Flexor Tendon Injuries

Flexor Tendon Injuries
Leul Merid Orthopedic surgery resident (R-1)

Outline Introduction Basic Science: Injury zones Tendon Repair:
Rehabilitation Outcomes Recommendation Primary repair Reconstruction References

Historical background

Restoration of satisfactory digital function after flexor tendon lacerations remains one of the most challenging problems in hand surgery Prior to the 1960’s tendons lacerated in “no man’s land” were not repaired in favor of delayed grafting

Kleinert and Verdan (1960’s) showed superior results with primary repair leading to general acceptance of this approach Years of anecdotal experience and surgical dogma followed pertaining to repair techniques and postoperative management

In the past 25 years more scientifically sound research has advanced our understanding of flexor tendon structure, nutrition, healing, biomechanics, response to stress, repair techniques Many studies have examined passive and active motion protocols Greatest limiting factor: absence of a universal system for assessing outcome

Questions Primary repair vs delayed grafting? Repair of FDS and FDP vs FDP alone? Flexor sheath excision? repair? neither? Type of suture material? Repair technique? Benefit of postoperative motion? Active or passive? How much?

Tendon Morphology 70% collagen (Type I) Extracellular components
Elastin Mucopolysaccharides (enhance water-binding capability) Endotenon – around collagen bundles Epitenon – covers surface of tendon Paratenon – visceral/parietal adventitia surrounding tendons in hand Synovial like fluid environment

Surgical anatomy The microscopic anatomy of the tendon consists of a
A central core (the endotenon) that is composed primarily of acellular, longitudinal, collagenous fibers that are sparsely interspersed with fibroblasts. A thin epitenon layer of cells surrounds the central core. The epitenon cells are fibroblasts that may have different functional properties and characteristics from the internal fibroblasts of the endotenon. The epitenon cells are arranged in a matrix that is presumed to have a proteoglycan composition.

Anatomy Extrinsic flexors Superficial group PT, FCR, FCU, PL
Arise from medial epicondyle, MCL, coronoid process

Anatomy Extrinsic Flexors Intermediate group FDS Arises from medial
epicondyle, UCL, coronoid process Usually have independent musculotendinous origins and act independantly

Anatomy Extrinsic flexors Deep group FPL – originates from
entire medial third of volar radius FDP – originates on proximal two thirds of the ulna, often has common musculotendinous origins

Anatomy Carpal tunnel 9 tendons Median nerve
FDS runs with 3rd and 4th slips superficial to 2nd and 5th FDP often indistinct here and proximal Median nerve is superficial to tendons At the wrist level ten structures pass through the carpal tunnel 4xfds, 4xfdp, fpl and median nerve Bordered by: hamate, triquetrum and pisiform and ulnarly Scaphoid and trapezium radially Roof = flexor retinaculum Consists of three components – the the deep forearm facsia, the transverse carpal ligament (which traverses from the scaphoid tuberosity and trapezial beak radially to the hook of the hamate and pisiform ulnary) and the distal aponeurosis btw the thenar and hypothenar muscles

Carpal Tunnel

Anatomy Flexor sheaths approx distal palmar crease
Predictable annular pulley arrangement Protective housing Gliding surface Biomechanical advantage Synovial layers merge at MP level Flexor tendons weakly attached to sheath by vinculae Pulleys A2 and a4 (most biomechanically important) arise from periosteum of proximal aspect of proximal phalanx, and middile aspect of middle phalanx (respectively) A1 a3 and a5 (joint pulleys) arise from volar plates of mp, pip and dip joints respectively Intervening cruciate pulleys (c1 c2 and c3) are thin and collapse to allow annular pulley approximation during flexion

Anatomy Camper’s Chiasma In the palm FDS is superficial to FDP
In the proximal sheath fds divides to allow fdp to pass through and go on to insert at the base of the distal phalanx Fds the reunites at camper’s chiasm before dividing into two slips of insertion on the base of the middle phalanx At the base of the fingers, the superficialis tendons divide,allowing the deeper profundi tendons to pass through themto become volar or superficial to the FDS . Each of the two slips of the penetrated FDS cross under the FDP,rotate 180 degrees, and rejoin at the Camper chiasm, and inserton the middle phalanx as the prime flexor of the proximal interphalangeal (PIP) joint.

Camper’s Chiasma Care should be taken when the flexor sublimis has been injured in the area just proximal to the proximal interphalangeal joint and distally where the orientation of the proximal and distal portions of the tendon can be misinterpreted and repairs may be incorrectly done with the sublimis slips malrotated Care also should be taken to deliver the flexor profundus tendon through the split portion of the flexor sublimis when the profundus tendon has retracted proximally

Tendon relationships Flexor digitorum sublimis spiral. Flexor digitorum sublimis separates just distal to level of metacarpophalangeal joint with finger in extension. It winds around profundus tendon to chiasma of Camper, where it decussates to insert in middle phalanx. Superficial portion of proximal sublimis tendon becomes deep at level of chiasma of Camper. If laceration is sustained in sublimis at midpoint of this spiral arrangement of both slips, proximal and distal ends rotate through 90 degrees, but in different directions. An unwary surgeon would be presented with two ends that do match, that appear to lie in good relationship, and that can be so sutured. If this is done, channel for profundus tendon is obliterated. If error is not noted and corrected, effect would be to block excursion of tendon and eliminate satisfactory motion Separated position of two tendon ends in distal palm after flexor tendon interruption and proximal retraction. Correctly position profundus in sublimis hiatus before passing tendons distally into digit. Reestablish anatomical relationship of profundus and sublimis tendon stumps so that they can be correctly repaired to corresponding distal tendon stumps. In some cases, profundus must be passed back through hiatus created by sublimis slips to lie palmar to Camper chiasma and to recreate position of tendons at level of tendon laceration.

Vincula Long and Short to each tendon in fingers
Long variable Short VBP inserts at head of middle phalanx VBS at head of proximal phalanx Provide some vascular supply Can confuse exam Thumb Vinculum brevis to FPL in 90% Inserts on IP volar plate and distal part of proximal phalanx

Vincula

Tendon Nutrition Vascular Synovial fluid diffusion
Longitudinal vessels Enter in palm Enter at proximal synovial fold Segmental branches from digital arteries Long and short vinculae Vessels at osseous insertions Synovial fluid diffusion Imbibition (pumping mechanism)

Tendon Nutrition Dorsal vascularity Avascular zones
FDS (over proximal phalanx FDP (over middle phalanx) Nutrition vital for rapid healing, minimization of adhesion and restoration of gliding

Biomechanics Effeciency of flexor system = the degree to which tendon excursion and muscle contraction translates into joint motion Governed by integrity of the pulley system and resistance to glide A2 and A4 most significant Pulleys decrease the moment arm length at each joint leading to increased joint motion

Biomechanics

Tendon Healing Fibroblastic phase (5d – 6 wks)
Inflammatory phase (0-5 d) Strength of the repair is reliant on the strength of the suture itself Fibroblastic phase (5d – 6 wks) collagen-producing phase Remodelling (6 wks-9 mos)

Tendon Healing Two forms Intrinsic healing Extrinsic healing
occur through the activity of the fibroblasts derived from the tendon. Extrinsic healing occurs by proliferation of fibroblasts from the peripheral epitendon adhesions occur because of extrinsic healing of the tendon and limit tendon gliding within fibrous synovial sheaths Balance between the two determines amount of extrinsic adhesion vs intrinsic tendon healing The extrinsic mechanism occurs through the activity of peripheral fibroblasts, whereas the intrinsic healing seems to occur through the activity of the fibroblasts derived from the tendon.

Tendon Healing Factors affecting tendon healing, and adhesion formation Surgical technique decreased vascularity Gapping Meticulous technique Postoperative motion (passive, active)

Tendon Adhesion Increased adhesion formation with:
Traumatic/surgical injury Crush injuries Ischemia Disruption of vinculae Immobilization Gapping at repair site Excision/injury to flexor sheath components Debate over benefit of sheath repair

Tendon Adhesion Experimental attempts to minimize adhesion formation
Oral: steroids, antihistamines, NSAIDS Topical: beta-aminoproprionitrile, hydrocyprolins, hyaluronic acid, collagen solutions, fibrin Physical: silicone/cellophane wrapping, polyethylene tubes, interposed sheath flaps Varying lab success but none proven definitively or adopted into clinical practice

Tendon Healing “It now seems irrefutable that the most effective method of returning strength and excursion to repaired tendons involves the use of strong, gap resistant suture techniques followed by the frquent application of controlled motion stress” -Strickland

Diagnosis hx p/e Age, occupation, dominant hand
Causes Sharp object RTA Sport inj Rupture Machine inj bite Volar and dorsal skin integrity Angular deformities Met, phal #/dsl Distal NV Capillary refill, 2 pt discr Continuity of the tendon Discuss nature of injury and postoperative course with patient

How to recognize flexor tendon injury
1.Natural position of fingers , cascade 2.Passive extension wrist not produce flexion 3.Wrist flexion even greater extension of finger 4.Loss of normal tension of affected finger 5.Loss of active flexion(difficult elicit in acute-pain)

6.FDP unable to flex DIP wiz PIP stabilized FDP flexes distal phalanx
Usually tethered except for index 7.FDS unable to flex PIP , when adj 2 fingers kept fully extended FDS flexes middle phalanx Independent slips Hold adjacent digits in full extension For index use paper grip test 8.Both tendons neither PIP nor DIP flex, wiz MCP immobilized 9.FPL IP not flexed , MCP stabilized 10.Weakness of hand with inability to hold objects 11.Incomplete closure of fingers wiz wide digit to palmar distance Testing for a suspected superficialis tendon laceration in the presence of an intact profundus tendon is more difficult. The surgeon must eliminate the flexion force of the profundus tendon by making use of the quadriga effect To do this, manually hold the distal joints of the adjacent digits in full extension while the patient attempts to flex the involved finger. An inability to flex the involved digit actively at the proximal interphalangeal joint indicates a lacerated superficialis tendon.

Flexor Tendon Repair Timing Incisions Tendon Retrieval
Repair Techniques Relationship of suture design to biomechanical strength Strickland stresses six characteristics of an ideal tendon repair: (1) easy placement of sutures in the tendon, (2) secure suture knots, (3) smooth juncture of tendon ends, (4) minimal gapping at the repair site, (5) minimal interference with tendon vascularity, and (6) sufficient strength throughout healing to permit application of early motion stress to the tendon.

Timing Delayed equal or better than emergent repair
1.Primary repair Golden period With in 24hrs in a clean wound Best results 2.Delayed primary repair 24-10 days Done: suspicion of infection , viability questionable or came late 3.Secondary repair --b/n 10-14days up to 4wks 4.Late secondary After 4 wks Delayed equal or better than emergent repair Acute or subacute acceptable Tendon deterioration/shortening after several wks Delay several days if wound infected

Incisions Factors Avoid crossing joints at 90 deg. Preference
Existing lacerations Need to expose other structures Generally a combination of zig zag or mid lateral incisions are used Depend on Direction of initial laceration Need to expose other injured structures Surgical preference Little advantage to limiting exposure Avoid crossing jt creases at rigth angles

A, Incision outlined on digit and palm
A, Incision outlined on digit and palm. B, Exposure of flexor tendon sheath after flap elevation. C, Closed incision

Tendon Retrieval Avoid trauma to synovial sheath lining
Forcep/hemostat/skin hook if proximal stump visible Proximal to distal milking, reverse esmarch Suction catheter Suture catheter to proximal tendons in palm and deliver distally Retraction often limited to A1/A2 pullet region by vinculae If lacerated proximal to vinculae or if vinculae disrupted, tendon ends may retract into plam If proximal stumps have retracted into the palm the correct orientation of FDS and FDP must be re-established (such that FDP lies volar to Camper’s Chiasm

Tendon Retrieval Retraction often limited to A1/A2 pulley region by vinculae If lacerated proximal to vinculae or if vinculae disrupted, tendon ends may retract into plam If proximal stumps have retracted into the palm the correct orientation of FDS and FDP must be re-established (such that FDP lies volar to Camper’s Chiasm) Retraction often limited to A1/A2 pullet region by vinculae If lacerated proximal to vinculae or if vinculae disrupted, tendon ends may retract into plam If proximal stumps have retracted into the palm the correct orientation of FDS and FDP must be re-established (such that FDP lies volar to Camper’s Chiasm

Tendon Advancement Previously advocated for zone 1 repairs, as moving the repair site out of the sheath was felt to decrease adhesion formation Disadvantages Shortening of flexor system Contracture Quadregia effect Little excursion distally, therefore adhesions near insertion less of an issue

Repair Techniques Ideal Gap resistant
Strong enough to tolerate forces generated by early controlled active motion protocols 10-50% decrease in repair strength from day 5-21 post repair in immobilized tendons This is effect is minimized (possibly eliminated) through application of early motion stress Minimal bulk Uncomplicated Minimal interference with tendon vascularity Strickland stresses six characteristics of an ideal tendon repair: (1) easy placement of sutures in the tendon, (2) secure suture knots, (3) smooth juncture of tendon ends, (4) minimal gapping at the repair site, (5) minimal interference with tendon vascularity, and (6) sufficient strength throughout healing to permit application of early motion stress to the tendon.

The R/ship suture design to biomechanical strength of repair

To provide tendon repairs of sufficient strength to permit passive and active motion rehabilitation
Repair Techniques – Concepts Suture material , caliber Placement dorsal Vs volar Pass Locking Vs “grasping” 2 Vs 4 strands ? knot placement In Vs out Core , Epitendinous configuration Cutting vs tapered needle Avoid accordion , gapping Suture should be non-reactive, small caliber, pliable, strong, hold good knot. Locking stitches effectively strangle the tendon whereas, mod kessler does not. Gen accepted need 4 strands for flex tendon repairs. 6 too much and 2 too few. Needle: Lam et als J Hand Surg 2003 – no diff in failure of cutting vs tapered needle – HE, inc poss of cutting suture w/ cutting needle.

easy placement of sutures in the tendon, Secure suture knots,
Although there is general consensus regarding the timing of flexor tendon repair, there continues to be controversy regarding the ideal flexor tendon repair technique. Strickland outlined six characteristics that a flexor tendon repair should satisfy prior to clinical application — easy placement of sutures in the tendon, Secure suture knots, smooth junction of tendon ends, minimal gap formation at the repair site, minimal interference with tendon vascularity, and sufficient strength throughout healing to permit the application of early motion stress to the tendon. Although many repair techniques have been proposed, few satisfy all six criteria. Strickland cited the four-strand cruciate repair as an example of a repair that fulfills the six requirements of an ideal suture repair.

Suture Material/Size Polydiaxanone (PDS)
Historically stainless steel (strongest and least reactive) but difficult to work with Braided polyester Synthetics sutures (Ethibond, Ticron; Mersilene) -most commonly used Caprolactam family (Supramid) Nylon Polypropylene (Prolene) Polydiaxanone (PDS) Increased caliber felt to increase tensile strength 2-0 or 3-0 recommended with early active motion protocols as many 4-0 suture strength are less than the fatigue strength of many 2 and 4 strand repairs monofilament stainless steel to-Historically stainless steel (strongest and least reactive) Adv-have the highest tensile strength Disadv-it is difficult to handle, tends to pull through the tendon, and makes a large knot. Although it can be used satisfactorily in the distal forearm, these disadvantages limit its use in the fingers. Most absorbable sutures, both catgut and the polyglycolic acid group (Dexon; Vicryl), become weak too early after surgery to be effective in tendon repai Synthetic sutures of the caprolactam family (Supramid) and nylon maintain their resistance to disrupting forces longer than polypropylene (Prolene) and polyester suture, and O'Broin et al. found that polydiaxanone (PDS) was as strong as polypropylene. In clinical situations most surgeons find that the braided polyester sutures (Ticron; Mersilene) provide sufficient resistance to disrupting forces and gap formation, handle easily, and have satisfactory knot characteristics; consequently these sutures are widely used. Increased caliber felt to increase tensile strength 2-0 or 3-0 recommended with early active motion protocols as many 4-0 suture strength are less than the fatigue strength of many 2 and 4 strand repairs

Ultimate Strength and Repair Technique
Proportional to number of strands Number of strands Two strand- 2-3 kgf Four nearly doubles Six – 6.8 kgf 6 and 8 strand repairs strongest Steep learning curve Increased bulk and resistance to glide Increased tendon handling and adhesion formation May not be necessary for forces of early active motion Several four strand repairs appear to have adequate strength without complexity of 6 and 8 strand repairs

Lee (4 strand) and Savage (6 strand)

Dorsal vs Volar Historically dorsal placement avoided due to tendon vascular anatomy Diffusion now felt to be primary source of nutrition during healing Biomechanical advantage and increased tensile strength found during finger flexion with dorsal sutures (Komanduri, Soejima, Stein) Increase work of flexion with volar sutures (Aoki) Dorsal stronger Less vascular disruption on volar side

Length of suture purchase
no greater strength after 1cm. Weaker under 1cm For obliquely cut tendons. 2mm gap forming force. no greater strength after 1cm. Weaker under 1cm. Tan Etals JHS 9/04.

Locking vs Grasping Loops
Locking stronger, and greater gap resistance in two stranded repairs (Manske et al.) Dorsal vs volar placement did not affect strength with locking repairs, but did affect strength of grasping repairs (Stein) Single locking loop best

Locking v. Grasping

Direction of locking circles
horizontal weaker than perpendicular/oblique. Tan Etals JHS 9/04 horizontal weaker than perpendicular/oblique

Cross-Sectional Area Increasing the cross-sectional area of the locking loop from 10 to 50% proportionately increased the ultimate tensile strength of the repair (Hatanaka, Manske) Has been demonstrated with core and circumferential suture tecniques

Size of locking loop Found 25% tendon width locking loops did best
4 strand cruciate . 10,25,33,50% of tendon width locking loops. Found 25% tendon width locking loops did best. Oblique strands passed volar to long strands. 10% failed by cutting out of tendon. Second image: using 25% 4 strand cruciate w/ simple running, cross-stitch, interlocking horizontal mattress. Load to 2mm gap: 157, 196, 263% of no epi suture. Dona et als. JHS July 04.

Suture Knot Location In – interference with healing at repair site
Out – interference with tendon gliding Knots outside superior in one in vitro study (Aoki) Statistically significant increase in tensile strength at 6 wks with knots-inside technique in canine model (Pruitt) Few studies,No consensus Weak point Location inside 60-80% the strength of outside

Gap Formation Gapping at tendon repair site associated with increased adhesion formation in laboratory/histological analysis (Lindsay) Gapping > 3mm correlated with decreased tensile strength in canine model (Gelberman) Gapping > 2mm correlated with poorer clinical results (Seradge)

Suture Configurations
Group 1= Simple Simple sutures; the suture pull is parallel to the tendon collagen bundles Shearing parallel to bundles Weak Group 2=End-to-end locking Bunnell suture; stress is transmitted directly across the juncture by the suture material Pull converted to compressive force around bundles Strength near that of suture Group 3=Interweave Pulvertaft technique (fishmouth weave); sutures are placed perpendicular to the tendon collagen bundles and the applied stress Strongest Bulky SUTURE CONFIGURATIONS Urbaniak, Cahill, and Mortenson divided the various tendon repair types into three groups (Fig. 63-5). Group 1 is exemplified by simple sutures; the suture pull is parallel to the tendon collagen bundles, transmitting the stress of the repair directly to the opposing tendon ends. Group 2 is exemplified by the Bunnell suture; stress is transmitted directly across the juncture by the suture material and is dependent on the strength of the suture itself. Group 3 is exemplified by the Pulvertaft technique (fishmouth weave); sutures are placed perpendicular to the tendon collagen bundles and the applied stress. It was found that interrupted sutures were the weakest and therefore unsuitable in most tendon repairs. The fishmouth or end-weave repairs are the strongest and are most suitable for the distal forearm and palm areas, whereas the intermediate suture configurations (Bunnell; Kessler) did not differ significantly in strength from the bulkier repairs. Papandrea et al., in biomechanical tests of human cadaver tendons, found the epitenon-first technique (Fig. 63-6) to be 22% stronger than the modified Kessler technique; although the knot of the modified Kessler suture occupied 20% of the tendon cross section, the epitenon-first suture occupied 2.6% of the cross section.

Eight methods of tendon anastomoses can be placed into three basic groups. In group 1, suture applies shearing force to tendon ends parallel to collagen bundles and results in weak repair. In group 2, longitudinal pull of suture is converted to either oblique or transverse compressive force on tendon, and strength of repair approaches strength of suture material. In group 3, the strongest union, loading of tendon applies compressive force of tendon to tendon at right angles to longitudinal shearing forces.

End-to-end suture of tendon using Bunnell crisscross stitch

Bunnell

Kessler

The Kessler grasping suture is a modification of the Mason-Allen suture.
“Grasping” technique. 1, First knot grasps one quarter of tendon width. 2, Needle passes longitudinally through one segment, emerging through cut surface. 3, Thread engages second segment of tendon; half of grasping suture has been completed. 4, Beginning of second half of suture; second needle passes transversely through other segment of tendon. 5, Second half of suture (corresponds to 2). 6, Suture is completed, but cut surfaces have not yet been approximated. 7, End of procedure; two diagonally placed knots are tied up.

Modified Kessler (1 suture)

Kessler-Tajima (2 sutures)

Tajima tendon repair. Double-armed needles on suture are helpful for this method

A, Standard Kessler core stitch is inserted using a round-bodied needle. Suture is tied with knot between cut ends. B, Second suture is inserted at right angles to first, again using round-bodied needle. C, Needle is passed along tendon, across junction, and out of tendon. If needle is too short, it can be brought out at junction, then passed in again. D, Rest of suture is inserted. E, Suture is tied under carefully judged tension to match first, with knot on outside of tendon. F, Repair is completed with epitendinous suture.

Simplified four-strand repair in which basic two-strand core suture is supplemented by horizontal mattress suture and running-lock stitch. A, Tajima core sutures in place. Back wall (dorsal) running-lock peripheral epitendinous stitch in progress. B, Back wall suturing completed. C, Mattress core suture added in palmar tendon gap. D, All core sutures tied. E, Completion of running-lock peripheral epitendinous suture. F, Repair completed

Kleinert modification of Bunnell crisscross suture technique.

Cruciate 4 Strand Repair
The ideal repair? - Strickland - McLarney

Strickland modification of flexor tendon repair techniques described by Kessler and Tajima
Separate sutures are introduced in each tendon end at distance of 0.5 to 1 cm. Approximately 25% of diameter of tendon is grasped by separate needle passage and locked on side of tendon. Suture is passed transversely behind knot across tendon, where second-needle pass-and-lock suture is used to grasp tendon side. Finally, suture is passed behind second knot and down tendon-to-tendon end. After placement of similar suture in opposite end, two tendon ends can be brought together, and repair usually is tidied up by small circumferential suture. When in place in end of given tendon, protruding suture ends can be used to pass tendon through tendon sheath and position it for repair without needing to damage tendon with further instrumentation.

Double right-angle suture with single monofilament or multifilament wire suture threaded on curved needle.

Core Suture Techniques Common End-to-end types
Crisscross stitch 4-0 nylon nylon epi

Techniques for end-to-end flexor tendon repair

More techniques Mason-Allen stitch
Although interest is growing in the use of multistrand techniques to achieve stronger repairs, reduce the possibility of gap formation, and permit earlier active motion, many surgeons continue to use variations of a core suture (Fig ). Such techniques allow satisfactory purchase on the tendon so that satisfactory tensile strength is maintained during the early healing phase. These techniques also prevent cutting through and out of the tendon and are dependable in the fingers. The Bunnell "crisscross" (Fig ) is the classic technique of end-to-end suture. Although it is a good grasping suture, it is not in common use because it is believed that the intratendinous placement of the crisscross sutures tends to disturb the intratendinous circulation, rendering the ends of the tendon avascular. In some digits, precise suture passage also is technically difficult. The Kleinert modification of the Bunnell crisscross (Fig ) is somewhat easier to insert and probably causes less intratendinous ischemia. Because of the single crisscross, "straightening" of the suture within the tendon and gap formation are possible. The Kessler grasping suture (Fig ) is a modification of the Mason-Allen suture. This technique is effective for tendon repair in the fingers and palm. In the fingers it has the disadvantage of knots being left exposed on the tendon surface. Continuing the interest in multiple-strand modifications, such as those of Savage (six strands) (Fig. 63-7) and Lee (four strands) (Fig. 63-8), Silfverskiöld and Andersson found experimentally that the grasp of a "cross-stitch" (Fig. 63-9) of 6-0 braided polyester was 117% stronger than a modified Kessler core suture with a conventional epitendinous repair. Reporting their clinical experience with a cross-stitch modified Kessler combination, Silfverskiöld and May found the cross-stitch to be a reliable technique when combined with a program of early active and passive flexion. Currently, it is believed that intratendinous crisscross suture techniques (Bunnell; Kleinert modification of Bunnell) tend to jeopardize the intratendinous circulation (Fig ). Although placement of sutures in the volar half of the tendon is recommended to avoid injury to the circulation, experimental work by Soejima et al. showed that the mean strength of repairs sutured in the dorsal half of the tendon was 58.3% greater than that in the volar half. Wray and Weeks, using chicken flexor tendons, compared the rupture rates and tensile strengths of the Bunnell, Kessler, Kleinert, and Tsuge et al. repairs. They concluded that the use of any of these techniques for flexor tendon repairs could be expected to produce about the same results. It is important to remember that no suture material or technique can be relied on to maintain tendon repairs with unlimited active movement in the early postoperative period. Most investigators report that the strength of the tendon repair diminishes considerably in the first 10 days. Thereafter the strength of the repair gradually increases, so by the end of 10 to 12 weeks considerable active forces can be applied in the rehabilitation program. The strength of the a tendon repair is proportional to the number of the suture strands that cross the repair site The number of the suture knots in the repair site should be minimized Repairs are stronger when the core sutures are placed dorsally Mason-Allen stitch

Core Sutures Current literature supports several conclusions regarding core sutures Strength proportional to number of strands Locking loops increase strength but may collapse and lead to gapping Knots should be outside repair site Increased suture callibre = increases strength Braided 3-0 or 4-0 probably best suture material Dorsally placed suture stronger and biomechanically advantageous Equal tension across all strands

Circumferential Sutures
Initially were designed to improve tendon glide Have been shown to add tensile strength (by 10–50%) and gap resistance to repairs (Diao, Pruitt, Silverskiold, Wade) Also confirmed in cyclic loading studies Running locked, horizontal mattress, epitenon/intrafibre, and cross-stitch have been shown to be the strongest Significant strength improvement Simple 1 kgf Mattress 2 kgf Locking mattress 3 kgf

Type of epi repair Compare strength of epi repair w/o core suture. Simple running vs cross stitch vs interlocking cross stitch and interlocking horizontal mattress. Dona et als JHS 10/03

Type of epi repair Interlocking horizontal mattress suture
The IHM had best 2nd is simple (no sig diff), HE, load to failure was sig lower. Dona et als JHS 10/03 Interlocking horizontal mattress suture

Two basic versions of cross-stitch.
Two basic versions of cross-stitch. A, Suturing starts on far side of repair and proceeds toward operator. Simple overlap of each preceding grasp by approximately 50% automatically produces weave pattern without need for special needle passages. Symmetrical placement of grasps (used here for clarity) is unnecessary in actual practice. Grasp size, overlap, and distance to tendon edge can be adapted to needs as suturing progresses. B, Suturing starts on near side of repair; overlapping is unnecessary

Epitenon-first technique
After placement of running epitendinous suture, core suture is placed within tendon. B, Completion of epitenon-first suture. Final knot is buried within tendon.

Strength vs Force (Core suture with running epitendinous suture)
Some 2-strand repairs vulnerable during 1-3 wks post repair with light active motion FACTORS AFFECTING TENSILE STRENGTH The forces present at the flexor tendon repair site during passive digital motion, active digital motion, and active digital motion against resistance have been measured clinically in patients undergoing median nerve decompression at the carpal tunnel (59). Passive motion generates up to 0.9 kilograms force (kgf) in the digital flexor tendon. Active flexion against no resistance generates up to 3.9 kgf. Grasp against resistance generates up to 6.4 kgf, and tip pinch up to 12.0 kgf. Tendon repair rehabilitation protocols usually employ digital active or passive grasping activities. Consequently, 3.9â€“6.4 kgf is considered an appropriate approximation of the flexor tendon forces required to flex an uninjured finger. It should be noted that edema and increased tissue viscoelasticity associated with an injured digit probably result in increased resistance to flexion; therefore, the forces required to flex an injured digit following tendon laceration and repair are likely to be increased (23). The tensile strength of standard two-strand suture techniques (e.g., Kessler, Bunnell) is approximately 2â€“3 kgf, as measured in human cadaveric tendons (2,6,66). These tensile strength values have been shown (44,67) to diminish more than 30% to 40% in experimental studies in immobilized tendons during the early (5â€“10 days) postoperative period; these values recover at approximately 2â€“3 weeks. Several factors can impact the ultimate tensile strength and the resistance to gap formation at the repair site.

Repair Augmentation Augmenting repairs with tendon splints or mesh has been associated with concerns related to decreased tendon glide and increased adhesion formation due to foreign body reaction Has not been accepted in clinical practice

Sheath Repair Advantages Disadvantages
Barrier to extrinsic adhesion formation More rapid return of synovial nutrition Disadvantages Technically difficult Increased foreign material at repair site May narrow sheathand restrict glide Presently, no clear cut advantage to sheath repair has been established

AUTHOR'S PERSPECTIVE preferred technique for flexor tendon repair within the digital sheath follows the previously noted principles, but it also takes into consideration the ease or difficulty of suture placement. The core consists of two two-strand locking sutures (3-0 braided polyester) as described by the Pennington modification of the Kessler technique , resulting in four strands across the repair site. (If surgical exposure allows, a third locking suture can be placed, resulting in six strands.) The knots for each of the two sutures are tied within the repair site. The circumferential suture is a criss-cross suture using 6-0 Prolene.

Fish-Mouth End-to-End Suture (Pulvertaft)
Pulvertaft technique of suturing tendon of small diameter to one of larger diameter. A, Smaller tendon is brought through larger tendon and anchored with one or two sutures after tension is adjusted. B, Tendon is brought through more proximal hole and is anchored again with one or two sutures after tension is adjusted. C, After excess is cut flush with larger tendon, exit hole can be closed with one or two sutures. D, Excess of larger tendon is trimmed as shown to permit central location of smaller tendon. This so-called fish mouth is closed with sutures.

End-to-Side Repair Steps in technique of end-to-side anastomosis. End of tendon has been buried (6). Sutures are appropriately placed to fasten tendons together.

Tendon-to-Bone Attachment

Tendon attachment through finger flap.

One method of attaching tendon to bone
A, Small area of cortex is raised with osteotome. B, Hole is drilled through bone with Kirschner wire in drill. C, Bunnell crisscross stitch is placed in end of tendon, and wire suture is drawn through hole in bone. D, End of tendon is drawn against bone, and suture is tied over button.

Zone I injury. Profundus tendon is advanced and reinserted into distal phalanx using pull-out wire suture and tie-over button.

Rehabilitation Goal promote intrinsic tendon healing & minimize extrinsic scarring to optimize tendon gliding & functional range of motion Early post-repair motion stress _ biologically alter the process of scar formation and maturation at the repair site such that collagen is laid down parallel to the axial forces (increase strength), and decrease adhesions :tendon adhesions are stretched (increased tendon glide) Load at failure for mobilized tendons twice that for immobilized tendons at 3 wks (Gelberman)

Rehabilitation Bunnel (1918) Postoperative immobilization
Active motion beginning at 3 wks postop. Suboptimal results by today’s standards Improved suture material/technique as well as postoperative rehabilitation protocols

Immobilization programme
Indicated Children and adults who r unable to comprehend and follow thru with a cpx mobilization protocol Associated injury to the adjacent structure sa fracture d/ors and health conditions that affect tissue healing sa RA

Kleinert splint with palmar pulley
Posterior splint, wrist in flexion Rubber bands from fingernails to volar wrist area hold fingers in flexion Patient able to actively extend against rubber bands (within confines of splint) Fingers pulled passively back into flexion Used widely since with some modifications Showed superior results with primary repair vs delayed grafting

Duran programme Designed premise that 3-5mm of tendon glide would Px restriction adhesion Passive DIP ext wiz PIP,MP in flex=glide FDP away from FDS suture site Passive PIP ext wiz DIP,MP in flex=glide both tendons away from injury site

Duran and Houser A, Diagram of controlled passive motion exercise. Metacarpophalangeal joint should remain in normal balanced position. Extension of distal interphalangeal joint is sufficient to move anastomosis 3 to 5 mm. Only distal interphalangeal joint moves during this exercise. B, Note distal migration of anastomosis of flexor digitorum profundus tendon away from that of flexor digitorum sublimis tendon. C, When middle phalanx is extended, both anastomoses glide distally. Only proximal interphalangeal joint moves during this exercise. D, Anastomoses are moved away from fixed structures that may have been injured. Elastic traction returns finger to original position.

Strickland’s active motion prog.
Depend on strong repair technique Force applied during rehab. <TS of repair to Px gapping/rupture Combined MP flex+WRIST ext=least tension on repair site to allow most d/tial excursion b/n FDP and FDS=tenodesis motion with hinged splint Req’t : Good pt cooperation and comprehension Controlled edema Minimal wound complication

The patient actively maintains digital flexion and holds
tenodesis splint with a wrist hinge is fabricated to allow for full wrist flexion. wrist extension of 30 degrees. and maintenance of MCP Ilexion of at least 60 degrees. After composite passive digitaillexion. the wrist is extended and passive flexion is maintained. The patient actively maintains digital flexion and holds that position for about 5 seconds. Patients are instructed to use the lightest muscle power necessary to maintain digital flexion. n, A tenodesis splint with a wrist hinge is fabricated to allow for full wrist flexion. wrist extension of 30 degrees. and maintenance of MCP Ilexion of at least 60 degrees. C, After composite passive digitaillexion. the wrist is extended and passive flexion is maintained. D, The patient actively maintains digital flexion and holds that position for about 5 seconds. Patients are instructed to use the lightest muscle power necessary to maintain digital flexion.

There are protocols that incorporate EAM while using a kleinert:
EVANS SLFVERSKIOLD and MAY Based on force application and individual tissue response=GROTH proposes a methodic rehab model .can be used with any existing protocol,not limited to zone,type of repair, or time of sequence .Flexion lag , resolution lag

Groth’s pyramid of progressive force application
Resistive isolated joint motion Resistive hook and straight fist Resistive composite fist Isolated joint motion Hook and straight fist Active composite fist Place and hold finger flexion Passive protected digital extension

Differential gliding exercises
Flexor tendon gliding exercises as described by Wehbé and Hunter. The five positions are neutral (A); angle position with the metacarpophalangeal joints at 90 degrees of flexion and interphalangeal joints neutral glides the flexor digitorum superficialis tendon with more excursion than the flexor digitorum profundus (B); the straight fist position places the metacarpophalangeal and proximal interphalangeal joints in full flexion with no flexion at the distal interphalangeal joint, creating maximum excursion for the flexor digitorum superficialis (C); the hook fist position, which positions the metacarpophalangeal joints in neutral and the proximal interphalangeal and distal interphalangeal joints in maximum flexion, creates the greatest differential excursion between the two tendons (D); and the full fist position, in which all joints are flexed maximally creates maximum flexor digitorum profundus gliding (E).

FDP and FDS blocking exercises

Grading outcome Boyes Strickland
A no of systems suggested to report function of finger(digital performance) Most used calculating or estimating ROM Boyes FOF estimated by msr distance b/n pulp and distal palmar crease Distance relates to amt of composite flexion & gives est finger function Quick & easy Strickland Dev’d formula for reporting results Most stringent system currently available for measuring results Accurately reflects differential functions of tendon repair Most accurate for cross comparing studies

To calculate digital performanance
% of Nl PIP&DIP motion= (PIP+DIP flexion)-(extension lag) x100 175

Recently standardize outcomes as ass’t tools in repair result:
SF 36 Disability of arm,shoulder and hand questionair(DASH) Hand jebson-tayler test Purdue pegboard test

Partial Flexor Tendon Lacerations
If a tendon is lacerated 60% or more, treated the same as a complete transection. A core suture is placed in the tendon, and the surface of the tendon is sutured with a continuous 6-0 nylon suture. The flexor sheath is repaired when possible. Postoperative management same as for a complete transection, with immobilization, early controlled passive motion, and restoration of forceful activities at 10 to 12 weeks. If the laceration is less than 60%, . evaluated for the risk of triggering. .If triggering is seen, the flap of tendon is smoothly débrided, and the flexor sheath is repaired to help avoid entrapment or triggering of the flap in the defect in the flexor sheath. .Postoperatively, the part is protected with dorsal block splinting for 6 to 8 weeks, and more forceful activities are resumed gradually after approximately 8 weeks a reasonable clinical approach to managing partial tendon lacerations would be as follows.

Children Usually not able to reliably participate in rehabilitation programs No benefit to early mobilization in patients under 16 years Immobilization > 4 wks may lead to poorer outcomes

FDP Avulsions Commonly male athletes
Forced extension at DIP during maximal flexion (jersey finger) Often missed due to normal xray and intact flexion at MP and PIP Opportunity for FDP reinsertion lost if treatment delayed

FDP Avulsions Leddy and Packer Type 1: zig-zag exposure
Tendon delivered through pulley system with catheter passed retrograde Fixed to base of phalanx with monofilament suture through distal phalanx and nail plate and tied over button Fix within 7-10 days before tendon degeneration and myostatic shortening occurs Type 2: small bony fragment retracts to A3 level Can fix up to 6 wks post injury (less shortening) May convert to type 1 if tendon slips through A3 pulley and into palm Use same technique as for type 1 Type 3: large bony fragment retracts to A4 level Bony reduction and fixation of fragment

FDP Avulsions Type 1: zig-zag exposure
Tendon delivered through pulley system with catheter passed retrograde Fixed to base of phalanx with monofilament suture through distal phalanx and nail plate and tied over button Fix within 7-10 days before tendon degeneration and myostatic shortening occurs Type 1: zig-zag exposure Tendon delivered through pulley system with catheter passed retrograde Fixed to base of phalanx with monofilament suture through distal phalanx and nail plate and tied over button Fix within 7-10 days before tendon degeneration and myostatic shortening occurs Type 2: small bony fragment retracts to A3 level Can fix up to 6 wks post injury (less shortening) May convert to type 1 if tendon slips through A3 pulley and into palm Use same technique as for type 1 Type 3: large bony fragment retracts to A4 level Bony reduction and fixation of fragment

FDP Avulsions Type 2: small bony fragment retracts to A3 level
Can fix up to 6 wks post injury (less shortening) May convert to type 1 if tendon slips through A3 pulley and into palm Use same technique as for type 1 Type 1: zig-zag exposure Tendon delivered through pulley system with catheter passed retrograde Fixed to base of phalanx with monofilament suture through distal phalanx and nail plate and tied over button Fix within 7-10 days before tendon degeneration and myostatic shortening occurs Type 2: small bony fragment retracts to A3 level Can fix up to 6 wks post injury (less shortening) May convert to type 1 if tendon slips through A3 pulley and into palm Use same technique as for type 1 Type 3: large bony fragment retracts to A4 level Bony reduction and fixation of fragment

FDP Avulsions Type 3: large bony fragment retracts to A4 level
Bony reduction and fixation of fragment Type 1: zig-zag exposure Tendon delivered through pulley system with catheter passed retrograde Fixed to base of phalanx with monofilament suture through distal phalanx and nail plate and tied over button Fix within 7-10 days before tendon degeneration and myostatic shortening occurs Type 2: small bony fragment retracts to A3 level Can fix up to 6 wks post injury (less shortening) May convert to type 1 if tendon slips through A3 pulley and into palm Use same technique as for type 1 Type 3: large bony fragment retracts to A4 level Bony reduction and fixation of fragment

Reconstruction

Single Stage Tendon Grafting Zone 2
Indications Delayed treatment making end to end repair impossible Patient factors prevent repair Late referral, missed tendon laceration or avulsion Supple joints with adequate passive ROM

Technique 1 cm distal FDP stump left intact 1 cm of FDS insertion left intact (decreased adhesion formation vs granulating insertion site) Tenodesis of FDS tail to flexor sheath (10-20 deg of flexion) optional Hyperextension at PIP in absence of FDS tendon occurs occasionally

Technique Graft donors Palmaris longus Plantaris Long toe extensors (FDS) (EIP) (EDM)

Technique Graft passed through pulley system Atraumatic technique Distal fixation with tension set proximally or proximal fixation first Multiple methods for fixation of graft ends

Technique Distal juncture

Technique proximal juncture Pulvertaft weave creates a stronger repair vs end to end techniques, and allows for greater ease when setting tension

Setting tension GA With wrist neutral Fingers fall into semi flexed position (slightly less than ulnar neighbour), allowing estimation of tension Local anesthesia, active flexion Electrical stimulation Bunnel – “tendons shrink” Pulvertaft – “tendons stretch”

Secondary Reconstruction Zone 1
Zone 1 (functioning FDS) Eg. Late presentation of FDP avulsion DIP fusion Tendon graft Risks damaging FDS function through injury/adhesions in a very functional finger ? Young patients, supple joints, need for active DIP flexion

Secondary Reconstruction Zones 3, 4 and 5
Usually associated with 3 – 5 cm gap Interposition graft FDS to FDP transfer End to side profundus juncture

Two Stage Reconstruction
Primary grafting likely to give poor result, but salvage of functioning finger still desirable Sub-optimal conditions Extensive soft tissue scarring Crush injuries Associated fractures, nerve injuries Loss of significant portion of pulley system

Patient selection Motivated Absence of neurovascular injury Good passive joint motion Balance benefits of two additional procedures in an already traumatized digit with amputation/arthrodesis

Excision of tendon remnants Distal 1 cm of FDP left intact, remainder excised to lumbrical level FDS tail preserved for potential pulley reconstruction Incision proximal to wrist FDS removed/excised Hunter rod then placed through pulley system and fixed distally (suture or plate and screw – depending on implant)

Rod extends proximally to distal forearm in plane between FDS and FDP Test glide Reconstruct pulleys as needed if implant bowstrings

Postop Start passive motion at 7 days Continue x 3mos to allow pseodosheath to form around implant Before stage 2 joints should be supple, and wounds soft

Stage 2 – implant removal and tendon graft insertion Distal and proximal incisions opened Implant located proximally and motor selected (FDP middle/ring/small, FDP index) Graft harvested, sutured to proximal implant and delivered distally Fixed to distal phalanx with pull out wire over button

Stage 2 – implant removal and tendon graft insertion Proximally sutured to motor with pulvertaft weave FDS transfer from adjacent digit described Obviates need for graft Difficulty with length/tension Postop Early controlled motion x 3 wks, then slow progression to active motion

Pulley Reconstruction
Pulley loss Bowstringing = tendon taking shortest distance between remaining pulleys Biomechanical disadvantage Excursion translates into less joint motion Adhesions/rupture at remaining pulleys due to increased stress A2 and A4 needed (minimum) Most biomechanically important Some authors advocate reconstructing a 3 or 4 pulley system for optimal results

Most done in conjunction with a two stage tendon reconstruction Can be done with single stage tendon graft generally if extensive pulley reconstruction is required it is better to do a two stage procedure

Methods Superficialis tendon Insertion left intact Remnant sutured to original pulley rim, to periosteum, or to bone through drill holes Tendon graft Sutured as above Passed through hole drilled in phalanx (risk of fracture) Wrapped around phalanx (requires 6-8 cm of graft)

Methods Extensor retinaculum Excellent gliding surface Difficult to harvest the 8-6 cm required for fixation around phalanx Artificial materials Dacron, PTFE, nylon silicone Due to abundant atogenous material and disadvantages of artificial materials, this has not become common clinical practice May be stronger in long term vs autogenous

Tenolysis Release of nongliding adhesions for salvage in poorly functioning digits with previous tendon injury Avoid in marginal digits May not tolerate additional vascular/neurologic injury May need concomitant collateral ligament release, capsulotomy Prepare patient for possible staged reconstruction

Tenolysis Timing Anesthesia 3-6 mos. Post repair (minimum)
Plateau with physiotherapy Anesthesia Local with sedation Allows patient participation Tests adequacy of release Motivates patient

Tenolysis Technique Zig zag incisions
Adhesions divided maintaining non-limiting adhesions Pulleys reconstructed as needed If extensive or not possible convert to staged reconstruction Immediate motion postop.

References Indian J Orthop WJO|www.wjgnet.com
Hand Clin 21 (2005) 257–265 Hand Surgery, Vol. 6, No. 1 the American Society for Surgery of the Hand Flexor Tendon Injuries - Hand - Orthobullets.com

Flexor Tendon Injuries

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