Case Report

Introduction

We present a case demonstrating how intraoperative use of CHECKPOINT GUARDIAN® can assist in guiding neuroplasty of the tibial nerve and its distal branches. Direct nerve stimulation allows real-time evaluation of motor responses in the intrinsic musculature of the foot, facilitating assessment of the adequacy of nerve decompression. This approach helps determine whether additional nerve branches, both distally within the foot and proximally along the leg, require further release. Using intraoperative stimulation as a functional guide aims to maximize postoperative recovery of strength, reduce pain, and improve sensation, thereby supporting return to normal activity. We believe that a more comprehensive decompression, guided by objective feedback from Checkpoint Guardian, may reduce the likelihood of revision surgery.

1

Case

A middle-aged woman working long hours on her feet in the medical profession presented with a history of intermittent plantar fasciitis. Conservative management included daily stretching, multiple footwear modifications, custom orthotics from several podiatrists, and consistent use of a night splint. Although her plantar fasciitis symptoms improved, she began experiencing progressive, sharp pain radiating from the ankle to the heel, followed by intermittent numbness and tingling in the forefoot and toes. As symptoms worsened, she was referred for further evaluation. Diagnostic nerve blocks produced findings consistent with tarsal tunnel syndrome. She experienced temporary relief with physical therapy and a subsequent steroid injection into the tarsal tunnel; however, symptoms recurred. A tibial nerve block at the ankle provided only short-term relief. Due to persistent pain and neurologic symptoms, the patient elected to proceed with surgical intervention, including decompression of the tibial nerve within the ankle and tarsal tunnel, release of the medial and lateral plantar branches, and release of the medial calcaneal branch.

Surgical Technique and Intraoperative Findings

A curvilinear incision was placed midway between the medial malleolus and the posterior aspect of the Achilles tendon, extending distally toward the transition of the heel into the arch. This approach allowed direct visualization and safe transection of the laciniate ligament while protecting surrounding structures. Initial nerve stimulation was performed at 20 mA and a pulse duration of 200 μs to localize the tibial nerve. Mild flexion of the digits and contraction of the abductor hallucis muscle belly were observed. Repeat stimulation at a lower setting of 2 mA and 200 μs produced no visible contraction. The laciniate ligament was then transected to complete the tarsal tunnel release. Bipolar cautery was used to remove tissue from both ends of the ligament to reduce postoperative scarring and adhesion formation. Post-release nerve stimulation was repeated at both 20 mA and 200 μs and 2 mA and 200 μs settings. Compared to baseline, stimulation at the lower setting of 2 mA and 200 µs elicited visible contraction of the toe flexors and abductor hallucis, which had not been present prior to the release. Although a standard tarsal tunnel release would typically conclude at this stage, further proximal evaluation was performed. Stimulation of the tibial nerve proximal to the laciniate ligament beneath the posterior tibial fascia demonstrated a diminished response compared to the distal release site. A Metzenbaum scissor and bipolar CASE REPORT Use of CHECKPOINT GUARDIAN® in Tarsal Tunnel Release and Associated Neuroplasty of the Lower Extremity cautery were used to transect the posterior tibial fascia and perform an external neurolysis, allowing mobilization of the tibial nerve. Range-of-motion testing confirmed excellent excursion of the nerve with no adhesion points noted. Repeat stimulation with Checkpoint Guardian at 2 mA and 200 μs demonstrated substantial improvement in muscle contraction compared to the response observed after the primary tarsal tunnel release alone. The medial calcaneal branch was identified arising from the tibial nerve within the tarsal tunnel and traced distally toward the heel. Release was performed as necessary to achieve full excursion without evidence of adhesions. Subsequent stimulation at a low setting of 0.5 mA and 100 µs along the tibial nerve produced mild muscle contraction within the tarsal tunnel. Further distal evaluation at the bifurcation of the medial and lateral plantar nerves showed no contraction at this level, establishing a new baseline with stimulation at both 2 mA and 0.5 mA. The fascia of the abductor hallucis muscle was released, and the septum separating the medial and lateral plantar nerve branches was removed with bipolar cautery. Range-of-motion testing of the foot and ankle demonstrated excellent mobilization of both plantar branches. Repeat nerve stimulation at 2 mA, and then at 0.5 mA and 100 μs, revealed substantial improvement in contraction of the abductor hallucis and toe flexors along the appropriate course of the tibial nerve.

Closure and Postoperative Care

Copious irrigation was performed, followed by bipolar cautery to achieve hemostasis and cauterization of all transected fascial edges to minimize postoperative scarring and adhesion formation. The subcutaneous layer was closed with 3-0 Monocryl suture, carefully avoiding any previously released fascial bands. The skin was reapproximated with surgical staples to facilitate early ambulation and physical therapy. A compression dressing was applied, and the patient was instructed to begin range-of-motion and nerve-gliding exercises on the day of surgery. The operative extremity was kept elevated as much as possible for the first 5 days. The patient was permitted to ambulate around the home in a surgical shoe with compression dressing in place.

Outcome

At the three-week postoperative follow-up, the patient reported complete resolution of pain with significant improvement in sensation and strength. She returned to work in a CAM boot at two weeks postoperatively and transitioned to regular athletic footwear at four weeks. At that time, she demonstrated full sensation in the foot with no recurrence of shooting pain or paresthesia.

The Checkpoint Stimulator is a single-use, sterile device intended to provide electrical stimulation of exposed motor nerves or muscle tissue to locate and identify nerves and to test nerve and muscle excitability. Do not use the Checkpoint Stimulator when paralyzing anesthetic agents are in effect, as an absent or inconsistent response to stimulation may result in an inaccurate assessment of nerve and muscle function.