Treating Osteochondral Lesions Of The Talus

Written by: Bob Baravarian, DPM

Offering a thorough primer on treating osteochondral lesions of varying sizes and comcomitant presentations, this author discusses key diagnostic principles and optimal procedure selection.

Surgeons have seen significant improvements in the past decade for the treatment of osteochondral lesions of the talus. Now there is a revolution of treatment options for what was once a troubling and difficult problem.

Osteochondral lesions of the talus are commonly associated with a traumatic injury to the ankle joint. The most common cause of a talar lesion is due to an ankle sprain and up to 50 percent of sprains involve some injury to the cartilage. Two common lesions are notable on the talus. The first is a posterior medial lesion and the second is an anterior lateral lesion. Both are due to differing forms of ankle sprains, causing lesion formation with either an inversion injury or an eversion injury.4 During the sprain, the talus grinds or slams against the tibia, resulting in damage to the underlying talar cartilage and bone region. A majority of osteochondral lesions may be silent in nature and may not cause significant pain. However, when an osteochondral lesion is present, patients may note pain with a sense of deep joint ache, locking, catching or instability associated with the ankle joint.5

Patients will often present to the doctor for care of an ankle sprain, either in an acute setting or in a chronic injury setting. Treatment of the ankle differs in the acute and chronic settings. Most commonly in the acute setting, the patient presents with an ankle sprain and treatment centers around the acute sprain. Standard radiographs are often normal. The only exception is in the case of a loose talar dome lesion, which will present on radiographs with a fleck of cartilage and bone loose or floating in the joint. However, most radiographs do not show symptoms of the osteochondral lesion.

In the acute setting of ankle sprain, patients protect the ankle with either a boot or brace. There is a period of four to six weeks of rest, ice and physical therapy in order to return the function of the ankle to a normal level. If there is chronic pain and difficulty with ambulation at the six-week mark, there should be further testing and treatment of a chronic injury, which I will further detail in this article.

Chronic ankle sprains are sprains that persist either after treatment of the acute stage of sprain for the first four to six weeks, or involve prolonged ankle pain resulting from a previous injury that is not healing normally. In such cases, consider an osteochondral lesion as part of the injury if there is a deep ache in the ankle joint with or without a locking or catching of the ankle joint. There may be additional factors contributing to the ankle pain such as synovitis of the joint, instability of the collateral ankle ligaments and a possible tear in the surrounding tendons, most commonly the peroneal tendons but also possibly including the posterior tibial tendon.

Examination of the osteochondral portion of injury is somewhat difficult but centers around pain in the ankle joint. Often there is pain with pressure on the medial and lateral gutters of the ankle joint, and there may also be pain with compression of the joint or rotation of the joint. One of the best diagnostic tests of an ankle osteochondral lesion of the talus is a diagnostic anesthetic injection of the ankle joint. Often, an ultrasound-guided injection allows infiltration of the ankle joint with local anesthesia, which decreases the feeling of pain in the joint. This anesthetic nerve block also allows better assessment of the extraarticular sources of pain such as tendon injury and ankle instability.

A Guide To Accurate Diagnostic Testing
The most common diagnostic testing of the ankle and osteochondral lesion of the talus is magnetic resonance imaging (MRI) of the ankle. A study by Verhagen and colleagues found MRI has a greater sensitivity in comparison to computed tomography (CT).

Perform the initial testing without contrast dye injection. The MRI, in acute or semi-acute cases, will show edema of the talus with overlying chondral damage. Note that in lesions that are chronic for several years, edema of the lesion site may be negative and, unless there is significant chondral damage, an MRI may not show the true level of damage to the region. In such cases, an MRI with contrast may show a region of articular damage that is shallow and does not involve the underlying bone surface. In most cases, an MRI will show some level of damage to the talus and is the best source of detailed information with regard to an osteochondral lesion.

Often, in an acute injury setting that does not respond to conservative care, an MRI may overread the level of damage. In such cases, the underlying bone contusion surrounding the lesion site may make the lesion seem larger than it actually is, which may change the underlying treatment. Therefore, if one suspects an osteochondral lesion and surgery is a consideration, a secondary evaluation with a CT scan of the ankle may show the true size of the lesion. This facilitates better surgical planning for a procedure that involves removing the subchondral bone and surrounding edema region. A CT scan is not first-line diagnostic imaging as it does not show additional potential ankle issues such as ligament and tendon damage. In these cases, surgeons often use CT as a confirmatory examination.

After establishing the presence of an osteochondral lesion, treatment options are often defined by the location and size of the lesion. Currently, my grading system is based on defining the circumferential size of the lesion, the depth of the lesion, the underlying subchondral edema of the lesion and the cystic changes associated with the lesion. Each of these factors affects the type of treatment that I suggest to the patient.

Key Insights On Conservative Care
Conservative care of an osteochondral lesion centers on resting the chondral surface in order to allow the lesion site to heal. Often, in chronic lesions lasting several months to several years, there is a lack of blood supply and necessary inflammation to the chondral lesion, which may negate the period of rest and protection of the lesion site. However, a non-weightbearing period with the use of crutches and boot protection may allow a superficial lesion with or without bone edema to heal.

We often will inject the joint, talar bone or both with a bone marrow aspirate and/or platelet-rich plasma (PRP) injection in order to stimulate healing. The PRP injection provides the inflammation necessary to allow healing to the area. Physicians often inject PRP into the ankle joint to inflame the joint and provide healing cells to the region.

If there is underlying bone edema, a bone marrow aspirate is best for injection into the bone surface. One can harvest the aspirate from the iliac crest, tibia or calcaneus for use in a bone marrow concentrate. Inject the concentrate through a small drill hole into the subchondral bone region. One can perform this in the office setting or operating room. The clinician can also inject the bone marrow aspirate in an intraarticular manner into the ankle joint to stimulate chondral healing. Another option is subchondral injection. In my experience, I have found stimulation of the injury greatly enhances the conservative treatment of an osteochondral lesion. I currently tend to approach lesions with a PRP and/or bone marrow injection if the patient can afford and is amenable to the treatment.

How The Size Of The Lesion Can Dictate Treatment
The larger the size of a lesion, the greater the potential that a cartilage transplantation will be necessary. Our current definition of size is divided into less than 5 mm, 5 mm to 10 mm and larger than 10 mm. Considering the fact that the talar surface is 40 mm by 40 mm or so in most patients, a lesion larger than 10 mm is approximately one-quarter of the surface of the talus and therefore encompasses a large portion of the region. Most smaller lesions are not painful or complicating if they are smaller than 3 mm.

Treat lesions from 1 mm to 5 mm with arthroscopic debridement and micro-drilling. Multiple studies have shown arthroscopy with microfracturing talar lesions of these size parameters facilitated improvement of function and reduction of pain in 65 to 90 percent of patients.9–13 One can add a bone marrow or PRP injection to stimulate healing, and this can also be helpful for general joint health. The surgeon can also add a cartilage replacement such as morselized cartilage replacement for additional scaffolding. Our preferred cartilage system for smaller lesions is BioCartilage (Arthrex).

One would commonly treat lesions between 5 mm and 10 mm in a similar manner to lesions 5 mm or smaller but proper debridement may require a small gutter incision to allow better visualization, debridement and cartilage replacement. We suggest adding a cartilage scaffold for this size lesion. Note that larger lesions often have deeper associated factors that physicians should address, which I will cover later in the article.

Treat lesions larger than 10 mm with a scaffold or true cartilage replacement. We have found the morselized scaffold to be inferior to a true cartilage replacement system with live cells. Therefore, we prefer DeNovo (Zimmer/Biomet) or Cartiform (Arthrex) to be a better system. The DeNovo system is a morselized live cartilage that is better suited to lesions that are difficult to access such as deep posterior lesions.

Use a gutter incision to access the joint and perform anterior distraction to visualize the cartilage damage. If ankle stabilization is also required, release of the ligaments prior to anterior joint distraction will allow better access. Place the cartilage in the lesion site after curettage and then repair the ankle ligaments with a modified Broström–Gould repair. If access is fairly easy with a mid-level medial lesion or a lateral lesion, the cartilage disc is slightly better as it is more stable. Curette the lesion, drill it, fashion the cartilage disc to fit into the lesion site and place it in the lesion. Suture the disc to the surrounding lesion or place an anchor in the talus, and suture down the cartilage disc. With DeNovo, Cartiform and the BioCartilage morselized cartilage system, one can place fibrin glue over the lesion to allow the material to adhere better.

When Lesions Have Associated Subchondral Cysts
If a lesion has associated subchondral cyst formation and there is superficial cartilage damage, there is often a break in the underlying bone surface, which allows the joint fluid to leak into the bone and cause cyst formation.
Often one can treat the lesion and cyst from an intraarticular approach. Debride the superficial cartilage and check the subchondral bone surface. If a deep lesion is present upon debridement, bone grafting is required and this bone graft can be allogeneic in nature or harvested from the patient. Allogeneic cancellous bone can fill the void and then one would cover the lesion as I described above with morselized cartilage or cartilage replacement. Again, a disc system is preferable over DeNovo as the disc has a better structure and can hold the bone graft in place better.

If the bone surface is stable but a significant subchondral cyst is present on MRI, an intraarticular subchondroplasty can fill the cyst and will incorporate. One can use any of the cartilage systems to cover the lesion. Again, a PRP or bone aspirate injection is helpful in such cases.

How To Treat A Subchondral Cyst Without Cartilage Damage
A subchondral cyst without superficial cartilage damage is rare and requires a different approach. In such a case, leave the cartilage alone and only check it with ankle arthroscopy. If the cartilage is damaged, perform a subchondral cyst approach as I have detailed above. If, however, the cartilage is stable, use a micro vector guide to treat the cyst only in order to prevent cartilage damage. In utilizing such a system, the surgeon would place the arthroscopic micro vector guide in the region of cartilage fraying and use a retrograde approach through the sinus tarsi to fill the cyst only.

There are two approaches that I currently suggest. Treat smaller lesions with a subchondroplasty and cyst fill. I will often add a bone marrow aspirate concentrate to the injection for stimulation. If the lesion is large, meaning more than 10 mm, I drill the lesion and fill it with a combination of bone graft and bone marrow aspirate concentrate. In my experience, this is better for true cyst filling and replacement of the bone with a true bone material.

When Patients Have Subchondral Edema Associated With A Talar Lesion
The treatment of subchondral bone has advanced and also changed with better understanding. Much like cartilage lesions, the underlying subchondral honeycomb bone may have damage, which results in pain. Treatment of the subchondral bone will aid in pain relief even if one treats the overlying cartilage.

Treat subchondral edema either through a retrograde approach from the sinus tarsi or from an intraarticular approach through the lesion site via subchondroplasty with or without a bone marrow aspirate add-on.

What You Should Know About Kissing Lesions
The most difficult lesions to treat are those that match on the tibia and talus surface. Surgeons often refer to these lesions as kissing lesions. Due to damage on bone surfaces, there is often greater pain and treatment is more significant. Our preferred treatment of such lesions is with a cartilage replacement system and the disc system has the best chance of success as it enables surgeons to place live cartilage on both surfaces.

It is important to warn patients that large kissing lesions tend to be very difficult to treat and, although pain will improve, pain may not completely resolve. There may also be a need for a second look and additional cartilage repair on one or both surfaces if pain continues. Finally, one may best treat large kissing lesions with significant damage with an ankle fusion or ankle replacement if primary treatment is not successful.

Addressing Massive Osteochondral Lesions
A massive lesion is one that encompasses one-third of the cartilage surface. Often, if not always, these lesions have large cystic underlying lesions and up to half of the talus is missing or has been eaten away by the cyst.

In such cases, a fresh allograft cartilage and bone replacement system are necessary. Perform either a medial or lateral malleolar osteotomy, remove the region of cartilage and remove bone damage in toto with an osteotomy. Replace the region with a block of fresh allograft replacement. Fixate the replacement region with either an absorbable, polyether ether ketone (PEEK) or headless fixation system. Protect the graft site until incorporation occurs, which surgeons can often verify with a CT scan. It is essential to be aware that these types of lesions often fail, resulting in massive bone loss and the need for a subtalar and ankle fusion with large bone graft placement in about 13 to 33 percent of patients.14–16

In Conclusion
Although the treatment of osteochondral lesions of the talus has evolved and improved, there is a need to understand the full spectrum of treatments and be well-versed in all forms of treatment in order to have a complete bag of tools necessary to treat these complicated occurrences. The size of the lesion is the main factor to consider. Secondary cyst formation and subchondral edema also add complicating factors but one can address these conditions at the time of lesion treatment. Finally, kissing lesions and massive lesions require an advanced level of knowledge and skill. The management of these lesions should be left to those who perform this type of care on a regular basis and are comfortable with the difficult treatment options for these lesions.

Dr. Baravarian is an Assistant Clinical Professor at the UCLA School of Medicine, and the Director and Fellowship Director at the University Foot and Ankle Institute in Los Angeles.

References

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