Volumetric 3D Reconstruction of Large Osteochondral Lesions of the Talus Being Reconstructed with Viable Osteochondral Allograft Combined with Autograft

Submission Type: Other Research Type: Level 3 - Retrospective cohort study, Case-control study, Meta-analysis of Level 3 studies Introduction/Purpose: Symptomatic osteochondral lesions of the talus (OLT) are challenging to treat. Articular Regional Reconstruction (ARR) is a novel technique combining viable osteochondral allograft with morselized autograft bone to address large, volumetric OLT lesions. OLT’s involve a wide spectrum of presentations varying in surface and bony defect involvement, so improving OLT characterization will be important to selecting appropriate surgical reconstruction techniques. OLTs are often described based on maximal linear dimension and localized based on talar surface zones. Methods approximating lesion size based on simple geometric shapes such as prisms, ellipsoids, or cylinders may oversimplify OLTs. We describe a consecutive series of patients undergoing ARR with accurate lesion volumes calculated via slice-by-slice tracing and 3D reconstruction. Methods: Patients indicated for the ARR procedure from a single surgeon were identified. OLT volume was determined for all patients with a preoperative weight bearing CT. Lesions were traced in consecutive CT slices in both sagittal and coronal views. Volume is reported as an average of the two views. Surgically, the OLTs were initially inspected arthroscopically then converted to open debridement. Medial malleolar osteotomies were utilized for access as necessary. A stable bony base and viable cartilage rim was established, removing all damaged cartilage and nonstructural bone debris from the OLT. Talar body structure and morphology was restored using autograft iliac crest or tibial placed into the bony defect. Viable osteochondral allograft (Cartiform®) was shaped and then secured over the autograft using suture anchors placed at the lesion periphery. Patient Reported Outcome (PRO) measures included PROMIS-physical function (PROMIS-PF), PROMIS-pain interference (PROMIS-PI), and single assessment numeric evaluation (SANE). Results: Sixteen patients with an average age of 34.2 (± 13.9 years) received ARR. Ten patients underwent medial malleolar osteotomy at time of surgery. To date, only one (6.3%) patient required revision OLT treatment, and the lesion had shrunk - amenable to all-arthroscopic intervention. Five others have undergone hardware removals allowing for ‘second looks’ of the revision, all demonstrating incorporation of the graft without delamination. Eight patients with preoperative and postoperative PROMIS-PF improved from 41.5 to 46.0 (p = 0.088), PROMIS- PI improved from 59.5 to 55.6 (p = 0.112), and SANE improved from 51 to 71.5 (p = 0.023). The average lesion was 0.464 cm2. Average coronal volume was smaller than average sagittal volume by 0.043cm2, but these differences were not significant (p = 0.124). Conclusion: Articular Regional Reconstruction (ARR) is a reproducible procedure with demonstrated potential for improvement in pain and physical function among patients with symptomatic, large volumetric osteochondral lesions of the talus, whether ‘contained’ or ‘uncontained’. Slice-by-slice tracing of OLTs can accurately determine lesion volume, particularly when lesions are non-uniform and cannot be approximated using uniform geometric shapes. Current work is being done to compare volume approximations with accurately traced volumes, and to assess associations between volume, preoperative and postoperative measures. Further studies on ARR of the talus are necessary to elucidate proper indications and strengthen long-term outcome data.