Compression in Anklefracture Treatment, The CAT-study
Compression in Anklefracture Treatment, The CAT-study
The aim of this project is to find out if compression treatment can lower the incidens of
 surgical wound complications, such as infection and wound rupture, in patients with ankle
 fractures. The compression regime consists of a two-layered compression stocking applied
 after surgery and a massage boot applied both before and after surgery.

 The largest part of the study is the clinical trial, with which we aim to prove the
 hypothesis:

 * That the compression regime reduces wound infections from 10-40% to 5% on patients with a
 broken ankle (Either one side of the ankle, two or three sides (including the posterior part
 of the ankle))
Malleolar fractures

 Surgical treatment of patients with malleolar fractures imposes a special challenge for
 orthopaedic surgeons. A typical ankle fracture results in haematoma, sometimes blistering and
 almost always oedema formation. This postpones the optimal time for surgery. When operating
 on a swollen ankle, it becomes obvious for the surgeon that the tissue elasticity and normal
 structure is changed. This can complicate the surgical approach, procedure, the reduction of
 the fracture and the closure of the incision. Quite often the skin is difficult to adapt,
 resulting in excessive tension on the sutures. This can potentially lead to skin necrosis and
 wound dehiscence. Blood and fluid imbibed tissue and prolonged operating time, increases the
 risk of post-operative infection, and thereby give the patient painful and extended
 post-operative course.

 When striving to give the patient a good treatment and rehabilitation, it is paramount to
 prevent surgical complications.

 Compression therapy, as part of the standard treatment of ankle fractures, is not yet
 described in the literature and no previous study has tested its efficiency in this patient
 group, in a systematic manner. It is a new, innovative way of helping the patients to faster
 rehabilitation and to prevent surgical soft tissue complications.

 If this study proves the expected effect on soft tissue complications, compression therapy
 will probably also show an effect on other fracture types: knee-, wrist-, tibia- and femoral
 fractures, making compression therapy an integrated part of the standard fracture regime in
 all orthopaedic departments.

 Malleolar fractures in Denmark has an incidence of 107/100.000 person, making it one of the
 most common fracture types in the country. In Denmark 6000 malleolar fractures are operated
 each year.

 Studies have shown increased complication rates in the elderly, diabetics, smokers, patients
 on immunomodulating medication, alcoholics, and patients with osteoporosis and peripheral
 neuropathy.

 Treatment of malleolar fractures in Denmark shows great local variations, and standard
 differs between hospitals, often with a low grade of clinical evidence.

 Nordsjællands Hospital has decided, to implement a standard regime of Flowtron Hydroven 3™
 and Coban™ 2 lite, to prevent oedema formation and blistering. The decision came after
 clinicians having observed a high incidence of oedema, blistering and wound healing problems
 in this cohort of patients, often forcing surgeons to postpone surgery and prolonging
 inpatient stay, resulting in a long and cumbersome rehabilitation for the patient.

 Intermittent pneumatic compression

 Intermittent pneumatic compression (IPC) is used mainly in prevention of DVT. The use of IPC
 in treatment of postoperative soft tissue care is only sporadically mentioned in the
 literature. These studies define the mechanisms of action as either mechanical or chemical.
 The mechanical effect is due to improved vascularity, redirection of blood flow and cyclic
 loading. The chemical effect is caused by increased production of nitric oxide (NO),
 producing vasodilation and the increase of inflammatory mediators, promoting heeling by
 stimulating proliferation of fibroblasts and endothelial cells. Some studies have
 investigated the effect of IPC on the vascularity of bone and soft tissue (animal studies),
 fracture related oedema and oedema related to venous disease and other medical conditions,
 showing a convincing effect on all. Accumulating data from experimental animal studies
 suggest that the use of IPC increases neurovascular ingrowth, the amount of newly organized
 parallel collagen fibres, fibroblast proliferation and proliferative repair. Further IPC
 counteract the negative influence immobilization has on tissue repair. Therefore,
 theoretically one should expect that application of an IPC unit on a newly operated and
 immobilized patients ankle, would prevent oedema formation, speed up tissue regeneration and
 enhance arterial blood flow thereby preventing wound healing problems defined as infection,
 wound dehiscence, prolonged healing, skin necrosis, exposed hardware, and maybe also
 accelerate bone heeling.

 COBAN 2 lite

 Coban™ 2 lite is a compression bandage consisting of an inner comfort layer and an outer
 stretch layer, designed to deliver therapeutic compression for the treatment of venous leg
 ulcers and related conditions. The bandage is purposed for patients less tolerant of
 compression, with mixed aetiology and a ABPI (ankle brachial pressure index) ≥ 0,5. Correctly
 applied, the bandage take the form of a solid tube which reduces slippage and let the patient
 wear it for up to several weeks without the need of re-application. The use of compression
 stockings and bandages are well described in literature, and an integrated part of the
 management of oedema end venous ulcers, but not addressed when it comes to fracture
 treatment.

 Adverse effects

 Intermittent pneumatic compression The IPC device is routinely employed in prevention of deep
 venous thromboembolism (DVT) and subsequently pulmonary embolism (PE) and in the management
 of lymfoedema. It is considered a safe and efficient alternative to medical
 thromboprophylaxis and only few adverse effects have been described in literature, all
 consisting of case reports.

 When using IPC as DVT prophylaxis it is often applied during surgery and with the patient in
 general anaesthesia, hindering the patient in reporting any discomfort. One author describes
 a case, where application of IPC on a patient with cancer associated thrombosis and embolism,
 results in a pulmonary embolism. The patient did not show signs of having a DVT prior to
 surgery, and the author concludes that the PE might have taken place regardless of the
 application of IPC devices.

 Two case reports describes peroneal nerve palsy as a possible adverse effect to IPC. The
 first case concerns a woman with pancreatic cancer and weight loss, who develops peroneal
 nerve palsy bilaterally under surgery, probably because there is no subcutaneous fat to
 protect the nerve against the applied pressure between the fibular head and the compression
 boot. The second case concerns an obese patient undergoing 10 hours intracranial surgery.

 One author reports a case where an older woman with postoperative delirium and fragile skin
 develops hemorrhagic bullae under the IPC-device. This could probably have been avoided, had
 the patient not ben delirious an inept of reporting discomfort.

 Some authors have tried to associate the IPS unit to compartment syndrome, but the cases have
 all been on patients whom have undergone prolonged operation in the lithotomy state, which is
 known to increase the risk for compartment syndrome in the lower leg.

 Malfunctioning of the equipment is described in literature, but is rare. The IPC-device can
 cause warmth and sweating under the inflatable textile and discomfort if it is placed
 incorrectly or directly on top of a suture.

 Compression bandage

 There are no descriptions in literature of major side effects to the compression bandage.
 During the early implementation of compression treatment of malleolar fracture at the unit of
 Orthopaedic Surgery, Nordsjællands Hospital, pressure-wounds have been observed, and in one
 case with a visible Achilles tendon. Several minor pressure wounds have been noted, but these
 have all successfully healed under conservative treatment.

 The Coban™ 2 lite can cause discomfort such as tightness, if applied to firmly. The inner
 comfortlayer can chafe bony prominences or tendons if applied to thick.

 Precautionary measures

 In order to prevent any side effects or discomfort, the project manager routinely and
 frequently examines all patients included in the trial. This will take place both in the
 Emergency Department, at the bedward 48-72 hours after admission, and postoperatively.

 The staff will receive ongoing training in the application and observation of both Coban™ 2
 lite and the Flowtron Hydroven 3™, in order to prevent any malfunctioning or misapplication.

 Hypotheses and Aims

 Hypotheses

 Study1 - That the compression regime reduces wound infections from 10-40% to 5% on patients
 with mono-, bi-, and trimalleolar fractures treated according to the ORIF-principles (open
 reduction internal fixation)

 Study 2

 - That the retrospective study will establish the historical incidence of infections, before
 the compression regime was implemented.

 Study 3 - That a systematic literature review will reveal the extent of infection and provide
 the author with knowledge of regimes described in international literature, aiming at
 lowering the incidence of infections.

 Aims

 Study 1

 -  To perform a prospective, un-blinded, controlled cohort study, to evaluate the effect of
 Flowtron Hydroven3™ and Coban2 lite™ on the incidence of complications (infection, wound
 dehiscence, prolonged healing, skin necrosis, exposed hardware, DVT, amputation and
 death) after operation for mono-, bi- and trimalleolar fractures at Nordsjællands
 Hospital.

 -  Study 2

 To perform a retrospective evaluation of the treatment for mono-, bi- and trimalleolar
 fractures, at Nordsjællands Hospital, Department of Orthopaedic Surgery, before the current
 compression management was implemented, focusing on the following parameters:

 A) Pre-operative compression/deflating management (elevation, Flowtron Hydroven™), prevalence
 of oedema, blistering, smoking, diabetes, co-morbidity, age and sex)

 B) Per-operative parameter: administration of antibiotics.

 C) Postoperative compression/deflation management (elevation, Flowtron Hydroven™ og Coban2
 lite™ ), oedema, blistering, infection, wound dehiscence, prolonged healing, skin necrosis,
 exposed hardware, DVT, amputation and death.

 - Study 3 To perform a literature study, enabling the author to describe, and establish the
 incidence of surgical complications for mono-, bi- and trimalleolar fractures, resulting in a
 review article.

 Project Plan

 The study is divided into 3 phases:

 Sub study 1: A prospective, mono-centre, randomized, controlled, non-blinded, cohort study,
 with a postoperatively follow-up period of 6 weeks.

 Sub study 2: A retrospective, mono-centre, cohort study based on patient files, with
 follow-up period of 6 weeks from the day of operation.

 Sub study 3: A literature study.

 Study period

 Sub study 1: 1.11.2013 - 5.12.2015 Sub study 2: 1.10.2013 - 1.5.2015 Sub study 3: 1.10.2013 -
 1.10.2014

 Study population

 -  Sub study 1: Each year approximately 170 patients are operated on for mono-, bi- and
 trimalleolar fractures. According to the power calculation (2x78)= 156 patients needs to
 be included in the study group. The inclusion period will run for 24 months, or till 156
 patients are included.

 -  Sub study 2: All patients operated for mono-, bi- and trimalleolar fractures, in a 12
 months period (1/1/2009-31/12/2009) before implementing the compression treatment
 consisting of Flowtron Hydroven™ and Coban2 lite™ the unit of Orthopaedic surgery,
 Nordsjællands Hospital.

 -  Sub study 3: Literature search on PubMed, on patients with ankle fractures, operated
 according to ORIF. Search words: ankle fracture/malleolar fracture, ORIF, complications,
 infections, wound dehiscence, necrosis and amputation.

 Language: English.

 Data sources:

 InfoView:

 A datawarehouse database containing CPR-numbers coupled to SKS-codes (Sundhedsvæsenets
 Klassifikations System, diagnosis codes). All patient contact to the Emergency Department,
 Out Patient Clinic and bed wards are recorded here.

 OPUS:

 IT-system containing the patient files necessary to perform sub study 2.

 Centricity:

 IT-system containing x-rays. Will be used to identify and classify ankle fractures on the
 patients whose data are found via InfoView.

 Labka:

 A system contained in OPUS, where blood sample-results are kept.

 Orbit:

 IT-system doctors use to book patients for surgical procedures, used to find all surgical
 procedures for a given code, a given year.

 PubMed:

 Database accessing primarily the Medline database of references and abstracts on life
 sciences and biomedical topics.

 Procordo

 Randomization, stratification, visualization of data, and data storage will be managed using
 an IT system called Procordo (Procordo ApS Rugaardsvej 5 DK-8680 Ry Denmark).

 Study procedures

 Study design:

 Sub study 1: Patients are included in the Emergency Department (red) by the doctor on duty or
 the project manager, if they are willing to participate and have given consent after written
 and oral information about the study. As part of the standard treatment, X-rays are taken to
 confirm the diagnosis. The fracture will be evaluated for the need of surgery, according to
 the department standard:

 1. Unstable fractures (SU3+4, SA2, PA2+3, PU2+3+4). Particularly SU-fractures are important
 to examine closely, in order to rule out ligamentous damage on the medial malleolar.

 2. Dislocated fractures in the lateral malleolus, with maximum diastases of 2 mm.

 3. Fracture of the medial malleolus.

 Standard blood tests will be carried out, if deemed necessary, and the affected ankle will be
 treated with a splint, according to the Emergency Department's standard procedures. The
 patient will hereafter get randomized. Randomization, stratification, visualization of data,
 and data storage will be managed using an IT system called Procordo (Procordo ApS Rugaardsvej
 5 DK-8680 Ry Denmark). Patients will be block randomized into blocks of 6-10. This size is
 chosen because of the stratification according to two variables, to make sure that an equal
 distribution of stratae is obtained each block. Block size is blinded for the researcher. The
 system will use a sequence of 300, and patients will be stratified according to diabetes,
 smoking and need for closed reduction. The patient will be on-line randomized in the
 emergency department, as close to the actual treatment as possible, in order to prevent
 superfluous drop-out. Randomization is handled by either a doctor or a nurse using a computer
 interface designed by Procordo. The person to include will open the computer, use the
 shortcut symbol to the randomization interface, type the user name and code accessible to the
 personnel in the emergency department. A sign with username and code will be hanging next to
 the computer. The user will be asked to identify him/herself by name, and to type several
 patient specific parameters: sex, CPR-number, fracture type, diabetes, smoking and others.
 The computer will search in the 300-sequence and come up with the next available number
 (either 1 or 2) to allocate the patient. The sequence is designed according to block-size,
 p-value (0,5 or 0,5) and the total number of 300. The allocation process itself is hidden
 from the investigator, and at no point in the process, will the system reveal if the patient
 is in the treatment- or the control-arm. This makes it possible to blind the treatment later
 on, when the patient visit the out-patient clinic. In theory the randomization interface is
 accessible to all personnel in the emergency department, which is why every inclusion will be
 checked by the project manager.

 To avert confounding treatments, a sign will be put on the patient bed during
 hospitalization, communicating which group the patient belongs to.

 The project manager will control that the intervention/non-intervention is applied according
 to the study protocol. This is done by continuous visits to the bed ward, examining the
 patients to see if the Coban2 lite™, Flowtron Hydroven™ and Braun frame are correctly used.

 The Intervention group (pink): Will receive compression therapy in the form of a Flowtron
 Hydroven™, 40-60 mmHg, ¾-1 hour, 3 times a day, when diagnosed and allocated in the emergency
 department, either on top of the splint, or if no splint is administered, on top of the
 dressing. This treatment will be continued, until the patient is fit for surgery according to
 clinical priority and theatre availability. The surgical procedure will follow the standards
 of the Department of Orthopaedic Surgery.

 After finished surgery, the doctor or nurse in the operating room (OR) will apply a dry,
 non-adherent, wound dressing (Vliwasorb® Lohmann & Rauscher, Gøngehusvej 252, DK-2950 Vedbæk,
 Denmark) and Coban2 lite™. The patient will continue the Flowtron Hydroven™ treatment in the
 bed ward (40-60 mmHg, ¾-1 hour 3 times a day) on top of the Coban2 lite™ bandage, until
 discharge.

 Before discharge the patient is fitted with a Walker boot, unless there is bad compliance or
 no pulse in arteria dorsalis pedis or tibialis anterior, in which case a CobraCast walking
 bandage is applied. Both boot and bandage is applied at the bed ward, when the patient has
 recovered from anaesthesia/analgesia, and worn during fysiotherapy and mobilization.
 Observation and control of both Flowtron Hydroven™ and Coban2 lite™ in the ward are carried
 out by the nurses with special training, according to standard procedures, and by the project
 manager who will collect data between 48-72 hours after admission. On the day of discharge,
 the Coban2 lite™ is removed, the wound dressing changed and a new Coban2 lite™ is re-applied.
 According to standard treatment, x-rays are taken after 2 and 6 weeks, and the patient is
 seen in the outpatient clinic accordingly. At both visits, clinical photos will be taken of
 the surgical wound, in order to blind the clinical evaluation. Two senior doctors will later
 be asked to evaluate the photos and determine if infection or wound dehiscence is present. At
 the 2 weeks visit the Coban2 lite™ and stitches are removed, and a compression stocking is
 fitted. The project manager will note any wound healing problems (infection, wound
 dehiscence, skin necrosis, visible osteosynthesis material).

 The Walker boot or CobraCast walking splint is re-applied. At the 6 weeks visit, x-rays will
 be taken, and again the project manager will note any wound healing problems (infection,
 wound dehiscence, skin necrosis, visible osteosynthesis material). If all parameters are
 acceptable, the patient course, and follow up is concluded.

 The control group: In the Emergency Department the affected leg will be elevated on a Braun
 Frame, and this treatment will continue in the bed ward, until the patient is fit for surgery
 according to clinical priority and theatre availability.

 The surgical procedure will follow the standards of the Department of Orthopaedic Surgery.

 After surgery, a Vliwasorb® wound dressing and TubiGrip™ bandage (Mölnlycke Health Care ApS,
 Gydevang 33, DK-3450 Allerød, Denmark) is applied. Finally the ankle is stabilized in a
 Walker boot, unless there is bad compliance or no pulse in arteria dorsalis pedis or tibialis
 anterior, in which case a CobraCast walking bandage is applied. Both boot and bandage is
 applied at the bed ward, when the patient has recovered from anaesthesia/analgesia, and worn
 during fysiotherapy and mobilization. According to standard treatment, x-rays are taken after
 2 and 6 weeks, and the patient is seen in the outpatient clinic accordingly. At both visits,
 clinical photos will be taken of the surgical wound, in order to blind the clinical
 evaluation. Two senior doctors will be asked to evaluate the photos and determine if
 infection or wound dehiscence is present. At the 2 weeks visit, the TubiGrip™ and stitches
 are removed. The project manager will note any wound healing problems (infection, wound
 dehiscence, skin necrosis, visible osteosynthesis material), and the TubiGrip™ and Walker
 boot are re-applied. At the 6 weeks visit, X-rays will be taken, and again the project
 manager will note any wound healing problems (infection, wound dehiscence, skin necrosis,
 visible osteosynthesis material). If all parameters are acceptable, the patient course, and
 follow up is concluded.

 Sub study 2: All treatments in this study have been closed, at the time of data collection.
 So the project will have no influence on the course of the patients.

 Material:

 Sub study 1: Each year approximately 170 malleolar fractures are operated on at Nordsjællands
 Hospital. Of these 78 are realistically to be included into the project, and studied
 according to the study variables outlined below. The inclusion period runs for 24 months or
 till (2x78) = 156 patients are included, and start 1/10/2013.

 Sub study 2: The 1/10/2013 the retrospective cohort study begins. 78 patient files will be
 studied according to the study variables outlined below. The patient files must be dated from
 before the department of orthopaedic surgery implemented the use of compression therapy as a
 routine treatment for ankle fractures.

 5 Study variables Applies to both, the intervention and control group.

 Pre-operative data

 -  CPR-number

 -  Age

 -  Sex

 -  Smoking at the time of admission (yes/no) (stratification variable)

 -  Diabetes (yes/no) (stratification variable)

 -  Alcohol consumption (<1 unit/week, 2-7/14 units/week, >7/14 units/week)

 -  Need for closed reduction (yes/no) (stratification variable)

 -  Palpable pulse in foot

 -  Application of Flowtron Hydroven3 (yes/no) (only intervention group)

 -  Elevation of on Braun Frame (yes/no) (only control group)

 -  Fracture date

 Per-operative data

 -  Administration of antibiotics (yes/no)

 -  Duration of surgery (in minutes)

 -  Skin blisters of effected leg (pale, red or black. The presence of only one blister from
 the knee and down results in a positive answer)

 -  Application of Coban2 Lite after surgery (yes/no) (only intervention group)

 -  Surgeon's level of training (reservelæge/1. reservelæge/afdelingslæge/overlæge)

 -  Time from admission (Emergency Department) to surgery (in hours)

 -  Fracture type (Lauge Hansen)

 Post-operative data during hospitalization, collected 48-72 hours after surgery

 -  Application of Flowtron Hydroven3 (yes/no) (only intervention group)

 -  Elevation of on Braun Frame (yes/no) (only control group)

 -  Death (yes/no)

 -  Adverse effects (pressure soars (type I-IV), peroneal nerve palsy, DVT, pulmonary
 embolism

 -  Administration of anticoagulants

 -  Support on operated leg (yes/no)

 Post-operative data collected at the 1st visit to the outpatient clinic, 2 weeks after
 surgery.

 -  Date for visit

 -  Infection (fever, swelling, pain, redness, secretion, need for antibiotics)

 -  Wound dehiscence (partial or complete rupture of the layers in the wound).

 -  Skin necrosis (wound edges with pale, black or otherwise non-vital skin)

 -  Visible osteosynthesis material (no/minor/major)

 -  Day of discharge (hours after surgery)

 -  Deep venous thrombosis (confirmed by ultrasound)

 -  Time from surgery to discharge

 -  Surgery date

 -  X-ray acceptable (yes/no)

 -  Re-admission (yes/no) Cause

 -  Clinical photos are taken of the surgical wound

 Post-operative data collected at the 2nd visit to the outpatient clinic, 6 weeks after
 surgery.

 -  Date for visit

 -  Infection (fever, swelling, pain, redness, secretion, need for antibiotics)

 -  Wound dehiscence (partial or complete rupture of the layers in the wound).

 -  Skin necrosis (wound edges with pale, black or otherwise non-vital skin)

 -  Visible osteosynthesis material (no/minor/major)

 -  X-ray acceptable (yes/no)

 -  Surgery date

 -  Re-admission (yes/no) Cause

 -  Deep venous thrombosis (confirmed by ultrasound)

 -  Amputation (yes/no)

 -  Death (yes/no)

 -  Clinical photos are taken of the surgical wound

 Primary outcome: Infection.

 Secondary outcomes: Wound dehiscence, skin necrosis, visible osteosynthesis material,
 blisters, DVT, amputation, death.

 Screening-log:

 During the study a screening-log will be kept. All patients who are potential candidates to
 randomization will be entered into the log.

 Ethical considerations

 The National Committee on Health Research Ethics:

 An application has been forwarded to the Regional Committee on Health Research Ethics, dated
 7/12/2012. Application number: 36522

 The Danish Data Protection Agency: journal no. 2012-41-1331. Exempted from reporting on the
 5th December 2012, as private medical research projects, which must be reported to the
 National Committee on Health Research Ethics, are no longer required to report to the Danish
 Data Protection Agency. The project manager is registered as private responsible for the data
 (Danish: privat dataansvarlig) and undertakes to ensure that the applicable personal data
 laws for medical research projects are followed by the research group.

 Danish Health and Medicines Authority, Pharmacovigilance and Medical Devices Case no.
 2012113737. The study is assessed not to require notification according to the regulations
 for medical equipment § 9, part 1 and therefore does not require reporting to the National
 Board of Health or the Danish Health and Medicines Authority, Pharmacovigilance and Medical
 Devices.

 Informed consent:

 A decision to participate in the research project will be obtained from all patients
 participating in the study. The decision is made upon due information on the nature,
 significance, implications and risks of the project and upon receipt of suitable written
 documentation. It is made voluntarily by a person who is capable of giving his or her
 consent. The consent shall be in writing, dated and signed, and is obtained in the Emergency
 Department (ED) The patient will be recruited in the ED as soon as the inclusion diagnosis is
 made. The initial contact and inclusion will be handled by the doctor on duty or the project
 manager. He or she will provide the above-mentioned written and oral information. The
 patients in the ED are examined in small booths, separated by curtains. This provides the
 necessary privacy to perform a physical examination, but preventing other patients from
 overhearing conversation can be difficult. Therefor the patient should be offered the
 possibility to continue the conversation in a quiet interview room. The patient is offered to
 have an assessor participate in the conversation. All patients must be offered due
 reconsideration time before making up their minds, this means enough time to talk to the
 assessor or make a phone call. For practical reasons though, it will be difficult to offer
 more than 60 minutes reconsideration time, due to the urgent nature of the trauma and the
 urgent need for surgery. Furthermore the Flowtron Hydroven™ need to be applied relatively
 quickly after the patient has been diagnosed with the ankle fracture, in order to obtain the
 best effect. The nature of the intervention is considered non-invasive and with few adverse
 effect, justifying the relatively short reconsideration time. The Informed consent form must
 be signed before the patient leaves the ED and the patient can at any time decide to withdraw
 from the project, without consequence to further treatment.

 Good Clinical Practice The local GCP-committee (GCP region Hovedstaden) has been contacted
 and report that the study is exempted from reporting to the GCP.

 Confidentiality:

 All personnel involved in the project are bound by professional confidentiality regarding all
 private data.

 The Danish law on "behandling af personoplysninger" (LOV nr. 429 af 31/05/2000) will be
 adhered to.

 Statistics Data will be analysed in collaboration with statistician Tobias Wirenfeldt
 Klausen. Data will be collected and partially analysed using SPSS (Statistical Product and
 Service Solutions, 21, IBM)

 Based on literature, which shows a complication rate between 10% and 40%, P1 (representing
 the expected complication rate in the control group), is set to 20% and P2 representing the
 expected complication rate in the intervention group) to 5%. Using Lehr's formula for
 calculating a power of 80% and a two-sided significance level at 0,05. The required sample
 size in each group = 16/(Standard difference)2

 Standard difference= 0,454

 (calcualtion details to obtain "standard difference" are difficult to show, due to
 formatting)

 Using the Quick formula:

 If the power is 80%, the required sample size in each group is:

 16/Standard difference= 16/0,454= 77,6 = 78 patients in each group.

 Material and Methods

 The (IPC)-unit used in this study is a Flowtron Hydroven 3™ (ArjoHuntleigh A/S Vassingerødvej
 52 DK-3540 Lynge). It consists of an inflatable textile-boot connected to a pump providing an
 intermittent pressure between 30-60mmHg.

 The compression bandage used in this study is Coban2 lite™ (3M a/s Hannemans Allé 53, 2300
 KBH S, Denmark). It consists of an inner comfort layer and an outer stretch layer, designed
 to give a resting pressure of more than 40mmHg. On standing it will produce a pressure of
 more than 60mmHg which is the level accepted as the pressure required to counteract venous
 hydrostatic pressure in the lower leg.
Inclusion Criteria:

 -  All patients operated on Nordsjællands Hospital, department of Orthopaedic surgery,
 during the inclusion period, for mono-, bi- and trimalleolar fracture, according to
 the AO-principles.

 -  Age above 18 years.

 Exclusion Criteria:

 Sub study 1:

 -  Age under 18

 -  Dementia

 -  Need for external fixation

 -  Known or suspected DVT or pulmonary embolism

 -  Patients without Danish CPR-number, or address in Denmark

 -  Patients who doesn´t want to participate or who are not able to give written or oral
 consent

 -  No palpable pulse in the foot in the affected leg (the posterior tibial,- or dorsal
 artery)

 -  Multi-traumatized patients and patients with fractures of more than one extremity

 Sub study 2:

 -  Age under 18

 -  Dementia

 -  Need for external fixation

 -  Multi-traumatized patients and patients with fractures of more than one extremity