The procedure is commonly performed on an outpatient basis with the patient
under regional or general anesthesia. We prefer a combination of general
anesthesia with popliteal block augmentation for postoperative pain control.
After appropriate sterile preparation and draping of the limb, the leg is
exsanguinated and a calf or ankle tourniquet is inflated. A 5-cm longitudinal
incision is made over the dorsal aspect of the first metatarsophalangeal
joint, just medial to the extensor hallucis longus tendon
(Fig. 1). Blunt dissection is
continued down to the level of the dorsal joint capsule. With a number-15
scalpel blade, a longitudinal dorsal joint capsulotomy is performed 2 mm
medial to the extensor hallucis longus tendon
(Fig. 2), after which the full
thickness of the capsule is reflected off the first metatarsophalangeal joint,
leaving a cuff for later repair. Forceful plantar flexion of the distal
phalanx can facilitate stripping of the remaining capsular and periosteal
attachments from both sides of the joint, allowing exposure of the entire
metatarsal head and the base of the proximal phalanx
(Fig. 3). The plantar plate and
the remaining portion of the capsule are mobilized from their osseous
attachments, maximizing exposure. The articular surface is examined for
arthritic changes; osteophytes that have formed at the joint level are
resected with use of a rongeur (Fig.
4). Careful planning of the bone preparation is required to
preserve maximum length of the hallux; options include cup-and-cone reamers,
burrs, or flat saw cuts. We use a microsagittal saw
(Fig. 5) to resect the
articular surfaces, thereby creating flat bone ends for maximal apposition
during the fusion. Care must be taken not to shorten the metatarsal by making
this cut with a dorsal-to-plantar bevel, which would have a detrimental effect
on the metatarsal cascade. Rather, the cut is made to position the proximal
phalanx in slight dorsiflexion relative to the floor. The articular surface at
the base of the proximal phalanx is then resected perpendicular to its long
axis with use of the microsagittal saw
(Fig. 6). During the
performance of both the metatarsal and phalangeal osteotomies, baby Hohmann
retractors are used to expose the bone surfaces and to match the plantar soft
tissues. The resection level is made deep to the subchondral plate, down to
healthy trabecular bone, to optimize the chance of obtaining a fusion of the
joint. Two flat parallel opposing surfaces are obtained and coapted for the
fusion (Fig. 7).
Positioning of the joint is very important in order to maximize function
after fusion has been obtained. The normal first metatarsal declines at a
10° to 40° angle relative to the floor, depending on the degree of
planus or cavus of the foot. Because of this variation, we reference the
position of the metatarsophalangeal joint relative to the floor rather than
aligning the joint relative to the metatarsal itself. In order to assess this
alignment, we use a sterile rigid flat surface (such as a lid from one of the
surgical trays) to create a weight-bearing surface against which we simulate
contact of the foot with the floor (Fig.
8). The toe should be positioned in 10° of dorsiflexion
relative to the floor (usually about 15° to 25° relative to the first
metatarsal shaft). In addition, the joint is positioned in 15° to 20°
of valgus, with care being taken to ensure that the hallux phalanx does not
impinge against the second toe (a condition that is poorly tolerated).
Rotational alignment is maintained in a neutral position, ensuring that the
toenail faces straight upward and is aligned with the toenails of the lesser
toes.
Fixation options include dorsal plating, staples, Kirschner wires, or
interfragmentary screw fixation. We routinely use two crossed 4.0-mm lag
screws for fixation. With the joint held in the appropriate position, two
guide-pins from the 4.0 cannulated screw system are placed across the first
metatarsophalangeal joint in a cruciate configuration. The first pin is placed
retrograde from the medial aspect of the proximal phalanx into the lateral
aspect of the first metatarsal neck, and the second pin is placed in an
antegrade direction from the medial aspect of the metatarsal neck (at the
flare) into the lateral aspect of the proximal phalangeal metaphysis. Ideally,
the screws should cross exactly at the joint line, in order to optimize
stability. Confirmation of the joint alignment and positioning of the internal
guide-pins is accomplished both clinically and radiographically. We use a
mini-C-arm image intensifier for this purpose
(Fig. 9). Once the hardware
location is confirmed, the toe is held in the correct position as the
retrograde pin is backed up until it no longer crosses the joint line yet
still remains within the bone of the phalanx
(Fig. 10). The antegrade
guide-pin is then overdrilled, and a 4.0 cannulated screw is placed over it
(Fig. 11). Backing out the
retrograde pin prior to placement of the proximal screw allows maximum
compression to be obtained across the fusion site with the first screw. The
retrograde pin is then advanced back across the joint and is overdrilled,
after which the second screw is inserted. An excellent reduction and rigid
compression of the arthrodesis site is reliably obtained with this technique,
thereby avoiding the need for a dorsal plate, which is often prominent and
requires later removal. The final alignment of the joint and screws is again
confirmed clinically with use of the flat plate
(Figs. 12-A and 12-B) and
radiographically under image intensification guidance.
Following irrigation of the wound, the joint capsule is repaired with use
of absorbable suture material. The skin is closed in a standard fashion. Final
radiographs are made in the anteroposterior and lateral planes and are
compared with the preoperative radiographs (Figs.
13 and
14).
Postoperatively, the patient is placed in a rigid-soled surgical shoe and
is instructed to be non-weight-bearing for two weeks. The postoperative
bandage is simple cotton covered with an elastic wrap. After this period,
weight-bearing on the heel is allowed in the surgical shoe for four weeks. By
six weeks after surgery, full weight-bearing in the surgical shoe is allowed,
provided that radiographs demonstrate appropriate healing at the fusion site.
By twelve weeks after the operation, the arthrodesis site should be healed and
the patient can be weaned from the surgical shoe and can begin wearing a
regular shoe as tolerated.
CRITICAL CONCEPTSINDICATIONS:Arthritis of the first metatarsophalangeal jointSevere hallux rigidus (grade 3 or 4)Hallux valgus deformity with arthritisSevere varus or valgus deformityNeuromuscular hallux valgus or hallux varusRELATIVE CONTRAINDICATIONS:Adjacent interphalangeal or first metatarsocuneiform joint arthritis, which
may be exacerbated by fusion of the metatarsophalangeal jointABSOLUTE CONTRAINDICATIONS:Active infection, which would preclude the use of internal fixationOpen physeal platesPITFALLS:Excessive dorsiflexion, resulting in:Abutment of the tip of the toe against the end of a shoeIncreased stress upon and eventually arthritis of the interphalangeal
jointPressure under the first metatarsal headInadequate dorsiflexion, resulting in:Jamming of the tip of the toe into the groundAn inability to roll over the metatarsophalangeal joint during gaitVarus alignment (straight toe), resulting in:Abutment against the medial counter of a shoeIncreased pressure on, and the development of arthritis of, the
interphalangeal joint of the halluxExcessive valgus, resulting in:Impingement against the second toePainful callus formation between the hallux and the second toeDevelopment of second toe crossover and metatarsophalangeal instabilityMalrotation, resulting in:Irritation of the medial (pronated) or lateral (supinated) toenail, with
pain and/or ingrown nailExcessive shortening of the first ray, leading to transfer
metatarsalgiaAUTHOR UPDATE:Since our original paper was published, no substantive changes have been
made in the surgical technique.
CRITICAL CONCEPTS
INDICATIONS:
Arthritis of the first metatarsophalangeal jointSevere hallux rigidus (grade 3 or 4)Hallux valgus deformity with arthritisSevere varus or valgus deformityNeuromuscular hallux valgus or hallux varus
Arthritis of the first metatarsophalangeal joint
Severe hallux rigidus (grade 3 or 4)
Hallux valgus deformity with arthritis
Severe varus or valgus deformity
Neuromuscular hallux valgus or hallux varus
RELATIVE CONTRAINDICATIONS:
Adjacent interphalangeal or first metatarsocuneiform joint arthritis, which
may be exacerbated by fusion of the metatarsophalangeal joint
Adjacent interphalangeal or first metatarsocuneiform joint arthritis, which
may be exacerbated by fusion of the metatarsophalangeal joint
ABSOLUTE CONTRAINDICATIONS:
Active infection, which would preclude the use of internal fixationOpen physeal plates
Active infection, which would preclude the use of internal fixation
Open physeal plates
PITFALLS:
Excessive dorsiflexion, resulting in:
Abutment of the tip of the toe against the end of a shoeIncreased stress upon and eventually arthritis of the interphalangeal
jointPressure under the first metatarsal head
Abutment of the tip of the toe against the end of a shoe
Increased stress upon and eventually arthritis of the interphalangeal
joint
Pressure under the first metatarsal head
Inadequate dorsiflexion, resulting in:
Jamming of the tip of the toe into the groundAn inability to roll over the metatarsophalangeal joint during gait
Jamming of the tip of the toe into the ground
An inability to roll over the metatarsophalangeal joint during gait
Varus alignment (straight toe), resulting in:
Abutment against the medial counter of a shoeIncreased pressure on, and the development of arthritis of, the
interphalangeal joint of the hallux
Abutment against the medial counter of a shoe
Increased pressure on, and the development of arthritis of, the
interphalangeal joint of the hallux
Excessive valgus, resulting in:
Impingement against the second toePainful callus formation between the hallux and the second toeDevelopment of second toe crossover and metatarsophalangeal instability
Impingement against the second toe
Painful callus formation between the hallux and the second toe
Development of second toe crossover and metatarsophalangeal instability
Malrotation, resulting in:
Irritation of the medial (pronated) or lateral (supinated) toenail, with
pain and/or ingrown nailExcessive shortening of the first ray, leading to transfer
metatarsalgia
Irritation of the medial (pronated) or lateral (supinated) toenail, with
pain and/or ingrown nail
Excessive shortening of the first ray, leading to transfer
metatarsalgia
AUTHOR UPDATE:
Since our original paper was published, no substantive changes have been
made in the surgical technique.