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.

Safety and Efficacy of the Under-Corrected Frontalis Sling in Myogenic Ptosis Accompanying Extraocular Muscle Paralysis.

OBJECTIVE: The surgical treatment of myogenic ptosis accompanying extraocular muscle paralysis is an intractable problem in the field of oculoplastic surgery due to the severe complications such as exposure keratopathy. It is promising to find an appropriate procedure to treat this kind of patients, which is able to ensure the safety and efficacy. METHODS: The authors retrospectively reviewed 12 eyes of 6 patients who underwent the under-corrected "double V-Loop" frontalis suspension sling procedure for myogenic ptosis accompanying extraocular muscle paralysis and access the safety and efficacy of this kind of surgery. All the patients underwent corneal fluorescein staining and confocal microscopy before and after the surgery to inspect the corneal condition. The density of central corneal epithelial cells and endothelial cells were observed. RESULTS: After the surgery, the eyelids contour was natural, and the symmetry was achieved in these cases. The average palpebral fissures height changed from 2.75 ±â€Š1.41 mm to 4.50 ±â€Š0.35 mm (P = 0.0007) and margin reflex distance 1 changed from -1.25 ±â€Š1.22 mm to +0.50 ±â€Š0.35 mm (P = 0.0002). Out of 12 operated eyes, mild postoperative lagophthalmos was present in 4 cases but without exposure keratopathy during the follow-up, the confocal microscopy showed that there were no significant differences in central corneal superficial epithelial cells (P = 0.93) and endothelial cells (P = 0.90) before and after the surgery. CONCLUSION: The under-corrected "double V-Loop" frontalis suspension sling is a proper surgery in myogenic ptosis accompanying extraocular muscle paralysis, which leads to a low occurrence of exposure keratopathy, maintains the integrity of the cornea, and remains the patients' vision function.

Can You Stall a Baclofen Pump During a Magnetic Rod Lengthening?

INTRODUCTION: Baclofen pumps are susceptible to magnetic forces because of the internal drug delivery mechanism. Magnetically controlled growing rods, sometimes implanted in the patients who have pumps, are lengthened using a device that generates a magnetic field. No previous study has determined if the external remote controller (ERC) can stall a baclofen pump during a rod lengthening. METHODS: Two baclofen pumps were placed in proximity to the ERC while it generated a magnetic field. This process was repeated with variations in the distance between pump and ERC, speed (dose) of the pump, lengthening time, and position of the ERC relative to the pump. The presence or absence of a stall was recorded. RESULTS: To stall a baclofen pump, the ERC needed to be running consistently for at least 30 mm of lengthening. The pump would not stall if it was >1 cm away from the ERC. The pump was more likely to stall if it was positioned in front of or behind the magnetic field, as opposed to the center of the field. DISCUSSION: As long as the baclofen pump is >1 cm away from the ERC, the pump will not stall, regardless of the length of time the ERC generates a magnetic field.

Diagnostic accuracy of 99mTc-antigranulocyte SPECT/CT in patients with osteomyelitis and orthopaedic device-related infections: A retrospective analysis.

OBJECTIVES: Conventional imaging techniques are routinely used in the diagnostic work-up of patients with suspected osteomyelitis or orthopaedic implant-associated infections. Hybrid nuclear medicine imaging techniques are a suitable alternative to routine imaging modalities as they provide anatomical and functional information within one procedure. Our study investigated the performance of anti-granulocyte SPECT/CT using 99mTc-labelled monoclonal antibodies in the diagnosis of osteomyelitis and orthopaedic implant-associated infections. METHODS: In this retrospective analysis, we included patients with 99mTc-antigranulocyte SPECT/CT acquired in the context of a suspected bone and joint infection. All patients underwent routine diagnostics and/or had a clinical follow-up of at least 12months. RESULTS: 26 episodes were included. Fifteen exams were performed for suspected osteomyelitis, and 11 for suspected orthopaedic implant-associated infection. SPECT/CT was ordered most often if standard diagnostic tests or conventional imaging modalities remained inconclusive. The overall sensitivity and specificity for the diagnosis of an infection were 77.8% and 94.1%, respectively. The positive predictive value was 87.5% and the negative predictive value 88.9%. Diagnostic accuracy was 88.5%. CONCLUSIONS: 99mTc-antigranulocyte SPECT/CT imaging has a high accuracy in the diagnosis of osteomyelitis and orthopaedic implant-associated infections and is a suitable non-invasive diagnostic tool if standard diagnostic examinations are inconclusive or not applicable.

Drilling of bone: Effect of drill bit geometries on thermal osteonecrosis risk regions.

Bone-drilling operation necessitates an accurate and efficient surgical drill bit to minimize thermal damage to the bone. This article provides a methodology for predicting the bone temperature elevation during surgical bone drilling and to gain a better understanding on the influences of the point angle, helix angle and web thickness of the drill bit. The proposed approach utilized the normalized Cockroft-Latham damage criterion to predict material cracking in the drilling process. Drilling simulation software DEFORM-3D is used to approximate the bone temperature elevation corresponding to different drill bit geometries. To validate the simulation results, bone temperature elevations were evaluated by comparison with ex vivo bone-drilling process using bovine femurs. The computational results fit well with the ex vivo experiments with respect to different drill geometries. All the investigated drill bit geometries significantly affect bone temperature rise. It is discovered that the thermal osteonecrosis risk regions could be reduced with a point angle of 110° to 140°, a helix angle of 5° to 30° and a web thickness of 5% to 40%. The drilling simulation could accurately estimate the maximum bone temperature elevation for various surgical drill bit point angles, web thickness and helix angles. Looking into the future, this work will lead to the research and redesign of the optimum surgical drill bit to minimize thermal insult during bone-drilling surgeries.

Biomechanical comparisons of current suspensory fixation devices for anterior cruciate ligament reconstruction.

PURPOSE: Cortical suspensory devices are routinely used for femoral side fixation of soft tissue graft in anterior cruciate ligament (ACL) reconstruction. The purpose of this study was to evaluate the biomechanical properties of a new adjustable loop device (GraftMax®) compared with established devices (EndoButton® and TightRope®) in ACL reconstruction and to investigate whether knotting the free end of TightRope could improve biomechanical properties. METHODS: The three cortical suspensory devices (GraftMax® Button; Conmed, EndoButton® CL; Smith & Nephew, and TightRope® RT; Arthrex) were tested under cyclic load (50-250 N for 1000 cycles) and pull-to-failure conditions at 50 mm/h in a device-only setup using a tensile testing machine. The TightRope was additionally tested with its free suture ends knotted. The statistical analyses were done with one-way analysis of variance (ANOVA) and post hoc Tukey HSD tests. RESULTS: There are significant differences in the load-to-failure among the devices. The EndoButton showed the highest mean failure load at 1204.7 N compared to other devices (GraftMax (914.2 N), knotted TightRope (868.1 N) and TightRope (800.1 N) (p < 0.001). The mean total displacement after 1000 cycles was 0.76 mm, 2.11 mm, 1.56 mm and 1.38 mm for the EndoButton, GraftMax, TightRope, and knotted TightRope, respectively. The EndoButton showed significantly better properties than both the GraftMax (p = 0.000) and the TightRope (p = 0.020) but not the knotted TightRope (p = n.s.) in total displacement. However, there was no significant difference between the TightRope and GraftMax (p = n.s.). CONCLUSION: The fixed loop (EndoButton) showed significantly better mechanical properties in failure load and displacement than TightRope or GraftMax in this biomechanical study. However, the mechanical properties of the GraftMax is comparable to the TightRope. Moreover, the knotting of TightRope improved mechanical properties in total displacement more than TightRope, but not in failure load. CLINICAL RELEVANCE: The biomechanical properties of the GraftMax are comparable to the TightRope. The TightRope, when knotted, shows an improvement both in load to failure and cyclic displacement, though the differences are not significant.

How do Orthopaedic Devices Change After Their Initial FDA Premarket Approval?

BACKGROUND: The FDA approves novel, high-risk medical devices through the premarket approval (PMA) process based on clinical evidence supporting device safety and effectiveness. Devices subsequently may undergo postmarket modifications that are approved via one of several PMA supplement review tracks, usually without additional supporting clinical data. While orthopaedic devices cleared via the less rigorous 510(k) pathway have been studied previously, devices cleared through the PMA pathway and those receiving postmarket PMA supplements warrant further investigation. QUESTIONS/PURPOSES: We asked: What are (1) the types of original orthopaedic devices receiving FDA PMA approval, (2) the number and rate of postmarket device changes approved per device, (3) the types of PMA supplement review tracks used, (4) the types of device changes approved via the various review tracks, and (5) the number of device recalls and market withdrawals that have occurred for these devices? METHODS: All original PMA-approved orthopaedic devices between January 1982 and December 2014 were identified in the publically available FDA PMA database. The number of postmarket device changes approved, the PMA supplement review track used, the types of postmarket changes, and any FDA recalls for each device were assessed. RESULTS: Seventy original orthopaedic devices were approved via the FDA PMA pathway between 1982 and 2014. These devices included 34 peripheral joint implants or prostheses, 18 spinal implants or prostheses, and 18 other devices or materials. These devices underwent a median 6.5 postmarket changes during their lifespan or 1.0 changes per device-year (interquartile range, 0.4-1.9). The rate of new postmarket device changes approved per active device, increased from less than 0.5 device changes per year in 1983 to just fewer than three device changes per year in 2014, or an increase of 0.05 device changes per device per year in linear regression analysis (95% CI, 0.04-0.07). Among the 765 total postmarket changes, 172 (22%) altered device design or components. The majority of the design changes were reviewed via either the real-time review track (n = 98; 57%), intended for minor design changes, or the 180-day review track (n = 71; 41%), intended for major design changes. Finally, a total of 12 devices had FDA recalls at some point during their lifespan, two being for hip prostheses with high revision rates. CONCLUSIONS: Relatively few orthopaedic devices undergo the FDA PMA process before reaching the market. Orthopaedic surgeons should be aware that high-risk medical devices cleared via the FDA's PMA pathway do undergo considerable postmarket device modification after reaching the market, with potential for design "drift," ie, shifting away from the initially tested and approved device designs. CLINICAL RELEVANCE: As the ultimate end-users of these devices, orthopaedic surgeons should be aware that even among high-risk medical devices approved via the FDA's PMA pathway, considerable postmarket device modification occurs. Continued postmarket device monitoring will be essential to limit patient safety risks.

Accurate and early diagnosis of orthopedic device-related infection by microbial heat production and sonication.

Proper and rapid diagnosis of orthopedic device-related infection is important for successful treatment. Sonication has been shown to improve the diagnostic performance. We hypothesized that the combination of sonication with a novel method called microcalorimetry will further improve and accelerate the diagnosis of implant infection. We prospectively included 39 consecutive patients (mean age 59 years, 62% males) at our institution from whom 29 orthopedic prostheses and 10 osteosynthesis material were explanted. The explanted device was sonicated. The resulting sonication fluid was analyzed using microcalorimetry. Using standardized criteria to define orthopedic device-related infection, 12 cases (31%) were defined as infected. In all, positive periprosthetic tissue cultures were found. The sensitivity and specificity of microcalorimetry of sonication fluid were 100% and 97%, respectively. Mean time to detection, defined as time to reach a rising heat flow signal of 20 µW measured after equilibiration needed to get accurate measurement, was 10.9 h. In summary, microcalorimetry of sonication fluid is a reliable and a fast method in detecting the presence of microorganisms in orthopedic device-related infection.

Mobility aid-related accidents in children.

During the period 1991-2008, more than 63 000 children were examined in US emergency rooms following an accident related to a mobility aid: 40% of the children were less than 10 years old; 60% of the accidents occurred at home; and 4.4% of the children were hospitalised. Wheelchairs were the devices most often involved (67%), followed by crutches and walkers. Most accidents involving children under 10 years old were linked to a walker or wheelchair, and mainly resulted in head injuries. Most of the accidents in older children involved crutches and caused lower-limb sprains. In practice, the correct use of mobility aids should be explained to parents and children, and information given about the circumstances most likely to lead to accidents. Children using these devices should be supervised if necessary.

Audit of acute Charcot's disease in the UK: the CDUK study.

AIMS/HYPOTHESIS: We studied factors associated with the development and resolution of acute Charcot foot using a web-based observational study. METHODS: Clinicians managing cases of acute Charcot foot in the UK and Ireland between June 2005 and February 2007 were invited to register anonymised details on a secure website. RESULTS: A total of 288 cases (age 57.0 ± 11.3 years [mean ± SD]; 71.2% male) were registered from 76 centres. Of these, 36% of patients recalled an episode of relevant trauma in the preceding 6 months, while 12% had had surgery to the affected foot. In 101 (35%) cases, ulceration was present at registration and 20% of these had osteomyelitis. Non-removable off-loading devices were used at presentation in 35.4% of cases, with removable off-loading used in 50%. Data on resolution were available for 219 patients. The median time to resolution was 9 months in patients whose initial management included the use of non-removable off-loading, compared with 12 months in the remainder (p = 0.001). Bisphosphonates were administered intravenously in 25.4% and orally in 19.4% of cases. The median time to resolution in patients who received bisphosphonates was 12 months and was longer than in those who did not (10 months, p = 0.005). CONCLUSIONS/INTERPRETATION: The median time to resolution was longer than in earlier series. Although limited by being observational and non-randomised, these data suggest that the use of non-removable off-loading at presentation may shorten the time to resolution. They provide no evidence to indicate that the use of bisphosphonates is beneficial.

Occupational asthma related to low levels of airborne methylene diphenyl diisocyanate (MDI) in orthopedic casting work.

Orthopedic plaster casts contain methylene diphenyl diisocyanate (MDI). A few case reports have suggested occupational asthma to MDI in casting work. However, the knowledge of the exposure levels related to the occupational asthma cases is lacking. We report on two occupational asthma cases due to MDI in nurses irregularly applying orthopedic plaster casts, verified with placebo controlled specific inhalation challenge. The levels of MDI in the air were measured in the exposure chamber during the specific inhalation challenges with a quantitative method including filter collection and subsequent liquid chromatography-mass spectrometry (LC-MS) analysis of the isocyanate groups. In order to estimate the level of airborne MDI in casting work, measurements were conducted also in two hospitals during the application and removal of synthetic plaster casts using the same method. The concentrations were well below the occupational exposure limit in both specific inhalation challenge and hospital measurements. Based on our findings, even minor exposure to airborne MDI in casting work can cause an asthmatic reaction in some patients.

Value of 3D CT in defining skeletal complications of orthopedic hardware in the postoperative patient.

OBJECTIVE: Conventional CT of the postoperative patient with metal hardware is frequently limited by beam-hardening artifacts. With the evolution of 3D CT, CT is an increasingly effective means of examining the postsurgical patient for the integrity of their hardware and the course of their healing. CONCLUSION: Potential postsurgical complications such as nonunion, osteolysis, infection, and heterotopic ossification are all well assessed by 3D CT.

Frequency of instrument breakage during orthopaedic procedures and its effects on patients.

BACKGROUND: While breakage of an orthopaedic instrument is a relatively rare occurrence, orthopaedic surgeons need to be familiar with this complication and how to deal with it. Relatively little information about this subject has been published. METHODS: Every case of instrument breakage during orthopaedic procedures performed in two hospitals during a two-year period was documented prospectively. All patients were followed for a postoperative period ranging from twelve to thirty-six months, during which radiographs in two planes were made to assess changes in, or migration of, the broken object. RESULTS: During the observation period, 11,856 surgical procedures were performed in the two hospitals. The overall rate of instrument breakage was 0.35%. The broken piece was removed in five cases, and the broken instrument was left in situ in thirty-seven cases. During the follow-up period, none of the patients had any symptoms. CONCLUSIONS: In most cases, breakage of an orthopaedic instrument is not a problem. Any instance of instrument breakage should be fully documented in the surgical report.

Genitoperineal injuries associated with the use of an orthopedic table with a perineal posttraction.

BACKGROUND: Surgical treatment of lower extremity fractures commonly involves the use of orthopedic table with perineal post for countertraction. However, prolonged application of the perineal post has been associated with significant complications. We describe our experience in the management of genitoperineal cutaneous injuries associated with the use of a traction table. METHODS: Six patients with genitoperineal complications attributed to the use of a traction table were treated at our institution over a period of 2 years. The patient's median age was 25 (range, 20-28) years and all had fractures caused by motor vehicle collision. We evaluated the clinical presentation of these perineal injuries, operative time, therapeutic approach, clinical outcomes, and hospitalization time. RESULTS: The mean operative time of the orthopedic surgery was 318 minutes +/- 128 minutes (range, 185-540). All patients developed a partial-thickness necrotic area involving the perineum and scrotum in 2 days to 15 days (mean, 7 +/- 5.4) after the surgery. Three patients developed infection of the necrotic tissue. All patients underwent surgical debridement 16.5 days +/- 6.5 days (range, 13-29) after the orthopedic surgery and only one debridement procedure was necessary in all cases. A primary wound closure was possible in one case, and in the other cases the wound healed completely by second intention. The mean hospitalization time was 26.3 days +/- 9.7 days (range, 19-44). CONCLUSION: Genitoperineal skin necrosis induced by perineal traction posttable is a morbid complication that demands surgical debridement and prolonged hospitalization for your treatment. There are many procedures available to reduce the risk of this complication that should be used more liberally by the orthopedic surgeons.

Medical devices in orthopedic applications.

Orthopedic medical devices have been extremely successful in restoring mobility, reducing pain, and improving the quality of life for millions of individuals each year. Their success is reflected in the worldwide biomaterials market, in which orthopedic devices dominated sales at approximately $14 billion in 2002. Of this, approximately $12 billion was spent on joint replacements. In spite of their overwhelming benefits and successes, orthopedic medical devices are not without risk of adverse effects. Most adverse joint replacement outcomes are thought to be mediated by degradation products generated by wear and electrochemical corrosion. Infection and flaws in device manufacturing are other noteworthy causes of orthopedic device failure. This article illustrates and discusses the uses, general properties, and limitations (including adverse outcomes) of orthopedic biomaterials, which are fundamental to understanding requirements for improving current orthopedic medical devices.