Identification of most consistent and reliable anatomical landmark to locate and protect radial nerve during posterior approach to humerus: a cadaveric study

Abstract

The location of the radial nerve (RN) is described with various bony landmarks, but such may be disturbed in the setting of fracture and dislocation of bone. Alternative soft tissue landmarks would be helpful to locate the nerve in such setting. To recognize certain anatomic landmarks to identify, locate and protect RN from any iatrogenic injury during surgical intervention such as open reduction and internal fixation. Forty arms belonging to 20 adult cadavers were used for this study. We measured the distance of RN from the point of confluence of triceps aponeurosis (TA), tip of the acromion and tip of the lateral epicondyle along the long axis of the humerus. These distances were correlated with the upper arm length (UAL). The average UAL was 32.64±0.64 cm. The distance of the RN from the point of confluence of TA (tricepso-radial distance, TRD), tip of acromion (acromion-radial distance) and tip of lateral epicondyle of humerus (condylo-radial distance, CRD) was 3.59±0.16 cm, 14.27±0.59 cm, and 17.14±1.29 cm respectively. No correlation was found with UAL. Statistically, TRD showed the least variability and CRD showed maximum variability. The minimum TRD was found to be 3.00 cm. So this should be considered as the maximum permissible length of the triceps split. The point of confluence of the TA appears to be the most stable and reliable anatomic landmark for localization of the RN during the posterior approach to the humerus.

Three-dimensional mapping of distal humerus fracture

“…In each of these approaches, however, one of the major concerns is injuring the radial nerve (RN), which passes diagonally through the spiral groove from the medial to the lateral side of the posterior surface of the humerus [ 19 ]. During surgical interventions, such as external fixator pin placement, transfixing wires (e.g., Ilizarov) or plating, secondary or iatrogenic palsies are not uncommon [ 20 ]. Thus, it is vital to identifying of the RN during surgery, especially in the posterior approach.…”

Surgical Anatomy of the Radial Nerve at the Dorsal Region of the Humerus

“…This difficulty in identification may represent one reason for the frequent injury to the nerve during a direct dorsal approach, particularly as many anatomical publications and surgical instructions show the RN as an isolated structure crossing the humerus [10][11][12]14,16,[19][20][21] . Reports with more detailed representation of the crossing nerves 17,18 illustrate an accompanying nerve branch without naming it or examining differences in thickness or profile.…”

“…After revision surgery with plate stabilization and bone grafting for humeral shaft nonunion repair, the rate of iatrogenic RNP is even higher, up to 18.5% [6][7][8] . Despite research on radial nerve (RN) anatomy [9][10][11][12][13][14][15][16][17][18] and the effort of establishing safe and danger zones 15,[19][20][21][22] to avoid iatrogenic nerve lesions, damage following surgical treatment resulting in RNP continues to occur frequently.…”

The morphological and morphometric analysis of the variant patterns of the tricipital aponeurosis: a new anatomical classification with possible clinical implications

“…The apex of TA is especially helpful in localization of radial nerve in the setting of the distal third humerus shaft fracture as this soft tissue landmark is formed by the long head and lateral head of triceps and their attachments are well proximal to the level of injury, thus, not likely to change with trauma [1]. Patra et al named this distance as tricepso-radial distance (TRD at the point of confluence) and reported this as the most consistent one for RN localisation [22].…”