Arthroscopic Treatment of Osteochondral Lesions of the Talus

G. Andrew Murphy

Jane C. Yeoh

Introduction

Osteochondral lesions of the talus (OLT) or osteochondritis dissecans of the talus was originally described as transchondral fractures of the talus by Berndt and Harty¹. After the initial classification by Berndt and Harty¹, several authors further classified OLTs by computed tomography (CT) imaging findings, magnetic resonance imaging (MRI) findings, and arthroscopic findings. OLTs can be symptomatic or asymptomatic. Asymptomatic OLTs should not be treated operatively.

Treatment of OLTs by arthroscopic débridement and bone marrow stimulation techniques has demonstrated good long-term outcomes. Van Bergen et al.² demonstrated that 94% (46 of 49) patients returned to work and 88% (37 of 42) patients returned to sport at an average follow-up of 141 ± 34 months. The majority of patients had good or excellent clinical outcomes, measured by the Ogilvie-Harris score (20% excellent, 58% good, 22% fair, 0% poor), AOFAS score (mean 88), and SF-36 (71 ± 16 mean physical component and 94 ± 22 emotional component.² When assessed for radiographic progression, 67% (32 of 48) patients showed no radiographic progression of osteoarthritis and 33% (16 of 48) patients showed osteoarthritis progression by one stage.²

Classification Systems

Several classification systems exist to grade OLTs by radiographs,³ MRI,⁴ and arthroscopic findings.⁵,⁶ Giannini et al.⁷ devised a classification that guides treatment of OLTs (Table 62-1).

Preoperative Planning

• Detailed history and physical examination

• Clinical findings confirmed with imaging findings.

▪ Only 30% (15 of 50) ankles with nonoperatively treated OLTs had ankle tenderness corresponding to the location of the OLT.⁷

• Pathologies that should be treated alongside the OCL of the talus (e.g., chronic ankle instability)

▪ 48% (24 of 50) ankles with nonoperatively treated OLT had subjective instability.⁸

Table 62-1 | Classification of osteochondral lesions based on radiographics, MRI, and arthroscopy

Radiographic Classification

MRI Revised Classification

Arthroscopic Classification

Arthroscopic Grade Based on Articular Cartilage

Berndt and Harty¹

Hepple et al.⁸

Dipaola et al.⁴

Ferkel et al.⁶

Stage 0^a

Not visible on radiographs

Stage 1

Articular cartilage damage only

Stage I

Irregularity and softening of articular cartilage, no definable fragment

Grade A

Smooth, intact cartilage, but soft and ballottable

Stage 1

Trabecular compression of subchondral bone

Grade B

Rough articular cartilage surface

Stage 2

Partially detached osteochondral fragment

Stage 2a

Cartilage injury with underlying fracture and surrounding bony edema

Stage II

Articular cartilage breached, definable fragment, not displaceable

Grade C

Articular cartilage has fibrillations and fissures

Stage 2b

Cartilage injury with underlying fracture without surrounding bony edema

Grade D

Articular cartilage flap present or bone exposed

Stage 3

Detached and undisplaced osteochondral fragment

Stage 3

Detached and undisplaced osteochondral fragment

Stage III

Articular cartilage breached, definable fragment, displaceable, but attached by some overlying articular cartilage

Grade E

Loose, undisplaced fragment

Stage 4

Detached and displaced osteochondral fragment

Stage 4

Detached and displaced osteochondral fragment

Stage IV

Detached and displaced osteochondral fragment (loose body)

Grade F

Loose, displaced fragment

Stage 5

Osteochondral lesion with subchondral cyst formation

^aStage 0 not part of original classification.

• Obtain weight-bearing AP, lateral, and oblique plain radiographs of the ankle (Fig. 62-1).

• Obtain cross-sectional imaging.

• MRI cross-sectional imaging (Figs. 62-2 and 62-3)

▪ MRI is preferred for visualization of bone marrow edema, soft tissue, and articular cartilage details.

Figure 62-1 | AP, mortise, and lateral weight-bearing radiographs of a lateral OLT in a 17-year-old woman.

• Spiral CT or weight-bearing CT (PEDCAT) (Figs. 62-2 and 62-3)

▪ CT is preferred for determining size of the lesion.

Figure 62-2 | Coronal CT and MR images of a lateral cystic subchondral OLT in a 17-year-old woman (same patient as in Fig. 62-1).

Figure 62-3 | Sagittal CT and MR images of a lateral cystic subchondral OLT (same patient as in Figs. 62-1 and 62-2).

• A comparison of these different imaging modalities can help the physician better understand the osteochondral lesion (Fig. 62-4).

Figure 62-4 | Mortise radiograph, coronal CT image, and coronal MR image of a medial OLT in a 36-year-old man. Note the clear delineation of the bony border of the OLT in the CT image and note the bone marrow edema apparent in the medial talus and medial malleolus on the MRI.

Decision Making

• Primary vs revision surgery

• The gold standard of primary treatment of small OLTs < 1.5 cm² is arthroscopic débridement and bone marrow stimulation or microfracture.

• Revision surgery or primary surgery of large lesions could include cartilage replacement procedures including osteoarticular transplantation system (OATS), autologous cartilage implantation (ACI), juvenile hyaline cartilage allograft, and bulk osteochondral allograft.

▪ Lesions ≥1.5 cm² treated with arthroscopic débridement and bone marrow stimulation are associated with increased risk of poor outcome.⁹ Therefore, lesions ≥1.5 cm² can be treated with arthroscopic débridement and bone marrow stimulation or cartilage replacement procedures.

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