Preparation
The procedure is performed with use of regional anesthesia (an ankle block
with 1% lidocaine and 0.5% bupivacaine). The use of a fluoroscope to monitor
alignment and fixation is recommended. The operation should be done without a
tourniquet so that bone vitality can be assessed during preparation.
Skin Incision and Approach
A standard dorsal approach is recommended regardless of existing scars. The
skin incision starts approximately 4 cm proximal to the metatarsophalangeal
joint and extends to the interphalangeal joint.
The tendon of the extensor hallucis longus is usually dissected out and is
cut in a z-shaped fashion to facilitate exposure of the metatarsophalangeal
joint. In cases of a cock-up great-toe deformity, it will be necessary to
lengthen this tendon anyway.
The joint capsule and the soft-tissue coverage of the metatarsal and
phalanx are incised longitudinally straight down to the bone and then are
opened as an envelope. A subperiosteal preparation is mandatory to ensure
sufficient release of the lateral soft tissues and adhesions. Only the plantar
aspect is left intact, to preserve the blood supply to both bones. After
inspection of the articular surfaces, osteophytes and debris are removed with
a rongeur. Special attention should be paid to the plantar aspect of the joint
to avoid laceration of the flexor hallucis longus tendon.
Preparation of the Joint Surfaces
In the next step, any remaining cartilage and sclerotic bone is removed to
create bleeding cancellous bone surfaces. Compared with flat cuts or a conical
preparation, a ball-and-socket preparation has the advantage of minimizing
bone loss, and it creates the ability to alter the position of the toe after
the preparation has been performed. This ball-and-socket preparation can be
carried out with a small spherical reamer, chisels, or a rongeur. The
potential disadvantage of this method, especially when it is done by hand, is
the inaccuracy in attaining a spherical surface, resulting in a reduced area
of bone contact. Special power-driven reamers (Hallu-Reamer; Newdeal, Plano,
Texas) can facilitate this step (Figs. 2-A
and 2-B).
CRITICAL CONCEPTSINDICATIONS:Revision SurgeryInstability of the metatarsophalangeal joint (cock-up deformity, floppy
toe)Recurrent valgus deformityPrimary SurgerySevere arthritis of the metatarsophalangeal jointCONTRAINDICATIONS:InfectionNeurological diseaseSevere vascular diseasePITFALLS:Despite the presence of other scars, a dorsal approach should be used. This
allows one to expose the metatarsophalangeal joint adequately and to avoid
injury to the medial dorsal cutaneous nerve, which may be difficult to
identify in the scar tissue.Positioning is the most important factor. A slight deviation from the
correct position in any of the three planes can lead to symptoms requiring
additional revision. The anatomical position of the foot during surgery
differs from the situation during normal weight-bearing, especially with
regard to the intermetatarsal angle and the first metatarsal inclination
angle. We recommend that, to best simulate the situation during gait, the
surgeon press the cover of an instrument tray against the sole of the foot
very firmly.In cases of severe metatarsus primus varus, a metatarsal osteotomy should
be considered. While some reduction of the first-second intermetatarsal angle
by the arthrodesis alone has been
reported2, the exact
amount and therefore the final result cannot be predicted. In our series, we
did not observe any reduction in the intermetatarsal angle.In cases of excessive shortening of the first ray, a bone-block
interposition arthrodesis may be necessary, although it is associated with
increased nonunion rates and wound
complications3. In
such cases, we use an autogenous tricortical graft from the iliac crest, which
is prepared with the spherical reamer on both ends. The two resulting
cup-shaped surfaces are inserted between the metatarsal and the phalanx, which
both have been prepared as described above. An anatomically preshaped plate
(Hallu-Plate; Newdeal) is used for fixation (Figs.
5-A,
5-B, and 5-C). If additional
stability is required, a 3.0-mm cancellous screw can be inserted.AUTHOR UPDATE:There have been no major changes in the procedure, except that a different
type of fixation is used in special cases. If the amount of residual bone does
not allow the insertion of crossed screws, or in patients treated with
bone-block interposition arthrodesis, definitive alignment is maintained with
an anatomically preshaped plate and screws (Hallu-Plate; Newdeal).
CRITICAL CONCEPTS
INDICATIONS:
Revision Surgery
Instability of the metatarsophalangeal joint (cock-up deformity, floppy
toe)Recurrent valgus deformity
Instability of the metatarsophalangeal joint (cock-up deformity, floppy
toe)
Recurrent valgus deformity
Primary Surgery
Severe arthritis of the metatarsophalangeal joint
Severe arthritis of the metatarsophalangeal joint
CONTRAINDICATIONS:
InfectionNeurological diseaseSevere vascular disease
Infection
Neurological disease
Severe vascular disease
PITFALLS:
Despite the presence of other scars, a dorsal approach should be used. This
allows one to expose the metatarsophalangeal joint adequately and to avoid
injury to the medial dorsal cutaneous nerve, which may be difficult to
identify in the scar tissue.Positioning is the most important factor. A slight deviation from the
correct position in any of the three planes can lead to symptoms requiring
additional revision. The anatomical position of the foot during surgery
differs from the situation during normal weight-bearing, especially with
regard to the intermetatarsal angle and the first metatarsal inclination
angle. We recommend that, to best simulate the situation during gait, the
surgeon press the cover of an instrument tray against the sole of the foot
very firmly.In cases of severe metatarsus primus varus, a metatarsal osteotomy should
be considered. While some reduction of the first-second intermetatarsal angle
by the arthrodesis alone has been
reported2, the exact
amount and therefore the final result cannot be predicted. In our series, we
did not observe any reduction in the intermetatarsal angle.In cases of excessive shortening of the first ray, a bone-block
interposition arthrodesis may be necessary, although it is associated with
increased nonunion rates and wound
complications3. In
such cases, we use an autogenous tricortical graft from the iliac crest, which
is prepared with the spherical reamer on both ends. The two resulting
cup-shaped surfaces are inserted between the metatarsal and the phalanx, which
both have been prepared as described above. An anatomically preshaped plate
(Hallu-Plate; Newdeal) is used for fixation (Figs.
5-A,
5-B, and 5-C). If additional
stability is required, a 3.0-mm cancellous screw can be inserted.
Despite the presence of other scars, a dorsal approach should be used. This
allows one to expose the metatarsophalangeal joint adequately and to avoid
injury to the medial dorsal cutaneous nerve, which may be difficult to
identify in the scar tissue.
Positioning is the most important factor. A slight deviation from the
correct position in any of the three planes can lead to symptoms requiring
additional revision. The anatomical position of the foot during surgery
differs from the situation during normal weight-bearing, especially with
regard to the intermetatarsal angle and the first metatarsal inclination
angle. We recommend that, to best simulate the situation during gait, the
surgeon press the cover of an instrument tray against the sole of the foot
very firmly.
In cases of severe metatarsus primus varus, a metatarsal osteotomy should
be considered. While some reduction of the first-second intermetatarsal angle
by the arthrodesis alone has been
reported2, the exact
amount and therefore the final result cannot be predicted. In our series, we
did not observe any reduction in the intermetatarsal angle.
In cases of excessive shortening of the first ray, a bone-block
interposition arthrodesis may be necessary, although it is associated with
increased nonunion rates and wound
complications3. In
such cases, we use an autogenous tricortical graft from the iliac crest, which
is prepared with the spherical reamer on both ends. The two resulting
cup-shaped surfaces are inserted between the metatarsal and the phalanx, which
both have been prepared as described above. An anatomically preshaped plate
(Hallu-Plate; Newdeal) is used for fixation (Figs.
5-A,
5-B, and 5-C). If additional
stability is required, a 3.0-mm cancellous screw can be inserted.
AUTHOR UPDATE:
There have been no major changes in the procedure, except that a different
type of fixation is used in special cases. If the amount of residual bone does
not allow the insertion of crossed screws, or in patients treated with
bone-block interposition arthrodesis, definitive alignment is maintained with
an anatomically preshaped plate and screws (Hallu-Plate; Newdeal).
To expose the phalangeal joint surface, the toe is brought into maximum
plantar flexion. A 1.6-mm Kirschner wire is placed into the center of the
phalanx as a guide for the reamer set. An adequately sized convex reamer is
then used to remove the sclerotic bone down to cancellous bleeding bone. The
preparation of the surface of the metatarsal head follows, performed in the
same manner as the concave counterpart.
Position
The position of the fusion is crucial. A hallux valgus angle of 15° is
recommended, but the correct position has to be determined for the individual
patient. Both impingement on the second toe (caused by excessive abduction)
and irritation of the medial aspect of the hallux by the shoe (caused by
insufficient abduction) must be avoided. Positioning in the sagittal plane can
be referenced to the first metatarsal or the plantar plane of the foot (Figs.
3-A, 3-B,
3-C, 3-D). The correct position
is achieved when the tip of the toe is able to exert pressure on the ground
while the patient is standing. Insufficient dorsal extension must be avoided
to prevent overloading of the toe and the interphalangeal joint during
walking. As it is difficult to simulate the weight-bearing situation in the
operating room, the use of the metatarsal as an osseous reference point may be
helpful. In general, a range of 15° to 20° is recommended for the
dorsal angle between the metatarsal and the phalanx, but the metatarsal
inclination angle of the individual patient has to be considered. The
inclination of the first metatarsal can be measured on a preoperative
weight-bearing lateral radiograph to help position the fusion in the sagittal
plane. The rotation of the toe should always be neutral.
Fixation
The method of fixation depends on the size and quality of the residual
phalanx. Usually, two crossed 3.0-mm cancellous screws (Synthes, Paoli,
Pennsylvania) are used. The guide-wires for the screws are inserted through
medial skin incisions under fluoroscopic control. The first is driven from the
medial aspect of the first metatarsal head, with the screw aimed at the
lateral cortex of the proximal phalanx. To avoid contact between the screws,
neither should be placed exactly in the center of the dorsoplantar diameter of
the bone; one should be shifted slightly dorsally and the other, slightly
plantarly. The second screw is inserted from the medial aspect of the proximal
phalanx and aimed at the lateral aspect of the metatarsal
(Figs. 4-A and 4-B).
Mobilization
Depending on the intraoperative stability of the fusion and the anticipated
compliance by the patient, the patient either wears a stiff-soled shoe and is
allowed weight-bearing to tolerance on the heel or wears a below-the-knee
walking cast until there is radiographic evidence of fusion. Normal shoe wear
is possible after seven to ten weeks.