An anatomic study of the morphologic characteristics of the dorsal capitolunate ligament

PURPOSE

There is consensus in favor of a description of the dorsal ligaments of the carpus as not including a direct ligament between the lunate and capitate. On the other hand, there is an anatomical formation which, according to the currently accepted description, corresponds to the dorsal midcarpal capsule, itself thickened by the dorsal intercarpal ligament. The question is whether the capsule at this point deserves to be called an individualizable ligament. In our operative experience of the dorsal carpus, we have encountered a stout structure adherent to the lunate and capitate. In this article, we present the anatomic evidence of this structure's existence.

METHODS

Seven adult fresh frozen upper extremities were dissected. Three wrists were longitudinally sectioned in line with the middle finger metacarpal. The remaining 4 were dissected dorsally. Two representative samples of the stout structure connecting the lunate to the capitate were sent to pathology for histologic analysis and staining.

RESULTS

In all 3 of the longitudinally sectioned wrists, a thick band of tissue could clearly be seen, originating on the lunate, spanning the dorsal interval between the lunate and the capitate, and inserting on the capitate. With this structure intact, dorsal dislocation of the capitate was not possible, but preliminary sectioning of the structure allowed dislocation. In the 4 dorsally dissected wrists, the same connection was observed, palmar to the dorsal intercarpal ligament, in every specimen. The average dimensions of the dorsal capitolunate were: 15.25 ± 1 mm long, 8.75 ± 1 mm wide at the midpoint, and 1.75 ± 1 mm thick. The two specimens sent to pathology after sectioning showed longitudinally oriented collagen fibers. This structure also stained positive for elastin and contained intrasubstance vascular structures.

CONCLUSION

There is a stout ligamentous structure connecting the lunate to the capitate, palmar to the dorsal intercarpal ligament. Disruption of this structure appears to be necessary for dorsal dislocation of the capitate. Clinical studies are needed to gain better understanding of the exact function and importance of this structure.

Defining sexual dimorphism in masculinizing chest surgery using 3-dimensional imaging

There is no consensus on the ideal scar location and inframammary fold (IMF) placement in the gender-affirming double-incision mastectomy technique. Recent advances in imaging technology have facilitated noninvasive investigations into anatomic variability, in many cases, obviating the traditional approach of cadaveric dissection to answer anatomic questions. A better understanding of chest wall sexual dimorphism may allow surgeons who perform gender-affirming procedures to achieve more natural-appearing results. A total of 60 chests were analyzed using either cadaveric dissection (n = 30) or virtual dissection with 3-dimensional (3-D) reconstructions of computed tomography (CT) images (n = 30) using the Vitrea® software. Chest proportions were recorded using each technique, correlating surface anatomy with muscular and bony landmarks. Cadaveric and 3-D radiography chest analysis revealed that natal male chest walls are, on average, wider and longer than natal female chest walls. The pectoralis major muscle dimensions and the location of its insertion were not found to significantly differ between male and female chests. The male nipple-areolar complex (NAC) tended to be narrower in length and width, with a less projecting nipple than the female NAC. Finally, the IMF was found to lie over the interspace between the fifth and sixth rib in both male and female chests. Our findings confirm natal male and female IMF are positioned between the 5th and 6th ribs. This fact affirms the senior author's technique of masculinizing the chest, keeping the masculinized IMF at approximately the same level as the natal female IMF and following the pectoralis major muscle edges to define the resulting scar in a way that differs from previously reported techniques.

Measurement of the gluteal compartment pressures: A cadaveric study describing safety and reproducibility of two methods

INTRODUCTION

Gluteal compartment syndrome is an uncommon entity and physicians may use intracompartmental pressure measurements for confirmation of the clinical diagnosis, or in cases where the physical exam is indeterminate. However, there is a paucity of literature describing a safe and reproducible technique to measure gluteal intracompartmental pressures during the diagnosis of gluteal compartment syndrome. The purpose of this cadaveric study is to evaluate the sole previous technique described in the literature to measure gluteal intracompartmental pressures and provide a modified technique which can be safely and reliably utilized clinically.

METHODS

A cadaveric study with three phases was performed in 16 gluteal regions in 8 cadavers. In the first phase, the previously described technique was assessed. In the second phase, a modified set of techniques was created and evaluated. In the third phase, inter-user reliability of the modified set of techniques was assessed and calculated using Cohen's ĸ coefficient. In all three phases, methylene blue was injected through pressure monitoring needles into the gluteus maximus (GMax), gluteus medius/minimus (GMM), and the tensor fascia lata (TFL) compartments. Following dissection, rate of successful penetration into each targeted compartment and distance from the neurovascular structures was recorded.

RESULTS

The previously described set of techniques was found to be variable. The modified set of techniques was effective, successfully reaching the GMax, GMM, and TFL compartments in 100%, 100%, and 81% of attempts, respectively. Inter-user reliability was excellent (ĸ = 1) for the techniques to reach both the GMax and GMM compartments, and moderate (ĸ = 0.54) for the technique to reach the TFL compartment. Within the GMax, the pressure monitoring needle was at a mean of 5.4±0.6 cm, 4.1±0.7 cm, 6.4±0.5 cm from the sciatic nerve (SN), superior gluteal nerve (SGN), and inferior gluteal nerve (IGN), respectively. Within the GMM, the pressure monitoring needle was at a mean of 9.7±1.4 cm, 7.4±1.3 cm, 11.1±1.7 cm from the SN, SGN, and IGN, respectively.

CONCLUSION

The modified set of techniques presented allows the three gluteal compartments to be safely and reproducibly reached to measure intracompartmental pressures during the diagnosis of gluteal compartment syndrome.

Comparison of three surgical techniques of posterolateral knee reconstruction: A cadaver study

BACKGROUND

Injuries to the posterolateral corner (PLC) of the knee are often overlooked but, require reconstruction in order to restore stability in varus and external rotation. Among the many anatomic and non-anatomic PLC reconstruction techniques available, the modified Larson (mLR), LaPrade (LPR) and Versailles reconstruction (VR) procedures are widely used.

HYPOTHESIS

The hypothesis was that anatomic PLC reconstruction (VR and LPR procedures) provides better restoration and control of external rotation.

PATIENTS AND METHODS

Fifteen fresh-frozen cadaveric knees were tested to compare the 3 procedures. Varus laxity on stress radiographs in full knee extension and external rotatory laxity on dial test at 30° flexion were quantified at 3 phases: intact knee, PLC sectioned and PLC reconstructed.

RESULTS

Mean varus laxity did not differ significantly between techniques in intact knees (p=.14), after PLC sectioning (p=.14) or after PLC reconstruction (p=.17). After PLC reconstruction, varus laxity was restored, with no statistical difference between mLR, VR and LPR compared to intact test values (respectively, -1.0, -1.3 and -1.5; p=.98). In all 3 groups, mean external rotation laxity on dial test at 30° flexion did not significantly differ between intact knees (p=.32) and after PLC sectioning (p=.15). After PLC reconstruction, the mLR technique was significantly less effective in restoring rotational stability than the VR and LPR techniques (p=.025).

DISCUSSION

The VR technique provided similar outcomes to LPR for restoring stability in varus and external rotation. The 2 "anatomic" reconstruction procedures (VR and LPR) were significantly more effective than the modified Larson technique for external rotation control, confirming the study hypothesis. Consequently, it remains preferable to use anatomic techniques in multiligament injuries involving the PLC.

LEVEL OF EVIDENCE

IV, cadaver study.

A Frontal Route to Middle and Posterior Cranial Fossa: Quantitative Study for the Lateral Transorbital Endoscopic Approach and Comparison with the Subtemporal Approach

BACKGROUND

Skull base lesions within the middle cranial fossa (MCF) remain challenging. Recent reports suggest that transorbital endoscopic approaches (TOEAs) might be particularly suitable to access the MCF and expose the lateral wall of the cavernous sinus and the Meckel's cave.

METHODS

The present study was developed to compare the nuances of the subtemporal approach (STA) with those of the lateral TOEA (LTOEA) to the MCF and posterior cranial fossa (PCF) in cadaveric specimens. After orbital craniectomy, interdural opening of the cavernous sinus lateral wall (CSlw), exposure of the Gasserian ganglion, and extradural elevation of the temporal lobe was performed. Next, anterior endoscopic petrosectomy was performed and the PCF was accessed. We quantitatively analyzed and compared the angles of attack and distances between LTOEA and STA to different structures at the CSlw, petrous apex (PA), and PCF.

RESULTS

Cadaveric dissection through the LTOEA completely exposed the CSlw and PA. LTOA exhibited larger distances than the STA to all targets. Importantly, these differences were greater at the PA and its surrounding key anatomic landmarks. The horizontal and vertical angles of attack allowed by the LTOA were smaller both for the CSlw and PA. However, these differences were not significant for the vertical angle of attack at the CSlw.

CONCLUSIONS

LTOEA provides a direct ventral route to the medial aspect of MCF, PA, and PCF. Although TOEAs are versatile approaches, the unfamiliar surgical anatomy and limited instrument maneuverability demand extensive cadaveric dissection before moving to the clinical setting.

Risks of injury in distal metatarsal minimally invasive osteotomy when comparing standard and modified techniques: A cadaveric study

BACKGROUND

The objectives of the study were to evaluate the structures at risk in distal metatarsal mini-invasive osteotomy (DMMO) and to compare standard and intraosseous approaches.

METHODS

DMMO was performed on the second and fourth metatarsals of 11 fresh-frozen cadaveric specimens. The standard technique was performed in 11 metatarsals. It was then compared to a modified intraosseous technique that entails starting inside the bone in 11 other metatarsals. The cadavers were dissected to identify unintentional injury to soft tissue structures.

RESULTS

In the standard group the most injured structures were the metatarsal joint capsules (MJC) (27%), extensor digitorum longus (EDL) (18%), and extensor digitorum brevis (EDB) (9%). The modified intraosseous group injured the EDL (27%), not the MJC (0%) and the EDB (0%). Distances between osteotomies and the dorsal metatarsal head articular surface (DMHAS) were 6.08 ± 3.99 mm in the standard and 9.92 ± 3.42 mm in the modified (p = 0.02).

CONCLUSION

The DMMO techniques most frequently injured the EDL. Intra-articular positioning of the osteotomy was more observed in the standard. Overall, it appears the modified method could be an alternative to the standard DMMO.

CLINICAL RELEVANCE

The modified minimally invasive DMMO has a comparable rate of potential iatrogenic injuries. This intraosseous procedure may present as an option when planning surgery to the lesser metatarsals.

LEVEL OF EVIDENCE

Level III. Comparative Cadaveric Study.

Anatomic Study of the Medial Collateral Ligament in Thai Population: A Cadaveric Study of 56 Elbows

PURPOSE

This study aims to elucidate basic anatomic and geometric features of MCL, providing more accurate and detailed information, as guidance for surgeons, to improve patient's outcome of the treatment.

METHODS

The anterior bundle (AB), posterior bundle (PB) and transverse bundle (TB) ligament of 56 fresh frozen Thai cadaveric elbows, were measured and recorded, comprise key ligament's geometric features, footprints and dimensions, and its relation to bony landmarks. Sagittal and coronal planes were used in respect of the anatomical position.

RESULTS

The mean distance between the center of AB origin and the apex of medial epicondyle is as follows: 2.97 ± 2.21 mm anteriorly, 4.73 ± 1.60 mm inferiorly in the sagittal plane, and 4.23 ± 1.13 mm deep from the epicondyle in the coronal plane. Its dimension is 6.23 ± 1.02 mm in width and 45.97 ± 6.75 mm in length. The ligament's insertion triangular shape has its base located 28.44 ± 3.51 mm anterior from the posterior olecranon border, and 22.52 ± 2.49 mm superior from the inferior ulnar border. The tip located 50.79 ± 4.86 mm anterior from the posterior olecranon border and 17.64 ± 2.80 mm superior from the inferior ulnar border.

CONCLUSION

Apprehension of the precise geometries and distances of the ligament's footprint relative to key anatomical point is crucial. This stereographically comprehended data are useful for surgeon as reference points to obtain stability, motion, kinetic, and kinematic properties of the elbow.

LEVEL OF EVIDENCE

Level V evidence.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s43465-022-00648-x.

An anatomic and 3D study of the development of the proximal humeral physis

PURPOSE

During maturation, the ossification centers of the proximal humerus form a characteristic pattern consisting of a metaphyseal peak and corresponding epiphyseal valley. The surface topographies of the metaphyseal peak and epiphyseal valley are not well described and may have variation with age and structural importance to the pathogenesis of proximal humeral epiphysiolysis.

METHODS

High-resolution 3-dimensional surface scans of 24 cadaveric proximal humeral epiphyses and metaphyses in specimens aged 3 to 18 years were obtained. Computer modeling software was used to measure the peak height of the metaphysis and maximal depth of the epiphysis relative to a perpendicular line drawn across the proximal humeral physis.

RESULTS

The metaphyseal peak had a mean height of 12.7 ± 1.6 mm while the epiphyseal valley had a mean depth of 13.1 ± 2.1 mm, both consistently positioned in the posterolateral quadrant. Both the absolute metaphyseal peak height (R² = 0.536; p < 0.001) and absolute epiphyseal valley depth (R² = 0.524; p < 0.001) increase with advancing age. Multiple linear regression analysis demonstrated that normalized metaphyseal peak height + sex (adjusted R² = 0.408; p < 0.002) correlated more with age than normalized epiphyseal valley depth + sex (adjusted R² = 0.128; p < 0.091).

CONCLUSION

Prominence of the metaphyseal peak and epiphyseal valley both increase with advancing age, with a lower correlation between normalized sizes with age as compared to the absolute sizes, suggesting that these structures stay relatively proportional with growth.

Anatomic Study Quantifying the Relationship Between the Arcuate Eminence and the Root of the Zygoma: Application to Skull Base Surgery

OBJECTIVE

The aim of this study was to define the structural relationship between the arcuate eminence (AE) and a known fixed external bony landmark, the root of the zygoma (ZR), and to determine its reliability as a consistent guide for guiding surgical approaches. To our knowledge, this is the only anatomic study to quantify the relationship between the AE and ZR.

METHODS

Twenty-one dry temporal bones were measured using digital calipers. The distance from the posterior aspect of the ZR to the midpoint of the AE was measured. Additionally, the anteroposterior distance between the ZR and AE and vertical distance between the 2 structures were measured. Student's t-test was used to compare the left and right sides.

RESULTS

An AE was found in every specimen. The mean ZR to AE distance was 30.9 mm. On most sides (91%), the ZR was located more inferiorly than the AE with a mean distance of 3 mm between the 2 structures. The mean distance between the AE and ZR was 17 mm. On all sides, the AE was located posterior to the ZR. No significant differences were found between sides. No anatomic variations or pathologic conditions were noted in any of the specimens.

CONCLUSIONS

The ZR is an easily identifiable and consistent bony landmark often used by skull base surgeons. In this investigation, we measured the anatomic relationships between the ZR and AE. Such data might assist in planning surgical trajectories and minimizing complications when skull base pathologies are approached.

Biportal endoscopic transorbital approach: a quantitative anatomical study and clinical application

BACKGROUND

We devised a biportal endoscopic transorbital approach (BiETOA) to gain surgical freedom by making a port for the endoscope and investigated the benefits and limitations of BiETOA.

METHODS

A cylindrical port was designed and 3-D printed using biocompatible material. The port was inserted through a keyhole between the superolateral side of the orbital rim and the temporal muscle. An endoscope was inserted through the port, and other instruments were inserted through the conventional transorbital route. BiETOA was used to dissect eight cadaveric heads, and the angle of attack and surgical freedom were assessed.

RESULTS

The mean maximal angle of attack was significantly different in BiETOA and endoscopic transorbital approach (ETOA) (P < 0.01) but not in BiETOA and ETOA lateral orbital rim (LOR) osteotomy (P = 0.207, P = 0.21). The mean surgical freedom was significantly different in BiETOA and ETOA (P < 0.01) and in BiETOA and ETOA LOR osteotomy (P < 0.01). In the clinical cases, tumors were removed successfully without any complications.

CONCLUSIONS

BiETOA provided increased surgical freedom and better visibility of deep target lesion and resulted in good surgical and cosmetic outcomes.

Comparative Analysis of Pterional, Supraorbital, Extended Supraorbital, and Transtubercular-Transplanum Approaches for Exposing the Anterior Communicating Artery Complex: A Cadaveric Study

OBJECTIVE

We aimed to quantify and compare surgical exposure and freedom at the anterior communicating artery (ACoA) complex using pterional (PT), supraorbital (SO), extended supraorbital withorbital osteotomy (SOO), and endonasal endoscopic transtubercular-transplanum (EEATT) approaches.

METHODS

Right-sided PT, SO, SOO, and EEATT approaches were performed using 10 cadaveric heads. Surgical exposure and freedom (horizontal and vertical attack angle) at the ACoA complex were measured. The farthest clipping distance from ACoA to A1 (precommunicating segment of the anterior cerebral artery)/A2 (postcommunicating segment of the anterior cerebral artery) was also quantified.

RESULTS

There was a significantly greater exposure length of right A1 in the PT approach (12.20 ± 2.48 mm) compared with the EEATT approach (9.52 ± 2.09 mm; P = 0.029). Among the 4 approaches, EEATT provided the shortest clipping distance for right A1 (6.56 ± 1.33 mm; P = 0.001) and the longest clipping distance for right A2 (3.36 ± 1.24 mm; P = 0.003). SO, SOO, and PT approaches (2.9 ± 0.9) had more observations on perforators from ACoA than did the EEATT approach (2.0 ± 0.66; P = 0.029). The EEATT approach (50.90 ± 17.45 mm²) provided better exposure of the superior part of the ACoA complex compared with the SO approach (29.37 ± 17.27 mm²; P = 0.05). PT and SOO approaches provided the greatest horizontal (36.88° ± 5.85°) and vertical (19.37° ± 4.70°) attack angle, respectively.

CONCLUSIONS

The SO, SOO, and PT approaches provided a better hemilateral view of the ACoA complex and similar surgical exposure, whereas the EEATT approach offered greater exposure in the upper part of the ACoA complex, with relatively limited exposure of perforators from ACoA and surgical freedom. The EEATT approach can play a role in exposure of lesion involving the ACoA complex.

Minimally Invasive Approaches to the Lateral Cavernous Sinus and Meckel's Cave: Comparison of Transorbital and Subtemporal Endoscopic Techniques

BACKGROUND

Transorbital and subtemporal keyhole approaches have recently been proposed to approach lesions in the lateral wall of the cavernous sinus (CS) and Meckel's cave (MC). Our goal was to compare these approaches and suggest indications for each of them.

METHODS

Five cadaver heads (10 sides, 40 procedures) were used. The lateral transorbital approaches were carried out without and with the removal of the lateral orbital rim, herein referred to as the lateral transorbital approach (LTOA) and the lateral orbital wall approach (LOWA). The subtemporal approaches were performed without and with the removal of the zygomatic arch, referred to as the subtemporal approach (STA) and the subtemporozygomatic approach (STZA). Five targets were chosen and 2 triangles were created representing the lateral wall of the CS and MC. Stereotactic measurements were quantified to calculate angles of attack, surgical freedom, and temporal lobe retraction for each approach.

RESULTS

LTOA presented the smaller horizontal angles of attack. LOWA increased the angles to the same level of STA and STZA. STA and STZA presented larger vertical angles of attack. The surgical freedom presented gradual increase from LTOA to LOWA, STA, and STZA. STA and STZA needed greater temporal lobe retraction for most targets.

CONCLUSIONS

LTOA is a good option to biopsy a lesion in the lateral wall of the CS and LOWA increased the surgical corridor to work with microsurgical techniques. STA and STZA could be better options when wide exposure is necessary, but temporal lobe retraction should be taken into consideration.

Ulnar facet locking screw locations of volar locking plates placed without flexor pollicis longus tendon contact: A cadaver study

BACKGROUND

The volar locking plate (VLP) system provides stable fixation and is widely used for distal radius fractures. Studies have shown that irritation of the implant prominence is a risk factor for flexor tendon rupture, especially of the flexor pollicis longus (FPL). Contact between VLPs and flexor tendons should be avoided. We aimed to investigate the ulnar facet locking screw locations of various VLPs placed without FPL tendon contact in cadaver wrists.

HYPOTHESIS

We hypothesized that ulnar facet locking screws would be in the vicinity of the subchondral bone when the plate is placed in the most distal position without FPL tendon contact.

MATERIALS AND METHODS

The study assessed two variable-angles and four fixed locking plates. We placed each plate in six different cadavers, resulting in 36 different plate-cadaver combinations. Plates were placed in the most distal position without FPL tendon contact. We drilled the most ulnar hole (hole A) and the second ulnar hole (hole B) of the distal row. All drilling procedures were performed using a specific jig for each fixed locking plate. For variable-angle locking plates, we drilled with a fixed jig for each plate. We obtained lateral radiographs when the drill penetrated the dorsal cortex and measured the distance between the drill and the articular surface.

RESULTS

With regard to hole A, the mean distances between the drill and the center of the articular surface were 2.6-5.2mm for the four fixed locking plates and 4.9-5.6mm for the two variable-angle locking plates. With regard to hole B, the mean distances between the drill and the center of the articular surface were 3.8-5.9mm for the four fixed locking plates and 5.5-5.9mm for the two variable-angle locking plates.

DISCUSSION

When clinicians place a VLP without FPL tendon contact, the distance between the ulnar facet screws and the center of the articular surface is over 3mm in most cases. Surgeons should select variable-angle drilling for strong articular support when using variable-angle locking plates.

LEVEL OF EVIDENCE

III, diagnostic Level.

The distance from the peroneal tendons sheath to the sural nerve at the posterior tip of the fibula decreases from proximal to distal

PURPOSE

The aim of this study is to compare the distance from the peroneal tendons sheath to the sural nerve in different points proximally and distally to the tip of the fibula.

METHODS

Ten fresh-frozen lower extremities were dissected to expose the nerves and tendons. Having the posterior tip of the fibula as a reference, the distance between the tendons sheath and the sural nerve was measured in each point with a tachometer with three independent different observers. Two measures were taken distally at 1.5 and 2 cm from fibula tip and 3 measures were performed proximally at 2, 3, and 5 cm from fibula tip. Data were described using means, standard deviations, medians, and minimum and maximum values.

RESULTS

The average distance between distance between the fibula tip and sural nerve is 16.6 ± 4.4 mm. The average distance between peroneal tendons sheath and the sural nerve at 5 cm, 3 cm, and 2 cm from the proximal fibular tip was 29.6 ± 3.2 mm, 24.2 ± 3.6 mm, and 19.7 ± 2.7 mm, respectively. The average distance between the peroneal tendons sheath and the sural nerve at 2 cm and 1.5 cm distal to fibular tip was 9.1 ± 3.5 mm and 7.8 ± 3.3 mm, respectively.

CONCLUSION

The distance from the peroneal tendons sheath to the sural nerve decreases from proximal to distal. As the distance between the peroneal tendons sheath and the sural nerve decreases from proximal to distal, performing the tendoscopy portal more distally would increase the risk of nerve iatrogenic injury.

What is the difference in morphologic features of the lumbar vertebrae between Caucasian and Taiwanese subjects? A CT-based study: implications of pedicle screw placement via Roy-Camille or Weinstein method

BACKGROUND

Safe placement of pedicle screws without jeopardizing neurovascular structures medially and anteriorly is important during spine surgery. Inferior breach of pedicle is also dangerous due to low margin of error. Lumbar morphology and identical pedicle orientation at L1 to L5 shown on CT scan of young Taiwanese patients (90 patients) were analyzed and compared with findings reported for Caucasian subjects.

METHODS

Previously reported techniques were employed to quantitatively elucidate the parameters regarding lumbar morphology and identical pedicle orientation at each vertebra. The parameters for pedicle angle (PA), pedicle diameter (PD), pedicle axis distance (PAD), midline axis distance (MAD), transverse pedicle axis distance (TPAD) and transverse intertangential angle (TITA) were measured.

RESULTS

Taiwanese subjects had different PA, PD, PAD, MAD at L1 to L5 and TITA at L3 to L5 compared with Caucasian subjects. L5 had the most convergent pedicle axis, the widest PD and the shortest antero-posterior axis morphology.

CONCLUSIONS

This study provides detailed information for identifying pedicle orientation during pedicle screw placement and elucidate racial differences in lumbar morphology and pedicle orientation between Taiwanese and Caucasian populations.

The distance from the peroneal tendons sheath to the sural nerve at the posterior tip of the fibula decreases from proximal to distal

PURPOSE

The aim of this study is to compare the distance from the peroneal tendons sheath to the sural nerve in different points proximally and distally to the tip of the fibula.

METHODS

Ten fresh-frozen lower extremities were dissected to expose the nerves and tendons. Having the posterior tip of the fibula as a reference, the distance between the tendons sheath and the sural nerve was measured in each point with a tachometer with three independent different observers. Two measures were taken distally at 1.5 and 2 cm from fibula tip and 3 measures were performed proximally at 2, 3, and 5 cm from fibula tip. Data were described using means, standard deviations, medians, and minimum and maximum values.

RESULTS

The average distance between distance between the fibula tip and sural nerve is 16.6 ± 4.4 mm. The average distance between peroneal tendons sheath and the sural nerve at 5 cm, 3 cm, and 2 cm from the proximal fibular tip was 29.6 ± 3.2 mm, 24.2 ± 3.6 mm, and 19.7 ± 2.7 mm, respectively. The average distance between the peroneal tendons sheath and the sural nerve at 2 cm and 1.5 cm distal to fibular tip was 9.1 ± 3.5 mm and 7.8 ± 3.3 mm, respectively.

CONCLUSION

The distance from the peroneal tendons sheath to the sural nerve decreases from proximal to distal. As the distance between the peroneal tendons sheath and the sural nerve decreases from proximal to distal, performing the tendoscopy portal more distally would increase the risk of nerve iatrogenic injury.

Radiographic Study of Lumbar Sympathetic Trunk in Oblique Lateral Interbody Fusion Surgery

BACKGROUND

Oblique lateral interbody fusion (OLIF) surgery provides a convenient and minimal access to the lesion disc with few complications; however, the left lumbar sympathetic trunk (LST) lies in the surgical field with a certain incidence of injury. The aim of this study was to describe the anatomic structures of the left LST at risk for injury during OLIF at different lumbar segment levels based on radiologic evaluations.

METHODS

Forty-four healthy young people (22 men and 22 women) were recruited, and routine lumbar magnetic resonance radiograph was performed. The LST, abdominal aorta (AA), and psoas muscle (PM) were observed, and all parameters were acquired using axial T2-weighted turbo spin echo sequence images. Independent-samples t test, 1-way analysis of variance test, and Least significant difference test were used to explore the LST's tract and the anatomic relationship with the adjacent anatomic landmarks at different levels.

RESULTS

The distance from the left lateral border of the AA to the anterior medial border of the left PM was significantly narrowing from the L2-3 to L4-5 segment levels (13.72 ± 3.00, 11.78 ± 2.69, and 9.18 ± 3.43 mm). The distance from the left lateral border of the AA to the left LST was also significantly decreased from the L2-3 to L4-5 segment levels (11.14 ± 2.89, 9.36 ± 2.79, and 6.63 ± 2.94 mm). However, the distance from the leading edge of the left PM to the left LST had no statistical differences among all adjacent segment levels (2.96 ± 0.62, 2.83 ± 0.62, and 3.07 ± 0.86 mm). The location of the left LST is more backward and lateral at level L2-3, whereas it is inside front at levels L3-4 and L4-5.

CONCLUSIONS

The practical risk of LST injury in different segment levels varied with specific anatomic conditions. The segment level L2-3 could provide a safer surgical space for OLIF, and the risk of the left LST injury might be greater during OLIF at level L4-5.

Proper detailed parameters for S1 sacral alar iliac screw placement in the Chinese population, a 3D imaging study

Background

S1-AI technique may be used as a salvage technique in pelvic fixation of complex spinal deformity surgery. However, the proper detailed parameters in the Chinese population has not been analyzed before to instruct S1-AI screws placement and to ensure the safety of clinical application while the trajectory in pelvic changes significantly at each angle.

Results

The ideal S1AI screw trajectory could be obtained in 28 of 30 female patient images (93.3%) and in all of the male patient images (100%). The screws that have already been used clinically in S2AI pathways can be applied in S1AI fixations.

Conclusion

It is feasible to place S1AI screws in 93.3% of female Chinese adult patients and in all male Chinese patients. Preoperative CT reconstruction should be performed to evaluate proper trajectory parameters and to avoid anterior violation.

Femoro-acetabular impingement: anatomic study of reliability and accuracy of alpha angle and offset ratio on fifty consecutive peri-operatively resected femoral heads

PURPOSE

The purpose of this study was to determine whether X-ray attributes of the femoro-acetabular impingement (FAI) - alpha angle (AA) and offset ratio (OR) reflect real measurements on resected femoral heads.

METHODS

FAI AA and OR were assessed on 50 consecutively-resected femoral heads. The parameters were measured on heads cut through the maximum range of the deformity and compared to the same parameters on standardized X-ray projections (anterior-posterior [AP] and axial views).

RESULTS

Mean AA was 76.47° on dissected heads vs. 75.81° on axial X-ray (p = 0.688). Mean OR was 0.132 on dissected heads vs. 0.220 on axial X-ray (p < 0.001). Mean AA on ideal AP X-ray was 79.46° vs. 81.51° on AP standing plain X-ray view (p = 0.431). AA measurements on plain X-ray AP and axial view of halved femoral heads correlated highly.

CONCLUSIONS

AA on axial X-ray view reflected the real AA in our series, but the risk of cartilage damage cannot be predicted.

An anatomic study of the lateral patellofemoral ligament

Objective

The lateral patellofemoral ligament (LPFL) is part of the lateral retinaculum cut during arthroscopic or open release. We investigated its anatomic and morphometric characteristics.

Materials and methods

We identified the LPFL insertion point on the condyle in vertical and sagittal planes in 32 adult cadaveric knees. We measured its length and width at the insertion point. We located the midpoint of this point and measured from it to the distal and posterior condylar ends. We measured anterior-posterior and proximal-distal lateral condylar lengths. We evaluated the insertion point shape on the lateral femoral condyle. Degree of relationship between variables was assessed using Pearson's correlation coefficient. p < 0.05 was considered statistically significant.

Results

The LPFL mean length was 23.2 mm, and mean width at the insertion point was 15.6 mm. Regarding its insertion into the lateral condyle, central insertions were more frequent (vertical plane: 53.1% central and sagittal plane: 75% central). A significant positive correlation was evident between the LPFL length and width at the insertion point (p = 0.05). Thus, the LPFL length was proportional to its width at the insertion point. A significant positive correlation was found between the anterior-posterior condylar length and width of the LPFL at the insertion point (p = 0.017). Therefore, greater anterior-posterior condylar length equates to a larger area of insertion on the condyle.

Conclusion

Greater width of the LPFL at the insertion point corresponds to greater LPFL and anterior-posterior lateral condylar lengths.

Drilling of the marginal tubercle to enhance exposure via mini pterional approach: An anatomical study and clinical series of 25 sphenoid wing meningiomas

Background:

The marginal tubercle (MT) of zygomatic bone can be an obstacle in the standard mini pterional (MPT) craniotomy; we aim to evaluate the effect of drilling this MT in enhancing the exposure of MPT craniotomy for resection of sphenoid wing meningiomas (SWMs).

Methods:

The authors utilized 60 dry skulls to perform the anatomical part of the study. The MT size was reflected by the AB distance, wherein point A is the most prominent part of MT and point B is located on the orbital rim in the same axial plane as point A. The authors analyzed the effect of MT size in masking the sphenozygomatic suture (SZS), which is the most anterior part of the MPT craniotomy. One silicon-injected embalmed specimen was used to demonstrate other modifications to the standard MPT approach. The results of the anatomical analysis were translated into the second part of the study, which consisted of the resection of 25 SWMs.

Results:

The MT obscured visualization when the AB distance measured 13 mm or greater. In the clinical series of SWMs, drilling such prominent MT maximized exposure during MPT approach.

Conclusion:

The MPT approach could be used for the resection of SWMs. Drilling of prominent MTs can enhance and optimize exposure to SWMs through standard MPT approaches.

The Medial Extra-Sellar Corridor to the Cavernous Sinus: Anatomic Description and Clinical Correlation

OBJECTIVE

The zenith of surgical interest in the cavernous sinus peaked in the 1980s, as evidenced by reports of 10 surgical triangles that could access the contents of the lateral sellar compartment (LSC). However, these transcranial approaches later became marginalized, first by radiosurgery's popularity and lower morbidity, and then by clinical potential of endoscopic corridors noted in several qualitative studies. Our anatomic study, taking a contemporary look at the medial extra-sellar corridor, gives a detailed qualitative-quantitative analysis for its use with increasingly popular endoscopic endonasal approaches to the cavernous sinus.

METHODS

In 20 cadaveric specimens, we re-examined the anatomic landmarks of the medial corridor into the LSC with qualitative descriptions and measurements. An illustrative case highlights a recurrent symptomatic pituitary adenoma that invaded the cavernous sinus approached through the medial corridor.

RESULTS

The corridor's shape varied from tetrahedron to hexahedron. Comparing right and left sides, width averaged 3.6 ± 4.5 mm and 4.0 ± 4.4 mm, and height averaged 2.3 mm and 2.1 mm, respectively. About 35% of sides showed ample space for access into the cavernous sinus. Our case report of successful outcome lends support for the safety and efficacy of this endoscopic approach.

CONCLUSIONS

Our re-examination of this particular surgical access into the LSC refines the understanding of the medial extra-sellar corridor as a main endoscopic access route to this compartment. Achieving safe access to the contents of the LSC, this 11th triangle is clinically relevant and potentially superior for select lesions in this region.

Is arthroscopic remplissage a tenodesis or capsulomyodesis? An anatomic study

PURPOSE

Arthroscopic remplissage of a Hill-Sachs lesion is classically described as a capsulotenodesis of the infraspinatus within the posterolateral humeral head. The aim of this cadaveric study was to evaluate the anatomic relationship between the position of anchors and sutures placed for remplissage and the infraspinatus and teres minor. The hypothesis was that remplissage actually corresponds to a capsulomyodesis of the infraspinatus and teres minor muscles.

METHODS

A two-anchor arthroscopic remplissage was performed followed by open dissection of ten fresh-frozen human cadaveric shoulders. The exit point of sutures related to muscle-tendon unit as well as the distance between the anchors and the rotator cuff was measured.

RESULTS

The superior sutures were localized generally in the infraspinatus, near the musculotendinous junction. The inferior sutures passed through the teres minor muscle in seven of ten cases. The distance between the superior and inferior anchors and the posterolateral greater tuberosity was 14 ± 2 and 12 ± 3 mm, respectively.

CONCLUSIONS

Arthroscopic remplissage is a capsulomyodesis of infraspinatus and teres minor rather than a capsulotenodesis of the infraspinatus alone as previously believed. Muscular damage may explain posterosuperior pain observed in patients who underwent remplissage.

Minimally invasive posterior approach in the popliteal fossa for semitendinosus and gracilis tendon harvesting: an anatomic study

INTRODUCTION

Harvesting the semitendinosus (ST) and gracilis (GR) tendons at the anteromedial side of the knee may be hampered by a conjoint tendon insertion on the tibial metaphysis and an accessory bundle between the ST and the medial gastrocnemius. Locating and sparing the terminal branches of the saphenous nerve are difficult on an anteromedial approach. The principal objective of the present anatomic study was to assess the feasibility of ST and GR harvesting from a minimally invasive posterior approach in the popliteal fossa. The secondary objective was to analyze the risk of saphenous nerve branch lesion during harvesting.

METHOD

Ten cadaver knees, free of scarring, were used. The whole body was positioned supine. The tendons were located in the popliteal fossa with the knee in 30° flexion. A mini-incision was performed in the fossa. The ST and GR tendons were located, and retrograde followed by anterograde stripping was performed. Tendon lengths and diameters were measured. The knees were then dissected to check for saphenous nerve branch lesions (anterior, infrapatellar and posterior branches).

RESULTS

The GR and ST tendons were respectively located at 14.4 and 24 mm from the medial edge of the knee. In 90% of cases, there was an accessory ST bundle toward the medial gastrocnemius muscle, 26 mm below the posterior edge. Tendons could be harvested without deviation of the stripper. Knee dissection did not find any saphenous nerve branches, these being protected by the sartorius fascia.

DISCUSSION

Posterior ST and GR tendon harvesting in the popliteal fossa is reliable and reproducible. It allows easy sectioning of the accessory ST bundle, without deviation during retrograde stripping. Unlike anterior harvesting, which leads to a rate of saphenous branch lesion of 50-78%, posterior harvesting protects the nerve branches by keeping away from the sartorius.

LEVEL OF EVIDENCE

Level 4.

Endoscopic, endonasal variability in the anatomy of the internal carotid artery

BACKGROUND

Classic three-dimensional schemas of the internal carotid artery (ICA) for transcranial approaches do not necessarily apply to two-dimensional endoscopic views. Modifying an existing ICA segment classification, we define endoscopic orientation for the lacerum (C3) to clinoid (C5) segments through an endonasal approach.

METHODS

In 20 cadaveric heads, we classified endoscopic appearance based on shape and angulation of C3 to C5 segments. Distances were measured between both arteries, and between the ICA and pituitary gland.

RESULTS

We identified 4 common ICA patterns: types I through III matched side-to-side, whereas type IV was asymmetric. In 80% of specimens, the pituitary gland had direct contact with the ICA. In 20% of specimens, a space existed between the pituitary gland and the cavernous segment. Access to the posterior aspect of the cavernous sinus medial to the cavernous segment was possible without retraction of the artery or pituitary gland. Spaces between the lacerum and cavernous segments were trapezoid (80%) and hourglass (20%).

CONCLUSIONS

Distinguishing which ICA type courses between the lacerum and clinoid segments can help clarify the relationships between the artery and its surrounding structures during endoscopic approaches. Adapting the classic terminology of ICA segments provided consistency of endoscopic relevance, defined potential endoscopic corridors, and highlighted the critical step of arterial contact.

A computed tomography-based anatomic comparison of three different types of c7 posterior fixation techniques : pedicle, intralaminar, and lateral mass screws

OBJECTIVE

The intralaminar screw (ILS) fixation technique offers an alternative to pedicle screw (PS) and lateral mass screw (LMS) fixation in the C7 spine. Although cadaveric studies have described the anatomy of the pedicles, laminae, and lateral masses at C7, 3-dimensional computed tomography (CT) imaging is the modality of choice for pre-surgical planning. In this study, the goal was to determine the anatomical parameter and optimal screw trajectory for ILS placement at C7, and to compare this information to PS and LMS placement in the C7 spine as determined by CT evaluation.

METHODS

A total of 120 patients (60 men and 60 women) with an average age of 51.7±13.6 years were selected by retrospective review of a trauma registry database over a 2-year period. Patients were included in the study if they were older than 15 years of age, had standardized axial bone-window CT imaging at C7, and had no evidence of spinal trauma. For each lamina and pedicle, width (outer cortical and inner cancellous), maximal screw length, and optimal screw trajectory were measured, and the maximal screw length of the lateral mass were measured using m-view 5.4 software. Statistical analysis was performed using Student's t-test.

RESULTS

At C7, the maximal PS length was significantly greater than the ILS and LMS length (PS, 33.9±3.1 mm; ILS, 30.8±3.1 mm; LMS, 10.6±1.3; p<0.01). When the outer cortical and inner cancellous width was compared between the pedicle and lamina, the mean pedicle outer cortical width at C7 was wider than the lamina by an average of 0.6 mm (pedicle, 6.8±1.2 mm; lamina, 6.2±1.2 mm; p<0.01). At C7, 95.8% of the laminae measured accepted a 4.0-mm screw with a 1.0 mm of clearance, compared with 99.2% of pedicle. Of the laminae measured, 99.2% accepted a 3.5-mm screw with a 1.0 mm clearance, compared with 100% of the pedicle. When the outer cortical and inner cancellous height was compared between pedicle and lamina, the mean lamina outer cortical height at C7 was wider than the pedicle by an average of 9.9 mm (lamina, 18.6±2.0 mm; pedicle, 8.7±1.3 mm; p<0.01). The ideal screw trajectory at C7 was also measured (47.8±4.8° for ILS and 35.1±8.1° for PS).

CONCLUSION

Although pedicle screw fixation is the most ideal instrumentation method for C7 fixation with respect to length and cortical diameter, anatomical aspect of C7 lamina is affordable to place screw. Therefore, the C7 intralaminar screw could be an alternative fixation technique with few anatomic limitations in the cases when C7 pedicle screw fixation is not favorable. However, anatomical variations in the length and width must be considered when placing an intralaminar or pedicle screw at C7.

Spinal dural attachments to the vertebral column: An anatomic report and review of the literature

BACKGROUND

The spinal dura is anchored within the vertebral canal by connective tissue in the epidural space as well as the spinal roots. Inadvertent disruption of these dural attachments may lead to durotomy and cerebrospinal fluid (CSF) leaks. We observed well-developed connective tissue ligaments connecting the lumbar dura to the spinal column and examined these tissues microscopically.

METHODS

Intraoperative images were obtained during lumbar laminectomy procedures. They demonstrated connective tissue attachments, linking the lumbar dura to the spinal column in the dorsal midline and dorsolaterally. Tissue samples were obtained and examined microscopically. We then conducted a search of the literature to find references to dural attachments to the spinal column.

RESULTS

Histological examination of the samples showed minimal cellular fibrous tissue. To date no references to these attachments have been made in neurosurgical literature. Previous studies, including live, cadaveric, and radiographic examinations, have demonstrated a dorsomedian fold of dura attached to the junction of the ligamentum flavum, and dorsolateral ligaments that divide the dorsal epidural space into an anterior and posterior compartment.

CONCLUSIONS

Epidural fibrous connections or ligaments between the dura and the lumbar spinal column may be of clinical importance to the neurosurgeon. Care should be taken during lumbar procedures not to disrupt or tear these ligaments as this may cause dural tears and CSF leaks. Identifying these ligaments and cutting them sharply may prevent inadvertent durotomies.