What it means
A knee that passes the straight line and locks backward on standing.
Where it comes from
Posterior capsule laxity with the habit of standing on a locked knee.
How it is measured
It is measured on the side view, in the sagittal plane. The defining measurement is Knee locks backward (Genu recurvatum), and it is reported as a finding from above 5°. The number is computed from landmarks on that photograph — not estimated by eye, and not compared against a stock example.
What the numbers mean
| Measurement | Grade |
|---|---|
| up to 5° | Within normal range |
| 5–10° | Mild hyperextension |
| 10–15° | Moderate hyperextension |
| 15° and above | Severe hyperextension |
Source of the bands: Loudon JK et al, JOSPT 1998;27:373-8 (knee recurvatum ≥ 5°)
What is usually seen alongside it
- Pelvis tipped forward or back (Sagittal pelvic tilt) — above 15°
None of these is a diagnosis on its own. Together they corroborate the finding; apart, they do not refute it — a measurement nobody took counts neither for nor against.
What confirms it
Generalised laxity is scored with the Beighton scale, of which knee hyperextension is one of the nine items.
Every number on this page is measured on the skin surface in a photograph. That is not the same as a measurement taken on a radiograph: it correlates with one and does not replace it. Wherever the decision depends on imaging, this page and the report itself say so.
What happens at the clinic
The assessment starts with three standing photographs — front, side and back. Every angle is measured on those photographs, the report prints the number and the grade for each, and the exercise programme is built from those numbers rather than from a template. Posture analysis explains the whole path, and the online assessment can be started from your own photograph now.
Frequently asked questions
At what point is genu recurvatum reported?
When knee locks backward (genu recurvatum) is above 5°, it is reported as a finding. That is where the "Mild hyperextension" band begins. The bands come from: Loudon JK et al, JOSPT 1998;27:373-8 (knee recurvatum ≥ 5°)
Can genu recurvatum be assessed from a photograph?
A photograph gives a number, which most assessments do not have. But it is a surface measurement and it does not replace imaging. Generalised laxity is scored with the Beighton scale, of which knee hyperextension is one of the nine items.
What is the most severe grade?
The worst band in this table is "Severe hyperextension". The grade is printed beside the measurement itself in the report, so it is always clear which number produced the word.