Plunging when drilling: effect of using blunt drill bits

Avoiding Compartment Syndrome, Vascular Injury, and Neurologic Deficit in Tibial Osteotomy: An Observational Study of 108 Limbs

INTRODUCTION

Tibial deformities are common, but substantial concern may be associated with corrective osteotomy regarding major complications reported in classic literature. Such studies chiefly focused on high tibial osteotomy, with relatively little investigation of other areas and types of deformity. The primary aim of this study was to identify the rate of compartment syndrome, vascular injury, nerve injury, and other major complications after elective tibial osteotomy.

METHODS

One hundred eight tibia osteotomies performed during 2019 to 2021 were evaluated, representing all tibia osteotomies except situations of existing infection. A retrospective chart review was performed to identify patient demographics, surgical indications, anatomic location of osteotomy, fixation used, and complications prompting additional surgery.

RESULTS

The most common osteotomy locations were high tibial osteotomy (35/108 = 32%, 32/35 = 91% medial opening, and 3/35 = 9% medial closing), proximal metaphysis (30/108 = 28%), and diaphysis (32/108 = 30%). The most common fixation was plate and screw (38/108 = 35%) or dynamic frame (36/108 = 33%). Tranexamic acid was administered to 107/108 = 99% of patients and aspirin chemoprophylaxis was used for 83/108 = 86%. A total of 33/34= 97% of anterior compartment prophylactic fasciotomies were performed for diaphyseal or proximal metaphysis osteotomies. No events of compartment syndrome, vascular injury, nerve injury, or pulmonary embolism occurred. One patient required débridement to address infection. Additional surgery for delayed/nonunion occurred for nine segments (8%). Additional surgery for other reasons were performed for 10 segments (9%), none resulting in reduced limb function.

CONCLUSION

Tibial osteotomy can be safely performed for a variety of indications in a diverse range of patients, without a notable risk of the most feared complications of compartment syndrome, vascular injury, and neurologic deficit. Prophylactic fasciotomy and reducing postoperative bleeding using tranexamic acid, along with location-specific safe surgical techniques, may help prevent major complications and thereby facilitate optimized deformity care.

Usefulness of a drill stopper to prevent iatrogenic soft tissue injury in orthopedic surgery

Objective

This study introduces a novel technique utilizing a drill stopper to limit drill penetration depth and to prevent iatrogenic injuries, specifically neurovascular damage, in orthopedic surgeries. Orthopedic surgeries frequently involve the use of drills, which are essential tools for various procedures. However, improper handling of drills can lead to iatrogenic soft tissue injuries, causing severe consequences such as permanent disability or life-threatening complications. To address this issue, we propose the use of a drill stopper as a safeguard to prevent excessive drill penetration and reduce the risk of soft tissue damage during surgery.

Materials and Methods

The study involved 32 orthopedic surgeons, half of whom were experienced and the other half inexperienced. Synthetic femur bone models (Synbone) were used for drilling exercises, employing four configurations: a sharp drill bit without a stopper (SF, Sharp Free), a sharp drill bit with a stopper (SS, Sharp Stopper), a blunt drill bit without a stopper (BF, Blunt Free), and a blunt drill bit with a stopper (BS, Blunt Stopper). Each participant conducted three trials for each configuration, and the penetration depth was measured after each trial.

Results

For experienced surgeons, the average penetration depths were 3.83 (±1.826)mm for SF, 11.02 (±3.461)mm for BF, 2.88 (±0.334)mm for SS, and 2.75 (±0.601)mm for BS. In contrast, inexperienced surgeons had average depths of 8.52 (±4.608)mm for SF, 18.75 (±4.305)mm for BF, 2.96 (±0.683)mm for SS, and 2.83 (±0.724)mm for BS.

Conclusion

The use of a drill stopper was highly effective in controlling drill penetration depth and preventing iatrogenic injuries during orthopedic surgeries. We recommend its incorporation, particularly when using a blunt drill bit or when an inexperienced surgeon operates in an anatomically unfamiliar area. Using the drill stopper, the risk of severe injuries from excessive drill penetration can be minimized, leading to improved patient safety and better surgical outcomes.

Development of a Metaphyseal Non-Union Model in the Osteoporotic Rat Femur

The aim of this current study was to establish a metaphyseal femoral non-union model in osteoporotic rats by comparing a power tool versus a manual tool for fracture creation. Twelve adult female Sprague Dawley rats were ovariectomized (OVX) and received a special diet for 6 weeks. Biweekly pQCT measurements confirmed a significant reduction in the cancellous and total bone mineral density in OVX rats compared to control (CTRL) animals. After 6 weeks, OVX rats underwent surgery creating a distal metaphyseal osteotomy, either using a piezoelectric- (n = 6) or a manual Gigli wire (n = 6) saw. Fractures were stabilized with a Y-shaped mini-locking plate. Within each group, three rats received Alginate directly into the fracture gap. OVX animals gained more weight over 8 weeks compared to CTRL animals. pQCT analysis showed a significant difference in the volumetric cancellous bone mineral density between OVX and CTRL rats. A histological examination of the osteoporotic phenotype was completed. Radiographic evaluation and Masson–Goldner trichrome staining with the piezoelectric saw failed to demonstrate bony bridging or a callus formation. New bone formation and complete healing were seen after 6 weeks in the Gigli group. For the creation of a metaphyseal atrophic non-union in the osteoporotic bone, a piezoelectric saw should be used.

Drill Bone with Both Hands: Plunge Depth and Accuracy with 4 Bracing Positions

Bone drilling is a critical skill honed during orthopaedic surgical education. How a bone drill is held and operated (bracing position) may influence drilling performance.

Methods

A prospective study with randomized crossover was conducted to assess the effect of 4 bracing positions on orthopaedic surgical trainee performance in a simulated bone drilling task. Linear mixed effects models considering participant training level, preferred bracing position, height, weight, and drill hole number were used to estimate pairwise and overall comparisons of the effect of each bracing position on 2 primary outcomes of drilling depth and accuracy.

Results

A total of 42 trainees were screened and 19 were randomized and completed the study. Drill plunge depth with a 1-handed drilling position was significantly greater by pairwise comparison to any of the 3 double handed positions tested: a soft tissue protection sleeve in the other hand (0.41 mm, 95% confidence interval [CI] 0.80-0.03, p = 0.031), a 2-handed position with the contralateral small finger on bone and the thumb on the drill (0.42 mm, 95% CI 0.06-0.79, p = 0.018), and a 2-handed position with the contralateral elbow braced against the table (0.40 mm, 95% CI 0.02-0.78, p = 0.038). No position afforded a significant accuracy advantage (p = 0.227). Interactions of participant height with plunge depth and accuracy as well between drill hole number and plunge depth were observed.

Conclusion

Orthopaedic surgical educators should discourage trainees from operating a bone drill using only 1 hand to reduce the risk of iatrogenic injury due to drill plunging.

Level of Evidence

Therapeutic Level II.

The effects of multiple drilling of a bone with the same drill bit: thermal and force analysis

Repeated use of the same drill bit during drilling wears off the cutting edges, which can lead to a significant increase in heat as a result of friction, which is harmful to a bone above 55 °C. Few previous studies have examined the effects of using the same drill bit several times, on temperature. The objective of this study was to determine the effect of each drilling on temperature and force. 72 trials were performed. A total of 24 stainless steel drill bits of ∅3.2 mm were used to drill bovine bone samples. Each drill bit was used at least 3 times. T thermocouples were used to measure temperatures during each drilling test. Possible correlations of cutting parameters were studied. Tests were performed on a test rig measuring forces and temperatures during drilling. Effects of spindle speed (N), feed rate (V_f), and several trials (E) on temperature and forces were measured. Images of the drill bits were analyzed by digital microscopy before and after the drilling series for signs of wear. Temperatures increased significantly from E₁ to E₃. They decreased moderately with V_f. The best cutting conditions were at N = 200 rpm for V_f = 60 mm/min and N = 100 rpm for V_f = 30 mm/min drilling. At N > 200 rpm, they were very high. Temperature rise is significantly related to number of drilling (E), spindle speed (N), and inversely to feed rate (V_f). Analysis of images by digital microscopy confirmed drill bits wearing off, following the number of trials.

Factors Associated With the Accuracy of Depth Gauge Measurements

Background: It is important to select appropriate screws in orthopedic surgeries, as excessively long or too short a screw may results failure of the surgeries. This study explored factors that affect the accuracy of measurements in terms of the experience of the surgeons, passage of drilled holes and different depth gauges.

Methods: Holes were drilled into fresh porcine femurs with skin in three passages, straight drilling through the metaphysis, straight drilling through the diaphysis, and angled drilling through the diaphysis. Surgeons with different surgical experiences measured the holes with the same depth gauge and using a vernier caliper as gold standard. The length of selected screws, and the time each surgeon spent were recorded. The measurement accuracy was compared based on the experiences of the surgeons and the passage of drilled holes. Further, parameters of depth gauges and 12-mm cortical bone screws from five different manufacturers were measured.

Results: A total of 13 surgeons participated in 585 measurements in this study, and each surgeon completed 45 measurements. For the surgeons in the senior, intermediate, and junior groups, the average time spent in measurements was 689, 833, and 785 s with an accuracy of 57.0, 42.2, and 31.5%, respectively. The accuracy and measurement efficiency were significantly different among the groups of surgeons (P < 0.001). The accuracy of measurements was 45.1% for straight metaphyseal drilling, 43.6% for straight diaphyseal drilling, and 33.3% for angled diaphyseal drilling (P = 0.036). Parameters of depth gauges and screws varied among different manufacturers.

Conclusion: Both observer factor and objective factors could affect the accuracy of depth gauge measurement. Increased surgeon's experience was associated with improvements in the accuracy rate and measurement efficiency of drilled holes based on the depth gauge. The accuracy rate varied with hole passages, being the lowest for angled drilled holes.

Power-Tool Use in Orthopaedic Surgery: Iatrogenic Injury, Its Detection, and Technological Advances: A Systematic Review

Power tools are an integral part of orthopaedic surgery but have the capacity to cause iatrogenic injury. With this systematic review, we aimed to investigate the prevalence of iatrogenic injury due to the use of power tools in orthopaedic surgery and to discuss the current methods that can be used to reduce injury.

The tale of two vessels, vascular complications following a breach of the pelvic inner table due to acetabular screws: a report of two cases

Injuries to the pelvic vasculature during total hip arthroplasties are rare but have serious consequence. They demand urgent and early identification so that appropriate treatment can be instituted. If the bleeding is severe, cardiovascular compromise occurs intraoperatively and this will alert the surgeon of this possibility during acetabular screw placement. Alternatively, a delay in diagnosis can occur because the bleeding and the injured vessel are in the pelvic cavity and not visualized during the surgery. In this article, we report two cases from our center occurring within a six-month interval that sustained a vascular injury during acetabular drilling for screw placement for cementless cup fixation. Each case had a different vessel injury and different lessons can be learned from these rare injuries. The first case had an injury of the inferior gluteal artery following a breach of the sciatic notch. The vessel was treated with percutaneous embolization. The second case demonstrated a venous injury, following a medial protrusio technique for congenital hip dysplasia and a short anterosuperior screw, transecting the external iliac vein. This was subsequently repaired using an endovascular technique. We conclude the reasons for these vessel injuries after analyzing advanced imaging, discuss measures to avoid vessel injury and detail the minimally invasive method for their treatment.

Plunging Dangerously: A Quantitative Assessment of Drilling the Clavicle

Bicortical drilling of the clavicle is associated with risk of iatrogenic damage from plunging given the close proximity of neurovascular structures. This study determined plunge depth during superior-to-inferior clavicle drilling using a standard drill vs drill-sensing technology. Two orthopedic surgeons drilled 10 holes in a fresh cadaveric clavicle with drill-sensing technology in freehand mode (functions as standard orthopedic drill) and another 10 holes with drill-sensing technology in bicortical mode (drill motor stops when the second cortex is breached and depth is measured in real time). The drill-measured depths were compared with computed tomography-measured depths. Distances to the neurovascular structures were also measured. The surgeons' plunge depths were compared using an independent t test. With freehand (standard) drilling, the mean plunge depth was 8.8 mm. For surgeon 1, the range was 5.6 to 15.8 mm (mean, 10.9 mm). For surgeon 2, the range was 3.3 to 11.0 mm (mean, 6.4 mm). The surgeons' plunge depths were significantly different. In bicortical mode, the drill motor stopped when the second cortex was penetrated. Drill-measured depths were verified by computed tomography scan, with a mean difference of 0.8 mm. Mean distances from the clavicle to the neurovascular structures were 15.5 mm for the subclavian vein, 18.0 mm for the subclavian artery, and 8.0 mm for the brachial plexus. Plunge depths differed between surgeons. However, both surgeons' plunge depths were greater than distances to the neurovascular structures, indicating a risk of injury due to plunging. Although a nonspinning drill bit may still cause soft tissue damage, drill-sensing technology may decrease the risk of penetrating soft tissue structures due to plunging. [Orthopedics. 2021;44(1):e36-e42.].

Feed rate control in robotic bone drilling process

The bone drilling process is characterised by various parameters, the most important of which are the feed rate (mm/s) and the drill speed (rpm). They highly reflect the final effects and results of the drilling process, such as mechanical and thermal damages of bone tissue and hole quality. During manual drilling, these parameters are controlled by the surgeon based on his practical skills. But automatic drilling can assure an optimal result of the manipulation where such parameters are under control. During bicortical automatic bone drilling such a process consists of several stages: searching the contact with the first cortex, cortex drilling and automatic stop; searching the contact with the second cortex, cortex drilling and automatic stop; drill bit extraction. This work presents a way to control the feed rate during different stages of the bone drilling process (an original feed rate control algorithm) using the orthopaedic drilling robot (ODRO). The feed rate control is based on a proposed algorithm created and realised by specific software. During bicortical bone drilling process the feed rate takes various values in any stage in the range 0.5-6 mm/s. These values depend on drill bit position and real time force sensor data. The novelty of this work is the synthesis of an original feed rate control algorithm to solve the main problems of bone drilling in orthopaedic surgery - minimisation the drilling time (the heat generation); eliminating of the drill bit slip at the first (near) cortex and the drill bit bending at the second (far) cortex; minimising the risk of micro cracks which causes Traumatic Osteonecrosis; improving hole quality of the drilled holes; eliminating of the drill bit slip and the drill bit bending at the second cortex; minimising the value of the second cortex drill bit penetration by bicortical bone drilling.

Surgical Drill Bit Design and Thermomechanical Damage in Bone Drilling: A Review

As drilling generates substantial bone thermomechanical damage due to inappropriate cutting tool selection, researchers have proposed various approaches to mitigate this problem. Among these, improving the drill bit design is one of the most feasible and economical solutions. The theory and applications in drill design have been progressing, and research has been published in various fields. However, pieces of information on drill design are dispersed, and no comprehensive review paper focusing on this topic. Systemizing this information is crucial and, therefore, the impetus of this review. Here, we review not only the state-of-the-art in drill bit designs-advances in surgical drill bit design-but also the influences of each drill bit geometries on bone damage. Also, this work provides future directions for this topic and guidelines for designing an improved surgical drill bit. The information in this paper would be useful as a one-stop document for clinicians, engineers, and researchers who require information related to the tool design in bone drilling surgery.

Identification of the lateral femoral safe zone for drilling during LISS plate fixation of distal femur fractures

BACKGROUND

The incidence of arterial injury associated with femoral fractures is approximately 1%. Lateral sub-muscular plate fixation is gaining popularity for the management of distal femoral fractures. The objective of this study was to assess the iatrogenic risk to the superficial femoral artery (SFA) during Less Invasive Stabilisation System (LISS) plate fixation of distal femoral fractures by analysing the range of distances and angles between LISS plate screws and the drilling line to the SFA.

MATERIALS AND METHODS

We identified all patients who underwent LISS plate fixation of distal femoral fractures between 2008 and 2018 in our level-1 trauma centre. Patients who underwent postoperative computed tomography for any reason were eligible for inclusion in the study. Twenty-five patients met the inclusion criteria. The sample comprised 10 male and 15 female patients with a mean age of 55 years. The most common fracture type was a supracondylar femur fracture (56%), followed by an intercondylar fracture (36%). A 13-hole LISS plate was the most common plate length used (44%). A consultant radiologist reviewed all scans to verify the visibility and marking of the SFA.

RESULTS

The median distance between the screw tip and the SFA was 21 mm (range, 8-65 mm). There was a negative correlation between the LISS plate hole number and the trajectory of drilling (Pearson coefficient: -0.87, p < 0.001). Using a linear regression model, the SFA was more likely to be in the line of drilling when the 6th to 10th holes in the LISS plate were used.

CONCLUSION

Extra care is needed when drilling into the LISS plate holes from the lateral to the medial direction in order to reduce the risk of iatrogenic injury to the SFA, especially in the high-risk plate zone where the artery can be close to the drilling line.

Experimental investigation on the effect of drill quality on the performance of bone drilling

Bone drilling is a well-known process in operative fracture treatment and reconstructive surgery. The cutting ability of the drill is lost when used for multiple times. In this study, the effect of different levels of drill wear on bone temperature, drilling force, torque, delamination around the drilling region and surface roughness of the hole was investigated using a series of experiments. Experimental results demonstrated that the wear of the drill is strongly related to the drilling force, torque, temperature and surface roughness of the drilled hole. Statistical analysis was performed to find the effect of various factors on multiple response variables in the bone drilling process. The favorable conditions for bone drilling are obtained when feed rate, drill speed and the roughness of the cutting edge of the drill were fixed at 30 mm, 2000 rpm and up to 2 mm, respectively. Further, analysis of variance (ANOVA) was performed to determine the factor with a significant impact on the response variables. F-test and p-value indicated that the feed rate had the highest effect on grey relational grade followed by the roughness of the drill. This study suggests that the sharp drill along with controlled drilling speed and feed rate may be used for safe and efficient surgical drilling in bone.

Oblique proximal locking screw in tibial fracture intramedullary nailing: a clinical imaging study of proximity to common peroneal nerve

Intramedullary nailing (IMN) is the treatment of choice in the surgical management of most tibia shaft fractures. The aim of the study was to evaluate the proximity of the common peroneal nerve (CPN) to the oblique proximal locking screw inserted from the anteromedial to the posterolateral direction. We identified all the patients who underwent the IMN of the tibia between 2008 and 2018. Patients who underwent post-operative computed tomography for any reason were identified. Patients were included if the CPN was visible on the axial slices, the proximal oblique locking screw was used, or the line of the drilling could be reconstructed. Twenty-nine patients met the inclusion criteria. The median length of the intramedullary nail was 345 mm. The median nail diameter was 10 mm. The median number of proximal interlocking screws was 2. All scans were reviewed by the musculoskeletal radiologist for verifying the visibility and marking of the CPN. The mean screw trajectory angle to the CPN was 9° (± 9°). Most of the drilling trajectories passed posterior to the CPN (79%). The depth of the intramedullary nail was on average - 8 mm (± 10 mm). A negative correlation was observed between the depth of the nail and the distance from the CPN (P < 0.001). During the insertion of the oblique proximal locking screw from the anteromedial to the posterolateral direction, the CPN is potentially at risk if the drill is allowed to plunge or an incorrectly long screw is used. Sinking the nail provides a better margin of safety.

Drilling Technique Can Minimize Plunging

PURPOSE

Vibratory and acoustic feedback, drill sharpness, and material density have each been shown to influence the depth of plunging when drilling through bicortical bone. We hypothesized that drilling technique can also influence the depth of plunging.

METHODS

Six subjects of various training levels (PGY1 to 16-year experienced surgeon) were asked to drill through a cortical bone surrogate, third-generation Sawbones tube with similar density and compressive modulus of healthy cortical bone. Using a sharp 4.5-mm drill bit and System 6 drill, each participant drilled 30 holes wearing surgical gloves to mimic tactile feedback and using 3 different techniques (10 holes each). The techniques were single-handed smooth, single-handed bounce, and 2-handed smooth drilling. A 60 frame-per-second high-definition video recorder was placed a standard distance from the model and used to calculate the depth of plunging. Analysis of variance with Fisher PLSD post hoc was used to compare techniques (significance P < 0.05).

RESULTS

The average ± SD plunge depths were 13.0 ± 4.2 mm (range 6.2-26.8 mm) for single-handed smooth, 17.2 ± 5.0 mm (range 8.0-28.8 mm) for single-handed bounce, and 10.6 ± 3.5 mm (range 5.8-19.2) for 2-handed smooth techniques. Difference among all 3 groups reached statistical significance.

CONCLUSION

Bounce technique had the greatest average depth and variance. The 2-handed technique demonstrated the least plunge and the lowest variance, indicating the highest degree of control. This study supports the use of a 2-handed technique for drilling when intraoperative circumstances permit.

Real-Time Monitoring with a Controlled Advancement Drill May Decrease Plunge Depth

BACKGROUND

Although drill use is fundamental to orthopaedic surgery, the risk of plunging past the far cortex and potentially damaging the surrounding soft tissues remains unavoidable with conventional drilling methods. A dual motor drill may decrease that risk by providing controlled drill-bit advancement and real-time monitoring of depth and energy expenditure. We hypothesized that using the dual motor drill would decrease plunge depth regardless of the user's level of experience.

METHODS

Sixty-six subjects of varying operative experience (20 attending orthopaedic surgeons, 20 orthopaedic surgery residents, and 26 senior medical students) drilled 3 holes with a conventional drill and 3 holes with a dual motor drill in a bicortical Sawbones block set in ballistic gel. The depth of drill penetration into the ballistic gel was measured for each hole using a digital caliper.

RESULTS

Overall, subjects plunged less with the dual motor drill (0.9 mm) than with the conventional drill (4.2 mm) (p < 0.001). This finding was consistent within each group: attending surgeons (0.9 compared with 3.2 mm; p = 0.02), residents (1.0 compared with 3.0 mm; p < 0.001), and students (0.7 compared with 6.0 mm; p < 0.001). Plunge depths were also stratified into 3 categories: 0 to <2 mm, 2 to 5 mm, and >5 mm. Using the dual motor drill, subjects were more likely to plunge <2 mm (97% plunged, on average, 0 to <2 mm and 3% plunged, on average, 2 to 5 mm), whereas subjects were more likely to plunge deeper with the conventional drill (27% plunged, on average, 0 to <2 mm, 45% plunged, on average, 2 to 5 mm, and 27% plunged, on average, >5 mm). Notably, no subject plunged ≥2 mm on the third attempt with the dual motor drill. Attending surgeons (p = 0.02) and residents (p = 0.01) plunged less than students with the conventional drill. There was no significant difference between attending surgeons and residents with the conventional drill (p = 0.96). There was no significant difference in plunge depth between groups using the dual motor drill.

CONCLUSIONS

The dual motor drill significantly decreased plunge depth for both surgically experienced and inexperienced subjects. Although inexperienced subjects performed worse with the conventional drill than those with experience, there was no difference in their performance with the dual motor drill.

CLINICAL RELEVANCE

Use of a controlled advancement drill may decrease the chance of plunge-related neurovascular injury during in vivo drilling.

[Effectiveness analysis of distal radius microplate locking plate for treatment of displaced fracture of medial clavicle]

OBJECTIVE

To investigate and evaluate the effectiveness of the distal radius microplate locking plate for the treatment of displaced fracture of medial clavicle.

METHODS

Between January 2013 and June 2017, 18 cases of obvious displaced fracture of medial clavicle were treated with distal radius microlocking plate. There were 10 males and 8 females, with an average age of 51.4 years (range, 18-88 years). Causes of injury included traffic accident injury in 15 cases, heavy object injury in 3 cases; all of them were closed injury. According to Edinburgh classification, 15 cases were ⅠB1 type and 3 cases were ⅠB2 type. Fracture displacement was 12-21 mm (mean, 16.3 mm). The time from injury to operation was 3-7 days (mean, 4.3 days). After operation, the clinical healing and complications of fracture were observed, and shoulder function was evaluated according to Rockwood's scoring criteria.

RESULTS

No incisional infection, neurovascular injury, or other early complications occurred. All 18 patients were followed up 8-15 months (mean, 12 months). All fractures reached clinical osseous union, and the healing time was 8-24 weeks (mean, 16.6 weeks). Postoperative plate loosening occurred in 1 case, which was removed surgically, while other patients did not suffer from complications such as bone nonunion, displacement, internal fixator loosening, and loss of reduction. At last follow-up, according to Rockwood's scoring criteria, the results were excellent in 12 cases and good in 6 cases.

CONCLUSION

The distal radius microplate locking plate is effective for the treatment of displaced medial clavicle fracture, which has few complications, and is feasible for early functional exercise, and is helpful for the recovery of shoulder joint function.

Risk of extrapelvine vascular injuries in osteosynthesis with gliding hip screws

BACKGROUND

Dynamic hip screw (DHS) osteosynthesis represents one of the most frequently performed fixation methods in orthopedic practice. The purpose of this study was to determine the potential risk of vascular damage by DHS side-plate screws (PS) and plunging instruments for individual femoral vessels and screw positions.

METHODS

In ten hemipelvic/leg specimens mounted with a large femur distractor, a DHS system with a four-hole side-plate was inserted. PS were inserted in 3 consecutive courses with different inclinations in the frontal plane of 0° (group 1), - 30° posterior (group 2) and + 30° anterior (group 3) in relation to the side-plate's surface, resulting in 120 PS positions. After screw tightening, the soft tissues on the medial side of the femur were dissected and investigated for vascular compromise; in each course, the effect of overshot instruments within a range of 50 mm beyond the side-plate's surface was also tested.

RESULTS

Totally, 37/120 screw positions (31%) revealed potential vascular compromise which comprised of 15/120 (13%) direct hits by screw tips and 22/120 (18%) potential impacts by plunging instruments. The deep femoral artery system (DFA) was significantly (p = 0.007) most often affected but no significant differences for individual vascular structures were seen. Direct vascular impacts occurred significantly more often (p = 0.0047) in screws with 0° inclination compared to + 30° inclination (p = 0.017). Significant differences among individual screw positions were only found in group - 30° with direct vessel contacts (p = 0.038).

CONCLUSIONS

The DFA system is significantly more at risk while significant preference of a certain vessel is missing. Our data indicate that more than 30% of 120 screw positions in DHS osteosynthesis revealed a potential danger of vascular compromise, when surgical principles are denied in hip fracture fixation.

CLINICAL RELEVANCE

Though vascular complications are infrequently encountered in DHS osteosynthesis they have to be considered as a potential complication when surgical principles are not followed in this anatomic area.

Accuracy in Screw Selection in a Cadaveric, Small-Bone Fracture Model

PURPOSE

Using a cadaveric model simulating clinical situations experienced during open reduction and internal fixation of proximal phalangeal fractures, the aim of this study was to evaluate the relationship between level of training and the rates of short, long, and ideal screw length selection based on depth gauge use without fluoroscopy assistance.

METHODS

A dorsal approach to the proximal phalanx was performed on the index, middle, and ring fingers of 4 cadaveric specimens, and 3 drill holes were placed in each phalanx. Volunteers at different levels of training then measured the drill holes with a depth gauge and selected appropriate screw sizes. The rates of short, long, and ideal screw selection were compared between groups based on level of training. Ideal screws were defined as a screw that reached the volar cortex but did not protrude more than 1 mm beyond it.

RESULTS

Eighteen participants including 3 hand fellowship-trained attending physicians participated for a total of 648 selected screws. The overall rate of ideal screw selection was lower than expected at 49.2%. There was not a statistically significant relationship between rate of ideal screw selection and higher levels of training. Attending surgeons were less likely to place short screws and screws protruding 2 mm or more beyond the volar cortex CONCLUSIONS: Overall, the rate of ideal screw selection was lower than expected. The most experienced surgeons were less likely to place short and excessively long screws.

CLINICAL RELEVANCE

Based on the low rate of ideal screws, the authors recommend against overreliance on depth gauging alone when placing screws during surgery. The low-rate ideal screw length selection highlights the potential for future research and development of more accurate technologies to be used in screw selection.

Effectiveness of a Low-Cost Drilling Module in Orthopaedic Surgical Simulation

INTRODUCTION

Financial pressures and resident work hour regulations have led to adjunct means of resident education such as surgical simulation. The purpose of this study is to determine the effectiveness of a hands-on training session in orthopaedic drilling technique educational model during a surgical simulation on reducing drill plunging depth and to determine the effectiveness of senior residents teaching a hands-on training session in orthopaedic drilling technique.

METHODS

A total of 13 participants (5 orthopaedic interns and 8 medical students) drilled until they penetrated the far cortex of a synthetic bone model and the plunging depth (PD) was measured. They were then randomized and underwent an education session with an attending orthopaedic surgeon or a senior resident. Next, the subjects drilled again with the PD being calculated. The preeducational and posteducational session were compared to determine if there was any improvement in PD and if there was a difference between educators. The cost of the model was also determined.

RESULTS

The mean maximum PD and mean PD before the education session was 1.58 (1.40-2.10) and 1.50cm (1.36-1.76), respectively. Following the educational session, the mean maximum PD and mean PD were 0.53 (0.42-0.75) and 0.50cm (0.40-0.72), respectively. These were both significantly lower than before the education session (p <0.05). After the educational session taught by the attending versus the session taught by the resident, the mean maximum PD was 0.59 (0.42-0.75) and 0.49cm. (0.45-0.75), respectively (p = 0.44). After the educational session taught by the attending versus the session taught by the resident, the mean PD was 0.54 (0.40-0.72) and 0.47cm. (0.40-0.65), respectively (p = 0.44). The cost of the station per participant was $5.44.

CONCLUSION

This study demonstrated a significant reduction in drilling PD with use of a low-cost training model and a formal didactic and skills session on proper drilling technique that can effectively be led by senior residents.

When Should We Change Drill Bits? A Mechanical Comparison of New, Reprocessed, and Damaged Bits

OBJECTIVES

We assessed how reprocessed and damaged drill bits perform relative-to-new drill bits in terms of drilling force required, heat generated at near and far cortices, and number of usable passes.

METHODS

Nine pairs of nonosteoporotic human cadaveric femora were tested using 3 types of 3.2-mm drill bits (new, reprocessed, and damaged) in 3 investigations (force, temperature, and multiple usable passes). Operating room conditions were simulated. Force and temperature data were collected for each type. The multiple pass investigation measured only force.

RESULTS

New and reprocessed drill bits performed similarly regarding force required and heat generated; both outperformed damaged bits. New and reprocessed bits had a similar number of usable passes in ideal conditions. Damaged bits required nearly 2.6 times as much force to maintain drilling rate.

CONCLUSIONS

Reprocessed drill bits seem to be a viable alternative to new drill bits for fracture treatment surgery in terms of force required, heat generated, and number of usable passes. Drill bits that are damaged intraoperatively should be replaced. In ideal conditions, new and reprocessed drill bits can be used for multiple consecutive cases.

CLINICAL RELEVANCE

Reprocessed drill bits may be as effective as new drill bits, representing potential cost savings for institutions. Both types can be considered for reuse.

Evaluating Internal Fixation Skills Using Surgical Simulation

BACKGROUND

Open reduction and internal fixation (ORIF) is an essential skill for an orthopaedic surgeon, yet teaching its components to surgical residents poses challenges in both complexity and cost. Surgical simulation has demonstrated efficacy and is now a mandated component of residency programs, but the techniques and resources required for effective simulation vary greatly. We hypothesized that simulation of ORIF skills could be accomplished in a cost-effective, quantifiable, and reproducible manner and that this experience coupled with didactic learning would increase skill proficiency and enhance ORIF performance.

METHODS

Sixteen postgraduate-year-1 orthopaedic surgery interns were assessed on performance of ORIF simulation tasks before and after attending a module designed to introduce and practice internal fixation techniques. Simulation tasks addressed drilling accuracy via oblique drilling through polyvinyl chloride (PVC) cylinders and bisecting wooden dowels and plunge control via drilling through layered boards of varying densities. Fracture fixation simulation involved fixing oblique fractures on synthetic ulnae. Task performance was assessed at 3 time points: immediately before the module, 1 week after the module, and 3 months after the module. Fracture fixation was assessed before and after the module via load-to-failure testing. Success rates for the tasks were analyzed using a repeated-measures analysis of variance, and mechanical properties of the fixed ulnar constructs were compared using paired t tests.

RESULTS

In all ORIF simulation tasks, pre-module to post-module improvement in success rates was significant (p < 0.001) and improvements were maintained between the post-module assessment and the 3-month follow-up. The interns also achieved significantly greater strengths in their ulnar fixation constructs, with a mean improvement of 256 N (p = 0.01) after the module.

CONCLUSIONS

These results indicate that the technical and sensorimotor skills relevant to internal fixation (with emphasis on the specific skill of using a drill) can be significantly augmented and retained in the short term in surgical residents after exposure to faculty-led lecture and hands-on skills practice using low-cost materials.

CLINICAL RELEVANCE

This study provides evidence for an effective, accessible method of enhancing and assessing surgical skills in training.

Heat Generation During Bone Drilling: A Comparison Between Industrial and Orthopaedic Drill Bits

OBJECTIVES

Cortical bone drilling for preparation of screw placement is common in multiple surgical fields. The heat generated while drilling may reach thresholds high enough to cause osteonecrosis. This can compromise implant stability. Orthopaedic drill bits are several orders more expensive than their similarly sized, publicly available industrial counterparts. We hypothesize that an industrial bit will generate less heat during drilling, and the bits will not generate more heat after multiple cortical passes.

METHODS

We compared 4 4.0 mm orthopaedic and 1 3.97 mm industrial drill bits. Three types of each bit were drilled into porcine femoral cortices 20 times. The temperature of the bone was measured with thermocouple transducers. The heat generated during the first 5 drill cycles for each bit was compared to the last 5 cycles. These data were analyzed with analysis of covariance.

RESULTS

The industrial drill bit generated the smallest mean increase in temperature (2.8 ± 0.29°C) P < 0.0001. No significant difference was identified comparing the first 5 cortices drilled to the last 5 cortices drilled for each bit. The P-values are as follows: Bosch (P = 0.73), Emerge (P = 0.09), Smith & Nephew (P = 0.08), Stryker (P = 0.086), and Synthes (P = 0.16). The industrial bit generated less heat during drilling than its orthopaedic counterparts. The bits maintained their performance after 20 drill cycles.

CONCLUSIONS

Consideration should be given by manufacturers to design differences that may contribute to a more efficient cutting bit. Further investigation into the reuse of these drill bits may be warranted, as our data suggest their efficiency is maintained after multiple uses.

Osteosynthesis for clavicle fractures: How close are we to penetration of neurovascular structures?

INTRODUCTION

Risks associated with drill plunging are well recognised in clavicle osteosynthesis. To date no studies have described plunge depth associated with clavicle osteosynthesis.

PRIMARY AIM

To determine whether plunge depth associated with clavicle osteosynthesis is great enough to penetrate neurovascular structures and whether surgical experience reduces the risk of neurovascular injury METHOD: Cadaveric clavicles were pressed into spongy phenolic foam to allow measurement of drill bit penetration beyond the far cortex (plunge depth). 15 surgeons grouped according to experience were asked to drill a single hole in the medial, middle and lateral clavicle in 2 specimens each. Each surgeon used fully a charged standard Stryker drill with a new 2.6mm drill bit and guide. Plunge depths were measured in 0.5mm increments. Depth measurements were compared amongst groups and to previously documented distances to neurovascular structures as outlined by Robinson et al. Kruskal-Wallis test was used for overall comparison and Mann-Whitney U test was used for comparing the groups individually.

RESULTS

Mean plunge depth across all groups was 3.4mm, (0.5-6.5), 4.0mm (1mm-8.5mm) and 4.0mm (0.5mm-15mm) in the medial, middle and lateral clavicle. Plunge depths were greater than previously documented distances to the subclavian vein at the medial clavicle on nine occasions. Plunge depths in the middle and lateral clavicle were well within the previously documented distances from neurovascular structures. There was no correlation between level of experience and median plunge depth (p=0.18). However, inexperienced surgeons plunged 1mm greater than intermediate and experienced surgeons (p=0.026). There was one significant outlier; a 15mm plunge depth by an inexperienced surgeon in the lateral clavicle.

CONCLUSION

Clavicle osteosynthesis has a relatively high risk of neurovascular injury. Plunge depths through the clavicle often exceed the distance of neurovascular structures, especially in the medial clavicle. A thorough understanding of the anatomy of these neurovascular structures and methods to prevent excessive plunging is important prior to undertaking clavicle osteosynthesis.

Performance test of different 3.5 mm drill bits and consequences for orthopaedic surgery

INTRODUCTION

Drilling of bones in orthopaedic and trauma surgery is a common procedure. There are yet no recommendations about which drill bits/coating should be preferred and when to change a used drill bit.

MATERIALS AND METHODS

In preliminary studies typical "drilling patterns" of surgeons concerning used spindle speed and feeding force were recorded. Different feeding forces were tested and abrasion was analysed using magnification and a scanning electron microscope (SEM). Acquired data were used for programming a friction stir welding machine (FSWM). Four drill bits (a default AISI 440A, a HSS, an AISI 440B and a Zirconium-oxide drill bit) were analysed for abrasive wear after 20/40/60 machine-guided and hand-driven drilled holes. Additionally different drill coatings [diamond-like carbon/grafitic (DLC), titanium nitride/carbide (Ti-N)] were tested.

RESULTS

The mean applied feeding force by surgeons was 45 ± 15.6 Newton (N). HSS bits were still usable after 51 drill holes. Both coated AISI 440A bits showed considerable breakouts of the main cutting edge after 20 hand-driven drilled holes. The coated HSS bit showed very low abrasive wear. The non-coated AISI 440B bit had a similar durability to the HSS bits. The ZrO2 dental drill bit excelled its competitors (no considerable abrasive wear at >100 holes).

CONCLUSIONS

If the default AISI 440A drill bit cannot be checked by 20-30× magnification after surgery, it should be replaced after 20 hand-driven drilled holes. Low price coated HSS bits could be a powerful alternative.