Anatomy of the Plantar Intermetatarsal Tunnel: A Cadaveric Study.

The contents of the plantar intermetatarsal tunnel (PIMT) and the relationship between the common plantar interdigital nerve (CPIN) and the PIMT were recorded. The width of the PIMT was measured at the metatarsal neck (MTN), metatarsophalangeal (MTP) joint and the base of the proximal phalanx (BPP). The length of the deep transverse metatarsal ligament (DTML), the PIMT and the intracapsular ligament (ICL) were also measured. The PIMT was revealed to be a narrow osseofibrous tunnel divided into 3 segments by the DTML: the distal section, the area under the DTML (middle) and the proximal section. The length of the middle section was 12.77 mm in the second intermetatarsal (IM) space and 10.18 mm in the third IM space. The lengths of the distal sections were 15.52 and 14.95 mm in the second and third IM spaces, respectively. There was some soft tissue between the CPIN and PIMT, and the CPIN was observed not to glide freely within the tunnel. The widths of the PIMT at the MTN, MTP joint and BPP were respectively 2.87, 2.56, and 3.42 mm in the second IM space and 3.10, 2.68 and 3.61 mm in the third IM space. The ICL lies between the capsules of the MTP joint, and the length of the ICL was 2.76 and 3.03 mm in the second and third IM spaces, respectively. The PIMT was found to be a complex spatial structure, and the ICL might prevent the CPIN from being squeezed into the IM space.

Treatment of Morton's neuroma with minimally invasive distal metatarsal metaphyseal osteotomy (DMMO) and percutaneous release of the deep transverse metatarsal ligament (DTML): a case series with minimum two-year follow-up.

BACKGROUND: The optimal treatment of symptomatic Morton's neuroma remains unclear; conservative methods are sometimes ineffective and neurectomy has significant rates of patient dissatisfaction. The aim of this study was to evaluate the outcome of minimally invasive distal metatarsal metaphyseal osteotomy (DMMO) and percutaneous release of the deep transverse metatarsal ligament (DTML) in patients with Morton's neuroma. METHODS: Between January 2018 and November 2019, 27 patients (29 feet) diagnosed with Morton's neuroma after clinical and radiological evaluation underwent DMMO and percutaneous DTML release. The primary clinical outcomes were pain (VAS) and function (AOFAS score). Secondary outcomes included patient satisfaction, complications, and radiographic outcomes. Patients were followed up for a minimum of two years. RESULTS: The median age of the participants was 66 years (range 48-79) and the follow-up time was 28 months (24-47). There was a decrease of 5.7 points in the VAS for pain (p < .001) and an increase of 19.9 in AOFAS (p < .001) after the surgical procedure. There was one case of superficial infection and one patient required resection of the neuroma (neurectomy). The majority of patients (89.7%) were satisfied and considered the procedure outcome as excellent or good. CONCLUSION: Treatment of Morton's neuroma with minimally invasive distal metatarsal metaphyseal osteotomy and percutaneous release of the deep transverse metatarsal ligament showed significant improvement in pain and function with a low incidence of complications and a high rate of personal satisfaction.

Intermetatarsal ligament section assisted with sonography for the percutaneous surgery of Morton's disease: Cadaveric study.

BACKGROUND: Surgical treatment of Morton's neuroma remains controversial. Several surgical techniques have been described including percutaneous transection of the deep metatarsal transverse ligament (DMTL). PURPOSE: To evaluate the efficacy and safety of percutaneous release of the DMTL under ultrasound guidance for the treatment of Morton's syndrome. MATERIALS AND METHODOLOGY: Percutaneous release of the DMTL was performed with ultrasound guidance in 48 intermetatarsal spaces of 16 cadaveric specimens. Specimens were then dissected to assess the completion of the release and the presence of any injuries of the neurovascular and tendinous adjacent structures. RESULTS: The DMTL was visualized with ultrasound in all cases. Complete release of the ligament was achieved in 87.5% (42/48) cases. One case of interdigital nerve injury was found. CONCLUSION: Percutaneous release of DMTL with ultrasound guidance for the treatment of Morton's disease has an acceptable rate of complications but care must be taken to ensure the complete release of the ligament.

Anatomic basis for a new ultrasound-guided, mini-invasive technique for release of the deep transverse metatarsal ligament.

INTRODUCTION: Morton's neuroma is an entrapment neuropathy of the third common plantar digital nerve, caused by the deep transverse metatarsal ligament (DTML). Minimally invasive or percutaneous surgery is a very common procedure, but surgical effectivity of this technique remains controversial. The goal of our study was to prove the effectiveness and safety of a new ultrasound-guided technique for DTML-release in a cadaver model. MATERIALS, METHODS, AND RESULTS: The DTML was visualized in 10 fresh frozen donated body to science-feet (eight male and two females, five left and five right) using an US device (GE Logic R7; 13 MHz linear probe, Madrid, Spain). Consecutively, minimally invasive ultrasound-guided surgery was performed. Exclusion criteria of the donated bodies to science were previous history of forefoot surgery and space occupying mass lesions. The complete release of the ligament was achieved in all specimens without damage of any important anatomical structures as proven by anatomical dissection. CONCLUSIONS: The results of this study indicate that our novel approach of an ultrasound-guided release of the DTML is safer and more effective compared to blind techniques. The DTML could reliably be visualized and securely cut through a dorsal, minimally invasive surgical incision of only 2 mm.

Is Endoscopic Decompression for Morton's Neuroma a Safe Technique?

INTRODUCTION: Morton's neuroma is predominantly attributed to chronic nerve entrapment within third space adjacent metatarsals, the deep transverse metatarsal ligament (DTML), and the plantar skin. While conservative treatments are of election, failures require alternative interventions such as ultrasound-guided injections and various surgical procedures, including minimally invasive neurectomy and DTML release. This study aimed to anatomically assess the risks associated with the endoscopic dorsal surgical decompression of Morton's neuroma. MATERIALS AND METHODS: Twenty feet from ten fresh-frozen cadaveric specimens underwent a dorsal percutaneous approach for endoscopic access. Surgical procedures were monitored by three foot and ankle surgeons. Post-surgical anatomical dissections were conducted to evaluate potential risks to surrounding structures. RESULTS: The endoscopic technique successfully sectioned the DMTL in all specimens (100%) without iatrogenic injury of tendons, nerves, or arteries, while lumbricals may be at risk. CONCLUSION: Endoscopic dorsal decompression of Morton's neuroma presents as an accessible minimally invasive surgical option with low risk of collateral associated injuries.

Study of the Anatomical Association between Morton's Neuroma and the Space Inferior to the Deep Transverse Metatarsal Ligament Using Ultrasound.

Morton's neuroma (MN) is a common condition in clinical practice. The compressive etiology is the most accepted, in which compression occurs in the tunnel formed by the adjacent metatarsals, the deep transverse metatarsal ligament (DTML) and the plantar skin. Ultrasound (US) is a reliable method of study. The presence of insufficient space under the DTML may be related to the appearance of MN. OBJECTIVES: To verify the relationship between MN and the space under the DTML between the metatarsal heads of the third (M3) and the fourth (M4) metatarsals using US. METHODS: This is a cross-sectional epidemiological study. The research study using the ultrasound (US) technique was carried out on 200 feet belonging to 100 patients aged 18 to 65 of both sexes, with a control group formed by 62 patients and a study group formed by 38 patients diagnosed with MN. RESULTS: The presence of MN and the factors associated with it were studied in 100 patients using ultrasound (US). The assessment and comparison with US of the space inferior to the DTML between M3 and M4 in control groups and patients with MN show that patients with MN have a smaller size in the variable "h" (height or distance DTML-plantar skin), in the variable "b" (base or intermetatarsal distance M3 and M4) and in the variable "s" (surface of the parallelogram "h" × "b"). The predictors of MN are a decrease in dimension "b" and an increase in weight. Sitting in an office chair and the use of a bicycle, due to equinus, have an influence on the space below the DTML, reducing it and promoting the appearance of MN. CONCLUSIONS: The two US measurements ("h" and "b") in the space below the DTML are smaller in patients with MN than in the asymptomatic group. A shorter distance between M3 and M4, and an increase in BMI are predictors of MN.

Novel Ultrasound Anatomical Measurement of the Deep Transverse Metatarsal Ligament: An Intra-Rater Reliability and Inter-Rater Concordance Study.

Insufficient space below the Deep Transverse Metatarsal Ligament (DTML) could be an etiological factor for Morton's Neuroma (MN). To date, there is a lack of studies measuring the space below the DTML. For this reason, this study assesses the intra- and inter-rater concordance and reproducibility of measurements of the space below the DTML between the third and the fourth metatarsal heads (M3 and M4) using ultrasound imaging to assess and verify the reliability and reproducibility of measurements of the space under the DTML. Forty feet from twenty patients were examined using ultrasound by three trained evaluators at two different times. The two measurements taken on each foot were: base (b)­distance between M3 and M4, and height (h)­distance between the DTML and the plantar skin surface. This was a quantitative, observational, analytical study. The concordance rate between observers for measurements of height and base were 98.5% and 99.5%, respectively. The mean area obtained of the space was 54.6 mm2 and 57.2 mm2 for both the left and right foot (p > 0.05). Reproducibility over time calculated in pre- and post-measurements showed an intraclass correlation coefficient of 1.00 (95%CI: 0.99−1.00), which leads us to conclude that the measurements are perfectly reproducible. Both measurements (height and base) of the space under the DTML, performed by ultrasound, are reliable and reproducible.

Deep transverse metatarsal ligament and static stability of lesser metatarsophalangeal joints: a cadaveric study.

BACKGROUND: The static support that guides motion around the lesser metatarsophalangeal joints (MTPJs) is complex. Biomechanical studies revealed important roles of both the plantar plane and collateral ligaments. Since part of the plantar plate is attached to the deep transverse metatarsal ligament (DTML), we hypothesized that the transection of the DTML in the intermetatarsal space may substantially reduce the MTPJ stability. METHODS: The second, third, and fourth MTPJ stabilities of 6 fresh-frozen human cadaveric foot specimens were measured under load control. Both dorsiflexion and dorsal subluxation conditions were tested. After the intact condition was assessed, the DTML was sequentially transected such that each MTPJ had a unilateral and then a bilateral DTML transection. Stiffness data were calculated using the loading range in each test condition. Paired Student t tests were performed to test for statistical significance (P value less than .05). RESULTS: In intact specimens, the mean stiffness with dorsiflexion of the second, third, and fourth toes was 0.52 ± 0.15 N/deg. When the DTML was operatively transected on one side, the dorsiflexion stiffness significantly decreased 17.3% to an average of 0.43 ± 1.00 N/deg (P < .001). Subsequent transection of the DTML on the other side of each joint resulted in a further significant decrease of 5.8% to an average of 0.40 ± 0.08 N/deg (P < .001). The mean stiffness with dorsal subluxation of the intact second, third, and fourth toes was 3.55 ± 0.66 N/mm. When the DTML was operatively transected on one side, the dorsal subluxation stiffness significantly decreased 16.1% to an average of 2.98 ± 0.64 N/mm (P < .001). Subsequent transection of the DTML on the other side of each joint resulted in a further significance decrease of 7.6% to an average of 2.71 ± 0.48 N/mm (P = .016). CONCLUSION: The DTML has a significant role in maintaining lesser MTPJ ligament stability. Both unilateral and bilateral DTML transections caused substantial instability of the lesser MTPJ. CLINICAL RELEVANCE: The DTML is part of the natural static restraint to dorsiflexion or dorsal subluxation of the lesser MTPJ. Operative transection, injury, or degeneration of this ligament may predispose the adjacent MTPJ to instability.