The Anatomical Course of the Femoral Nerve with Regard to the Direct Anterior Approach for Total Hip Arthroplasty.

BACKGROUND: Femoral nerve (FN) injury is noted as a serious neurological complication following total hip arthroplasty performed via a direct anterior approach (DAA). Therefore, we aimed to clarify the anatomical course of the FN around the acetabular rim and in relation to retractor placement during DAA. METHODS: According to standard protocol, a DAA for total hip arthroplasty was performed on 69 hemipelves from formalin-preserved full-body donors. The surgery was halted after retractor placement at the anterior part of the acetabulum. Then dissection was performed to expose the FN and the iliopsoas muscle. Various measurements were taken using a reference line from the anterior superior iliac spine to the acetabulum's center. A total of 6 measurement points, one every 30° from 0° to 150° along the reference line were used to determine the association between the FN and the retractor tip (RT) and the anterior acetabular rim. RESULTS: The mean distance from the RT to the FN was 22.5 millimeters (mm). The distance from the FN to the anterior acetabular rim decreased from 0 to 90°, where it was 18.8 mm, before increasing again to 27.3 mm at 150°. CONCLUSIONS: In our cadaveric study, the FN was within 11 to 36 mm of the RT. Second, we found the FN to be closest to the anterior acetabular rim at 90° and 120°. Accordingly, special care should be taken during retractor placement, and if possible, placement at 90° and 120° avoided.

Embryology of the Abdominal Wall and Associated Malformations-A Review.

In humans, the incidence of congenital defects of the intraembryonic celom and its associated structures has increased over recent decades. Surgical treatment of abdominal and diaphragmatic malformations resulting in congenital hernia requires deep knowledge of ventral body closure and the separation of the primary body cavities during embryogenesis. The correct development of both structures requires the coordinated and fine-tuned synergy of different anlagen, including a set of molecules governing those processes. They have mainly been investigated in a range of vertebrate species (e.g., mouse, birds, and fish), but studies of embryogenesis in humans are rather rare because samples are seldom available. Therefore, we have to deal with a large body of conflicting data concerning the formation of the abdominal wall and the etiology of diaphragmatic defects. This review summarizes the current state of knowledge and focuses on the histological and molecular events leading to the establishment of the abdominal and thoracic cavities in several vertebrate species. In chronological order, we start with the onset of gastrulation, continue with the establishment of the three-dimensional body shape, and end with the partition of body cavities. We also discuss well-known human etiologies.

The Anatomical Course of the Superior Gluteal Nerve With Regard to the Direct Anterior Approach for Primary and Revision Total Hip Arthroplasty.

BACKGROUND: During primary and revision total hip arthroplasty (THA) lesions of the superior gluteal nerve (SGN) can substantially compromise patient outcome. For the primary direct anterior approach (DAA) and its proximal approach extensions, especially the muscular branch entering the tensor fasciae latae (TFL) muscle is at risk. SGN lesions can result in fatty atrophy and functional loss of the TFL. Therefore, the course and branching pattern of the SGN were examined and related to the DAA and its proximal approach extension. The aim of the study is to describe safe and danger zones for the SGN with regard to the DAA and its proximal extensions. METHODS: Twenty-five formalin-fixed cadavers with 48 hemipelves were dissected. The course, distribution, and branching pattern of the SGN and its muscular branch inserting into the TFL muscle were investigated with regard to the DAA with the help of anatomical landmarks like the greater trochanter and the iliac tubercle. RESULTS: In 72.9% of the specimens the SGN passed the greater sciatic foramen superior to the piriformis muscle with one main trunk. The muscular branch of the SGN supplying the TFL divided from the main branch in 89.6% of the specimens at the level of the greater sciatic foramen. Before entering the TFL muscle the muscular branch showed a variable branching pattern in the interval between the gluteus medius and minimus. A danger zone for the SGN with regard to the DAA was found in the proximal fourth of the skin incision. CONCLUSION: Special care in proximal instrument placement should be taken during the DAA. When extending the DAA proximally manipulations in the proximal, caudal surgical window should be performed with the utmost care.

The Anatomical Course of the Lateral Femoral Cutaneous Nerve in Relation to Various Skin Incisions Used for Primary and Revision Total Hip Arthroplasty With the Direct Anterior Approach.

BACKGROUND: Although the direct anterior approach (DAA) has become a standard for primary and revision total hip arthroplasty, it involves a high risk of injuring the lateral femoral cutaneous nerve (LFCN). The aim of this study is to examine the course of the LFCN in relation to various skin incisions and approach extensions used for the DAA. METHODS: We obtained 44 limbs and hemipelves from 22 formalin-preserved cadavers, in which LFCN was identified. All nerve branches of the LFCN were carefully traced. The branching pattern and the distribution in the thigh were described in relation to the standard approach for primary total hip arthroplasty, the skin crease bikini incision, the longitudinal extension, and the lazy S extension of the DAA. RESULTS: We found 31 (70.5%) Sartorius-type, 6 (13.6%) posterior-type, and 7 (15.9%) fan-type branching patterns of the LFCN. We observed 2.02 branches per hemipelvis. All fan-type LFCNs had 3 or more than 3 branches. We found that the main branch of the LFCN was medial to the primary DAA approach as well as to the lazy S extended DAA approach. The bikini incision and the incision for the longitudinal extension of the DAA crosses the main branch of the LFCN in 100% of cases. CONCLUSION: The fan-type pattern of the LFCN might be harmed by all skin incisions. Chances are high that LFCN branches could be jeopardized with a bikini-type incision and the longitudinal extension of the DAA. The risk of jeopardizing the LFCN with a lazy S-type distal extension is reduced.

Screw tip augmentation leads to improved primary stability in the minimally invasive treatment of displaced intra-articular fractures of the calcaneus: a biomechanical study.

PURPOSE: To investigate if the stability of minimally invasive screw osteosynthesis of displaced intra-articular calcaneal fractures (DIACF) can be effectively increased by an innovative approach to screw tip augmentation. METHODS: In eight-paired human cadaver hindfoot specimens, DIACF of Sanders type IIB were treated with either standard screw osteosynthesis or with bone cement augmentation of the screw tips in the main fragments. The instrumented specimens were subjected to a cyclic loading protocol (9000 cycles, with stepwise increasing loads, 100-1000 N). The interfragment motions were quantified as tuber fragment tilt (TFT) and posterior facet inclination angle (PFIA) using a 3-D motion analysis system. Böhler's angle (BA) was evaluated from X-rays. A load-to-failure test was performed after the cyclic loading protocol. RESULTS: All but one specimen of the augmented group withstood more cycles than the respective specimens of the non-augmented group. Mean cycles to failure for the failure criterion of 5° TFT were 7299 ± 1876 vs. 3864 ± 1810, corresponding to loads of 811 N ± 195 vs. 481 N ± 180, (P = 0.043). There were no significant differences observed in the PFIAs. The failure criterion of 5° BA was reached after a mean of 7929 cycles ± 2004 in the augmented group and 4129 cycles ± 2178 in the non-augmented group, corresponding to loads of 893 N ± 200 vs. 513 N ± 218, (P = 0,090). The mean load-to-failure of the four specimens in the augmented group that completed the cyclic loading was 1969 N over a 1742-2483 N range. CONCLUSION: Screw tip augmentation significantly improved the mechanical stability of the calcanei after osteosynthesis in terms of decreased tuber fragment tilts and less changes in Böhler's angle.

The supraorbital region revisited: An anatomic exploration of the neuro-vascular bundle with regard to frontal migraine headache.

BACKGROUND: Recent findings on the pathogenesis of frontal migraine headache support, besides a central vasogenic cause, an alternative peripheral mechanism involving compressed craniofacial nerves. This is further supported by the efficiency of botulinum toxin injections as a new treatment option in frontal migraine headache patients. METHODS: The supraorbital regions of 22 alcohol-glycerine-embalmed facial halves of both sexes were dissected. Both the supratrochlear and supraorbital nerves (STN and SON, respectively) were identified, and their relationship with the corrugator supercilii muscle (CSM) was investigated by dissection and ultrasound. The course of both nerves was defined, and the interaction between the supraorbital artery (SOA) and SON was determined. RESULTS: We discovered a new possible compression point of the STN passing through the orbital septum and verified previously described compression points of both STN and SON. Osteofibrous channels used by the STN and SON were found constantly. We described the varying topography of the STN and CSM, the SON and CSM, and the SON and SOA. Further, we provide an algorithm for the ultrasound visualization of the supraorbital neurovascular bundle. CONCLUSION: Our data support the hypothesis of a peripheral mechanism for frontal migraine headache because of following potential irritation points: first, the CSM is constantly perforated by the SON and frequently by the STN; second, the topographic proximity between SOA and SON and the osteofibrous channels is used by the SON and STN; and third, the STN passes through the orbital septum.