Posterior Neurovascular Bundle Research Articles

Comparing Magnetic Resonance Imaging and Prostate-Specific Membrane Antigen-Positron Emission Tomography for Prediction of Extraprostatic Extension of Prostate Cancer and Surgical Guidance: A Prospective Nonrandomized Clinical Trial.

Survivors of surgically managed prostate cancer may experience urinary incontinence and erectile dysfunction. Our aim was to determine if 68Ga-prostate-specific membrane antigen-11 positron emission tomography CT (PSMA-PET) in addition to multiparametric (mp) MRI scans improved surgical decision-making for nonnerve-sparing or nerve-sparing approach. We prospectively enrolled 50 patients at risk for extraprostatic extension (EPE) who were scheduled for prostatectomy. After mpMRI and PSMA-PET images were read for EPE prediction, surgeons prospectively answered questionnaires based on mpMRI and PSMA-PET scans on the decision for nerve-sparing or nonnerve-sparing approach. Final whole-mount pathology was the reference standard. Sensitivity, specificity, positive predictive value, negative predictive value, and receiver operating characteristic curves were calculated and McNemar's test was used to compare imaging modalities. The median age and PSA were 61.5 years and 7.0 ng/dL. The sensitivity for EPE along the posterior neurovascular bundle was higher for PSMA-PET than mpMRI (86% vs 57%, P = .03). For MRI, the specificity, positive predictive value, negative predictive value, and area under the curve for the receiver operating characteristic curves were 77%, 40%, 87%, and 0.67, and for PSMA-PET were 73%, 46%, 95%, and 0.80. PSMA-PET and mpMRI reads differed on 27 nerve bundles, with PSMA-PET being correct in 20 cases and MRI being correct in 7 cases. Surgeons predicted correct nerve-sparing approach 74% of the time with PSMA-PET scan in addition to mpMRI compared to 65% with mpMRI alone (P = .01). PSMA-PET scan was more sensitive than mpMRI for EPE along the neurovascular bundles and improved surgical decisions for nerve-sparing approach. Further study of PSMA-PET for surgical guidance is warranted in the unfavorable intermediate-risk or worse populations. NCT04936334.

Medial Structures at Risk During Sinus Tarsi Approach for Fixation of Sustentaculum Tali Fractures: A Cadaveric Study

Category: Hindfoot; Trauma; Other Introduction/Purpose: Calcaneal fractures are a common injury with potential for concomitant involvement of the sustentaculum tali. Common surgical repair involves a sinus tarsi approach with placement of a lag screw from lateral to medial. There is no current study that focuses on the potential damage to the medial structures after screw placement. The goal of this paper was to describe the incidence in which medial structures were damaged using a sinus tarsi approach for lateral to medial screw fixation of the sustentaculum tali. Methods: Seven fresh-frozen below-the-knee cadaver specimens were used for the present anatomic dissection study. Prior to investigations, specimens were inspected with fluoroscopic radiographs for any pathology or prior operational intervention Each specimen underwent screw placement using the sinus tarsi approach. Medial dissection of the calcaneus was performed after screw placement to determine the proximity of the anatomical structures of interest to the inserted hardware. The four anatomical structures of interest were the tibialis posterior tendon, flexor hallucis longus, flexor digitorum longus, and posterior neurovascular bundle. Distance from the 4.0 mm screw to the previously mentioned anatomic structures was measured with a scientific ruler and recorded to the nearest millimeter. The mean, standard deviation, and range for distances were calculated for all structures. Analysis of variance (ANOVA) was used to determine statistical significance. Results: The average patient age, height, and weight were 79.3 years, 5 feet 4 inches, and 127 lbs respectively. The primary outcome of interest was the longitudinal distance between the medial aspect of the screw to the anatomical structures of interest. On average, the posterior neurovascular bundle had the closest proximity to the medial aspect of the screw for all seven specimens with a mean distance of 6.4 mm. The second closest structure was the FHL with a mean distance of 7 mm, followed by the FDL and tibialis posterior tendon, with mean distances of 9.9 mm and 13.9 mm respectively. The posterior neurovascular bundle was hit by the screw on one occasion, whereas the hardware contacted the FDL on two separate occasions. The screw was placed through the FDL in one of the two occasions; however, the FDL was not transected or ruptured. Conclusion: This study sheds more light on the potential risks to medial structures when placing the sustentacular screw during open reduction and internal fixation of displaced intraarticular calcaneal fractures. We urge the orthopedic surgeon to exercise extreme caution when performing this critical step of the procedure to minimize avoidable injury to structures of importance that may increase the morbidity of the patient.

Avoidance of injury to the posterior neurovascular bundle during total ankle arthroplasty – A simple technical tip

Iatrogenic nerve injury to the tibial nerve is a serious but avoidable complication of total ankle replacements and may be under-reported as it may go unrecognised or thought to be due to tarsal tunnel syndrome. The tibial nerve is particularly vulnerable during the saw cuts at the posteromedial corner without appropriate protection. Prior to drilling the tibial and talar pins of the adjustment block for the Infinity ankle replacement we perform a 2 cm incision behind the medial malleolus. The tibialis posterior tendon sheath is identified and incised. A periosteal elevator is used to develop a plane between the back of the tibia and the tibialis posterior tendon and then exchanged for a mini Hohmann retractor protecting the neurovascular bundle. This allows us to drill the pins and saw cuts safely. The Hohmann retractor can be felt at the tip of the saw blade providing reassurance that the blade is not too deep. Our technique has not previously been reported in the literature. It acts as a simple reproducible way of avoiding injury to structures at the back of the ankle joint.

Anatomic Structures at Risk during Posterior to Anterior Percutaneous Screw Fixation of Posterior Malleolar Fractures: A Cadaveric Study

Category:Ankle; TraumaIntroduction/Purpose:Posterior malleolus fractures (PMFs) are typically associated with trimalleolar ankle fractures and have been reported to occur in 10-40% of ankle fractures. The PM may be fixed by direct ORIF or indirect percutaneous reduction. Direct reduction via a posterolateral approach is required for larger fragments, which requires prone or lateral decubitus positioning. Indirect reduction and fixation with anterior to posterior (AP) screws remains the most common method, in which screw threads are not entirely across the fracture site to allow interfragmentary compression.Objective: Determine the risk to anatomic structures utilizing a percutaneous technique for posterior to anterior (PA) screw fixation. It is advantageous as it places all the threads across the fracture site even for small fragments and can be performed in the supine position.Methods:10 fresh-frozen, morphologically normal cadaver lower leg. Under fluoroscopic guidance, 1.35 mm Kirschner wire was inserted percutaneously from anteromedial to posterolateral. Guidewire was inserted from a starting point just medial to the tibialis anterior tendon and aimed at a point just lateral to the Achilles tendon. Small skin incision was made over the wire posteriorly, displacing the Achilles tendon medially as required. The wire was then over-drilled in posterior to anterior direction and replaced with a 4.0 mm partially threaded cannulated screw directed posterior to anterior. Each specimen was dissected, and adjacent soft tissue and neurovascular structures were identified. The distance from the guidewire to each anatomic structure of interest was measured. Descriptive analysis and the correlation between the mean distances from the guidewire to each structure was calculated using SPSS version 26.Results:The sural nerve was directly transected in 1/10 specimens (10%) and in contact with the wire in a second specimen (10%). There was a significant correlation between the proximity of the guidewire to the apex of Volkmann’s tubercle and its proximity to the sural nerve.(r= 0.705, p = 0.034) The flexor hallucis longus (FHL) muscle belly was perforated by the guidewire 40% of the time but was not tethered or entrapped by the screw. The neurovascular bundles were safely away from the wire in all cases. The lateral 1-2 mm of the Achilles tendon was pierced by the guidewire 20% of the time. Although suboptimal, these injuries may be of little clinical consequence, and the screw passed without tethering the tendon in all cadaveric specimens.Conclusion:Percutaneous PA screw placement is a safe technique which can be improved with several modifications. A mini- open technique is recommended to protect the sural nerve. The surgeon may consider aiming slightly more medial and closer to the Achilles tendon in order to avoid injury to the sural nerve. It is also advisable to use a soft tissue guide when over-drilling the guidewire. There may be potential for tethering of the FHL with use of a washer or large screw head. Risk to the anterior and posterior neurovascular bundles is minimal.

Anatomic Structures at Risk During Posterior to Anterior Percutaneous Screw Fixation of Posterior Malleolar Fractures: A Cadaveric Study.

Background. There are no established guidelines for fixation of posterior malleolus fractures (PMFs). However, fixation of PMFs appears to be increasing with growing evidence demonstrating benefits for stability, alignment, and early functional outcomes. The purpose of this study was to determine the risk to anatomic structures utilizing a percutaneous technique for posterior to anterior (PA) screw fixation of PMFs. Methods. Percutaneous PA screw placement was carried out on 10 fresh frozen cadaveric ankles followed by dissection to identify soft tissue and neurovascular structures at risk. The distance from the guidewire to each anatomic structure of interest was measured. The correlation between the mean distances from the guidewire to each structure was calculated. Results. The sural nerve was directly transected in 1/10 specimens (10%) and in contact with the wire in a second specimen (10%). There was a significant correlation between the proximity of the guidewire to the apex of Volkmann's tubercle and its proximity to the sural nerve. The flexor hallucis longus (FHL) muscle belly was perforated by the guidewire 40% of the time but was not tethered or entrapped by the screw. Conclusions. Percutaneous PA screw placement is a safe technique which can be improved with several modifications. A mini-open technique is recommended to protect the sural nerve. There may be potential for tethering of the FHL with use of a washer or large screw head. Risk to the anterior and posterior neurovascular bundles is minimal.Levels of Evidence: Level V.

Comparison of Tip- Versus Hub-Oscillating Saw Blade Control in a Total Knee Arthroplasty Model

BackgroundOscillating saws are commonly used for bone preparation in total knee arthroplasty but can cause injury to the posterior neurovascular bundle during tibial resection. Tip-oscillating saw blades are a recent innovation that could improve saw control due to decreased excursion; however, the tactile feedback to the surgeon is different. MethodsTo compare traditional hub and new tip-oscillating saw blades, 16 participants of varying levels of experience were video-recorded during composite tibial bone model resections to measure posterior saw blade plunge. Subjective perceptions of saw control and preference were also surveyed. ResultsSaw blade design and level of surgical experience did not produce a significant difference in posterior saw blade plunge (P > .05). Independent of saw blade design, subjects with no previous saw experience had significantly decreased posterior tibial plunge over subsequent resections. Tip-oscillating saw blades were perceived to be easier to use and control by less experienced participants (P = .0163). ConclusionTip-oscillating saw blades do not alter the risk of posterior tibial saw plunge compared with traditional saw blades.

Avoiding Neurovascular Risk During Percutaneous Clamp Reduction of Spiral Tibial Shaft Fractures: An Anatomic Correlation With Computed Tomography.

The use of percutaneous clamps is often a helpful tool to aid reduction and intramedullary nailing of distal tibial spiral diaphyseal fractures. However, the anterior and posterior neurovascular bundles are at risk without careful clamp placement. We describe our preferred technique of percutaneous clamp reduction for distal spiral tibial fractures with a distal posterolateral fracture spike, with care to protect the adjacent neurovascular structures. We also investigated the relationship between these neurovascular structures and the site of common percutaneous clamp placement. Preoperative computed tomography images of surgically managed patients who sustained this specific common fracture pattern (distal third spiral diaphyseal tibia fracture with a posterolateral fragment) were retrospectively reviewed. On computed tomography, we extrapolated the ideal virtual clamp site on the posterolateral fracture fragment to facilitate reduction. The average distance of this clamp position from the anterior neurovascular bundle was 14 mm (SD = 7.6), with a range of 6-32 mm. The average distance of the clamp site from the posterior neurovascular bundle was 19 mm (SD = 6.1), with a range of 11-30 mm. In 31% of patients, the distal fragment's apex extended anterior to the interosseous membrane, and in 69% of patients, the apex was posterior to the interosseous membrane. We also describe our preferred surgical technique with percutaneous clamping and tibial nailing, which involves sliding the posterolateral tine of the percutaneous clamp along the lateral tibial cortex to prevent neurovascular bundle injury.

Morphological Description of the Flexor Digitorum Accessorius Longus Muscle and its Clinical Significance

OTTONE, N. E.; TEJEDOR, M; BLASI, E.; MEDAN, C. D.; FUENTES, R. & DEL SOL, M. Morphological description of theflexor digitorum accessorius longus muscle and its clinical significance. Int. J. Morphol., 33(2):611-619, 2015.SUMMARY: The flexor digitorum accessorius longus muscle (FDALM) is an anatomical variation that occurs with low frequencyin the leg and feet. It was first described by Meckel in 1818. It arises from the tibia or fibula and extends from this towards the quadratusplantae muscle or the flexor digitorum longus muscle, crossing the medial retromalleolar canal and creating a close relationshi p with theelements of the tibialis posterior neurovascular bundle. A hundred and ten legs were dissected from Caucasian, adult, undefined sexcadavers, previously kept in 5% formalin solution. We developed a dissection technique in 2 times to search for and find the flexordigitorum accessorius longus muscle, essential for the safe and successful development of surgical procedures in the region. Th ree casesof flexor digitorum accessorius longus muscle muscle were described. Two of them were founded in the same cadaver, in a bilateraldisposition. Knowledge of this muscle variation, its embryonic origin and the possibility of finding during clinical studies an d invasiveprocedures in the leg and feet is important for differential diagnosis in compressive pathologies.KEY WORDS: Flexor digitorum accessorius longus muscle; Compressive pathologies; Anatomical variation

Ultrasound (US) measurement of the distance between the Achilles tendon and the posterior tibial neurovascular bundle in equinus infantile deformity

To study the distance between the Achilles tendon and the posterior tibial neurovascular bundle via ultrasound (US) - Doppler, with the goal of preventing neurovascular bundle injuries. We studied 36 feet with equinus deformity (18 cases on the right and left side) in children with a mean age of 20.9 months. The distance between the Achilles tendon and the posterior tibial artery was intraoperatively measured using linear US at 10 MHz with Doppler. The measurement was made 1 cm proximal to the calcaneus insertion of the Achilles, where we planned to perform the tenotomy. The patient's weight and height were also recorded. Kolmogorov-Smirnov, t test, and Pearson correlation analyses were applied. Statistical significance was defined as p < 0.05. Mean distance between Achilles tendon and posterior neurovascular tibial bundle was 7.3 mm, and no differences between sexes or sides were observed. The distance was significantly correlated with weight (r = 0.54, p = 0.01) but not height or age. The distance between the Achilles tendon and the tibialis posterior neurovascular bundle is small, and there is a risk of surgical injury during tenotomy of the Achilles tendon.

Anatomic Comparison of Lateral Transfer of the Long Flexors for Concomitant Peroneal Tears

Lateral transfers of the flexor hallucis longus (FHL) or flexor digitorum longus (FDL) tendons have been described for treatment of concomitant, irreparable peroneal tears. This study evaluated the anatomic benefits and constraints of lateral FHL and FDL tendon transfers with regard to available tendon length, diameter, and proximity to the posterior neurovascular bundle. In 9 cadaveric specimens, the FHL and FDL tendons were transected through a medial approach distal to the knot of Henry. Each tendon was transferred into a lateral incision, passing the FDL tendon both posterior and anterior to the tibial neurovascular bundle. The tendons were individually secured to the base of the fifth metatarsal with the foot in maximal eversion and dorsiflexion. The length of donor tendon available for fixation at the fifth metatarsal was measured. After the FDL tendon transfer was secured, the posterior neurovascular bundle was examined for signs of compression. Average FHL tendon diameter measured 5.1 mm; the FDL measured 4.5 mm. After passage through a bone tunnel, an additional 4.9 cm of FHL tendon remained to suture to itself; only 0.5 cm remained for the posterior and anterior FDL transfers. Transfer of the FHL did not increase muscle bulk within the retrofibular groove. Every FDL transfer posterior to the neurovascular bundle produced obvious visual compression of the tibial nerve with plantar flexion and inversion of the foot. Use of the FHL tendon for lateral transfer consistently provided sufficient length of tendon for multiple fixation options and a stronger muscle for transfer. Fixation options for the FDL were limited due to its shorter length. Lateral transfer of the FDL tendon posterior to the neurovascular bundle caused visible compression on the tibial nerve with ankle and hindfoot range of motion. This anatomic study confirmed several advantages for the use of the FHL tendon transfer in cases of concomitant peroneal tears.

Assessing the Safe Direction of Instruments During Posterior Ankle Arthroscopy Using an MRI Model

The safety of posterior ankle arthroscopy is still the subject of debate. The purpose of this study was to evaluate the anatomical relationship between the posterior portals and the neurovascular structures using magnetic resonance imaging (MRI) to determine the safety of posterior portals in posterior ankle arthroscopy. Forty ankles from 38 patients who had undergone MRI scanning for ankle disorders were assessed (18 males, 20 females). For each ankle, the angles of the presumed position of the portals to the posterior neurovascular structures and the malleoli were measured on 4-mm proximal slices from the anterior tip of the fibula. The shortest distance from the sural nerve and the tibialis posterior neurovascular bundle to the position of the posterior portals was measured. The average distance between the posteromedial portal and the tibialis posterior neurovascular bundle was 18 ± 3 mm, whereas the average distance between the posterolateral portal and the sural nerve was 15 ± 3 mm. In 100% of ankles, there were no neurovascular structures lying within the region between the anterior tip of fibula and the posteromedial portal or between the posterior tip of fibula and the posteromedial portal. In 32 ankles (80%), the medial neurovascular structures were present on the medial side of the line running between the anterior tip of medial malleolus and the posteromedial portal. The posterior neurovascular structures were not in immediate proximity to where we estimated the posteromedial and posterolateral portals to be located. The findings of the present MRI-based study suggest that arthroscopic instruments oriented toward the fibula may be safely introduced into the posterior ankle without injuring the neurovascular structures.

Familial History of Bone Tumors

A 61-YEAR-OLD MAN PRESENTS WITH PROGRESSIVE CHRONIC PAIN OF HIS LOWER extremities and episodes of dysthesia of his left foot. On physical examination, he has bowing of his extremities with prominent bony masses on both legs, particularly near his knee, that have been present since birth (FIGURE 1). The patient’s father and sister have similar lesions. Complete blood cell count and differential are within normal limits. Plain radiograph and magnetic resonance imaging show multiple exostosis with the largest lesion arising from the posterior left tibia. There is no evidence of malignant transformation, although significant impingement on the posterior neurovascular bundle is seen. What Would You Do Next?.

Medial subtalar arthroscopy: a cadaveric study of the tarsal canal portal

To study the safety of the tarsal canal portal in medial subtalar arthroscopy. Twenty-three fresh frozen foot and ankle specimens were divided into two groups with different orientation of the portal tract. Three types of tarsal canal portals were identified. The relationships of the metal rod and the flexor digitorum longus tendon and the posterior neurovascular bundle were studied. In group A, a type 1 tarsal canal portal tract was established in seven specimens, a type 2 portal tract in three specimens, and a type 3 portal tract in two specimens. In group B, a type 1 portal tract was established in ten specimens and a type 2 portal tract in one specimen. No type 3 portal tract was established in group B. There was no statistical significance demonstrated for establishment of a type 1 portal tract and "non type 1" (type 2 or 3) portal tract in group A and group B. The average shortest distance between the rod and the posterior tibial neurovascular bundle was 7 mm in group A and 9 mm in group B. This study provides the anatomic basis for the establishment of the tarsal canal portal. There is a risk of injury to the flexor digitorum longus tendon and the posterior tibial neurovascular bundle with the tarsal canal portal, and it should be used with great caution.

Safe femoral pin placement in knee navigation surgery: A cadaver study

A number of navigation systems used for total knee replacement surgery currently require the insertion of a distal femoral reference sensor pin, which is placed anterior to posterior just superior to the level of the knee joint. There is potential for the posterior neurovascular bundle to be damaged during the insertion of this sensor device. The aim of this cadaveric study was to identify the structures at risk during insertion of the distal femoral sensor, and determine whether a safe zone for insertion could be identified. Sixteen cadaveric lower limbs (8 pairs) were studied. In each knee Steinman pins were passed from anterior to posterior, 5 cm proximal to the level of the femoral articular cartilage, directly AP and angled at 30° passing medially or laterally. All pins that were passed directly from anterior to posterior and from lateral to medial passed within 5 mm of a major neurovascular structure, while 62.5% of pins passing from medial to lateral passed within 5 mm of a major neurovascular structure. The popliteal vessels and the sciatic nerve are at risk of injury from a navigation pin or drill placed in the distal femur during knee navigation. Caution should be exercised in passing these pins and alternate methods of fixing femoral sensors should be considered.