Introduction

Orthopaedic surgery is a dynamic field of medicine with ever-changing advances in knowledge and techniques. As our patient populations continue to grow younger and more active, we search for more anatomic and less invasive methods of addressing pathology. The subspecialty of surgery of the foot and ankle likewise is participating in this exciting evolution of understanding and approaches to common acute and chronic conditions of the foot and ankle. In this chapter we discuss newer techniques and treatment options for foot and ankle disorders.

Osteochondral Lesions of the Talus

Osteochondral lesions of the talus (OLT) are rare, representing just 4% of all such lesions in the body.¹ The term OLT evolved from an 1888 report that described “osteochondritis dissecans” as a loose body associated with articular cartilage and subchondral bone fracture.² Because inflammation is not an important factor in the etiology of OLT, many authors do not use the term “osteochondritis dissecans.”

The two locations most often seen in which OLTs are involved are posteromedial and anterolateral. Trauma is cited as the etiology in more that 85% of patients.³^–⁷ Although the etiology of nontraumatic OLT is unknown, some reports have cited a primary ischemic event or genetic predisposition (e.g., identical medial talar lesions in identical twins, multiple lesions occurring in the same patient) as a cause.⁸

Acute traumatic events are typically the cause of lateral lesions. Lesions on the anterolateral aspect of the talar dome are caused by inversion and dorsiflexion, resulting in the anterolateral aspect of the talar dome’s impacting the fibula. These lesions usually more shallow and “wafer shaped” than medial lesions.⁹

Medial lesions usually are caused by repetitive overuse syndromes; ; only a small number of medial lesions can be attributed to trauma. Posteromedial lesions result from inversion, plantarflexion, and external rotational forces. The posteromedial talar dome impacts the tibial articular surface, leading to a deep, cup-shaped lesion in the talus.

The classic presentation for the OLT is characterized by chronic ankle pain with swelling. The pain usually is localized to the side of the ankle where the lesion is located. Other symptoms include weakness, stiffness, catching, and giving way with repeated inversion injuries. Initial physical examination signs include tenderness on palpation behind the medial malleolus with the ankle dorsiflexed (posteromedial lesions) and over the anterolateral ankle joint when in maximal plantarflexion (anterolateral lesions). A joint effusion is a clear sign of intra-articular involvement.

Weight-bearing plain radiographs should be used to evaluate the ankle (anterior-posterior, lateral, and mortise views). Posteromedial lesions are evaluated best by imaging the ankle in various degrees of plantarflexion. Anterolateral lesions are evaluated best by imaging the ankle in various degrees of dorsiflexion. In our experience, magnetic resonance imaging (MRI) is the most appropriate imaging modality to evaluate for OLT. Areas of low signal intensity on T1-weighted images indicate a chronic lesion resulting from sclerosis of the bed of the talus.¹⁰ High signal rims on T2-weighted images indicate an unstable osteochondral fragment.^11,¹² Intra-articular, gadolinium-enhanced MRI can provide images of articular cartilage, assess stability, and detect intra-articular bodies.¹³ Significant ankle effusions may provide a “physiologic arthrogram,” negating the need for gadolinium.

The OLT should be staged before treatment is determined. In 1959, Berndt and Harty ¹⁴ devised a system for staging OLT. Since that time, various researchers have revised and refined their original classification systems as newer technologies, such as arthroscopy, computed tomography (CT), and MRI became available. Table 25-1 is a staging classification developed by Hepple et al.¹⁵ and is based on MRI imaging.

Table 25-1 Classification System for Staging Osteochondral Lesions of the Talus Using Magnetic Resonance Imaging

Stage I	Articular cartilage damage only
Stage IIa	Articular cartilage injury with underlying fracture and edema
Stage IIb	Stage II without edema
Stage III	Detached fragment (rim signal) but nondisplaced
Stage IV	Displaced fragment
Stage V	Subchondral cyst formation

Treatment

Nonoperative

Generally, conservative treatment should be attempted first. Two studies reviewed the long-term outcomes of patients with OLT and the possible development of osteoarthrosis. Conservative treatment consists of protected ambulation for pain relief and an appropriate sports brace during activity. Conservative treatment should be attempted for at least 6 months. McCullough and Venugopal ¹⁶ followed 10 patients for 15 years and found that although conservative treatment often does not lead to radiographic union, osteoarthrosis was uncommon unless the fragment was detached. They stated that patients with nondisplaced fragments could be treated conservatively but that acute displaced fractures should undergo immediate reduction and internal fixation. Bauer et al.¹⁷ concurred that osteoarthrosis of the ankle is a rare occurrence and found that skeletally immature ankles have the best prognosis for healing with conservative treatment. In summary, asymptomatic and nondisplaced OLT should undergo conservative treatment, whereas displaced or continued symptomatic lesions should be treated surgically.

Retrograde drilling is ideal for cystic subchondral lesions with intact articular cartilage. Using specialized systems, accurate drilling of the lesion is possible. This drill path provides revascularization, and the bone graft serves as osteoconductive and osteoinductive material. This technique has advantages over antegrade drilling in that it does not alter the actual articular surface integrity. Retrograde drilling of a talar OCD was first described in 1981 as an isolated case.²⁴ More recently, a modification of this technique with arthroscopic assistance was described. Clinical research has shown good clinical results with this technique.²³ A study by Taranow et al.²³ looked at 16 patients after retrograde drilling and grafting of OLTs. There were no complications and a significant increase in the American Orthopaedic Foot and Ankle Society (AOFAS) Ankle/Hindfoot score. This technique is recommended for the subchondral cyst on the basis of its early surgical success and the absence of complications associated with transmalleolar osteotomies, transmalleolar drilling, and chondrolytic debridement.

Cartilage Restoration Procedures

Although microfracture and drilling techniques produce a fibrocartilage tissue in the affected area, it does not produce normal hyaline cartilage. In efforts to restore a joint surface with more anatomic and favorable biomechanical properties, newer procedures have been developed to restore a hyaline cartilage surface. Lesions greater than 10 mm in diameter may be best managed primarily with cartilage restoration procedures instead of excision and drilling. ²⁵

Autologous osteochondral grafting (osteoarticular transfer system, mosaicplasty)

The osteoarticular transfer system (OATS) and mosaicplasty transplant viable plugs of cartilage and subchondral bone from various donor sites into the talar dome.

Single-plug systems, such as OATS, harvest a single, large plug to match the size of the lesion. This method is postulated to reduce the fibrocartilage ingrowth seen in multiple-plug system. Donor site morbidity, however, is a bigger concern because of the size of the graft. Arthrex OATS procedures were used in nine patients in a study by Assenmacher et al.²⁶ At an average of 9.3 months, MRI revealed stable graft osteointegration by DeSmet criteria in all patients. Patients reported significant clinical improvement on the basis of visual analog pain scales and the AOFAS Ankle/Hindfoot scores (average 80.2).⁴ Al-Shaikh et al.²⁷ reviewed the results of 19 patients who underwent the Arthrex OATS technique for lesions averaging 12 × 10 mm in 19 patients. Sixty-eight percent of these patients had failed prior attempts at excision, curettage, and/or drilling. At an average of 16 months, patients reported improvement in AOFAS Ankle/Hindfoot scores (88 average) and reported no significant donor site morbidity. Eighty-nine percent of these patients stated that they would have this procedure done again. Al-Shaikh et al.²⁷ concluded that the OATS procedure is a viable salvage technique for patients who failed prior debridement procedures.

In multiple-plug systems (mosaicplasty), a number of osteochondral plugs are harvested to fill the defect. These plugs can recontour the surface of the talar dome, but critics have found that up to 20% to 40% of the defect is replaced by fibrocartilage.²⁷ Gautier et al.²⁸ showed good to excellent results in 11 patients at an average of 24 months, using Sulzermedica’s SDS “Soft Delivery System.” The lesions in this study averaged 18 × 10 mm, and the authors made no recommendations for absolute size limits. Previous studies, however, recommended a lower size limit of 10 mm. Hangody et al.²⁵ looked at 36 patients treated with mosaicplasty at 2- to 7-year follow-up. All of these lesions were greater than 10 mm in diameter. Ninety-four percent of these patients reported good to excellent results using the Hannover scoring system, with no long-term knee donor site morbidity.

Osteochondral plugs can also be harvested from the ipsilateral talus. Sammarco and Makwana ²⁹ harvested osteochondral plugs form the medial and lateral talar facets in 12 patients. The authors reported significant improvement in the AOFAS Ankle/Hindfoot scores and found no structural failures in the donor site or graft site.

Autogenous chondrocyte implantation

If the osteochondral lesion is large (greater than 2 × 1 cm), it is not amenable to OATS or mosaicplasty because of the expected size of the donor defect. Autogenous chondrocyte implantation (ACI) is a new technique that is showing promise for these larger lesions in the knee and ankle. In 1994, Swedish investigators first reported on this novel technique for large osteochondral lesions in the knee.³⁰ They looked at 23 patients over a 2- to 7-year follow-up period with lesions measuring from 1.5 to 6.5 cm in diameter and in whom all prior treatments had failed. Eighty-eight percent of their patients had good or excellent results. Studies in the United States and further extensive studies in Sweden have validated these results at up to 10 years.³¹^–³⁴

ACI is indicated in younger patient ¹⁵^–⁵⁹ with focal osteochondral defects without diffuse arthritis. A “kissing lesion” on the tibial plafond is a contraindication to this procedure because results are very poor when this is present. Other patients who could benefit from this procedure are those with failed prior surgeries and those who have large lesions with extensive subchondral cystic changes. Multifocal lesions could be treated with ACI in some cases. Patients who should not undergo ACI are those who have not had an attempt at other forms of surgical treatment, those with early degenerative changes or osteoarthritis, or those with uncorrected malalignment or instability.

The basic principle is to harvest viable chondrocytes from the patient, culture the chondrocytes, and reimplant them into the patient. This technique requires a two-stage procedure. First, an arthroscopic evaluation of the lesion is undertaken. Arthroscopy allows a thorough evaluation of the size and shape of the lesion, as well as the overall integrity of the adjacent and opposite cartilage surfaces. A biopsy of healthy articular cartilage (approximately 200-300 mg) then is taken from a nonweight-bearing area of articular cartilage (typically the intercondylar notch of the knee in a separate arthroscopic procedure). This biopsy is sent for laboratory culture and growth of additional chondrocytes. The process involves enzymatic digestion of the tissue and cultivation, which leads to a tenfold increase in chondrocytes. After 2 to 3 weeks in culture under the presence of antibiotics to ensure sterility, approximately 10 to 12 million cells will be available for transplantation. The second stage of this procedure is the implantation of the cultured cells. Postoperative care is essential in ensuring a good result.

Giannini et al.³⁵ reported excellent results at up to 26 months in eight patients who underwent ACI for OLT. They not only showed improved clinical scores (AOFAS Ankle/Hindfoot scores improving from 32 to 91/100) but also showed regenerated areas of cartilage on follow-up arthroscopy and normal type II hyaline cartilage by histology. Minas and Peterson published a study of 14 patients with ACI at an average follow-up of 28 months.³⁶ They reported an 11/14 good to excellent outcome, with two poor results and one lost to follow-up. In a recent study on the economics and quality of life profile of this procedure, Minas³⁷ showed significant improvement in quality of life at 2 years, and the technique was found to be cost effective in comparison with other treatment modalities.

Other new techniques

There is a new interest in bulk fresh osteochondral allografts for the replacement of large areas of focal cartilage damage. Candidates are matched to donors on the basis of joint size, and the surgery is performed within 5 days of tissue recovery to optimize the survival of the donor cartilage. Tontz et al. report on 12 patients at an average of 21-month follow-up who had bulk tibiotalar allografts.³⁸ They reported intraoperative fracture in one patient and graft collapse in another, but overall satisfaction and relief of pain in the other 10 patients. They concluded that this technique shows promise for the treatment of articular cartilage defects in young, active patients. Gross et al.³⁹ performed fresh osteochondral graft transplantation in nine patients for OLT (one case was for acute open fracture of the talus). Six of the nine grafts remained viable at an average of 11 years. Three cases went on to arthrodesis because of graft resorption. In a literature review on the treatment of OLT, Caylor and Pearsall⁴⁰ conclude that bulk fresh allografts can provide excellent results. The concern with these fresh bulk allografts is the host immune reaction to viable cells within the graft and the possibility of major infections. Also, graft collapse has been shown to occur in some cases.⁴¹ More research in this area is needed to ensure the safety and efficacy of this procedure.

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