Bradley M. Lamm, Ahmed Thabet, John E. Herzenberg, and Dror Paley
ANATOMY AND PATHOGENESIS
The midfoot extends from the midtarsal joint to the Lisfranc joint and connects the hindfoot and forefoot.2,3 Normal gait requires complex synergetic actions between the joints of the hindfoot and midfoot.6
Midfoot deformities can be either stiff or flexible and can present as uniplanar or multiplanar deformities.
Midfoot deformities have a severe impact on the pedal biomechanics by altering weight-bearing forces and pedal alignment.
PATIENT HISTORY AND PHYSICAL FINDINGS
Preoperative clinical examination and radiographs(FIG 1) are used to determine the degree and location of deformity.
Clinical examination is critical with midfoot deformities for assessment of the joint range of motion, flexibility, and the degree of rotation deformity (supination and pronation).
SURGICAL TREATMENT
The goal of surgical intervention is to restore pedal alignment, to allow proper transfer of weight from hindfoot to forefoot during gait, to decrease pain, and to re-establish functional gait without affecting adjacent joint motion.2
Conventional midfoot osteotomies are limited, as acute deformity correction can cause neurovascular compromise and requires extensive exposure, retained hardware can increase risk of infection, and wedge resection can sacrifice normal joints and alter anatomic realignment.5
In the literature, many types of osteotomies have been described for correction of midfoot deformities, each one designed to correct a specific deformity or condition.2,3,7,8
Cavus: Cole, Japas, and Akron osteotomies
Relapsed clubfoot and metatarsus adductus: medial opening cuneiform wedge and lateral closing cuboid wedge osteotomies
We present a percutaneous midfoot Gigli saw osteotomy technique for correction of uniplanar and multiplanar midfoot deformities.
This unique percutaneous saw technique was first described in 1894 by Italian obstetrician Leonard Gigli.
A Gigli saw is a twisted stainless steel cable that is a very effective cutting surface when used in a reciprocating fashion against bone.1
Our technique has several major advantages:
It is minimally invasive, which decreases the risk of soft tissue injury and infection and improves osseous healing by preserving the periosteum and soft tissues. It minimizes the soft tissue insult, which is essential for the multiply operated foot.
It is not limited by the magnitude of the deformity, spares joints and growth plates, and allows for ease of uniplanar or multiplanar deformity correction.
Gradual external fixation produces regenerated bone, which is preferred to bone resection. The bone resection can increase foot stiffness.
Gradual external fixation also allows for accurate anatomic realignment of the foot, which re-establishes normal ligament and muscle function.4,5
Preoperative Planning
Radiographic planning determines the center of rotation angulation (CORA) of the midfoot deformity.4
The level of the CORA, together with clinical examination and radiographic assessment to determine the degree and location of deformity, determines the correct osteotomy level.
Positioning
The patient is placed in a supine position on a radiolucent table.
FIG 1 • Weight-bearing AP radiographic view shows a midfoot adduction deformity (35 degrees) in an adult patient with fibular hemimelia. In addition, she also has a hallux abductovalgus deformity. (Copyright 2008, Rubin Institute for Advanced Orthopedics, Sinai Hospital of Baltimore.)
The leg is prepped just below a nonsterile thigh tourniquet, which allows for bending of the knee during surgery. The ability to flex the knee 90 degrees intraoperatively is advantageous in obtaining anteroposterior (AP) fluoroscopic imaging of the foot.
A hemisacral bump is placed to obtain a foot-forward position.
The patient is prepped and draped, and the tourniquet is elevated.
Approach
Various levels of midfoot osteotomies can be performed (talocalcaneal neck or cuboid-navicular or cuboid-cuneiform bones) based on preoperative planning.
The talocalcaneal neck osteotomy is used when the subtalar joint is stiff or fused.
When the subtalar joint is a mobile, the level of the midfoot osteotomy is across the cuboid and navicular or cuboid and cuneiform.4,5
TECHNIQUES
MIDFOOT OSTEOTOMY
The midfoot osteotomy is performed before external fixation application or screw insertion.
With the aid of fluoroscopy, the level of osteotomy is identified and marked (TECH FIG 1A).
A 1.8-mm Ilizarov wire is placed on the foot under fluoroscopic guidance, and a marking pen is used to mark the exact level of the osteotomy on both the AP and lateral views.
All midfoot osteotomies require four percutaneous transverse incisions.
The first incision is made transversely at the plantar lateral border of the foot, and subperiosteal dissection with a periosteal elevator is performed across the plantar vault of the foot. This subperiosteal dissection creates a subperiosteal tunnel that protects the tendons and neurovascular bundle along the plantar aspect of the foot.
The periosteal elevator is then maneuvered in a rocking motion against the bone and across the entire plantar arch to the plantar medial foot (TECH FIG 1B).
A second transverse incision is made where the skin is tented by the extension of the periosteal elevator, and the elevator is removed.
A no. 2 Ethibond suture is clasped with a curved tonsil hemostat and passed through the previously created subperiosteal tunnel from the lateral incision to the medial incision (TECH FIG 1C).
Once the suture is passed, the Gigli saw is tied to the suture and pulled from lateral to medial through in the same subperiosteal tunnel (TECH FIG 1D).
The position of the Gigli saw is checked by image intensifier to ensure that the level of osteotomy has been properly maintained.
Through the medial plantar incision, the periosteal elevator is passed across the dorsum of the foot subperiosteally below the tibialis anterior tendon so as to exit just lateral to this tendon.
The third transverse incision is made lateral to the tibialis anterior tendon, where the elevator tents the dorsal skin.
The curved tonsil is then passed subperiosteally from the third incision to the second incision to clasp the Ethibond suture, which is pulled with the Gigli saw through the third incision (TECH FIG 1E).
Again the elevator is extended from the third incision across the dorsum of the foot laterally and subperiosteally below the extensor tendons to exit at the level just dorsal to the cuboid and the first incision.
The fourth transverse incision is made where the elevator tents the lateral skin (TECH FIG 1F).
From the fourth to third incision, the curved tonsil grasps the suture attached to the Gigli saw and is pulled through the fourth incision.
TECH FIG 1 • Percutaneous Gigli saw osteotomy of the midfoot. A. There are three levels in the midfoot at which a Gigli saw is passed percutaneously: the talocalcaneal neck, the cuboid-navicular bones, and the cuboid-cuneiform bones. The illustration shows a cuboid-cuneiform level osteotomy. Four small incisions are used to pass the saw: one medial plantar, one lateral plantar, and two dorsal incisions. B.Because of the concavity of the transverse arch and the multiple bones present, the plantar periosteal elevation often weaves in and out of the subperiosteal space. C. A suture is passed from lateral to medial (the reverse can also be done). D. The Gigli saw is passed from lateral to medial under the foot. E. Through a third incision, which is made on the dorsomedial aspect of the foot, the suture and Gigli saw are passed to the dorsum of the foot. F. A fourth incision is made on the dorsolateral side, and the periosteum is elevated on the dorsum of the foot. G. The suture and Gigli saw are passed around the foot from plantar to dorsal, exiting on the dorsolateral side opposite the entrance site on the plantar lateral side. H. The bone is cut by the Gigli saw to the level of the cuboid. I. The lateral periosteal bridge is elevated and maintained to protect the skin crossing the Gigli saw. J. The cuboid bone is then cut, and the saw is cut and removed. (Copyright 2008, Rubin Institute for Advanced Orthopedics, Sinai Hospital of Baltimore.)
The Gigli saw is now circumferentially around the bones of the midfoot (TECH FIG 1G). Care must be taken during the passage of the Gigli saw to maintain the correct level of the planned osteotomy.
The two Gigli saw handles are now attached, and, using a reciprocating motion, the midfoot is cut from medial to lateral (TECH FIG 1H). The Gigli saw handles may need to be crossed while making the reciprocating cut to avoid lateral soft tissue injury.
To avoid injury to the peroneal tendons and lateral skin, cutting is stopped just before the lateral bone is exited. A periosteal elevator is placed between the fourth and first incisions crossing the Gigli saw, and then the cut is continued (TECH FIG 1I).
When the cut is complete, the elevator will block further progression of the saw.
After completion of the cut, the osteotomy is checked with the image intensifier.
The Gigli saw is then cut and withdrawn from the foot (TECH FIG 1J).
The tourniquet is deflated, and the incisions are closed.4,5
EXTERNAL FIXATION APPLICATION
External fixation allows for gradual correction of deformity and lengthening, which can be accomplished by the Ilizarov external fixator or the Taylor spatial frame.
Stirrup wires placed just proximal and distal to the midfoot osteotomy are used.
As a rule, forces tend to take the passage of least resistance, which in the foot are the joints and growth plates, so it is essential to add these two stirrup wires adjacent to each side of the osteotomy. Each wire is carefully inserted on either side of the osteotomy under fluoroscopic guidance (TECH FIG 2).
Then proceed to build the frame according to the deformity, fixing the tibia, talus, calcaneus, and proximal midfoot with the proximal fixation block and the distal midfoot and forefoot with the distal fixation block.
Finally, the stirrup wires are attached to the frame distally and proximally as appropriate.
Stirrup wires do not need to be tensioned.
Olive stirrup wires are used to limit osseous transverse plane deviation during gradual external fixation correction.
TECH FIG 2 • Opening medial wedge and normotrophic regenerate bone formation during distraction treatment of the patient in Figure 1 with the Taylor spatial frame. The stirrup wires are adjacent to the percutaneous midfoot Gigli saw osteotomy. A lateral olive wire is used to resist lateral forefoot translation during the distraction treatment. The hallux abductovalgus was acutely corrected. (Copyright 2008, Rubin Institute for Advanced Orthopedics, Sinai Hospital of Baltimore.)
ACUTE CORRECTION CONSIDERATIONS
When performing a midfoot derotation (supination and pronation) correction, the medial muscle and fascia (abductor hallucis muscle) must be released from the osseous midfoot attachments.
Wedge resection can be performed by using two separate Gigli saws passed simultaneously.
The distal cut is performed first, and the proximal cut is performed second.
Then the two medial percutaneous incisions are connected to remove the osseous wedge.
Screw fixation, tension band wire, plates, staples, or static external fixation can also be used for fixation.
GRADUAL DISTRACTION THEN ACUTE CORRECTION
When using the Ilivarov external fixator for small feet
(pediatric patients), a valuable technique is gradual distraction then acute correction.
Initial foot distraction for 2 or 3 weeks with external fixation is performed to disengage the bone segments and distract the soft tissue envelope.
Then, under general anesthesia, the forefoot fixation is disconnected from the hindfoot frame and acute manipulation (derotation, angulation, or translation) of the forefoot is accomplished to achieve the correct position.
The forefoot and hindfoot fixation is reattached in the corrected position and maintained until bone consolidation.
This technique reduces the time the external fixator is needed.
OUTCOMES AND COMPLICATIONS
We reviewed our series of midfoot deformities corrected with the percutaneous Gigli saw midfoot osteotomy and external fixation.
These patients achieved our goal of a plantigrade foot position with improvement in gait (FIG 2).
Minor complications included digital flexion contractures, which were treated by flexor tenotomy, and superficial pin tract infections, which were treated with oral antibiotics.
Major complications included premature consolidation, which required reosteotomy, and a tarsal tunnel syndrome, which developed during treatment and required surgical decompression.
We also have performed a series of cadaveric midfoot Gigli saw osteotomies under fluoroscopy to determine the safety of this osteotomy.
After completion of the osteotomy, the dissection revealed no neurovascular or tendon or muscle damage.
ACKNOWLEDGMENT
The authors thank Joy Marlowe, MA, for her excellent illustrative artwork and Alvien Lee for his photographic expertise.
FIG 2 • Final weight-bearing AP radiographic view of the patient in Figure 1 and Techniques Figure 2 shows full correction of the adduction deformity (straight lateral border of the foot). (Copyright 2008, Rubin Institute of Advanced Orthopedics, Sinai Hospital of Baltimore.)
REFERENCES
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· Conti SF, Kirchner JS, Van Sickle D. Midfoot osteotomies. Foot Ankle Clin 2001;6.
· Dehne R. Osteotomy of the pediatric foot. Foot Ankle Clin 2001;6.
· Paley D. Principles of Deformity Correction. New York: Springer, 2005.
· Paley D. The correction of complex foot deformity using Ilizarov's distraction osteotomies. Clin Orthop Relat Res 1993;293:97–111.
· Perry J. Gait analysis: Normal and Pathological Function. Thorofare, NJ: Slack, 1992.
· Statler TK, Tullis BL. Pes cavus. J Am Podiatr Med Assoc 2005;95: 42–52.
· Wilcox PG, Weiner DS. Akron mid tarsal dome osteotomy in the treatment of rigid pes cavus: a preliminary review. J Pediatr Orthop 1985;5: 333–338.