Knee Surg Sports Traumatol Arthrosc DOI 10.1007/s00167-014-2857-0
SHOULDER
Correlation of clinical symptoms and function with fatty degeneration of infraspinatus in rotator cuff tear Joong-Bae Seo • Jae-Sung Yoo • Ho-Seong Jang • Jung-Sang Kim
Received: 5 July 2013 / Accepted: 18 January 2014 Ó Springer-Verlag Berlin Heidelberg 2014
Abstract Purpose The aim of this study was to analyse the correlation of clinical symptoms and function with the fatty degeneration of the infraspinatus in rotator cuff tears. Methods A total of 152 patients who had rotator cuff tears was enroled retrospectively. The infraspinatus muscle was divided into two compartments according to the bundle of fibres, and the patients were divided into four groups that reflected fatty degeneration. The muscle strength of the shoulder and clinical symptoms was investigated. Results The severity of the rotator cuff tear and retraction increased with fatty degeneration of both the superior and inferior parts in the infraspinatus muscles. Because of the increasing fatty degeneration of the superior part of the infraspinatus, the shoulder strength index (SSI) of abduction had poor results. Additionally, as the fatty degeneration of the inferior part of the infraspinatus increased, the SSI of abduction and external rotation had worse results. Conclusions Fatty degeneration of the superior part of the infraspinatus has no correlation with the power of external rotation but has a negative correlation with the power of abduction. Moreover, fatty degeneration of the inferior part of the infraspinatus has a negative correlation with both the power of abduction and external rotation. Level of evidence Retrospective study, Level IV.
J.-B. Seo (&) Kinesiologic medical science, Dankook University Graduate School, Cheoan, Korea e-mail: [email protected] J.-S. Yoo H.-S. Jang J.-S. Kim Department of Orthopaedic Surgery, Dankook University College of Medicine, 119, Dandae-ro Dongnam-gu, Cheonan-si, Chungnam 330-715, Republic of Korea
Keywords Infraspinatus Rotator cuff tear Fatty degeneration Atrophy
Introduction The rotator cuff consists of four muscles: the supraspinatus, the infraspinatus, the subscapularis and the teres minor. Each muscle acts together with the other rotator cuff muscles to give stability to the shoulder joint by maintaining the humeral head in the glenoid fossa. Regarding the function of these muscles, it is believed that the supraspinatus plays a main role in abduction and the infraspinatus and teres minor have the main role in external rotation [2, 3, 6]. Rotator cuff tear is one of the most common injuries in the shoulder [18]. It is generally accepted that the supraspinatus is the most frequently torn muscle and the tear usually occurs at its point of insertion into the humeral head at the greater tuberosity [4]. However, it is has been reported that the insertion of the infraspinatus reaches the anteriormost area of the greater tuberosity. These findings imply that the infraspinatus has a main role even in shoulder abduction and that most rotator cuff tears might involve the infraspinatus tendon. Recently, there have been some reports on re-evaluating the anatomical structure of the infraspinatus and its function [14, 15]. Kato et al. [7] reported in an anatomical investigation that the infraspinatus was composed of oblique and transverse parts according to the direction of the muscle fibres. Matsuki et al. [10] divided the infraspinatus muscle into 4 compartments and reported that the superior compartments of the infraspinatus are associated with anterior half tears of the rotator cuff and the inferior compartments are associated with posterior half tears of the rotator cuff. Many studies have reported on infraspinatus; however, not many
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Knee Surg Sports Traumatol Arthrosc Table 1 Patient’s data according to fatty degeneration of infraspinatus Fatty degeneration of infraspinatus upper fibre I (n = 89)
II (n = 41)
Fatty degeneration of infraspinatus lower fibre
III (n = 12)
IV (n = 10)
P value
I (n = 33)
II (n = 78)
III (n = 23)
IV (n = 18)
P value 0.057
Mean age
52.2 ± 8.1
57.7 ± 9.2
54.6 ± 8.2
58.4 ± 10.6
0.014
50.8 ± 7.7
54.5 ± 8.6
56.3 ± 10.5
57.3 ± 8.4
Sex (M:F)
62:27
14:27
5:7
4:6
0.001
28:5
37:41
12:11
10:8
0.002
Right/Left Dominant arm:Nondominant arm
66:23 63:26
37:4 31:10
11:1 12:0
10:0 6:4
0.040 N.S.
22:11 18:15
63:15 62:16
21:2 18:5
18:0 14:4
0.016 0.047
N.S. non-significant
studies have reported on the relation between the compartments of infraspinatus and clinical symptoms. We hypothesize that infraspinatus is composed of 2 compartments (superior and inferior) each compartment of infraspinatus has each functions. The aim of this study was to analyse the correlation of clinical symptoms and function with the fatty degeneration of the infraspinatus according to compartment in rotator cuff tears.
Materials and methods Following IRB exempt approval, a total of 152 patients with rotator cuff tears were enroled retrospectively from 2008 to 2012. All patients were diagnosed with the same kind of MRI so that they could be evaluated under the same conditions. The exclusion criteria were neuromuscular disease, biceps or labral lesions, shoulder instability, acromioclavicular joint arthritis, humeral head arthritis, adhesive capsulitis, bilateral shoulder disease and previous surgery on the affected shoulder. The subjects consisted of 86 men and 67 women, and their mean age was 54.3 years (27–77 years). Among which, there were 124 right rotator cuff tears and 28 left rotator cuff tears, and 112 were dominant arms and 40 were non-dominant arms (Table 1). Clinical and functional evaluation Visual analogue scale (VAS) scores of each patient were evaluated. Clinical symptoms for all patients were evaluated using the American Shoulder and Elbow Surgeons (ASES) scoring system and Korean shoulder society (KSS) scoring system. Muscle strength was tested using a spring scale myometer (Manley 2012 spring scale; Manley Tool and Machine, Independence, MO). Abduction and external rotation muscle power were evaluated. One side of spring is connected to a fixed column, and the other side is
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connected to the patient’s wrist. The maximum abduction strength was examined in the 90° abduction position parallel to the scapular plane, and the maximum external rotation strength was examined in the neutral position in which the elbow is attached to the body. We compared muscle strength using the shoulder strength index (SSI) [1]. Instead of using the absolute value of the muscle strength, we used the relative muscle strength of the affected shoulder compared with the muscle strength of the contralateral shoulder. Because normal muscle strength for each patient is totally different from that of others, comparison of the absolute values is meaningless. To calculate the SSI, the muscle strength of the affected shoulder is divided by the muscle strength of the contralateral shoulder. The strength of the muscle power of both shoulders should be evaluated consecutively to ensure reproducibility and reliability. Radiological evaluation Magnetic resonance imaging protocol included oblique coronal proton density-weighted and T2-weighted fat saturated spin-echo images (3,300/14–95 [repetition time ms/ echo time ms]; section thickness, 4 mm; intersection gap, 0.8 mm; field of view, 16 cm), oblique coronal T1weighted fat saturated spin-echo images (777/12 [repetition time ms/echo time ms]; section thickness, 3 mm; intersection gap, 0.6 mm; field of view, 16 cm); oblique sagittal T1-weighted spin-echo images (images (600/12 [repetition time ms/echo time ms]; section thickness, 4 mm; intersection gap, 1.2 mm; field of view, 16 cm) and transverse T1-weighted spin-echo images (images (600/12[repetition time ms/echo time ms]; section thickness, 3 mm; intersection gap, 0.9 mm; field of view, 16 cm). The size of the rotator cuff tear was measured using the maximum diameter of the tear in the oblique sagittal T2weighted images. When the width of a tear was too large to measure with one straight line over the convex humeral head, more than one straight line was drawn. The patients were
Knee Surg Sports Traumatol Arthrosc
Fig. 1 a After examining a series of consecutive oblique sagittal T2weighted images, the maximum AP diameter of a tear was measured. b When the width of a tear was too large to measure with one straight line over the convex humeral head, more than one straight line was drawn
Fig. 2 a After examining a series of consecutive coronal T2weighted images, the maximum medial-to-lateral diameter of retraction was measured. b When the width of retraction was too large to measure with one straight line over the convex humeral head, more than one straight line was drawn
Table 2 Measurement of the size and retraction of rotator cuff tear
(C20 mm, \25 mm), group e (C25 mm, \30 mm) and group f (C30 mm) (Fig. 2) (Table 2). Fatty degeneration of the infraspinatus was evaluated on the most lateral of the oblique sagittal T1-weighted images in which the scapular spine remained in contact with the scapular body [20]. The infraspinatus was divided into 2 compartments (superior part and inferior part) to identify the localization of the fatty degeneration of the infraspinatus (Fig. 3). In almost all cases, we could find the triangular shape of the superior part with a fatty infiltration pattern that extended from the mid-portion of the scapular spine to the mid-portion of the posterior margin of the infraspinatus. However, if the case did not have an obvious fatty infiltration pattern, we traced the shape of the muscle belly with the fatty infiltration pattern through serial oblique sagittal images to divide the superior part and inferior part (Fig. 4). Fatty degeneration of the infraspinatus was evaluated with Matsuki’s grading system [10]. Fatty degeneration in each compartment was graded on a scale of I–IV according to the ratio of muscle and extra-muscle fat: grade I, no atrophy; grade II, mild atrophy with more muscle than fat; grade III, moderate atrophy with equal amounts of fat and muscle and grade IV, severe atrophy with more fat than muscle.
The size of rotator cuff tear
The retraction of rotator cuff tear
\10 mm
Group A
Group a
C10 mm, \15 mm
Group B
Group b
C15 mm, \20 mm
Group C
Group c
C20 mm, \25 mm
Group D
Group d
C25 mm, \30 mm
Group E
Group e
C30 mm
Group F
Group f
divided into six groups reflecting the diameter: group A (\10 mm), group B (C10 mm,\15 mm), group C (C15 mm, \20 mm), group D (C20 mm,\25 mm), group E (C25 mm, \30 mm) and group F (C30 mm) (Fig. 1) (Table 2). The retraction of the rotator cuff tear was measured using the maximum diameter of the tear in the oblique coronal T2-weighted images. When the retraction of a tear was too large to measure with one straight line over the convex humeral head, more than one straight line was drawn. The patients were divided into six groups reflecting the diameter: group a (\10 mm), group b (C10 mm, \15 mm), group c (C15 mm, \20 mm), group d
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Knee Surg Sports Traumatol Arthrosc
Fig. 3 Infraspinatus muscle atrophy was evaluated with the oblique sagittal T1-weighted images. The region of interest was manually drawn on the border of the infraspinatus muscle, i.e. the inferior surface of the scapular spine, the posterior surface of the scapular spine, the posterior surface of the scapular body, the superior surface of the teres minor muscle and the anterior surface of the deltoid muscle. The region of interest was divided into two compartments by 1 line: the line was manually drawn on the inferior margin of the superior part. Muscle atrophy in each compartment was graded on a four-point scale. 1 superior part of infraspinatus, 2 inferior part of infraspinatus. Delt deltoid, SSC subscapularis, SSP suprascapularis, ISP infraspinatus and TM teres minor
All measurements of distance or areas described below were performed electronically on the MRI of the rotator cuff using the measurement software of the picture archiving and communication system (PACS). MR scans were repeatedly interpreted by a consensus read-out of two blinded observers to evaluate intra and interoberserver reliability. Fatty degeneration was determined as a measurement of the stage determined by two blinded observers on the sagittal MRI slices. In evaluation of fatty degeneration of the infraspinatus, both intraobserver reliability (j = 0.91) and interobserver reliability (j = 0.88) were ‘‘almost perfect agreement’’. IRB approval This study is approved by Dankook university medical IRB and the ID number of the approval was 2013-07-010. Statistic analysis Within each compartment, differences in the degree of fatty degeneration between the four groups were examined by Kruskal–Wallis test with a Mann–Whitney U test. Spearman’s correlation coefficient was used to estimate the correlation of fatty degeneration to outcome measures, strength, pain, tear size and severity of retraction. The weighted kappa (j) coefficient was used to estimate the interobserver reliability when evaluating the fatty degeneration of the infraspinatus. Interobserver reliability was classified according to
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Fig. 4 a Oblique sagittal T1-weighted image shows the triangular shape of the superior part with a fatty infiltration pattern that extended from the mid-portion of the scapular spine to the mid-portion of the posterior margin of the infraspinatus. b Tracing serial oblique sagittal images are helpful in finding the superior and inferior parts in some cases
the j coefficients: ‘‘slight agreement’’, 0.00–0.20; ‘‘fair agreement’’, 0.21–0.40; ‘‘moderate agreement’’, 0.41–0.60; ‘‘substantial agreement’’, 0.61–0.80 and ‘‘almost perfect agreement’’, 0.81–1.00. All statistical analyses were performed with SPSS version 19.0 (SPSS Inc., Chicago, II, USA), and the level of significance was set at P \ 0.05.
Results Correlation of fatty degeneration of the divided compartments of the infraspinatus with rotator cuff tear Fatty degeneration of the superior part of the infraspinatus was classified with 89 (58.6 %) cases as grade I, 41 (27.0 %) as grade II, 12 (7.9 %) as grade III and 10 (6.6 %)
0.294 Corr coeff Spearman’s rho correlation coefficients
0.396 \0.001 3.6 ± 1.7
0.002 2.3 ± 1.6
2.2 ± 1.4 1.8 ± 1.2
2.1 ± 1.7
0.393
0.329
\0.001 4.4 ± 1.7 3.3 ± 1.9
3.3 ± 2.2
4.4 ± 1.4
\0.001
II Corr coeff III
IV
P value
2.9 ± 1.8
The most important finding of the present study was correlation of the fatty degeneration of the divided compartments of the infraspinatus with SSI. Rotator cuff muscle atrophy and fatty degeneration are important determinants of clinical outcome following rotator cuff repairs [9, 12]. Severe atrophy and fatty degeneration may indicate poor reparability of torn cuff tendons [19]. Gladstone et al. [5] reported that muscle atrophy and fatty infiltration of the rotator cuff muscles play a significant role in determining functional outcome after cuff repair. Additionally, they suggested that
3.5 ± 1.9 2.8 ± 1.7 2.0 ± 1.3
2.1 ± 1.6
Tear size
Retraction
Discussion
3.2 ± 2.2
I II I
SSI has a negative correlation with the fatty degeneration of the superior part of the infraspinatus. However, SSI of external rotation has no relation with fatty degeneration of the superior part. Both SSI of abduction and external rotation has negative correlation with the fatty degeneration of the inferior part of the infraspinatus (Table 4).
Table 3 Correlation of tear size and retraction with muscle fatty degeneration
Correlation of the fatty degeneration of the divided compartments of the infraspinatus with shoulder function
III
Fatty degeneration of infraspinatus lower fibre
ASES and KSS scores have negative correlation with the fatty degeneration of the superior part and inferior part of the infraspinatus. However, VAS scores have no relation with fatty degeneration of the infraspinatus (Table 4).
Fatty degeneration of infraspinatus upper fibre
Correlation of the fatty degeneration of the divided compartments of the infraspinatus with clinical symptoms
IV
P value
as grade IV. Additionally, fatty degeneration of the inferior part of the infraspinatus was classified with 33 (21.7 %) cases as grade I, 78 (51.3 %) as grade II, 23 (15.1 %) as grade III and 18 (11.8 %) as grade IV. The size of the rotator cuff tear was classified with 62 (40.8 %) cases as group 1, 30 (19.7 %) as group 2, 23 (15.1 %) as group 3, 16 (10.5 %) as group 4, 8 (5.3 %) as group 5 and 13 (8.6 %) as group 6. The retraction of the rotator cuff tear was classified with 65 (42.8 %) cases as group 1, 26 (17.1 %) as group 2, 11 (7.2 %) as group 3, 25 (16.5 %) as group 4, 6 (4.0 %) as group 5 and 19(12.5 %) as group 6. Fatty degeneration of the superior and inferior parts of the infraspinatus both appear to positively influence the size of the rotator cuff tear. In addition, fatty degeneration of the superior and inferior parts of the infraspinatus both appear to positively influence the retraction of the rotator cuff tear (Table 3).
3.8 ± 1.7
Corr coeff
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Corr coeff Spearman’s rho correlation coefficients, SSI shoulder strength index, ABD abduction, ER external rotation, KSS Korean shoulder society, ASES American Shoulder and Elbow Surgeons, VAS visual analysis scale, N.S. non-significant
0.113
-0.541 \0.001
NS 6.2 ± 2.5
0.34 ± 0.15 0.53 ± 0.17
6.6 ± 2.0 6.2 ± 1.8
0.72 ± 0.14 0.75 ± 0.22
5.9 ± 2.1 0.010
-0.143 NS
NS 4.8 ± 2.8
0.61 ± 0.24 0.62 ± 0.23
6.1 ± 2.1
6.6 ± 1.5
0.61 ± 0.20 0.67 ± 0.21 SSI (ER)
VAS score
6.6 ± 1.4
-0.407 \0.001 0.44 ± 0.20 0.47 ± 0.18 0.62 ± 0.20 -0.548 0.50 ± 0.19 0.69 ± 0.18 SSI (ABD)
0.41 ± 0.14
0.37 ± 0.16
\0.001
0.71 ± 0.18
-0.267
-0.329
0.011
\0.001
49.4 ± 13.7
42.3 ± 12.3 34.6 ± 10.8
53.3 ± 11.9 57.7 ± 13.5
44.5 ± 12.9 51.6 ± 13.8
62.3 ± 12.4 -0.292
-0.250
0.003
0.007 43.4 ± 10.6
54.4 ± 11.0 49.8 ± 11.5
38.9 ± 9.8
52.6 ± 14.1 60.4 ± 12.9
47.5 ± 14.1
KSS score
ASES score
II Corr coeff P value IV III
Table 4 Correlation of functional outcomes with muscle fatty degeneration
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39.2 ± 12.4
I II I
III
Fatty degeneration of infraspinatus lower fibre Fatty degeneration of infraspinatus upper fibre
IV
P value
Corr coeff
Knee Surg Sports Traumatol Arthrosc
understanding the degree of muscle atrophy and fatty infiltration before surgery can help to guide patient’s expectations. Melis et al. [11] suggested that rotator cuff repair should be performed before the appearance of fatty infiltration (Stage 2) and atrophy (positive tangent sign), especially when the tear involves multiple tendons. There were many studies on fatty degeneration of the supraspinatus because it is generally accepted that the supraspinatus is the most frequently torn muscle [13, 16, 20]. Shen et al. [17] reported that fatty degeneration of the supraspinatus has a significant negative correlation with functional outcomes in 27 patients with full-thickness rotator cuff tears who underwent cuff repair. Melis et al. [11] suggested that the onset of symptoms in severe fatty infiltration of the supraspinatus is earlier than that of moderate fatty infiltration of the supraspinatus through a retrospective study with 1,688 patients. However, it is has been reported that the insertion of the infraspinatus reaches the anteriormost area of the greater tuberosity. These findings imply that the infraspinatus has a main role even in shoulder abduction and that most rotator cuff tears might involve the infraspinatus tendon. Recently, there have been some reports on re-evaluating the anatomical structure and function of the infraspinatus [8, 14, 15, 21]. Mochizuki et al. [15] reported in an anatomical investigation that the footprint of the supraspinatus was triangular in shape, with an average maximum medial-tolateral length of 6.9 mm and an average maximum anteroposterior width of 12.6 mm and the footprint of the infraspinatus was trapezoidal in shape, with an average maximum medial-to-lateral length of 10.2 mm and an average maximum anteroposterior width of 32.7 mm. Therefore, they suggested that the footprint of the supraspinatus on the greater tuberosity is much smaller than previously believed and this area of the greater tuberosity is actually occupied by a substantial amount of the infraspinatus. Recently, some authors have tried to analyse the compartments of the infraspinatus. Matsuki et al. [10] divided the infraspinatus into 4 compartments and investigated the relation of fatty degeneration for each compartment of the infraspinatus with rotator cuff tears. Kato et al. [7] reported in a cadaveric study that the infraspinatus was composed of the superior and inferior parts in accordance with the direction of the muscle part and the mean width of the superior part was 13.4 mm and that of the inferior part was 62.1 mm. They did a histological study showing that almost all of the tendinous portion of the infraspinatus is derived from the inferior part of the infraspinatus and the tendinous portion of the superior part is made up of thin membrane-like tissues, which attached to the tendinous portion of the oblique part. Therefore, Kato et al. [7] suggested that the inferior part of the infraspinatus mainly
Knee Surg Sports Traumatol Arthrosc
contributes to shoulder abduction and the superior part may have only a supportive role in the infraspinatus function. In this study, the superior and inferior parts were able to be found on the most lateral of the oblique sagittal T1weighted images in which the scapular spine remained in contact with the scapular body as Kato et al. [7] suggested (Fig. 3). In the functional evaluation, fatty degeneration of the superior part of the infraspinatus has a negative correlation with SSI of abduction and fatty degeneration of the inferior part of the infraspinatus has a negative correlation with both SSI of abduction and external rotation. This result corresponds with the suggestion by Kato et al. [7] that the inferior part of the infraspinatus mainly contributes to the shoulder abduction. However, because fatty degeneration of the superior part of the infraspinatus has a negative correlation with SSI of abduction, it does not agree with the suggestion by Kato et al. [7]. Therefore, it is considered that the function of the superior part has not only just a supportive role in the infraspinatus function but also contributes to the abduction of the shoulder. Our study has the following limitations: first, our study has a small number of cases in each group because patients were divided into four groups according to fatty degeneration of the infraspinatus; second, interobserver reliability of determination of division of infraspinatus was not high. Furthermore, there is a lack of consensus regarding the definition of division of infraspinatus; third, we could not exclude the influence of other factors; we did not evaluate other factors (for example, atrophy or fatty degeneration of the supraspinatus) that could influence shoulder functions. Nevertheless, it is considered that this study is meaningful because the study attempted to analyse the correlation of clinical symptoms and function with fatty degeneration of the infraspinatus according to compartment in rotator cuff tear. This study could be helpful to understand anatomical structure and function of infraspinatus because the analysis of shoulder function in this study support the result of anatomical study of Kato et al. [7].
Conclusions Fatty degeneration of both the superior and inferior parts in the infraspinatus muscles has a positive correlation with the severity of the rotator cuff tear and retraction. In addition, fatty degeneration of the superior part of the infraspinatus has no correlation with the power of external rotation but has a negative correlation with the power of abduction. Fatty degeneration of the inferior part of the infraspinatus has a negative correlation with both the muscle strength of abduction and external rotation.
Acknowledgments This study was granted exemption by our Institutional Review Board. This article is granted from Dankook University, during the conducts of the study.
References 1. Carbonel I, Martinez AA, Aldea E, Ripalda J, Herrera A (2013) Outcome and structural integrity of rotator cuff after arthroscopic treatment of large and massive tears with double row technique: a 2-year followup. Adv Orthop 2013:914148 2. Colachis SC Jr, Strohm BR (1971) Effect of suprascauular and axillary nerve blocks on muscle force in upper extremity. Arch Phys Med Rehabil 52:22–29 3. Colachis SC Jr, Strohm BR, Brechner VL (1969) Effects of axillary nerve block on muscle force in the upper extremity. Arch Phys Med Rehabil 50:647–654 4. Gartsman GM, Khan M, Hammerman SM (1998) Arthroscopic repair of full-thickness tears of the rotator cuff. J Bone Joint Surg Am 80:832–840 5. Gladstone JN, Bishop JY, Lo IK, Flatow EL (2007) Fatty infiltration and atrophy of the rotator cuff do not improve after rotator cuff repair and correlate with poor functional outcome. Am J Sports Med 35:719–728 6. Inman VT, Saunders JB, Abbott LC (1996) Observations of the function of the shoulder joint. 1944. Clin Orthop Relat Res 330:3–12 7. Kato A, Nimura A, Yamaguchi K, Mochizuki T, Sugaya H, Akita K (2012) An anatomical study of the transverse part of the infraspinatus muscle that is closely related with the supraspinatus muscle. Surg Radiol Anat 34:257–265 8. Kolbe AB, Collins MS, Sperling JW (2012) Severe atrophy and fatty degeneration of the infraspinatus muscle due to isolated infraspinatus tendon tear. Skeletal Radiol 41:107–110 9. Liem D, Lichtenberg S, Magosch P, Habermeyer P (2007) Magnetic resonance imaging of arthroscopic supraspinatus tendon repair. J Bone Joint Surg Am 89:1770–1776 10. Matsuki K, Sugaya H, Watanabe A, Toyone T, Moriishi J, Mochizuki T, Akita K, Wada Y (2010) Infraspinatus muscle atrophy as a function of the sagittal extent of rotator cuff tears. Orthopedics 33:305 11. Melis B, DeFranco MJ, Chuinard C, Walch G (2010) Natural history of fatty infiltration and atrophy of the supraspinatus muscle in rotator cuff tears. Clin Orthop Relat Res 468: 1498–1505 12. Mellado JM, Calmet J, Olona M, Esteve C, Camins A, Del Perez Palomar L, Gine J, Sauri A (2005) Surgically repaired massive rotator cuff tears: MRI of tendon integrity, muscle fatty degeneration, and muscle atrophy correlated with intraoperative and clinical findings. AJR Am J Roentgenol 184:1456–1463 13. Meyer DC, Pirkl C, Pfirrmann CW, Zanetti M, Gerber C (2005) Asymmetric atrophy of the supraspinatus muscle following tendon tear. J Orthop Res 23:254–258 14. Mochizuki T, Sugaya H, Uomizu M, Maeda K, Matsuki K, Sekiya I, Muneta T, Akita K (2008) Humeral insertion of the supraspinatus and infraspinatus. New anatomical findings regarding the footprint of the rotator cuff. J Bone Joint Surg Am 90:962–969 15. Mochizuki T, Sugaya H, Uomizu M, Maeda K, Matsuki K, Sekiya I, Muneta T, Akita K (2009) Humeral insertion of the supraspinatus and infraspinatus. New anatomical findings regarding the footprint of the rotator cuff. Surgical technique. J Bone Joint Surg Am 91(Suppl 2 Pt 1):1–7 16. Schaefer O, Winterer J, Lohrmann C, Laubenberger J, Reichelt A, Langer M (2002) Magnetic resonance imaging for
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Knee Surg Sports Traumatol Arthrosc supraspinatus muscle atrophy after cuff repair. Clin Orthop Relat Res 403:93–99 17. Shen PH, Lien SB, Shen HC, Lee CH, Wu SS, Lin LC (2008) Long-term functional outcomes after repair of rotator cuff tears correlated with atrophy of the supraspinatus muscles on magnetic resonance images. J Shoulder Elbow Surg 17:1S–7S 18. Strobel K, Hodler J, Meyer DC, Pfirrmann CW, Pirkl C, Zanetti M (2005) Fatty atrophy of supraspinatus and infraspinatus muscles: accuracy of US. Radiology 237:584–589 19. Sugihara T, Nakagawa T, Tsuchiya M, Ishizuki M (2003) Prediction of primary reparability of massive tears of the rotator cuff
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on preoperative magnetic resonance imaging. J Shoulder Elbow Surg 12:222–225 20. Thomazeau H, Rolland Y, Lucas C, Duval JM, Langlais F (1996) Atrophy of the supraspinatus belly. Assessment by MRI in 55 patients with rotator cuff pathology. Acta Orthop Scand 67: 264–268 21. Yamaguchi H, Suenaga N, Oizumi N, Hosokawa Y, Kanaya F (2012) Will preoperative atrophy and Fatty degeneration of the shoulder muscles improve after rotator cuff repair in patients with massive rotator cuff tears? Adv Orthop 2012:195876
SHOULDER
Correlation of clinical symptoms and function with fatty degeneration of infraspinatus in rotator cuff tear Joong-Bae Seo • Jae-Sung Yoo • Ho-Seong Jang • Jung-Sang Kim
Received: 5 July 2013 / Accepted: 18 January 2014 Ó Springer-Verlag Berlin Heidelberg 2014
Abstract Purpose The aim of this study was to analyse the correlation of clinical symptoms and function with the fatty degeneration of the infraspinatus in rotator cuff tears. Methods A total of 152 patients who had rotator cuff tears was enroled retrospectively. The infraspinatus muscle was divided into two compartments according to the bundle of fibres, and the patients were divided into four groups that reflected fatty degeneration. The muscle strength of the shoulder and clinical symptoms was investigated. Results The severity of the rotator cuff tear and retraction increased with fatty degeneration of both the superior and inferior parts in the infraspinatus muscles. Because of the increasing fatty degeneration of the superior part of the infraspinatus, the shoulder strength index (SSI) of abduction had poor results. Additionally, as the fatty degeneration of the inferior part of the infraspinatus increased, the SSI of abduction and external rotation had worse results. Conclusions Fatty degeneration of the superior part of the infraspinatus has no correlation with the power of external rotation but has a negative correlation with the power of abduction. Moreover, fatty degeneration of the inferior part of the infraspinatus has a negative correlation with both the power of abduction and external rotation. Level of evidence Retrospective study, Level IV.
J.-B. Seo (&) Kinesiologic medical science, Dankook University Graduate School, Cheoan, Korea e-mail: [email protected] J.-S. Yoo H.-S. Jang J.-S. Kim Department of Orthopaedic Surgery, Dankook University College of Medicine, 119, Dandae-ro Dongnam-gu, Cheonan-si, Chungnam 330-715, Republic of Korea
Keywords Infraspinatus Rotator cuff tear Fatty degeneration Atrophy
Introduction The rotator cuff consists of four muscles: the supraspinatus, the infraspinatus, the subscapularis and the teres minor. Each muscle acts together with the other rotator cuff muscles to give stability to the shoulder joint by maintaining the humeral head in the glenoid fossa. Regarding the function of these muscles, it is believed that the supraspinatus plays a main role in abduction and the infraspinatus and teres minor have the main role in external rotation [2, 3, 6]. Rotator cuff tear is one of the most common injuries in the shoulder [18]. It is generally accepted that the supraspinatus is the most frequently torn muscle and the tear usually occurs at its point of insertion into the humeral head at the greater tuberosity [4]. However, it is has been reported that the insertion of the infraspinatus reaches the anteriormost area of the greater tuberosity. These findings imply that the infraspinatus has a main role even in shoulder abduction and that most rotator cuff tears might involve the infraspinatus tendon. Recently, there have been some reports on re-evaluating the anatomical structure of the infraspinatus and its function [14, 15]. Kato et al. [7] reported in an anatomical investigation that the infraspinatus was composed of oblique and transverse parts according to the direction of the muscle fibres. Matsuki et al. [10] divided the infraspinatus muscle into 4 compartments and reported that the superior compartments of the infraspinatus are associated with anterior half tears of the rotator cuff and the inferior compartments are associated with posterior half tears of the rotator cuff. Many studies have reported on infraspinatus; however, not many
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Knee Surg Sports Traumatol Arthrosc Table 1 Patient’s data according to fatty degeneration of infraspinatus Fatty degeneration of infraspinatus upper fibre I (n = 89)
II (n = 41)
Fatty degeneration of infraspinatus lower fibre
III (n = 12)
IV (n = 10)
P value
I (n = 33)
II (n = 78)
III (n = 23)
IV (n = 18)
P value 0.057
Mean age
52.2 ± 8.1
57.7 ± 9.2
54.6 ± 8.2
58.4 ± 10.6
0.014
50.8 ± 7.7
54.5 ± 8.6
56.3 ± 10.5
57.3 ± 8.4
Sex (M:F)
62:27
14:27
5:7
4:6
0.001
28:5
37:41
12:11
10:8
0.002
Right/Left Dominant arm:Nondominant arm
66:23 63:26
37:4 31:10
11:1 12:0
10:0 6:4
0.040 N.S.
22:11 18:15
63:15 62:16
21:2 18:5
18:0 14:4
0.016 0.047
N.S. non-significant
studies have reported on the relation between the compartments of infraspinatus and clinical symptoms. We hypothesize that infraspinatus is composed of 2 compartments (superior and inferior) each compartment of infraspinatus has each functions. The aim of this study was to analyse the correlation of clinical symptoms and function with the fatty degeneration of the infraspinatus according to compartment in rotator cuff tears.
Materials and methods Following IRB exempt approval, a total of 152 patients with rotator cuff tears were enroled retrospectively from 2008 to 2012. All patients were diagnosed with the same kind of MRI so that they could be evaluated under the same conditions. The exclusion criteria were neuromuscular disease, biceps or labral lesions, shoulder instability, acromioclavicular joint arthritis, humeral head arthritis, adhesive capsulitis, bilateral shoulder disease and previous surgery on the affected shoulder. The subjects consisted of 86 men and 67 women, and their mean age was 54.3 years (27–77 years). Among which, there were 124 right rotator cuff tears and 28 left rotator cuff tears, and 112 were dominant arms and 40 were non-dominant arms (Table 1). Clinical and functional evaluation Visual analogue scale (VAS) scores of each patient were evaluated. Clinical symptoms for all patients were evaluated using the American Shoulder and Elbow Surgeons (ASES) scoring system and Korean shoulder society (KSS) scoring system. Muscle strength was tested using a spring scale myometer (Manley 2012 spring scale; Manley Tool and Machine, Independence, MO). Abduction and external rotation muscle power were evaluated. One side of spring is connected to a fixed column, and the other side is
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connected to the patient’s wrist. The maximum abduction strength was examined in the 90° abduction position parallel to the scapular plane, and the maximum external rotation strength was examined in the neutral position in which the elbow is attached to the body. We compared muscle strength using the shoulder strength index (SSI) [1]. Instead of using the absolute value of the muscle strength, we used the relative muscle strength of the affected shoulder compared with the muscle strength of the contralateral shoulder. Because normal muscle strength for each patient is totally different from that of others, comparison of the absolute values is meaningless. To calculate the SSI, the muscle strength of the affected shoulder is divided by the muscle strength of the contralateral shoulder. The strength of the muscle power of both shoulders should be evaluated consecutively to ensure reproducibility and reliability. Radiological evaluation Magnetic resonance imaging protocol included oblique coronal proton density-weighted and T2-weighted fat saturated spin-echo images (3,300/14–95 [repetition time ms/ echo time ms]; section thickness, 4 mm; intersection gap, 0.8 mm; field of view, 16 cm), oblique coronal T1weighted fat saturated spin-echo images (777/12 [repetition time ms/echo time ms]; section thickness, 3 mm; intersection gap, 0.6 mm; field of view, 16 cm); oblique sagittal T1-weighted spin-echo images (images (600/12 [repetition time ms/echo time ms]; section thickness, 4 mm; intersection gap, 1.2 mm; field of view, 16 cm) and transverse T1-weighted spin-echo images (images (600/12[repetition time ms/echo time ms]; section thickness, 3 mm; intersection gap, 0.9 mm; field of view, 16 cm). The size of the rotator cuff tear was measured using the maximum diameter of the tear in the oblique sagittal T2weighted images. When the width of a tear was too large to measure with one straight line over the convex humeral head, more than one straight line was drawn. The patients were
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Fig. 1 a After examining a series of consecutive oblique sagittal T2weighted images, the maximum AP diameter of a tear was measured. b When the width of a tear was too large to measure with one straight line over the convex humeral head, more than one straight line was drawn
Fig. 2 a After examining a series of consecutive coronal T2weighted images, the maximum medial-to-lateral diameter of retraction was measured. b When the width of retraction was too large to measure with one straight line over the convex humeral head, more than one straight line was drawn
Table 2 Measurement of the size and retraction of rotator cuff tear
(C20 mm, \25 mm), group e (C25 mm, \30 mm) and group f (C30 mm) (Fig. 2) (Table 2). Fatty degeneration of the infraspinatus was evaluated on the most lateral of the oblique sagittal T1-weighted images in which the scapular spine remained in contact with the scapular body [20]. The infraspinatus was divided into 2 compartments (superior part and inferior part) to identify the localization of the fatty degeneration of the infraspinatus (Fig. 3). In almost all cases, we could find the triangular shape of the superior part with a fatty infiltration pattern that extended from the mid-portion of the scapular spine to the mid-portion of the posterior margin of the infraspinatus. However, if the case did not have an obvious fatty infiltration pattern, we traced the shape of the muscle belly with the fatty infiltration pattern through serial oblique sagittal images to divide the superior part and inferior part (Fig. 4). Fatty degeneration of the infraspinatus was evaluated with Matsuki’s grading system [10]. Fatty degeneration in each compartment was graded on a scale of I–IV according to the ratio of muscle and extra-muscle fat: grade I, no atrophy; grade II, mild atrophy with more muscle than fat; grade III, moderate atrophy with equal amounts of fat and muscle and grade IV, severe atrophy with more fat than muscle.
The size of rotator cuff tear
The retraction of rotator cuff tear
\10 mm
Group A
Group a
C10 mm, \15 mm
Group B
Group b
C15 mm, \20 mm
Group C
Group c
C20 mm, \25 mm
Group D
Group d
C25 mm, \30 mm
Group E
Group e
C30 mm
Group F
Group f
divided into six groups reflecting the diameter: group A (\10 mm), group B (C10 mm,\15 mm), group C (C15 mm, \20 mm), group D (C20 mm,\25 mm), group E (C25 mm, \30 mm) and group F (C30 mm) (Fig. 1) (Table 2). The retraction of the rotator cuff tear was measured using the maximum diameter of the tear in the oblique coronal T2-weighted images. When the retraction of a tear was too large to measure with one straight line over the convex humeral head, more than one straight line was drawn. The patients were divided into six groups reflecting the diameter: group a (\10 mm), group b (C10 mm, \15 mm), group c (C15 mm, \20 mm), group d
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Fig. 3 Infraspinatus muscle atrophy was evaluated with the oblique sagittal T1-weighted images. The region of interest was manually drawn on the border of the infraspinatus muscle, i.e. the inferior surface of the scapular spine, the posterior surface of the scapular spine, the posterior surface of the scapular body, the superior surface of the teres minor muscle and the anterior surface of the deltoid muscle. The region of interest was divided into two compartments by 1 line: the line was manually drawn on the inferior margin of the superior part. Muscle atrophy in each compartment was graded on a four-point scale. 1 superior part of infraspinatus, 2 inferior part of infraspinatus. Delt deltoid, SSC subscapularis, SSP suprascapularis, ISP infraspinatus and TM teres minor
All measurements of distance or areas described below were performed electronically on the MRI of the rotator cuff using the measurement software of the picture archiving and communication system (PACS). MR scans were repeatedly interpreted by a consensus read-out of two blinded observers to evaluate intra and interoberserver reliability. Fatty degeneration was determined as a measurement of the stage determined by two blinded observers on the sagittal MRI slices. In evaluation of fatty degeneration of the infraspinatus, both intraobserver reliability (j = 0.91) and interobserver reliability (j = 0.88) were ‘‘almost perfect agreement’’. IRB approval This study is approved by Dankook university medical IRB and the ID number of the approval was 2013-07-010. Statistic analysis Within each compartment, differences in the degree of fatty degeneration between the four groups were examined by Kruskal–Wallis test with a Mann–Whitney U test. Spearman’s correlation coefficient was used to estimate the correlation of fatty degeneration to outcome measures, strength, pain, tear size and severity of retraction. The weighted kappa (j) coefficient was used to estimate the interobserver reliability when evaluating the fatty degeneration of the infraspinatus. Interobserver reliability was classified according to
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Fig. 4 a Oblique sagittal T1-weighted image shows the triangular shape of the superior part with a fatty infiltration pattern that extended from the mid-portion of the scapular spine to the mid-portion of the posterior margin of the infraspinatus. b Tracing serial oblique sagittal images are helpful in finding the superior and inferior parts in some cases
the j coefficients: ‘‘slight agreement’’, 0.00–0.20; ‘‘fair agreement’’, 0.21–0.40; ‘‘moderate agreement’’, 0.41–0.60; ‘‘substantial agreement’’, 0.61–0.80 and ‘‘almost perfect agreement’’, 0.81–1.00. All statistical analyses were performed with SPSS version 19.0 (SPSS Inc., Chicago, II, USA), and the level of significance was set at P \ 0.05.
Results Correlation of fatty degeneration of the divided compartments of the infraspinatus with rotator cuff tear Fatty degeneration of the superior part of the infraspinatus was classified with 89 (58.6 %) cases as grade I, 41 (27.0 %) as grade II, 12 (7.9 %) as grade III and 10 (6.6 %)
0.294 Corr coeff Spearman’s rho correlation coefficients
0.396 \0.001 3.6 ± 1.7
0.002 2.3 ± 1.6
2.2 ± 1.4 1.8 ± 1.2
2.1 ± 1.7
0.393
0.329
\0.001 4.4 ± 1.7 3.3 ± 1.9
3.3 ± 2.2
4.4 ± 1.4
\0.001
II Corr coeff III
IV
P value
2.9 ± 1.8
The most important finding of the present study was correlation of the fatty degeneration of the divided compartments of the infraspinatus with SSI. Rotator cuff muscle atrophy and fatty degeneration are important determinants of clinical outcome following rotator cuff repairs [9, 12]. Severe atrophy and fatty degeneration may indicate poor reparability of torn cuff tendons [19]. Gladstone et al. [5] reported that muscle atrophy and fatty infiltration of the rotator cuff muscles play a significant role in determining functional outcome after cuff repair. Additionally, they suggested that
3.5 ± 1.9 2.8 ± 1.7 2.0 ± 1.3
2.1 ± 1.6
Tear size
Retraction
Discussion
3.2 ± 2.2
I II I
SSI has a negative correlation with the fatty degeneration of the superior part of the infraspinatus. However, SSI of external rotation has no relation with fatty degeneration of the superior part. Both SSI of abduction and external rotation has negative correlation with the fatty degeneration of the inferior part of the infraspinatus (Table 4).
Table 3 Correlation of tear size and retraction with muscle fatty degeneration
Correlation of the fatty degeneration of the divided compartments of the infraspinatus with shoulder function
III
Fatty degeneration of infraspinatus lower fibre
ASES and KSS scores have negative correlation with the fatty degeneration of the superior part and inferior part of the infraspinatus. However, VAS scores have no relation with fatty degeneration of the infraspinatus (Table 4).
Fatty degeneration of infraspinatus upper fibre
Correlation of the fatty degeneration of the divided compartments of the infraspinatus with clinical symptoms
IV
P value
as grade IV. Additionally, fatty degeneration of the inferior part of the infraspinatus was classified with 33 (21.7 %) cases as grade I, 78 (51.3 %) as grade II, 23 (15.1 %) as grade III and 18 (11.8 %) as grade IV. The size of the rotator cuff tear was classified with 62 (40.8 %) cases as group 1, 30 (19.7 %) as group 2, 23 (15.1 %) as group 3, 16 (10.5 %) as group 4, 8 (5.3 %) as group 5 and 13 (8.6 %) as group 6. The retraction of the rotator cuff tear was classified with 65 (42.8 %) cases as group 1, 26 (17.1 %) as group 2, 11 (7.2 %) as group 3, 25 (16.5 %) as group 4, 6 (4.0 %) as group 5 and 19(12.5 %) as group 6. Fatty degeneration of the superior and inferior parts of the infraspinatus both appear to positively influence the size of the rotator cuff tear. In addition, fatty degeneration of the superior and inferior parts of the infraspinatus both appear to positively influence the retraction of the rotator cuff tear (Table 3).
3.8 ± 1.7
Corr coeff
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Corr coeff Spearman’s rho correlation coefficients, SSI shoulder strength index, ABD abduction, ER external rotation, KSS Korean shoulder society, ASES American Shoulder and Elbow Surgeons, VAS visual analysis scale, N.S. non-significant
0.113
-0.541 \0.001
NS 6.2 ± 2.5
0.34 ± 0.15 0.53 ± 0.17
6.6 ± 2.0 6.2 ± 1.8
0.72 ± 0.14 0.75 ± 0.22
5.9 ± 2.1 0.010
-0.143 NS
NS 4.8 ± 2.8
0.61 ± 0.24 0.62 ± 0.23
6.1 ± 2.1
6.6 ± 1.5
0.61 ± 0.20 0.67 ± 0.21 SSI (ER)
VAS score
6.6 ± 1.4
-0.407 \0.001 0.44 ± 0.20 0.47 ± 0.18 0.62 ± 0.20 -0.548 0.50 ± 0.19 0.69 ± 0.18 SSI (ABD)
0.41 ± 0.14
0.37 ± 0.16
\0.001
0.71 ± 0.18
-0.267
-0.329
0.011
\0.001
49.4 ± 13.7
42.3 ± 12.3 34.6 ± 10.8
53.3 ± 11.9 57.7 ± 13.5
44.5 ± 12.9 51.6 ± 13.8
62.3 ± 12.4 -0.292
-0.250
0.003
0.007 43.4 ± 10.6
54.4 ± 11.0 49.8 ± 11.5
38.9 ± 9.8
52.6 ± 14.1 60.4 ± 12.9
47.5 ± 14.1
KSS score
ASES score
II Corr coeff P value IV III
Table 4 Correlation of functional outcomes with muscle fatty degeneration
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39.2 ± 12.4
I II I
III
Fatty degeneration of infraspinatus lower fibre Fatty degeneration of infraspinatus upper fibre
IV
P value
Corr coeff
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understanding the degree of muscle atrophy and fatty infiltration before surgery can help to guide patient’s expectations. Melis et al. [11] suggested that rotator cuff repair should be performed before the appearance of fatty infiltration (Stage 2) and atrophy (positive tangent sign), especially when the tear involves multiple tendons. There were many studies on fatty degeneration of the supraspinatus because it is generally accepted that the supraspinatus is the most frequently torn muscle [13, 16, 20]. Shen et al. [17] reported that fatty degeneration of the supraspinatus has a significant negative correlation with functional outcomes in 27 patients with full-thickness rotator cuff tears who underwent cuff repair. Melis et al. [11] suggested that the onset of symptoms in severe fatty infiltration of the supraspinatus is earlier than that of moderate fatty infiltration of the supraspinatus through a retrospective study with 1,688 patients. However, it is has been reported that the insertion of the infraspinatus reaches the anteriormost area of the greater tuberosity. These findings imply that the infraspinatus has a main role even in shoulder abduction and that most rotator cuff tears might involve the infraspinatus tendon. Recently, there have been some reports on re-evaluating the anatomical structure and function of the infraspinatus [8, 14, 15, 21]. Mochizuki et al. [15] reported in an anatomical investigation that the footprint of the supraspinatus was triangular in shape, with an average maximum medial-tolateral length of 6.9 mm and an average maximum anteroposterior width of 12.6 mm and the footprint of the infraspinatus was trapezoidal in shape, with an average maximum medial-to-lateral length of 10.2 mm and an average maximum anteroposterior width of 32.7 mm. Therefore, they suggested that the footprint of the supraspinatus on the greater tuberosity is much smaller than previously believed and this area of the greater tuberosity is actually occupied by a substantial amount of the infraspinatus. Recently, some authors have tried to analyse the compartments of the infraspinatus. Matsuki et al. [10] divided the infraspinatus into 4 compartments and investigated the relation of fatty degeneration for each compartment of the infraspinatus with rotator cuff tears. Kato et al. [7] reported in a cadaveric study that the infraspinatus was composed of the superior and inferior parts in accordance with the direction of the muscle part and the mean width of the superior part was 13.4 mm and that of the inferior part was 62.1 mm. They did a histological study showing that almost all of the tendinous portion of the infraspinatus is derived from the inferior part of the infraspinatus and the tendinous portion of the superior part is made up of thin membrane-like tissues, which attached to the tendinous portion of the oblique part. Therefore, Kato et al. [7] suggested that the inferior part of the infraspinatus mainly
Knee Surg Sports Traumatol Arthrosc
contributes to shoulder abduction and the superior part may have only a supportive role in the infraspinatus function. In this study, the superior and inferior parts were able to be found on the most lateral of the oblique sagittal T1weighted images in which the scapular spine remained in contact with the scapular body as Kato et al. [7] suggested (Fig. 3). In the functional evaluation, fatty degeneration of the superior part of the infraspinatus has a negative correlation with SSI of abduction and fatty degeneration of the inferior part of the infraspinatus has a negative correlation with both SSI of abduction and external rotation. This result corresponds with the suggestion by Kato et al. [7] that the inferior part of the infraspinatus mainly contributes to the shoulder abduction. However, because fatty degeneration of the superior part of the infraspinatus has a negative correlation with SSI of abduction, it does not agree with the suggestion by Kato et al. [7]. Therefore, it is considered that the function of the superior part has not only just a supportive role in the infraspinatus function but also contributes to the abduction of the shoulder. Our study has the following limitations: first, our study has a small number of cases in each group because patients were divided into four groups according to fatty degeneration of the infraspinatus; second, interobserver reliability of determination of division of infraspinatus was not high. Furthermore, there is a lack of consensus regarding the definition of division of infraspinatus; third, we could not exclude the influence of other factors; we did not evaluate other factors (for example, atrophy or fatty degeneration of the supraspinatus) that could influence shoulder functions. Nevertheless, it is considered that this study is meaningful because the study attempted to analyse the correlation of clinical symptoms and function with fatty degeneration of the infraspinatus according to compartment in rotator cuff tear. This study could be helpful to understand anatomical structure and function of infraspinatus because the analysis of shoulder function in this study support the result of anatomical study of Kato et al. [7].
Conclusions Fatty degeneration of both the superior and inferior parts in the infraspinatus muscles has a positive correlation with the severity of the rotator cuff tear and retraction. In addition, fatty degeneration of the superior part of the infraspinatus has no correlation with the power of external rotation but has a negative correlation with the power of abduction. Fatty degeneration of the inferior part of the infraspinatus has a negative correlation with both the muscle strength of abduction and external rotation.
Acknowledgments This study was granted exemption by our Institutional Review Board. This article is granted from Dankook University, during the conducts of the study.
References 1. Carbonel I, Martinez AA, Aldea E, Ripalda J, Herrera A (2013) Outcome and structural integrity of rotator cuff after arthroscopic treatment of large and massive tears with double row technique: a 2-year followup. Adv Orthop 2013:914148 2. Colachis SC Jr, Strohm BR (1971) Effect of suprascauular and axillary nerve blocks on muscle force in upper extremity. Arch Phys Med Rehabil 52:22–29 3. Colachis SC Jr, Strohm BR, Brechner VL (1969) Effects of axillary nerve block on muscle force in the upper extremity. Arch Phys Med Rehabil 50:647–654 4. Gartsman GM, Khan M, Hammerman SM (1998) Arthroscopic repair of full-thickness tears of the rotator cuff. J Bone Joint Surg Am 80:832–840 5. Gladstone JN, Bishop JY, Lo IK, Flatow EL (2007) Fatty infiltration and atrophy of the rotator cuff do not improve after rotator cuff repair and correlate with poor functional outcome. Am J Sports Med 35:719–728 6. Inman VT, Saunders JB, Abbott LC (1996) Observations of the function of the shoulder joint. 1944. Clin Orthop Relat Res 330:3–12 7. Kato A, Nimura A, Yamaguchi K, Mochizuki T, Sugaya H, Akita K (2012) An anatomical study of the transverse part of the infraspinatus muscle that is closely related with the supraspinatus muscle. Surg Radiol Anat 34:257–265 8. Kolbe AB, Collins MS, Sperling JW (2012) Severe atrophy and fatty degeneration of the infraspinatus muscle due to isolated infraspinatus tendon tear. Skeletal Radiol 41:107–110 9. Liem D, Lichtenberg S, Magosch P, Habermeyer P (2007) Magnetic resonance imaging of arthroscopic supraspinatus tendon repair. J Bone Joint Surg Am 89:1770–1776 10. Matsuki K, Sugaya H, Watanabe A, Toyone T, Moriishi J, Mochizuki T, Akita K, Wada Y (2010) Infraspinatus muscle atrophy as a function of the sagittal extent of rotator cuff tears. Orthopedics 33:305 11. Melis B, DeFranco MJ, Chuinard C, Walch G (2010) Natural history of fatty infiltration and atrophy of the supraspinatus muscle in rotator cuff tears. Clin Orthop Relat Res 468: 1498–1505 12. Mellado JM, Calmet J, Olona M, Esteve C, Camins A, Del Perez Palomar L, Gine J, Sauri A (2005) Surgically repaired massive rotator cuff tears: MRI of tendon integrity, muscle fatty degeneration, and muscle atrophy correlated with intraoperative and clinical findings. AJR Am J Roentgenol 184:1456–1463 13. Meyer DC, Pirkl C, Pfirrmann CW, Zanetti M, Gerber C (2005) Asymmetric atrophy of the supraspinatus muscle following tendon tear. J Orthop Res 23:254–258 14. Mochizuki T, Sugaya H, Uomizu M, Maeda K, Matsuki K, Sekiya I, Muneta T, Akita K (2008) Humeral insertion of the supraspinatus and infraspinatus. New anatomical findings regarding the footprint of the rotator cuff. J Bone Joint Surg Am 90:962–969 15. Mochizuki T, Sugaya H, Uomizu M, Maeda K, Matsuki K, Sekiya I, Muneta T, Akita K (2009) Humeral insertion of the supraspinatus and infraspinatus. New anatomical findings regarding the footprint of the rotator cuff. Surgical technique. J Bone Joint Surg Am 91(Suppl 2 Pt 1):1–7 16. Schaefer O, Winterer J, Lohrmann C, Laubenberger J, Reichelt A, Langer M (2002) Magnetic resonance imaging for
123
Knee Surg Sports Traumatol Arthrosc supraspinatus muscle atrophy after cuff repair. Clin Orthop Relat Res 403:93–99 17. Shen PH, Lien SB, Shen HC, Lee CH, Wu SS, Lin LC (2008) Long-term functional outcomes after repair of rotator cuff tears correlated with atrophy of the supraspinatus muscles on magnetic resonance images. J Shoulder Elbow Surg 17:1S–7S 18. Strobel K, Hodler J, Meyer DC, Pfirrmann CW, Pirkl C, Zanetti M (2005) Fatty atrophy of supraspinatus and infraspinatus muscles: accuracy of US. Radiology 237:584–589 19. Sugihara T, Nakagawa T, Tsuchiya M, Ishizuki M (2003) Prediction of primary reparability of massive tears of the rotator cuff
123
on preoperative magnetic resonance imaging. J Shoulder Elbow Surg 12:222–225 20. Thomazeau H, Rolland Y, Lucas C, Duval JM, Langlais F (1996) Atrophy of the supraspinatus belly. Assessment by MRI in 55 patients with rotator cuff pathology. Acta Orthop Scand 67: 264–268 21. Yamaguchi H, Suenaga N, Oizumi N, Hosokawa Y, Kanaya F (2012) Will preoperative atrophy and Fatty degeneration of the shoulder muscles improve after rotator cuff repair in patients with massive rotator cuff tears? Adv Orthop 2012:195876
