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Hallux Rigidus- First MTP Arthroscopy

    Overview

    Learn the Hallux Rigidus: First MTP Arthroscopy surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Hallux Rigidus: First MTP Arthroscopy surgical procedure.
    An MTP arthroscopy is a straight-forward operation to perform though with no absolute indications as open surgery is also an appropriate alternative for all conditions that can be treated by arthroscopy.
    The conditions most commonly dealt with are mild or moderate arthritic change, post-traumatic joint pain, osteochondral or chondral defects, loose bodies and synovitis.
    The advantage of big toe arthroscopy is that it results in potentially less pain and an earlier mobilisation (both generally and specifically of the joint) following surgery. This is due to the smaller soft tissue exposure used in comparison to an open technique. Evidence on any greater effect in terms of the outcome of conditions treated is lacking.

    Indications

    INDICATIONS.
    -Mild or moderate arthritic change
    -Post-traumatic joint pain
    -Osteochondral defect
    -Loose bodies
    There is no demonstrated advantage in terms of the longer term outcome using the minimally invasive technique versus an open First MTP debridement.
    There is in my experience less pain and swelling if surgery is performed arthroscopically, which is simply in keeping with all other joint arthroscopy. This allows in most cases a joint mobilisation program to start by the end of week one or two and a return to non-manual work within the same time frame.
    SYMPTOMS & EXAMINATION.
    The patient will have symptoms and signs well localised to the 1st metatarsophalangeal (MTP) joint. These symptoms will include pain , stiffness and locking. On examination signs will be swelling , local tenderness , reduced range and possibly a dorsal joint bony prominence (cheilus) from the MTP joint.
    In patients with early/mild or moderate 1st MTP arthritic change pain is usually activity related. In general it is present during (and for a variable time after) the mechanical stimulus but does not occur at night or at rest to any real extent. Pain will be well localised to the joint and normally deeply felt or dorsally felt.If well localised and consistent plantar pain is present the sesamoids should be considered as a source of possible pain .These are not likely to be adequately treated by a more general joint debridement if specifically symptomatic.
    Swelling and deformity will normally be present to a variable degree. In most cases the nature of the deformity will be a dorsal spur effecting the 1st Metatarsal head . It can also effect the base of the proximal Phalanx . On occasion the nature of the deformity is a Hallux Valgus which can co-exist with arthritis.
    The patient is likely to display pain at the end of range when the joint is passively moved rather than pain through-out the range(which is more an indication of severe degenerative change).
    If a patient just has isolated impingement pain then an isolated cheilectomy is reasonable. If joint symptoms are present then an arthroscopy should subsequently be performed (under the same anaesthetic).
    There is no demonstrated advantage in terms of the longer term outcome using the minimally invasive technique versus an open First MTP debridement.
    That is to say the chance of significant improvement in both cases is in the region of 70-80% (with a 5% chance of early significant worsening of arthritic joint pain).
    There is in my experience less pain and swelling if surgery is performed arthroscopically. This allows in most cases a joint mobilisation program to start by the end of week one or two and a return to non-manual work within the same time frame. The technique offers not only these early benefits but potentially an easier path to a maintained increased dorsiflexion range (compared to an open debridement) though this benefit is not proven.
    INVESTIGATION.
    A plain X-ray may be sufficient do diagnose some cases of mild or moderate arthritis.
    As an alternative an MRI can be useful in giving a view of the chondral surfaces (which can be effected prior to plain X-Ray changes). MRI is not however 100% sensitive for detecting chondral involvement. There is also no accepted percentage chondral coverage which is recognised as needing to remain for a good outcome to be possible.
    MRI is also indicated for assessing pain following trauma to the non-arthritic joint. It will identify osteochondral lesions (which are rare in the 1st MTP) as well as some chondral injuries (the feature most often present being subtle peri-articular oedema). It should be remembered that most often the pathology is either synovitis or arthrofibrosis , neither of which is detected by MRI.
    NON-OPERATIVE OPTIONS.
    –Joint injection( with or without manipulation): This can be a useful intervention in the earliest of arthritic cases, gaining up to 6 months of symptomatic relief . Sloan, Calder & Bendall reported on this in 2001 (Journal Bone Joint Surg 2001. 83(5):706-8)
    -Stiff soled & rocker profile shoes (eg. fit-flop , MBT ).
    -Rigid or semi-rigid functional foot orthotic


    Setup

    GA or regional anaesthesia
    Popliteal or intermeattarsal block for post-operative pain relief
    Laminar flow , peri-operative antibiotics and LMW Heparin
    Thigh tourniquet and Flowtron on contra-lateral calf
    Supine position and set-up with calf bolster and manual traction.

    Operation

    The First metatarsophalangeal (MTP) joint line should be first identified. This will be by a combination of plantar and dorsiflexion whilst palpating the joint as well as distracting the joint and looking for a “vacuum” sign (see next image).
    In this image the Extensor Hallucis Longus (EHL) tendon is easily visible (2) which serves as a marker for the midpoint of the joint. The metatarsal head has just been de-bulked with a minimally invasive cheilectomy through a medial portal(1).

    With the joint distracted by an assistant (1) a slight depression often develops in the soft tissues at the level of the joint .This is also known as the “vacuum sign” and identifies the level of the joint(2). I recommend operating lights are left turned on for this initial stage.

    A green or blue needle is carefully inserted into the joint whilst distraction occurs.
    It is inserted either to the medial or lateral side of the EHL tendon at the level of the joint , wherever the joint is more easily defined.
    The metatarsal head is in close proximity and care should be taken to avoid over-penetrating the joint and abrading the chondral surface.
    Two portals are required , each midway between the central EHL tendon and the outer margin of the joint.
    It matters little which one is done first.

    The assistant withdraws the needle and the surgeon then immediately incises with a finely pointed scalpel (No 11 blade). Care is taken to follow exactly the path of the needle (2) with the stab incision (1) through the capsule.

    The smallest of incisions is usually required. It will be angled towards the midline point of the joint.

    The exact path of the blade is next followed with a small and straight ended artery clip.
    This is then opened in the long axis of the toe to widen the portal .

    The blunt obturator from the arthroscope is initially inserted through the portal. It should pass easily into the joint. If it does not then change the angle of entry into the joint and if this does not lead to easy entry then repeat the previous stage carefully.

    The scope is next inserted and initial inspection made
    The fluid required should be infused at 40mmHg with an appropriate pump.
    Despite care being taken to follow the previous steps the first few insertions of the scope can still be tight. Go back through the last few steps in reverse if needed.
    Care should be taken not to turn on the fluid until a picture of the articular surfaces is seen. If fluid is accidentally infused into the soft tissues around the joint these will expand , pressing into the joint and reducing the joint/operating space.

    With the fluid running the joint (as well as the area of capsular release/stripping for the minimally invasive cheilectomy) will become visibly distended (2).
    The needle is inserted under direct vision (1) for the second portal placement and then the other steps are gone through as previously.
    Both portals are used interchangeably for the scope and instruments.
    Traction is on occasion made easier for the assistant by using a swab wrapped tightly around the toe (3). The commonly described alternative to this is a Chinese fingertrap.

    The main instruments used are the small coblation probe (used on predominantly coagulation setting to ablate soft tissue lesions) and a small (2.0 &/or 2.7 mm) full radius soft tissue resector . Care should be taken with the latter that the suction is on a low a setting as possible.
    Small joint instruments such as grabbers , hook and curved artery clip are also of use.

    Post Operative

    Obviously determined by the condition treated & associated procedures
    Assuming a straight-forward soft tissue scope then reduce the compressive forefoot bandage at 5 days and patient may be able to drive from then if comfortable and in appropriately supportive shoes.
    Wounds to be kept strictly covered by breathable dressings 24/7 and dry until 2 weeks.
    Sutures removed at this stage .
    Earlier wound exposure risks superficial infection which can progress to deep infection with rapid speed. Any simple arthroscopic portal erythema should be aggressively treated with high dose oral antibiotics and very early clinical review.
    Beyond 2-3 weeks patients may shower the ankle but keep dressings in place whilst in shoe-wear for a further week or two.
    The first two weeks post-op the patient should aim simply to return to comfortable walking.
    The realistic expectation after a soft-tissue scope is for largely unrestricted activity by 6 weeks.
    If the indication for operation has been arthritis then the time by which a steady state is likely to have been reached is on average 12 weeks and not 6. There is also an associated risk of immediate deterioration , maybe in 5% of patients.

    Recommended Reading

    Indications for and techniques of first metatarsophalangeal joint arthroscopy.
    Foot & Ankle International.2006.27(12):1049-1054.
    U.K.Debnath , M.V.Hemmady ,K.Hariharan.
    A mixed bag of the usual MTP pathologies in 25 feet( 20 patients).
    Ata minimum of 2 year follow up pain free in 19 of the feet.”
    Arthroscopy of the great toe
    .AAOS Instructional course lectures.1999.48:343-346.
    C.Frey , C.N.vanDijk.
    Good review article
    Hallux metatarsophalangeal (MTP) joint arthroscopy for Hallux Rigidus.
    Foot & Ankle Intl .36 (1) ,2015
    K J Hunt.
    Good review article and technique description . Full text at http://journals.sagepub.com/doi/full/10.1177/1071100714559728.

    Reference

    • orthoracle.com

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