Outcomes in Patients with Global Pincer Versus Focal Pincer Femoroacetabular Impingement Treated with Hip Arthroscopy: A Retrospective Study with a Minimum 2-Year Follow-Up.

OBJECTIVE: Global pincer is a relatively rare form of pincer deformity and is typically associated with technical challenges during surgery. So far, controversy remains whether patients with global pincer have equivalent surgical outcomes compared to patients with focal pincer. This study compares the clinical outcomes of arthroscopic treatment between patients with global pincer femoroacetabular impingement (FAI) and focal pincer FAI in the Chinese population. METHODS: Data were retrospectively collected from patients with global and focal pincer FAI who underwent hip arthroscopy with a minimum two-year follow-up between April 2016 and December 2018. Radiographic measurements, arthroscopic procedures, preoperative and postoperative patient-reported outcomes (PROs) including modified Harris hip score (mHHS), hip outcome score-activities of daily living (HOS-ADL), international hip outcome tool-12 (iHOT-12), and visual analogue scale (VAS) scores, rates of revision surgery and conversion to total hip arthroplasty (THA) were recorded. Achievement of minimal clinically important difference (MCID) and patient acceptable symptomatic state (PASS) was compared for the VAS, mHHS, HOS-ADL, and iHOT-12 scores between groups. RESULTS: The total of 33 and 167 patients were included in the global and focal group, respectively. There were no intergroup differences in age, gender, body mass index or follow-up times. Lateral center-edge angle (LCEA) was reduced in both groups postoperatively. Both groups demonstrated significant improvements in PROs compared with preoperative levels at the final follow-up. The preoperative scores showed significant differences in terms of mHHS (60.34 vs 62.90, P = 0.031) and HOS-ADL (61.45 vs 64.74, P = 0.022) scores between two groups, and the improvement of HOS-ADL score was significantly higher in global group (P = 0.027). However, the postoperative scores, including VAS, mHHS, HOS-ADL, and iHOT-12 scores, showed no significant differences between two groups. And there were no significant differences in the rate of meeting the PASS and MCID between groups. One (3.0%) in the global group and six (3.6%) patients in the focal group underwent revision arthroscopy respectively, with no significant difference (P = 0.876). There were no conversions to THA in both groups. CONCLUSIONS: Arthroscopic management of global pincer FAI can achieve excellent functional scores at minimum 2-year follow-up. The outcomes were similar to focal pincer FAI patients with a low rate of secondary procedure.

[Non-structural carbohydrate content of trees and its influencing factors at multiple spatial-temporal scales: A review]. / æ ‘æœ¨éžç»“æž„æ€§ç¢³æ°´åŒ–åˆç‰©å«é‡å¤šæ—¶ç©ºå°ºåº¦å˜åŒ–ç‰¹å¾åŠå ¶å½±å“å› ç´ ç ”ç©¶è¿›å±•.

Non-structural carbohydrates (NSC) are essential substances for the tree growth and metabolism, and play an important role in environmental adaptation of trees. At temporal scale, NSC contents in trees have limited inter-annual variation, which could be attributed to the strategy of tree growth and carbon storage. Different factors influence NSC contents of trees in various climatic regions, which change substantially at the seasonal scale. At spatial scale, the variations of NSC content in trees show an insignificantly decreasing trend with the decreases of latitude at global and continental scales, which are mainly related to the hydrothermal gradients. The trend at regional scale is opposite because of the decrease of hydrothermal gradients and lower sample frequency. More sophisticated relations exist between the variations of NSC content in trees and altitudes, which are caused by species-specific characteristics and the variations of micro-habitat conditions. The variations of NSC content in trees at multiple spatial-temporal scales are generally determined by both biotic and abiotic factors, which are mainly dependent on the tradeoff among photosynthate production, respiratory depletion, and tree growth. Furthermore, the methods used for the determination of NSC content are different, which results in great uncertainties in comparing conclusions from different studies. The methods used for sample collection and measurement of NSC should be improved and unified to enhance the comparison among different studies. The NSC contents of trees in different age classes should be measured with all organs collected at multiple spatial-temporal scales. The underlying mechanisms, significance of NSC storage, transformation and allocation on tree growth and survival should be further discussed.

[Tree seedling distribution, regeneration mechanism and response to climate change in alpine treeline ecotone]. / é«˜å±±æž—çº¿ç”Ÿæ€äº¤é”™åŒºæœ¨æœ¬æ¤ç‰©å¹¼è‹—åˆ†å¸ƒç‰¹å¾ã€æ›´æ–°æœºåˆ¶åŠå ¶å¯¹æ°”å€™å˜åŒ–çš„å“åº”.

Tree seedlings are one of the important components in alpine treeline ecotone, whose regeneration is crucial to treeline migration in response to climate change. We analyzed the spatial distribution, regeneration of tree seedlings and their responses to climate change in treeline ecotone in recent decades. The spatial distribution of tree seedlings in treeline ecotone is dominated by diffuse and clustered forms, with different indicative significance for spatial dynamics of treeline. At global scale, the altitude distribution limits of tree seedlings are usually related to the length and average temperature of growing season, along with the species characteristics. However, precipita-tion plays an important role at regional scale. The initial stage of seedling recruitment is restricted by seed source, which determines seed distribution and germination to a great extent. Microenvironment facilitates seedling regeneration by providing shelter for establishment and improving their survival rate. The regeneration process is more relevant to multiple biotic, abiotic factors and their interactions. With global warming, rising temperature in treeline ecotone and more precipitation are more suitable for seedling regeneration of treeline species. The expansion of seedlings to higher elevations could be considered as the portent of timberline upwards migration. Due to species-specific adaption strategy, however, some trees only increase seedling density and timberline location is constant. In the future, it is necessary to take precise dating techniques, such as tree-ring and 14C dating, and conduct long-term in-situ monitoring and indoor simulation experiments. To provide scientific basis for mountain ecosystem restoration and conservation, we should strengthen the studies on spatial patterns and regeneration mechanism of seedlings in treeline ecotone at multiple spatio-temporal scales, the adaptation strategies of tree seedlings in different types of treeline ecotone and treeline dynamics prediction.