Bony Channels Research Articles

Anterior percutaneous full-endoscopic transcorporeal decompression of the spinal cord via one vertebra with two bony channels for adjacent two-segment cervical spondylotic myelopathy: a technical note

BackgroundThe current treatments for adjacent two-segment cervical spondylotic myelopathy (CSM) include two-segment anterior cervical discectomy and fusion (ACDF) and single-segment anterior cervical corpectomy and fusion (ACCF). Long-term follow-up has demonstrated that both procedures have complications such as reduced cervical mobility, accelerated degeneration of adjacent segments and loosening of internal fixation screws. The purpose of this study is to demonstrate the feasibility, safety, and efficacy of anterior percutaneous full-endoscopic transcorporeal decompression of the spinal cord (APFETDSC) via one vertebra with two bony channels for the treatment of adjacent two-segment CSM and to present our surgical experience.MethodsAnterior percutaneous full-endoscopic transcorporeal decompression of the spinal cord (APFETDSC) via one vertebra with two bony channels was performed for 12 patients with adjacent two-segment CSM with follow-up care for at least 12 months. The Visual analog scale (VAS) and the Japanese Orthopedic Association Score (JOA) were recorded, and modified Macnab criteria were used to evaluate the treatment excellence rate. Radiological examinations, including X-ray, computed tomography (CT) and magnetic resonance imaging (MRI), were used to evaluate spinal cord decompression, intervertebral stability and healing of the bony channel.ResultsAll 12 patients completed the operation successfully. No postoperative complications, such as dysphagia, Horner’s syndrome, or laryngeal recurrent nerve palsy, were found. The postoperative VAS and JOA scores were significantly improved compared with those before surgery(P < 0.001). According to the modified Macnab criteria, the clinical outcome was excellent in 8 cases, good in 3 cases and fine in 1 case at the final follow-up and the excellent and good rate was 91.7%. Postoperative and follow-up imaging showed significant spinal cord decompression, well-healed bony channels and no cervical instability.ConclusionsThis study is the first report of anterior percutaneous full-endoscopic transcorporeal decompression of the spinal cord via one vertebra with two bony channels. This procedure has the advantages of less trauma, faster recovery, fewer complications and no need to implant internal fixators. This is a minimally invasive, feasible and safe surgical procedure for patients with adjacent two-segment CSM.

Three-Dimensional High-Resolution Temporal Bone Histopathology Identifies Areas of Vascular Vulnerability in the Inner Ear

Objectives: Hypothesized causes of vestibular neuritis/labyrinthitis include neuroinflammatory or vascular disorders, yet vascular disorders of the inner ear are poorly understood. Guided by known microvascular diseases of the retina, we developed 2 hypotheses: (1) there exist vascular vulnerabilities of artery channels in cases of hypothetical nerve swelling for the superior, inferior, and vestibulocochlear artery and (2) there are arteriovenous crossings that could compromise vascular flow in disease states. Methods: Two fully mounted and stained temporal bones were used to render three-dimensional reconstructions of the labyrinth blood supply. Using these maps, areas of potential vascular compression were quantified in 50 human temporal bones. Results: Although inner ear arteries and veins mostly travel within their own bony channels, they may be exposed (1) at the entrance into the otic capsule, and (2) where the superior vestibular vein crosses the inferior vestibular artery. At the entry into the otic capsule, the ratio of the soft tissue to total space for the superior vestibular artery was significantly greater than the inferior vestibular artery/cochleovestibular artery (median 44, interquartile range 34–55 vs. 14 [9–17], p < 0.0001). Conclusions: Three-dimensional reconstruction of human temporal bone histopathology can guide vascular studies of the human inner ear. Studies of retinal microvascular disease helped identify areas of vascular vulnerability in cases of hypothetical nerve swelling at the entrance into the otic capsule and at an arteriovenous crossing near the saccular macula. These data may help explain patterns of clinical findings in peripheral vestibular lesions.

Length of the Narrow Bony Channels May Not be the Sole Cause of Differential Involvement of the Nerves in Vestibular Neuritis.

To measure the vestibular nerve bony channels, applying a 3D measurement to account for the oblique trajectory of the singular nerve. The clinical syndrome vestibular neuritis affects structures innervated by the superior vestibular nerve more commonly than the inferior vestibular nerve. Anatomical differences such as a longer, narrower bony channel of the superior vestibular nerve may increase its susceptibility to entrapment. Length of the narrow segment of each vestibular nerve in which the nerve occupies more than 80% of the bony channel was measured. Forty six normal ears sectioned in the axial plane were measured. The narrow channel for the lateral semicircular canal (SCC, mean [SD] 2.94 ± 0.54) mm was longer than that of the singular nerve innervating the posterior SCC (1.95 ± 0.58 mm [p < 0.0001]), which also exceeded that of the utricular nerve (1.45 ± 0.36 mm [p < 0.0001]). The nerve to the superior part of the saccule (i.e., Voit's nerve) was 1.14 ± 0.48 mm and that of the inferior saccule was 0.52 ± 0.37 mm. The length of the narrow bony channel for the singular nerve is longer than previously reported and exceeds the utricular nerve. Comparing these data with the frequency of clinical lesions in recent literature suggests that, although bony channel length may contribute to differential involvement of the vestibular nerves, other factors may increase susceptibility of the superior vestibular nerve, including redundancy in innervation of the saccule and posterior SCC and anastomoses between the facial nerve and the superior vestibular nerve through which reactivated herpes virus may spread.

MRI of the inferior alveolar nerve and lingual nerve-anatomical variation and morphometric benchmark values of nerve diameters in healthy subjects.

Since MRI using dedicated imaging sequences has recently shown promising results in direct visualization of the inferior alveolar nerve (IAN) and the lingual nerve (LN) with high spatial resolution, the aim of this study was to generate suitable standard specifications to reliably depict the IAN and LN in MRI and to delineate the anatomy and its variants of these nerves in healthy subjects. Thirty healthy volunteers were examined on a 3-T scanner (Elition, Philips Healthcare, Best, the Netherlands). The sequence protocol consisted of 3D STIR, 3D DESS, and 3D T1 FFE "black bone" sequences. The study reconfirmed a good feasibility of direct visualization of proximal and peripheral portions of the IAN and of the proximal course of the LN. The STIR sequence showed the highest apparent signal to noise ratio (aSNR) and best apparent nerve-muscle contrast to noise ratio (aNMCNR) for IAN and for the LN. The applied MRI sequences allowed to differentiate the tissue composition of the neurovascular bundle inside the mandibular canal. Dedicated MRI sequence protocols proved effectively to detect the IAN and LN and their course in healthy volunteers. The tissue composition of the mandibular neurovascular bundle was conclusively distinguishable as was the varying topography inside multiple bony channels. The presented data on the precise and valid visualization of the IAN and LN have clinical implications in respect to local anesthesia prior to dental treatments in the mandible but also regarding surgical procedures and implant insertion in the molar region.

Anatomical study on isocentric C-arm three-dimensional imaging navigated percutaneous double screw fixation of pubic symphysis diastasis

Objective With the isocentric C-arm (Iso-C) three-dimensional computerized navigation system, cadaveric pelvic specimens were used to imitate double screw fixation of the symphysis pubic. Practicability and safety of the screw trajectory were examined postoperatively by local cadaveric dissections and imaging tests. Methods Pelvic specimens were harvested from 8 male and 7 female adult cadavers. Double screw placement in symphysis pubic was performed using the Iso-C three-dimensional navigation and entry point and safety trajectory was achieved. With the detailed local dissection postoperatively, distances from screw entry and exit points to unilateral structures (spermatic cord, femoral artery and vein, femoral nerve, obturator artery and vein, obtrurator nerve, and so on) were measured respectively. After complete removal of surrounding soft tissues of the specimen with only bony structure kept, the entry angle and length were calculated. Accuracy of double screw fixation of symphysis pubic was further checked using X-ray and CT. Results Entry point of the first screw was at the junction of unilateral pubic tubercle and transitional site of superior pubic ramus. Mean angle of the first screw with the horizontal plane was (7.7±1.9)° in men and (8.1±1.7)° in women. Mean angle between the first screw and coronal plane was (7.8±1.8)° in men and (7.7±2.0)° in women. Entry point of the second screw was in the same place in the contralateral pubic tubercle. Mean angle between the second screw and horizontal plane was (30.6±4.0)° in men and (30.8±3.4)°in women. Mean angle between the second screw and coronal plane was (9.1±3.0)°in men and (9.2±3.3)°in women. Conclusions With the three-dimensional computerized navigation system, the bony channels of double screws implanted in the symphysis pubic are achieved and reliable. Percutaneous double screw fixation is feasible to treat the pubic symphysis diastasis. Key words: Pubic symphysis diastasis; Bone nails; Anatomy, regional; Surgery, computer-assisted

Percutaneous Acetabuloplasty: A Cadaveric Study

Periacetabular osteolysis is a common etiology of prosthesis failure in patients who undergo total hip arthroplasty. These lesions are treated by open and, more recently, percutaneous techniques. The purpose of this study was to determine the relevant surface anatomy and bony landmarks in establishing percutaneous access to periacetabular regions and identifying critical at-risk structures in establishing access. Percutaneous access to the periacetabular region was established superiorly, anteroinferiorly, and posteroinferiorly by using 5 L5-to-mid thigh fixed cadaver pelvises with latex-injected vessels using threaded guidewires. Dissection was completed to identify structures at risk, with the distance from the wires recorded to the nearest millimeter. C-arm position for the optimal visualization and placement of guidewires was recorded. Average distance from the pin and the at-risk structures ranged from 11.2 to 38.7 mm. All 3 approaches allowed for safe percutaneous access to the periacetabular regions without injuring significant anatomical structures. This study established safe starting points and orientation for guidewires and radiograph projections associated with percutaneous access to the periacetabular regions. The findings in this study will be useful for developing minimally invasive approaches to these regions for the treatment of osteolytic lesions of diverse etiology. However, a biomechanical evaluation of the impact of these bony channels on the strength of pelvis under physiological and unanticipated loading must be performed before this technique can be safely translated to clinical practice.

Alveolar bone necrosis and tooth exfoliation secondary to herpes zoster in the setting of HIV/AIDS

Varicella–Zoster virus (VZV) is one of the eight herpesviruses that have been found to affect humans, and is the cause of both varicella (chicken pox) and herpes zoster (shingles). Unlike varicella, herpes zoster is a sporadic disease with a lifetime risk estimated to be 10–20%. Herpes zoster can occur in anyone who has had varicella, but is more common with increasing age, almost doubling in each decade past the age of 50 years. It is also more frequent in immunocompromised patients. Other complications of herpes zoster are widespread, and include postherpetic neuralgia, encephalitis, myelitis, cranial and peripheral nerve palsies, secondary bacterial infection, acute retinal necrosis and pneumonia [1]. A well-documented but rare complication of herpes zoster is spontaneous exfoliation of the teeth with alveolar bone necrosis [2]. Although some of these patients received chemotherapy for an underlying malignancy, relatively few cases of alveolar bone necrosis as a complication of herpes zoster have been described in HIV-positive patients [3,4]. Over a period of one year, six HIV-positive patients aged 36, 38, 47, 48, 52 and 73 years presented with skin and oral lesions after acute herpes zoster infection affecting the areas innervated by the mandibular division of the trigeminal verve. The patients presented with unilateral alveolar necrosis of the mandibular alveolar bone with sparing of the inferior border (Fig. 1). Three patients had sustained pathological fractures as a result of the loss of alveolar bone. Tooth exfoliation was present in the affected areas. The CD4 cell counts were available for four of the patients, which were all less than 200 cells/μl. No patient had a previous history of herpes zoster. Histological examination of the necrotic bone confirmed the presence of osteonecrosis without contributing towards the possible pathogenesis.Fig. 1: Unilateral alveolar bone necrosis ending abruptly in the midline. The tooth sockets from the exfoliated teeth are clearly visible.The EC-Clearinghouse consensus report is still the most widely used classification of oral lesions associated with adult HIV infection [5]. This scheme groups lesions into three categories according to the strength of association with HIV infection. This scheme is recognized to be more applicable to patients in Europe and the United States, with the need to document new and emerging oral diseases and conditions from developing countries emphasized [6]. Although herpes zoster is listed as a group 2 lesion (less commonly associated with HIV infection), spontaneous bone necrosis as a complication of herpes zoster is not listed in the classification. The alveolar bone of the maxilla and mandible has a rich vascular supply. It is derived from supraperiosteal arterioles, vessels from the periodontal ligament and vessels supplying the interdental bone crest. The precise mechanism of herpes zoster-related alveolar bone necrosis is still uncertain. The alveolar arteries may become compressed by the transudate associated with inflammation of the alveolar nerves in enclosed bony channels, with resulting ischaemia and necrosis of the alveolar bone and periodontium. A related postulate is that VZV may cause vasoconstriction of the blood vessels supplying the alveolar bone by invading the sympathetic nerves that accompany these vessels [2]. Evidence of local vasculitis in herpes zoster is limited, although extracranial granulomatous vasculitis has been reported as a postherpetic reaction whereas vascular damage by VZV in the central nervous system is well documented [7]. We have only encountered this manifestation of herpes zoster infection in the setting of HIV/AIDS, strengthening our opinion that alveolar bone necrosis as a complication of herpes zoster infection warrants inclusion as a group 2 lesion.

Audit of the multidisciplinary management of orbital infection secondary to sinusitis

Acute infection of the orbit may have several aetiologies such as conjunctivitis, trauma and stye, and it may also be idiopathic. However, the most common cause is acute sinusitis spreading directly from the paranasal sinuses which are intimately related to the orbit. The maxillary and ethmoidal sinus infections are the most common causes of orbital involvement (Mill & Kartush 1985). Only the thin translucent bone of the lamina papyracea separates the ethmoidal air cells and the orbit. The infection may enter the orbit either by direct extension, by local thrombophlebitis or by infected thromboemboli along valveless venous connections (Chandler et al . 1970). Neurovascular foramina, congenital or acquired bony dehiscences and valveless venous channels provide potential routes for bacteria to spread from the sinus through the lamina papyracea to the periosteum of the orbit (Harris 1983). A classification of orbital infection secondary to sinusitis was advanced by Chandler in 1970 (Chandler et al . 1970). It is based on local pathological changes and does not include intracranial complications but does indicate worsening morbidity, long-term complications and even death. In the preantibiotic era, orbital cellulitis resulted in blindness in 20% of patients, 13% had grave impairment of vision and 17% died of meningitis (Gamble 1933; Duke Elder & MacFaul 1974). Despite advances in imaging and antibiotics, there is a significant 10% incidence of visual loss (Patt & Manning 1991). We report here an audit designed to improve current practice and instigate a multidisciplinary approach to the management of orbital infections secondary to sinusitis and improve the quality of care offered to these patients.

Anatomic Differences in the Lateral Vestibular Nerve Channels and their Implications in Vestibular Neuritis

Anatomic differences may render the superior division of the vestibular nerve more susceptible to injury during vestibular neuritis. Neural degeneration has been identified in temporal bone studies of vestibular neuritis. Previous anatomic and physiologic studies of vestibular neuritis have demonstrated that the superior division of the vestibular nerve is preferentially affected, with sparing of the inferior division. A preliminary temporal bone study has implicated neural entrapment as a possible cause for this preferential injury. Two independent unbiased observers performed histologic analysis of 184 temporal bones from our temporal bone library. Measurements of the medial, midpoint, and lateral portions of the superior vestibular, inferior vestibular, and the singular nerves and their bony channels lateral to the internal auditory canal were made. These measurements included the length and width of each bony channel and an estimated percent of each channel occupied by bony spicules at each location. The lengths of the bony channels of the singular nerve (0.598 mm) and the inferior vestibular nerve (0.277 mm) were significantly shorter than the average length of the superior vestibular channel (1.944 mm; p < 0.0001). The total percent of the channel occupied by bone at the midpoint was significantly greater for the superior vestibular (28%) compared with either the singular (0%) or the inferior vestibular channel (18%) (p < 0.0001). The lateral bony channel of the superior vestibular nerve is seven times longer than the inferior vestibular and more than three times longer than the singular channel. There are a larger percentage of bony spicules occupying the superior vestibular compared with the inferior vestibular or singular channels. In addition, the superior nerve passes through a longer area of severe narrowing compared with the inferior or singular nerves. This anatomic arrangement of a longer bony channel with more interspersed bony spicules could make the superior vestibular nerve more susceptible to entrapment and ischemia.

Fusion rate after posterior lumbar interbody fusion with carbon fiber implant: 1-year follow-up of 51 patients.

Problems associated with posterior lumbar interbody fusion (PLIF) have traditionally included the need for donor bone, prolonged healing time of donor bone, the difficulty of cutting precise bony channels, the risk of retropulsion of graft, postoperative collapse of the bone graft, and pseudarthrosis. To avoid these problems a carbon fiber reinforced polymer implant cage has been developed to facilitate interbody fusion. The aim of the present study was to evaluate the technical problems and fusion rate associated with these new device for PLIF. Between April 1991 and December 1993, 65 pairs of these implant cages were sold in Sweden. They were traced to six hospitals, where they had been used in the treatment of 51 patients operated on at a total of 65 levels. All PLIF were supplemented with VSP (Variable Screw Placement) instrumentation. All medical records were evaluated and all patients were examined with plain radiographs taken at least 1 year after surgery. If that investigation did not show a clear fusion they were also evaluated with CT (18 patients, 27 levels). No intraoperative problems with the device have been reported; 44 patients (86%) and 58 levels (89%) achieved successful fusion. All patients bar one maintained their immediately obtained postoperative disc height. CT with 1-mm slices and sagittal reconstruction is most helpful if radiographs are difficult to interpret.

Periductal vessels of the endolymphatic duct.

Light microscope was used to examine the rich vascular plexus surrounding the human endolymphatic duct, both in the periductal loose connective tissue and in the bony channels surrounding the bony vestibular aqueduct. We also performed computer-aided three-dimensional reconstruction on one serially sectioned region of the endolymphatic duct. We found an anastomotic and looping network of vessels residing in the loose connective tissue close to the epithelium of the endolymphatic duct. This network often received a vascular contribution from the vessels in the periaqueductal bony channels. These findings were verified by light microscopic examination of 50 temporal bone specimens. Concurrent with this finding, histologic examination also showed different characteristic features of the vascular system of the endolymphatic duct-proximal sac areas and of the more distal parts of the endolymphatic sac. These features include the arrangement, quantity, and contents of the periaqueductal bony channels, as well as the organization of the bone containing these periductal bony channels. Findings from this study help the understanding of the anatomy of the human endolymphatic duct. In addition, they support and supplement earlier observations of the structure of the endolymphatic duct. We suggest the possible existence of a periductal vasculature system, similar in pattern to that in the endolymphatic sac, but specialized to work with the duct to aid its function.

Reconstruction of anterior cruciate ligament with carbon fiber. An experimental study on pigs.

During a follow-up period of 16 weeks in 18 pigs, macroscopical and histological studies revealed invasion of fibroblasts and mesenchymal cells around the carbon fiber prosthesis inserted to replace the ACL but scarce tissue ingrowth into the prosthesis proper. There was no adherence of the carbon ligament onto the bony channels. The peak tensile strength of the reconstructed ligament was about one third of the paired normal ACL ligament during the 16 week experiment.

Vascularity of endolymphatic sac in Meniere's disease. A histopathological study.

The vascularity of the endolymphatic sac (ES) in the vestibular aqueduct (VA) and of periaqueductal bony channels was studied in 18 temporal bones from patients with Meniere's disease and in the same number of control bones with no endolymphatic hydrops and no premortem history of otologic disease. The control bones were selected on the basis of having VAs of the same sizes as the hydropic bones. This was important in order to eliminate any possibility that differences in degree of vascularity of the ES could have been due simply to differences in the degree of development of the VA. All specimens were sectioned and stained with hematoxylin and eosin. The ES of each bone was reconstructed two-dimensionally by the medial view graphic reconstruction method, and its vascularity was studied histologically under a light microscope. There were fewer and smaller blood vessels in the ESs of bones from individuals with Meniere's disease than in the ESs of control bones. This was particularly true in the richly rugose and the cranial orifice portions of the sac. However, no significant differences were recognized in the degree of vascularity of the periaqueductal bony channels between control and Meniere's disease bones.

Results of the Magnuson operation for recurrent dislocation of the shoulder

T HE problem of recurrent dislocation of the shoulder has troubled orthopedists and surgeons for many years. Numerous theories as to the pathogenesis have been advanced but the following are most commonly accepted. Some authorities, notably Bankhart,’ have described a detachment (usually traumatic) of the glenoid Iabrum from the antero-inferior rim of the glenoid which permits anterior and inferior dislocation of the humeral head. Others (Hill and Sacks) d escribed an abnorma1 groove in the posterolateral quadrant of the humeral head which they believe facilitated recurrent dislocation. Still others, DePalma2 in particular, have found by anatomic studies of a11 ages that the above labral and humeral defects are concomitant with increasing age, but that in the later decades of life, while the bone and labral defects increased in frequency and severity, the incidence of recurrent dislocation declined. From these observations DePalma postulated that other factors must be involved, being convinced that the real causative factor was a tearing and relaxation of the musculotendinous cuff of the shoulder plus a stretching of the other auxiliary stabilizing structures such as the glenohumeral Iigaments and the deltoid muscle. This relaxation permits excessive external rotation of the humeral head which predisposes to dislocation. This postulate is concurred with and appears to account for all the elements necessary to explain this phenomenon. Attempts to correct this disabling condition have been legion. Watson-Jones3 states that sixty different operations have been described. These divide themselves into four classes: tion. This method has not been conspicuously successful. Various suspension operations, such as the Henderson5 and NicolaG procedures, attempting to “snug-up” the humeral head in the glenoid cavity by tendinous slings. These slings passing through bony channels tend to atrophy, become relaxed and finally disintegrate. Bankhart and Putti-Platt believed that by reattaching the glenoid labrum (the typical Bankhartian lesion) or reinforcing the antero-inferior capsule, recurrent dislocations might be prevented. This method has been widely used. In 1945 Magnuson’ proposed an approach to this problem which he believed met all of the factors involved. Recurrent dislocation occurs with the arm in abduction and external rotation. Magnuson believed that by limiting the range of these two types of motion dislocation would be less apt to recur. His method transfers the normal insertion of the subscapularis tendon from the lesser tuberosity to a point distal to the greater tuberosity, thus providing a dynamic musculotendinous sling about the humeral head holding it up, and in internal rotation, preventing dislocation. The author has found this method to be both simple and successful.

Roentgenographic variations of the maxillary sinus and the nutrient canals of the maxilla and the mandible

The roentgenographic examination of the maxillary sinus is rather complicated, this being due to the presence of the upper dental arch. The conditions mentioned are best studied on intraoral films. Cysts and other pathologic lesions may readily be differentiated from changes in the maxillary sinus, and in like manner details of the various extensions of the sinus are best made out. The great detail obtained on intraoral films makes the vascular bony channels which have been variously diagnosed as pathologic changes particularly more significant; likewise knowledge of the vascularity of the mandible is essential due to the varied diagnoses made; for without a thorough knowledge of the normal anatomic structures and their variations, recognition of pathologic lesions is next to impossible.