Session IX - Upper Extremity

Intramedullary Nailing of Humeral Shaft Fractures with a Locking Flexible Nail

James P. Stannard, MD; Howard W. Harris, MD; Gerald McGwin, Jr., PhD; David A. Volgas, MD; Jorge E. Alonso, MD, University of Alabama at Birmingham, Birmingham, AL

Purpose: Intramedullary nailing of humeral shaft fractures has been reported with mixed results. Difficulties with high rates of nonunion, shoulder pain and dysfunction, and other complications have been reported in recent articles. The purpose of this study was to document the results and complications associated with the use of a new flexible, locking intramedullary nail that can be implanted either retrograde or antegrade. Antegrade insertion is through the greater tuberosity, sparing the rotator-cuff mechanism. Retrograde insertion can be accomplished with an entry hole approximately one-half the size necessary for a solid nail.

Methods: A retrospective chart review of the records of 51 patients with 52 humeral shaft fractures was combined with a prospective radiographic and outcome evaluation. Inclusion criteria for patients in this study were a diaphyseal humerus fracture and one or more of the following: multiple long bone fractures, open fracture, associated severe chest wall injury, floating elbow, or failure to maintain an acceptable closed reduction. Exclusion criteria included: age less than 16 years, medullary canal less than 8 cm in diameter, or a fracture pattern unsuitable for intramedullary nailing. Data obtained included: mechanism of injury, injury severity score, ipsilateral extremity injury, time to fracture union, complications, fracture pattern and classification, implant positioning, and fracture alignment. Shoulder function was evaluated using a combination of Constant Shoulder Scores, range of motion, and subjective pain data.

Results: Forty-two patients with 43 fractures had adequate clinical follow-up (mean 56 weeks, range 12 to 160) for analysis. Twenty patients sustained open fractures (38%), with two grade-IIIC, three grade-IIIA, nine grade-II, and six grade-I injuries. The fractures were frequently associated with high-energy multiple trauma injuries. Injury Severity Scores ranged from 4 to 50, with a mean of 17.5. Sixteen (31%) patients had ipsilateral extremity injuries and 31 (60%) had other orthopaedic injuries. The mean time to clinical fracture union was 11.7 weeks. Eleven fractures were located in the proximal third, 29 in the middle third, 3 in the distal third, and 9 were segmental, spanning more than one zone. Twenty-five nails were implanted with use of the antegrade technique, and 27 were placed retrograde. Only 8% of patients had a poor shoulder function outcome on the basis of range of motion and pain; 81% of patients had good or excellent results, with an average Constant Shoulder Score of 88 for all patients. Five patients experienced five complications prior to attaining union. The complications included two nonunion (4.7%), two hardware failures (4.7%), and one wound infection (2.3%). All of these complications occurred where 7.5-mm nails had been used; the difference was significant when evaluated with the Fishers Exact test with a P value of 0.05. SF-36 outcome data demonstrated a mean physical component of 39.2 and a mean mental component of 46.1. There was no significant difference in the physical or mental component scores when evaluated for antegrade versus retrograde or the occurrence of a complication.

Discussion and Conclusion: The flexible humeral nail functioned well in our patients, with 12% of patients experiencing a complication, including a 4.7% nonunion rate. Additionally, the nail functioned very well on 11 segmental fractures, 9 of which extended to the surgical neck of the humerus. Retrograde placement combined with deployment of the ball-tipped wires that are built into the nail allowed successful treatment of these very difficult fractures. However, small medullary canals, which required the smaller nail, were associated with a higher complication rate. This implant should be used with caution in any patient who has a medullary diameter of less than 9 mm.