Radial nerve-palsy-tendon-transfers

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  • 1. Radial Nerve Palsy Tendon Transfers Episode II

2. What is a tendon transfer? The tendon of a functioning muscle is detached fromits insertion and reattached to another tendon orbone to replace the function of a paralysed muscleor injured tendon. The transferred tendon remainsattached to its parent muscle with an intactneurovascular pedicle. 3. What is a tendon transfer? Using the power of a functioning muscle unit toactivate a non functioning nerve/muscle/tendonunit. Tendon transfers work to correct: instability imbalance lack of co-ordination restore function by redistributing remaining muscular forces 4. Indications Paralysed muscle Nerve injury peripheral or brachial plexus High cervical quadriplegia (needs some input to brachial plexus/hand) Neurological disease Nerve repair with early transfer as internal splint Injured (ruptured or avulsed) tendon or muscle Considerations Graft vs. transfer (adhesions more likely in graft 2 anastomoses) Quality of available donors Length of time since injury Nature of tendon bed Balancing deformed hand e.g. cerebral palsy or rheumatoid arthritis Some congenital abnormalities 5. General principles1. Only justified in restoring functional motion of the hand, not just motion Not all patients require the same functions/motions2. Patient factors Age Functional disabilities with poor non operative prognosis Ability to understand nature and limitations of surgery, including aesthetic goals Motivated to co-operate with post operative physiotherapy 6. General principles3. Recipient site Tissue Equilibrium concept as per Steindler/Boyes Tissue bed into which transfer is placed should be soft and supple Good soft tissue coverage Stable underlying skeleton Full passive range of motion of joints to be powered Area to be powered must be sensate 7. General principles4. Donor muscle factors (APOSLE)Amplitude of the donor muscle Should be matched to the unit being replaced Finger flexors 60 - 70mm, finger extensors and EPL 40 - 50mm, wrist flexors / extensors 30 - 40mm, brachioradialis 20 - 30mm Amplitude of motion of any tendon can be increased by :- Increasing the number of joints its crosses eg the amplitude of a tendon crossing the wrist joint is increased by 20 30mm by full ROM of wrist Tenodesis effect during active movement Freeing fascial attachments to donor tendons Inserting the tendon closer to the joint being moved, but this requires a motor unit of increased power (due to leverage); and vice versa 8. General principlesPower of the donor muscle Any transferred muscle loses at least one grade of strength, so only Grade 5muscles are satisfactory (Grade 4, or 85% normal strength, can be sufficientfor some transfers). Donor muscle strength should be maximised pre-operatively. Strongest are brachioradialis and FCU. Donor power correlated roughly withcross sectional area of muscle and fibre length Overly powerful muscles will unbalance and, over time, deform a joint. Somuscle power should be matched if possible. Effective power of a transfer can be increased by placing the tendon insertionfarther from the joint axis and as close to 90 as possible 9. General principlesOne tendon, One function Effectiveness reduced in transfer designed to produce multiple functionsSynergistic muscle groups are generally easier to retrain Fist group wrist extensors, finger flexors, digital adductors, thumb flexors, forearm pronators, intrinsics Open hand group wrist flexors, finger extensors, digital abductors, forearm supinators Use of synergistic muscles tends to help retain joint balance 10. General principlesLine of transfer Should approximate pull of original tendon if possible Acute angles should be avoidedExpendability Transfer must not cause loss of an essential function 11. General principles5. Other muscle factors of secondary importance Innervation - Donor muscle should be independently innervated and not act inconcert with other motors (eg lumbricals) Availability or necessity of antagonists eg brachioradialis is an effective wristextensor only if triceps is functioning to resist its normal elbow flexor action6. Tension of the transfer All transfers should be sutured at the maximum tension in the position thatreverses their proposed activity (Listers 4th Edn)7. Location and nature of pulley if required 12. General principles8. Selected arthrodeses Simplify polyarticular system Stabilise joints Arthrodeses useful in providing stable pinch grip Thumb MPJ and IPJ Index PIPJ and DIPJ 13. General principles9. Timing The timing of tendon transfers depends upon the aetiology and prognosis of motor imbalance, the neurophysiologic problems for the patient, and the constitution of the involved extremity (Omer GE: Timing of tendon transfers to the hand. Hand Clin 4(2):317, 1988) Usually last stage in reconstruction, after skeletal stability, soft tissue coverage, sensation and joint mobility tissue equilibrium Brown suggested early transfer if expected poor results Nerve gap>4cm Large wound or extensive scarring Skin loss over nerve10. Comparison to alternatives Nerve repair or transfer Tendon repair or graft Tenodesis (joint stabilisation by anchoring tendons that move the joint) Arthrodesis Amputation Muscle lengthening, release or denervation (in spasticity) 14. General principles11. Contraindications Age due to joint stiffness, decreased need for power movements anddifficult rehabilitation Motivation patients must be concerned about disability and highlymotivated to perform hand rehabilitation Task analysis transfers must be designed to accomplish tasks rather than justspecific motions. Eg opening doors requires grasp and twist Nature of disability systemic and local disease factors must be controlledbefore reconstruction attempted12. Disadvantages No increase in strength Normal function of transferred muscle is lost Transferred tendon may perform a different force, amplitude of movementand functional pattern Transferred tendon must learn a new movement/function 15. Selecting donor tendons Based on Smith & Hastings (Principles of tendon transfers to the hand. InstrCourse Lect 29:129, 1980)1. List functioning muscles2. List which of those muscles are expendable3. List hand functions requiring restoration4. Match #2 and #35. Staging 16. Maximising Success / Surgical Technique1. Incisions should not cross the path of the transferred tendon2. Avoid interference with normal structures3. Tendon should insert into the joint of motion at 90 to maximise power and excursion. Insertion can be moved away from the joint to improve power, but this is at the expense of decreased excursion4. The transferred tendon should insert into another tendon or bone. Strong insertions allow earlier mobilisation. 17. Maximising Success / Surgical Technique5. A single insertion is best. Dual insertions tend to provide motion to the tighter insertion. Can be an advantage in complex movements, where one insertion is tighter during one phase of motion, and the other takes over during another phase.6. Tension should be set to produce the necessary joint movement with maximal muscle contraction. Some initial over correction should be planned, as some tendon stretch is usual. 18. Maximising Success / Surgical Technique7. Joint should be initially immobilised in a position that relieves tension at the insertion of the transfer8. Reverse order harvest grafts, prepare recipient site and tunnel before raising muscle 19. General Post Operative Management Rehabilitation is equally important in tendon transfer successas surgical execution Rehabilitation / physiotherapy is essential in Regaining joint mobility lost during splinting Training tendon to glide in new course Teaching patients to activate a new muscle to achieve a certain function, which requires development of new neural pathways The more that a patient notices a disability, the greater themotivation, so the easier the retraining Children are usually managed with static protocols or longerprotective phase 20. Basic Principles of Post Operative Rehabilitation Described by Toth 19861. Protective phase Begins at surgery and lasts 3 5 weeks Objectives:- Protective splinting Oedema control Mobilise uninvolved joints2. Mobilisation phase Begins when tendon healing is adequate for activation (usually 3 5 weeks post op) Objectives Mobilise tendon transfer Immobilise soft tissue Continue immobilisation of uninvolved joints to prevent joint stiffness from disuse Reinforce preoperative teaching and patient education Continue oedema control and protective splinting Begin home rehabilitation program Usually day time dynamic splinting with nightly static splinting 21. Basic Principles of Post Operative Rehabilitation3. Intermediate phase Begins 5 8 weeks post operatively Gradually increases hand activity and passive range of motion exercises Limited functional movements permitted4. Resistive phase Beginning at 8 12 weeks Tendon junctions are strong enough to withstand increasing resistance Therapeutic objective is to increase endurance and strength of transferredmuscles Work related simulated tasks are begun to patient tolerance 22. Radial Nerve Palsy Need to differentiate between complete radial nerve palsy (includestriceps) and posterior interosseous palsy Brachioradialis and ECRL are innervated prior to termination into posterior interosseous and sensory branches of radial nerve Severe impairment due to loss of extension power to the wrist, fingers,thumb and loss of radial abduction of the thumb Wrist extension is critical for stability, which is essential for grip andassisting the function of many tendons crossing the wrist 23. Tendon Transfers Well defined and highly effective, aiming toreplace Wrist extension Finger extension Thumb extension and abduction Standard accredited to Riordan 1964 24. Radial Nerve Palsy Non-Operative Treatment Splintage Burkhalter observed grip strength increased 3-5 by simply stabilising the wrist with splintage Tailor to needs of patient Brand recommended that if wrist splint during day then need night finger extension splint because lose length of flexor muscle fibres making it more difficult to achieve normal balance after nerve recovery or after tendon transfers Maintenance of full passive ROM in all joints of thewrist/hands and prevent contractures 25. Radial Nerve Palsy Early transfers (Internal Splintage) Burkhalter believes greatest functional loss is grip strength therefore advocated early PT to ECRB Therefore eliminate need for external splint plus also restore gripstrength 3 indications: Works as substitute during early regeneration Works as helper by adding power to reinnervated muscle Acts as substitute in cases which results of nerve repair are poor(eg chronic/crush injuries or elderly) 26. Riordan TransferDonorInsertion Function PTECRBWrist dorsiflexionFCU EDC IF - LF Finger extension PLEPL (rerouted) Thumb extension 27. PT to ECRB 28. FCU to EDC 29. PL to EPL 30. DonorInsertionFunction ReferencePT ECRL & ECRBWrist extensionJones 1921FCREPL, EPB, APL & EDC IF Thumb & index extension, thumbFCUEDC MF LFabductionFinger extensionPT ECRB Wrist extensionGoldner 1974FDS MF EPL (re routed)Thumb extension & abductionFCUEDCFinger extensionPT ECRB Wrist extensionBrand 1975PL EPLThumb extensionFCREDCFinger extensionPT ECRL & ECRBWrist extensionBoyes 1970FCRAPL & EPBThumb abductionFDS RF EPL & EIPThumb & index extensionFDS MF EDC via interosseous m Finger extensionPT ECRB Wrist extensionBeasley 1970PL APLThumb abductionFDS LF EPLThumb extensionFDS RF EDCFinger extensionPT ECRB Wrist extensionSmith &FCUEDC & EPLDigit extensionHastings 31. Brand transfers for radial nerve palsy 32. Brand transfers for radial nerve palsy Boyes/Brand believes that finger extension is bestmonitored by synergistic FCR, and that EPL remainsmotored by PL FCU too strong and excursion too short for finger extensors FCU function as a prime ulnar stabiliser of wrist makes it too important to sacrifice Boyes also concluded that FDS excellent for fingerextensors because of greater excursion (70mm)therefore FDS MF to EDC FDS RF to EPL and EI (more independent control to thumb and IF) 33. Direct Nerve Transfers Transfer of intact nerves to denervatedmuscles. MacKinnon and associates Median nerve supplies redundant branches to FDSand therefore available for transfer Or branches to PL and FCR (if these tendons notused for transfer) 34. Post-Operatively Long arm splint immobilisation for 4 weeks 15-30 pronation wrist 40 extension MPJ 10-15 flexion Thumb in maximal extension and abduction PIPJ fingers left free ROS & change splint at 10-14 days AROM hand therapy begins at 4 weeks Removable short arm splint to extend fingers, thumb andwrist for further 2 weeks, only removed for exercises