Fluoroscopic freehand and electromagnetic-guided targeting system for distal locking screws of humeral intramedullary nail

Implant Design and Its Applications in the Fixation of Osteoporotic Bones: Newer Technologies in Nails, Plates and External Fixators

Background

Osteoporosis, characterised by decreased bone mass and degradation of bone tissue, poses a major global health concern, particularly for the ageing population. The traditional fixation techniques often fail in osteoporotic bones due to their diminished density and strength. Technological advancements in orthopaedic implants, specifically nails, plates, and external fixators, have emerged to address these challenges.

Materials and Methods

Improvements in implant design focus on material properties, surface modifications, and geometric advancements. Titanium and its alloys are favoured for their biomechanical properties such as lower elastic modulus and high strength-to-weight ratio. The biodegradable materials like polylactic acid and magnesium alloys offer the advantage of gradual resorption as bone heals. Surface modifications, such as coatings with bioactive materials and drug-eluting surfaces, promote osseointegration and enhance fixation strength.

Results and Discussion

Intramedullary (IM) nails have evolved to enhance stability and minimise complications associated with osteoporotic fractures. Third and fourth-generation nails incorporate surface treatments for better integration and healing. The advances in screw design, locking mechanisms, and flexible axial stimulation have improved fixation and allowed micromotion, which promotes fracture healing. The use of external fixators, particularly for complex fractures in osteoporotic bones, offers less invasive treatment options with adaptable stiffness for improved healing.

Conclusion

Technological innovations in implant materials, design, and surgical techniques have significantly improved the management of osteoporotic fractures. Newer technologies, including 3D printing, virtual and augmented reality, and artificial intelligence, show promise in enhancing implant customization, surgical planning, and postoperative outcomes. However, further clinical validation and research are needed to expand their clinical applications.

Intramedullary nailing for humeral shaft fractures: Is distal locking necessary?

INTRODUCTION

Intramedullary (IM) nailing of humeral shaft fractures is a reliable means to achieve bone union while allowing early motion. The hypothesis was that distal locking is unnecessary due to good primary stability of the impacted nail in the distal, truncated cone portion of the medullary canal. The primary objective of this study was to confirm the success of the procedure without distal locking by identifying failure criteria. The secondary objectives were to compare the outcomes of IM nailing with and without distal locking.

MATERIAL AND METHODS

This was a retrospective, single-center, non-randomized study of 128 patients with a humeral shaft fracture between 2012 and 2020 treated surgically with a long IM nail. Proximal locking was done in every case, then the rotational stability of the nail was tested. Stable nails were not locked distally (group A), while unstable nails were locked distally through an anterior approach (group B). All patients were reviewed with at least 12 months' follow-up.

RESULTS

Distal locking was performed in 30 patients (mean age 63, 17-91) while the fracture in 98 patients (mean age 65, 20-93) did not require distal locking. The average time to union was 4 months (2-6). The average operative time in group B was 87min (35-185) with 90s fluoroscopy time (33-158) versus 52min (20-127) with 44 s fluoroscopy time (12-143) in group A (p<0.05). Four patients in group B suffered postoperative radial nerve palsy and two others had another fracture at the level of the distal locking screws. The union rate did not differ between groups (Group A 94.6%, group B 86.2%, p=0.217) nor did the functional recovery - SSV of 79.5 (10-100) in group A versus 76 (40-100) in group B (p=0.271) - or the range of motion (p>0.05). There were no instances of rotational malunion.

DISCUSSION

Except for certain distal third fractures, distal locking is not necessary to achieve bone union when the nail is impacted into the medullary canal. This reduces the operative time, fluoroscopy time and risk of neurological damage.

LEVEL OF EVIDENCE

IV.

A New Accurate, Simple and Less Radiation Exposure Device for Distal Locking of Femoral Intramedullary Nails

Background

Due to the metal elasticity of intramedullary nails (IMs) and irregularities of the long bone marrow cavity and other reasons, one of the greatest challenges for surgeons is to position the distal locking screw. Therefore, a novel laser guiding navigation device was designed for the distal locking of femoral IMs. The purpose of this study was to compare the effectiveness of the novel device and freehand technique for distal locking of IMs in the femoral model.

Methods

The laser guiding navigation device (laser group) and freehand technique (freehand group) were used in the distal locking of the IMs in the femoral model. All operations were performed by surgeons of the same level. The differences between the two groups were compared in terms of operative time, radiation exposure time, first success rate, deviation angle between ideal trajectory and actual trajectory, and learning curve.

Results

The distal locking of the IMs in the femoral model was performed 40 times in each group. The results showed that the laser group was better than the freehand group in terms of operative time (345±165 VS 212±105 seconds, t=4.27, P<0.001), radiation exposure time (164±57 VS 41±15 seconds, t=13.15, P<0.001) and first successrate (χ ²=21.36, P<0.001). Compared with the freehand group, the actual trajectory of the laser group was closer to the ideal trajectory in coronal and horizontal planes. Furthermore, the learning curve time of the laser group was shorter.

Conclusion

Compared with traditional freehand technique, the novel laser guiding navigation device can shorten the operative time and reduce radiation exposure invitro. In addition, it is easy to master with more accuracy and a higher first success rate in vitro.

Augmented reality based navigation for distal interlocking of intramedullary nails utilizing Microsoft HoloLens 2

BACKGROUND AND OBJECTIVE

The distal interlocking of intramedullary nail remains a technically demanding procedure. Existing augmented reality based solutions still suffer from hand-eye coordination problem, prolonged operation time, and inadequate resolution. In this study, an augmented reality based navigation system for distal interlocking of intramedullary nail is developed using Microsoft HoloLens 2, the state-of-the-art optical see-through head-mounted display.

METHODS

A customized registration cube is designed to assist surgeons with better depth perception when performing registration procedures. During drilling, surgeons can obtain accurate and in-situ visualization of intramedullary nail and drilling path, and dynamic navigation is enabled. An intraoperative warning system is proposed to provide intuitive feedback of real-time deviations and electromagnetic disturbances.

RESULTS

The preclinical phantom experiment showed that the reprojection errors along the X, Y, and Z axes were 1.55 ± 0.27 mm, 1.71 ± 0.40 mm, and 2.84 ± 0.78 mm, respectively. The end-to-end evaluation method indicated the distance error was 1.61 ± 0.44 mm, and the 3D angle error was 1.46 ± 0.46°. A cadaver experiment was also conducted to evaluate the feasibility of the system.

CONCLUSION

Our system has potential advantages over the 2D-screen based navigation system and the pointing device based navigation system in terms of accuracy and time consumption, and has tremendous application prospects.

Evaluation of the accuracy of the Sureshot® electromagnetic targeting system in distal locking of long-nailed humeral diaphyseal fractures

INTRODUCTION

Osteosynthesis of humeral diaphyseal fractures by long intramedullary nailing is a widespread practice. Distal interlocking is a delicate and uncertain step in the procedure, and the free-hand method is adopted by most surgeons. We evaluated the accuracy of a magnetic field-guided system for distal interlocking of long intramedullary nailed humeral diaphyseal fractures.

HYPOTHESIS

The field magnetic method to interlock distal screws procured satisfying success rates at first attempt in each hole.

STUDY DESIGN

Single center, retrospective, descriptive and continuous.

MATERIAL AND METHODS

We used the Sureshot® Distal Targeting System (DTS) and the Trigen® (Smith & Nephew) nail. All patients who presented to our center for osteosynthesis of a fracture of the humeral diaphysis by long intramedullary nailing between April 1, 2016 and June 30, 2018 were retrospectively included.

RESULTS

The analyses included 32 of the 34 patients who presented during this period (mean age, 64 years). There were 51 attempts to install distal interlocking screws. The screws were interlocked successfully in 40 cases (78.4%), and there were 11 failures (21.6%). There was an average of 29 fluoroscopic views and an average cumulative dose area product of 36.90 cGcm².

DISCUSSION

We found a lower success rate than that found in the literature for the accuracy of Sureshot® DTS in long humeral nailing. We found also a lower success rate than for tibial and femoral centromedullary nailing with this system. Our study showed a success rate of only 78.4% at the first attempt for distal interlocking of Trigen® humeral long nails.

LEVEL OF EVIDENCE

IV; retrospective study without control group.

Free-hand distal locking of intramedullary nails: How to quickly achieve perfect circles without specific instrumentation

INTRODUCTION

Intramedullary locked nails are mainly used for the fixation of mid-shaft fractures in the long bones. But inserting the distal locking screws by the free-hand technique may require high exposure to radiation. Our method achieves perfect circles on radiographs on the first attempt for lower limb fractures without any specific instrumentation.

SURGICAL TECHNIQUE

We applied a geometric principle in which two lines perpendicular to another line are parallel to each other. Proximal locking, whether it is done or not, serves as a guide for the first perpendicular line to the nail. The fluoroscopy unit is aligned along the drill sleeve or the screwdriver left in place to achieve perfect circles on the first attempt.

DISCUSSION

This technique is simple, reliable, and reproducible. It does not require any specific instrumentation, allows the surgeon to choose any manufacturer's nail and reduces the operating room staff's exposure to radiation.

Can the complications of distal locking be prevented with a new nail that offers a novel locking technique in the treatment of humeral shaft fractures?

OBJECTIVES

This study aims to investigate whether complications related to distal locking can be prevented with InSafeLOCK® nail in the treatment of humeral shaft fractures.

PATIENTS AND METHODS

Hospital records of 31 patients (15 males, 16 females; mean age 54.4±10.1 years; range, 20 to 86 years) treated with InSafeLOCK® nail for humeral shaft fractures were investigated retrospectively between February 2016 and January 2019. Arbeitsgemeinschaft für Osteosynthesefragen (AO) classification was used to determine the type of fracture. During the implementation, the elapsed time for distal locking was investigated. Complications encountered during both implementation and postoperative follow-up were investigated.

RESULTS

Fourteen of the fractures were type A, 12 were type B, and five were type C. The mean follow-up time was 18.2 (range, 6 to 30.5) months. The mean duration for distal locking was 2.1 (range, 1.2 to 3.1) minutes. In one (3.2%) patient, cortical penetration occurred at the anterior cortex of the humerus at distal to the nail. In one patient, nail breakage occurred at the distal part of the nail. In one patient, rotational instability occurred due to screw loosening.

CONCLUSION

InSafeLOCK® humeral nail is safe when applied with the recommended technique. It can easily be applied without damaging the veins, nerves or other soft tissues around the elbow due to the internal distal locking feature; furthermore, there is no need to use fluoroscopy or targeting guide. Thus, it is possible to avoid complications that may occur during and after distal locking in conventional intramedullary nail implementations.

A comparison of free-hand method and electromagnetic navigation technique for the distal locking during intramedullary nailing procedures: a meta-analysis

BACKGROUND

Some studies have reported that the electromagnetic navigation (EN) technique is better than the free-hand (FH) method. Nevertheless, there are few clinical trials. In recent years, several clinical trials have been conducted, providing sufficient information to compare the two methods.

METHODS

We compared the FH and EN techniques (SURESHOT, Smith and Nephew, Inc., Memphis, TN) in terms of the distal locking time, exposure time, first success rate, healing time and operative time. We comprehensively searched the Medline, Embase, and Cochrane library databases according to predetermined inclusion and exclusion criteria, and then we extracted data for specific variables from these reports. The risk of bias was assessed. Stata 13.0 was used for analysis.

RESULTS

Nine studies involving 579 patients were pooled in this study. The meta-analysis showed that EN was associated with a shorter distal locking time (P = 0.001) and exposure time (P = 0.001) than FH performed by surgeons who are not proficient in using the FH technique. No significant differences were found in the first success rate (P = 0.231), healing time (P = 0.09) or operative time (P = 0.510).

CONCLUSION

The EN technique has the advantages of a shorter distal locking time and smaller amount of ionizing radiation exposure compared with the FH technique.

Reduced Surgical Time and Higher Accuracy of Distal Locking with the Electromagnetic Targeting System in Humeral Shaft Intramedullary Nailing

Objective

To evaluate the efficacy of the electromagnetic distal targeting system in the treatment of humeral shaft fractures.

Methods

From January 2012 to December 2018, we retrospectively reviewed 60 patients with humeral shaft fractures treated by intramedullary nailing. Among 60 cases, 41 were men and 19 were women. The average age at surgery was 48.5 years (range, 21–81 years). We performed the same surgical procedure for all patients. According to the different distal locking technique used, all patients were divided into two groups. The standard fluoroscopic freehand technique was used for Group FH, while the electromagnetic real‐time targeting technique was used for Group EM. All procedures were performed by two senior surgeons. Overall surgical time, cases of complications, failure of distal locking, union time, and shoulder function assessment were recorded intraoperatively and during follow‐up.

Results

Twenty‐seven patients in Group FH and 33 patients in Group EM met the inclusion criteria. No significant difference was found in the demographic data of the two groups. The mean surgical time was 76.48 ± 10.73 min in Group FH and 65.61 ± 8.91 min in Group EM (P < 0.05), showing significant difference. Seven failures occurred in Group FH and two failures occurred in Group EM (P < 0.05). No relevant complications were noted. The average union time was 3.37 ± 0.49 months in Group FH and 3.39 ± 0.50 months in Group EM (P = 0.855). The mean follow‐up was 14.30 ± 2.28 months in Group FH and 15.27 ± 2.83 months in Group EM (P = 0.153). The disabilities of the arm, shoulder and hand score (DASH) score, the range of motion (checked with the constant score), and the degree of functionality were, respectively, 21.52 ± 3.23, 27.04 ± 1.84, and 81.31% ± 3.88% in Group FH and 19.09 ± 2.40, 26.18 ± 1.70, and 77.97% ± 3.91% in Group EM (P = 0.233, 0.971, and 0.607).

Conclusion

The electromagnetic real‐time targeting system reduced surgical time and improved accuracy, and there was no radiation exposure in the distal locking procedure for humeral shaft fractures.

InSafeLock humeral nail provides a safe application for proximal and distal locking screws with distal endopin - An anatomical study

INTRODUCTION

Efforts to prevent iatrogenic neurovascular injuries with humeral intramedullary nailing lead to design new implants and inside to out distal locking technique using an endopin aims to provide a safer screw application. InSafeLock (TST, Istanbul, Turkey) humeral nail have been recently developed to minimize the possible screw related complications. The anatomical relationship between locking screws and neurovascular structures with the application time were compared between Trigen Humeral Nail (Smith and Nephew, Memphis, USA) and InSafeLock Humeral Nail.

HYPOTHESIS

InSafeLock humeral nail would be safer than Trigen Humeral nail in terms of neurovascular injury.

MATERIALS AND METHODS

Seven cadavers were used with both shoulders and surgical application of two nails was performed as the manufacturer guide. An Insafelock humeral nail was used for each right humerus and a Trigen humeral nail was used for each left humerus. Once the nails were placed, proximal and distal region of the nails were dissected to evaluate the relationship between screws and adjacent anatomical structures. The duration of the each screw was assessed via a stopwatch.

RESULTS

No significant finding was noted for the relationship between the neurovascular structures and proximal screws in two groups (p<0.05). The distal locking of the InSafeLock humerus nail had a shorter application time and no neurovascular damage was recorded.

DISCUSSION

The newly developed Insafelock humerus nails are at least as safe and effective as current humeral nails available on the market. Additional benefits include the preservation of neurovascular structures, as the Insafelock humerus nail does not require the use of an extra incision. Furthermore, surgical time is significantly shorter with using distal endopin.

LEVEL OF STUDY

III, controlled laboratory study.

Electromagnetic distal targeting system does not reduce the overall operative time of the intramedullary nailing for humeral shaft fractures

Introduction

We aimed to evaluate the efficacy of the use of the electromagnetic distal targeting system in treating humeral shaft fracture.

Methods

Patients were divided in: Group 1) patients that received a distal locking screw placement following the free-hand technique; Group 2) patients in which the distal locking screw was performed using the SURESHOT device.

Results

No differences were noted comparing Group 1 (freehand) [71,9 range 40-135 min] to Group 2 (SURESHOT)[70, range 25-125 min].

Conclusion

The use of the EM distal targeting system doesn't reduce the overall operative time of the humeral shaft fracture fixation using IMN.