# Ottawa ankle rule Ottawa ankle rule ## Also searched as - Ottawa ankle rule - Ottawa Ankle Rules - Stiell ankle rule - ankle x-ray decision rule - OAR ankle - Ottawa radiography ankle - Stiell 1992 ankle - malleolar zone x-ray rule Status: LIVE Price: $0.005 USDC `GET /api/calc/ottawa_ankle` HTML: https://magentlab.com/docs/ottawa-ankle Markdown: https://magentlab.com/docs/ottawa-ankle.md Not a medical device. Not a diagnosis, dose, or listing recommendation. ## What it computes Apply the Stiell 1992 Ottawa ankle rule and return whether an ankle x-ray series is indicated from caller-assigned malleolar pain, malleolar bone tenderness, and inability to bear weight. ## When to use When an agent has caller-assigned findings after blunt ankle injury and needs the published ankle-series radiography rule, not the Ottawa foot rule. ## When not to use - Not a diagnosis of fracture. magent does not examine the ankle. - This tool is the Ottawa ankle rule only. It is not the Ottawa foot or midfoot rule (navicular or fifth metatarsal) and not the Pittsburgh knee rule. - Inability to bear weight means both immediately after injury and in the emergency department (four steps). One alone is not enough. - Adult rule as published. magent does not take age; the caller assigns the five findings. ## Formula ``` Ankle x-ray indicated iff malleolar_pain and (lateral_malleolus_tenderness or medial_malleolus_tenderness or (unable_to_bear_weight_immediately and unable_to_bear_weight_in_ed)) ``` ## Citation [A study to develop clinical decision rules for the use of radiography in acute ankle injuries](https://doi.org/10.1016/S0196-0644(05)82656-3) Stiell IG, Greenberg GH, McKnight RD, Nair RC, McDowell I, Worthington JR Ann Emerg Med. 1992;21(4):384-390 DOI: [10.1016/S0196-0644(05)82656-3](https://doi.org/10.1016/S0196-0644(05)82656-3) ## Worked example ### All findings absent Given: `lateral_malleolus_tenderness=false, malleolar_pain=false, medial_malleolus_tenderness=false, unable_to_bear_weight_immediately=false, unable_to_bear_weight_in_ed=false` 1. No malleolar pain, no malleolar bone tenderness, and able to bear weight 2. Ankle x-ray is not indicated ### Malleolar pain and lateral malleolus tenderness Given: `lateral_malleolus_tenderness=true, malleolar_pain=true, medial_malleolus_tenderness=false, unable_to_bear_weight_immediately=false, unable_to_bear_weight_in_ed=false` 1. Pain in the malleolar zone 2. Bone tenderness at the posterior edge or tip of the lateral malleolus 3. Ankle x-ray is indicated ### Unable immediately but able in the ED Given: `lateral_malleolus_tenderness=false, malleolar_pain=true, medial_malleolus_tenderness=false, unable_to_bear_weight_immediately=true, unable_to_bear_weight_in_ed=false` 1. Malleolar pain is present 2. Unable immediately after injury, but able to take four steps in the ED 3. One weight-bearing failure alone is not enough; ankle x-ray is not indicated ## Parameters - `malleolar_pain` (boolean, required): Pain in the malleolar zone as assigned by the caller. true or false. Ankle x-ray is not indicated when false, even if tenderness flags are true. - `lateral_malleolus_tenderness` (boolean, required): Bone tenderness at the posterior edge or tip of the lateral malleolus. true or false. Applies only inside the malleolar zone. - `medial_malleolus_tenderness` (boolean, required): Bone tenderness at the posterior edge or tip of the medial malleolus. true or false. Applies only inside the malleolar zone. - `unable_to_bear_weight_immediately` (boolean, required): Unable to bear weight immediately after injury (four steps). true or false. Counts only when also unable in the emergency department. - `unable_to_bear_weight_in_ed` (boolean, required): Unable to bear weight in the emergency department (four steps). true or false. Counts only when also unable immediately after injury. ## Bulk (POST) POST the same path with a JSON items array. Price is n times the GET unit. Invalid items return HTTP 400 before settlement. Method: `POST /api/calc/ottawa_ankle` Max items: 25 Price: unit_amount * n (unit 5000 atomic) Status: PREVIEW - 1 to 25 items. Each item uses the same keys as the GET query parameters. - The first invalid item fails the whole request (index in the 400 JSON). You are not charged. - HTTP 200 is {count, path, items}. Each items[i] is the GET 200 body for that row. - Catalog misses (empty matches, found=false) stay paid 200s inside that slot. - x402 resource URL is this path plus n and body_sha256. Browsers that prefer text/html get the same paywall as GET; Pay retries POST with the same items. Example request: ```json { "items": [ { "lateral_malleolus_tenderness": "false", "malleolar_pain": "false", "medial_malleolus_tenderness": "false", "unable_to_bear_weight_immediately": "false", "unable_to_bear_weight_in_ed": "false" }, { "lateral_malleolus_tenderness": "false", "malleolar_pain": "false", "medial_malleolus_tenderness": "false", "unable_to_bear_weight_immediately": "false", "unable_to_bear_weight_in_ed": "false" } ] } ``` Human paywall (two-item fixture): https://api.magentlab.com/paywall/bulk/ottawa-ankle Example 200: ```json { "count": 2, "path": "/api/calc/ottawa_ankle", "items": [ { "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.", "citation": { "authors": "Stiell IG, Greenberg GH, McKnight RD, Nair RC, McDowell I, Worthington JR", "doi": "10.1016/S0196-0644(05)82656-3", "id": "stiell-1992", "source": "Ann Emerg Med. 1992;21(4):384-390", "title": "A study to develop clinical decision rules for the use of radiography in acute ankle injuries" }, "formula": "ottawa_ankle", "formula_expression": "Ankle x-ray indicated iff malleolar_pain and (lateral_malleolus_tenderness or medial_malleolus_tenderness or (unable_to_bear_weight_immediately and unable_to_bear_weight_in_ed))", "criteria": [ { "factor": "malleolar_pain", "met": false }, { "factor": "lateral_malleolus_tenderness", "met": false }, { "factor": "medial_malleolus_tenderness", "met": false }, { "factor": "unable_to_bear_weight_both", "met": false, "unable_to_bear_weight_immediately": false, "unable_to_bear_weight_in_ed": false } ], "xray_indicated": false }, { "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.", "citation": { "authors": "Stiell IG, Greenberg GH, McKnight RD, Nair RC, McDowell I, Worthington JR", "doi": "10.1016/S0196-0644(05)82656-3", "id": "stiell-1992", "source": "Ann Emerg Med. 1992;21(4):384-390", "title": "A study to develop clinical decision rules for the use of radiography in acute ankle injuries" }, "formula": "ottawa_ankle", "formula_expression": "Ankle x-ray indicated iff malleolar_pain and (lateral_malleolus_tenderness or medial_malleolus_tenderness or (unable_to_bear_weight_immediately and unable_to_bear_weight_in_ed))", "criteria": [ { "factor": "malleolar_pain", "met": false }, { "factor": "lateral_malleolus_tenderness", "met": false }, { "factor": "medial_malleolus_tenderness", "met": false }, { "factor": "unable_to_bear_weight_both", "met": false, "unable_to_bear_weight_immediately": false, "unable_to_bear_weight_in_ed": false } ], "xray_indicated": false } ] } ``` ## Response fields - `formula` (string): ottawa_ankle - `formula_expression` (string): Stiell 1992 ankle-series indication rule - `xray_indicated` (boolean): true when malleolar pain is present and any zone criterion is met. Not a diagnosis of fracture. - `criteria` (array): Per-factor rows with factor and met; unable_to_bear_weight_both is both unable flags - `citation` (object): Stiell 1992 Ann Emerg Med citation - `disclaimer` (string): Not-a-device notice ## Example JSON Frozen fixture. Not a live lookup. ```json { "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.", "citation": { "authors": "Stiell IG, Greenberg GH, McKnight RD, Nair RC, McDowell I, Worthington JR", "doi": "10.1016/S0196-0644(05)82656-3", "id": "stiell-1992", "source": "Ann Emerg Med. 1992;21(4):384-390", "title": "A study to develop clinical decision rules for the use of radiography in acute ankle injuries" }, "formula": "ottawa_ankle", "formula_expression": "Ankle x-ray indicated iff malleolar_pain and (lateral_malleolus_tenderness or medial_malleolus_tenderness or (unable_to_bear_weight_immediately and unable_to_bear_weight_in_ed))", "criteria": [ { "factor": "malleolar_pain", "met": false }, { "factor": "lateral_malleolus_tenderness", "met": false }, { "factor": "medial_malleolus_tenderness", "met": false }, { "factor": "unable_to_bear_weight_both", "met": false, "unable_to_bear_weight_immediately": false, "unable_to_bear_weight_in_ed": false } ], "xray_indicated": false } ``` ## Errors - HTTP 400 `invalid_flag`: boolean clinical flags must be true or false Returned before settlement; you are not charged. - HTTP 400 `invalid_items`: POST body must be a JSON object with only an items array Returned before settlement; you are not charged. - HTTP 400 `invalid_item_count`: items must be an array of 1 to 25 objects Returned before settlement; you are not charged. - HTTP 400 `invalid_item`: each items entry must be a JSON object Returned before settlement; you are not charged. Shared HTTP 402 and 503: https://magentlab.com/docs/payments ## Related tools - [San Francisco Syncope Rule](https://magentlab.com/docs/sf-syncope) — Compute the San Francisco Syncope Rule (CHESS) criterion count and rule-positive flag from published cutoffs. ## Payment Required query parameters must be present and valid. Invalid params return HTTP 400 JSON before settlement. magent does not charge. Fix the params, then request a new 402 quote for that complete URL. Catalog misses (empty matches, found=false) are valid paid 200s. - GET the tool with Accept: application/json (do not send Accept: text/html unless you want the human paywall). - HTTP 402 means you have not paid. Decode the base64 PAYMENT-REQUIRED header. HTTP 503 is not a new quote. - Sign EIP-3009 (scheme exact, assetTransferMethod eip3009) with validBefore = now + accepts[0].maxTimeoutSeconds (600 seconds). That window starts when you sign and must cover wallet confirmation plus CDP verify and settle. Magent retries transient facilitator 429/5xx before answering. Do not send upto or batch-settlement payloads; magent does not offer those schemes. - Retry the same URL with PAYMENT-SIGNATURE (base64 JSON echoing accepted, payload, and extensions when present). - Success is HTTP 200 JSON plus PAYMENT-RESPONSE. Settlement happens before the tool runs. HTTP 503 settlement_uncertain or settle_failed: retry the same PAYMENT-SIGNATURE. Mint a new nonce only after a new HTTP 402. - offered `exact` on eip155:8453: Fixed-price USDC on Base. The buyer authorizes the advertised amount (EIP-3009). magent settles before the tool runs (paymentFlow upfront). extra.assetTransferMethod=eip3009 extra.paymentFlow=upfront. - not offered `upto`: Not offered. Usage-based: buyer authorizes a ceiling, seller settles the actual amount after work. Reserved for a future metered tool. Not for current calculators or code search. - not offered `batch-settlement`: Not offered. Payment-channel vouchers claimed later in batches. Not the same as POST {items} bulk (that is still exact). Same-path POST {items} is still scheme exact: one EIP-3009 authorization for n times the GET unit. That is not x402 batch-settlement (payment channels / vouchers). Shared HTTP 402 and 503 table: https://magentlab.com/docs/payments Stdio MCP (one process per host): https://magentlab.com/docs/mcp ## Guarantees - Invalid query parameters return HTTP 400 before settlement. You are not charged. - Settlement finishes before the tool executes (paymentFlow upfront). Uncertain or failed settlement fails closed (HTTP 503). Retry the same PAYMENT-SIGNATURE. - HTTP 402 is unpaid only. Do not sign a second authorization because of a 503. - Execution is timeout-bounded and concurrency-capped. - Calculator inputs are stored encrypted for allowlisted operators (Magent Console). They are not in public logs, SSH lookups, catalog, or rollups. Request logs store path without query.