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PERFORMING THE LATARJET PROCEDURE WITH DEDICATED INSTRUMENTS
L. Doursounian, A. Debet-Mejean
Article Summary

INTRODUCTION
MATERIALS &T METHODS
Patients
Materials
Surgical technique
Evaluation
RESULTS
Complications
Clinical results
Subscapularis muscle strength
Return to sports
Radiographic results
CT results
Statistical analysis
DISCUSSION
Bone block positioning
Nonunion
CONCLUSION
NOTE
Hôpital Saint Antoine - 75012 Paris - France

INTRODUCTION

 

Recurrence of dislocation after a first episode requires surgical treatment in one out of four cases.1 Many different procedures have been described so far, which can be broken down into two main categories: surgical procedures on soft tissue are considered more anatomical (e.g. Bankart procedure, the gold standard); those using a bone block were pioneered by Latarjet.

 

Although the Latarjet procedure (in which a coracoid bone block is positioned flush with the anterior-inferior border of the glenoid) was questioned because of the many complications reported,2-8 and in spite of the boom of arthroscopic techniques, it is still extensively used in Europe as primary surgery or after a failed Bankart repair. The bone block can be positioned either horizontally or vertically.9-13 As regards exposure, horizontal sectioning of the subscapularis has become more popular than vertical sectioning in the last few years.3,11-15 Whatever the orientation of the bone block, the tricky thing is to accurately position the transplant through a subscapularis-sparing approach.3,16 Dividing the muscle in line with its fibers does not offer such a good exposure as vertical sectioning, but it has the advantage of better preserving anatomical and functional structures.17 The deleterious consequences of malpositioning and nonunion of the bone block are well documented in the literature:10,16,18-26 recurrence of instability if the bone block is too medial or ununited, osteoarthritis if the bone block overhangs. Therefore, it is critically important to correctly position the coracoid bone block while preserving the subscapularis as much as possible. This has prompted us to develop a dedicated set of instruments that would allow optimal preparation, positioning and fixation of the bone block. These instruments were successfully used in a consecutive series of patients operated on by the same surgeon between 1999 and 2005, as optimal and reproducible vertical positioning of the coracoid bone block could be achieved. A retrospective study was conducted on 34 patients, 27 of whom were reviewed at a mean follow-up of 24.4 months. Twenty-seven patients were clinically evaluated, 23 radiologically evaluated, and 11 had an MRI.

 

 

MATERIALS &T METHODS

Patients

The series involved 34 patients operated on between March 1999 and January 2005. There were 31 males and 3 females with a mean age of 32 years (range, 20–58 years). The dominant side was involved in 95% of the cases. The average interval between the first episode of dislocation and surgery was 5.2 years (range, 0.5–30 years). There had been at least 2 episodes of dislocation in 30 patients, and subluxations in 4. Ten patients suffered chronic pain. No patient had had previous surgery in the affected shoulder. Only one of the 34 patients had hyperlaxity. Preoperatively, the patients had a complete clinical examination performed by the same physician, a standard radiographic evaluation, and 45% of them had a CT scan. There was glenoid erosion in 28 patients, glenoid fracture in 5, and no glenoid lesion in 1. A Hill-Sachs lesion was present in 31 patients. There was no preoperative osteoarthritis. Eleven patients were engaged in sports that require cocking such as tennis and rock climbing, 6 in resisted-throwing sports (e.g. karate), and 10 in very low-risk sports such as jogging and diving.

Materials

The system includes an implant and an instrument set (Orthomed S.A., St Jeannet, France). The implant consists of a titanium glenoid screw anchor and a compression screw (Figs. 1a & b). The instrument set includes basically 3 instruments : a unique and yet simple tool which serves both as a diameter measuring gauge (10 and 12 mm) for the coracoid process and as a guide to perform the resection at the appropriate level (i.e. where the bone block will have the desired diameter) (Fig. 2); a cannulated awl (Fig. 2) to place the bone block and mark the position with its pointed shaft (Fig. 3); a cannulated counterbore drill (ø 10 or 12 mm) which drills and counterbores in one operation: first, the hole for the glenoid screw anchor is drilled, then the cylindrical housing for the base of the coracoid bone block is prepared with the counterbore (Fig. 4). The bone block is secured by a titanium glenoid fixation screw (length 21 mm, diameter 5.8 mm) that acts as an anchor. It receives the compression screw (length 30 or 35 mm, diameter 3 mm) which provides secure fixation and compression of the bone block.

 

 a

 b

Fig. 1: a) Glenoid screw anchor for insertion into the anterior rim of the glenoid. It is intended to accommodate the compression screw (b).

 
Fig. 2: Two-pronged retractor/measuring gauge (10 and 12 mm).

a

b

Fig. 3: a) Cannulated awl/shaft assembly; b) pointed shaft is partially retracted.

 
Fig. 4: Cannulated counterbore drill for drilling of the screw anchor hole and preparation of the bone block housing.

 

Surgical technique

 

The patient is usually positioned supine on the operating table with a small cushion placed under the medial border of the scapula to maintain the shoulder in a lateral position (Fig. 5). The upper extremity is draped free and prepped, and a stockinette is applied. The procedure is performed using a deltopectoral approach (Fig. 6). A retractor is placed above the coracoid process to obtain adequate exposure. Medial and lateral attachments to the coracoid process are released off the bone. The coracoid bone block (12-15 mm long) is harvested with the insertion of the coracobrachialis using a bone chisel or an oscillating saw (Figs 7a & b).

 

Due to the close proximity of the musculocutaneous nerve, extreme caution should be used when mobilizing the bone block (Fig. 8). The bone block is drilled throughout its length using a 3.2 mm drill (Fig. 9) for later insertion of the compression screw. The base of the bone block is shaped into a calibrated cylinder (Figs 10a & b) so that it fits one of the measuring gauge holes (10 or 12 mm) (Fig. 11). Next, the subscapularis muscle is incised in line with its fibers at the junction of the distal one-third and proximal two-thirds (Fig. 12). The joint capsule is exposed and a horizontal capsulotomy is performed (Fig. 13). Then, the anterior-inferior surface of the glenoid is exposed by inserting a Hohmann retractor under the glenoid (Fig. 14). Any labral or capsular tissue that interfere with placement of the bone block should be excised. The bone block is loaded onto the cannulated awl and positioned flush with the anterior-inferior border of the glenoid (Figs. 15a & b). Once the correct position has been determined, the awl is hammered into the bone. The awl shaft is unthreaded and removed (Fig. 16). A guide pin is inserted into the cannulated awl and driven into the glenoid to a depth of 3 cm (Figs. 17a & b). Then, the awl is removed and the guide pin is cut flush with the surface of the bone block (Figs. 18a & b). The bone block is removed and preserved for subsequent fixation. Thus, the position of the transplant is accurately defined and marked for the rest of the procedure.

The cannulated counterbore drill is used over the guide pin. First, the hole for the glenoid screw anchor is drilled. Then, as the proximal end of the instrument is advanced, the counterbore for the bone block is drilled (Fig. 19). After the guide pin has been removed, the glenoid screw anchor can be inserted and fully countersunk in the bone (Figs. 20a & b). The compression screw is inserted through the bone block and threaded into the screw anchor (Figs. 21a & b).

Being associated with a metal anchor, the screw features many more threads than a normal bone screw and provides compression of the bone block. Care should be taken to position the bone block such that its wide side faces the humeral head, and to fully seat it in the prepared housing. Museux forceps are used to test for perfect stability of the transplant. Once the bone block is securely fixed, it is recommended to check for the absence of impingement between the bone block and the subscapularis in external rotation, and between the bone block and the humeral head (Figs. 22a, b, c). The subcutaneous and cutaneous layers are sutured and a Redon drain is routinely placed. A postoperative x-ray is mandatory to appreciate the quality of the repair (Fig. 23). Postoperatively, the patient is immobilized with elbow close to body for approximately 10 days. Physical therapy is initiated the first postoperative week.

 
 Fig. 5: Patient in supine position with a small cushion placed under the shoulder, medial to the scapula, in order to resist medial translation. A small armboard can be used as long as it is not in the surgeon's way (some surgeons like to stand at the patient's armpit, others lateral to the shoulder joint).
 
Fig. 6: Deltopectoral incision starts at the tip of the coracoid process.

a

b

Fig. 7: a) Fibrous tissue overlaying the coracoid process is opened with electrocautery at resection level (b).
 
Fig. 8: As the musculocutaneous nerve enters the coracobrachialis within only a few centimeters of its coracoid insertion, great caution should be used when mobilizing the coracoid bone block. Also, careful handling is recommended during shaping of the bone block.
 
Fig. 9: When drilling the compression screw hole through the coracoid bone block, the drill should be directed toward the tip of the bone block.

 ab

Fig. 10 (a, b): The resected surface of the bone block is shaped using an oscillating saw or a gouge to fit the 10 or 12 mm hole of the measuring gauge.
 
Fig. 11: The coracoid bone block should pass the 10 or 12 mm hole by at least 3 mm.
Fig. 12: The subscapularis is incised in line with its fibers at the junction of the distal one-third and proximal two-thirds.
 

 
Fig. 13: Adequate exposure of the capsule is provided by placing a curved Beckman-type self-retaining retractor.

 a

b

Fig. 14: a) The anterior-inferior border of the glenoid is exposed. The inferior Hohmann retractor is inserted into the joint and placed along the inferior border of the glenoid to retract the distal one-third of the subscapularis inferiorly; b) the bone block is loaded onto the cannulated awl.

 a

b

 Fig. 15 (a, b): The coracoid bone block is postioned flush with the anterior-inferior border of the glenoid.
 
Fig. 16: Awl shaft is removed.

 a

b

Fig. 17 (a, b): A guide pin is inserted through the cannulated awl and driven into the glenoid to a depth of 3 cm (approx.).

 a

b

Fig. 18 (a, b): The guide pin is cut flush with the surface of the bone block.
 
Fig. 19: The cannulated counterbore drill is used over the guide pin to drill the hole for the glenoid screw anchor.

 a

b

Fig. 20 (a, b): The glenoid screw anchor is inserted and fully countersunk in the bone.

 a

b

Fig. 21 (a, b): The compression screw is inserted through the bone block and threaded into the screw anchor. This takes some time because of the great number of metal threads. Care must be taken not to overtighten the compression screw and crush the bone block!

 a

b

c

Fig. 22: a) The bone block should easily and fully seat in its housing; b, c) check for the absence of impingement between the bone block and the subscapularis in external rotation.
 
Fig. 23: Postoperative radiograph (AP view) showing the bone block in situ.

 

Evaluation

 

All the patients (n=34) were reviewed at between 3 and 6 months postoperatively for assessment of the anatomical, radiographic, and functional outcome. Seven patients were lost to follow-up after this first evaluation. A second evaluation was performed at an average of 24.4 months (range, 7–74 months) by an independent observer. Twenty-three patients were clinically and radiologically evaluated and 4 were evaluated by telephone interview. Patients were questioned about instability, stiffness, sensation of loss of strength, activities, and level of sports activity. The clinical result was assessed by the Duplay score and the Constant score. Ranges of motion were measured using a goniometer. ER1 (elbow at the side) only was measured for comparison with the intact contralateral side. The subscapularis strength was tested by the hand behind back lift-off test using a spring-scale dynamometer: the examiner stood in front of the patient, loops were secured to either end of the device and held by the patient and the examiner respectively. The patient was asked to hold his hand behind his back at waist level and move the arm away from the body against resistance from the examiner (Fig. 1). The subjective result was rated based on the level of satisfaction of the patient: "very satisfied, satisfied, disappointed, dissatisfied."

 

Twenty-three patients were radiologically evaluated using an A/P view of the shoulder, a "Y" view, and a lateral view of the glenoid. Evaluation focused on evidence of nonunion and lysis, fracture or migration of the bone block. The vertical position of the bone block relative to the equator (as described by Hovelius et al.)10 was assessed on AP and "Y" views. The position of the bone block relative to the joint line was measured in millimeters on a lateral view of the glenoid. The examiner also checked for the absence of protrusion of the screw into the posterior fossa. The Samilson27 criteria were used to classify osteoarthritis of the shoulder (if any).

Eleven patients had unenhanced CT scans of their operated shoulder (Fig. 24). A series of thin bone window CT sections (in 2 mm increments) was obtained in both the sagittal and coronal planes. Axial scans were obtained parallel to the coracoid screw. This CT study provided detailed information on bone block healing status, presence of degenerative changes, and lysis of the bone block. It further allowed to establish the position of the coracoid bone block in all planes. Position of the bone block relative to the joint line was measured on axial scans.

All the data were computed in a database (Microsoft® Excel 2000). The non-parametric Wilcoxon test for paired samples was used to compare continuous variables. The following variables: internal rotation, external rotation, Constant score, Duplay score were compared to the normal value. The variable "subscapularis muscle strength" was compared to the contralateral side.

 

 
 Fig. 24: CT analysis
 
Fig. 25: Assessment of bone block position. Note the slight protrusion of the glenoid screw anchor into the posterior fossa.

 a

b

Fig. 26 (a, b): Radiographs showing a coracoid bone block at 6 months postop.

 
 Fig. 27: Bone block is placed too laterally and overhangs.
 
Fig. 28: Bone block is placed too medially and is ineffective.

 
Fig. 29: Axial CT image showing a well-positioned bone block.

Fig. 30: CT scan image of a nonunion.
 
Fig. 31: Secondary loosening of a coracoid bone block. Note the incorrect shaping of the bone block which could not seat in its housing.

RESULTS

Complications

A superficial scar infection occurred which was treated topically and did not affect the overall result. There were no neurovascular complications in this series.

Clinical results

• Subjective results

The overall satisfaction rate was 92%. Of the 27 patients interviewed, 14 were very satisfied, 11 were satisfied, and 2 were disappointed.

Objective results

Of the 23 patients examined, 15 had an excellent Duplay score (90-100 points), 4 a good score (76-90 points), 3 a fair score (60), and 1 only a poor score (50). Overall, 86.6% of the patients had a good or excellent score. On average, the Constant score was 93.5% (range, 86-100%) of that of the contralateral side. 

• Stability

Of the 27 patients interviewed, 1 patient had subluxation events. One patient was reoperated on for redislocation caused by a high-energy injury sustained 3 months after the initial procedure when playing rugby. After revision surgery, this patient was satisfied and had a stable shoulder. In the 23 patients who were clinically reviewed, only the patient who had recurrent subluxation showed apprehension in arm cocking; none of them complained of a sensation of instability.

• Range of motion

 

Forward elevation and abduction of the operated shoulder were not affected in our series.

 

On average, loss of internal rotation was 1 vertebra (range, 0-7 vertebrae) and loss of external was rotation 7.1° (range, 0-40°).

In 3 patients only was loss of external rotation greater than 20 degrees as compared to the healthy side. Those patients who were interviewed by telephone did not report decrease in range of motion (ROM).

 

Subscapularis muscle strength

On average, patients had 14% (range, 0–35%) loss of subscapularis strength as compared to the healthy side. As regards pain, 88% of the patients stated that they felt no pain or only minimal pain on strenuous activity.

Return to sports

On average, patients could return to sports 6 months (range, 3–12 months) after surgery. Sixteen of the 22 athletes (72%) returned to their previous level of performance. One athlete returned to the same sport at a lower level of competition, 3 amateur athletes still participate in sports occasionally, 2 have given up sports altogether. Therefore, 90% of the patients resumed athletic activities after their operation.

Radiographic results

 

One out of the 23 patients who were radiographically followed had grade 1 osteoarthritis with an otherwise excellent functional outcome. Standard radiographs showed that all bone blocks were in a subequatorial position. On lateral views of the glenoid, all bone blocks were located within 1-2 mm of the joint line (Figs. 26a & b).

 

One nonunion (4.3%) with loosening of the coracoid screw was diagnosed from the standard x-rays in the patient who had subluxation events. Five patients had lysis of the proximal one-third of the bone block around the screw head, without this affecting the overall result. In one patient, the bone block had completely disappeared 9 months after surgery. Still, the overall objective result was good, the shoulder was stable, and the patient felt mild pain. In 15 patients, the glenoid screw anchor protruded out of the posterior cortex of the glenoid.

 

CT results

 

One out of the 23 patients who were radiographically followed had grade 1 osteoarthritis with an otherwise excellent functional outcome. Standard radiographs showed that all bone blocks were in a subequatorial position. On lateral views of the glenoid, all bone blocks were located within 1-2 mm of the joint line (Figs. 26a & b).

 

One nonunion (4.3%) with loosening of the coracoid screw was diagnosed from the standard x-rays in the patient who had subluxation events. Five patients had lysis of the proximal one-third of the bone block around the screw head, without this affecting the overall result. In one patient, the bone block had completely disappeared 9 months after surgery. Still, the overall objective result was good, the shoulder was stable, and the patient felt mild pain. In 15 patients, the glenoid screw anchor protruded out of the posterior cortex of the glenoid.

 

Statistical analysis

External rotation was significantly decreased as compared to normal value (p=0.14). Constant score (p ≤ 1.10-3) and Duplay score (p ≤ 1.10-3) were both significantly different from normal value. Subscapularis strength was significantly less on the operated side than on the healthy side (p ≤ 1.10-3). However, there was no significant decrease in internal rotation (p=0.098).

 

DISCUSSION

 

Since it was described in 1954 and 1958,28-29 the Latarjet technique has been extensively used for treatment of recurrent anterior dislocation of the shoulder. For a long time, the joint was approached by sectioning the subscapularis muscle. This of course afforded excellent exposure but required suture repair which was associated with a certain amount of morbidity. The L-shaped incision used by Patte30 allowed preservation of the inferior one-third of the muscle which could therefore be used as a hammock and helped stabilize the humeral head. Today, most authors3,11-15,23 make a horizontal incision at the junction between the middle and distal thirds of the subscapularis, thus reverting to the initial technique advocated by Latarjet28,29 and Bristow.31 It is now recognized that division of the muscle in line with its fibers is much preferable to vertical sectioning which seems to be associated with a higher incidence of fatty muscle degeneration.17,32-33 This muscle atrophy would seem to be responsible for a loss of external rotation32-33 or internal rotation17 and, above all, for a loss of strength in internal rotation.32,33 Furthermore, Decker's works34 show that the upper and lower subscapularis work independently, which supports the idea that the horizontal approach is more anatomical. It has indeed the advantage of better preserving the anatomical and functional structures, but it does not offer such a good exposure as vertical sectioning, making the procedure technically more demanding. According to Matton,3 poor visibility of the joint makes it more difficult to correctly position the bone block.

 

Based on these findings, we felt it of interest to design special instruments that would assist in correct bone block positioning through a limited approach. Our goals were twofold: first, allow the surgeon to safely and accurately mark the position and orientation of the bone block using one single guide pin for all the instruments; second, use a glenoid screw anchor that would accommodate a bone block compression screw.

 

Bone block positioning

 

It is critically important to correctly position the coracoid bone block in both the vertical and horizontal planes.10,14,18-21 Correct positioning is more difficult to achieve when a conventional horizontal approach is used.3,16 Then, correct position and orientation must be maintained at all times until the fixation screw is tightened, which is not easy particularly during drilling and screw tightening, even if the bone block is firmly held with Museux forceps. Thanks to the cannulated awl, the bone block can be easily handled and accurately positioned. Once optimal position has been determined, the assistant firmly holds the awl while the guide pin is being inserted. This step is critical as this pin will serve as a guide for all the instruments in the subsequent steps. The coracoid bone block is removed, leaving the guide pin in place as it will be helpful later on to check for correct positioning (below the equator) and orientation (relative to the horizontal plane) of the transplant. This dedicated instrument set provides a highly reliable and reproducible method for correct positioning of the bone block.

 

Many authors have studied the position of the bone block on standard radiographs. In 56 patients operated by the Latarjet technique, Allain et al.20 noted that 53% of the bone blocks were placed too laterally and 5% too medially, the remaining bone blocks being optimally positioned. In the Cassagnaud's series,21 CT analysis revealed that more than 10% of the bone blocks were overhanging. Hovelius10 reported 36% malpositioning (i.e. above the equator) and 6% medial positioning. In Huguet's series,18 45% of the bone blocks overhung the joint. All these works stressed the importance of the bone block position which is directly related to the outcome: if it is too lateral and overhanging (Fig. 27), it is bound to cause osteoarthritis to develop over time3,10,16,18,21,22,25-26 and limits internal rotation due to impingement upon the humeral head;18 if it is too medial (Fig. 28), it is a source of recurrent instability;10,18,35 lastly, if it is located above the equator, it exposes the joint to recurrent dislocation.10 It is difficult to define an optimal position but it is generally held that it should be located below the equator, neither too medial nor too lateral (less than 10 mm from the cartilage for some authors,10 less than 2 mm for others18). According to some surgeons, it should be flush with the damaged glenoid surface so as to increase the joint surface area. According to Goutallier,36 increasing the glenoid joint surface area helps prevent Hill-Sachs lesions and thus avoid recurrent anterior dislocation resulting from the cam effect. In our series, no bone block overhang was observed on the standard radiographs. The CT study showed that 8 bone blocks were flush with the anterior-inferior border of the glenoid (within 1-2 mm of the rim) (Fig. 29), one was in a more medial position (within 4 mm of the rim) but was very stable, and three were located 1 mm from the bone surface with no visible arthritic lesions. In the patient with glenohumeral osteoarthritis, the bone block was located within 1-2 mm of the joint line.

Furthermore, the CT analysis revealed that some bone blocks which were radiographically very close to the joint line were actually quite distant from the cartilage. As regards transplant obliquity relative to the joint line, findings were inconclusive due to the disparity in measurements. However, there is a possibility that it plays a role in impingement between the bone block and the humeral head. It would be interesting to perform a large scale CT study over a longer time span to better evaluate the correlation between the obliquity of the bone block and the occurrence of glenohumeral osteoarthritis.

As to the position relative to the equator, all bone blocks in this series were positioned below the equator, and the radiographic findings were confirmed by the CT scans.

 

Nonunion

 

In our series - admittedly of small size - only one out of the 23 bone blocks which were radiographically evaluated did not heal (Fig. 30). In the literature,3,9-16,18-21,23,24,33,37 the nonunion rate is highly variable and ranges from 0 to 50%. Many authors showed that nonunion of the bone block does have an impact on the outcome. For Cassagnaud,21 nonunion affects all revision parameters. For Hovelius,10-11 it is associated with an increased rate of postoperative instability. For Guity,38 it is a source of pain, and for Wymenga,9 it affects range of motion.

 

Strength of the construct depends both on decortication of the anterior-inferior border of the glenoid and on quality of fixation of the bone block. Position varies from one surgeon to another. Horizontal bone blocks fixed with two screws would seem to be less prone to nonunion than vertical bone blocks, but this is not documented in the literature. However, it is not unreasonable to assume that a bone block placed in the vertical position is more stressed by the coracobrachialis. Also, it definitely offers a smaller contact surface with the glenoid and cannot accommodate more than one fixation screw. The instruments we have developed address all these issues.

With conventional instruments, decortication of the anterior-inferior border of the glenois is performed with a curette. Besides the lack of reproducibility of this technique, it is often limited to the superficial cortical bone. The cannulated counterbore drill that we have developed provides optimal circumferential decortication. It allows the creation of an appropriately sized and shaped cavity to accommodate the bone block, with a controlled depth to offer a cancellous bone bed that promotes healing. Recession of the bone block minimizes the impact of the coracobrachialis moment arm. In addition, fixation of the bone block has been optimized. An original system has been designed which consists of a glenoid screw anchor and a coracoid screw, providing compression of the bone block. The conventional fixation method described in the literature uses either a 3.5 mm bicortical screw or a 4.5 mm malleolar screw. The complications associated with this method are well documented. Huguet,18 Walch,35 and Vander Maren22 claimed that 3.5 mm screws were likely responsible for a great number of complete lyses, and 4.5 mm screws might be the source of fractures due to their large diameter. Therefore, a trade-off had to be made between a bulky screw which provides strong fixation and a small-diameter screw which does not weaken the bone block. Our system consists of a screw with a small proximal diameter (3 mm) that is threaded into a larger diameter anchor which provides the strong fixation that is necessary to allow compression of the bone block. Only one complete lysis occurred in our series.

Furthermore, some authors believe that only a bicortical screw can provide stable fixation.10,22 But a bicortical screw may be too long as seen in 75% of the cases in Banas' series.14 According to Cassagnaud,21 bicortical screws protrude into the infraspinatus fossa and cause pain. According to Guity,38 they are responsible for a loss of external rotation.

Our glenoid screw anchor should address these issues since it does not require bicortical purchase to provide strong fixation. However, 15 out of 23 screw anchors were found to protrude into the posterior fossa, which prompted us to reduce the length of the screw anchor. But this new anchor has two drawbacks. First, it so tightly captures the coracoid screw that it makes it difficult to control the torque load and places the bone block at risk of fracture. A specially designed torque screwdriver could provide a solution. Another issue is the difficulty to remove the screw anchor which is fully countersunk. This could potentially be a problem should the patient need a total shoulder prosthesis. Pihlajamäki37 had an interesting idea that deserves further investigation: a bioabsorbable device. But of course, it should be able to maintain strong fixation for the time necessary to achieve good healing.

Our well-thought-out instruments have made our surgical technique rather straightforward and highly reproducible when compared to other techniques using conventional instruments. Thanks to our standardized surgical protocol which uses the same guide pin throughout the procedure, the learning curve has been significantly shortened, which is easily understandable. The reason is that both positioning and fixation of the bone block are mainly a matter of personal experience and feeling, so that teaching this technique to young surgeons is not an easy task. With our guide pin, one can objectively evaluate the position of the bone block and, in case of malpositioning, get trainees to understand what went wrong. Still, whatever the equipment used, this procedure requires extreme caution (i.e. avoid injury to the musculocutaneous nerve, check for the absence of soft tissue under the bone block during screw tightening, for the absence of impingement upon the capsule etc ....).

 

CONCLUSION

This retrospective study involved 34 patients with recurrent anterior instability of the shoulder who were surgically treated over a period of 5 years by the Latarjet technique using dedicated instruments. The results are similar to those achieved with conventional instruments. Both subjective and objective clinical results are good with 92% satisfaction, 86.6% good or excellent Duplay score, and good stability in 92% of the shoulders. Bone blocks were correctly positioned (i.e. no overhang or medial positioning) and nonunion rate was only 4.3%. Therefore, it can be concluded that thanks to our equipment, the Latarjet procedure is now standardized, accurate and reproducible, and can be performed without detaching the subscapularis. In addition, this equipment assists in correct positioning of the transplant and provides stable and reliable fixation.

 

NOTE

 

Since this study was published (Bristow-Latarjet procedure with specific instrumentation: study of 34 cases. Doursounian L, Debet-Mejean A, Chetboun A, Nourisssat G. Int Orthop. 2008 Jul 17), a number of procedures have been performed and many patients have been reviewed. Furthermore, as this equipment has been routinely used by other surgical teams, we have been able to compare findings. As a matter of fact, their conclusions are most favorable and consistent with ours. Still, a few complications have been reported by some authors which we must make mention of to help surgeons prevent them.

 


Before using the guide pin with the cannulated awl, it is recommended to check for free passage through the cannulated counterbore drill to avoid the risk of migration or fracture of the pin during drilling. After drilling, the guide pin must be removed to avoid the risk of migration during insertion of the glenoid screw anchor.

Insertion of the screw anchor cannot be achieved with a standard screwdriver, a special 3 mm diameter screwdriver must be used.

Secondary loosening of the coracoid bone block is typically due to faulty preparation or poor compression of the bone block. A bone block that is not properly sized will not fit in its housing (Fig. 31). Although it may seem fully seated, it is not bottomed out. As a result, there is not full contact and congruency within the prepared cavity. The same occurs when soft tissue is entrapped between the bone block and the glenoid bone. It is therefore highly recommended, after drilling, to check for the absence of transplant-bone interface gaps with the tip of forceps or a spatula, and to assess stability of the bone block using Museux forceps to ensure that there is no rotational play.

In one uncontrollable patient, the surgical wound reopened and glenohumeral osteoarthritis developed. The patient underwent arthroscopic revision which confirmed that the bone block was still well fixed and functional. After careful lavage, arthroscopic synovectomy and appropriate antibiotic therapy, the patient did well.

 

 

References

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2. Young DC, Rockwood CA Jr. Complications of a failed Bristow procedure and their management. J Bone Joint Surg Am. 1991 Aug;73(7):969-81.
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4. Stromqvist B, Wingstrand H, Egund N. Recurrent shoulder dislocation and screw failure after the Bristow-Latarjet procedure. A case report. Arch Orthop Trauma Surg. 1987;106(4):260-2.
5. Bach BR Jr, O’Brien SJ, Warren RF, Leighton M. An unusual neurological complication of the Bristow procedure. A case report.
J Bone Joint Surg Am. 1988 Mar;70(3):458-60.
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Maîtrise Orthopédique n° 182 - March 2009
 
 
 
 
 
 
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