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1.  Surgical Technique: Static Intramedullary Nailing of the Femur and Tibia Without Intraoperative Fluoroscopy 
On a recent mission directed at definitive care for victims of the Haitian earthquake, the orthopaedic team developed a technique for freehand distal locking of femoral and tibial nails without intraoperative fluoroscopy or proximally mounted targeting jigs.
Description of Technique
After performing open antegrade or retrograde nailing by standard techniques, the freehand lock must be obtained before doing standard outrigger locking. This allows the surgeon to control the nail and deliver the locking hole in the nail to a unicortical drill hole in the femur. Before nail insertion, the distance of the desired locking hole is measured from the outrigger in a standard way such that it can be reproduced after the nail is inserted. Through a unicortical drill hole, the nail is palpated with the tip of a Kirschner wire and systematic maneuvers allow the Kirschner wire to palpate and fall into the locking hole. The Kirschner wire is tapped across the second cortex before drilling. The screw is inserted, and the ball-tipped insertion guidewire is placed back into the nail to palpate the crossing screw confirming position.
Patients and Methods
We treated 16 patients with 18 long bone fractures using the described technique. We assessed patients clinically and radiographically immediately postoperatively.
A total of 19 blind freehand interlocks were attempted, and 17 were successful as assessed by direct intraoperative observations and by postoperative radiographs.
We describe a simple technique for performing static locked intramedullary nailing of the femur and tibia without fluoroscopy. This technique was successful in most cases and is intended for use with any nailing system only when fluoroscopy or specialized systems for nailing without fluoroscopy are not available.
PMCID: PMC3210293  PMID: 21369767
2.  Radiation-free Insertion of Distal Interlocking Screw in Tibial and Femur Nailing: A Simple Technique 
Distal interlocking screw insertion in intramedullary nailing of long-bone fracture is a challenging task for orthopedic surgeons. It is difficult particularly when the surgeon is in his learning stage or when image intensifier is not available. We describe a radiation-free technique of distal interlocking screw insertion which is easy and practicable.
Materials and Methods:
In this technique, a same length nail is placed over the skin (outer nail) and through its distal-most screw hole, a 3.2 mm drill bit is inserted to drill the distal locking screw hole of the intramedullary nail (inner nail). With a small skin incision over the distal screw holes, the distal-most screw hole is identified; the bone window overlying the screw hole is widened with an awl and a locking bolt is inserted with a washer under direct visualization. The other distal interlocking screw is simply drilled by matching the other three holes of the outer and inner nails. We have operated 86 patients (39 femoral shaft fracture and 47 tibial shaft fracture) in 1 year where this technique was used. There were 41 open fracture and 45 closed fracture.
Within 6 months of follow-up, bony union was achieved in 36 of 39 femur fractures and 45 of 47 tibial fractures. No unwanted complications were observed during the postoperative period and in follow-up.
This method of radiation-free distal interlocking screw insertion is simple and can be used in third world country where image intensifier facility is not available. However, surgeons are encouraged to use image intensifier facility where the facility is available.
PMCID: PMC3461770  PMID: 23066456
Intramedually nail; radiation; femur fracture; tibia frcature
3.  Assessment of CAOS as a training model in spinal surgery: a randomised study 
European Spine Journal  2006;16(2):239-244.
The objectives of this study were (1) to quantify the benefit of computer assisted orthopaedic surgery (CAOS) pedicle screw insertion in a porcine cadaver model evaluated by dissection and computed tomography (CT); (2) to compare the effect on performance of four surgeons with no experience of CAOS, and varying experience of pedicle screw insertion; (3) to see if CT with extended windows was an acceptable method to evaluate the position of the pedicle screws in the porcine cadaver model, compared to dissection. This was a prospective, randomised, controlled and blinded porcine cadaver study. Twelve 6-month-old porcine (white skinned Landrace) lumbar spines were scanned pre-operatively by spiral CT, as required for the CAOS computer data set. Computer randomisation allocated the specimens to one of four surgeons, all new to CAOS but with different levels of experience in spinal surgery. The usual anatomical landmarks for the freehand technique were known to all four surgeons. Two pedicles at each vertebral level were randomly allocated between conventional free hand insertion and an electromagnetic image guided surgery (NAVITRAK®) and 6.5 mm cancellous AO screws inserted. Post-operatively, spiral CT was blindly evaluated by an independent radiologist and the spine fellow to assess the accuracy of pedicle screw placement, by each method. The inter- and intra-observer reliability of CT was evaluated compared to dissection. The pedicle screw placement was assessed as perfect if within the pedicle along its central axis, or acceptable (within < 2 mm from perfect), and measured in millimetres from perfect thereafter. One hundred and sixty-six of 168 pedicles in 12 porcine spines were operated on. Complete data were present for 163 pedicles (81 CAOS, 82 freehand). In the CAOS group 84% of screws were deemed acceptable or perfect, compared to 75.6% with the freehand technique. Screw misplacement was significantly reduced using CAOS (P = 0.049). Seventy-nine percent of CAOS screws were ideally placed compared with 64% with a conventional freehand technique (P = 0.05). A logistic linear regression model showed that the miss placed pedicle screw rate was significantly reduced using CAOS (P = 0.047). CAOS benefited the least experienced surgeons most (the research registrars acceptable rate increased from 70 to 90% and the spine fellow from 76 to 86%). CAOS did not have a statistically significant effect on the experienced consultant spine surgeon increasing from 70 to 79% (P = 0.39). The experienced general orthopaedic surgeon did not benefit from CAOS (P = 0.5). CT compared to dissection showed an intra-observer reliability of 99.4% and inter-observer reliability of 92.6%. The conclusions of this study were as follows: (1) an increased number of pedicle screws were ideally placed using the CAOS electromagnetic guidance system compared to the conventional freehand technique; (2) junior surgeons benefited most from CAOS; (3) we believe CAOS (Navitrak®) with porcine lumbar spines evaluated by post operative CT, represents a useful model for training junior surgeons in pedicle screw placement; (4) experienced spine surgeons, who have never used CAOS, may find CAOS less helpful than previously reported.
PMCID: PMC2200694  PMID: 16683122
Pedicle screw insertion; Computer assisted orthopaedic surgery; Conventional fluoroscopic technique; Training model; Porcine cadaver lumbar spine study
4.  A sonography assisted technique for the removal of a femoral interlocking nail – a technical note 
Open methods for removal of femoral interlocking nails involve an incision (up to 10 cm) over the trochanter to find the tip of the nail. The distal locking screws are some times difficult to palpate and an incision (up to about 5 cm) is often needed for exposure. Intra-operative fluoroscopy is often used as an adjunct technique to minimize the surgical wound. However, patients and surgeons are exposed to a radiation hazard. Sonography can provide a real-time and efficient alternative to fluoroscopy.
Sonography of soft tissue has been established to identify a foreign body. A metallic implant has a hyperechoic image; therefore, we can identify the correct position of the screws preoperatively and intraoperatively.
We have developed a technique using sonography and minimal incisions for the removal of a femoral interlocking nail. The proximal wound is 2.5 cm in length and the wound is 0.5 cm in length for each distal locking screw.
The sonography can be used to minimize the length of incision and prevent radiation exposure in the removal of intramedullary femoral nails.
PMCID: PMC1274328  PMID: 16229748
5.  Interlocking nailing without imaging: the challenges of locating distal slots and how to overcome them in SIGN intramedullary nailing 
International Orthopaedics  2009;34(6):891-895.
Placement of the distal interlocking screw is the most difficult part in all intramedullary nail interlocking screw systems and the Surgical Implant Generation Network (SIGN) interlocking system is not an exception. SIGN nails are interlocking implants designed with a precision instrumentation set for use in treatment of long bone fractures without an image intensifier. Locating the distal slots of SIGN nails could be challenging for young SIGN surgeons when treating very complex comminuted fractures and in obese patients. This study was stimulated by a patient who presented one year after surgery with knee pain due to a migrating nail because of missed distal screws. A total of 48 patients divided into two groups of 24 were studied retrospectively and prospectively. The retrospective studies revealed that failure to locate distal locking slots in ten antegrade nailing procedures was due to wrong entry point and comminution of the fracture. The challenges encountered led us to innovating methods to overcome the difficulties of placement of distal screws in a prospective study. Application of methods A and B made location of the distal slots easier in the prospective study even though there were more complex comminuted fractures. The methods also reduced the antegrade operation time by 1 hour 11 minutes. We concluded that SIGN nailing could be challenging and frustrating at the early learning stage. Application of the two innovative methods will make distal slot location easier. They will also make SIGN interlocking nailing less difficult for young SIGN surgeons as they journey through the learning curves.
PMCID: PMC2989006  PMID: 19813011
6.  Feasibility of preoperative 125I seed-guided tumoural tracer injection using freehand SPECT for sentinel lymph node mapping in non-palpable breast cancer 
EJNMMI Research  2014;4:19.
This study was designed to explore the feasibility of replacing the conventional peri-/intratumoural ultrasound (US)-guided technetium-99m albumin nanocolloid (99mTc-nanocolloid) administration by an injection of the same tracer guided by a freehand single-photon emission computed tomography (SPECT) device in patients with non-palpable breast cancer with an iodine-125 (125I) seed as tumour marker, who are scheduled for a sentinel lymph node biopsy (SLNB). This approach aimed to decrease the workload of the radiology department, avoiding a second US-guided procedure.
In ten patients, the implanted 125I seed was primarily localised using freehand SPECT and subsequently verified by conventional US in order to inject the 99mTc-nanocolloid. The following 34 patients were injected using only freehand SPECT localisation. In these patients, additional SPECT/CT was acquired to measure the distance between the 99mTc-nanocolloid injection depot and the 125I seed. In retrospect, a group of 21 patients with US-guided 99mTc-nanocolloid administrations was included as a control group.
The depth difference measured by US and freehand SPECT in ten patients was 1.6 ± 1.6 mm. In the following 36 125I seeds (34 patients), the average difference between the 125I seed and the centre of the 99mTc-nanocolloid injection depot was 10.9 ± 6.8 mm. In the retrospective study, the average distance between the 125I seed and the centre of the 99mTc-nanocolloid injection depot as measured in SPECT/CT was 9.7 ± 6.5 mm and was not significantly different compared to the freehand SPECT-guided group (two-sample Student's t test, p = 0.52).
We conclude that using freehand SPECT for 99mTc-nanocolloid administration in patients with non-palpable breast cancer with previously implanted 125I seed is feasible. This technique may improve daily clinical logistics, reducing the workload of the radiology department.
PMCID: PMC4052880  PMID: 24949282
Freehand SPECT; Declipse®SPECT; 125Iodine seed; Sentinel lymph node biopsy; Non-palpable breast cancer
7.  Intramedullary fixation of forearm fractures with new locked nail 
Indian Journal of Orthopaedics  2011;45(5):410-416.
Lack of availability of interlocked nails made plate osteosynthesis the first choice of treatment of forearm fractures inspite of more surgical exposure, periosteal stripping and big skin incision subsequent scar along with higher risk of refracture on implant removal. We hereby report the first 12 cases with 19 forearm bone fractures internally fixed by indegenous interlocked nail.
Materials and Methods:
Existing square nails were modified to have a broad proximal end of 5.5 mm with a hole for locking screw of 2.5 mm. The nail has a distal hole of 1/1.2/1.5 mm in 2.5/3/3.5 mm diameter nail, respectively. A new method of distal locking with a clip made of k wire is designed. The clip after insertion into the bone and hole in nail and opposite cortex snuggly fits the bone providing a secure locking system. Twelve skeletally mature patients, mean age 32 years (range 24-45 years) with 19 diaphyseal fractures of the forearm were treated with this indigenously made new nail. The patient were evaluated for fracture union, functional recovery and complications. The functional outcome was assessed by disabilities of arm, shoulder and hand questionnaire (DASH score).
Time to radiographic union ranged between 12 and 28 weeks, with a 100% union rate. Complications were minimal, with mild infection in open fracture (n=1) and delayed union (n=1) in patient with comminuted fracture of the ulna only. The clinical results were excellent. The DASH score ranged between 0 and 36 points.
This new interlocking nail may be considered as an alternative to plate osteosynthesis for fractures of the forearm in adults. The advantages are benefit of closed reduction, smaller residual scar, reduced cost and early union with allowance of immediate movements.
PMCID: PMC3162676  PMID: 21886921
Forearm fractures; intramedullary fixation; locked nail; osteosynthesis
8.  Intramedullary nailing of humeral diaphyseal fractures. Is distal locking really necessary? 
Distal interlocking is regarded as an inherent part of the antegrade humeral nailing technique, but it exposes both the patient and surgeon to radiation, is time consuming, and has a potential risk of damaging neurovascular structures. We have presented our technique of diaphyseal humeral nailing without any distal interlocking in this paper.
Materials and Methods:
We have presented a series of 64 consecutive patients (33 male and 31 female, mean age: 41.5 years) with humeral shaft fractures treated with antegrade rigid intramedullary nailing without distal interlocking following a strict intra and postoperative protocol. According to the AO classification, there were 36 type A fractures, 22 type B, and 6 type C. Nails were inserted unreamed or by using limited proximal reaming and they were fitted as snuggly as possible into the medullary canal. After impaction of the nail into the fossa, we carefully tested rotational stability of fixation by checking any potential external rotation when the arm was slightly turned externally and left to the gravity forces. We were ready to add distal screws, but that was not required in these cases. Follow-up assessment included fracture union, complications and failures, and the final clinical outcome at minimum 2-year follow-up using the parameters of the constant score.
All fractures, except two, united between the 4th and 5th postoperative month. In one case, nail was exchanged with plate, and, in another, a larger nail was used at a second surgery. Shoulder function according to constant score, at a minimum of 2-year follow-up, was excellent or very good in 93.7% of the patients.
Provided that some technical issues are followed, the method reduces intraoperative time and radiation exposure and avoids potential damage to neurovascular structures.
PMCID: PMC3743033  PMID: 23960365
Distal interlocking; humeral fractures; humeral nailing
9.  Fatigue performance of angle-stable tibial nail interlocking screws 
International Orthopaedics  2012;37(1):113-118.
Tibial nail interlocking screw failure often occurs during delayed fracture consolidation or at early weight bearing of nailed unstable fractures, in general when high implant stress could not be reduced by other means. Is there a biomechanical improvement in long-term performance of angle stable locking screws compared to conventional locking screws for distal locking of intramedullary tibial nails?
Surrogate bones of human tibiae were cut in the distal third and distal locking of the 10 mm intramedullary tibial nail was performed with either two angle stable locking screws or two conventional locking screws in the mediolateral plane. Six specimens per group were mechanically tested under quasi-static and cyclic axial loading with constantly increasing force.
Angle stable locking screw constructs exhibited significantly higher stiffness values (7,809 N/mm ± 647, mean ± SD) than conventional locking screw constructs (6,614 N/mm ± 859, p = 0.025). Angle stable locking screw constructs provided a longer fatigue life, expressed in a significantly higher number of cycles to failure (187,200 ± 18,100) compared to conventional locking screw constructs (128,700 ± 7,000, p = 0.004).
Fatigue performance of locking screws can be ameliorated by the use of angle stable locking screws, being especially important if the nail acts as load carrier and an improved stability during fracture healing is needed.
PMCID: PMC3532652  PMID: 22875484
10.  Expandable self-locking nail in the management of closed diaphyseal fractures of femur and tibia 
Indian Journal of Orthopaedics  2009;43(3):264-270.
Intramedullary fixation is the treatment of choice for closed diaphyseal fractures of femur and tibia. The axial and rotational stability of conventional interlocking nails depends primarily on locking screws. This method uses increased operating time and increased radiation exposure. An intramedullary implant that can minimize these disadvantages is obviously better. Expandable intramedullary nail does not rely on interlocking screws and achieves axial and rotational stability on hydraulic expansion of the nail. We analyzed 32 simple fractures of shaft of femur and tibia treated by self-locking expandable nail.
Materials and Methods:
Intramedullary fixation was done by using self-locking, expandable nail in 32 patients of closed diaphyseal fractures of tibia (n = 10) and femur (n = 22). The various modes of injury were road traffic accidents (n = 21), fall from height (n = 8), simple fall (n = 2), and pathological fracture (n = 1). Among femoral diaphyseal fractures 16 were males and six females, average age being 33 yrs (range, 18- 62 yrs). Seventeen patients had AO type A (A1 (n = 3), A2 (n = 4), A3 (n = 10)) and 5 patients had AO type B (B1 (n = 2), B2 (n = 2), B3 (n = 1)) fractures. Eight patients having tibial diaphyseal fractures were males and two were females; average age was 29.2 (range, 18- 55 yrs). Seven were AO type A (A1 (n = 2), A2 (n = 3), A3 (n = 2)) and three were AO type B (B1 (n = 1), B2 (n = 1), and B3 (n = 1)). We performed closed (n = 27) or open reduction (n = 5) and internal fixation with expandable nail to stabilize these fractures. The total radiation exposure during surgery was less as no locking screws were required. Early mobilisation and weight-bearing was started depending on fracture personality and evidences of healing. Absence of localised tenderness and pain on walking was considered clinical criteria for union, radiographic criteria of union being continuity in at least in three cortices in both AP and lateral views. Patients were followed for at least one year.
The average operative time was 90 min (range, 55-125 min) for femoral fractures and 53 min (range, 25-115 min) for tibial fractures. Radiation exposure was minimum, average being 84 seconds (range, 54-132) for femoral fractures and 54 seconds (range, 36-78) for tibial fractures. All fractures healed, but few had complications, such as infection (one case with tibial fracture) bent femoral nail with malunion (n = 1), and delayed union (n = 3; 2 cases in femur and 1 case in tibia). Mean time of union was 5.1 months (range, 4-10½ months) for femoral fractures and 4.8 months (range, 3-9 months) for tibial fractures.
We found the nail very easy to use with effective fixation in AO type A and B fractures in our setting. Less surgical time is required with minimum complications. The main advantage of the expandable nail is that if affords. satisfactory axial, rotatory, and bending stability with decreased radiation exposure to operating staff and the patient.
PMCID: PMC2762176  PMID: 19838349
Diaphyseal fracture femur; diaphysial fracture tibia; expandable nail; self-locking nail; radiation risk
11.  Guided Application of Ventricular Catheters (GAVCA) - multicentre study to compare the ventricular catheter position after use of a catheter guide versus freehand application: study protocol for a randomised trail 
Trials  2013;14:428.
The standard technique for the placement of ventricular catheters (VC) comprises a high proportion of malpositioning of the catheter (12.5 to 40%). Technical advances such as neuronavigation or ultrasound have been shown to increase the accuracy of the procedure. Since these means result in significant technical and time consuming efforts, they are used for selected cases only. In order to simplify the controlled placement of ventricular catheters a newly developed smartphone assisted guiding tool has been introduced. In this study the efficacy and safety of this guiding tool is determined.
This study is a multicentre, randomised, controlled trial. A total of 144 patients planned for an elective shunting procedure will be enrolled throughout 10 study centres within two years. The primary objective of the trial is to show the superiority of the guided placement in comparison to the standard freehand technique of ventricular catheter application. Patients will be followed up for 30 days after the operation in regard to image-based evaluation of the catheter position as well as possible shunt dysfunction and complications.
The Guided Application of Ventricular Catheters (GAVCA) trial compares the guided catheter positioning with the standard freehand technique of catheter placement in hydrocephalic patients. If superiority is shown, the standard technique may be changed with the advantage of a more reliable and safer positioning of the ventricular catheter with just a slight effort in time and pre-operative planning.
Trial registration
The GAVCA trial is registered at under the number NCT01811589.
PMCID: PMC3866392  PMID: 24330776
12.  Validation of navigation assisted cup placement in total hip arthroplasty 
International Orthopaedics  2011;36(1):17-22.
Computer navigation has the potential to provide precise intraoperative knowledge to the surgeon. Previous studies with navigation have confirmed its function for improved component position but few studies have reported the accuracy and precision of navigation system in clinical use. With this study we propose to evaluate the efficacy of navigation in guiding cup placement.
Fifty-six patients undergoing primary total hip arthroplasty were prospectively included in this study. Stryker imageless navigation system which is accurate to 0.5° was used in all cases. Intraoperative data was collected for the acetabular component position using navigation for the freehand cup placement and the final cup placement done using navigation. Postoperative evaluation of component position was done with computed tomography (CT) and the deviation from intraoperative freehand and navigation values were calculated.
The mean inclination of the freehand reading was 39.5° (range, 20°–58°), mean version of freehand reading was 10.7° (−6°– 27°), and the mean navigation reading was 43.2° (37°–49°) for inclination and 13.0° (−8° – 24°) for version. On postoperative CT scan analysis the mean inclination was 45.3° (34°–56°) and mean version was 15.1° (4°–25°). The deviation of the freehand inclination from the post operative CT scan reading was 11.4° (1°–30°) and the version deviated by a mean of 10.8° (2°–26°). The deviation of the navigation reading from the CT scan reading had a mean of 5.3° (1°–13°) for inclination and 5.6° (1°–17°) for version.
The accuracy of the navigation system over conventional freehand cup placement is validated by this study.
PMCID: PMC3251664  PMID: 21537975
13.  Showcase of Intraoperative 3D Imaging of the Sentinel Lymph Node in a Breast Cancer Patient using the New Freehand SPECT Technology 
Breast Care  2012;7(6):484-486.
After the development of a hand-held intraoperative device for 3D real-time imaging of radioactively labeled sentinel lymph nodes in the human body, we present our first experience with the newest version of the freehand single-photon emission computed tomography (SPECT) technology in the operating room. The freehand SPECT system combines a gamma probe and an optical infrared positioning system, and provides surgeons with 3D imaging including exact depth information of the radioactive target. This technology was used intraoperatively in a female breast cancer patient to localize the axillary sentinel lymph nodes. The data obtained with freehand SPECT correlate well with conventional lymphoscintigraphy and with data collected using a conventional hand-held probe. By offering fast real-time intraoperative imaging, the new freehand SPECT system might facilitate the detection and removal of the sentinel lymph node(s) in certain situations and can be used for documentation and quality assurance purposes.
PMCID: PMC3971815  PMID: 24715831
Breast cancer; Lymph node dissection; Quality assurance; Sentinel lymph node
14.  Intramedullary fixation of proximal humerus fractures: do locking bolts endanger the axillary nerve or the ascending branch of the anterior circumflex artery? A cadaveric study 
Proximal humerus fractures are one of the most common fractures. Intramedullary locked nailing is becoming a popular alternative treatment, especially for easier fracture patterns. Although axillary nerve injury has been reported, no study has compared the safety of the proximal locking options relative to the axillary nerve and the ascending branch of the anterior circumflex artery.
Six different commercially available proximal humeral nails were implanted in 30 shoulders of 18 cadavers. After fluoroscopically guided implantation the shoulders were carefully dissected and the distance between the locking screws, the axillary nerve and the ascending branch of the anterior circumflex artery was measured.
The course of the axillary nerve varies. A mean distance of 55.8 mm (SD = 5.3) between the lateral edge of the acromions and the axillary nerve at the middle of the humerus in a neutrally rotated position was observed. The minimum distance was 43.4 mm, the maximum 63.9 mm.
Bent nails with oblique head interlocking bolts appeared to be the most dangerous in relation to the axillary nerve. The two designs featuring such a bend and oblique bolt showed a mean distance of the locking screw to the axillary nerve of 1 mm and 2.7 mm respectively Sirus (Zimmer®) and (Stryker®) T2 PHN (Proximal Humeral Nail)).
Regarding the ascending branch of the anterior circumflex artery, there was no difference between the nails which have an anteroposterior locking option.
It is of great importance for surgeons treating proximal humerus fractures to understand the relative risk of any procedure they perform. Since the designs of different nailing systems risk damaging the axillary nerve and ascending branch, blunt dissection, the use of protection sleeves during drilling and screw insertion, and individual risk evaluation prior to the use of a proximal humeral nail are advocated.
PMCID: PMC2636765  PMID: 19087350
15.  Freehand Liver Volumetry by Using an Electromagnetic Pen Tablet: Accuracy, Precision, and Rapidity 
Journal of Digital Imaging  2010;24(2):360-365.
The purpose of this study is to assess the accuracy, precision, and rapidity of liver volumes calculated by using a freehand electromagnetic pen tablet contourtracing method as compared with the volumes calculated by using the standard optical mouse contourtracing method. The imaging data used as input for accuracy and precision testing were computed by software developed in our institution. This computer software can generate models of solid organs and allows both standard mouse-based and electromagnetic pen-driven segmentation (number of data sets, n = 70). The images used as input for rapidity testing was partly computed by modeling software (n = 70) and partly selected from contrast-enhanced computed tomography (CT) examinations (n = 12). Mean volumes and time required to perform the segmentation, along with standard deviation and range values with both techniques, were calculated. Student's t test was used to assess significance regarding mean volumes and time calculated by using both segmentation techniques on phantom and CT data sets. P value was also calculated. The mean volume difference was significantly lower with the use of the freehand electromagnetic pen as compared with the optical mouse (0.2% vs. 1.8%; P < .001). The mean segmentation time per patient was significantly shorter with the use of the freehand electromagnetic pen contourtracing method (354.5 vs. 499.1 s on phantoms; 457.4 vs. 610.0 s on CT images; P < .001). Freehand electromagnetic pen-based volumetric technique represents a technologic advancement over manual mouse-based contourtracing because of the superior statistical accuracy and sensibly shorter time required. Further studies focused on intra- and interobserver variability of the technique need to be performed before its introduction in clinical application.
PMCID: PMC3056975  PMID: 20352280
Liver volumetry; computed tomography (CT); pen tablet; contour tracing
16.  Accuracy of thoracic pedicle screw placement in scoliosis using the ideal pedicle entry point during the freehand technique 
International Orthopaedics  2008;33(2):469-475.
Previously, we described the ideal pedicle entry point (IPEP) for the thoracic spine at the base of the superior facet at the junction of the lateral one third and medial two thirds with the freehand technique on cadavers. Here we measured the accuracy of thoracic pedicle screw placement (Chung et al. Int Orthop 2008) on post-operative computed tomography (CT) scans in 43 scoliosis patients who underwent operation with the freehand technique taking the same entry point. Of the 854 inserted screws, 268 (31.3%) were displaced; 88 (10.3%) and 180 (21.0%) screws were displaced medially and laterally, respectively. With regard to the safe zone, 795 screws were within the safe zone representing an accuracy rate of 93%; 448 and 406 thoracic screws inserted in adolescent idiopathic and neuromuscular scoliosis showed an accuracy of 89.9 and 94%, respectively (p = 0.6475). The accuracy rate of screws inserted in the upper, middle and lower thoracic pedicles were 94.2, 91.6 and 93.7%, respectively (p = 0.2411). The results indicate that IPEP should be considered by surgeons during thoracic pedicle screw instrumentation.
PMCID: PMC2899059  PMID: 18357448
17.  Cervical pedicle screw placement: feasibility and accuracy of two new insertion techniques based on morphometric data 
European Spine Journal  2006;16(1):47-56.
This morphometric and experimental study was designed to assess the dimensions and axes of the subaxial cervical pedicles and to compare the accuracy of two different techniques for subaxial cervical pedicle screw (CPS) placement using newly designed aiming devices. Transpedicular fixation is increasingly used for stabilizing the subaxial cervical spine. Development of the demanding technique is based on morphometric studies of the pedicle anatomy. Several surgical techniques have been developed and evaluated with respect to their feasibility and accuracy. The study was carried out on six conserved human cadavers (average age 85 years). Axes and dimensions of the pedicles C3–C7 (60 pedicles) were measured using multislice computed tomography (CT) images prior to surgery. Two groups consisting of 3 specimens and 30 pedicles each were established according to the screw placement technique. For surgical technique 1 (ST1) a para-articular mini-laminotomy was performed. Guidance of the drill through the pedicle with a handheld aiming device attached onto the medial aspect of the pedicle inside the spinal canal. Screw hole preparation monitored by lateral fluoroscopy. In surgical technique 2 (ST2) a more complex aiming device was used for screw holes drilling. It consists of a frame with a fully adjustable radiolucent arm for carrying the instruments necessary for placing the screws. The arm was angled according to the cervical pedicle axis as determined by the preoperative CT scans. Drilling was monitored by lateral fluoroscopy. In either technique 3.5 mm screws made of carbon fiber polyetheretherketone (CF-PEEK) were inserted. The use of the CF-PEEK screws allowed for precise postoperative CT-assessment since this material does not cause artifacts. Screw placement was qualified from ideal to unacceptable into four grades: I = screw centered in pedicle; IIa = perforation of pedicle wall less than one-fourth of the screw diameter; IIb = perforation more than one-fourth of the screw diameter without contact to neurovascular structures; III = screw more than one-fourth outside the pedicle with contact to neurovascular structures. Fifty-six pedicle screws could be evaluated according to the same CT protocol that was used preoperatively. Accuracy of pedicle screw placement did not reveal significant differences between techniques 1 and 2. A tendency towards less severe misplacements (grade III) was seen in ST2 (15% in ST2 vs. 23% in ST1) as well as a higher rate of screw positions graded IIa (62% in ST2 vs. 43% in ST1). C4 and C5 were identified to be the most critical vertebral levels with three malpositioned screws each. Because of the variability of cervical pedicles preoperative CT evaluation with multiplanar reconstructions of the pedicle anatomy is essential for transpedicular screw placement in the cervical spine. Cadaver studies remain mandatory to develop safer and technically less demanding procedures. A similar study is projected to further develop the technique of CPS fixation with regard to safety and clinical practicability.
PMCID: PMC2198884  PMID: 16628443
Cervical spine; Cervical pedicle; Anatomical study; Fixation technique
18.  Simultaneous Use of Cannulated Reamer and Schanz Screw for Closed Intramedullary Femoral Nailing 
ISRN Surgery  2011;2011:502408.
Introduction. Closed reduction is a critical component of the intramedullary nailing and at times can be difficult and technically challenging resulting in increased operative time. Fluoroscopy is used extensively to achieve closed reduction which increases the intra-operative radiation exposure. Materials and Methods. Sixty patients with femoral diaphyseal fractures treated by locked intramedullary nailing were randomized in two groups. In group I, fracture reduction was performed under fluoroscopy with a cannulated reamer in the proximal fragment or with simultaneous use of a cannulated reamer in the proximal fragment and a Schanz screw in the distal fragment. Patients in group II had fracture reduction under fluoroscopy alone. Results. Closed reduction was achieved in 29 patients in group I and 25 patients in group II. The guide wire insertion time, time for nail insertion and its distal locking, total operative time, and total fluoroscopic time were 26.57, 27.93, 68.03, and 0.19 minutes in group I, compared with 30.87, 27.83, 69.93, and 0.24 minutes in group II, respectively. The average number of images taken to achieve guide wire insertion, for nail insertion and its locking and for the complete procedure in group I, respectively, was 12.33, 25.27, and 37.6 compared with 22.1, 26.17, and 48.27, respectively, in group II. Conclusion. The use of cannulated reamer in proximal fragment as intramedullary joystick and Schanz screw and in the distal fragment as percutaneous joystick facilitates closed reduction of the fracture during closed intramedullary femoral nailing with statistically significant reduction in guide wire insertion time and radiation exposure.
PMCID: PMC3200078  PMID: 22084760
19.  Distal Locking of Tibial Nails 
The indications for intramedullary nailing have expanded to include most tibial shaft fractures. Nail design has improved since their first introduction, but distal locking remains a difficult part of the procedure, resulting in radiation exposure to the patient and the surgeon and increased operation time. To address these issues, we describe an alternative surgical technique using a newly designed distal targeting device that consists of a proximally mounted aiming arm, and we report the preliminary data from its use in all tibial shaft fractures amenable to surgery for a 2–year period. Sixty-three tibial shaft fractures were treated with this method. The mean duration of the distal locking was 6.5 minutes, and in all successful cases, radiation exposure for distal locking was two shots (one shot before targeting and another for the confirmation of proper screw insertion). Radiation exposure was on average 0.85 seconds (range, 0.4–1.2 seconds) and 1.4 mGy (range, 0.8–1.9 mGy). There were no major intraoperative complications related to the technique. The method has certain advantages and can reduce radiation exposure and operation time. Nonetheless, familiarity with the instrumentation is a prerequisite for accurate distal locking.
Level of Evidence: Level IV Therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.
PMCID: PMC2505307  PMID: 18196396
20.  Novel free-hand T1 pedicle screw method: Review of 44 consecutive cases 
Summary of Background Data:
Multilevel posterior cervical instrumented fusions are becoming more prevalent in current practice. Biomechanical characteristics of the cervicothoracic junction may necessitate extending the construct to upper thoracic segments. However, fixation in upper thoracic spine can be technically demanding owing to transitional anatomy while suboptimal placement facilitates vascular and neurologic complications. Thoracic instrumentation methods include free-hand, fluoroscopic guidance, and CT-based image guidance. However, fluoroscopy of upper thoracic spine is challenging secondary to vertebral geometry and patient positioning, while image-guided systems present substantial financial commitment and are not readily available at most centers. Additionally, imaging modalities increase radiation exposure to the patient and surgeon while potentially lengthening surgical time.
Materials and Methods:
Retrospective review of 44 consecutive patients undergoing a cervicothoracic fusion by a single surgeon using the novel free-hand T1 pedicle screw technique between June 2009 and November 2012. A starting point medial and cephalad to classic entry as well as new trajectory were utilized. No imaging modalities were employed during screw insertion. Postoperative CT scans were obtained on day 1. Screw accuracy was independently evaluated according to the Heary classification.
In total, 87 pedicle screws placed were at T1. Grade 1 placement occurred in 72 (82.8%) screws, Grade 2 in 4 (4.6%) screws and Grade 3 in 9 (10.3%) screws. All Grade 2 and 3 breaches were <2 mm except one Grade 3 screw breaching 2-4 mm laterally. Only two screws (2.3%) were noted to be Grade 4, both breaching medially by less than 2 mm. No new neurological deficits or returns to operating room took place postoperatively.
This modification of the traditional starting point and trajectory at T1 is safe and effective. It attenuates additional bone removal or imaging modalities while maintaining a high rate of successful screw placement compared to historical controls.
PMCID: PMC4173230  PMID: 25288835
Cervicothoracic; free-hand; pedicle screw; technique; thoracic; thoracic starting points
21.  Case Report: A Technique to Remove a Jammed Locking Screw from a Locking Plate 
Locking titanium plates revolutionized the treatment of osteoporotic and metaphyseal fractures of long bones. However as with any innovation, with time new complications are identified. One of the problems with titanium locking plates is removal of screws, often attributable to cold welding of screw heads into the locking screw holes. Several techniques have been described to overcome this problem. We describe a new easy technique to remove a jammed locking screw in a locking plate that is easily reproducible and suggest an algorithm to determine the method to remove screws from locking plates.
Case Description
A 57-year-old man underwent removal of a locking titanium plate from the distal femur. Because the screws could not be readily removed, we used a new technique to remove the jammed locking screws. A radial cut was made in the plate into the locking screw hole and wedged with an osteotome. This released the screw head from the locking screw hole. The screw holes were connected with radial cuts and jammed locking screws were removed in a similar fashion.
Literature Review
Instruments used for removal of locking screws, including conical extraction screws, hollow reamers, extraction bolts, modular devices, and carbide drill bits, have been described. However, these do not always work.
Purposes and Clinical Relevance
Removing screws from locking titanium plates can be difficult. There is no method of implant removal that can be universally applied. Therefore, this new technique and our algorithm may be used when removing screws from locking titanium plates.
PMCID: PMC3018209  PMID: 20700670
22.  Minimally invasive percutaneous transpedicular screw fixation: increased accuracy and reduced radiation exposure by means of a novel electromagnetic navigation system 
Acta Neurochirurgica  2010;153(3):589-596.
Minimally invasive percutaneous pedicle screw instrumentation methods may increase the need for intraoperative fluoroscopy, resulting in excessive radiation exposure for the patient, surgeon, and support staff. Electromagnetic field (EMF)-based navigation may aid more accurate placement of percutaneous pedicle screws while reducing fluoroscopic exposure. We compared the accuracy, time of insertion, and radiation exposure of EMF with traditional fluoroscopic percutaneous pedicle screw placement.
Minimally invasive pedicle screw placement in T8 to S1 pedicles of eight fresh-frozen human cadaveric torsos was guided with EMF or standard fluoroscopy. Set-up, insertion, and fluoroscopic times and radiation exposure and accuracy (measured with post-procedural computed tomography) were analyzed in each group.
Sixty-two pedicle screws were placed under fluoroscopic guidance and 60 under EMF guidance. Ideal trajectories were achieved more frequently with EMF over all segments (62.7% vs. 40%; p = 0.01). Greatest EMF accuracy was achieved in the lumbar spine, with significant improvements in both ideal trajectory and reduction of pedicle breaches over fluoroscopically guided placement (64.9% vs. 40%, p = 0.03, and 16.2% vs. 42.5%, p = 0.01, respectively). Fluoroscopy time was reduced 77% with the use of EMF (22 s vs. 5 s per level; p < 0.0001) over all spinal segments. Radiation exposure at the hand and body was reduced 60% (p = 0.058) and 32% (p = 0.073), respectively. Time for insertion did not vary between the two techniques.
Minimally invasive pedicle screw placement with the aid of EMF image guidance reduces fluoroscopy time and increases placement accuracy when compared with traditional fluoroscopic guidance while adding no additional time to the procedure.
PMCID: PMC3040822  PMID: 21153669
Minimally invasive; Electromagnetic field navigation; Pedicle screw; Fluoroscopy; Accuracy
23.  A new approach to computer-aided spine surgery: fluoroscopy-based surgical navigation 
European Spine Journal  2000;9(Suppl 1):S078-S088.
A new computer-based navigation system for spinal surgery has been designed. This was achieved by combining intraoperative fluoroscopy-based imaging using conventional C-arm technology with freehand surgical navigation principles. Modules were developed to automate digital X-ray image registration. This is in contrast to existing computed tomography- (CT) based spinal navigation systems, which require a vertebra-based registration procedure. Cross-referencing of the image intensifier with the surgical object allows the real-time image-interactive navigation of surgical tools based on one single registered X-ray image, with no further image updates. Furthermore, the system allows the acquisition and real-time use of multiple registered images, which provides an advanced multi-directional control (pseudo 3D) during surgical action. Stereotactic instruments and graphical user interfaces for image-interactive transpedicular screw insertion have been developed. A detailed validation of the system was performed in the laboratory setting and throughout an early clinical trial including eight patients in two spine centers. Based on the resulting data, the new technique promises improved accuracy and safety in open and percutaneous spinal surgery.
PMCID: PMC3611449
Key words Spine; Implant; Pedicle screws; Navigation; Fluoroscopy
24.  Freehand determination of the trajectory angle for cervical lateral mass screws: how accurate is it? 
European Spine Journal  2011;20(6):972-976.
Different methods of lateral mass screw placement in the cervical spine have been described with separate trajectories for each technique in the sagittal and parasagittal planes. In the latter, plane 30° has been recommended in the modified Magerl’s technique as the optimum angle to avoid injury to the vertebral artery and nerve root. The estimation of this angle remains arbitrary and very much operator dependant. The aim of this study was to assess how accurately the lateral trajectory angle of 30° is achieved by visual estimation amongst experienced surgeons in a tertiary spinal unit and to determine the likelihood of neurovascular injury during the procedure. We chose an anatomical ‘sawbone’ model of the cervical spine with simulated lordosis. The senior author marked the entry points. Five spinal consultants and five senior spinal fellows were asked to insert 1.6-mm K wires into the lateral masses of C3 to C6 bilaterally at 30° to the midsagittal plane using the marked entry points. The lateral angulation in the transverse plane was measured using a custom protractor and documented for each surgeon at each level and side. The mean and standard deviation (SD) of the data were obtained to determine the inter observer variability. Utilising this data, measurements were then made on a normal axial computerised tomography (CT) scan of the cervical spine of an anonymous patient to determine if there would have been any neurovascular compromise. Among the 10 surgeons, a total of 80 insertion angles were measured from C3 to C6 on either side. The overall mean angle of insertion was 25.15 (range 20.4–34.8). The overall SD was 4.78. Amongst the 80 measurements between the ten surgeons, two episodes of theoretical vertebral artery violation were observed when the angles were simulated on the CT scan. A moderate but notable variability in trajectory placement exists between surgeons during insertion of cervical lateral mass screws. Freehand estimation of 30° is not consistently achieved between surgeons and levels. In patients with gross degenerative or deformed cervical spine anatomy, this may increase the risk of neurovascular injury. The use of the ipsilateral lamina as an anatomical reference plane is supported.
PMCID: PMC3099156  PMID: 21279393
Cervical spine; Lateral mass screw; Surgical technique; Reliability
25.  A Comparitive Clinical Study Between Self Tapping and Drill Free Screws as a Source of Rigid Orthodontic Anchorage 
Background and Objectives
Self-tapping miniscrews are commonly being used as a temporary anchorage device for orthodontic purpose. A prerequisite for the insertion of these screws is the preparation of a pilot hole, which is time consuming and may result in damage to nerves, tooth root, drill bit breakage and thermal necrosis of bone. On the other hand the design of drill-free screws enables them to be inserted without drilling. The aim of this prospective study was to compare the stability and clinical response of the soft tissue around the self tapping and drill free screws when used for orthodontic anchorage for en mass retraction of maxillary anterior teeth.
Materials and Methods
The study sample consisted of 20 patients requiring retraction of maxillary anterior teeth. The screws were placed in the alveolar bone between maxillary 2nd premolar and 1st molar bilaterally at the junction of attached gingiva and moveable mucosa. Pilot hole was drilled on the side which was selected for insertion of the self tapping screw under copious irrigation, after which it was inserted. Drill free screw was inserted on the contralateral side without predrilling. All screws were immediately loaded with 150–200 gm of retraction force. Patients were recalled for regular follow up for a period of 6 months. If the screws became mobile or showed any signs of inflammation during the course of the study, they were considered to be a failure.
After a period of 6 months an overall success rate of 77.5% was noted. Four self tapping and five drill-free screws failed during the study. There was no statistically significant difference between the two types of screws with respect to success/failure. Mobility was found to be the major cause for the failure.
Both self-tapping and the drill-free screws are effective anchorage units. But the latter have an edge over the conventional self-tapping screws because of decrease in operative time, little bone debris, less thermal damage, lower morbidity, and minimal patient discomfort as predrilling is not required, thus they can be used as a viable alternative. But self-tapping screws are still recommended for areas with high bone density and thick cortical bone.
PMCID: PMC3319814  PMID: 23449815
Orthodontic anchorage; Mini implants; Self-tapping screw; Drill-free screws

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