Easley_CH066.indd

C H A P T E R 66

Supramalleolar Osteotomy with Internal Fixation: Perspective 2

Markus Knupp and Beat Hintermann

DEFINITION

IMAGING AND OTHER DIAGNOSTIC STUDIES ■ Weight-bearing radiographs of the entire foot, the ankle, the tibial shaft (full-length radiographs), and the Saltzman hind- foot view are necessary to assess the nature and location of the deformity. Unless deformity at the level of the knee joint or the femur can be excluded clinically, whole lower limb radiographs are obtained. ■ Next to conventional radiography, computed tomography (CT) and magnetic resonance imaging are not routinely required. However, they could be of value when assessing rotational malalignment, osteochondral lesions, and pero- neal tendon disorders or evaluating the aspect of the liga- ment insufficiency. ■ Combined single-photon emission and conventional com- puted tomography (SPECT-CT) has been found to be a valu- able tool for the assessment and staging of osteoarthritis in asymmetric osteoarthritis of the ankle joint.

■ A supramalleolar osteotomy is an osteotomy at the level of the distal tibia with or without osteotomy of the fibula. ■ The correction is intended to normalize altered load distribu- tion across the joint and may be indicated in cases of asym- metric osteoarthritis, malunited fractures of the distal tibia, osteochondral lesions, and recurrent instability with deformity.

ANATOMY

■ Trauma and neurologic disorders leading to varus or valgus alignment around the ankle joint predispose to asymmetric joint load. ■ This causes cartilage wear, in particular in the presence of associated ligamentous instability and muscular imbalance.

PATHOGENESIS

■ Various conditions such as neurologic disorders, congenital and acquired foot deformities, posttraumatic malunions, and instability may be associated with malalignment of the ankle joint complex.

DIFFERENTIAL DIAGNOSIS

■ Symmetric or end-stage osteoarthritis ■ Muscular imbalance (eg, in neurologic disease) ■ Forefoot-driven hindfoot deformities

NATURAL HISTORY

■ Malalignment of the hindfoot may result from bony defor- mities above or below the level of the ankle joint. ■ Ligamentous instability or muscular imbalance of the ankle or the adjacent joints may be a contributing or even an ini- tiating factor in the natural history of malalignment around the ankle joint.

NONOPERATIVE MANAGEMENT

■ Asymptomatic, moderate malalignment usually is treated conservatively. ■ Malalignment that is due to forces from the neighboring structures, such as plantarflexed first metatarsal or unbal- anced muscle forces can be treated with physiotherapy or shoe wear modifications. Deforming forces, such as forefoot abnormalities or muscular imbalance, may require surgical procedures other than supramalleolar osteotomies. ■ Recommendations whether surgical or conservative therapy should be aimed for in asymptomatic but severe malaligned hindfeet are controversial. Because the deformity is likely to lead to excessive wear, surgery should be considered. ■ An alternative surgical treatment is the calcaneal displace- ment osteotomy (medial or lateral). Commonly, however, correction of malalignment is best performed at the level of the deformity.

PATIENT HISTORY AND PHYSICAL FINDINGS

■ A thorough medical history should be taken.

■ Systemic diseases such as diabetes mellitus (Charcot ar- thropathy), rheumatoid arthritis, and neurovascular dis- orders need to be assessed carefully. ■ Tobacco use should be considered a relative contraindica- tion to supramalleolar osteotomy. ■ Disorders that alter the bone quality and healing ca- pacity (medication, osteoporosis, age) should be assessed carefully. ■ Physical examination should include the following: ■ Drawer test and talar tilt test to assess ankle joint stability ■ Assessment of the inversion and eversion force to exclude peroneal tendon insufficiency

SURGICAL MANAGEMENT

■ Supramalleolar osteotomies are divided into opening/closing wedge osteotomies and dome-shaped osteotomies. ■ Ideally, the correction is carried out at the center of rotation of angulation (CORA), preferably in the metaphyseal bone.

■ Subtalar range of motion

■ Coleman block test to exclude a forefoot driven hindfoot varus

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■ Deformities which cannot be corrected at the CORA as well as for large corrections, a dome-shaped osteotomy should be considered in order to avoid excessive translation of the distal fragment. ■ Congruent joints should be considered for dome-shaped osteotomies; incongruent joints usually qualify for wedge osteotomies. ■ In case of a wedge osteotomy: ■ Valgus deformities are usually addressed with a medial closing wedge osteotomy. ■ Varus malalignment is corrected with a medial opening wedge osteotomy or a lateral closing wedge osteotomy. ■ For all corrections of the distal tibia, a correction of the length and position of the fibula must be considered in order to preserve ankle joint congruency. ■ The most important aspect of the preoperative planning is the assessment of the origin of the deformity. Different enti- ties need to be distinguished, and it is mandatory to separate the isolated frontal plane deformity of the hindfoot from complex deformities involving the transverse, sagittal, and coronal planes with or without muscular dysfunction and imbalanced ligamentous structures. ■ Distinction of congruent and incongruent joints ( FIG 1 ) is helpful in determining the type of osteotomy performed (tibia only vs. tibia and fibula; wedge osteotomy vs. dome- shaped osteotomy).

■ To determine the size of the wedge that should be added or removed to restore anatomic alignment in the ankle, the tibiotalar angle should be measured. ■ On a standard anteroposterior image of the ankle joint, the tibiotalar angle is the angle between the tibial axis and the tibial joint surface. The wedge to be corrected can be measured out of the radiographs or calculated with the mathematical formula tan H/W, where is the angle to be corrected, H is the wedge height in millimeters, and W is the tibial width ( FIG 2 ). ■ An overcorrection of 3 to 5 degrees is recommended by most authors for asymmetric osteoarthritis. ■ Additional deviation (eg, rotational or translational defor- mities) must be taken into consideration during the planning of the osteotomy.

Positioning

Preoperative Planning

■ Positioning of the patient depends on the surgical approach:

■ Anterior approach: supine position

■ Lateral approach: lateral decubitus position or supine with a sandbag under the buttock of the affected limb ■ Medial approach: supine, ipsilateral knee in slight flexion with a sandbag under the calf

Approach

■ An anterior, lateral, or medial approach can be chosen to correct the deformity. The choice depends on the nature of the defor- mity, the local soft tissue conditions, and previous approaches.

FIG 1 ● An illustration of a congruent ( left ) and an incongruent ( right ) joint. In congruent joints, the joint space between tibia and talus is paral- lel despite the distal tibial joint surface angle being in a varus or valgus deviation. In incongruent joints, the talus is tilted within the ankle mortise.

FIG 2 ● Planning of the correction: measuring the deformity and plan- ning the wedge size that should be inserted ( lower line of the white triangle indicating the level of the osteotomy).

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T E C H N I Q U E S

■ Lateral Closing Wedge Osteotomy to Correct Valgus Exposure ■ After exsanguination of the leg, a pneumatic tourniquet is in- flated on the thigh. ■ A 10-cm longitudinal, slightly curved incision is made along the anterior margin of the distal fibula. If the incision needs to be extended distally, it is curved ventrally to end just distal to and anterior of the lateral malleolus ( TECH FIG 1 ). ■ The fibula and the tibia are then exposed laterally. To avoid de- vascularization of the bone, stripping of the periosteum is not performed. ■ At the distal end of the incision, the anterior syndesmosis is exposed. ■ The lateral branch of the sural nerve and the short saphenous vein run dorsal to the line of incision and are usually not seen during this procedure. However, extended proximal dissec- tion may require identification, exposure, and protection of the branches of the superficial peroneal nerve. Cauterization of some of the branches of the peroneal artery, which lie deep to the medial surface of the distal fibula, may be necessary. Fibular Osteotomy ■ In most cases in which a varus deformity is addressed with a lat- eral closing wedge osteotomy, the fibula needs to be shortened to preserve the congruency in the ankle joint. The shortening can be done by simple bone block removal or a Z-shaped os- teotomy. Alternatively, an oblique osteotomy (distal anterior to proximal posterior) can be used, although the Z-shaped fibular osteotomy confers greater control of rotation and primary stabil- ity compared to a block resection for fibular shortening. ■ The length of the Z-shaped fibular osteotomy is approximately 2 to 3 cm, starting distally at the level of the anterior syndesmosis. ■ Kirschner wires (K-wires) can be placed as a reference at the level of the transverse cuts to confirm the location of the oste- otomy fluoroscopically. ■ The osteotomy is then carried out with an oscillating saw. ■ After the fibula has been mobilized, bone blocks are resected on both ends of the Z based on the amount of the planned shortening ( TECH FIG 2 ).

■ To avoid interference from the dense syndesmotic ligaments when performing the Z-osteotomy, we routinely direct the proxi- mal transverse cut anteriorly and the distal cut (which typically sits at the syndesmosis) posteriorly. Lateral Closing Wedge Tibial Osteotomy ■ To define the desired osteotomy, two K-wires are drilled through the tibia, with the tips converging at the medial cortex, making sure that the angle between the K-wires corresponds with the preoperative planning (see TECH FIG 2 ). ■ Unless the deformity is located proximal to the supramal- leolar area, the wires are directed from proximal to the anterior syndesmosis to the medial physeal scar ( TECH FIG 3A ). ■ After fluoroscopic verification of the location of the wires ( TECH FIG 3B ), the periosteum is incised only at the level of the planned osteotomy and carefully mobilized with a scalpel or periosteal elevator. ■ The osteotomy is then performed using an oscillating saw cooled with saline or water irrigation to limit thermal injury to bone. ■ Placing the K-wires accurately avoids cutting through the medial cortex; ideally, the medial cortex should serve as a hinge. ■ Correction of the deformity must be performed at the CORA of the deformity to avoid relative translational malpositioning of the distal (ankle) and proximal (tibial shaft) fragments. ■ The gap is then closed and the osteotomy is secured with a plate. We prefer locking plates that afford optimal primary stability; however, it is imperative that the osteotomy is com- pletely closed when employing locking plate technology ( TECH FIG 3C,D ).

TECH FIG 2 ● Drawing illustrating the Z-shaped osteotomy to shorten the fibula.

TECH FIG 1 ● Lateral approach to the distal fibula and tibia.

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T E C H N I Q U E S

B

C

D

TECH FIG 3 ● A. Placement of the K-wires for guidance of the osteotomy. B. Intraoperative ra- diograph showing the guidewires for the tibial osteotomy after the Z-shaped fibula osteotomy. Distal tibia/fibula before ( C ) and after ( D ) closure of the osteotomy. Note the shortening of the fibula.

A

■ Prior to locking the plate both proximal and distal to the oste- otomy, we use a tensioning device to optimally compress the osteotomy. ■ We routinely close the periosteum over the osteotomy with 2-0 absorbable sutures. Optimizing Joint Congruity and Securing the Fibula ■ Fluoroscopically, optimal tibiotalar joint congruity and fibular os- teotomy reduction are determined. ■ Once the joint is congruent, the fibula is secured with screws (in the longitudinal limb of the Z-osteotomy) or a one-third tu- bular plate ( TECH FIG 4 ). ■ The subcutaneous tissues and the skin are closed with inter- rupted sutures. ■ Medial Open Wedge Osteotomy for Correction of Varus Deformity Exposure ■ The limb is exsanguinated and the thigh tourniquet is inflated. ■ The anterior incision is made anteriorly over the distal tibia and ankle, immediately lateral to the tibial crest. The superficial peroneal nerve crosses the distal aspect of the incision and must be protected.

TECH FIG 4 ● Fixation of the fibula with a plate.

■ The extensor retinaculum is then divided longitudinally to ex- pose the extensor tendons. The approach uses the interval be- tween the tibialis anterior and extensor hallucis longus tendons. ■ A longitudinal incision in the extensor retinaculum is made be- tween the anterior tibial tendon and the extensor hallucis longus tendon, starting 10 cm proximal to the joint, about midway be- tween the malleoli ( TECH FIG 5 ). ■ The anterior tibial tendon is retracted medially and the ten- don of the extensor hallucis longus is retracted laterally, if possible, without opening the tendon sheaths.

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T E C H N I Q U E S

of the osteotomy, periosteal stripping should be limited to the osteotomy site. ■ The osteotomy is carried out as described in the section entitled Tibial Osteotomy. Medial Approach ■ The patient is positioned supine on the operating table; a bump placed under the contralateral hip may improve exposure. ■ The limb is exsanguinated and the tourniquet is inflated. ■ The great saphenous vein and the saphenous nerve usually lie anterior to the incision. A 10-cm longitudinal incision is made beginning over the medial malleolus and extending proximally over the distal tibia ( TECH FIG 6A ). ■ The skin flaps are mobilized, with care taken not to damage the neurovascular bundle, which runs along the anterior border of the medial malleolus ( TECH FIG 6B ). ■ The posterior tibial tendon, which lies immediately on the pos- terior aspect of the medial malleolus, must be identified and retracted posteriorly. It needs to be exposed, its sheath incised, and the tendon retracted posteriorly to visualize the dorsal sur- face of the distal tibia. Tibial Osteotomy ■ The tibia is exposed with minimal periosteal stripping ( TECH FIG 7A ). ■ The plane of the osteotomy is determined under image inten- sification, and a K-wire is placed from the medial cortex into the physeal scar or, in case of a malunion, at the apex of the deformation ( TECH FIG 7B ). ■ The periosteum is then incised at the level of the osteotomy and elevated off the bone using a scalpel or a periosteal elevator. The osteotomy must be planned carefully because placing it

TECH FIG 5 ● Anterior approach to the distal tibia with the interval between the extensor hallucis longus and the anterior tibial tendon and the neurovascular bundle lying lateral to it.

■ The deep neurovascular bundle (anterior tibial artery and deep peroneal nerve), located in the lateral aspect of the approach, must be identified and protected. ■ The ankle joint is covered by an extensive fat pad that contains a venous plexus and requires partial cauterization. ■ If tibiotalar joint débridement or exostectomy is required, we make an anterior capsulotomy at this time. If only a supramalleolar oste- otomy is planned, however, there is no need to expose the joint. ■ With all soft tissues and neurovascular structures protected, the anterior surface of the tibia can be exposed. To promote healing

A

B

TECH FIG 6 ● A,B. Medial approach to the distal tibia.

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T E C H N I Q U E S

A

B

C

D

TECH FIG 7 ● A. Intraoperative picture of the K-wire placement. B. Incision and careful stripping of the periosteum. C. Osteotomy of the tibia with an oscillating saw. D. Drawing of the saw cut for a medial opening wedge osteotomy. E. Fill the gap. F. Plate fixation of the osteotomy. F E

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T E C H N I Q U E S

inaccurately may lead to relative translation of the distal and proximal fragments, resulting in malalignment of the ankle joint under the tibial shaft axis. ■ We recommend using a wide saw blade to create a congruent osteotomy ( TECH FIG 7C,D ). ■ Alternatively, a chisel or osteotome may be used instead of the oscillating saw to limit thermal injury to bone. ■ The correction is based on preoperative planning. ■ The gap can be filled with allograft (we use Tutoplast Spongiosa, Tutogen Medical GmbH, Neunkirchen, Germany) or autograft iliac crest bone ( TECH FIG 7E ).

■ We typically secure the osteotomy with a medial locking plate, but plates with an integrated spacer (eg, Puddu plate, Arthrex Inc., Naples, FL) can be used instead ( TECH FIG 7F ). ■ Fixation of the osteotomy is as described earlier in the section entitled Lateral Closing Wedge Osteotomy to Correct Valgus. ■ The tendon sheath of the posterior tibial tendon is reapproxi- mated with 2-0 absorbable sutures and the subcutaneous tis- sues and the skin are closed with interrupted sutures. Do not overtighten the posterior tibial tendon sheath because it may create stenosing flexor tenosynovitis. ■ Case results are shown in TECH FIG 8 .

TECH FIG 8 ● Pre- and postoperative radiographs (weight-bearing anteroposterior, lateral, and Saltzman views, respectively) of a 62-year-old male patient with varus os- teoarthritis of his ankle joint. The postoperative images are made 1 year after a medial opening wedge osteotomy.

■ Medial Closing Wedge Osteotomy for Correcting Valgus Malalignment ■ The technique essentially is the same as for the opening wedge osteotomy described in the previous section with removal of a bone wedge.

■ K-wire placement is done according to the planned correction ( TECH FIG 9A ). ■ The bone wedge is then removed ( TECH FIG 9B ) and the cor- rection secured with a medial plate. ■ A clinical example is shown in TECH FIG 10 .

TECH FIG 9 ● A. K-wire placement for a medial closing wedge osteotomy. B. Wedge removal in a medial closing osteotomy. A B

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T E C H N I Q U E S

TECH FIG 10 ● Pre- and postoperative radiographs (weight-bearing anteroposterior, lateral, and Saltzman views, respectively) of a 58-year-old male patient with valgus os- teoarthritis of his ankle joint. The postoperative images are made 1 year after a medial closing wedge osteotomy.

■ Dome-Shaped Osteotomy ■ An anterior approach is used. ■ The level of the osteotomy usually lies at the metaphyseal level, above the tibiofibular syndesmosis. ■ A marking pen can be used to mark the osteotomy of the tibia and the planned angular correction.

■ Multiple 2-mm drill holes along the osteotomy line are made ( TECH FIG 11A ). The osteotomy is then completed with a 5-mm chisel ( TECH FIG 11B ). ■ Prior to mobilization of the osteotomy, the original position of the distal fragment in relation to the proximal fragment is marked on the anterior surface of the tibia (use a marking pen or the electrocautery to mark the bone) ( TECH FIG 11C ).

A

B TECH FIG 11 ● A. Intraoperative image showing the marking of the center of rotation (K-wire) and the drill holes along the osteotomy line. B. Image after completion of the osteotomy with a chisel. (continued)

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T E C H N I Q U E S

TECH FIG 11 ● (continued) C. Image after correction of the deformity. Note the electrocautery markings on the tibial cortex ( asterisks ) and the 2.5-mm K-wire in the medial malleolus ( arrow ) which was used as a joystick to correct the deformity and then for preliminary fixation of the correction. D. Preoperative ( left ) and postoperative radiographs of a 46-year-old patient with congruent varus arthritis of his ankle joint. The correction was fixed with a T-shaped plate for the tibia and a third tubular plate for the fibula. C D

■ The fibula is exposed through a separate lateral incision and then osteotomized as described in the section Fibular Osteotomy. ■ The osteotomy is mobilized, the deformity corrected as preop- eratively planned, and a 2.5-mm K-wire introduced from the medial malleolus to preliminarily secure the correction.

■ The correction of the tibia is secured with one T-shaped plate or two straight (one medial and one lateral plate) plates with interlocking screws. ■ The length and position of the fibula is then adjusted under fluoroscopic control and the fibula secured with an additional plate or with two screws ( TECH FIG 11D ).

PEARLS AND PITFALLS

Laceration of the posterior tibial tendon

■ For lateral osteotomies and dome-shaped osteotomies in posttraumatic cases with extensive scarring on the posteromedial aspect of the ankle, it may be necessary to expose the tendon through a minimal incision to protect it. ■ This loss of the hinge mechanism of the far cortex introduces the risk for rotational or translational malpositioning and postoperative displacement of the osteotomy. ■ Consider additional fixation with a second plate in a second plane. ■ In select cases, the syndesmosis needs to be mobilized to maintain congruent tibiotalar joint alignment. We do this by releasing the anterior syndesmotic ligaments from the anterolateral distal tibia, imme- diately proximal to the ankle joint. The ligaments are released by removing Chaput tubercle from the anterolateral distal tibia using an osteotome or chisel. Once the osteotomy is secured and the fibula is reduced to the desired position to create a congruent ankle joint, the syndesmosis is stabilized at its new resting tension by reattaching Chaput tubercle with a screw and a washer or with transosseous sutures. ■ The risk can be lowered by using implants that provide angular stability and by leaving a hinge of bone and periosteum at the far cortex when performing the tibial osteotomy to achieve a controlled correc- tion in the desired plane.

Accidental cutting through the entire tibia in wedge osteotomies

Mobilization of the syndesmosis

Loss of reduction of the osteotomy

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POSTOPERATIVE CARE

■ Intraoperative complications include nerve or tendon injury. We ensure that all adjacent neurovascular structures and tendons are identified and protected. SUGGESTED READINGS 1. Knupp M, Pagenstert G, Valderrabano V, et al. Osteotomies in varus malalignment of the ankle [in German]. Oper Orthop Traumatol 2008;20:262–273. 2. Knupp M, Stufkens SA, Bolliger L, et al. Classification and treat- ment of supramalleolar deformities. Foot Ankle Int 2011;32: 1023–1031. 3. Knupp M, Stufkens SA, Pagenstert GI, et al. Supramalleolar osteot- omy for tibiotalar varus malalignment. Tech Foot Ankle Surg 2009;8: 17–23. 4. Knupp M, Stufkens SA, van Bergen CJ, et al. Effect of supramalleolar varus and valgus deformities on the tibiotalar joint: a cadaveric study. Foot Ankle Int 2011;32(6):609–615. 5. Myerson MS, Zide JR. Management of varus ankle osteoarthri- tis with joint-preserving osteotomy. Foot Ankle Clin 2013;18(3): 471–480. 6. Pagenstert GI, Hintermann B, Barg A, et al. Realignment surgery as alternative treatment of varus and valgus ankle osteoarthritis. Clin Orthop Relat Res 2007;462:156–168. 7. Pagenstert GI, Knupp M, Valderrabano V, et al. Realignment surgery for valgus ankle osteoarthritis. Oper Orthop Traumatol 2009;21: 77–87. 8. Stamatis ED, Cooper PS, Myerson MS. Supramalleolar osteotomy for the treatment of distal tibial angular deformities and arthritis of the ankle joint. Foot Ankle Int 2003;24:754–764. 9. Stufkens SA, van Bergen CJ, Blankevoort L, et al. The role of the fib- ula in varus and valgus deformity of the tibia: a biomechanical study. J Bone Joint Surg Br 2011;93(9):1232–1239. 10. Takakura Y, Takaoka T, Tanaka Y, et al. Results of opening-wedge osteotomy for the treatment of a post-traumatic varus deformity of the ankle. J Bone Joint Surg Am 1998;80(2):213–218.

■ The leg is elevated in the immediate postoperative period. ■ A compressive dressing and splint are maintained for 2 days to diminish swelling. ■ A short-leg non–weight-bearing cast is used for 6 to 8 weeks. ■ If radiologic evidence of consolidation is present after 6 weeks, partial weight bearing is allowed for 2 weeks, after which the patient advances gradually to full weight bearing. ■ A rehabilitation program for strengthening, gait training, and range of motion is prescribed 8 weeks after surgery, with gradual return to full activities as tolerated. ■ We have been observing our first series of 94 patients with a varus or valgus deformity of the ankle joint for 43 months (range of 12 to 126 months). ■ At the radiographic assessment after 12 months, all oste- otomies showed complete consolidation. Pain reduction was found in all patients, which is similar to earlier reports. Improved radiographic osteoarthritis scores were noted in 75% of the patients. Additionally, patients exhibited a trend toward normalization of gait and function. ■ Apart from perioperative complications such as delayed wound healing problems or infection, postoperative con- cerns include delayed union or nonunion of the osteotomy. ■ Another potential complication is malunion, resulting from inaccurate alignment of the osteotomy at the time of surgery or postoperative loss of position.

OUTCOMES

COMPLICATIONS