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Objective outcome evaluation using inertial sensors in subacromial impingement syndrome: a five-year follow-up study
This content has been downloaded from IOPscience. Please scroll down to see the full text. 2014 Physiol. Meas. 35 677 (http://iopscience.iop.org/0967-3334/35/4/677) View the table of contents for this issue, or go to the journal homepage for more
Download details: IP Address: 137.120.4.50 This content was downloaded on 25/06/2014 at 16:16
Please note that terms and conditions apply.
Institute of Physics and Engineering in Medicine Physiol. Meas. 35 (2014) 677–686
Physiological Measurement
doi:10.1088/0967-3334/35/4/677
Objective outcome evaluation using inertial sensors in subacromial impingement syndrome: a five-year follow-up study ¨ R J P Korver, R Senden, I C Heyligers and B Grimm AHORSE Research Foundation, Department of Orthopaedic Surgery and Traumatology, Atrium Medical Center Parkstad Heerlen, Henri Dunantstraat 5, 6419 PC Heerlen, The Netherlands E-mail: [email protected], [email protected], [email protected] and [email protected] Received 14 December 2013, revised 8 February 2014 Accepted for publication 19 February 2014 Published 12 March 2014 Abstract
Shoulder-related dysfunction is the second most common musculoskeletal disorder and is an increasing burden on health-care systems. Commonly used clinical questionnaires suffer from subjectivity, pain dominance and a ceiling effect. Objective functional measurement has been identified as a relevant issue in clinical rehabilitation. Inertia based motion analysis (IMA) is a new generation of objective outcome assessment tool; it can produce objective movement parameters while being fast, cheap and easy to operate. In this prospective study, an inertial sensor comprising a three-dimensional accelerometer and gyroscope is attached at the humerus to measure shoulder movements during two motion tasks in patients with subacromial impingement syndrome at baseline and at five-year after treatment. One hundred healthy subjects served as healthy reference database and 15 patients were measured pre- and post-treatment. IMA was better able to detect improvement in shoulder movements compared to the clinical questionnaires (Disability of Arm, Shoulder and Hand (DASH) and Simple Shoulder Test (SST); p < 0.05) and was hardly correlated with the clinical questionnaires (Pearson R = 0.39). It may therefore add an objective functional dimension to outcome assessment.
0967-3334/14/040677+10$33.00
© 2014 Institute of Physics and Engineering in Medicine Printed in the UK
677
¨ R J P Korver et al
Physiol. Meas. 35 (2014) 677
The fast assessment (t < 5 min) of a simple motion test makes it suitable for routine clinical follow-up. Keywords: shoulder, outcome evaluation, inertia sensor, follow-up, subacromial impingement syndrome (Some figures may appear in colour only in the online journal)
Introduction Shoulder-related dysfunction with limited range of motion and restricted activities of daily living (ADL) is the second most common musculoskeletal disorder and severely affects patients’ perception of their general health. The prevalence in subjects beyond 65 years of age is 34% and is responsible for an increasing burden on health-care systems (Chakravarty and Webley 1990, Ketola et al 2009). Subacromial impingement syndrome has been identified as the most frequent cause of shoulder pain (Ketola et al 2009). It is commonly chronic and recurrent, with treatment including rest, subacromial gluco-corticosteroid injections, oral non-steroidal anti-inflammatory drugs, physiotherapy and arthroscopic decompression with acromioplasty and bursectomy (Ketola et al 2009). The syndrome has significant economic consequences owing to its treatment costs and to losses incurred through absence from work (Ketola et al 2009). Due to the magnitude (i.e.: high prevalence in general population, restrictions and pain experienced, and the socio-economic costs) the importance of monitoring the outcome of medical procedures has long been recognized in orthopaedic surgery. In clinical practise, function is frequently evaluated visually or using questionnaires of which the Disability of Arm, Shoulder and Hand (DASH) score and the Simple Shoulder Test (SST) are most popular (Jester et al 2004, Lippitt et al 1992). Although validated, these instruments are subjective, providing incomplete insight on patient’s shoulder function. Furthermore, poor reliability has been reported for these questionnaires (Kirkley et al 2003). Even for the Constant–Murley score, which includes objective range of motion, poor reliability is documented (Rocourt et al 2008). In addition, although there are multiple questionnaires available to assess shoulder function, there is currently no gold standard. Objective assessments like radiographs provide a static image but do not measure dynamic function. Several studies used advanced motion analysis systems for movement analysis such as opto-electronic systems, ultra-sound based systems, force sensors or electromyography (Akkaya et al 2012, Ashford et al 2013, Leggin et al 1996, Bey et al 2006, Van Andel et al 2008). Although these methods provide an objective evaluation of shoulder movements, they are less practical for routine clinical use because they require technically skilled personnel, are time-consuming, relatively expensive and need a laboratory possible causing unnatural movements. In addition, kinematic analysis of the upper extremity has not received as much scientific attention as that of the lower limb, where gait analysis has been validated as a clinical feasible assessment tool (Senden et al 2009). Last decade, inertia based motion analysis (IMA) has been indicated as a potential alternative for lab-based motion analysis of the shoulder (Coley et al 2007, 2008a, 2008b). A single inertial sensor, comprising a three-dimensional (3D) accelerometer and gyroscope, showed to be suitable to measure overall shoulder movement during ADL tasks in standardized controlled conditions (Coley et al 2007). In addition, the discriminative power of IMA to reliably differentiate pathological from healthy shoulder movements has been shown (sensitivity 98.0%, specificity 81.0%, ICC 0.90) (K¨orver et al 2014). To our knowledge, 678
¨ R J P Korver et al
Physiol. Meas. 35 (2014) 677
Table 1. Demographics of test subjects. Age (yr)
Weight (kg)
Height (m)
BMI (kg m−2) Arm length (cm) IMA asym. (%)
Healthy group 40.6 ± 15.7 74.6 ± 15.2 1.72 ± 0.08 25.1 ± 4.4 N = 100 (♂ = 37) Patient group 56.4 ± 11.8 73.4 ± 13.1 1.69 ± 0.08 25.7 ± 4.0 N = 15 (♂ = 5)
30.0 ± 2.1
9.6 ± 7.1%
29.6 ± 1.5
35.3 ± 13.6%
the sensitivity of IMA to detect changes after treatment during a long-term period of follow-up has never been shown. This is the first longitudinal study in which the ability of IMA to detect changes in shoulder movements over time was investigated. In addition, the correlation between objective (IMA) and subjective (clinical questionnaires) assessments was investigated. Methods Subjects
Healthy subjects and patients with subacromial impingement syndrome were recruited. In both groups, the majority of subjects were right sided dominant (92% and 93% respectively) (table 1). Demographic data (i.e. length, weight, gender and date of birth) were collected. Exclusion criteria for both groups were anatomical abnormality (e.g. congenital, osteoarthritis), previous trauma and/or treatment (surgical or non-surgical) for shoulder joint pathology and a neuromuscular, musculoskeletal or systemic disorder (e.g. Parkinson’s disease, rheumatoid arthritis). The healthy group consisted of one hundred subjects (40.6 ± 15.7 years, male/female = 37/63) and served as reference group. The healthy shoulder status in this group was defined by history taking (i.e.: no pain, complaints or previous treatment of any kind of their shoulder joints currently or in the past) and no deviating results in the standard orthopaedic physical examination. Twenty-one patients (56.4 ± 11.8 years, male/female = 7/14) who were diagnosed with unilateral impingement syndrome confirmed using x-rays, ultrasound and/or MR imaging, were included. Five years after the diagnosis, patients were contacted for a second evaluation. Fifteen (57.7 ± 10.4 years, male/female = 5/10) of the 21 patients were willing to participate in this prospective study. These 15 patients were treated with a combination of subacromial gluco-corticosteroid injections and physiotherapy (i.e. rotator cuff and peri-scapular stabilizer strengthening). All but three patients (80%) were free of pain after the treatment, requiring no further treatment. The remaining three patients were additionally treated with an arthroscopic decompression with acromioplasty and bursectomy. Equipment
Bilateral shoulder measurements were performed according to a protocol approved by the hospital’s Institutional Ethics Board Committee. All subjects performed two motion tasks while sitting on a non-rotating stool with 90◦ of hip, knee and ankle flexion. Two ADL based tasks, which are part of standard clinical questionnaires (i.e. CMS, DASH and SST) and which have previously been used for IMA shoulder assessment were performed three times at self-selected speed (figure 1(b)) (Coley et al 2007). (1) Hand to the back (mimics ‘toilet hygiene’). Subjects started with the arm in the neutral anatomical position with their arm hanging beside their body and their thumb pointing to 679
¨ R J P Korver et al
Physiol. Meas. 35 (2014) 677
(a)
(b)
Figure 1. (a) Orientation of the 3D kinematics inertial sensor module and it’s fixation
on the subject’s humerus. (b) The two motion tasks: ‘arm to the back’ (left) and ‘arm behind the head’ (right).
anterior (starting position). The point of task achievement (PTA) was reached when the hand palm touched the belt indicator. The position was hold for 2 s before moving back to the starting position. (2) Hand behind the head (mimics ‘combing hair’). This task started with the hand in the starting position, as mentioned above. The PTA was reached when their hand palm was placed on the occiput with the elbow straight out to the side. After holding this position for 2 s the subjects were instructed to move their arm back to the starting position. Test duration was 0.05) (table 2, figure 3). Patients treated with a combination of subacromial gluco-corticosteroid injections and physiotherapy showed an improved DASH 5-year after treatment (53.1 ± 13.6 versus 33.8 ± 23.5), while SSTscore did not change (5.4 ± 1.6 versus 6.2 ± 3.7). In the group treated with arthroscopic decompression with acromioplasty and bursectomy, the DASH-score did not change after treatment (53.7 ± 18.6 versus 53.7 ± 15.5), while the SST-score reduced (7.7 ± 2.1 versus 3.0 ± 2.0). There differences were not statistically tested, as the subgroups are too small. At five-year follow up, seven subjects (47%) of the patient group were suffering shoulder complaints at their previously healthy side. This creates a ‘false’ asymmetry AR-score as the change in asymmetry over time is not only due to improvements of the affected shoulder but also by a deteriorated function of the healthy shoulder. This is also illustrated by the large ranges in asymmetry AR-scores (range: −192.9%–24.7%) compared to the much smaller range in relative asymmetry AR-scores (−43.4%–40.5%). After treatment, AR-scores of the affected shoulder improved with regard to pre treatment (4.45 versus 2.83; p < 0.05) and exceeded the AR-scores of the healthy subjects (4.19; p > 0.05) at five-year after treatment. The patients treated with a combination of subacromial gluco-corticosteroid injections and physiotherapy showed improved AR-score of the affected shoulder (2.77 ± 0.90 pre versus 4.44 ± 1.38 post treatment) while no change in AR-scores were found in patients treated with an arthroscopic decompression with acromioplasty and bursectomy (3.38 ± 0.75 pre versus 3.60 ± 1.56 post treatment). There was also only a weak correlation between the clinical questionnaires and IMA asymmetry AR-scores (DASH: R = 0.39; SST: R = 0.32). Further, also only a weak correlation was found between the two clinical questionnaires (R = 0.22). Discussion Along with the use of standardised therapeutic strategies, outcome evaluation comprises an important instrument for evaluating the success and effectiveness of a treatment. It is used both 682
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Physiol. Meas. 35 (2014) 677
Figure 3. Scatter plots of individual results (asymmetry AR-score, DASH-score and SST) at baseline and five-year follow-up.
to illustrate established management concepts and to evaluate new therapeutic strategies. With growing interest in health and health care, outcome analysis may determine which treatment and which circumstances ensure good results also for economic aspects (Ketola et al 2009, Jester et al 2004, Lippitt et al 1992, Kirkley et al 2003, Rocourt et al 2008, Leggin et al 1996, Bey et al 2006, Van Andel et al 2008, Senden et al 2009, Coley et al 2007, Jolles et al 2011, Roy et al 2009). A prospective study on patients with impingement syndrome with a follow-up of five years was conducted to investigate whether IMA is sensitive for changes in shoulder movement after 683
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Physiol. Meas. 35 (2014) 677
treatment. In addition, associations between IMA parameters (i.e.: asymmetry AR-scores) and commonly used questionnaires were investigated. In a study of Coley et al ten healthy subjects and ten patients with unilateral shoulder pathology were measured during a follow-up of six months post treatment and, similar to our study, IMA was used to calculate the asymmetry percentage in angular rates during ADL tasks. Their healthy reference group showed 6% asymmetry and the patient group 41% asymmetry at baseline, which is similar to our results. In our study, AR-scores were higher (4.5 versus 2.8; p < 0.05) and asymmetry AR-scores lower (−19.0% versus 35.3%; p < 0.05) after treatment indicating better control and coordination of the affected shoulder. Although Coley et al were able to get a significant improvement in asymmetry scores at three and six months post treatment (19% and 17% respectively; p < 0.05), the scores did not reach those of the healthy subjects (p < 0.05) (Coley et al 2007). By the fact that there is still improvement of shoulder function after six months of follow-up, as is shown by our results at 5-years post-treatment in which the AR-scores of the healthy subjects were approached and even were exceeded in 60% (table 2). Jolles et al (2011) used an angular rate parameter as measured by IMA, comparable to our study, in patients treated for unilateral shoulder pathology and compared them to a healthy reference group. At one-year follow-up patients showed asymmetry scores similar to the healthy subjects (15 ± 15% versus 8 ± 5%; p > 0.05). It is important that, in contrast to the AR-scores, the asymmetry AR-score is affected by movements of both shoulders. Therefore the asymmetry score may mask changes (e.g. improvement) in shoulder function of the affected shoulder due to changes (e.g. impairment) in function of the contra-lateral shoulder. This indicates that asymmetry scores can better be used for diagnostics or for short term follow-up. To monitor changes in shoulder function during long term follow-up, AR-scores of an affected shoulder can better be compared to a healthy reference database as is shown by the much smaller range in relative asymmetry AR-scores compared to the asymmetry AR-scores (table 2). This is also more suitable for routine clinical use because only the affected side has to be measured, thereby reducing the test duration. IMA derived asymmetry scores showed improvements of 119% (asymmetry AR-score) to 154% (relative asymmetry AR-scores), which is much higher than the improvements detected by the DASH (40%) and SST (3%). This indicates that IMA is more sensitive to detect change in shoulder function compared to commonly used questionnaires. These results are in agreement with the results of Coley et al (2007) and Jolles et al (2011) who showed that IMA was able to detect changes in shoulder function whereas no changes were detected by questionnaires. Motion parameters are more sensitive to functional changes than the clinical scores, which may help the clinician to detect abnormal rehabilitation and can promote efficient intervention. Although IMA and DASH-score showed significant improvements in shoulder function after treatment, no change in SST was found. This suggests that the SST captures different aspects of shoulder function during ADL, i.e. it may be more pain-related and shoulder function specific (for example the DASH: ‘can you place an object on a shelf above your head?’ versus SST: ‘can you lift one pound to the level of your shoulder without bending your elbow?’). Previous studies state that the SST has a high reliability compared to other clinical questionnaires. However, it is only weakly correlated to the Constant–Murley score, which includes objective range of motion measurements, illustrating the subjective character of the SST (Jolles et al 2011, Beaton and Richards 1998, Roy et al 2009, Skutek et al 2000). A possible explanation for the more subjective character of the SST might be that the SST (12 items) is designed for patient self-assessment and emphasises the patient’s perspective, compared to the DASH (30 items) which is also a patient reported questionnaire but is a more 684
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Physiol. Meas. 35 (2014) 677
complex evaluation instrument consisting of function- and pain-related questions and includes questions regarding role function and social activities. In contrast to previous studies who showed a good correlation between IMA derived parameters and the DASH (R = 0.71) and SST (R = 0.76), the current study only found a weak correlation (R-range: 0.32–0.39) (Jolles et al 2011). This might be due to differences between studies in baseline scores on questionnaires (DASH: 83.7 versus 53.5 and SST: 4.0 versus 5.5), while IMA parameters were similar. The weak association between questionnaires and IMA may illustrate that objective measures (like IMA or CMS) capture different aspects of shoulder function compared to the questionnaires which are more subjective and related to pain sensation. Therefore, IMA adds additional information about the patients’ shoulder function beyond the standard clinical outcome scales. Combing questionnaires with objective outcome tools may contribute to improved diagnostics, treatment evaluations and clinical decision-making. Furthermore, patients can be better informed about the expected result after treatment because an improvement in function does not inevitably mean an improvement in pain sensation. Although this study was not designed to investigate treatment superiority, the observation of improved AR- and DASH-scores in the non-surgically treated patients compared to the deteriorated SST-scores in the surgically treated patients at five-year follow-up is interesting and may even further indicate that the SST captures different aspects of shoulder function. These results are in agreement with the Dutch guideline for impingement syndrome of the Dutch Orthopaedic Surgery Society stating that non-surgical treatment must be first choice. However larger patient groups are needed to perform treatment comparison and statistical analysis of the results. Conclusion This study investigated whether an IMA derived score is sensitive to identify changes in shoulder function in patients with impingement syndrome 5-years after treatment. IMA showed to be more sensitive to detect changes in shoulder movement compared to commonly used questionnaires. The weak correlations between IMA parameters and the subjective and pain related clinical questionnaires shows the added value of IMA for clinical use. Applying IMA in clinical practise may help physicians in decision-making. In addition, it can be used to clarify the patient’s post treatment expectations. Acknowledgments This study was not sponsored. The study design, data collection, analysis and interpretation of data, and writing of the manuscript were done independently. References Akkaya N, Ardic F, Ozgen M, Akkaya S, Sahin F and Kilic A 2012 Efficacy of electromyographic biofeedback and electrical stimulation following arthroscopic partial meniscectomy: a randomized controlled trial Clin. Rehabil. 26 224–36 Ashford S, Turner-Stokes L, Siegert R and Slade M 2013 Initial psychometric evaluation of the arm activity measure (ArmA): a measure of activity in the hemiparetic arm Clin. Rehabil. 27 1–13 Beaton D and Richards R R 1998 Assessing the reliability and responsiveness of 5 shoulder questionnaires J. Shoulder Elbow Surg. 7 565–72 Bey M J, Zauel R, Brock S K and Tashman S 2006 Validation of a new model-based tracking technique for measuring three-dimensional, in vivo glenohumeral joint kinematics J. Biomech. Eng. 128 604–9 685
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Chakravarty K K and Webley M 1990 Disorders of the shoulder: an often unrecognized cause of disability in elderly people Br. Med. J. 300 848–9 Coley B, Jolles B M, Farron A and Aminian K 2008a Arm position during daily activity Gait Posture 28 581–7 Coley B, Jolles B M, Farron A, Bourgeois A, Nussbaumer F, Pichonnaz C and Aminian K 2007 Outcome evaluation in shoulder surgery using 3D kinematics sensors Gait Posture 25 523–32 Coley B, Jolles B M, Farron A, Pichonnaz C, Bassin J P and Aminian K 2008b Estimating dominant upper-limb segments during daily activity Gait Posture 27 368–75 Jester A, Harth A, Wind G, Germann G and Sauerbier M 2004 Disabilities of the arm, shoulder and hand (DASH) questionnaire: determining functional activity profiles in patients with upper extremity disorders J. Hand Surg. Br. 30 23–28 Jolles B M, Duc C, Coley B, Aminian K, Pichonnaz C, Bassin J P and Farron A 2011 Objective evaluation of shoulder function using body-fixed sensors: a new way to detect early treatment failures? J. Shoulder Elbow Surg. 20 1074–81 Ketola S, Lehtinen J, Arnala I, Nissinen M, Westinius H, Sintonen H, Aronen P, Konttinen Y T, Malmivaara A and Rousi T 2009 Does arthroscopic acromioplasty provide any additional value in the treatment of shoulder impingement syndrome? J. Bone Joint Surg. Br. 91 1326–34 Kirkley A, Griffin S and Dainty K 2003 Scoring systems for the functional assessment of the shoulder Arthroscopy 19 1109–20 K¨orver R J P, Heyligers I C, Samijo S K and Grimm B 2014 Inertia based functional scoring of the shoulder in clinical practice Physiol. Meas. 35 167–76 Leggin B G, Neuman R M, Iannotti J P, Williams G R and Thompson E C 1996 Intrarater and interrater reliability of three isometric dynamometers in assessing shoulder strength J. Shoulder Elbow Surg. 5 18–24 Lippitt S B, Harryman D T and Matsen F A 1992 A practical tool for evaluating function: the simple shoulder test The Shoulder: A Balance of Mobility and Stability ed F A Matsen, F H Fu and R J Hawkins (Rosemont, IL: American Academy of Orthopaedic Surgeons) pp 501–18 Rocourt M H H, Radlinger L, Kalberer F, Sanavi S, Schmid N S, Leunig M and Hertel R 2008 Evaluation of intratester and intertester reliability of the Constant–Murley shoulder assessment J. Shoulder Elbow Surg. 17 364–9 Roy J S, MacDermid J C and Woodhouse L J 2009 Measuring shoulder function: a systematic review of four questionnaires Arthritis Rheum. 61 623–32 Senden R, Grimm B, Heyligers I C, Savelberg H H C M and Meijer K 2009 Acceleration-based gait test for healthy subjects: reliability and reference data Gait Posture 30 192–6 Skutek M, Fremerey R W, Zeichen J and Bosch J 2000 Outcome analysis following open rotator cuff repair. Early effectiveness validated using four different shoulder assessment scales Arch. Orthop. Trauma Surg. 120 432–6 Van Andel C J, Wolterbeek N, Doorenbosch C A M, Veeger H E J and Harlaar J 2008 Complete 3D kinematics of upper limb extremity functional tasks Gait Posture 27 120–7
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Objective outcome evaluation using inertial sensors in subacromial impingement syndrome: a five-year follow-up study
This content has been downloaded from IOPscience. Please scroll down to see the full text. 2014 Physiol. Meas. 35 677 (http://iopscience.iop.org/0967-3334/35/4/677) View the table of contents for this issue, or go to the journal homepage for more
Download details: IP Address: 137.120.4.50 This content was downloaded on 25/06/2014 at 16:16
Please note that terms and conditions apply.
Institute of Physics and Engineering in Medicine Physiol. Meas. 35 (2014) 677–686
Physiological Measurement
doi:10.1088/0967-3334/35/4/677
Objective outcome evaluation using inertial sensors in subacromial impingement syndrome: a five-year follow-up study ¨ R J P Korver, R Senden, I C Heyligers and B Grimm AHORSE Research Foundation, Department of Orthopaedic Surgery and Traumatology, Atrium Medical Center Parkstad Heerlen, Henri Dunantstraat 5, 6419 PC Heerlen, The Netherlands E-mail: [email protected], [email protected], [email protected] and [email protected] Received 14 December 2013, revised 8 February 2014 Accepted for publication 19 February 2014 Published 12 March 2014 Abstract
Shoulder-related dysfunction is the second most common musculoskeletal disorder and is an increasing burden on health-care systems. Commonly used clinical questionnaires suffer from subjectivity, pain dominance and a ceiling effect. Objective functional measurement has been identified as a relevant issue in clinical rehabilitation. Inertia based motion analysis (IMA) is a new generation of objective outcome assessment tool; it can produce objective movement parameters while being fast, cheap and easy to operate. In this prospective study, an inertial sensor comprising a three-dimensional accelerometer and gyroscope is attached at the humerus to measure shoulder movements during two motion tasks in patients with subacromial impingement syndrome at baseline and at five-year after treatment. One hundred healthy subjects served as healthy reference database and 15 patients were measured pre- and post-treatment. IMA was better able to detect improvement in shoulder movements compared to the clinical questionnaires (Disability of Arm, Shoulder and Hand (DASH) and Simple Shoulder Test (SST); p < 0.05) and was hardly correlated with the clinical questionnaires (Pearson R = 0.39). It may therefore add an objective functional dimension to outcome assessment.
0967-3334/14/040677+10$33.00
© 2014 Institute of Physics and Engineering in Medicine Printed in the UK
677
¨ R J P Korver et al
Physiol. Meas. 35 (2014) 677
The fast assessment (t < 5 min) of a simple motion test makes it suitable for routine clinical follow-up. Keywords: shoulder, outcome evaluation, inertia sensor, follow-up, subacromial impingement syndrome (Some figures may appear in colour only in the online journal)
Introduction Shoulder-related dysfunction with limited range of motion and restricted activities of daily living (ADL) is the second most common musculoskeletal disorder and severely affects patients’ perception of their general health. The prevalence in subjects beyond 65 years of age is 34% and is responsible for an increasing burden on health-care systems (Chakravarty and Webley 1990, Ketola et al 2009). Subacromial impingement syndrome has been identified as the most frequent cause of shoulder pain (Ketola et al 2009). It is commonly chronic and recurrent, with treatment including rest, subacromial gluco-corticosteroid injections, oral non-steroidal anti-inflammatory drugs, physiotherapy and arthroscopic decompression with acromioplasty and bursectomy (Ketola et al 2009). The syndrome has significant economic consequences owing to its treatment costs and to losses incurred through absence from work (Ketola et al 2009). Due to the magnitude (i.e.: high prevalence in general population, restrictions and pain experienced, and the socio-economic costs) the importance of monitoring the outcome of medical procedures has long been recognized in orthopaedic surgery. In clinical practise, function is frequently evaluated visually or using questionnaires of which the Disability of Arm, Shoulder and Hand (DASH) score and the Simple Shoulder Test (SST) are most popular (Jester et al 2004, Lippitt et al 1992). Although validated, these instruments are subjective, providing incomplete insight on patient’s shoulder function. Furthermore, poor reliability has been reported for these questionnaires (Kirkley et al 2003). Even for the Constant–Murley score, which includes objective range of motion, poor reliability is documented (Rocourt et al 2008). In addition, although there are multiple questionnaires available to assess shoulder function, there is currently no gold standard. Objective assessments like radiographs provide a static image but do not measure dynamic function. Several studies used advanced motion analysis systems for movement analysis such as opto-electronic systems, ultra-sound based systems, force sensors or electromyography (Akkaya et al 2012, Ashford et al 2013, Leggin et al 1996, Bey et al 2006, Van Andel et al 2008). Although these methods provide an objective evaluation of shoulder movements, they are less practical for routine clinical use because they require technically skilled personnel, are time-consuming, relatively expensive and need a laboratory possible causing unnatural movements. In addition, kinematic analysis of the upper extremity has not received as much scientific attention as that of the lower limb, where gait analysis has been validated as a clinical feasible assessment tool (Senden et al 2009). Last decade, inertia based motion analysis (IMA) has been indicated as a potential alternative for lab-based motion analysis of the shoulder (Coley et al 2007, 2008a, 2008b). A single inertial sensor, comprising a three-dimensional (3D) accelerometer and gyroscope, showed to be suitable to measure overall shoulder movement during ADL tasks in standardized controlled conditions (Coley et al 2007). In addition, the discriminative power of IMA to reliably differentiate pathological from healthy shoulder movements has been shown (sensitivity 98.0%, specificity 81.0%, ICC 0.90) (K¨orver et al 2014). To our knowledge, 678
¨ R J P Korver et al
Physiol. Meas. 35 (2014) 677
Table 1. Demographics of test subjects. Age (yr)
Weight (kg)
Height (m)
BMI (kg m−2) Arm length (cm) IMA asym. (%)
Healthy group 40.6 ± 15.7 74.6 ± 15.2 1.72 ± 0.08 25.1 ± 4.4 N = 100 (♂ = 37) Patient group 56.4 ± 11.8 73.4 ± 13.1 1.69 ± 0.08 25.7 ± 4.0 N = 15 (♂ = 5)
30.0 ± 2.1
9.6 ± 7.1%
29.6 ± 1.5
35.3 ± 13.6%
the sensitivity of IMA to detect changes after treatment during a long-term period of follow-up has never been shown. This is the first longitudinal study in which the ability of IMA to detect changes in shoulder movements over time was investigated. In addition, the correlation between objective (IMA) and subjective (clinical questionnaires) assessments was investigated. Methods Subjects
Healthy subjects and patients with subacromial impingement syndrome were recruited. In both groups, the majority of subjects were right sided dominant (92% and 93% respectively) (table 1). Demographic data (i.e. length, weight, gender and date of birth) were collected. Exclusion criteria for both groups were anatomical abnormality (e.g. congenital, osteoarthritis), previous trauma and/or treatment (surgical or non-surgical) for shoulder joint pathology and a neuromuscular, musculoskeletal or systemic disorder (e.g. Parkinson’s disease, rheumatoid arthritis). The healthy group consisted of one hundred subjects (40.6 ± 15.7 years, male/female = 37/63) and served as reference group. The healthy shoulder status in this group was defined by history taking (i.e.: no pain, complaints or previous treatment of any kind of their shoulder joints currently or in the past) and no deviating results in the standard orthopaedic physical examination. Twenty-one patients (56.4 ± 11.8 years, male/female = 7/14) who were diagnosed with unilateral impingement syndrome confirmed using x-rays, ultrasound and/or MR imaging, were included. Five years after the diagnosis, patients were contacted for a second evaluation. Fifteen (57.7 ± 10.4 years, male/female = 5/10) of the 21 patients were willing to participate in this prospective study. These 15 patients were treated with a combination of subacromial gluco-corticosteroid injections and physiotherapy (i.e. rotator cuff and peri-scapular stabilizer strengthening). All but three patients (80%) were free of pain after the treatment, requiring no further treatment. The remaining three patients were additionally treated with an arthroscopic decompression with acromioplasty and bursectomy. Equipment
Bilateral shoulder measurements were performed according to a protocol approved by the hospital’s Institutional Ethics Board Committee. All subjects performed two motion tasks while sitting on a non-rotating stool with 90◦ of hip, knee and ankle flexion. Two ADL based tasks, which are part of standard clinical questionnaires (i.e. CMS, DASH and SST) and which have previously been used for IMA shoulder assessment were performed three times at self-selected speed (figure 1(b)) (Coley et al 2007). (1) Hand to the back (mimics ‘toilet hygiene’). Subjects started with the arm in the neutral anatomical position with their arm hanging beside their body and their thumb pointing to 679
¨ R J P Korver et al
Physiol. Meas. 35 (2014) 677
(a)
(b)
Figure 1. (a) Orientation of the 3D kinematics inertial sensor module and it’s fixation
on the subject’s humerus. (b) The two motion tasks: ‘arm to the back’ (left) and ‘arm behind the head’ (right).
anterior (starting position). The point of task achievement (PTA) was reached when the hand palm touched the belt indicator. The position was hold for 2 s before moving back to the starting position. (2) Hand behind the head (mimics ‘combing hair’). This task started with the hand in the starting position, as mentioned above. The PTA was reached when their hand palm was placed on the occiput with the elbow straight out to the side. After holding this position for 2 s the subjects were instructed to move their arm back to the starting position. Test duration was 0.05) (table 2, figure 3). Patients treated with a combination of subacromial gluco-corticosteroid injections and physiotherapy showed an improved DASH 5-year after treatment (53.1 ± 13.6 versus 33.8 ± 23.5), while SSTscore did not change (5.4 ± 1.6 versus 6.2 ± 3.7). In the group treated with arthroscopic decompression with acromioplasty and bursectomy, the DASH-score did not change after treatment (53.7 ± 18.6 versus 53.7 ± 15.5), while the SST-score reduced (7.7 ± 2.1 versus 3.0 ± 2.0). There differences were not statistically tested, as the subgroups are too small. At five-year follow up, seven subjects (47%) of the patient group were suffering shoulder complaints at their previously healthy side. This creates a ‘false’ asymmetry AR-score as the change in asymmetry over time is not only due to improvements of the affected shoulder but also by a deteriorated function of the healthy shoulder. This is also illustrated by the large ranges in asymmetry AR-scores (range: −192.9%–24.7%) compared to the much smaller range in relative asymmetry AR-scores (−43.4%–40.5%). After treatment, AR-scores of the affected shoulder improved with regard to pre treatment (4.45 versus 2.83; p < 0.05) and exceeded the AR-scores of the healthy subjects (4.19; p > 0.05) at five-year after treatment. The patients treated with a combination of subacromial gluco-corticosteroid injections and physiotherapy showed improved AR-score of the affected shoulder (2.77 ± 0.90 pre versus 4.44 ± 1.38 post treatment) while no change in AR-scores were found in patients treated with an arthroscopic decompression with acromioplasty and bursectomy (3.38 ± 0.75 pre versus 3.60 ± 1.56 post treatment). There was also only a weak correlation between the clinical questionnaires and IMA asymmetry AR-scores (DASH: R = 0.39; SST: R = 0.32). Further, also only a weak correlation was found between the two clinical questionnaires (R = 0.22). Discussion Along with the use of standardised therapeutic strategies, outcome evaluation comprises an important instrument for evaluating the success and effectiveness of a treatment. It is used both 682
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Figure 3. Scatter plots of individual results (asymmetry AR-score, DASH-score and SST) at baseline and five-year follow-up.
to illustrate established management concepts and to evaluate new therapeutic strategies. With growing interest in health and health care, outcome analysis may determine which treatment and which circumstances ensure good results also for economic aspects (Ketola et al 2009, Jester et al 2004, Lippitt et al 1992, Kirkley et al 2003, Rocourt et al 2008, Leggin et al 1996, Bey et al 2006, Van Andel et al 2008, Senden et al 2009, Coley et al 2007, Jolles et al 2011, Roy et al 2009). A prospective study on patients with impingement syndrome with a follow-up of five years was conducted to investigate whether IMA is sensitive for changes in shoulder movement after 683
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treatment. In addition, associations between IMA parameters (i.e.: asymmetry AR-scores) and commonly used questionnaires were investigated. In a study of Coley et al ten healthy subjects and ten patients with unilateral shoulder pathology were measured during a follow-up of six months post treatment and, similar to our study, IMA was used to calculate the asymmetry percentage in angular rates during ADL tasks. Their healthy reference group showed 6% asymmetry and the patient group 41% asymmetry at baseline, which is similar to our results. In our study, AR-scores were higher (4.5 versus 2.8; p < 0.05) and asymmetry AR-scores lower (−19.0% versus 35.3%; p < 0.05) after treatment indicating better control and coordination of the affected shoulder. Although Coley et al were able to get a significant improvement in asymmetry scores at three and six months post treatment (19% and 17% respectively; p < 0.05), the scores did not reach those of the healthy subjects (p < 0.05) (Coley et al 2007). By the fact that there is still improvement of shoulder function after six months of follow-up, as is shown by our results at 5-years post-treatment in which the AR-scores of the healthy subjects were approached and even were exceeded in 60% (table 2). Jolles et al (2011) used an angular rate parameter as measured by IMA, comparable to our study, in patients treated for unilateral shoulder pathology and compared them to a healthy reference group. At one-year follow-up patients showed asymmetry scores similar to the healthy subjects (15 ± 15% versus 8 ± 5%; p > 0.05). It is important that, in contrast to the AR-scores, the asymmetry AR-score is affected by movements of both shoulders. Therefore the asymmetry score may mask changes (e.g. improvement) in shoulder function of the affected shoulder due to changes (e.g. impairment) in function of the contra-lateral shoulder. This indicates that asymmetry scores can better be used for diagnostics or for short term follow-up. To monitor changes in shoulder function during long term follow-up, AR-scores of an affected shoulder can better be compared to a healthy reference database as is shown by the much smaller range in relative asymmetry AR-scores compared to the asymmetry AR-scores (table 2). This is also more suitable for routine clinical use because only the affected side has to be measured, thereby reducing the test duration. IMA derived asymmetry scores showed improvements of 119% (asymmetry AR-score) to 154% (relative asymmetry AR-scores), which is much higher than the improvements detected by the DASH (40%) and SST (3%). This indicates that IMA is more sensitive to detect change in shoulder function compared to commonly used questionnaires. These results are in agreement with the results of Coley et al (2007) and Jolles et al (2011) who showed that IMA was able to detect changes in shoulder function whereas no changes were detected by questionnaires. Motion parameters are more sensitive to functional changes than the clinical scores, which may help the clinician to detect abnormal rehabilitation and can promote efficient intervention. Although IMA and DASH-score showed significant improvements in shoulder function after treatment, no change in SST was found. This suggests that the SST captures different aspects of shoulder function during ADL, i.e. it may be more pain-related and shoulder function specific (for example the DASH: ‘can you place an object on a shelf above your head?’ versus SST: ‘can you lift one pound to the level of your shoulder without bending your elbow?’). Previous studies state that the SST has a high reliability compared to other clinical questionnaires. However, it is only weakly correlated to the Constant–Murley score, which includes objective range of motion measurements, illustrating the subjective character of the SST (Jolles et al 2011, Beaton and Richards 1998, Roy et al 2009, Skutek et al 2000). A possible explanation for the more subjective character of the SST might be that the SST (12 items) is designed for patient self-assessment and emphasises the patient’s perspective, compared to the DASH (30 items) which is also a patient reported questionnaire but is a more 684
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complex evaluation instrument consisting of function- and pain-related questions and includes questions regarding role function and social activities. In contrast to previous studies who showed a good correlation between IMA derived parameters and the DASH (R = 0.71) and SST (R = 0.76), the current study only found a weak correlation (R-range: 0.32–0.39) (Jolles et al 2011). This might be due to differences between studies in baseline scores on questionnaires (DASH: 83.7 versus 53.5 and SST: 4.0 versus 5.5), while IMA parameters were similar. The weak association between questionnaires and IMA may illustrate that objective measures (like IMA or CMS) capture different aspects of shoulder function compared to the questionnaires which are more subjective and related to pain sensation. Therefore, IMA adds additional information about the patients’ shoulder function beyond the standard clinical outcome scales. Combing questionnaires with objective outcome tools may contribute to improved diagnostics, treatment evaluations and clinical decision-making. Furthermore, patients can be better informed about the expected result after treatment because an improvement in function does not inevitably mean an improvement in pain sensation. Although this study was not designed to investigate treatment superiority, the observation of improved AR- and DASH-scores in the non-surgically treated patients compared to the deteriorated SST-scores in the surgically treated patients at five-year follow-up is interesting and may even further indicate that the SST captures different aspects of shoulder function. These results are in agreement with the Dutch guideline for impingement syndrome of the Dutch Orthopaedic Surgery Society stating that non-surgical treatment must be first choice. However larger patient groups are needed to perform treatment comparison and statistical analysis of the results. Conclusion This study investigated whether an IMA derived score is sensitive to identify changes in shoulder function in patients with impingement syndrome 5-years after treatment. IMA showed to be more sensitive to detect changes in shoulder movement compared to commonly used questionnaires. The weak correlations between IMA parameters and the subjective and pain related clinical questionnaires shows the added value of IMA for clinical use. Applying IMA in clinical practise may help physicians in decision-making. In addition, it can be used to clarify the patient’s post treatment expectations. Acknowledgments This study was not sponsored. The study design, data collection, analysis and interpretation of data, and writing of the manuscript were done independently. References Akkaya N, Ardic F, Ozgen M, Akkaya S, Sahin F and Kilic A 2012 Efficacy of electromyographic biofeedback and electrical stimulation following arthroscopic partial meniscectomy: a randomized controlled trial Clin. Rehabil. 26 224–36 Ashford S, Turner-Stokes L, Siegert R and Slade M 2013 Initial psychometric evaluation of the arm activity measure (ArmA): a measure of activity in the hemiparetic arm Clin. Rehabil. 27 1–13 Beaton D and Richards R R 1998 Assessing the reliability and responsiveness of 5 shoulder questionnaires J. Shoulder Elbow Surg. 7 565–72 Bey M J, Zauel R, Brock S K and Tashman S 2006 Validation of a new model-based tracking technique for measuring three-dimensional, in vivo glenohumeral joint kinematics J. Biomech. Eng. 128 604–9 685
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