Comparison of Glenohumeral Contact Pressures and Contact Areas After Glenoid Reconstruction With Latarjet or Distal Tibial Osteochondral Allografts
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Understanding and properly addressing irregularities in the osseous architecture of the glenohumeral joint are critical to the overall successful treatment of glenohumeral instability. After a traumatic anterior shoulder dis- location, a concomitant glenoid rim fracture or an attritional bone injury may compromise the static restraints of the glenohumeral joint, further perpetuating shoulder instability. Loss of the glenoid’s bony articular conformity significantly inhibits its ability to withstand shear stress.
With recognition of glenoid bone loss as a potential cause for failure in glenohumeral instability, various surgical techniques for glenoid reconstruction have recently been emphasized by many authors, calling attention to this often underappreciated problem. Principles of surgical management are guided by the extent of osseous injuries to the glenoid, the surgeon’s personal experience with specific reconstructive techniques, and patient-specific factors such as work and athletic demands. Both arthroscopic and open techniques have been described, and there is a growing body of evidence to suggest that bony reconstruction of the glenoid is recommended if there is significant bone loss (usually .20%-25%).
For patients with significant bone defects, several autologous bone grafting procedures, including the Latarjet (and modified Bristow) procedure as well as the use of iliac crest bone grafts, have been described. Although long-term studies have demonstrated that such techniques result in stable and functional shoulders, arthritis continues to be a concern. It is postulated that nonanatomic repair of the glenoid arc, extra-articular nonanatomic repair of capsulolabral tissues, and a lack of chondral surface reconstitution may in part explain the high incidence of degenerative disease after coracoid transfer. In a recent study, Ghodadra showed that glenohumeral contact pressures increase by up to 390% in the anteroinferior quadrant of the glenoid when a 30% bone defect is present. The authors then showed that joint contact pressures were optimally restored with flush positioning of an iliac or coracoid bone graft. Coracoid grafts that were placed proud significantly increased peak forces within the joint and altered joint loading patterns, a finding that further supports the rationale for finding anatomic means for reconstruction of a congruous glenohumeral joint.
Reconstruction of glenoid bone defects with distal tibial osteochondral allografts has recently been described as a technique for restoring the articular surface of the glenoid while providing for a customized, anatomic fit of the bone graft and avoiding coracoid morbidity. Although this technique provides the theoretical benefit of improved joint congruity and decreased contact pressures, it is unclear whether the distal tibial graft truly reduces glenohumeral contact pressures and congruity in comparison with coracoid grafts.
The purposes of this study were to determine changes in the magnitude and location of mean contact pressures after (1) the creation of a 30% anterior glenoid defect and subse- quent glenoid bone augmentation procedures with flush placement of (2) a Latarjet coracoid graft or (3) a distal tibial osteochondral graft. It was hypothesized that bone augmentation with the distal tibial osteochondral graft in a flush position would best normalize articular contact pressures while also providing complete glenoid bone restoration.