Background: Fresh osteochondral allograft (OCA) transplantation represents a biologic restoration technique as an alternative treatment option for larger osteochondral lesions of the talus (OLT). The purpose of this study was to evaluate midterm outcomes after OCA transplantation for the treatment of OLT. Methods: Nineteen patients (20 ankles) received partial unipolar OCA transplant for symptomatic OLT between January 1998 and October 2014. The mean age was 34.7 years, and 53% were male. The average graft size was 3.8 cm2. All patients had a minimum follow-up of 2 years. Outcomes included the American Academy of Orthopaedic Surgeons Foot and Ankle Module (AAOS-FAM), the Olerud-Molander Ankle Score (OMAS), and pain and satisfaction questionnaires. Failure of OCA was defined as conversion to arthrodesis or revision OCA transplantation. Results: Five of 20 ankles (25%) required further surgery, of which 3 (5%) were considered OCA failures (2 arthrodesis and 1 OCA revision). The mean time to failure was 3.5 (range, 0.9 to 6.7) years. Survivorship was 88.7% at 5 years and 81.3% at 10 years. The median follow-up of the 17 patients with grafts in situ was 9.7 years. The mean OMAS improved significantly from 40 points preoperatively to 71 points postoperatively (P < .05; range, 5 to 55). The mean postoperative AAOS-FAM core score was 81.5 ± 15 (range, 40.5 to 96.6). Fifteen of 17 patients responded to follow-up questions regarding their ankle; 14 patients reported less pain and better function, and 13 patients were satisfied with the results of the procedure. Conclusion: Our study of midterm results after OCA transplantations showed that this procedure was a reasonable treatment option for large OLT. Level of Evidence: Level IV, case series.

The structure of the ankle joint complex creates an ideal balance between mobility and stability, which enables gait. If a lesion emerges in the ankle joint complex, the anatomical structure is altered, which may disturb mobility and stability and cause intense pain. A lesion in the articular cartilage on the talus bone, or a lesion in the subchondral bone of the talar dome, is referred to as an Osteochondral Lesion of the Talus (OLT). Replacing the damaged cartilage or bone with an implant is one of the methods that can be applied to treat OLTs. Episurf Medical develops and produces patient-specific implants (Episealers) along with the necessary associated surgical instruments by, inter alia, creating a corresponding 3D model of the ankle (talus, tibial, and fibula bones) based on either a Magnetic Resonance Imaging (MRI) scan or a Computed Tomography (CT) scan. Presently, the3D models based on MRI scans can be created automatically, but the 3Dmodels based on CT scans must be created manually, which can be very time-demanding. In this thesis project, a U-net based Convolutional Neural Network (CNN) was trained to automatically segment 3D models of ankles based on CT images. Furthermore, in order to optimize the quality of the incoming CT images, this thesis project also consisted of an evaluation of the specified parameters in the Episurf CT talus protocol that is being sent out to the clinics. The performance of the CNN was evaluated using the Dice Coefficient (DC) with five-fold cross-validation. The CNN achieved a mean DC of 0.978±0.009 for the talus bone, 0.779±0.174 for the tibial bone, and 0.938±0.091 for the fibula bone. The values for the talus and fibula bones were satisfactory and comparable to results presented in previous researches; however, due to background artefacts in the images, the DC achieved by the network for the segmentation of the tibial bone was lower than the results presented in previous researches. To correct this, a noise-reducing filter will be implemented. / Fotledens komplexa anatomi ger upphov till en ideal balans mellan rörlighetoch stabilitet, vilket i sin tur möjliggör gång. Fotledens anatomi förändras när en skada uppstår, vilket kan påverka rörligheten och stabiliteten samt orsaka intensiv smärta. En skada i talusbenets ledbrosk eller i det subkondrala benet på talusdomen benämns som en Osteochondral Lesion of the Talus(OLT). En metod att behandla OLTs är att ersätta den del brosk eller bensom är skadat med ett implantat. Episurf Medical utvecklar och producerar individanpassade implantat (Episealers) och tillhörande nödvändiga kirurgiska instrument genom att, bland annat, skapa en motsvarande 3D-modell av fotleden (talus-, tibia- och fibula-benen) baserat på en skanning med antingen magnetisk resonanstomografi (MRI) eller datortomografi (CT). I dagsläget kan de 3D-modeller som baseras på MRI-skanningar skapas automatiskt, medan de 3D-modeller som baseras på CT-skanningar måste skapas manuellt - det senare ofta tidskrävande. I detta examensarbete har ett U-net-baserat Convolutional Neuralt Nätverk (CNN) tränats för att automatiskt kunna segmentera 3D-modeller av fotleder baserat på CT-bilder. Vidare har de speciferade parametrarna i Episurfs CT-protokoll för fotleden som skickas ut till klinikerna utvärderats, detta för att optimera bildkvaliteten på de CT-bilder som används för implantatspositionering och design. Det tränade nätverkets prestanda utvärderades med hjälp av Dicekoefficienten (DC) med en fem-delad korsvalidering. Nätverket åstadkom engenomsnittlig DC på 0.978±0.009 för talusbenet, 0.779±0.174 för tibiabenet, och 0.938±0.091 för fibulabenet. Värdena för talus och fibula var adekvata och jämförbara med resultaten presenterade i tidigare forskning. På grund av bakgrundsartefakter i bilderna blev den DC som nätverket åstadkom för sin segmentering av tibiabenet lägre än tidigiare forskningsresultat. För att korrigera för bakgrundsartefakterna kommer ett brusreduceringsfilter implementeras