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Kozioł T, Stolarz K, Osiowski A, Osiowski M, Jasiewicz B, Taterra D. The prevalence, morphology and topography of fabella in knee joints in the polish population and its association with size of patella. Surg Radiol Anat 2025; 47:149. [PMID: 40425942 PMCID: PMC12116647 DOI: 10.1007/s00276-025-03655-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2025] [Accepted: 05/05/2025] [Indexed: 05/29/2025]
Abstract
PURPOSE The fabella is a sesamoid bone located posterior to the lateral femoral epicondyle within the gastrocnemius muscle. While commonly present in mammals, its prevalence in humans remains unclear, with reported rates ranging from 3 to 87%. Fabella is more frequently observed in Asian and Australian populations but is rare in European and American populations. Although often asymptomatic, it can sometimes cause knee pain, known as "fabella syndrome," and may contribute to neurological symptoms when in proximity to the common fibular nerve. Given the limited awareness of fabella's presence, this study aims to assess its prevalence and anatomical characteristics to aid in the differential diagnosis of knee pain. METHODS A retrospective analysis was conducted on 500 knee radiographs from 383 patients experiencing knee pain. Data collected included patient age and sex, fabella presence and dimensions, fabella location (distances to surrounding bony structures), patella dimensions, and patellotibial ligament length. RESULTS Fabella was detected in 31 females (14.76%) and 29 males (25.66%). Among the examined knees, fabella was present in 40 (12.82%) of female and 39 (20.74%) of male knees. The mean fabella length was 8.85 mm (SD = 2.59), and thickness was 5.63 mm (SD = 1.88), with no significant sex differences. No correlation was found between fabella size and patella dimensions. Notably, patients with fabella were older on average, and bilateral fabellae were significantly larger than unilateral cases (p < 0.05). CONCLUSION Fabella is a relatively common anatomical variant in Central European populations, present in one in six women and one in four men. Its increased prevalence in older individuals suggests a potential age-related development. A comprehensive understanding of fabella anatomy may aid clinicians in diagnosing and managing unexplained knee pain, particularly in elderly patients.
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Affiliation(s)
- Tomasz Kozioł
- Department of Anatomy, Jagiellonian University Medical College, Krakow, Poland.
| | - Kacper Stolarz
- Jagiellonian University Medical College, Krakow, Poland
- Ortho and Spine Research Group, Zakopane, Poland
| | - Aleksander Osiowski
- Jagiellonian University Medical College, Krakow, Poland
- Ortho and Spine Research Group, Zakopane, Poland
| | - Maksymilian Osiowski
- Jagiellonian University Medical College, Krakow, Poland
- Ortho and Spine Research Group, Zakopane, Poland
| | - Barbara Jasiewicz
- Department of Orthopedics and Rehabilitation, Jagiellonian University Medical College, Zakopane, Poland
| | - Dominik Taterra
- Ortho and Spine Research Group, Zakopane, Poland
- Department of Orthopedics and Rehabilitation, Jagiellonian University Medical College, Zakopane, Poland
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Al Mudayris LA, Alghamdi AH, Albunyan S, Almulhim AK, Alsaleem M, Abuljadail S. The Prevalence of Fabella and Its Association With Osteoarthritic Severity of Knee in Saudi Arabia: A Multicenter Study. Cureus 2024; 16:e65784. [PMID: 39211677 PMCID: PMC11361753 DOI: 10.7759/cureus.65784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/30/2024] [Indexed: 09/04/2024] Open
Abstract
INTRODUCTION The fabella exhibits variable prevalence across populations and is associated with musculoskeletal disorders. Limited research exists on fabella-related studies, particularly in Saudi Arabia, necessitating further investigation to understand its prevalence and association with knee osteoarthritis (OA). METHODS A retrospective multicenter study was conducted in AlAhsa, Saudi Arabia, reviewing knee X-rays of patients diagnosed with knee OA. Statistical analysis assessed potential associations between fabella presence, demographic factors, and OA severity using the Kellgren-Lawrence classification. RESULTS Among 348 participants, 96 (27.6%) exhibited fabella presence, with 38 (39.6%) of them showing fabellar degenerative changes. No significant associations were found between fabella presence and gender, age, knee side, or OA severity, except for a marginal trend in age groups. However, there was an increasing trend in fabellar degeneration with advancing OA grades. CONCLUSION Our study emphasizes the importance of investigating fabella prevalence and its associations with knee OA in diverse populations. While no significant correlations were found in this cohort, the findings prompt further exploration, emphasizing the need for multicenter studies to enhance understanding and clinical management of fabella-related conditions in knee OA.
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Affiliation(s)
| | | | - Sara Albunyan
- Medicine, College of Medicine, King Faisal University, Al-Ahsa, SAU
| | | | - Mohammad Alsaleem
- Orthopedic Surgery, Al Moosa Specialist Hospital, Al-Ahsa, SAU
- Orthopedics, King Fahad Hospital Hofuf, Al-Ahsa, SAU
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Bauman JM, Alzahabi OA. X-ray Imaging Versus Anatomical Dissection for Identification of the Fabella. Cureus 2024; 16:e62186. [PMID: 38993415 PMCID: PMC11239198 DOI: 10.7759/cureus.62186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/05/2024] [Indexed: 07/13/2024] Open
Abstract
INTRODUCTION Reported prevalence rates of the fabella sesamoid bone vary widely, particularly between studies based on either X-ray imaging or anatomical dissection approaches. The purpose of this study was to directly compare these two methodologies in their detection of fabellae and investigate whether variability in the density of fabellae could explain any discrepancies. METHODS Fifty cadaveric knee segments were examined for the presence of a fabella by both X-ray imaging and anatomical dissection. The relative density of each excised fabella specimen was then quantified using a separate set of radiographs. Results: Fabellae were detected in 40% of the sample knees via a manual dissection approach but in just 12% of those same specimens using X-ray imaging. Relative density measurements confirmed that fabellae identifiable only via dissection were significantly less dense than fabellae visible in whole knee radiographs but denser than the surrounding tissue. CONCLUSION Radiology cannot reliably detect cartilaginous or incompletely ossified fabellae, which were found in 28% of the study population. Clinicians should consider the potential occurrence of a fabella when diagnosing posterolateral knee pain, even if it may not be visible via X-ray.
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Affiliation(s)
- Jay M Bauman
- Center for Anatomical Science and Education, Saint Louis University School of Medicine, Saint Louis, USA
| | - Obadah A Alzahabi
- Center for Anatomical Science and Education, Saint Louis University School of Medicine, Saint Louis, USA
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Zhong J, Zhang G, Si L, Hu Y, Xing Y, He Y, Yao W. The prevalence and parameters of fabella and its association with medial meniscal tear in China: a retrospective study of 1011 knees. BMC Musculoskelet Disord 2022; 23:188. [PMID: 35232412 PMCID: PMC8886965 DOI: 10.1186/s12891-022-05092-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 02/02/2022] [Indexed: 11/17/2022] Open
Abstract
Background Fabella is a sesamoid bone of knee that has potential biomechanical function. We aimed to examine the fabellar prevalence and parameters in Chinese population and test the hypothesis that fabellar presence and morphology were associated with meniscus tear or ligament injury. Methods A total of 1011 knee magnetic resonance imaging scans from 979 patients with knee pain were analyzed retrospectively. The exclusion criteria are postsurgical scans, difficulty in fabella discrimination, conditions not suitable for measurement, and unsatisfied image. The fabellar presence and its parameters (length, width and thickness) were documented. The association between fabellar presence and meniscus tear or ligament injury were assessed by chi-square test, in all knees and subgroups (age, gender, side, lesion part). The correlation of fabellar presence and parameters with advancing age was assessed by Spearman correlation analysis. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to investigate whether factors related with meniscus tear or ligament injury. Diagnostic performance of risk factors was assessed by receiver operating characteristic (ROC) analysis. Results The overall prevalence of fabellae was 39.8% (402/1011 knees) and increased with the increasing age (r = 0.237, P < 0.001). The size of the fabellae differed according to genders, age, and presence of articulating grooves. Fabella presented more often in knees with medial meniscus (MM) tears (66.7% vs 33.8%; P < 0.001) with a multivariate OR of 2.960 (95% CI, 1.853–3.903). The association remained in all tear parts (anterior, middle, and posterior), and in younger (age < 50 years) and older patients (age ≥ 50 years). Age, fabellar length, width, length/thickness ratio and width/thickness ratio yielded an area under the ROC curve (AUC) of 0.604–0.766 to predict an MM tear. In combination with age, fabellar width and length/thickness ratio, the AUC was improved 0.791 (95% CI, 0.744–0.837), with a sensitivity of 73.0% and a specificity of 74.6%. Conclusion The presence of fabellae, increased fabellar length and width as well as flatter fabellar morphology, are significantly associated with an increased risk for MM tear. These findings might aid clinicians in identifying patients at risk for a MM tear and informing them. Supplementary Information The online version contains supplementary material available at 10.1186/s12891-022-05092-4.
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Affiliation(s)
- Jingyu Zhong
- Department of Imaging, Tongren Hospital, Shanghai Jiao Tong University School of Medicine, No. 1111, Xianxia Road, 200336, Shanghai, China
| | - Guangcheng Zhang
- Department of Sports Medicine, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, No. 600 Yishan Road, 200233, Shanghai, China
| | - Liping Si
- Department of Imaging, Tongren Hospital, Shanghai Jiao Tong University School of Medicine, No. 1111, Xianxia Road, 200336, Shanghai, China
| | - Yangfan Hu
- Department of Imaging, Tongren Hospital, Shanghai Jiao Tong University School of Medicine, No. 1111, Xianxia Road, 200336, Shanghai, China
| | - Yue Xing
- Department of Imaging, Tongren Hospital, Shanghai Jiao Tong University School of Medicine, No. 1111, Xianxia Road, 200336, Shanghai, China
| | - Yaohua He
- Department of Sports Medicine, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, No. 600 Yishan Road, 200233, Shanghai, China. .,Department of Orthopedics, Shanghai Sixth People's Hospital, Jinshan Branch, No. 147 Jiankang Road, 201500, Shanghai, China.
| | - Weiwu Yao
- Department of Imaging, Tongren Hospital, Shanghai Jiao Tong University School of Medicine, No. 1111, Xianxia Road, 200336, Shanghai, China.
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Unluturk O, Duran S, Yasar Teke H. Prevalence of the fabella and its general characteristics in Turkish population with magnetic resonance imaging. Surg Radiol Anat 2021; 43:2047-2054. [PMID: 34398300 DOI: 10.1007/s00276-021-02817-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 08/06/2021] [Indexed: 11/24/2022]
Abstract
INTRODUCTION The fabella is a fibrocartilaginous or ossified sesamoid bone in the knee, largely located in the lateral tendon of the head of the gastrocnemius muscle. In this study, the prevalence, gender differences, localization and size of the fabella were determined in a Turkish population to make a comparison with other population studies in the literature. MATERIALS AND METHODS Thousand patients (500 females, 500 males) who underwent knee magnetic resonance imaging (MRI) with fabella in all three planes, including axial, sagittal and coronal evaluated, retrospectively. All MRI examinations were performed using a 1.5 T unit. Patients with a history of trauma or operation, motion artifacts and patients who could not be evaluated due to image quality were excluded. Anteroposterior diameter in sagittal plan (sAP) of the fabella and the fabella-femur distance was measured. Measurements were evaluated with Pearson's Chi-squared and Mann-Whitney U test for non-homogeneous data in SPSS program, and ANOVA test for homogeneous data. A p value of < 0.05 was considered significant in all analyses. RESULTS The overall prevalence of fabella was found to be 155 cases. Unilateral fabella was detected in 72.9% of the cases, of which 56.6% were on the right side and 43.4% were on the left side. The median value of AP diameter in sagittal plan was calculated as 4.40 ± 1.31 mm. Concerning the gender-related examination the sAP diameter of the fabella was larger in men than in women (p < 0.05). The median value of FFD was calculated as 2.50 ± 0.50 mm. The distribution of FFD between genders was not statistically significant (p = 0.492). CONCLUSION The fabella is usually a sesamoid bone that can be detected incidentally by imaging techniques. The incidence in the Turkish population is 15.5%, and no gender difference was detected. It is clear that further studies on the basis of populations are needed, especially considering that pathological problems remain in question and there is a lack of scientific data (variations, developmental characteristics, etc.) on sesamoid bones.
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Affiliation(s)
- Ozge Unluturk
- Ministry of Justice, Council of Forensic Medicine, İstanbul, Turkey
| | - Semra Duran
- Department of Radiology, University of Health Sciences, Ankara Bilkent City Hospital, Bilkent Bulvarı No.1, Ankara, Turkey.
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Matroushi ODA, Sirasanagandla SR, Shabibi AA, Obaidani AA, Dhuhli HA, Jaju S, Mushaiqri MA. Radiological study of fabella in Omani subjects at a tertiary care center. Anat Cell Biol 2021; 54:315-320. [PMID: 33967029 PMCID: PMC8493026 DOI: 10.5115/acb.20.194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 04/07/2021] [Accepted: 04/07/2021] [Indexed: 11/27/2022] Open
Abstract
Ethnic diversity is associated with variability in the prevalence rates of fabella. We aimed to evaluate the prevalence and the radiological features of fabella in Omani patients. This is a retrospective analysis of hospital electronic database of patients referred for radiological investigations (radiographs and magnetic resonance imaging) of the knee, at a tertiary care referral center. Descriptive statistics were performed to determine the prevalence of fabella. Chi-square test was used to determine the association between sex or age with respect to the presence of fabella. A total of 813 knee radiographs were reviewed for the presence of fabella. Fabella was found in 24.1% of total cases. A statistically significant sex difference was observed with respect to the presence of fabella in left knees in males (P<0.01). The presence of fabella was significantly associated with age groups for the right (P<0.05) and left knees (P<0.01). In magnetic resonance imaging film reviews, all the identified fabellae (20.2%) were bony structures and were located within the lateral head of the gastrocnemius muscle. There were no cartilaginous fabellae detected. The current study revealed a prevalence of 24.1% of fabella in Omani subjects which is almost similar to the results as seen in Caucasian ethnic populations.
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Affiliation(s)
| | - Srinivasa Rao Sirasanagandla
- Department of Human and Clinical Anatomy, College of Medicine and Health Sciences, Sultan Qaboos University, Muscat, Oman
| | - Ammar Al Shabibi
- College of Medicine and Health Sciences, Sultan Qaboos University, Muscat, Oman
| | | | - Humoud Al Dhuhli
- Department of Radiology and Molecular Imaging, College of Medicine and Health Sciences, Sultan Qaboos University, Muscat, Oman
| | - Sanjay Jaju
- Department of Family Medicine & Public Health, College of Medicine and Health Sciences, Sultan Qaboos University, Muscat, Oman
| | - Mohamed Al Mushaiqri
- Department of Human and Clinical Anatomy, College of Medicine and Health Sciences, Sultan Qaboos University, Muscat, Oman
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Asghar A, Naaz S, Chaudhary B. The Ethnic and Geographical Distribution of Fabella: A Systematic Review and Meta-Analysis of 34,733 Knees. Cureus 2021; 13:e14743. [PMID: 34084671 PMCID: PMC8164001 DOI: 10.7759/cureus.14743] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/28/2021] [Indexed: 11/13/2022] Open
Abstract
INTRODUCTION The primary studies demonstrated that fabellar prevalence (FP) varied with ethnic and geographical distribution. Osteoarthritis (OA) and age-related degeneration have a significant association with FP. The prevalence of OA worldwide was doubled with life expectancy. Increased life expectancy has increased exposure to OA and age-related degeneration which could be a possible reason for the rise of FP. The analysis was conducted to provide insight about FP in respect to geographical, ethnic, sex, and laterality distribution. METHODOLOGY Eighty-six studies were included which have data from 34,733 knee joints. Fifty radiological studies were consisting of 27,293 knees and 36 cadaveric studies had the data of 7,440 knees of dissected specimens, respectively. The prevalence, Odds, and rate ratios were calculated for aging, osteoarthritis, and ethnic variation. Results: The worldwide FP was 25% (95% CI, 0.22, 0.28). The prevalence of fabella was found to be higher in cadaveric studies (32%) than radiological studies (19%) with significant heterogeneity. The FP was 16-18% till 1950 which was doubled by 2020 (35%). The FP in OA knee was 51% which was thrice of baseline.
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Affiliation(s)
- Adil Asghar
- Anatomy, All India Institute of Medical Sciences Patna, Patna, IND
| | - Shagufta Naaz
- Anaesthesiology, All India Institute of Medical Sciences Patna, Patna, IND
| | - Binita Chaudhary
- Anatomy, All India Institute of Medical Sciences Patna, Patna, IND
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Asghar A, Naaz S, Narayan RK, Kumar A. Does the Prevalence of Ossified Fabella Vary in Knee Osteoarthritis and Age-Related Degeneration? A Meta-Analysis of About 11,000 Knees. Cureus 2021; 13:e12535. [PMID: 33564533 PMCID: PMC7863029 DOI: 10.7759/cureus.12535] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/06/2021] [Indexed: 12/15/2022] Open
Abstract
OBJECTIVE Osteoarthritis (OA) and age-related degeneration (ARD) are stimulants for the development of the fabella in the knee joint. This meta-analysis updates previous studies and reviews on the prevalence of the fabella in OA or ARD knee joints. In addition, it provides a quantitative estimation of the fabellar prevalence in knees having OA and ARD. METHODOLOGY Twenty studies containing data from 11,056 knee joints were utilized in the investigation, consisting of 6,819 knees of individuals with OA (including those with age greater than 40 years) and 4,237 knees of individuals without OA (including less than 40 years of age), respectively. Totally, 2,434 knees of the OA subjects had fabellae (including more than 40 years), while in the non-OA subjects, 844 had fabellae (including less than 40years). The odds ratio (OR) and relative risk (RR) were calculated. RESULTS The fabellar prevalence was observed to be higher in OA knees, where the risk ratio of developing fabella was 2.55 (2.15-3.02). Compared with this, the risk ratio for the incidence of fabella in ARD knee was 1.71 (1.59-1.85). The bilateral occurrence of fabella was more common than unilateral. The risk of developing fabella in individuals aged less than 40-year was 0.59 which was 41% less than individuals aged more than 40 years. The risk ratio of developing fabella in co-exposure of ARD and OA was 1.84 [1.66, 2.04, 95% CI]. CONCLUSION OA and ARD would increase the prevalence of ossified fabella by 84%, thus acting as stimulants or associations and risk factors for ossified fabella.
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Affiliation(s)
- Adil Asghar
- Anatomy, All India Institute of Medical Sciences Patna, Patna, IND
| | - Shagufta Naaz
- Anesthesiology, All India Institute of Medical Sciences Patna, Patna, IND
| | - Ravi K Narayan
- Anatomy, All India Institute of Medical Sciences Patna, Patna, IND
| | - Anup Kumar
- Orthopaedics, All India Institute of Medical Sciences Patna, Patna, IND
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