Intra-Articular Osteochondroma in the Elbow: Diagnosis and Surgical Treatment in an 8-Year-Old Boy

Introduction

INCIDENCE AND PRESENTATION OF OSTEOCHONDROMA:

Osteochondromas, commonly known as osteocartilaginous exostoses, represent a prevalent category of benign bone tumors within the human skeletal system [1]. Osteochondroma growths consist of osseous tissue adorned with a hyaline cartilage cap, and are considered hamartomas originating from anomalous cartilage growth [2]. Osteochondromas are classified into 2 groups: solitary and multiple [3]. The solitary type occurs in a single bone and is not inherited, while hereditary multiple exostoses, an autosomal dominant condition, can lead to numerous osteochondromas [4].

From an epidemiological perspective, osteochondromas predominantly manifest during the second and third decades of an individual’s life, with approximately 70% of affected individuals being younger than 20 years [5]. Osteochondromas are more common in males, with a male-to-female ratio of 2: 1 [6,7]. The growth of these tumors typically parallels the overall growth of the patient and becomes dormant upon the closure of epiphyses [8]. Although often asymptomatic, osteochondromas can develop symptoms due to factors such as fracture, formation of bursae, pain, neurological and vascular compromise, joint interference, malformation or misalignment, and rare malignant transformation [9].

The diagnosis of osteochondroma typically involves clinical evaluation and imaging studies. Patients may present with a painless, palpable mass, but symptomatic cases might exhibit pain, swelling, or restricted motion if the tumor interferes with surrounding tissues. X-rays are the primary imaging modality, revealing the characteristic features of osteochondromas: a bony outgrowth with a cartilage cap contiguous with the underlying bone cortex and medullary canal. MRI can further delineate the cartilage cap and assess for any malignant transformation [1,10].

MANAGEMENT OF OSTEOCHONDROMA:

Management strategies for osteochondromas depend on the presence and severity of symptoms. Asymptomatic lesions typically require observation and periodic follow-up [11]. Surgical excision is indicated for symptomatic osteochondromas causing pain, functional impairment, or suspicion of malignant transformation. Complete removal of the tumor, including its cartilage cap, is crucial to minimize recurrence [12].

DIFFERENTIAL DIAGNOSES OF INTRA-ARTICULAR OSTEOCHONDROMA:

Differentiating intra-articular osteochondromas from other cartilaginous or bony lesions is critical. The following differential diagnoses should be considered:Foreign Body: Typically introduced by trauma, presenting with acute pain and inflammation. Imaging reveals a radiopaque object not connected to the bone [13].Enchondroma: A benign cartilaginous tumor within the bone marrow, commonly found in small bones of the hands and feet. It shows a characteristic central calcification on X-rays [14].Chondroblastoma: A benign but locally aggressive tumor usually occurring in the epiphysis of long bones. It presents with pain and swelling, and X-rays show a lytic lesion often with a thin sclerotic rim [15].Periosteal Chondroma: A rare benign cartilaginous tumor located on the surface of bones, presenting as a slow-growing mass causing cortical scalloping and periosteal reaction [16].Chondromyxoid Fibroma: A rare benign bone tumor that presents with a lobulated appearance on imaging, often with a sclerotic margin [17].Malignant Chondrosarcoma: A malignant tumor requiring differentiation due to its aggressive nature. It presents with pain and a mass, and imaging shows irregular, destructive lesions with calcifications [18].

This report presents a patient with an osteochondroma in an unconventional location of the elbow joint of the right arm, specifically originating from the trochlea and capitellum, and emerging post-skeletal maturity. This report describes the presentation, diagnosis, and management of an intra-articular osteochondroma of the right elbow joint in an 8-year-old boy.

Case Report

A right-handed 8-year-old Saudi boy presented to one of the authors with complaints from his parents of insidious dull pain in his right elbow, persisting for 3 months and limiting his elbow motion. The initial physical examination revealed a hard, mildly tender mass beneath the posterior elbow, along with a restricted range of motion. No other abnormalities were noted, and there was no significant family history or history of trauma or infection. Initially, conservative treatment was recommended for 1 month.

Despite various conservative measures, including nonsteroidal anti-inflammatory drugs and physical therapy, the patient’s symptoms had not significantly improved by the follow-up visit 1 month later. During this visit, a firm swelling in the right cubital fossa was also observed, which had developed over the past month. The patient had no history of similar bony lesions or underlying medical conditions.

Physical examination at this follow-up revealed a slightly tender solid mass on the posterior aspect of the elbow joint in the right distal arm. The range of the right elbow joint movements was limited, measuring 60° to 80° for flexion and extension, respectively, whereas the left elbow had a full range from 0° to 140°. Pronation and supination of the forearms were unaffected. No abnormalities were observed in the over-lying skin. There were no signs of muscle weakness, sensory disturbances, or vascular issues in the affected limb, and the overall general and hematological examinations were normal.

Imaging studies were conducted to further evaluate the mass. A right elbow lateral radiograph depicted an osseous mass on the posterior aspect of the distal part of the humeral epiphysis with a calcified, sclerotic cortical margin. The axial computed tomography (CT) image of the elbow showed a pedunculated bony outgrowth (red arrow) arising from the olecranon fossa. CT scans confirmed the presence of a mass extending into the anterior aspect of the trochlea and capitellum, seamlessly connected to the underlying bone (Figure 1). A nonenhanced MRI revealed a solid mass in the elbow joint, displaying chondral components on the articular surface, while a fat-suppressed post-contrast MRI indicated soft tissues with reactive inflammatory changes (Figure 2).

A technetium-99 isotope scan exhibited localized uptake in the tumor region, with no corresponding uptake elsewhere. Chest X-ray and CT chest scans showed no signs of metastasis. The above findings indicated a diagnosis of an osteochondroma originating from the trochlea and the capitellum.

Surgical exploration was conducted through an 8 cm curved incision along the elbow’s lateral aspect. After preserving the radial nerve, a transverse capsulotomy was performed to address the anterior joint capsule and relieve the contracture. Upon opening the capsule, a lobulated, pinkish-white intraarticular mass was identified, measuring approximately 5×2×1 cm. The mass had a cartilage cap and continuity with the distal humerus. Complete excision of the mass was achieved, and intraoperative fluoroscopy confirmed total re-section. Following the lesion excision, the patient’s elbow regained normal functionality.

Histopathological examination of the excised mass confirmed the diagnosis of benign osteochondroma, characterized by a typical cartilaginous cap overlying a bony stalk that was in continuity with the underlying bone, corroborating the clinical and imaging findings (Figure 3).

The patient’s postoperative recovery was uneventful, and follow-up visits confirmed the absence of recurrence and a full restoration of elbow joint function.

Discussion

This case report highlights several critical aspects of osteochondromas, particularly those arising in unusual locations such as the elbow joint. From this clinical case, we can learn about the presentation, diagnostic challenges, and treatment outcomes associated with intra-articular osteochondromas. The patient’s symptoms of insidious dull pain and limited motion over 3 months, coupled with the discovery of a hard, mildly tender mass on physical examination, underscore the need for a thorough evaluation when a child presents with persistent joint pain.

Osteochondromas, also known as exostoses, originate from abnormal cartilaginous tissue within the physis, as suggested by Virchow in 1891 [19]. This tissue detaches from the growth plate periphery during skeletal growth and thus forms a distinct osseous growth region by endochondral ossification [19]. Osteochondromas are typically found in the long bones, including the femur, tibia, and humerus, with rare instances around the elbow with infrequent intra-articular occurrences [1,20].

Osteochondromas are usually symptomatic if intra-articular, and asymptomatic if extra-articular. Para-articular osteochondromas may arise from synovial chondromas [21]. Jaffe et al first described intra-articular osteochondromas arising from the adjacent soft tissue or the joint capsule [22]. A recent case series indicated that osteochondromas constitute over a third of benign bone tumors of long bones [1,23]. Of these, 10% of patients exhibit multiple hereditary exostoses (auto-somal dominant). These osteochondromas occur predominantly in male children before the second decade of life [24]. The condition’s prevalence in the general population has been estimated to be 1 in 50 000 individuals [25]. Classical osteochondromas are anatomically connected to the medullary canal of the bone of origin. The lesions usually extend through the underlying cortex to merge with the cortex of the bony stalk. Osteochondromas have an encapsulating cartilaginous cap consisting of hyaline cartilage representing the actively growing part of the mass. Early diagnosis and surgical intervention may confer a better prognosis and promote the skeletal growth process. Significantly, this growth process naturally halts upon reaching skeletal maturity [1].

The diagnostic process in the present case was comprehensive, involving a series of imaging studies that provided valuable insights into the nature of the masses. The initial radiograph revealed an osseous mass with a calcified, sclerotic cortical margin, while CT scans confirmed the mass’s extension into the trochlea and capitellum. MRI further elucidated the cartilaginous components and reactive inflammatory changes, supporting the diagnosis of osteochondroma. This detailed imaging workup is crucial, as it helps differentiate osteochondromas from other potential causes of similar symptoms, such as synovial chondromatosis or malignant tumors.

The diagnostic process involved a thorough physical examination and imaging studies. CT scans depicted cortical continuity, while MRI demonstrated both mass continuity into the marrow and cartilaginous cap thickness. There are some osteochondroma variants, including subungual, turret exostosis and traction, periosteal osteochondromatous proliferation, and dysplasia epiphyseal hemimelia [9]. Secondary osteochondromas have been reported following trauma, radiation, and osteomyelitis [26].

Histopathologically, the mass exhibited the classic features of osteochondroma, including a cartilage cap and continuity with the underlying bone. This finding is consistent with the pathogenesis described by Virchow and supported by subsequent histopathological and experimental studies [19]. The surgical approach and postoperative management, involving immediate active motion exercises, were critical in ensuring a swift and complete recovery, a strategy supported by Jang et al as the criterion standard for treating intra-articular osteochondromas [23].

Our patient’s plain X-ray revealed a mineralized mass without any abnormal calcification in it and the adjacent tissues. A CT scan provided additional information about the lesion’s nature and extent. Surgical intervention was deemed necessary due to the increasing severity of symptoms and the intra-articular nature of the lesion, which posed a risk of further joint damage and functional impairment. The complete excision of the mass, confirmed by intraoperative fluoroscopy, led to a full restoration of elbow function, highlighting the effectiveness of timely surgical management.

Surgical intervention was planned based on the increasing intensity of the symptoms and because of the uncertainty around the nature and extent of the lesion intra-articularly. Jang et al also reported that open surgical excision is the criterion standard approach for intra-articular osteochondroma [23]. As found intraoperatively, the tumor was completely intraarticular, and the histologic picture was consistent with osteochondroma. After excision of the lesion, full elbow flexion and extension were achieved intra-operatively. No immobilization was needed, and active-motion exercises for the elbow and forearm were encouraged immediately and 2 months postoperatively. During this period, the patient received physiotherapy (elbow motion exercises), and symptoms were completely resolved at the 2-month follow-up visit. Notably, this kind of presentation in the elbow joint has not been documented previously, and the pathogenesis remains uncertain. Shariatzadeh et al [27] and Dittrich et al [28] also reported intra-articular osteochondromas similar to our case except for the age of the patients.

The present case underscores the importance of considering osteochondroma in the differential diagnosis of persistent joint pain in children, particularly when accompanied by a palpable mass. The combination of thorough imaging studies and timely surgical intervention can lead to excellent outcomes, as demonstrated in this case.

Conclusions

This rare case of intra-articular osteochondroma in the elbow joint, especially in such a young patient, highlights the need for heightened clinical awareness and prompt diagnostic and therapeutic action. The report highlights the importance of surgical removal and histopathology in the diagnosis of this common bone lesion to exclude the differential diagnoses of intra-articular masses including foreign body, enchondroma, chondroblastoma, periosteal chondroma, chondromyxoid fibroma, or malignant chondrosarcoma.