2.4 Manual Muscle Testing & ROM Goniometry for PTAs
Key Takeaways
- Manual muscle testing (MMT) grades run from 0 (no contraction) to 5 (full ROM against gravity with maximal resistance); grades 2, 3, and 4 are the most clinically actionable for tracking progress.
- PTAs may perform MMT and goniometry for data collection within the plan of care, but PTAs do not interpret findings to change the diagnosis or rewrite the plan — that remains the physical therapist's role.
- Normal range of motion (ROM) benchmarks include shoulder flexion 0-180, knee flexion 0-135, hip external rotation 0-45, ankle dorsiflexion 0-20, and elbow flexion 0-150 degrees per American Academy of Orthopaedic Surgeons (AAOS) norms.
- Goniometer placement uses three landmarks: stationary arm aligned with the proximal segment, fulcrum over the joint axis, moving arm aligned with the distal segment.
- An MMT grade is invalid if the patient cannot be positioned correctly (gravity-eliminated vs against-gravity), if pain limits effort, or if substitution occurs.
Manual Muscle Testing (MMT) Grades
MMT, also called manual muscle testing or the Kendall/Daniels-Worthingham scale, grades a muscle's ability to move a segment against gravity and resistance.
| Grade | Numeric | Description |
|---|---|---|
| 0 | 0/5 | Zero — no palpable contraction |
| 1 | 1/5 | Trace — palpable contraction, no movement |
| 2- | 2-/5 | Partial ROM in a gravity-eliminated position |
| 2 | 2/5 | Poor — full ROM in a gravity-eliminated position |
| 2+ | 2+/5 | Initiates movement against gravity but cannot complete full ROM |
| 3- | 3-/5 | More than 50% but less than full ROM against gravity |
| 3 | 3/5 | Fair — full ROM against gravity, no manual resistance |
| 3+ | 3+/5 | Full ROM against gravity with minimal resistance |
| 4 | 4/5 | Good — full ROM against gravity with moderate resistance |
| 5 | 5/5 | Normal — full ROM against gravity with maximal resistance |
PTA Scope Notes
The American Physical Therapy Association (APTA) lists MMT under data collection that a PTA may perform when the PT has included it in the plan of care. The PTA records the grade and reports it; the PT interprets it to change diagnosis or alter the plan of care. A PTA who notices a previously 4/5 quadriceps falling to 2/5 collects that data and notifies the PT promptly rather than rewriting the program.
Common Validity Pitfalls
- Wrong position: A patient placed against gravity who can only achieve gravity-eliminated motion should be re-tested gravity-eliminated.
- Substitution: Hip flexion substituting for knee extension; trunk lean substituting for shoulder abduction.
- Pain-limited effort: Document that the test was limited by pain rather than assigning a falsely low grade.
- Inconsistent stabilization: Failure to stabilize the proximal segment invalidates the grade.
Range of Motion (ROM) Goniometry
A universal goniometer has three components: a fulcrum (axis), a stationary arm, and a moving arm. Standardized placement using bony landmarks is what makes a measurement reproducible.
Normal ROM Benchmarks (AAOS Active ROM, Adult)
| Joint | Motion | Normal Range (degrees) |
|---|---|---|
| Shoulder | Flexion | 0-180 |
| Shoulder | Extension | 0-50-60 |
| Shoulder | Abduction | 0-180 |
| Shoulder | Internal rotation | 0-70 |
| Shoulder | External rotation | 0-90 |
| Elbow | Flexion | 0-150 |
| Forearm | Pronation / Supination | 0-80 / 0-80 |
| Wrist | Flexion / Extension | 0-80 / 0-70 |
| Hip | Flexion | 0-120 |
| Hip | Extension | 0-30 |
| Hip | Abduction / Adduction | 0-45 / 0-30 |
| Hip | Internal / External rotation | 0-45 / 0-45 |
| Knee | Flexion | 0-135 |
| Ankle | Dorsiflexion | 0-20 |
| Ankle | Plantarflexion | 0-50 |
| Subtalar | Inversion / Eversion | 0-35 / 0-15 |
Values vary slightly between AAOS and American Medical Association (AMA) norms; use the source your jurisdiction or program prefers consistently.
Goniometer Technique Checklist
- Position the patient in the recommended starting position.
- Stabilize the proximal segment.
- Identify and palpate the joint axis (fulcrum landmark).
- Align the stationary arm with the proximal segment landmark.
- Move the distal segment through available ROM (active or passive per POC).
- Align the moving arm with the distal segment landmark.
- Read and record to the nearest degree, noting AROM vs PROM and pain.
Reliability improves with same-tester re-measurement, consistent landmarks, and standardized starting position.
A PTA is performing manual muscle testing on a patient's quadriceps. With the patient in short-sitting, they complete full active knee extension but cannot maintain the position against any downward resistance. Which MMT grade is MOST appropriate?
During shoulder flexion goniometry, a PTA measures 165 degrees but observes the patient extending the lumbar spine and elevating the scapula. What is the BEST PTA action before recording the value?