Three-dimensional templating arthroplasty of the humeral head

Background

No anatomical study has been conducted over Asian population to design humeral head prosthesis for the population concerned. This study was done to evaluate the accuracy of commercially available humeral head prosthetic designs, in replicating the humeral head anatomy.

Methods

CT scan data of 48 patients were taken and their 3D CAD models were generated. Then, humeral head prosthetic design of a BF shoulder system produced by a standardized, commercially available company (Zimmer) was used for templating shoulder arthroplasty and the humeral head size having the perfect fit was assessed. These data were compared with the available data in the literature.

Results

All the humeral heads were perfectly matched by one of the sizes available. The average head size was 48.5 mm and the average head thickness was 23.5 mm. The results matched reasonably well with the available data in the literature.

Conclusions

The humeral head anatomy can be recreated reasonably well by the commercially available humeral head prosthetic designs and sizes. Their dimensions are similar to that of the published literature.     

Morphometry of typical cervical vertebrae on dry bones and CT scan and its implications in transpedicular screw placement surgery

Background

Transpedicular stabilization of subaxial cervical spine is a very delicate procedure that requires thorough understanding of the pedicle anatomy to minimize the rate of neurovascular complications. The current study was conducted to investigate the morphometric details including dimensions and axis of typical cervical vertebrae (C3–C6) for transpedicular screw insertion surgery.

Methods

The current study was conducted on 100 sides of 50 dry and 160 sides of 80 vertebrae on computerized tomography scans of typical cervical vertebrae. Parameters that were studied bilaterally included distance between medial aspect of the pedicle and dural sac, pedicle height, pedicle width, interpedicular distance, lateral and medial cortical thickness, transverse pedicle angle and chord length.

Results

Distance between medial aspect of the pedicle and dural sac was found to be 2.2 ± 0.99 mm. Mean pedicle height (6.5 ± 1.1 mm) was found to be greater than pedicle width (4.9 ± 0.9 mm) in all the vertebrae. Mean transverse pedicle angle and chord length was observed to be 39.4° and 32.1 mm, respectively. Mean interpedicular distance, medial and lateral cortical thickness was observed to be 21.8 ± 1.6, 1.43 ± 0.4 and 0.79 ± 0.2 mm, respectively.

Conclusions

The present study highlights a three-dimensional orientation of subaxial cervical pedicle anatomy, while emphasizing the risks involved in the view of comparatively smaller values of pedicle dimensions of subaxial cervical vertebrae. This knowledge about typical cervical vertebrae, its pedicle and their adjacent neurovascular structures may enhance the safety of transpedicular screw insertion.     

Anatomy and surgical landmarks for the ansa pectoralis: application to pectoralis major nerve selective neurotomy

Background

Ansa pectoralis neurotomy is a surgical approach in the treatment of the pectoralis major muscle spasticity causing an attitude in adduction and internal rotation of the shoulder.

Objective

To establish the anatomical landmarks allowing an easier localisation of the ansa pectoralis during neurotomy.

Material and methods

Fifteen adult human cadavers (10 embalmed and 5 fresh) were dissected in order to determine anatomical landmarks allowing an easier localization of the ansa pectoralis during neurotomy.

Results

In all the cadavers, the lateral pectoral nerve arose from the lateral cord of the brachial plexus, 0.2 cm above to 1.5 cm below the inferior border of the clavicle with a mean distance of 0.76 cm for left and right side, whereas the medial pectoral nerve arose from the medial cord of the brachial plexus, 0.7–2.3 cm below the inferior border of the clavicle with a mean distance of 0.61 cm for the left side and 0.68 cm for the right side. We systematically found both the origin of pectoral nerves and the ansa pectoralis at the level of the middle third of the distance between the sternoclavicular and the acromioclavicular joints. Moreover, ansa pectoralis was constantly localized lateral to the thoracoacromial artery. In four cases, the division of the lateral pectoral nerve was not found. In one case, medial pectoral nerve did not exist.

Conclusion

Ansa pectoralis can be found by a curved incision made at the mid-third of the distance between the sternoclavicular and the acromioclavicular joints, the medial point being located just below the lower edge of the clavicle and the lateral point 2 cm below the inferior edge of the clavicle.     

Glenohumeral relationship in maximum elevation

Purpose

The purpose of this study was to clarify rotational relationships between the anatomical landmarks of the glenohumeral joint in maximum elevation.

Methods

Twenty-five healthy volunteers (20 men, 5 women; mean age, 31 years) held the arm in maximum elevation in an open MRI system. In each three-dimensionally computer-generated image, elevation angle of the humerus in the plane of elevation was measured, based on the glenoid and the scapular planes. Using the equator set on the head surface by the plane parallel to the humeral axis, involving the head center and the bicipital groove, glenoid location and rotational relationships were investigated.

Results

The elevation angle was 102° ± 9° in the plane 7° ± 8° anterior to the scapular plane, and axial rotation was fixed with the glenoidal long axis parallel to the equator (within 2°). Each glenoid center located on antero-superior portion of the humeral head, and the direction from the top of the head to its location was the same as that of the shaft tilting, indicating the glenoid only translated without rotation after reaching the top of the head on the equator.

Conclusions

Before reaching maximum elevation, the glenohumeral joint would be locked in axial rotation. The position when the glenoid is on the top of the humeral head with the humeral shaft perpendicular to the glenoid is considered to be essentially the final position of elevation, above which the glenohumeral joint only translates without axial rotation even if the humerus is more elevated.     

Anatomical study of the medial patello-femoral ligament: landmarks for its surgical reconstruction

Purpose

The aim of this dissection study was to describe the anatomical insertions of the medial patello-femoral ligament (MPFL), and to assess its relationship with surrounding structures to improve its surgical reconstruction.

Methods

Twelve knees (7 cadavers) were included for the study. Measurements and general features of the MPFL were assessed: lengths, widths and insertions.

Results

The MPFL was found in all knees, presenting a triangular shape, and extending from the medial part of the patella to its femoral insertion (its length was of 59 ± 6.6 mm), distal to the adductor tubercle. The mean femoral insertion of the MPFL was 7.2 ± 2.7 mm proximal and 7.4 ± 4.0 mm posterior to the medial femoral epicondyle (MFE). It was also at a mean 11 ± 2.8 mm distal and 1.3 ± 2.1 mm posterior to the adductor tubercle, and 22 ± 6.4 mm anterior to the posterior condyle. We did not find any double-bundle organization on the patellar insertion. The width of the MPFL was 8.8 ± 2.9 mm at the femoral insertion, 27 ± 5.9 mm at the patellar insertion, and 12 ± 3.1 mm in the middle of the MPFL. The vastus medialis obliquus was found to be inserted on the superior part of the MPFL.

Conclusion

The adductor tubercle appeared to be a better landmark than the MFE for the femoral tunnel positioning during surgical reconstructions of the MPFL because it was easier to identify and its relationship with the femoral insertion of the MPFL was constant (10 mm below).     

旋肱前血管外侧降支为蒂肱骨上段骨膜瓣的应用解剖

目的：为带旋肱前动脉外侧降支为蒂的肱骨上段外侧面骨膜瓣痊术提供解剖依据：方法：在３８侧经动脉环绕色乳胶的成人上肢标本上对旋肱前上侧降支的来源、走行、分布进行了了解剖学观测,并在４侧标本上不幕拟手术实验。结果：旋肱前动脉经 肱肌和肱二头肌短头深面,绒上科颈外进至结节间沟外侧缘分别分出升支和降支。升支上行分布于肱骨头和小结节部。降支有２条分别沿胸大肌止腱内、个侧紧贴骨膜下行,为内侧降支和外侧降支。外侧     

Is there a relationship between symptoms of patients and tomographic characteristics of styloid process?

Objectives

To investigate the angulations and length of the styloid process (SP) on three-dimensional computed tomography (3D-CT) images between the patients having elongated SP complaints and those without any stylalgia symptoms.

Patients and methods

One hundred patients underwent 3D-CT evaluation of the bilateral temporomandibular joints to investigate for symptomatic elongated styloid process (ESP) at our institution. The differences between the mean angulations and lengths of the SP and comparisons between patient and control groups were analyzed by student t test.

Results

In study group, mean length of styloid processes was 40.7 ± 10.8 mm on the right and 40.3 ± 10.9 mm on the left. Mean medial angles of SP were measured as 22.60 ± 4.0 on the right side and 22.60 ± 4.5 on the left side. In the same group, mean anterior angles of SP were 16.10 ± 6.9 on the right and 16.70 ± 7.1 on the left side. The “in-group” comparisons of lengths, medial and anterior angles did not produce statistically significant results. The comparison of medial angulations between the symptomatic and asymptomatic patients was the only statistically meaningful result in our study.

Conclusion

3D-CT has several advantages according to conventional tomography for visualization of head and neck anatomy. The increase of medial angulation of SP may be responsible for the development of complaints in ESP.     

Arterial supply of the distal humerus

Purpose

Distal humeral fractures are rare, but severe injuries, the treatment of which is often accompanied by serious complications and its outcome strongly depends on the quality of surgical therapy. Non-union is a common entity, compromising clinical results and requiring revision surgery. Osteonecrosis is an underestimated etiologic factor in the development of non-union. The present study aims to display the distribution patterns of the arterial vessels at the distal humerus, to correlate the displayed vessels with local nutrient foramina and to disclose an endangerment of these structures by common osteosynthetic implants.

Methods

Eight plastinated fresh frozen upper extremities were digitally analyzed regarding the vascular density of the cancellous bone, by calculating the ratio of area comprised by arterial vessels and the area comprised by cancellous bone on sagittal cuts of the distal humerus. Possible differences in the vascular density of the medial epicondylar region, the lateral epicondylar region and a watershed area between the epicondyles and distal to the supracondylar region were investigated. On the basis of 200 macerated humeri, the distribution pattern of cortical nutrient foramina and their anatomic relation to properly applied common distal humerus plates were documented.

Results

The data show a significantly higher density of vessels per cancellous bone in the epicondylar regions than in the watershed region (p < 0.000, median 0.148 vs. 0.103). The analysis of the nutrient foramina showed distinct distribution patterns with a single foramen over the medial epicondyle (55 specimens, 27.5 %) and an area of several foramina at the posterior part of the lateral epicondyle (200 of the specimens, 100 %). In almost every specimen, the application of the osteosynthetic implants led to an overlay over the investigated nutrient foramina.

Discussion

Osteonecrosis and non-union are severe complications in the surgical treatment of distal humeral fractures. The biology of the bone, especially the blood supply, has to be respected as much as possible during open procedures, to optimize bony healing. This has to be considered when performing periosteal stripping or applying osteosynthetic plates over the postero-lateral and medial epicondyle. The watershed area of the distal humerus has to be considered as being prone to minor arterial blood supply and thereby non-union is possible, if the arterial vessels coming from the epicondyles are destroyed.     

The anatomical and clinical details of the pterygoid canal: a three-dimensional reconstructive virtual anatomic evaluation based on CT

Purpose

To delineate the pterygoid canal (PC) configuration and its position in relation to surrounding important anatomical landmarks using three-dimensional reconstructive technology based on CT for the Chinese.

Methods

The computerized tomography arteriography (CTA) data of 137 patients were retrospectively evaluated using neuroimaging three-dimensional reconstructive software. The morphological parameters of the PC as well as the spatial relationship and distance between the PC relative to internal carotid artery (ICA) and the foramen rotundum were evaluated.

Results

83.9 % of the PC can be identified by our neuroimaging three-dimensional reconstructive software. The mean distance from the PC to the ICA was 2.6 ± 1.2 mm. The mean distance between medial aspects of bilateral ICA was 19.6 ± 2.7 mm. The distal vertical and horizontal distances between the PC and foramen rotundum were 5.2 ± 3.2 and 6.1 ± 2.8 mm, respectively. All the proximal end of the PC were inferior-lateral to the ICA. The PC mainly (92.9 %) ran posteriorly with a medial to lateral direction. The distance from the PC to ICA was positively correlated with the distance between bilateral ICA and the distal diameter of the PC. The vertical distance between the PC and foramen rotundum was positively correlated with the length of the PC and the horizontal distance between the PC and foramen rotundum.

Conclusions

Understanding the configuration and spatial relationship of the PC may be helpful to improve the accuracy and safety of operation during the expanded transnasal endoscopic approaches to skull base. The three-dimensional reconstructive virtual anatomic technology may be a useful tool to delineate the PC configuration and its position to surrounding important anatomical landmarks.     

Morphometric analysis of the proximal ulna using three-dimensional computed tomography and computer-aided design: varus,dorsal, and torsion angulation

Purpose

The proximal ulna, particularly the course of the posterior border, has a complex three-dimensional (3D) morphology which has been highlighted recently due to its clinical relevance in relation to surgical treatments. 3D computed tomography (CT) reconstruction and computer-aided design (CAD) based software can help to visualize the complex anatomy and thus aid the investigation of the more detailed morphology of the proximal ulna.

Methods

In our current study, 3D CT reconstruction images of 20 cadavers were imported into the 3D CAD program. Three morphologic angle parameters of the proximal ulna were measured including the dorsal, varus and torsion angulation. The torsion angulation was measured using the flat spot of olecranon dorsal aspect. We measured the total length of the ulna and the distance between the olecranon tip and the apex of dorsal and varus angulation. Furthermore, the thickness of olecranon was also measured for all the specimens.

Results

The results showed that the mean dorsal, varus, and torsion angulation was 4.3° (range 2.6°–5.9°), 12.1° (range 7.9°–17.6°), and 22.5° (range 16.6°–30.5°), respectively. The average length ratio of the dorsal and varus angulation apex to the total ulnar length was 26.4 % (range 19.8–30.7 %) and 32.7 % (range 27.5–37.5 %), respectively. The average of olecranon thickness at the proximal tip, mid-olecranon fossa, and at coronoid tip level was 17.8 mm (range 14.1–22.8 mm), 19.7 mm (range 15.8–23.1 mm), and 35.1 mm (range 27.9–41.8 mm), respectively.

Conclusion

In conclusion, variations in the proximal ulna have to be considered when anatomically contoured dorsal plates are applied. Knowledge of the 3D morphologic anatomy of the proximal ulna would provide important information on fracture reductions, and the design of a precontoured dorsal plate or a prosthetic ulnar stem.     

Accessory coracobrachialis: a case report with its morphological and clinical significance

Method

During the routine dissection of a male cadaver for teaching undergraduate medical students, a variation was seen in the morphology of coracobrachialis muscle.

Results

The presence of an anomalous head of coracobrachialis muscle which had muscular origin from an abnormal site on coracoid process and thin tendinous insertion at the junction of brachialis and triceps muscle in common with insertion of coracobrachialis muscle to the medial surface of the middle of the shaft of the humerus.

Conclusion

Coracobrachialis muscle can have variant origin related to its embryogenesis with its clinical and surgical significance.     

The prevalence, length and position of the anterior loop of the inferior alveolar nerve in Chinese, assessed by spiral computed tomography

Purpose

This study used spiral computed tomography to identify the anterior loop of the inferior alveolar nerve, and to measure its length and position in Chinese. This information may be useful to safely install endosseous implants in the most distal area of the interforaminal region.

Methods

Sixty-eight Chinese patients were included in this retrospective study. Patients were scanned by 64-slice spiral computed tomography, and the prevalence, length, and position of the anterior loop were assessed using the multiplanar capabilities of software.

Results

An anterior loop could be identified in 83.1 % of the cases, with a mean length of 2.09 mm (range 0–5.31 mm). The mean distance from the superior border of the mental foramen to the alveolar crest was 13.00 mm, and the mean distance from the superior border of the origin of the anterior loop to the alveolar crest was 17.83 mm.

Conclusions

The anterior loop was highly prevalent in Chinese, and the length of the anterior loop was highly variable. Therefore, we recommend that drilling commences from a location approximately 5.5 mm mesially from the mental foramen, when installing implants in the most distal interforaminal area.     

The medial head of the triceps brachii. Anatomy and blood supply of a new muscular free flap: the medial triceps free flap

Purpose

The anatomical features of the posterior compartment of the arm seem to provide the basis to raise one of the smallest free muscular flaps, with minimal donor site morbidity: the medial triceps free flap.

Methods

The anatomic study was carried out on 27 fresh cadaver arms: 7 prepared for corrosion cast, 15 for simple dissection and 5 for dissection after latex injection. Morphological data of the muscle, as well as pedicle constancy and size, were recorded.

Results

The mean size of the medial head was 10.7?×?2.5?×?3.3?cm; the mean weight was 30.1?g. We found a constant and unique pedicle supplying the whole medial head of triceps muscle, composed by the middle collateral artery (MCA), two veins and a nerve. The mean length of MCA was 2.9?cm and the ??extended?? pedicle, including the deep brachial artery (DBA), was 8?C12?cm long. At their origin, the mean caliber of MCA was 1.5?mm and the mean caliber of DBA 2.4?mm.

Conclusions

Our findings confirmed the reliability of the MC vessels and their anatomical relationships with the medial head of triceps brachii muscle, which could be harvested as a free flap or as a pedicled flap based on anterograde or retrograde flow. This technique should be safe, yielding mild donor site morbidity, and suitable in regional reconstruction or distant reanimations.     

Anatomical landmarks for locating the sphenoid ostium during endoscopic endonasal approach: a cadaveric study

Purpose

The sphenoid ostium (SO) provides a natural portal for entering the sphenoid sinus and beyond up to the skull base. It is not always easy to locate the ostium during the endoscopic approach. The present study was designed to establish readily identifiable anatomical landmarks for locating the sphenoid ostium.

Methods

Cadaveric dissection was performed in 30 hemisections of head and neck and various measurements were taken from fixed anatomical landmarks in the nasal cavity to the sphenoid ostium. The size, shape and position of sphenoid ostium were determined in relation to the anterior wall of the sphenoid sinus and the superior turbinate.

Results

The mean distance from the supero-lateral angle of the posterior choana to the SO was found to be 21.21 ± 6.02 mm. The mean distance of the SO from the midline was 4.85 ± 2.89 mm. In all the specimens, the SO was situated within 1 cm of the midline. The mean distance between the inferior end of the SO and the postero-inferior edge of the superior turbinate was 8.03 ± 3.52 mm. The SO was present on an average distance of 55.1 ± 3.54 mm from the limen nasi. In 93.3 % of the specimens, the SO was situated between 5 and 6 cm of the inferior end of the limen nasi. The angle between the anterior nasal spine and the SO was found to be remarkably constant. In 93.3 % of the specimens, it was from 25° to 30°.

Conclusions

The sphenoid ostium could be localized medial to the superior turbinate between 1.5 and 3 cm above the supero-lateral angle of the posterior choana, within 1 cm of the midline and within 1 cm of the postero-inferior edge of the superior turbinate.     

Glenohumeral relationships at different angles of abduction

Purpose

The objective of this study was to clarify the relationships among anatomical landmarks of the glenohumeral joint at different angles of abduction.

Methods

Fifteen volunteers (ten men, five women; mean age 29 years) were enrolled in this study. Images of externally and internally rotated positions at 45°, 90°, and 135° of abduction in the plane 30° anterior to the trunk were taken using an open magnetic resonance imaging system. Landmarks including the glenoidal long axis with its center, bicipital groove, center of the head, and humeral shaft axis were determined. Using a line set on the surface of the head in the plane parallel to the humeral axis (including the head center and bicipital groove with its parallel and perpendicular lines), the glenoid location and rotational relationships were investigated in each position.

Results

The average angles of axial rotation were 48° ± 27° at 45º of abduction, 71° ± 20° at 90° of abduction, and 40° ± 27° at 135° of abduction. The trajectories of the glenoid center primarily extended over the anterior portion of the humeral head at 45° of abduction and over the posterior portion at 90° of abduction, while those at 135° of abduction were localized on a small upper portion of the head.

Conclusions

The glenohumeral relationships demonstrated that arm abduction might influence shoulder function through its effects on the portion of the humeral surface in contact with the glenoid during rotation and the resultant changes in the glenohumeral relationships.     

Finite element analysis of the strain distribution in the humeral head tubercles during abduction: comparison of young and osteoporotic bone

Aim

The aim of this work was to design an accurate 3D digital model of the humerus and rotator cuff muscles. This model was then used to study strain distribution in humeral tubercles according to bone density.

Materials and methods

The geometry of bone and muscle structures was reproduced using SURFDRIVER© software, based on anatomical sections, CT scans and MRI images from the Visible Human Project image library. The contours were transferred to PATRAN© software to rebuild volumes and mesh them. Calculations of strains and their distribution were performed using NASTRAN© software. All the elements were considered to be isotropes.

Results

The study of the distribution of stress magnitude according to the type of bone modeled, shows that some stresses in cortical bone are greater than those in cancellous bone and are also greater in old bone, implying more deformation in old bone at constant force. This study also shows that stresses do not penetrate deeply into cancellous tissue.

Conclusion

Observing the simulation results led understanding of the pathology of certain fractures of the proximal end of the humerus. This study also helped explain why certain types of osteosynthesis fail due to tubercles reconstruction failures.     

Shoulder bony landmarks location using the EOS® low-dose stereoradiography system: a reproducibility study

Purpose

To investigate the reproducibility of shoulder bony landmarks location using the EOS^® low-dose stereoradiography system, in order to validate this new tool for the study of gleno-humeral pseudo-kinematics.

Methods

An inter and intraobserver reproducibility study of shoulder bony landmarks location concerning 22 healthy volunteers. This study concerned the neutral position, arm at rest. Humerus and scapula were modeled with simple geometric shapes using specific software. Those shapes were positioned on A-P and lateral x-rays views. Images analysis of the 22 subjects was carried out three times (n _r = 3), by two observers (n _o = 2), for a total of n _tot = 132 analyses.

Results

We obtained a very good reproducibility for the humeral head center and the diaphysis axis with 95% confidence interval (IC95%) inferior to 1.09 mm and 0.41°, respectively. The uncertainty was higher for the lateral and medial epicondyles. Regarding the scapular bony landmarks, we observed a good reproducibility for the tip of the coracoid process, the inferior glenoid rim, and the axillar border with a 95% confidence interval lower than 2.13, 2.91 mm, and 3.67°, respectively. The uncertainty was higher for the most postero-lateral point of the acromion and the superior glenoid rim.

Conclusion

Our analysis of the x-rays obtained with the EOS^® low-dose stereoradiography system assessed the location reliability and reproducibility of specific scapular and humeral bony landmarks. This work opens the way to gleno-humeral pseudo-kinematics analysis using EOS^® imaging system.     

Left gastric vein on the dorsal side of the splenic artery: a rare anatomic variant revealed during gastric surgery

Purpose

The left gastric vein (LGV) is an important blood vessel requiring dissection during gastric surgery. We describe a rare anatomic variant of the LGV.

Methods

The LGV drainage pattern was analyzed relative to intraoperative vascular anatomy in 2,111 patients with gastric cancer who underwent radical resection from May 2007 to September 2012. The incidence of the anatomic variant was determined, and the diameter and length of the LGV and the distances from the end of the LGV to the splenoportal confluence and the root of the left gastric artery (LGA) were measured by abdominal CT reconstruction.

Results

In 6 of the 2,111 (0.28 %) gastric cancer patients who underwent radical resection, the LGV descended on the left side of the gastropancreatic fold, ran across the dorsal side of the splenic artery and drained into the splenic vein. The mean diameter and length of the LGV were 5.10 ± 0.40 and 37.40 ± 5.19 mm, respectively, and the mean distance from the end of the LGV to the splenoportal confluence was 13.05 ± 0.86 mm. The closer the LGV and LGA were to the root, the greater the distance between them, with a mean 13.85 ± 1.02 mm between the end of the LGV and the root of the LGA.

Conclusions

In this rare anatomic variant, the LGV descends along the gastropancreatic fold, runs across the dorsal side of the splenic artery and drains into the splenic vein. Knowledge of this rare anatomic variant will help avoid damage to the LGV during gastric surgery.