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| ORIGINAL ARTICLE |
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| Year : 2018 | Volume
: 26
| Issue : 2 | Page : 94-99 |
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Ultrasonographic morphological changes in the prefemoral fat pad associated with knee osteoarthritis
Kazuyuki Shibata1, Kyoji Okada2, Masahiko Wakasa2, Isao Saito3, Akira Saito2, Yusuke Takahashi2, Hiromichi Sato2, Hitomi Takahashi4, Takeshi Kashiwagura5, Yoshiaki Kimura5
1 Department of Rehabilitation, Akita City Hospital; Department of Physical Therapy, Akita University Graduate School of Health Sciences, Akita, Japan
2 Department of Physical Therapy, Akita University Graduate School of Health Sciences, Akita, Japan
3 Division of Rehabilitation, Ugo Municipal Hospital, Ugo, Akita, Japan
4 Department of Rehabilitation, Akita City Hospital, Akita, Japan
5 Department of Orthopedic Surgery, Akita City Hospital, Akita, Japan
| Date of Submission | 18-Jul-2017 |
| Date of Acceptance | 14-Sep-2017 |
| Date of Web Publication | 12-Jun-2018 |
Correspondence Address:
Dr. Kazuyuki Shibata
Department of Rehabilitation, Akita City Hospital, 4-30 Kawamoto-Matsuoka-Cho, Akita 010-0933
Japan
 Source of Support: None, Conflict of Interest: None
DOI: 10.4103/JMU.JMU_15_17
Background: In normal knees, quadriceps contraction changes the shape of the prefemoral fat pad (PFP). However, in persons with knee osteoarthritis (OA), the functional or morphological changes of the PFP are unclear. This study aimed to clarify the morphological changes in the PFP in individuals with knee OA through ultrasonography. Materials and Methods: Participants were divided into the OA (36 knees; mean age, 74 years), elderly (31 knees; mean age, 70 years), and young (26 knees; mean age, 21 years) groups. The anteroposterior (AP) length of the PFP before and during isometric quadriceps contraction at 0°, 30°, 60°, and 90° knee flexion was measured ultrasonographically. The difference between the maximum and minimum length values, change in length, was also measured. These parameters were compared among the three groups. In the OA group, correlations between the parameters and clinical features (knee pain; visual analog scale, knee range of motion [ROM], Kellgren and Lawrence (K/L) grade, and intercondylar distance) were examined by Spearman and Pearson's correlation coefficient tests. Results: The AP lengths of the PFP before contraction were significantly lower in the OA group than in elderly group and young group at 30° (6.9 ± 2.5 vs. 12.0 ± 3.6 or 11.1 ± 2.7 mm, respectively; in order P = 0.014, P = 0.006) and 60° (6.5 ± 2.0 vs. 9.7 ± 2.5 or 9.1 ± 2.7 mm, respectively; both P < 0.001). The AP lengths of the PFP during contraction were significantly lower in the OA group than in elderly group and young group at 0° (6.7 ± 2.3 vs. 8.8 ± 3.7 or 9.1 ± 1.6 mm, respectively; both P < 0.001), 30° (7.9 ± 2.6 vs. 12.9 ± 3.7 or 13.0 ± 2.6 mm, respectively; both P < 0.001), and 60° (7.1 ± 2.5 vs. 13.5 ± 2.6 or 13.6 ± 3.0 mm, respectively; both P < 0.001). The change in length before maximum isometric quadriceps contraction was significantly lower in the knee OA group than in both elderly and young groups (3.3 ± 1.9 vs. 8.4 ± 2.5 or 6.8 ± 3.0 mm, respectively; both P < 0.001). The change in length during contraction was also significantly lower in the knee OA group than in both the elderly and young groups (3.9 ± 2.3 vs. 8.7 ± 2.3 or 8.9 ± 2.0 mm, respectively; both P < 0.001). In the OA group, change in length during contraction was significantly associated with knee pain (r = −0.476, P = 0.007), knee ROM (r = 0.388, P = 0.019), and Kellgren and Lawrence grade (r = −0.357, P = 0.045). Conclusions: In knee OA, movement of PFP was decreased more than healthy participants. In the knee OA group, the decrease of the morphological change of the PFP showed the relationship between VAS score, knee extension ROM, intercondylar distance (ICD), and K/L grade. An evaluation to the PFP may be required in individuals with knee OA. Keywords: Adipose tissue, osteoarthritis, knee, ultrasonography
How to cite this article:
Shibata K, Okada K, Wakasa M, Saito I, Saito A, Takahashi Y, Sato H, Takahashi H, Kashiwagura T, Kimura Y. Ultrasonographic morphological changes in the prefemoral fat pad associated with knee osteoarthritis. J Med Ultrasound 2018;26:94-9 |
How to cite this URL:
Shibata K, Okada K, Wakasa M, Saito I, Saito A, Takahashi Y, Sato H, Takahashi H, Kashiwagura T, Kimura Y. Ultrasonographic morphological changes in the prefemoral fat pad associated with knee osteoarthritis. J Med Ultrasound [serial online] 2018 [cited 2021 Apr 15];26:94-9. Available from: http://www.jmuonline.org/text.asp?2018/26/2/94/234306 |
| Introduction | |  |
Osteoarthritis (OA) is a common musculoskeletal disease in the elderly. Pain and quadriceps weakness are well-known characteristics of knee OA [1] and affect walking ability and activity of daily living.[2] In persons aged above 40 years in Japan, the prevalence of knee OA is 42.6% in men and 62.4% in women, respectively, and a total of 25.3 million people (8.6 million men and 16.7 million women) are possibly affected by this condition.[3]
Many causes of knee OA have been considered in the literature.[4],[5],[6],[7] Distel et al.[8] and Ballegaard et al.[9] implicated fat pads as one of the causes. There are three fat pads in the knee joint, the infrapatellar fat pad (IFP), quadriceps fat pad, and prefemoral fat pad (PFP). Of these, the IFP has been widely investigated by several authors.[10],[11],[12],[13] The chemical effects of IFP were also recently noted.[8],[9]
PFP supports the sliding of the suprapatellar bursa (SB) during the isometric contraction of the quadriceps [14] since it is located between the SB and femur.
However, the relationship between PFP and knee OA is unclear. The purpose of the present study was to clarify the morphological changes in the PFP in individuals with knee OA and elderly persons without knee OA and to examine any correlations between PFP motion change and clinical or physical features of knee OA.
Participants
Twenty-five participants with knee OA were enrolled in the present study (9 men, 16 women, mean age 74 years, mean body mass index [BMI] 26.6 kg/m 2; 95% confidence interval [CI] 24.8–28.5). They were diagnosed as having knee OA based on clinical knee symptoms and knee radiography, namely, knee pain, swelling, poor range of motion (ROM), lost joint space, deformities, and osteophyte. In the radiographic findings, cases graded as 2, 3, or 4 on the Kellgren and Lawrence (K/L) grade [15] were included. Among the 25 participants, 11 had bilateral knee OA and 14 had unilateral knee OA. Consequently, 36 knees were examined as the knee OA group.
Thirty-one knees of 18 healthy elderly individuals (5 men, 13 women, mean age 70 years, mean BMI 22.3 kg/m 2; 95% CI 21.0–23.5) were classified as the elderly group. Twenty-six knees of 14 young and healthy participants (8 men, 6 women, mean age 21 years, mean BMI 21.5 kg/m 2; 95% CI 20.6–22.3) were classified as the young group. In the elderly and the young groups, persons having any symptom or deformity around the knees, knee pain, obvious deformity, orthopedic or neuromuscular disorder in the lower limb, and wear or irregularity of the femoral cartilage discovered through ultrasonographic survey [16] were excluded. This study was carried out based on the “Helsinki Declaration” (October 2008, Seoul, revised). In addition, personal information was handled according to the Personal Information Protection Law and participant privacy was protected. We confirmed that participants understood the study's purpose and obtained written informed consent. This study received the approval of the Municipal Akita City Hospital Ethical Review Board in 2014 (approval number 12).
| Materials and Methods | | |
Ultrasound image recording
We used a B-mode ultrasound device (HI VISION Noblus, Hitachi Aloka Medical, Mitaka city, Tokyo, Japan) and a 13-4 MHz transducer. The long axial view was obtained by placing the transducer on the line from the anterosuperior iliac spine to the center of the patella.[14],[17] In the sitting position, the participants' knees were fixed at 0°, 30°, 60°, and 90° flexion using an isometric knee musculometer (Hydromusculator GT160, OG Giken, Okayama city, Okayama, Japan). PFP was examined before and during maximum isometric quadriceps contraction at each knee flexion position [Figure 1]. | Figure 1: Ultrasound images showing the prefemoral fat pad and suprapatellar bursa (knee extension position). A: Healthy elderly person at rest, B: Healthy elderly person during isometric quadriceps contraction, C: Knee OA at rest, D: Knee OA during isometric quadriceps contraction. OA: Osteoarthritis, QT: Quadriceps tendon. *In knee OA, knee effusion in the suprapatellar bursa was observed
Click here to view |
Ultrasound image analysis
The anteroposterior (AP) lengths of the PFP and the SB before and during maximum isometric quadriceps contraction were measured from the ultrasound images. The PFP was observed between the surface of the femur and deep layer of the SB. From the PFP length, before the contraction at 0°, 30°, 60°, and 90° flexed position, the maximum and the minimum AP lengths were selected. Afterward, the difference between the maximum value and minimum value AP length was calculated and expressed as the “change in length.” Similarly, the change in length was calculated from PFP values during the maximum isometric quadriceps contraction. The change in length indicates that how much AP length was changed due to the change in knee angle.
The existence of knee effusion was defined as when the AP length of the SB from the ultrasound images exceeded 2 mm,[18] and the knee OA group was further divided into the effusion and the no-effusion groups. The AP length and change in PFP length were compared between the knee OA, elderly, and young groups. These parameters were also compared between the effusion and no-effusion groups in the knee OA group.
Clinical and physical assessments
Knee pain was evaluated using the 100-mm visual analog scale (VAS).[19] The participants marked the point on the scale which indicated the maximum intensity of knee pain they felt recently. The distance, in the standing position, between the medial femoral condyles on both limbs was measured as the ICD.[20] Maximum knee flexion and extension angles were measured in the supine position using a standard goniometer (OG giken, Okayama city, Okayama, Japan).
Statistical analysis
Statistical analyses were performed using SPSS Statistics version 21 (IBM, Chuo Ward, Tokyo, Japan). The assumption of normality was assessed by the Shapiro–Wilk test.
The AP length of the PFP before and during the quadriceps contraction, length change, and AP length of the SB was analyzed using one-way ANOVA and Tukey's multiple comparison tests among the knee OA, elderly, and young groups. The AP length of the PFP was compared between before and during the quadriceps contraction using paired t- tests. In the knee OA group, the parameters were compared between the knee effusion and no-knee effusion groups using student's t-tests.
Spearman and Pearson's correlation coefficient tests were used to assess the relationship between parameters of PFP and knee effusion and for other clinical and physical assessments. The level of significance was set at P < 0.05.
| Results | | |
The anteroposterior length of the prefemoral fat pad
The AP length of the PFP before maximum isometric quadriceps contraction was significantly lower in the knee OA group than in the elderly or the young groups at 30° (6.9; 95% CI 6.0–7.7 vs. 12.0; 95% CI 10.7–13.4 or 11.1; 95% CI 10.0–12.2 mm, respectively; in order P = 0.014, P = 0.006) and 60° (6.5; 95% CI 5.8–7.2 vs. 9.7; 95% CI 8.7–10.6 or 9.1; 95% CI 8.0–10.2 mm, respectively; both P < 0.001). There was no difference between the elderly and young groups regarding any knee angles. The AP length of the PFP during contraction was significantly lower in the knee OA group than in the elderly or young groups at 0° (6.7; 95% CI 5.7–7.6 vs. 8.8; 95% CI 7.5–10.2 or 9.1; 95% CI 8.5–9.8 mm, respectively; both P < 0.001), 30° (7.9; 95% CI 7.0–8.8 vs. 12.9; 95% CI 11.6–14.3 or 13.0; 95% CI 12.0–14.1 mm, respectively; both P < 0.001), and 60° (7.1; 95% CI 6.2–7.9 vs. 13.5; 95% CI 12.5–14.5 or 13.6; 95% CI 12.4–14.8 mm, respectively; both P < 0.001). There was no difference between the elderly and young groups regarding any knee angles. In the young group, the AP length of the PFP before contraction was significantly lower than during the contraction for each knee angle. Similarly, in the elderly group, these differences were observed at 0°, 60°, and 90° knee flexion. In the knee OA group, there was no significant difference in AP length between before and during contraction at any knee angles [Figure 2]. | Figure 2: Anteroposterior length of the prefemoral fat pad (mean values ± standard deviation) at each knee flexion angle for (a) 0°, (b) 30°, (c) 60°, and (d) 90°. Anteroposterior length of the prefemoral fat pad was lower in the knee osteoarthritis group than in both the elderly or young groups at 0°, 30°, and 60°. There was a significant difference in anteroposterior length of the prefemoral fat pad between before and during the contraction in both the elderly and the young groups. White bar, before maximum isometric quadriceps contraction; black bar, during the contraction. *P < 0.05, **P < 0.001, #Significant difference between before and during the contraction at P < 0.01. OA: Osteoarthritis
Click here to view |
Change in length
The change in length before maximum isometric quadriceps contraction was significantly lower in the knee OA group than in both elderly and young groups (3.3; 95% CI 2.6–3.9 vs. 8.4; 95% CI 7.5–9.3 or 6.8; 95% CI 5.6–8.0 mm, respectively; both P < 0.001). Length change during contraction was also significantly lower in the knee OA group than in both the elderly and young groups (3.9; 95% CI 3.1–4.7 vs. 8.7; 95% CI 7.8–9.5 or 8.9; 95% CI 8.1–9.8 mm, respectively; both P < 0.001). There was no significant difference in length change between the elderly and the young groups [Figure 3]. | Figure 3: Change in prefemoral fat pad length in the knee osteoarthritis, elderly, and young groups. Change in length before the maximum isometric contraction (white bar) and during the contraction (black bar) was significantly lower in the knee Osteoarthritis group than in the elderly or young groups. **P < 0.001 (one-way ANOVA and Tukey's multiple comparison tests). OA: Osteoarthritis
Click here to view |
The anteroposterior length of the suprapatellar bursa
The AP length of the SB was significantly higher in the knee OA group than in the elderly and young groups (4.3; 95% CI 3.1–4.7 vs. 1.1; 95% CI 0.8–1.5 or 1.1; 95% CI 0.9–1.3 mm, respectively; both P < 0.001). No significant difference was found between the elderly and the young groups. The knee OA group was further divided into the effusion (26 knees, mean age 73 years) and no-effusion (10 knees, mean age 77 years) groups. The AP length of the PFP before and during the contraction was not significantly different between the effusion and no-effusion groups. The length change of the PFP before and during the contraction was significantly lower in the effusion group than in the no-effusion group (2.7; 95% CI 2.0–3.5 mm vs. 4.7; 95% CI 3.7–5.6 mm, 3.4; 95% CI 2.4–4.4 mm vs. 5.3; 95% CI 4.2–6.3 mm, respectively, in order P = 0.006, P = 0.008) [Figure 4]. | Figure 4: Change in prefemoral fat pad length in the effusion and no-effusion groups. Changes before maximum isometric quadriceps contraction (white bar) and during the contraction (black bar) were significantly lower in the effusion group than in the no-effusion group (a: P =0.006, b: P =0.008; respectively). OA: Osteoarthritis
Click here to view |
Correlations between prefemoral fat pad parameters and physical assessments in the knee osteoarthritis group
There was no significant correlation between AP length of the PFP before or during the contraction and physical assessments, namely, VAS score, knee ROM, ICD, and K/L grade. The change in PFP length before the contraction was significantly associated with ICD. The change in PFP length during the contraction was significantly associated with VAS score, knee ROM, and K/L grade [Table 1]. | Table 1: Correlations between prefemoral fat pad parameters and clinical features
Click here to view |
| Discussion | | |
The anteroposterior length of the prefemoral fat pad
Many reports have shown that white adipose tissue secretes inflammatory substances such as cytokines [21] in addition to its role as the storehouse of extra calories. Hoffa first reported a syndrome of infrapatellar fat pad (IFP) impingement in 1904.[11] The inflamed fat pad may be hypertrophied predisposing it to crushing or impingement between the femur and tibia and to further injury and inflammation.[12] Bohnsack et al.[22] suggested that the IFP played a role in stabilizing the patella in the extremes of knee motion. Subhawong et al.[23] reported that edema in IFP may be an important indicator of underlying patellofemoral maltracking or impingement, and there was a statistically significant association between the presence of IFP edema and PFP edema. Regarding PFP, Kim et al.[24] reported in their magnetic resonance imaging study that PFP could show an impingement between the anterior aspect of the distal femur and the patella undersurface and a mass-like fatty tissue protrusion from the PFP on the lateral femoral condyle caused mechanical symptoms. Dynamic motions of the PFP during isometric contraction of the quadriceps have been well described through ultrasonography.[14] The PFP may support the sliding of the SB during quadriceps contraction and knee flexion or extension since it is located between SB and femur. However, a correlation between PFP and knee disorders including knee OA has not been reported.
The present study showed that, in individuals with knee OA, AP length of the PFP did not change before and during maximum isometric quadriceps contraction for any knee angles from 0° to 90°. In contrast, in individuals without knee symptoms or deformity, the length significantly increased as the knee angle increased both before and during the contraction. Since these abnormal patterns of the length were observed only in the OA group, they are considered to cause by knee OA, and not aging. Since quadriceps weakness is occasionally present in individuals with knee OA,[25] quadriceps weakness may be related to decreased movement of PFP. In addition, the morphological change of PFP was also considered to be a cause of the decreased movement due to OA changes.
Change in length
Change in PFP length during knee motion from 0° to 90° was significantly lower in the OA group than in the elderly and young groups. Since the normal change in PFP length with passive motion was confirmed in the elderly group, the small length change in the OA group was related to knee OA. PFP is a fat pad within the knee joint, and its surrounding structures including the quadriceps muscle passively change its shape. Ultrasonography imaging could assess the fibrosis or atrophy of musculoskeletal structures.[26],[27],[28] Moreover, the decreased movement of the PFP may be associated with a longstanding limitation of ROM and/or pain in the OA group.
The anteroposterior length of the suprapatellar bursa
Effusion in the SB is one of the symptoms of knee OA. Ike et al.[29] found a significant correlation between the volumes of synovial fluid obtained in the knee joint and maximum depth (AP length) of the SB measured through ultrasound. Fahrer et al.[30] found that knee effusion reduced maximum isometric muscle strength because of reflex inhibition. Since the bursa exists adjacent to the PFP, effusion of the bursa might be associated with the motion and change of PFP. Actually, change in PFP length before and during the contraction was significantly lower in the effusion group than in the no-effusion group. Saavedra et al.[31] reported that the pressure exerted on the effusion by the quadriceps and patella pushes the fluid in knee flexion. This mechanism might be associated with a decrease in length change in the OA group. Inflammatory cytokine density in the synovial fluid is high in individuals with knee OA.[32],[33] Direct pressure and/or chemical agents from the effusion of the SB might affect PFP, resulting in the decreased change in length.
Correlations between prefemoral fat pad parameters and physical assessments in the knee osteoarthritis group
Change in length was significantly correlated with ICD representing varus deformity of the knee OA, although there was no significant correlation between the AP length of the PFP and several clinical features. Since knee varus deformity is a result of OA progression associated with the change of the soft tissue around the knee,[34],[35],[36] not only varus deformity but also changes in the PFP itself, might affect the decreased movement of the PFP. Moreover, the change in length was also related to the VAS score, knee ROM, and K/L grade. IFP has substance – P-containing fibers and their close relationship to its posterior synovial lining implicates IFP pathologies as a source of infrapatellar knee pain.[37] Clockaerts et al.[38] reported that adipose tissue secreting inflammatory agents in the IFP, which are in close contact with the synovial layers and articulating cartilage, play an important role in the etiopathogenesis of OA. IFP probably plays important roles in the development of knee disorders. However, there has not been any report mentioning PFP.
Study limitations
The present study had several limitations. First, the influence of muscle strength was not investigated and since PFP is adipose tissue, its movement or change of shape depends on muscle contraction. Muscle strength and its influences on the PFP are important. Furthermore, quantitative evaluation of PFP elasticity was not performed. Ultrasonography including echo intensity and/or elastographic measurement may be useful for analyzing PFP elasticity.
This study included bilateral knee OA; they were same participants in knee OA group. There may be a bias in the statistical analysis relationship between each knee and the individual characteristics such as age, BMI, and ICD.
| Conclusions | | |
As a result of quantitative evaluation of PFP using ultrasonography, the AP length of the PFP was lower in the knee OA than in the elderly and the young groups. The PFP of the knee OA was not able to confirm the morphological change of the PFP by knee joint movement and quadriceps contraction like as found in the elderly and the young groups. In the knee OA group, the decrease of the morphological change of the PFP showed the relationship between VAS score, knee extension ROM, ICD, and K/L grade. In addition, the existence of knee effusion was thought to reduce the change in length of the PFP by knee joint movement. Although these causal relationships should be further investigated, PFP evaluation seems important in clinical practice.
Acknowledgment
We would like to thank Editage (www.editage.jp) for English language editing. We also thank the staff in our hospital for useful discussions.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
| References | | |
| 1. | Sharma L, Dunlop DD, Cahue S, Song J, Hayes KW. Quadriceps strength and osteoarthritis progression in malaligned and lax knees. Ann Intern Med 2003;138:613-9.  [ PUBMED] |
| 2. | Demura T, Demura S, Uchiyama M, Sugiura H. Examination of factors affecting gait properties in healthy older adults: Focusing on knee extension strength, visual acuity, and knee joint pain. J Geriatr Phys Ther 2014;37:52-7. [ PUBMED] |
| 3. | Yoshimura N. Epidemiology of osteoarthritis in Japan: The ROAD study. Clin Calcium 2011;21:821-5. [ PUBMED] |
| 4. | Felson DT, Zhang Y, Hannan MT, Naimark A, Weissman B, Aliabadi P, et al. Risk factors for incident radiographic knee osteoarthritis in the elderly: The Framingham Study. Arthritis Rheum 1997;40:728-33. [ PUBMED] |
| 5. | McAlindon T, Zhang Y, Hannan M, Naimark A, Weissman B, Castelli W, et al. Are risk factors for patellofemoral and tibiofemoral knee osteoarthritis different? J Rheumatol 1996;23:332-7. [ PUBMED] |
| 6. | Muraki S, Akune T, Oka H, Ishimoto Y, Nagata K, Yoshida M, et al. Incidence and risk factors for radiographic knee osteoarthritis and knee pain in Japanese men and women: A longitudinal population-based cohort study. Arthritis Rheum 2012;64:1447-56. [ PUBMED] |
| 7. | Nishimura A, Hasegawa M, Kato K, Yamada T, Uchida A, Sudo A, et al. Risk factors for the incidence and progression of radiographic osteoarthritis of the knee among Japanese. Int Orthop 2011;35:839-43. |
| 8. | Distel E, Cadoudal T, Durant S, Poignard A, Chevalier X, Benelli C, et al. The infrapatellar fat pad in knee osteoarthritis: An important source of interleukin-6 and its soluble receptor. Arthritis Rheum 2009;60:3374-7. |
| 9. | Ballegaard C, Riis RG, Bliddal H, Christensen R, Henriksen M, Bartels EM, et al. Knee pain and inflammation in the infrapatellar fat pad estimated by conventional and dynamic contrast-enhanced magnetic resonance imaging in obese patients with osteoarthritis: A cross-sectional study. Osteoarthritis Cartilage 2014;22:933-40. [ PUBMED] |
| 10. | Dean BJ, Reed DW, Matthews JJ, Pandit H, McNally E, Athanasou NA, et al. The management of solitary tumours of Hoffa's fat pad. Knee 2011;18:67-70. [ PUBMED] |
| 11. | Hoffa A. The influence of adipose tissue with regard to pathology of the knee joint. J Am Med Assoc 1904;43:795-6. |
| 12. | Jacobson JA, Lenchik L, Ruhoy MK, Schweitzer ME, Resnick D. MR imaging of the infrapatellar fat pad of Hoffa. Radiographics 1997;17:675-91. [ PUBMED] |
| 13. | Kumar D, Alvand A, Beacon JP. Impingement of infrapatellar fat pad (Hoffa's disease): Results of high-portal arthroscopic resection. Arthroscopy 2007;23:1180-60. [ PUBMED] |
| 14. | Martinoli C. Musculoskeletal ultrasound: Technical guidelines. Insights Imaging 2010;1:99-141. [ PUBMED] |
| 15. | Kellgren JH, Lawrence JS. Radiological assessment of osteo-arthrosis. Ann Rheum Dis 1957;16:494-502. [ PUBMED] |
| 16. | Podlipská J, Koski JM, Pulkkinen P, Saarakkala S. In vivo quantitative ultrasound image analysis of femoral subchondral bone in knee osteoarthritis. ScientificWorldJournal 2013;2013:182562. |
| 17. | Bianchi S, Zwass A, Abdelwahab IF, Banderali A. Diagnosis of tears of the quadriceps tendon of the knee: Value of sonography. AJR Am J Roentgenol 1994;162:1137-40. [ PUBMED] |
| 18. | Hong BY, Lee JI, Kim HW, Cho YR, Lim SH, Ko YJ, et al. Detectable threshold of knee effusion by ultrasonography in osteoarthritis patients. Am J Phys Med Rehabil 2011;90:112-8. |
| 19. | McCormack HM, Horne DJ, Sheather S. Clinical applications of visual analogue scales: A critical review. Psychol Med 1988;18:1007-19. [ PUBMED] |
| 20. | Sass P, Hassan G. Lower extremity abnormalities in children. Am Fam Physician 2003;68:461-8. [ PUBMED] |
| 21. | Fain JN. Release of interleukins and other inflammatory cytokines by human adipose tissue is enhanced in obesity and primarily due to the nonfat cells. Vitam Horm 2006;74:443-77. [ PUBMED] |
| 22. | Bohnsack M, Hurschler C, Demirtas T, Rühmann O, Stukenborg-Colsman C, Wirth CJ, et al. Infrapatellar fat pad pressure and volume changes of the anterior compartment during knee motion: Possible clinical consequences to the anterior knee pain syndrome. Knee Surg Sports Traumatol Arthrosc 2005;13:135-41. |
| 23. | Subhawong TK, Eng J, Carrino JA, Chhabra A. Superolateral Hoffa's fat pad edema: Association with patellofemoral maltracking and impingement. AJR Am J Roentgenol 2010;195:1367-73. [ PUBMED] |
| 24. | Kim YM, Shin HD, Yang JY, Kim KC, Kwon ST, Kim JM, et al. Prefemoral fat pad: Impingement and a mass-like protrusion on the lateral femoral condyle causing mechanical symptoms. A case report. Knee Surg Sports Traumatol Arthrosc 2007;15:786-9. |
| 25. | Slemenda C, Brandt KD, Heilman DK, Mazzuca S, Braunstein EM, Katz BP, et al. Quadriceps weakness and osteoarthritis of the knee. Ann Intern Med 1997;127:97-104. [ PUBMED] |
| 26. | Arts IM, Pillen S, Schelhaas HJ, Overeem S, Zwarts MJ. Normal values for quantitative muscle ultrasonography in adults. Muscle Nerve 2010;41:32-41. [ PUBMED] |
| 27. | Pillen S, Tak RO, Zwarts MJ, Lammens MM, Verrijp KN, Arts IM, et al. Skeletal muscle ultrasound: Correlation between fibrous tissue and echo intensity. Ultrasound Med Biol 2009;35:443-6. [ PUBMED] |
| 28. | Sipilä S, Suominen H. Muscle ultrasonography and computed tomography in elderly trained and untrained women. Muscle Nerve 1993;16:294-300. |
| 29. | Ike RW, Somers EC, Arnold EL, Arnold WJ. Ultrasound of the knee during voluntary quadriceps contraction: A technique for detecting otherwise occult effusions. Arthritis Care Res (Hoboken) 2010;62:725-9. [ PUBMED] |
| 30. | Fahrer H, Rentsch HU, Gerber NJ, Beyeler C, Hess CW, Grünig B, et al. Knee effusion and reflex inhibition of the quadriceps. A bar to effective retraining. J Bone Joint Surg Br 1988;70:635-8. |
| 31. | Saavedra MÁ, Navarro-Zarza JE, Villaseñor-Ovies P, Canoso JJ, Vargas A, Chiapas-Gasca K, et al. Clinical anatomy of the knee. Reumatol Clin 2012;8 Suppl 2:39-45. |
| 32. | Kim HR, Lee JH, Kim KW, Kim BM, Lee SH. The relationship between synovial fluid VEGF and serum leptin with ultrasonographic findings in knee osteoarthritis. Int J Rheum Dis 2016;19:233-40. [ PUBMED] |
| 33. | Jiang L, Bao J, Zhou X, Xiong Y, Wu L. Increased serum levels and chondrocyte expression of nesfatin-1 in patients with osteoarthritis and its relation with BMI, hsCRP, and IL-18. Mediators Inflamm 2013;2013:631251. [ PUBMED] |
| 34. | Sharma L, Song J, Felson DT, Cahue S, Shamiyeh E, Dunlop DD, et al. The role of knee alignment in disease progression and functional decline in knee osteoarthritis. JAMA 2001;286:188-95. |
| 35. | Verdonk PC, Pernin J, Pinaroli A, Ait Si Selmi T, Neyret P. Soft tissue balancing in varus total knee arthroplasty: An algorithmic approach. Knee Surg Sports Traumatol Arthrosc 2009;17:660-6. [ PUBMED] |
| 36. | Yusuf E, Bijsterbosch J, Slagboom PE, Rosendaal FR, Huizinga TW, Kloppenburg M, et al. Body mass index and alignment and their interaction as risk factors for progression of knees with radiographic signs of osteoarthritis. Osteoarthritis Cartilage 2011;19:1117-22. |
| 37. | Dragoo JL, Johnson C, McConnell J. Evaluation and treatment of disorders of the infrapatellar fat pad. Sports Med 2012;42:51-67. [ PUBMED] |
| 38. | Clockaerts S, Bastiaansen-Jenniskens YM, Runhaar J, Van Osch GJ, Van Offel JF, Verhaar JA, et al. The infrapatellar fat pad should be considered as an active osteoarthritic joint tissue: A narrative review. Osteoarthritis Cartilage 2010;18:876-82. [ PUBMED] |
[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1]
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