Three-dimensional characterization of the microstructure in rabbit patella-patellar tendon interface using propagation phase-contrast synchrotron radiation microtomography.

Understanding the three-dimensional ultrastructure morphology of tendon-to-bone interface may allow the development of effective therapeutic interventions for enhanced interface healing. This study aims to assess the feasibility of propagation phase-contrast synchrotron radiation microtomography (PPC-SRµCT) for three-dimensional characterization of the microstructure in rabbit patella-patellar tendon interface (PPTI). Based on phase retrieval for PPC-SRµCT imaging, this technique is capable of visualizing the three-dimensional internal architecture of PPTI at a cellular high spatial resolution including bone and tendon, especially the chondrocytes lacuna at the fibrocartilage layer. The features on the PPC-SRµCT image of the PPTI are similar to those of a histological section using Safranin-O staining/fast green staining. The three-dimensional microstructure in the rabbit patella-patellar tendon interface and the spatial distributions of the chondrocytes lacuna and their quantification volumetric data are displayed. Furthermore, a color-coding map differentiating cell lacuna in terms of connecting beads is presented after the chondrocytes cell lacuna was extracted. This provides a more in-depth insight into the microstructure of the PPTI on a new scale, particularly the cell lacuna arrangement at the fibrocartilage layer. PPC-SRµCT techniques provide important complementary information to the conventional histological method for characterizing the microstructure of the PPTI, and may facilitate in investigations of the repair mechanism of the PPTI after injury and in evaluating the efficacy of a different therapy.

Clinical outcomes of remnant preserving augmentation in anterior cruciate ligament reconstruction: a systematic review.

PURPOSE: The objective of this study was to systematically review the current evidence to see whether the remnant preservation techniques could obtain better clinical outcomes than the standard anterior cruciate ligament reconstruction procedure. METHODS: The authors systematically searched online databases to identify the studies which compared the remnant preservation techniques with the standard techniques. Two reviewers independently extracted data and evaluated the methodological quality of each study. Clinical outcomes in terms of knee stability, clinical scores, vascularization, proprioception, tibial tunnel enlargement and complications were qualitatively compared. RESULTS: Thirteen studies met the inclusion criteria for review. Compared with the standard procedure, significantly better results regarding knee stability in the remnant preserving group were reported in two of nine studies in the instrumented knee laxity, one of eight studies in the Lachman test and none of eight studies regarding the pivot shift test. Five studies assessed International Knee Documentation Committee scores but found no differences. One of two studies indicated significantly earlier revascularization according to the signal/noise quotient value of the graft on magnetic resonance imaging. One of two studies indicated significantly better proprioceptive function in terms of joint position sense using the reproduction of passive positioning test. Two of two studies showed significantly less tibial tunnel enlargement in the remnant preserving group. None of the studies showed significant increase in the risk of cyclops lesion formation and the loss of knee range of motion in the remnant augmentation group. CONCLUSIONS: The current evidence suggests that the short-term clinical outcomes of patients with the remnant augmentation technique are comparable, if not superior, with that of patients undergoing the standard technique, although it is insufficient to justify the remnant preserving augmentation as a routine treatment for anterior cruciate ligament ruptures. LEVEL OF EVIDENCE: Systematic review, Level IV.

Allograft versus autograft for anterior cruciate ligament reconstruction: an up-to-date meta-analysis of prospective studies.

PURPOSE: Although a large number of anterior cruciate ligament (ACL) reconstructions are performed annually, there remains a considerable amount of controversy over whether an autograft or an allograft should be used. The aim of this meta-analysis was to compare the clinical outcomes of allograft and autograft in primary ACL reconstruction. METHODS: The authors systematically searched electronic databases to identify prospective studies which compared allografts with autografts for primary ACL reconstruction. The results of the eligible studies were analysed in terms of instrumented laxity measurements, Lachman test, Pivot Shift test, objective International Knee Documentation Committee (IKDC) Scores, Lysholm Scores, Tegner Scores, and clinical failures. Study quality was assessed and relevant data were extracted independently by two reviewers. A random effect model was used to pool the data. Statistical heterogeneity between trials was evaluated by the chi-square and I-square tests. RESULTS: Nine studies, with 410 patients in the autograft and 408 patients in the allograft group, met the inclusion criteria. Five studies compared bone-patellar tendon-bone (BPTB) grafts, and four compared soft-tissue grafts. Four studies were randomized controlled trials, and five were prospective cohort studies. The results of the meta-analysis showed that there were no significant differences between allograft and autograft on all the outcomes in terms of instrumented laxity measurements (P=0.59), Lachman test (P=0.41), Pivot Shift test (P=0.88), objective IKDC Scores (P=0.87), Lysholm Scores (P=0.79), Tegner Scores (P=0.06), and clinical failures (P=0.68). These findings were still robust during the sensitivity analysis. However, a subgroup analysis of Tegner scores by involving only BPTB grafts showed a statistical difference in favour of autografts (P=0.005). CONCLUSIONS: There was insufficient evidence to identify which of the two types of grafts was significantly better for ACL reconstruction, though the subgroup analysis indicated that reconstruction with BPTB autograft might allow patients to return to higher levels of activity in comparison with BPTB allograft. More high-quality randomized controlled trials with specified age and activity level are highly required before drawing a reliable conclusion.

[Histomorphological analyse of accelerating the fibrocartilage layer repair of patella-patellar tendon junction in rabbits by low intensity pulsed ultrasound stimulation].

OBJECTIVE: To analyse the effect of low intensity pulsed ultrasound stimulation (LIPUS) on accelerating the fibrocartilage layer repair of patella-patellar tendon junction. METHODS: A total of 60 mature female New Zealand white rabbits undergoing standard partial patellectomy were divided into 2 groups randomly. The control group was given comfort treatment and the treatment group was given LIPUS treatment starting from day 3 to the end of week 6 postoperatively. The scheduled time points of animal euthanization would be at week 6, week 12 and week 18 postoperatively. The patella-patellar tendon (PPT) complex would be harvested and cut into sections after decalcification for H&E staining, Safranine o/fast green staining. The thickness and gray value of fibrocartilage layer were analyzed by SANO Microscope Partner image analyzer. RESULTS: At week 6, week 12 and week 18 postoperatively, the fibrocartilage layer in the treatment group was significantly thicker than that in the control group (P<0.01), and the gray value of fibrocartilage layer was significantly smaller than that in the control group (P<0.01). CONCLUSION: LIPUS helps to accelerate the fibrocartilage layer repair of patella-patellar tendon junction in rabbit models.

Initiation Timing of Low-Intensity Pulsed Ultrasound Stimulation for Tendon-Bone Healing in a Rabbit Model.

BACKGROUND: Low-intensity pulsed ultrasound stimulation (LIPUS) has been proven to be a beneficial biophysical therapy for tendon-bone (T-B) healing. However, the optimal time to initiate LIPUS treatment has not been determined yet. LIPUS initiated at different stages of the inflammatory phase may profoundly affect T-B healing. PURPOSE: An established rabbit model was used to preliminarily investigate the effect of LIPUS initiation timing on T-B healing. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 112 mature rabbits that underwent partial patellectomy were randomly assigned to 4 groups: daily mock sonication (control group) and daily ultrasonication started immediately postoperatively (immediate group), on postoperative day 7 (7-day delayed group), or on postoperative day 14 (14-day delayed group). Peripheral leukocyte counts at the inflammatory phase were used to assess postoperative inflammation. The rabbits were sacrificed at 8 or 16 weeks postoperatively for microarchitectural, histological, and mechanical evaluations of the patella-patellar tendon (PPT) junction. RESULTS: The biomechanical properties of the PPT junction were significantly improved in the LIPUS-treated groups. Significantly higher ultimate strength and stiffness were seen in the 7-day delayed group compared with the other groups at 8 weeks postoperatively (P < .05 for all). Newly formed bone expansion from the remaining patella in the ultrasonic treatment groups was significantly increased and remodeled compared with the control group. Micro-computed tomography analysis showed that the 7-day delayed group had significantly more bone volume and bone mineral content at the interface as compared with the other groups at 8 weeks postoperatively (P < .05 for all). Histologically, the ultrasonic treatment groups exhibited a significantly better PPT junction, as shown by more formation and remodeling of the fibrocartilage layer and newly formed bone. Additionally, peripheral leukocyte counts displayed a significant increase from postoperative day 1 to day 3 in the immediate group as compared with the other groups. Furthermore, postoperative hydrarthrosis was more likely in the immediate group. CONCLUSION: LIPUS started at postoperative day 7 had a more prominent effect on T-B healing compared with the other treatment regimens in this study. CLINICAL RELEVANCE: The findings of the study may help optimize the initiation timing of LIPUS for T-B healing.

The effect of low-intensity pulsed ultrasound on bone-tendon junction healing: Initiating after inflammation stage.

The purpose of this study was to explore the effect of low-intensity pulsed ultrasound (LIPUS) treatment initiating after inflammation stage on the process of bone-tendon junction (BTJ) healing in a rabbit model. Thirty-six rabbits undergoing partial patellectomy were randomly divided into two groups: control and LIPUS. The period of initial inflammatory stage is 2 weeks. So LIPUS treatment was initiated at postoperative week 2 and continued until the patella-patellar tendon (PPT) complexes were harvested at postoperative weeks 4, 8, and 16. At each time point, the PPT complexes were harvested for qRT-PCR, histology, radiographs, synchroton radiation micro computed tomography (SR-µCT), and biomechanical testing. The qRT-PCR results showed that LIPUS treatment beginning at postoperative week 2 played an anti-inflammatory role in BTJ healing. Histologically, the LIPUS group showed more advanced remodeling of the lamellar bone and marrow cavity than the control group. The area and length of the new bone in the LIPUS group were significantly greater than the control group at postoperative weeks 8 and 16. SR-µCT demonstrated that new bone formation and remodeling in the LIPUS group were more advanced than the control group. Biomechanical test results demonstrated that the failure load, ultimate strength and energy at failure were significantly higher than those of the control group. In conclusion, LIPUS treatment beginning at postoperative week 2 was able to accelerate bone formation during the bone-tendon junction healing process and significantly improved the healing quality of BTJ injury. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1697-1706, 2016.