[Plate Osteosynthesis of Distal Ulna Fractures with Associated Distal Radius Fractures Treated by Open Reduction and Internal Fixation. Short-Term Functional and Radiographic Results].

PURPOSE OF THE STUDY: The aim of the study was to describe the indication criteria and operative technique and to present the first conclusions of a prospective study dealing with an assessment of functional and radiographic findings in patients with concurrent fractures of the distal ulna and distal radius; the former was treated by osteosynthesis using an LCP Distal Ulna Plate (De Puy Synthes, USA) and the latter by plate osteosynthesis.

MATERIAL AND METHODS: Between August 2013 and September 2014, 18 patients (3 men and 15 women; average age, 58 years; range, 25-74 years) with a fracture of the distal ulna and a concurrent distal radius fracture were treated by plate osteosynthesis. The indications for surgery included displaced ulnar styloid base fractures in 10 patients, displaced comminuted fractures of the ulnar head in seven patients and a subcapital fracture of the ulna in one patient. The average follow-up was 9 months, with 13 (72%) patients being followed up for 6 months at least. The outcome of surgery was evaluated on the basis of X-ray views and multiplanar reconstruction of CT scans. Functional results were based on measuring the range of motion at wrist and forearm and hand grip strength and on the scores obtained from the Mayo Wrist Score System and Quick DASH Questionnaire.

RESULTS: The average values for wrist and forearm range of motion were as follows: 68° in flexion (60-80°), 71° in extension (40- 90°), 87° in pronation (70-90°), 81° in supination (50-90°). This corresponded to a 92% (74-100%) range of motion at the contralateral wrist and forearm. The average hand grip strength measured with a dynamometer was 80.6% (53-100%) of the gripping force exerted by the unaffected extremity. Post-operative X-ray and CT findings showed good reduction of both distal radius and distal ulna fractures as well as good fragment retention by means of LCP implants. During follow-up complete bone union and full stability of the radioulnar joint were achieved in all patients. The functional outcome of treatment was shown by the average Mayo wrist score and Quick DASH score of 84 (55-100) and 7.4 (0-47.7) points, respectively.

DISCUSSION: The functional outcome of treatment in our patients corresponded to the severity of their distal forearm fractures. The patients with more serious distal radius fractures, frequently associated with ulnar head fractures, had poorer functional results than the patients with less serious fractures. According to the AO classification, in the distal radius fractures, prevailing fracture types were 23-C3 (78%) and 23-C2 (16%). In relation to the distal ulna fracture type, the patients with ulnar styloid base fractures had better functional results than the patients with ulnar head fractures, because a fracture of the styloid process does not affect the congruency of the distal radioulnar joint (DRUJ). Fractures of the ulnar styloid process base, following distal radius fracture osteosynthesis, were invariably associated with DRUJ instability. This fracture type is always accompanied by injury to the distal radioulnar ligament of the triangular fibrocartilage complex (TFCC) and, in case of a displaced fracture, surgical management is indicated. In agreement with the results of other authors it was found in our study that, when the anatomical position of the distal radioulnar joint had been achieved, both the functional and the radiographic findings were post-operatively very good. The final average values for the range of wrist and forearm motion, hand grip strength and hand and arm function were assessed as very good. CONCLUSIONS The assessment of our results and their comparison with the literature data showed that osteosynthesis of distal ulna fractures with concurrent distal radius fractures managed by open reduction and internal fixation are indicated in displaced fractures of the ulnar styloid process base, displaced comminuted fractures of the ulnar head where fragments interfere with DRUJ congruency, and unstable displaced subcapital fractures of the ulna. The early results of this study provide evidence for the efficiency of plate osteosynthesis in the treatment of distal ulna fractures.