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Single Leg Hop

Page 4.21.2 · Functional Testing · examination page

The first test that loads the knee at speed, which is where a knee that squats well can still fail.

Pipeline status. Editorial draft. Evidence verification did not run. Not consultant reviewed. Not for clinical use.

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Single Leg Hop

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For Medical Students

What It Tests

The single leg hop tests the knee's ability to produce and absorb force on one limb, so it adds power and landing control to what the squat measures. 4.21.1 covers the single leg squat.

The examination is comparing the distance hopped on each side and the quality of the landing. 4.4.9 covers single leg landing.

It matters because producing force and absorbing it are different abilities, and a knee can have one without the other. 3.14.8 covers landing.

How It Is Performed

Confirm the patient is at a stage of rehabilitation where hopping is permitted, and do not test before that. 4.2.34 covers previous rehabilitation.

Mark a starting line and ask the patient to hop forward as far as they can on one leg and land on the same leg.

Require a controlled landing that is held, since an uncontrolled landing is a failed attempt rather than a longer hop.

Measure the distance from the line to the heel, and repeat for the other side.

Watch the landing specifically, for knee position, trunk position and whether the landing is held. 3.12.7 covers dynamic valgus.

Record the ratio between the two sides rather than the absolute distances, since the comparison is what is interpreted. 4.1.4 covers the structured approach.

Note any pain or apprehension, and whether the patient refuses the test. 4.2.6 covers giving way.

What a Positive Means

Similar distances on both sides with controlled held landings is the normal result.

A shorter hop on the affected side indicates a deficit in force production, which is usually quadriceps. 4.3.9 covers muscle wasting.

A similar distance with an uncontrolled landing indicates a deficit in force absorption, which is a different problem. 4.4.9 covers single leg landing.

Apprehension or refusal is itself a finding and is often the limiting factor after a reconstruction. 4.22.6 covers the return to sport psychological measure.

Pain at landing localises to the loaded structure, which makes the test provocative as well as functional. 4.7.6 covers the painful arc.

Key Learning Points

  • Producing force and absorbing it are different abilities.
  • An uncontrolled landing is a failed attempt rather than a longer hop.
  • The ratio between sides is what is interpreted.
  • Apprehension or refusal is a finding in its own right.
  • The test provokes pain as well as measuring function.

MRCS Level

How It Is Performed

In a viva this is part of the return to sport answer and the expected version names the comparison and the landing quality.

The expected points are the rehabilitation stage, the setup, the controlled landing requirement, the measurement, the landing observation, the ratio, and the pain or apprehension.

Say that you would not test before the rehabilitation stage allows it. 4.2.34 covers previous rehabilitation.

Say that you would require the landing to be held, and give the reason. 4.4.9 covers single leg landing.

Say that you would record the ratio between limbs rather than an absolute distance. 4.1.4 covers the structured approach.

What a Positive Means

The reasoning expected is that a hop requires concentric force production for take off and eccentric absorption on landing, and the knee can be deficient in either. 3.14.7 covers jumping.

Landing produces higher forces than take off, which is why the landing is where the failure shows and why it is observed rather than only timed. 3.14.8 covers landing.

Quadriceps deficit reduces both, but reduces absorption more, which is why a hop with a poor landing is a quadriceps finding. 4.3.9 covers muscle wasting.

Fear of reinjury limits performance independently of strength, which is why apprehension is recorded separately. 4.22.6 covers the return to sport psychological measure.

How Good It Is

The test is reproducible for distance and subjective for landing quality.

Its best contribution is the side to side comparison, which converts a subjective functional judgement into a measured one. 4.7.9 covers the functional range.

It does not isolate a structure, so it measures the limb rather than the knee.

No imaging corresponds to it, so it complements the structural examination. 4.1.6 covers that relationship.

No figures appear for any accuracy comparison on this page, under decision 023, and the comparison is the claim being made. A symmetry threshold is conventional in the literature and this repository does not state the number, because the number would be written from memory.

Key Learning Points

  • A hop needs concentric production and eccentric absorption.
  • Landing forces exceed take off forces, so the landing is where failure shows.
  • A hop with a poor landing is a quadriceps finding.
  • Fear of reinjury limits performance independently of strength.
  • The side to side ratio converts a subjective judgement into a measured one.

FRCS Level

How Good It Is

At decision level the hop contributes to return to sport decisions and to monitoring rehabilitation.

A symmetrical hop with controlled landings is one of the criteria used before return to sport, and the examination supplies it. 4.21.7 covers return to sport testing.

An asymmetrical hop after a reconstruction indicates incomplete rehabilitation regardless of the laxity examination. 4.20.1 covers the reconstruction assessment.

Apprehension without a strength deficit is a different problem with a different intervention, and the test separates them. 4.22.6 covers the return to sport psychological measure.

Pain provoked at landing redirects the assessment to the structure that was loaded. 4.17.5 covers articular cartilage defects.

Where It Misleads

The commonest error is recording distance without landing quality, so a compensating patient passes. 4.4.9 covers single leg landing.

A single hop does not test fatigue, and the deficit often appears with repetition. 4.21.3 covers the triple hop.

The unaffected side is assumed normal, and after a long rehabilitation it is often deconditioned too. 4.1.4 covers the structured approach.

A symmetrical result is read as readiness, which it is one component of rather than evidence for. 4.21.8 covers return to play decision making.

Testing too early risks the healing structure, which is why the stage governs the test. 4.2.34 covers previous rehabilitation.

Key Learning Points

  • Distance without landing quality lets a compensating patient pass.
  • A single hop does not test fatigue.
  • The unaffected side is often deconditioned after a long rehabilitation.
  • A symmetrical result is one component of readiness rather than evidence for it.
  • The rehabilitation stage governs whether the test is safe.

Fellowship Level

Where It Misleads

At fellowship level the hop test's limits are about what symmetry means rather than about how it is performed.

Symmetry is measured against a limb that has also changed, so a ratio can normalise while both limbs remain below their original capacity. 4.1.4 covers the structured approach.

A single plane forward hop does not test the rotational and lateral demands that cause most knee injuries. 3.14.6 covers cutting manoeuvres.

Landing quality is graded by observation, which reintroduces the subjectivity the measured distance removed. 4.4.9 covers single leg landing.

Fear and capacity both limit the result and the test does not separate them, which is why a separate psychological measure exists. 4.22.6 covers the return to sport psychological measure.

Passing a hop battery does not establish readiness, and the literature's thresholds are conventions this repository does not restate. 4.21.8 covers return to play decision making.

Key Learning Points

  • A ratio can normalise while both limbs stay below their original capacity.
  • A forward hop does not test rotational or lateral demand.
  • Observational landing grades reintroduce subjectivity.
  • Fear and capacity both limit the result and are not separated.
  • Passing a hop battery does not establish readiness.

Explore Further

Where this topic came from and where it goes next in the spiral.

References

No reference list is attached to this draft. Evidence verification has not run, because source retrieval was unavailable at generation time. Under the Operations Handbook a missing reference is acceptable and an invented one is a critical failure, so nothing has been cited and no citation marker appears in the text. This page carries no diagnostic accuracy figure, which is decision 023 rather than an omission. The comparative standing of these tests is standard teaching and a specific sensitivity written from memory is the same class of claim as an invented citation, so ACC-001 refuses the number and the page states the comparison. A reviewer with the literature can add the figures into How Good It Is without restructuring the page, and chapter 3.17 lists the studies the figures would come from. Any measurement here, including a flexion angle, is written from standard teaching, has not been checked, and is registered under decision 006 in pipeline/config/figures with a verification state of UNVERIFIED_FROM_MEMORY.

Safety. KneeSchool is educational and does not give individual medical advice. Seek urgent assessment for a knee that cannot bear weight after an injury, a hot swollen knee with a fever, or new numbness, weakness or coldness in the leg or foot.