Superior Gluteal Nerve Anatomy and Its Injuries: Aiming for a More Secure Surgical Approach of the Pelvic Region.

Because most of the recognized causes of superior gluteal nerve (SGN) injury are iatrogenic, detailed knowledge of the anatomy of the SGN is crucial to prevent its injury associated with surgical procedures. This study aims to describe the precise location of SGN or its branches at the greater sciatic foramen, measure the distances of these neural structures to palpable bony landmarks, and evaluate the possible correlation between these parameters and pelvis size. Twenty human cadaveric hemipelvises were studied. After dissection to expose the SGN or its branches at the greater sciatic foramen, the distances from these neural structures to the greater trochanter (GT), to the anterior superior iliac spine (ASIS), to the posterior superior iliac spine (PSIS), to the ischial tuberosity (IT), and to the greater sciatic notch apex were measured. We found that at the greater sciatic foramen, the SGN emerges as a common trunk in 75% of hemipelvises, and already divided in its superior and inferior branches in 25% of hemipelvises. When the SGN exits the pelvis as a common trunk, it does so, in most cases, in contact with the bone at the apex of the greater sciatic notch or superior to the level of the apex. The median distance from the SGN at the greater sciatic notch to the PSIS, ASIS, GT and IT is 7.6 cm, 10.9 cm, 7.5 cm and 10.8 cm, respectively. We found a positive correlation between some of the analyzed parameters and the size of the pelvis. The anatomical data of this study may serve as pivotal guides during orthopedic pelvic surgery, contributing to minimize SNG iatrogenic lesions with significant implications in the patient's quality of life.

The Surgical Vascular Anatomy of the Lower Lumbar Arteries and Its Implications in Minimally Invasive Spine Surgery: A Cadaveric Study.

BACKGROUND: Minimally invasive lateral lumbar interbody fusion is a technique that has become increasingly popular for the treatment of degenerative lumbar spine disease; however, the pertinent surgical vascular anatomy has not been examined in detail. The goal of this study is to examine the anatomy of the lower lumbar and median sacral arteries, which are important determinants of these surgical outcomes. METHODS: This is an observational, experimental study based on cadaveric models, including 20 embalmed adult human cadavers. The following measurements were made: length of the lumbar and median sacral arteries, vertical distance between the third and fourth lumbar arteries and the superior end plate of the corresponding vertebrae, anterior vertebral body height, and intervertebral disc height. RESULTS: Our sample showcased considerable variability regarding vascular anatomy around the lower lumbar spine. In 10% of specimens, the abdominal aorta bifurcated at the level of the L3-L4 intervertebral disc, and 20% showed variations in vena cava origin. Regarding the lumbar arteries, in 10% of the sample, the fourth lumbar artery was absent on the right side, and 10% presented a fifth lumbar artery. The median sacral artery was present in all cadavers; however, in 15% of specimens, it originated from a common trunk that also gave rise to the fourth pair of lumbar arteries. Anterior vertebral body height was smaller in L3 comparing with L5 (P = 0.003), and there was a significant cephalocaudal increase in the anterior intervertebral disc height in the analyzed levels (P < 0.001). Bilaterally, the distance between the fourth lumbar arteries and the superior end plate of the L4 vertebral body was shorter than this distance at the L3 vertebral body (P < 0.001 and P = 0.002 on the right and left, respectively). CONCLUSIONS AND CLINICAL RELEVANCE: These data may be useful in spine surgery planning and operative management. These anatomic variations should be identified beforehand to prevent difficulties during surgery and possible complications.

Deep gluteal space anatomy and its relationship with deep gluteal pain syndromes.

INTRODUCTION: Increasing interest has been seen in understanding the anatomy and biomechanics involved in the Deep Gluteal Syndrome, therefore the main objective of our paper was to define the anatomy of the deep gluteal space concerning the important osseous, muscular and neurological structures. METHODS: 12 cadaveric models (24 hemipelvises) were used. We proceeded with classical anatomic dissection and evaluated numerous osseous, musculotendinous and neurologic structures and their relationships. We also determined the femoral anteversion and neck-shaft angles. RESULTS: We found that 15.4% of lower limbs examined presented variations in the sciatic nerve (SN) emergence, and this was significantly longer in men. The distance from the SN to the trochanteric region was also significantly lower in males.The average ischiofemoral distance (IFD) was 2.5 ± 1.3 cm, at the same time that the structures comprised in that space showed superior areas, such as the quadratus femoris (QF) with 5.0 ± 1.1 cm and the SN with 1.4 ± 0.3 cm widths.Besides that, we also evaluated the distance from the SN to the lesser trochanter (LT) and the ischial tuberosity (IT), in the ischiofemoral space, reaching average values of 1.1 ± 0.7 cm and 1.5 ± 0.6 cm respectively.Regarding the relationship between the proximal hamstring insertion, we verified that the LT was at an average distance of 1.6 ± 1.1 cm, that the SN was only 0.2 ± 0.3 cm lateral to it, and the PN is just 2.6 ± 1.2 cm proximal to it. CONCLUSIONS: Our study confirmed the extreme variation in the SN origin that can contribute to the Piriformis syndrome. The IFD obtained in our study showed that this distance was small for the structures contained in this space.The proximal hamstring insertion showed a significantly more extended footprint in males, which puts the pudendal nerve (PN) at higher risk of iatrogenic injury.

Coracoid morphology and humeral version as risk factors for subscapularis tears.

BACKGROUND: The pathophysiology of subscapularis (SS) lesions is still relatively unknown despite recent interest in predictive factors for SS tears. Our goal was to determine the influence of the coracoid morphology and humeral version on SS tears. METHODS: This was a retrospective, controlled, single-blinded study. We analyzed 232 shoulders with SS lesions confirmed by magnetic resonance imaging. The coracoid proximal length, coracoid distal length (CLD), and coracoid total length were measured. The coracoid length ratio, coracoid angle (CA), and humeral version were also evaluated. RESULTS: We found that greater humeral retroversion was progressively related to more serious SS injuries, with values of -28.6° ± 19.5° and -51.0° ± 11.1° in the normal SS group and tear group, respectively (P < .001). The same tendency was shown for the CA, with values of 123.8° ± 11.1° in the control group vs. 97.4° ± 10.1° in the tear group (P < .001). Greater CLD, coracoid total length, and coracoid length ratio were also associated with an increased risk of SS tears (P < .001). The CA and CLD represented the best predictors of SS tears, presenting areas under the receiver operating characteristic curve of 90.0% and 89.0%, respectively. CONCLUSIONS: This article is the first to study the influence of different parameters of the coracoid process morphology and humeral version on SS tears. We proved that humeral version and coracoid morphology were important risk factors for SS pathology and could accurately predict these lesions. Finally, our study was the first to create a classification system to divide coracoids according to their morphology and relative risk of associated SS tears.