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Supra malleolar tibial osteotomy-Medial opening wedge with Arthrex plate

    Overview

    Learn the Supra malleolar tibial osteotomy-Medial opening wedge with Arthrex plate surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Supra malleolar tibial osteotomy-Medial opening wedge with Arthrex plate surgical procedure.
    A supra-malleolar tibial osteotomy is used for either a varus or valgus tibial malalignment in the presence of a salvageable osteo-arthritic joint (or indeed before the ankle has become arthritic). It can also be used with a normal diaphyseal alignment but intra-articular angular deformity.
    What is a salvageable joint and what is not is not well defined in the literature. The upper limit of deformity that responds well to the technique is also not defined. It is not simply to be regarded as analogous to a proximal tibial osteotomy in an early arthritic knee which is a more commonly indicated operation with a much greater body of evidence behind it.
    The principle (as with proximal tibial osteotomies) is to preferentially load healthy articular surface and redistribute weight away from the deficient parts of the joint. The most common scenario is the varus joint and this can be corrected either with a medial opening wedge or a lateral closing wedge. The medial wedge will stretch the medial soft tissues and the use of an appropriately sized tibial plate does nothing to lessen this.
    If used as an arthritic joint sparing salvage procedure patients will have mild or moderate ankle arthritis only and symptoms commensurate with this. The predictable and in general long lived and highly functional results to be expected after an ankle fusion should not be disregarded in this patient subgroup.


    Indications

    INDICATIONS
    -A supra-malleolar osteotomy is used for either a varus or valgus tibial malalignment in the presence of a salvageable osteo-arthritic joint.
    -A supra-malleolar osteotomy can also be used with a normal diaphyseal alignment but intra-articular angular deformity.
    The technical considerations are:
    What is the extent of the arthritic change. This in my opinion requires an MRI, but all cases are also arthroscoped at the time of surgery.
    Where does the deformity lie. Intra-articular or extra-articular and where is the CORA , Centre Of Rotation of Angulation?.
    Whether to use an opening or closing wedge. Personal preference and effected by the medial soft tissue envelope which if poor can be unforgiving.
    At what level to make the osteotomy. Either at the CORA or a predetermined point above the joint but remaining in metaphyseal bone.
    Whether to correct to a neutral alignment or slightly overcorrect the deformity.
    How to fix the osteotomy. A robust plate, or frame, is required.
    How to fill the large void produced by an opening wedge. Autograft is likely to be insufficient.
    How to deal with the fibula. The design and location of the osteotomy and how to fix it. The Teramoto distal tibial oblique osteotomy is a design that exits laterally and inferiorly at the level of the distal tib/fib joint and as described requires no osteotomy of the fibula.
    Whether additional correction may be required. On occasion the need may present for an intercurrent calcaneal osteotomy.

    SYMPTOMS AND EXAMINATION
    Patients will have mild or moderate ankle arthritis and symptoms commensurate with this.
    It should be borne in mind that the deformity may not be uni-planar. That is to say there may be a degree of rotational deformity associated which may also require correction through the osteotomy. This may be difficult to appreciate at the time of examination but should be looked for at the time of surgery also.
    It should also be remembered that a more proximal deformity may be present, contributing to the distal position. As a general principle any proximal deformity should be corrected first.
    Clinically the whole of the effected lower limb should be examined (as of course one routinely does with each & every foot and ankle examination)
    INVESTIGATION
    -Weight bearing plain X-Rays. The extent of the degenerate change can be estimated and the location of the deformity appreciated.
    –MRI scan. Gives a more objective assessment, though far from infallible, of the articular surfaces.
    Even if imaging suggests the joint to be salvageable patients need to be aware that a final decision will be made at the time of surgery when the joint is assessed directly by arthroscopic examination .

    Setup

    GA or regional anaesthesia
    Femoral & sciatic blocks for post-operative pain relief
    Laminar flow , peri-operative antibiotics , 2-4 weeks of post operative LMW Heparin
    Thigh tourniquet and Flowtron on contra-lateral calf
    Ankle positioned into neutral using sandbags & side supports
    Large , rolled up sterile towels behind the ankle to improve access for cuts.

    Operation

    Post-traumatic varus malunion of a pilon type distal tibial fracture. Good apparent joint space preservation with narrowing mainly to the lateral aspect of the plafond. Internal fixation had been removed and the joint debrided elsewhere as an initial attempt at salavage which had failed. This is a weight-bearing X-ray.

    Prior to the open work the ankle should be arthroscopically assessed.
    It is possible that MRI has not revealed the true extent of degenerative change and if too advanced will mean most likely a corrective fusion should be proceeded to instead. Pre-operative discussions should have taken place with the patient about both and appropriate consent taken.
    The first bony stage of the operation is to perform the fibula osteotomy but to get the level the same as for the tibial osteotomy it helps to get the tibial cutting jig set up(as detailed in the next few slides) and use this as a marker for the Fibula cut.
    The Fibula can be approached through a small direct lateral incision and a laterally based wedge of bone removed. My own preference is to internally fix this osteotomy after the tibial plate has been applied. Not all surgeons fix the fibula.
    A medial midline incision with full thickness skin flaps(in this case re-opening the previous surgical scar) is used. The saphenous nerve and vein sit in the fat layer close to the anterior crest of the tibia. If the vein is cut it will bleed a lot and need ligation.
    The Tibialis posterior sheath needs to be opened (1) to identify the posterior border of the tibia. A sub-periosteal dissection needs to be performed between the deep aspect of the tendon and the bone.
    Once the plane between bone and soft tissue is identified this needs to be developed and the soft tissues freed off the bone in preparation for the osteotomy. A large, round-nosed blunt edged periosteal elevator combined with occasional sharp knife dissection is used for this.

    The large blunt ended periosteal elevator is also used to sub-periosteally dissect across to the lateral tibial cortex(1).

    An initial guide wire (on the set) is drilled into the lower tibia a few cm above the joint line and paralleling the joint line. Medio-laterally it should sit in the midline. Its position on the A-P X-Ray is checked with image intensification.

    A second guide wire(2) is placed parallel and superior to the first(1) at the planned level of the osteotomy. This will generally be at the CORA of the deformity. In cases of extra-articular deformity this generally corresponds to the site of tibial fracture malunion. The second wire is placed precisely parallel to the joint line using the guide on the set.
    It is not however always technically possible to perform the osteotomy at the level of the fracture and it should be located in a position which enables appropriate positioning and fixing of the plate. Ideally this will be in metaphyseal bone which heals more predictably than diaphyseal bone.

    The wire and cutting guide are next turned through 90 degrees to the plane of the osteotomy(1).To stabilise the wire and cutting guide a second guide is inserted into the tibia (2) posterior to the first.The previously reflected soft tissue envelope is retracted using blunt end retractors(3,4) anteriorly and posteriorly.

    Having first performed a fibular osteotomy through a direct lateral incision(at the level of the planned tibial osteotomy) ,the tibia is then osteotomised using a large oscillating blade(1). The anterior(3) and posterior (2) soft tissues are protected with retractors.
    The arc made by the blade should not be too wide but the blade needs to be relatively long and stout.
    Once the far cortex is reached it should be progressively and carefully weakened with probing cuts from the saw. Cutting it completely makes the situation much less stable .
    If this occurs you will likely need to stabilise the osteotomy temporarily with K-wires.

    The osteotomy is left incomplete laterally. A large osteotome (1) is used to lever gently and test mobility. More careful and probing lateral tibial sawing may be required.

    Use the Arthrex distractor to open the osteotomy under controlled tension. As the screw is tightened(1) the broad blades are pushed apart and the osteotomy opened medially.
    The trick is to pay careful attention to how the osteotomy is reacting. If there is minimal movement as the blades are being opened consider very fractionally weakening the lateral cortex again with the saw and then re-inserting the distractor again.

    The size of the metal wedge required to correct the joint is trialed using the graded trial wedge.
    The position needs also to be checked radiographically to ensure adequate correction has been achieved before plate size is finalised.
    At this stage with the angular deformity corrected also assess the rotational profile of the ankle. If not correctly aligned this can be corrected through the osteotomy.

    The appropriately sized plate applied. With the deformities being treated a large gap is likely as seen here. It is often difficult to fill this with enough auto-graft. Either donor femoral head or a manufactured substitute (such as Wright Allo-matrix) should be available.
    A conversation needs to be had with the patient pre-operatively about the benefits and risks of donated bone products.

    The screw holes are divergent and progressive alternate tightening of all screws is likely to be required as opposed to sequential. This plate requires AO large fragment screws and is non-locking.

    The osteotomy grafted with donor femoral head graft(1).
    The Tibialis posterior tendon visible posteiorly(2).
    Closure can be with 2.0 & 3.0 vicryl sutures.
    If a large opening wedge has been required the medial skin closure can be tight.

    Pre and post operative Xrays of the Arthrex opening wedge plate for supramalleolar osteotomy.
    On the post-operative image note the slight valgus that has been produced at the Fibula fracture site. Not also that the most lateral aspect of the osteotomy is irregular as during completion of the cut with osteotome the bone fractured through the line of the old injury.
    The gap has been filled with femoral head allograft.

    Post operative X-Rays of the Arthrex opening wedge plate for supramalleolar osteotomy.
    It is worth reflecting that had the plate been placed any more distally the result would likely have been an intra-articular screw or two from the plate.

    Apperance at three months. The femoral head allograft is now well incorporated.

    An alternative procedure is an intra-articular correction using a corrective fusion. This may be more appropriate if the articular surfaces are significantly osteoarthritic. This is determined by an ankle arthroscopy at the time of surgery. Again note that the articular surface appears well maintained on the AP X-ray but this was not reflected by the arthroscopic findings.
    The small wire in the talus is a sheared off guide wire tip. No harm given its intra-osseous position apart from to a Surgeons pride.

    Post Operative

    2 weeks in back-slab
    dressing changes at 1 & 2 weeks
    Complete cast between weeks 2 to 6 & non-weight bear
    Check X-ray at 6 week stage . Usually may commence light weight bear and progress to 50% body weight by 12 weeks. Dependant upon age , bone quality and co-morbidities, either week
    6-12 in a robust post-operative boot or in a walking cast.
    Physio to commence once out of cast and basic range of movement progressing to strengthening then functional rehabilitation as tolerated.
    Further X-ray at 12 weeks. Satisfactory progression is judged by both radiographic progression as well as a patients comfort upon limited weight-bearing.
    Generally a further 6 weeks is required at this stage in a post-operative boot.The progression from partial to full weight-bearing is made during this period.
    A further X-ray is performed at 18 weeks to confirm union and if symptoms are in keeping with this the patient may move onto a stiff-soled hiking boot for a further 4 weeks, then normal shoes.
    No heavy manual type activity or sport for 5-6 months post operation.

    Recommended Reading

    Results of opening-wedge osteotomy for the treatment of a post-traumatic varus deformity of the ankle.
    Y.Takakura, T.Takaoka et al.
    J Bone Joint Surg1998.80-A:213-218.
    9 patients, all united, average follow up 7 years. Arthritis was a reason for exclusion from this study.
    No restriction in Activities of daily living post-operatively.
    Excellent results in 4, Good results in 2, fair in three.”
    Low tibial osteotomy for Osteoarthritis of the ankle .
    Y.Takakura , Y.Tanaka ,T.Kumai , S.Tamai.
    J Bone Joint Surg 1995.77B:50-54.
    5 patients closing wedge , 1 with oblique osteotomy , 12 opening wedge. Delayed union 4 cases , all united by 6 months.
    Mean follow up 6 years & 9 months.
    All cases arthroscoped intraoperatively & 10 of the 18 post-operatively of which 7 had evidence of fibrocartilage formation. Excellent results in 6, good 9, fair 3.
    Low tibial osteotomy for varus-type osteoarthritis of the ankle .
    Y.Tanaka ,Y.Takakura et al .
    J Bone Joint Surg 2006.88B:909-13.
    19 of 26 females ankles scored excellent or good with a mean follow up of 8 years. Joint space recovery seen in cases graded milder on their own plain X-ray classification. 4 went on to non-union requiring secondary surgery. The ankles are not reported to have been arthroscoped. Only autograft used, but small Japanese female ankles . Fibula seems not to have been fixed. The paper postulates that these cases of intra-articular deformity are a Japanese sub-type.

    Reference

    • orthoracle.com

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