TissueDB/Simulators/VesselBox Vessel Ligation Trainer (Hu)

The VesselBox Vessel Ligation Trainer is a low-cost open-surgery trainer built from locally available materials — a four-sided pine box, a disposable latex glove finger as the vessel substitute, and 3-0 silk — for teaching open vessel ligation to graduating medical students and incoming surgical interns (Hu et al. 2015, Journal of Surgical Education;^[1] Hu et al. 2015, Journal of Surgical Research^[2]). Developed at the University of Virginia, it mounts a glove finger inside the deep box: the trainee gains proximal control of the vessel and directs an assistant to take distal control with an opposing forceps, divides the vessel between the two forceps with Mayo scissors, and ties both ends with 3-0 silk, prompting the assistant to release each forceps in turn.^[1] The box is intentionally deep and vision-restricted to replicate controlling a vascular pedicle in a confined abdominal compartment.^[1] The published mounting device is proprietary and is not described in the source papers; a TissueDB-suggested binder-clip substitute is given in the build instructions below.

1. Cut four pine boards to form the walls of a deep, four-sided box because Hu et al. 2015 specify a "four-sided box created from pine wood" to simulate a confined abdominal compartment.^[1] Box dimensions are not specified in either published paper — choose a depth and base width that restrict visualisation of the working field while still permitting two-handed instrument access. A TissueDB-suggested starting reference (not source-specified) is roughly 30 × 20 × 15 cm internal.
2. Fasten the four walls together using wood screws or nails, ensuring the open working aperture permits clear instrument access and that the construct sits stable on a flat workbench surface.
3. Sand any rough edges that might catch instruments or sutures during a session.
4. Confirm the box is rigid enough to resist deformation under the tension required to tie a 3-0 silk ligation against a glove-finger vessel substitute.

Important note: the original VesselBox uses a "proprietary vessel mounting device" (Hu et al. 2015) that is not described in either published paper.^[1] The design below is a TissueDB-suggested substitute, not a replica of the published mount, and may produce different clamping force and tension. Builders seeking exact replication of the published design are encouraged to contact the corresponding author Sara K Rasmussen (skr3f@virginia.edu, University of Virginia School of Medicine) or first author Yinin Hu (yh9b@virginia.edu).

1. Cut two pine blocks to approximately 50 × 30 × 15 mm from offcuts because they will form the mounting platforms for the binder-clip clamps on either side of the box base.
2. Drill two 3 mm pilot holes through the wide face of each pine block, approximately 30 mm apart, because these holes will receive the wood screws affixing each binder-clip to its block.
3. Clamp each large binder-clip arm in a vice and drill a fine matching hole (approximately 2 mm) through each arm-shaft because the binder-clip must be screw-fastened to its pine block, not adhesive-fastened, to withstand tying tension.
4. Screw each binder-clip to its pine block using two 25 mm wood screws, one screw per arm-shaft hole into the block face.
5. Position the two clip-block assemblies on opposite walls of the box base, with the clip jaws facing each other across the compartment; space them so the mounted glove finger spans the gap under tension (exact spacing is builder's discretion — not specified in the source).
6. Drill two pilot holes through the bottom of each clip-block assembly into the box base, and affix each block with two more 25 mm wood screws.
7. Confirm a glove-finger pinched between the two clip jaw sets is held under steady tension during a test ligation, and that slips do not occur until intentional release.

Limitations of Substitute Design A (build-phase note): binder-clip clamping force is not equivalent to the published proprietary mount's tension. Some experimentation may be required to find the optimal glove-finger length and tension for a given trainee population. Glove fingers are held by friction at the binder-clip jaws; slips can occur during high-force ligation and require reseating between attempts.

1. Cut a finger from a fresh disposable latex surgical glove because the glove finger is the vessel substitute and must be discarded after two ligations per Hu et al. 2015.^[1]
2. Insert one open end of the glove finger between one binder-clip's jaws and release the clip jaws to grip, because the glove finger must be held under tension between the two mounts.
3. Repeat on the opposing binder-clip jaws, ensuring the glove finger spans the gap between the two mounts taut and parallel to the box base.
4. Confirm the mounting time is less than 30 seconds per mounted glove finger and that the construct permits two ligation attempts per mounted glove finger before disposal, both as specified by Hu et al. 2015.^[1]
5. Replace the used glove finger and any soiled silk ties between learners, then check the binder-clip mounts and pine box for rigidity and undamaged condition before the next session.

⚑ Open for review: this Cusum curriculum protocol is usage guidance and may be better housed on a dedicated learning/USE module than on the build page — flagged for the owner; retained here for now.

1. Set the Cusum acceptable failure rate at 5% and the unacceptable failure rate at 20% because Hu et al. 2015 (J Surg Res) specify these decision parameters for surgical-skill acquisition Cusum analysis on this construct.^[2]
2. Set the Type I error rate at 10% and the decision interval h₀ at 1.41 because these were the parameters used in the published Cusum-guided curriculum and produced the reported 8 to 16 practice attempts to proficiency.^[2]
3. Run the trainee through a rolling window of 8 practice attempts because Hu et al. 2015 (J Surg Res) used an 8-attempt window for proficiency assessment.^[2]
4. Score each attempt against the procedure-specific checklist and the OSATS Global Rating Scale, with camera framing limited to the simulator and the participants' forearms to blind the rater to identity and skill tier.^[1][2]
5. Plan an average session length of approximately 21.8 minutes (IQR 19.5–27.7 per Hu et al. 2015, J Surg Res) and expect 8 to 16 attempts to reach Cusum-defined proficiency.^[2]
6. Run an optional fresh human cadaver post-test at the end of curriculum (short gastric artery, mesenteric artery branch, extremity venous branch, or friable strands of breast tissue as a surrogate when no vessel is available) per the published transfer-of-skill protocol.^[2]

^[1][2]