September 26, 2021
Osteochondral defect of the talus

Osteochondral defect of the talus

Introduction

Osteochondral defect (OCD) of the talus is the 3rd most common location for an OCD after the knee and elbow. First recognized by Konig in 1888 [1]Konig, F: Ueber freie Korper in den Gelenken. Deutsch Z Chir, 27:90 – 109, 1888; an osteochondral defect is loosely defined as an insult to both the articular cartilage and subchondral bone of the talus. Historically, this was termed ‘osteochondritis dessicans’ to describe the idiopathic, atraumatic lesions that were found but osteochondral defect is now the widely accepted vernacular.

Case Introduction

You are evaluating a 17 year old soccer player with persistent ankle pain that has not improved with conservative therapy. She has previously had several ankle sprains. You are suspicious of an osteochondral lesion. Which of the following imaging modalities is most sensitive for osteochondral defects of the talus?

A) Ultrasound

B) CT

C) Radiographs

D) MRI

Osteochondral Defect of the Talus XR

Image 1. Radiograph of an OCD of the talus[2]van Bergen, Christiaan JA, Mikel L. Reilingh, and C. Niek van Dijk. “Tertiary osteochondral defect of the talus treated by a novel contoured metal implant.” Knee Surgery, Sports … Continue reading

Pathophysiology

The talus is particularly susceptible to OCD lesions. This in part due to the talus being covered in 60% articular cartilage with a tenuous blood supply. Talar OCD lesions are also associated with ankle sprains and fractures, one of the most common orthopedic conditions.[3]Saxena A, Eakin C. Articular talar injuries in athletes: results of microfracture and autogenous bone graft. Am J Sports Med. 2007;35(10):1680-1687. Most lesions are found on either the anterolateral or posteromedial talar dome. The etiology and pathophysiology are poorly understood. The mechanism may be a single traumatic insult or chronic, repetitive microtrauma. A single traumatic event is thought to represent the majority of cases.[4]Verhagen, Ronald AW, et al. “Systematic review of treatment strategies for osteochondral defects of the talar dome.” Foot and ankle clinics 8.2 (2003): 233-242. Some cases are idiopathic. Perhaps even more interesting, some are asymptomatic and discovered incidentally when imaging is performed for other reasons.

Image 2. Osteochondral defect of the talus on CT[5]D’Hooghe, Pieter, et al. “Concomitant injuries in chronic ankle instability.” Clinical Research on Foot and Ankle 6.3 (2018): 7.

Clinical Features

The clinical features can vary slightly depending on the acuity. In acute trauma, physicians may attribute the patient’s symptoms to an uncomplicated ankle sprain and initially miss the OCD. Patients will have typical symptoms of a lateral ankle sprain including ATFL tenderness, trouble weight bearing, and swelling. Displaced lesions can cause locking and catching. In more subacute or chronic presentations, patient’s report deep ankle pain after activity potentially without swelling, restricted range of motion or tenderness. On physical exam, a joint effusion may or may not be present. The talus may be tender, with restricted range of motion and painful plantar- and/or dorsiflexion.

Image 3. OCD lesion of the talus on MRI[6]Youn, Gun Min, et al. “Arthroscopic-assisted osteochondral allograft transplantation for posterolateral lesions of the talus without fibular osteotomy.” Arthroscopy techniques 8.3 (2019): … Continue reading

Evaluation

Evaluation begins with standard radiographs, which are often normal as the sensitivity is low.[7]Verhagen RA, Maas M, Dijkgraaf MG, Tol JL, Krips R, van Dijk CN. Prospective study on diagnostic strategies in osteochondral lesions of the talus: is MRI superior to helical CT? J Bone Joint Surg Br. … Continue reading Potential findings include displacement, osteonecrosis and cystic changes. MRI is the imaging modality of choice which is highly sensitive and specific. MRI provides good characterization of the articular surface and any bone or cartilage edema but may overestimate the size of the lesion. CT is not routinely ordered but may better characterize the subchondral bone. Diagnostically, arthroscopy is the gold standard and 100% sensitive but not routinely utilized without an MRI first.

Management

Management depends primarily on displacement. A nonoperative attempt should be made on asymptomatic lesions and strongly considered in acute, nondisplaced lesions. Patients are typically immobilized in a short leg cast or tall walking boot for 6-8 weeks. There is no consensus on weight bearing status which ranges from non weight bearing to full weight bearing. About 50% of these patients will do well without surgery.[8]Canale ST, Belding RH. Osteochondral lesions of the talus. J Bone Joint Surg Am. 1980;62(1):97-102. Indications for surgical management are displaced lesions and those that have not resolved with conservative management. Surgical techniques include cartilage repair, cartilage replacement and regenerative therapies.
Following surgery, around 90% of patients will return to sport and about 75% to pre-injury level of competition.[9]Steman, Jason AH, et al. “Return to sports after surgical treatment of osteochondral defects of the talus: a systematic review of 2347 cases.” Orthopaedic journal of sports medicine 7.10 … Continue reading There are no clear return to play guidelines for surgical OCD Lesions. Complications include ankle osteoarthritis, graft failure and persistent pain. Some patients due not achieve pain relief regardless of treatment.

Case Conclusion

Answer is D, MRI. Imaging modalities are well studied for osteochondral lesions. Radiographs are not sensitive at all. CT is around 80% sensitive and MRI is about 96% sensitive making it the imaging modality of choice. Note that arthroscopy, the gold standard, is 100% sensitive but not routinely used unless an MRI has been previously obtained.

Verhagen RA, Maas M, Dijkgraaf MG, Tol JL, Krips R, van Dijk CN. Prospective study on diagnostic strategies in osteochondral lesions of the talus: is MRI superior to helical CT? J Bone Joint Surg Br. 2005;87(1):41-46.

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