TissueDB/Simulators/Lower Limb Deformity Correction Simulator

The Lower Limb Deformity Correction Simulator (OpenSurgiSim) is an adult, 3D-printed training system for lower-limb bone deformity correction using external rail fixation, built for junior and trainee orthopaedic surgeons in low- and middle-income countries where expert trainers, cadavers and specialised mock bones are scarce.^[2] A modular kit of 3D-printed bone parts assembles into 10 real-patient deformity cases (each printable twice); the trainee mounts the assembled bone on printed holders under a webcam and uses their own clinical tools — a drill, a hacksaw and an external rail (LRS) fixator — to drill the fixator-pin holes, cut the osteotomy and apply the fixator. The OpenSurgiSim cloud software (opensurgisim.com) tracks augmented-reality markers on the bone through the webcam and returns real-time guidance and an automatic self-assessment score (cut error and pin position and angle). The webcam, lighting and clinical instruments are ordered off-the-shelf or are the surgeon's own.

Open the developer's file folders for the required printing route: Alternative 1 — STL parts that need paper markers, Alternative 2 — OBJ parts with colour-marker textures, STL parts without marker holders, and other STL parts and tools. For Alternative 1, the individual marker-holder STL files are FA.stl, FC.stl, TB.stl, TD.stl; use the paper-marker PDF with that route. The parts without marker holders are FB.stl, FB-3.stl, FB-7.stl, FB-10.stl, FD.stl, FD-4.stl, FD-8.stl, TA.stl, TA-2.stl, TA-6.stl, TC.stl, TC-1.stl, TC-5.stl, TC-9.stl. Alternative 2 contains FA.obj, FC.obj, TB.obj and TD.obj. Keep each OBJ with its same-name MTL file and supplied PNG texture: FA and TB use pattern 1 (PNG); FC and TD use pattern 2 (PNG). Keep the selected parts, file format and marker method together; the four holder/tool STL links are at the start of Phase 3.

1. Download the required modular bone parts from the labelled folders above. Alternative 1 supplies STL parts with marker holders. Alternative 2 supplies OBJ parts with their MTL material files and marker textures; keep those companion files together. The other folders supply parts without marker holders, bone holders, the independent marker holder and the cut-error tool.
2. Send the selected model files to a 3D printing service. Specify: 2–3 mm wall thickness; hollow interior for bone parts with marker holders and other parts, lattice interior for bone parts without marker holders. Alternative 1 includes 3D Systems SLS printer specifications and requires separate paper markers. Alternative 2 includes HP colour-printer specifications and textured OBJ files with integrated colour markers; its folder is labelled "No Paper Marker Needed". Confirm the required printing process and material with the source and provider.

1. Verify all printed parts by their embedded labels: FA, FB, FC, FD for femur parts; TA, TB, TC, TD for tibia parts. Each label has numbered variants (e.g., TC-1, TC-5, TC-9) for different deformity cases.

1. Review the 10 case assembly combinations. Each case uses a specific set of four modular parts. For example, Case 1 (Uniapical Tibial Shaft Frontal) assembles TA + TB + TC-1 + TD. Each case can be practiced twice using duplicate variant parts.

1. If using Alternative 1 for marker-holder parts: download the Markers PDF file. Print on A4 white sticker paper at actual size (100% scale). Each sheet contains Marker-1 (proximal bone), Marker-2 (distal bone), and Marker-3 (independent holder) with backup copies.

1. Cut out square markers along their edges (3.5 cm × 3.5 cm). Paste Marker-1 on parts TB and FA. Paste Marker-2 on parts TD and FC. Paste Marker-3 on both sides of the independent marker holder. Align each marker with the notch on its marker holder (notch indicates the UP direction).

Assembly video: Marker cutting and placement.

1. Prepare a white workspace area (40 × 30 cm) on the table surface. Paste two A4 sheets side by side using tape to create a white background. Position the workspace in front of the trainee standing position.

1. Mount two table clamps to the table edge on the trainee side (for bone holders) and one clamp on an adjacent side (for the webcam stand).

1. Attach the webcam (Logitech C270 or equivalent 720p camera) to the gooseneck stand. Clamp the stand to the table edge.

1. Position the webcam approximately 60 cm above the workspace. Adjust camera orientation so the entire workspace area and both AR markers on the bone assembly are visible in the camera view on the computer screen.

1. Attach the LED ring light clamp to the camera stand, positioning the ring around the camera lens. Connect to the computer via USB. Adjust brightness for uniform white illumination across the workspace.

1. Connect the webcam to the computer via USB. Open a web browser (Chrome v84+, Firefox v77+, or Safari v11+) and navigate to opensurgisim.com.

Setup video: Camera stand and webcam setup.

Obtain the printed holder and tool files from the developer's other-parts collection: Bone-holder 1.stl, Bone-holder 2.stl, Cut-error measurement tool.stl, Independent marker holder.stl. Keep the two bone-holder filenames distinct in the assembly record even though the current source files contain the same model. Use the selected bone-part set and marker route from Phase 1.

1. Gather all clinical tools: power drill, hacksaw, drill bits (4.9 mm), drill sleeves (5 mm inner diameter), and the complete external rail fixator set (pins, clamps, T-handle, rail).

1. Insert the two 3D-printed bone holders into the two table clamps on the trainee side. Tighten the clamp screws to secure each bone holder.

1. Select modular bone parts for the chosen case study from the kit. Refer to the assembly guide for part codes. Assemble the parts to form the deformed bone model.

1. Place the assembled bone onto the two bone holders in the workspace. Verify that both AR markers (Marker-1 on the proximal part, Marker-2 on the distal part) face upward and are visible in the webcam view on the computer screen.
2. Run the AR calibration step in the OpenSurgiSim software (Step 4 in any psychomotor case study). Place the independent marker (with Marker-3) in the central workspace area. Adjust lighting until the on-screen instructions turn green, confirming acceptable marker detection.

Assembly and calibration videos: Bone part assembly demonstration; Bone holder and table clamp assembly; AR system calibration.

• Source: Deformity Correction of Lower Limb Bones — Basic Principles (Appropedia)