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Table of Contents
ORIGINAL ARTICLE
Year : 2022  |  Volume : 71  |  Issue : 4  |  Page : 303-306

Ambiguity of the radiographs around the elbow joint: Anatomical variant versus degenerative changes


1 Clinic of Traumatology, Masaryk Hospital, Ústí Nad Labem; Department of Anatomy, Second Faculty of Medicine, Charles University, Prague 5, Czech Republic
2 Department of Computer Science, Faculty of Electrical Engineering, Czech Technical University, Prague 2, Czech Republic
3 Department of Anatomy, Second Faculty of Medicine, Charles University, Prague 5, Czech Republic

Date of Submission24-Apr-2021
Date of Decision06-Apr-2022
Date of Acceptance16-Aug-2022
Date of Web Publication01-Dec-2022

Correspondence Address:
Dr. Vojtech Kunc
Department of Anatomy, Second Faculty of Medicine, Charles University, V Úvalu 84, 150 06, Prague 5
Czech Republic
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jasi.jasi_80_21

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  Abstract 


Introduction: Interpretation of traumatological radiographs of the region of the elbow joint may come with many challenges. Aside from traumatological avulsions and fractures, we can also identify other entities such as persistent epiphysis, aseptic necrosis, osteochondritis dissecans, calcific bursitis, synovial chondromatosis, and other degenerative changes. It is also necessary for all these pathological conditions to be differentiated from the anatomical variants. Material and Methods: We performed a retrospective analysis of patients admitted to our clinic between 2010 and 2020 for arthroscopic treatment of chronic elbow joint stiffness. We evaluated the radiographs of their elbow joints for the presence of accessory ossification. If present, these cases were then sorted by previously defined criteria into groups according to the kind of anatomical variant and degenerative changes. On the basis of these data, we performed a statistical analysis. Results: We analyzed 39 limbs in 39 patients (12 women and 27 men). The average age was 40.9 years (span 16–74). The exclusion criteria did not exclude any patient. Accessory ossifications were present in 78.4% (29/37) of patients, and all three criteria for accessory bone were fulfilled by two patients. Discussion and Conclusion: This sample of patients suffering from joint stiffness due to degenerative changes around the elbow joint enabled us to prove the usefulness of the criteria for differentiating degenerative changes from accessory bones. We were also able to validate the hypothesis that in a sample of patients suffering from elbow stiffness, the dominant cause of the stiffness should be the degenerative changes, while the accessory bones prevalence should not differ significantly from their prevalence in the healthy population. Our analysis showed that the seemingly ovoid intra-articular loose bodies do not appear on the radiographs as regularly shaped and can be differentiated from accessory bones. In order to avoid the wrong interpretation of elbow radiographs, it is necessary to be aware of this issue. Our study validates the three previously defined criteria as means to diagnose accessory bones with a high specificity. The intra-articular loose bodies macroscopically seemed ovoid and regular. Nevertheless, they do not appear as regularly shaped on radiographs and do not, therefore, fulfill the criteria of accessory bones.

Keywords: Accessory ossicles, degenerative changes, Elbow joint


How to cite this article:
Kunc V, Kunc V, Kuncova K, Kachlik D, Kopp L. Ambiguity of the radiographs around the elbow joint: Anatomical variant versus degenerative changes. J Anat Soc India 2022;71:303-6

How to cite this URL:
Kunc V, Kunc V, Kuncova K, Kachlik D, Kopp L. Ambiguity of the radiographs around the elbow joint: Anatomical variant versus degenerative changes. J Anat Soc India [serial online] 2022 [cited 2023 Jan 27];71:303-6. Available from: https://www.jasi.org.in/text.asp?2022/71/4/303/362555




  Introduction Top


To interpret elbow joint radiographs is a challenging task. We must be able to determine whether the patient suffers from skeletal trauma or other pathological disorders such as persistent epiphysis, aseptic necrosis, osteochondritis dissecans, calcifying bursitis, and synovial chondromatosis or whether the issue is caused by the degenerative changes that may be present. Several anatomical variants, especially accessory bones, might be misinterpreted as pathological or traumatic conditions. As those variants are usually presented unilaterally, the contralateral X-ray is not helpful, which makes the correct diagnosis potentially challenging for many clinicians.[1] Some of the accessory bones might be symptomatic and need surgical treatment.[2]

Accessory bones around the elbow joint are a rare entity compared to the accessory bones of the hand and foot, and the literature on this topic is scarce with issues still unsolved.[1],[3],[4],[5] Contrary to the term pathological ossification, the term “accessory (variable, variant, and supernumerary) bone (ossicle)” is reserved for a congenital anatomical structure. In our previous study, we proposed a nomenclature based on the older classifications of Wood and Campbell,[6] Obermann and Loose,[7] and Schwarz.[8] This terminological classification based on 2413 radiographs of elbow joints distinguishes six types of accessory bones of the elbow [Figure 1].[1]
Figure 1: Type I and II refer to intra-articular bones. Type I is situated ventrally in the coronoid fossa (os supratrochleare anterius), type II is situated dorsally in the olecranon fossa (os supratrochleare posterius). Type III and V (os subepicondylare mediale and subepicondylare laterale) are sesamoid bones in the common orirgin of flexor muscles under the medial epicondyle and in the common oririgin of extensor muscles under the lateral condyle, respectively. Type IV and VI (os sesamoideum tricipitale and os sesamoideum brachiale) are also sesamoid bones in the tendons of corresponding muscles. Existence of so-called “patella cubiti” is still not clear and this entity is considered the synonym to the os sesamoideum tricipitale in this classification[1]

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This study aimed to verify the efficiency of the previously described criteria for the radiographic evaluation of the accessory bones on a sample of patients with chronic elbow disorders caused by assumed ossification of a pathologic origin. For the confirmation of the previously defined criteria, we presume that the prevalence of accessory bones in our current sample will be similar to the prevalence in the healthy sample used for our previous work. Therefore, if the previously defined criteria enable the differentiation of the degenerative changes (pathological ossification) from the variable accessory bones, the latter would occur with similar prevalence in patients with chronic elbow disorders as in healthy patients. All elbows were visualized arthroscopically (as a part of the treatment of elbow joint stiffness).


  Material and Methods Top


We carried out a retrospective analysis of patients admitted to our department for the arthroscopic treatment of elbow joint stiffness from 2010 to 2021. All patients fulfilled our indication criteria for the arthroscopic visualization of the elbow joint (posttraumatic mild-to-severe intrinsic elbow joint stiffness without any improvement on receiving physiotherapy treatment). Exclusion criteria were defined as: (1) incomplete radiographs (only single projection), (2) radiographs in the cast or (3) radiographs containing osteosynthesis material, (4) incomplete surgical protocol, (5) patient's disagreement with his/her inclusion in this study, and (6) degenerative changes of Grade 3 or 4 according to Kellgren–Lawrence classification: an example shown in [Figure 2].[9] This study was done in accordance with the ethical standards stated by the Helsinki Declaration of 1975, as revised in 2000.
Figure 2: Pathological ossification do not fulfill the criteria for accessory bones

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Overall, we analyzed 39 limbs in 39 patients of central European origin, from which 30.8% (12/39) were women and 69.2% were men. There were more procedures performed on the right extremity (59% – 23/39) than on the left (41% – 16/39). Two patients with severe degenerative changes met our exclusion criteria. Patients' age ranged from 16 to 74 years (average 40.9, median 39, and standard deviation 14.87).

We collected the following data from the documentation: the age of the patient during the procedure, side, date of the procedure, description of the accessory body in the joint (if present), and previous surgeries performed on the analyzed elbow that had taken place before the arthroscopic procedure. Subsequently, we analyzed the elbow X-ray in anteroposterior and lateral projections on the Phillips 227E monitor with a resolution of 1920 × 1080 px in the basic settings.

We used the criteria defined in our previous study for the identification of accessory bones: (I) a regular ovoid shape, (II) smooth margins, and (III) a regular ratio of cortical to cancellous bone along its circumference. If all the criteria were fulfilled and therefore the finding was considered an accessory bone, we used the previously defined classification based on the position of the bone to identify which category it belongs [Figure 1].

We used the Fisher's exact test to compare the observed prevalence of accessory bones with the prevalence described in our previous study. The same test was used to check if the fulfillment of criteria I-III had any connection to sex or the side of the procedure. To assess the relationship between the presence of an accessory bone in our sample and the patient's age, we used logistic regression and Kendall's correlation (variant b). The presence of an accessory bone was coded as value 1 and its absence as value 0. In the case of logistic regression, we tested if the presented coefficient differed significantly from zero in a model with a constant term included. In the case of Kendall's correlation, we tested if the correlation coefficient differed significantly from zero. The statistical analysis was concluded in the Python 3.8 language with the use of SciPy version 1.2.1 library.[10]


  Results Top


Accessory ossification (before the application of any exclusion criterion) was present in 78.4% of the (29/37) cases. Of these cases, criterion I was fulfilled by 27.6% (8/29), criterion II by 17.2% (5/29), and criterion III by 6.9% (2/29). Overall, 10.3% (3/29) of the ossification cases met one of the criteria, 10.3% (3/29) of the cases fulfilled two of the criteria, and 6.9% (2/29) of the cases fulfilled all the three criteria. According to the mentioned criteria, the congenital accessory bones were present in two out of 29 patients.

As the first step, we analyzed if there was a statistically significant difference between the prevalence of the accessory bones in the current sample compared to the previous study. In the current sample, 2 out of 29 patients (6.9%) had accessory bones, whereas in the previous study, it was 15 out of 1940 (0.77%). The difference was shown to be statistically significant by Fisher's exact test (P = 0.025). However, one os supratrochleare anterius was present in this sample, while the previous study has not reported any case in this category of the accessory bone. The patient in question came to us due to the symptoms resulting from the presence of this bone, making our sample biased by its occurrence as it was no coincidence. The observation of the os supratrochleare anterius, therefore, did not come from a random sample of the population, and we cannot include it when assessing its prevalence in the overall population. After the exclusion of this finding, the Fisher's exact test did not show a statistically significant difference among the studies (P = 0.21).

The presence of accessory ossification (both congenital and pathological) did not have any statistically significant relationship to the patient's age. The coefficient for age neither significantly differ from zero in logistic regression (P = 0.182), nor does Kendall's correlation significantly differ from zero (P = 0.184).

As a sanity check, we analyzed if any criterion showed any correlation with age, gender, or the side of the procedure. This analysis did not show any significant relationship [Table 1].
Table 1: P value of each test used for a statistical significance analysis of relation between the criteria and each of the followed parameters in our sample

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  Discussion Top


All the three criteria for accessory bone identification were fulfilled in 6.9% (2/29) of patients, and those cases were, therefore, considered congenital or due to the trauma in early childhood. Pathological posttraumatic degenerative accessory ossifications were distributed equally in the sample (78.4%) without any relation to gender or side. The criteria for accessory bone identification were not in relation to any of the collected parameters (age, gender, and side). If they were of a degenerative or posttraumatic origin, it would be more probable that there would be such a relation.

Two of the observed accessory bones were classified as os subepicondylare mediale (type V) and os supratrochleare anterius (type I). The first is the most commonly occurring accessory bone of the elbow in the Central European population (0.46%) [Figure 3]. The latter is an interesting case, as it was not present in the sample of 2413 elbows in our previous study.[1] The previous literature describes only rare cases of it.[2] It is very probable that its' presence was symptomatic and had brought the patient to the hospital.
Figure 3: Os subepicondylare mediale is the most common accessory bone around the elbow joint

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Os sesamoideum tricipitale and os supratrochleare posterius are also rare symptomatic accessory bones. They were not present in our sample, and 18 cases[2],[8],[11],[12] and 36 cases[1],[13],[14] were described in the previous literature, respectively.

If we did not exclude patients with severe degenerative changes, we would incorrectly add one os sesamoideum brachiale and one accessory bone around the tip of the olecranon (no such bone is described in our previous classification). Therefore, we conclude that our criteria for accessory bones differentiation are not helpful in degenerative elbows of higher than grade 3 severity according to Kellgren–Lawrence classification. For such differentiation, a fourth criterion based on the length-to-width ratio might be helpful, as no other accessory bone in the human body is extensively long and narrow. Unfortunately, it is impossible to define such a criterion based merely on two cases.

Even though the comparison of 6.9% prevalence in this study to 0.77% in the previous study might seem like a reason to question the previous criteria, we conclude that these data for reasons stated above do not contradict our previous work. The symptoms are usually described as pain and stiffness.[2],[15] Cases of an accessory bone fracture have also been described in the literature.[7],[16]

It is incredibly difficult to diagnose the accessory bones in children, as there is not enough information in the previous literature about such cases, except for “patella cubiti” (type VI).[17],[18],[19] In a detailed analysis of ossification centers presented by Silberstein et al., there is neither a description of the accessory ossification centers nor a description of the accessory bones.[20],[21],[22],[23],[24] It is, therefore, reasonable to hypothesize that the ossification of the accessory bones occurs at a later age.

Our arthroscopic examination showed that pathological ossifications are visually also ovoid-shaped and regularly shaped. Nevertheless, this shape is made up of tissues other than bone as the X-ray image is irregular. Therefore, arthroscopic differentiation of these entities is not possible, and imaging (or histology) is the golden diagnostic standard.


  Conclusion Top


This study showed that all the three diagnostic criteria for accessory bone differentiation can be used in the elbow region with a high specificity in all cases except for the joints suffering from severe degenerative changes.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Kunc V, Kunc V, Černý V, Polovinčák M, Kachlík D. Accessory bones of the elbow: Prevalence, localization and modified classification. J Anat 2020;237:618-22.  Back to cited text no. 1
    
2.
Mittal R, Sampath Kumar V, Gupta T. Patella cubiti: A case report and literature review. Arch Orthop Trauma Surg 2014;134:467-71.  Back to cited text no. 2
    
3.
Amar E, Rozenblat Y, Chechik O. Sesamoid and accessory bones of the hand – An epidemiologic survey in a Mediterranean population. Clin Anat 2011;24:183-7.  Back to cited text no. 3
    
4.
Coskun N, Yuksel M, Cevener M, Arican RY, Ozdemir H, Bircan O, et al. Incidence of accessory ossicles and sesamoid bones in the feet: A radiographic study of the Turkish subjects. Surg Radiol Anat 2009;31:19-24.  Back to cited text no. 4
    
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Koo BS, Song Y, Lee S, Sung YK, Sung IH, Jun JB. Prevalence and distribution of sesamoid bones and accessory ossicles of the foot as determined by digital tomosynthesis. Clin Anat 2017;30:1072-6.  Back to cited text no. 5
    
6.
Wood VE, Campbell GS. The supratrochleare dorsale accessory ossicle in the elbow. J Shoulder Elbow Surg 1994;3:395-8.  Back to cited text no. 6
    
7.
Obermann WR, Loose HW. The os supratrochleare dorsale: A normal variant that may cause symptoms. AJR Am J Roentgenol 1983;141:123-7.  Back to cited text no. 7
    
8.
Schwarz GS. Bilateral antecubital ossicles (fabellae cubiti) and other rare accessory bones of the elbow. Radiology 1957;69:730-4.  Back to cited text no. 8
    
9.
Kellgren JH, Lawrence JS. Radiological assessment of osteo-arthrosis. Ann Rheum Dis 1957;16:494-502.  Back to cited text no. 9
    
10.
Virtanen P, Gommers R, Oliphant TE, Haberland M, Reddy T, Cournapeau D, et al. SciPy 1.0: Fundamental algorithms for scientific computing in Python. Nat Methods 2020;17:261-72.  Back to cited text no. 10
    
11.
Habbe JB. Patella cubiti: A report of four cases. Am J Roentgenol 1942;48:513-26.  Back to cited text no. 11
    
12.
Kjelland PM. A rare anomaly in the elbow; patella cubiti. Acta Radiol 1945;26:491-6.  Back to cited text no. 12
    
13.
Canamero B, Ángeles M, Giraldo S, Alberto W, Rivera G, Ignacio J, et al. Os supratrochleare dorsale del codo. Acta Rheumatol 2014;1:25-8.  Back to cited text no. 13
    
14.
Gudmundsen TE, Ostensen H. Accessory ossicles in the elbow. Acta Orthop Scand 1987;58:130-2.  Back to cited text no. 14
    
15.
Ahlgren SA, Rydholm A. Patella cubiti. Report of an operated case. Acta Orthop Scand 1975;46:931-3.  Back to cited text no. 15
    
16.
Behnke E, Horne K. Fractured os supratrochleare dorsale: A case report of elbow pain in a young person with a history of remote trauma. Am J Roentgenol 2011;196:A58-52.  Back to cited text no. 16
    
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Burge P, Benson M. Bilateral congenital pseudarthrosis of the olecranon. J Bone Joint Surg Br 1987;69:460-2.  Back to cited text no. 17
    
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Kattan KR, Babcock DS. Case report 105. Bilateral patella cubiti. Skeletal Radiol 1979;4:249-50.  Back to cited text no. 18
    
19.
Thijn CJ, van Ouwerkerk WP, Scheele PM, de Jongh HJ. Unilateral patella cubiti: A probable posttraumatic disorder. Eur J Radiol 1992;14:60-2.  Back to cited text no. 19
    
20.
Silberstein MJ, Brodeur AE, Graviss ER. Some vagaries of the capitellum. J Bone Joint Surg Am 1979;61:244-7.  Back to cited text no. 20
    
21.
Silberstein MJ, Brodeur AE, Graviss ER, Luisiri A. Some vagaries of the medial epicondyle. J Bone Joint Surg Am 1981;63:524-8.  Back to cited text no. 21
    
22.
Silberstein MJ, Brodeur AE, Graviss ER, Luisiri A. Some vagaries of the olecranon. J Bone Joint Surg Am 1981;63:722-5.  Back to cited text no. 22
    
23.
Silberstein MJ, Brodeur AE, Graviss ER. Some vagaries of the lateral epicondyle. J Bone Joint Surg Am 1982;64:444-8.  Back to cited text no. 23
    
24.
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