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Calcaneal osteotomy with OrthoSolutions FRS Locking Plate

    Overview

    Learn the Calcaneal osteotomy with OrthoSolutions FRS Locking Plate surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Calcaneal osteotomy with OrthoSolutions FRS Locking Plate surgical procedure.
    A Calcaneal locking plate provides very robust fixation and optimally maintains the hard fought for displacement achieved performing a Calcaneal osteotomy.
    It is associated with low rates of implant removal and does not require image intensification necessarily during operation.
    However it self evidently requires an open technique , as opposed to screws which can be used with minimally invasive/percutaneous techniques. It is possible to fix the osteotomy in distraction at the osteotomy site unless care is taken.

    Indications

    INDICATIONS
    -The indications for performing a Calcaneal osteotomy are various but usually to correct hindfoot malalignment (valgus , varus , or high or low Clacaneal pitch)
    -The indications for using the plate to fix a Calcaneal Osteotomy are relative
    ADVANTAGES OF A LOCKING PLATE
    The plate allows very robust primary fixation even in poor quality bone given the screws lock into it.
    More importantly once applied to the Calcaneus the plate holds very precisely the displacement of the osteotomy .This is a significant advantage over the “parallel screws “method which usually results in some loss of the displacement , even if cannulated screws are used to splint the position during screw insertion.
    It also becomes possible to more easily hold the Calcaneus in certain planes against resistance , for example to increase Calcaneal pitch as part of a Pes Planus reconstruction.
    Another (& secondary) advantage over the parallel screw method is that no X-ray is required intra-operatively. The locking screws are simply measured with depth gauge which is easily applied and the plate dimensions are directly seen.
    Plates may seem bulky relative to screws but it is unusual to need to remove them post-operatively for reasons of impingement (unlike posteriorly located screws, see published results section).
    DISADVANTAGES OF A LOCKING PLATE
    An open approach is required for application of the plate which carries with it greater risks of soft tissue compromise than with a percutaneous ,minimally invasive technique.
    On a cautionary note good bone to bone contact should be ensured before locking the plate (see technique) . A risk is otherwise that the osteotomy may be fixed in a distracted position , which would raise the chance of non-union (which otherwise is a very rare eventuality).

    Setup

    Laminar flow theatre
    GA or Spinal anesthesia
    Thigh tourniquet
    Supine patient position
    Well padded bolster behind calf to raise heel off couch , slight internal tilt to table to stop external rotation of the limb.
    Peri-operative antibiotics & LMW Heparin prophylaxis.

    Operation

    A standard Atkins type approach(1) has been used here (see Calcaneal fracture fixation) but other lateral approaches also work. The peroneal tendons and sural nerve (2) have been lifted superiorly within the full-thickness soft tissue flap. A sub-periosteal stripping technique using a combination of sharp dissection and a large , round ended periosteal elevator .
    The superior and inferior bony margins of the Calcaneus should be defined in the area where the osteotomy is to be made. Superiorly (4) one doesn’t need to see the Achilles but should be able to palpate it. Anterior to this one should be able to appreciate the highest point of the posterior facet. Inferiorly (3) the calcaneus should be exposed well anterior to the weight bearing point of the heel

    The osteotomy is performed using a single sided and stiff, inflexible large reciprocating saw blade (1).
    The cut is oblique and the heel ideally is hanging dependant off a bolster , not “pinned” to the operating table. The cut should be well anterior to both the Achilles and the weight-bearing Calcaneal Tuberosity.
    The neuro-vascular bundle medially should be slightly anteriorly placed relative to this cut . Once the medial wall is palpably reached and notched with the saw blade the medial cut may alternatively be completed with controlled sharp osteotome cuts using a largish Hibs type osteotome. Care should be excercised to avoid over-penetrating the medial cortex. The osteotomy should be moderately or fairly mobile after this stage.

    Completing the osteotomy medially with an appropriate sized osteotome (1). If mobility is limited then medial bone spurs/edges should be looked for by visualising the medial aspect of the osteotomy by distracting it open with a laminar spreader (see next image). These can be removed using targeted osteotome blows. The Osteotomy will now be more mobile .

    A smooth bladed medium sized laminar spreader can also be useful at this stage. Gentle distraction through the osteotomy by using the spreader up and down its length usually results in as much mobility as one can achieve.

    With the Osteotomy now fully mobile it can be displaced , in this case medially . If the deformity being corrected is planovalgus one can consider increasing Calcaneal pitch by translating the posterior fragment (1) inferiorly as well.
    With a significant translation as seen here it is likely this will need to be maintained manually whilst an assistant passes a temporary , stabilising stout( 2.4mm) K-wire(s) from the posterior aspect of the heel.
    It is important that the direction of K-wire travel is specifically directed laterally from its entry point which will be mid-width of the posterior Calcaneus. Given the direction of translation of the heel is medial the medial soft tissues are at risk of being entered and damaged by the K-wire unless this is angled laterally as it passes forward across the osteotomy site.

    The Locking Calcaneal plate can now be offered up to the bone .
    The step produced (1) will determine the size of plate used . 10 or 12 mm is a large as most plates come and more displacement is unlikely to be required . Ideally the plate is placed mid-point (2,2) on the lateral wall. Attention should be paid that good bone to bone contact occurs at the osteotomy site(1).
    Another key point is that the plate should ideally sit completely flat upon the lateral calcaneal wall. If it does not then then the plate will have a tendency to lift when the screws are locked home. To ensure the plate sits flat feel free to remove some of the lateral wall bone if required.

    The drill-guides screw precisely into the plate. Care should be taken here to correctly locate the guide threads into those on the plate which can be easily threaded by forcing them. This will result in imprecise screw placement and incomplete seating ( and prominence) of the screw head. Drill in a controlled fashion and avoid over-penetration medially.

    An anterior screw should be inserted first. The plate will then buttress the mobile posterior fragment and maintain position . Because the screws lock into the plate there is less need for a good medial cortical fix ( which would risk over-penetration of the medial cortex ). By going shorter with the screws one can also avoid the need for an axial on table X-ray to confirm screw lengths. As long as the bone contact remains good at the osteotomy site at this stage the second ( and posterior ) hole is drilled , measured and screw inserted. On occasion as the first screw is tightened home and the plate firmly contacts the lateral cortex this can lead to some distraction at the osteotomy site. This will be due to imprecise initial placement of the plate. Tricks to try are either to slacken off the first screw slightly when the second hole is being drilled , then tighten both screws gradually together , or to remove the temporary K wire fixation.

    With the plate locked in position any remaining K wires are removed .The effect of a large displacement is a prominent lateral lip of bone at the osteotomy site. This can be smoothed-off /debulked with bone nibblers.
    Closure is with 2.0 Vicryl & 3.0 subcuticular vicryl. Insert drain according to preference.

    The plate has been used to achieve an increase in calcaneal pitch (as well as medial displacement) as part of a flat foot reconstruction. This is noticeable on the lateral Xray as a clear step at the inferior aspect of the osteotomy.
    This is a direction of displacement which can otherwise be difficult to maintain in this situation as the Achilles will tend to be on the tighter side and translate the distal osteotomy in a superior direction.

    There is some indication on the A-P X-Ray that a medial shift of the heel has occurred.

    This axial CT best demonstrates the significant medial shift in the Calcaneal tuberosity that can be maintained with step plate fixation.

    This axial CT best demonstrates the significant medial shift in the Calcaneal tuberosity that can be maintained with step plate fixation.

    Post Operative

    Remove drain at 24 hours if used
    Non-weight bear 5 -6 weeks
    Backslab post op till 2 weeks , dressing changes at 1& 2 weeks
    Full cast then till 5 -6 weeks & check Xray
    Long post-operative boot with crutches & increase weight bear as tolerated after 5-6 weeks
    Concurrently Physiotherapy to commence out of cast
    Initially non-weight bearing program of range of movement & strengthening , progressing to balance as full weight is tolerated.
    Once able to full weight bear comfortably out of post-operative boot consider transition into Stiff-soled hiking boot and subsequently normal shoe-wear once balance & swelling permit.

    Recommended Reading

    Comparison of three different fixation methods of calcaneal osteotomy.
    Foot Ankle Int 2013. 34(3):420-5
    Abbasian A, Zaidi R, Guha A, Goldberg A, Cullen N, Singh D.
    Lateral locking plate compared retrospectively with both headed and headless screws used via a plantar-posterior insertion point.
    67 osteotomies in all of which 2 underwent delayed union (both of which were lateral plates in which group wound complications were also higher) .47% of the headed screws required removal (17 osteotomies) ,11 of the headless screws (18 osteotomies) and 6 of the lateral plates (32 osteotomies)
    Comparing fixation used for Calcaneal displacement ostetomies: A look at removal rates and cost.
    Foot Ankle Spec 2015.8(1):18-22
    Lucas DE, Simpson GA ,Philbin TM.
    A large group with displacement osteotomies were fixed with either a lateral locking plate of lag screw fixation. Comparison made with respect to time to union and implant removal rates as well as number of follow up visits to discharge
    19% (32 patients) fixed with screws required removal against 1 patient with a locking plate. The screw group required more follow ups and time to union not different between the groups.
    Mechanical stability of a locked step plate versus single compression screw for fixation of a medial displacement calcaneal osteotomy
    Foot Ankle Int 2012. 33(8):669-74
    Konan S et al
    A cadaveric study in which 6 pairs of specimens underwent a 10mm medial displacement osteotomy fixed either with a 7mm screw or a step-plate with 4 locking screws.
    The locking plate construct required twice as much load to fail as the single screw.

    Reference

    • orthoracle.com

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