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Early complications associated with the Thompson approach to the proximal radius.

Forearm fractures in adults are common injuries that benefit from open reduction and internal fixation. The radius can be accessed by both and volar and dorsal approaches. The ulna is often accessed by a direct approach. (1) For most radius shaft fractures, the volar (Henry) approach is usually favored. In the case of fractures of the proximal one-third of the radius, some surgeons choose to use the dorsal (Thompson) approach to avoid placing hardware over the bicipital tuberosity, although the volar approach can be used for these fractures as well. An additional advantage of the Thompson approach is the superficial location of the radius; consequently, the surgeon avoids working in a deep recess and does not need to dissect around radial recurrent vessels. (1) However, the posterior interosseous nerve (PIN) can be easily injured from the Thompson approach due to its intimate relationship with the supinator overlying the radius.

There is a paucity of literature describing the potential complications of the dorsal approach to the radius. A recent study compared the volar and dorsal approaches to the radius in 70 patients in a non-randomized fashion. (2) The investigators found similar union and complication rates between both approaches. Notably, the nerve injury rate was 7.7% in the volar approach and 6.5% in the dorsal approach. The reported nerve injuries in the dorsal approach were to the radial nerve. The aim of this case series is to document our experience with acute complications of the dorsal Thompson approach, specifically with regard to injuries to the posterior interosseous nerve.

Radial Nerve Anatomy

The radial nerve originates as a branch of the posterior cord of the brachial plexus. It then travels through the triangular interval in the upper arm. The borders of the triangular interval are the teres major superiorly and the long and lateral heads of the triceps medially and laterally. It then courses around the posterior aspect of the humerus in the spiral groove before perforating the lateral intermuscular septum. Carlan and coworkers found that the radial nerve is in contact with the posterior aspect of the humerus from 17.1 cm to 10.9 cm proximal to the lateral epicondyle before becoming lateral to the humeral shaft and piercing the lateral intermuscular septum, entering the anterior compartment of the brachium. (3) It can then be identified in the interval between the brachioradialis and the brachialis muscles.

The course of the posterior interosseous nerve in the proximal forearm and its muscular innervations have been the subject of cadaveric studies. (4) Abrams found variable innervation of the forearm mobile wad and extensor compartment muscles, but the most common pattern found was radial nerve innervation of the brachioradialis and extensor carpi radialis longus. The extensor carpi radialis brevis did not have a reliable motor branch with variations in innervation by the radial nerve, PIN, and superficial radial nerve.

The bifurcation point of the sensory (superficial radial) and motor (PIN) branches of the radial nerve occurred on average 10.3 mm proximal to the lateral epicondyle. The PIN then enters the supinator muscle and exits on average 7.0 cm from the radiocapitellar joint, at which point it provides branches to extensor digitorum communis (EDC), extensor digiti mimimi (EDM), and extensor carpi ulnaris (ECU). (5) Innervation to the extensor pollicis longus (EPL), extensor digiti minimi (EDM), extensor pollicis brevis (EPB), and extensor indicis proprius (EIP) follows as the PIN gives off its most distal motor branch on average 11.5 cm proximal to the radial styloid. (4) The PIN then travels in the floor of the fourth dorsal compartment through the distal forearm and provides a proprioceptive branch to the wrist capsule. The superficial radial nerve emerges from the brachioradialis approximately 8 cm proximal to the radial styloid and then divides distally to provide sensation to the dorsal-radial aspect of the hand.

Materials and Methods

A retrospective chart review was performed on operatively treated forearm fractures at our institution. Over a period from January 2008 to May 2014 a total of 120 patients underwent open reduction and internal fixation for radius shaft fractures either isolated or associated with ulna fractures. Eleven were found to have utilized the Thompson approach to the proximal radius. No volar approaches were undertaken for proximal one-third fractures of the radius. At our institution, the dorsal approach is used for radius shaft fractures in which it would not be possible to obtain adequate fixation from the volar approach, which is usually considered to be at least three bicortical screws using a dynamic low contact small fragment plate (Fig. 1). The stated indication for the dorsal approach was a proximal location of the radius fracture in 10 cases and presence of dorsal open wounds in one patient (patient seven). Demographic data was collected and the fractures were classified based on the Orthopaedic Trauma Association (OTA) classification system. Complications occurring in the first 2 weeks after surgery were recorded. The mean follow-up time was 15 weeks (range: 1 to 52 weeks).

A dorsal approach to the proximal radius was used in all of our cases. A cadaveric dissection is used here to illustrate the exposure. The proximal landmark of the skin incision was the lateral epicondyle and extended distally toward Lister's tubercle (Fig. 2). The superficial interval between the extensor carpi radialis brevis and the extensor digitorum communis was incised and the supinator muscle belly was exposed (Figs. 3 through 5). Blunt dissection through the supinator was performed and the posterior interosseous nerve was visualized along with the radial shaft (Figs 5 and 6). The posterior interosseous nerve was visualized and protected in all of our cases. The forearm was pronated during reduction and fixation to bring the nerve distally and radially. There were no noted intraoperative injuries to the nerve, and 3.5 mm limited contact dynamic compression plates (LC-DCP) were applied to the dorsal aspect of the radius. Fixation of the ulna was performed as indicated.

Results

The average age of the patients was 31 years (range: 20 to 46 years). Ten patients were male and one was female. All patients had intact radial nerve function prior to surgery. The average distance from the fracture to the radial head articular surface was 72 mm (range: 34 mm to 132 mm) and 41 mm (range: 3 mm to 100 mm) from the bicipital tuberosity. Four fractures were open, and seven were closed injuries. In five cases, there was no fracture of the ulna. Injury mechanism and fracture classification are listed in Table 1. Postoperatively, two (18%) postoperative posterior interosseous nerve palsies were identified. There was one postoperative compartment syndrome requiring fasciotomy. There were no wound complications. There was an overall early complication rate of 27%. Patient one was contacted by phone 3 months after surgery and stated that he recovered digital extension. We were unable to contact patient four for follow-up.

Discussion

Our study found an 18% rate of posterior interosseous nerve palsy after open reduction and internal fixation of the proximal radius despite identification and protection of the nerve in all cases. Patient one's PIN palsy resolved 3 months after surgery, characteristic of neuropraxia caused by a neural lesion. We were unable to obtain follow up for patient four, but likely both of these cases represent traction injuries to the nerve. Our rate is higher than the 6.5% noted by Mehdi and colleagues, (2) albeit with lower sample size. As noted by Abrams and associates, (4) the PIN exits the supinator muscle on average 7.0 cm from the radiocapitellar joint, making it especially vulnerable to injury at all points proximal to this. (4) Our one case of compartment syndrome notably was in a patient who had previous radius fixation using a volar approach. The scarred soft tissue envelope may have contributed to this complication.

Nigro and associates reported nine cases of traction injuries to the PIN after distal biceps repair, and noted an average recovery time of 86 days, with all patients recovering within 5 months. (6) Nasab and coworkers reported two cases of radial nerve palsy after the dorsal approach with one patient making a recovery and the second patient having persistent injury for 4 months postoperatively. (2) Observation is recommended for at least 3 months for PIN paralysis. If no recovery is seen at 3 months, we recommend electrodiagnostic studies. If the electrodiagnostic studies suggest that the nerve is in continuity, we recommend continued observation for at least 5 months prior to neurolysis and tendon transfers.

One unanswered question is whether the closure of the fascia overlying the extensor carpi radialis brevis (ECRB) and extensor digitorum communis is truly necessary or advisable. The closure may improve soft tissue healing, although it may increase dorsal compartmental pressure. Given that this interval is often incised in fasciotomies of the dorsal compartment of the forearm, future studies could examine the effectiveness of this release for reducing nerve injury and compartment syndrome associated with the dorsal Thompson approach. (7)

It is important to perform a thorough physical exam both preoperatively and postoperatively when operating on proximal forearm fractures to identify nerve deficits. In the case of PIN palsy, active wrist extension may cause wrist radial deviation due to unopposed function of the ECRB. However, this is not reliable due to the variable innervation of this muscle. Another way it can be identified is a thumb interphalangeal extension deficit since the PIN reliably innervates the EPL. EDC function can also be tested with active extension at the finger metacarpophalangeal joints with the proximal and distal interphalangeal joints flexed. Posterior interosseous nerve palsy can be easily missed due to ulnar nerve innervated intrinsic muscle extension of the finger proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints.

This study has several limitations. Principal among them is the short, average follow-up time and small sample size. The lack of follow up may be related to our institution being an urban public hospital. The main purpose of our study was to describe this uncommon approach and its attendant acute complications. The small sample size is a result of the volar approach being preferred for the majority of radial shaft fractures. However, the relatively high rate of acute PIN injury, despite identification and protection during, surgery is an important finding. Given the limited literature about the dorsal approach to the proximal radius, our hope is to provide further experience and insight with this surgical approach, particularly with respect to complications.

Disclosure Statement

None of the authors have a financial or proprietary interest in the subject matter or materials discussed, including, but not limited to, employment, consultancies, stock ownership, honoraria, and paid expert testimony.

References

(1.) Catalano LW 3rd, Zlotolow DA, Hitchcock PB, et al. Surgical exposures of the radius and ulna. J Am Acad Orthop Surg. 2011 Jul; 19(7):430-8.

(2.) Mehdi Nasab SA, Sarrafan N, Fakoor M, Mohammadzadeh M. Comparison of volar and dorsal approaches for surgical treatment in fracture of proximal half of the radius. Pak J Med Sci. 2013 Apr; 29(2):532-5.

(3.) Carlan D, Pratt J, Patterson JM, et al. The radial nerve in the brachium: an anatomic study in human cadavers. J Hand Surg Am. 2007 Oct; 32(8):1177-82.

(4.) Abrams RA, Ziets RJ, Lieber RL, Botte MJ. Anatomy of the radial nerve motor branches in the forearm. J Hand Surg Am. 1997 Mar; 22(2):232-7.

(5.) Spinner RJ, Berger RA, Carmichael SW, et al. Isolated paralysis of the extensor digitorum communis associated with the posterior (Thompson) approach to the proximal radius. J Hand Surg Am. 1998 Jan; 23(1):135-41.

(6.) Nigro PT, Cain R, Mighell MA. Prognosis for recovery of posterior interosseous nerve palsy after distal biceps repair. J Shoulder Elbow Surg. 2013 Jan; 22(1):70-3.

(7.) Ronel DN, Mtui E, Nolan WB 3rd. Forearm compartment syndrome: anatomical analysis of surgical approaches to the deep space. Plast Reconstr Surg. 2004 Sep 1; 114(3):697-705.

Donato J. Perretta, M.D., Kenneth M. Brock, B.S., and Nirmal C. Tejwani, M.D., Department of Orthopaedic Surgery, NYU Hospital for Joint Diseases, New York, New York.

Correspondence: Donato J. Perretta, M.D., Department of Orthopaedic Surgery, Hospital for Joint Diseases, 301 East 17th Street, New York, New York 10003; dperretta@gmail.com.

Caption: Figure 1 A 35-year-old male sustained this proximal radius fracture during a soccer game. A dorsal approach was performed, and dorsal plate was applied. No instability was noted at the distal radio-ulnar joint. Postoperatively, he was noted to have a PIN palsy.

Caption: Figure 2 Landmarks for skin incision. To view this figure in color, see www.hjdbulletin.org.

Caption: Figure 3 Superficial exposure. To view this figure in color, see www.hjdbulletin.org.

Caption: Figure 4 Exposure of fascia overlying supinator muscle. To view this figure in color, see www.hjdbuhetin.org.

Caption: Figure 5 Identification of the posterior interosseous nerve with radial shaft. To view this figure in color, see www.hjdbuhetin.org.

Caption: Figure 6 Identification of the posterior interosseous nerve with radial shaft with ruler. To view this figure in color, see www. hjdbulletin.org.

Table 1 Summary of Identified Cases Using Dorsal (Thompson) Approach
to the Proximal Radius; PIN, Posterior Interosseous Nerve

     Age/Sex   Mechanism           Fracture Pattern (OTA)

1    35M *     Soccer injury       Proximal radius fracture (22-A2)

2    38M       8-foot fall         Proximal radius and ulna fracture
                                   after prior both bones forearm open
                                   reduction and internal fixation
                                   (22-A3)

3    22M       Fall from bicycle   Proximal radius and ulna fracture
                                   (22-A3)

4    27M       Snowboarding        Proximal radius fracture (22-A2)

5    52M       Fall from bicycle   Elbow dislocation, coronoid
                                   fracture, proximal radius fracture,
                                   midshaft ulna (20-A2), (22-B3)

6    24M       Gunshot wound       Proximal radius fracture (22-C2)

7    20M       60-foot fall        Proximal radius and ulna fracture
                                   (22-B3)

8    46F       Lifting purse       Proximal radius and ulna fracture
                                   after prior radial shaft open
                                   reduction and internal fixation
                                   (22-A3)

9    34M       5-foot fall         Proximal radius and ulna fracture
                                   (22-B3)

10   19M       Motorcycle fall     Proximal radius fracture (22-A2)

11   25M       Soccer              Proximal radius fracture (22-A2)

     Fracture
     to Radial   Open vs.
     Head (mm)   Closed     Complication

1      78.7      Closed     PIN palsy

2      70.3      Open       Compartment
                            syndrome

3      81.0      Closed     None

4      74.0      Closed     PIN palsy

5      58.0      Open       None

6      34.0      Open       None

7      132.0     Open       None

8      47.5      Closed     None

9      66.0      Closed     None

10     81.0      Closed     None

11     72.4      Closed     None

* See Figure 1.


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Author:Perretta, Donato J.; Brock, Kenneth M.; Tejwani, Nirmal C.
Publication:Bulletin of the NYU Hospital for Joint Diseases
Date:Oct 1, 2016
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