The anterior deltoid's importance in reverse shoulder arthroplasty: A cadaveric biomechanical study

Department of Orthopaedic Surgery, Northwestern University, Chicago, IL, USA.
Journal of shoulder and elbow surgery / American Shoulder and Elbow Surgeons ... [et al.] (Impact Factor: 2.29). 03/2013; 22(3):357-364. DOI: 10.1016/j.jse.2012.02.002
Source: PubMed


BACKGROUND: Frequently, patients who are candidates for reverse shoulder arthroplasty have had prior surgery that may compromise the anterior deltoid muscle. There have been conflicting reports on the necessity of the anterior deltoid thus it is unclear whether a dysfunctional anterior deltoid muscle is a contraindication to reverse shoulder arthroplasty. The purpose of this study was to determine the 3-dimensional (3D) moment arms for all 6 deltoid segments, and determine the biomechanical significance of the anterior deltoid before and after reverse shoulder arthroplasty. METHODS: Eight cadaveric shoulders were evaluated with a 6-axis force/torque sensor to assess the direction of rotation and 3D moment arms for all 6 segments of the deltoid both before and after placement of a reverse shoulder prosthesis. The 2 segments of anterior deltoid were unloaded sequentially to determine their functional role. RESULTS: The 3D moment arms of the deltoid were significantly altered by placement of the reverse shoulder prosthesis. The anterior and middle deltoid abduction moment arms significantly increased after placement of the reverse prosthesis (P < .05). Furthermore, the loss of the anterior deltoid resulted in a significant decrease in both abduction and flexion moments (P < .05). CONCLUSION: The anterior deltoid is important biomechanically for balanced function after a reverse total shoulder arthroplasty. Losing 1 segment of the anterior deltoid may still allow abduction; however, losing both segments of the anterior deltoid may disrupt balanced abduction. Surgeons should be cautious about performing reverse shoulder arthroplasty in patients who do not have a functioning anterior deltoid muscle.

Download full-text


Available from: T. Sean Lynch, Jan 04, 2014
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Professor Grammont revolutionised shoulder surgery with his reverse shoulder arthroplasty design. Patients who had poor results from a conventional shoulder replacement because of cuff deficiency can now be treated effectively. Although designed for cuff tear arthropathy, indications continue to evolve and broaden. The initial results look very promising and the implant has gained much popularity over the years. The article provides an extensive literature review of the indications, results and complications for reverse shoulder arthroplasty.
    The Open Orthopaedics Journal 09/2013; 7:366-372. DOI:10.2174/1874325001307010366
  • [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this review is to provide a better understanding of biomechanical changes induced by reverse shoulder arthroplasty (RSA), discuss the different techniques of radiographic assessment of upper limb lengthening after RSA and determine the ideal soft tissue tension that provides the best functional outcome without increasing the risk of complications. Inclusion criteria were articles in which the primary interest was the technique of measuring upper-extremity lengthening after complications related to lengthening and its role in postoperative function; those written in English, French or German; and those that provided evidence levels I-IV relevant to search terms. Seven articles met our inclusion criteria. Postoperatively, changes in humeral length varied from minus five to five millimetres, and changes in upper-extremity length varied from 15 mm to 27 mm. The acromiohumeral distance averaged 23 mm. Humeral and arm shortening increased the risk of dislocation and led to poor anterior active elevation. The type of surgical approach did not play a role in postoperative function. Subclinical neurological lesions were frequent. Studies in this systematic review indicate that deltoid tensioning by restoring humeral length and increasing the acromiohumeral distance is critical for adequate postoperative function and to prevent dislocation. Excessive arm lengthening should be avoided, with zero to two centimetres of lengthening being a reasonable goal to avoid postoperative neurological impairment.
    International Orthopaedics 11/2013; 38(5). DOI:10.1007/s00264-013-2175-z · 2.11 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Reverse shoulder arthroplasty (RSA) yields unsatisfactory results after deltoid flap reconstruction due to defect of the deltoid muscle. We retrospectively reviewed the outcome of 19 patients after failed deltoid flap reconstruction treated with RSA. Follow-up was after a mean of 4.5 years. Seven patients (37 %) had nine postoperative complications requiring totally 16 revision surgeries. Nonetheless, at latest follow-up, 17 patients had no or mild, two had moderate, and none had severe pain. Before RSA; 13 patients had a pseudoparesis. At latest follow-up, none of the patients had a pseudoparesis. Mean flexion was 121° (90°-160°). Abduction strength averaged 2.3 kg (range 0-5.4 kg). The mean constant score was 70 % (range 28-98 %). Of the 19 patients, 15 were very satisfied with the outcome, four were satisfied, and none was dissatisfied. The mean overall subjective shoulder value was 73 % (30-95 %) of the value of a normal shoulder. Despite of a localized defect of the deltoid muscle after deltoid flap repair, RSA can reliably be associated with a satisfactory outcome.
    Archives of Orthopaedic and Trauma Surgery 01/2014; 134(3). DOI:10.1007/s00402-013-1908-1 · 1.60 Impact Factor
Show more