Goniometry

General principles of length measurement

Visual assessment of limb length is an insufficiently precise method, as it only allows for the detection of pronounced asymmetries and disproportions. The primary and most objective tool for the clinician is the tape measure.

Comparative tape measurement not only records the fact of a discrepancy but also allows for precise documentation of metrics to assess the dynamics of the pathological process.

Key rules for taking measurements:

• Measurements are always taken strictly between easily palpable anatomical bony landmarks.
• The patient is positioned flat, and the limbs must be extended as much as possible along the longitudinal axis of the trunk.
• If there are restrictions in joint mobility (e.g., due to pain or muscle spasm), both limbs are placed in a forced but strictly symmetrical position.
• When working with the lower extremities, it is necessary to monitor the position of the pelvis: the anterior superior iliac spines (spina iliaca anterior superior) must be at the same level to eliminate errors caused by pelvic tilt.
• The tape measure is pulled taut, without sagging.

Types of limb length changes

Limb shortening is the most frequently encountered finding in traumatological practice. There are three isolated types of length changes and one combined type:

1. Absolute (true, anatomical) shortening. Characterized by a real decrease in the anatomical length of the bone. Main causes: consequences of improperly healed fractures, epiphyseal compression, or systemic bone growth disorders.
2. Relative (articular) shortening or lengthening. Indicates the presence of severe joint damage itself. Develops in the setting of dislocations or intra-articular fractures when the relative position of the articular surfaces is disrupted.
3. Apparent (functional) shortening. Associated with a fixed pathological posture (ankylosis, contracture, or marked rigidity). Main distinguishing feature: upon detailed segmental measurement, the anatomical length of each individual bone remains within normal limits.
4. Clinical (total) change. Represents a combination of several of the aforementioned types of deformities in a single patient.

Technical nuance: During differential diagnosis between absolute and relative length changes, the distal reference point always remains unchanged. The entire difference in methodology lies in the correct selection of the proximal landmark.

Bony landmarks for measurement

Measurements are divided into determining relative (the entire limb, including adjacent joints) and absolute (individual anatomical segments) length.

Lower extremity:

• Entire limb (relative length): from the anterior superior iliac spine (ASIS) to the tip of the medial malleolus.
• Entire limb (absolute length): from the tip of the greater trochanter of the femur to the medial malleolus.
• Thigh (absolute): from the greater trochanter to the lateral femoral condyle (or the lateral joint line of the knee).
• Leg (absolute): from the medial joint line of the knee joint to the tip of the medial malleolus (less commonly the lateral).

Upper extremity:

• Entire limb (relative length): from the acromion process of the scapula to the styloid process of the radius (or to the tip of the 3rd finger of the hand).
• Entire limb (absolute length): from the tip of the greater tubercle of the humerus to the styloid process.
• Arm / Upper arm (absolute): from the greater tubercle to the lateral epicondyle of the humerus.
• Forearm (absolute): from the tip of the olecranon (olecranon) to the styloid process of the radius.

Measurement of small segments and circumferences

Specific landmarks are used for the precise diagnosis of foot and hand pathologies:

• Hand width: measured transversely between the heads of the 2nd and 5th metacarpal bones.
• Finger length: from the base of the phalanx to the tip.
• Foot length: from the most prominent part of the calcaneus to the tip of the 1st toe.
• Forefoot length: from the neck of the talus to the tip of the 1st toe.
• Foot height: from the dorsal surface of the navicular bone vertically to the floor (patient standing, foot perpendicular to the leg).

Determination of limb circumference. The method is used for objective assessment of edema severity, the size of tumor-like masses, or the degree of muscle atrophy. Measurements are taken on symmetrical areas of the healthy and affected limbs at the level of the upper, middle, and lower thirds of the segment. It is extremely crucial to measure exactly the same distance from the chosen bony landmark. Basic landmarks for the lower extremities: the knee joint line, poles of the patella, tibial tuberosity. For the upper extremities: humeral epicondyles, olecranon, and styloid processes.

Biomechanical research methods

Modern orthopedics relies on a comprehensive examination that records spatial, kinematic, regulatory, and dynamic parameters of the musculoskeletal system. The main instrumental methods include dynamometry, stabilography, comprehensive gait analysis, and goniometry.

Goniometry aims to determine the range of motion in a joint, allowing the clinician to assess the degree of functional limitations and record the range of active motion for rehabilitation planning.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Assessment of passive range of motion in goniometry
• Dynamometry and stabilography: role in diagnostics
• Kinematic and dynamic parameters of gait
• Mechanisms of formation of joint contractures and ankylosis
• Clinical examples of bone epiphysis impaction

Other topics in the section "General Questions of Traumatology and Orthopedics"

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