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First MTP replacement- Cartiva implant(Wright Medical)

    Overview

    Learn the First MTP replacement: Cartiva implant(Wright Medical) 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 replacement: Cartiva implant(Wright Medical) surgical procedure.
    The Cartiva implant is a hydrogel polymer implant designed for use in 1st metatarsophalangeal arthritis (hallux rigidus). The material has a similar coefficient of friction and hydration characteristics to hyaline cartilage and is intact the same material widely used in contact lenses.
    The procedure is simple to undertake and has an excellent scientific and level 1 clinical evidence background. Cartiva has been extensively studied in a prospective randomised controlled trial against 1st MTPJ fusion as part of the 12 centre MOTION study group. This study has demonstrated that it is at least as good as a fusion at 2 and at 5 years in terms of pain relief and improvement in function both in activities of daily life and in sport.
    A comprehensive literature review which includes award winning peer reviewed papers and presentations at mutilple international meetings is included in this operation (See references). The Cartiva MOTION study is the largest and most comprehensive PRCT in forefoot surgery that has been undertaken yet.

    Indications

    INDICATIONS
    The Cartiva implant is indicated in cases of Hallux rigidis of Coughlin Grade 2,3 or 4. The principle guide to this implant is a clinical situation with a middle aged patient with a painful grind test whereas those patients where there is pain only at the extremes of movement may benefit from a Cheilectomy alone, especially if it is the dorsal swelling rather than motion which is the source of pain.
    A careful history must be taken focussing especially on risks of osteoporosis. Previous fragility fractures, early menopause or medical evidence of low bone mineral density are relative contraindications due to the higher risk of implant subsidence.
    SYMPTOMS & EXAMINATION
    Appropriate patients complain of activity related pain often associated with swelling. Patients in the authors opinion do better when they have a useful pre-operative range of motion as this motion along with pain relief is the goal. Evidence is that the outcomes are not affected by age, gender, BMI, severity of arthritis or duration of symptoms.
    IMAGING
    Standing plain radiographs are required. These will demonstrate osteoarthritis and the radiographs and clinical findings can be used to grade the arthritis according to the scale of Coughlin (ref). Care must be taken to inspect the radiographs for evidence of metatarsal head cysts which may preclude the Cartiva implant as they may not allow adequate bone support. More complex imaging by way of CT or MRI scans are indicated if there is concern about bone support.
    ALTERNATIVE OPERATIVE TREATMENT
    The alternatives to Cartiva include Cheilectomy for those cases where there is end of range or impingement pain only and the grind test is negative. If there is a positive grind test then the options are to arthrodese the joint with screws or a plate with the subsequent sacrifice of movement or a joint replacement. There are many reports of semi or total joint replacement. Most have failed over time and failed to give the long term benefits that are needed. A more desirable approach is to use an implant which removes less bone and thus ‘burns no bridges’ if and when it fails by making a subsequent revision to arthrodesis straightforward (Glazebrook M, Baumhauer J, Davies MB. Revision of Implant to Great Toe Fusion: Did We “Burn a Bridge” With a Synthetic Implant Hemiarthroplasty? Foot & Ankle Orthopaedics. 2017 Sep 11;2(3))
    NON-OPERATIVE MANAGEMENT
    The painful and stiff great toe metarsophalangeal joint can be treated by activity modification and the use of oral or sometimes topical analgesics. Avoiding provocative activities such as running or dancing can allow the pain to be manageable for some. Footwear selection to accommodate for a swollen or enlarged joint secondary to dorsal osteophyte formation is helpful especially when it is the dorsal cheilus which is the source of pain. Footwear which has a rigid sole will limit motion at the first MTPJ and this simple measure can help minimise pain in those with a painful arc of motion (a positive grind test). Using shoes which don’t place the joint in a dorsiflexed attitude also reduces impingement type pain and so often patients are advised to avoid high heeled foot wear and this advice is sometimes met with dismay and so patients will seek treatment modalities which reduce pain but preserve motion, the goal of the Cartiva.
    CONTRAINDICATIONS
    Cartiva is contraindicated in the presence of infection or a history of 1st MTPJ sepsis in the past. Care must be taken if plain radiographs show significant cysts or inadequate bone stock. A full menstrual history should be taken to be aware of osteoporosis. I use CT scanning to determine the exact position of cysts if these are a concern. If in doubt I feel it is best to avoid caressive and aim towards a fusion. CT scans are also the best way to check for sesamoidal arthritis if there is predominently pain on the plantar side of the joint. If there is established sesamoid-metatarsal arthritis then Cartiva is best avoided. Gout is considered a relative contraindication also as is hallux values due to difficulty with correct orientation and subsequent loading of the implant.

    Setup

    Patient is positioned supine often with a sandbag to allow easy access to the dorsum of the fist ray. Antibiotics are given on induction of anaesthetic. The procedure is carried out under foot and ankle regional anaesthetic, spinal/ epidural or general anaesthetic. An appropriate level tourniquet is applied. Image intensification is not needed but I find it useful to have the plain standing images displayed during the operation.

    Both 8mm and 10mm Cartiva sets and implants should be always available at the outset. I use a Mercian small instrument foot tray for soft tissue dissection and subsequent repair. In addition to this other equipment required is a power tool with a wire driver capable of holding a 2mm wire and with a chuck and key. Saline and a 20mm syringe for lavage is also needed.

    Operation – 1

    The initial incision I prefer is a direct straight dorsal one. The implant can be put in through a true medial approach and others who also do fusions through this approach use this. Old incisions for example if the patient has had a previous open cheilectomy amy be used providing a good clear view of the whole dorsal metatarsal head is achieved.

    I make my deeper incision to the capsule and paratenon in one cut parallel and medial to the Extensor Hallucis Longus (EHL) tendon leaving enough of a cuff medial to the tendon to allow the castle to be repaired without picking up the tendon in the suture line at the end.

    Often loose osteophytes from either the phalanx or metatarsal head are encountered and are carefully excised (1). At this stage no cheilectomy is made unless it is essential to actually gain access to the joint space. A self retaining soft tissue retractor, must be placed deep such that the capsule is retracted and not the skin edges which are vulnerable especially when subsequently the joint is dislocated.

    Further deep dissection around the metatarsal head releases the medial and lateral collateral ligaments to allow the phalanx to be plantar flexed completely thus exposing the circumference of the metatarsal head articular surface.

    Plantar flexing the phalanx completely is required to expose the circumference of the metatarsal head articular surface.This is vital to allow correct positioning of the Cartiva and to ensure that an adequate rim of been exists around the implant. In this case there is a small area of residual cartilage on the plantar 1/4 of the head (1). Any loose flaps of cartilage are removed with a small sharp curette.
    At this stage an assessment is made of the metatarsal head size to select either an 8mm or 10mm implant. Generally a 10mm implant fits well, but for small adults or those where a cheilectomy has rendered the head narrow in sagittal depth an 8mm implant is used.

    Either the 8mm or 10mm Cartiva set is opened. This contains only four instruments which are size specific and come in a sterile set. The Placer (8 or 10mm) is a cannulated guide with a flat end on one side and a concave end on the other.
    The Introducer (8 or 10mm) is a hollow tube of narrowing internal diameter with a stepped end allowing it to be held with good visibility to the cavity reamed.
    The Metatarsal Drill Bit (8 or 10mm) has a flange to prevent over reaming.
    The final instrument on the set is a single use 2mm long non threaded guide wire.

    With an assistant keeping the toe plantar flexed all the way through, the Placer and Guide wire from the Cartiva set are now used.
    The guide wire needs to be ‘held long’ in the wire driver adapter of the power tool so that it will protrude at least 3 cms from the Introducer.
    Ensure that the concave end of the Introducer is offered up to the metatarsal head.

    The Placer is positioned such that it is central in the metatarsal head and aligned with the long axis of the shaft of this bone in the sagittal and transverse planes.
    It should be aligned perpendicular therefore to the coronal plane. The edges of the Introducer are inspected to make sure that the curved surface covers the metatarsal surface thereby making sure the implant isn’t seated at a “tilt”.
    Some prefer to position the implant more dorsal or aim to position it at the point of maximal chondral loss but I feel it is mechanically best to be at the centre of rotation so that the implant interposes throughout the excursion of the joint.

    In essence then aiming to position the guide wire central to the head and shaft in all planes with good coverage of the placer. A further check can be made that at least 2mm of bone exists all around the periphery of the Placer, to subsequently support the Cartiva implant.

    Position of the wire is carefully maintained as it is inserted under power.

    The guide wire is drilled in ensuring it is at least 3cms into the head so that it is stable and supports the reamer well. A further inspection to check alignment is well worth it at this stage as the wire can still easily be repositioned now. I don’t use an image intensifier for this as I prefer to see the head and joint clearly with an adequate exposure, however a mini C-arm could be used for those that wish it.

    The Metatarsal Drill is now used – I set the power tool to ream rather than drill if this setting is available as I do not wish to overheat the bone. Irrigation with cool saline is provided by my assistant both to keep from thermal damage but also so that I can clearly see who deep my drill is going.

    I stop reaming just before the metal stop flange hits the metatarsal head (by approximately 1mm) or the implant will be seated too deep in my opinion. Originally the implant was designed to protrude 1 to 1.5mm from the surface but most in the original MOTION study group (of which I am one) prefer to have the implant at least 2mm proud and so stop reaming before the flange hits the surface.

    The Cartiva implant comes in a sterile pack bathed in saline. It has a flat and a curved surface and it is the same diameter as it is in length. The flat surface will lie deep on the base of the bone well and the curved surface makes the articular surface. The introducer is 0.5mm smaller in diameter than the implant and this squeezes saline from the implant at introduction thus making it a stable expansion fit in the bone well.

    After washing away any further bone debris, the residual ‘well’ is carefully inspected for any voids or bone cysts in the base or sides. Occasionally an unexpected cyst can be found – none were in this case. When found, I carefully curette the cyst out and pack it fully with the reamings from the drill. The Cartiva Placer instrument makes for a perfect fitting tamp for this purpose in the base or sides.
    A further check can be made that at least 2mm of bone exists all around the periphery of the bone well to subsequently support the Cartiva implant.

    In this instance of a Cartiva implant put in elsewhere, the function and pain relief were poor and a subsequent MRI showed the implant to be inadequately supported with bone dorsally. This is to be avoided by careful positioning of the placer, guide wire and subsequent reaming.

    The Introducer is wetted with saline to allow the Cartiva implant to glide. The Cartiva is firmly held as it is easy for it to ‘pop’ across the operating theatre in my experience! It is put into the non tapered end of the tube with the curved surface uppermost. This is the end that will provide for the articular surface.

    The flat end of the Placer is used to push the Cartiva down the tapered inner Introducer tube. This squeezes the implant tight and so care must be made to have the Introducer well supported on the table whilst pushing down. Never push it in without the end supported or again it will ‘pop’ out onto the OR floor! Push until firm resistance of the implant at the end of the Introducer against the table is felt.

    The implant can be seen to lie right at the end of the tube ready for insertion. If it is not at the end re-push with the Placer again putting the end on the firm surface of the table.

    The Introducer is placed with the recessed end on the bone well. It does not fit inside the well aperture and forcing it to do so will break the margin of the bone potentially rendering the implant unstable after introduction. The Placer again is used to drive the implant into the bone well. A firm end point will be felt and the Introducer will slip off the implant.

    The Cartiva is now seen to be well seated and with 2mm of protrusion. Up to 3mm of protrusion in the authors opinion is acceptable but I am concerned that beyond this further protrusion may render the implant unstable. If this happens I take the implant out, re-ream further after putting the guide wire back in by hand and selecting a new implant to put in.

    A check is made that the interposition of the implant is effective at keeping the articular surfaces separate from one another and that there is no block to adequate glide.
    Occasionally (rarely) a sesamoid release is required. I carry this out with a freer elevator slid into the metatarso-sesamoidal articulation.

    Consideration can now be made for a Cheilectomy. I inspect the joint in maximum dorsiflexion and if there is impinging bone this can now be safely removed, whilst still respecting the rule of a minimum of 2mm of bone rim support for the implant. Bone can obviously be safely removed if impinging from the phalanx.
    The cheilectomy if required is either done with Rongeurs or with very careful use of a saw. Be careful not to catch any part of the implant with the saw and once again to respect the rule of a minimum of 2mm of bone rim support for the implant.
    I aim to achieve at least 70degrees of dorsiflexion in the expectation that some is inevitably lost in the post-op period. The greater range that can be achieved on table then the better providing of course that the joint remains stable.
    Also it can be worth inspecting the distal poles of the sesamoids themselves as sometimes impinging osteophytes are seen here and can be removed with fine rongeurs – there were none in this case.

    At least 70 degrees of dorsiflexion is my aim and without bony impingement.

    The wound is finally lavaged with saline. The capsule is repaired without tension, with interrupted 2/0 Vicryl sutures being careful not to pick up the EHL tendon in the repair. If there has been an extensive cheilectomy sometimes the capsule repair appears “baggy” as it has been stretched with the cheilus. I do not remove ‘redundant’ capsule as this bagginess will aid free movement of the joint after repair.

    Operation – 2

    Skin repair is at the surgeon’s discretion but I prefer to use interrupted Monocryl sutures so that no further suture removal is required whilst any seepage does not cause a wound haematoma. The sutures have ‘dropped off’ by 4-6 weeks.

    The wound is dressed with a Post-op Opsite wound care dressing and then covered with orthopaedic gauze, cotton wool roll and crepe. This bulky dressing is removed by the patient at 5 days, post-op, leaving the adhesive dressing in place, and allowing them to start to get the joint moving more freely from that point.

    Post Operative

    Cartiva is a day case procedure. The patient is instructed to mobilise fully weight bearing on the first day with a dressing show to accommodate the bulky dressing. I advice the patient to keep the limb elevated to horizontal for 50 minutes in each hour for the first three days. They may then start to allow dependence of the limb but to elevate if they feel it is swollen or painful.
    The bulky dressing is reduced to the adhesive dressing only by the patient or carer at day 5 and they patient is then instructed to put the joint through a range of motion as full as they are able without pain both passively and actively.
    From day 5 patients are allowed to wear a trainer shoe or slipper to allow them to be more mobile but again to elevate if they feel the foot is swollen or painful.
    I do not carry out routine post-operative images as the implant cannot be seen. The ‘well’ can be defined and can be seen to mature on images after 3 or so months but in my experience plain radiographs add little or nothing to my management. If there are concerns about ongoing pain or poor function beyond 6 months the MRI scanning (or in skilled and experienced hands) Ultrasound scanning can determine the imply position – see slide 13.

    Medical review at two weeks allows them to have the wound inspected and then to commence physiotherapy increasing their walking and range of motion exercises. The physiotherapy regime is simple dorsiflexion and plantar flexion daily exercises both loaded i.e. with the toe grounded, and non loaded using the patients hands to drive full range of motion. I am always keen that the well, sometimes over-motivated, patients doesn’t force into a painful arc as this will generate inflammatory changes and subsequent scarring. “Little, often and without pain” is the motto I try to instil in both the patient and their attending physiotherapist. Ongoing considered range of motion exercises should continue for a full six months to gain the most from the procedure.
    I do not allow my patients to regain sport that involves running for 3 months but they are allowed to do pilates, yoga, cycling and such like non impact activities from week 4. Likewise I ask them to avoid heels for 3 months. This advice is to reduce the likelihood, in my opinion, of implant subsidence and so leads to a better long term outcome.
    I follow patients up for 6 months seeing them at weeks 2, 6 and 26. It takes 6 months before they feel satisfied in my experience and the data suggests that there is improvement in pain and range of motion up to and beyond a year (Baumhauer JF, Singh D, Glazebrook M, Blundell CM, et al. Correlation of hallux rigidus grade with motion, VAS pain, intraoperative cartilage loss, and treatment success for first MTP joint arthodesis and synthetic cartilage implant. Foot Ankle Int. 2017 Nov; 38(11):1175-1182). Patients are told of this at the outset to avoid a mis-match between expectations and reality.

    Recommended Reading

    Scientific Material Papers:
    Baker MI, Walsh SP, Schwartz Z, Boyan BD. A review of polyvinyl alcohol and its uses in cartilage and orthopedic applications. J Biomed Mater Res B Appl Biomater. 2012 Jul;100(5):1451-7.
    This article defines the structural characteristics of the hydrogel polymer and its use as cartilage replacement.
    Baumhauer JF, Marcolongo M. The Science Behind Wear Testing for Great Toe Implants for Hallux Rigidus. Foot Ankle Clin. 2016 Dec; 21(4):891-902.
    A paper discussing the mechanical were testing of a variety of 1st MTPJ replacements. It includes the animal testing of the Cartiva and its receptive cycle testing in the laboratory.
    Clinical Evidence:
    Baumhauer J, Singh D, Glazebrook M, Blundell CM, et al. Prospective, randomised, multicentred clinical trial assessing safety and efficacy of a synthetic cartilage implant versus first metatarsophalangeal arthrodesis in advanced hallux rigidis. Foot and Ankle Int. 2016; 37(5): 457-69
    The 2 year results of the pivotal MOTION study describing the prospective randomised control trial at 12 centres in UK and Canada, in which the Cartiva is compared to arthrodesis. The results of pain, activities of daily living and sports demonstrate non-inferiority of the Cartiva to arthrodesis and preservation of motion with a mean increase in range of motion from pre-op by 6 degrees for the Cartiva. The revision rate for both arms )i.e. arthrodesis and Cartiva) was 12% at 2 years. This paper when presented at AOFAS won the Roger Mann award for best clinical research paper.
    Baumhauer JF, Singh D, Glazebrook M, Blundell CM, Nielsen D, Pedersen ME, Sakellariou A, Solan M, Wansbrough G, Younger ASE, Daniels TR. Correlation of hallux rigidus grade with motion, VAS pain, intraoperative cartilage loss, and treatment success for first MTP joint arthodesis and synthetic cartilage implant. Foot Ankle Int. 2017 Nov; 38(11):1175-1182.
    This paper further stratified the results of the MOTION study specifically examining for correlations with the Coughlin grade of OA. Findings were that grades 2,3 and 4 performed similarly in all outcome measures.
    Glazebrook MA, Younger ASE, Daniels TR, Singh D, Blundell C, De Vries G, Le ILD, Nielsen D, Pedersen ME, Sakellariou A, Solan M, Wansbrough G, Baumhauer JF. Treatment of first metacarpophalangeal joint arthritis using hemiarthroplasty with a synthetic cartilage implant or arthrodesis: A comparison of operative and recovery time. Foot Ankle Surg. 2017-May-19.
    The study showed that for the MOTION study group average times for Cartiva operation were roughly half those for a fusion. Recovery of function was quicker to 6 months for the fusion group but at 1 year both arms had similar recoveries and this was maintained at 2 years.
    Goldberg A, Singh D, Glazebrook M, Blundell CM, et al. Association between patient factors and outcome of synthetic cartilage implant hemiarthroplasty versus first metatarsophalangeal joint arthrodesis in advanced hallux rigidus. Foot and Ankle International. 2017;38 (11):1199-1206
    This was a further regression analysis of the Cartiva arm of the MOTION Study cohort. Outcomes were independent of age, gender, BMI, Coughlin grade, severity or duration of symptoms. Hallux valgus patients however showed a worse outcome.
    Surgical Technique:
    Younger ASE, Baumhauer JF. Polyvinyl Alcohol Hydrogel Hemiarthroplasty of the Great Toe: Technique and Indications. Techniques in Foot and Ankle Surgery. 2013;12(3):164-169.
    Younger AS, Baumhauer JF, Glazebrook M. Polyvinyl alcohol hemiarthroplasty for first metatarsophalangeal joint arthritis. Curr Orthop Pract. 2013;24(5):493-497.
    Both of these papers described the technique for Cartiva implantation as is demonstrated in this Orthoracle case.
    Glazebrook M, Baumhauer J, Davies MB. Revision of Implant to Great Toe Fusion: Did We “Burn a Bridge” With a Synthetic Implant Hemiarthroplasty? Foot & Ankle Orthopaedics. 2017 Sep 11;2(3)
    The authors here review those cases where a Cartiva had failed to give pain relief and in each case an arthrodesis was successfully achieved with both a simple technique and an outcome equivalent to the arthrodesis arm of the original MOTION study group

    Reference

    • orthoracle.com

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