Influence of volar margin of the lunate fossa fragment fixation on distal radius fracture outcomes: A retrospective series.

BACKGROUND: Distal radius fractures accompanied by the volar margin of the lunate fossa (VMLF) lesions are often overlooked or inadequately reduced in clinical practice. AIM: To investigate the impact of VMLF fragment in distal radius fractures on the stability and function of the wrist joint. METHODS: This was a retrospective study of patients with distal radius fractures who underwent surgical treatment between January 2013 and December 2017. The patients were divided into two groups according to whether the VMLF fragments were fixed or not. X-rays and computed tomography were performed before surgery, immediately postoperatively, and at 1, 3, and 6 mo to measure the scapholunate angle, radiolunate angle, capitolunate angle, and effective radiolunate flexion (ERLF). The Mayo wrist score and disabilities of the arm, shoulder, and hand (DASH) score were determined at 1 year. RESULTS: Thirty-five patients were included. There were 15 males and 20 females. Their mean age was 52.5 ± 14.3 (range: 19-70) years. There were 38 wrists (17 on the left side, 15 on the right, and three bilateral; 16 in the fixed group, and 22 in the unfixed group). The interval between trauma and surgery was from 1 h to 1 mo. The incidence of postoperative wrist instability in the unfixed group (86.4%) was higher than in the fixed group (25.0%) (P ≤ 0.001). Ten patients had ERLF > 25° in the unfixed group and none in the fixed group (P = 0.019). The Mayo wrist score was 94 ± 5.7 in the fixed group and 68 ± 15.1 in the unfixed group (P < 0.001). The DASH score was 4.6 ± 2.5 in the fixed group and 28.5 ± 19.5 in the unfixed group (P < 0.001). CONCLUSION: Injuries of VMLF, even small fractures, might damage the radial-lunar ligament, leading to postoperative wrist instability, sagittal force line imbalance, and poor recovery of wrist joint function.

Non-invasive quantification of age-related changes in the vertebral endplate in rats using in vivo DCE-MRI.

BACKGROUND: Small animal models that can mimic degenerative disc disease (DDD) are commonly used to examine DDD progression. However, assessments such as histological studies and macroscopic measurements do not allow for longitudinal studies because they can only be completed after the animal is sacrificed. Dynamic contrast-enhanced MRI (DCE-MRI) may provide a reliable, non-invasive in vivo method for detecting the progression. METHODS: The present study investigated the progression of changes in lumbar discs and the effect of endplate conditions on diffusion into the lumbar discs of aging sand rats after intravenous administration of gadolinium-containing contrast medium through the tail vein. Contrast enhancement was measured in the lumbar intervertebral discs on each image. The results were compared with those from conventional histological characterizations. RESULTS: T2-weighted images revealed that with aging, the shape of L3-L4, L4-L5, L5-L6, and L6-S1 nucleus pulposus (NP) became irregular, while the mean areas, signal intensities, and T2 values of the NP were significantly decreased. Each of the observed disc changes demonstrated a progressive increase in phase during 2-min scout scans. Post-contrast MRI showed impaired endplate nutritional diffusion to the disc with aging, enhancement was significantly greater in young animals than in old animals. Endplate calcification or sclerosis was histologically confirmed; histologic score was correlated with the age. We found the histological score of the endplate negatively corresponded to the DCE-MRI results. CONCLUSIONS: DCE-MRI studies offer a non-invasive in vivo method for investigating the progress of diffusion into the discs and the functional conditions of the endplate. We conclude that quantitative DCE-MRI can identify the severity of disc degeneration and efficiently reflect the progression of vertebral endplate changes in the aging sand rat lumbar spine via the NP contrast enhancement patterns.

Minimally invasive transforaminal lumbar interbody fusion (MI-TLIF): surgical technique, long-term 4-year prospective outcomes, and complications compared with an open TLIF cohort.

Transforaminal lumbar interbody fusion (TLIF) is an important surgical option for the treatment of back pain and radiculopathy. The minimally invasive TLIF (MI-TLIF) technique is increasingly used to achieve neural element decompression, restoration of segmental alignment and lordosis, and bony fusion. This article reviews the surgical technique, outcomes, and complications in a series of 144 consecutive 1- and 2-level MI-TLIFs in comparison with an institutional control group of 54 open traditional TLIF procedures with a mean of 46 months' follow-up. The evidence base suggests that MI-TLIF can be performed safely with excellent long-term outcomes.

[The Biomechanics Influence of unilateral laminectomy and discectomy surgery on the adjacent different grades of Disc Degeneration].

OBJECTIVES: To study the stress distribution of the adjacent different grades of disc degeneration underwenting unilateral laminectomy and discectomy surgery using non-linear finite element analysis. METHODS: Based on the lumbar CT scans, the finite element model (FEM) of lumbar spinal segment (L3-L5) was established. According to L3-L4 intervertebral disc degeneration, different grades of disc degeneration (healthy, mild, moderate and severe) models were established and unilateral laminectomy and discectomy surgery were also established. Physiological action such as flexion, extension, lateral bending and lateral rotation was simulated and the von Mises stress in the nucleus pulposus and annulus fibrosus matrix of L3-L4 disc was investigated. RESULTS: After unilateral laminectomy and discectomy surgery, the extremum value of von Mises stress of nucleus pulposus and annulus fibrosus matrix was maximum during extension and minimus left bending in the healthy intervertebral disc. Compared with healthy disc, the increment of extremum value was found during left bending in the mildly degenerated disc. When the value decreased in the moderately degenerated disc, but still higher than that in the healthy disc. When the adjacent disc is severely degenerated, the extremum value of nucleus pulposus decreased, in addition to axial rotation, and even lower than that of healthy disc. The value of annulus matrix decreased and still higher than that of healthy disc, especially during left bending. CONCLUSIONS: After unilateral laminectomy and discectomy surgery, avoiding lateral bending will reduce the abnormal stress in the degenerated disc and decreased the risk of accelerating disc degeneration.

Finite element analysis in adjacent segment degeneration after lumbar fusion.

BACKGROUND: Adjacent segment degeneration (ASD) following lumbar fusion has been well documented in recent years. However, the pathogenesis of ASD is not clear. To investigate this issue, we established a finite element model of segments L2-L5, simulated a single-segment posterior fixation in L3-L4 and investigated the stress variation and the effects of the instrumented lumbar posterior fixation on adjacent levels. METHODS: Models A, B and C of L2-L5 multisegment finite element intact models were established. In model A, segment L3-L4 was not fixed and was without disc degeneration in the adjacent segment (L2-L3, L4-L5); in model B there was posterior pedicle fixation in segment L3-L4 without disc degeneration in the adjacent segment (L2-L3, L4-L5); in model C there was posterior pedicle fixation in segment L3-L4 with a degenerated disc in the adjacent segment (L2-L3, L4-L5). Four levels of axial pressure, 0.3, 0.5, 1.0 and 2.0 MPa, were compared between each model of the stress variation on the discs of the adjacent segment (L2-L3, L4-L5). RESULTS: The maximum principal stress mean value of disc L2-L3 under four pressures in model A was determined. The statistical results showed that stress was not significant difference in disc L2-L3 between models A and B, but there was a significant difference in disc L2-L3 between models A and C and a significant difference between each group in disc L4-L5 under four pressure conditions. CONCLUSIONS: The preoperative degeneration of the adjacent segment of the disc is a significant risk factor for ASD.

[Assessment of correction effect in relation to fulcrum bending flexibility in adult idiopathic scoliosis patients].

OBJECTIVE: To study the relationship between the fulcrum bending flexibility (FBF) and correction rate (CR) of adult idiopathic scoliosis, and to explore the ability of FBF to assess the correction effect in relation to fulcrum bending flexibility. METHODS: 69 patients with adult idiopathic scoliosis with structural curves at thoracic or lumbarthoracic segments, 16 males and 53 females, aged 26.5 (19 - 53) were treated by pedicle screws instrumentation. Pre-operative standing and fulcrum bending films and postoperative standing X-ray film were taken. Cobb angle was measured. The data underwent regression analysis with the software SPSS 10.0. RESULTS: A regression formula was established: CR = 0.213 + 0.768 x FBF with P < 0.01. CONCLUSION: A definite linear relation exists between the FBF and CR of adult idiopathic scoliosis. By using the formula in proper samples, the effects of new instrumentation or correction technique can be objectively assessed.

[Dynamic observation of the biomechanic properties of sciatic nerve at the suture site in rats following repairing].

OBJECTIVE: To observe the biomechanic properties of sciatic nerve at the suture site in rats following repairing. METHODS: The right sciatic nerves of 40 white Sprague-Dawley 300-350 gm rats were exposed, cut and then repaired with 10-0 nylon sutures, laced in the epineurium. 0, 1, 3, 6 weeks after operation, the tensile strength of the sciatic nerves were measured, the data analyzed statistically. RESULTS: The load-elongation curves for both the normal unoperated and operated nerves had the similar shape. The tensile strength of the 0 week was significant difference to 1, 3 and 6 weeks (P < 0.01). No significant difference was found among 1, 3 and 6 weeks. CONCLUSION: The tensile strength of the injured nerves are recovered in the first week and resistant in 6 weeks after repairing.