Is Cartilage Grafting Better Than Drilling For Osteochondral Lesions?

Yes, Tom Chang, DPM cites recent advances in the use of autografts and allografts, and emphasizes that hyaline cartilage is more durable than fibrocartilage.

   The last few years have seen the introduction of evolving techniques for osteochondral defects for talar lesions. These techniques include the use of autografts and allografts in single plugs or mosaic patterns.

   Surgeons have utilized similar techniques for chondral defects in the metatarsal heads as well. The degenerative changes in patients with hallux valgus or hallux limitus can present with lesions that can fall into the traditional types I to IV. Patients can also occasionally present with cystic changes within the talar dome or metatarsal heads. Magnetic resonance imaging (MRI) may be useful to image these cystic changes and recognize the deep marrow edema within the involved bone.

   Most of our traditional techniques include subchondral drilling, abrasion arthroplasty or microfracture. Penetration of drill holes through the subchondral bone plate will stimulate mesenchymal cells within the bone marrow to form fibrocartilage. This form of repair is functional but fibrocartilage definitely does not have the durability and strength of normal hyaline cartilage. A good analogy is to compare normal skin to a healed scar. The scar tissue is functional but never is as supple and healthy as normal skin.

   Studies have shown short-term success with fibrocartilage repair but patients with such joints usually return with pain and degenerative damage to the same areas within two to four years, especially when the repair is in weightbearing joints of the body. Once the repair fibrocartilage fails, the joints continue to undergo degeneration rapidly and progress onto end-stage arthrosis within a short amount of time.

A Closer Look At Allografts And Autografts

   In recent years, surgeons have used other forms of cartilage repair that attempt to replace these osteochondral defects with hyaline cartilage options. These have been in the form of both allografts and autografts. Several authors have described autografts as having good medium to long-term results. Hangody, et al., reported a seven-year follow-up on osteochondral autografts from the knee to the ankle joint. Osteochondral autografts have shown promise in providing the hyaline repair many have been seeking for these difficult lesions.1

   The available sites of donor tissue have initially been from the knee, mainly in the notch region or the lateral femoral condyle. Donor cartilage can only come from “non-essential, non-weightbearing” areas of a joint space. Although there is adequate surface area there, the biomechanical characteristics of this knee plug are not ideal for the loading properties of the ankle and the foot. The cartilage is also thicker than in the ankle and joints of the foot. Therefore, it would be helpful to have donor sites from the same joint in question.

Key Considerations With The Harvesting And Application Of Grafts

   We are now taking osteochondral grafts from the medial and lateral talar surfaces as well as the spring ligament area. There have been reports in the literature of successful outcomes with osteochondral autografts from the medial and lateral talar surfaces.2

   The spring ligament site, which derives from the plantar medial navicular, has become popular due to the radius of curvature one sees on many diseased joint surfaces. It is helpful to try and match this when possible. In the majority of cases, the donor sites are not backfilled and we have not seen any hemarthrosis to speak of.

   In communication with multiple members of the Podiatry Institute, surgeons have performed over 50 spring ligament grafts without talonavicular joint pain.

   Surgeons have utilized frozen allografts in the past but their popularity has dwindled as fresh grafts have become more common. Fresh talar allografts have also gained popularity recently with success and one can perform them for both unipolar (single sided) and bipolar (double-sided) repair. Brage and Bugbee have reported good success with a variety of these repairs in the ankle.3

   Manufacturers carefully screen these ankle grafts and the companies then release the grafts for implantation within weeks of procurement. The current recommendation is to implant the fresh cartilage within three to four weeks of procurement. The percentage of viable cartilage cells still present is extremely high in this timeframe.

   When one uses cartilage grafting in the repair of joint disease, it is also extremely important to discuss other mechanical contributions to the overall correction. It is often important to carefully assess biomechanical contributions to the deformity. It is imperative to create a better environment for the joint in question. In the forefoot, this will often require osteotomies.

What You Should Know About Cartilage Grafting And Joint Preservation

   The inclusion of cartilage grafting techniques does not change the overall approach to joint preservation. Consider metatarsal decompressional osteotomies in joint preservation cases with hallux valgus or hallux limitus. One can perform this behind the graft site and the site will still be within the metaphyseal portion of the bone. This will provide a much healthier long-term environment for the joint.

   There has been recent excitement over synthetic grafts showing evidence of hyaline cartilage repair. In vitro and in vivo models have documented the formation of hyaline cartilage into the graft site. Researchers have confirmed these findings with histopathological biopsies and tissue staining.

   It is important to place the synthetic grafts adjacent to healthy bone and cartilage tissue. Once the graft is in place, there is essentially a creeping substitution type of incorporation as both the bone and the cartilage heal in from the periphery inward. Depending on the size of the defect, this process reportedly takes one to two years. The central portions of the graft are the last to heal and fully revascularize.

   However, once the healing is complete, this provides the surgeon with an almost perfect cartilage repair in a synthetic form. The applications of this technology to our current practices will be limitless.

In Summary

   Surgeons continue to treat osteochondral defects on a daily basis. These newer techniques have given us the opportunity to achieve hyaline cartilage repair to these difficult problems. This improved repair will provide longevity to the joint and greater patient satisfaction when one is exploring joint salvage options.

Dr. Chang is the Chief of the Department of Podiatric Medicine and Surgery at the Sutter Medical Center in Santa Rosa, Ca. He is a Clinical Professor at the California School of Podiatric Medicine at Samuel Merritt College. Dr. Chang is a Fellow of the American College of Foot and Ankle Surgeons, and is a faculty member of the Podiatry Institute.

References

1. Hangody L, Vásárhelyi G, Hangody LR, et al. Autologous osteochondral grafting--technique and long-term results. Injury. 2008 Apr;39 Suppl 1:S32-9.

2. Marymont JV, Shute G, Zhu H, et al. Computerized matching of autologous femoral grafts for the treatment of medial talar osteochondral defects. Foot Ankle Int 2005 Sep;26(9):708-12.

3. Kim CW, Jamali A, Tontz W Jr, Convery FR, Brage ME, Bugbee W. Treatment of post-traumatic ankle arthrosis with bipolar tibiotalar osteochondral shell allografts. Foot Ankle Int. 2002 Dec;23(12):1091-102.

No, Thomas Brosky II, DPM, notes the advantages of retrograde drilling and emphasizes its ability to promote revascularization and healing.

   Talar dome lesions are typically a result of trauma to the ankle mortise. However, there is much confusion within the literature about the terminology associated with this pathologic process.

   Osteochondritis dissecans (OCD) is the term we generally use in describing this condition. Actually, “osteochondritis” implies an inflammatory process of the bone and cartilage, which is not always the case. The term “dissecans,” from the word “dissect,” implies a loose fragment of bone or cartilage, which may or may not be present. Since most cases are the result of traumatic insult, the term “osteochondral fracture” (OCF) is more appropriate.

   The thinking is that direct trauma or microtrauma causes separation and damage to the overlying articular cartilage. This cartilaginous fracture can then extend through the subchondral bone and cause focal osteonecrosis and loose body fragments. Motion occurring at the osteochondral fracture site can lead to cystic formation from an influx of synovial fluid and further avascular necrosis of the underlying subchondral bone. The articular cartilage receives much of its nutrition from the synovial fluid via diffusion and is typically spared.1 For this reason, it is crucial to make an appropriate assessment of the condition preoperatively.

Essential Diagnostic Insights

   Physicians frequently misdiagnose osteochondral fractures of the talar dome upon initial presentation. Once the initial edema has resolved, patients will complain of pain with weightbearing activities. Other symptoms include ankle locking, stiffness, chronic swelling and instability. Patients who present with a history of chronic ankle sprains are generally at higher risk for transchondral fractures.

   The initial evaluation should include routine radiographs of the ankle mortise. Various authors have reported that standard radiographs range from being 60 to 100 percent diagnostic. 2-4 While standard radiographs can detect subchondral bone lesions, they are inadequate for articular cartilage pathology. Technetium-99m bone scans can be helpful in detecting transchondral fracture but lack specificity in determining soft tissue pathology. Computed tomography (CT) possesses challenges similar to using bone scans for cartilage disease.

   When dealing with potential transchondral fractures, there are two important questions that one should answer.

   1. What is the viability of the articular cartilage?
   2. Is there significant subchondral bone pathology?

   Typically, magnetic resonance imaging (MRI) is the standard in determining the amount of subchondral bone disease but is not always accurate in detecting cartilage damage. Violation of the subchondral bone plate with granulation tissue and fluid accumulation may imply cartilage disease, but arthroscopy is the superior technique in evaluating cartilaginous lesions.

   Taranow, et al., described a method of staging using MRI to diagnose bone lesions and arthroscopy to determine the final condition of the articular cartilage. 5 This technique provides a more accurate method of determining whether more aggressive approaches are necessary to repair the lesion.

Understanding The Rationale For Retrograde Drilling

   When we diagnose stable lesions with MRI or arthroscopy, we are assuming the articular cartilage is intact and the underlying bone is avascular. This condition can predispose the cartilage to degeneration and loosening. It makes more sense to replace the underlying bone disease with healthy bone than it does to drill the “healthy” cartilage from above and damage it further.

   Antegrade drilling of the subchondral bone is widely accepted but surgeons should avoid it if they have confirmed that the cartilage is stable. Traditional antegrade drilling techniques have provided satisfactory short-term results but the literature demonstrates high rates of arthrosis with long-term follow-up. 6-8

   Retrograde drilling causes capillary ingrowth of bone beneath the cartilage and hence a more stable environment for revascularization and healing. Kono and colleagues compared transmalleolar drilling to retrograde drilling of talar dome lesions with intact cartilage. When they performed arthroscopy one year after the procedure, they found that eight out of the 19 lesions treated with transmalleolar drilling had deteriorated from grade 0 to grade 1 lesions. Alternatively, out of the 11 lesions treated with retrograde drilling, three improved from grade 1 to grade 0 lesions and eight lesions remained unchanged. 9

   When high-grade articular damage is present, surgical treatment should be based on the size of lesion, location and the age of patient. Surgical options include debridement of the lesion with curettage or abrasion of the bone bed, internal fixation of the fragment and bone grafting.

   In recent years, surgeons have used allografts to replace degenerative cartilage. However, when large defects are present (> 1.5cm2), it makes more sense to replace “dead tissue” with “healthy tissue.” Autogenous osteochondral grafts from the knee and talus can provide excellent sources of healthy transplantable tissue.

Pertinent Pearls On The Retrograde Drilling Technique

   After identifying the location and degree of subchondral bone pathology on MRI, utilize arthroscopy to determine cartilage viability. Surgeons can access medial lesions through the sinus tarsi region laterally and lateral lesions through the talar body medially.

   Make a 1 cm incision over the entry site to the talus and use fluoroscopy to determine the position of guide wire placement. Use the arthroscope to confirm that there is no penetration of the cartilage by the guide wire. Once the guide wire is within the subchondral bone pathology, one can remove the scope. Then place a cannulated drill (3.5 to 6.5 mm) over the guide wire and drill to the lesion under direct fluoroscopic visualization.

   For large cystic lesions in subchondral bone (>2.0cm2), I have adapted spinal equipment (Spineology®) to shape the defect and remove debris. Then backfill the defect with autogenous bone graft from your preferred site. An accessible donor site is the lateral calcaneus, where the surgeon makes a small incision and uses a bone trephine to obtain cancellous bone.

In Conclusion

   When MRI is not conclusive in determining cartilage health, arthroscopy can provide a valuable tool in evaluating this micropathologic process. When stable lesions are present, one should avoid violating the articular cartilage. Simply repairing osteonecrotic subchondral bone can aid in the long-term viability of cartilage and prevent arthrosis. This technique offers a relatively quick procedure with a high yield of success.

Dr. Brosky is a Fellow of the American College of Foot and Ankle Surgeons. He is an attending surgeon at DeKalb Medical Center in Decatur, Ga. He is in private practice at the Foot and Ankle Clinic of Oakwood in Oakwood, Ga.

References

1. Naumetz VA, Schweigal JF. Osteocartilaginous lesions of the talar dome. J Trauma, 20:924-927,1980.

2. Parisien JS. Arthroscopic treatment of osteochondral lesions of the talus. Am J Sports Med, 14:211-217, 1986.

3. Pettine KA, Morrey BF. Osteochondral fractures of the talus – along term follow-up. J Bone Joint Surg, 69B:89-92, 1987

4. Van Buecken K, Barrack RL, Alexander AH, et al. Arthroscopic treatment of transchondral talar dome fractures. Am J Sports Med, 17:350-356, 1989.

5. Taranow WS, Bisignani GA, Towers JD, Conti SF. Retrograde Drilling of Osteochondral Lseions of the Talar Dome. Foot Ankle Int Aug 1999; 20(8):474-80.

6. Alexander AH, Lichtman DM. Surgical treatment of transchondral talar-dome fractures (osteochondritis dissecans). J Bone Joint Surg, 62A:646-652,1980.

7. Angermann P, Jensen P. Osteochondritis dissecans of the talus: long-term results of surgical treatment. Foot Ankle,10:161-163, 1989.

8. Canale ST, Belding RH. Osteochondral lesions of the talus. J Bone Joint Surg, 67A:97-102,1980.

9. Kono M, et al. Retrograde drilling of Osteochondral lesions of the talar dome. Am J Sports Med 34:1450-1456,2006.

For further reading, see “How To Address Osteochondral Lesions” in the September 2005 issue of Podiatry Today.
Also check out the archives at www.podiatrytoday.com.