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STORM – A Revolutionary Aid For Tibial Fracture Reduction
Authors: Mr Peter Hull (SpR), Ms Helen Whalley (SpR), Mr Charles Docker (Consultant) Worcestershire Acute Hospitals Trust, Worcester Royal Infirmary

Preoperative Warming: Helping Stop The Drop
Author: Dr JA Harper PhD, Business Analyst, Arizant UK



STORM – A Revolutionary Aid For Tibial Fracture Reduction
Authors: Mr Peter Hull (SpR), Ms Helen Whalley (SpR), Mr Charles Docker (Consultant) Worcestershire Acute Hospitals Trust, Worcester Royal Infirmary

Introduction
 Tibial fractures, including pilon and plateau fractures, are challenging injuries to treat. At present the main options for the management of these fractures are:
  1. Plaster cast
  2. Intramedullary nailing (if the fracture is extra-articular)
  3. Plating
  4. External fixation

For all the methods, the final aim is to attain an aligned, united tibia, with no complications and free joint motion above and below the fracture.

For the surgical management, prior to definitive fixation, it is necessary to align the fracture. Certain methods of fixation, aid the reduction intra-operatively, for example passing the nail in a simple tibial fracture, or lagging the fracture to a plate. The joints on an external fixator may also be used as a reduction aid.

However, prior to any fixation, the ideal aim is to have a fully aligned fracture that will stay aligned with ease, until the definitive fixation has been applied.

Many methods are available to help align the fracture, including manual reduction (requires a skilled assistant), a traction table, or some form of distractor. None of these methods address all of the components required to reduce and hold a fracture prior to, and during fixation, namely:
  1. Length
  2. Rotation
  3. Alignment
The Staffordshire Orthopaedic Reduction Machine (STORM) is a simple, but ingeniously developed device that helps reduce the fracture, and then holds it until the definitive method of fixation is applied. STORM is a re-usable device, with the only disposables (and hence cost after the initial purchase), being 2 K-wires, 2 unicortical screws and a drill bit.

Method of Application
 STORM is used in the operating theatre within the sterile field. Both legs are prepped to allow an intra-operative assessment of rotation.

Two 2mm k-wires are inserted, one in the proximal tibia / distal femur (see below) and one in the calcaneum; these are then tensioned onto the STORM frame. Through these two wires, controllable axial traction can be applied and malrotation corrected.

Figure 2a: Pre-operative radiograph



Figure 2b: Fracture with controlled axial traction applied by STORM (note that traction has not corrected the translation)
Finally, two or more uni-cortical screws are inserted into the tibia, one proximal, and one distal to the fracture. These are attached to translation arms which are then used to pull or push fracture fragments horizontally and vertically to fine-tune any remaining angulation or translation. An anatomically accurate reduction can then be achieved and held by STORM. The mechanics and configuration of the fracture can be assessed post-reduction and held in place while being fixed by a method considered to be most appropriate to the individual patient; intramedullary nail, percutaneous locking plate, external fixation, or a combination.

The device can be used to reduce fractures throughout the tibia, including pilon and plateau fractures, where it’s ability to help achieve and hold a good reduction is also useful for percutaneous screw, plate or fine-wire fixation. For plateau fractures the proximal tensioned STORM wire can be placed through the femoral condyles.

STORM is a very simple device to use, and takes approximately 15 minutes to apply. Once applied the fracture can typically be reduced and held within 20 minutes1. The definitive procedure should then be relatively simple, and the time taken reproducible, as the fracture is already reduced and held.

When nailing a tibial fracture, the anatomical reduction which is held throughout the procedure does away with the need for ‘pollar’ or bollard screws.

Theoretically STORM obviates the need for a surgical assistant, as it’s application is simple. The reduction is mechanical, and does not require any surgical force, and once reduced the fracture is held stable whilst the definitive procedure is performed.

Surgical Tips
 Always insist on using a radiolucent table, to enable ease of imaging intra-operatively.

For percutaneous plating from the medial side, place the translation screws and arms on the anterolateral tibial crest, to ensure there is a clear passage for the plate. STORM is particularly valuable when using locking plates, as these plates rely on perfect reduction, prior to their application, as the locking screws are unable to lag the bone to the plate.

For nailing, the proximal tibial wire is placed more posteriorly (although remembering the location of the lateral peroneal nerve posterior to the neck of the fibula), so as not to interfere with the nail insertion point.

When nailing, the uni-cortical screws need to be inserted away from the isthmus, to allow the reamer and nail to pass easily.

When using STORM to reduce a fracture prior to nailing, some form of bolster to rest the distal end of STORM against to keep the knee flexed, makes the nailing part of the procedure easier for any assistant.
Figure 2c: The fracture is then reduced using the unicortical screws, attached to the translation arms. Following this reduction, the axial traction was reduced, to close the fracture gap (note this fracture was treated definitively with an external fixator, hence the screws could be placed near the isthmus) Figure 3: STORM being using successfully to reduce a fracture prior to intramedullary nailing

Current limitations
 When nailing, the STORM device prevents flexion of the knee past 80 degrees due to it impinging on the back of the thigh (although this is not usually a problem).

STORM has been successfully used with complex frames (for example Ilizarov), however careful pre-operative planning is required to prevent STORM impeding the correct placement of pins / wires. It is possible to apply the translation arms after placement of any rings or Schantz screws in the tibia. Reduction is then completed before connecting components.

Conclusion
 STORM is a simple yet effective device for achieving and then holding anatomical tibial reduction relatively effortlessly, prior to definitive fixation. It is re-usable, and the only disposable kit for each procedure is a drill bit, 2 wires and 2 screws. Therefore, it is a cost effective device; both in terms of up front costs, and also by reducing theatre time1.

References
  1. Moorcroft CI, Ogrodnik PJ, Thomas PBM,Verborg SA. A Device for Improved Reduction of Tibial Fractures Treated with External Fixation. Proceedings of the Institute of Mechanical Engineers 2000; 214: 449-457.


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Preoperative Warming: Helping Stop The Drop
Author: Dr JA Harper PhD, Business Analyst, Arizant UK

Introduction
 Unplanned mild perioperative hypothermia is a common occurrence in surgery1 and is associated with increased rates of wound infection (SSIs)2, longer hospital stays3 and higher mortality rates4. Patients undergoing orthopaedic procedures are not immune to this risk. Although patients are routinely warmed during and after orthopaedic surgery, the benefits of preoperative warming are under-recognised. Here, we explain why stopping the temperature drop during orthopaedic surgery is important and how new active warming devices can help.

Mild perioperative hypothermia occurs when a patient’s core body temperature falls to between 34ºC and 36ºC. This can have profound effects, including adverse patient outcomes and significant healthcare costs5. Research has shown that during the first hour of anaesthesia alone, the core temperature of surgical patients can drop as much as 1.6ºC6. Any patient undergoing surgery can suffer perioperative hypothermia, but patients undergoing certain types of operations are at particular risk. A majority of hip and knee prosthesis operations undertaken in the UK between 2004 and 2006, for example, were performed on elderly patients, according to Government figures. These patients are at higher risk of hypothermia because they have relatively low metabolic heat production7,8,9. In addition, they are more likely to contract SSIs10,11, especially if they have an underlying illness12. Preoperative warming using new forced-air warming devices can provide real benefits to orthopaedic patients by preventing hypothermia from setting in before the patient arrives in the operating theatre.

Figure 1: Graph showing the typical pattern of temperature decrease during general anaesthesia
Causes of perioperative hypothermia
 Perioperative hypothermia occurs because anaesthetised patients cannot regulate their core body temperature. The body’s ideal thermic state is near 37.0ºC in the patient core, the body cavity encompassing the vital organs. Under normal circumstances, the central nervous system can maintain this core temperature within 0.2ºC above or below this ideal state6,13, with the peripheral tissues 2-4ºC cooler14. Unanaesthetised patients can maintain normothermia by behavioural changes, such as putting on a warm jumper. In addition, their hypothalamus maintains temperature within an acceptable range using information received from thermoreceptors located around the body. If the sensed temperature is outside the desired range, the hypothalamus initiates thermoregulation responses such as vasoconstriction and shivering15.

When a surgical patient undergoes general or major regional anaesthesia prior to surgery, however, these behavioural and physiological thermoregulation mechanisms are disrupted16,17. Patients under general anaesthesia cannot change their behaviour and are often administered muscle relaxants, which prevent shivering18. Furthermore, anaesthesia reduces the ability of the hypothalamus to regulate temperature so that core body temperature can drift up to 4ºC from normothermia17. The threshold at which vasoconstriction is triggered can be reduced below body temperature causing the arteriovenous shunts, which redistribute heat from the core to cooler peripheral tissue, to open. It has been shown that the induction of either general or regional anaesthesia can cause a drop in patient core temperature of 1.0ºC to 1.6ºC within the first hour, with 81 percent of this core temperature drop caused by heat redistribution6. After one hour, core temperature continues to fall, but more slowly. Three hours after general anaesthesia began, 65 percent of total heat loss is due to heat redistribution6. The remainder is environmental heat loss due to, for example, the exposure of a large body cavity during surgery and the infusion of cold fluids or blood products17,19. Patients undergoing regional anaesthesia experience similar disruption to their autonomic thermoregulation system. However, they are at greater risk of undetected hypothermia because nerve blocks cause thermoreceptors in the blocked area to read the temperature as abnormally high, causing the patient to feel warmer. In addition, temperature monitoring of patients under regional anaesthesia is less frequent20.

Consequences of perioperative hypothermia
 Perioperative hypothermia is associated with intra- and postoperative complications, which include increased blood loss and aggravated postoperative protein loss. However, one of the more serious complications of hypothermia is the heightened risk of contracting surgical site infections (SSIs)1. Mild hypothermia increases the risk of SSI contraction by impairing patients’ immunity and causing postoperative thermoregulatory vasoconstriction. Postoperative vasoconstriction reduces the ability of white blood cells to fight infections in the crucial first few hours after bacterial contamination of surgical wounds1,21. It also lowers oxygen availability in peripheral tissue, decreasing the production of oxygen and nitrosyl free radicals, which kill microbes22-24. Wound infection can prolong hospitalisation by 5-20 days25,26 and double hospital costs27.

In addition to SSIs, mild unplanned hypothermia can cause a range of other complications. Studies have shown that hypothermic patients, especially those undergoing procedures associated with considerable microvascular bleeding, lose significantly more blood perioperatively because hypothermia impairs the operation of clotting factor enzyme and platelets, reducing coagulation28-30. Furthermore, hypothermic patients take longer to recover from anaesthesia, increasing the likelihood that they will suffer associated complications because their colder body temperature can cause the effect of many drugs commonly used in surgery to last longer. For example, the duration of action of vecuronium, a nondepolarising muscle relaxant, increases from 29 minutes in a warm patient to 67 minutes in a patient with a body temperature of 34.3ºC. In addition, drugs used to reverse vecuronium, such as neostigmine, take 12 minutes longer to work in a hypothermic patient31.

Mild hypothermia lengthens postoperative recovery by aggravating protein breakdown32. One study found that a week after surgery, elderly patients left unwarmed during hip arthroplasty had lost more body cell mass than normothermic patients32. In addition, hypothermia-induced vasoconstriction after surgery does not just increase the risk of SSIs, but also lengthens postoperative wound healing time by impeding hydroxylation of proline and lysine residues, an oxygen-dependent process that cross-links collagen strands during scar tissue formation1,33,34. Along with shivering, which can increase oxygen consumption, postoperative vasoconstriction also makes cardiac disturbances after surgery more likely by increasing arterial blood pressure35. Patients who suffer morbid cardiac events spend, on average, 5.5 hours longer in intensive care35.

Figure 2: Patient adjusting controls of Bair Paws gown
Figure 3: Bair Paws gown and Bair Hugger unit in use during surgery
SSIs and orthopaedic surgery
 SSIs can be particularly problematic in orthopaedic surgery because there is a relatively high risk of joint space and deeper tissue infection following joint replacement procedures, particularly by drug-resistant bacteria. Since the Department of Health began mandatory monitoring of SSI occurrence in April 2004, the rate of SSI contraction following certain orthopaedic procedures, such as hip hemiarthroplasty, has remained above 3 percent, with 31.8 percent of these being deep or joint infections10. Furthermore, 30.5 percent of infections following knee prosthesis are deep or joint10. Treatment of these deep infections may require complete replacement of the artificial joint and extensive antibiotic treatment since the bacteria colonise the artificial joint surfaces causing premature loosening of the implant. After adhering to the joint surface, the bacteria develop a fibrous biofilm, making them more resistant to the patient’s immune response and antimicrobial therapy36.

Tackling perioperative hypothermia
 The clinical benefits of maintaining intraoperative normothermia during all types of surgery, including orthopaedic, are now widely recognised. There are several techniques for maintaining intraoperative normothermia including cotton blankets, thermal drapes, circulating water mattresses and infusing warm fluids. Of these, the most effective is forced-air warming37. Cotton blankets and thermal drapes are passive insulators, do not provide active warming and cool quickly, meaning that nurses have to spend time bringing new ones to patients. Circulating water mattresses are less effective than forced-air warming for many operations, including orthopaedic surgery, because heat is only transferred into the patient’s back38. Infusing warm fluids is not a stand-alone solution to hypothermia but can be used along with forced-air warming39.

Although using warm air to maintain patient normothermia in the operating theatre is common and has been growing in popularity for some time40, the advantages of warming the patient perioperatively, particularly preoperatively, are less well-known. However, this is changing. The NHS ‘Saving Lives’ campaign, which aims to reduce Healthcare Associated Infections (HCAI) including SSIs, has highlighted perioperative normothermia as a way of reducing infection rates41. As well as stopping patients feeling cold before surgery42, preoperative warming can prevent hypothermia in surgeries less than an hour in length. When combined with intra-operative warming, prewarming can prevent hypothermia in longer procedures. Preventing hypothermia is far easier and more effective than treating it, particularly intraoperatively. This is primarily because the amount of heat distributed from the body core to peripheral tissues can be quite large, and because vasoconstriction at the skin surface slows the transfer of applied heat19,43. By actively warming patients for 0.5 to 1 hour prior to anaesthesia, anaesthetically-induced vasodilation can be reduced37,44. In addition, heat redistribution can be prevented by ‘banking’ heat in peripheral tissue preventing a core-to-peripheral temperature gradient from developing, and keeping patients warm even after several hours of surgery45.

New warming technologies can now keep orthopaedic patients warmed throughout the surgical process. One such system is Arizant Healthcare’s Bair Paws® system, which incorporates forced-air warming into a surgical gown. The gown is perforated with small holes and, when attached to its warming unit, a steady stream of warm air is continuously blown through them. During surgery, the Bair Paws warming unit is disconnected and a more powerful Bair Hugger® warming unit is attached. Immediately after surgery, the Bair Paws warming unit is re-attached. This can be adjusted by the patient, once they regain consciousness, which means they can set a comfortable temperature. Patient discomfort is a lesser, but still important, consequence of perioperative hypothermia – some patients go so far as to rate the coldness that they experience before and after surgery as being worse than their surgical pain42. The Bair Paws surgical gown feels soft on the skin, protects patient modesty with wrap-around coverage and, crucially, is single-use. Various studies have shown that single-use of warming coverlets46 and use of forced-air warming systems do not increase SSI risk even if used during long surgical procedures47.

Preoperative warming is an important, but currently under-recognised, way to prevent unintended hypothermia. With the NHS’s Saving Lives campaign placing perioperative warming firmly on the surgical practice agenda, and new technologies now on the market, prewarming should form an integral part of orthopaedic practice.

References
  1. Kurz A, Sessler DI, et al Perioperative Normothermia to Reduce the Incidence of Surgical-Wound Infection and Shorten Hospitalization. New England Journal of Medicine. 334: 1209-1215; 1996.
  2. Barie, PS. Surgical Site Infections: Epidemiology and Prevention. Surgical Infections Supplement 3: 9 -21; 2002.
  3. Jeran L. Clinical Guideline for the Prevention of Unplanned Perioperative Hypothermia, American Society of PeriAnesthesia Nurses Development Panel. Journal of PeriAnesthesia Nursing. 16(5): 305 – 314; 2001.
  4. Tryba M, Leban J, et al. Does active warming of severely injured trauma patients influence perioperative morbidity? Anesthesiology. 85: A283; 1996.
  5. Sessler D.I. Mild perioperative hypothermia. The New England Journal of Medicine. 336: 1730 – 1737; 1997.
  6. Sessler D.I. Perioperative Heat Balance. Anesthesiology. 92:(2), 2000.
  7. Ayres U. Older people and hypothermia: The role of the anaesthetic nurse. British Journal of Nursing. 13: 396 – 403; 2004.
  8. El-Gamal N. et al. Age-related thermoregulatory differences in a warm operating room environment (approximately 26 degrees C). Anesthesia and Analgesia 90: 694 – 698; 2000.
  9. Morrison R.C. Hypothermia in the elderly. International Anesthesiology Clinics. 26(2): 124 - 133; 1988
  10. Health Protection Agency. Second Report of the Mandatory Surveillance of Surgical Site Infection in Orthopaedic Surgery: April 2004 to March 2006. London: Health Protection Agency, January 2007.
  11. Cruse P.J.E., Foord R. The epidemiology of wound infection. A 10- year prospective study of 62,939 wounds. Sur. Clin. North. Am. 60: 27 – 40; 1980.
  12. Ridgeway S. et al. Infection of the surgical site after arthoplasty of the hip. J. Bone Joint Surg. 87 (6): 844 – 850; 2005.
  13. Lopez M, Sessler D.I. et al. Rate and Gender Dependence of the Sweating, Vasoconstriction, and Shivering Thresholds in Humans. Anesth. 80: 780-788; 1994.
  14. Sessler. D.I. Temperature Monitoring. In: Miller R.D. ed. Anesthesia. 5th Edition. New York: Churchill Livingstone Inc. 2: 1367 - 1389; 2000.
  15. Guyton A.C., Hall J.E. Textbook of Medical Physiology. 10th Edition; 2000.
  16. Leslie K., Sessler D.I. Perioperative hypothermia in the high-risk surgical patient. Best Practice & Research. Clinical Anaesthesiology. 17: 485 – 498; 2003.
  17. Sessler D.I. Mild perioperative hypothermia. The New England Journal of Medicine. 336: 1730 – 1737; 1997.
  18. Arizant Healthcare Inc. Unintended Hypothermia: The Importance of Maintaining Normothermia, Workbook. Continuing Education; 2007.
  19. Sessler D.I. Complications and treatment of mild hypothermia. Anesthesiology. 95: 531 – 543; 2001.
  20. Shimosato S., Etsten B.E. The role of the venous system in cardio- circulatory dynamics during spinal and epidural anesthesia in man. Anesth. 30: 619 – 628; 30.
  21. Miles, A. et al The value and duration of defence reactions of the skin to the primary lodgement of bacteria’. British Journal of Experimental Pathology. 38: 79 – 96; 1957
  22. Van Oss C.J. et al. Effect of temperature on the chemotaxis, phago- cytic engulfment, digestion, and O2 consumption of human poly- morphonuclear leukocytes. J. Reticuloendoth. Soc. 27: 561-565; 1980.
  23. Leijh, P.C. et al. Kinetics of phagocytosis of Staphylococcus aureus and Escherichia coli by human granulocytes. Immunology. 37:453–465; 1979.
  24. Miles A.A. et al. The value and duration of defense reactions of the skin to the primary lodgement of bacteria. Br J Exp Pathol 38: 79; 1957.
  25. Bremmelgaard A. et al. Computer-aided surveillance of surgical in fections and identification of risk factors. J Hosp Infect. 13: 1-18; 1989.
  26. Haley R.W. et al. Identifying patients at high risk of surgical wound infection: a simple multivariate index of patient susceptibility and wound contamination. Am J Epidemiol 121: 206–15; 1985.
  27. Plowman R. et al. The rate and cost of hospital-acquired infections occurring in patients admitted to selected specialities of a district general hospital in England and the national burden imposed. J Hosp Infect 47 (3): 198 – 209.
  28. Michelson A.D. et al Reversible inhibition of human platelet activation by hypothermia in vivo and in vitro. Thrombosis and Haemostasis 71: 633 – 640; 1994.
  29. Rohrer M., Natale A. Effect of hypothermia on the coagulation casade. Critical Care Medical. 20: 1402 – 1405; 1992.30. Schmied H. et al Mild hypothermia increases blood loss and transfusion requirements during total hip arthroplasty. The Lancet 347 (8997): 289 – 292; 1996.
  30. Heier T. et al. Mild intraoperative hypothermia increases duration of action and spontaneous recovery of vecuronium blockage during nitrous oxide-isoflurane anaesthesia in humans. Anaesthesia. 74 (5): 815 – 819; 1991.
  31. Carli F. et al. Effect of perioperative normothermia on postoperative protein metabolism in elderly patients undergoing hip arthroplasty. British Journal of Anaesthesia. 63 (3): 276 – 282; 1989.
  32. Prockop D.J. et al. The biosynthesis of collagen and its disorders. New England Journal of Medicine. 301: 13-23; 1979.
  33. de Jong L., Kemp A. Stoichiometry and kinetics of the prolyl 4- hydroxylase partial reaction. Biochimica et Biophysica Acta. 787: 105–111; 1984.
  34. Frank S.M. et al Perioperative maintenance of normothermia reduces the incidence of morbid cardiac events. Journal of the American Medical Association. 277: 1127 – 1134; 1997.
  35. Gallo J. et al. Pathogenesis of prosthesis-related infection. Biomed papers 147 (1): 25 – 35; 2003.
  36. Sessler D.I. Consequences and treatment of perioperative hypothermia. Anaesthesiology Clinics of North America. 12 (3): 425 – 456; 1994.38. Kurz A. et al Forced-air warming maintains intraoperative normothermia better than circulating-water mattresses. Anaesthesia and Analgesia. 77 (1): 89 – 95; 1993.
  37. Mahoney C.B., Odom, J. Maintaining intraoperative normothermia: A meta-analysis of outcomes with costs. AANA Journal. 67 (2): 155- 164; 1999.
  38. Sigg D.C. The potential for increased risk of infection due to the reuse of convective air-warming/cooling coverlets. Acta Anaesthesiology Scandinavica 43: 173 – 176; 1999.
  39. NHS Saving Lives programme, High Impact Intervention No.3 http://www.dh.gov.uk/prod_consum_dh/groups/dh_digitalassets/@ dh/@en/documents/digitalasset/dh_4113474.pdf; 2006.
  40. Wagner D. et al. Effects of comfort warming on preoperative patients. Association of Operating Room Nurses. 84 (3): 427 – 447; 2006.
  41. Ereth M.H. et al Isolation of peripheral and central thermal compartments in vasoconstricted patients. Aviation, Space and Environmental Medicine. 63: 1065 – 1069; 1992.
  42. Mauermann W.J., Nemergut E.C. The Anesthesiologist’s Role in the Prevention of Surgical Site Infections. Anaesthesiology. 105 (2): 413 – 321; 2006.
  43. Sessler D.I. et al Optimal duration and temperature of prewarming. Anaesthesia. 82 (3): 674 – 681; 1995.
  44. Zink R.S. Convective warming therapy does not increase the risk of wound contamination in the operating room. Anesthesia and Analgesia. 76 (1): 54 – 62; 1993.
  45. Huang J.K.C. et al. The Bair Hugger patient warming system in prolonged vascular surgery: an infection risk? Critical Care. 7 (3): 13 -16; 2003.

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