Presentation on theme: "Physiology of Muscle, Tendon & Ligament Healing"— Presentation transcript:
1Physiology of Muscle, Tendon & Ligament Healing Jason R. Miller, DPM, AACFAS, FAPWCADept. of Surgery
2Purpose of LectureTendon repair and tenoplasty are important aspects of podiatric surgery.Ligament ruptures are common and repairs are often needed.Knowledge of tendon and ligament healing allow the surgeon to make appropriate decisions concerning procedures, materials, post-op care and possible complications.Understand the basic biology of nerves and their response to injury.
3DefinitionsTendon Transfer: Detachment of a tendon of a functioning muscle at its insertionTendon Transposition: Rerouting without detachment to assist in other functionsMuscle-Tendon Transplantation: Detachment of a muscle tendon at both the origin and insertion to a new location with the NV structures intact.Tendon Suspension: Tendon supports a structure
4Tendon Anatomy Very strong, stronger than muscle for size As strong as bone with a failing point similar to steel!Can transmit force through ability to glidePassive component of the musculotendinous unit in light of their incredible influence on the foot.
5Tendon Histology 30% Collagen, 2% Elastin, 68% Water Bulk is supplied by reticulin70% Type I collagen
6Ligament Histology 33% Composition: 90% Type I collagen, Elastin, Glycosaminoglycans.67% Water
7Anatomy of the TendonTropocollagen – the most basic molecular unit of tendon3 Coverings:Endotenon- fascicles are surrounded by this areolar CT, contains BV, L, N, and FB.Epitenon- Fascicles bound together by this 1-2 cell fibroblastic & synovial layerParatenon- loose areolar layer continuous with the epitenon & perimysium, straight.
8Anatomy of the TendonTendon/Synovial Sheath: acts like a pulley when tendon has an angled course.Peritenon- term applied collectively to all CT structures associated with a tendon incl para-, meso-, epi-, and endotenon.
11Tendon Circulation 3 Sources: Small amount from the central blood vessels originating in the muscle.Some from vessels of the bone and periosteum near the tendon’s insertion.Majority comes from small vessels in the paratenon or through the mesotenon. If absent then carried thru the vincula. Synovial fluid also nourishes the tendon.
13Tendon Innervation Afferent supply only Source in musculotendinous junction and external local nerves.Golgi tendon organs: monitor increases in tension rather than length.
14Tendon Attachment to Bone Attach at 90° angles to bone in 4 layers:Tendon collagen fibersFibrocartilageBoneSharpey’s fibers – originate in bone and end in perisoteum.
15Tendon Healing4 StagesStage 1: Severed ends joined by fibroblastic splint. At the end of this stage, the repair site is in its weakest state with serous material & granulation tissue (Zone of degeneration) 1 week
16Tendon HealingStage 2: Increase in paratenon vascularity and collagen proliferation.2 weeksStage 3: Collagen forms longitudinally, increases strength. Controlled passive motion is beneficial to decrease fibrous adhesions.3 weeks
17Tendon HealingStage 4: Fibers align, increasing strength further. Swelling and vascularity reduce. AROM can be performed.4 weeks
18Tendon Healing Healing can be augmented by: Early mobilization US Elec. Stim.Growth factors
19Tendon LengtheningMuscle strength will be reduced by one grade (Polio Foundation) once healed.Transfers will equally degrade muscle strength.
20Tendon SutureSurgilon®: Non absorbable, non reactive. Increased strength during end of Stage 1.Stainless steel: Strongest, least reactive. Should be removed, can tear thru tendon.Silk: Old school surgeons.Tevdek®/Ticron®: Nonabsorbable braided polyester, resists gapping at 3 weeks better than nylon or polypropylene.
21Tendon SutureVicryl®/Dexon®: Absorbable polygalactic acid/polyglycolic acid strong enough to keep repair intact.Ethibond®: Strong, Non absorbable braided polyester. Good choice.
22Methods of Tendon Repair Bunnell end to end: Strong, but restricts tissue.Double right angle: Quick, for small tendons.Lateral trap: Tightly pulls edges of tendon together w/o damaging central microcirculation
23Methods of Tendon Repair Chicago: Simple X stitchRobertson: Best method of anastomosis for tendons of differing sizes.Interlace: Method for attaching small to large tendons.Herringbone stitch & insertion: Method for grafting one tendon into center of another.
24Securing Tendon To Bone Trephine plug3 Hole SutureButtress & button anchorTunnel w/ slingScrew & washer (cleated polyacetyl, Ti)STATAC, Mitek, PEBA
25Objectives of Tendon Transfer To improve motor function where weakness or imbalances exist to prevent deformity.To eliminate deforming forcesTo provide active motor powerTo provide better stabilityTo eliminate or reduce need for bracingTo improve cosmesis
26Principles of Transfer Do not create new imbalancesUnderstand anatomy & physiologyCorrect fixed/structural deformities 1stPerform at appropriate ageSelect suitable tendonProvide a mechanically efficient line of pullPerform stabilizing procedures 1st
27Principles of Transfer Preserve the gliding mechanismUse atraumatic techniquePreserve neurovascular supplyProvide adequate muscle-tendon tensionUse secure fixation techniquesAppropriate post-op management
28Ligamentous HealingTreated similarly to tendon, blood supply similar without muscular blood supplyHealing stages similarPrimary repair of initial ruptures is preferredSuture choices same as tendon.
30Nerve Healing & Repair Nerve fibers Basal lamina layer Ensheathed by Schwann cellsMyelinated fibers are individually encasedNon-myelinated fibers are encased in groupsBasal lamina layerEnvelops Schwann cellsCritical role in supporting axonal regeneration by serving as a “highway”
31Nerve Healing & Repair Endoneurium Perineurium Myelinated & unmyelinated are embedded with this CTPerineuriumCompact layer that encircles the endoneurium composed of concentric, elongated perineural cells
32Nerve Healing & Repair Perineurium Internal Epineurium Partitions nerve fibers into fasciclesInternal EpineuriumExternal EpineuriumConcentric layers of CT encircling the fasciclesContain fibroblasts, macrophages, mast cells, BVs, and fat
34Seddon classification Neurapraxia - mildest grade of nerve injuryReduction or complete blockage of conduction across a segment of nerve.Axonal continuity is maintainedNerve conduction is preserved proximal & distal to the lesion but not across itUsually reversible injuries, full recovery in days to weeks.
35Seddon classification Etiologies:Direct mechanical compressionIschemia/PVDMetabolic derangementsDisease or toxinscausing demyelination
36Seddon classification AxonotmesisInterruption of the axons with preservation of the surrounding CT “highway”Distal Wallerian degeneration of the axons occurs during a several day periodDirect e-stim will NOT give rise to nerve conduction or muscle responseRecovery can occur through axonal regeneration due to CT highway
37Seddon classification Schwann cells proliferate and form longitudinal conduits (bands of Bungner) through which axons regenerate in months.Recovery depends on:Extent of retrograde axonal lossTime to regenerate & reinnervate target muscles/sensory end organsRegenerate at 1mm/day
38Axonotmetic Injuries Mixed sensory & motor nerves regenerate slower Nerve complexity dictates accuracy of nerve regeneration
39Seddon Classification Neurotmesis – most severe gradeDisruption of axon, myelin, and CT “highway” components of nerve.Recovery through regeneration cannot occurExternal continuity is preserved but intrneural fibrosis occursAlso includes complete loss of continuitySurgery is required to remove roadblocks to healing.
40Sunderland Classification Created 5 grade system.Grade I – neurapraxic injuryGrade II – axonotmetic injuryGrade III – endonerium disruptedGrade IV – additional disruption of perineuriumGrade V – epineural continuity is disrupted (neurotmesis)
41Mackinnon & Dellon Added Grade VI Combinations of the previous grades of injury.
42Operative Decision Making Open injury:Lesion in continuityMedical mgmt. with close F/U, EMG/MRNLesion DiscontinuitySharp transection – end to end repairBlunt transection – delayed repair, resect scar, graft, repair.
43Operative Decision Making Closed Injury:Majority caused by stretch and/or compressive forces.Hematoma may require emergent surgery (ie compartment syndrome, pseudoaneurysm)Most injuries do not involve transectionMay represent any of Seddon’s 3 grades
44SummaryGuidelines will help you as a surgeon to deal with tendon, ligament, & nerve injuries.Understanding principles will lead to more successful repairs and mgmnt.