Thurs., 10/14/10 Upper Extremity, Paper #27, 3:02 pm OTA-2010
Electrophysiological Assessment after Minimally Invasive Fracture Treatment of the Proximal Humerus Using a Minimal Anterolateral Acromial Approach
Götz Röderer, MD1; Philipp Hansen2; Anne-Dorte Sperfeld, MD2;
Lothar Kinzl; Florian Gebhard, MD1; Jan Kassubek, MD2;
1University of Ulm, Orthopaedic Trauma, Ulm, Germany;
2University of Ulm, Neurology, Ulm, Germany
Purpose: Minimally invasive fracture treatment of the proximal humerus can be performed using a minimal anterolateral acromial approach with the aim of soft-tissue protection. The anatomical relationship to the axillary nerve is close and there is risk of nerve lesion. In many cases it is difficult to clinically diagnose an axillary nerve lesion at the level of the minimal anterolateral acromial approach. The aim of this study was to investigate whether electromyography (EMG) shows signs of deltoid muscle impairment as a result of an axillary nerve lesion after performing a minimal anterolateral acromial approach, and to what possible extent it goes along with functional impairment.
Methods: 23 patients (14 men, 9 women; average age, 58 years) who sustained a fracture of the proximal humerus that was treated with minimally invasive locked plating using the minimal anterolateral acromial approach were included. Ten postoperative follow-up investigations were performed at 6 weeks, 6 months, and 12 months, respectively. As a control group, 10 patients (7 women, 3 men; average age, 67 years) with proximal humerus fractures that were treated nonoperatively were investigated once 6 weeks after the initial trauma. EMG changes indicating lesion of the axillary nerve were distinguished in “acute,” “chronic,” and “combined,” and semiquantified in “slight,” “medium,” and “severe.” Functional outcome was assessed using the Constant score.
Results: In summary, there were 3 (10%) cases with signs of acute neurogenic impairment of the anterior part of the deltoid muscle (2 slight and 1 medium), 15 (50%) chronic (10 slight and 5 medium), and 6 (20%) combined (3 slight, 1 medium, and 2 severe). There were more cases with signs of neurogenic impairment (acute and chronic) at initial/early follow-up (6 weeks, n = 8; 6 months, n = 9) compared to 12 months postoperatively (n = 7). The EMG findings were in 2 cases (7%) after 6 weeks in accordance with an incomplete lesion of the axillary nerve with different functional outcome (Constant 73 vs 24.5 points) and in 1 case after 6 months with complete lesion of the axillary nerve (Constant 49 points). The overall rate of axillary nerve lesion according to EMG in our study was 10%. One case of incomplete lesion (Constant 73 points) showed good regression during follow-up (slight neurogenic impairment after 6 months, Constant 83 points). The average Constant score in patients without any signs of neurogenic impairment in EMG was 74 points, compared to 51 points (acute neurogenic impairment), 69 points (chronic), and 68 points (combined).
Conclusion: There are EMG signs of neurogenic impairment of the deltoid muscle after minimal anterolateral acromial approach in almost all patients. However, even in patients treated nonoperatively, there are such findings in 10%. The functional outcome (Constant score) is worse in patients with neurogenic impairment than without. The severity of impairment together with the functional outcome can improve during the postoperative course even in case of axillary nerve lesion in the EMG. In those cases, no lesion of the axillary nerve in its structure seems to be present.
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• The FDA has not cleared this drug and/or medical device for the use described in this presentation (i.e., the drug or medical device is being discussed for an “off label” use). ◆FDA information not available at time of printing. Δ OTA Grant.