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.^[1] 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 main cost is the 3D-printed bone kit (about $400–700, SLS or FDM); the webcam, lighting and clinical instruments are ordered off-the-shelf or are the surgeon's own. Developed by AlgoSurg Inc. (USA) and the Center for Limb Lengthening & Reconstruction, Mangal Anand Hospital, Mumbai.

3D Model Files (STL) for Bone Kit:

• Parts with marker holder (Alternative 1 — SLS, markers built in)
• Parts with marker holder (Alternative 2 — color print, separate markers)
• Parts without marker holder
• Other parts (bone holders, marker holder, cut-error tool)
• AR Markers PDF (for Alternative 2)

Assembly and Setup Videos:

• Bone part assembly demonstration
• Marker cutting and placement
• Camera stand and webcam setup
• Bone holder and table clamp assembly
• AR system calibration

1. Download STL files for the modular bone parts from Google Drive. Files are organized into four categories: parts with marker holder (Alternative 1 or Alternative 2), parts without marker holder, and other parts (bone holders, marker holder, cut-error tool).
2. Send STL files to a 3D printing service. Specify: 2–3 mm wall thickness, hollow interior. Alternative 1 uses SLS printing (markers integrated — no separate marker printing needed). Alternative 2 uses HP Jet Fusion color printing (requires separate marker printing on sticker paper).

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 2 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).

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.

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.

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.