We present the long-term results of pectoralis major transfer to restore elbow flexion in seven patients (ten procedures). The early results in all the patients were encouraging but with longer follow-up a gradual and progressive flexion deformity was observed with a decrease in the arc of flexion in eight elbows, reaching ≥ 90° in all cases. The results of pectoralis major transfer deteriorate with time due to the development of a recalcitrant flexion deformity of the elbow. With bilateral involvement we now recommend that the procedure be undertaken on one side only to allow the hand to reach the mouth for feeding, while the opposite side remains in extension for perineal toilet

Transfer of pectoralis major has evolved as the most favoured option for the management of the difficult problem of irreparable tears of subscapularis. We describe our experience with this technique in 30 patients divided into three groups. Group I comprised 11 patients with a failed procedure for instability of the shoulder, group II included eight with a failed shoulder replacement and group III, 11 with a massive tear of the rotator cuff. All underwent transfer of the sternal head of pectoralis major to restore the function of subscapularis. At the latest follow-up pain had improved in seven of the 11 patients in groups I and III, but in only one of eight in group II. The subjective shoulder score improved in seven patients in group I, in one in group II and in six in group III. The mean Constant score improved from 40.9 points (28 to 50) in group I, 32.9 (17 to 47) in group II and 28.7 (20 to 42) in group III pre-operatively to 60.8 (28 to 89), 41.9 (24 to 73) and 52.3 (24 to 78), respectively. Failure of the tendon transfer was highest in group II and was associated with pre-operative anterior subluxation of the humeral head. We conclude that in patients with irreparable rupture of subscapularis after shoulder replacement there is a high risk of failure of transfer of p?ctoralis major, particularly if there is pre-operative anterior subluxation of the humeral head

Two patients presented with pain in the arm and a radiographic lesion of the upper humerus which warranted surgical exploration and excision biopsy. In both cases the pathology was inflammatory and involved the insertion of pectoralis major. Tendinitis of the pectoralis major with an associated lesion of the humerus has not previously been described

Four patients with pectoralis major ruptures underwent clinical and dynamometric assessment and one patient underwent late surgical repair. The operation is described. Dynamometry proved a useful and objective method of estimating the loss of strength and indicating patients who might benefit from surgical repair

We report the transfer of the sternal part of the pectoralis major to the lower pole of the scapula in 15 patients with winged scapula. At follow-up after 1 to 16 years nine had a satisfactory result and were gainfully employed, though in four of these re-operation had been necessary. Two patients had fair results; the transplant functioned, but they had limited voluntary control. Four were failures: two had had paralysis of other shoulder girdle muscles in addition to the serratus anterior. The indications for the operation are discussed

Rotator cuff pathology is the main cause of shoulder pain and dysfunction in older adults. When a rotator cuff tear involves the subscapularis tendon, the symptoms are usually more severe and the prognosis after surgery must be guarded. Isolated subscapularis tears represent 18% of all rotator cuff tears and arthroscopic repair is a good alternative primary treatment. However, when the tendon is deemed irreparable, tendon transfers are the only option for younger or high-functioning patients. The aim of this review is to describe the indications, biomechanical principles, and outcomes which have been reported for tendon transfers, which are available for the treatment of irreparable subscapularis tears. The best tendon to be transferred remains controversial. Pectoralis major transfer was described more than 30 years ago to treat patients with failed surgery for instability of the shoulder. It has subsequently been used extensively to manage irreparable subscapularis tendon tears in many clinical settings. Although pectoralis major reproduces the position and orientation of the subscapularis in the coronal plane, its position in the axial plane – anterior to the rib cage – is clearly different and does not allow it to function as an ideal transfer. Consistent relief of pain and moderate recovery of strength and function have been reported following the use of this transfer. In an attempt to improve on these results, latissimus dorsi tendon transfer was proposed as an alternative and the technique has evolved from an open to an arthroscopic procedure. Satisfactory relief of pain and improvements in functional shoulder scores have recently been reported following its use. Both pectoralis minor and upper trapezius transfers have also been used in these patients, but the outcomes that have been reported do not support their widespread use. Cite this article: Bone Joint J 2024;106-B(9):970–977

Introduction: Shoulder hemiarthroplasty is an established treatment for complex proximal humeral fractures but the functional results of these hemiarthroplasties in proximal humeral fractures are often poor and unpredictable. The capacity of restoring proximal humeral anatomy in such these complex fractures is of capital importance to obtain proper placement and secure fixation of the tuberosities to the prosthesis. The purpose of this study was to determine the value of the upper edge of the pectoralis major insertion as a landmark to determine proper height and version of hemiarthroplasties implanted for proximal humeral fractures. Material and Methods: The upper edge of the pectoralis major insertion was referenced with a metallic device in 20 cadaveric humerus. A Computed Tomography study was performed in all the specimens. Total humeral length was recorded in all the specimens. The distance between the upper pectoralis major insertion and the tangent to the humeral head was also recorded. The anatomical neck of the humeral head was determined in the axial plane of the CT scan and a perpendicular line was drawn to represent the posterior fin of the prosthesis. To that image, the CT scan slice showing the upper insertion of the pectoralis major was superimposed and the distance of the metallic reference to the posterior fin of the prosthesis was recorded as it was the angle formed by the line connecting the upper pectoralis major insertion with the center of the anatomical neck diameter and with the posterior fin of the prosthesis. Qualitative variables are presented in absolute and percentage values. Quantitative variables are presented with mean values and standard deviation. Results: Mean total humeral length was 32,13 cm. The mean distance from the upper pectoralis major insertion to the tangent to the humeral head was of 5,64. The mean distance from the upper pectoralis major insertion to the tangent to the humeral head represents the 17,55% of the total humeral length. The mean distance of the upper pectoralis major insertion to the posterior fin of the prosthesis was of 1,06 cm. The angle between the upper pectoralis major insertion and the posterior fin of the prosthesis was of 24,65º. Conclusions: Mean distance from the upper part of the pectoralis major insertion to the top of the humeral head of 5, 6 cm with a 95% confidence interval. Placement of the prosthesis in the proper retroversion can be achieved by placing the posterior fin 1,06 cm posterior to the upper insertion of the pectoralis major or by placing the posterior fin at 24,65º with respect to the upper insertion line. Upper insertion of the pectoralis major constitutes a reliable reference to reproduce anatomy in hemiarthroplasties for proximal humeral fractures

Between March 1994 and June 2003, 80 patients with brachial plexus palsy underwent a trapezius transfer. There were 11 women and 69 men with a mean age of 31 years (18 to 69). Before operation a full evaluation of muscle function in the affected arm was carried out. A completely flail arm was found in 37 patients (46%). Some peripheral function in the elbow and hand was seen in 43 (54%). No patient had full active movement of the elbow in combination with adequate function of the hand. Patients were followed up for a mean of 2.4 years (0.8 to 8). We performed the operations according to Saha’s technique, with a modification in the last 22 cases. We demonstrated a difference in the results according to the pre-operative status of the muscles and the operative technique. The transfer resulted in an increase of function in all patients and in 74 (95%) a decrease in multidirectional instability of the shoulder. The mean increase in active abduction was from 6° (0 to 45) to 34° (5 to 90) at the last review. The mean forward flexion increased from 12° (0 to 85) to 30° (5 to 90). Abduction (41°) and especially forward flexion (43°) were greater when some residual function of the pectoralis major remained (n = 32). The best results were achieved in those patients with most pre-operative power of the biceps, coracobrachialis and triceps muscles (n = 7), with a mean of 42° of abduction and 56° of forward flexion. Active abduction (28°) and forward flexion (19°) were much less in completely flail shoulders (n = 34). Comparison of the 19 patients with the Saha technique and the 15 with the modified procedure, all with complete paralysis, showed the latter operation to be superior in improving shoulder stability. In all cases a decrease in instability was achieved and inferior subluxation was abolished. The results after trapezius transfer depend on the pre-operative pattern of paralysis and the operative technique. Better results can be achieved in patients who have some function of the biceps, coracobrachialis, pectoralis major and triceps muscles compared with those who have a complete palsy. A simple modification of the operation ensures a decrease in joint instability and an increase in function

Sternoclavicular joint infections are uncommon but severe and complex condition usually in medically complex and compromised hosts. These infections are challenging to treat with risks of infection extending into the mediastinal structures and surgical drainage is often faced with problems of multiple unplanned returns to theatre, chronic non-healing wounds that turn into sinus and the risk of significant clinical escalation and death. Percutaneous aspirations or small incision drainage often provide inadequate drainage and failed control of infection, while open drainage and washout require multidisciplinary support, due to the close proximity of the mediastinal structures and the great vessels as well as failure to heal the wounds and creation of chronic wound or sinus. We present our series of 8 cases over 6 years where we used the plan of open debridement of the Sternoclavicular joint with medial end of clavicle excision to allow adequate drainage. The surgical incision was not closed primarily, and a suction vacuum dressing was applied until the infection was contained on clinical and laboratory parameters. After the infection was deemed contained, the surgical incision was closed by local muscle flap by transferring the medial upper sternal head of the Pectoralis Major muscle to fill in the sternoclavicular joint defect. This technique provided a consistent and reliable way to overcome the infection and have the wound definitively closed that required no secondary procedures after the flap surgery and no recurrence of infections so far. We suggest that open and adequate drainage of Sternoclavicular joint staged with vacuum dressing followed by pectoralis major local flap is a reliable technique for achieving control of infection and wound closure for these challenging infections

Introduction: Between June 2005 and September 2007, ten male athletes underwent repair of the pectoralis major tendon using a new double row surgical technique whereby employing three bone anchors to produce a large foot print of the pectoralis major tendon. Here, we present our new surgical technique for the repair of the pectoralis major tendon with the results. Patients: The mean age was 33.9 years (23–46 years) and the average follow up was 20.3 months (12–39). The mean time between surgery and the original injury was 11.6 weeks (1–48 weeks). We used the visual analogue scale for determining the level of satisfaction with regards to cosmesis and pain. Also, the patients were asked them about their subjective loss of strength. Results: Eight patients were in pain prior to surgery and all patients were unsatisfied with the appearance of their chest. The average loss of strength was 75% pre-operatively. At the final follow up, none of the patients complained of any pain while pushing things away from their body; nine patients had no pain on moving their arm across the chest whilst one patient reported mild pain. Nine were satisfied with the appearance and the average regain in strength was around 90%. One patient developed a deep infection requiring a further washout and antibiotics. No re-rupture was seen amongst our patients. Hence, we conclude that satisfactory results can be achieved with this new technique

Aims. Despite the expansion of arthroscopic surgery of the shoulder, the open deltopectoral approach is increasingly used for the fixation of fractures and arthroplasty of the shoulder. The anatomy of the terminal branches of the posterior circumflex humeral artery (PCHA) has not been described before. We undertook an investigation to correct this omission. Patients and Methods. The vascular anatomy encountered during 100 consecutive elective deltopectoral approaches was recorded, and the common variants of the terminal branches of the PCHA are described. Results. In total, 92 patients (92%) had a terminal branch that crossed the space between the deltoid and the proximal humerus and which was therefore vulnerable to tearing or avulsion during the insertion of the blade of a retractor during the deltopectoral approach to the shoulder. In 75 patients (75%) there was a single vessel, in 16 (16%) a double vessel and in one a triple vessel. Conclusion. The relationship of these vessels to the landmark of the tendon of the insertion of pectoralis major into the proximal humerus is described. Damage to these previously undocumented branches can cause persistent bleeding leading to prolonged surgery and post-operative haematoma and infection, as well as poor visualisation during the procedure. Cite this article: Bone Joint J 2016;98-B:1395–8

Pectoralis major tendon rupture is a relatively rare injury, resulting from violent, eccentric contraction of the muscle. Over fifty percent of these injuries occur in athletes classically in weight-lifters during bench press. In this study, thirteen cases of distal rupture of the pectoralis major muscle in athletes are presented. All patients underwent surgical repair. Physical findings and surgical technique are described. Magnetic resonance imaging was used in the diagnosis of all patients and intra-operative findings correlated with the reported scans in eleven patients with minor differences in two patients. During follow up examination, six patients had excellent results, six had good results and one had a fair result. Eleven patients could return to sports activity at their preoperative level. Among our patients we emphasize that of an orthopaedic resident who suffered a rupture of his pectoralis major tendon as an unusual complication of closed manipulation of an anterior shoulder dislocation. According to the literature and our experience, we suggest that only surgical repair of the pectoralis major rupture will result in complete recovery and restoration of the full strength of the muscle which is essential for the active athlete

Introduction and Aims: Pectoralis major tendon rupture is a relatively rare injury, resulting from violent, eccentric contraction of the muscle. Over 50percent of these injuries occur in athletes, classically in weight-lifters during bench press. Method: In this study, 13 cases of rupture of the pectoralis major muscle in athletes are presented. All patients underwent surgical repair. Physical findings and surgical technique are described. Magnetic resonance imaging was used in the diagnosis of all patients. Intra-operative findings correlated with the reported scans in 11 patients with minor differences in two patients. Results: During follow-up examination, six patients had excellent results, six had good results and one had a fair result. Eleven patients could return to sports activity at their pre-operative level. Among our patients we emphasise that of an orthopaedic resident who suffered a rupture of his pectoralis major tendon as an unusual complication of closed manipulation of an anterior shoulder dislocation. Conclusion: According to the literature and our experience, we suggest that only surgical repair of the pectoralis major rupture will result in complete recovery and restoration of the full strength of the muscle, which is essential for the active athlete

Upper limbs are commonly involved in Arthrogyposis Multiplex Congenita. They may be involved in isolation or in combination with lower limbs. There are two patterns of involvement in upper limbs. The most common (type I) pattern presents with adduction and internal rotation at the shoulder, extension at the elbow, pro-nation of the forearm and flexion deformity of the wrist, indicating involvement of the C5 and C6 segments. These deformities can be quite disabling and may require surgery to help improve function. We present our long-term results with pectoralis major transfer procedure (as modified by senior author MJB) to restore elbow flexion in seven patients (ten procedures). Results: Early results in all our patients were quite encouraging. Six patients retained useful power in transferred pectoralis major muscle and maintained the arc of flexion, which was attained following tricepsplasty. However, as children were followed up a gradually increasing flexion deformity and decreasing flexion arc were observed in eight elbows. The onset and progression of flexion deformity was gradual and progressive. The flexion deformity reached ninety degrees or more in all cases. Conclusions: Results of pectoralis major transfer to treat extension contracture of the elbow in arthrogryposis deteriorate with time due to development of recalcitrant flexion deformity of the elbow. Presently we recommend this procedure on one side only in cases of bilateral involvement because if one procedure is carried out it would be possible for this hand to get to the mouth for feeding and the other unoperated side would be able to look after the perineal hygiene

Introduction: The purpose of this study was to evaluate the results 9 to 12 years after the transfer of 3 distal parts of pectoralis major muscle to restore active elbow flexion in patient with arthrogryposis. Material and methods: From 1996 to 1999, elbow flexion was reconstructed in 9 upper extremities by 5 patient aged 4.3–9 years. The patients were clinically evaluated according to the subjective and objective assessment and examined electromyographically before the surgery and during the follow up. Last clinical examination was provided 8 to12 years after the surgery in patients aged 15 to 18 years. Results: 3–4 years after pectoralis major transfer, 6 very good and good results were achieved, the average active ROM of elbow ranged 15 to 95 degrees. The power of elbow flexion was graded as 4 and 4+. This method was unsuccessful in the remaining 3 cases, the patients were not able to reach the mouth with the hands because of limited elbow flexion. 9 to12 years after the surgery, the results were similar. 5 extremities remain very good and good. One deterioration was obvious. The ROM of elbow changed, namely the extension was mostly reduced even in very good and good evaluations (the average decrease was 13.8 degrees, the range −20 to +10 deg.). The active flexion was not changed in 5 elbows, or it was increased (the average increase 4,4 deg., the range 0–15 deg.). The final limitation of extension (30 – 50 degrees) does not restrict using the hands for perineal hygiene and the final active flexion (85–100 degrees) allows elevating the hands to the head for feeding and toilet. Discussion and Conclusions: From the analysis of unsuccessful results 3–4 years after the surgery it was obvious that all cases were related to very limited preoperative passive flexion of the elbow; restricted movement of the shoulder and failed distal fixation of the transferred muscle. After 9–12 years, the active elbow flexion and extension for raising the hands to the mouth and for toilet needs, respectively, remain in majority previously successful cases. Because most children reached the skeletal maturity, no further shortening of the transferred muscle and limitation of extension is expected. These findings do not concur with the literature reports. According to our results, the transfer of the pectoralis major represents the efficient method for permanent restoring of bilateral active elbow flexion with the remaining functional extension. The ROM does not change significantly after having reached the plateau 2 years postoperatively. The prerequisites for successful results are a minimum of 90 degrees of passive flexion of the elbow before the surgery, the active shoulder abduction of 80–90 degrees, long-term rehabilitation and successful fixation of the transferred muscle to the forearm

Introduction: Tumors of the axilla impose a surgical difficulty because they are usually large at presentation and in close proximity to the major neurovascular bundle of the upper extremity. Attempted tumor resection via the base of the axilla is difficult because of limited exposure of the axillary content and neurovascular bundle. The authors have used a safe and reliable exposure for these situations. Methods: Between 1980 and 1997, 35 patients underwent extensile exposure of an axillary tumor. Diagnoses included 19 primary and 16 metastatic tumors of the axilla. The axillary cavity was fully exposed via the deltopectoral groove after detachment and reflection of two layers of muscles: first, the pectoralis major and, second, the coracoid origin of the pectoralis minor, cora-cobrachialis, and the short head of the biceps muscle. This surgical approach allowed full tumor visualization and determination of the exact anatomic relation of the tumor to the neurovascular bundle and as a result, tumor respectability. Following resection, the pectoralis minor and conjoined tendons were reattached to the coracoid process with a nonabsorbable suture, and the pectoralis major was reattached to its insertion site on the proximal humerus in the same manner. Results: Exposure revealed a safe plane of dissection between the tumor and the major neurovascular bundle in 23 patients and invasion of the major neurovascular bundle in 12 patients who subsequently underwent a forequarter amputation. At the most recent follow-up, none of these patients had functional limitation, which could be attributed to the extensile approach itself. All patients gained their presurgical pectoralis major and biceps function. Complications in the group of patients that underwent tumor resection included three (13%) superficial wound infections. Due to intended enbloc resection of an involved nerve with the tumor, two nerve palsies (8.7%) were documented. None of the remaining 21 patients had numbness, paresthesias, or nerve pain. There were three (13%) local recurrences; two were managed with wide excision and adjuvant radiation therapy and one necessitated amputation. Conclusions: The extensile exposure of the axilla allows full visualization of axillary tumors. It allows determination of tumor respectability and safe and reliable resection, when indicated. This exposure is associated with good functional outcome and an acceptable morbidity and is recommended in the management of axillary tumors

Purpose of the study: Old tears of the subscapular muscle situated in the glenoid area are not accessible to direct repair and require locoregional muscle plasty. The clavicular portion of the pectoralis major can be used for reconstruction. The purpose of this study was to describe the operative technique and examine short-term outcome. Material and methods: Five patients, mean age 54 years (45–71 years) with an irreparable tear of the subscapularis in the glenoid area with fatty degeneration greater than grade two in the Goutallier classification were treated. Four had had previous surgery for acromioplasty associated with rotator cuff repair in two or implantation of a humeral prosthesis in one. The preoperative Constant score was 27.5 (mean, range = 8.5–54) due to invalidating pain, limited active mobility and reduced muscle force. Gerber’s lift-off test was positive for those patients for whom it could be performed. Plain x-rays evidenced anterior subdislocation of the humeral head in one case. Subscapular reconstruction was achieved using the entire clavicular portion of the pectoralis major which was dissected and sectioned at its distal insertion on the humerus then reinserted by transosseous suture onto the lesser tuberosity. The rehabilitation program started with active and passive mobility against gravity within a few days of surgery using biofeedback contraction of the muscle flap then active contractions two months postoperatively. Patients were reviewed at a mean 19 months (6–42 months) for clinical and radiological assessment. Results: Four patients had a painless shoulder with a negative lift-off test. The gain in active mobility was predominantly achieved with anterior elevation and abduction. Muscle force was weak leading to a low overall Constant score at revision (mean = 50, range = 30–63). Radiographically, the humeral head was centered exactly as on the preoperative films. There were no cases with a new anterior subdislocation nor an aggravation of a former subdislocation. Functional outcome was better in cases with a unique tear of the subscapularis. Discussion and conclusion: Open surgery is used for primary repair of recent tears of the subscapularis. This technique gives 80 p. 100 good and very good results. In case of symptomatic acromioclavicular osteoarthtisis, better long-term results can be obtained by using a tendodesis of the long biceps and resecting the lateral centimeter of the clavicle. In case of irreparable tears in the glenoid area, reconstruction by transfer of the clavicular portion of the pectoralis major can produce a stable painless shoulder with improved active moblity and normal clinical tests. This method provides anterior stability of the glenohumeral articulation and prevents any anterior subdislocation of the humeral head, thus protecting the joint from secondary degeneration

After establishing anatomical feasibility, functional reconstruction to replace the anterolateral part of the deltoid was performed in 20 consecutive patients with irreversible deltoid paralysis using the sternoclavicular portion of the pectoralis major muscle. The indication for reconstruction was deltoid deficiency combined with massive rotator cuff tear in 11 patients, brachial plexus palsy in seven, and an isolated axillary nerve lesion in two. All patients were followed clinically and radiologically for a mean of 70 months (24 to 125). The mean gender-adjusted Constant score increased from 28% (15% to 54%) to 51% (19% to 83%). Forward elevation improved by a mean of 37°, abduction by 30° and external rotation by 9°. The pectoralis inverse plasty may be used as a salvage procedure in irreversible deltoid deficiency, providing subjectively satisfying results. Active forward elevation and abduction can be significantly improved

Introduction:. Tuberosity healing is strongly correlated with functional results in all series of three- and four-part fractures of the proximal humerus treated by hemiarthroplasty. We formed a working group to improve position of the implant and fixation of the tuberosities on an implant specifically intended for traumatology. Material and Methods:. An anatomic study on 11 cadavers and a prospective multicentre clinical study of 32 cases were performed to validate extrapolable original solutions at the patient scale: placement of the stem at a height indicated in relation to the insertion of the clavicular bundle of the pectoralis major, locking of the stem, placement (based on bone quality) of a variable volume metaphyseal frame (offset modular system® OMS®), avoiding medialisation of the tuberosities, and fixation of the tuberosities using strong looped sutures, brightly coloured so that they can be located more easily. Evaluation by Dash score and Constant score was correlated with positioning of the tuberosities using radiographs. Results:. The clinical study enabled a distance of the top of the head to pectoralis major of 5.5 cm +/− 5 mm to be determined, confirming the results of the anatomic study and data from the literature. The distal double-locking ancillary device and the suturing technique for the tuberosities using looped sutures was judged to be effective by all of the surgeons. 23 patients (5 males, 9 CT4 and 8 CT3) with an mean age 69,6 (33–90) were operated on by 3 senior surgeons and reviewed at a mean follow-up of 17,3 months (6–24). All patients were seen again at 3 months and 6 months and the average motion at last follow was abduction of 90,7° (140–40), active anterior elevation of 113,25° (160–60), and external rotation of 43,2°(55–30). One complication was noted: inadequate position of a locking screw. In the 17 patients operated without oms® 50% had adequate initial positioning of the tuberosities and 10% secondary displacement. In comparison the 6 patients operated with the oms® 100% had adequate initial positioning of the tuberosities and no secondary displacement occurred. Discussion:. The series from Sofcot, Boileau, and more recently Reuther yielded results of 40 to 66% malposition or nonunion of the tuberosities. The initial clinical results from our series are encouraging and demonstrate that using a variable volume metaphyseal frame in synthesis of the tuberosities with control of the height of the implant is reliable. This multicentre study should be extended by a more long-term analysis

Residual muscle weakness in obstetric brachial plexus palsy results in soft-tissue contractures which limit the functional range of movement and lead to progressive glenoid dysplasia and joint instability. We describe the results of surgical treatment in 98 patients (mean age 2.5 years, 0.5 to 9.0) for the correction of active abduction of the shoulder. The patients underwent transfer of the latissimus dorsi and teres major muscles, release of contractures of subscapularis pectoralis major and minor, and axillary nerve decompression and neurolysis (the modified Quad procedure). The transferred muscles were sutured to the teres minor muscle, not to a point of bony insertion. The mean pre-operative active abduction was 45° (20° to 90°). At a mean follow-up of 4.8 years (2.0 to 8.7), the mean active abduction was 162° (100° to 180°) while 77 (78.6%) of the patients had active abduction of 160° or more. No decline in abduction was noted among the 29 patients (29.6%) followed up for six years or more. This procedure involving release of the contracted internal rotators of the shoulder combined with decompression and neurolysis of the axillary nerve greatly improves active abduction in young patients with muscle imbalance secondary to obstetric brachial plexus palsy