Subscapularis Release in Shoulder Replacement Determines Structural Muscular Changes

Department of Orthopaedic Surgery and Traumatology, Ghent University Hospital, Ghent, Belgium.
Clinical Orthopaedics and Related Research (Impact Factor: 2.77). 02/2012; 470(8):2193-201. DOI: 10.1007/s11999-012-2291-x
Source: PubMed


Osteotomy of the lesser tuberosity in shoulder arthroplasty allows bony healing of the subscapularis tendon but does not prevent fatty degeneration in its muscle. Occurrence or increase in fatty degeneration may depend on the surgical technique.
We (1) assessed fatty degeneration in the subscapularis muscle and its cross-sectional area after a C-block osteotomy of the lesser tuberosity with minimal mobilization of the subscapularis muscle, and (2) determined whether this technique had any adverse effect on function, fatty degeneration, and cross-sectional area of the subscapularis muscle.
We retrospectively examined 36 patients with shoulder replacements who had C-block osteotomies. Constant-Murley scores and clinical signs of subscapularis insufficiency were recorded. We radiographically assessed prosthetic placement. On CT scans, lesser tuberosity healing, fatty degeneration, and cross-sectional area of the subscapularis muscle were determined. The minimum followup was 13 months (mean, 18 months; range, 13-33 months).
The mean absolute Constant-Murley score was 71.2. Two patients had weakness of the subscapularis muscle without loss of active motion. All tuberosities healed anatomically. A normal glenohumeral relationship was found in all cases. Fatty degeneration was Grade 0 in 44%, Grade 1 in 39%, Grade 2 in 14%, and Grade 3 in 3%. The subscapularis muscular cross-sectional area decreased from 16.7 cm(2) preoperatively to 14.5 cm(2) postoperatively (13%).
The C-block osteotomy with minimal dissection of the subscapularis is associated with a low incidence of fatty degeneration in the subscapularis muscle after shoulder arthroplasty although the muscular cross-sectional area of the subscapularis decreased.
Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

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    • "In an attempt to prevent dysfunction of the subscapularis associated with tenotomy or peel techniques and improve outcomes during TSA, the lesser tuberosity osteotomy (LTO) was developed [4] [5]. Proponents of the LTO argue its advantages include bone-to-bone healing of the osteotomy leading to improved strength of repair, lack of violation of the tendon substance of the subscapularis, enhanced exposure of the glenoid as well as the ability to monitor the repair radiographically . "
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    ABSTRACT: Take down of the subscapularis tendon is a necessary step in performing total shoulder arthroplasty through the deltopectoral approach. Anatomic repair and healing of the subscapularis is vital to achieving reliable functional outcomes postoperatively. Detachment of the subscapularis is typically achieved by either tenotomy, subscapularis peel, or lesser tuberosity osteotomy. Previous reports have suggested that subscapularis dysfunction after either tenotomy or peel is remarkably high. It is our opinion that lesser tuberosity osteotomy is the preferred method of subscapularis take down during shoulder arthroplasty. Herein we review the literature comparing the various techniques of subscapularis management and discuss our preferred method for lesser tuberosity osteotomy during total shoulder arthroplasty via the standard deltopectoral approach.
    Seminars in Arthroplasty 03/2013; 24(1):7–10. DOI:10.1053/j.sart.2013.04.001
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    • "This approximation was supported by an EMG study comparing healthy subjects to rotator cuff tear patients and reporting no significant differences in inter-muscular coordination (Hawkes et al., 2012). We associated muscular deficiency with PCSA, as suggested by clinical observations (De Wilde et al., 2012; Goutallier et al., 1994). "
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    ABSTRACT: Background: The rotator cuff muscles are the main stabilizer of the glenohumeral joint. After total shoulder arthroplasty using anterior approaches, a dysfunction of the subscapularis muscle has been reported. In the present paper we tested the hypothesis that a deficient subscapularis following total shoulder arthroplasty can induce joint instability. Methods: To test this hypothesis we have developed an EMG-driven musculoskeletal model of the glenohumeral joint. The model was based on an algorithm that minimizes the difference between measured and predicted muscular activities, while satisfying the mechanical equilibrium of the glenohumeral joint. A movement of abduction in the scapular plane was simulated. We compared a normal and deficient subscapularis. Muscle forces, joint force, contact pattern and humeral head translation were evaluated. Findings: To satisfy the mechanical equilibrium, a deficient subscapularis induced a decrease of the force of the infraspinatus muscle. This force decrease was balanced by an increase of the supraspinatus and middle deltoid. As a consequence, the deficient subscapularis induced an upward migration of the humeral head, an eccentric contact pattern and higher stress within the cement. Interpretation: These results confirm the importance of the suscapularis for the long-term stability of total shoulder arthroplasty.
    Clinical biomechanics (Bristol, Avon) 01/2013; 28(2). DOI:10.1016/j.clinbiomech.2012.11.010 · 1.97 Impact Factor
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    ABSTRACT: Background: Loosening of the glenoid component remains the most common problem in total shoulder arthroplasty. It has been described that the round-backed, all-polyethylene components with cemented peg fixation perform better biomechanically and clinically than flat-backed, metal-backed, or keeled components. However, side effects of cementing have been described. We hypothesized that cementing of a specific type of all-polyethylene glenoid component with 3 peripheral pegs and 1 central anchor peg is not necessary to obtain good clinical and radiologic results. Materials and methods: Thirty-four shoulders (34 patients), with a mean follow-up of 28.3 months, were evaluated clinically with the Constant-Murley score and the SF-12 Health Survey score. The fixation of the glenoid component was evaluated with computed tomography scan. Results: The Constant-Murley score increased from 40.2 points (range, 13-73 points) preoperatively to 72 points (range, 54-93 points) postoperatively. The SF-12 Physical Component Summary score was 45, and the SF-12 Mental Component Summary score was 50. No signs of loosening were seen around the pegs or glenoid in 30 shoulders. Signs of loosening were seen around the central anchor peg and the peripheral pegs in 4 shoulders. There was no statistical difference between the clinical outcome of patients with and without signs of loosening. Conclusion: The clinical and radiologic evaluation of an uncemented all-polyethylene glenoid is promising, with good clinical results and with no signs of loosening in 88% of the patients on computed tomography scans.
    Journal of shoulder and elbow surgery / American Shoulder and Elbow Surgeons ... [et al.] 04/2013; 22(10). DOI:10.1016/j.jse.2013.01.036 · 2.29 Impact Factor
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