Minimally invasive plate osteosynthesis for distal radius fractures.

BACKGROUND: Fractures of distal radius are common injury in all age groups. Cast treatment with or without close reduction is a viable option. However, the results are often unsatisfactory with restricted function. The open reduction and internal fixation often results in extensive soft tissue dissection and associated high rates of infect and delayed/nonunion. The distractor/external fixator have reported good functional and anatomical results but the incidence of pin traction infection nerve injury and cosmedic deformity are high. We introduced a modified operative technique for minimally invasive plate osteosynthesis (MIPO) for distal radial fracture and evaluated the functional outcomes and complications.
MATERIALS AND METHODS: 22 distal radial fractures (10 left, 12 right) were treated using the MIPO technique and two small incisions with a palmar locking plate from August 2009 to August 2010. The wrist function was assessed according to Dienst wrist rating system, and postoperative complications were recorded.
RESULTS: According to Dienst wrist rating system, 13 patients showed excellent results, 6 cases showed good results and 3 patients had moderate results. No patient had poor results. Thus, the excellent and good rate was 86.4%. One patient had anesthesia in the thenar eminence and this symptom disappeared after 3 months. One patient had delayed healing in the proximal wrist crease. Two patients had mild pain on the ulnar side of the wrist and two patients had limited wrist joint function.
CONCLUSION: The MIPO technique by using two small palmar incisions is safe and effective for treatment of distal radial fractures.

INTRODUCTION

Distal radius fracture is a common injury in all age groups. However, there are several controversies in the operative indication, surgical approach and the best treatment method. The gold standard in the treatment of distal radius fracture remains uncertain.1 Cast treatment with or without closed reduction has long been considered a viable option for treatment of distal radius fractures. However, the results are often unsatisfactory with restricted function and disabilities.23 Several studies have reported good anatomical and functional results of distal radius fractures treated with external fixation but also described high incidence of pin tract infection, cosmetic deformity, and nerve injury.4 Traditional open reduction and internal fixation often results in extensive soft tissue dissection and periosteal injury and may be associated with high rates of infection, delayed union and nonunion.45

Fortunately, the technique of minimally invasive plate osteosynthesis (MIPO) recently emerged and this technique can minimize soft tissue stripping and damage to the vascularity of the bone.6 It can lead to a reduction in complications caused by conventional treatment. MIPO has been widely used in the treatment of the femoral and tibial fractures.78 More recently its use has also been expanded for the fixation of upper extremity fractures.9101112 In 2005, Imatani et al.13 first reported that five patients of distal radius metaphysis comminuted fracture were treated by MIPO in which reduction and internal fixation was completed by two longitudinal incisions (3 cm) on the palmar side of distal forearm. Inspired by the report, we designed two kinds of incisions (2 cm) according to the distance between the main fracture line and the wrist for further minimizing soft tissue related complications, such as tendon injury, nerve dysfunction, and vascular compromises.14 Besides, mini-incision can offer better cosmetic results.1516 Plate fixation of distal radius fractures usually involves two kinds of incisions: Palmar and dorsal. The palmar approach has been demonstrated to be more superior because it can avoid the complications caused by the attrition of the extensor tendon in the dorsal approach.171819 In addition, the cortex on the palmar side of distal radius is wide and flat which benefits the exposure of fracture fragments and placement of the plate, especially for a die-punch type of fracture. Importantly, the operative scar of the wrist is not very obvious, leading to an excellent appearance.20 A palmar locking plate has superior biomechanics compared with traditional dorsal locking plate.21

We reviewed our experience in treating distal radius fractures using the palmar locking plate and two kinds of incisions in the MIPO technique, in order to assess the functional outcome and complications following this method.

MATERIALS AND METHODS

22 patients with distal radial fractures (10 left, 12 right) were treated by the modified MIPO technique with a T-shaped palmar locking plate. An informed consent was taken from the patients and the approval of the ethics committee of Hand Surgery Hospital was obtained.

We used the AO/ASIF classification of distal radius fracture using plain radiographs. Our indications for using MIPO were type A2, type A3, type B1, type B3, type C1 and type C2 distal radial fractures. Patients with type A1, B2 or C3 of distal radius fracture were not included in this study.

Operative procedure

Patient was placed on a conventional table in the supine position under brachial plexus block. Manual reduction was performed under fluoroscopy. Once a satisfactory reduction was achieved, one or two 1.5 mm kirschner wires were obliquely inserted from the styloid process of radius to the proximal ulnar side to maintain the reduction, sometimes the kirschner wires were inserted from the opposite direction as well. It is necessary to add another K wire, parallel to the articular surfaces of the distal radius for a type C fracture. The two skin incisions of 2 cm each were made [Figure 1]. For patients with a distance between the main fracture surface and articular surface of distal radius within 1 cm, distal skin incision was made along the proximal wrist crease. If this distance was more than 1 cm, distal skin incision was made on the radial side along the proximal wrist crease, parallel to flexor carpi radialis. After cutting the superficial and deep fascia on the radial side of flexor carpi radialis, the flexor carpi radialis and the radial artery were retracted to the radial or ulnar side respectively. Then the flexor pollicis longus was retracted to the ulnar side to expose the pronator quadratus. A longitudinal incision was made at the middle of distal partial pronator. This incision was not needed for patients with incomplete injury to the pronator quadratus. For a few patients with unsatisfied closed reduction, the incision should be made on the fracture end to help reduction under direct vision. A suitable, oblique, T-shaped palmar locking plate was inserted through the incision extraperiosteally. After satisfactory fracture reduction and fixation of the plate, a 2 cm proximal skin incision was made on the radial side of the flexor carpi radialis. The superficial and deep fascia was cut to retract the radial artery and the flexor pollicis longus was dissected using forceps to expose the proximal end of the locking plate. The incisions were closed in layers [Figure 2].

Figure 1

Preoperative clinical photographs showing (a) One horizontal and one vertical incision. (b) Two vertical incisions.

Figure 2

Intraoperative clinical photographs showing (a) One horizontal and one vertical incision were made at the palmar side. (b) The locking screws were inserted to fix the plate.(c) Intraoperative X-ray showed the reduction of the fracture on the lateral and anteroposterior view

Plaster splints were not applied to any patient postoperatively. We encouraged the patients to exercise their shoulders, elbows, metacarpophalangeal joints, interphalangeal joints 2 or 3 days after operation. Patients were advised to perform extension and flexion movement of the affected wrist joints after 3-5 days post surgery. Two weeks postoperatively, active rotational exercises for forearm were also added. The patients were followed up every 2 months [Figure 3].

Figure 3

Postoperative X-rays (a) anteroposterior (b) lateral views at 2 months followup demonstrating a healed distal radius fracture

RESULTS

The average age of the patients was 65 years (range 37-80 years). There were 7 males and 15 females. The mean time from injury to surgery was 7 days (range 0.5 hour-10 days). They were all closed fracture and were classified according to AO/ASIF system, including type A2 (n=5), type A3 (n=3), type B1 (n=4), type B3 (n=7), type C1 (n=2), and type C2 (n=1). All 22 patients were followed up for an average time of 12 months (range, 10-18 months). According to wrist function evaluation criteria described by Dienst et al.,22 13 patients obtained excellent results, six cases had good results and three patients had moderate results. None of the patients had poor results [Figure 4]. Thus, excellent and good results were seen in 86.4%. One patient had anesthesia in the thenar eminence and this symptom disappeared after 3 months. One patient had delayed healing in the proximal wrist crease. Two patients had mild pain on the ulnar side of the wrist. Two patients had limited wrist joint function.

Figure 4

Postoperative clinical photographs showing functional results. The extension and flexion of the wrist and the supination and pronation of the forearm were all good

DISCUSSION

MIPO has become popular in the treatment of fractures due to satisfactory clinical outcomes. Since the first MIPO techniques were developed for subtrochanteric and distal femoral fractures, these methods were modified and adapted for use in other fracture types as well, including the distal tibia,2324 humeral shaft925 and the foot.26 In this study, we adopted a modified MIPO technique that used a palmar locking plate through two small incisions to treat distal radial fractures. Incision length was determined according to the distance between the main fracture line and the articular surface of distal radius.

A prospective, randomized study analyzed 90 patients with displaced intraarticular distal radius fractures with an average of 4-year followup to evaluate the functional outcomes of three modes of treatment (plaster immobilization, external fixation, and open reduction with internal fixation). Good or excellent results were achieved in 43%, 80%, and 63% in each group, respectively.4 Similarly, another prospective, randomized study reported that good or excellent outcomes of conventional closed reduction and immobilization with or without Norian SRS (Skeletal Repair System) cement in the management of intra or extraarticular distal radial fractures were 45%.27 It appears that the functional outcome was similar when compared our results with that using external fixation. However, patients undergoing external fixation are at high risk for infection. Pin tract infection was the major complication of external fixation of fractures and the rates of infection ranged from 0.5% to 30%.28 Some bacteria, usually Staphylococcus aureus and Staphylococcus epidermidis, often colonized at the site of external fixation pins28 that resulted in these infection. In our study, there were no infections. Conventional closed reduction using only simple plaster cast immobilization is insufficient to maintain the reduction and Cherubino et al. observed a secondary loss of reduction during plaster cast immobilization in 35% of cases.2 A traditional open surgical approach may increase the risk of nonunion, delayed healing and infection due to extensive soft tissue stripping.30 In addition, the complication of nerve injuries are commonly reported after operative treatment of distal radius fractures. The incidence has been estimated from 0% to 17%, with the median nerve being the most commonly injured followed by the radial and ulnar nerves.31 However, in present study, no damage of radial artery and median nerve occurred in all 22 patients postoperatively since our longitudinal incisions were usually along the radial side of the flexor carpi radialis and our surgery was performed strictly in the safety window area to avoid accidental injury.32 Besides, the radial artery and median nerve were not exposed during the operation in current study 27% cases developed complications in our study including anesthesia (4.5%), delayed healing (4.5%), pain (9%) and limited extension and rotation (9%) 27% complication rate associated with MIPO used in our study for various types of fractures shows that this method is not suitable for all distal radius fractures. A specific treatment method and selection of individuals will certainly reduce the number of complications.

The limitations of this study include the small sample size, the short followup time, and the absence of a control group.

In conclusion, two small incisions to implant a palmar locking plate by MIPO for distal radius fractures give good functional results. But further research also should be carried out to explore more suitable treatment for specific individuals. 33