Special Topic A Review of the Biomechanical and Functional Changes in the Shoulder following Transfer of the Latissimus Dorsi Muscles Scott L. Spear, M.D., and Christopher L. Hess, M.D. Washington, D.C. bidity. However, the normal physiology of the Summary: The latissimus dorsi muscle is shoulder girdle depends on the function of among the most commonly used muscle flaps this muscle. Thus, the questions are, are there because it has broad versatility and is gener- biomechanical changes resulting from the loss ally believed to result in minimal donor-site of this muscle, and do these changes translate morbidity. However, the normal physiology into a significant deficit in normal function? of the shoulder girdle depends on the func- Perhaps most importantly, do these changes tion of this muscle. Therefore, we have un- lead to interference with daily activities? We dertaken this review of the literature to ex- have undertaken this review of the literature to amine the issue of biomechanical and examine the issue of biomechanical and func- functional changes of the shoulder that occur tional changes of the shoulder that occur with with transfer of the latissimus dorsi muscle transfer of the latissimus dorsi muscle. In addi- and to determine whether these changes re- tion to any measurable changes, we were par- sult in deficits in normal function. A review of ticularly interested in the clinical implications the literature pertaining to all aspects of the and how one should advise a patient consider- latissimus muscle and shoulder function fol- ing these options. lowing muscle transfer was conducted. The latissimus muscle functions in extension, ad- ANATOMY AND PHYSIOLOGY duction, and internal and external rotation. The latissimus dorsi muscle is one of 26 mus- After the transfer of the muscle there are cles that make up the complex shoulder joint.1 deficits in extension and adduction. These Its broad origin arises as an aponeurosis from deficits result in a faster rate of fatigue during the lower thoracic and lumbar vertebra, sa- activities in which the arms are extended over crum, and iliac crest. As the muscle spans the the head, such as ladder climbing and swim- back heading toward the shoulder, several ming. In addition, there is no decrease in small slips of origin may arise from the lower range of shoulder motion. (Plast. Reconstr. four ribs.2 Crossing the scapula, the latissimus Surg. 115: 2070, 2005.) joins with the teres major muscle; it then wraps around the teres major as it traverses the axil- lary space, creating the posterior axillary fold. The muscle then inserts onto the anteromedial The use of muscle flaps to facilitate the trans- aspect of the humerus along the crest and floor fer of soft tissue is one of the pillars of recon- of the bicipital or intertubercular groove, just structive surgery. The latissimus dorsi muscle is lateral to the teres major muscle.3 among the most commonly used muscle flaps Innervated by the thoracodorsal nerve (C6 because it has broad versatility and is generally to C8), the latissimus muscle acts on the hu- believed to result in minimal donor-site mor- merus in medial rotation, adduction, shoulder From the Division of Plastic Surgery, Medstar-Georgetown University Hospital. Received for publication July 28, 2004. DOI: 10.1097/01.PRS.0000163329.96736.6A 2070 Vol. 115, No. 7 / LATISSIMUS DORSI TRANSFER 2071 extension, depressing of the raised arm, and rotation, 3:2. Upon removal of the muscle, mo- downward rotation of the scapula. These func- tions involving the latissimus should experience a tions are possible through the synergistic ac- change in these torque ratios, to a degree, based tions of the latissimus with six other muscles in on the relative contribution of the latissimus to which the teres major muscle is the principal each movement. component (Table I).4 Although it is only one component of this seven-muscle unit, the latis- LITERATURE simus is one of the most powerful of these The latissimus dorsi flap was originally de- muscles.5 scribed by Tansini in 1906 to cover mastectomy Unfortunately, because of the number of defects.7 The flap fell out of favor until 1976, muscles and complexity of vectors involved in when Olivari8 redescribed it. Since that time, it each shoulder motion, it is difficult to quantify has become one of the workhorses for cover- a specific muscle’s exact contribution to a age of soft-tissue defects throughout the body. given movement. However, by studying ana- Surprisingly though, there have been few con- tomic features of each muscle and certain ac- trolled studies to examine the biomechanical tions, such as torque, the approximate contri- and functional changes that result from remov- bution of the latissimus muscle to shoulder ing the latissimus muscle from the shoulder motion can be appreciated. Therefore, the def- unit. This may be because early reports describ- icits created by its loss can be estimated. To ing the use of the latissimus stated subjectively begin with, the potential force generated by a that shoulder function was unchanged.4,8–10 It muscle is based on its effective size, which is should be noted that some authors did state determined by its physiologic cross-section. that disability could occur in activities that re- This is calculated by measuring the volume of quire strong shoulder adduction,11,12 although the muscle and dividing by the muscle fiber none of these observations were verified by length. The value for each shoulder muscle has objective assessment. been previously calculated, and the latissimus It was not until 1985 that Laitung and Peck13 muscles can generate a significant amount of examined shoulder adduction in 19 patients 2 force.5 Second, when the working capacity of months to 4 years after an operation in which the shoulder is examined, we find that a rela- the latissimus was removed and used as a free tive balance exists between flexor and extensor flap. With arms at 90 degrees of abduction, torques. Ivey et al.6 demonstrated these rela- they utilized a Salter spring balance to examine tionships in the shoulder using variable- adduction strength. The authors determined resistance isokinetic devices. They found the that adduction strength was not affected, but following torque ratios: flexion-extension, 4:5; that scar contracture and loss of range of mo- abduction-adduction, 1:2; and internal-external tion did occur. They concluded that latissimus muscle transfer did not affect arm adduction TABLE I strength, and that therefore shoulder function Latissimus Dorsi Functions and Substitute Muscles was not affected. In another study, Russell et al.14 set out to Function Substitute Muscle determine the extent of functional deficit fol- Medial rotation Latissimus dorsi lowing the use of the latissimus muscle for Pectoralis major reconstructive purposes. Twenty-four patients, Teres major 9 to 65 years of age, were studied 3 to 24 Subscapularis Backward extension Latissimus dorsi months after pedicled or free latissimus muscle Teres major transfer. Among other things, they attempted Deltoid to examine the strength and range of motion Adduction Latissimus dorsi Pectoralis major of all shoulder and trunk muscles involved in Coraco brachialis shoulder motion. No instrument testing was Teres major utilized, and no attempt was made to standard- Teres minor Depress raised arm Latissimus dorsi ize the group. The authors determined that Pectoralis major the operated shoulder was up to 34 percent Teres major weaker than the nonoperated side in 73 per- Accessory cough and squeeze All chest wall muscles cent of patients, and that some patients dem- Reprinted from McCraw, J. B., Penix, J. O., and Baker, J. W. Repair of major defects of the chest wall and spine with the latissimus dorsi myocutaneous onstrated a decreased range of motion follow- flap. Plast. Reconstr. Surg. 62: 197, 1978. ing muscle transfer. Unfortunately, because 2072 PLASTIC AND RECONSTRUCTIVE SURGERY, June 2005 each muscle group was not isolated, a conclu- DISCUSSION sion concerning the specific actions of the la- The use of the latissimus dorsi muscle for tissimus muscle could not be drawn. reconstruction, in particular breast reconstruc- Since that time, several significant studies tion, has become common in plastic surgery. have examined the full extent of shoulder Advising patients on different reconstructive 15–17 function following latissimus transfer. options requires educating them on the pros 15 Brumback et al. examined the dominant and and cons of each method, not just in terms of nondominant shoulders of 17 patients, 22 to the recipient site but the donor site as well 96 months after free muscle transfer. These because patients will have their own reasons for patients were compared with 17 healthy volun- choosing a particular reconstruction. There- teers. Patients were questioned regarding daily fore, it is necessary for the surgeon to have a activities and were evaluated for scar quality, thorough understanding of all aspects of the range of motion, and 19 different isometric, latissimus flap, especially the functional isotonic, and isokinetic strength tests. In this changes that can occur. well-conducted study, the authors reported Despite the paucity of literature examining that none of the patients noted any change in the biomechanics of the shoulder following the ability to perform activities of daily living or removal of the latissimus muscle, there appears had to modify sports-related activities because to be enough information to arrive at some of shoulder function. Only one patient de- conclusions. First, there are definite biome- scribed soreness of the donor shoulder follow- chanical changes that occur in the shoulder ing work performed with arms over the head. girdle following latissimus muscle transfer. Also, passive range of motion was not reduced This seems obvious when one considers the in these patients.