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First MTP Fusion -Coughlin reamer preparation and Orthosolutions Cannulated 4mm screws

    Overview

    Learn the First MTP Fusion :Coughlin reamer preparation and Orthosolutions Cannulated 4mm screws surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the First MTP Fusion :Coughlin reamer preparation and Orthosolutions Cannulated 4mm screws surgical procedure.
    A 1st MTP (metatarsophalangeal ) joint fusion is a highly versatile operation both in terms of the conditions which can be treated as well as in terms of the function possible after successful fusion.
    A union rate of 90% plus is recorded in most series using current techniques. Success defined in terms of patient satisfaction rates though can be slightly lower than those of radiographic union of the fusion .
    The keys to operative success are careful joint preparation, positioning and appropriate fixation.
    Successful union of requires adequate preparation of the articular surfaces to expose subchondral bone, and rigid internal fixation. The technique described uses reciprocal dome shaped reamers to provide a congruent ‘ball and socket’ interface for fusion, this allows more versatility in aligning the toe optimally than flat cuts, provides a large surface area for fusion, and can be used to correct concomitant hallux interphalangeus.
    There are various ways of fixing the fusion, most commonly a single axial compressive screw combined with a dorsal neutralising or compression plate . The technique detailed in this operation is a “crossed-screws” technique which differs only in the final mode of fixation.
    Author : Mr Nick Cullen FRCS (Tr & Orth)
    Institution :The Royal National Orthopaedic Hospital ,Stanmore ,UK.
    Clinicians should seek clarification on whether any implant demonstrated is licensed for use in their own country.
    In the USA contact: fda.gov
    In the UK contact: gov.uk
    In the EU contact: ema.europa.e

    Indications

    INDICATIONS :
    -For end stage and symptomatic degenerative First MTP(Metatarsophalangeal ) arthritis (whatever the cause)
    -As a salvage operation after failed first MTP joint debridement with severe pain
    -As a salvage operation after failed first MTP joint replacement ( usually using a bone block technique)
    -For salvage after recurrent Hallux Valgus ( consider also a Lapidus operation ) or to treat Hallux Varus
    -As a primary corrective operation in severe Hallux Valgus deformity
    -As a primary corrective operation for Hallux Valgus in the neurological patient
    -As a two stage procedure for an infected joint replacement or an infected MTP non-union.
    SYMPTOMS & ASSESSMENT:
    Patients who will be much improved by an MTP fusion will in most cases have severe pain , well localised to the level of the Metatarso-phalangeal (MTP) joint , and advanced arthritic change or joint destruction. Pain is often improved to an extent when in appropriately supportive shoes.
    Pain is likely to be restricting the patients function significantly from their pre-arthritic state, whatever this was. There are no absolutes in determining which patients may benefit from a lesser operation (such as an MTP joint debridement) . Symptomatically though persistent pain at rest and in bed are often indicators of an advanced arthritis likely to need fusion.
    On examination joint movement will be very limited and likely to be painful through the range of movement in severe arthritis. In more moderate disease pain occurs at the end of range mainly. I would however rate the reduction in range of movement as being a less important consideration than the level of pain being experienced in deceiding whether a fusion is an appropriate intervention. The rank of importance in considering whether to fuse or not is foremost the level of pain , next the level of radio-graphic arthritic change and least important in fact the reduction in range of movement. Different surgeons opinions on this weighting may vary.
    Prominent osteophytes around the joint , producing additional pain from impingement when in shoes are common, and will be debrided at the time of a fusion . When examining the first ray it is important to examine also the inter-phalangeal joint of the hallux, which will be called into play more following fusion. If it hyper-extends significantly pre-operatively then in a female (or broad-minded male) the wearing of high heels will not be a problem.
    If there is symptomatic degenerative change at the inter-phalangeal joint too then consider intercurrent joint debridement here or possibly an MTP joint replacement. This is not a common occurrence fortunately.
    Be aware of a sub-group of patients with advanced MTP arthritis and significant hypertrophic bony exostoses around the joint who have very minimal pain. They present with dorsal impingement and severe arthritis but minimal or no arthritic pain. These simply require debridement of the dorsal exostoses and rarely require fusion.
    Patients who are keen to return to sporting activity , including running , should have no real concerns following big toe fusion. Following an ankle fusion subtalar and possibly midfoot arthritis will in the majority of patients ensue. There is no clear correlation with what occurs in the first ray after MTP fusion. In other words the remaining inter-phalangeal joint of the Hallux is only exceptionally effected after the fusion.
    The classification system of Coughlin is probably the most adopted for grading Hallux Rigidus and is worthy of fuller review (see results section). It combines an assessment of range of movement , plain X-ray features , the nature and frequency of pain as well as when during the range of joint movement pain occurs. In this it certainly identifies the aspects of an arthritic joint can that can be measured but lacks a weighting to the relative importance of these features in determining appropriate treatment.
    INVESTIGATIONS:
    In most patients with arthritic change an AP and Lateral weight-bearing X-Ray will suffice.
    X-Rays are in not especially prognostic and if the diagnosis is clear clinically and non-operative treatment being pursued then are not absolutely required.
    In patients being considered for an MTP joint debridement then an MRI gives a more objective assessment of the joint and also has the advantage of visualising the sesamoids well. It should be borne in mind however that more minor degrees of arthritic change may well not be identified even by MRI.
    NON-OPERATIVE ALTERNATIVES:
    Activity modification and regular non-steroidal medication are likely to have been tried already by the patient.
    Injections of steroid and local anaesthetic will usually provide only short term relief in advanced cases of MTP arthritis . They have a role in calming acute flare-ups.
    Of most help for weight-bearing symptoms is the choice of appropriate shoe-wear. A stiff soled and “rocker-profile” sole should be advised. This may be a particular make such as an MBT or Fit-Flop shoe or simply a more traditional leather soled brogue with an appropriate sole.
    SURGICAL ALTERNATIVES:
    –First MTP debridement: See relevant Atlas section
    -First MTP debridement and Moberg procedure: See relevant Atlas section
    -First MTP replacement (full joint replacements and replacements of only one side of the joint both exist); See relevant Atlas section
    –Kellers excision arthroplasty: See relevant Atlas section
    -First metatarsal osteotomy: (Watermann , shortening Scarf and Youngswick are three examples of such realignment /joint space “creating” procedures ): See relevant Atlas section.
    CONTRAINDICATIONS:
    Patients who are unlikely to co-operate with post-operative instructions. Examples would include patients with impaired mental faculties or any smokers who realistically will not abstain during the period required for bony union.
    Patients with poor vascular supply to the foot or factors leading to impaired soft tissue or bone healing need these factors to be optimised pre-operatively.

    Setup

    General or Regional anaesthetic.
    Antibiotics & LMW Heparin on induction.
    Laminar flow theatre.
    Thigh tourniquet (ankle tourniquet gets in the way of positioning the wire driver and drill during fixation).
    Patient supine.
    Intra-operative nerve block (ankle) for analgesia

    Operation – 1

    Patient is positioned supine on the table.
    The skin is prepped up to the knee with Alcoholic preparation solution.
    A small bolster can be placed under the ipsilateral hip so that the foot sits in 10o of external rotation from the vertical.
    A thigh or ankle tourniquet can be used.
    The incision is marked, a longitudinal approach in the mid-line of the 1st MTP joint from the medial border of the 1st metatarsal to the IP joint of the proximal phalanx.

    An incision is made with a size 10 blade through the skin and subcutaneous tissue. Care should be taken not to incise into the capsule at this stage.
    Once down on to the capsule the subcutaneous tissue is gently elevated with sharp dissection off the capsule.
    The dorsomedial cutaneous nerve is contained within the cutaneous tissue dorsally and this is identified and carefully protected in the dorsal flap. The subcutaneous tissue is cleared from a short distance of the plantar aspect at the capsule leaving enough of the plantar and dorsal limb for suture without injuring the nerves on closure.

    The medial capsule is incised down to bone, the capsule is then carefully dissected off the 1st metatarsal and extended on to the proximal phalanx. The periosteum and joint capsule should be elevated in one layer.
    It is important that dissection proceeds immediately adjacent to the bone avoid facing the scalpel blade in to the soft tissue, this will ensure that full thickness flaps of capsule are elevated and will avoid damage to the medial cutaneous nerves.

    Developing a small pocket of space adjacent to the bone over the dorsal aspect of the 1st metatarsal and the dorsal aspect of the proximal phalanx will allow passage of a mini Homan’s over the top of the bone. This will assist with retraction, which is very helpful when dissecting the soft tissue from the dorsal MTP joint to provide good exposure.

    The capsule is carefully elevated off the dorsum of the joint and the dissection is progressed round to the lateral side of the MTP joint, the proximal phalanx and the 1st metatarsal.

    Attention is turned to the plantar capsule and again in one full thickness flap this is elevated off the both the proximal phalanx and the 1st metatarsal to expose the plantar aspect of the 1st metatarsal. Plantar plate will need to be released off the plantar aspect of the proximal phalanx however the flexor hallucis brevis should be left intact where possible.

    The plantar vessels are indicated here with the forceps, whilst the metatarsal head does have an interosseous blood supply(which is interrupted in a distal metatarsal osteotomy) it is helpful to preserve these to maintain as rich a blood supply to the metatarsal head as possible.

    Using Rongeurs the dorsal, medial and lateral osteophytes are cleared to expose underlying subchondral bone, and leaving the native but degenerate metatarsal head.

    The hallux is plantarflexed to begin to expose the 1st metatarsal head. It is important to be able to access the plantar aspect of the metatarsal head, if this is not possible, then further release of the lateral and medial collateral ligaments, can improve the view, and release of the sesamoids with a periosteal elevator or McGlamry elevator may also assist the exposure.

    Once the 1st metatarsal head is sufficiently exposed a guide wire can be passed in to the central aspect of the 1st metatarsal head, this should be introduced in the mid-line along the shaft. It is helpful to observe the 1st metatarsal both medially and dorsally to ensure that the wire is aligned centrally through the metatarsal in all planes.

    The wire is then driven down seated far enough down the shaft so that it doesn’t toggle when the reamer is engaged over it.


    The appropriate size should be selected and the reamer should be the same size or slightly larger than the 1st metatarsal head, a smaller Coughlin reamer is likely to take away too much bone dorsally and plantarly. Once the correct size is chosen this should be mounted on a cannulated power hand drill



    Taking care to plantarflex the proximal phalanx sufficiently it is very important to ensure that the Coughlin reamer does not engage or gouge the proximal phalanx. The Coughlin reamer is used with short bursts and an assistant should carefully irrigate with normal saline to prevent overheating and thermal damage to the subchondral bone.

    The Coughlin reamer is engaged and slowly takes away bone from the subchondral bone and cartilage, the depth of resection should be carefully inspected after each burst to avoid over-resection.

    After reaming the metatarsal head the bone of the metatarsal head often looks smooth and polished this may be mistaken for residual subchondral bone. Inspecting this layer closely however it has yellow softer consistency of cancellous bone.

    Once the Coughlin reamer has been removed the majority of the cartilage and subchondral bone has been removed it is usually necessary to clear the marginal remnants using a Rongeur.

    The 1st metatarsal head has now been cleared of all cartilage and subchondral bone, it should appear as a well-rounded dome. Using a K-wire the cancellous bone is penetrated around its surface producing a pepper pot appearance and the drill holes can be carefully joined up by using a mini Lambotte osteotome or a pair of sharp bone cutters.

    Moving the attention to the proximal phalanx, the surface will need to be anteriorly translated from the distal aspect of the 1st metatarsal head to provide adequate exposure for reaming. Often careful dissection of the plantar aspect of the 1st metatarsal head subperiosteal release of the plantar plate will assist, leaving the FHB attachment intact.

    The proximal phalanx should be appropriately exposed so that the metatarsal head is not damaged when this is reamed with the Coughlin reamer.

    The proximal phalanx has been adequately dissected and now is brought out distally to the 1st metatarsal ready for guide wire placement.
    The proximal phalanx should be appropriately exposed so that the metatarsal head is not damaged when this is reamed with the Coughlin reamer.



    It is helpful at this stage using a Rongeur to slowly scour the cartilage on the proximal phalanx, which aids engagement of the blades of the Coughlin reamer and avoids the reamer sliding off the smooth cartilage.

    Consideration should now be made to the placement of the guidewire for reaming the proximal phalanx. In this case we can see that there is a degree of interphalangeus. Fusing the 1st MTP joint in the anatomical position is likely to leave residual hallux interphalangeus.
    If the alignment of the guidewire is offset, it is possible to correct the interphalangeus through the MTP joint by eccentrically reaming the proximal phalanx.

    The optimal alignment of the guidewire is best assessed by drawing a line parallel to the proximal toenail.
    By passing the guidewire through the proximal phalanx perpendicular to the drawn line, it will allow reaming to occur in the plane of the toe.

    Once the alignment has been assessed the wire is passed in the appropriate vector towards the mid-line of the hallux. With a large hallux interphalangeus angle, the entry point may be slightly more medially than central. Whereas, in a straight well aligned hallux, the entry point will be central within the 1st metatarsal head.


    Once the alignment has been assessed the wire is passed in the appropriate vector towards the mid-line of the hallux. and the position once again checked.
    Care should be made not to penetrate the interphalangeal joint with the wire.

    Once the K-wire is satisfactorily seated the articular surface of the proximal phalanx of the hallux is presented in to the surgical field with the assistant plantarflexing the hallux maximally, and using the mini Homan’s to lever the proximal plantar aspect of the proximal phalanx forward so that it clears the 1st metatarsal head; this is done in order to avoid damage to the metatarsal head during the reaming.

    Operation – 2

    The Coughlin reamer is passed down the guidewire through the central aperture. Care is taken to ensure that the Coughlin reamer is not engaged until closely engaged to the proximal phalanx and the metatarsal head is clear of the margins of the reamer.
    The reamer is then engaged in short bursts. It is helpful for the assistant to either slow irrigation of saline to avoid thermal damage to the reamed bone surfaces.

    Proceed with the reaming until the yellowish subchondral bone is exposed over the majority of the phalangeal head.
    The Coughlin reamer does produce a slight polishing effect and the bone appears slightly smoother than cancellous bone and this should not be mistaken for residual subcortical bone.

    The articular surface has been removed.
    There is usually a margin of articular surface around the rim that needs to be cleared using a rongeur.

    Once adequate cartilage and subchondral bone has been removed the central guidewire is removed using a wire driver and multiple drill holes are passed evenly across the surface of the proximal phalanx with a pepper potting fashion. Again the assistant irrigates the wire slowly with cold saline to ensure that there is no thermal necrosis of the bone.

    The proximal phalanx should be left with a widely distributed set of punch holes across the whole facet pentrating the subchondral plate.

    The individual drill holes are then connected either using a mini Lambotte osteotome or a sharp bone cutter to increase the surface area of exposed cancellous bone in order to aid union.

    A tray lid or flat surface should always be left sterile on the scrub trolley and this is used to gauge the position of the foot, which is placed flat on the surface, with the ankle dorsiflexed.
    The MTP joint is positioned here showing that the pulp of the toe just accommodates a finger underneath it, ensuring there is enough elevation from the floor during the terminal phase of gait. The assistant should hold the MTP joint still.

    Holding the MTP joint in the same position, the proximal phalanx should then be tested to ensure that it engages the tray lid in flexion. Dorsiflexing the toe too much will lead to overload of the plantar aspect of the 1st metatarsal head and pressure from shoes on the dorsal hallux, leaving it too plantarflexed will lead to an overload of the plantar aspect of the hallux.
    Time should be taken to check and re-check the ideal position. Once an adequate position is achieved it is important that assistant hold the toe firmly in this position avoiding further movement.

    The mid-line of the metatarsal and proximal phalanx have been marked here which will help demonstrate the placement of guidewires and hence the screws.

    The first guidewire is passed dorsal to the dorsal half of the 1st metatarsal above our previously marked line and is aimed towards the dorsal half of the phalanx to exit the proximal phalanx, at the metaphyseal diaphyseal junction. Inserting the wire in a controlled manner, with a gentle pistoning action of the the drill, allows tactile feedback from the distal cortical surface. Advancement should stop once this is penetrated.

    Next the distal to proximal wire is inserted and this is passed from the diaphyseal metaphyseal junction of the toe, along plantar half of the bone and is aimed towards the plantar half of the 1st metatarsal to exit again at the diaphyseal metaphyseal junction of the 1st metatarsal head.
    Again passing the wire on a high speed drill in a controlled fashion using a slow pistoning technique with the drill as it gives an indication of when the far cortex is penetrated.
    By keeping the proximal to distal wire dorsal and the distal to proximal wire plantar then contact between the cross screws is avoided and hence the need to repositioning.

    The distal and proximal wires are- demonstrated here. The proximal to distal wire is sitting in the dorsal half of the bone and the distal to proximal in the plantar half of the bone which avoids contact between the cross cannulated screws and the need for replacement.

    The position of the toe is then re-checked in the temporary fixed position with the K-wire to ensure that realignment continues to be optimal. It is important to provide a good countersink for both of the screws in order to allow seating of the screw. Without doing this , due to the obliquity of the guide-wires, the screw head tends to impinge on the cortical surface of the metatarsal producing a sheer force that will fracture the medial cortex of the metatarsal.

    Here an Orthosolutions countersink is passed over the wire.


    The countersink is rotated to clear a volume of cortical bone in the direct line of the screw tract, deeply enough to accommodate the screw head.

    A depth guage is passed in to the countersunk hole and the depth of the screw read from here. An appropriately sized 4mm cannulated screw is selected.

    The wire is then over drilled with 2.7 cannulated drill. The drill should penetrate both the proximal and the distal cortices. Frequently the wire becomes incarcerated within the drill and it is important for the assistant to continue to hold the toe in the reduced position, it is advisable to have a spare guidewire at hand to pass down the drill hole whilst the incarcerated wire is removed from the drill.

    The appropriately sized cannulated screw is passed on to the guidewire and inserted with a screwdriver with the assistant holding the 1st MTP joint reduced.

    The screw is passed until it engages just gently and should not be snugged home all the way at this stage. The image here shows that the screw has a small way to go before full engagement. This will allow some leeway in fine tuning both compression and toe alignment.

    The same process is undertaken on the distal phalanx.
    A countersink is used to clear room for the head of the cannulated screw. Both cortices are drilled. The size of the screw is measured. The appropriate screw is introduced over the guidewire and carefully tightened. Once the screw is just engaging (not firmly seated) the surgeon can assess the position of the toe.
    Tightening the distal screw first will achieve a small amount of adduction as it compresses the medial aspect of the joint and can be used to fine tune any residual interphalangeus.
    If the proximal screw is tightened first, this will cause a compression of the lateral articular surface and reduce any residual varus. The two screws should be snugged down one after the other until tight.

    Tightening the distal screw first will achieve a small amount of adduction as it compresses the medial aspect of the joint and can be used to fine tune any residual interphalangeus.
    If the proximal screw is tightened first, this will cause a compression of the lateral articular surface and reduce any residual varus. The two screws should be snugged down one after the other until tight.

    The screws are firmly introduced and are flush with the cortical surface with a good engagement of the far cortex and the joint at this stage can be seen to be nicely compressed.

    The position of the hallux is checked again using a false floor to ensure that there is adequate clearance of the distal phalanx at the hallux and that the toe engages in the ground and also that the varus valgus alignment is satisfactory.

    A stress test of the MTP joint is helpful to ensure that adequate fixation is achieved but if there is still give in this joint then the fixation is inadequate and one could consider a staple or plate to augment the fixation.

    The wound is thoroughly irrigated with saline to free any bony fragments within the soft tissues or drilled debris.

    Operation – 3

    The capsule is closed with 2.0 Vicryl. Care should be taken to avoid entrapping the medial cutaneous nerves which have been identified and protected previously

    Subcuticular closure of the skin.

    Skin glue to seal the wound.

    Dry dressings are applied to the foot. It is important to apply these once the skin glue is dry and avoid the gauze being too tight which may produce pressure areas over the toe will affect the digital blood supply.

    Finally a band of dressings is applied with wool and crepe.

    Post Operative

    Day-case or overnight stay
    An on-table or immediate post-operative X-Ray is always required.
    Prophylactic LMW Heparin for 2 weeks.
    Weight bear using post operative shoe for 5-6 weeks.
    Crutches likely required 1-2 weeks.
    Change dressings at 1 and 2 weeks and use a heavy , padded forefoot dressing /Kellers bandage for this duration. From 2 weeks just local dressings to the wound which should be continued 24/7 until wound completely dry and healed. After this continue dressings whenever in shoe wear for a further month.
    If the wound is slow to heal (or breaks down) swab for microbiology , ensure patient is non-smoking and also complying with post-operative advice, and continue with regular (daily or more frequently as required) dressing changes.
    From 3 weeks the patients should cleanse the foot twice a day, once in a salt water bath and once by bathing/showering.
    Check X-Ray is required at 5 -6 weeks to confirm bony union and also a clinical review is required.
    If at all equivocal (due to ongoing pain or inconclusive X-ray) then re X-ray in a further 3-4 weeks (or consider CT scan for a more objective view) and limit activity according to symptoms until then. If in pain from the 1st MTP also consider using a post-operative boot instead of the standard post operative shoe. The patient should aim for pain-free function and strictly limit activity and weight-bearing to achieve this.
    Appropriate shoe-wear fit is vital in the first month or so after the post-op shoe.
    I advise fit-flops ,Ugg boots, wider fits or open stiff soled sandals. Stiff low heels ( platform or wedge shoes ) are encouraged in women , from when comfortable. A similar rocker-profile and stiff soled shoe will help in men also for this period.
    Patients may use a static bike & swim from 5-6 weeks , Cross-train from 6-7 weeks and re-start light jogging on treadmill from 10 weeks at soonest under normal circumstances.

    Recommended Reading

    Manipulation and injection for hallux rigidus.
    J Bone Joint Surg.2001.83-B:706-708
    M.C.Solan , J.D.F.Calder ,S.P.Bendall
    Injection & MUA demonstrated to be of use for grade 1 & 2 Osteoarthritis.
    Mean follow up of 41 months
    In patients with Grade 1 X-Ray changes relief for 6 months median was achieved with the intervention.
    Arthrodesis of the first MTP joint using a dorsal titanium contoured plate.
    Foot & Ankle International.2004.25(11):783-787.
    R.Flavin, M.M.Stephens.
    12 patients , all united radiographically by 6 weeks using a purpose designed dorsal plate.
    Non-union after arthrodesis of the first Metatarsal-phalangeal joint:A systematic review
    J Foot Ankle Surg. 2011; 50(6): 710-13.
    T S Roukis
    37 papers reviewed , which included as a minimum 12 months follow up , at least 30 patients and modern internal fixation techniques. This resulted in 2,818 cases being considered. Almost 50% of cases were for Hallux Valgus , just over 30% for Hallux rigidus and approximately 10% both for Rheumatoid Forefoot and as a revision procedure. Non-union overall was at 5.4% with one third only of those being symptomatic.
    Hallux Metatarsophalangeal joint arthrodesis with a hybrid locking plate and a plantar neutralisation screw:A prospective study.
    Foot Ankle Int 2013 34(11): 1535-40
    J Doty, M Coughlin , C Hirose, T Kemp.
    49 feet post-operatively were followed up for a minimum of 12 months.
    Visual analogue score for pain reduced from a mean of almost 7 to less than 2. Over 50% had an improvement in gait , over 40% no change and fewer than 5% were worse. Non and delayed union or 4%.
    Almost 90% of patients rated the outcome as excellent or good.
    Hallux rigidus. Grading and long term results of operative treatment
    J Bone Joint Surg 2003.85-A(11): 2072-88
    Coughlin MJ, Shurnas PS
    Outcome of fusion and debridement surgery reported as well as a classification system which has been fairly widely adopted since. The grading runs from 0 to 4 and is based on clinical and radiographic features as well as range of dorsiflexion at the MTP joint (versus the normal side or in absolute terms).

    Reference

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