Bone Osteolysis Following Acromioclavicular Joint Reconstruction Using Synthetic Ligament (Surgilig™).

Good short term results have led to increased use of synthetic ligaments for acute and chronic acromioclavicular joint (ACJ) disruption. They have proved quite safe in the short term but we present two cases of osteolysis following ACJ reconstruction using a synthetic ligament, reminding surgeons of potential complications with artificial ligaments. A high index of suspicion is needed to diagnose such complications early before irretrievable bone loss to osteolysis.

Bone density and cortical thickness in normal, osteopenic, and osteoporotic sacra.

It is unclear if a decrease in cancellous bone density or cortical bone thickness is related to sacral insufficiency fractures. We hypothesized that reduction in overall bone density leads to local reductions in bone density and cortical thickness in cadaveric sacra that match clinically observed fracture patterns in patients with sacral insufficiency fractures. We used quantitative computed tomography to measure cancellous density and cortical thickness in multiple areas of normal, osteopenic, and osteoporotic sacra. Cancellous bone density was significantly lower in osteoporotic specimens in the central and anterior regions of the sacral ala compared with other regions of these specimens. Cortical thickness decreased uniformly in all regions of osteopenic and osteoporotic specimens. These results support our hypothesis that areas of the sacrum where sacral insufficiency fractures often occur have significantly larger decreases in cancellous bone density; however, they do not support the hypothesis that these areas have local reduction of cortical bone thickness.

Biomechanical comparison of two headless compression screws for scaphoid fixation.

This study compared compression generation between two headless compression screws: the Synthes 3.0-mm and the Acutrak standard. Twenty scaphoids were harvested from 10 pairs of fresh cadaveric forearms. A washer-shaped load cell was inserted between the halves of each scaphoid created by a simulated fracture via osteotomy. One scaphoid of each pair was tested with the Synthes and the other with the Acutrak. Parameters of interest were peak screw torque and fracture site compression. Differences in parameters of interest were checked for significance (p < .05) with paired t tests. No significant differences were shown in mean (+/- standard deviation) peak torque (57 +/- 28 Ncm vs. 55 +/- 32 Ncm; p < .84), compression immediately after insertion (119 +/- 54 N vs. 91 +/- 37 N; p < .15), or compression 5 min after insertion (32 +/- 30 N vs. 38 +/- 24 N; p < .61) between the Synthes and Acutrak screw fixations, respectively. The choice between these two screws to stabilize scaphoid waist fractures should be based on parameters other than compression generation, such as size, availability, cost, and ease of use of the implant.

A biomechanical comparison of lateral and posterior approaches to sacroplasty.

STUDY DESIGN: Biomechanical cadaveric bench study. OBJECTIVE: To measure the augmentation effect and extravasation risk of posterior and lateral approaches to sacroplasty. SUMMARY OF BACKGROUND DATA: The biomechanical stabilizing effect of sacroplasty is unknown. METHODS: Using a sacral insufficiency fracture model, we performed sacroplasty in 15 osteoporotic cadaveric pelves. Five served as controls, and 10 were each injected with 4 mL of a polymethylmethacrylate cement (5 via a posterior approach, 5 via a lateral approach). Cement extravasation was assessed using computed tomography. Restored strength and stiffness were defined as the ratios of treatment to initial strength and to stiffness, respectively. Between-group differences in restoration parameters were checked for significance (P < 0.05) using an analysis of variance followed by Tukey's test. RESULTS: We found no significant differences between groups in terms of restored strength ( approximately 61%) and stiffness ( approximately 77%). Both injection methods produced extravasation into the anterior sacrum, the posterior sacrum, the sacroiliac joint, and the neural foramens. CONCLUSION: Sacroplasty with 4 mL of cement does not restore the strength or stiffness of the sacrum in a cadaveric model, regardless of the approach used.