Shoulder motion - lessons learned from the Kinect motion capture system.

The Kinect sensors, originally developed for gaming, have been used as a non-invasive approach to shoulder motion analysis. These sensors provide an image by detecting the pattern of projected infrared dots reflected by the body's surface. Processing these images against the computer's knowledge of human anatomy provides data on the position of defined body elements, such as the trunk, shoulder, arm, elbow and forearm. These measurements are observer independent and can be made in the clothed patient without the need to attach markers.

Several recent articles have presented the utility of such technology in understanding the relationship between shoulder motion and shoulder function.

In normal shoulders, range of motion correlates strongly with shoulder function,

Measurement of active shoulder motion using the Kinect, a commercially available infrared position detection system The active motion in well-functioning patient shoulders averaged 155° ± 22° abduction, 159° ± 14° flexion, 76° ± 18° external rotation in abduction, -59° ± 25° internal rotation in abduction, and -3.3 ± 3.7 inches of cross-body adduction, values similar to those obtained in normal volunteers.  Use of the Kinect system proved practical in clinical examination rooms, requiring <5 minutes to document the 5 motions in both shoulders.

In arthritic shoulders, the range of motion is not the major determinant of shoulder function. In Relationship Between Patient-Reported Assessment of Shoulder Function and Objective Range-of-Motion Measurements, there was poor correlation between objective measurements of active abduction and total SST scores: the coefficients of determination (R) were 0.29 for the osteoarthritic shoulders of women and 0.25 for those of men.  The authors concluded that factors other than active range of motion were the major drivers of the function of the arthritic shoulder. 

In shoulders with cuff pathology, neither the range of motion or the extent of the pathology was the major determinant of shoulder function.  In Patient self-assessed shoulder comfort and function and active motion are not closely related to surgically documented rotator cuff tear integrity the authors examined 55 shoulders having surgery for cuff-related symptoms, correlating the preoperative Simple Shoulder Test score with the preoperative active shoulder motion measured by the Kinect and with the integrity of the cuff observed at surgery. The 16 shoulders with tendinosis or partial-thickness tears had an average Simple Shoulder Test score of 3.7 ± 3.3, active abduction of 111° ± 38°, and active flexion of 115° ± 36°. The corresponding values were 3.6 ± 2.8, 94° ± 47°, and 94° ± 52° for the 22 full-thickness supraspinatus tears and 3.9 ± 2.7, 89° ± 39°, and 100° ± 39° for the 17 supraspinatus + infraspinatus tears.

The scapulothoroacic articulation is an important contributor to humerothoracic motion in patients having elective shoulder surgery. In The contribution of the scapula to active shoulder motion and self-assessed function in three hundred and fifty two patients prior to elective shoulder surgery, the Kinect system was used to assess active scapulothoracic (ST) and humerothoracic (HT) abduction in 12 controls and in 352 patients before elective shoulder surgery. For the controls, ST abduction averaged 26 ± 7° of the active HT abduction (135 ± 5°). For the 352 patients having elective surgery, active ST abduction averaged 12 ± 10° of the active HT abduction (72 ± 38). For 10 of the 12 SST functions, patients unable to perform the function had significantly less scapulothoracic abduction, for example, shoulders unable to lift one pound to shoulder level had 9 ± 8° of ST abduction in contrast to 17 ± 10°  for those able to perform this function (p < .001).

While the information gathered using the Kinect remains clinically relevant, as pointed out by he authors of Reliability and agreement of Azure Kinect and Kinect v2 depth sensors in the shoulder joint range of motion estimation the original user-friendly Kinect systems are unfortunately no longer produced for game consoles. The Azure Kinect is available, but requires custom programming using the Azure Kinect Body Tracking SDK

Our hope is that developers will produce a "plug and play" product that can be used for shoulder clinical research and practice.

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Here are some videos that are of shoulder interest

Shoulder arthritis - what you need to know (see this link).

How to x-ray the shoulder (see this link).

The ream and run procedure (see this link).

The total shoulder arthroplasty (see this link).

The cuff tear arthropathy arthroplasty (see this link).

The reverse total shoulder arthroplasty (see this link).

The smooth and move procedure for irreparable rotator cuff tears (see this link).

Shoulder rehabilitation exercises (see this link).

Treatment of irreparable cuff tears with retained active elevation

Significant improvement in patient self-assessed comfort and function as early as six weeks after the smooth and move procedure for shoulders with irreparable rotator cuff tears and retained active elevation

These authors point out that it has been previously  documented that the smooth and move procedure—smoothing the proximal humeral surface while maintaining the coracoacromial arch—can provide clinically significant long-term improvement in function for patients having irreparable rotator cuff tears with retained active elevation (see previous blog post that is reproduced below).

In this study they sought to demonstrate that clinically significant gains in comfort, function, and active motion can be realized as early as 6 weeks after this procedure. They conducted a prospective cohort study of the 6-week clinical outcomes for 48 patients enrolled prior to a smooth and move procedure for irreparable rotator cuff tears. Prior rotator cuff repair had been attempted in 28 (70%).

In 40 patients with preoperative and 6-week postoperative measurements, the Simple Shoulder Test scores improved from an average of 3.4 ± 2.8 preoperatively to 5.7 ± 3.5 at 6 weeks (p < 0.001), an improvement that exceeded the published values for the minimal clinically important difference (MCID).

The clinical outcomes were not worse for the 18 shoulders with irreparable tears of both the supraspinatus and infraspinatus.

In 30 patients with preoperative and 6-week postoperative objective measurements of active motion, the average abduction improved from 93(± 43) to 123(± 47)° (p = 0.005) and the average flexion improved from 102(± 46) to 126(± 44)° (p = 0.023).

They concluded that in addition to its previously documented long-term effectiveness for shoulders with irreparable rotator cuff tears and retained active elevation, this study demonstrates that the smooth and move procedure provides clinically significant improvement as early as 6 weeks after surgery.

They present the case example of a 71 year old physician photographer with a failed prior cuff repair attempt. Here is the preoperative radiograph

At surgery he had no supraspinatus or infraspinatus. The debris shown below was removed from his humeroscapular motion interface

This video (used with permission of the patient) shows his function 6 weeks after surgery.

Eight weeks after surgery he was photographing north of the Arctic Circle. Here's one of his photos.

This study should be considered along with a prior study, which is discussed below.

Treatment of irreparable cuff tears with smoothing of the humeroscapular motion interface without acromioplasty

These authors sought to determine whether shoulders with irreparable rotator cuff tears and retained active elevation (>100 degrees) can be durably improved using a conservative surgical procedure that smoothes the interface between the proximal humeral convexity and the concave undersurface of the coracoacromial arch followed by immediate range of motion exercises.

The typical pathology in these cases is shown in the figure below.

The surgical approach is through a deltoid splitting incision that preserves the deltoid origin, the acromion and the coracoacromial ligament.

The coracoacromial arch is preserved to avoid the complication of anterosuperior escape that is commonly encountered when acromioplasty is performed in the presence of a large cuff tear.

The surgery includes smoothing of the prominence of the greater tuberosity that is exposed in cuff tears along with resection of adhesions in the humeroscapular motion interface and a gentle manipulation under anesthesia to resolve the stiffness that is commonly associated with chronic cuff tears. Immediate active assisted and active motion are encouraged immediately after surgery. Because no repair or reconstruction has been performed, activities, including deltoid strengthening can be resumed as soon as they are comfortable. 

They reviewed 151 patients with a mean age of 63.4 (range 40–90) years at a mean of 7.3 (range 2–19) years after this surgery. The patient data are shown below, contrasting the patients that did and did not improve by the MCID of 2 in the Simple Shoulder Test

In 77 shoulders with previously unrepaired irreparable tears, Simple Shoulder Test (SST) scores improved from an average of 4.6 (range 0–12) to 8.5 (range 1–12) (p < 0.001). Fifty-four patients (70%) improved by at least the minimally clinically important difference (MCID) of 2 SST points. 

For 74 shoulders with irreparable failed prior repairs, SST scores improved from 4.0 (range 0–11) to 7.5 (range 0–12) (p < 0.001). Fifty-four patients (73%) improved by the MCID of 2 SST points.

They provided this case example. A rancher in his mid 60s had a right rotator cuff reconstruction with freeze-dried acellular human dermal collagen tissue matrix that subsequently became infected. He presented to us with a painful stiff right shoulder. At surgery there was extensive scar throughout the humeral scapular motion interface. The subscapularis was detached but was reconstructible. The supraspinatus was absent. The upper 2/3 of the infraspinatus was absent as well. The tuberosities were prominent. He had a smooth and move procedure at which time the abundant scar in the humeral scapular motion interface was debrided. The previous sutures and Graft Jacket were excised. The bursa was removed. The prominent tuberosities were resected using a rongeur and a burr. A manipulation under anesthesia was performed to assure a full passive range of motion. Passive and active range of motion exercises were started immediately after surgery. Three years later he reported excellent shoulder comfort and function and sent us this photo of his return to one of his favorite activities

They concluded that smoothing of the humeroscapular interface can durably improve symptomatic shoulders with irreparable cuff tears and retained active elevation > 100 degrees. They point out that this conservative procedure offers an alternative to more complex procedures in the management of irreparable rotator cuff tears.

Comment: Currently surgeons are actively pursing a variety of methods for managing patients with symptomatic irreparable rotator cuff tears, including marginal convergence, patch grafts, superior capsular reconstructions, degrading subacromial 'balloons' tendon transfers and reverse shoulder arthroplasty. Each of these procedures is more complex than the smooth and move procedure described in this article and none offers the opportunity for immediate postoperative resumption of active use of the shoulder.

These results from 151 patients having the smooth and move procedure can be contrasted to those from 24 patients having a 'superior capsular reconstruction' using an 8 mm fascia lata graft harvested from the patients thigh have been reported by Mihata et al (see this link). After the superior capsular reconstruction it is recommended that an abduction pillow be used for 4 weeks after the reconstruction with active exercises not started until 8 weeks after surgery.

Of note is that standard dermal grafts that used instead of fascial lata are often <2mm depending on the company selling them.

While future clinical research will hopefully clarify the indications for the superior capsular reconstruction and other more complex procedures, the advantages of the smooth and move procedure lie in its simplicity, its avoidance of tissue autograft or commercially available decellularized dermal allograft, its lack of postoperative 'down time', its high rate of durable improvement, and the fact that it does not preclude other surgical options should it fail to yield the desired result.

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We have a new set of shoulder youtubes about the shoulder, check them out at this link.

Be sure to visit "Ream and Run - the state of the art" regarding this radically conservative approach to shoulder arthritis at this link and this link

Use the "Search" box to the right to find other topics of interest to you.

How you can support progress in shoulder surgery

You may be interested in some of our most visited web pages  arthritis, total shoulder, ream and run, reverse total shoulder, CTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'

Shoulder range of motion - objective measurement

Can shoulder range of movement be measured accurately using the Microsoft Kinect sensor plus Medical Interactive Recovery Assistant software?

This study compared the accuracy of measuring shoulder range of movement with a simple laptop-sensor combination vs. trained observers (shoulder physiotherapists and shoulder surgeons) using motion capture (MoCap) laboratory equipment as the gold standard.

Shoulder movements of 49 healthy volunteers were simultaneously measured by trained observers, MoCap, and the MIRA device. Internal rotation was assessed with the shoulder abducted 90° and external rotation with the shoulder adducted. Visual estimation and MIRA measurements were compared with gold standard MoCap measurements for agreement using Bland-Altman methods.

There were 1670 measurements analyzed. The MIRA evaluations of all 4 cardinal shoulder movements were significantly more precise, with narrower limits of agreement than the measurements of trained observers. 

The authors concluded that a laptop combined with a Microsoft Kinect sensor can measure all cardinal shoulder movements with significantly closer agreement to Vicon MoCap than trained observer measurements.

This article builds on two prior studies:

Digital data acquisition of shoulder range of motion and arm motion smoothness using Kinect v2

These authors evaluated the accuracy of Kinect v2  as a digital tool for measuring shoulder ROM objectively and proposed a concept of motion smoothness reflecting the quality of arm motion.

In 10 male participants they measured the arm position in flexion, abduction, external rotation, and internal rotation) in three ways: (1)  Kinect v2, (2) a 3-dimensional (3D) motion analysis system, and (3) goniometry. Participants then performed a point-to point arm motion as naturally as possible. Kinematic data were collected with Kinect v2 and the 3D motion analysis system and then postprocessed to acquire parameters related to motion smoothness, including peak to mean velocity ratio, acceleration to movement time ratio, and number of peaks.

They found that Kinect v2 resulted in very good agreement of ROM measurement (r > 0.9) with the 3D motion analysis (95% limits of agreement < ±8°) compared with goniometry (95% limits of agreement <±10°). The Kinect v2 also showed a good correlation and agreement of measurement of motion quality parameters compared with the 3D motion analysis (peak to mean velocity ratio, acceleration to movement time ratio, and number of peaks.

The figures below show a comparison of a normal shoulder's motion with that of a patient with a cuff tear.

 What was particularly telling is the comparison of the precise measurements of motion by the Kinect in comparison to the highly variable measurements made with a goniometer.

Comment: This work builds on that previously presented:

Measurement of active shoulder motion using the Kinect, a commercially available infrared position detection system

These authors demonstrated the practicality of using an inexpensive, validated, commercially available infrared position sensor, the Kinect, for the observer-independent recording of the active ranges of motion of patients' shoulders. This device - familiar to computer gamers - does not require the application of sensors or markers to the patient and functions well in the clothed subject.

When mounted to a wheeled frame along with a laptop computer, the Kinect can be easily moved from one examination room to another. 

The Kinect outputs numerical data that can also be represented as a stick figure. The device measures the angles between the arm (A) and the trunk (T), automatically correcting for the patient leaning to one side or the other.

In 10 control subjects, they compared Kinect motion measurements to measurements made on standardized anteroposterior and lateral photographs taken concurrently. The Kinect measurements strongly agreed with photographic measurements. 

In 51 patients, they correlated active motion with the ability to perform the functions of the Simple Shoulder Test (SST). The total SST score was strongly correlated with the range of active abduction. The ability to perform each of the individual SST functions was strongly correlated with active motion. 

The active motion in well-functioning patient shoulders averaged 155° ± 22° abduction, 159° ± 14° flexion, 76° ± 18° external rotation in abduction, −59° ± 25° internal rotation in abduction, and −3.3 ± 3.7 inches of cross-body adduction, values similar to the control shoulders. 

Use of the Kinect system was practical in clinical examination rooms, requiring <5 minutes to document the 5 motions in both shoulders.

Comment: The shoulder's ability to participate in sports and activities of daily living depends on its active range of motion. Because of inter-observer variability, range of motion measurements with a goniometer are of limited utility in rigorously assessing limitation of motion and the effectiveness of treatment. The use of an objective system for the observer-independent measurement of active shoulder motion - such as the Kinect - holds promise for clarifying the indications for and the results of therapeutic interventions designed to improve shoulder function and for the comparison of results among surgeon-scientists.

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The reader may also be interested in these posts:

Healing through joint replacement

Consultation for those who live a distance away from Seattle.

Click here to see the new Shoulder Arthritis Book.

Click here to see the new Rotator Cuff Book

Information about shoulder exercises can be found at this link.

Use the "Search" box to the right to find other topics of interest to you.

You may be interested in some of our most visited web pages including:shoulder arthritis, total shoulder, ream and run, reverse total shoulder, CTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'

See from which cities our patients come.

See the countries from which our readers come on this post.

Assessing shoulder function: subjective, objective or both?

Relationship Between Patient-Reported Assessment of Shoulder Function and Objective Range-of Motion Measurements

These authors asked three questions:

(1) How does subjective patient assessment of shoulder function correlate with objectively measured active shoulder range of motion? 

(2) What is the difference in active motion between shoulders that can and those that cannot be used to perform each of the functions of the Simple Shoulder Test (SST see this link)? and

(3) Does the relationship between subjective and objective assessment of shoulder function differ between male and female patients?

In 74 male and 30 female patients with osteoarthritis they analyzed the relationship between the SST patient self-assessments of shoulder function  and objective range-of-motion measurements recorded by the observer-independent Kinect motion capture system

For both female and male patients, they found a poor correlation between objective measurements of active abduction and the total SST scores of osteoarthritic shoulders (square symbols). The relationships between active abduction and total SST score were closer for the contralateral shoulders (diamond symbols).

For all shoulders combined there was essentially no difference in these relationships for female (square symbols) and male (diamond symbols). 

They found a significant difference in active abduction between the osteoarthritic shoulders that allowed and those that did not allow the patient to perform the individual SST functions for only 4 of the 12 functions in the female group and 5 of 12 in the male group because of the highly variable relationship between self-assessed function and active abduction. 

In contrast, when the contralateral shoulders were assessed, this difference was found to be significant for 10 of the 12 functions in the female group and all 12 of the functions in the male group. 

Comment: One of the challenges in the measurement of passive and active shoulder motion is that these "objective" measurements have been shown to be observer-dependent. This study used an observer-independent method for measuring the range of active shoulder motion. 

The key finding in this study was that the active range of motion correlated poorly with the patients' self-assessed function of their osteoarthritic shoulders, meaning that the shoulder function was dependent on characteristics of the shoulder and the patient other than the active range of motion.

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Consultation for those who live a distance away from Seattle.

Click here to see the new Shoulder Arthritis Book

Click here to see the new Rotator Cuff Book

Use the "Search" box to the right to find other topics of interest to you.

You may be interested in some of our most visited web pages including:shoulder arthritis, total shoulder, ream and run, reverse total shoulder, CTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'

See from which cities our patients come.

See the countries from which our readers come on this post.

Objective measurement of shoulder motion

Digital data acquisition of shoulder range of motion and arm motion smoothness using Kinect v2


These authors evaluated the accuracy of Kinect v2  as a digital tool for measuring shoulder ROM objectively and proposed a concept of motion smoothness reflecting the quality of arm motion.

In 10 male participants they measured the arm position in flexion, abduction, external rotation, and internal rotation) in three ways: (1)  Kinect v2, (2) a 3-dimensional (3D) motion analysis system, and (3) goniometry. Participants then performed a point-to point arm motion as naturally as possible. Kinematic data were collected with Kinect v2 and the 3D motion analysis system and then postprocessed to acquire parameters related to motion smoothness, including peak to mean velocity ratio, acceleration to movement time ratio, and number of peaks.

They found that Kinect v2 resulted in very good agreement of ROM measurement (r > 0.9) with the 3D motion analysis (95% limits of agreement < ±8°) compared with goniometry (95% limits of agreement <±10°). The Kinect v2 also showed a good correlation and agreement of measurement of motion quality parameters compared with the 3D motion analysis (peak to mean velocity ratio, acceleration to movement time ratio, and number of peaks.

The figures below show a comparison of a normal shoulder's motion with that of a patient with a cuff tear.

 What was particularly telling is the comparison of the precise measurements of motion by the Kinect in comparison to the highly variable measurements made with a goniometer.

Comment: This work builds on that previously presented:

Measurement of active shoulder motion using the Kinect, a commercially available infrared position detection system

These authors demonstrated the practicality of using an inexpensive, validated, commercially available infrared position sensor, the Kinect, for the observer-independent recording of the active ranges of motion of patients' shoulders. This device - familiar to computer gamers - does not require the application of sensors or markers to the patient and functions well in the clothed subject.

When mounted to a wheeled frame along with a laptop computer, the Kinect can be easily moved from one examination room to another. 

The Kinect outputs numerical data that can also be represented as a stick figure. The device measures the angles between the arm (A) and the trunk (T), automatically correcting for the patient leaning to one side or the other.

In 10 control subjects, they compared Kinect motion measurements to measurements made on standardized anteroposterior and lateral photographs taken concurrently. The Kinect measurements strongly agreed with photographic measurements. 

In 51 patients, they correlated active motion with the ability to perform the functions of the Simple Shoulder Test (SST). The total SST score was strongly correlated with the range of active abduction. The ability to perform each of the individual SST functions was strongly correlated with active motion. 

The active motion in well-functioning patient shoulders averaged 155° ± 22° abduction, 159° ± 14° flexion, 76° ± 18° external rotation in abduction, −59° ± 25° internal rotation in abduction, and −3.3 ± 3.7 inches of cross-body adduction, values similar to the control shoulders. 

Use of the Kinect system was practical in clinical examination rooms, requiring <5 minutes to document the 5 motions in both shoulders.

Comment: The shoulder's ability to participate in sports and activities of daily living depends on its active range of motion. Because of inter-observer variability, range of motion measurements with a goniometer are of limited utility in rigorously assessing limitation of motion and the effectiveness of treatment. The use of an objective system for the observer-independent measurement of active shoulder motion - such as the Kinect - holds promise for clarifying the indications for and the results of therapeutic interventions designed to improve shoulder function and for the comparison of results among surgeon-scientists.

===

Consultation for those who live a distance away from Seattle.

Click here to see the new Shoulder Arthritis Book

Click here to see the new Rotator Cuff Book

Use the "Search" box to the right to find other topics of interest to you.

You may be interested in some of our most visited web pages including:shoulder arthritis, total shoulder, ream and run, reverse total shoulder, CTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'

See from which cities our patients come.

See the countries from which our readers come on this post.

Active range of shoulder motion - objective measurement with the Kinect

Measurement of active shoulder motion using the Kinect, a commercially available infrared position detection system

These authors demonstrated the practicality of using an inexpensive, validated, commercially available infrared position sensor, the Kinect, for the observer-independent recording of the active ranges of motion of patients' shoulders. This device - familiar to computer gamers - does not require the application of sensors or markers to the patient and functions well in the clothed subject.

When mounted to a wheeled frame along with a laptop computer, the Kinect can be easily moved from one examination room to another. 

The Kinect outputs numerical data that can also be represented as a stick figure. The device measures the angles between the arm (A) and the trunk (T), automatically correcting for the patient leaning to one side or the other.

In 10 control subjects, they compared Kinect motion measurements to measurements made on standardized anteroposterior and lateral photographs taken concurrently. The Kinect measurements strongly agreed with photographic measurements. 

In 51 patients, they correlated active motion with the ability to perform the functions of the Simple Shoulder Test (SST). The total SST score was strongly correlated with the range of active abduction. The ability to perform each of the individual SST functions was strongly correlated with active motion. 

The active motion in well-functioning patient shoulders averaged 155° ± 22° abduction, 159° ± 14° flexion, 76° ± 18° external rotation in abduction, −59° ± 25° internal rotation in abduction, and −3.3 ± 3.7 inches of cross-body adduction, values similar to the control shoulders. 

Use of the Kinect system was practical in clinical examination rooms, requiring <5 minutes to document the 5 motions in both shoulders.

Comment: The shoulder's ability to participate in sports and activities of daily living depends on its active range of motion. Because of inter-observer variability, range of motion measurements with a goniometer are of limited utility in rigorously assessing limitation of motion and the effectiveness of treatment. The use of an objective system for the observer-independent measurement of active shoulder motion - such as the Kinect - holds promise for clarifying the indications for and the results of therapeutic interventions designed to improve shoulder function and for the comparison of results among surgeon-scientists.

===

Consultation for those who live a distance away from Seattle.

Click here to see the new Shoulder Arthritis Book

Click here to see the new Rotator Cuff Book

Use the "Search" box to the right to find other topics of interest to you.

You may be interested in some of our most visited web pages including:shoulder arthritis, total shoulder, ream and run, reverse total shoulder, CTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'

See from which cities our patients come.

See the countries from which our readers come on this post.