12 January 2007

Ossur Scientific E-letter Issue #1 2007

Dear readers,

This E-letter includes nine different scientific papers. The articles cover the subjects of amputation, rehabilitation, prosthetics/biomechanics, orthotics/biomechanics, bionics and quality management.

Six of the selected papers have been published in 2006, one 2005 and one 2004. One will be published in 2007.

 

Amputation

Anthony T. Roberts J. Modrall J G. Huerta S. Asolati M. Neufeld J. Parker B. Yang W. Sarosi G.

Transmetatarsal amputation: assessment of current selection criteria

The American Journal of Surgery Volume 192, Issue 5, November 2006, Pages 8-11

Anthony and colleagues assessed the validity of current selection criteria for transmetatarsal amputations. The selection is based on the degree of tissue loss/infection, tissue perfusion, current ambulatory status and an estimation of the ambulation after an amputation.

To validate the criteria a retrospective study was performed including 52 transmetatarsal amputations. Information was collected regarding patient demographics, comorbitity, surgical variables, rate of reamputation and post-op ambulatory status.

The study group found that vascular insufficiency or infection were the primary indication for transmetatarsal amputation in 96% of the patients. The majority of the patients were diabetics (89%). After undergoing the first transmetatarsal amputation 85 additional operations were required, only nine patients (18%) had a single operation. More proximal amputation was required in 56% of the patients resulting in symes-(-14%), transtibial-(69%) and transfemoral –amputations (17%). It was found that non-insulin diabetics were associated with an increased risk of revision to a more proximal level of amputation. The rate of the ambulatory ability at the last follow-up was 74% (83% of the transmetatarsal amputated and 67% of the more proximal amputations). The likelihood of ambulation was significant decreased in those who had undergone previous vascular procedures.

Anthony and colleagues concluded that current selection criteria for transmetatarsal amputation may be inadequate. The conclusion was based on the fact that multiple operations should be expected in the majority of the transmetatarsal amputated patients, although the majority of the patients retain ambulatory.

Dosluoglu H H. O’Brien M S. Lukan J. Harris M D. Dryjski M L. Cherr G S

Does preferential use of endovascular interventions by vascular surgeons improve limb salvage, control of symptoms, and survival of patients with critical limb ischemia?

The American Journal of Surgery. Volume 192, Issue 5 , November 2006, Pages 572-576

Dosluogu et al evaluated the impact of the effects of the endovascular interventions compared to open surgery in patients with critical limb ischemia

A total of 275 consecutive patients (301 limbs), who underwent revascularization or primary major amputation, were treated and compared in three different periods;

Group I (pre-endovascular era). June 1, 2001 to October 31, 2002 (17 months).
Group II November 1, 2002 to October 31m, 2003 (12 months), transition period with increasing endovascular treatment and decreasing open procedures.
Group III (post-endovascular era). November 1, 2003 to June 30, 2005.

The study showed that the rate of primary major amputation decreased from 14.8% to 10.5% and to 3.5%. The overall 24-month limb salvage increased from 60% to 69% and to 85% and an increase was also found following a limb salvage attempt (71%, 77% and 88%. Length of stay decreased from 10.7 to 5.2 days. During the study period no difference in survival were observed. The authors concluded that endovascular interventions in patients with critical limb ischemia decreased the amount of primary major amputations, improved the limb salvage and decreased the length of hospitalisation, without a difference in survival. 
 

Rehabilitation

Franchignoni F. Orlandini D. Ferriero G. Moscato T A

Reliability, validity, and responsiveness of the locomotor capabilities index in adults with lower-limb amputation undergoing prosthetic training

Archives of Physical Medicine and Rehabilitation. Volume 85, Issue 5, May 2004, Pages 743-748

Franchignoni and his study group wanted to assess the reliability, validity and responsiveness of the standard Locomotor Capabilities Index (LCI) and the revised Locomotor Capabilities Index (LCI-5) in people with lower limb amputation, who went through prosthetic training.

LCI is an instrument to monitor the impact of therapeutic interventions. It assesses the patient’s perceived capability to perform different locomotor activities. The activities scored on a 4-level ordinal scale in LCI and a 5-level ordinal scale in LCI-5. Previous tests of LCI have shown good results except a high ceiling effect. The new LCI-5 was devised to improve the instrument’s ability to discriminate between patients and decrease the ceiling effect.

The study included 50 inpatients with a unilateral lower limb amputation. LCI and LCI-5 were analyzed for test-retest reliability, internal consistency, ceiling effect and effect size. Both versions of LCI were compared regarding construct validity with the Rivermead Mobility Index, a timed walking test and the FIM instrument. The authors concluded that both the LCI and LCI-5 captured the overall locomotor ability of lower-limb amputees during prosthetic training. The new LCI-5 presents similar and sometimes superior psychometric properties than the standard LCI. LCI-5 also showed a lower ceiling effect

Boulias C. Meikle B. Pauley T. Devlin M.

Return to Driving After Lower-Extremity Amputation

Archives of Physical Medicine and Rehabilitation Volume 87, Issue 9, September 2006, Pages 1183-1188

Boulias and collegues studied the driving behaviours after a major lower limb amputation and the influencing factors for return driving. The study contained a population of 123 patients aged older than 18 years old, who had performed an uni- or bilateral major lower limb amputation. The patients had been fitted with a prosthesis at least one year before the study and were active automobile drivers within six months prior to amputation. The average age of the population was 63.4±12.1 years and the average time since amputation was 6.8±8.3 years.

The study group found that 80.5% of the population returned to driving 3.8 months after amputation, but the majority reported a reduced driving frequency. Factors that significantly decreased the likelihood to return driving were: female sex, age of >60, right sided amputation and a preamputation driving frequency less than every day. The level of amputation, reason for amputation, preamputation automobile transmission and accessibility to public transit did not significant associate with return to drive. Right-sided amputated had significantly more concerns regarding driving and frequently required vehicle modifications. Common barriers to return to driving included fear and/or lack of confidence, preference not to drive and medical conditions.
 

Prosthetics/biomechanics

Zmitrewicz R J. Neptune R R. Sasaki K.

Mechanical energetic contributions from individual muscles and elastic prosthetic feet during symmetric unilateral transtibial amputee walking: A theoretical study

Journal of Biomechanics Article in Press, Corrected Proof

Zmitrewicz and colleagues wanted to identify the contributions of energy storage and return (ESAR) ankle foot prosthesis to trunk support, forward propulsion and leg swing initiation. Further the study group wanted to analyze the compensation of the muscles to provide a normal, symmetric gait pattern.

This theoretical study used muscle actuated forward simulations of unilateral transtibial amputee walking and a non-amputee walking. It was found that the ESAR prosthesis gave the necessary trunk support, but it could not provide the normal net trunk forward propulsion that normally the plantar flexors provides and also the leg swing initiation that normally the biarticular gastrocnemicus provides. In order to compensate the residual leg’s gluteus maximus and rectus femoris delivered increased energy to the trunk for forward propulsion in early stance and in late stance into pre-swing respectively. To help initiate swing the residual leg’s ileopsoas delivered increased energy in pre-and early swing. In the intact leg during the first half of stance the soleus, gluteus maximus and rectus femoris gave increased energy for forward propulsion of the trunk. Iliopsoas increased the leg energy it delivered in pre-and early swing.

Zmitrewicz and colleagues concluded that the combination of the ESAR prosthesis and muscle compensations was able produce a normal, symmetric gait pattern. The authors though suggest that those compensations might place constraints on the neuromuscular and musculoskeletal system and therefore such pattern might be not optimal.
 

Orthotics /biomechanics

Lam W K. Leong J C Y. Li Y H. Hu Y. Lu W.W.

Biomechanical and electromyographic evaluation of ankle foot orthosis and dynamic ankle foot orthosis in spastic cerebral palsy

Gait & Posture Volume 22, Issue 3 , November 2005, Pages 189-197

Lam and colleagues performed motion analysis and electromyography in 13 children with spastic CP and dynamic equinus deformity to evaluate how the gait was affected by ankle foot orthoses (AFO) and dynamic ankle foot orthoses (DAFO). A control group was recruited consisting of 18 healthy age matched children.

Motionanalysis showed that the CP patients had a significantly shorter stride length and increased plantarflexion in initial contact, midstance and swing phase than the controls when walking barefoot. Further it was seen that both AFO and DAFO increased the stride length, permitted pre-positioning for initial contact and also controlled the unwanted plantarflexion during swing phase. DAFOs allowed a significantly larger range of motion than the AFOs.

Electromyelography showed an extremely high firing in the subjects lower limbs, compared to controls, which resulted in tiredness. The AFOs significantly reduced the high firing while the DAFOs did not. The authors suggest that walking endurance may be improved by wearing AFOs. Further the DAFOs had advantage of allowing a larger ankle movement, which may maintain muscle strength and also improves acceptance of the device.

Bartonek Å. ErikssonM. Gutierrez-FarewikE M

A new carbon fibre spring orthosis for children with plantarflexor weakness

Gait and posture 2006 Sep 6 Article in Press, Corrected Proof

A new ankle foot orthosis with a carbon fibre spring constructed for patients with plantarflexor weakness were tested and compared with patient’s regulary orhosis by a 3D-gait analysis.

The orthosis was designed out of principles from carbon fibre prosthetic feet, with the aim to store energy during dorsiflexion at midstance and to release the energy at the end of stance phase to aid push-off.

The gait analysis showed increased dorsiflexion, altered knee kinematics and improved kinetic and temporo-spatial parameters.
The authors concluded that the test group, with plantarflexion weaknesses, improved their walking ability when wearing the carbon fibre spring orthosis. Further the subjective impressions of children and parents were positive.

 

Bionics

Hochberg L R. Serruya M D. Friehs G M. Mukand J A. Saleh M. Caplan A H. Branner A. Chen D. Penn R D. Donoghue J P.

Neuronal ensemble control of prosthetic devices by a human with tetraplegia

Nature 442, 164-171(13 July 2006)

Hochberg and his team presented initial results of a tetraplegic man using a pilot neuromotor prostesis. By collecting movement related signals from cortical areas, transferring them around the damaged parts of the nervous system to the external effectors, the neuromotor prosthesis aims to replace or restore motor functions in paralyzed humans.

An microelectrode array, implanted in primary motor cortex, collected signals from intended hand movements three years after a spinal cord injury. Decoders were created sending signals to a cursor with witch the subject operated computerized tasks etc, even while he conversed. The signals were also send to a prosthetic hand, which could be opened and closed. Further rudimentary actions were performed with a multi-jointed robotic arm. The study group found that the signals for movements in the cortex must remain and are engaged by the intention of a movement even though sensory input and limb movements have been absent for long. Further it was found that the neuromotor prosthesis requires intended driven cortical activity converted to signals to be able to enable useful tasks.

The authors concluded that those early results of a neuromotor prosthesis could provide a valuable new neurotechnology to restore independence for paralyzed persons.
 

Quality management

Daly J. Willis K. Small R. Green J. Welch N. Kealy M. Hughes E.

A hierarchy of evidence for assessing qualitative health research

Journal of Clinical Epidemiology Volume 60, Issue 1 , January 2007, Pages 43-49

Daly and colleagues wanted to outline criteria for assessing qualitative empirical studies in health and medicine leading to a hierarchy of evidence that is specific to qualitative methods. By focusing on central methodological procedures as defining a research framework, sampling and data collection, data analysis and drawing research conclusions the study group worked out a hierarchy of qualitative research design that reflected the reliability of study conclusions for decisions made in health practice and policy.

This work described four levels of qualitative hierarchy of evidence for practice. Single case studies are least likely to produce good evidence, though they may provide important insights into up till now unexplored contexts. Descriptive studies are ranged in following order and do not offer detailed analysis, but might give helpful lists of quotations. Conceptual studies, analyzing all data according conceptual themes is given more weight, but might be limited by a lack of diversity in the sample. The best evidence for practise is provided by the generalizable studies that use conceptual frameworks to derive a fittingly diversified sample with an analysis accounting for all data. The authors concluded that a hierarchy of evidence offer a useful guide to define the strength of evidence and thereby a achieving a foundation for decision making and policy generation.

Empower Health Care Solutions wish you all a happy new year and we look forward to providing you with more interesting scientific news in 2007!

Best regards,
Louise Klevbo.

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