Biomechanical Comparison of a Novel Multiplanar, Perpendicular Whipstitch With the Krackow Stitch and Standard Commercial Whipstitch.

Background: Using alternating orthogonal suture throws with the looped whipstitch technique may allow enhanced suture fixation. Hypothesis: It was hypothesized that this novel multiplanar, perpendicular looped whipstitch (MP) technique would have improved biomechanical properties compared with the standard looped whipstitch (WS) and Krackow stitch (KS). Study Design: Controlled laboratory study. Methods: A total of 30 cadaveric tibialis anterior tendons were randomly assigned into 3 groups of 10. Tendons were secured to a custom clamp, and the other end was sutured using 1 of 3 techniques: the KS, WS, or novel MP. The MP was performed with alternating orthogonal throws starting right to left, then front to back, left to right, and back to front. Each technique used 4 passes of No. 2 FiberWire spaced 5 mm apart and ending 10 mm from the tendon end. Tendons were preloaded to 5 N, pretensioned to 50 N at 100 mm/min for 3 cycles, returned to 5 N for 1 minute, cycled from 5 to 100 N at 200 mm/min for 100 cycles, and then loaded to failure at 20 mm/min. Elongation was recorded after pretensioning and cycling and was measured both across the suture-tendon interface and from the base of the suture-tendon interface to markings on the suture limbs (construct elongation). One-way analyses of variance were performed, with Bonferroni post hoc analysis when appropriate. Results: There were no differences in cross-sectional area or stiffness among the 3 techniques. The ultimate load for WS (183.33 ± 57.44 N) was less compared with both MP (270.76 ± 39.36 N) and KS (298.90 ± 25.94 N) (P ≤ .001 for both). There was less construct elongation for KS compared with WS and MP for total displacement, measured from pretensioning to the end of cycling (P < .001). All 3 techniques saw a decrease in length (shortening) at the suture-tendon interface during testing. There was more shortening at the suture-tendon interface for WS compared with KS (P = .006). Conclusion: The KS appears superior, as it maximized strength while minimizing construct elongation or graft shortening. The ultimate load of the MP technique was greater than that of the standard technique but not significantly different from that of the KS technique. Clinical Relevance: The KS is preferred. If using a WS, multiplanar, perpendicular passes should be considered.

Spinal deformity surgery is accompanied by serious complications: report from the Morbidity and Mortality Database of the Scoliosis Research Society from 2013 to 2020.

PURPOSE: The Morbidity and Mortality (M&M) report of the Scoliosis Research Society (SRS) has been collected since 1965 and since 1968 submission of complications has been required of all members. Since 2009, the SRS has collected information on death, blindness, and neurological deficit, with acute infection being added in 2012 and unintentional return to the operating room (OR) being added in 2017. In this report, we use the most recent data submitted to the SRS M&M database to determine the rate of neurological deficit, blindness, acute infection, unintentional return to the OR, and death, while also comparing this information to previous reports. METHODS: The SRS M&M database was queried for all cases from 2013 to 2020. The rates of death, vision loss, neurological deficit, acute infection, and unintentional return to the OR were then calculated and analyzed. The rates were compared to previously published data if available. Differences in complication rates between years were analyzed with Poisson regression with significance set at α = 0.05. RESULTS: The total number of cases submitted per year varied with a maximum of 49,615 in 2018 and a minimum of 40,464 in 2020. The overall reported complication rate from 2013 to 2020 was 2.86%. The overall mortality rate ranged from 0.09% in 2018 to 0.14% in 2015. The number of patients with visual impairment ranged from 4 to 13 between 2013 and 2015 (no data on visual impairment were collected after 2015). The overall infection rate varied from 0.95 in 2020 to 1.30% in 2015. When the infection rate was analyzed based on spinal deformity group, the neuromuscular scoliosis group consistently had the highest infection rate ranging from 3.24 to 3.94%. The overall neurological deficit rate ranged from 0.74 to 0.94%, with the congenital kyphosis and dysplastic spondylolisthesis groups having the highest rates. The rates of unintentional return to the OR ranged from 1.60 to 1.79%. Multiple groups showed a statistically significant decreasing trend for infection, return to the operating room, neurologic deficit, and death. CONCLUSIONS: Neuromuscular scoliosis had the highest infection rate among all spinal deformity groups. Congenital kyphosis and dysplastic spondylolisthesis had the highest rate of neurological deficit postoperatively. This is similar to previously published data. Contrary to previous reports, neuromuscular scoliosis did not have the highest annual death rate. Multiple groups showed a statistically significant decreasing trend in complication rates during the reporting period, with only mortality in degenerative spondylolisthesis significantly trending upwards. LEVEL OF EVIDENCE: Level III.

Comparing the physicochemical properties of dicalcium phosphate dihydrate (DCPD) and polymeric DCPD (P-DCPD) cement particles.

We developed a new and injectable poly-dicalcium phosphate dihydrate (P-DCPD) forming cement. The key structural difference between P-DCPD and classical DCPD is that P-DCPD is composed of interconnected P-DCPD crystals by interlocking to the polyphosphate chains. In contrast, DCPD is composed of a package of DCPD crystals with weak mutual ionic bonding. The purpose of this continuing study was to compare the physicochemical properties between P-DCPD and DCPD cement particles. Data collected from SEM, X-ray diffraction, and Raman Spectroscopy approaches demonstrated that P-DCPD has a more stable chemical structure than DCPD as evidenced by much less transformation to hydroxyapatite (HA) during setting. Nanoindentation showed a similar hardness while the elastic modulus of P-DCPD is much lower than DCPD that might be due to the much less HA transformation of P-DCPD. P-DCPD has much lower zeta potential and less hydrophilicity than DCPD because of its entangled and interconnected polyphosphate chains. It is expected that superhydrophilic DCPD undergoes faster dissolution than P-DCPD in an aqueous environment. Another interesting finding is that the pH of eluent from P-DCPD is more neutral (6.6-7.1) than DCPD (5.5-6.5). More extensive experiments are currently underway to further evaluate the potential impacts of the different physiochemical performance observed of P-DCPD and DCPD cement particles on the biocompatibility, degradation behavior and bone defect healing efficacy both in vivo and in vitro.

Osteocytes' expression of the PTH/PTHrP receptor has differing effects on endocortical and periosteal bone formation during adenine-induced CKD.

Osteocytes play a key role in the pathophysiology of chronic kidney disease (CKD). However, the extent to which osteocytes contribute to abnormalities in bone turnover due to excessive levels of parathyroid hormone (PTH) remains poorly understood. The purpose of this study was to determine the extent to which bone formation and tissue strength during the progression of CKD is modified through osteocytes' response to PTH. Conditional knockout mice targeting osteocytes' expression of the PTH/PTH-related protein type 1 receptor (PPR) were subjected to adenine-induced CKD. After 6-weeks of treatment, adenine-induced CKD was found to reduce bone formation at the periosteal and endocortical surfaces of the tibia. The loss in bone mass corresponded with a significant decrease in structural-level mechanical properties. In knockout mice, the loss of PPR expression in osteocytes further exacerbated the loss in bone formation at the endocortical surface, but inhibited bone loss at the periosteal surface. In general, the effects of adenine-induced CKD were not as extensive in female mice. Collectively, these findings demonstrate that osteocytes' response to PTH under adenine-induced CKD has a unique impact on bone turnover that is specific to the periosteal and endocortical surfaces.