Flexor Hallucis Longus Augmentation for Insertional or Noninsertional Achilles Tendinopathy

14 Pages·2004·0.67 MB·English

11
Flexor Hallucis Longus Augmentation
for Insertional or Noninsertional
Achilles Tendinopathy
Gregory P. Guyton
Simple surgical debridement of the Achilles jig. Debridement of 50% or less was not associated
tendon, either for insertional or noninsertional with rupture if performed in a superior-to-infe-
tendinopathy, inevitably gives rise to a quandary: rior direction.1
What if there is very little normal tissue left (Fig. Mechanics aside, the addition of more plan-
11.1)? In these cases, augmentation of the remain- tarfl exion strength may be appropriate even in
ing tendon should be considered. A wide variety cases of milder tendinopathy. Just as the thresh-
of potential options are available for this purpose, old for determining when augmentation is appro-
including the use of free allograft or autograft, priate is nebulous, so is the limit of debridement.
local graft from the plantaris, reshaping of the A variety of subjective approaches have been
Achilles itself by a V to Y transfer or turn-down described, the most radical of which was recently
procedure, a peroneus brevis tendon transfer, or advocated by Martin et al.2 In an effort to make
a fl exor hallucis longus (FHL) tendon transfer. insertional Achilles debridement more predict-
Transfer of the FHL is attractive: the tendon is able, they adopted a technique of complete exci-
almost invariably free from tendinopathy itself, is sion of the distal 5 cm of the Achilles, followed by
anatomically convenient, and can be harvested midfoot harvest of the FHL and spanning of the
with only minimal functional loss in nonathletic defect. Despite the dramatic nature of the surgery,
patients. We point out that the same technique patient satisfaction was remarkably high, with 38
can be used in the management of chronic rup- of 44 patients fully satisfi ed.
tures of the Achilles tendon. In the nonathletic patient, the clinical defi cit
resulting from the harvest of the FHL seems to be
remarkably limited. Most patients in all the pub-
Indications lished series are over 50; it is unclear if the loss of
hallucal push-off would be more noticeable in a
younger population to whom the ability to
When Should Augmentation Be Considered?
sprint or jump is more highly valued. Coull et al.
No clear consensus exists as to the precise degree analyzed morbidity following FHL transfer in-
of tendon debridement that should warrant aug- cluding harvests both from the midfoot and the
mentation. In insertional tendinopathy, debride- posterior aspect of the ankle.3 A trend toward
ment of up to 50% of the tendon insertion is decreased loading of the hallux on the operative
considered unlikely to result in major mechanical side was noted on force plate pressure measure-
compromise of the tendon insertion. Kolodziej et ments, and a clinically apparent decrement in
al. performed a biomechanical study involving fl exion strength of the hallux was noted on
progressive release of the Achilles tendon inser- physical exam. Nevertheless, clinical symptoms
tion in 25% increments followed by application of were essentially absent, and no transfer metatar-
a cyclic load of three times body weight in a testing salgia was present. This result has been borne out
99
100 G.P. Guyton
FIGURE 11.1. A chronic ossific insertional Achilles tendinopathy.
in other follow-up studies of the procedure; the each other. These usually have to be dissected free
success of the surgery may well outweigh any per- and released to free the FHL for transfer.
ceived defi cits with the toe. Surgically approaching the midfoot and the
Achilles simultaneously can present intraopera-
Surgical Technique tive positioning challenges. It can be diffi cult to
work on the medial side of the midfoot with the
patient prone. As a compromise, most patients
Harvest Site
have suffi cient external rotation of the leg to allow
Two anatomic options are available for harvesting the Achilles to be approached with the patient in
the FHL for transfer, a long harvest at the knot a semilateral position with the contralateral pelvis
of Henry and a short harvest behind the ankle elevated. Because of the positioning issues, har-
through the same posterior incision used to vesting the FHL in the midfoot should be included
debride the Achilles. The original descriptions of as a possibility in the preoperative plan when
FHL augmentation of the Achilles utilized a medial considered.
midfoot incision to harvest the FHL at the level of The additional length of the FHL available
the knot of Henry as the tendon passes over the through the midfoot harvest allows multiple
fl exor digitorum longus. This approach provides options regarding its insertion into the calcaneus,
a substantial length of tendon that can then be including straight bone tunnels, convergent bone
doubled back upon the Achilles to bridge any tunnels, suture anchors, or interference screws.
defects. Tashjian et al. estimated that approxi- Obtaining enough length from a posterior FHL
mately 3 cm more tendon length can be obtained harvest can be a challenge, and the FHL sheath
from the midfoot, but careful dissection can yield must be incised as distally as possible to cut the
even more.4 From a surgical standpoint, harvest- tendon as it begins to pass underneath the susten-
ing the tendon in the midfoot provides both taculum tali. It is rare that suffi cient length can be
advantages and disadvantages. It does involve an obtained posteriorly to double the tendon back
extra incision and the knot of Henry can rest upon itself, and fi xation into the calcaneus is
remarkably deep within the foot. Nevertheless, usually limited to suture anchors or interference
the approach is along a natural fascial plane and screws. Additionally, the neurovascular bundle
is well-tolerated. Many patients will have one or runs just superfi cial to and crosses over the FHL
more large juncturae connecting the fl exor digito- as it passes behind the ankle. No neurovascular
rum longus to the FHL as the two tendons cross injuries have been reported with the technique,
11. Flexor Hallucis Longus Augmentation for Insertional or Noninsertional Achilles Tendinopathy 101
but its proximity remains a concern for surgeons Stepwise Procedure
learning the technique. The anatomic margins of
safety are greater in the midfoot. The Posterior Approach
The posterior approach does not afford the
option of tenodesing the distal stump of the FHL 1. The patient is positioned according to the
to the FDL, whereas this is easily accomplished, if surgeon’s preference. For an anticipated harvest
desired, in the midfoot. Advocates of the tech- from the midfoot, supine positioning with a large
nique argue that the juncturae connecting the sandbag bump under the contralateral hip allows
FDL and FHL more distally provide a natural the leg to be externally rotated to access the medial
tenodesis in most patients. Some have advocated aspect of the foot (Fig. 11.2).
that tenodesis does not correlate with function 2. A direct midline incision is usually utilized
in any case and routinely omit it as part of the (Fig. 11.3). This incision follows the natural border
procedure. between the angiosomes, or arterial vascular ter-
There is no clear consensus on the optimal ritories, of the leg.5 The risk of leaving a small
harvest location for the FHL. The only compara- segment of devascularized skin is minimized by
tive series of any kind is the previously mentioned this technique. If it is anticipated that the distal
analysis of hallux morbidity. Coull et al. did Achilles is to be completely split and detached, a
distinguish between patients who underwent simple direct midline incision is used all the way
harvest behind the midfoot and those who had down to the Achilles insertion (Fig. 11.4). If,
posterior ankle harvest procedures, but it was not however, the case involves a noninsertional tendi-
a primary outcome variable and the two patient nopathy or detachment of the Achilles is not
populations represented a change in routine tech- anticipated, the distal 3–4 cm may veer across
nique rather than randomization. No discernable to the medial side to allow improved access to
differences in complications between the tech- the medial aspect of the calcaneal tuberosity
niques were noted. Outcomes with regard to the (Fig. 11.5).
Achilles itself were not analyzed. Hopefully, 3. Debridement of the Achilles tendon is then
ongoing studies will address the issue and provide undertaken. If a supplementary length procedure
some guidance, but, for the time being, both is necessary, such as a V–Y lengthening or a
points of view have merit and come down to the central third turn-down, these can be accom-
surgeon’s choice. The advantages and disadvan- plished at this time.
tages of the two harvest sites are summarized in 4. If a Haglund’s deformity or insertional ossi-
Table 11.1. fi cation is taken down, care should be taken to
TABLE 11.1. Comparison of Midfoot versus Posterior Ankle Harvest of Flexor Hallucis Longus Tendon
Midfoot (Knot of Henry) Harvest Posterior Ankle Harvest
Midfoot harvest is difficult with the patient in a prone Accomplished through the same incision as the
position. Achilles debridement.
Posterior Ankle Harvest Requires a separate midfoot incision, although it is Single incision technique.
Advantages generally well-tolerated.
Requires the tendinous juncturae connecting the FHL and No juncturae are present behind the ankle.
FDL to be released.
Allows easy tenodesis of the distal FHL stump and the Tenodesis of the tendons is not possible.
FDL if desired.
Dissection is carried out well away from the neurovascular The tibial nerve and branches cross superficially over the FHL
Midfoot Harvest bundle. behind the ankle.
Advantages Between 4 and 6 cm of additional tendon is available to Sufficient tendon is available only to provide motor
double back and make up defects in the distal Achilles. augmentation of the Achilles. No direct grafting of the
A variety of fixation methods of the FHL into the Achilles can be achieved.
calcaneus can be used, including simple bone tunnels. Interference screws or suture anchors are usually required to
secure the short length of FHL to bone.
102 G.P. Guyton
FIGURE 11.2. The patient is positioned supine with a large sandbag under the contralateral hip to allow simultaneous access to the
Achilles and medial midfoot.
FIGURE 11.3. A direct midline posterior incision is used. The midfoot incision can be only 4 cm long, and is centered at the plantar border
of the first tarsometatarsal joint.
11. Flexor Hallucis Longus Augmentation for Insertional or Noninsertional Achilles Tendinopathy 103
FIGURE 11.4. The tendon itself is split in the midline and the two halves are elevated off the ossific spur.
avoid such excessive resection that bone tunnels deep posterior compartment of the leg is exposed.
for the FHL augmentation could be compromised This is then split beginning approximately 5–7 cm
(Figs. 11.6 and 11.7). above the ankle mortise (Fig. 11.8). The FHL at
5. The fat pad anterior to the Achilles is split this level comes well across the midline, and, pro-
directly in the midline, and the fascia investing the vided that the dissection remains strictly on the
FIGURE 11.5. Most residual pain complaints appear to be related to underresection. If complete detachment of the Achilles is necessary,
it should be undertaken without hesitation.
104 G.P. Guyton
FIGURE 11.6. An osteotome directed from the top between the spur and the calcaneal tuberosity will restore the normal contour of the
bone without excessive resection that could compromise the bone tunnels necessary for the FHL augmentation.
midline, the muscle belly immediately encoun- 6. A right-angle hemostat is useful for getting
tered below the fascia will be the FHL (Fig. 11.9). around the tendon at the level of the mus-
The peroneus brevis muscle belly originates culotendinous junction. Before pulling vigo-
off the fi bula and the intermuscular septum far rously, considerable care should be taken to
to the lateral side; it is usually easily avoided ensure the tibial nerve has not also been in-
(Fig. 11.9). advertently pulled up. The nerve at this level can
FIGURE 11.7. The calcaneus after resection. Note the still-intact plantaris on the medial (upper) portion of the wound.
11. Flexor Hallucis Longus Augmentation for Insertional or Noninsertional Achilles Tendinopathy 105
FIGURE 11.8. The fascia is split directly anterior to the Achilles tendon in the midline. The FHL muscle belly is readily apparent. A Penrose
drain is placed around the tendon; care is taken to ensure it does not pass around the tibial nerve.
be roughly the same dimension as the FHL tendon Fixation
itself.
7. The tendon is then traced as distally as 1. If a posterior harvest has been made, the
possible behind the sustentaculum and care- FHL is then placed into the calcaneus using suture
fully severed or harvested in the midfoot (see anchors or with a tenodesis screw using a blind
below). tunnel technique.
FIGURE 11.9. The midfoot incision. The abductor hallucis muscle belly is reflected inferiorly.
106 G.P. Guyton
2. If a midfoot harvest has been made, a 4.0- 2. The abductor hallucis muscle belly is
mm burr is used to make convergent bone tunnels refl ected inferiorly. This area can be highly vascu-
in the calcaneus. As originally described, the pro- lar in some patients and meticulous electrocau-
cedure utilized a direct medial-to-lateral bone tery is essential.
tunnel, but this unnecessarily wastes a consider- 3. A fascial plane can be readily identifi ed that
able length of tendon. A bone tunnel directly on courses deep into the foot. Access to the knot of
the dorsal surface of the calcaneus can be made Henry at this level is blocked by the tendinous
with the ankle dorsifl exed. A second, converging origin of the fl exor hallucis brevis. This origin
bone tunnel from the medial side allows a rela- occasionally is so well-defi ned that it can be mis-
tively short bone tunnel but with a strong bone taken for the FHL itself. The medial plantar nerve
bridge. The bone tunnels should be widened to at this level is usually more plantar and lateral
approximately 6 mm using the burr, depending than the dissection plane, but care should still be
on the size of the FHL tendon. exercised (Figs. 11.10 and 11.11).
3. The tendon end is then whip-stitched using 4. The tendinous origin of fl exor hallucis brevis
suitable lead suture, and passed from dorsal to is taken down usually by passing a right-angle
medial through the bone tunnels. It is then turned hemostat deep to it and cutting against it. Loose
back upon itself. Under appropriate moderate fatty tissue deep to it encompasses the knot of
tension, approximately 6–8 cm of length can Henry.
usually be refl ected proximally up the Achilles. It 5. At the distal end of the knot of Henry the
is then sutured in position. FDL and FHL can be tenodesed using a 2-0 vicryl
suture. The FHL is then severed and whip-stitched
(Fig. 11.12).
The Midfoot Harvest
6. Using the whip-stitch to pull up on the FHL,
1. A 6-cm incision is made along the medial tenotomy scissors are used to take down the ten-
border of the foot centered over the medial aspect dinous juncturae between the FDL and FHL at the
of the fi rst tarsometatarsal joint. proximal end of the knot of Henry. This is always
FIGURE 11.10. The tendinous origin of the flexor hallucis muscle belly can mimic the appearance of the FHL. It must be released to access
the knot of Henry at this level.
11. Flexor Hallucis Longus Augmentation for Insertional or Noninsertional Achilles Tendinopathy 107
FIGURE 11.11. The knot of Henry.
easier to accomplish at this point than before an Results
attempt is made to pull the tendon into the pos-
terior ankle wound. Whip-stitching the tendon at The concept of using the fl exor tendons of the foot
this point rather than later facilitates easy retrieval to augment the Achilles tendon began with the
if the juncturae are only partially released and the fl exor digitorum longus (FDL), described in 1991.6
tendon gets held up during passage. The more convenient anatomy of the FHL was
7. The tendon is pulled into the posterior subsequently recognized, and the technique of
wound (Fig. 11.13). FHL augmentation for chronic Achilles tendon
FIGURE 11.12. The FHL and FDL are
tenodesed prior to release of the FHL.
This is followed by whip-stitching the
FHL and release of the juncturae
between the two tendons.
108 G.P. Guyton
FIGURE 11.13. The FHL is pulled into the posterior wound.
rupture was fi rst described in 1993 using a midfoot patient continued to use an ankle foot orthosis
harvest and a transverse bone tunnel in the calca- (AFO) (Figs. 11.14–11.19).
neus.7 The initial report contained seven patients A subsequent series in 2000 followed 20 patients
with reportedly satisfactory clinical results. A who underwent the procedure for a mean of 14
mild limitation of motion was noted and one months.8 Again, good subjective clinical results
FIGURE 11.14. Convergent bone tunnels are placed in the calcaneus. The ankle is first dorsiflexed, and a 4.0-mm burr is used to make a
tunnel on the dorsal half of the calcaneus.