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T. Ettl et al.
Outlook
Technology Development
Of course, there are some major challenges for the future. Currently, there is no
CE-certied presurgical planning software that is compatible with CARLO® device.
The surgeries can be planned in commercial software, such as Mimics® (Materialize,
Belgium) or IPS CaseDesigner (KLS Martin, Germany) and exported as Standard
Tessellation Language (.stl) les, where CARLO® planning can be superimposed on
the preplanned surfaces (Fig.25.5).
In future, dedicated software for planning orthognathic surgeries, tumor resections and reconstruction, and other indications will be developed to fully digitalize
CARLO® workow and save time between the planning and surgery. With intrasurgical 3D scans and navigation, ad hoc planning and execution seems possible in
the near future.
Another limitation is high data volumes generated by the CARLO® device.
CARLO® uses the optical coherence tomography (OCT) system to control cutting
depth for prevention of injury of surrounding tissues. This real-time monitoring
generates gigabytes of data within seconds. Thus, processing of these high data
rates is an enormous challenge. However, the OCT system can have other uses than
just measurement of cutting depth. Besides cutting, light also offers diagnostic possibilities. As it has no mass, it can be coupled into the same optical path as the cutting laser giving unparalleled live information about the surgery and the tissue being
cut. OCT is one of the techniques that may be integrated into CARLO for real-time
a
cdef
Fig. 25.5 Virtual planning executed with commercial planning platform transferred to CARLO®.
(a) Mandibular resection determined by cutting guides. (b) Fibular resection determined by cutting
guides. (c) Resected mandible is exported as .stl les and loaded to CARLO® planning software.
The start and end point of the cut as well as support point dening the plane are placed. The cutting
path can be adjusted so that it ts perfectly on the surface of the fragment. (d) Next, resected mandible is replaced with the whole mandible. (e) Resected bula fragments together with tibia for
orientation are exported as .stl les and loaded to CARLO® planning software. The start and end
point of the cut as well as support point dening the plane are placed. (f) Resected bula is replaced
with the whole bula
b
25 Cold Ablation Robot-Guided Laser Osteotome (CARLO®): Technology…
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439
diagnostics during surgery. One of the most promising techniques in intra-surgical
cancer diagnostics is laser-induced plasma spectroscopy (LIBS), where short laser
pulses (<10ns) applied to the tissue of interest vaporize a very small volume of the
tissue, generating a hot plasma cloud, in which basic elements can be analyzed [20].
It has already been shown that LIBS can be used to distinguish different tissue types
[21]. Furthermore, other studies show that the LIBS method can distinguish between
benign and malignant cells [22]. While the idea of using LIBS for cancer is known
for a long time, major progress for tissue differentiation has happened mainly during the last years. This work takes major advantage of the high robustness against
environmental inuences. Its advantages in combination with an Er:YAG laser were
also proven, making this diagnostic technique a promising candidate for integration
into CARLO® device, a step toward autonomous diagnostic-surgical complex.
Future Indications
The ongoing technological will allow future expansion of indications beyond
CMF. Improved depth control with more efcient processing of OCT data combined with geometrical cuts already available in CARLO® will allow precise adjustment of bone length and corrections of malunions in extremities without the use of
patient-specic cutting guides.
The technology can also be used in neurosurgical indications. Currently, trials are
underway to test the use of CARLO® for stereoelectroencephalography (sEEG) [23].
The use of CARLO® would allow a precise placement of electrode channels based
on imaging data, allowing omission of the stereotactic frame during surgery. The
same techniques could be used for a less invasive and more precise brain biopsies
[24]. With development of faster laser, additional neurosurgical indications that
require longer cutting path and higher cutting depth, e.g., craniotomies, will be
possible.
Overall, the ongoing technological advancements and research into additional
indications could allow CARLO® to be used not only to cut virtually any bone in the
body but also differentiate between tissues, diagnose potential tumors, and map
their margins. The potential of replacing multiple software and devices with
CARLO® could eventually prove to be cost-effective and time-saving, placing
CARLO® as an important element of the OR of the future.
References
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in intraoral surgery. Oral Maxillofac Surg Clin North Am. 2021;33(2):275–85.
3. Rajitha Gunaratne GD, Khan R, Fick D, Robertson B, Dahotre N, Ironside C.A review of the
physiological and histological effects of laser osteotomy. J Med Eng Technol. 2017;41(1):1–12.
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4. Stübinger S, Nuss K, Pongratz M, Price J, Sader R, Zeilhofer HF, etal. Comparison of
Er:YAG laser and piezoelectric osteotomy: an animal study in sheep. Lasers Surg Med.
2010;42(8):743–51.
5. Nelson JS, Orenstein A, Liaw LH, Berns MW. Mid-infrared erbium:YAG laser ablation of
bone: the effect of laser osteotomy on bone healing. Lasers Surg Med. 1989;9(4):362–74.
6. Walsh JT Jr, Flotte TJ, Deutsch TF.Er:YAG laser ablation of tissue: effect of pulse duration
and tissue type on thermal damage. Lasers Surg Med. 1989;9(4):314–26.
7. Hibst R. Mechanical effects of erbium:YAG laser bone ablation. Lasers Surg Med.
1992;12(2):125–30.
8. Baek KW, Dard M, Zeilhofer HF, Cattin PC, Juergens P. Comparing the bone healing after
cold ablation robot-guided Er:YAG laser osteotomy and piezoelectric osteotomy-a pilot study
in a minipig mandible. Lasers Surg Med. 2021;53(3):291–9.
9. Baek KW, Deibel W, Marinov D, Griessen M, Dard M, Bruno A, etal. A comparative investigation of bone surface after cutting with mechanical tools and Er:YAG laser. Lasers Surg Med.
2015;47(5):426–32.
10. Augello M, Baetscher C, Segesser M, Zeilhofer HF, Cattin P, Juergens P.Performing partial
mandibular resection, bula free ap reconstruction and midfacial osteotomies with a cold
ablation and robot-guided Er:YAG laser osteotome (CARLO(®))—a study on applicability
and effectiveness in human cadavers. J Craniomaxillofac Surg. 2018;46(10):1850–5.
11. Holzinger D, Ureel M, Wilken T, Müller AA, Schicho K, Millesi G, etal. First-in-man application of a cold ablation robot guided laser osteotome in midface osteotomies. J Craniomaxillofac
Surg. 2021;49(7):531–7.
12. Ureel M, Augello M, Holzinger D, Wilken T, Berg BI, Zeilhofer HF, etal. Cold ablation robotguided laser osteotome (CARLO(®)): from bench to bedside. J Clin Med. 2021;10(3):450.
13. Koehnke R, Assaf AT, Helmbold K. Cold Ablation Robot-guided Laser Oateotome on simulated bilateral sagittal split osteotomy in a cadaveric model. Submitted to Int J Oral Maxillofac
Surg 2023.
14. Posnick JC, Choi E, Liu S.Occurrence of a ‘bad’ split and success of initial mandibular healing: a review of 524 sagittal ramus osteotomies in 262 patients. Int J Oral Maxillofac Surg.
2016;45(10):1187–94.
15. Köhnke R, Kolk A, Kluwe L, Ploder O.Piezosurgery for sagittal Split osteotomy: procedure
duration and postoperative sensory perturbation. J Oral Maxillofac Surg. 2017;75(9):1941–7.
16. Khan A, Morrison A, Cheung A, Hashem W, Compston J.Osteonecrosis of the jaw (ONJ):
diagnosis and management in 2015. Osteoporos Int. 2016;27(3):853–9.
17. Rupel K, Ottaviani G, Gobbo M, Contardo L, Tirelli G, Vescovi P, etal. A systematic review of
therapeutical approaches in bisphosphonates-related osteonecrosis of the jaw (BRONJ). Oral
Oncol. 2014;50(11):1049–57.
18. Ristow O, Otto S, Troeltzsch M, Hohlweg-Majert B, Pautke C. Treatment perspectives for medication- related osteonecrosis of the jaw (MRONJ). J Craniomaxillofac Surg.
2015;43(2):290–3.
19. Elsalanty ME, Genecov DG.Bone grafts in craniofacial surgery. Craniomaxillofac Trauma
Reconstr. 2009;2(3):125–34.
20. Fortes FJ, Moros J, Lucena P, Cabalín LM, Laserna JJ.Laser-induced breakdown spectroscopy. Anal Chem. 2013;85(2):640–69.
21. Rohde M, Mehari F, Klämp F, Adler W, Neukam FW, Schmidt M, etal. The differentiation of
oral soft- and hard tissues using laser induced breakdown spectroscopy—a prospect for tissue
specic laser surgery. J Biophotonics. 2017;10(10):1250–61.
22. Moon Y, Han JH, Choi JH, Shin S, Kim YC, Jeong S.Mapping of cutaneous melanoma by
femtosecond laser-induced breakdown spectroscopy. J Biomed Opt. 2018;24(3):1–6.
23. Winter F, Winter T, Bammerlin M, Shawarba J, Dorfer C, Roessler K.Navigated, robot-driven
laser craniotomy for SEEG application using optical coherence tomography in an animal
model. Front Robot AI. 2021;8:695363.
24. Ha TT, Thieringer FM, Bammerlin M, Cordier D. High precision bone cutting by Er:
YAG lasers might minimize the invasiveness of navigated brain biopsies. Front Oncol.
2022;11(5456):690374.
T. Ettl et al.
Chapter 26
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Motor Nerve Reconstruction oftheFacial
Nerve
JeffreyT.Gu, NatalieA.Krane, MyriamLoyo, AllisonSlijepcevic,
andMarkK.Wax
Introduction
Facial palsy (FP), a disorder in which movement of the muscles innervated by the
facial nerve are negatively impacted, is a devastating condition with functional and
aesthetic consequences and is often associated with depression, social isolation, and
poor quality of life (QOL) [1, 2, 3]. Facial asymmetry from facial palsy may lead to
displays of incongruent emotional expression, which may be misinterpreted and
make social interaction more challenging. Facial expression plays an essential role
in human communication by allowing us to convey emotions and provide nonverbal
cues. Functionally, facial paralysis may signicantly impair eyelid closure secondary to paralytic lagophthalmos, result in collapse of the external nasal valve causing
nasal obstruction, and impair oral competence and speech. Facial paralysis can
result from central or peripheral etiologies depending upon where the injury has
occurred along the facial motor pathway. Etiologies are myriad and include idiopathic (i.e., Bell’s palsy), stroke, congenital abnormalities, infectious, autoimmune,
traumatic, iatrogenic, and neoplastic causes.
J. T. Gu · M. Loyo · M. K. Wax (*)
Department of Otolaryngology-Head and Neck Surgery, Oregon Health and Science
University, Portland, OR, USA
e-mail: guj@ohsu.edu; loyo@ohsu.edu; waxm@ohsu.edu
N. A. Krane
Division Facial Plastic and Reconstructive Surgery, Department of Otolaryngology-Head and
Neck Surgery, Oregon Health and Science University, Portland, OR, USA
e-mail: krane@ohsu.edu
A. Slijepcevic
Department of Otolaryngology-Head and Neck Surgery, Atrium Wake Forest Baptist,
Wake Forest, NC, USA
e-mail: aslijepc@wakehealth.edu
© The Author(s), under exclusive license to Springer Nature
Switzerland AG 2023
J. C. Melville et al. (eds.), Advancements and Innovations in OMFS, ENT, and
Facial Plastic Surgery, https://doi.org/10.1007/978-3-031-32099-6_26
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Reanimation of facial expression is equally as diverse and may be achieved by
restoring continuity of the nerve-muscle network using techniques for nerve repair
or substitution to facilitate neurotization of the distal facial nerve, or with techniques to substitute muscle function through muscle transfer. In this chapter, we
provide a framework of options for motor nerve reconstruction of the facial nerve.
Discussion of repair options is organized by size and extent of the defect and varies
from primary repair of the transected nerve to cable graft repair of the resected
nerve, as well as different nerve transfer procedures, cross-facial nerve grafts, and
free gracilis muscle transfer for reanimation of the paralyzed face.
J. T. Gu et al.
Timing ofRepair andOutcomes
Duration of denervation and status of the facial musculature are among the most
important factors when determining the potential for treating facial paralysis.
Reversibly paralyzed facial muscles with potential for spontaneous recovery have
physiologically viable bers with intact motor units that will respond to ingrowing
axons. Flaccid facial paralysis with atrophic or brotic facial muscles are irreversibly paralyzed and will not respond to reinnervation due to mechanical and physiologic barriers to incoming axons and therefore require functional muscle to replace
the denervated facial muscles. Facial muscles completely denervated for less than
1year have been shown to respond to nerve transfer [1]. Evidence from case series
suggest that patients who undergo nerve repair within 1year after onset of FP were
more likely to achieve a House-Brackmann (HB) grade of three or better compared
to patients who underwent neurorrhaphy longer than 1year from onset [4]. Although
optimal timing for nerve transfer remains a topic in need of further study, repairs
performed beyond 12months from injury are less likely to succeed than procedures
performed earlier than 12months. However, facial musculature may remain receptive to reinnervation for periods up to 24 months following denervation in
adults [5, 6].
Jowett etal. proposed a classication system to categorize FP into ve management domains based on timing of presentation and status of the facial nerve and
facial musculature: (1) acute accid FP, (2) accid FP with potential for spontaneous recovery, (3) accid FP with viable facial musculature and low potential for
spontaneous recovery, (4) accid FP without viable facial musculature, and (5)
post-paralytic FP [7].
When considering timing and options for repair, using the aforementioned classication system may help guide treatment considerations. When the facial nerve
has incurred transection, prompt tension-free repair at the time of injury is the best
treatment option to prevent accid FP. In cases of complete facial paralysis with an
anatomically intact facial nerve, the timing of repair is less clear given potential for
spontaneous recovery. Previously for patients who developed acute accid FP following cerebellopontine angle (CPA) resections with an intact nerve, it was common practice to observe for spontaneous recovery for a period of 1year prior to any
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intervention. However, this approach results in delay of intervention in the subset of
patients who do not recover spontaneously. Recovery patterns of FP following
resection of CPA masses suggest that satisfactory recovery of facial functional is
unlikely to occur when there is no clinical evidence of facial movement within the
rst 6months [8]. Thus, recovery at 6months following CPA resection can be used
to reliably predict outcomes after 1year. In patients with an anatomically intact
facial nerve and HB grade V or worse who do not show improvement of at least one
HB grade after 6months of observation, the probability of ultimate recovery of
meaningful expression is less than 10% [9]. Therefore, the risk of facial nerve
exploration is minimal, and nerve transfer to one midfacial branch can be safely
pursued prior to 1year following nerve injury.
In cases where the facial nerve has been transected and minimal improvement in
facial function is seen 6–12months after onset, there is a low potential for spontaneous recovery of facial motion, but viable facial musculature remains. Since facial
musculature may remain receptive to reinnervation procedures up to 12months
after denervation, nerve repair and transfers are indicated within this timeframe.
Interposition graft repair may be indicated to restore neural continuity at the time of
injury when a tension-free repair is not possible. In cases where interposition graft
repair is not feasible, or when no recovery is noted within the rst 12months, a
nerve transfer procedure to the main trunk of the facial nerve can be considered.
Volitional expressions may be restored through targeted nerve transfers in this timeframe, such as masseter or hypoglossal nerve transfer to lower branches of the facial
nerve for smile reanimation, or cross facial nerve grafting to upper branches for
blink restoration.
In situations of accid FP without viable native musculature, such as following
resection or congenital absence, or unlikely to be receptive to reinnervation (e.g.,
denervation period exceeding 24months), nerve repair or transfers are no longer
indicated. In such cases, surgical interventions including static facial suspensions
and free muscle transfers should be considered. Dynamic smile reanimation may be
achieved through temporalis muscle transfer (e.g., lengthening temporalis myoplasty or minimally invasive coronoid transposition) or neurotized free muscle
transfer.
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Factors Affecting Reconstruction
In addition to timing considerations regarding duration of denervation and status of
the facial musculature, it is important to also consider patient factors, including age
and history of prior radiation. Historically, elderly patients in their seventh and
eighth decades of life were often excluded from the option of dynamic facial reanimation [10]. Prior reports examining rodent and human models of axonal load suggested axonal regeneration and total axon counts in peripheral and central nerves
can decrease with age, which were thought to contribute to worse outcomes of
cross-facial grafting in the aging population [11]. Improved outcomes in general
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have been found to be associated with increased axonal load and specically with
the presence of greater than 900 axons in the donor nerve when a cross-facial nerve
graft is used [12]. More recently, ndings from human cadaveric studies suggest
there is a high likelihood that a zygomatic branch of the nerve would have over 900
axons at its last intra-parotid point and that age may not always correlate with axonal counts [13]. Furthermore, several clinical series examining outcomes of facial
reanimation in patients 60years of age or older have shown good outcomes without
signicant differences in morbidity from dynamic facial reanimation using nerve
transfers or free functional gracilis aps [10, 14, 15]. Therefore, age alone should
not preclude the consideration of dynamic facial reanimation in elderly patients.
At the younger end of the spectrum, etiologies of pediatric facial palsy are
equally varied and can be generalized into congenital and acquired causes.
Congenital causes of pediatric facial palsy include birth trauma, Moebius syndrome,
congenital unilateral lower lip paralysis, hemifacial macrosomia, CHARGE, and
other syndromes. Most cases of acquired pediatric facial palsy arise from infectious
etiologies but can also be due to intracranial masses, iatrogenic injury, or trauma.
The most common cause of pediatric facial palsy is Bell’s palsy, which accounts for
40–50% of all pediatric cases and usually presents unilaterally. Most cases of Bell’s
palsy recover full facial function and do not require surgical intervention. In cases
that do require surgical intervention, free muscle transfer with cross facial nerve
grafting allows for functional reanimation. Children are more capable of cerebral
plasticity, and, therefore, a robust and sustainable dynamic reconstruction should be
the goal whenever possible to optimize facial movement and psychosocial interactions in children. Excellent long-term functional outcomes with improvement in
smile, facial asymmetry, and QOL have been reported in children following free
gracilis muscle transfer (FGMT) [16, 17].
The effect of high-dose radiation therapy on facial nerve grafts was previously
thought to be detrimental, which led many surgeons to prefer static or dynamic
slings over facial nerve grafts in patients undergoing postoperative radiation therapy. However, outcomes from dynamic or static slings are commonly inferior to that
after facial nerve grafting or free muscle transfer. Results from animal models comparing facial nerve cable autografts with and without prior radiation treatment have
not demonstrated any signicant differences in clinical appearance or axon counts
[18, 19]. In human cohort studies, radiotherapy with mean doses of 6000cGy has
not been found to be a signicant negative prognostic factor in best facial nerve
function achieved, especially when normal or near-normal function is present preoperatively [20, 21]. In a retrospective case study of 55 patients, long-term outcomes in patients observed over a 10-year period after facial nerve grafting have
demonstrated successful reinnervation in the group receiving postoperative radiation, with no signicant differences in success rates when compared to nonirradiated patients [22]. Altogether, these results suggest that patients requiring radiation
therapy should not be precluded from dynamic reanimation procedures with facial
nerve grafting. Perioperative consideration and optimization of comorbidities that
affect wound healing and microvasculature, including nutritional status, tobacco
use, and other modiable factors, should be addressed, although these factors and
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their impact on outcomes in facial reanimation procedures have not specically
been studied.
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Primary Repair andOutcomes
In the case of the transected nerve, such as from iatrogenic nerve sectioning, nerve
resection during tumor resection, or penetrating trauma, primary repair of the nerve
allows for the best chance for return of nerve function. Primary repair offers a single
neurorrhaphy, as opposed to multiple sites of neurorrhaphy with cable grafting
repair. Evidence from histologic studies has demonstrated decreasing number of
viable axons at each neurorrhaphy. Electrophysiologic studies have also shown better outcomes from axonal regeneration with end-to-end suture repair [23]. Two conditions must be met for primary neurorrhaphy to result in successful outcomes: both
proximal and distal nerve ends must exist, and direct nerve coaptation must be performed in the absence of tension. Tension leads to diminished perfusion and neural
regeneration [24]. A defect of up to 18mm of missing nerve can be repaired primarily, although this may necessitate mastoidectomy and rerouting of the nerve to
achieve a tension-free repair. If the repair is under tension, it is likely to be unsuccessful, and nerve grafting would be a better option to consider [5, 23, 25]. Timing
of repair in traumatic nerve transections is critical and should be performed as early
as possible. Wallerian degeneration begins within 24h and is complete at 72h.
During the rst 72h after injury, the nerve segments can be stimulated intraoperatively, and identication of branches is easier in the unscarred environment. The
axons regenerate at a rate of about 1mm per day allowing for axonal growth to
eventually reach the neuromuscular junction.
For primary repair of the transected nerve, the severed nerve ends are rst fully
mobilized to allow for tension-free neurorrhaphy and then debrided under microscopic magnication to remove devitalized tissue. A contrasted background may be
helpful for improving visualization, and 8–0 or 9–0 polypropylene suture is used for
the anastomosis to bring together the epineurium. Placement of fascicular or perineural sutures is challenging to perform and may place the nerve substance at
greater risk. Two or three well-placed sutures should be sufcient to reapproximate
the segments [23]. Measurements of objective facial functioning have been reported
in the literature using the Sunnybrook facial grading system (SFGS), which consists
of three parts evaluating resting symmetry, symmetry of voluntary movement, and
synkinesis. Subjective facial functioning and patient satisfaction have been reported
using the facial disability index, which is a brief self-reported questionnaire of
physical disability and psychosocial factors related to facial neuromuscular function
with physical function and social/well-being function subscales. Long-term follow up of primary repair after traumatic facial nerve injuries has shown adequate objective facial functioning as measured by the SFGS (mean score 74/100, range 40–96),
and good subjective functional and emotional outcomes as measured by the mean
facial disability index (FDI) physical and social scores (mean FDI physical function
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score 86, range 50–100; mean FID social/well-being function score 81, range
40–100) [25].
Cable Repair andOutcomes
When tension-free neurorrhaphy cannot be achieved despite mobilization of the
facial nerve, an interposition or cable graft is the best option for repair. The options
for nerve grafting are numerous. Careful consideration of the accessibility of the
nerve, donor site morbidity, and surgeon experience should guide decision-making
to determine the optimal donor nerve. When only a single nerve branch needs repair,
the great auricular nerve (GAN) may be used as it is usually within the same operative eld (Fig.26.1a, b). When multiple branches need repair, a longer nerve such
as the sural nerve may be considered as it would provide additional graft material.
Grafts are directed preferentially toward the midfacial branches to restore smile.
Other commonly used sensory nerves harvested for facial nerve grafting include the
medial or lateral antebrachial cutaneous nerves, which may be considered if reconstruction with a radial forearm free tissue transfer is planned [23]. Currently, there
is no consensus on whether sensory or motor nerve grafts provide the best outcomes
for patients requiring cable grafting, and overall there does not appear to be any
signicant differences noted within the literature regarding polarity of the graft [23,
26]. Patients with cancer and perineural spread at the margin of resection have been
shown to have successful reinnervations with immediate facial nerve grafting [27].
Return of facial function should be expected no sooner than 6months after nerve
repair or grafting and can commonly take between 12 and 18months for maximal
recovery. Patients who undergo surgery can expect a HB grade III as the best possible outcome [28]. Compared to primary nerve repair, cable grafting has a slower
return of nerve function and an increased rate of synkinesis [29].
ab
Fig. 26.1 Cable graft repair using the greater auricular nerve (GAN) within the same operative
eld. (a) Dissection of the GAN is visualized at the posterior aspect of the surgical eld. (b) Cable
graft using GAN to buccal branch (images courtesy of Mark K.Wax, MD)
Sura
nerve
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447
Sural Nerve
The sural nerve is a useful cable graft in situations requiring longer lengths of
graft material, or if several branches require repair. Grafts of up to 40cm can be
obtained, which can then be divided into several longitudinal nerve segments. If a
size mismatch exists, the sural nerve can usually be safely neurolyzed along its
fascicles for relatively long distances to provide several fascicles of decreased
diameter for better size match. The sural nerve branches off the tibial nerve in the
popliteal fossa and passes along two heads of the gastrocnemius muscle and
courses posterior to the lateral malleolus next to the lesser saphenous vein.
Although morbidity from harvesting the sural nerve is quite low, patients should
be counseled preoperatively regarding the resulting numbness to the lower lateral
leg and lateral aspect of the dorsum of the foot (Fig.26.2a). Early techniques
involved a lengthy continuous lower-leg incision extending from just posterior to
the lateral malleolus to the midcalf region (Fig.26.2b). Newer techniques have
evolved utilizing a series of stair- step incisions, as well as endoscopic approaches
and single incision techniques [30]. Care should be taken to place the incision for
the donor site away from areas of contact with footwear to avoid irritation of the
scar. The sural nerve graft is then sutured in an end-to-end fashion to allow for
tension-free neurorrhaphy (Fig.26.2c). In a case series reviewing patients with
sural nerve graft over a 10-year period, more than half of patients had a HB grade
III or IV [22].
abc
l
Fig. 26.2 Sural nerve graft. (a) The sural nerve can be found using surface landmarks. It is found
posterior to the lateral malleolus. Patients should be counseled regarding numbness to the lateral
aspect of the dorsum of the foot. (b) Dissection of the sural nerve via a continuous lower-leg incision. (c) Sural nerve cable graft repair of the upper division branches (illustrations courtesy of
Natalie A.Krane, MD; Images courtesy of Mark K.Wax, MD)
Distribution
of sural
nerve at
the ankle
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