3 What is a tendon transfer? The tendon of a functioning muscle is detached from its insertion and reattached to another tendon or bone to replace the function of a paralysed muscle or injured tendon. The transferred tendon remains attached to its parent muscle with an intact neurovascular pedicle.
4 What is a tendon transfer? “Using the power of a functioning muscle unit to activate a non functioning nerve/muscle/tendon unit”.Tendon transfers work to correct:instabilityimbalancelack of co-ordinationrestore function by redistributing remaining muscular forces
5 Indications Paralysed muscle Nerve injury – peripheral or brachial plexusHigh cervical quadriplegia (needs some input to brachial plexus/hand)Neurological diseaseNerve repair with early transfer as internal splintInjured (ruptured or avulsed) tendon or muscleConsiderationsGraft vs. transfer (adhesions more likely in graft – 2 anastomoses)Quality of available donorsLength of time since injuryNature of tendon bedBalancing deformed hand e.g. cerebral palsy or rheumatoid arthritisSome congenital abnormalities
6 General principles1. Only justified in restoring functional motion of the hand, not just motionNot all patients require the same functions/motions2. Patient factorsAgeFunctional disabilities with poor non operative prognosisAbility to understand nature and limitations of surgery, including aesthetic goalsMotivated to co-operate with post operative physiotherapy
7 General principles 3. Recipient site “Tissue Equilibrium” concept as per Steindler/BoyesTissue bed into which transfer is placed should be soft and suppleGood soft tissue coverageStable underlying skeletonFull passive range of motion of joints to be poweredArea to be powered must be sensate
8 General principles Amplitude of the donor muscle 4. Donor muscle factors (APOSLE)Amplitude of the donor muscleShould be matched to the unit being replacedFinger flexors mm,finger extensors and EPL mm,wrist flexors / extensors mm,brachioradialis mmAmplitude 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 wristTenodesis effect during active movementFreeing fascial attachments to donor tendonsInserting the tendon closer to the joint being moved, but this requires a motor unit of increased power (due to leverage); and vice versa
9 General principles Power of the donor muscle Any transferred muscle loses at least one grade of strength, so only Grade 5 muscles are satisfactory (Grade 4, or 85% normal strength, can be sufficient for some transfers). Donor muscle strength should be maximised pre-operatively.Strongest are brachioradialis and FCU. Donor power correlated roughly with cross sectional area of muscle and fibre lengthOverly powerful muscles will unbalance and, over time, deform a joint. So muscle power should be matched if possible.Effective power of a transfer can be increased by placing the tendon insertion farther from the joint axis and as close to 90° as possible
10 General principles One tendon, One function Effectiveness reduced in transfer designed to produce multiple functionsSynergistic muscle groups are generally easier to retrainFist group – wrist extensors, finger flexors, digital adductors, thumb flexors, forearm pronators, intrinsicsOpen hand group – wrist flexors, finger extensors, digital abductors, forearm supinatorsUse of synergistic muscles tends to help retain joint balance
11 General principles Line of transfer Should approximate pull of original tendon if possibleAcute angles should be avoidedExpendabilityTransfer must not cause loss of an essential function
12 General principles 5. Other muscle factors of secondary importance Innervation - Donor muscle should be independently innervated and not act in concert with other motors (eg lumbricals)Availability or necessity of antagonists eg brachioradialis is an effective wrist extensor 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 that reverses their proposed activity” (Lister’s 4th Edn)7. Location and nature of pulley if required
13 General principles 8. Selected arthrodeses Simplify polyarticular systemStabilise jointsArthrodeses useful in providing stable pinch gripThumb MPJ and IPJIndex PIPJ and DIPJ
14 General principles 9. 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 resultsNerve gap>4cmLarge wound or extensive scarringSkin loss over nerve10. Comparison to alternativesNerve repair or transferTendon repair or graftTenodesis (joint stabilisation by anchoring tendons that move the joint)ArthrodesisAmputationMuscle lengthening, release or denervation (in spasticity)
15 General principles 11. Contraindications Age – due to joint stiffness, decreased need for power movements and difficult rehabilitationMotivation – patients must be concerned about disability and highly motivated to perform hand rehabilitationTask analysis – transfers must be designed to accomplish tasks rather than just specific motions. Eg opening doors requires grasp and twistNature of disability – systemic and local disease factors must be controlled before reconstruction attempted12. DisadvantagesNo increase in strengthNormal function of transferred muscle is lostTransferred tendon may perform a different force, amplitude of movement and functional patternTransferred tendon must learn a new movement/function
16 Selecting donor tendons Based on Smith & Hastings (Principles of tendon transfers to the hand. Instr Course 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
17 Maximising Success / Surgical Technique Incisions should not cross the path of the transferred tendonAvoid interference with normal structuresTendon 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 excursionThe transferred tendon should insert into another tendon or bone. Strong insertions allow earlier mobilisation.
18 Maximising Success / Surgical Technique 5. 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.
19 Maximising Success / Surgical Technique Joint should be initially immobilised in a position that relieves tension at the insertion of the transferReverse order – harvest grafts, prepare recipient site and tunnel before raising muscle
20 General Post Operative Management Rehabilitation is equally important in tendon transfer success as surgical executionRehabilitation / physiotherapy is essential inRegaining joint mobility lost during splintingTraining tendon to glide in new courseTeaching patients to activate a new muscle to achieve a certain function, which requires development of new neural pathwaysThe more that a patient notices a disability, the greater the motivation, so the easier the retrainingChildren are usually managed with static protocols or longer protective phase
21 Basic Principles of Post Operative Rehabilitation Described by Toth 19861. Protective phaseBegins at surgery and lasts 3 – 5 weeksObjectives:-Protective splintingOedema controlMobilise uninvolved joints2. Mobilisation phaseBegins when tendon healing is adequate for activation (usually 3 – 5 weeks post op)ObjectivesMobilise tendon transferImmobilise soft tissueContinue immobilisation of uninvolved joints to prevent joint stiffness from disuseReinforce preoperative teaching and patient educationContinue oedema control and protective splintingBegin home rehabilitation programUsually day time dynamic splinting with nightly static splinting
22 Basic Principles of Post Operative Rehabilitation 3. Intermediate phaseBegins 5 – 8 weeks post operativelyGradually increases hand activity and passive range of motion exercisesLimited functional movements permitted4. Resistive phaseBeginning at 8 – 12 weeksTendon junctions are strong enough to withstand increasing resistanceTherapeutic objective is to increase endurance and strength of transferred musclesWork related simulated tasks are begun to patient tolerance
23 Radial Nerve PalsyNeed to differentiate between complete radial nerve palsy (includes triceps) and posterior interosseous palsyBrachioradialis and ECRL are innervated prior to termination into posterior interosseous and sensory branches of radial nerveSevere impairment due to loss of extension power to the wrist, fingers, thumb and loss of radial abduction of the thumbWrist extension is critical for stability, which is essential for grip and assisting the function of many tendons crossing the wrist
24 Tendon Transfers Well defined and highly effective, aiming to replace Wrist extensionFinger extensionThumb extension and abductionStandard – accredited to Riordan 1964
25 Radial Nerve Palsy Non-Operative Treatment Splintage Burkhalter observed grip strength increased 3-5 by simply stabilising the wrist with splintageTailor to needs of patientBrand 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 transfersMaintenance of full passive ROM in all joints of the wrist/hands and prevent contractures
26 Radial Nerve Palsy Early transfers (“Internal Splintage”) Burkhalter believes greatest functional loss is grip strength therefore advocated early PT to ECRBTherefore eliminate need for external splint plus also restore grip strength3 indications:Works as substitute during early regenerationWorks as helper by adding power to reinnervated muscleActs as substitute in cases which results of nerve repair are poor (eg chronic/crush injuries or elderly)
27 Riordan Transfer Donor Insertion Function PT ECRB Wrist dorsiflexion FCUEDC IF - LFFinger extensionPLEPL (rerouted)Thumb extension
33 Brand transfers for radial nerve palsy Boyes/Brand believes that finger extension is best monitored by synergistic FCR, and that EPL remains motored by PLFCU too strong and excursion too short for finger extensorsFCU function as a prime ulnar stabiliser of wrist makes it too important to sacrificeBoyes also concluded that FDS excellent for finger extensors because of greater excursion (70mm) thereforeFDS MF to EDCFDS RF to EPL and EI (more independent control to thumb and IF)
34 Direct Nerve Transfers Transfer of intact nerves to denervated muscles.MacKinnon and associatesMedian nerve supplies redundant branches to FDS and therefore available for transferOr branches to PL and FCR (if these tendons not used for transfer)
35 Post-Operatively Long arm splint immobilisation for 4 weeks 15-30 pronationwrist 40 extensionMPJ 10-15 flexionThumb in maximal extension and abductionPIPJ fingers left freeROS & change splint at daysAROM hand therapy begins at 4 weeksRemovable short arm splint to extend fingers, thumb and wrist for further 2 weeks, only removed for exercises
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