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Table of Contents    
Year : 2019  |  Volume : 67  |  Issue : 3  |  Page : 894-896

Loose bodies of bilateral atlantoaxial joints: A rare occurrence

1 Department of Neurosurgery, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
2 Department of Histopathology, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India

Date of Web Publication23-Jul-2019

Correspondence Address:
Dr. Madhivanan Karthigeyan
Department of Neurosurgery, PGIMER, Sector 12, Chandigarh - 160 012
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0028-3886.263187

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How to cite this article:
Karthigeyan M, Salunke P, Kataria MS, Gupta K. Loose bodies of bilateral atlantoaxial joints: A rare occurrence. Neurol India 2019;67:894-6

How to cite this URL:
Karthigeyan M, Salunke P, Kataria MS, Gupta K. Loose bodies of bilateral atlantoaxial joints: A rare occurrence. Neurol India [serial online] 2019 [cited 2019 Dec 7];67:894-6. Available from:


The formation of loose bodies (LBs) has been commonly described in various large synovial joints, and are most commonly seen in the knee.[1],[2] Smaller joints can be infrequently involved.[1] Rare reports have documented the existence of such LBs in spine, the source of which is likely from the adjacent synovial facet joints.[3],[4],[5],[6],[7] We herein present a patient with atlantoaxial dislocation (AAD), who harboured LBs in the bilateral C1-C2 joints.

A 53-year old woman presented with neck pain and spastic quadriparesis for 2-years. The computed tomography (CT) revealed AAD associated with segmentation anomalies such as assimilated-C1 and fused C2-3 vertebrae. In addition, the C1-C2 joints showed degenerative changes such as sclerosis, narrowing of joint space and formation of bridging osteophytes [Figure 1]. The magnetic resonance imaging (MRI) disclosed cervico-medullary compression. Posterior C1-C2 fusion was performed.[8],[9] During the exposure of facets, we observed smooth-walled, glistening white, hard masses lying adjacent to the bilateral C1-C2 joints [Figure 2]. These were suggestive of LB which was confirmed on histopathology. A retrospective review of the radiology identified the LB [Figure 1]. Postoperatively, the patient had symptomatically improved and was doing well at a 1-year follow-up visit.
Figure 1: (a-e) Preoperative images. (a) Midsagittal CT image shows atlantoaxial dislocation along with bony segmentation defects (assimilated C1, C2-C3 fusion and C5-C6 block vertebrae). (b and c) Parasagittal CT cuts along bilateral C1-C2 facets show sclerosis of joints and narrowed joint spaces. Note the presence of loose bodies (LB) (arrow). (d) Axial CT images show bilateral sclerosed C1-C2 joints and the presence of LBs (arrow). (e) Corresponding axial MRI section demonstrates LBs (marked by arrow)

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Figure 2: (a and b) Intraoperative photographs. (a) Loose bodies (arrow) are evident in bilateral C1-C2 joints (the facets are indicated by asterisk). (b) Gross specimen of the loose bodies

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The LBs are well-known entities in human joints and can be a cause of joint pain, swelling and limited joint movements.[1],[2] At times, they are an incidental finding during surgery for other joint pathologies.

The origin of intra-articular LBs is ascribed to conditions such as 1) synovial osteochondromatosis, 2) osteochondral fractures, and 3) degenerative joint disruption.[10] Synovial osteochondromatosis is characterized by metaplasia of the synovial membrane of a joint to form cartilaginous/osteocartilaginous nodules; the nodules then separate to form LBs. The synovial chrondromatosis is termed primary when the phenomenon is denovo in a normal joint, and secondary when it occurs in association with an underlying joint pathology such as osteoarthritis, osteochondritis dessicans, Charcot's arthropathy and osteonecrosis.[1] There are three stages described by Milgram in this process.[10] Initially, the synovial lining undergoes metaplasia, followed by a transitional phase with both synovial nodules and free LBs, and the last stage of multiple LBs with no active synovial disease.

Osteochondral fractures involve the articular surfaces of joints, and during trauma, a small fragment can detach to give rise to a free lying LB.[10] Concerning the formation of a LB secondary to degenerative arthritis, mechanisms such as fragmentation of the joint surface, fractured osteophytes and osteochondral nodule proliferation have been proposed.[10]

The natural history of LBs has been studied.[11],[12] Once they detach from the synovial lining and are free within the joint, they become devoid of any blood supply. They form new surface layers due to proliferation of the chondroblasts and osteoblasts which derive their nutrition from the synovial fluid. Resorption cavities and remodelling also occurs secondary to the osteoclastic activity. Slowly, degenerative changes with secondary calcification develop in the nidus of LBs. Over a period of time, the LB reattaches to the synovial surface of the joint and becomes revascularized.[11],[12] The calcified cartilage is then resorbed by the synovium, and osteogenesis occurs as a body's reactive mechanism to contain the LB.

The radiologic appearance of LB depends on their bony and cartilaginous content. CT scan can identify calcific lesions which are spherical and periarticular in location. In the absence of calcification, the LB may be easily overlooked. In T1-weighted images, they appear hypointense. In T2-weighted sequences, they show a high-signal intensity due to the high water content of cartilage.[1] The calcified areas display low-signals in both T1 and T2 sequences.

LBs in the spine (2, cervical and 3, lumbar) have been described; however, none have been reported in the C1-C2 joints.[3],[4],[5],[6],[7] One of the patients with a cervical LB presented with cord compression due to progressive enlargement in the size of the LB.[5] Though the LB was lying within the spinal canal in the other case, it did not cause any symptom.[4] Its asymptomatic nature was attributed to the slowly growing nature with simultaneous adaptability of the cord tissue to chronic compression. The lumbar LB manifested with canal stenosis and neurogenic claudication; one patient among them had multiple LBs, that was associated with spondylolisthesis.[3],[6],[7] When causing compression, the removal of the offending fragment relieves symptoms. The LB in our patient was possibly due to the degenerative arthritis of bilateral C1-2 facet joints. The long-standing instability and osseous-segmentation anomalies could have probably accelerated the degenerative phenomenon. Apart from an aging spine, the repeated micro-trauma and stress secondary to C1-C2 instability and congenital fusion of vertebrae could have contribute to such an extensive degeneration seen on imaging.

To summarize, we present the first case of occurrence of LBs in the atlantoaxial joints. The superimposed degenerative process in congenital AAD appears to be the inciting event in our patient.

Compliance with ethical requirements

Informed consent was obtained from patient.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Neumann JA, Garrigues GE, Brigman BE, Eward WC. Synovial chondromatosis. JBJS Rev 2016;4. pii: 01874474-201605000-00005. doi: 10.2106/JBJS.RVW.O.00054.  Back to cited text no. 1
Raval P, Vijayan A, Jariwala A. Arthroscopic retrieval of over 100 loose bodies in shoulder synovial chondromatosis: A case report and review of literature. Orthop Surg 2016;8:511-5.  Back to cited text no. 2
Tambe A, Monk J, Calthorpe D. “Spinolith”: Case report of a loose body in the spinal canal. Spine (Phila Pa 1976) 2002;27:E248-9.  Back to cited text no. 3
Shin C, Nourbakhsh A, Ozkan E, Garges KJ. Asymptomatic osseous loose body in the cervical spine. A case report. J Bone Joint Surg Am 2007;89:1586-8.  Back to cited text no. 4
Hongo M, Miyakoshi N, Kasukawa Y, Ando S, Ishikawa N, Okada K, et al. Enlargement of an osseous loose body in the cervical spine with cord compression. Spine J 2009;9:e11-4.  Back to cited text no. 5
Takeshima Y, Hanakita J, Takahashi T, Nakase H. Multiple osseous loose bodies associated with lumbar isthmic spondylolisthesis. World Neurosurg 2016;95:623.e1-4.  Back to cited text no. 6
Treon K, Ockendon M. Osteochondral loose body: An unusual cause of lumbar spinal stenosis. Eur Spine J 2017;26(Suppl 1):167-9.  Back to cited text no. 7
Salunke P, Sahoo S, Khandelwal NK, Ghuman MS. Technique for direct posterior reduction in irreducible atlantoaxial dislocation: Multi-planar realignment of C1-2. Clin Neurol Neurosurg 2015;131:47-53.  Back to cited text no. 8
Salunke P, Sahoo SK, Deepak AN, Ghuman MS, Khandelwal NK. Comprehensive drilling of the C1-2 facets to achieve direct posterior reduction in irreducible atlantoaxial dislocation. J Neurosurg Spine 2015;23:294-302.  Back to cited text no. 9
Milgram JW. The development of loose bodies in human joints. Clin Orthop Relat Res 1977;124:292-303.  Back to cited text no. 10
Milgram JW. The classification of loose bodies in human joints. Clin Orthop Relat Res 1977;124:282-91.  Back to cited text no. 11
Milgram JW, Gilden JJ, Gilula LA. Multiple loose bodies: Formation, revascularization, and resorption. A 29-year followup study. Clin Orthop Relat Res 1996;322:152-7.  Back to cited text no. 12


  [Figure 1], [Figure 2]


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