Foot & Ankle International - September 2020 - 1137

Stotter et al
lesions of the talus (24.8%), chronic ankle instability
(14.3%), and fractures (8.6%). In 41% (43/105) only 1
working portal was used in addition to the anterocentral
portal, and in 19% (20/105) the anterolateral portal
could be avoided.
The overall complication rate was 7.6% (8/105). No
major complications (superficial or deep infection,
venous thromboembolism, ATA injury) and no tendon
injuries were observed. All complications involved nerve
injuries and were accompanied by impaired sensitivity of
the dorsum of the foot and in most cases sensitivity to
touch of the arthroscopic portals. Table 2 shows detailed
information on all patients with nerve injuries.
Complications caused by the anterocentral portal occurred
in 1.90% (2/105) of the cases and included injury to the
medial branch of the superficial nerve and to the DPN.
Figure 2 shows a schematic sensitivity map of these 2
patients. Injury to the DPN was observed in only 1%
(1/105) of all patients and was associated with a loss of
detection and nociception.

Quantitative Sensory Testing
QST was available for 93.1% (94/101) of all patients. In
3 patients, forefoot deformities would not allow automatic measurement. In these cases, tuning fork testing
showed no significant difference of the VDT between the
affected and nonaffected sides. The QST was performed
in the first web space, which is solely innervated by the
DPN. Figure 3 shows the QST results for all patients.
Gain and loss of function on the affected side were
observed in patients without clinical signs of nerve injury.
Injury to the DPN resulted in loss of mechanical detection
and decreased nociception. In this patient, the values for
VDT, CDT, CPT, and HPT showed a deviation of Q3 of
more than 1.5 interquartile ranges and were hence identified as outliers. The WDT was not altered significantly.
Further statistical analyses were not feasible due to the
small number of injuries to the DPN.

Ultrasonography
Of all patients, 96.0% (97/101) were available for ultrasonography. In all patients, all structures at risk could be
identified and imaged (Figure 4). There were no injuries to
the ATA and to the EDL and EHL tendons. The integrity of
the SPN and DPN was confirmed in all patients without
any clinical signs of nerve injury. Of the 7 patients suffering from an SPN injury, a neuroma of the affected nerve
was present in 3 patients (Figure 5). In these cases, the
neuroma was located adjacent to the anterolateral portal.
However, the patient with an injury of the DPN and 4 out
of 7 patients with an SPN injury showed no pathological
findings in the sonography, without signs of neuroma.

1137

Discussion
The current study is the first to investigate the neurovascular
complications of the anterocentral portal in ankle arthroscopy. The most important finding was that with proper operative technique, the anterocentral portal was a safe
arthroscopic approach to the ankle joint. Injuries to neurovascular structures caused by the anterocentral portal
occurred in 2%. The overall complication rate of ankle
arthroscopy has been reported to be between 3.4% and
10.3%.3,7,8,34-36 Nerve injuries account for approximately
half of the complications.36 Most studies report on data for
anterolateral and anteromedial portals.21,27 The SPN is the
most frequently affected structure, usually injured when
using an anterolateral portal.7 The anterocentral portal is discouraged by many authors, based on cadaveric studies that
demonstrated its proximity to the anterior neurovascular
bundle.3,9,20,24 It is deemed to be unsuitable for ankle arthroscopy because of a high risk for injury to the DPN and SPN.3
Furthermore, case reports of pseudoaneurysms of the ATA
following ankle arthroscopy have been reported.5,15,16,18,25
The anterocentral portal is established between the EHL
and EDL tendons at the joint level.11 Accordingly, structures
at risk include the medial dorsal cutaneous nerve (medial
branch of the SPN), the DPN, and the anterior tibial artery
and veins.11 The recommendations not to use the anterocentral portal are mainly based on anatomical and cadaveric
interventional studies.9,24,34 In such a study, the mean distance from the anterocentral portal to the anterior neurovascular bundle was 3.3 mm. In 22% (4/18), the arthroscope
was in direct contact with the neurovascular bundle.9
Scheibling et al19 performed anterocentral portal placement
in cadaveric ankles with and without ultrasonography and
reported distances between the arthroscope and the anterior
neurovascular bundle of 6.1 and 3.7 mm, respectively.
However, Buckingham et al2 found a mean distance of 0.7
mm for the artery with direct contact of the arthroscope in
90% and a 1.1-mm mean distance for the DPN. Furthermore,
the arthroscope touched branches of the SPN in all cases
and lacerations occurred in 15% (3/20). The average distance between the lateral border of the EHL tendon, which
serves as an anatomical landmark during portal placement,
and the DPN was reported to be 4.2 mm.24
As the anterocentral portal is currently not recommended,
data on associated complications in a clinical setting are limited. Generally, it is suggested that injury to anterocentral
neurovascular structures does not occur during establishment of the anterocentral portal, but rather during removal of
tibial osteophytes and anterior synovectomy.15,18 While the
DPN crosses the ankle joint between the EHL and EDL muscles, adjacent to the ATA, and is always in proximity to the
anterocentral portal, the SPN has a higher variability. It
divides into the medial and lateral branches (medial and
intermediate dorsal cutaneous nerves) and is purely sensory.

Foot & Ankle International - September 2020

Table of Contents for the Digital Edition of Foot & Ankle International - September 2020