Osteochondral defects of the talus treated with autologous bone grafting

We reviewed, retrospectively, 13 patients who had undergone open anterograde autologous bone grafting of the talus for symptomatic osteochondral defects of the dome of the talus. The mean age of the seven men and six women was 38.4 years. The defects included the full thickness of articular cartilage, extended through the subchondral plate and were associated with subchondral cysts. Six patients (46%) were clinical failures requiring further surgery. Of the remaining seven, functional outcome results were obtained at a mean of 51.9 months after surgery. The mean outcome scores for the Musculoskeletal Outcomes Data Evaluation and Management System foot and ankle questionnaire and the American Orthopaedic Foot and Ankle Society ankle-hindfoot scale were 87.0 and 84.3, respectively. There was an overall 46.2% patient satisfaction rate. We believe that the technique of autologous bone grafting presented should be used with extreme caution, when considered as the primary treatment for the adult patient with a symptomatic advanced osteochondral defect of the talus.     

Autologous osteochondral grafting for talar cartilage defects

The purpose of this study was to evaluate the clinical results of Osteochondral Autograft Transfer System (OATS) for the treatment of symptomatic osteochondral defects of the talus using standardized outcome analysis. Nineteen patients with symptomatic osteochondral defect (OCD) of the talus were treated with autologous osteochondral grafting. There were six men and 13 women. The average age was 32 years (range, 18 to 48 years). The average duration of symptoms prior to surgery was 4.2 years (range, three months to 12 years). All patients had failed nonoperative treatment, and 13 (68%) patients had failed prior excision, curettage and/or drilling of the lesion. The average size of the lesion prior to autografting was 12 mm x 10 mm (range, 10 x 5 mm to 20 x 20 mm). Donor plugs were harvested from the trochlear border of the ipsilateral femoral condyle. Ankle exposure was obtained with a medial malleolar osteotomy in 13 patients, arthrotomy in five patients and lateral malleolar osteotomy in one patient. Clinical evaluations were performed for both the recipient ankle and donor knee using the AOFAS Ankle/Hindfoot Scale and Lysholm knee scale, respectively. The average follow-up time was 16 months (range, 12 to 30 months). The average postoperative AOFAS ankle score was 88 (range, 60 to 100). Most patients had occasional mild pain, but excellent function, range of motion, stability and alignment. The average postoperative ankle score for the 13 patients who failed prior surgery was 91 (range, 84 to 100). The average postoperative Lysholm knee score was 97 (range, 87 to 100). Only two patients had mild knee pain. Postoperative radiographs were available for 13 patients. There was no evidence of graft subsidence and all grafts healed. All malleolar osteotomies united. Seventeen (89%) patients said that they would undergo the procedure again. The results of osteochondral autograft transplant for OCD lesions of the talus demonstrate excellent postoperative ankle scores including improvement of pain and function with minimal knee donor site morbidity. Also, our results indicate that this is an effective salvage procedure following failed previous procedures and for patients with longstanding symptoms.     

No mid-term difference in mosaicplasty in previously treated versus previously untreated patients with osteochondral lesions of the talus

Introduction Osteochondral transplantations, albeit technically challenging, appear promising not only in knee joint lesions, but also in the treatment of talus lesions. We hypothesized that in patients suffering osteochondral lesions of the talus, favorable outcomes are obtained in patients undergoing primary mosaicplasty as compared to patients undergoing secondary mosaicplasty. Materials and methods Over a 3-year period (1998–2001), 14 patients (six male, eight female, median age 22 years) were treated with an autologous osteochondral transplantation of the talus. Eight patients were previously untreated (group I). Six patients had previous ankle procedures, such as microfracturing (group II). The median follow-up was 24 months and 100% complete at 12 months. The functional outcome was evaluated at least at 6 weeks, 12 weeks, and 1 year after surgery using pain on a visual analog scale (VAS) and sports activity was recorded at 1 year after surgery. In ten patients, magnetic resonance imaging (MRI) of the ankle was performed at 1 year after surgery (group I/II: 7/3). Results Overall ankle pain was decreased from 6.9 ± 2.1 to 4.0 ± 2.8 postoperatively. The mean knee pain for the donor knee was 2.6 ± 2.4. We found no significant difference between the primary mosaicplasty group and the secondary mosaicplasty group with regard to pain. MRI scans of ten patients showed a complete incorporation of the osteochondral cylinders at 1 year after surgery. Conclusion Favorable outcomes were obtained in patients undergoing primary mosaicplasty as compared to patients undergoing secondary mosaicplasty. We found no significant difference among patients with previous ankle surgery in contrast to those without, with a median 24-months follow-up.     

Autologous chondrocyte transplantation for treating cartilage defects of the talus

BACKGROUND: Despite its highly specialized nature, articular cartilage has a poor reparative capability. Treatment of symptomatic osteochondral defects of the talus has been especially difficult until now. METHODS: We performed autologous chondrocyte transplantation in twelve patients with a focal deep cartilage lesion of the talus. There were seven female and five male patients with a mean age of 29.7 years. The mean size of the lesion was 2.3 cm(2). All patients were studied prospectively. Evaluation was performed with use of the Hannover ankle rating score, the American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, a visual analogue scale for pain, and magnetic resonance imaging. RESULTS: All patients were available for follow-up at a mean of sixty-three months. There was a significant improvement in the Hannover score, from 40.4 points preoperatively to 85.5 points at the follow-up examination, with seven excellent results, four good results, and one satisfactory result. The AOFAS mean score was 88.4 points compared with 43.5 points preoperatively. Magnetic resonance imaging showed a nearly congruent joint surface in seven patients, discrete irregularities in four, and an incongruent surface in one. The patients who had been involved in competitive sports were able to return to their full activity level. CONCLUSIONS: The promising clinical results of this study suggest that autologous chondrocyte transplantation is an effective and safe way to treat symptomatic osteochondral defects of the talus in appropriately selected patients.     

Osteochondral autografts for osteochondritis dissecans of the talus

Eighteen symptomatic advanced-stage osteochondritis dissecans (OCD) of the talus (Berndt and Harty stages III 7 and IV 11) in 17 patients were treated with multiple autogenous osteochondral cylindrical grafts. The mean time of follow-up was 36 months (range, 25-49). The average age at surgery was 22.7 years (range, 19-34). The mean size of defect of OCD was 13.6 mm x 7.2 mm. Two or three osteochondral grafts (6 or 7 mm in diameter and 15-20 mm in length) were harvested from the superomedial margin of the ipsilateral knee. A partial osteotomy of the medial malleolus or osteotomy of the distal lateral tibia was performed for all cases. Being evaluated by the Freiburg ankle score, 16 of 18 ankles (88.8%) had excellent and two (11.8%) had good results. "Second-look" arthroscopy of 16 ankles revealed consistency of the osteochondral grafts and congruity between grafts and native cartilage in 14 (87.5%), and a softening or fissuring of the osteochondral graft in two. Our results showed that this procedure provided an effective treatment for a symptomatic advanced-stage OCD of the talus.     

Cartilage repair of the talus

The cause of a typical osteochondral lesion of the talus is traumatic; if symptomatic, several options exist. Because nonoperative treatment results in no more than 50% good to excellent results, the following types of surgery are in clinical use: (1) debridement and drilling, (2) osteochondral transfer, and (3) autologous chondrocyte transplantation. Reported good to excellent results are at least 80% in the short term. Currently available data allow no recommendation of a specific therapy for a specific lesion. Advocates of drilling and debridement accept that the repair tissue is fibrocartilage; osteochondral transfer includes a donor side morbidity. We are still at the beginning of cartilage repair; it will take time before a certain type of lesion can be treated with the best modality because that requires comparative randomized prospective studies with a long follow-up. All modern cartilage repair techniques, that were initially investigated at the knee joint, are now in use for ankle osteochondral lesions. Reported short-term success rates are greater than 80%. Further improvements will depend on the understanding of the pathogenesis and the role of contributing factors (eg, instability).     

Bony Lesion Recurrence After Mosaicplasty for Osteochondritis Dissecans of the Talus

Autogenous osteochondral grafts have recently become popular for use in small, isolated, contained articular cartilage defects. We treated a 26-year-old man who had a cartilage defect measuring 10 × 20 mm in the anteromedial area of the right talus. We performed multiple osteochondral grafting of the lesion with medial malleolar osteotomy from a donor site in the ipsilateral knee joint. Two years after the operation, the patient’s ankle pain recurred and the bony lesion in the talus also became osteolytic. Because we believed that only the cartilaginous portions of the osteochondral plugs grafted 2 years previously were fully fixed and viable, and that recurrence had occurred at the bony portions, at reoperation we performed curettage of the bony lesions and grafted iliac bone into the lesions with fenestration of the inferomedial ankle joint cartilage, not grafted plug cartilage. Therefore, probably because of overuse, the bony lesion in the talus had recurred 2 years after the first operation, but the grafted hyaline cartilage had survived. Autogenous osteochondral grafting into the talus, unlike the knee joint, should be done with care to ensure there is no sclerotic bone surrounding the lesion in patients with long-standing symptoms and recurrence of bony lesions.     

Early results of autologous chondrocyte implantation in the talus

Autologous chondrocyte implantation (ACI) has been used most commonly as a treatment for cartilage defects in the knee and there are few studies of its use in other joints. We describe ten patients with an osteochondral lesion of the talus who underwent ACI using cartilage taken from the knee and were prospectively reviewed with a mean follow-up of 23 months. In nine patients the satisfaction score was 'pleased' or 'extremely pleased', which was sustained at four years. The mean Mazur ankle score increased by 23 points at a mean follow-up of 23 months. The Lysholm knee score returned to the pre-operative level at one year in three patients, with the remaining seven showing a reduction of 15% at 12 months, suggesting donor-site morbidity. Nine patients underwent arthroscopic examination at one year and all were shown to have filled defects and stable cartilage. Biopsies taken from graft sites showed mostly fibrocartilage with some hyaline cartilage. The short-term results of ACI for osteochondral lesions of the talus are good despite some morbidity at the donor site.     

不同方法治疗踝部骨折伴随的距骨骨软骨骨折临床效果对比研究

目的 对比研究自体骨软骨移植术和骨软骨折块摘除钻孔术治疗踝部骨折伴随的急性Ⅲ、Ⅳ型距骨骨软骨骨折的临床效果.方法 2002年5月至2007年8月,38例踝部骨折伴随的急性Ⅲ、Ⅳ型距骨骨软骨骨折,术中明确距骨骨软骨骨折的部位以及范围.20例折块摘除后,自同侧膝关节非负重区钻取骨软骨柱,采取打压固定技术将骨软骨柱植入受区的孔中,为移植组;18例骨软骨折块摘除后行钻孔术为钻孔组.对比观察研究两组患者踝关节的功能、X线以及MRI表现.结果 移植组随访1.5～4.0年,平均(2.92±0.65)年,钻孔组随访2.5～5.0年,平均(3.02±0.83)年.7例行多柱移植,13例行单柱移植.根据Baird和Jackson踝关节评分系统进行功能评分:移植组平均(89.85±4.83)分,钻孔组平均(84.28±5.65)分,两组比较差异有统计学意义(t=3.277.P=0.002);X线片示移植组3例踝关节发生创伤性关节炎,发生率为15.0%(3/20),钻孔组8例踝关节发生创伤性关节炎,发生率为44.4%(8/18),两组比较差异有统计学意义(χ2=31.7,P<0.05);MRI显示移植组3例骨软骨柱松动吸收,发生距骨剥脱性骨软骨炎,占15.0%(3/20),其余修复的关节面平滑,骨软骨柱与周围组织结合良好;钻孔组6例发生距骨剥脱性骨软骨炎,发生率为33.3%(6/18),两组比较差异有统计学意义(χ2=39.6,P<0.05);两组膝关节均无远期供区并发症.结论 自体骨软骨移植治疗踝部骨折伴随的急性Ⅲ、Ⅳ型距骨骨软骨骨折是一种有效的手术方法 ,降低了踝关节创伤性关节炎和距骨剥脱性骨软骨炎的发生率,提高了踝关节的功能.     

Osteochondral transplantation for the treatment of osteochondral defects at the talus with the Diamond twin system® and graft harvesting from the posterior femoral condyles

Background

The aim of this study is to analyze clinical results after osteochondral cylinder transplantation for osteochondral defects at the medial or lateral talar dome using the Diamond twin system (Karl Storz). We hypothesize that grafts harvesting from the posterior femoral condyles are associated with less donor site morbidity than reported by previous studies.

Methods

We have surgically treated 20 patients with an osteochondral defect of the talus by osteochondral transplantation with the Diamond twin system via an osteotomy of the ankle. The osteochondral cylinders were harvested from the posterior aspects of the femoral condyles of the ipsilateral knee. The defects at donor site were filled with a bone substitute of tricalcium phosphate (Synthricer, Karl Storz). The mean age was 25.4 years. After a mean time of 12.6 months, the screws at the medial malleolus were removed and an arthroscopy was performed. The functional outcome was evaluated with the visual analog scale for pain at walking, running, stair climbing, quality of life at the time of implant removal and at a mean follow-up of 25.8 months. Activity was assessed with the Tegner scale. Knee function was evaluated with the Lysholm score.

Results

In one case, the osteochondral cylinder did not heal and an osteochondral fragment was removed arthroscopically. In all other cases, the osteochondral cylinder was stable with surrounding cartilage. The average ICRS Cartilage Repair Assessment was 10.1 points (±1.3). All malleolar osteotomies healed radiologically. In 15 patients, a synovectomy and local debridement of the ankle were performed at second-look arthroscopy. Ankle pain at walking, running and stair climbing as measured by a visual analog scale (10-0) decreased significantly from preoperatively to the first follow-up (mean 12.6 months) and to the second follow-up (mean 25.8 months). The ankle-related quality of life increased significantly from preoperatively to postoperatively. There was no significant change in the Lysholm score. The activity measured with the Tegner activity scale increased significantly from preoperatively to the last follow-up, but only two out of nine patients continued pivoting sports.

Conclusions

Autologous osteochondral grafting with the Diamond twin system is a reliable treatment option for symptomatic osteochondral defects of the talus. After 1 year, the majority of patients had still some complaints. However, after screw removal and second-look arthroscopy, the pain and ankle-related quality of life further improved.

Clinical relevance

The donor site morbidity after graft harvesting from the posterior aspects of the femoral condyles is lower than previously reported.     

Fresh osteochondral grafting in the treatment of osteochondritis dissecans of the talus

We present a review of the literature on classification and treatment of osteochondral defects of the talus. We report the case of an isolated Berndt and Harty grade II lesion treated with a fresh osteochondral allograft. We believe that fresh allograft osteochondral grafting of the talus is an excellent technique for symptomatic Berndt and Harty grade II or higher lesion of the talus without significant tibiotalar arthritis. In selected patients, this procedure can provide excellent functional results.     

Mosaicplasty for the treatment of osteochondritis dissecans of the talus: two to seven year results in 36 patients

An osteochondral defect (OCD) is known as a symptomatic lesion causing pain, recurrent synovitis, and altered joint mechanics most commonly in a weight-bearing joint. Loose bodies may develop, which may then cause joint destruction and/or locking. The damage to the articular surface is most likely a precursor of ankle osteoarthritis. With the recent advances in diagnostic imaging, such as MRI, as well as the development of ankle arthroscopy, the identification and classification of these lesions has become much more precise. This allows more accurate staging and improves treatment recommendations. The assessment of a particular treatment is also improved. A variety of treatment alternatives are now available. These include arthroscopic procedures including debridement, retrograde drilling, and bone grafting. Compared to open treatment, arthroscopic procedures may be particularly advantageous in the treatment of small defects and stable OCD lesions. Until recently, however, favorable results have been less predictable for large or unstable osteochondral defects. We treat these more difficult lesions with a mosaic autogenous osteochondral transplantation. In our hands, this appears to provide an optimal treatment result. The present report evaluates the clinical outcome of 36 patients followed for two to seven years after a mosaicplasty autogenous osteochondral transplantation from a non or less weight bearing portion of the knee to the ipsilateral talus. Ankle function was measured by the Hannover scoring system and showed good to excellent results in 34 cases (94%) with no long term donor site morbidity. The encouraging clinical results are supplemented with radiographs and histology, which support the premise of lasting relief of symptoms and prevention of ankle arthrosis.     

Osteochondritis Dissecans of the Lateral Process of Talus Involving the Subtalar Joint: An Unusual Case

Osteochondritis dissecans is a fairly recognized entity affecting the talus dome but subtalar joint involvement is not that common. We report a case of a 34-year-old male with osteochondritis dissecans of lateral process talus which was missed on imaging studies and identified intraoperatively. The patient was treated with curettage of the subchondral cyst at talus, followed by bone grafting and fixation of the osteochondral lesion with a 4-mm partially threaded cancellous screw. At the 1-year follow-up evaluation, there were no signs of recurrence and the patient resumed his complete activities including sports. We believe that the threshold for diagnosing these lesions should be low in cases with nonspecific chronic ankle pain, and surgeons are encouraged to consider this diagnosis.     

Delayed presentation of a loose body in undisplaced paediatric talar neck fracture

Fractures of the talus are rare in children. A high index of suspicion is needed to avoid missing such an injury, which is not an uncommon occurrence especially with undisplaced fractures. We present an unusual case of an undisplaced talar neck fracture in a five-year-old child leading to a delayed presentation of a symptomatic osteochondral loose body in the ankle joint. To our knowledge there are no reports in the literature of osteochondral loose bodies occurring in conjunction with an associated undisplaced talar neck fracture in either children or adults. The loose body was removed using anterior ankle arthroscopy. The child had an uneventful post operative recovery and regained full range of movement and function of his ankle joint and was discharged at one year follow-up. We aim to highlight the need to have a low threshold to further evaluate symptomatic children after fracture healing of an undisplaced talar neck fracture for a possible associated loose body in the ankle joint.     

Arthroscopic treatment of osteochondral lesions of the distal tibia

BACKGROUND: Osteochondral lesions of the tibia are much less frequent than those of the talus, and treatment guidelines have not been established. We hypothesized that arthroscopic treatment methods used for osteochondral lesion of the talus would also be effective for those of the distal tibia. METHODS: A review of 880 consecutive ankle arthroscopies identified 23 patients (2.6%) with osteochondral lesions of the distal tibia. Four patients were excluded because of concomitant acute ankle fractures requiring open reduction and internal fixation and two were lost to followup, leaving 17 in the study. The mean age was 38 (19 to 71) years. Six (35%) had osteochondral lesions of the tibia and talus; 11 had isolated lesions of the distal tibia. Treatment included excision, curettage, and abrasion arthroplasty in all patients. Five patients had transmalleolar drilling of the lesion, two had microfracture, and two had iliac bone grafting. At last followup, patients were evaluated with a questionnaire, physical examination, and ankle radiographs. RESULTS: Mean followup was 44 (24 to 99) months. Preoperatively, the median American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot score was 52; postoperatively, it was 87. Using the Wilcoxon signed-rank test to compare preoperative and postoperative scores, there was significant improvement in the ankle-hindfoot score postoperatively (p < 0.001). Seven patients had excellent results, seven had good results, one had a fair result, and two had poor results. CONCLUSIONS: Osteochondral lesions of the distal tibia present a challenge to the orthopedic surgeon. Arthroscopic treatment by means of debridement, curettage, abrasion arthroplasty, and, in some patients, transmalleolar drilling, microfracture, or iliac crest bone grafting, resulted in excellent and good results in 14 of 17 patients at medium-term followup.     

The detached osteochondral fragment as a source of cells for autologous chondrocyte implantation (ACI) in the ankle joint

OBJECTIVE: Autologous chondrocyte implantation (ACI) has been successfully used for the treatment of osteochondral lesions of the talus. One of the main problems of this surgical strategy is related to the harvesting of the cartilage slice from a healthy knee. The aim of this study was to examine the capacity of chondrocytes harvested from a detached osteochondral fragment to proliferate and to serve as a source of viable cells for ACI in the repair of ankle cartilage defects. METHODS: Detached osteochondral fragments harvested from the ankle joint of 20 patients with osteochondral lesions of the talus served as the source of human articular cartilage specimens. All of the osteochondral lesions were chronic and of traumatic origin. In all cases, the fragments were utilized to evaluate the viability and proliferation of the cells, the histological appearance of the cartilage tissue and the expression of specific cartilage markers by real-time polymerase chain reaction (PCR). In the 16 patients scheduled for ACI, the expanded chondrocytes were used for chondrocyte implantation. In the other 4 patients, with lesion size <1.5cm(2), microfractures were created during the initial arthroscopic step. As a control group, 7 patients with comparable osteochondral lesions underwent the same surgery, but received chondrocytes harvested from the ipsilateral knee. RESULTS: According to the American Orthopaedic Foot and Ankle Scoring (AOFAS) system, patients in the experimental group had a preoperative score of 54.2+/-16 points and a postoperative one of 89+/-9.6 points after a minimum follow-up time of 12 months (P<0.0005). The control group of patients had a preoperative score of 54.6+/-11.7 points and a postoperative one of 90.2+/-9.7 points at a minimum follow-up time of 12 months (P<0.0005). The clinical results of the two groups did not differ significantly from each other. Chondrocytes isolated from the detached fragments were highly viable, phenotypically stable, proliferated in culture and redifferentiated when grown within the three-dimensional scaffold used for ACI. The morphological and molecular characteristics of the cartilage samples obtained from the detached osteochondral fragments were similar to those of healthy hyaline articular cartilage. CONCLUSIONS: The good results achieved with this strategy indicate that cells derived from the lesioned area may be useful in the treatment of osteochondral defects of the talus.     

Editorial Commentary: Osteochondral Lesions of the Talus: All,Nothing, or Something in Between

Osteochondral lesions of the talus occur with relatively frequency, often as the sequelae of benign ankle sprains, and are only surpassed by the knee and elbow as more common locations. While microfracture of the talus is the most common first-line surgical treatment performed at the time of ankle arthroscopy, marrow stimulation alone results in fibrocartilaginous repair tissue rather than true hyaline-like articular cartilage. In addition, the benefits of bone marrow stimulation for the treatment of large (>150 mm²), deep (>7 mm), or cystic lesions is limited. Autologous osteochondral transplant has emerged as one such treatment option for large lesions that may address underlying bone loss and reconstitute articular cartilage. The utility of autologous osteochondral transplant also must be interpreted with an understanding of the potential complications, including donor-site morbidity. In addition, it is important to decompress, curettage, and back fill associated cysts with bone graft. When cysts are not treated aggressively, patients may have ongoing bone marrow edema and pain.     

Treatment of osteochondritis dissecans of the femoral condyle with autologous bone grafts and matrix-supported autologous chondrocytes

The objective of this study was to determine the clinical outcome of combined bone grafting and matrix-supported autologous chondrocyte transplantation in patients with osteochondritis dissecans of the knee. Between January 2003 and March 2005, 21 patients (mean age 29.33 years) with symptomatic osteochondritis dissecans (OCD) of the medial or lateral condyle (grade III or IV) of the knee underwent reconstruction of the joint surface by autologous bone grafts and matrix-supported autologous chondrocyte transplantation. Patients were followed up at three, six, 12 and 36 months to determine outcomes by clinical evaluation based on Lysholm score, IKDC and ICRS score. Clinical results showed a significant improvement of Lysholm-score and IKDC score. With respect to clinical assessment, 18 of 21 patients showed good or excellent results 36 months postoperatively. Our study suggests that treatment of OCD with autologous bone grafts and matrix-supported autologous chondrocytes is a possible alternative to osteochondral cylinder transfer or conventional ACT.     

Retrograde osteochondral grafting for osteochondral lesion of the talus: a new technique eliminating malleolar osteotomy

Osteochondral grafting is one of the most effective treatment options for osteochondral lesions of the talus. However, the necessity for a medial malleolar osteotomy is the major drawback of the technique. This report presents a case treated with retrograde osteochondral grafting that eliminated the need for a medial malleolar osteotomy. An osteochondral lesion of the medial talus was detected in a 49-year-old woman. Under arthroscopic guidance, the talus was entered from the sinus tarsi region to establish a tunnel extending to the lesion. An osteochondral graft taken from the ipsilateral knee was inserted into the distal end of the tunnel and was advanced to the joint surface. Postoperative computed tomography scans showed that the graft completely filled the tunnel and provided congruency with the articular surface. Details of this technique are described.     

Arthroscopic Bone Grafting of Talar Bone Cyst Using Posterior Ankle Arthroscopy

A subchondral cyst of the talus frequently occurs with an osteochondral lesion of the talar dome. Debridement, curettage, and bone grafting through the articular defect was frequently the recommended treatment in reported studies for a massive cyst. We report a case of a massive cyst of the talar body with a small osteochondral lesion of the talar dome. Our patient was successfully treated by curettage and bone grafting of the cyst using posterior ankle arthroscopy, with minimal disruption of the articular surface of the talar dome.