Predictors of safety margin for coracoid transfer: a cadaveric morphometric analysis

Latarjet Procedure to Restore Glenohumeral Stability in a Patient With a Postage Stamp Fracture

The "postage stamp fracture" is an anterior glenoid rim fracture following arthroscopic repair of a Bankart lesion. Often occurring at the time of an acute trauma, a fracture line propagates though the previous Bankart repair anchor sites, resulting in recurrent anterior instability of the glenohumeral joint. The resultant glenoid rim fracture edge gives a similar appearance as the edge of a stamp, with the osseous edge having the classic "perforation" pattern. When patients present with a postage stamp fracture, even in the setting of subcritical glenoid bone loss, we believe that additional soft-tissue stabilization procedures and/or fracture fixation pose a significant risk of failure. In our opinion, a Latarjet procedure is recommended in a majority of patients with a postage stamp fracture for restoration of glenohumeral stability. The procedure offers a reliable, reproducible surgical intervention that controls for many of the factors that can make arthroscopic revision unreliable, such as poor bone quality, adhesions, labral degeneration, and bone loss. Here, we outline our preferred surgical technique to restore glenohumeral stability using the Latarjet procedure for a patient with a postage stamp fracture.

Variant pectoralis minor muscle: a case study with clinical relevance

The pectoralis minor (PMn) muscle originates from the third, fourth, and fifth ribs near the costochondral junctionusually and gets inserted on the medial margin and upper surface of the coracoid process of the scapula. To look at the morphological insertion patterns and sites of attachment of the PMn muscle in the donated cadavers. Over all 19 limbs were included in the study (9 right and 10 left). Out of 19 limbs, 10 belonged to female and 9 belonged to male cadavers. The cadavers were meticulously dissected to determine the morphological insertion types and location of the attachment of the muscle. Unusual pattern of insertion was observed in 6 limbs (31.6%) out of total 19 limbs included in the study. The variations we observed does not fall completely in the classification by Le Double, hence variations we observed can be considered as new and rare variant which to our knowledge is not reported in literature. We propose this new variant to be type 4 of Le Double classification. The potential of ectopic PMn tendon should be taken into consideration and tested out, especially in patients with shoulder discomfort and stiffening who have ruled out the more frequent diseases. For proper surgical planning, a preoperative magnetic resonance imaging or USG examination of the shoulder joint is required considering the prevalence of variation in the insertion pattern of PMn muscle. Preoperative identification of any abnormal PMn insertion can help to reduce the risk of iatrogenic tendon injury and post-operative problems.

The clinical anatomy of variations of the pectoralis minor

Shoulder pathology is a very common medical presentation and can be due to anatomical variations. Therefore, knowledge of variants is important for the clinician treating patients with such complaints so that misdiagnosis is minimized and iatrogenic injury prevented. A review of the literature was performed of the variant anatomy of the pectoralis minor muscle. The aim of this review is to better inform clinicians who might treat patients with shoulder pathology so that if identified, variants of the pectoralis minor muscle are better appreciated.

A cadaveric morphometric analysis of coracoid process with reference to the Latarjet procedure using the "congruent arc technique"

INTRODUCTION

Congruent arc Latarjet procedure involves rotating the coracoid process so that its inferior surface is flush with the glenoid face, owing to their matching radius of curvature (ROC). However, there has been no cadaveric study to actually measure and compare the ROC of coracoid with glenoid, especially in Indian population.

MATERIALS AND METHODS

44 shoulders were dissected in 24 cadavers to measure usable length of coracoid process, width, height, ROC of coracoid and glenoid as well as ulnar length (as proxy of cadaver height). Critical coracoid height and length were estimated based on screw sizes of 2.7 mm, 3.5 mm, 4 mm and 4.5 mm, and pair concordance between height and length calculated. ROC of coracoid and glenoid were compared to measure extent of congruency.

RESULTS

The mean usable length of coracoid process, width and height at mid-point were 21.8 mm, 13.7 mm and 8.6 mm, respectively. Out of the different screw sizes, 2.7 mm screws were found safe in 82% shoulders. 24 coracoid-glenoid pairs fulfilled the operational definition (≤ 5 mm) of congruency while rest 20 were seemingly incongruent chiefly due to coracoid variations, with mean ROC difference 4.13 mm (95% CI 1.51-6.74 mm). The ulnar length was significantly smaller in the incongruent ROC group (p = 0.0002).

CONCLUSIONS

The available length as well as height of the transferred coracoid must be considered when deciding optimum diameter fixation screws in Latarjet procedure. Owing to smaller anatomic dimensions of coracoid in Indian population, 2.7-mm screws provide the safest fixation option. Also, the ROC of coracoid and glenoid does not match in substantial proportion of the cadavers. Pre-operative planning should include a CT-based assessment of glenoid and coracoid dimensions to decide the technique of Latarjet procedure and the optimum diameter fixation screws required.

Arthroscopic Latarjet for Shoulder Instability

Arthroscopic Latarjet is a relatively new, but viable option for the treatment of anterior shoulder instability. Arthroscopic Latarjet has the advantage of faster recovery, reduced stiffness, identification of additional shoulder pathology, and improved cosmesis when compared with open Latarjet. By the majority of clinical and radiographic parameters, arthroscopic Latarjet produces equivalent outcomes compared with open Latarjet. A relatively substantial learning curve for arthroscopic Latarjet exists at about 25 cases; however, multiple studies have demonstrated comparable outcomes and surgical time after the learning curve.

Best implant choice for coracoid graft fixation during the Latarjet procedure depends on patients' morphometric considerations

PURPOSE

To assess the anthropometric dimensions of the coracoid process and the glenoid articular surface and to determine possible implications with the different commercially available Latarjet fixation techniques.

METHODS

In a total of 101 skeletal scapulae the glenoid length (GL), the glenoid width (GW), the coracoid length (CL), the coracoid width (CW) and the coracoid thickness (CTh) were measured. In order to assess the ability of the transferred coracoid to restore the glenoid anatomy we created a hypothetical model of 10%, 15%, 20%, 25% and 30% glenoid bone loss. We analyzed four common surgical fixation techniques for the Latarjet procedure (4.5 mm screws, 3.75 mm screws, 3.5 mm screws, and 2.8 mm button). The distances from the superior-inferior and medio-lateral limits of the coracoid using the four different fixation methods were calculated. We hypothesized that the "safe distance" between the implant and the coracoid osteotomy should be at least equal to the diameter of the implant.

RESULTS

The intra and inter-observer reliability tests were almost perfect for all measurements. The mean GH was 36.8 ± 2.5 mm, the GW 26.4 ± 2.2 mm, the CL 23.9 ± 3 mm, the CW 13.6 ± 2.mm, and the mean CTh was 8.7 ± 1.3 mm. The CL was < 25 mm in 46% of the cases. In cases with 25% and 30% bone loss, the coracoid graft restored the glenoid anatomy in 96% and 79.2% of the cases. With the use of the 4.5 mm screws the "safe distance" was present in 56% of the cases, with the 3.75 mm screws in 85%, with the 3.5 mm screws in 87%, and with the 2.8 mm button in 98% of the cases. The distance from the medio-lateral limit of the coracoid could be significantly increased (up to 9 mm) when smaller-button implants are used.

CONCLUSIONS

The coracoid graft could not always restore glenoid defects of 30%. Larger implants could be positioned too close to the osteotomy and the "medio-lateral offset" of the coracoid could be increased with smaller implants.