Cadaveric Study of the Neurovascular Bundle in Tarsal Tunnel Region among Sudanese - 2020

Background: Tarsal tunnel is situated medial to the ankle lying deep to the flexor retinaculum. Within which lies the neurovascular bundle in separate compartments. This study examines the level of bifurcation points of tibial nerve and posterior tibial artery, and the location of medial and lateral plantar nerves in the tarsal tunnel. As well as the origin of the medial calcaneal nerves. Methods: This study was a descriptive observational cross sectional study. Step by step dissections of the tarsal tunnel were performed on 30 Sudanese cadavers, the contents of the tarsal tunnel were explored. Results: The tibial nerve was found to bifurcate before the the medial malleolus calcaneal axis (MMCA) in (n=4/30, 13.3%) specimens , and inside the tunnel (n=26/30, 86.7%). The branching point of the posterior tibialartery was found before the MMCA in (n=10/28, 35.7%) of specimens, at the MMCA in (n=16/28, 57.1%), and after the MMCA in (n= 2/28, 7.1%). Medial calcaneal nerves were found to be derived from the LPN plus the TN in (n=13/30, 43.3%), while in (n=6/30, 20%) were derived from LPN plus MPN plus TN. only (n=5/30, 16.7 %) were derived from LPN alone. Conclusion: anatomical knowledge of the bifurcation points of tibial nerve and posterior tibial artery is of great importance in many medical procedures like external fixation of medial malleolus fractures, medial displacement osteotomy and nerve blocks in podiatric medicine.

Medial Displacement Calcaneal Osteotomy: Loss of Correction with Varying Drilling Techniques

Category: Hindfoot Introduction/Purpose: Surgical correction of Stage 2 posterior tibial tendon dysfunction typically involves a combination of soft tissue and bony corrections, often including a medial displacement calcaneal osteotomy (MDCO). This osteotomy is often fixated utilizing two parallel screws; however, it remains unknown how much correction is lost based on various accepted drilling techniques for common fixation of this osteotomy. Our cadaveric study compares three different surgical drilling techniques, using two parallel cannulated screws for fixation, to best maintain desired translation of the MDCO. Methods: Fifteen above knee, fresh-frozen, matched pair cadaveric specimens (30 limbs) were randomized equally into three groups. Calcanealosteotomies were performed, followed by manual 10 mm medial translation of the tuberosity. Two parallel 2.5mm guide wires were advanced across the osteotomy site under fluoroscopy. The first group involved a ‘staggered’ drilling technique in which one guide wire was over drilled to the osteotomy site with a 4.5mm cannulated drill and then a 7.0 mm cannulated screw was placed across the osteotomy, followed by a second screw in similar fashion. The second, ‘simultaneous’ group consisted of over drilling both guide wires sequentially followed by placement of both screws. The third control group involved simultaneously over drilling only the near cortex, followed by placement of the 2 screws. Following screw fixation, the calcaneal tuberosity was manually translated in a lateral direction. The loss of correction was then marked and measured in millimeters. Results: All thirty cadaveric specimens underwent standard medializing calcaneal displacement osteotomy without significant variation, or complication. Loss of medialization was measured in millimeters following a manual lateral displacing force after the screw fixation of the osteotomy. The ‘simultaneous’ drilling group experienced the greatest loss of medial displacement with the mean loss of correction being 2.6 mm (range 1.37 - 3.48 mm) following manual lateral translation. The ‘staggered’ group showed an average loss of 1.16 mm (range 0.36 - 2.67 mm). The control group, that simply involved drilling of the near cortex, demonstrated the greatest maintenance of medial displacement with a mean loss of only 0.036 mm (range 0.01 - 0.06 mm). Conclusion: Our cadaveric study comparing three different drilling techniques for maintaining the intended correction following MDCO demonstrates that simultaneous over drilling of only the tuberosity near cortex prior to screw fixation was the most resistant to loss of medial displacement; whereas mean loss of correction with simultaneous drilling of both wires to the osteotomy resulted in the greatest loss of correction at an average of 26%.

A Comparative Study of Two Different Techniques for Calcaneal Displacement Osteotomy

Category: Hindfoot Introduction/Purpose: The lateral oblique incision is widely used for calcaneal displacement osteotomy in correction of hindfoot deformities. Wound healing problems and neurovascular injury are limitations of this procedure. A technique using a Shannon burr for calcaneal displacement osteotomy was introduced to avoid these complications. The advantages of the percutaneos calcaneus osteotomy have been evaluated in a comperative study. Methods: Lateral oblique incision for calcaneus osteotomy was performed in 58 patients. The senior author changed the osteotomy technique 2014. Further 64 calcaneus osteotomies were performed percutaneously. The main indication for the calcaneus osteotomy was correction of hindfoot deformities. Complementary the number of screws used for the fixation have been axamined in the study. Results: The mean age of the patients was 51,6 (14-72) years. The patients were folled up for 12 months. All cases achieved radiographic union. Wound healing problems have been registrated in the open technique group in 16 patients (27,6%). Six of them (10,3%) required a surgical revision. No wound healing problems appeared in the percutaneous group. N. suralis was affected in the open technique group in 12 patients (20,6%) and in 4 patients (6,2%) in the percutaneous osteotomy group (p 0,02). The operating time was significantly shorter in the percutaneus osteotomy group. The correction of the hindfoot axis succeed in all patients. Risk of complication did not differ significantly between single and double screw in the percutaneous osteotomy group. Conclusion: The clinical and radiological examinations showed outstanding results. There is no evident difference between the two techniques in the radiological results. Use of a single screw in percutaneous osteotomy of the calcaneus did not increased the complication rate. The percutaneous calcaneal osteotomy had a lower complication rate in our study and is probably a useful technique in patients with diabetes and affected perfusion. Further randomised studies should consider this results.

Medial Displacement Osteotomy Performed Concurrently with Triple Arthrodesis Improves Pain and Mobility in Patients with Rigid Flatfoot Deformity and Hindfoot Valgus

Category: Hindfoot, Midfoot/Forefoot, Flatfoot Introduction/Purpose: Progression of flatfoot deformity and arthritis affects 6-38% of patients with posterior tibial tendon dysfunction treated with a triple arthrodesis. Current theory suggests that undercorrection of hindfoot valgus places abnormal stresses on the deltoid ligament and tibiotalar joint, contributing to the development of increased valgus tilt of the ankle joint or collapse of the medial arch. No large series to our knowledge has attempted to assess the potential benefit of the prospective correction of hindfoot valgus at the time of the triple fusion. Here we analyze the outcomes of 31 unilateral Stage III or IV rigid flatfoot corrections performed with concurrent medial displacement osteotomies. Methods: In an institutional review board approved retrospective study, a total of 31 feet in 31 patients were operated upon from 1/1/2009 to 1/1/2016 by a single surgeon at a large academic medical center. American Orthopaedic Foot & Ankle Society hindfoot scores and visual analog pain scores (VAS) were obtained prior to surgery and at the final post-operative follow-up where available). Foot and Ankle Ability Measure (FAAM) scores were available for 17 (54.8%) of patients. Patient demographic data, including age, body mass index (BMI), charlson comorbidity score, smoking status, and HbA1c where available were recorded. Additional surgical outcomes of interest included a return to unassisted mobility in a shoe or boot, infection and wound complication rate, 90 day re-admissions and revision/subsequent procedures. Pre-and post-operative data were analyzed using Student’s t-test for continuous variables, and Fisher’s exact test for categorical variables using Graphpad Prism (LaJolla, CA). Results: Patient demographic data is demonstrated in figure 1. Average follow-up was 1.3 ± 1.1 years (range .5 to 6.0 years). Average Pre-operative AOFAS scores available from 23/31 (74.2% of patients) averaged 33.5, with 1-year post-operative scores (8/31, 25.8%) of 76.8 ± 4.6 (p < .0001). VAS scores decreased from 6 ± 2.9 to 2 ± 2.7 (p < .0001). Superficial infections were treated in 3/31 (9.7%) of patients, while wounds developed in 6.5%. Mobility without assistive modality in a shoe or boot was reported by 30/31 (96.8%) patients, with one patient requiring a walker. No 90-day readmissions occurred, no amputations occurred, and a single patient returned to the OR 393 days after admission for symptomatic hardware removal. Conclusion: Here we demonstrate in a large retrospective analysis that performing a medial displacement osteotomy in patients with hindfoot valgus in the setting of rigid flatfoot deformity results in nearly universal remobilization, substantially improved functional outcomes, and significantly decreased pain. Few patients had wound complications or infections, and no revision reconstructions were required. Limitations to this study include inconsistent post-operative reporting, and a lack of long term post-operative outcomes. Further work includes a re-surveying of this patient base for updated patient outcomes, as well as quantitative radiographic analysis.

Mechanical Stability of a Locked Step-Plate versus Single Compression Screw Fixation for Medial Displacement Calcaneal Osteotomy

Background: Reconstruction of a flatfoot commonly involves a calcaneal Medial Displacement Osteotomy (MDO) to correct hindfoot valgus in combination with soft tissue procedures. We compared fixation of an MDO using either a single, large cannulated screw versus a locking step-plate in load to failure in a cadaveric model. Methods: Eight matched pairs of cadaveric limbs were loaded using a mechanical testing rig. Two pairs served as non-operated controls. The remaining paired limbs underwent a 10-mm MDO stabilized either with a single 7-mm screw or a step-plate with four locking screws. One pair was used as a pilot study and the remaining five pairs were loaded up to 4500 N to failure. Results: In the five pairs loaded to failure, the median (with 95% CI) maximum force were 1779 N (1099-2312) and 826 N (288-1607) for the plate and screw, respectively ( p = 0.043). With single screw fixation, the tuberosity fragment consistently failed by rotation and angulation into varus. With plate fixation, failure occurred as the screws cut through the internal surfaces of the tuberosity and body with no failure at the screw-plate interface. Conclusion: In this cadaveric model, a locked step-plate supported a significantly higher maximum force than a single large cannulated screw. Clinical Relevance: The magnitude of the load supported by the locking step-plate suggests that allowing early weightbearing post-operation may be safe in clinical practice before union of the osteotomy.

Biomechanical In Vitro - Stability Testing on Human Specimens of a Locking Plate System Against Conventional Screw Fixation of a Proximal First Metatarsal Lateral Displacement Osteotomy

Introduction:The aim of this study was to examine resistance to angulation and displacement of the internal fixation of a proximal first metatarsal lateral displacement osteotomy, using a locking plate system compared with a conventional crossed screw fixation.Materials and Methodology:Seven anatomical human specimens were tested. Each specimen was tested with a locking screw plate as well as a crossed cancellous srew fixation. The statistical analysis was performed by the Friedman test. The level of significance was p = 0.05.Results:We found larger stability about all three axes of movement analyzed for the PLATE than the crossed screws osteosynthesis (CSO). The Friedman test showed statistical significance at a level of p = 0.05 for all groups and both translational and rotational movements.Conclusion:The results of our study confirm that the fixation of the lateral proximal first metatarsal displacement osteotomy with a locking plate fixation is a technically simple procedure of superior stability.

Finite Element Analysis of Acetabular Medial Wall Displacement Osteotomy in Adult Acetabular Dysplasia

Objective To look for a suitable displacement range of acetabular medial wall following osteotomy by computer-aided design finite element analysis. Methods SolidWorks 2008 software was used to establish three-dimensional models of acetabular dysplasia pelvis. Acetabular medial wall displacement osteotomy was simulated to make acetabular medial wall bone displace from 2 mm bone contact to 7 mm bone contact in the pelvic cavity. One experimental group was set at 1 mm intervals, totally 10 experimental groups. The acetabulum in each group was split into four quadrants. The prosthesis acetabulum-bone interface in each group was analyzed by computer simulation contrast mechanics experiment. The Mises stress and shear stress values were measured between acetabular prosthesis and bone interface. Results In groups 1, 5, 6, 9 and 10, the Mises stress was unevenly distributed in posterior inferior, anterior superior and anterior inferior quadrants. In groups 2, 3, 4, 7 and 8, the Mises stress was evenly distributed in posterior inferior, anterior superior and anterior inferior quadrants. Of them, the stress was most even in the group 4. In groups 2, 3, 4, 7 and 8, the shear stress was evenly distributed in the above-mentioned three quadrants. The shear stress was lowest in the groups 7 and 8. These indicate that joint force in the acetabulum mainly focused in the posterior superior quadrant. With the displacement of acetabular cup, the contact area of acetabular cup and bone would gradually increase, which finally increased the Mises stress in the contact surface. However, shear stress decreased with displacement of acetabular medial wall. Conclusion the suitable displacement range of acetabular medial wall osteotomy is 1 mm away from the pelvic cavity and 1 mm complete embolism in the pelvic cavity. The optimal position was 1 mm complete embolism in the pelvic cavity.