6 Is There a Role for External Fixation with or without Kirschner Wires?

10.1055/b-0039-169246

6 Is There a Role for External Fixation with or without Kirschner Wires?

Frédéric Schuind

Abstract

The best indication of distal radius external fixation is the highly comminuted fracture, operated shortly after the accident. Other good indications are open, contaminated distal radius fracture and the unstable polytrauma patient (“damage control” principle). Volar marginal Barton-type fractures are better treated by plate. Radiometacarpal external fixation, with pins inserted in the radius and second metacarpal diaphyses and half-frame fixation, relies on transarticular distraction to reduce the fracture and to maintain its reduction. An excellent or good reduction is obtained in 93.5% of the cases, though minor bone settling frequently occurs. Sometimes a step-off is observed on postoperative CT scan, justifying the subsequent implantation of a volar plate, keeping the fixator for length and alignment of the radius. The main drawback of external fixation is the bone and skin reactions to the percutaneous pins. The recovery of function is slower than after plate fixation, but, after 1 year, the functional results are equivalent. Overall, there are less major complications after external fixation, there is no volar scar, and no necessity to remove an internal implant.

6.1 Introduction

The traditional care of distal radius fractures is closed reduction and cast immobilization. In unstable fractures, this treatment leads to an unacceptable rate of secondary displacement, up to 60%. ¹ According to Lafontaine et al, ² the factors of instability include dorsal tilt > 20°, dorsal comminution, intra-articular radiocarpal involvement, associated fracture of the ulna, and age over 60. In subsequent studies, age has been reported to be the main factor of instability. ³ ^, ⁴ Most unstable fractures are, therefore, nowadays operated in an effort to prevent symptomatic malunion. During many years, external fixation has been considered the technique of choice, but for the last 15 years, locked volar plate has become the standard. External fixation has fallen out of favor because of significant drawbacks, including the risk of infection at pin sites, postoperative complex regional pain syndrome (CRPS), poor tolerance of the external frame by the patients, and the higher risk of redisplacement. Some of these criticisms are well established (infections at pin–skin sites); others are more beliefs than facts, as demonstrated in comparative studies and meta-analyses. ⁵ ^, ⁶ ^, ⁷ ^, ⁸ ^, ⁹ ^, ¹⁰ ^, ¹¹ ^, ¹² ^, ¹³ ^, ¹⁴ ^, ¹⁵ ^, ¹⁶ ^, ¹⁷ ^, ¹⁸ ^, ¹⁹ ^, ²⁰ In fact, there is no clear evidence that locked plate fixation is a better technique. The initial functional results are better after plate fixation, but after 1 year, there is almost no difference; the rate of reoperation is higher after plate fixation, mainly for tendon complications—not seen after external fixation. Considering not only the functional results but also the rate and seriousness of their complications, neither external fixation nor palmar plating has demonstrated an obvious benefit over nonoperative methods or simple pinning techniques, especially in geriatric patients. ²¹ ^, ²² ^, ²³ ^, ²⁴ ^, ²⁵ ^, ²⁶

6.2 Indications and Contraindications

External fixation can be used to treat most distal radius fractures. In our opinion, the best indication is the highly comminuted fracture, operated immediately after the accident (▶Fig. 6.1). Of course, external fixation is the technique of choice in the infrequent open, contaminated distal radius fracture (▶Fig. 6.2), and in the unstable polytrauma patient, following the principle of “damage control.” ²⁷ Relative indications also include the patient unwilling to undergo open reduction and internal fixation of his/her distal radius fracture, and the rare cases of general (allergy to metals and coagulation problems—an external fixator can be implanted without discontinuing anticoagulant therapy) or local contraindications to open surgery and plate fixation. External fixation is not a good technique to fix volar marginal Barton-type fractures, better treated by a volar plate, nor pediatric distal radius fractures, where pinning remains the golden standard. Another relative contraindication to external fixation is the severely immunocompromised patient when pin infection may represent a serious risk. Some patients also refuse an external frame, a rare situation in our experience.

**Fig. 6.1** **(a, b)** Comminuted distal radius fracture treated by distraction bridging radiometacarpal external fixation.

**Fig. 6.2** A 70-year-old woman transferred from Africa after traditional treatment of an open forearm and distal radius fracture. Obvious contraindication to internal fixation techniques.

6.3 Surgical Techniques

External fixation is a “keep it simple and safe” method. The classical technique is the implantation of pins in the diaphysis of the radius and of the second (or sometimes third) metacarpal bone (“radiometacarpal external fixation”), “bridging” the wrist joints. ²⁸ ^, ²⁹ ^, ³⁰ The method relies on transarticular distraction to reduce the fracture and to maintain its reduction. It is usually assumed that the fracture fragments are pulled in place by the intact ligaments (“ligamentotaxis”). ³¹ Having observed that transarticular distraction also allows to reduce fragments devoid of ligament insertion, we have suggested another explanation of the mechanism of reduction, a decrease of the intra-articular pressure during distraction with a suction effect on the small articular fragments. ³² This mechanism can occur only in very recent fractures. The fixator is, therefore, ideally applied within 72 hours of the fracture; after this delay, it is more difficult to obtain by simple reduction, a good reduction of an articular fracture. Radiometacarpal external fixation can be implanted using different types of mountings. At our university clinic, we have chosen the Stryker Trauma Hoffmann II device. Two 3-mm Apex pins are implanted in the middle third of the radius and two identical pins in the diaphysis of the second metacarpal bone. A simple half-frame is then constructed, allowing maintenance of the position of closed reduction of the fracture, which is usually obtained by axial traction, and some palmar flexion and ulnar inclination (▶Fig. 6.1, ▶Fig. 6.3). If necessary, additional Kirschner wires (K-wires) are pinned in epiphyseal fragments, if the reduction obtained by distraction is not sufficient or to provide additional stability ³³ ^, ³⁴ (▶Fig. 6.4). We never open the fracture to insert a bone graft or a bone substitute. ³⁵ Control imaging is obtained after the operation. About 3 weeks later, the external fixation rod is unlocked and the wrist straightened to a neutral position, releasing the transarticular distraction. The relocked fixator remains in place for another 3 to 4 weeks, before removal of the pins at the outpatient clinic or in day surgery. Physiotherapy is then instituted, if not already started during fixator time until good motion of wrist and fingers is recovered.

**Fig. 6.3** A 44-year-old gentleman victim of a high-energy fall on his left wrist. Markedly displaced extra-articular fracture of his distal radius with associated fracture of the ulnar styloid (Frykman VI **[a, b]**). Acute dysesthesias in median nerve dermatoma. Emergency reduction and radiometacarpal external fixation **(c, d)**. Rapid disappearance of all neurologic symptoms without carpal tunnel decompression. Removal of the fixator after 6 weeks. At 6 months, the patient has no pain and has recovered almost full wrist joint amplitudes and 89% grasping strength, as compared to the right dominant side. Note however on the X-rays done after removal of the fixator at 3 months **(e, f)**, some shortening of the radius causing a positive ulnar variance. This bone settling, not present on the immediate postoperative radiograms **(c, d)**, could possibly have been prevented by additional Kirschner-wire (K-wire) fixation.

**Fig. 6.4** **(a, b)** An 83-year-old osteoporotic woman victim of a low-energy closed Frykman IV fracture of her right distal radius. Osteosynthesis by radiometacarpal external fixation with additional Kirschner wires (K-wires). Good function after fracture healing, though the K-wires did not prevent some radius shortening at final follow-up. The wires could have been folded at their extremity to prevent migration.

Beside this classical method of external fixation, other techniques are available. We do not use dynamic external fixation that could promote earlier recovery of wrist function with the risk of loss of fracture reduction. ³⁶ ^, ³⁷ Some authors use external fixation as a neutralizing osteosynthesis, after closed or arthroscopic reduction and pinning of the bone fragments: this method has been named “augmented external fixation.” ³⁴ McQueen has popularized radioradial external fixation to treat simple extra-articular fractures. ³⁸ Pins are then implanted only in the radius, a first group in the distal diaphysis, proximal to the fracture line, and the second group in the distal radius epiphysis, distally to the fracture. The reduction is obtained by direct manipulation of the fracture fragments. Hoel and Liverneaux recently proposed another external fixation method using K-wires directly implanted in the fracture fragments, fixed by an external connector (HK2 technique). ³⁹