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Weils osteotomy (using Othosolutions forefoot reconstruction system, FRS)

    Overview

    Learn the Weils osteotomy (using Othosolutions forefoot reconstruction system, FRS) surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Weils osteotomy (using Othosolutions forefoot reconstruction system, FRS) surgical procedure.
    The Weils’ osteotomy is an effective, technically straightforward and reproducible way of reducing plantar metatarsal head pain due to mechanical overload. The metatarsal length is slightly shortened as well as the head elevated by the technique.
    Less commonly it can be indicated to deal with degenerate change from the lesser metatarso-phalangeal joints.
    It is important to preserve (or reconstruct) an appropriate “metatarsal arcade” whereby from lateral to medial each adjacent metatarsal is slightly longer than its fellow when viewed in the axial plane. Failure to do this will usually transfer mechanical pain down the line laterally to the next longest metatarsal.
    A Weils osteotomy is often performed part of a more general forefoot reconstruction, in patients with a hallux valgus and transfer metatarsalgia.

    Indications

    INDICATIONS :
    Lesser toe metatarsalgia (a common indication) .
    Lesser MTP symptomatic arthritis (a less common indication and usually effecting the 2nd MTP).
    Lesser MTP joint dislocation (combined with soft tissue rebalancing)
    To aid access and as part of a technique for plantar plate repair.
    SYMPTOMS & EXAMINATION:
    Patients present with weight-bearing pain underneath the lesser metatarsal heads or joint pain & stiffness (if the joint is arthritic)
    Patients will tend to be point tender under the relevant metatarsal heads (most commonly second and third) if the issue is one of “mechanical overload” of the metatarsal. The location of this discomfort on examination should correspond to the site of their symptoms during weight-bearing .These patients often will have plantar callosities under the metatarsal heads. Callosities though are not invariable in patients with high metatarsal head plantar pressures, in particular in the elderly with thin plantar fat pads.
    There are other causes of pain in this area of the forefoot and it is always worth examining the foot for an intercurrent Mortons’ neuroma by medio-lateral and axial compression of the web spaces which will usually produce pain if present. Pain in this instance often radiates into the toes. This pathology may of course co-exist as opposed to being an alternative diagnosis.
    It is not uncommon for patients with lesser ray metatarsalgia (the main indication for a Weils osteotomy) to have inter-current first ray pathology, in particular Hallux Valgus which should also be assessed and may need operation if symptomatic.
    It is also not uncommon for the effected lesser toe to have an associated saggital plane hyper-extension deformity at the MTP level. Such hyper-extension of the toe contributes to increased plantar pressure and tendon lengthening may also be required. It is possible that the slight shortening of the metatarsal produced by the Weils osteotomy will result in enough soft tissue laxity to correct this without any need to lengthen the tendons.
    It is important not simply to examine the forefoot in isolation even if forefoot symptoms alone are present. Self evidently a Cavus foot or Achilles contracture driving a forefoot strike during gait will both lead to high forefoot pressures and issues with the causative pathology lying elsewhere should be considered.
    NON-OPERATIVE MANAGEMENT:
    The initial management of metatarsalgia should in most patients be with appropriately off-loading orthotics or shock absorbing shoewear. Fit-flop shoes , a UK manufactured shoe , or a semi-rigid off the shelf Functional Foot Orthotic (FFO) are good starting points. Custom made orthotics may be more effective in the long term however .
    Regular debridement of plantar callosities also helps if these are present.
    INVESTIGATION:
    An AP X-Ray is required in all patients pre-operatively which will often reveal an issue with the relative metatarsal lengths , and identify degenerative change if present.
    If there is no abnormality on the AP X-Ray a lateral or oblique X-Ray is often of little use in assessing the plantar inclination of the metatarsal heads . If this is a consideration then a limited coronal CT may be indicated which gives a much more objective picture of the weight-bearing profile of the forefoot.
    Assess the forefoot also with Ultrasound if a Mortons’ neuroma or synovitis is queried.
    SURGICAL ALTERNATIVES TO A WEILS’:
    Not all lesser toe metatarsalgia is appropriately treated with a Weils osteotomy.
    Exceptions are:
    – Congenital curly fifth toe treated with an extensive soft tissue release.
    -Cavus foot where a Wedge Tarsectomy or closing dorsal wedge basal metatarsal osteotomies may be required.
    -Rheumatoid Foot where metatarsal head excision is more appropriate in the presence of joint destruction
    -Elderly , low demand patient with poor bone quality where a metatarsal plantar condylectomy may be considered.
    -There is debate about the role of Achilles or Gastro-Soleus release in the surgical management of Forefoot overload symptoms and this should always be assessed.
    CONTRAINDICATIONS:
    Conditions and medications that effect soft tissue and bone healing need to be optimised as does the vascular inflow. Smoking should be ceased during the post-operative period and patients should be compliant with post-operative requirements.


    Setup

    General or Regional anaesthetic
    Antibiotics & LMW Heparin on induction
    Laminar flow theatre if available
    Ankle tourniquet
    Patient supine
    Pre/post operative Nerve block (popliteal and / or inter-metatarsal )for analgesia
    High speed saw & wire driver / drill
    Lambotts osteotomes

    Operation

    A fairly innocuous picture of a foot that appears normal both in its dorsal and lateral aspects when weight-bearing but with significant lesser metatarsal head pain on loading.

    The plantar aspect of the same foot shows very clearly diffuse and significant callosities under the second to fourth metatarsal heads indicating mechanical overload of these metatarsal heads.

    A longitudinal dorsal incision is made extending from base of proximal phalanx to just proximal to the metatarsal neck.
    The base of the proximal phalanx is always a bit more proximally located that one expects, and in this picture will be about a cm proximal to the distal extent of the wound.
    If two neighbouring metatarsals are being operated upon then the incision sits between them in the area of the intermetatarsal space.
    If two separate dorsal incisions are required then ensure the “skin-bridges” between them are as wide as possible.

    Blunt dissection through the fat layer in the line of the metatarsal reveals the Extensor digitorum longus(1) and brevis (2, which lies laterally) tendons.Whilst scissor dissecting the fat layer fine cutaneous nerve branches may be encountered which should be preserved if practical.

    The extensor tendons are left intact and retracted laterally using a wests retractor(1) following which the dorsal capsule (2) is opened longitudinally in the line of the metatarsal to expose the head and neck(3).
    If a hyper-extension deformity is also being corrected it is probably worth waiting to reassess the soft tissue tensions until after the Weils osteotomy has been translated. This by itself will produce additional laxity of the tendons without any release being performed.
    On occasion if the hyper-extension is particularly marked then a tendon lengthening will need to be performed initially just to allow adequate access to the dorsal aspect of the metatarsal , pre-osteotomy. The nature of this should be a Z-lengthening of the longus tendon & division of the brevis tendon.
    On occasion significant shortening of the metatarsal is required which will probably result in laxity of the extensors and a visible lag.
    The tendons should under these circumstances be carefully shortened/tightened to leave them commensurate with the resting tension in any unoperated toes, at the end of the procedure.

    Once the metatarsal neck has been exposed the collateral ligaments are freed on the medial and lateral aspects of the joint by sharp dissection (1).
    This is in every case, but to a greater or lesser extent depending on how tight they are. A Homans’ retractor needs to slide between them and the metatarsal neck to hold the soft tissues away from the neck and deliver the metatarsal head so that it is in a safe and adequately exposed position to cut.
    Stick very closely to bone when freeing the collaterals and dissect along the bone proximally. A good technique is to insert a McDonalds distally between the metatarsal head and the capsule and place the capsule and collaterals under tension whilst freeing them off the lateral & medial aspects of the bone.
    Cut inside the capsule from distal to proximal and stay on the bone. Alternatively cutting from “outside to in” to access the collateral ligaments risks injuring the neuro-vascular bundles, and should not be done.
    Any chondral or soft tissue joint pathology effecting the joint can be treated at this stage.

    To judge the screw length it is offered up against the metatarsal in the line in which it will be used.There is no accurate way of measuring the screw size needed as it is self drilling and self tapping. The screw as seen here comes as a single unit with its shank attached.
    The screw sizes are 11-14mm lengths in 1mm increments.

    With the collaterals released two homans retractors (1) are placed adjacent to the metatarsal neck to expose the head (2) and neck and protect the neuro-vascular bundles.

    The line of the osteotomy is taken dorsally through a few mm of metatarsal head(2) and the saw blade needs to be angled fairly acutely and plantarwards(1).If this is not done the risk is of producing a very long osteotomy which will not be especially moveable.
    See what fits but an angle of 30-45 degrees to horizontal would not be unusual
    Choose a short & narrow saw blade.

    Care should be taken to prevent much medio-lateral movement of the saw blade(1) beyond the bone as this may result in injury to the neuro-vascular bundles.

    Once the first saw cut is almost complete it is usual to make a second parallel cut into the metatarsal head, thus removing a dorsal sliver of bone once the cut is completed.Usually once the saw cuts are complete on the plantar surface the lower (head) fragment translates proximally almost automatically(as here). If it does not a well directed tap with a lambotts osteotome (1) will assist.
    A nice technique is when making the first cut do not complete this fully, but take it quite close to this (you will start to feel some increased resistance from the inferior bone cortex before it cuts fully and stop progressing the cut at this stage). Then place the second cut inferior to it by a mm or two and complete this one fully with the saw. It will be necessary to lever off the sliver of bone with a small ,sharp Lambotts osteotome.

    The head fragment can be very mobile on occasion and it is best stabilised by holding it reduced with a smallish artery clip (as soon as it has been mobilised following osteotomy) , applied carefully to the sides of the metatarsal head.The head fragment(2) now translated proximally
    and sitting evenly beneath the dorsal shaft(3). The blunt end of a Mcdonalds is useful to guide the head into position. Depending upon what the aim is the head can be moved in one (or more) of three ways, namely translation proximally, medio-laterally or rotation.

    The now mobile metatarsal head should be accurately positioned in its corrected, and foreshortened position. This needs to be confirmed by direct visualisation of its immediate neighbours or using an image intensifier before the chosen twist-off screw is inserted under power.The twist off screw is mounted in a Jacobs chuck and drilled on low speed. Once flush with the dorsal bone the shank is broken to detatch the screw. Often this will occur whilst the screw is being inserted and it will need to be finally driven home using the screw driver supplied
    It is useful to excert a degree of control/counter pressure when the screw is being inserted by placing a thumb firmly underneath the metatarsal head whilst downward pressure is applied with the twist-off screw.
    It is helpful to control the position of the metatarsal head using a fine artery clip or mosquito either side of the metatarsal head and counteract the tendency to displacement during fixation.

    The length of the shortened metatarsal is compared to its neighbours using image intensifier. Only after the correct relative length is confirmed is the dorsal lip of bone removed.Prior to this the screw can be removed and repositioned/replaced if the length requires adjustment.
    If the metatarsal is shortened too much relative to its neighbours then a normal smooth “metatarsal arcade” is not re-established and overload is potentially transferred to the neighbouring metatarsal.
    With experience Image intensifier may not be required if each metatarsal head can be visualised sequentially next to its neighbour. Careful assessment should always be made about the metatarsal lengths.
    After fixation of the osteotomy the tendon tensions should be assessed (if not already released) . Compare the resting position of the operated toe to its neighbouring lesser toes and also simulate weight-bearing by applying pressure under the metatarsal heads to judge whether release (or tightening ) of the extensor will be required.
    It is important to ensure good surgical repair of the tendon with several 2.0 vicryl sutures.

    Xray appearances pre and post operatively
    This patient has had a first metatarsal osteotomy for hallux valgus a number of years previously which has resulted in shortening of the first metatarsal and transfer metatarsalgia effecting 2nd & 3rd metatarsals only. A significant amount of shortening of the 2nd and 3rd metatarsals has been required and would have left the 4th relatively long if not also shortened.
    Note that a normal “metatarsal arcade” has been re-established with each metatarsal from the 5th to the second being just fractionally longer than the next and the 1st metatarsal broadly similar in length to the 2nd.
    This is the sort of case where careful tightening of the extensor tendons may be required after such comprehensive shortening of the metatarsals.This is a decision to make on table
    An alternative solution to the problem would be a lengthening first ray osteotomy (such as can be achieved with a Scarf cut).

    Xray appearances pre and post operatively of a foot with a constitutionally short first metatarsal with Hallux Valgus and a symptomatic bunionette .In addition the patient had been suffering with significant 2nd to 4th transfer metatarsalgia associated with a diffuse planter callus here and point tenderness to the metatarsal heads.
    Treatment required significantly shortening Weils osteotomies to the 2nd through to 4th toes as well as chevron to the Hallux and a small osteotomy to the 5th metatarsal .

    Post Operative

    Patients require a post-operative X-Ray before discharge (often taken on-table to confirm the Metatarsal lengths) and a final X-ray at 5-6 weeks (assuming all is well). X-ray may be required beyond this if there are problems.
    LMW Heparin is administered for 2 weeks
    Weight bearing is using appropriately stiff soled post operative shoe for 5-6 weeks
    Crutches likely required 1-2 weeks
    Patients are taught self-mobilisation of the operated MTP joint from 2-5 weeks post operatively . What exactly to do and when is determined by the associated soft tissue procedure and comfort of the patient.
    If a hyper-extended toe has required soft tissue /tendon lengthening then it should have corrective plantar to dorsal strapping performed by the patient for up to 8-12 weeks post-operatively. During this time fibrosis and scarring of the operated soft tissues will occur and may result in a recurrent hyper-extension if no measures are taken.
    If the tendons have been tightened then dorsal supportive taping to prevent an extensor lag is used.
    A bulky bandage is used for a week or two followed by local dressings to the toes.
    These dressings are to continue 24/7 until all wounds are dry.
    From 4 weeks the patients should cleanse the foot twice a day, once in a salt water bath and once by bathing/showering
    Dressings to continue for the first month in normal shoe-wear.
    Appropriate shoe-wear fit is vital in the first month or so after post-op shoe
    I advise fit-flops , Uggs , wider fits or open sandals. Stiffer Heels ( platform or wedge ) are encouraged in women , from when comfortable , to promote MTP dorsi-flexion.
    Patients may soonest start a static bike & swim from 5-6 weeks , Cross-train from 7-8 weeks and re-start light jogging on treadmill from 10 weeks .

    Recommended Reading

    The Weil Osteotomy:A seven year follow up.
    J Bone Joint Surg.2005.87-B;1507-1511
    S.G.Hofstaetter , J.G.Hofstaetter , J.A.Petroustas , F.Gruber , P.Ritschl , H.Trnka.
    25 feet , indication for operation was dislocated MTP joint or severe plantar callosity.
    Excellent or good results little changed over the study period and in the mid 80% range.
    Patients opinion of outcome improved over the study period with 60% excellent or good results at a year improved by the time of the seven year follow up
    Redislocation rate was 12% and almost 70% of patients had toes that did not make ground contact (floating toes) though these were not painful.
    Dorsiflexion contracture after the Weil osteotomy: results of cadaver study and three-dimensional analysis.
    Foot Ankle Int. 2001 Jan;22(1):47-50.
    Trnka HJ ,Nyska M, Parks BG, Myerson MS
    This interesting cadaver study identifies that by the depression of the metatarsal head which can occur as a result of a Weils the interosseous muscles act as dorsiflexors ( and not plantarflexors as intended).

    Reference

    • orthoracle.com

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