[Research on Locating Device for the Entry Point of Intramedullary Nail Based on Inertial Navigation]

Objective

To introduce a locating device for the entry point of intramedullary nail based on the inertial navigation technology, which utilizes multi-dimensional angle information to assist in rapid and accurate positioning of the ideal direction of femoral anterograde intramedullary nails' entry point, and to verify its clinical value through clinical tests.

Methods

After matching the locating module with the developing board, which are the two components of the locating device, they were placed on the skin surface of the proximal femur of the affected side. Anteroposterior fluoroscopy was performed. The developing angle corresponding to the ideal direction of entry point was selected based on the X-ray image, and then the yaw angle of the locating module was reset to zero. After resetting, the locating module was combined with the surgical instrument to guide the insertion angle of the guide wire. The ideal direction of entry point was accurately located based on the angle guidance. By setting up an experimental group and a control group for clinical surgical operations, the number of guide wire insertion times, surgical time, fluoroscopy frequency, and intraoperative blood loss with or without the locating device was recorded.

Results

Compared to the control group, the experimental group showed significant improvement in the number of guide wire insertion times, surgical time, fluoroscopy frequency, and intraoperative blood loss, with a statistically significant difference (P<0.01).

Conclusion

The locating device can assist doctors in quickly locating the entry point of intramedullary nail, effectively reducing the fluoroscopy frequency and surgical time by improving the success rate of the guide wire insertion with one shot, improving surgical efficiency, and possessing certain clinical value.

Analysis of the location and trajectory of the Kirschner wires in the fixation of extension-type supracondylar fracture of the humerus by 3D computational simulation

BACKGROUND

Closed reduction and percutaneous pinning is still a preference for the treatment of supracondylar humerus fractures in children. However, no reports have shown the pin trajectory and the characteristics of the entry point so far. So we established a computational simulation model of the elbow to observe the trajectory of pinning for supracondylar humerus fractures.

METHODS

We reconstructed an adult elbow computationally and simulated pin placement through lateral and medial pinning. Pin trajectories were traced after placement and after the addition of the skin profile; the relative entry points of the pins were determined. We used the center of the dorsal olecranon inflection as an anatomic reference for the entry points of lateral pinning. Four quadrants were established based on the center of the dorsal olecranon inflection: upper medial quadrant, upper lateral quadrant, lower medial quadrant, and lower lateral quadrant (LLQ).

RESULTS

The maximum angle of pinning through the lateral column was 64° ± 3°. The minimum angles of pinning through the lateral column and middle column were 37° ± 3° and 20° ± 2°, respectively. The range of safe angle pinning through the medial column was between 18° ± 2° and 57° ± 3° to avoid penetration of the olecranon fossa and the cortex of the medial column. The entry points of lateral pinning were within the lateral half of the LLQ, and the lateral one-third of the LLQ contained all entry points of the pins through the lateral column and minor points of the pins through the middle column. The exit points of the medial pinning were within the lateral fringe of the metaphyseal-diaphyseal junction region; entering from the inferior two-thirds of the medial epicondyle could lead to the exit points in the proximal half of the metaphyseal-diaphyseal junction region laterally.

DISCUSSION

For lateral pinning, the entry points would be within the lateral half of the LLQ. For the pins through the lateral column, the entry points should be within the lateral one-third of the LLQ. For medial pinning, entering from the inferior two-thirds of the medial epicondyle would lead to a more proximal exit.

DIPHOS® nail for proximal humeral fractures: our experience with more than 190 procedures and surgical tips

AIM

evaluate the outcome of proximal  humeral nailing over 5 years follow-up, focusing  on possible complications. Secondary endpoint is the description and analysis of some technical notes to simplify surgical procedure.

MATERIALS AND METHODS

the cohort is composed by 194 fractures fixed with short nail. Neer Classification was used to assess the type of fracture; Deltoid Tuberosity Index (DTI) was applied to verify local bone quality. Follow-up with X-rays and orthopaedic evaluation was conducted on every operated subject.

RESULTS

mean follow up of the study was 25.4 months. We registered an average CMS score of 84.66 points for 2-parts fractures, 79.05 points for 3-part fractures and 68.62 points for 4-parts fractures. We obtained radiographical healing in 95.9% of patients (186/194) after 2.7 months on average. We recorded "very good" / "good" results in 90.3% of 2-parts fractures, 88.5% of 3-parts fractures and 46.2% of 4-part fractures. Overall complication rate was 10.3% (20/194 nails).  Second surgery was performed in 8.2% (16/194) of cases.

CONCLUSION

intramedullary nailing is an effective treatment for 2 and 3-part fractures with relatively low incidence of complications, small surgical accesses and short surgical time. Future researches are necessary to analyze the results related to nailing in 4-fragment fractures, still uncertain and influenced by multiple factors. The presence of the intramedullary nail reduces the lever arm of the screws making the osteosynthesis more reliable. Modern nails guarantee angular stability for proximal cancellous screws and allows 1 or 2 screws at calcar level to get a valid medial support.

Where have all the children gone? High HIV prevalence in infants attending nutrition and inpatient entry points

Introduction

Despite notable progress towards PMTCT, only 50% of HIV‐exposed infants in sub‐Saharan Africa were tested within the first 2 months of life and only 30% of HIV‐infected infants are on antiretroviral treatment. This study assessed HIV prevalence in infants and children receiving care at various service entry points in primary healthcare facilities in Uganda.

Methods

A total of 3600 infants up to 24 months of age were systematically enrolled and tested at four regional hospitals across Uganda. Six hundred infants were included and tested from six facility entry points: PMTCT, immunization, inpatient, nutrition, outpatient and community outreach services.

Findings

The traditional EID entry point, PMTCT, had a prevalence of 3.8%, representing 19.6% of the total HIV‐positive infants identified in the study. Fifty percent of the 117 identified HIV‐positive infants were found in the nutrition wards, which had a prevalence of 9.8% (p < 0.001 compared to PMTCT). Inpatient wards had a prevalence of 3.5% and yielded 17.9% of the HIV‐positive infants identified. Infants tested at immunization wards and through outreach services identified 0.8% and 1.7% of the HIV‐positive infants respectively, and had a prevalence of less than 0.3%.

Conclusions

Expanding routine early infant diagnosis screening beyond the traditional PMTCT setting to nutrition and inpatient entry points will increase the identification of HIV‐infected infants. Careful reflection for appropriate testing strategies, such as maternal re‐testing to identify new HIV infections and HIV‐exposed infants in need of follow‐up testing and care, at immunization and outreach services should be considered given the expectedly low prevalence rates. These findings may help HIV care programmes significantly expand testing to improve access to early infant diagnosis and paediatric treatment.

[Study on sustentaculum tali screw placement for constant fragment of calcaneal fracture]

Objective

To investigate the anatomical characters of the sustentaculum tali (ST), accurate entry point and direction for the placement of ST screw from posterior subtalar joint facet to the constant fragment (CF) in calcaneal fractures.

Methods

A total of 100 patients with calcaneal fractures performed ankle CT scans were enrolled between January 2016 and April 2016. According to the inclusion criteria, the clinical data of 33 patients were analyzed, including 18 males and 15 females, with a median age of 41.0 years (range, 18-60 years). There were 16 cases on left side and 17 cases on the right side. Three-dimensional (3D) calcaneal model was reconstructed by Mimics 17.0 software, and the ST anatomical references were measured, including the length of upper and lower edge, the length and height of the midline, the horizontal angle between the midline and foot plantar surface. The parameters of the optimal entry point position (P' point) and placement angle of the ST screw were determined. The length of ST screw was also measured. The differences between males and females or left and right sides were compared.

Results

The length of upper edge of the ST was (16.60±2.23) mm, lower edge (20.65±2.90) mm, midline (20.56±2.62) mm, and the height of midline was (9.61±1.36) mm. The horizontal angle between the midline and foot plantar surface was (23.43±3.36)°. The vertical distance from P' point to the lowest point of the tarsal sinus was (3.09±1.65) mm, while the horizontal distance was (14.29±2.75) mm. The distance from P' point to the apex of the lateral talus, subchondral bone of subtalar joint, calcaneocuboid joint was (11.41±3.22), (6.59±2.22), (34.58±3.75) mm, respectively. The horizontal angle between the ST screw and foot plantar surface was (-1.17±2.07)°. The anteversion angle of ST screw was (16.18±2.05)° and the length was (41.64 ± 3.09) mm. There were significant differences in the length of upper and lower edge, the length and height of the midline, the distance from P' point to the apex of the lateral talus, subchondral bone of subtalar joint, and calcaneocuboid joint, and the anteversion angle and length of the ST screw between males and females ( P<0.05). There was no significant difference in above all parameters between left and right sides ( P>0.05).

Conclusion

After appropriate reduction of the calcaneal fractures, the entry point of ST screw was recommended at about 14 mm posterior and about 3 mm upper related to the foot horizontal line through the lowest tarsal sinus point; and the direction of ST screw placement was about 17° anteversion for males and 15° anteversion for females.

Multi-modal imaging, model-based tracking, and mixed reality visualisation for orthopaedic surgery

Orthopaedic surgeons are still following the decades old workflow of using dozens of two-dimensional fluoroscopic images to drill through complex 3D structures, e.g. pelvis. This Letter presents a mixed reality support system, which incorporates multi-modal data fusion and model-based surgical tool tracking for creating a mixed reality environment supporting screw placement in orthopaedic surgery. A red–green–blue–depth camera is rigidly attached to a mobile C-arm and is calibrated to the cone-beam computed tomography (CBCT) imaging space via iterative closest point algorithm. This allows real-time automatic fusion of reconstructed surface and/or 3D point clouds and synthetic fluoroscopic images obtained through CBCT imaging. An adapted 3D model-based tracking algorithm with automatic tool segmentation allows for tracking of the surgical tools occluded by hand. This proposed interactive 3D mixed reality environment provides an intuitive understanding of the surgical site and supports surgeons in quickly localising the entry point and orienting the surgical tool during screw placement. The authors validate the augmentation by measuring target registration error and also evaluate the tracking accuracy in the presence of partial occlusion.

Computed tomography-based prediction of the straight antegrade humeral nail's entry point and exposure of "critical types": truth or fiction?

BACKGROUND

Straight antegrade intramedullary nailing of proximal humerus fractures has shown promising clinical results. However, up to 36% of all humeri seem to be "critical types" in terms of the potential violation of the supraspinatus (SSP) tendon footprint by the nail's insertion zone. The aims of this study were to evaluate if a computed tomography (CT) scan could reliably predict the nail's entry point on the humeral head and if it would be possible to preoperatively estimate the individual risk of iatrogenic violation of the SSP tendon footprint by evaluating the uninjured contralateral humerus.

METHODS

Twenty matched pairs of human cadaveric shoulders underwent CT scans, and the entry point for an antegrade nail as well as measurements regarding critical distances between the entry point and the rotator cuff were determined. Next, gross anatomic measurements of the same data were performed and compared. Furthermore, specimens were reviewed for critical types.

RESULTS

Overall, 42.5% of all specimens were found to be critical types. The CT measurements exhibited excellent intra-rater and inter-rater reliability (intraclass correlation coefficients >0.90). Similarly, excellent agreement between the CT scan and gross anatomic measurements in contralateral shoulders (intraclass correlation coefficients >0.88) was found.

CONCLUSION

Assessing the uninjured contralateral side, CT can reliably predict the entry point in antegrade humeral nailing and preoperatively identify critical types of humeral heads at risk of iatrogenic implantation damage to the SSP tendon footprint. This study may help surgeons in the decision-making processon which surgical technique should be used without putting the patient at risk for iatrogenic, implant-related damage to the rotator cuff.

Neurovascular distribution within the abdominal head of the pectoralis major muscle: Application to breast and flap surgery

The abdominal head of the pectoralis major (AHPM) is important in cosmetic and flap surgeries. Few studies have reported on its neurovascular entry points and distribution patterns. We aimed to determine the entry points and distribution patterns of the neurovascular structures within the AHPM. Thirty-two hemithoraxes were dissected, and the distribution patterns of the neurovascular structures were classified into several categories. The neurovascular entry points were measured at the horizontal line passing through the jugular notch (x-axis) and the midclavicular line (y-axis). The AHPM was innervated by the communication branches of the medial pectoral nerve (MPN) and the lateral pectoral nerve (LPN) in 78.1% of the specimens and of the MPN without the communication branches in 21.9%. All the LPNs had communication branches, which could be classified as independent in 46.9% of the samples, with the MPN in 21.9%, and with the LPN in 9.3%. The blood supply of the AHPM was composed of branches from the lateral thoracic artery (LTA) in 62.5% of the specimens, the thoracoacromial artery (TA) in 15.6%, and the LTA with the TA in 21.9%. The mean distance of the entry point was 6.3 cm ± 1.3 cm lateral to the y-axis, 8.1 cm ± 3.3 cm below the x-axis in the nerves, 6.5 cm ± 1.2 cm lateral to the y-axis, and 8.6 cm ± 3.0 cm below the x-axis in the arteries. This study defined the average neurovascular entry point and distribution pattern in detail using standard lines to enable the AHPM to be better understood.

Anatomical determination of a safe entry point for occipital condyle screw using three-dimensional landmarks

The occipital condyle (OC) is an important area in craniovertebral surgery, but neither its anatomical features nor the procedures concerning the OC have been detailed yet. The morphological analysis of the structures were made in totally 704 sides of the occipital bones of adult skulls by 3D-Doctor Demo version. The length and width of the OC were found to be 23.9 ± 3.4 (right), 24 ± 3.3 (left) and 11.9 ± 2.3 (right), 10.7 ± 2.3 mm (left), respectively. The mean anterior intercondylar distance and the posterior intercondylar distance were measured as 20.9 ± 3.6 and 43.1 ± 4 mm, respectively. The sagittal intercondylar angle was observed as 68.7 ± 10.6º. The sagittal condylar angle was observed to be 32.9 ± 7.6º and 38.2 ± 7.3º in the right and left, respectively. The head circumference was observed to be 65.6 ± 7.8 and 64.4 ± 7.2 mm in the right and left, respectively. The head area was measured as 231.9 ± 53.3 and 214.9 ± 45.1 mm² in the right and left, respectively. The most common type was oval-like (59.67%), whereas the most unusual one was two-portioned condyle (0.32%). In Pearson correlation analysis, it was significant that a statistically strong relation was noticed between the length and area, and the circumference and area. The findings suggest that the oval type was more successful to work with, while the triangular, circular and two-portioned types were highly risky for the fixation resonance as the surface got quite smaller. As a result, we suggest that by resecting nearly half of the OC, the border of the hypoglossal canal can be involved.

Determination of adequate entry angle of lumbar sympathetic ganglion block in korean

BACKGROUND

The target of lumbar sympathetic ganglion block is the anterolateral surface of the L2, 3 and 4 vertebral bodies, where the lumbar sympathetic ganglion usually lies. In most cases, a block-needle is inserted approximately 5-8 cm lateral to spinous process on the skin and directed to the anterolateral surface of vertebral body obliquely. The purpose of this study is to determine the safe entry angle and entry point in Korean by using the abdominal CT scan images.

METHODS

The abdominal CT images of eighty five patients were recruited to this study. The minimal angle aimed at the lumbar sympathetic ganglion that can pass through the lateral aspect of body and maximal angle that avoids puncturing the kidney, ureter or retroperitoneal space were measured. The distance from midline to skin entry point was also measured.

RESULTS

There was no significant difference in entry angle among L2, 3, and 4 level. The entry angle was similar in the right and left side, and in males and females. The entry angle of old age group was significantly smaller than that of young age group. The calculated safe entry angle was 30.5 +/- 0.4 degrees and entry point was 7.7 +/- 0.2 cm and 6.7 +/- 0.1 cm lateral from midline in males and females respectively.

CONCLUSIONS

These measurements can be used as a reference for lumbar sympathetic ganglion block and radiofrequency lesioning. Prior to performing the lumbar sympathetic ganglion block for cancer patients, the abdominal CT scan should be reviewed to prevent complications.