MCQs – Hand 5

MCQs-Hand 5
EIP transfer

– acute mallet fractures are best treated with extension splinting

– for FDP avulsions that retract into the palm, all the blood supply to that tendon has been torn, and you have a window of 7-10 days to get at them. Waiting longer means that you’ll probably need a graft.

– rotational malunion of the fingers after metacarpal fracture is best treated with metacarpal derotational osteotomy

– the MCP collaterals act as cams, as they are stretched in flexion, lax in extension. If you immobilize them in extension, they contract and will not permit flexion. Hence, immobilize them in flexion! Loss of motion is related to collateral shortening.

– complex MCP dislocations are usually caused by interposition of the volar plate.

– the digital nerve is most at risk when volarly approaching a complex MCP dislocation.

– the most superficial structure to be wary of when approaching a radial clubhand surgically is the median nerve – it is radially displaced and immediatey subcutaneous.

– remember that there are two deep fascial spaces in the hand – the outer boundaries are the thenar fascia radially, and the hypothenar fasica ulnarly. The oblique septum from the 3rd metacarpal divides this deep space into two spaces – the medial “midpalmar” space, and the lateral “thenar” space. Both communicate with Parona’s space which is the space between the deep flexors of the forearm and the anterior surface of pronator teres.

– if you lose ulnar sensation to the hand but have normal interosseous power, you’ve just lost the sensory branch – the lesion must be at or just distal to Guyon’s canal, where the deep and superficial branches divide. The deep branch is said to go through between the abductor digiti minimi and flexor digiti minimi. Conversely, if you lose interosseous power and have intact sensation, the lesion could be at Guyon’s or in between abductor digiti minimi and flexor digiti minimi.

– Guyon’s canal is formed by the pisoform medially, hook of hamate laterally, transverse carpal ligament (continuation of carpal tunnel roof) is the floor of the canal, and the volar carpal ligament (continuation of some forearm fascia) is the roof
– with regards to scaphoid blood supply – the tuberosity receives its supply from the palmar branches of the radial artery. The remaining majority of the scaphoid gets its supply dorsally.

– the volar Russe approach to the scaphoid goes through the fibrous sheath of FCR.

– MCP flexion is most likely going to allow the long extensors to extend the IP joints of the hand when the intrinsics are paralyzed.

– there is “synergy” between wrist and fingers – synergy exists between finger flexion and wrist extension, and it exists between finger extension and wrist flexion (try this on your own hand and you’ll understand!). This concept is important when deciding about tendon transfers – ideally, you’d like to transfer tendons that are synergistic, because they will be acting “in phase”.

Remember the principles of tendon transfer
– must correct joint contractures first
– the transferred muscle/tendon should have at least a solid grade 4 power – expect it to lose one grade
– the transferred tendon must have adequate excursion to move the involved joint
– the tendon should be transferred in as straight of a line of pull as possible
– ideally, one tendon per function – do not try to motor two different functions with one tendon
– in phase transfer (synergism) is better than transferring tendons of muscles that work out of phase
– the tendon must be expendable!
– the tissue bed must be in equilibrium – soft tissue induration is gone, there is no further reaction in the wound, the joints are supple, the scars are as soft as they are going to be. Tendon transfers work best when passed between the subcutaneous fat and deep fascial layer, not when in the pathway of scar.

– A contracture of the oblique retinacular ligament is bound to cause a DIP extension contracture; not sure if a triangular ligament contracture will do the same, or