Posterior Corner Research Articles

A New Segment of the Trochlear Nerve: Cadaveric Study with Application to Skull Base Surgery

Objectives The trochlear nerve is important to preserve during approaches to the skull base. Traditionally, this nerve has been divided into cisternal, cavernous, and orbital segments. However, the authors anecdotally observed an additional segment during routine cadaveric dissections. Therefore, they performed this study to better elucidate this anatomy. Design Twenty latex-injected cadaveric sides (10 adult cadavers) were dissected with the aid of an operating microscope. Standard microdissection techniques were used to examine the course of the distal cisternal and precavernous segments of the trochlear nerve. Setting Cadaver laboratory. Main Outcome Measures Measurements were made using a microcaliper. Digital images were made of the dissections. Results The authors identified a previously undescribed segment of the trochlear nerve in all specimens. This part of the nerve coursed between the entrance of the trochlear nerve into the posterior corner of the oculomotor trigone to the posterior wall of the cavernous sinus. This segment of trochlear nerve was, on average, 4 mm in length. Conclusions The authors have identified a new segment of the trochlear nerve not previously described. They propose that this be referred to as the trigonal segment. Knowledge of the microanatomy of the trochlear nerve is useful to skull base surgeons.

Revision of the Indo-West Pacific genus Brachypterois (Scorpaenidae: Pteroinae), with description of a new species from northeastern Australia.

A taxonomic revision of the scorpaenid genus Brachypterois resulted in three valid species. Brachypterois serrulifer Fowler 1938, previously regarded as ajunior synonym of Sebastes serrulatus Richardson 1846, can be distinguished from its congeners by having usually 16 pectoral-fin rays (vs. 15 in the congeners) and 0-22 spines on the median lateral ridge of the maxilla (vs. almost always absent), in addition to longer dorsal- and anal-fin soft rays, relatively fewer large dark spots on the caudal fin, and the posterior lacrimal spines usually directed ventrally. Brachypterois curvispina sp. nov., described on the basis of 32 specimens, can be distinguished from B. serrulata (Richardson 1846) by having fewer number of scale rows in the longitudinal series 41-45 (vs. 44-51 in B. serrulata); relatively long head, its length 41.6-44.5 (mean 43.1)% SL [vs. 38.3-43.1 (mean 40.2)% SL]; posterior lacrimal spines usually directed posteriorly, with the tip curved strongly upward in large males (vs. simply directed posteroventrally); and posteriorly directed spine(s) on the posterior corner of the outer angular ridge (vs. directed ventrally). Brachypterois serrulifer is distributed widely in the Indo-West Pacific, whereas distributional ranges of B. curvispina sp. nov. and B. serrulata are restricted to northeastern Australia and the northwestern Pacific, respectively. Intraspecific variation, including sexual dimorphism and ontogenetic changes in the three species are described in detail. A neotype, collected from southern Taiwan, is designated for S. serrulatus Richardson 1846.

Apoptosis Occurs Throughout the Diseased Rotator Cuff

Background: Even though apoptosis is known to be closely associated with rotator cuff tears, the differences in apoptosis according to the location within the torn supraspinatus tendon are still unknown. Purpose: To elucidate where apoptosis begins within the supraspinatus tendon. Study Design: Controlled laboratory study. Methods: Tendon tissues were collected from 14 patients undergoing arthroscopic rotator cuff repair surgery and 7 patients undergoing surgery for proximal humeral fracture who served as controls. In the patients with rotator cuff tears, the samples were harvested at 3 sites: the most lateral torn margin, 1 cm medial from the torn margin, and at the posterior torn corner. Caspase 3/7, 8, and 9 and cytochrome c activities were measured to determine the intracellular apoptosis pathway. Apoptotic cells were determined by in situ TUNEL (terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling) staining, and immunohistochemistry was performed. Results: The apoptotic activities of tendons from the experimental subjects were significantly higher than those of the controls. There were, however, no significant differences between the 3 sample sites. Immunohistochemistry also revealed strong expression of increased caspase 3/7, 8, and 9 and cytochrome c but no significant difference between them. Conclusion: This study shows that the intracellular apoptotic pathway is not only through the cell membrane receptor but also via intracellular mitochondria cascade. Clinical Relevance: Because apoptosis occurs regardless of the location within the rotator cuff, debridement of the torn margin to obtain a healthy tendon may not be needed. Further study should focus on not only the technique of tying the torn tendon back to the bone but also biological augmentation to reverse or prevent further apoptosis within rotator cuff tendon.

Anteromedial marginal fracture of medial tibial plateau without significant knee ligamentous injury in hypermobility patient: a case report and review of literature

Anteromedial rim fracture of medial tibial plateau is a rare fracture pattern with only a small number of case reports in the literature. However, it is highly likely that is associated with specific significant soft tissue injuries, especially posterior and posterolateral corner structure, and medial meniscus injury. It is thought this fracture is caused by hyperextension and varus rotation mechanism. The previous reports highlight the typical pattern of severe concomitant knee ligament injury associated with this fracture that always require surgical repair to restore knee stability and function. In this report, we present an unusual case with a history of generalized joint laxity and acute anteromedial marginal fracture of medial tibial plateau without associated significant ligament damage, together with a literature review of this condition. We believe this case report introduces new insights into this unique fracture pattern.

OP0269 MRI of the spine for detection of new bone formation in ankylosing spondylitis: Does it offer any advantages over radiography?

BackgroundRadiographic assessment of new bone formation in the anterior vertebral corners of the cervical and lumbar spine is the current gold standard for detection of damage and disease progression in...

Life colouration of three Australoheros species from the rio Paraíba do Sul basin, southeastern Brazil (Teleostei: Labroidei: Cichlidae)

The colouration in life of three Australoheros species from the rio Paraíba do Sul basin is described herein: Australoheros muriae, Australoheros paraibae and Australoheros robustus. These three species share a character state characterized by the presence of two red zones on caudal-fin’s posterior margin corners, differentiating them from its congeners from the coastal river basins of southeastern Brazil. Australoheros muriae, as well as, its congeners from the coastal river basins of southeastern Brazil (except A. macacuensis), do not expose metallic blotches on anal fins, differing from A. paraibae and A. robustus which always show metallic blotches on anal fin. Australoheros muriae is also distinguished from these other two species by having red iridescence restricted to the upper region of flank, near dorsal-fin base. Australoheros paraibae differs from A. robustus by having ground of body yellow or yellowish brown, absence of any red iridescence on flank, dorsal-fin ground colouration yellow to yellowish brown and anal fin with ground colouration reddish brown on anterior portion, and yellowish brown on posterior portion.

The Effect of Age on Cervical Sagittal Alignment

Retrospective study. To determine age-related changes in cervical sagittal alignment using whole-spine standing radiographs in asymptomatic adults. Modern surgical techniques have emphasized the importance of maintaining proper sagittal alignment. But there is a paucity of literature investigating age-related changes in cervical sagittal alignment. One hundred healthy unoperated adults who were free of spinal problems obtained whole-spine standing radiographs. They consisted of 2 groups divided by age: those in their 20s and those older than 60 years. Each group had an equal ratio of males and females. Distances from C2 as well as C7 plumb lines to the following points were measured: thoracic and lumbar apex as well as the posterior superior corner of the S1 vertebral body. In addition, Cobb angles for C0-C2, C2-C7, thoracic kyphotic angle, lumbar lordotic angle, and T1 sagittal slope angles were measured. The distance between the C2 and C7 plumb lines did not vary with age. The thoracic apex shifted caudally from T6 in the younger group to T7 in the older group. The most common lumbar apex was L4 for both groups. The distance from C2, as well as C7 plumb lines to the posterior superior corner of the S1 vertebral body, as well as the thoracic apex increased significantly in the older group. On the contrary, the distance from the 2 plumb lines to the lumbar apex decreased in the older group. Also, C2-C7 angle increased and T1 sagittal slope angle decreased in the older group compared with the younger group. However, no difference was found for the other Cobb angles between the 2 groups. The distances between the plumb lines from C2 and C7 were maintained but C2-C7 sagittal angle increased with aging.

Identification of a New Segment of the Trochlear Nerve

Introduction: The trochlear nerve is important to preserve during approaches to the skull base. Traditionally, this nerve has been divided into cisternal, cavernous, and orbital segments. Materials and Methods: Twenty latex-injected cadaveric sides (10 adult cadavers) were dissected with the aid of an operating microscope. Standard microdissection techniques were employed to examine the course of the distal cisternal segment of the trochlear nerve. Results: In all specimens, a fourth segment of the trochlear nerve was identified. This part of the nerve coursed between the entrance of the trochlear nerve into the posterior corner of the oculomotor trigone, and the posterior wall of the cavernous sinus. This segment of trochlear nerve was, on average, 3 mm in length. Conclusions: We have identified a new segment of the trochlear nerve not previously described. We propose that this be referred to as trigonal segment. Hence, the new proposed classification would be cisternal, trigonal, cavernous, and orbital. Knowledge of the microanatomy of the trochlear nerve may be of assistance to the skull base surgeon, especially during entrance into the cavernous sinus.

Computer-Assisted Surgery Patterns of Ligamentous Deformity of the Knee: A Clinical and Cadaveric Study

Knee malalignment during total knee arthroplasty (TKA) is commonly classified as either varus or valgus on the basis of a standing anteroposterior radiograph. Computer-assisted surgery (CAS) navigation TKA provides precise dynamic evaluation of knee alignment throughout the full range of motion (FROM). The goal of this study was to classify patterns of CAS-generated knee deformity curves that match specific soft tissue contracture combinations. This can then be applied as an algorithm for soft tissue balancing on the basis of the preoperative knee deformity curve. Computer navigation-generated graphs from 65 consecutive TKA procedures performed by a single surgeon were analyzed. A stress-strain curve of the coronal alignment of the knee was recorded throughout FROM before bony resection. All graphs were classified into groups according to their pattern. Cadaveric knee models were then used to test the correlation between isolated and combined ligamentous contractures and identified CAS deformity curves. An analysis of the intraoperative knee alignment graphs revealed four distinct patterns of coronal deformity on the basis of intraoperative data: 13% diagonal, 18.5% C-shaped, 43.5% comma shaped, and 25% S-shaped. Each represents the change in varus and valgus alignment during FROM. All patterns were reproduced with cadaveric knees by recreating specific contracture constellations. A tight posterior capsule gave an S-shaped curve, a tight lateral collateral ligament gave a C-shaped curve, tight medial collateral ligament gave a diagonal curve, and a tight posterior lateral corner gave a comma-shaped curve. Release of the specific contractures resulted in correction of all patterns of deformity as measured by CAS. We propose a new classification system for coronal plane knee deformity throughout FROM. This system intends to match individual and combined soft tissue pathological contractures to specific stress-strain curves obtained through routine knee CAS preparation. This classification system may provide surgeons with a general guide for soft tissue balancing during computer-navigated TKA.

A 30-year-old woman with acute knee injury

See page 1390 for the question. Additional MRI showed a prominent bone contusion at the location of the radiographically visible depression in the lateral femur condyle (figure 2). Remarkably, also a bone bruise was observed at the posterolateral side of the tibial plateau (figure 3). Furthermore, an empty notch sign, full disruption of the anterior cruciate ligament (ACL), oedema around an intact medial collateral ligament and an accompanying tear of the posterior horn of the lateral meniscus were also observed on MR (figure 4). The increased depth of the femoral notch, visible on the lateral plain knee radiograph, is an infrequent but characteristic radiological image, known as ‘lateral (femoral) notch sign’. Figure 2 Sagittal MR fat suppressed PD-weighted image shows marrow oedema (solid arrow) around a deep femoral sulcus in the lateral femoral condyle. PD, proton density. Figure 3 Coronal short T1 inversion recovery (STIR) heavily T2-weighted MRI shows bone bruise (solid arrow) on the posterolateral side of the tibial plateau as well. Figure 4 Sagittal non-fat-suppressed PD-weighted images show an anterior cruciate ligament tear (A, solid white arrow) and a tear of the posterior horn of the lateral meniscus, reaching the surface (B, white arrow). PD, proton density. The ‘lateral notch sign’ is an abnormally deep lateral condylopatellar sulcus due to a compression fracture of the lateral femoral condyle, which has been described as an indirect sign of ACL rupture. It is caused by impression of the lateral femoral condyle against the posterior lateral corner of the tibial plateau, during subluxation in the case of acute ACL tear, similar to a Hill-Sachs lesion of the humerus caused by anterior dislocation of the glenohumeral joint. This impaction causes a pattern of injuries well known as ‘kissing contusions’, which are usually radiographic occult injuries to the cartilage and bone. In 92–100% of patients with acute ACL rupture, …

Global sagittal alignment and health-related quality of life in lumbosacral spondylolisthesis

Global sagittal alignment is considered as an important aspect in the management of spinal disorders, but the evidence establishing its clinical impact in lumbosacral spondylolisthesis is still poor. This study evaluated the impact of global sagittal alignment on the health-related quality of life (HRQOL) of patients with spondylolisthesis. A retrospective study of 149 consecutive unoperated children and adolescents presenting with lumbosacral spondylolisthesis (117 low-grade and 32 high-grade) was performed. Two global sagittal alignment parameters were measured on standing lateral radiographs: spinal tilt (ST) and C7 plumbline deviation (C7P deviation). All patients completed the SRS-22 questionnaire to assess HRQOL. Pearson's correlations were calculated between parameters of global sagittal alignment and HRQOL. Multiple regression analyses were also undertaken to account for slip percentage and lumbosacral kyphosis (LSK). Both global sagittal alignment parameters were correlated with the SRS-22 total score. When analyzed separately, the correlation was absent in patients with a low-grade slip but remained significant for patients with a high-grade slip (r = 0.35 for ST; r = -0.35 for C7P deviation). The relation was strengthened in high-grade spondylolisthesis when considering only patients with a C7P in front of the posterior corner of upper sacral endplate (r = 0.48 for ST; r = -0.48 for C7P deviation) and was also positive for the SRS-22 pain and appearance domains. For these last patients, the relationship with global sagittal alignment remained significant in the multiple regression analysis. HRQOL was particularly worse for high-grade patients with a C7P in front of the hip axis. In high-grade spondylolisthesis, an increasing positive sagittal alignment was related to a poorer SRS-22 total score, especially when the C7P is in front of the hip axis. Global sagittal alignment should particularly be assessed in patients with high-grade spondylolisthesis.

Paper 117: The “Lateral Notch Sign” in ACL Injury: Incidence, Mechanism, Morphology and Correlation

IntroductionThe “lateral notch sign”, an impression fracture visible on a lateral knee radiograph has been described as an indirect sign of ACL rupture. However, surprisingly few papers have been published, so compared to the “Segond sign” (which is significantly more infrequent) the “lateral notch sign” is relatively unknown amongst orthopaedic surgeons. The “lateral notch sign” is caused by an impression of the lateral femoral condyle against the posterior superior lateral corner of the tibial plateau during the subluxation in case of an ACL rupture.It was the aim of the study to analyze and compare radiographs and MRIs' of patients with ACL rupture according to frequency, location and morphology of the “lateral notch sign”. In addition, the correlations of the cause of injury and accompanying injuries of the lateral meniscus have been calculated.

Paper 131: Combined Reconstruction of CHronic Posterior Cruciate Ligament and Posterolateral Corner Deficiency: A 2-9 Year Follow Up Study

Paper 131: Combined Reconstruction of CHronic Posterior Cruciate Ligament and Posterolateral Corner Deficiency: A 2-9 Year Follow Up Study

Ryocalanus antarcticus sp. nov. (Crustacea: Copepoda) – first ryocalanoid from the Southern Ocean

A new ryocalanoid copepod, Ryocalanus antarcticus sp. nov., is described from both genders collected during the German expeditions EASIZ-II in 1998 and ANDEEP SYSTCO in 2008 above the seabed in deep waters of the Southern Ocean. The new species is well distinguished from congeners in the shape of the genital double-somite and the posterior corners of prosome, the structure of distal segments of geniculated antennule in male and details of leg 1 and limb armament. Species of Ryocalanus are separated into two groups. Group I contains medium to large sized copepods with a single rostrum, a geniculated moderately modified right antennule in the male, and the distal segments of the male uniramous leg 5 armed with terminal spines. Group II of Ryocalanidae share the small size (<1.6 mm), a bifid rostrum, the male highly complex geniculated right antennule, with strongly modified distal segments, and an indistinctly biramous male leg 5 with distal exopod segments lacking terminal spines. R. antarcticus sp. nov. is the first ryocalanoid copepod recorded from the Southern Ocean.

Crusaceans family Melitidae (Amphipoda - Gammaridea) from Vietnam sea

Crusaceans family Melitidae (Amphipoda - Gammaridea) from Vietnam sea

A New Species of the Genus Scincella Mittlemann, 1950 (Squamata: Scincidae) from Vietnam

We describe a new species of Scincella based on a single specimen from Dien Bien Province, northern Vietnam. Scincella darevskii sp. nov. is distinguished from its congeners by the following character combination: size large (SVL 88.6 mm); prefrontals separated; supraoculars 5; primary temporal single; external ear opening present, with 3 lobules on anterior margin; midbody scales in 28 rows; dorsal scales smooth, in 6 rows across the back; paravertebral scales 62, not widened; dorsum and tail base bronze with a light dorsolateral stripe from neck to hindlimb; upper lateral zone with dark brown stripe from nostril to anterior corner of eye and from posterior corner of eye to tail base; another light stripe running from nostril below the eye to tympanum and continuous to anterior groin. In addition, we discuss the validity of S. ochracea based on examination of type material, and we comment on the diversity of Vietnamese Scincella , the species number of which increased from four to currently nine within one year only.

A New Miniature Treefrog of the Scinax ruber Clade from the Cerrado of Central Brazil (Anura: Hylidae)

Abstract We describe a new species of treefrog of the Scinax ruber clade related to Scinax fuscomarginatus from southwest of the state of Goias in central Brazil. The new species is characterized by its small size (snout–vent length of males, 15.9–18.6 mm; females, 18.1–18.7 mm), very slender body, a snout that is strongly acute in lateral view and subelliptical in dorsal view, two lateral broad blackish stripes from the posterior corner of the eye to inguinal region, reduced toe webbing, and advertisement calls that are a single pulsed note with a pulse period of 2–13 ms and a dominant frequency of 2.51–5.95 kHz. Vocalizations of the new species and S. fuscomarginatus, Scinax parkeri, Scinax squalirostris, and Scinax wandae are provided and discussed.

Lumbo-pelvic lordosis and the pelvic radius technique in the assessment of spinal sagittal balance: strengths and caveats

The two main methodologies described for the assessment of spinal sagittal alignment are the pelvic radius (PR) technique and that based on measures of the Pelvic Incidence (PI) and Spino-Sacral Angle (SSA). Both methods stress the fundamental relationship between the anatomical position and orientation of the sacrum within the pelvis and the spinal curves above. The aim of the current study was to assess the strengths and potential weaknesses of the PR technique. The PR technique uses measures based on a line (the PR), drawn between the hip axis and the posterior corner of the S1 endplate. The angle formed between the PR line and the sacral endplate, PRS1, is a developmental measure of sacropelvic morphology. Geometrically, PI and PRS1 are approximately complementary angles and both reflect reciprocal alterations in pelvic tilt (for PI) or angulation (for PRS1) and the slope of the S1 endplate. The angle formed between PR and T12, the PR-T12, reflects a combined measure of pelvic morphology and lumbar lordosis. It appears to be a useful measure, which provides a simple and rapid assessment of lumbopelvic sagittal balance, but only in the presence of a congruent thoracic curvature. After reviewing the literature, published measures made using the PR technique were compared to measures taken from a substantial patient population (479 adult patients). Errors can occur using the PR technique if the PRT12 is viewed in isolation from the thoracic kyphosis. We found the ratio of the thoracic kyphosis to lumbar lordosis (T4-T12/T12-S1) to be a useful predictor of congruent sagittal alignment, which may alert the clinician to situations where use of the PR-T12 in isolation may be misleading.

Quality Control of Reconstructed Sagittal Balance for Sagittal Imbalance

Prospective radiographic study. To investigate the feasibility of controlling quality of reconstructed sagittal balance for sagittal imbalance. Patients with sagittal imbalance cannot walk or stand erect without overwork of musculature because of compromised biomechanical advantage. The result is muscle fatigue and activity-related pain. During reconstructive surgery, restoration of optimal sagittal balance is crucial for obtaining satisfactory clinical results. However, there is no way to control quality of reconstructed sagittal balance before or during surgery. A method was developed to determine the lumbosacral curve in a way that theoretically would bring sagittal balance to an ideal state by calculation and simulation for each patient before surgery and then template rods of the curve and a blueprint were made accordingly for operative procedures. Ninety-four consecutive patients with sagittal imbalance due to lumbar kyphosis were treated for intractable pain and then followed up for a mean of 4.3 years. Radiographs were analyzed before surgery, 2 months after surgery, and at most recent follow-up. The mean estimated values of L1-S1 lordosis, sacral inclination angle, sacrofemoral distance, and distribution of L1-S1 lordosis at the closing-opening wedge osteotomy site and L4-S1 segments were 30.8°, 24.6°, 0 mm, 16.1% (-5°), and 62% (-19°), respectively. The mean reconstructed values were 41.1°, 23.3°, 3.9 mm, 41% (-17°), and 46% (-19°), respectively. There were significant differences between estimated and reconstructed values of L1-S1 lordosis and the percentage of distributions; however, there was no significant difference between the estimated and reconstructed magnitude of L4-S1 lordosis, sacral inclination angle, and sacrofemoral distance. A properly oriented pelvis can be brought nearly directly above the hip axis. The mean sagittal global balance, represented by the distance between the vertical line through the hip axis and sacral promontory, improved from 61.4 mm before surgery to 3.9 mm 2 months after surgery, and 1.3 mm at final follow-up. Normal sagittal global balance was reconstructed and maintained. The mean sagittal spinal balance measured as the horizontal distance between the C7 sagittal plumb line and the posterior superior corner of S1 improved from 97.4 mm before surgery to 11 mm 2 months after surgery. However, there was significant loss of sagittal spinal balance to 25.4 mm at the fi nal visit. Normal sagittal spinal balance was reconstructed and appeared to be maintained. The magnitude of T1-T12 kyphosis compensated from 13° before surgery to 25.2° 2 months after surgery and 34.5° at fi nal follow-up. Quality control of the reconstructed sagittal balance for sagittal imbalance is possible. Correctly orienting the pelvis, reconstructed by the restoration of enough L1-S1 lordosis with adequate distribution at L4-S1 segments, is a matter of critical importance for optimizing reconstructed sagittal balance. The correctly oriented pelvis can be determined before surgery. Preventing junctional fracture and persistent rehabilitation of surgically injured lumbar extensor musculature are crucial for maintaining the reconstructed sagittal balance.

Biomechanical Analysis of the Strength of the Mandible After Marginal Resection

This study investigated the biomechanical behavior of the mandible after marginal resection by tensile test in a human cadaveric mandible and finite element (FE) analysis. Human cadaveric mandibular models after marginal resection were prepared with residual heights of 5, 10, and 15 mm. The strength in each of these mandibular models was examined by tensile testing. In addition, FE models of the mandible after marginal resection were prepared with residual heights of 5, 7.5, 10, 12.5, and 15 mm. Distribution and magnitude of von Mises stress were analyzed by applying bite forces of 151 N as a point load on the incisal region and 355.2 and 478.1 N on the premolar and molar regions on the nonresected and resected sides, respectively. At the molar region of the resected side, bite forces of 368.5 N and 286.9 N (80% and 60%, respectively, of 478.1 N) were also applied. On tensile testing, all cadaveric mandibular models were broken at the posterior resection corner. The tensile force was significantly larger in the model with a residual height of 15 mm compared with that of those with a 5- or 10-mm residual height. On FE analysis, von Mises stress was concentrated at the resection corner. The region of maximal von Mises stress concentration in FE models was consistent with that showing destruction on tensile testing. The relationship between the residual height and von Mises stress in the resection area was linear in models of the incisal, premolar, and molar loading on the nonresected side and quadratic in models of the premolar and molar loading on the resected side. The maximal von Mises stress in the resection area was highest during molar loading on the resected side under the present loading condition and exceeded the threshold for the development of pathologic fracture in the model with a residual height of around 10 mm or less. However, the maximal von Mises stress decreased in parallel with the reduction of bite force in the molar region of the resected side. The residual height and bite force are critical factors for the prevention of pathologic fracture of the mandible after marginal resection. Currently, a residual height of more than 10 mm and reduction of bite force are recommended to reduce the risk of fracture.