Dorsomedial Cutaneous Nerve Research Articles

The potentially dangerous zone of the dorsomedial cutaneous nerve in minimally invasive surgery for hallux valgus: a cadaveric study

BackgroundThis study aims to describe the distribution of the dorsomedial cutaneous nerve (DMCN) in the middle and proximal parts of the metatarsal from a lateral view. The purpose is to provide guidance to surgeons in protecting the nerve during the 3rd and 4th generation minimally invasive surgery (MIS) for hallux valgus (HV).MethodsA total of 20 cadaveric feet were dissected to expose the course of the DMCN and sentinel vein. Measurements of the distances between the nerve/vein and the upper border of the metatarsal, as well as the height of the metatarsal, were taken from a lateral view. The distribution area was then described in proportion.ResultsAt the base of the metatarsal, the DMCN was distributed in the upper 25.7% of the area. When it reached the middle of the metatarsal, the DMCN was distributed in the upper 13.2–47.2% of the area. As for the sentinel vein, it was distributed in the upper 23.5–71.9% and upper 4.1–52.7%, respectively, at these two positions.ConclusionsThe area, which is above the line connecting the upper 1/4 point at the base of the first metatarsal and the 1/2 point at the middle of the first metatarsal, is a dangerous zone for the DMCN. Avoiding the zone is recommended during MIS for HV.

Supernumerary Branches of the Dorsomedial Cutaneous Nerve of the Hallux Crossing the Extensor Hallucis Longus Tendon

The dorsomedial cutaneous nerve of the hallux (DMCN) provides sensation to the skin of the dorsomedial hallux (big toe) and the first metatarsophalangeal joint. This cutaneous nerve, a terminal branch of the superficial fibular (peroneal) nerve, is located in the dorsum of the foot and crosses the extensor hallucis longus (EHL) tendon during its course. At this intersection point, the DMCN is at risk for injury during operations of the hallux and metatarsophalangeal joint including EHL tendon transfer, hallux valgus or hallux rigidus corrections, bunionectomy, cheilectomy, or injection procedures. Iatrogenic injuries often result in sensory loss, debilitating causalgia, or neuroma formation. The aim of this study was to identify anatomical variations at the intersection of the DMCN and the EHL tendon. Twenty‐three feet (12 left‐sided, 11 right‐sided) from 12 cadavers were dissected to follow the course of the DMCN and look at its intersection with the EHL tendon. Dissection resulted in damage to three DMCNs; however, 20 feet (11 left‐sided and 9 right‐sided feet) dissections resulted in excellent visualization of both the DMCN and the EHL tendon. Supernumerary branches of the DMCN were identified crossing the EHL tendon in multiple locations in fourteen of twenty feet (70.0%), including nine left feet (9/11, 81.8%) and five right feet (5:9, 55.6%). Of the fourteen feet with supernumerary branches, seven feet (50.0%) had two branches, four feet (28.6%) had three branches, and three feet (21.4%) had four‐to‐six branches of the DMCN crossing over the EHL tendon in multiple locations. The results of this study identify the complex branching patterns of the DMCN. Surgeons should be aware of that supernumerary branches of the DMCN exist, crossing the EHL tendon in multiple locations, and use ultrasonography to lower the risk of iatrogenic injury to the DMCN during surgical procedures.

Preventing Iatrogenic Injury to the Dorsomedial Cutaneous Nerve of the Hallux

The dorsomedial cutaneous nerve of the hallux (DMCN) is a sensory nerve that crosses the extensor hallucis longus (EHL) tendon to innervate the great toe and the first metatarsophalangeal joint. The DMCN is vulnerable to injury during operative procedures including hallux valgus or hallux rigidus correction, bunionectomy, and cheilectomy, as well as EHL tendon transfer surgeries. Intraoperative injury to the DMCN may cause pain that is intractable without subsequent surgical intervention. Accordingly, understanding anatomical variation of the DMCN is of the utmost importance. Therefore, this study assessed 23 cadaveric legs and feet to identify morphological variations of the DMCN. Observed variations included supernumerary branches crossing the EHL tendon and atypical superficial fibular nerve branching that affected the anatomical relationship between the DMCN and the EHL tendon. This study provides details of atypical variations of the DMCN and the resulting data, when used in conjunction with current imaging techniques (ultrasonography), may help to prevent unwarranted iatrogenic nerve injury.

MTP Arthrodesis: Percutaneous Interfragmentary Screw Placement and Nerve Injury

Category:Basic Sciences/Biologics; Midfoot/ForefootIntroduction/Purpose:Iatrogenic cutaneous nerve injury is the most common complication encountered in foot and ankle surgery with limited evidence to inform surgeons on neuroprotective techniques. The purpose of this study was to assess risk for injury to the dorsomedial cutaneous nerve (DCN) during insertion of percutaneous interfragmentary screws used in metatarsophalangeal (MTP) arthrodesis.Methods:Ten mid-tibia fresh frozen cadaver specimens were obtained for execution of this study. All cadavers were grossly and radiographically inspected for any evidence of existing pathology or prior operative intervention. Percutaneous placement of interfragmentary screw in both distal to proximal and proximal to distal fashion was performed. Only the skin was incised before reaming and screw placement. After screw placement, dissection of the great toe was conducted. The distance between the screws and the DCN was obtained. The DCN was also inspected for injury.Results:A total of 10 cadavers were included. The average age of our population was 64 (+- 12.6). Males represented 80% of our included specimens. Injury to the DCN was not reported using the proximal to distal screw fixation. The mean distance from the dorsal cutaneous nerve using proximal to distal interfragmentary screw fixation was 7.45+- 3.85 mm compared to 4.30+-2.71 mm in the distal to proximal screw. Distal to proximal screw fixation was associated with 10% risk of nerve injury with no nerve injuries occurring at the site of proximal to distal screws.Conclusion:In our cadaver study, proximal to distal screw fixation seems to offer neuroprotection in the setting of MTP arthrodesis. The DCN is known to have many anatomic variants, and DCN injuries can be a pretext for painful neuroma formation. Surgeons should consider careful dissection to the joint capsule in effort to decrease the risk of neurogenic injury when placing interfragmentary screws in MTP arthrodesis.

Anatomy of the Dorsomedial Cutaneous Nerve to Hallux and Surgical Implications According to the Severity of Hallux Valgus Deformity: A Cadaveric Study

The dorsomedial cutaneous nerve to hallux provides sensation to the dorsomedial aspect of the first metatarsophalangeal joint and hallux. Postoperative damage to the dorsomedial cutaneous nerve to hallux have been reported with the dorsomedial approach and symptoms can be very debilitating. The present study aims to understand how the distance between this nerve and the extensor hallucis longus tendon are affected by the severity of the hallux valgus deformity, at the level of the first metatarsophalangeal joint. We performed a cadaveric study using 35 cadaveric lower extremities (N = 35). Each specimen was classified according to the hallux valgus severity through a 30 kg partial weight-bearing antero-posterior radiograph. Before dissection, the lower extremities’ greater saphenous vein was injected with black latex to simplify the distinction between anatomical structures. We concluded that as the hallux valgus angle and the first intermetatarsal angle increase, the distance between the dorsomedial cutaneous nerve to hallux and the extensor hallucis longus tendon also increases, ranging from 12 mm in normal feet to 19 mm in severely deformed feet. Hallux valgus is a three-dimensional deformity that changes traditional surgical landmarks. To avoid harming this nerve, we established a danger zone ranging from 12 mm to 19 mm medial from the extensor hallucis longus tendon, at the level of the first metatarsophalangeal joint. The mid-medial approach to MTP should be preferred as it is out of the danger zone.

Clinical Outcomes Following Minimally Invasive Dorsal Cheilectomy for Hallux Rigidus.

Following failure of conservative treatment, a dorsal cheilectomy can be performed for patients in early stages of hallux rigidus by a traditional open approach or by a minimally invasive technique. We report our clinical outcomes following minimally invasive dorsal cheilectomy (MIDC). Eighty-nine patients (98 feet) with symptomatic hallux rigidus treated between 2011 and 2016 were included in this study. The average age was 54 years. Manchester-Oxford Foot Questionnaire (MOxFQ) scores and visual analog scale (VAS) pain scores were collected. The mean follow-up was 50 months. The average VAS score improved from 8.0 preoperatively to 3 postoperatively. The mean MOxFQ summary index score decreased from 58.6 preoperatively to 30.5 postoperatively. All 3 MOxFQ domains also improved. Swelling took an average of 5.3 weeks to settle. There were 2 wound infections and 2 delayed wound healings. Two patients had transient nerve paraesthesia, while 2 patients had permanent numbness in the dorsomedial cutaneous nerve distribution. Twelve patients (12%) underwent reoperation, of which 7 had a first metatarsophalangeal joint arthrodesis for ongoing pain, 4 had repeat cheilectomy for residual impingement, and 1 had an open removal of loose bone. Our results suggest that MIDC resulted in improvement in patient-reported outcome measures and was a safe technique with minimal complications. The complications were similar to open cheilectomy. There was an associated learning curve as 5 of our reoperations were due to incomplete cheilectomy. Coughlin grade 1 did well with MIDC as with open cheilectomy as none went onto an arthrodesis. However, 10% (7/65) of our grade 2 and 3 cases went on to an arthrodesis. Level IV, retrospective case series.

Minimally Invasive Dorsal Cheilectomy of the First Metatarsal: A Cadaveric Study.

Minimally invasive dorsal cheilectomy (MIDC) for hallus rigidus is gaining in popularity. The optimal position for the stab incision for MIDC is dorsomedial to allow an ergonomic sweeping movement of the burr, potentially putting the dorsomedial cutaneous nerve (DMCN) to the hallux at risk. We aimed to quantify the risk of using this minimally invasive technique with a cadaveric study. A total of 13 fresh-frozen cadaveric specimens amputated below the knee were obtained for this study. After the procedure, the specimens were dissected, and structures were inspected for damage. The DMCN to the hallux was cut completely in 2 specimens (15%). All the extensor hallucis longus tendons were intact, although in 1 specimen, the tendon showed some fraying on the underside of the tendon. The average distance of the stab incision from the first metatarsophalangeal (MTP) joint was 17.7 (range, 10-23) mm. The relationship of the DMCN to the stab incision was variable. The average distance of the DMCN to the incision was 3.8 (range, 0-7) mm. The danger zone for damaging the DMCN was at one-third the length of the first metatarsal proximal to the first MTP joint. The DMCN has been well studied by several authors and has a variable course. This nerve was damaged in 15% of our specimens following MIDC. We believe patients should be made aware of this risk when considering surgery. A carefully made working capsular pocket for the burr and marking this nerve before making the incision if palpable could mitigate this risk.

Minimally Invasive Dorsal Cheilectomy of the first metatarsal

Category: Other Introduction/Purpose: Traditionally, a dorsal cheilectomy of the first metatarsophalangeal (MTP) joint is performed with an open approach through a dorsomedial or midmedial incision. It is now possible to perform minimally invasive dorsal cheilectomy (MIDC) of the first metatarsal with a wedge burr. The stab incision for MIDC needs to be dorsomedial to allow an ergonomic sweeping movement of the burr. This potentially puts the dorsomedial cutaneous nerve (DMCN) to the hallux at risk. There have been no clinical or cadaveric studies to date quantifying the risk to the DMCN and the surrounding structures when a Wedge burr was used for MIDC. We aim to determine this by using fresh-frozen cadaveric specimens in a “high-risk” situation in which most of the surgeons were novices to the technique. Methods: A total of 13 fresh-frozen cadaveric specimens (7 right, 6 left) amputated below the knee were obtained for this study. 13 foot and ankle surgeons (2 left handed, 11 right handed) who had no or minimal experience in MI surgery participated in this study. After a demonstration by an experienced MI surgeon and a practice on sawbones by participants, each surgeon performed a MIDC over the first metatarsal. Fluoroscopic guidance was available throughout the procedure. After the procedure, the specimens were dissected and the DMCN and the extensor hallucis longus (EHL) were inspected for damage. The same dissection steps were used for each specimen. The relationship of the DMCN to landmarks were measured. All measurements were made to the nearest millimetre. Results: Dissection of the specimens revealed that the DMCN to the hallux was cut completely in two specimens (15%). All the EHL tendon were intact, although in one specimen, the tendon showed some fraying on the underside of the tendon, estimated to be 15%. The average distance of the stab incision from the first MTP joint was 17.7 (range: 10 – 23) mm. In terms of the relationship of the DMCN to the stab incision in specimens where the DMCN was not cut, the DMCN was superior in five specimens and inferior in six specimens. The distance of the DMCN to the incision was 3.8 (range: 0 -7) mm. Conclusion: The DMCN to the hallux has been well studied by several authors and has a variable course. This nerve is at high risk of being damaged with open surgery and is a commonly reported complication of surgery to the hallux with rates reportedly as high as 45%. This nerve was damaged in 15% of our specimens following MIDC in a “high-risk” situation. Patients need to be specifically made aware of this risk when being consented for surgery. A carefully made working capsular pocket for the burr and marking this nerve before placing the incision if palpable could mitigate this risk.

Clinical Outcomes Following Minimally Invasive Dorsal Cheilectomy

Category: Midfoot/Forefoot Introduction/Purpose: Hallux rigidus is a degenerative condition of the first metatarsophalangeal (MTP) joint, usually characterised by a dorsal osteophyte. This typically result in impingement pain and limitation of movement of the first MTP joint. Following failure of conservative treatment, a dorsal cheilectomy can be performed for patients in early stages of hallux rigidus. Minimally invasive forefoot surgery is becoming more popular with advances in technology and it is now possible to perform a minimally invasive dorsal cheilectomy (MIDC) of the first metatarsal with a wedge burr. We aim to report our clinical outcomes following MIDC. Methods: Eighty-nine patients (98 feet; 44 Right, 36 Left, 9 Bilateral) who had symptomatic hallux rigidis with failed conservative treatment, between 2011 and 2016, were included in this study. The average age was 54 (range: 29 – 71) years old. There were 25 Male and 64 Female in our cohort. They were graded preoperatively by Coughlin and Shurnas Classification (Grade 1, n=30; Grade 2, n=48; Grade 3, n=11). Clinical data were recorded. Pre and postoperative Manchester-Oxford Foot Questionnaire [MOxFQ] scores and visual analog scale (VAS) pain score were collected. The mean follow-up was 50 months (range: 12 - 84). Results: Average VAS score improved from 8.0 (range: 6 – 10) preoperatively to 3 (range: 0 – 10) postoperatively. The mean MOxFQ summary index score decreased from 58.6 (range: 30 – 94) preoperatively to 30.5 (range: 0 – 92) postoperatively. All three MOxFQ domains also improved. Swelling took an average of 5.3 (1 – 12) weeks to settle. There were 2 wound infections and 2 delayed wound healing. Two patients had transient nerve paraesthesia while two (2%) patients had permanent numbness in the dorsomedial cutaneous nerve distribution. Twelve patients (12%) had a reoperation, of which 7 had a first MTP joint fusion for ongoing pain (Coughlin Grade 2, n=6; Grade 3, n=1), 4 had repeat cheilectomy for residual impingement, and 1 had an open removal of loose bone. Conclusion: Our results suggest that minimally invasive dorsal cheilectomy (MIDC) shows significant improvement in patient reported outcome measure with MOxFQ scores. MIDC seems to be a safe technique with minimal complications. There is an associated learning curve as 5% of our reoperations were due to incomplete cheilectomy. Coughlin grade 1 do well with MIDC but 10% of our grade 2 & 3 went onto a fusion.

The Use of Ultrasonography to Identify the Intersection of the Dorsomedial Cutaneous Nerve of the Hallux and the Extensor Hallucis Longus Tendon: A Cadaveric Study

Terminal branches of the superficial fibular nerve are at risk of iatrogenic damage during foot surgery, including hallux valgus rigidus correction, bunionectomy, cheilectomy, and extensor hallucis longus tendon transfer. One terminal branch, the dorsomedial cutaneous nerve of the hallux, is particularly at risk of injury at its intersection with the extensor hallucis longus tendon. Iatrogenic injuries of the dorsomedial cutaneous nerve of the hallux can result in sensory loss, neuroma formation, and/or debilitating causalgia. Therefore, preoperative identification of the nerve is of great clinical importance. The present study used ultrasonography to identify the intersection between the dorsomedial cutaneous nerve of the hallux and the extensor hallucis longus tendon in cadavers. On ultrasound identification of the intersection, dissection was performed to assess the accuracy of the ultrasound screening. The method successfully pinpointed the nerve in 21 of 28 feet (75%). The sensitivity, positive likelihood ratio, and positive and negative predictive values of ultrasound identification of the junction of the dorsomedial cutaneous nerve and the extensor hallucis longus tendon were 75%, 75%, 100%, and 0%, respectively. We have described an ultrasound protocol that allows for the preoperative identification of the dorsomedial cutaneous nerve of the hallux as it crosses the extensor hallucis longus tendon. The technique could potentially be used to prevent the debilitating iatrogenic injuries known to occur in association with many common foot surgeries.

Anatomical variation of the dorsomedial cutaneous nerve of the hallux

Anatomical variation of the dorsomedial cutaneous nerve of the hallux

In-vivo imaging of the sentinel vein using the near-infrared vascular imaging system in hallux valgus patients.

A high incidence of dorsomedial cutaneous nerve (DMCN) damage in hallux valgus surgery has been reported. Identification of the vein around 1st metatarsal head is reported to be helpful to reduce the DMCN damage during surgery. The near-infrared (NIR) vascular imaging system, the VeinViewer® Flex, projects the vein onto the skin. The purpose of this study was to investigate the difference of the vein course between normal and hallux valgus foot using the VeinViewer® Flex, and to validate that the DMCN was accompanied with its vein. Twenty-seven feet with the hallux valgus and 27 feet in healthy subjects were included. The vein was projected onto the skin at the metatarsal head by the VeinViewer® Flex. The distance between the vein and the mid-line of the metatarsal head was measured. The correlation of the distance and hallux valgus angle or 1-2 intermetatarsal angle (IMA) was analyzed. The vein depicted by the VeinViewer® Flex and operative findings was compared in 4 patients during surgery. The vein in the hallux valgus patients shifted toward the dorsolateral side on the metatarsal bone head compared to that in healthy subjects. The distance from the midline of the 1st metatarsal bone to the vein in the hallux valgus (12.1mm) was significantly higher than that in healthy subjects (2.7mm) (p<0.05). There was a significant correlation between the shift of the vein course toward dorsolateral and IMA. Surgical exploration revealed that the vein depicted by VeinViewer® Flex could be easily identified and the nerve was along with this vein in all 4 surgical cases. The vein in the hallux valgus patients shifted toward the dorsolateral on the metatarsal bone and it could be a landmark to identify DMCN. The NIR vascular imaging system would be useful to reduce the risk of nerve damage in great toe surgery.

Bunions, feet and battling nerve damage: is the sentinel vein a reliable landmark to locate the dorsomedial cutaneous nerve of the hallux?

Background Hallux valgus is a common condition in which the phalanges of the hallux deviate laterally and the first metatarsal deviates medially. The deformity is attributed to the long-term wear of tightly fitting footwear; however, a genetic predisposition may contribute to developing the condition. Surgical treatment of hallux valgus includes an osteotomy and rebalancing of the soft tissues. The sensory branch of the dorsomedial cutaneous nerve (DMCN) lies close to the surgical incision site and is at risk of iatrogenic damage. Sensory nerve damage following the procedure has been reported in up to 45% of patients. Objectives A previous study described a transverse vessel, named the sentinel vein, located immediately superficial to the DMCN. It was therefore suggested that the sentinel vein could act as a landmark for the DMCN. The objective of the current study was to recreate the work from this previous study as far as possible, and determine if the sentinel vein is a reliable landmark for the DMCN. Methods Cadaveric specimens were carefully dissected to observe both the appearance and position of the sentinel vein. Non-dimensional measurements were then taken to report the anatomical location of the vein. Results A preserved sentinel vein was observed in 18 out of 31 specimens. In all cases the DMCN was found to either lie immediately deep to the overlying sentinel vein or just distal at the point where the vein joined the plantar venous network. Subjectively, the appearance and position of the vein was seen to vary greatly between different specimens. Non-dimensional measurements placed the sentinel vein at a mean of 30.17% of the total metatarsal length. However intra- and inter-observer repeatability analysis of the results suggested that the measurements may not be reliable in accurately describing the location of the vein. Conclusion The variation in appearance of the sentinel vein between the specimens, along with the inability to reliably measure the position of the vein, indicates that the sentinel vein may not be a reliable landmark for the dorsomedial cutaneous nerve, and therefore the use of this structure as an anatomical landmark should be cautioned.

Mapping the intersection point of the dorsomedial cutaneous nerve of the hallux and the extensor hallucis longus tendon to prevent iatrogenic injury during foot operative procedures

IntroductionThe dorsomedial cutaneous nerve (DMCN) of the hallux is a terminal branch of the superficial fibular (peroneal) nerve which supplies the skin of the medial aspect of the great toe. This cutaneous nerve branch is particularly vulnerable to iatrogenic injury during operative procedures involving the joints of the hallux, including hallux valgus correction, hallux ridigus correction, bunionectomy, and cheilectomy. Moreover, the DMCN of the hallux can be damaged during extensor hallucis longus (EHL) tendon transfer procedures due to the fact this nerve travels superficial to EHL tendon while traveling obliquely in the dorsum of the foot from a proximal lateral location to a distal medial position.MethodsThis prospective study involved cadaveric dissection of 20 legs to identify the location of where the dorsomedial cutaneous nerve (DMCN) of the hallux intersects the medial border of the extensor hallucis longus (EHL) tendon. Upon identification, further dissection was performed to follow the entire course of the superficial fibular nerve and the EHL tendon as well as their branching patterns. After marking the intersection point with a fine needle probe, digital photographs of the medial and dorsal aspects of each foot were taken of each foot. A ruler with length demarcations, specific to the millimeter, was held flush with the foot during photography. Digital photographs were then analyzed using the ruler markings as reference for measurement calibrations.ResultsThe intersection of where the DMCN of the hallux superficially crosses the medial border of the extensor hallucis longus (EHL) tendon was measured from a variety ways, including the angle of its intersection (154.7 ± 11.1 degrees) and its position relative to the distal‐most dorsal surface of the hallux (14.1 ± 1.2 cm). Additional measurements derived from this prospective study will be presented.ConclusionsThis prospective study identified the location at which dorsomedial cutaneous nerve (DMCN) of the hallux intersects the medial border of the extensor hallucis longus (EHL) tendon and mapped this intersection point in relation the other landmarks of the foot. The goal of this study is to derive confidence intervals for surgeons to identify the location of this cutaneous nerve to help prevent its iatrogenic damage during surgeries on the joints of the big toe or during extensor hallucis longus tendon transfer surgeries. If these measurements are used in conjunction with current techniques, such as ultrasound or the fourth toe flexion maneuver, the rate of successful mapping of the DMCN of the hallux may be further enhanced. Currently, additional dissections are being performed to increase the N‐value of the study.Support or Funding InformationThe research of Kyle D. Miller and Jordan V. Swearingen was supported by the West Virginia University Initiation to Research Opportunities (INTRO) Program.

Using ultrasound to prevent iatrogenic injury to the dorsomedial cutaneous nerve of the hallux

IntroductionThe dorsomedial cutaneous nerve (DMCN) of the hallux is a terminal branch of the superficial fibular (peroneal) nerve which supplies the skin of the medial aspect of the great toe. This cutaneous nerve branch is particularly vulnerable to iatrogenic injury during operative procedures involving the joints of the hallux, including hallux valgus correction, hallux ridigus correction, bunionectomy, and cheilectomy. Moreover, the DMCN of the hallux can be damaged during extensor hallucis longus (EHL) tendon transfer procedures due to the fact this nerve travels superficial to EHL tendon while traveling obliquely in the dorsum of the foot from a proximal lateral location to a distal medial position.MethodsA first‐year medical student, with introductory‐level experience in ultrasonography (USG), performed all USG in the study in an attempt to identify the intersection point of where the DMCN of the hallux crosses the EHL tendon superficially. This study used an ultrasound machine (GE Venue 40 ultrasound machine) in conjunction with an L8‐L18i wide‐band high‐frequency linear array transducer to approximate this intersection. To check the accuracy of the DMCN location, a cruciate incision was made through the skin according to the midpoint markers on the L8‐18i probe.ResultsSuccessful mapping of the DMCN was gauged in binary fashion; if the DMCN was located directly beneath the center of the cruciate incision described, the method was considered successful. Of 28 feet dissected, 21 DMCN nerves (75%) were successfully located.ConclusionsThis study reports that a first‐year medical student with introductory‐level experience successfully identified the intersection of the DMCN with the EHL via USG in 75% of feet examined. Therefore, the success rate would likely improve when USG is performed by surgeons and clinicians with more experience in USG in conjunction with other examination methods, such as the four toe flexion sign. Therefore, USG may provide an inexpensive, accurate, non‐invasive means of pre‐operatively identifying the location of the DMCN of the hallux relative to the EHL tendon to prevent inadvertent nerve damage during foot surgery.Support or Funding InformationThe research of Kyle D. Miller and Jordan V. Swearingen was supported by the West Virginia University Initiation to Research Opportunities (INTRO) Program.

Postoperative Pain and Preemptive Local Anesthetic Infiltration in Hallux Valgus Surgery

Several techniques of anesthesia are used in foot surgery. Preemptive analgesia helps to prevent the development of hypersensitivity in the perioperative period. The aim of our study was to assess the role of preemptive local anesthetic infiltration and postoperative pain after hallux valgus surgery. We evaluated 118 patients who underwent modified chevron and mini-invasive Mitchell-Kramer bunionectomy of the first distal metatarsal. After spinal anesthesia each patient randomly received an infiltration of local anesthetic or the same amount of normal saline 10 minutes before the skin incision. We measured the intensity of pain 4, 8, 12, 16, 24, and 72 hours after the release of the tourniquet using a visual analogue scale (VAS). Rescue analgesia and all other side effects were noted. Preemptive analgesia resulted in less pain during the first 24 hours after surgery. The decrease of VAS score was significantly lower in the study group during all the short postoperative periods measured. The rescue analgesia was administered in 11.9% of patients in the injected group and 42.4% in the placebo group (P < .05). In the injected group we did not observe significant difference in VAS score between patients post-chevron and miniinvasive Mitchell-Kramer osteotomy of the first distal metatarsal. No systemic adverse effects were noted. One persistent injury of dorsomedial cutaneous nerve was observed. Preemptive local anesthetic infiltration was an efficient and safe method to reduce postoperative pain after hallux valgus surgery. The analgesic effect was satisfactory in both traditional and minimally invasive techniques.

Sensory dysfunction in the great toe in hallux valgus

Injury to the dorsomedial cutaneous nerve in the foot may occur after operations for hallux valgus. Pressure neuropathy before operation is also described but remains largely unexplored. We have investigated the incidence of sensory deficit in the great toe before operating for hallux valgus and examined to what extent any deficit was related to the degree of angulation of the joint. Forty-three patients with a total of 61 great toes with hallux valgus presenting for consideration of surgical correction had their sensation tested in pre-designated zones using a five-filament set of Semmes-Weinstein monofilaments. These allowed good inter-observer reliability with an intra-class correlation coefficient of 0.84. Sensory symptoms were noted by only 21% of the patients, a measurable reduction in sensation by one monofilament grade or more was found in an additional 44%. No relationship was found between the degree of sensory loss and the degree of angulation. Patients with symptomatic hallux valgus may have sensory loss in the toe without being aware of it. Normal subjective sensation does not reliably predict normal sensory function. Given the potentially high rates of nerve damage following operations for hallux valgus, we recommend objective sensory testing as part of routine assessment before surgery.

The surgical anatomy of the dorsomedial cutaneous nerve of the hallux.

Most techniques described for the correction of hallux valgus require exposure of the distal aspect of the first metatarsal. A dorsomedial incision is often recommended. Texts counsel against damaging the dorsal digital nerve, as a painful neuroma is an unwelcome surgical complication. Our study on cadavers aimed to investigate the anatomy of the dorsomedial cutaneous nerve in the metatarsophalangeal region, with special reference to surgical incisions. A constant, previously unrecognised branch of the nerve was identified. This branch is likely to be damaged if a dorsomedial approach is used. It is recommended that a mid-medial incision be used instead, i.e. at the junction of the plantar and dorsal skin.

Dorsomedial cutaneous nerve syndrome: treatment with nerve transection and burial into bone.

Damage to the dorsomedial cutaneous nerve of the foot, which innervates the medial hallux, may occur with crush injury or iatrogenically with bunion surgery. Severe neuritic pain after bunion surgery may alert the surgeon that this small nerve has been damaged. The term "dorsomedial cutaneous nerve syndrome" is suggested for this condition, and nine patients with such forefoot presentations, all of which were unresponsive to nonoperative interventions, are described. The nerve had been either transected or bound in scar tissue; in these nine cases, the nerve was then resected and buried in the proximal aspect of the first metatarsal or the medial cuneiform. Most patients underwent an additional procedure (other than the nerve procedure), such as revision bunionectomy or arthrodesis, but all felt they could clearly delineate nerve pain from bone or joint pain. All patients experienced marked relief of their symptoms, usually within days after the surgery, and were satisfied with the results. The verbal analog pain score, on a scale of 0 (no pain) to 10 (pain requiring amputation), improved from a preoperative level of 8.6 to a postoperative level of 2.0. Resection and burial of this nerve appears to be a useful treatment for neuritis unresponsive to nonoperative measures.

The surgical anatomy of the dorsomedial cutaneous nerve of the hallux

Most techniques described for the correction of hallux valgus require exposure of the distal aspect of the first metatarsal. A dorsomedial incision is often recommended. Texts counsel against damaging the dorsal digital nerve, as a painful neuroma is an unwelcome surgical complication. Our study on cadavers aimed to investigate the anatomy of the dorsomedial cutaneous nerve in the metatarsophalangeal region, with special reference to surgical incisions. A constant, previously unrecognised branch of the nerve was identified. This branch is likely to be damaged if a dorsomedial approach is used. It is recommended that a mid-medial incision be used instead, i.e. at the junction of the plantar and dorsal skin.