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Medial Ankle Impingement Syndrome due to Talar Osteochondroma and Gout Attack: A Case Report
J Korean Foot Ankle Soc 2024;28:31-35
Published online March 15, 2024;  https://doi.org/10.14193/jkfas.2024.28.1.31
© 2024 Korean Foot and Ankle Society

Min Gyu Kyung, Dongjun Jeon, Dong Yeon Lee*

Department of Orthopedic Surgery, Seoul National University Hospital,
*Department of Orthopedic Surgery, Seoul National University College of Medicine, Seoul, Korea
Correspondence to: Dong Yeon Lee
Department of Orthopedic Surgery, Seoul National University Colege of Medicine, 101 Daehak-ro, Jongno-gu, Seoul 03080, Korea
Tel: 82-2-2072-1863, Fax: 82-2-764-2718, E-mail: leedy@snu.ac.kr
ORCID: https://orcid.org/0000-0001-8233-6285
Received December 26, 2023; Revised February 9, 2024; Accepted February 13, 2024.
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
Osteochondromas are benign bone tumors typically found in the metaphyseal region of long bones. These tumors are often asymptomatic and detected incidentally. However, their occurrence in atypical sites such as the talus can pose significant diagnostic and treatment challenges. This report describes a rare case of osteochondroma of the medial tubercle of the talus, which is an unprecedented location based on a review of relevant literature. A 28-year-old male presented with worsening medial ankle pain and limping. Imaging revealed a lesion consistent with osteochondroma contributing to medial ankle impingement syndrome. Uniquely, this case also featured a coinciding gout attack in the ankle joint. Surgical removal of the lesion resulted in significant symptom relief and functional improvement. This case underscores the need to consider rare diagnoses, such as talar osteochondroma, when presented with persistent medial ankle pain and highlights the potential presence of concurrent conditions, such as gout.
Keywords : Osteochondroma, Talus, Gout, Impingement
CASE REPORT

A 28-year-old previously healthy male visited our outpatient clinic with worsening right medial ankle pain. He reported that he had sprained his right ankle approximately five years ago, and he has experienced chronic pain that would wax and wane since the incident. He was unware of any pathologies around the ankle because he did not specifically check radiographs and merely waited for the symptoms to disappear. Approximately three months prior to his visit, he started experiencing more frequent episodes of pain, swelling, and limping. One week before the visit, he noticed worsening redness around the medial malleolus along with experiencing significantly increased limping. The patient denied any history of recent trauma. He reported drinking alcohol approximately twice a week but denied any history of gout attacks.

Physical examination revealed mild-to-moderate swelling and focal tenderness around the medial malleolus, and the pain worsened with passive ankle inversion. His initial laboratory tests showed that his uric acid level was elevated at 8.7 mg/dL (normal range: 3∼7 mg/dL), while his C-reactive protein value was 0.45 mg/dL (normal range: 0∼0.5 mg/dL). Otherwise, the other blood test results were within normal limits.

The initial plain radiograph revealed the presence of a bony protrusion on the medial side of the talus adjacent to the medial malleolar tip (Fig. 1). Computed tomography (CT) was performed to assess the three-dimensional structure, which revealed an approximately 10×8 mm lesion protruding anteromedially from the medial tubercle (Fig. 2). Subsequent magnetic resonance imaging (MRI) with T1- and T2-weighted views demonstrated findings consistent with osteochondroma in the medial tubercle of the talus and a moderate amount of joint effusion with synovitis, as well as subcortical cysts in the medial malleolus (Fig. 3).

Figure 1. Initial standing ankle (A) anteroposterior and (B) lateral radiographs demonstrating the presence of a bony protrusion (arrowhead) at the medial side of the talus.

Figure 2. Computed tomography images showing an osteochondroma occurring on the medial tubercle of the talus.

Figure 3. (A) T1- and (B) T2-weighted magnetic resonance images showing osteochondroma in the talus medial tubercle, a moderate amount of joint effusion with synovitis, and subcortical cysts in the medial malleolus.

We assumed that the osteochondroma protruding from the medial aspect of the talus could be causing medial impingement syndrome and presumed it to be the main source of pain. Therefore, we explained to the patient that removing the medial lesion would likely lessen the pain. The patient agreed with this assessment and to undergo the surgery.

Under spinal anesthesia, we palpated the medial malleolus and sustentaculum tali and made an incision between them. A portion of the deltoid ligament was incised and the tibialis posterior tendon was retracted to identify the protruding bony mass at the medial tubercle of the talus, slightly posterior and superior to the sustentaculum tali (Fig. 4). After dividing the surrounding capsule, the bony mass appeared to be encased in a material resembling whitish gout tophi. We performed an exploration and removed as much of the tophi as possible. An osteotome was used to excise the bony mass, which appeared consistent with an osteochondroma with some cartilage. We then smoothed the surrounding area with a burr to prevent any remnant medial impingement. Intraoperative fluoroscopy confirmed the successful removal of the lesion and ensured that no impingement had occurred. The deltoid ligament was repaired after meticulous irrigation.

Figure 4. Intraoperative medical photo. (A) Identification of the lesion (tip of the needle) by retracting the tibialis posterior tendon, (B) after complete excision of the lesion, (C) excised talar osteochondroma, and (D) gout tophi.

For postoperative rehabilitation, the patient was instructed to wear a short leg splint for one month, followed by an ankle brace for an additional month. During these periods, weight-bearing was allowed as tolerated. The final histopathological results confirmed the presence of the anticipated osteochondroma with a maximum cartilage cap thickness of 1.1 mm, and the attached whitish material was identified as gout tophi (Fig. 5). The patient was prescribed febuxostat 40 mg daily and colchicine 0.6 mg daily.

Figure 5. Microscopic slide view of (A) osteochondroma with a cartilage cap (H&E, ×400) and (B) deposition of needle shaped crystals indicating gout tophi (H&E, ×1,600).

At the six-month postoperative follow-up, the patient was able to walk and run well. The Foot and Ankle Outcome Score (FAOS) was 85.2 points (FAOS symptom: 89; FAOS pain: 88; FAOS activities of daily living: 100; FAOS sports: 80; and FAOS quality of life: 69) and the visual analog scale score was 4 points. These scores showed improvement compared with the preoperative scores of 60.2 (FAOS symptom: 57; FAOS pain: 61; FAOS activities of daily living: 85; FAOS sports: 60; and FAOS quality of life: 38) and 6 points, respectively. The uric acid level returned to the normal range, and no signs of recurrence were observed on simple radiographs (Fig. 6). Regular outpatient follow-up visits were planned.

Figure 6. Final standing ankle (A) anteroposterior and (B) lateral radiographs 6 months after surgery showing no recurrence.
DISCUSSION

In the ankle, impingement can occur in the anterior, anterolateral, posterior, medial, or lateral areas, and symptoms are triggered more often when attempting to walk with weight-bearing than during rest. Regarding the etiology, medial pain can be induced by ossicles, such as os subtibiale following trauma,3) and cases exist where the medial clear space becomes obliterated due to the progression of arthritis.4) Based on the patient’s history and physical examination alone, we initially speculated that the impingement symptoms might be due to a large ossicle. However, imaging revealed a rare osteochondroma of the medial talar tubercle. In this case, the impingement was likely caused by a space-occupying lesion within the narrow medial joint space. Additionally, the proximity of the tibialis posterior tendon suggests that may have been irritated, potentially leading to tenosynovitis.

The incidence of osteochondroma occurring solely in the talus is less than 0.5%,2) making it a very rare condition. Only a few case reports have documented this occurrence. First, when it occurs on the dorsal side near the talar neck, it can limit the range of motion, especially ankle dorsiflexion. According to the reports by Galanis et al.2) and Wang et al.1), surgical treatment has yielded good clinical outcomes for these patients. Second, a case has been reported in which the osteochondroma was located on the posterior talus, completely limiting plantar flexion.5) Third, Boya et al.6) and Shah et al.7) reported cases of laterally located osteochondroma of the talus occurring in children and adults, respectively. Fourth, similar to our case, osteochondromas on the medial side have been reported.8,9) However, these were large extra-articular lesions rather than intra-articular lesions of the ankle joint. Finally, in some rare cases, it may be present in the form of an intra-articular loose body.10) Therefore, this study is meaningful because it reports a case of osteochondroma occurring on the medial tubercle of the talus, a location not previously documented in the literature.

Interestingly, deposition of gout tophi triggered an attack in this case in addition to the rare talar osteochondroma. Previous literature has noted that gout itself can manifest as a pseudotumor in the foot and ankle region.11) There have also been reports of cases where tophaceous gout around joints, encapsulated by a capsule, mimics bone tumors such as osteochondroma.12) However, the unique aspect of our case lies in the presence of an osteochondroma at the medial tubercle of the talus, which exists as an intraarticular pathology itself, while being encased with gout tophi. In fact, it is challenging to strictly differentiate whether the source of pain is due to medial impingement from osteochondroma or a gout attack. Additionally, since the patient had not specifically sought radiographic examination and merely waited for the symptoms to subside, the absence of previous radiographs makes it difficult to precisely determine the onset of the osteochondroma. Nonetheless, considering the clinical presentation of the patient’s symptoms, which were not severe but fluctuated over time and then suddenly worsened, along with the insidious onset characteristics of osteochondroma, it seems that an existing osteochondroma was exacerbated by a superimposed gout attack. Furthermore, the patient’s consistent history of alcohol consumption may have been a contributing risk factor for gout. However, ascertaining the presence of gout tophi in the ankle joint was difficult as the patient had not previously been treated specifically for gouty arthritis, and the first metatarsophalangeal joint was unaffected.

In conclusion, this study suggests that, despite its rarity, talar osteochondroma at the medial talar tubercle accompanied by a gout tophi may be considered in the differential diagnosis with patients presenting with swelling, sudden worsening of pain, and limping of the medial aspect of the ankle. In such cases, accurately diagnosing the lesion not only through plain radiographs, but also through CT and MRI scans is crucial. Surgical treatment can lead to favorable clinical outcomes.

References
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