Complete arthroscopic excision and macroscopic visualization of a talar osteoid osteoma: A rare opportunity

INTRODUCTION

Osteoid osteoma is a benign bone-forming tumor that typically affects adolescents and young adults with a male-to-female predilection of between 2 and 3:1. The incidence is around 1/100,000 per year and represents between 10 and 12% of benign bone tumors.^[1] It presents with localized pain, often worse at night and relieved by non-steroidal anti-inflammatory drugs. While commonly found in the long bones, its presence in the talus is rare, accounting for approximately 5% of all osteoid osteomas.^[2] The typical treatment involves complete excision or ablation of the nidus. This case presents a rare opportunity to visualize the lesion in its entirety following arthroscopic removal from the anterior talar neck, providing insight into the lesion’s gross morphology and emphasizing the importance of complete nidus removal.

CASE REPORT

A 13-year-old female athlete presented with anterior ankle pain of 12 months’ duration. Initial clinical suspicion was of soft tissue impingement. However, persistent and nocturnal pain prompted further investigation. Radiographs revealed subtle sclerosis of the talar neck. Magnetic resonance imaging (MRI) [Figures 1 and 2] and computed tomography (CT) imaging identified features typical of osteoid osteoma. The lesion was addressed arthroscopically using a standard two-portal anteromedial and anterolateral approach with a 2.9 mm 30° arthroscope (Stryker) in the anterolateral portal. An angled probe was used to assess the tissue on the dorsal neck of the talus, and a 3.5 mm shaver (Stryker) was placed in the anteromedial portal to resect overlying inflamed synovial tissue. The lesion was visualized as a smooth, round, pea-like lesion and was completely shelled out [Figures 3 and 4]. The osteoma was removed through the anteromedial portal and is shown in its entirety [Figure 5].

Close

Figure 1:

Sagittal T2-weighted fast spin echo magnetic resonance image demonstrating a hyperintense lesion at the anterior talar neck.

Export to PPT

Close

Figure 2:

Coronal proton density fat-suppressed magnetic resonance image showing the lesion at the subchondral surface of the talar neck, confirming its arthroscopic accessibility.

Export to PPT

Close

Figure 3:

Arthroscopic view of the lesion. The surrounding osteoid exhibits a characteristic pinkish hue just distal to the articular cartilage.

Export to PPT

Close

Figure 4:

Intraoperative image showing the nidus of the osteoma being exposed after resection of the overlying osteoid. The central core is visible within its bed.

Export to PPT

Close

Figure 5:

Macroscopic image of the entire excised osteoid osteoma, shown adjacent to the arthroscopic probe for scale.

Export to PPT

Histopathological processing

The excised lesion was fixed in 10% neutral-buffered formalin, followed by decalcification using a gentle ethylenediaminetetraacetic acid-based protocol to preserve cellular and matrix detail. After routine tissue processing and paraffin embedding, 5 μm sections were prepared and stained with hematoxylin and eosin. Microscopic analysis confirmed a well-defined nidus composed of interlacing trabeculae of woven bone rimmed by osteoblasts, set within a highly vascular fibrous stroma. Surrounding reactive sclerotic bone was also noted. No cellular atypia or features of malignancy were identified, confirming the diagnosis of an osteoid osteoma.

Postoperatively, the patient experienced immediate pain resolution. She resumed full athletic activity within 3 months, and follow-up radiographs showed no signs of recurrence [Figure 6].

Close

Figure 6:

Lateral ankle radiograph at 3 months postoperatively, demonstrating minor irregularity at the site of excision without evidence of recurrence.

Export to PPT

DISCUSSION

Orthopedic surgeons will be familiar with the presentation and imaging appearances of osteoid osteomas. Most lesions are located within the cortex of a long bone and exhibit a central lucent nidus, with increased sclerosis of the surrounding bone on imaging studies. These lesions may also show marked periosteal new bone formation.^[3] CT scanning is the cross-sectional imaging of choice, as MRI is reported to miss 34% of lesions.^[4] Treatment usually consists of excision or destruction by various means, including physical ablation with drills or extremes of heat with either radiofrequency probes or local freezing with cryoprobes.^[5,6] A sterilizable radiation probe was described in 1983 by Colton and Hardy.^[7] En bloc excision provides the pathologist with the opportunity to section the lesions to confirm the histological features, which Jaffe first described in 1935, who did not have the privilege of seeing the lesion as a whole.^[8]

The nidus may be soft and granular or dense with a gritty texture, depending on the degree of calcification present. The lesion excised in this report was encased in a dense shell. Most orthopedic surgeons will likely not have seen an intact osteoid osteoma, and neither will the pathologist, as they will only see the products of the sections they observe through the microscope lens.

Previous reports of osteoid osteoma excision from the talus have been reported,^[9-11] the lesions being removed arthroscopically using a burr. Histological assessment was not possible, and the authors suggested that the use of non-motorized techniques would be preferable.^[8] Hetsroni et al.^[12] report using a burr to remove sclerotic bone, followed by a curette to remove the cherry-red nidus. The central lesion was sent for histological analysis, but the result was not reported in the paper. A further report of an osteoma in the posteromedial tibia at the ankle was successfully treated using a two-port posterior arthroscopic technique, again using a burr.^[13]

Many cases present with significant sclerosis of bone, and in treating the abnormality, there may be a tendency to excise more bone than is necessary. There is a tendency to use less invasive techniques, as outlined above,^[14] to avoid making an en bloc resection. Seeing the central core of the osteoma confirms the entity and helps to understand that only this core needs to be removed, and as such, excessive resection of sclerotic bone blocks in the ankle and other anatomical sites is not required. However, if percutaneous or minimal access methods are utilized, they must ensure that the whole of this central core is removed to prevent persistent symptoms from retained nidus tissue or from subsequent recurrences. Ge et al.^[15] report a success rate of 96% in a systematic review of arthroscopic excision.

Ankle arthroscopy is a common procedure, but not undertaken by all orthopedic surgeons, and requires training and experience. Choosing arthroscopy to treat an osteoid osteoma will depend on the individual skills and experience of the surgeon performing the procedure. In some units, experienced radiologists will be better placed to use radiofrequency ablation using CT guidance. The author’s view is that ankle arthroscopy for anterior talar neck lesions provides safe and direct access, allowing for visualization of the lesion and confirmation that it has been resected in its entirety. Jordan et al.^[4] report that most talar osteoid osteomas are excised surgically, but there is an increasing trend to use ablation therapy.

Arthroscopy is preferable to open arthrotomy to minimize wounds and enhance the speed of recovery. Visualization is excellent, and the procedure is considered safe in the hands of experienced surgeons with minimal minor complications, including temporary superficial peroneal nerve neuropraxia, post-operative intra-articular bleeding, and joint swelling compared with the open approach. Intra-articular radiofrequency ablation carries the risk of thermal necrosis to the articular cartilage and the neurovascular bundle and must be used with caution.

CONCLUSION

Arthroscopic en bloc excision of a talar osteoid osteoma is a feasible and effective treatment option. This technique allows for complete lesion removal with minimal bone loss, facilitates histological confirmation, and promotes rapid recovery. It is the author’s opinion, following this single case experience, that surgeons should aim to remove the entire nidus to ensure success, but without unnecessary excision of surrounding bone.