A Proposed Treatment Algorithm For Osteochondral Lesions Of The Talus

The broad term “osteochondral lesion of the talus” describes an injury or abnormality of the talar articular cartilage and adjacent bone.¹ We can describe lesions as a cartilage defect, bone cyst or subchondral bone cyst. Clinicians have used variety of terms to describe these injuries, including osteochondritis dissecans, osteochondral defect or osteochondral fracture.¹ Osteochondral lesions of the talus occur in up to 70 percent of acute ankle sprains and fractures. In more than one-third of these patients, conservative treatment fails and surgery is indicated.^1,2

If conservative treatment fails and surgical intervention is warranted, there are numerous options including: excision; excision and curettage; excision and curettage combined with microfracture (i.e., bone marrow stimulation); autogenous bone graft; retrograde drilling; and newer techniques such as osteochondral autograft transfer (OATS) and autologous chondrocyte implantation.³ Surgical management of osteochondral lesions of the talus has evolved with advances in ankle arthroscopy techniques as well as the new applications of biologic stimulation and allografting techniques to promote healing of osteochondral lesions of the talus.⁴

Surgical strategies for osteochondral lesions of the talus have substantially increased over the last decade. However, no high-quality, long-term or randomized controlled studies on the topic exist.^1,3 In addition, past publications seem to have a clear consensus regarding etiology of osteochondral lesions of the talus but there is significant controversy when looking at treatment efficacy and recommendations.⁵

Procedure selection is generally based on lesion size, location on the talar dome and/or a history of prior failed surgical management.² Historical treatment recommendations, however, have been based on expert opinion and lower quality studies.^2,3 To date, there has been one proposed surgical algorithm, which included general recommendations based broadly on lesion size.⁶ However, this study did not include factors such as location, history of prior surgery, condition of subchondral bone, presence of bipolar lesions or if the lesion was constrained or unconstrained. This leaves the surgeon with a difficult decision when deciding which procedure is best for the patient.

We have developed a surgical treatment algorithm to aid the surgeon with procedure selection based on the available literature, which takes into consideration multiple patient factors as well as characteristics of osteochondral chondral lesions of the talus (see “An Algorithm For Osteochondral Lesion Workup And Treatment” at right, or download the PDF). This algorithm describes initial workup recommendations followed by an easy to follow chart with surgical recommendations based on lesion size, location, timing, history of past surgery, presence of cyst and condition of the subchondral plate. The algorithm also includes a list of differential diagnoses to guide an additional workup if the listed characteristics do not match up with the individual patient presentation.

A Closer Look At The Authors’ Initial Workup Protocol

Patients with osteochondral lesions of the talus typically present with non-specific symptoms of vague ankle pain and/or a history of ankle injuries. They may complain of generalized pain, weakness, swelling, stiffness and/or limited ankle range of motion with catching or locking. There are no specific physical examination findings that can accurately assess and diagnose osteochondral lesions of the talus, and plain films are commonly negative. It is therefore important to have a high level of clinical suspicion in patients with persistent vague ankle pain and/or a history of ankle injuries.²

In addition to standard weightbearing ankle X-rays, we routinely obtain a weightbearing stress inversion view of the ankle to assess for concomitant lateral ankle instability.

Researchers have shown that radiographs alone miss osteochondral lesions of the talus in up to 50 percent of patients.¹ Therefore, magnetic resonance imaging (MRI) is often necessary in the diagnosis of osteochondral lesions of the talus. An MRI is the diagnostic modality of choice with the ability to assess both osseous and soft tissue pathologies frequently associated with osteochondral lesions of the talus. Magnetic resonance imaging reportedly has a sensitivity of 0.96 and a specificity of 0.96 in the diagnosis of these lesions.¹

Computed tomography (CT) is a useful adjunctive study for patients with an abnormal MRI to better evaluate the condition of the underlying subchondral and cancellous bone. However, it lacks the ability to assess cartilage condition in osteochondral lesions of the talus.² A CT scan is often more useful than MRI for advanced degenerative joint disease, in which assessment of bone quality and local deformity is more important than cartilage condition. Weightbearing CT is a newer modality that is particularly useful when working up patients for total ankle replacement (TAR).

Diagnostic joint injection is another important tool in the evaluation of osteochondral lesions of the talus. Pain relief is usually short-term (days and not weeks) and not specific, but a positive response to injection confirms that the pain source is intra-articular. Re-examination of the ankle five to 10 minutes after injection helps to document a positive response. Pre-injection pain on palpation at the anterior joint line is usually no longer present and the patient usually reports pain relief when walking in the office. One can also utilize joint injection prior to weightbearing stress inversion imaging.

What The Proposed Surgical Treatment Algorithm Clarifies

Procedure selection for osteochondral lesions of the talus is challenging due to the number of procedure options available. Our proposed algorithm systematically attempts to consider multiple characteristics of patient and lesion presentation that have implications for procedure selection.

Large lesions (osteochondral lesions with a large cyst > 3 cm) and bipolar lesions (adjacent talar and tibial lesions) associated with advanced degenerative joint disease do not respond well to simple debridement or cartilage resurfacing techniques (indicated in light blue in the algorithm). Procedure selection for end-stage disease largely depends on patient specific factors to decide between ankle fusion and TAR. Consider ankle fusion for patients who are under 50 years old, have a loss of protective sensation, have a high body mass index, varus or valgus deformity that TAR cannot correct, or poor skin quality (associated with age, stasis, or prior surgery). Total ankle replacement is perferable in the absence of these factors (see first case study).

When it comes to an unconstrained lesion, there is a lack of distinct margins such as a shoulder lesion with an underlying cyst. One would treat these lesions with an en bloc fresh frozen talus allograft, which typically requires a malleolar osteotomy (indicated in red in the algorithm). The surgeon should plan ahead regarding the incision, osteotomy, and bone resection since patients with advanced disease of this nature may require future revision to TAR.

For a cystic lesion that is constrained (intact margin of healthy bone and cartilage after debridement) but involves a breach of the subchondral bone plate, the surgeon can perform curettage and autograft of the cystic defect with allograft resurfacing to avoid malleolar osteotomy (indicated in green in the algorithm). An OATS procedure more often requires osteotomy and when surgeons use the procedure for large cystic lesions, there are reported success rates ranging from 74 to 100 percent.³

For an osteochondral lesion of the talus > 1.5 cm in diameter with intact subchondral bone plate and no associated subchondral cyst, one would typically treat this with curettage and microfracture/bone marrow stimulation combined with allograft resurfacing (indicated in purple in the algorithm) as we have described in the second case below (see second case study). In these cases, surgeons may use products such as particulated juvenile allograft (DeNovo NT Natural Tissue Graft, Zimmer Biomet) or dehydrated cartilage (BioCartilage, Arthrex). For lesions < 1.5 cm, one can utilize curettage and bone marrow stimulation. Many publications support bone marrow stimulation for lesions < 1.5 cm in diameter with an average success rate of approximately 85 percent (indicated in orange in the algorithm).³

Treat a subchondral bone cyst with intact joint surface and subchondral bone plate with either subchondroplasty or retrograde drilling with allograft (indicated in gray in the algorithm). The average success rate of retrograde drilling is reportedly 88 percent but this is supported by low level studies and none report lesion size or characteristics.³

Surgeons can perform an arthroscopic synovectomy (indicated in dark blue in the algorithm) to treat anterior ankle impingement without an osteochondral lesion of the talus. One can diagnose this condition based on a positive history and exam, a negative X-ray and MRI, and a positive response to diagnostic injection. Of note, a negative MRI does not rule out anterior impingement.

It is important to keep in mind that surgeons are not able to determine some of these factors until assessing the joint or lesion arthroscopically, which creates a challenge regarding consent, prior authorization, and availability of products. Two-stage treatment may therefore be necessary for unexpected intraoperative findings.

When To Consider Differential Diagnoses

The surgeon should consider non-articular diagnoses when the presentation does not fit with an osteochondral lesion of the talus. The differential diagnosis includes sinus tarsi impingement, peroneal tendinopathy, chronic ankle instability, posterior tibial tendinopathy, os trigonum syndrome and syndesmotic injury (indicated in brown in the algorithm).

Case 1: An example of total ankle replacement for osteochondral lesion of the talus lesion > 3 cm with advanced degenerative joint disease (indicated in light blue in the algorithm). A 52-year-old man presented to the clinic with chronic right ankle pain. The patient reported a previous work-related injury that was treated with ankle arthroscopy years prior to presenting to our office. He reported previous improvement in pain with a corticosteroid ankle joint injection every six months. His physical exam was remarkable for a slight varus stance position with crepitation and pain on ankle joint range of motion. Standard weightbearing radiographs and a weightbearing CT demonstrated advanced degenerative changes to the ankle joint with large subchondral cystic changes and bipolar lesions.

The decision to pursue TAR was based on patient age, history/symptoms and mild varus deformity. The patient had a normal body mass index, intact sensation and no skin quality concerns. The patient had a total ankle replacement, which resulted in rectus alignment. Postoperatively, the patient went on to heal uneventfully, resuming normal recreational and work activities with a noted improvement in pain and ankle joint range of motion.

Case 2: An example of a constrained cystic lesion with breach of subchondral bone (indicated in green in the algorithm). A 62-year-old retired woman presented for evaluation of chronic right ankle pain. The physical examination demonstrated tenderness along the anterior ankle joint line. No restriction or crepitus was present with ankle joint range of motion. The patient had an X-ray and an MRI prior to the appointment with primary care. The patient had an osteochondral lesion of the talus in the central talar dome with a breach of the subchondral plate and cystic changes. After receiving a diagnostic ankle joint injection, the patient noted immediate relief. Re-examination five minutes after injection revealed no pain but pain had returned at the time of the nurse’s phone call one week later.

Surgical treatment included ankle arthroscopy with curettage of the talar cyst, autograft of the talar defect and allograft resurfacing with BioCartilage. An OATS procedure would have been a reasonable alternative but is more expensive and more often requires tibial notchplasty or malleolar osteotomy.

The patient went on to heal uneventfully without complications. The last follow-up appointment was at eight months postoperative, at which time she reported no pain and improved range of motion. She had resumed her normal activities without restrictions. Postoperative radiographs were unremarkable with a stable lesion.

In Conclusion

Surgical options for the treatment of osteochondral lesions of the talus are numerous and have expanded over the past few years. To date, there are no randomized controlled trials on the efficacy of osteochondral lesion treatments and most publications that exist are of low quality with short-term follow-up and varying conclusions. In addition, there has yet to be a proposed treatment algorithm detailing procedure choice based on full consideration of lesion and patient characteristics.

These issues often lead surgeons to have to choose the best surgical procedure without clear clinical recommendations or evidence regarding the efficacy of individual treatments. While the proposed algorithm is only expert opinion, we intend it to be a tool to guide surgeon decision making for individual patients who present with an osteochondral lesion of the talus.

There remains a need for future research including randomized controlled trials with long-term follow-up to establish the efficacy of recommended treatments.

Dr. Boffeli is a board-certified foot and ankle surgeon practicing at HealthPartners Specialty Center in St. Paul, Minn. He is a Fellow of the American College of Foot and Ankle Surgeons, and the Director of the Foot and Ankle Surgical Program at Regions Hospital/HealthPartners Institute for Education and Research.

Dr. Schaefbauer is a third-year Chief Resident at HealthPartners Specialty Center in St. Paul, Minn.

References

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3. Zengerink M, Struijs PA, Tol JL, Van Dijk N. Treatment of osteochondral lesions of the talus: a systematic review. Knee Surg Sports Traumatol Arthrosc. 2010; 18(2):238-246.
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