You are in: eMedicine Specialties > Orthopedic Surgery > FOOT AND ANKLE Osteochondral Lesions of the TalusArticle Last Updated: Nov 6, 2007AUTHOR AND EDITOR INFORMATIONSection 1 of 12
  Author: Gregory C Berlet, MD, FRCS(C), Clinical Assistant Professor of Orthopedics, Chief of Foot and Ankle Surgery, Department of Orthopedic Surgery, Ohio State University College of Medicine and Public Health, Fellowship Director of Orthopedic Foot and Ankle Center Gregory C Berlet is a member of the following medical societies: American Medical Association, American Orthopaedic Foot and Ankle Society, Canadian Medical Association, Canadian Orthopaedic Association, College of Physicians and Surgeons of Ontario, Ontario Medical Association, and Royal College of Physicians and Surgeons of Canada Coauthor(s): Christopher Hyer, DPM, Advanced Podiatric Surgery Fellowship Director, Foot and Ankle Surgery, Orthopedic Foot and Ankle Center; Robert D Santrock, MD, Consulting Surgeon, Orthopedic Associates of Meadville, PC; Thomas H Lee, MD, Assistant Professor of Orthopedic Surgery, Chief, Section of Foot and Ankle Surgery, Department of Orthopedic Surgery, Ohio State University College of Medicine; Consulting Surgeon, Orthopedic Foot and Ankle Center Editors: James K DeOrio, MD, Director of Foot and Ankle Fellowship Program, Assistant Professor of Orthopedic Surgery, Orthopedic Surgery, St. Luke's Hospital, Jacksonville, Florida; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Shepard R Hurwitz, MD, Director of Clinical Services, Department of Orthopedic Surgery, University of Virginia School of Medicine; Director, Division of Foot and Ankle Surgery, Department of Orthopedic Surgery, University of Virginia Health System; Dinesh Patel, MD, FACS, Associate Clinical Professor of Orthopedic Surgery, Harvard Medical School; Chief of Arthroscopic Surgery, Department of Orthopedic Surgery, Massachusetts General Hospital; Jason H Calhoun, MD, FAAOS, Chairman, J Vernon Luck Distinguished Professor, Department of Orthopedic Surgery, University of Missouri Author and Editor Disclosure Synonyms and related keywords: osteochondritis dissecans, OCD, subchondral bone fracture, transchondral talus fractures, osteochondral lesions of the talus, OLT, knee fracture, elbow fracture, ankle fracture, joint disorder, osteochondral autograft transfer system, autologous chondrocyte transplantation, Cheng classification system, Berndt and Harty classification system, Ferkel classification system INTRODUCTIONSection 2 of 12
  History of the ProcedureThe earliest report of osteochondritis dissecans (OCD) was published in 1888 by Konig,1 who characterized a loose body formation associated with articular cartilage and subchondral bone fracture. In 1922, Kappis described this process in the ankle joint.2 On the basis of a review of all literature describing transchondral fractures of the talus, Berndt and Harty developed a classification system for radiographic staging of osteochondral lesions of the talus (OLTs).3 Their classification system has been the foundation for other systems, yet it remains the most widely used system today (see Staging). (See also the eMedicine articles Congenital Vertical Talus and Osteochondritis Dissecans, as well as Fresh Osteochondral Grafting in the Treatment of Osteochondritis Dissecans of theTalus, on Medscape.) FrequencyOsteochondral lesions are rare joint disorders. Most often, they affect the knee, followed by the elbow and the talus. Lesions of the talus account for 4% of all osteochondral lesions in the body.4 EtiologyBoth Konig and Kappis believed that lesions due to OCD were the result of ischemic necrosis of the underlying subchondral bone that eventually led to separation of the fragment and its overlying articular cartilage.1, 2 Inflammation has not been shown to be a significant factor in the etiology of OCD. Therefore, the term OCD may be misleading. Assenmacher proposed the term osteochondral lesions of the talus, or OLTs.5 A history of trauma is documented in more than 85% of patients.6, 7, 8, 9, 10 Pritsch et al reported that a traumatic event preceded 75% of both medial and lateral lesions in 24 patients.11 Trauma is implicated less often in posteromedial lesions.4, 12, 13 Although the etiology of nontraumatic OLTs is unknown, a primary ischemic event may cause this form of the disease. Nontraumatic OLTs can also be familial. Multiple lesions can occur in the same patient, and identical medial talar lesions have occurred in identical twins.14 PathophysiologyAnterolateral lesions on the talar dome result from inversion and dorsiflexion forces, which cause the anterolateral aspect of the talar dome to impact the fibula. These lesions are usually shallower and more wafer shaped than medial lesions, possibly because of a more tangential force vector that results in shearing-type forces.15 Posttraumatic medial lesions are deeper and cup shaped. They result from a combination of inversion, plantarflexion, and external rotation forces that cause the posteromedial talar dome to impact the tibial articular surface with a relatively more perpendicular force vector. A study of the contact pressures on the talus with varying degrees of lateral ligament transections and ankle positions showed that the medial rim of the talus was subjected to high pressures, even without ligamentous transection.15 Results of another study implicated the difference in cartilage stiffness; the tibial cartilage is 18-37% stiffer than the corresponding sites on the talus.16 The results of other studies indicated that the mean cartilage thickness is inversely related to the mean compressive modulus.17, 18 These findings may lend credence to the clinically observed etiology of OLTs (ie, repetitive overuse syndrome in medial lesions and an acute traumatic event in lateral lesions). Observations from biomechanical studies suggest that the size of the lesion may alter the contact stresses in the ankle. Statistically significant changes in contact characteristics occur with lesions larger than 7.5 mm X 15 mm; this finding indicates that lesion size may play a role in predicting long-term outcome.19 ClinicalIn most cases, the mechanism of injury is an inversion injury to the lateral ligamentous complex. Patients typically present with chronic ankle pain along with intermittent swelling and, possibly, weakness, stiffness, instability, and giving way. Upon physical examination, assess joint laxity with the anterior drawer test and assess strength by comparison with the contralateral ankle. Physical examination findings of joint laxity are uncommon. Palpation may reveal tenderness behind the medial malleolus when the ankle is dorsiflexed, indicating a posteromedial lesion. Anterolateral lesions may be tender when the anterolateral ankle joint is palpated with the joint in maximal plantarflexion. INDICATIONSSection 3 of 12
Conservative treatment should be attempted first, whenever possible. Studies have shown that a trial of conservative treatment has no adverse effect on subsequent surgical intervention.4, 13 One study demonstrated that nonoperative conservative treatment can sometimes result in healing of higher-stage lesions.9 After a period of immobilization followed by physical therapy, patients with continued symptoms should be evaluated with MRI and other imaging studies to assess the condition of the articular cartilage and stability and to detect any intra-articular bodies.20 Symptoms of intra-articular derangement are indications for operative intervention. Such symptoms include effusion, catching or locking of the ankle, instability preceded by pain, and ankle pain relieved with diagnostic lidocaine. RELEVANT ANATOMYSection 4 of 12
The dome of the talus is covered by the trochlear articular surface, which supports the weight of the body. The talar dome is trapezoidal in shape, and its anterior surface is on average 2.5 mm wider than the posterior surface. The medial and lateral articular facets of the talus articulate with the medial and lateral malleoli. The articular surface of these facets is contiguous with the superior articular surface of the talar dome. Approximately 60% of the talar surface is covered by articular cartilage. The talus has no muscular or tendinous attachments. Most of the blood supply of the talus enters through the neck via the sinus tarsi. The dorsalis pedis artery supplies the head and neck of the talus. The artery of the sinus tarsi is formed from branches of the peroneal and dorsalis pedis arteries. The artery of the tarsal canal branches from the posterior tibial artery. The sinus tarsi artery and the tarsal canal artery join to form an anastomotic sling inferior to the talus, from which branches enter the talar neck. CONTRAINDICATIONSSection 5 of 12
Surgery to treat OLTs is contraindicated when the risks outweigh the perceived benefits. Risks include active infection in the operative area, patient noncompliance, and medical instability in patients. Relative contraindications include degenerative changes of the ankle involving more than an isolated OLT. WORKUPSection 6 of 12
Imaging Studies
Diagnostic Procedures
StagingAn OLT should be staged. MRI is used to evaluate the quality of the overlying cartilage and to assess the stability of the lesion. Several staging systems have been developed on the basis of the first system that Berndt and Harty proposed in 1959.3 In 1996, Ferkel modified this classic system and developed another system, based on CT.28 Ferkel's system corresponds to the stages in the Berndt and Harty classification but also considers fragment separation, the presence of subchondral cysts, and the extent of osteonecrosis.
TREATMENTSection 7 of 12
Medical therapyConservative management of OLTs should be attempted first. Symptomatic patients with negative findings on plain radiographs should undergo an initial period of immobilization, followed by physical therapy. Studies have shown that a trial of conservative therapy does not adversely affect surgery performed after conservative therapy has failed.4, 13 Patients whose plain images indicate OLTs and those who remain symptomatic after 6 weeks should undergo additional evaluation with MRI. Surgical therapySurgical treatment depends on a variety of factors, including patient characteristics (eg, activity level, age, degenerative changes) and lesions (eg, location, size, chronicity). However, surgical treatment adheres to 1 of the following 3 principles:
Preoperative detailsRadiographic imaging is essential to assess alignment and grade the OLTs. A marked distortion of normal mechanical alignment must be corrected at the same operative setting as the surgery to address the OLTs. Grading the OLTs allows for proper prognostication and influences whether the lesion can be approached with an antegrade or retrograde technique. Intraoperative detailsSurgical exposure When anterolateral OLTs are treated, open surgical exposure is accomplished via an anterolateral approach to the ankle joint. Plantarflexion aids in exposing the lesion; however, this approach requires caution to avoid damaging the branches of the superficial peroneal nerve. The open approach is also challenging when treating posteromedial OLTs. An osteotomy cut that enters the joint too far laterally can endanger the weight-bearing plafond, and a cut that enters the joint too far distally on the medial malleolus limits exposure. Screw holes must be predrilled before osteotomy. In addition, care must be taken to avoid injury to the allograft nerve and vein, anterior tibial tendon, posterior tibial tendon, flexor digitorum longus (FDL), posterior tibial artery, and tibial nerve. An apex proximal chevron bone cut provides excellent visualization,6 and Cohn et al30 had no nonunions or malunions when using a chevron medial malleolar osteotomy in 19 patients. Posteromedial OLTs have also been treated by using a combined anterior and posterior arthrotomy exposure. This approach allows access to 80% of the talar dome while it avoids the medial malleolar osteotomy in most cases.31 Arthroscopic treatment of OLTs can be accomplished using wide-angle 2.7-mm arthroscopes, which provide more maneuverability than traditional 4- and 5-mm arthroscopes. Noninvasive joint distraction techniques enable easier visualization of the entire talar dome. Treatment of a completely detached lesion For a completely detached lesion believed to be inappropriate for internal fixation, removal of the loose body and debridement of the bony bed are indicated. The base of the bed should be debrided back to bleeding bone, and the edges should be trimmed back to viable cartilage. Instruments available for use in this procedure include blunt-tipped probes, pituitary graspers, gouges, Kirschner wires, awls, full-radius shavers, ring curettes, and high-speed burrs. Studies have shown that excision and nonoperative treatment yield poor results and that excision, curettage, and drilling provide the best outcome.32 Treatment of intact lesions Drilling of the subchondral bone creates channels to enable revascularization of the fragment. Drilling can be accomplished using existing arthroscopic portals, a curved meniscus-repair needle guide,33 and transmalleolar drill holes.22 Sinus tarsi approaches to posteromedial lesions, also known as retrograde drilling or transtalar drilling, do not disrupt the articular surface. Retrograde drilling can facilitate bone grafting, which is ideal for large subchondral cystic lesions with intact articular cartilage. The COLT (Interpore Cross, Irvine, Calif) provides for accurate positioning of the drill hole and a cannula for bone graft delivery. Studies have shown good clinical and radiographic results using transarticular/transmalleolar drilling34 and retrograde/transtalar drilling.35 Internal fixation The use of traditional bone screws passed in an antegrade fashion is discouraged because irreparable damage to the intact articular cartilage results. Screw fixation is typically used for anterolateral lesions only because of the difficulty in gaining good exposure for posteromedial lesions. Kirschner wires can be inserted retrograde through a nonarticular portion of the talus. Bioabsorbable pins can be advanced immediately below the articular surface, then cut off at the skin. Bone grafting The authors have reported successful fixation after autogenous osteochondral grafting of an osteochondritis dissecans of the knee.36 Another report described treating 27 large (8 mm X 8 mm and larger) ankles with a cortical bone peg technique.37 The pegs, which were 2-3 mm wide and 15-20 mm long, were harvested from the distal tibia and passed through the articular surface. They reported good clinical results in 89% of their patients at an average 7 years of follow-up. Another study, with an 11-year mean follow up, reported 9 cases of fresh osteochondral allografting.38 Of 9 grafts, 6 remained in situ, and 3 patients required ankle arthrodesis because of resorption and fragmentation of the graft. These authors discourage the use of allografting in OLTs. Another study reported a high rate of complications in patients who underwent tibiotalar osteochondral allografting.39 Autologous osteochondral grafting (OATS, mosaicplasty) These techniques involve grafting a plug from the femoral trochlea or condyle into the OLTs on the talar dome. The OATS procedure transplants a single plug into the OLTs, and mosaicplasty is used to harvest and transplant multiple plugs. Single-plug grafts result in reduced ingrowth of the fibrocartilage, although donor-site morbidity may be greater because of harvesting a single, larger plug. The mosaicplasty procedure is said to provide a better match to the talar dome contour and surface area of the defect, although 20-40% of the defect is filled with fibrocartilage.40 Several groups have reported good results using both procedures. Eleven patients who underwent mosaicplasty had good to excellent results at 24 months.41 The lesions averaged 18 mm X 10 mm, and there were no adverse effects on the knee. Another study reported that 94% of 36 patients undergoing mosaicplasty had good-to-excellent results, with follow-up ranging from 2-7 years.42 Previous surgical procedures had failed in 29 of the patients. In another study, plugs were harvested from the ipsilateral medical or lateral articular facet of the talus in 12 patients. Significant improvement in American Orthopaedic Foot and Ankle Society (AOFAS) scores was reported, and no structural failures occurred in the graft or donor site.43 Autologous chondrocyte transplantation Two reports describe good early results with autologous chondrocyte transplantation (ACT). Koulalis et al reported the results of ACT in 8 patients, with an average follow-up of 17.6 months.44 Patients first underwent diagnostic arthroscopy, cartilage biopsy, chondrocyte extraction, and culture. An average of 2.5 weeks later, arthrotomy, malleolar osteotomy, bone debridement, and chondrocyte transplantation were performed. Patients were kept on non–weight-bearing status for 6-7 weeks. Routine arthroscopic examination performed 6 months after the transplant showed cartilagelike tissue completely covering the OLTs. (Histologic examination of 1 biopsy sample did not show hyaline cartilage.) Giannini et al reported similar results 24 months posttransplant, showing that hyaline cartilage can be transplanted in the ankle joint and good function can be expected.45 ACT has been performed more often in the knee. Results of the first 100 patients undergoing this procedure in a multicenter, 5-year study found that 79% showed improvement at 5 years. Compared to a control group undergoing different procedures, such as drilling or abrasionplasty, patients undergoing the transplant procedure had better functional outcomes.46 Coexisting OLT and ligamentous instability Acute ankle ligament injuries with a large unstable fragment typically first undergo surgical repair of the talar lesion. The ligament is allowed to heal postoperatively. Treatment decisions for treating chronic OLTs with chronic ankle instability are less clear. Postoperatively, OLTs require early motion, which is not appropriate for reconstructed ligaments. Options include first repairing the OLTs and then repairing the ligamentous injury at another time or repairing the 2 injuries simultaneously and postponing early ankle motion until the ligament has healed. Thermal capsular shrinkage may also be a possible treatment solution.36 Postoperative detailsA postoperative rehabilitation program should be tailored to each patient's individual circumstances and goals by a licensed physical therapist. Rehabilitation can generally begin after healing is demonstrated, which may occur after 6-7 weeks of non–weight-bearing status if drilling or internal fixation was performed. With the goal of attaining full ankle range of motion, physical rehabilitation includes active and passive range-of-motion exercises and a home program, edema control, and strength and proprioceptive training. Follow-upPain following operative treatment of OLTs is common for up to a year. MRI changes, including edema, are slow to resolve and often match the patient's report of an achy feeling in the joint. After 6 months, a persistent effusion, a catching sensation, or severe pain signifies that healing is not progressing as intended, and further investigation with CT or MRI is appropriate. For excellent patient education resources, visit eMedicine's Foot, Ankle, Knee, and Hip Center and Imaging Center. Also, see eMedicine's patient education articles Ankle Arthroscopy, Understanding X-rays, and Magnetic Resonance Imaging (MRI). COMPLICATIONSSection 8 of 12
Operative treatment for OLTs has inherent risks. Open exposure entails use of a medial malleolar osteotomy or anterior plafond bone block to gain exposure of the tibiotalar joint. The medial malleolar osteotomy typically heals well with low incidence of nonunion,30 but care must be taken to correctly place the osteotomy and protect the adjacent tendons and neurovascular structures. An anterior tibial bone block access window is associated with a lower risk of malunion but may limit access to posterior lesions.43 Arthroscopic intervention is associated with less surgical morbidity and joint stiffness, decreased rehabilitation time, and an increased functional outcome.47 Schuman reviewed 22 patients who underwent arthroscopy with curettage and drilling at an average follow-up of 4.8 years, with 86% good-to-excellent results.48 Complications associated with arthroscopy include hyperesthesia around the portal incision and, occasionally, neuralgia of the superficial peroneal nerves, but these were minor and transient. Some have advocated the use of allograft implants, but these grafts may become resorbed over time and fragment, necessitating the need for ankle arthrodesis.38 So far, no reports have been made of allograft rejection by the host. The osteochondral transplantation procedures have the additional risk of a second surgical site, which adds to the risk of possible complications. A 4-year follow-up of 36 mosaicplasty patients reported 6 patients with donor-site complaints during strenuous exercise, but this resolved after the first year.42 The OATS procedure is thought to have greater donor-site morbidity, since larger plugs are taken than those taken with the mosaicplasty. Gautier et al evaluated 11 patients at a 24-month follow-up and found 10 of 11 had graft incorporation and were without major complications.41 Patients may subjectively report mild pain or stiffness in the knee or ankle, but this is without objective deficits. Other authors have similarly found good graft incorporation without serious complications.5, 42 Restoration of articular surface congruity may be very difficult particularly in talar shoulder lesions. ACT is relatively new, and published reports are few but include good results.44 The procedure does necessitate 2 operations and is technically difficult, but no complications have been reported. OUTCOME AND PROGNOSISSection 9 of 12
Nonoperative treatments of OLTs are associated with published success rates of 45-50%.32, 49 Operative interventions have repeatedly been reported with significantly better success rates. In the meta-analysis by Tol et al, the combination of excision, curettage, and drilling has an 85% success rate and better outcomes than does excision and curettage without drilling or excision alone.32 Autologous osteochondral grafting has likewise had favorable outcomes. Reports on both mosaicplasty and OATS for OLTs have reported success rates around 90% at follow-up of 4 years and 16 months.40, 42 The ACT procedure in the knee has been associated with good-to-excellent results at a 2-year follow-up.50 In the ankle, good results have been reported with arthroscopically confirmed cartilage coverage of the graft site, but whether this newly generated cartilage with hold up to the stresses on the ankle is yet to be seen.51 FUTURE AND CONTROVERSIESSection 10 of 12
Future controversies will likely revolve around minimizing operative morbidity and costs. Early reports with allografts have shown some subsidence and resorption, necessitating ankle arthrodesis. If this trend continues, the use of allografts will likely fall from favor. Thus far, autologous osteochondral grafting seems to be the most reproducible and stable grafting technique. As this procedure gains favor, more reported complications of the knee donor site may evolve. The ACT procedure is based on actual repair of deficits of articular cartilage. Additional histologic and long-term clinical data are needed to determine the success or failure rate of this therapy. Currently, this technology is fairly cost prohibitive, with the expense of cell culturing and 2 surgeries. Future possibilities may include the use of adhesive patches instead of the periosteal flap and the addition of growth factors.51 MULTIMEDIASection 11 of 12
REFERENCESSection 12 of 12
Osteochondral Lesions of the Talus excerpt Article Last Updated: Nov 6, 2007 | ||||||||||||||||||||||||||||||||||||||||||
