Emerging Concepts In Treating Osteochondral Lesions Of The Talus
Osteochondral lesions of the talus are very common and frequently occur after an inversion ankle sprain. The common mechanisms for an osteochondral lesion of the talar dome include a plantarflexion-inversion or dorsiflexion-inversion injury to the ankle. Plantarflexion-inversion injuries often cause posteromedial osteochondral lesions on the talar dome while dorsiflexion-inversion injuries will tend to cause anterolateral lesions on the talar dome. Lateral lesions tend to be more shallow and “wafer” shaped while medial lesions tend to be deeper and “cup” shaped.
Berndt-Hardy classified osteochondral lesions of the talus into four stages.1 Stage 1 is a subchondral fracture of the talar dome. Stage 2 is a partially detached chondral fragment on the talar dome. Stage 3 is a completely detached but non-displaced fragment of the talar dome. Stage 4 is a completely detached and displaced fragment of the talar dome.
All patients with Stage 1 and 2 lesions, along with those who have Stage 3 medial lesions, receive conservative treatment with a non-weightbearing below-knee cast for a minimum of six weeks. If pain persists, surgery is indicated in these patients. Stage 3 lateral lesions and all Stage 4 lesions respond best with surgery. Chondral tissue has poor vascularity and its healing potential is very minimal. Due to this, chronic pain and swelling may occur and approximately 17 to 50 percent of patients may develop early osteoarthritis in the joint.2,3
The majority of osteochondral lesions will require surgical intervention as only 45 percent of patients with an osteochondral lesion of the talus improve with conservative and non-operative treatment.4 This is often due to the lack of vascularity and the absence of progenitor cells to articular cartilage cells.4 Management of osteochondral lesions of the talus can be a challenge to foot and ankle surgeons. The foot and ankle surgeon should determine the size and depth of the lesion before deciding on surgical options for the patient. One can best determine this with a computed tomography (CT) scan of the ankle.
Key Insights On Arthroscopic Debridement And Microfracture Chondroplasty
Arthroscopic debridement and microfracture of osteochondral lesions generally have good outcomes if the lesion is less than 1.5 cm in diameter.5 The microfracture technique allows the surgeon to recruit progenitor cells by penetrating the subchondral bone at the floor of the lesion.
This technique stimulates revascularization and results in the formation of fibrocartilage, which has significantly poorer mechanical properties in comparison to hyaline cartilage. It is a minimally invasive and fairly effective treatment.4,6 Microfracture surgery requires the patient to be non-weightbearing in a removable cast. Range of motion begins as soon as possible in these patients unless they underwent concurrent lateral ankle stabilization.
Pertinent Pointers On Using The Osteochondral Allograft Transplant System
The osteochondral allograft transplant system is a method in which mature hyaline cartilage from an allograft replaces an osteochondral defect. This cartilage replacement procedure repairs the defect with mature hyaline cartilage cells as well as restoring the anatomic architecture of the bone.2,9,10 This method is not associated with the morbidity associated from the harvest of an autograft.