Download Dee Chapter 31 : Foot Fractures

Tendon transfers
Dee Chapter 60
OKU Hand
Topics
Principles of tendon transfer
Radial nerve palsy
Median nerve palsy
Ulnar nerve palsy
Combined nerve lesions
Principles of tendon transfer
Fundamental concept
Recipient musculotendinous unit is more important to limb function than the donor unit
Alternatives to tendon transfer
 Neurorrhaphy
 Intercalary tendon graft
 Tendon lengthening
 Tenodesis
 Free muscle transfer
 Arthrodesis
Main requirements
1.
2.
3.
4.
5.
6.
Supple skin, subcutaneous tissue and joint
Muscle must have adequate power
Muscle must have sufficient amplitude (or excursion)
Must have a satisfactory line of pull
Preferably synergistic action
Functional integrity of the donor function must be preserved
Supple skin,
subcut and joint
Power
Amplitude or
excursion
Line of pull
Synergistic
Donor function
Must not have joint or soft tissue contracture
Directly proportional to cross sectional area of muscle
Independant of length or excursion
Work capacity of muscle = power x amplitude (kg.m)
Potential excursion is the difference between maximal
length on traction, and length at maximal contraction
Usually resting length is directly in the middle of these 2.
i.e.
Excursion = (tension length – resting length) x 2
Should be as straight as possible
Each turn or bend reduces power and amplitude
Preferably should be synergistic to new action
But sometimes not possible, doesn’t have to be
Must be maintained by another capable muscle to
prevent imbalance
Surgical considerations
Timing of surgery depends on
Joint need preop contracture release,
splinting, therapy
Skin/subcut may require pedicle or
free flap
Power must match the lost muscle
Also transferred muscle usually loses
1 power grade, so must use a muscle
that is minimum 4+ or 5
Practical guidelines:
Wrist motors 30mm
Finger extensors 50 mm
Finger flexors 70mm
New function more easily learnt if
synergistic



cause of problem
prognosis for recovery
patient preference to some extent
Nerve problems
may want to wait for nerve to recover to see eventual function
may also consider alternative like neurolysis, neurorrhaphy + N grafting
Indications for early tendon transfer < 12 weeks
1. proximal N lesions
2. irreparable N lesions
3. other lesions with statistically poor chance of acceptable recovery
4. donor tendon completely expendable
5. no imbalance will be created later by nerve regeneration
Skin planning and incisions
Pre-op planning – list of deficits vs list of available donor muscles
Multiple short transverse incisions are better than long ones
Need soft tissue cover over tendon junctures
May use end-to-side, end-to-end, or tendon weave
Radial nerve palsy
Functional impairment
No wrist extension
No MCPJ extension
Loss of abduction and extension of thumb
Without wrist extension there can be no power grip
Usually sensory component is not significant in radial N palsy
If PIN only, wrist extension may be preserved by functioning ECRL – so no need to address wrist
Treatment
Most use dynamic extension splints and OT to keep wrist, hand and fingers supple
Some suggest early transfers which serve as internal splints
 controversial and not used by everybody
 early PT (pronator teres) to ECRB end to side transfer
o PT still works as a pronator
o But also allows wrist extension – power grasp
o May make external splinting unnecessary
o If inadequate motor function returns, then extra transfers for MCPJ extension and thumb
extension/abduction
Some common transfers for radial N palsy
FCU retained for important
role in wrist flexion
PT used for wrist extension because of work
capacity and also pronator function still
preserved
FDS long and ring fingers
 passed through hole in interosseus
membrane to transfer to their target
muscles
 mobilised proximally so that when their
muscle mass sits in the hole, rather
than the tendon to avoid adherence at
transfer site
FCR is strong abductor of thumb MC
Easier to do than boyle
But main disadvantage is use
of FCU as a donor because
wrist works in radial
dorsiflexion and ulnar
palmarflexion
Restores wrist and MCP extension as well as
thumb abduction/extension
Boyle
PT to ECRB
FCR to EPB and APL
FDS long finger to EDC
FDS ring finger to EPL and EIP
Green
PT to ECRB
FCU to EDC
PL to rerouted EPL
PT to ECRB
FCR to EDC
PL to rerouted EPL
Alternative to Green to avoid
FCU use
Median nerve palsy
Functional impairment
Sensory component is very important and needs to be addressed
Motor deficit
 low median N distal forearm
o Opponens poll, APB and to varying extent FPB
o 1/3 of patients have sufficient strength in FPB that opponens transfer is not required
 high median N
o in addition to opponens, APB and FPB - entire FDS, FDP to index/long and FPL are lost
o FCR not working but functional wrist flexion comes from FCU (ulnar N)
Treatment
Opponens function
Try to see if opponens function can be preserved
 Residual FPB function in 1/3 patients
 Neurorrhaphy or nerve grafting
If not then surgery
Prerequisites are good skin and supple joints.
May need pre-transfer release of 1st web space contracture if present
Opponensplasty
Much experience gained in polio patients
Stronger donor must be selected if thumb adductor, 1st dorsal interosseus and EPL are functioning
If combined lesions and above paralyzed, can use weaker donor
Usual opponensplasty donors
1. PL – Camitz transfer
o Test by opposing thumb and little finger and flexing wrist
2. FDS to ring (through FCU loop)
3. EIP or EDQP
o Test by doing the Horn sign – 3rd, 4th fingers flexed, 2nd and 5th fingers extended
Median N palsy
Low median
nerve palsy
Antagonists of opponens are functioning
so strong motor is required
Line of pull for opponens function should
be from the pisiform area
 Half of FCU tendon used to make
a sling at the level of the pisiform
Longstanding CTS with thenar wasting
Ring finger FDS usually used for opponens plasty
 Harvested proximal to metacarpal A1 pulley
 Through FCU sling
 Subcutaneous to insert into tendon of APB
or dorsoulnar base of 1MC
(Alternative tendons are PL, EIP, EDQP, ECU)
Camitz transfer
After CTS release, can transfer PL to APB to
provide palmar abduction of thumb
(Or FDS4, EIP, EDQP, ADM)
EIP, EDQP, ECU, Abd dig min for opponensplasty
High median
nerve palsy
FDS, FDP2,3 and FPL gone
FCU still functioning to allow wrist flexion
Since FDS gone, cannot use FDS4 for
opponensplasty  use alternatives

FDP2,3 side-to-side attached to FDP4,5 for long
finger flexion – if more power needed, ECRL can be
transferred to FDP 2,3
BR to FPL for thumb IPJ flexion
Ulnar nerve palsy
Functional impairment
Loss of interossei and ulnar 2 lumbricals
Loss of independant MCPJ flexion
Difficulty in coordination of proper finger flexion without MCPJ flexion
 Because FDS and FDP cause flexion of IPJs first with only secondary MCPJ flexion later
 Gripping large objects a problem because unable to start grasp with MCPJ flexion
 Power grip severely impaired
Loss of abduction and adduction of fingers impairs dexterity
Loss of adductor pollicis
Loss of key pinch ability
Compensatory hyperflexion of thumb IPF (to increase mechanical advantage of EPL as secondary
adductor) = Froment’s sign
Clawing
Usually seen in ulnar 2 fingers
Again due to weak MCPJ flexion resulting in IPJ flexion with MCPJ extension
Without exercise/splinting, fixed contractures can occur
High ulnar N
Loss of FCU for wrist flexion, and FDP 4,5
Paradoxically less clawing
But significantly reduced powergrip now
Sensation
Significant but not as bad as median N sensory loss
Treatment
Aim to restore key pinch function and compensate for loss of active MCPJ flexion
High ulnar lesions – replace FCU
Ulnar N palsy
Key Pinch grip
Requires stable thumb
MC, MCPJ and index
finger
Important to reproduce
Adductor Pollicis
function
Static procedures
Loss of active
MCPJ flexion
Used when full IPJ
extension can be achieved
when MCPJ extension is
blocked
BR or ECRB transfer
 free tendon graft sutured to ulnar base of thumb PP
 brought across adductor muscle and taken dorsally
through 3rd web
 then secured to BR or ECRB which have been mobilised to
create enough length
Others consider thumb MCPJ or IPJ fusion ± transfer to improve
index finger abduction
Static procedures to prevent hyperextension of MCPJ
 bone blocks
 MCPJ arthrodesis
 Volar plate capsulorrhaphy
None of these can increase power grip
Ulnar N palsy
High ulnar N
Dynamic procedures
Dynamic tendon transfers
Fixed flexion contractures
present
Or
Extensor mechanism
already stretched and
there is extension lag of
IPJs when MCPJ
hyperextension is
prevented
FDP4,5 weakness
FCU weakness
Mainly designed to produce primary flexion at MCPJ
May improve power grip
 Originally FDS used but does not improve power grip
 Now extensor tendons can be used
Usually transfer is passed through lumbrical canal, under
transverse MC ligament into
 lateral band of finger (can cause PIPJ hyperextension)
 PP
 Or A2 pulley
FDP2,3 attached side to side to improve FDP4,5 function
1/2 or all FCR transferred to FCU
Combined nerve lesions
Difficult because limited motors available for transfer
Prevent contractures and deformity
Often lack of donor muscle may mean increasing use of static procedures like tenodesis, fusion, etc