The Teramoto distal tibial oblique osteotomy (DTOO): surgical technique and applicability for ankle osteoarthritis with varus deformity
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We have devised a medial peri-articular osteotomy, the distal tibial oblique osteotomy (DTOO), and have used this technique since 1994 for ankle osteoarthritis of advanced and late stages associated with varus inclination. This report describes the surgical technique and its applicability. DTOO can be used for cases of varus ankle osteoarthritis with a range of the ankle joint movement of at least 10° or more. The osteotomy is obliquely directed cut across the distal tibia from proximal-medial to distal lateral and is of an opening-wedge type with the centre of rotation coincident with the centre of the tibiofibular joint. A laminar spreader instrument is inserted in the osteotomy to open the wedge until the lateral surface of the talar body is seen on X-ray to be in contact and congruent with medial articular surface of the lateral malleolus. Common obstacles which may prevent this contact and congruency are bony spurs present on the anterior side of fibula or on the lateral side of the tibia; these require removal. The opening-wedge osteotomy is held in position by an Ilizarov external fixator or internally fixed with a plate. Bone graft is taken from the iliac crest and inserted into the open wedge. If, after completion of the osteotomy, the dorsiflexion angle of the ankle joint does not exceed 0°, a Z-lengthening is performed of the Achilles tendon. In the DTOO for ankle osteoarthritis, the contact area of the ankle joint increases and decreases the load pressure per unit area. Furthermore, as the width of the ankle mortice is restored through the realignment of the body of the talus, instability at the ankle joint decreases. There is additional improvement with restoration of the inclination of the distal tibial articular surface as this directs the hindfoot valgus and corrects the alignment of the foot, with consequent improvement of ankle pain.
KeywordsAnkle Tibia Deformity Distal tibial oblique osteotomy Varus Ankle osteoarthritis
Historically, supramalleolar low tibial osteotomies (LTO) [12, 13, 14], total ankle arthroplasty (TAA) [6, 7] and arthrodesis of the ankle (AA) [1, 2, 3] have been performed for the surgical treatment for ankle osteoarthritis. It is accepted generally that the LTO is not suited to advanced or late stages of osteoarthritis [13, 14]. Although it is considered that the TAA maintains a range of the ankle joint movement, it not suited for patients who anticipate manual work or active leisure pursuits as daily undertakings [6, 7]. Ankle arthrodesis (AA) is used for cases of advanced and late stages of osteoarthritis whilst it is successful in producing a stable and pain-free ankle, it sacrifices mobility, and there is the possibility of degenerative changes in adjacent joints with time.
We have devised a peri-articular osteotomy, the distal tibial oblique osteotomy (DTOO) and have used this technique since 1994 for varus ankle osteoarthritis of advanced and late stages. This achieves the objective of maintaining mobility of the ankle joint and reconstructing the ankle mortise such that it is capable of high demand activity and is accompanied with good clinical results. DTOO is a surgical technique able to realign the ankle joint surface without cutting the fibula. The purpose of this report is to describe the surgical technique and its applicability for varus ankle osteoarthritis.
Clinical indications for the procedure
Takakura classified varus ankle osteoarthritis into four stages using weight-bearing radiographs: .
Stage 1 No joint space narrowing but early sclerosis and osteophyte formation.
Stage 2 Narrowing of the joint space medially.
Stage 3 Obliteration the joint space with subchondral bone contact medially.
Stage 4 Obliteration of the whole joint space with complete bone contact.
In clinical use, a simplified form of the classification describes stage 1 as early, stage 2 and 3 as intermediate, and stage 4 as late. Tanaka further classified stage 3 into stages 3a and 3b. In stage 3a, the obliteration of the joint space was limited to the medial malleolus and in stage 3b, the obliteration extended to the roof of the dome of the talus. Tanaka concluded that LTO can be used for up to stage 3a according to this classification for ankle osteoarthritis, and that it is not indicated for advanced nor the late stages 3b and 4 [13, 14]. In comparison, the DTOO is indicated for all stages of varus ankle osteoarthritis as long as there is a movable range within the joint, typically at least 10° or more [9, 10]. Use of this technique should be based on taking into consideration the patient’s social, work and sports activities—regardless of patient’s age or stage of ankle osteoarthritis as based on the classification by Tanaka. However, the DTOO is contraindicated in patients with joint degeneration after infected arthritis, rheumatoid arthritis, a Charcot joint and steroid-induced arthropathy.
Osteotomy stabilisation with an Ilizarov external fixator
A skin incision 3 cm long is made about 7 cm proximal to the tibial articular surface on the medial side and a subperiosteal exposure created. Using X-ray image intensification, a check on the starting point of the osteotomy is made to ensure it is about 6 cm proximal to the tibial articular surface. The cut is made obliquely towards the centre of the tibiofibular joint. A 2-mm Kirschner wire is driven from the proximal-medial to distal lateral in the coronal plane and towards the centre of the tibiofibular joint; this guide can be used to direct the osteotome for the osteotomy.
Ilizarov rings are applied in three locations: just below the proximal tibial tubercle (A), tibial diaphyseal region (B) and just above the ankle (C). The first Ilizarov ring is fixed in place perpendicularly to the tibial shaft just below the tibial tubercle using two wires and two 6 mm half pins. The clearance between the front of the tibia and the ring is set to approximately three finger breadths (Fig. 2d, e). Next, the Ilizarov ring in the diaphyseal region is fixed in place with two 6-mm half pins. Finally, the distal bone fragment is fixed in place with five Ilizarov wires. On this last ring, the most distal Ilizarov wire is inserted parallel to the middle Ilizarov ring (B—diaphyseal region). This Ilizarov ring is positioned just above the ankle joint (C) to be parallel to the Ilizarov ring (B) of the diaphysis. Next, more Ilizarov wires are inserted posterior to the fibula forwards in a medial direction; additional wires are inserted in safe corridors around the ankle such that the distal ring(C) is secured by 4 or 5 Ilizarov wires. After confirming that the bone fragment is fixed in place and does not move after removing the spreader, bone graft is taken from the iliac crest and transplanted. Recently, two 2.4-mm Kirschner are added percutaneously from the medial malleolus to augment stability and removed once healing is complete (Fig. 2d).
In those patients in whom the dorsiflexion angle of the ankle joint does not exceed plantigrade after completion of the osteotomy and bone grafting, a Z-lengthening is performed on the Achilles tendon. Finally, the wound is lavaged and a Penrose drain is placed prior to closing the wound. After the operation, attention should be paid for potential skin necrosis; in many cases, the medial skin gets tense after the correction with possibility of necrosis or blistering.
The Ilizarov external fixator may not be suited for some clinical cases. When a hemiarthroplasty or total knee arthroplasty has been used for the ipsilateral knee joint or if the Ilizarov external fixator is declined by the patient, locking plate fixation is used. For such cases, the tension created on the medial side makes plate insertion on the same medial surface difficult, and as such, a compromise to the degree of correction has to be made in order to facilitate skin closure over the plate. This is a strong argument for using the Ilizarov external fixator for fixation of the osteotomy [9, 10, 11]. Alternatively, the problem of tension on the medial skin can be reduced if some bone is removed from the cortex on the medial side of the distal tibia to facilitate adequate correction and wound closure without tension. We have noted that if there is no previous scar on the medial skin and the osteotomy separation is less than 15 mm, a locking plate can be inserted without removing the medial tibial cortex and cancellous bone. In any case, the most important point is to avoid an insufficient correction just to facilitate plate insertion and wound closure [9, 10].
Osteotomy stabilisation with a locking plate
The surgical strategies of intra-articular debridement (IAD) [4, 8], low tibial osteotomies (LTO) [12, 13, 14], total ankle arthroplasty (TAA) [6, 7], arthrodesis of the ankle (AA) [1, 2, 3] and distraction arthroplasty (DA)  can be used for treatment of ankle osteoarthritis. IAD is suitable for early-stage ankle osteoarthritis but not for advanced nor late stages [4, 8]. In comparison, LTO is indicated for up to stage 3a (Tanaka classification for ankle osteoarthritis) but not for advanced or late stages 3b and 4 [13, 14]. TAA maintains ankle joint movement and is suited for advanced and late stages; it is not suited for patients where there is severe deformity associated with the distal tibial articular surface, and furthermore, sports and heavy manual work activities are limited after surgery [6, 7]. In contrast, AA [1, 2, 3] is a surgical technique for advanced and late stages of ankle osteoarthritis as it is possible to have high levels of pain-free function, but there is loss of ankle joint movement and a risk of arthrosis of adjacent joints in the future. Distraction arthroplasty is a method with a possibility of the joint cartilage repair but current results are mixed with reports of patients with better pain scores and some without any improvement .
In DTOO, the shape of the ankle joint surface is changed by cutting and tilting the tibial plafond without osteotomy of the fibula. The inclination of the distal tibial articular surface with respect to the tibial axis is altered and with associated improvement in ankle stability [9, 10]. The oblique osteotomy is dilated with a spreader until the lateral talar articular surface comes into contact with the medial articular surface of the lateral fibular malleolus; this is achieved whilst contact is maintained between the medial malleolar articular surface and the medial talar articular surface. Therefore, in DTOO, the ankle mortise congruency is restored such that medial and lateral articular gutters on either side of the talar body are symmetrical. This implies that the contact area of the talar articular surface is increased with the tibia and fibula by performing the DTOO; with the contact area increased, load pressure is dispersed across the ankle joint, and there is a decrease in the load pressure per unit area applied to the ankle joint. This degree of improved congruency between the articular surfaces of the talar dome and distal tibial plafond and that in the medial and lateral gutters of the ankle mortise improves ankle stability [9, 10].
The distal tibial oblique osteotomy (DTOO) is a procedure suited for the ankle osteoarthritis by improving the contact area of the ankle joint and decreasing the load pressure per unit area. This is accomplished with an improvement in ankle stability and a restoration of the hindfoot valgus. Clinical results confirm a reduction in ankle pain and an ability to perform hard manual work or return to sports activities.
Compliance with ethical standards
Conflict of interest
The authors declare no conflict of interest and no funds have been received in connection with this study.
All procedures performed were in accordance with the ethical standards of the institution and with the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards.
Informed consent was obtained from all individual participants included in the study.
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