Multiplier vs Primal's 3D Knee
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Multiplier
This app automates complex calculations for predicting mature height, bone length, and limb length discrepancies in children. It simplifies manual methods, reducing calculation time and errors for various orthopedic and growth-related assessments.
- Predict mature height
- Calculate bone length
- Assess limb length discrepancy
- Analyze growth remaining
- Plot height on CDC charts
- Scanogram calculations
- Foot length analysis
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The Multiplier App automates calculations to predict mature height and bone length in children. This method was created originally in Baltimore at the University of Maryland and subsequently developed at the International Center for Limb Lengthening (ICLL), Rubin Institute for Advanced Orthopedics (RIAO), Sinai Hospital of Baltimore. We have taught the Multiplier Method for more than 19 years at our annual Baltimore Limb Deformity Course (http://www.DeformityCourse.com). These calculations are typically performed by hand, using various formulae. Certain calculations are easy, but others involve more complicated formulae. Utilizing this app will reduce the time needed for these routine calculations and decrease errors. You need only input certain data (sex, age, length) and the app will calculate the answer by using the appropriate Multiplier formula. The Multiplier App will allow you to make the following calculations: LOWER EXTREMITY · Limb Length Discrepancy (LLD) (Congenital) · LLD (Developmental) · Growth Remaining · Bone Length · Timing of Angular Correction · Timing of Epiphysiodesis · Comprehensive (Congenital) LLD and Epiphysiodesis · Scanogram Calculations (Calculates femur/tibia lengths, overall limb length discrepancy, and amount/side of femur/tibia discrepancies) UPPER EXTREMITY · LLD (Congenital) · LLD (Developmental) · Growth Remaining · Bone Length Height and CDC Growth Charts (Calculates height at maturity, calculates height at every age, and plots the patient’s height and weight on the CDC growth charts) ACHONDROPLASIA · Height · Sitting Height · Leg Length Fetus (Calculates the length of tibia or femur at birth and maturity) FOOT · Foot Length · Foot Length Discrepancy · Foot Height · Foot Height Discrepancy Spine (Calculates sitting height at maturity) Oblique Plane Deformity (Calculates magnitude, orientation, and direction of an oblique plane deformity) Inclined Osteotomy (Calculates the rotational orientation and the vertical inclination of the osteotomy) This app also provides the following additional resources: · Bone Age: Elbow and Hand (Shows how to determine skeletal age by using radiographs of the elbow or hand) · Figures that show the standard measurements for the lower limb and foot · The multiplier formulae that the app uses to perform the calculations · Tables that show the multiplier values that are used in the formulae · Figures that show the Solomin Foot Analysis (Deformity correction planning for the midfoot, hindfoot, and ankle using reference lines and angles provided by Dr. Leonid Solomin) · Figures that show the development of the apophyses, epiphyses, and bones · Bibliography · User guide DISCLAIMER: No growth prediction method is 100% accurate; this App is not a substitute for sound and careful clinical judgment. PRIVACY POLICY: We respect the privacy of the people who use the International Center for Limb Lengthening apps. The Multiplier app does not collect, use, or distribute any data from the users.
Primal's 3D Knee
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Primal's 3D Real-time Human Anatomy app for the Knee is the ultimate 3D interactive anatomy viewer for all medical educators, practitioners and students. Meticulously built over ten years from high-resolution cross-sectional photographs of real cadavers, the app provides an accurate and visually stunning reconstruction of the anatomy of the knee. The easy to use and intuitive interface lets you choose precisely the anatomy you want to see, from exactly the angle you want to see it. This flexibility is supported by a wealth of user-friendly tools to help you set up your ideal anatomical image, quickly and easily: • The Gallery contains 9 pre-set scenes, designed by an in-house team of anatomical experts, to clearly and comprehensibly present in-depth regional and systemic anatomy of the knee. Each scene is divided into five layers to provide greater control over the depth of anatomy shown; making tailoring the anatomy you want to see simple and quick. • The Contents folders arrange all 225 structures systemically, meaning you can browse by subcategory and switch all related structures on at once. It provides an excellent learning tool – for example turn on all branches of the popliteal artery, or the muscles of the lateral compartment of the leg. • The Contents layer controls split each system into five layers – from deep to superficial. This allows you to quickly build up different systems to the depth you want to see. **Save to Favourites** Save the views you create for later in the Favourites, save anything as an image, or share with another user as a URL link. Use the pins, labels and drawing tools to customize your images for enlivened presentations, engaging course materials and handouts – all from your iPad! **Informative** Read detailed and accurate text for each structure using the T icon, and in a feature unique to Primal Pictures, each anatomical term in the text is linked to the appropriate model in the 3D model. Selecting these links will highlight the relevant structures, bringing the text to life and make learning anatomy more visual and immediate. **Context** See each structure in context with the anatomy that surrounds it. Explore these relationships and easily navigate to related anatomical structures to expand your learning. Select a field name in the right-hand menu to show the anatomical category and sub-category of the structure for added understanding and simple navigation. **Technical Specifications** iPad 3 and above only. iPad Air and above for optimal viewing. iPhone 6 and above for best performance.
Screenshots
Verdict
The clearest difference is in-app purchases: Multiplier at none against Primal's 3D Knee's 1. Multiplier also leads on iOS requirement (13.0 vs 15.0). Primal's 3D Knee's advantage is update cadence (every 2 months vs every 7 months). On price, ads and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Primal's 3D Knee sells 1 one-off in-app purchase. Multiplier asks for nothing beyond the download.
Multiplier ships an update every 7 months, Primal's 3D Knee every 2 months. The most recent releases landed on July 2, 2026 and September 10, 2026 respectively.
| Parameter | Multiplier | Primal's 3D Knee |
|---|---|---|
| Price | Free | Free |
| Rating | 4.6 (24 ratings) — better | — |
| Positive reviews | 83.3% of reviews | — |
| Number of ratings | 24 — better | — |
| Update frequency | Every 7 months | Every 2 months — better |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Monetization | Paid | — |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 13.0 — better | 15.0 |
| Further details — not scored | ||
| Size | 62 MB | 125 MB |
| Age rating | 12+ | 12+ |
| Developer | LifeBridge Health | Pharma Intelligence UK Ltd |
In-app purchases
Multiplier
No in-app purchases
Primal's 3D Knee
- Primal's 3D Knee$39.99
Questions
Is Multiplier free?
Is Primal's 3D Knee free?
Do Multiplier or Primal's 3D Knee have ads?
Which is updated more often, Multiplier or Primal's 3D Knee?
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