Arthroscopic surgical tools: a source of metal particles and possible joint damage

The use of slice encoding for metal artifact correction (SEMAC) sequencing improves the diagnostic evaluation of graft integrity following anterior cruciate ligament reconstruction

OBJECTIVES

To determine whether magnetic resonance imaging (MRI) with metal artifact reduction sequencing is superior to conventional knee MRI in the evaluation of an injured anterior cruciate ligament (ACL) graft, where visualisation on conventional MRI can be limited by the metal artifact from fixation devices.

METHODS

Eighteen patients underwent conventional MRI sequence (proton density fat saturated [PDFS]) and two types of metal artifact reduction sequencing MRI (WARP, slice encoding for metal artifact correction (SEMAC); Siemens) following a secondary injury to their ACL reconstructed knee. Six raters with experience in knee MRI evaluation reviewed sagittal PDFS, WARP, and SEMAC sequences, providing semi-quantitative grades for visualisation and diagnostic confidence assessing the ACL, posterior cruciate ligament , menisci, tibial and femoral tunnel margins, and articular cartilage. Intra-class correlation coefficients for inter-rater reliability were evaluated. The 6-rater mean scores for the visualisation and diagnostic confidence derived from each sequence were compared using the Friedman test for multiple paired samples.

RESULTS

No statistically significant difference in the ACL visualisation among the sequences was found (p ​= ​0.193). Further, a subgroup analysis was performed in cases evaluated as "moderately blurry" or "indistinct ACL visualisation" on PDFS (58% of cases). SEMAC significantly improved diagnostic confidence in ACL visualisation (p ​= ​0.041) and ACL graft rupture (p ​= ​0.044) compared to PDFS. There was no statistically significant difference in the inter-observer reliability between sequences. The WARP sequence added 2.84 ​± ​0.69 ​min, while SEMAC added 2.95 ​± ​0.40 ​min to the standard knee MRI scan time.

CONCLUSION

use of the SEMAC metal reduction sequence significantly improved diagnostic accuracy and confidence in the detection of ACL graft rupture in cases where the ACL was moderately blurry or indistinct on the PDFS sequence. This sequence should be considered as an adjunct to conventional PDFS in cases where graft visualisation is limited by the metal artifact from fixation devices.

LEVEL OF EVIDENCE

III.

Surgically adjust tibial tunnel in anatomical anterior cruciate ligament single-bundle reconstruction: A time-zero biomechanical study in vitro

BACKGROUND

The anatomical positioning of the graft during anterior cruciate ligament reconstruction (ACLR) is of great significance for restoring normal knee kinematics and preventing early joint degeneration. Therefore, the adjustment of the mispositioned guide pin becomes extremely important. Our research aims to test the time-zero biomechanical properties in adjusting inaccurate guide pins to the center of the tibial footprint in anatomical anterior cruciate ligament single-bundle reconstruction.

METHODS

Porcine tibias and bovine extensor tendons were used to simulate a transtibial ACL reconstruction in vitro. Load-to failure testing was carried out in 4 groups: control group (n = 45): the guide pin was drilled at the center of the ACL footprint; group I, group II and group III (n = 45, respectively): the guide pin was respectively drilled 1 mm, 2 mm and 3 mm away from the center of the ACL footprint. In the experimental groups, a small tunnel with a 4.5 mm reamer is made and the guide pin is shifted to the center of the footprint. All the reamed tibias were scanned by CT to measure the area of the tunnel in the footprint, and time-zero biomechanical properties were recorded.

RESULTS

All graft-tibia complexes failed because the grafts slipped past the interference screws. Compare to control group, the ultimate load, yield load, and tunnel exit area in group III decreased significantly (p < 0.05). Regarding to the ultimate load, yield load, tensile stiffness, twisting force and tunnel exit area, t-test showed no significant differences between control group and group I, group II respectively (p > 0.05). Pearson test showed that tunnel exit area was negatively correlated with other characteristics (p < 0.05).

CONCLUSIONS

Surgical adjustment of the guide pin to the center of the tibial footprint may have significant influence in time-zero biomechanical properties in anatomical anterior cruciate ligament single-bundle reconstruction when the adjusted tibial tunnel was significantly enlarged compare to the standard tibial tunnel.

Optimal Fluoroscopic Angulation to Determine Intercondylar Notch Violation during Pediatric Medial Patellofemoral Ligament Reconstruction

Previous anatomic data has suggested that during pediatric medial patellofemoral ligament (MPFL) reconstruction, the femoral tunnel must be angled distally and anteriorly to avoid damage to the distal femoral physis and then intercondylar notch. The purpose of this study was to determine the optimal degree of fluoroscopic angulation necessary to radiographically determine the presence of intercondylar notch violation. Fourteen adult cadaveric human femora were disarticulated and under fluoroscopic guidance, Schöttle's point was identified. A 0.62-mm Kirschner wire was then drilled through the condyle to create minimal notch violation. The femur was then placed on a level radiolucent table and coronal plane radiographs angled from -15 to 60 degrees were obtained in 5-degree increments to determine the fluoroscopic angle at which intercondylar notch violation was most evident. Grading of optimal fluoroscopic angle between two authors found that violation of the notch was the best appreciated at a mean angle of 43 ± 15 degrees from neutral. Results from this study emphasize the importance of angling the beam to essentially obtain a notch view to assess for a breech.

Understanding the structure and cutting mechanism of shaver blades: A case study on articular cartilage

Mechanical shaver blades have been used in minimally invasive knee arthroscopy surgery for nearly 50 years, however, the tooth structure and cutting mechanism of shaver blades were less reported. This paper designed several shaver blades (triangular tooth/TT, circular tooth/CT and convex arc tooth/CAT), defined the cutting edges and angles of the original shaver (OS) and proposed a newly designed shaver (NDS) with a positive secondary rake angle to optimize cutting performance. The cutting process and theoretical model of the OS and NDS were analysed from 2D and 3D perspectives. A comparative experimental analysis of cutting performance, including cutting force, surface roughness, and groove geometries, was carried out to verify the influence of tooth structures and secondary rake angle. The results showed that the tooth of the OS has three different cutting edges, among which the secondary cutting edge sited at the tube section contributes to the puncturing process, and the primary cutting edge located on the outer wall of the tube participates in the oblique cutting process and finally removes the soft tissue. The cutting process of the secondary cutting edge of NDS has been changed from puncturing to oblique cutting, therefore, only the oblique cutting exists throughout the shaving process. This makes the shape and quantity of the chips of OS and NDS different, which has been verified by experiment. The cutting performance of CT was superior to that of TT and CAT, highlighting the importance of tooth roots in the cutting process. Positive secondary rake angle significantly improved the cutting performance of CAT, but not that of TT with a small profile angle (30°) and CT, which means both the puncturing and oblique cutting play important roles. Not all the positive secondary rake angle was helpful to the cutting process and 30° and 45° were suggested.

SEM-EDX Analysis of Metal Particles Deposition from Surgical Burs after Implant Guided Surgery Procedures

The preparation of the implant site in guided surgery procedure takes place without irrigation, which could lead to increased friction of the drills with the formation and release of debris or metal particles. The presence of metal particles in the peri-implant tissue could represent a trigger for macrophage activity, bone resorption processes, and consequent implant loss. According to the guided surgical protocol, the study aimed to evaluate the presence of metal particles deposited during implant site preparation. Twenty-five adult porcine ribs from the same adult individual were chosen due to their trabecular bone structure, similar to facial bones. The samples were all 8 cm (length) × 3 cm (depth) × 2 cm (width) and were further subdivided to obtain 50 elements of 4 cm × 3 cm × 2 cm. Plexiglass was used to create structures such as surgical guides so that their function could be mimicked, and the guided implant site preparation sequence could be performed with them. The drill kit used in this study is a guided surgery drill kit characterized by high wear resistance, high yield strength, and good corrosion resistance. This same kit was used 50 times in this way to prepare 50 different implant sites and evaluated at different edges and number of preparation (T0-neutral edge, T1-1 full preparation, T2-10, T3-20, T4-30, T5-40, and T6-50) by SEM-EDX to assess the presence of any metal deposition. The presence of metal residues in the implant site increased according to the cycles of use of the drills. We have observed that in the first three groups, there is no presence of metals. This is evident in groups T3 and T4. Finally, the presence of metal residues becomes significant in the study’s last two groups of samples. The study highlighted how the lack of irrigation in the work site leads the deposition of metal particles and in addition to a reduction in the efficiency of the drills, resulting in less precise cutting, altering the shape of the prepared site, and, lastly, reducing the primary stability of the implants.

Comparison of tendon-bone healing between a newly developed ultrasound device and the conventional metallic drill in a rabbit MCL reconstruction model

BACKGROUND

Ligament reconstructive surgeries demand tunnel creation using an over-drilling technique, though this technique has some problems such as metallic particle liberation or difficulties in tunnel creation other than circular cross-section. Recently, a new ultrasound (US) device for bone excavation to overcome these problems was developed. This study aimed to compare the tendon-bone healing in tunnels created using the new US device to that created using the conventional drill in a rabbit model.

METHODS

A total of 72 rabbits underwent a reconstruction for the anterior half of the medial collateral ligament (MCL) using a half of the patellar tendon. For the femoral tunnel creation, a new US device was used in 36 rabbits (US group), while a conventional metallic drill was used for the remaining 36 rabbits (DR group). At 4, 8, and 12 weeks postoperatively, biomechanical (n = 10) and histological (n = 2) evaluations were performed.

RESULTS

The ultimate failure load was almost equivalent between the US and DR groups at each period (US/DR; 4 weeks, 50.0 ± 12.8 N/43.4 ± 18.9 N, p = 0.62; 8 weeks, 78.6 ± 11.5 N/77.3 ± 29.9 N, p = 0.92; and 12 weeks: 98.9 ± 33.5 N/102.2 ± 38.3 N, p = 0.80). Pull-out failure from the femoral tunnel was only observed in two rabbits in the US group and one rabbit in the DR group at 4 weeks postoperatively. At 8 and 12 weeks, all specimens had a mid-substance tear. The collagen fiber continuity between tendon and bone occurred 8 weeks postoperatively in both groups and no histological difference was recognized throughout the evaluation period.

CONCLUSIONS

The tunnels created using the new US device and the conventional drill had equivalent biomechanical and histological features in tendon-bone healing. The bone excavation technology by the new US device may be applicable in ligament reconstructive surgeries.

Enhancing Staphylococcus aureus sterilization of stainless steel by the synergistic effect of surface structure and physical washing

Staphylococcus aureus infection is common in the clinical environment. It has been shown that the presence of micro/nano structures on material surfaces promote bacterial adhesion resistance. Herein, we assessed the S. aureus adhesion properties on laser micro/nano structured stainless-steel (316 L) surfaces after mechanical rotation and ultrasonic washing. The interaction force between S. aureus and structured surfaces was evaluated. A high concentration S. aureus solution was used to evaluate the bacterial sterilization efficiency after film formation on the stainless-steel surface. After 24 h of incubation, S. aureus films were formed on material surfaces. The comparison of static washing, surface mechanical rotation, and ultrasonic washing showed a decrease of S. aureus adhesion on the polished and laser induced periodic surface structures. However, S. aureus adhesion on the micro/nanoparticle surface after mechanical rotation washing did not display any obvious change compared to the polished one. Additionally, specimens after ultrasonic cleaning showed clear antibacterial adhesion than mechanical rotation. After the ultrasonic sterilization process, the laser induced periodic laser surface sample showed optimal bacterial adhesion inhibition. Finally, in vitro tests showed that the biocompatibility of the laser-induced structured surface did not change significantly from the polished surface one.

Assessment of arthroscopic shavers: a comparison test of resection performance and quality

Background

Arthroscopic shavers play an indispensable role in arthroscopic debridement. They have exquisite structures and similar designs. The purpose of this study was to establish a reproducible testing protocol to compare the resection performance and the quality (tensile strength, torsional strength, and corrosion resistance) of different arthroscopic shavers with comparable designs. We hypothesized that there could be little difference in resection performance and quality between these shavers.

Methods

Incisor Plus Blade (IPB; Smith & Nephew, Andover, MA) and Double Serrated Plus Blade (DSPB; BJKMC, Shanghai, China) were selected for resection performance and quality test. For resection performance testing, the resection torque, which is the minimum torque required to cut off silicone blocks with the same cross-sectional area, was measured to evaluate the resection performance of shaver blades when the other factors remain the same. For quality testing, tensile and torsion tests of the shavers’ joint part were performed, and ultimate failure load and maximum torque were measured and compared. The corrosion resistance of these blades was assessed by the boiling water test based on the ISO13402.

Results

No significant difference existed in the resection torque between the shaver blades of IPB and DSPB (P = 0.54). To the failure load of shavers’ joint parts, IPB was significantly higher than DSPB, both in the outer and inner blades (P < 0.0001). The maximum torque of the joint part had no significant difference between IPB and DSPB (for inner blades P = 0.60 and outer blades P = 0.94). The failure load (for both IPB and DSPB P < 0.0001) and maximum torque (for IPB P = 0.0475 and DSPB P = 0.015) of the inner blades were higher than those of the outer blades. No blemishes were observed on the surface of the blades after corrosion resistance tests.

Conclusions

This study provided some new methods to evaluate the resection performance and quality of different shavers. The resection performance, the torsional strength of the joint part, and the corrosion resistance of IPB and DSPB may show comparable properties, whereas the tensile strength of the shavers’ joint part showed some level of difference.

Radiographic evaluation of the glenohumeral joint space in patients undergoing arthroscopic shoulder surgery in the beach-chair position

Background

Shoulder arthroscopy can be performed with the patient in the lateral decubitus or beach-chair position, but in both cases, glenohumeral (GH) joint spaces must be increased to improve visualization and allow access of the optical instrument. The aim of this study was to determine the effects of limb setup and longitudinal traction on the opening of the GH space with patients placed in the beach-chair (dorsal decubitus) position.

Methods

GH spaces at 3 test points corresponding to the anatomic locations of Bankart lesions were determined indirectly from radiographic images obtained from 67 patients presenting shoulder pathology with an indication for arthroscopic surgery. Measurements were made with the operative limb in neutral rotation and positioned in relation to the coronal plane in adduction, 45° of abduction, or adduction with an axillary spacer, in each case with and without longitudinal traction.

Results

GH spaces were optimized at 2 of 3 test points when the operative limb was positioned in adduction or neutral rotation and manual longitudinal traction was applied with or without a polystyrene spacer placed under the axilla, but use of the spacer was essential to maximize the GH space at all 3 locations. In contrast, 45° of abduction proved to be the least appropriate position because it afforded the smallest GH space values with or without traction.

Conclusion

Appropriate positioning of the patient on the operating table is a critical aspect of shoulder arthroscopy. Radiographic images revealed that adducted upper-limb traction with the use of an axillary spacer in patients in the beach-chair position generates a significant increase in the GH space in the lower half of the glenoid cavity, thereby facilitating visualization and access of the optical equipment to the GH compartments.