Emergency · LIVE

Recurrent Instability of the Patella (RIP)

RIP

Sum the Hevesi 2019 Recurrent Instability of the Patella (RIP) score after first-time patellar dislocation from age, caller-assigned skeletal immaturity, trochlear dysplasia, and TT-TG/PL ratio, and return the published 0–5 point total and 10-year recurrent-instability band.

LIVE $0.005 USDC GET /api/calc/rip

Markdown: /docs/rip.md · Canonical: https://magentlab.com/docs/rip

Not a medical device. Not a diagnosis, dose, or listing recommendation.

What it computes

Sum the Hevesi 2019 Recurrent Instability of the Patella (RIP) score after first-time patellar dislocation from age, caller-assigned skeletal immaturity, trochlear dysplasia, and TT-TG/PL ratio, and return the published 0–5 point total and 10-year recurrent-instability band.

When to use

When an agent has already assigned Hevesi 2019 RIP factors after a first-time patellar dislocation and needs the published point total and 10-year recurrent-instability band, not a surgical order and not a later PIP model.

When not to use

• Not a medical device. magent does not read radiographs, assign Dejour grade, or measure TT-TG or patellar length.
• Trochlear dysplasia is a caller-assigned present/absent flag for Dejour A–D; magent does not grade trochlea.
• Age <25 scores 2; age ≥25 scores 0. Age 8–80 and TT-TG/PL 0.1–2.0 are magent clamps, not published ranges.
• This is Hevesi 2019 RIP only. Not Balcarek 2013 and not a later patellar-instability predictor (PIP) model. Does not use contralateral dislocation as a factor.
• Bands 0–1 low (10-year recurrent instability 0.0%), 2–3 intermediate (30.6%), and 4+ high (79.2%) follow Hevesi 2019. Not a reconstruction order.

Formula

RIP = age_points (<25 → 2, ≥25 → 0) + skeletal_immature 1 + trochlear_dysplasia 1 + (tt_tg_pl_ratio ≥ 0.5 → 1); Hevesi 2019; max 5; risk 0-1 low, 2-3 intermediate, 4+ high (10-year recurrent instability 0.0% / 30.6% / 79.2%)

Citation

Title

The Recurrent Instability of the Patella Score: A Statistically Based Model for Prediction of Long-Term Recurrence Risk After First-Time Dislocation

Authors

Hevesi M, Heidenreich MJ, Camp CL, Hewett TE, Stuart MJ, Dahm DL, Krych AJ

Source

Arthroscopy. 2019;35(3):953-960

DOI

10.1016/j.arthro.2018.09.017

Worked example

Also searched as

• RIP score
• Recurrent Instability of the Patella
• Hevesi RIP
• first-time patellar dislocation
• patellar instability recurrence
• TT-TG/PL ratio
• trochlear dysplasia Dejour
• skeletal immaturity physes
• Hevesi 2019

Try

Opens the live endpoint. Unpaid browser requests show the paywall; agents should send Accept: application/json.

/api/calc/rip?age=40&skeletal_immature=false&trochlear_dysplasia=false&tt_tg_pl_ratio=0.3

Full URL: https://api.magentlab.com/api/calc/rip?age=40&skeletal_immature=false&trochlear_dysplasia=false&tt_tg_pl_ratio=0.3

Call

Expect HTTP 402 until you retry with PAYMENT-SIGNATURE. Incomplete query params return HTTP 400 before any quote or charge.

curl -i -H "Accept: application/json" "https://api.magentlab.com/api/calc/rip?age=40&skeletal_immature=false&trochlear_dysplasia=false&tt_tg_pl_ratio=0.3"

Parameters

Bulk (POST)

POST the same path with a JSON items array. The first item is the GET unit; each additional item is $0.002. Invalid items return HTTP 400 before settlement.

POST /api/calc/rip Max 25 unit_amount + extra_item_amount * (n - 1) extra $0.002 PREVIEW

• 1 to 25 items. Each item uses the same keys as the GET query parameters.
• POST of 1 item costs the same as GET. Lists longer than 25: chunk into multiple POSTs. Extra items still execute; do not pad dummy rows.
• 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 (fixture)

{
  "items": [
    {
      "age": "40",
      "skeletal_immature": "false",
      "trochlear_dysplasia": "false",
      "tt_tg_pl_ratio": "0.3"
    },
    {
      "age": "40",
      "skeletal_immature": "false",
      "trochlear_dysplasia": "false",
      "tt_tg_pl_ratio": "0.3"
    }
  ]
}

Open bulk paywall →

Opens a two-item fixture on the API host. Unpaid browsers get the same MetaMask paywall as GET; Pay retries POST with those items.

Example 200 (fixture)

{
  "count": 2,
  "path": "/api/calc/rip",
  "items": [
    {
      "components": [
        {
          "value": 40,
          "factor": "age",
          "points": 0,
          "present": false
        },
        {
          "factor": "skeletal_immature",
          "points": 0,
          "present": false
        },
        {
          "factor": "trochlear_dysplasia",
          "points": 0,
          "present": false
        },
        {
          "value": 0.3,
          "factor": "tt_tg_pl_ratio",
          "points": 0,
          "present": false
        }
      ],
      "age": 40,
      "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": "Hevesi M, Heidenreich MJ, Camp CL, Hewett TE, Stuart MJ, Dahm DL, Krych AJ",
        "doi": "10.1016/j.arthro.2018.09.017",
        "id": "hevesi-2019",
        "pmid": "30612768",
        "source": "Arthroscopy. 2019;35(3):953-960",
        "title": "The Recurrent Instability of the Patella Score: A Statistically Based Model for Prediction of Long-Term Recurrence Risk After First-Time Dislocation"
      },
      "formula": "rip",
      "formula_expression": "RIP = age_points (<25 → 2, ≥25 → 0) + skeletal_immature 1 + trochlear_dysplasia 1 + (tt_tg_pl_ratio ≥ 0.5 → 1); Hevesi 2019; max 5; risk 0-1 low, 2-3 intermediate, 4+ high (10-year recurrent instability 0.0% / 30.6% / 79.2%)",
      "max_score": 5,
      "score": 0,
      "risk": "low",
      "skeletal_immature": false,
      "trochlear_dysplasia": false,
      "tt_tg_pl_ratio": 0.3
    },
    {
      "components": [
        {
          "value": 40,
          "factor": "age",
          "points": 0,
          "present": false
        },
        {
          "factor": "skeletal_immature",
          "points": 0,
          "present": false
        },
        {
          "factor": "trochlear_dysplasia",
          "points": 0,
          "present": false
        },
        {
          "value": 0.3,
          "factor": "tt_tg_pl_ratio",
          "points": 0,
          "present": false
        }
      ],
      "age": 40,
      "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": "Hevesi M, Heidenreich MJ, Camp CL, Hewett TE, Stuart MJ, Dahm DL, Krych AJ",
        "doi": "10.1016/j.arthro.2018.09.017",
        "id": "hevesi-2019",
        "pmid": "30612768",
        "source": "Arthroscopy. 2019;35(3):953-960",
        "title": "The Recurrent Instability of the Patella Score: A Statistically Based Model for Prediction of Long-Term Recurrence Risk After First-Time Dislocation"
      },
      "formula": "rip",
      "formula_expression": "RIP = age_points (<25 → 2, ≥25 → 0) + skeletal_immature 1 + trochlear_dysplasia 1 + (tt_tg_pl_ratio ≥ 0.5 → 1); Hevesi 2019; max 5; risk 0-1 low, 2-3 intermediate, 4+ high (10-year recurrent instability 0.0% / 30.6% / 79.2%)",
      "max_score": 5,
      "score": 0,
      "risk": "low",
      "skeletal_immature": false,
      "trochlear_dysplasia": false,
      "tt_tg_pl_ratio": 0.3
    }
  ]
}

Response

Example JSON

Machine form of the same example. Frozen fixture. Not a live lookup.

{
  "components": [
    {
      "value": 40,
      "factor": "age",
      "points": 0,
      "present": false
    },
    {
      "factor": "skeletal_immature",
      "points": 0,
      "present": false
    },
    {
      "factor": "trochlear_dysplasia",
      "points": 0,
      "present": false
    },
    {
      "value": 0.3,
      "factor": "tt_tg_pl_ratio",
      "points": 0,
      "present": false
    }
  ],
  "age": 40,
  "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": "Hevesi M, Heidenreich MJ, Camp CL, Hewett TE, Stuart MJ, Dahm DL, Krych AJ",
    "doi": "10.1016/j.arthro.2018.09.017",
    "id": "hevesi-2019",
    "pmid": "30612768",
    "source": "Arthroscopy. 2019;35(3):953-960",
    "title": "The Recurrent Instability of the Patella Score: A Statistically Based Model for Prediction of Long-Term Recurrence Risk After First-Time Dislocation"
  },
  "formula": "rip",
  "formula_expression": "RIP = age_points (<25 → 2, ≥25 → 0) + skeletal_immature 1 + trochlear_dysplasia 1 + (tt_tg_pl_ratio ≥ 0.5 → 1); Hevesi 2019; max 5; risk 0-1 low, 2-3 intermediate, 4+ high (10-year recurrent instability 0.0% / 30.6% / 79.2%)",
  "max_score": 5,
  "score": 0,
  "risk": "low",
  "skeletal_immature": false,
  "trochlear_dysplasia": false,
  "tt_tg_pl_ratio": 0.3
}

Client errors (HTTP 400)

Invalid params return 400 without charge. Shared HTTP 402 and 503 meanings: Payments.

Related tools

• Mirels — Sum the Mirels 1989 score for diagnosing impending pathologic fractures in long-bone metastatic disease from four caller-assigned items and return the published 4–12 integer total and band (≤7 / 8 / ≥9). Not an operative order and not SINS.
• MESS — Compute the Johansen 1990 Mangled Extremity Severity Score from caller-assigned skeletal/soft-tissue, limb ischemia, shock, and age integers, doubling ischemia when time exceeds 6 hours, and return the published 0-6 / ≥7 band.

Payment

Unpaid requests return HTTP 402 even if query parameters or POST items are missing or invalid, so CDP and agents can index the path. After a PAYMENT-SIGNATURE, 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. Unpaid valid requests return HTTP 402 with a base64 PAYMENT-REQUIRED header. HTTP 503 is not a new quote: retry the same PAYMENT-SIGNATURE. Full handshake and shared payment errors: Payments. Stdio MCP: /docs/mcp.

Guarantees

• HTTP 402 is unpaid, including a missing query. After PAYMENT-SIGNATURE, invalid parameters return HTTP 400 before settlement. You are not charged. HTTP 402 never includes the tool JSON.
• exact: settlement finishes before the tool (paymentFlow upfront). batch-settlement: verify/deposit before the tool; chargedCumulativeAmount commits after HTTP 2xx. 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.