Relationship between the Branching Patterns of the Radial Nerve and Supinator Muscle.

The posterior interosseous nerve (PIN) innervates the posterior compartment muscle of the forearm and is a continuation of the deep branch of the radial nerve. The anatomic descriptions of PIN vary among different authors. This study investigated the distribution patterns of PIN and its relationships to the supinator muscle. This study investigated which nerves innervate the posterior compartment muscles of the forearm, the radial nerve, and the PIN, using 28 nonembalmed limbs. Also, the points where the muscle attaches to the bone were investigated. The measured variables in this study were measured from the most prominent point of the lateral epicondyle of the humerus (LEH) to the most distal point of the radius styloid process. For each specimen, the distance between the above two points was assumed to be 100%. The measurement variables were the attachment area of the supinator and branching points from the radial nerve. The attachment points of the supinator to the radius and ulna were 47.9% ± 3.6% and 31.5% ± 5.2%, respectively, from the LEH. In 67.9% of the specimens, the brachioradialis and extensor carpi radialis longus (ECRL) were innervated by the radial nerve before superficial nerve branching, and the extensor carpi radialis brevis (ECRB) innervated the deep branch of the radial nerve. In 21.4% of the limbs, the nerve innervating the ECRB branched at the same point as the superficial branch of the radial nerve, whereas it branched from the radial nerve in 7.1% of the limbs. In 3.6% of the limbs, the deep branch of the radial nerve branched to innervate the ECRL. PIN was identified as a large branch without divisions in 10.7% and as a deep branch innervating the extensor digitorum in 14.3% of the limbs. The anatomic findings of this study would aid in the diagnosis of PIN syndromes.

Transbrachioradialis Approach to the Radial Tunnel: An Anatomic Study of 5 Potential Compression Sites.

BACKGROUND: Recent anatomic studies have failed to demonstrate a single utilitarian approach to intraoperative identification and surgical release of all 5 potential sites of posterior interosseous nerve (PIN) compression in the radial tunnel. This study examines if a single incision brachioradialis-splitting approach without the use of additional anatomic windows is capable of adequately exposing the entire length of the radial tunnel, including all 5 sites of PIN compression to allow for adequate release. METHODS: Ten fresh frozen cadaver forearms (6 female, 4 male) were dissected utilizing a curvilinear 7 cm incision over the brachioradialis. The muscle belly was split via simple blunt retraction, exposing the radial tunnel. The PIN was identified and mobilized at 5 compression sites: radiocapitellar joint (RCJ), radial recurrent vessels (Leash of Henry), fibrous medioproximal edge of extensor carpe radialis brevis, arcade of Frohse, and distal edge of supinator. RESULTS: The PIN was identified and effectively released in all specimens without difficulty from this single approach. All 5 sites of compression were visible and accessible through the brachioradialis-split approach. Specifically, there was no difficulty in identifying and releasing the PIN at the distal edge of supinator. CONCLUSIONS: Radial tunnel syndrome is defined as PIN compression within the radial tunnel spanning from the fibrous RCJ to the distal edge of the supinator. A single brachioradialis-splitting approach is adequate for complete visualization and release of all compression sites of the radial tunnel. Utilizing this technique allows for surgical access and ease as well as minimizing necessity for additional windows or multiple incisions.

Avoiding radial nerve palsy in proximal radius shaft plating - a cadaver study.

BACKGROUND: Opinions vary concerning the position of forearm rotation during detachment of the supinator in radial nerve palsy Henry's and Thompson's approaches. PURPOSE: To define the optimal forearm position for a safe detachment of the supinator during these approaches and to clarify their close relationship to the posterior interosseous nerve (PIN). METHODS: The study sample comprised 90 upper extremities of 45 human adult cadavers, embalmed using Thiel's method. After detection of the radial nerve in the interval between the brachialis and brachioradialis, its pathway was traced to the Arcade of Frohse (AF). Measurements involved the distance between the AFand the radial border of the distal biceps tendon (DBT) in pronation and supination, the interval between the AF and the radiocapitellar joint space (RCJS) in supination and the radial length (RL). RESULTS: Distances between the DBT and the AF were significantly shorter during pronation (right side: 14.1 ± 3.4mm; left side: 13.5 ± 3.2mm) compared with supination (right side: 20.5 ± 3.6mm; left side: 19.8 ± 3.5mm) for both right and left extremities. The mean interval between the AF and the centre of the RCJS was 25.2 ± 5.9mm for the right side and 24.7 ± 5.6mm for the left side, which correlated positively with the RL. CONCLUSION: These results indicate a safe detachment of the supinator from the radius with the forearm placed in supination during both Henry's and Thompson's approaches.

Sensory nerve supply of the distal radio-ulnar joint with regard to wrist denervation.

The objective of this study was to determine the precise departure points of the articular branches innervating the distal radio-ulnar joint from the anterior and posterior interosseous nerves. The study sample consisted of 116 upper limbs from adult human cadavers. The articular branches were prepared under the dissection microscope to take measurements using the radial styloid process as point of reference. The articular branch departed from the anterior interosseous nerve at a mean distance of 2.9 cm proximal to the styloid for a radius length of 20.5 cm, and 3.7 cm for a radius length of 26.5 cm, respectively. For the posterior interosseous nerve, the departure point was at a mean distance of 3.1 cm (radius length of 20.5 cm) and at 4.0 cm (radius length of 26.5 cm). Apart from a single branch from the posterior interosseous nerve, all articular branches were located distal to the proximal border of the pronator quadratus. Results indicate that wrist denervation from the volar approach, if performed at the proximal border of the pronator quadratus, or from the dorsal approach at a distance of 4.8 cm (for a radius length of 20.5 cm) or 6.2 cm (for a radius length of 26.5 cm) proximal to the radial styloid process, will eliminate the nerve supply to the distal radio-ulnar joint in the majority of cases.

Deep branch of the radial nerve in lateral surgical approaches to the radial head - A cadaveric study.

INTRODUCTION: The traditional Kocher approach for lateral radial head exposure may be complicated by injury to the deep branch of the radial nerve (DBRN) and the radial collateral ligament. Kaplan approach is less commonly used, due to its known proximity to the DBRN. Extensor Digitorum Communis (EDC) splitting approach allows possible wide surgical exposure and low risk of radial collateral ligament injury. The comparison of the proximity of the DBRN to the surgical dissection at the level of radial head among approaches to the radial head has not previously been evaluated. We aimed to determine the anatomical proximity of the DBRN in these 3 common radial head approaches and to define a safe zone of dissection for the surgical exposure. METHODS: Cadaveric dissections of 9 pairs of fresh frozen upper extremities were performed using EDC splitting, Kaplan and Kocher approach to the radial head sequentially in a randomized order. A mark was made on the radial head upon initial exposure during dissection. Measurements from the marked point of the radial head to the DBRN were made at the level of radial head. RESULTS: The distance of DBRN to the radial head was 20 (17-22) mm in EDC splitting approach, 7 (3-11) mm in Kaplan approach and 29 (25-33) mm in Kocher approach. The EDC splitting approach was associated with a significantly lower chance of encountering the DBRN at the level of radial head as compared to the Kaplan approach (P<0.001). In all cases, lateral ligamentous complex was not exposed in Kaplan and EDC approaches, but were encountered in Kocher approach, risking injury to the radial collateral ligament. CONCLUSIONS: The EDC splitting approach provides adequate exposure without the need to elevate or retract the EDC and ECU muscle mass that could risk injuring the DBRN. The Kaplan approach should be done by experienced surgeons who are familiar with the anatomy in this region, with extreme caution due to proximity of the DBRN to the surgical dissection at the level of the radial head. Caution of the DBRN should be taken during anterior elevation and retraction of the muscle mass in Kocher approach. LEVEL OF EVIDENCE: IV.

Tendon and neurovascular injuries of the distal radius after pinning with Kirschner wires: A meta-analysis of cadaveric studies.

Tendon and nerve structures are at risk when displaced fractures of the distal radius are pinned using K-wires. The aim of this meta-analysis (MA) is to examine the published evidence of such complications in cadavers. Eight studies met our inclusion criteria. The meta-analytical results were as follows: (a) 2.87% and 30.5% tendon involvement at the radial styloid process (RSP) and the dorso-radial area of the distal radius, respectively; (b) 3.5% and 1.1% tendon involvement when the percutaneous pinning (PP) and the limited open pinning (LOP) techniques were used, respectively; (c) 16.1% and 3.4% nerve involvement at the RSP and the dorso-radial area of the distal radius, respectively; (d) in 35.7% the nerve was speared and in 64.3% it touched the K-wire at the styloid area; (e) 61.3% cephalic vein involvement in the styloid area; (f) the second branch of the sensitive branch of the radial nerve (SBRN) was the closest to a wire inserted into the RSP; (g) the mean (±SD) distance between a branch of the SBRN and a styloid wire was 2.17 ± 0.82 mm. Our results for nerve and tendon injury frequencies in the RSP were close to those in clinical meta-analytical studies, offering an excellent statistical model of evidence synthesis based on cadaveric studies to assess the frequency of such injuries in clinical practice. However, this cadaveric MA yielded more accurate data than the previously reported clinical MA in assessing the real risk of injury of such structures in the distal radius in terms of their proximity to the inserted K-wires.

The course of the posterior interosseous nerve in relation to the proximal radius: is there a reliable landmark?

PURPOSE: The posterior interosseous nerve (PIN) is closely related to the proximal radius, and it is at risk when approaching the proximal forearm from the ventral and lateral side. This anatomic study analyzes the location of the PIN in relation to the proximal radius depending on forearm rotation by means of a novel investigation design. The purpose of this study is to define landmarks to locate the PIN intraoperatively in order to avoid neurological complications. METHODS: We dissected six upper extremities of fresh-frozen cadaveric specimens. The mean donor age at the time of death was 81.2 years. The PIN was dissected and marked on its course along the proximal forearm with a 0.3-mm flexible radiopaque thread. Three-dimensional (3D) X-ray scans were performed, and the location of the nerve was analyzed in neutral rotation, supination, and pronation. RESULTS: In the coronal view, the PIN crosses the radial neck/shaft at a mean of 33.4 (±5.9)mm below the radial head surface (RHS) in pronation and 16.9 (±5.0)mm in supination. It crosses 4.9 (±2.2)mm distal of the most prominent point of the radial tuberosity (RT) in pronation and 9.6 (±5.2)mm proximal in supination. In the sagittal view, the PIN crosses the proximal radius 61.8 (±2.9)mm below the RHS in pronation and 41.1 (±3.6)mm in supination. The nerve crosses 29.2 (±6.2)mm distal of the RT in pronation and 11.0 (±2.8)mm in supination. CONCLUSION: With this novel design, the RT could be defined as a useful landmark for intraoperative orientation. On a ventral approach, the PIN courses 10mm proximal of it in supination and 5mm distal of it in pronation. Laterally, pronation increases the distance of the PIN to the RT to approximately 3cm.

The cadaveric anatomy of the distal radius: implications for the use of volar plates.

INTRODUCTION: Fractures of the distal radius are common upper limb injuries, representing a substantial proportion of the trauma workload in orthopaedic units. With ever increasing advancements in implant technology, operative intervention is becoming more frequent. As growing numbers of surgeons are performing operative fixation of distal radial fractures, an accurate understanding of the relevant surgical anatomy is paramount. The flexor carpi radialis (FCR) tendon forms the cornerstone of the Henry approach to the volar cortex of the distal radius. A number of key neurovascular structures around the wrist are potentially at risk during this approach, especially when the FCR is mobilised and placed under retractors. METHODS: In order to clarify the safe margins of the FCR approach, ten fresh frozen human cadaver limbs were dissected. The location of the radial artery, the median nerve, the palmar cutaneous branch of the median nerve and the superficial branch nerve were measured with respect to the FCR tendon. Measurements were taken on a centre-to-centre basis in the coronal plane at the watershed level. In addition, the distances between the tendons of brachioradialis, abductor pollicis longus and flexor pollicis longus, and the radial artery and median nerve were measured to create a complete picture of the anatomy of the FCR approach to the distal radius. RESULTS: The structure most at risk was the palmar cutaneous branch of the median nerve. It was located on average 3.4mm from the FCR tendon. The radial artery and the main trunk of the median nerve were located 7.8mm and 8.9mm from the tendon. The superficial branch of the radial nerve was 24.4mm from the FCR tendon and 11.1mm from the brachioradialis tendon. CONCLUSIONS: Operative intervention is not without complication. We believe a more accurate understanding of the surgical anatomy is key to the prevention of neurovascular damage arising from the surgical management of distal radial fractures.

McBurney's button-hole to the posterior interosseous nerve.

McBurney's button-hole is an exposure technique for the posterior interosseous nerve quoted in Anrold Kirkpatrick Henry's famous book Extensile Exposures. This short article discusses the overlap between three historical surgeons, Thompson, Henry and McBurney to discover the meaning of the reference and technique, which is used by surgeons to this day.

The effect of drill trajectory on proximity to the posterior interosseous nerve during cortical button distal biceps repair.

PURPOSE: The aim of this study was to evaluate the effect that different drill trajectories across the radius have on the proximity of the drill tip to the posterior interosseous nerve (PIN). METHODS: In 10 cadaveric specimens, we drilled from the bicipital tuberosity across the radius using 4 different trajectories: (1) aiming across the radius at 90° to the longitudinal axis of the radius, (2) distally at 45°, (3) ulnarly, and (4) radially. We measured the distance between the tip of the drill as it exited the dorsal cortex of the radius and the PIN. RESULTS: Aiming 90° across the radius and aiming ulnarly across the radius resulted in a distance of 11.2 ± 3.2 mm (95% confidence interval [CI], 8.9 to 13.5 mm) and 16.0 ± 3.8 mm (95% CI, 13.3 to 18.7 mm), respectively, between the drill tip and the PIN. Aiming the drill 45° distally and aiming radially resulted in a distance of only 2.0 ± 2.2 mm (95% CI, 0.5 to 3.6 mm) and 4.2 ± 2.2 mm (95% CI, 2.6 to 5.8 mm), respectively. The differences were found to be statistically significant. CONCLUSIONS: On the basis of the results of this anatomic study, when using the cortical button distal biceps repair technique, we recommend drilling across the radius at 90° to its longitudinal axis and aiming from 0° to 30° ulnarly, with the patient's forearm in full supination. This provides an increased margin of safety to prevent injury to the PIN compared with drilling radially or distally. CLINICAL RELEVANCE: By avoiding distal and radial drilling, the risks of PIN injury should be minimized during distal biceps tendon repair.

Variations in the anatomic relations of the posterior interosseous nerve associated with proximal forearm trauma.

BACKGROUND: The posterior interosseous nerve is at risk for iatrogenic injury during surgery involving the proximal aspect of the radius. Anatomic relationships of this nerve in skeletally intact cadavers have been defined, but variations associated with osseous and soft-tissue trauma have not been examined. This study quantifies the effect of a simulated diaphyseal fracture of the proximal aspect of the radius and of a radial neck fracture with an Essex-Lopresti injury on the posterior interosseous nerve. METHODS: In twenty unembalmed cadaveric upper extremities, the distance from the radiocapitellar joint to the point where the posterior interosseous nerve crosses the midpoint of the axis of the radius (Thompson approach) was recorded in three forearm positions (supination, neutral, and pronation). Specimens were then treated with either proximal diaphyseal osteotomy (n = 10) or radial head excision with simulated Essex-Lopresti injury (n = 10), and the position of the nerve in each forearm position was remeasured. We evaluated the effect of the simulated trauma on nerve position and correlated baseline measurements with radial length. RESULTS: In neutral rotation, the posterior interosseous nerve crossed the radius at a mean of 4.2 cm (range, 2.5 to 6.2 cm) distal to the radiocapitellar joint. In pronation, the distance increased to 5.6 cm (range, 3.1 to 7.4 cm) (p < 0.01). Supination decreased that distance to 3.2 cm (range, 1.7 to 4.5 cm) (p < 0.01). Radial length correlated with each of these measurements (r > 0.50, p = 0.01). Diaphyseal osteotomy of the radius markedly decreased the effect of forearm rotation, as the change in nerve position from supination to pronation decreased from 2.13 ± 0.8 cm to 0.24 ± 0.2 cm (p = 0.001). Proximal migration of the radius following radial head excision was accompanied by similar magnitudes of proximal nerve migration in all forearm positions. CONCLUSIONS: Forearm pronation has minimal effect on posterior interosseous nerve position within the surgical window following a displaced diaphyseal osteotomy of the proximal aspect of the radius. The nerve migrates proximally toward the capitellum with proximal migration of the radius in all forearm positions following a simulated Essex-Lopresti lesion. Visualization and protection of the posterior interosseous nerve is recommended when operatively exposing the traumatized proximal aspect of the radius.

The risk injury to the posterior interosseous nerve in standard approaches to the proximal radius: a cadaver study.

PURPOSE: The aim of this study was to provide guidance on the safe zones for the exposure of the proximal radius by measuring the distance from the PIN to various anatomical landmarks in the proximal forearm in pronation and supination. METHODS: Twenty cadaveric arms were used for this study. On the anterior aspect of the forearm, the distance between insertion of the biceps tendon and the arcade of Frohse as well as the shortest distance between the PIN and the ulnar aspect of the radial neck were measured. On the posterior aspect of the forearm, the shortest distance between the PIN and the ulnar border of the interosseous membrane was measured at 30 and 50 mm distal to the articular surface of the radial head. RESULTS: The distance between the PIN and ulnar aspect of the radial neck had a mean of 21.6 mm in supination and 13.3 mm in pronation. The distance between the radial tuberosity and the arcade of Frohse was 18.6 mm. The mean distance between the PIN and the radial border of ulna at 30 mm distal to the articular surface of the proximal radius was 12.3 mm in supination and 22.3 mm in pronation. At 50 mm distal to the articular surface of the proximal radius the mean distance was 8 mm in supination and 16.2 mm in pronation. CONCLUSIONS: The course of this nerve is variable as it winds around the radial neck within the belly of the supinator muscle. Safe distances for dissection have been presented in our study.

[Posterior interosseous nerve palsy due to lipoma]. / Lipoma bagli posterior interosseöz sinir felci.

A 45-year-old male patient presented with paralysis of slow onset in the right forearm and hand muscles. Electromyographic assessment revealed severe denervation in the muscles innerved by the posterior interosseous nerve. Magnetic resonance imaging demonstrated a tumoral mass compressing the nerve. The patient underwent surgical excision with an initial diagnosis of lipoma. Surgical exploration and a biopsy confirmed the diagnosis. Active wrist movements and digital extension were possible after three weeks and the patient resumed full strength six weeks after the operation.

Superficial surgical landmarks for identifying the posterior interosseous nerve.

OBJECT: There is a paucity of information in the neurosurgical literature regarding the surgical anatomy surrounding the posterior interosseous nerve (PIN). The goal of the current study was to provide easily recognizable superficial bone landmarks for identification of the PIN. METHODS: Thirty-four cadaveric upper extremities obtained from adults were subjected to dissection of the PINs, and measurements were made between this nerve and surrounding superficial bone landmarks. In all specimens the main radial trunk was found to branch into its superficial branch and PIN at the level of the lateral epicondyle of the humerus. Proximally, the PIN was best identified following dissection between the brachioradialis and extensor carpi radialis longus and brevis muscles. At its exit site from the supinator muscle, the PIN was best identified after retraction between the extensor carpi radialis longus and brevis and extensor digitorum communis muscles. This site was a mean distance of 6 cm distal to the lateral epicondyle of the humerus. No compression of the PIN by the tendon of origin of the extensor carpi radialis brevis muscle was seen. One specimen was found to have a proximally split PIN that provided a previously undefined articular branch to the elbow joint. The mean diameter of the PIN proximal to the supinator muscle was 4.5 mm. The leash of Henry crossed the PIN in all but one specimen and was found at a mean distance of 5 cm inferior to the lateral epicondyle. The PIN exited the distal edge of the supinator muscle at a mean distance of 12 cm distal to the lateral epicondyle of the humerus. Here the mean diameter of the PIN was 4 mm. The exit site from the distal edge of the supinator was found to be at a mean distance of 18 cm proximal to the styloid process of the ulna. This exit site for the PIN was best identified following dissection between the extensor carpi radialis longus and brevis and extensor digitorum communis muscles. The distal articular branch of the PIN was found to have a mean length of 13 cm and the proximal portion of this terminal segment was located at a mean distance of 7.5 cm proximal to the Lister tubercle. CONCLUSIONS: The addition of more anatomical landmarks can help the neurosurgeon to be more precise in identifying the PIN and in avoiding complications during surgery in this region.

Posterior interosseous nerve injury complicating ulnar osteotomy for a missed Monteggia fracture.

We describe a 6-year-old boy with a posterior interosseous nerve injury after an ulnar osteotomy for a chronic Monteggia lesion. Although the first consultant did an ulnar osteotomy to reduce the radial head, the posterior interosseous nerve palsy did not recover. Next we found that the posterior interosseous nerve had been drawn into the radiocapitellar joint. It is important to confirm interposition of the nerve at the radiocapitellar joint during corrective osteotomy for a chronic Monteggia lesion.

Posterior interosseous nerve palsy due to parosteal lipoma.

Lipomas are extremely common benign soft tissue tumours that are usually subcutaneous and asymptomatic. Occasionally, lipomas can occur in deeper soft tissue planes and when adjacent to the neck of the radius they can cause compression of the posterior interosseous nerve. Five such cases are described. An anterior approach to excision of the lipoma is recommended.

Anatomical considerations regarding the posterior interosseous nerve during posterolateral approaches to the proximal part of the radius.

BACKGROUND: The purpose of our study was to quantify the dimensions of a surgically safe zone along the proximal part of the radius, from the posterolateral aspect. METHODS: The posterolateral approach between the anconeus and the extensor carpi ulnaris was performed in thirty-two cadaveric specimens, and the posterior interosseous nerve was exposed. Forearms were measured from the radial styloid process to the radiocapitellar joint. The distance from the capitellum to the point where the posterior interosseous nerve crossed the radial shaft and the angle between the nerve and the shaft were measured with forearms in pronation and supination. RESULTS: Pronation of the forearm allowed safe exposure of at least the proximal thirty-eight millimeters of the lateral aspect of the radius, with an average proximal safe zone of 52.0 +/- 7.8 millimeters. Supination decreased this proximal safe zone to as little as twenty-two millimeters and an average of 33.4 +/- 5.7 millimeters. The angle formed by the posterior interosseous nerve and the radial shaft in supination averaged 47.4 +/- 6.8 degrees; this decreased to 27.8 +/- 6.7 degrees with pronation. CONCLUSIONS: Approaching the lateral aspect of the proximal part of the radius is safest in pronation.

Safety of the limited open technique of bone-transfixing threaded-pin placement for external fixation of distal radial fractures: a cadaver study.

OBJECTIVE: To examine the safety of threaded-pin placement for fixation of distal radial fractures using a limited open approach. DESIGN: A cadaver study. METHODS: Four-millimetre Schanz threaded pins were inserted into the radius and 3-mm screw pins into the second metacarpal of 20 cadaver arms. Each threaded pin was inserted in the dorsoradial oblique plane through a limited open, 5- to 10-mm longitudinal incision. Open exploration of the threaded-pin sites was then carried out. OUTCOME MEASURES: Injury to nerves, muscles and tendons and the proximity of these structures to the threaded pins. RESULTS: There were no injuries to the extensor tendons, superficial radial or lateral antebrachial nerves of the forearm, or to the soft tissues overlying the metacarpal. The lateral antebrachial nerve was the closest nerve to the radial pins and a branch of the superficial radial nerve was closest to the metacarpal pins. The superficial radial nerve was not close to the radial pins. CONCLUSION: Limited open threaded-pin fixation of distal radial fractures in the dorsolateral plane appears to be safe.

Denervation of the radiocarpal joint. A follow-up study in 22 patients.

Denervation surgery has been a mainstay of our management of chronic pain in the wrist. If there is useful movement at the wrist we prefer denervation to arthrodesis. We have reviewed 22 patients at a mean of 50 months after such denervation surgery at the wrist. This was the only treatment in 16 patients; the other six also had other treatments. Pain was reduced in 16 patients, and 17 were satisfied or improved. None of the patients wished to have a supplementary arthrodesis. We stress the importance of preoperative blockade tests and of a very detailed knowledge of the local anatomy.