Modified Boytchev procedure for treatment of recurrent anterior dislocation of shoulder.

BACKGROUND: More than 200 different operations have been described for the treatment of recurrent anterior dislocation of shoulder. The Modified Boytchev procedure employs rerouting of the detached tip of coracoid process with its attached conjoined tendon (short head of biceps and coracobrachialis) deep to subscapularis and reattaches to its anatomical location. We conducted a study on evaluation of long-term effect of modified Boytchev procedure and to compare our results with other studies published in literature.
MATERIALS AND METHODS: Since June 2002, modified Boytchev procedure was performed on 48 patients, who presented with recurrent anterior dislocation. 45 were men and 3 were women and were in the age group of 18-40 years (mean 27.83±4.95 years). Forty patients were affected on the dominant side and rest on the non-dominant side. The mean number of dislocations in these patients was 18.22±12.08. The mean followup period was 58.13±19.06 months (range 18-96 months). The patients were evaluated by visual analogue score, modified American Shoulder and Elbow Surgeon's Score (ASES), and Single Assessment Numeric Evaluation (SANE) score at the last followup.
RESULTS: All the patients regained almost preoperative range of forward flexion at the last followup. In the preoperative period the mean external rotation deficit at 0° and at 90° of abduction was 13.22°±5.16° and 18.06°±6.50°, respectively. At the last followup, the mean external rotation deficit at 0° and at 90° of abduction was 8.06°±2.47° and 8.95°±2.07°, respectively. This improvement in external rotation deficit was statistically significant (P<.05). Preoperative scores were compared with the most recent followup scores for all variables with use of a paired t test. All patients had significant improvement in visual analogue score, modified American Shoulder and Elbow Surgeon's Score (ASES), and Single Assessment Numeric Evaluation (SANE) score at the last followup. Four of the patients developed superficial infection which got resolved after treating with antibiotics, and two of the patients developed transient musculocutaneous nerve paresis. There was no radiological evidence of loosening and migration of coracoid screw or any glenohumeral arthritis on subsequent followup of skiagrams in any of our patients.
CONCLUSION: Modified Boytchev procedure is an efficacious and technically simple procedure to treat recurrent anterior dislocation of shoulder.

INTRODUCTION

Recurrent anterior dislocation of shoulder is not uncommon and more than 200 different operations have been described for its treatment.1 Though the etiology of recurrent anterior dislocation of shoulder is dubious till date, three lesions are usually thought to be responsible for its recurrence; Bankart lesion, Hill and Sachs lesion and posttraumatic laxity of the subscapularis.2–4

Amongst most of the operative procedures for recurrent anterior dislocation of shoulder; relatively few of them have good result in terms of recurrence and loss of shoulder movement in followup period. Most of the surgical procedures described for recurrent anterior dislocation of shoulder are based mainly on two basic active (rotator cuff and biceps) and passive (capsuloligamentous) mechanisms. About half a century ago, Boytchev (1951),5 a Bulgarian orthopaedic surgeon, described a surgical technique for recurrent anterior dislocation of the shoulder. This procedure involves rerouting of the detached tip of coracoid process with its attached conjoined tendon (short head of biceps and coracobrachialis) along with the pectoralis minor muscle deep to subscapularis and reattaching to its anatomical location. Later, Conforty modified this procedure by rerouting the conjoined tendon of the short head of biceps and coracobrachialis only.6

On reviewing the literature and different scientific studies, theoretically it stands out that this procedure would be very effective in preventing the recurrence.6–16 However, there are few studies which criticize the procedure.1718 In order to overcome the ambiguity over the procedure, we conducted a study on on evaluation of long –term result of Modified Boytchev Procedure and to compare our results with other studies published in literature.

MATERIALS AND METHODS

Since June 2002, the modified Boytchev procedure was performed on 48 patients, who presented with recurrent anterior dislocation of shoulder and were in the age group of 18-40 years. 45 were men and 3 were women, the mean age being 27.83±4.95 years. Forty patients were affected on the dominant side. Three of the male patients were professional district level football player. The mean number of dislocations in these patients was 18.22±12.08 times [Table 1]. Patients who had less than three anterior dislocations, bilateral dislocation, multidirectional instability, neuromuscular disorders, epilepsy, abnormal mental status, and those lost to followup were excluded from the study. All patients had a traumatic onset of symptoms and had a failure of initial nonoperative management. One of them had initial failure of Putti Platt operation, which was done three years ago. Thirty-eight patients presented with radiographs taken before reduction, which showed an anterior dislocation, however, radiographs of six shoulders showed anterior instability with small Hill-Sachs lesion(less than 15% of the humeral head).

Table 1

Demographic data

Each of them had objective and subjective measurements in preoperative and followup period at 1 month, 3 months, 6 months, 1 year, and yearly thereafter. All recording of data was done on case record form. The case record form included patient's questionnaire, subjective and objective clinical measurements for analysis of result. Each subject underwent a physical examination after he or she had completed the patient questionnaire, which included the patients profile, pain and functional status of the affected shoulder in comparison to the normal shoulder in terms of 100 percentages scale (ASES Score, SANE Score). The affected shoulder was compared with the contralateral shoulder in terms of range of motion, strength (Manual Muscle Testing), and shoulder stability (apprehension test, load and shift, sulcus sign).19 Range of motion was examined in forward flexion, and external rotation at 0° and 90° of abduction.

Operative procedure

Under general anesthesia and in supine position, 10 to 12 cm skin incision was made over the deltopectoral groove starting proximally between the clavicle and coracoid process and extending distally. Deep fascia was divided and the dissection was carried deep in the deltopectoral groove, taking care of cephalic vein. Pectoralis major was retracted medially and deltoid laterally to expose the coracoid process with attached conjoined tendons of coracobrachialis and short head of biceps brachii muscles. From anterior end of horizontal part of coracoid process, a drill hole was made along its axis. Osteotomy was done at about 1.5 cm proximal to the tip of coracoid process. The free part of coracoid along with attached conjoined tendons was mobilized distally, taking extreme care to avoid injury to musculocutaneous nerve. Just proximal to lower border of subscapularis, its fibers were split carefully (taking care of anterior circumflex humeral vessels) and a tunnel was created between subscapularis and shoulder capsule. The osteotomised tip of coracoid process with attached conjoined tendons was passed through this tunnel and fixed to the predrilled proximal part of coracoid process with a screw, while the assistant held the arm in flexion internal rotation at shoulder and flexion at elbow [Figure 1]. Hemeostasis was achieved, suction drain placed, and the wound was closed in layers. Arm was immobilized by arm to chest bandage maintaining flexion, adduction, and internal rotation of shoulder. After removal of stitch at 2nd week, passive pendular movement and abduction was allowed and from third week onwards active movement was advocated. After 8 weeks, the patient was allowed to do the normal activities.

Figure 1

(a) Intraoperative photograph showing drilling of coracoids process before osteotomy. (b) Preparation of path for rerouting of detached conjoined tendon deep to subscapularis. (c) Reattachment of detached conjoined tendon by one cortical screw in anatomical position

Comparisons were made between preoperative and postoperative outcome scores. All comparisons were analyzed with use of a paired Student t test for significance.

RESULTS

Our followup period ranged from 18 months to 96 months with a mean of 58.13±19.06 months. Results were analysed in terms of recurrence, range of motion, VAS score, modified ASES score, and SANE score.20–22 None of the patients had recurrence. All the patients regained almost preoperative range of forward flexion at the last followup. In the pre-operative period, the mean external rotation deficit at 0° and at 90° of abduction was 13.22°±5.16° and 18.06°±6.50°, respectively. At the last followup, the mean external rotation deficit at 0° and at 90° of abduction was 8.06°±2.47° and 8.95°±2.07°, respectively [Table 2]. This improvement in external rotation deficit is statistically significant (P<.05). Pre-operative deficit in external rotation of shoulder was due to apprehension of dislocation, which increased in immediate postoperative period due to pain. Evaluation of the patients in preoperative and at followup showed that neither of them had any decrease in strength, nor anyone showed a positive load and shift test, sulcus test or any signs of hyperlaxity. Thirty-eight patients demonstrated a positive apprehension sign in the preoperative period.

Table 2

Loss of motion compared to opposite normal side - Mean ± standard deviation (range)

Preoperative scores were compared with the most recent followup scores for all variables with use of a paired- t test. All patients had significant improvement in VAS score, modified ASES score, and SANE score at the last followup after the procedure. Analysis using Pearson's coefficient correlation of data between modified ASES score and SANE score show statistically significant linear correlation [Table 3]. Each of the patients, including the professional football players, returned to the preoperative level of their respective activity. Four patients developed superficial infection, which got resolved after antibiotics as per the culture and sensitivity report. Two patients developed transient musculocutaneous nerve paresis that got resolved spontaneously within three months. There was no radiological evidence of Lossening, migration of coracoid screw or any glenohumeral arthritis on subsequent followup in any of our patients [Figure 2].

Table 3

Shoulder score and statistical analysis

Figure 2

Preoperative (a,c) and followup (b,d) skiagrams of shoulder (anteroposterior views) of two patients showing no glenohumeral osteoarthrosis, screw migration in followup period

DISCUSSION

The modified Boytchev procedure is biomechanically sound that acts by two possible mechanisms: dynamic muscular sling effect89 and improved shoulder joint proprioception.10 The subscapularis is pulled forward by the rerouted conjoined tendon during elevation of the shoulder thereby causing an increase in the lever arm and enhancing the internal rotational moment arm. When the arm is in the vulnerable position of abduction and external rotation, the rerouted muscles prevent the superior displacement of the subscapularis and dislocation. The anterior dislocation of the humeral head is prevented by the increased muscle bulk composed of the subscapularis, coracobrachialis and the short head of the biceps which enhances the bracing effect over the anteroinferior aspect of the glenohumeral joint. Since the rerouted muscles have to pass through a longer course, deep to the subscapularis, the tension within them increases which counteracts the physiological dislocation action of the subscapularis which is responsible for anterior dislocation of the shoulder. Biomechanical study of Halder et al.23 and cadaveric study of Jiang et al.7 provides valid scientific reason for prevention of recurrence after modified Boytchev procedure. Study by Shibata et al.10 revealed that the efficacy of modified Boytchev procedure was not only due to the muscular sling effect but improved shoulder proprioception also played an important role in prevention of shoulder dislocation. Conjoined tendon transfer led to an increase in the pressure between the humeral head and the subscapularis tendon, which leads to stimulation of mechanoreceptors which in turn improves shoulder joint proprioception. This improvement in proprioception led to improvement of reflex which was responsible for protection against shoulder dislocation.

Review of scarce literature on Boytchev procedure [Table 4] and our study indicates that modified Boytchev procedure is no more controversial.6–16 Most of studies show good result in terms of recurrence and restriction of movement. We think that this operative procedure did not gain popularity because it was originally described in Bulgarian language and that made it inaccessible in most of the countries. The First Scandinavian-Japanese Shoulder Congress24 held in 1989 and thereafter successive meetings made this procedure known to the Asian countries. Since 1990 till date, most studies from this part of the world have given good results and valid scientific study has led us to recommend modified Boytchev as an effacacious operative procedure for treatment of recurrent anterior dislocation of shoulder.

Table 4

Reported results of modified Boytchev procedure

The prime goal of any operative procedure for recurrent anterior dislocation of shoulder is directed towards prevention of recurrence. On review of literature,25 many studies show that low Rowe Score following an open procedure was not due to high recurrence but was due to diminished range of motion or function, whereas a low Rowe Score following an arthroscopic procedure is due to high recurrence. When the individual recurrence score of these two procedures are matched open procedures gain superiority over the arthroscopic procedures. Inspite of high Rowe score associated with arthroscopic procedures, open procedures are better as because more than half of the Rowe score is attributed to functional evaluation, while the stability contributes to less than 1/3rd of the total Rowe score. So the use of Rowe Score to compare the results in term of recurrence is one of the limitations. Systemic review and meta-analysis of literature shows open procedure for recurrent anterior shoulder instability are more reliable than arthroscopic procedures. Pooled data demonstrates significantly lower risk of recurrent instability, dislocation, and re-operation after open procedure. On comparison with other common open procedures, it was found that low Rowe score was due to diminished range of motion. So in order to minimise it, we followed a rehabilitation program26 with special attention to strengthening exercises of the conjoined tendon that probably resulted in good range of motion with minor restriction in our study.

The incidence of recurrence reported after the Bankart, Putti-Platt, and Bristow laterjet procedure ranged from 2 to 10%, 0 to 12.5%, and 2-10% respectively, with restriction of external rotation (average 10°) and glenohumeral osteoarthrosis in long term followup study. Athletic individuals with involvement of the dominant shoulder were not capable of returning to high performance levels of overhead sports activity (particularly throwing) after the operation in followup period. All these procedure require expertise and long learning curve. On comparison with other procedures for treatment of recurrent anterior dislocation of shoulder, modified boytchev procedure had comparable result in term of recurrence, range of motion, and complications.

Hence this procedure fulfils most of the criteria of an ideal procedure27 for recurrent anterior dislocation of shoulder and allows us to conclude that this procedure is an effective procedure, technically simple, and does not require expert skills or any sophisticated instruments and can be performed by all orthopaedic surgeons where basic operative facility is present.