[Intramedullary fixation of humerus shaft fractures. An analysis of complications of 2 implants with special reference to outcome after management with the unreamed humerus interlocking nail].

INTRODUCTION: Operative treatment of humeral shaft fractures has gained a new impetus with the development of intramedullary interlocking systems for the humerus. Because of the anatomical structure of the humeral marrow cavity, a regular jamming of nail into bone is not to be expected, so that the stability of these systems needs to be achieved through an interlocking mechanism. Among the commercially available interlocking nailing systems the unreamed humeral nail (UHN) and the Seidel-nail (SHN) can be regarded as the standard implants.

DESIGN: In a retrospective study comparing two groups of patients, each treated with one of the two systems, problems and advantages, as well as disadvantages were analyzed, and the complications inherent in the systems examined.

PATIENTS: Between 1988-1992, 47 patients with humeral shaft fractures were treated with a Seidel interlocking nail: 25 acute and 18 pathological fractures as well as 4 non-unions (Group 1). Between 1997-1999, 34 patients with humeral shaft fractures were treated with the unreamed humeral nail (UHN). A total of thirty-five (n = 35) nailings (30 acute and 4 pathological fractures, as well as one re-osteosynthesis after emergence of a non-union) were carried out. Three primary palsies of the radial nerve ensued: two with loss of sensitivity, and one complete paralysis (Group 2).

METHODS: Based on pre- and postoperative X-rays and follow-up examinations, the healing process and complications inherent in each of the systems were evaluated.

RESULTS: Intra-operative complications of Seidel-nailing (Group 1) were seen in 5 cases: failure of the proximal target device in 2 (4.2%) cases; the breaking of the long screwdriver during the distal locking in 1 (2.1%) case; blockade of nail-insertion due to the spreading distal lamellas in 1 (2.1%) case; in 1 (2.1%) case it was impossible to find the imbus of the distal locking screw with the screwdriver. Incorrect surgical technique resulting in further fragmentation of the shaft required revisions in 2 (4.2%) cases. In 3 cases (6.4%), the insertion of the nail was insufficient, so that an impingement resulted. In 12 cases, postoperative complications after Seidel-nailing resulted: 3 (6.4%) radial nerve palsies, of which 2 (4.2%) were transitory; 3 (6.4%) infections; in 3 (6.4%) cases, loosening of the locking bolt inserted in the frontal plane; in 1 (2.1%) case, loosening of the distal spreading screw. The system failed in treating 2 (of 4) non-unions, whereas successful ossification and repair occurred in all acute fractures. In Group 2 (UHN) the acute fractures of 33 cases healed without complications. Intra-operative complications of the unreamed nail: in 2 cases (5.6%), failure of the target devices resulted in malpositoning of interlocking screws. The following intra-operative complications of the retrograde technique were observed: burst of a fragment at the insertion site in 1 case (2.8%); intra-articular positioning of the most proximal interlocking screw in another case (2.8%). Postoperative complications of the unreamed nail: breaking of a proximal and a distal interlocking screw in 1 case (2.8%), which had no influence on the healing progress. In 1 case (2.8%) both proximal interlocking screws came loose and a non-union ensued. After re-osteosynthesis with the same technique, bony repair was achieved.

CONCLUSION: The possibilities of operative methods in treatment of humeral shaft fractures are enhanced by intramedullary interlocking systems. Comparing with the Seidel nail, the unreamed humeral nail (UHN) has two advantages: it can be inserted anterogradely as well as retrogradely, and it provides the possibility of compressing the fracture, resulting in a high rotational stability. Due to these results, the application of the UHN is recommended.