Fresh-frozen Cadaver Research Articles

Using robot technology to analyze forces and torques in tooth removal

This study aimed to capture both forces and torques exerted during tooth removal in clinically relevant dimensions and high detail. An ex vivo measuring setup was designed consisting of, amongst others, a compliant robot arm and a six-axis force/torque sensor. Fresh-frozen cadavers were used to match the clinical situation as closely as possible. Complete data was successfully recorded in 110 tooth removal experiments. The highest peak force was 99 N. An increase in forces in the dorsal region was objectified in both average and total forces exerted. Extrusion and buccal forces were found to be most dominant in both upper and lower jaw. A strong limitation exists in our scientific understanding of tooth removal procedures. In this study, for the first time, forces and torques are presented in high detail and in all (clinically relevant) dimensions. Despite the limited data size and ex vivo circumstances, the hereby-presented data show a reliable order of magnitude when considering forces in tooth removal and could serve as a benchmark for future research in this field. A better understanding of these procedures could aid in the development of evidence-based and improved educational material.

Mechanical ventilation during cardiopulmonary resuscitation: influence of positive end-expiratory pressure and head-torso elevation

BackgroundEfficient ventilation is important during cardiopulmonary resuscitation (CPR). Nevertheless, there is insufficient knowledge on how the patient’s position affects ventilatory parameters during mechanically assisted CPR. We studied ventilatory parameters at different positive end-expiratory pressure (PEEP) levels and when using an inspiratory impedance valve (ITD) during horizontal and head-up CPR (HUP-CPR). MethodsIn this human cadaver experimental study, we measured tidal volume (VT) and pressure during CPR at different randomized PEEP levels (0, 5 or 10 cmH2O) or with an ITD. CPR was performed, in the following order: horizontal (FLAT), at 18° and then at 35° head-thorax elevation. During the inspiratory phase we measured the net tidal volume (VT) adjusted to predicted body weight (VTPBW), reversed airflow (RAF), and maximum and minimum airway pressure (Pmax and Pmin). ResultsUsing ten thawed fresh-frozen cadavers we analyzed the inspiratory phase of 1843 respiratory cycles, 229 without CPR and 1614 with CPR. In a mixed linear model, thoracic position and PEEP significantly impacted VTPBW (p < 0.001 for each), and the insufflation time, thoracic position and PEEP significantly affected the RAF (p < 0.001 for each) and Pmax (p < 0.001). For Pmin, only PEEP was significant (p < 0.001). In subgroup analysis, at 35° VTPBW and Pmax were significantly reduced compared with the flat or 18° position. ConclusionWhen using mechanical ventilation during CPR, it seems that the PEEP level and patient position are important determinants of respiratory parameters. Moreover, tidal volume seems to be lower when the thorax is positioned at 35°.

ILIF ASSISTIDA POR ENDOSCOPIA POR VIA TRANSILÍACA: ESTUDO EM CADÁVER

ABSTRACT Objective: Demonstrate the feasibility of endoscopic assisted L5S1 intraforaminal lumbar interbody fusion (iLIF) through a transiliac approach. Methods: Ten transiliac iLIF and ten supra iliac iLIF were performed bilaterally at L5S1 in five randomly selected fresh-frozen human cadavers. The following measurements were recorded: distances from the transiliac track to the iliac crest, posterior superior iliac spine, and superior gluteal neurovascular bundle; pelvic parameters; approach angles; cage’s lateral and AP center point ratio (CPR); percentage of the cage crossing the midline in the AP and lateral views. Endplate integrity was assessed through endoscopic visualization. In addition, the facet joint, sacroiliac joint, iliolumbar ligament, and exiting and traversing nerve roots were checked for integrity through anatomic dissection. Results: In the transiliac technique, the axial and coronal approach angles were significantly decreased by 13.5º (95% CI -15.5; -11.5; p value&lt;0.001) and 13.2º (95% CI -15.3; -11.1; p value&lt;0.001), respectively, the sagittal approach angle was significantly increased by 5.4º (95% CI 1.8,8.9; p-value = 0.008), and the AP CPR was significantly higher (MD 0.16; 95% CI 0.12,0.20; p value&lt;0.001). The percentage of the cage crossing the AP view’s midline was increased by 31.6% (95% CI 19.8,43.4; p value&lt;0.001). The integrity of endplates, facet joints, sacroiliac joints, iliolumbar ligament, and exiting and traversing nerve roots was maintained. Conclusion: L5S1 transiliac iLIF is a feasible surgical technique. It allows a more centrally placed interbody cage in the coronal plane without compromising the anterior position in the lateral plane. The integrity of the major anatomic structures at risk was preserved. Evidence Level III: A case-control study.

Bi-Cortical transhumeral drilling for biceps tenodesis – Is it safe?

BackgroundBiceps tenodesis is an effective procedure performed to treat shoulder pain originating from the long head biceps tendon. In arthroscopic biceps tenodesis unicortical drilling of the humerus is more commonly practiced as it is considered safe to the vital structures lying posterior to the proximal humerus. Many surgeons are wary of the bi-cortical approach as it poses a risk to these vital structures. The aim of this study was to establish whether bi-cortical drilling in proximal humerus is safe or not. Our second purpose was to find a safe zone (if any) for bi-cortical drilling if bi-cortical drilling is safe. MethodsThis study is a descriptive study conducted on cadaveric shoulders. Bilateral shoulders and arms of ten fresh-frozen cadavers (mean age 77.7 y) were dissected. Four landmarks in the dissected humerus were identified. They were superior margin of the bicipital groove, center of the bicipital groove, upper and lower border of pectoralis major insertion. Bi-cortical trans-humeral pinning was done in the humerus at all these points so that the pin exited through the posterior cortex of the humerus. The shortest distance between the pin and the nearest vital structure namely axillary nerve, radial nerve, articular surface of the humeral head, and cephalic vein was calculated from each fixed landmark. ResultsWe established that bi-cortical drilling in proximal humerus was safe. The safe zone established for bi-cortical biceps tenodesis is at the middle of bicipital groove, which is 18.00 ± 4.02 mm inferior to the groove’s upper border. The boundaries of the safe zone lie 9.39 mm superiorly and 9.40 mm inferiorly to the middle of the bicipital groove. ConclusionThe center of the established safe zone for bi-cortical trans-humeral pinning was 18 mm inferior to the bicipital groove’s upper border.

Estimating the location of the posterior interosseus nerve during an extensor digitorum communis-splitting approach: a comparison of methods using the transepicondylar distance.

The posterior interosseus nerve (PIN) may be encountered when using the extensile extensor digitorum communis (EDC)-splitting approach to the elbow. An accurate means of estimating its location remains elusive. The purpose of this investigation is to identify whether the methods described in previous studies can be improved upon to more accurately estimate the PIN's location using the transepicondylar distance (TED). Forty-five fresh-frozen cadavers were dissected using the EDC-splitting approach. Method A (N=39) used an electronic caliper measuring along the midlateral border of the radius from the lateral epicondyle (LE) and radiocapitellar joint in supination, neutral position, and pronation. Method B (N=16) used a sterile tape measure, measuring from the LE in pronation only along an axis from the LE to Lister's tubercle passing through the center capitellum. In method A, the mean TED was 63.4±6.1 mm. Of the 6 measurements, the TED was most correlated to the actual distance to the PIN from the LE in pronation (68.3±7.3 mm; R2=0.266). The median difference between the estimated and actual distances was -5.6 mm (-19.3 mm to 7.6 mm). In method B, the mean TED was 68.4±8.7 mm, and the mean measured distance from the LE in pronation was 68.7±9.4 mm. The TED closely correlated with the measured distance to the PIN (R2=0.95, P<.001). The mean difference between the estimated and actual distances was ±2.0 mm (range -4.0 mm to2.0 mm), significantly more precise than method A (P=.007). Using a tape measure, the TED predicted the PIN's location within a mean ±2 mm in pronation along an axis from the LE to Lister's tubercle, using an EDC-splitting approach. This technique is simple and comparatively more accurate than those used previously.

Evaluation of an Injectable Biphasic Calcium Sulfate/Hydroxyapatite Cement for the Augmentation of Fenestrated Pedicle Screws in Osteoporotic Vertebrae: A Biomechanical Cadaver Study.

Cement augmentation of pedicle screws is one of the most promising approaches to enhance the anchoring of screws in the osteoporotic spine. To date, there is no ideal cement for pedicle screw augmentation. The purpose of this study was to investigate whether an injectable, bioactive, and degradable calcium sulfate/hydroxyapatite (CaS/HA) cement could increase the maximum pull-out force of pedicle screws in osteoporotic vertebrae. Herein, 17 osteoporotic thoracic and lumbar vertebrae were obtained from a single fresh-frozen human cadaver and instrumented with fenestrated pedicle screws. The right screw in each vertebra was augmented with CaS/HA cement and the un-augmented left side served as a paired control. The cement distribution, interdigitation ability, and cement leakage were evaluated using radiographs. Furthermore, pull-out testing was used to evaluate the immediate mechanical effect of CaS/HA augmentation on the pedicle screws. The CaS/HA cement presented good distribution and interdigitation ability without leakage into the spinal canal. Augmentation significantly enhanced the maximum pull-out force of the pedicle screw in which the augmented side was 39.0% higher than the pedicle-screw-alone side. Therefore, the novel biodegradable biphasic CaS/HA cement could be a promising material for pedicle screw augmentation in the osteoporotic spine.

A new skin flap from the zygomaticotemporal region: Anatomical study and clinical application to eyelid reconstruction.

Eyelid reconstruction is a demanding task faced by plastic surgeons. Island flaps from the zygomaticotemporal region, where the zygomatico-orbital artery predominates in vascularization, represent the recent local approaches to this problem. Questions exist as to where and on what element the flap should be based, and whether or not they should be adapted in relation to the behavior of the zygomatico-orbital artery. A total of 22 fresh-frozen adult cadaver heads were employed. The fasciocutaneous perforators of the zygomatico-orbital artery and their anastomoses with the surrounding arteries, especially those in the upper palpebra, were investigated. On this basis, a distally based perforator flap was created and executed for eyelid reconstruction in 7 patients. The zygomatico-orbital artery was interconnected through its perforators with the subdermal plexus over the zygomaticotemporal region and with the arteries in the surroundings. The transverse facial artery took the place of zygomatico-orbital artery where it was absent. Both the arteries anastomosed consistently with the superficial orbital arcade at a predictable site. All 7 flaps survived completely. A new distally based perforator flap from the zygomaticotemporal region is described regarding its anatomical basis and clinical applications to eyelid reconstruction. With a vascular axis consistently present and a pivot adjacent to the defects, the flap is more reliable in vascularization, and less harm to its donor site than orbicularis oculi myocutaneous flaps, and poses no concern about whether the zygomatico-orbital artery is present or not.

Metacarpal Shortening with Intramedullary Screw Fixation: A Cadaveric Study.

Background Intramedullary screw fixation is a commonly used technique for the management of metacarpal fractures. However, compression across the fracture site can lead to unintentional shortening of the metacarpal. Questions/Purposes Our aim was to evaluate the risk of overshortening with differing intramedullary device designs for fixation of metacarpals. Methods The small finger metacarpal of nine fresh-frozen cadavers were included. A metacarpal neck fracture was simulated with a 5-mm osteotomy. Three different intramedullary screw designs were compared. Each screw was placed in a retrograde fashion into the intramedullary canal and the amount of shortening measured. Screws were reversed and the number of reverse turns with the screwdriver needed to release overshortening were measured. Results The average shortening at the osteotomy site was 2.5 mm. The mean shortening was 80%, 58%, and 12% for the partially threaded screw, fully threaded screw, and threaded nail, respectively. The mean differences of the distance shortened were statistically significant for the threaded nail compared with the partially and fully threaded screws. The partially threaded screw had the most shortening, while the threaded nail provided the least amount of shortening. When the screws were reversed, the screws did not disengage until the screw was fully removed from the osteotomy site. Conclusion The fully threaded nail demonstrates less shortening and possibly minimizes overshortening of fractures compared with partially threaded and fully threaded screw designs. Overshortening cannot be corrected by unscrewing the screw unless completely removed from the distal fragment. Clinical Relevance Orthopaedic surgeons may select intermedullary screws based on the design that is suited for the particular metacarpal fracture pattern.

Latarjet coracoid transfer vs. distal clavicle autograft for anterior shoulder instability with glenoid bone loss: A biomechanical comparison of two graft reconstructions in various medial to lateral positions

While the consensus of optimal positioning of the transferred coracoid, no biomechanical study has established if the position differs for other bone block types. To compare the effect of distal clavicle autograft and coracoid autograft alignment and medialization on glenohumeral stability. Eight Fresh-frozen cadaver shoulders comprised of the scapula and proximal humerus were tested. The cadavers were tested while positioning both grafts, the distal clavicle autograft and coracoid graft, consecutively at 0 mm, 4 mm and 8 mm medially. Each experiment comprised of maximum external rotation and glenohumeral abduction of 60° while applying a constant, 50 N medial compressive force via a pneumatic actuator to the humerus under all conditions. The starting position was determined by the humeral head being seated at its most medial position on the glenoid surface. The conjoint tendon was routed through a split in subscapularis and loaded with a 5N weight using a pulley system for all Latarjet trials to simulate the sling effect. Clavicle grafts at all offsets showed a statistically significant decrease in the stability ratio versus the intact condition. Within the clavicle graft conditions, the 4 mm clavicle offset had a significantly lower stability ratio versus the 0 mm clavicle offset and a significantly higher stability ratio than the 8 mm offset. The clavicle 8 mm offset graft had a significantly lower stability ratio than the 0 mm offset position. The Latarjet graft with 0 mm of medial offset showed no statistically significant difference in stability ratio when normalized at 10 mm of anterior displacement relative to the intact glenoid condition, while the 4 mm and 8 mm medial offset Latarjet conditions had significantly lower stability ratios versus the intact condition. Within the Latarjet graft positions, the stability ratio of the 4 mm medial offset had no statistically significant difference than the 0 mm offset. In shoulders with anterior glenoid bone loss, the Latarjet procedure and transfer of an osteoarticular distal clavicle autograft seem to be biomechanically sound if placed flush with the glenoid. Medialization of 4 mm provides acceptable restoration of shoulder stability when a Latarjet procedure is used but not for a distal clavicle autograft.

Alternative Path for Optic Nerve Decompression in Pseudotumor Cerebri With Full Endoscopic Lateral Transorbital Approach.

Endonasal endoscopic approaches are the most preferred surgical methods in patients with pseudotumor cerebri because of easy access to the optic nerve, but the choice of this technique may not apply to all endoscopic endonasal cases. Moreover, there may be difficulties in practice in some cases, including the coronavirus disease 2019 pandemic. This study aimed to suggest an alternative endoscopic approach by lateral orbitotomy for optic nerve decompression in patients with pseudotumor cerebri. The study was performed using 5 fresh-frozen cadaver heads (bilaterally, total of 10 sides) injected intravenously with colored silicone preserved in the cold chain. An average of 2.5 cm skin incision was made to fit the lateral orbitotomy. The lengths of the recurrent meningeal artery (mm), the meningo-orbital band (mm), and the optic nerve (mm) to the orbital margin were measured. After these morphometric measurements, optic nerve decompression was performed endoscopically, and the length of the decompression was measured (mm). The average length (mm) between the orbital rim and meningeal recurrent artery (or meningolacrimal branch) was 16.2mm, between the orbital rim and the meningo-orbital band was 18.5mm, and between the orbital rim and optic nerve was 44.1mm. The average optic nerve decompression length was 4.4mm. The endoscopic lateral orbitotomy approach provides easy access to the optic nerve by anatomically following the recurrent meningeal artery and the meningo-orbital band. It can be a safe second-line approach after endonasal approaches for optic nerve decompression in pseudotumor cerebri.

Biomechanical Evaluation of a Novel Expandable Vertebral Augmentation System Using Human Cadaveric Vertebrae

Unacceptable sagittal alignment and cement leakage are major concerns of percutaneous vertebroplasty when treating patients with painful vertebral osteoporotic compression fractures. To maintain the restored vertebral height and reduce the reliance on cement as the major stabilizer, an expandable vertebral augment system (EVA®) made of titanium alloy consisting of a rigid tube encased by a barrel with an anterior expansion mechanism was developed. The aim of the current study was to determine whether this novel design is as effective as existing procedures in terms of height restoration and biomechanical performance. Eight osteoporotic vertebrae (T12-L3) confirmed by dual-energy X-ray absorptiometry from two fresh-frozen human cadavers (70- and 72-year-old females) were used. Twenty-five percent reduced anterior wedge vertebral compression fractures were created using a material testing machine. Four randomized specimens were augmented with EVA® (Chang Gu Biotechnology Co. Ltd., Taipei city, Taiwan), and another four randomized specimens were augmented with OsseoFix® (AlphaTec Spine Inc., Carlsbad, CA, USA). The implant size and cement volume were controlled. The anterior vertebral body height (VBH) ratio and pre/postaugmented ultimate strength and stiffness were measured and compared. The mean anterior VBH restoration ratio was 8.54% in the EVA® group and 8.26% in the OsseoFix® groups. A significant difference from augmentation was measured in both groups (p &lt; 0.05), but there was no significant difference between the EVA® and OsseoFix® groups in anterior VBH restoration. The ultimate strengths of the EVA® and OsseoFix® groups were 6071.4 ± 352.6 N and 6262.9 ± 529.2 N, respectively, both of which were statistically significantly higher than that of the intact group (4589.9 ± 474.6 N) (p &lt; 0.05). The stiffnesses of the EVA®, OsseoFix®, and intact groups were 1087.2 ± 176.9, 1154.9 ± 168.9, and 1637.3 ± 340.8 N/mm, respectively, indicating that the stiffness was significantly higher in the intact group than in both the EVA® and OsseoFix® groups (p &lt; 0.05). No significant differences were observed between the two augmentation procedures in height restoration or ultimate strength and stiffness. This novel EVA® system showed comparable height restoration and biomechanical performance to those of existing implants for human cadaveric osteoporotic compression fractures. Potential advantages of preventing cement posterior leakage and promoting cement interdigitation are expected with this ameliorated design.

Screw placement in arthroscopically assisted osteosynthesis of radial head fractures using a reference k-wire in the radiocapitellar joint: a cadaveric study

PurposeThe optimal screw placement in arthroscopically assisted fixation of radial head fractures is still an issue and no guiding methods have been evaluated in the recent literature. The study hypothesis was that using a “reference k-wire” percutaneously inserted in and parallel to the radiocapitellar joint would enable to achieve a trajectory more parallel to the radial head articular surface as compared to a free-hand k-wire placement.MethodsArthroscopically assisted placement of a k-wire in the radial head was performed in seven fresh-frozen human cadaver specimens by three surgeons. Three different techniques were evaluated: freehand drilling (technique A), placement using a “reference” k-wire in the radiocapitellar joint as a reference without (technique B), and with the AO parallel k-wire guide (technique C). Radiographs from all procedures were obtained and the inclination angle “α” between the k-wire and the articular surface of the radial head was measured and compared among the techniques.ResultsAngles of 84 radiographs were obtained and showed a mean α angle of 30.1° ± 13° for technique A, 5.7° ± 4.5° for technique B, and 5.4° ± 3.7° for technique C. The angle α was significantly higher with technique A as compared to B (p < 0.0001) and C (p < 0.0001). There was no difference between methods B and C (n.s.). No difference was observed among the surgeons for all three methods (p = 0.66).ConclusionWith the use of an additional “reference” k-wire placed in the radiocapitellar joint, the guiding k-wire for screw drilling can be placed almost parallel to the radial head joint line with limited variability and a good reproducibility during arthroscopically assisted radial head fracture fixation.Clinical relevanceThe here-presented method of an additional, percutaneous introduced “reference” k-wire is easily applicable and helpful to achieve parallel screw placement during arthroscopically assisted radial head fracture fixation.Level of evidenceIV, biomechanical cadaver study

Computed Tomography Scan vs Saline Load Test in the Detection of Traumatic Arthrotomies of the Ankle: A Cadaveric Study

Category: Trauma Introduction/Purpose: The diagnosis of traumatic arthrotomy is typically made through a saline load test (SLT), though there has been a growing base of literature regarding the use of computed tomography (CT) scan in various joints for diagnosis. To date, there has been little data supporting the use of CT to diagnose traumatic arthrotomy of the ankle. Through simulated arthrotomies of the ankle in cadavers, we aim to assess the sensitivity and ability of CT for diagnosing traumatic arthrotomy. SLT were also performed in each specimen to determine the volume of saline needed for diagnosis. Methods: Six fresh-frozen cadavers with twelve ankles were initially included in this study. The presence of intra-articular air prior to arthrotomy was excluded with a baseline CT scan. Ankles underwent arthrotomy at the anterolateral, anteromedial, posteromedial, posterolateral portals with fluoroscopic guidance. A subsequent CT scan was obtained to identify the presence of intra-articular air. Ankles then underwent SLT and volumes resulting in extravasation were recorded. Results: Eleven ankles were included, with one exclusion due to the presence of implants. Arthrotomies were made in three ankles at the anterolateral portal, three at the anteromedial portal, two at the posteromedial portal, and three at the posterolateral portal. Following arthrotomy, intra-articular air was detected in all eleven ankles by CT scan. All eleven ankles were subjected to SLT, with each demonstrating extravasation through the arthrotomy site. The mean volume of saline needed for extravasation was 7.7 mL, with a range of 3 to 22 mL and a standard deviation of 5.4. Conclusion: CT scan was demonstrated to be sensitive and effective in diagnosing traumatic arthrotomy in a cadaveric model.

Vascular Supply to the Proximal Plantar Plate of Lesser Toe Metatarsophalangeal Joint is Primarily Supplied by the Attachment to the Metatarsal: A Nano-CT Microvasculature Study

Category: Lesser Toes Introduction/Purpose: Lesser toe metatarsophalangeal (MTP) instability is implicated in common forefoot pain and deformities. The plantar plate is a major stabilizing structure of the MTP joint with instability frequently occurring after a tear or attenuation of this structure. Previous studies have demonstrated that the blood supply to the proximal plantar plate comes from both the metatarsal and the plantar fascia. Commonly, a McGlamry elevator is used to strip the plantar plate from the plantar surface of the metatarsal to improve exposure of the MTP joint. The vascular consequence of stripping the plantar plate from the metatarsal is not yet well understood. The purpose of this study is to quantify the relative contribution of blood supply to the proximal plantar plate from the metatarsal and plantar fascia. Methods: Twelve fresh-frozen human adult cadaver lower extremity specimens were utilized for this study, resulting in 35 lesser MTP joints that were studied. All specimens were between the ages of 18 and 65 years and had no history of diabetes, peripheral vascular disease, or connective tissue disorders. Specimens with a history of trauma to the foot or ankle, prior foot or ankle surgery, or evidence of clinical deformity of less toes upon inspection were excluded. The specimens were prepared as described previously in Finney et al. The anterior and posterior tibial arteries were perfused with a barium solution and counterstained with phosphomolybdic acid. The second through fourth MTP joints of 12 feet were imaged with nano-computed tomography (nano- CT) at 14-micron resolution. Reconstructed 3D and 2D CT images were utilized for analysis of the volume of vasculature along the metatarsal pedicle and plantar fascia of the proximal plantar plate. Results: Based on nano-CT imaging, the plantar plate specimen demonstrated microvascular infiltration at the proximal attachments of the metatarsal neck, interosseous muscles, periosteum, and plantar fascia (Figure 1). An average of 63.5% of the vascular supply to the proximal portion of the plantar plate entered from the metatarsal pedicle in 35 lesser toe specimens analyzed. The remaining 36.5% of the vascular supply entered from the plantar fascia. The second toes, third toes, and fourth toes had an average of 64.7%, 59.0%, and 67.1% of vasculature supply from the metatarsal pedicle, respectively. The average volume of vasculature from the metatarsal pedicle to the proximal plantar plate was 0.38 mm3, while the average volume of vasculature from the plantar fascia to the proximal plantar plate was 0.19 mm3. Conclusion: The vascular supply of the proximal plantar plate is supplied from both the metatarsal pedicle and plantar fascia. Using the McGlamry elevator for exposure of the MTP joint disrupts the dominant tributary for proximal plantar plate perfusion.

Biomechanical Study of Syndesmotic Stability in AITFL and PITFL Injury Models

Category: Basic Sciences/Biologics; Trauma Introduction/Purpose: Severe ankle syndesmotic injuries can cause not only anterior inferior tibiofibular ligament (AITFL) injury but also posterior inferior tibiofibular ligament (PITFL) injury. However, the biomechanical stability and the best surgical treatment method for PITFL injuries are unknown. This study aimed to evaluate the stability of AITFL and PITFL injury models and the treatment models with suture-button (SB) fixation, AITFL augmentation with suture-tape (aST), and PITFL augmentation with suture-tape (pST). We hypothesized that PITFL injury causes posterior instability of syndesmosis and that this can be stabilized with pST fixation Methods: This study was approved by our institution's ethics review board. Ten normal fresh-frozen cadaver legs (4 males and 6 females) that were donated to our university's department of anatomy were used. The specimens were tested with the application of traction and rotational forces for dorsiflexion and external and internal rotation of the ankle joint. The fibular rotational angle related to the tibia (FRA), anterior tibiofibular diastasis (aTFD), and posterior tibiofibular diastasis (pTFD) were measured using the magnetic tracking system. Intact, injured (AITFL, PITFL and IOM resection), SB fixation, SB + aST fixation, and SB + aST + pST fixation models were made and loaded with forces. One-way ANOVA was used to evaluate the relationship between the models. Post-hoc analysis of the differences between the models was performed using Dunnett's test. A p value of 0.05 was chosen as the level of significance. Results: In the injured model, both FRA and TFD were significantly increased compared with those of the intact model in all directions. In the SB fixation model, only FRA with an external rotation force was significantly increased compared with that of the intact model. In the SB+aST model, both FRA and aTFD were not significantly different from those in the intact model. Conclusion: The results of this study showed that there was external and internal rotational instability in the AITFL and PITFL injury models, while there was stability in the SB + aST model. SB fixation alone did not reduce FRA with an external rotation force and there was no significantly different FRA with an internal rotation force. With SB fixation alone, anterior instability was found to be greater than posterior stability, while aST fixation was associated with anterior stability. In this study, the change in syndesmosis stability after pST fixation was found to be restrictive.

Optimal Position of the Bone Anchor for the Internal Brace Suspensionplasty Technique for Thumb Basal Joint Arthroplasty

Ligament reconstruction and tendon interposition is a common technique for thumb basal joint arthroplasty. Recently, a variation of this technique, a suture suspensionplasty, has been introduced. The goal of our study was to assess the optimal position of the bone anchor in the thumb metacarpal. We hypothesized that an anchor placed in the radial aspect of the thumb metacarpal base would provide improved stability and resist subsidence more effectively than an ulnar-based thumb anchor. Eight fresh-frozen cadaver arms were imaged fluoroscopically in anteroposterior and lateral views centered over the thumb carpometacarpal joint before and after trapeziectomy and after the placement of radial-based and ulnar-based bone anchors. The intermetacarpal angle between the thumb and index metacarpals was measured on all images after the application of a standard force. Radial abduction, opposition, subsidence, palmar abduction, and adduction were measured. Subsidence was calculated as the percentage loss of the trapezial space. Both radially and ulnarly placed internal brace constructs allowed more radial abduction, opposition, and palmar abduction than the pretrapeziectomy constructs. They both also reduced subsidence by approximately 20% to 29% compared with the posttrapeziectomy constructs. Comparing radial to ulnar constructs, motion and subsidence were similar. There was immediate stability of the thumb with respect to axial load and subsidence after anchor placement, and this was independent of the anchor position. The position of the bone anchor in the thumb metacarpal base did not affect the range of motion. Although the device can limit subsidence, it does not appear to restrict any range of motion of the thumb, irrespective of anchor position. This cadaver study can help hand surgeons understand the effect of positioning of bone anchors when performing a specific suture suspensionplasty technique.

Relevant landmarks to navigate the suture locations for the arthroscopic triangular fibrocartilage complex foveal reattachment.

Key step of arthroscopic triangular fibrocartilage complex (TFCC) foveal reattachment is to suture dorsal and palmar deep components of radioulnar ligaments (RULs) to the fovea of ulnar head to ensure distal radioulnar joint stability. However, the deep components are covered and cannot be identified arthroscopically from standard radiocarpal joint view. Suturing sites described in previous studies have not been proved gasping of the deep components. The purpose of this study was to investigate our TFCC suture locations using relevant landmarks on securing the RULs' deep components for arthroscopic TFCC foveal reattachment. Wrist arthroscopy and horizontal mattress suture was performed in 20 fresh-frozen cadaver wrists. Based on close proximity of the ulnocarpal ligaments to the palmar RUL and fovea, palmar suture location was designated at the junction between ulnolunate, ulnotriquetral ligaments and palmar border of TFCC disc, whereas dorsal suture location was at dorsal border of TFCC disc, opposite the palmar location, at same distance between prestyloid recess and palmar location. The radiocarpal and ulnocarpal joint was subsequently opened to evaluate grasping of RULs' deep components and evaluate the relevant landmarks. Thirty-nine of 40 (97%) RULs' deep components were successfully grasped by the sutures. With 0.98-0.99 interobserver agreement for the measurements, mean distance between sigmoid notch to suture and suture to ulnar capsule were 5.6 ± 1.1 and 4.0 ± 0.9mm, respectively. Whereas, the dissecting point of deep component from the superficial component of the RULs was detected immediately radial to the midpoint between the sigmoid notch and the ulnar capsule (4.5 ± 0.9mm from sigmoid notch). We determined the relevant anatomical landmarks to navigate the TFCC suture locations, which reliably secure the deep components of the radioulnar ligaments for the arthroscopic TFCC foveal reattachment.

A Multiclass Classification Model for Tooth Removal Procedures

Surprisingly little is known about tooth removal procedures. This might be due to the difficulty of gaining reliable data on these procedures. To improve our understanding of these procedures, machine learning techniques were used to design a multiclass classification model of tooth removal based on force, torque, and movement data recorded during tooth removal. A measurement setup consisting of, among others, robot technology was used to gather high-quality data on forces, torques, and movement in clinically relevant dimensions. Fresh-frozen cadavers were used to match the clinical situation as closely as possible. Clinically interpretable variables or “features” were engineered and feature selection took place to process the data. A Gaussian naive Bayes model was trained to classify tooth removal procedures. Data of 110 successful tooth removal experiments were available to train the model. Out of 75 clinically designed features, 33 were selected for the classification model. The overall accuracy of the classification model in 4 random subsamples of data was 86% in the training set and 54% in the test set. In 95% and 88%, respectively, the model correctly classified the (upper or lower) jaw and either the right class or a class of neighboring teeth. This article discusses the design and performance of a multiclass classification model for tooth removal. Despite the relatively small data set, the quality of the data was sufficient to develop a first model with reasonable performance. The results of the feature engineering, selection process, and the classification model itself can be considered a strong first step toward a better understanding of these complex procedures. It has the potential to aid in the development of evidence-based educational material and clinical guidelines in the near future.

Biomechanics of Transforaminal Endoscopic Approaches.

Biomechanical cadaveric study. The aim of this study was to compare the effect of transforaminal endoscopic approaches with open decompression procedures. Clinical studies have repeatedly highlighted the benefits of endoscopic decompression, however, the biomechanical effects of endoscopic approaches (with and without injury to the disk) have not been studied up to now. Twelve spinal segments originating from four fresh-frozen cadavers were biomechanically tested in a load-controlled endoscopic transforaminal approach study. Segmental range of motion (ROM) after endoscopic approach was compared with segmental ROM after (1) microsurgical decompression with unilateral laminotomy and (2) midline decompression with bilateral laminotomy. In the intact state and after decompression, the segments were loaded in flexion-extension (FE), lateral shear (LS), lateral bending (LB), anterior shear (AS), and axial rotation (AR). Vertebral segment ROM was comparable between the two endoscopic transforaminal approaches. However, there was a-statistically nonsignificant-trend for a larger ROM after accessing via the inside-out technique: FE: +3% versus +7%, P =0.484; LS: +1% versus +12%, P =0.18; LB: +0.6% versus +9%, P =0.18; AS: +2% versus +11%, P =0.31; AR: -4% versus +5%, P =0.18. No significant difference in vertebral segment ROM was seen between the transforaminal endoscopic approaches and open unilateral decompression. Vertebral segment ROM was significantly smaller with the transforaminal endoscopic approaches compared with midline decompression for almost all loading scenarios: FE: +4% versus +17%, P =0.005; AS: +6% versus 21%, P =0.007; AR: 0% versus +24%, P =0.002. The transforaminal endoscopic intracanal technique preserves the native ROM of lumbar vertebral segments and shows a trend toward relative biomechanical superiority over the inside-out technique and open decompression procedures.

The Effect of an Additional Core Suture During Pulvertaft Tendon Repair: A Fresh-Frozen Cadaver Study

Pulvertaft tendon repair is a strong suture technique; however, proper tendon tension is impaired by repair site elongation. Therefore, methods to reduce postoperative elongation are warranted. This study aimed to determine the effects of additional core sutures during Pulvertaft tendon repair on repair site elongation and rupture strength. A total of 48 finger extensor tendons were harvested from fresh-frozen cadavers, and tendons with similar diameters were paired. The 24 pairs of tendons were divided into the following 4 groups: group I, 3 interlaced weaves only; group II, 3 interlaced weaves and 2 core suture strands with 4-0 nylon; group III, 3 interlaced weaves and 2 core suture strands with 4-0 FiberWire; and group IV, 4 interlaced weaves only. Each sutured tendon was placed in a Universal Testing Machine, and repair site elongation after repeated traction loads and rupture strength were measured. The mean elongation values were 2.74 ± 0.84 mm, 1.80 ± 0.16 mm, 1.60 ± 0.18 mm, and 1.92 ± 0.18 mm for groups I, II, III, and IV, respectively. The elongation values were significantly lower in groups II, III, and IV than in group I. The mean rupture strengths were 64.9 ± 16.0 N, 94.8 ± 17.2 N, 110.9 ± 21.3 N, and 104.9 ± 17.5 N for groups I, II, III, and IV, respectively. Rupture strengths were significantly higher for groups III and IV than for group I. After adding core sutures during Pulvertaft tendon repair, the elongation amount decreased, and the rupture strength improved. The study showed the effect of additional core sutures during Pulvertaft tendon repair, suggesting that it could be useful in reducing postoperative tendon elongation when extensor tendon transfers are performed.