[Intramedullary pinning of diaphyseal fractures of both forearm bones in adults: 46 cases].

PURPOSE OF THE STUDY: The goal when treating shaft fractures of the forearm bones is to obtain good bone healing with good preservation of upper limb function. We report a retrospective (1995-2004) consecutive series of patients aged 32 years on average (range 16 to 92 years) who presented 46 shaft fractures of both forearm bones.

MATERIAL AND METHODS: Using Hackethal's classification by sixths, the fracture involved the 3rd and 4th sixth in 39 cases (84.7%) for the radius and 33 (71.7%) for the ulna. Seventeen (37%) patients were trauma victims with multiple injuries. Fourteen fractures (30.4%) were open and all fractures were treated: 11 stage I (23.9%), two stage II (4.3%) and one stage III (2.3%). Intramedullary pinning was used in all cases for the radius and the ulna. In 27 patients (58.6%) pinning was achieved without open access to the focus. Pin diameter was 2.5mm for 38 cases (82.6%). Self-controlled rehabilitation exercises were started immediately without complementary immobilization. Outcome was assessed in 41 patients with a mean follow-up of 18 months (range three months to seven years).

RESULTS: Functional outcome, according to Tscherne and Oestern, was very good or good in 31 cases (75.5%). For 35 cases (85.4%) bone healing was achieved at mean 3.5 months for the radius and four months for the ulna. Retarded healing was noted in four cases (9.7%) for the ulna. For the 41 patients reviewed, 11 (26.8%) presented axial misalignment of one of the forearm bones with an angle strictly greater than 10 degrees for three. There were six patients with nonunion (14.6%), of both bones in two and one in four. Radioulnar synostosis was observed in four cases (9.7%). No infections or recurrent fractures were noted.

DISCUSSION: The localization of the fracture line affected the outcome. Among the four cases with a fracture in the 5th sixth of the radius, two developed misalignment with an angle strictly greater than 10 degrees and one presented a secondary displacement which required revision on day 15 for plate-screw fixation of the radius. This might be due to the spreading corticals of the distal radius where pin stabilization would be less effective than for fractures in the 3rd or 4th sixths where the corticals run parallel. Outcome was less satisfactory when the fracture focus was opened. Four of the six nonunions and three of the four synostoses occurred among the 19 patients who had open pinning. This might be due to loss of the fracture hematoma. Analysis of the type of fixation has shown that our best results were obtained when we used a single 2.5 mm elastic pin. For the cases where we used a smaller pin (2 mm), we had three major misaligments, one nonunion involving both bones and one recurrent dislocation of the radial head. There were no infections or recurrent fractures in this series where the pin was removed in 27 patients (65.6%) at mean one year.

CONCLUSION: Intramedullary pinning is an attractive alternative for the treatment of shaft fractures involving both forearm bones in adults. Best results are obtained if the fracture (situated outside the 5th sixth) can be stabilized without opening the focus with a single 2.5 mm pin. This method combines the advantages of closed osteosynthesis, that is, a simple nontraumatic procedure decreasing the risk of suppuration, and early return of function, limiting postoperative immobilization. It enables early sturdy bone healing with a low risk of recurrent fracture.