuries or hammer hand injuries are prevalent in golfers and sports involving bats particularly baseball.
Stress fractures occur in the non dominant hand of golfers
Fractures of the hook of the hamate occur through the base of the process and
can be difficult to detect on routine radiography.
Cross sectional imaging is generally required and the diagnosis should be considered in
patients with resistant ulnar sided pain associated with focal tenderness distal to the pisiform bone in the region of the hook of the hamate.
Axial, CT and MR images are both efficient in the diagnosis.
The CT technique that is described is the so called prayer position where
the patient is scanned palms together and axial images acquired through both wrists.
The advantage of this technique is to allow us comparison between sides.
The appearances on MR can be subtle particularly when perifracture oedema has resolved.
The area of the base of the hook of the hamate needs to be scrutinised carefully.
Osteochondritis of the lunate// Related to ulnar negative variance
Graded according to extent of involvement on XRay
1 Normal XRay
2 Sclerosis on XRay
3 Contour loss
4 Osteoarthritis
To be differentiated from intraosseus ganglion which is more focal and cyst like. Ganglion may be the consequence of scapholunate ligament injury
One of the commonest causes of ulnar sided wrist pain is arthropathy of the pisiform triquetral joint.
In the majority of cases this is due to simple degenerative disease however
any arthropathy may involve this joint including seropositive, seronegative or
any of the synovial metaplasias including synovial osteochondromatosis and PVNS, though clearly these latter entities are rare.
The disease may manifest by the presence of effusion, synovial cyst, articular cartilage diseases and subchondral bone oedema.
Tenderness may be present over the pisiform and, if clinically appropriate, an ultrasound guided injection may be of value.
Pisiform triquetral subluxation may occur secondary to injury to the pisiform-hamate ligament.
The pisiform-hamate and the pisiform metacarpal ligaments represent the distal connections of flexor carpii ulnaris which inserts over the proximal aspect of the bone.
Injuries to flexi carpii ulnaris, the adjacent pisiform and associated ligaments is referred to as Raquet wrist and
may been seen in association with any of the racket sports but also with baseball, cycling and golf.
Two ligaments attach the pisiform distally essentially representing the continuation of FCU
These are the Pisohamate and Pisometacarpal ligaments
