# Pittsburgh Knee Rule Calculator

> Pittsburgh Knee Rule Calculator is a paid API for AI agents from api.magentlab.com, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-15).

Applies the Pittsburgh knee rule (Seaberg 1994) to determine whether a knee radiograph is indicated after fall or blunt trauma, based on age and ability to walk.

## Facts

- Endpoint: GET https://api.magentlab.com/api/calc/pittsburgh_knee
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/pittsburgh-knee-rule-calculator-a21791e3
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_tgOL6M0CzZ-sr7D_hx0Ql

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability pittsburgh-knee-rule-calculator-a21791e3
```

Example prompt: Apply the Pittsburgh knee rule for a 58-year-old patient who fell and is unable to walk four weight-bearing steps — should they get a knee x-ray?

## When to prefer this

Use this endpoint when you need to apply the Pittsburgh knee rule specifically (Seaberg 1994), as distinct from the Ottawa knee rule. Best for emergency department triage workflows, clinical decision support agents, or EHR integrations where a deterministic, cited rule is required to determine knee radiograph necessity after fall or blunt trauma. Prefer this over manual rule lookup when age and ambulation status are already known.

## Known failure modes

- Missing required query parameters (age, blunt_trauma_or_fall, unable_to_walk_four_steps) returns a validation error
- Age outside 0-120 range may produce an error or undefined behavior
- Passing non-boolean for boolean fields returns an error
- Misapplying rule to non-fall/non-blunt-trauma mechanism may yield incorrect interpretation

## How this service works

Pittsburgh knee rule (Seaberg 1994): after fall or blunt trauma, a knee radiograph is indicated if the patient cannot walk four weight-bearing steps or is younger than 12 or older than 50. Deterministic published rule with citation. Not a diagnosis; not the Ottawa knee rule.

## Output

Returns the result of the Pittsburgh knee rule: whether a knee radiograph is indicated (true/false), with the specific rule criteria met (age limb, ambulation limb, mechanism requirement), and citation to Seaberg 1994. Deterministic output — not a diagnosis.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "headers": {
     "type": "object",
     "additionalProperties": {
      "type": "string"
     }
    },
    "queryParams": {
     "type": "object",
     "required": [
      "age",
      "blunt_trauma_or_fall",
      "unable_to_walk_four_steps"
     ],
     "properties": {
      "age": {
       "type": "integer",
       "description": "Age in years (0-120). Seaberg 1994: younger than 12 or older than 50 meets the age limb; 12 and 50 do not."
      },
      "blunt_trauma_or_fall": {
       "type": "boolean",
       "description": "Fall or blunt trauma mechanism (Seaberg 1994). true or false as assigned by the caller. The rule does not indicate a film without this mechanism."
      },
      "unable_to_walk_four_steps": {
       "type": "boolean",
       "description": "Inability to ambulate four weight-bearing steps (Seaberg 1994). true or false as assigned by the caller."
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "path": "/api/calc/pittsburgh_knee",
  "count": 2,
  "items": [
   {
    "formula": "pittsburgh_knee",
    "citation": {
     "id": "seaberg-1994",
     "doi": "10.1016/0735-6757(94)90274-7",
     "title": "Clinical decision rule for knee radiographs",
     "source": "Am J Emerg Med. 1994;12(5):541-543",
     "authors": "Seaberg DC, Jackson R"
    },
    "criteria": [
     {
      "met": true,
      "factor": "blunt_trauma_or_fall"
     },
     {
      "met": false,
      "factor": "unable_to_walk_four_steps"
     },
     {
      "met": false,
      "value": 30,
      "factor": "age_lt_12"
     },
     {
      "met": false,
      "value": 30,
      "factor": "age_gt_50"
     }
    ],
    "age_years": 30,
    "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.",
    "xray_indicated": false,
    "formula_expression": "Knee x-ray indicated iff blunt_trauma_or_fall and (unable_to_walk_four_steps or age < 12 or age > 50)",
    "blunt_trauma_or_fall": true,
    "unable_to_walk_four_steps": false
   },
   {
    "formula": "pittsburgh_knee",
    "citation": {
     "id": "seaberg-1994",
     "doi": "10.1016/0735-6757(94)90274-7",
     "title": "Clinical decision rule for knee radiographs",
     "source": "Am J Emerg Med. 1994;12(5):541-543",
     "authors": "Seaberg DC, Jackson R"
    },
    "criteria": [
     {
      "met": true,
      "factor": "blunt_trauma_or_fall"
     },
     {
      "met": false,
      "factor": "unable_to_walk_four_steps"
     },
     {
      "met": false,
      "value": 30,
      "factor": "age_lt_12"
     },
     {
      "met": false,
      "value": 30,
      "factor": "age_gt_50"
     }
    ],
    "age_years": 30,
    "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.",
    "xray_indicated": false,
    "formula_expression": "Knee x-ray indicated iff blunt_trauma_or_fall and (unable_to_walk_four_steps or age < 12 or age > 50)",
    "blunt_trauma_or_fall": true,
    "unable_to_walk_four_steps": false
   }
  ]
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/pittsburgh-knee-rule-calculator-a21791e3/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.magentlab.com](https://www.zero.xyz/host/api.magentlab.com/llms.txt)