2.4 Manual Muscle Testing & ROM Goniometry for PTAs
Key Takeaways
- Manual muscle test (MMT) grades run from 0 (no contraction) to 5 (full ROM against gravity with maximal resistance); the transition at grade 3 (full ROM against gravity, no resistance) is the most-tested threshold.
- PTAs perform MMT and goniometry for data collection within the plan of care but 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 positioning is wrong (gravity-eliminated vs against-gravity), if pain limits effort, or if substitution occurs.
Manual Muscle Testing (MMT) Grades
Manual muscle testing (MMT), scored with the Kendall or Daniels-Worthingham scale, grades a muscle's ability to move a segment against gravity and applied resistance. The decisive question is whether the segment can complete its full range against gravity — that defines the jump from grade 2 to grade 3.
| 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 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 a PTA may perform when the PT has included it in the plan of care. The PTA records and reports the grade; the PT interprets it to change diagnosis or alter the plan. A PTA who finds a previously 4/5 quadriceps dropping to 2/5 collects that data and notifies the PT promptly rather than rewriting the program.
Common Validity Pitfalls
- Wrong gravity position: A patient tested against gravity who can only achieve gravity-eliminated motion must be re-tested gravity-eliminated, or the grade is invalid.
- Substitution: Hip flexion substituting for knee extension; trunk lean substituting for shoulder abduction; tenodesis mimicking finger extension.
- Pain-limited effort: Document that the test was limited by pain rather than assigning a falsely low grade.
- Inconsistent stabilization: Failing 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 on bony landmarks is what makes a measurement reproducible between sessions and between testers.
Normal ROM Benchmarks (AAOS Active ROM, Adult)
| Joint | Motion | Normal Range (degrees) |
|---|---|---|
| Shoulder | Flexion | 0-180 |
| Shoulder | Extension | 0-60 |
| 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 / Plantarflexion | 0-20 / 0-50 |
| Subtalar | Inversion / Eversion | 0-35 / 0-15 |
Values differ slightly between AAOS and American Medical Association (AMA) norms; pick the source your jurisdiction or program prefers and apply it consistently. Recording motion as, for example, "knee 10-110" indicates a 10-degree extension lag (flexion contracture) with 110 degrees of flexion — a notation style the exam expects you to read correctly.
Goniometer Technique Checklist
- Position the patient in the recommended starting position.
- Stabilize the proximal segment.
- Palpate and identify 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 the POC).
- Align the moving arm with the distal-segment landmark.
- Read and record to the nearest degree, noting AROM versus PROM and any pain.
Reliability improves with same-tester re-measurement, consistent landmarks, and an identical starting position each visit. When a measurement is contaminated by substitution, the PTA re-stabilizes, re-measures, and records the corrected value rather than mathematically subtracting an estimated error.
Positioning, End-Feels, and the PTA's Reporting Role
Reliable data collection depends on positioning the patient correctly before any grade or angle is taken. For MMT, the rule is that against-gravity testing precedes resisted testing: a muscle that cannot complete its arc against gravity is graded 2 or below and re-tested gravity-eliminated. Only a muscle that achieves full against-gravity range (grade 3) earns the addition of manual resistance for grades 4 and 5.
Normal End-Feels (Goniometry Companion Data)
| End-Feel | Example | Implication |
|---|---|---|
| Soft tissue approximation | Knee flexion (calf meets thigh) | Normal |
| Capsular (firm) | Shoulder lateral rotation | Normal limit, or abnormal if early/restricted |
| Bony (hard) | Elbow extension | Normal |
| Empty | Acute bursitis (pain stops motion) | Abnormal, report to PT |
| Springy block | Meniscal tear blocking knee extension | Abnormal, report to PT |
A PTA records end-feel as supporting data; an abnormal or unexpected end-feel (empty, springy block, or a capsular end-feel arriving far short of normal range) is reported to the supervising PT rather than treated as a target to stretch through.
Where PTA Scope Ends
The PTA collects ROM, MMT, girth, posture, and pain data and reports it accurately and promptly. The PTA does not synthesize that data into a new diagnosis, modify the plan of care's goals, or perform the initial or discharge evaluation. A trending decline — a quadriceps slipping from 4/5 to 2/5, or knee flexion regressing 15 degrees across two visits — is exactly the data the PT needs, so the PTA's value lies in capturing it precisely (degrees, grade, position, and pain) and communicating it before the next session changes anything.
A PTA is performing manual muscle testing on a patient's quadriceps. In short-sitting the patient completes full active knee extension but cannot hold 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?