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1.  Tertiary osteochondral defect of the talus treated by a novel contoured metal implant 
The primary treatment of most osteochondral defects of the talus is arthroscopic debridement and bone marrow stimulation. There is no optimal treatment for large lesions or for those in which primary treatment has failed. We report a 20-year-old female patient with persistent symptoms after two previous arthroscopic procedures. Computed tomography showed a cystic defect of the medial talar dome, sized 17 × 8 × 8 mm. The patient was treated with a novel contoured metal implant. At 1 and 2 years after surgery, the patient reported considerable reduction in pain and had resumed playing korfball at competitive level.
Level of evidence IV.
doi:10.1007/s00167-011-1465-5
PMCID: PMC3096766  PMID: 21409468
Osteochondral lesions; Bone cyst; Talus; Ankle; Metal implant; Treatment
2.  Direction of the oblique medial malleolar osteotomy for exposure of the talus 
Introduction
A medial malleolar osteotomy is often indicated for operative exposure of posteromedial osteochondral defects and fractures of the talus. To obtain a congruent joint surface after refixation, the oblique osteotomy should be directed perpendicularly to the articular surface of the tibia at the intersection between the tibial plafond and medial malleolus. The purpose of this study was to determine this perpendicular direction in relation to the longitudinal tibial axis for use during surgery.
Materials and methods
Using anteroposterior mortise radiographs and coronal computed tomography (CT) scans of 46 ankles (45 patients) with an osteochondral lesion of the talus, two observers independently measured the intersection angle between the tibial plafond and medial malleolus. The bisector of this angle indicated the osteotomy perpendicular to the tibial articular surface. This osteotomy was measured relative to the longitudinal tibial axis on radiographs. Intraclass correlation coefficients (ICC) were calculated to assess reliability.
Results
The mean osteotomy was 57.2 ± 3.2° relative to the tibial plafond on radiographs and 56.5 ± 2.8 on CT scans. This osteotomy corresponded to 30.4 ± 3.7° relative to the longitudinal tibial axis. The intraobserver (ICC, 0.90–0.93) and interobserver (ICC, 0.65–0.91) reliability of these measurements were good to excellent.
Conclusion
A medial malleolar osteotomy directed at a mean 30° relative to the tibial axis enters the joint perpendicularly to the tibial cartilage, and will likely result in a congruent joint surface after reduction.
doi:10.1007/s00402-010-1227-8
PMCID: PMC3117279  PMID: 21165631
Medial malleolus; Osteotomy; Ankle; Radiography; Preoperative planning; Surgical approach
3.  Novel metallic implantation technique for osteochondral defects of the medial talar dome 
Acta Orthopaedica  2010;81(4):495-502.
Background and purpose
A metallic inlay implant (HemiCAP) with 15 offset sizes has been developed for the treatment of localized osteochondral defects of the medial talar dome. The aim of this study was to test the following hypotheses: (1) a matching offset size is available for each talus, (2) the prosthetic device can be reproducibly implanted slightly recessed in relation to the talar cartilage level, and (3) with this implantation level, excessive contact pressures on the opposite tibial cartilage are avoided.
Methods
The prosthetic device was implanted in 11 intact fresh-frozen human cadaver ankles, aiming its surface 0.5 mm below cartilage level. The implantation level was measured at 4 margins of each implant. Intraarticular contact pressures were measured before and after implantation, with compressive forces of 1,000–2,000 N and the ankle joint in plantigrade position, 10° dorsiflexion, and 14° plantar flexion.
Results
There was a matching offset size available for each specimen. The mean implantation level was 0.45 (SD 0.18) mm below the cartilage surface. The defect area accounted for a median of 3% (0.02–18) of the total ankle contact pressure before implantation. This was reduced to 0.1% (0.02–13) after prosthetic implantation.
Interpretation
These results suggest that the implant can be applied clinically in a safe way, with appropriate offset sizes for various talar domes and without excessive pressure on the opposite cartilage.
doi:10.3109/17453674.2010.492764
PMCID: PMC2917574  PMID: 20515434
4.  Osteochondral defects in the ankle: why painful? 
Osteochondral defects of the ankle can either heal and remain asymptomatic or progress to deep ankle pain on weight bearing and formation of subchondral bone cysts. The development of a symptomatic OD depends on various factors, including the damage and insufficient repair of the subchondral bone plate. The ankle joint has a high congruency. During loading, compressed cartilage forces its water into the microfractured subchondral bone, leading to a localized high increased flow and pressure of fluid in the subchondral bone. This will result in local osteolysis and can explain the slow development of a subchondral cyst. The pain does not arise from the cartilage lesion, but is most probably caused by repetitive high fluid pressure during walking, which results in stimulation of the highly innervated subchondral bone underneath the cartilage defect. Understanding the natural history of osteochondral defects could lead to the development of strategies for preventing progressive joint damage.
doi:10.1007/s00167-010-1064-x
PMCID: PMC2855020  PMID: 20151110
Osteochondral defect; Cartilage; Ankle joint; Subchondral cyst; Natural history; Pain

Results 1-4 (4)