A group of hand surgeons realized in the 1970s that the level of injury did not predict the number of available muscles in the upper limb very well. Therefore the international classification was established in 1979, at the Edinburgh meeting. It was called “The international classification (IC) of hand surgery in tetraplegic patients” (table 2) and it describes the number of possible transferable muscles. To measure and evaluate hand strength each muscle is tested and all muscles with a
BMRC grade of M4 or more are recorded.
[3]Table 2: International Classification of Hand surgery in Tetraplegic Patients
[3]
| Group | M4 (BMRC) Muscles |
| IC 0 | No muscle below the elbow |
High-level Tetraplegia | | |
| IC 1 | m. brachioradialis |
| IC 2 | m. extensor carpi radialis longus |
Mid-level tetraplegia | | |
| IC 3 | m. extensor carpi radialis brevis |
| IC 4 | m. pronator teres |
| IC 5 | m. flexor carpi radialis |
Low-level tetraplegia | | |
| IC 6 | finger extensors |
| IC 7 | thumb extensor |
| IC 8 | partial digital flexors |
| IC 9 | lack only intrinsics |
| IC X | exceptions |
A muscle not included in the International Classification, but of great importance, is the triceps muscle. When assessing a patient pre-operatively the triceps strength must also be recorded. An active triceps means a patient can reach in space, and the elbow can be stabilized against gravity and against other muscles to be transferred. (see further)
[3]
Furthermore, to classify patients it is essential to record sensation in at least the thumb and index pulpa. Patients with a
two point discrimination of less than 10mm are classified as cutaneous sensation (OCu) and patients with a two point discrimination of more than 10mm are classified as ocular sensation (O) (meaning that control of the to be operated limb cannot be performed by normal sensation, but is controlled visually).
[28]
Therefore patients are classified as: O or OCu, IC gr(0-X), Triceps + or –
For example: a patient has sensation of 8 mm in thumb and index pulpa, and has a good brachioradialis, extensor carpi radialis longus and brevis and a pronator teres (all of M4) but no Triceps. This patient is classified as OCu 4, Tr -.
TABLE 1. International Classification for Surgery of the Hand in Tetraplegia (Edinburgh 1978, Modified—Giens, 1984)
Reprinted with permission from Kuz JE, Van Heest AE, House JH. Biceps-to-triceps transfer in tetraplegic patients: report of the medial routing technique and follow-up of three cases. J Hand Surg 1999;24A:161–172.
Grade | Lowest Motor Description | Muscle Function Below the Elbow |
0 | Elbow Flexion/supination | None |
1 | Forearm neutralization | BR |
2 | Weak wrist extension | ECRL |
3 | Strong wrist extension | ECRB |
4 | Forearm pronation | PT |
5 | Wrist flexion | FCR |
6 | Finger extension | EDC |
7 | Thumb extension | EPL |
8 | Weak digital flexion | FDS |
9 | Strong digital Flexion (lacks only intrinsics) | FDP |
X | Exceptions | Variable |