Level III, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

No abstract

OBJECTIVE This study aims to quantify the impact of vancomycin powder application on new bone formation and spine fusion rates in a rat posterolateral arthrodesis model. METHODS Thirty-six female Sprague-Dawley rats underwent a posterolateral lumbar spinal fusion (PLF) at the L-4 and L-5 vertebrae. Fusion was elicited via implantation of an absorbable collagen sponge containing 3 µg rhBMP-2. Rats were divided into 3 groups: no vancomycin (control), standard-dose vancomycin, and high-dose vancomycin, based on what was applied to the fusion bed. Clinical studies typically describe the application of 1 g vancomycin into the surgical wound. Presuming an average individual patient weight of 70 kg, a weight-based equivalent dose of vancomycin powder was applied subfascially in the PLF model constituting a “standard-dose” treatment group (14.3 mg/kg, n = 12). To determine whether there is a critical threshold beyond which vancomycin increases the risk of pseudarthrosis, a 10-fold higher dose was administered to a “high-dose” treatment group (143 mg/kg, n = 12). No vancomycin powder was applied to the surgical site in the control group (n = 12). Fusion was evaluated with plain radiographs at 4 and 8 weeks after surgery. The spines were harvested after the 8-week radiographs were obtained and evaluated using manual palpation, microCT analysis, and histological analysis. RESULTS Radiographs demonstrated equivalent bridging bone formation in all groups. No significant differences in fusion scores were seen in the standard-dose (mean 2.25) or high-dose (2.13) treatment groups relative to untreated control animals (1.78). Similarly, fusion rates did not differ significantly different between vancomycin-treated animals (100% for both groups) and control animals (92%). Quantification of new bone formation via microCT imaging revealed no significant between-groups differences in the volume of newly regenerated bone (control vs standard-dose vancomycin, p = 0.57; control vs high-dose vancomycin, p = 0.53). CONCLUSIONS This is the first in vivo study to specifically address the development of pseudarthrosis after intrawound application of vancomycin during fusion surgery. Our results demonstrate that vancomycin powder does not inhibit fusion rates at a dose that is the weight-percentage equivalent of what is routinely used by surgeons. Moreover, bone formation and fusion rates were not reduced even after administration of a vancomycin dose that is 10-fold higher than that which is typically administered clinically. Our findings suggest that if there is a critical threshold above which vancomycin inhibits bone healing, such a dose is out of the range which might be considered reasonable for clinical use.

No abstract

Development of a pharmacologic agent that reduces the adverse effects of cigarette smoke on bone-healing could prove useful to orthopaedic surgeons. Since dioxin and other similar cigarette smoke toxins exert their effects through Ahr pathway activation, the receptor represents a potential therapeutic target to improve spinal fusion rates in patients who smoke.

Dual-mobility (DM) bearings in total hip arthroplasty (THA) have been reported to reduce dislocation rates, especially in high-risk patients, and are being rapidly adopted in primary and revision THAs. However, this technology introduces additional interfaces that have the potential to result in unforeseen complications. We present a series of 3 patients with mechanically assisted crevice corrosion at the acetabular component–metal dual-mobility liner interface. Consequently, we urge judicious use and close clinical observation of this new, effective technology in THA.

Cases of congenital absence of the cruciate ligaments are seen rarely in the literature. When reported, they are almost exclusively associated with various additional lower extremity deformities. We report the cases of 15-year-old monozygotic twin brothers. Both brothers presented with right knee pain and instability and were found on magnetic resonance imaging (MRI) to have congenital absence of the right anterior cruciate ligament (ACL). Examination of full length leg radiographs and MRI of the knee showed no associated abnormalities. Twin B previously underwent partial medial meniscectomy performed by an outside orthopaedic surgeon at which time the absence of the ACL was noted but not repaired. After diagnosis at our practice, both twins underwent arthroscopically assisted ACL construction with bone-patella-bone-autograft. Following recovery from surgery, both twins returned to high level athletics. These cases are among few reports of isolated congenital absence of the ACL, and to our knowledge there are no other cases of isolated congenital absence of the ACL in monozygotic twins.

Improvements in the processing of polyethylene have led to a dramatic reduction in wear rates in total hip arthroplasty. This led to the adoption of modern highly cross-linked polyethylene in total knee arthroplasty (TKA). However, the differences in modes of wear and failure between total hip arthroplasty and TKA have tempered expectations regarding similar decreases in polyethylene-related complications in TKA. We present a case of early catastrophic failure of a modern sequentially irradiated and annealed highly cross-linked polyethylene insert only 5 years after contemporary cementless TKA.