Re-tear after arthroscopic rotator cuff tear surgery: risk analysis using machine learning.

BACKGROUND: Postoperative rotator cuff retear after arthroscopic rotator cuff repair (ARCR) is still a major problem. Various risk factors such as age, gender, and tear size have been reported. Recently, magnetic resonance imaging-based stump classification was reported as an index of rotator cuff fragility. Although stump type 3 is reported to have a high retear rate, there are few reports on the risk of postoperative retear based on this classification. Machine learning (ML), an artificial intelligence technique, allows for more flexible predictive models than conventional statistical methods and has been applied to predict clinical outcomes. In this study, we used ML to predict postoperative retear risk after ARCR. METHODS: The retrospective case-control study included 353 patients who underwent surgical treatment for complete rotator cuff tear using the suture-bridge technique. Patients who initially presented with retears and traumatic tears were excluded. In study participants, after the initial tear repair, rotator cuff retears were diagnosed by magnetic resonance imaging; Sugaya classification types IV and V were defined as re-tears. Age, gender, stump classification, tear size, Goutallier classification, presence of diabetes, and hyperlipidemia were used for ML parameters to predict the risk of retear. Using Python's Scikit-learn as an ML library, five different AI models (logistic regression, random forest, AdaBoost, CatBoost, LightGBM) were trained on the existing data, and the prediction models were applied to the test dataset. The performance of these ML models was measured by the area under the receiver operating characteristic curve. Additionally, key features affecting retear were evaluated. RESULTS: The area under the receiver operating characteristic curve for logistic regression was 0.78, random forest 0.82, AdaBoost 0.78, CatBoost 0.83, and LightGBM 0.87, respectively for each model. LightGBM showed the highest score. The important factors for model prediction were age, stump classification, and tear size. CONCLUSIONS: The ML classifier model predicted retears after ARCR with high accuracy, and the AI model showed that the most important characteristics affecting retears were age and imaging findings, including stump classification. This model may be able to predict postoperative rotator cuff retears based on clinical features.

Timing of retears after arthroscopic rotator cuff repair and associated factors: a retrospective analysis.

BACKGROUND: Retear after arthroscopic rotator cuff repair (ARCR) remains a complication of important concern. Few reports have evaluated retear timing and its associated patient characteristics in large cohorts. This study aimed to investigate retear timing and patient characteristics and factors associated with this parameter. METHODS: Of the 638 consecutive shoulders that underwent ARCR from August 2009 to November 2019, shoulders with retear complication within 1 year of surgery were included. Retears were defined as type IV or V of the Sugaya's classification, and magnetic resonance imaging was performed at 6 weeks, 3 months, 6 months, and 1 year after surgery. The distribution of patients with retears at the timing of retears was investigated. In addition, patients with retears were classified into the following two groups: early group with retears occurring at 6 weeks and 3 months postoperatively or late group with retears occurring between 6 months and 1 year postoperatively. Associated factors such as sex, age, tear size, pre and postoperative range of motion, surgical technique, and clinical outcome between the two groups were investigated. RESULTS: The 41 shoulders with retears were divided into four groups: 1) within 6 weeks after surgery (n = 9, 22.0%), 2) 6 weeks-to 3 months after surgery (n = 19, 46.3%), 3) 3-6 months after surgery (n = 11, 26.8%), and 4) 6 months-1 year after surgery (n = 2, 4.9%). In addition, there were significantly larger retear sizes in the Sugaya's classification in the early group compared to the late group (P = .013), while there were significantly more males in the late group compared to the early group (P = .030). CONCLUSION: The highest retear rate after ARCR was observed from 6 weeks to 3 months after surgery, with equivalent rates within 6 weeks and from 3 months to 6 months after surgery.

Modified tension band wiring fixation for avulsion fractures of the calcaneus in osteoporotic bone: a review of three patients.

Calcaneal avulsion fractures are not uncommon, and they are probably more likely in patients with osteoporosis. Closed manipulation for this type of fracture often fails to achieve acceptable reduction, and open reduction and internal fixation are usually required. However, open reduction and internal fixation with either a lag screw or Steinmann pins do not provide satisfactory fixation in patients with diabetes and elderly patients because of the presence of porotic bone. Levi described a tension band fixation system used to treat a calcaneal avulsion fracture using a simple technique performed with a transverse Kirschner wire through the os calcaneus, securing a figure-of-8 metal tension band wiring to the fragment. We report the successful treatment of 3 patients with calcaneal avulsion fractures using a modified tension band wiring technique, resulting in satisfactory recovery. Re-displacement of the fragment during the initial follow-up period was not reported, and bony union was achieved in all patients. We believe this technique is a useful surgical option for the treatment of calcaneal avulsion fractures.

Diffuse pigmented villonodular synovitis in the metatarsophalangeal joint of the hallux: a case report.

UNLABELLED: A 60-year-old woman presented to our institution with a 2-month history of swelling and unrelieved pain on walking, localized to the right hallux. Magnetic resonance image scans revealed a multinodular soft tissue mass with low signal intensity on both T1- and T2-weighted images. Microscopic examination of a specimen procured using fine-needle biopsy revealed multinucleated giant cells, hemosiderin deposition, and foaming histiocytes, indicative of pigmented villonodular synovitis. Thereafter, excision of the mass and a thorough synovectomy were carried out using 2 separate longitudinal incisions. Although pigmented villonodular synovitis of the first metatarsophalangeal joint is not unheard of, it is relatively rare and physicians should consider it in the differential diagnosis when treating patients with prolonged chronic arthritis of the first pedal ray. This case, moreover, clearly depicts the diagnostic value of magnetic resonance imaging combined with fine-needle biopsy in regard to making the diagnosis of pigmented villonodular synovitis. LEVEL OF CLINICAL EVIDENCE: 4.

Ankle valgus and subtalar varus in treated clubfoot.

UNLABELLED: The purpose of this study was to clarify whether residual subtalar varus in treated clubfoot affects the configuration of the ankle joint in the coronal plane. Radiographic characteristics of the ankle and subtalar joint in congenital clubfoot, after a minimum of 10 years of treatment, were analyzed and presented. Weight-bearing radiographs of the ankles and feet, as well as computerized tomographic images of the hindfoot, were obtained for 30 patients (41 feet), at a mean of 15.2 +/- 6.1 years after initial treatment. Subtalar varus was measured in terms of the tilting angle of the posterior facet of the talocalcaneal joint, as viewed using computerized tomographic scans, and a larger angle was indicative of greater subtalar varus. Ankle valgus was measured with anteroposterior mortise views; a larger angle was indicative of greater ankle valgus. The analyses showed that feet with greater subtalar varus also showed statistically significantly greater valgus of the ankle mortise angles (P = .003). These results suggest that the ankle compensates for residual deformity of the subtalar joint in the coronal plane in patients treated for clubfoot. It also suggests that the configuration of the ankle during the course of treatment may warrant closer attention. LEVEL OF CLINICAL EVIDENCE: 2.

Ethylene/polar monomer copolymerization behavior of bis(phenoxy-imine)Ti complexes: formation of polar monomer copolymers.

Bis(phenoxy-imine) Ti complexes bearing a phenyl group ortho to the phenoxy-O can mediate the copolymerization of ethylene and 5-hexene-1-yl-acetate though they are group 4 transition metal catalysts.

Estrogen specifically stimulates expression and production of osteoprotegerin from rheumatoid synovial fibroblasts.

We studied the effects of estrogen on human fibroblast-like synovial cells in rheumatoid arthritis (RA-FLS) focusing on receptor activator of NF-kappaB ligand (RANKL) and its decoy receptor osteoprotegerin (OPG), the osteoclast formation and function regulators that have a substantial role in bone erosion of RA. Estrogen influences osteoporosis and the onset of RA clinically. The cellular responses of RA-FLS to estrogen are initiated via two high-affinity estrogen receptors (ERs). Culture of RA-FLS in the presence of 10(-6) M 17beta-estradiol (E2) increased expression of estrogen receptor (ER)-alpha, but not ER-beta. OPG mRNA expression was significantly increased, whereas RANKL mRNA was unaffected. E2 treatment also significantly increased the amount of OPG released in the culture supernatant. The increase of OPG and ER-alpha was specifically antagonized by the pure estrogen antagonist ICI 182780. Tamoxifen, a selective ER moderator, did not increase OPG. The results indicate that estrogen stimulates secretion of OPG from RA-FLS by acting on ER-alpha, which likely prevents bone erosion in RA.

Living ethylene/norbornene copolymerisation catalyzed by titanium complexes having two pyrrolide-imine chelate ligands.

Ethylene/norbornene copolymerisation behaviour of titanium complexes with two pyrrolide-imine chelate ligands is described.

Decoy receptor 3 expressed in rheumatoid synovial fibroblasts protects the cells against Fas-induced apoptosis.

OBJECTIVE: Decoy receptor 3 (DcR3), a newly identified member of the tumor necrosis factor receptor (TNFR) superfamily, is a soluble receptor that binds to members of the TNF family, including FasL, LIGHT, and TNF-like molecule 1A. DcR3 is mostly expressed in tumor cells, and it competitively inhibits binding of TNF to TNFRs. The present study was undertaken to investigate DcR3 expression in fibroblast-like synoviocytes (FLS) from patients with rheumatoid arthritis (RA) and osteoarthritis (OA), and to analyze the effects of DcR3 on Fas-induced apoptosis in RA FLS. METHODS: Expression of DcR3 in FLS was measured by reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blotting. FLS were incubated with DcR3-Fc chimera protein or transfected with DcR3 small interfering RNA (siRNA) using the lipofection method, before induction of apoptosis. Apoptosis induced by Fas in FLS was detected with TUNEL staining and Western blotting of caspase 8 and poly(ADP-ribose) polymerase. Finally, FLS were incubated with TNFalpha prior to Fas-induced apoptosis, expression of DcR3 was analyzed by quantitative RT-PCR, and apoptosis was measured. RESULTS: DcR3 was expressed in both RA FLS and OA FLS. DcR3-Fc protein inhibited Fas-induced apoptosis in FLS. Down-regulation of DcR3 in FLS by siRNA increased Fas-induced apoptosis. TNFalpha increased DcR3 expression and inhibited Fas-induced apoptosis in RA FLS, but not in OA FLS. CONCLUSION: DcR3 expressed in RA FLS is increased by TNFalpha and protects the cells against Fas-induced apoptosis. These findings indicate that DcR3 may be a possible therapeutic target in RA.

Unprecedented living olefin polymerization derived from an attractive interaction between a ligand and a growing polymer chain.

Ti complexes incorporating fluorine-containing phenoxy-imine chelate ligands (fluorinated Ti-FI catalysts) have been demonstrated to induce an unprecedented living polymerization effect with both ethylene and propylene, through an attractive interaction between the fluorine atom in the ligand and a beta-hydrogen atom on the growing polymer chain. With the aid of this attractive interaction, highly controlled living ethylene polymerization, highly-syndiospecific living propylene polymerization, the synthesis of unique block copolymers from ethylene and propylene, and the catalytic production of monodisperse polyethylene and Zn-terminated polyethylene have been realized. The attractive interaction provides a conceptually new strategy for the achievement of controlled living olefin polymerization.

Fluorine- and trimethylsilyl-containing phenoxy--imine Ti complex for highly syndiotactic living polypropylenes with extremely high melting temperatures.

A fluorine- and trimethylsilyl-containing phenoxy-imine titanium complex was synthesized and the structure was determined by an X-ray analysis. The complex on activation with MAO initiates highly controlled syndiospecific living propylene polymerization to form extremely high Tm syndiotactic polypropylenes (Mw/Mn = 1.05-1.08, Tm = 156-152 degrees C) at 0 or 25 degrees C. Moreover, at 50 degrees C, the complex afforded monodisperse syndiotactic polypropylene with very high Tm's of 149, 150 degrees C. In contrast, complexes having a t-Bu group instead of the silyl group provided lower tacticity polymers with much lower Tm's. In addition, we revealed the substituent effect that plays a key role for the highly controlled syndiospecific polymerization displayed by the catalyst.

Syndiospecific living propylene polymerization catalyzed by titanium complexes having fluorine-containing phenoxy-imine chelate ligands.

The propylene polymerization behavior of a series of Ti complexes featuring fluorine-containing phenoxy-imine chelate ligands is reported. The Ti complexes combined with methylalumoxane (MAO) can be catalysts for living and, at the same time, stereospecific polymerization of propylene at room temperature or above. DFT calculations suggest that the attractive interaction between a fluorine ortho to the imine nitrogen and a beta-hydrogen of a growing polymer chain is responsible for the achievement of room-temperature living propylene polymerization. Although the Ti complexes possess C(2) symmetry, they are capable of producing highly syndiotactic polypropylenes. (13)C NMR is used to demonstrate that the syndiotacticity is governed by a chain-end control mechanism and that the polymerization is initiated exclusively via 1,2-insertion followed by 2,1-insertion as the principal mode of polymerization. (13)C NMR spectroscopy also elucidated that the polypropylenes produced with the Ti complexes possess regio-block structures. Substitutions on the phenoxy-imine ligands have profound effects on catalytic behavior of the Ti complexes. The steric bulk of the substituent ortho to the phenoxy oxygen plays a decisive role in achieving high syndioselectivity for the chain-end controlled polymerization. Over a temperature range of 0-50 degrees C, Ti complex having a trimethylsilyl group ortho to the phenoxy oxygen forms highly syndiotactic, nearly monodisperse polypropylenes (94-90% rr) with extremely high peak melting temperatures (T(m) = 156-149 degrees C). The polymerization behavior of the Ti complexes can be explained well by the recently proposed site-inversion mechanism for the formation of syndiotactic polypropylene by a Ti complex having a pair of fluorine-containing phenoxy-imine ligands.

FI catalysts: new olefin polymerization catalysts for the creation of value-added polymers.

This contribution reports the discovery and application of phenoxy-imine-based catalysts for olefin polymerization. Ligand-oriented catalyst design research has led to the discovery of remarkably active ethylene polymerization catalysts (FI Catalysts), which are based on electronically flexible phenoxy-imine chelate ligands combined with early transition metals. Upon activation with appropriate cocatalysts, FI Catalysts can exhibit unique polymerization catalysis (e.g., precise control of product molecular weights, highly isospecific and syndiospecific propylene polymerization, regio-irregular polymerization of higher alpha-olefins, highly controlled living polymerization of both ethylene and propylene at elevated temperatures, and precise control over polymer morphology) and thus provide extraordinary opportunities for the syntheses of value-added polymers with distinctive architectural characteristics. Many of the polymers that are available via the use of FI Catalysts were previously inaccessible through other means of polymerization. For example, FI Catalysts can form vinyl-terminated low molecular weight polyethylenes, ultra-high molecular weight amorphous ethylene-propylene copolymers and atactic polypropylenes, highly isotactic and syndiotactic polypropylenes with exceptionally high peak melting temperatures, well-defined and controlled multimodal polyethylenes, and high molecular weight regio-irregular poly(higher alpha-olefin)s. In addition, FI Catalysts combined with MgCl(2)-based compounds can produce polymers that exhibit desirable morphological features (e.g., very high bulk density polyethylenes and highly controlled particle-size polyethylenes) that are difficult to obtain with conventionally supported catalysts. In addition, FI Catalysts are capable of creating a large variety of living-polymerization-based polymers, including terminally functionalized polymers and block copolymers from ethylene, propylene, and higher alpha-olefins. Furthermore, some of the FI Catalysts can furnish living-polymerization-based polymers catalytically by combination with appropriate chain transfer agents. Therefore, the development of FI Catalysts has enabled some crucial advances in the fields of polymerization catalysis and polymer syntheses.

Living copolymerization of ethylene with norbornene catalyzed by bis(pyrrolide-imine) titanium complexes with MAO.

Bis(pyrrolide-imine) Ti complexes in conjunction with methylalumoxane (MAO) were found to work as efficient catalysts for the copolymerization of ethylene and norbornene to afford unique copolymers via an addition-type polymerization mechanism. The catalysts exhibited very high norbornene incorporation, superior to that obtained with Me(2)Si(Me(4)Cp)(N-tert-Bu)TiCl(2) (CGC). The sterically open and highly electrophilic nature of the catalysts is probably responsible for the excellent norbornene incorporation. The catalysts displayed a marked tendency to produce alternating copolymers, which have stereoirregular structures despite the C(2) symmetric nature of the catalysts. The norbornene/ethylene molar ratio in the polymerization medium had a profound influence on the molecular weight distribution of the resulting copolymer. At norbornene/ethylene ratios larger than ca. 1, the catalysts mediated room-temperature living copolymerization of ethylene and norbornene to form high molecular weight monodisperse copolymers (M(n) > 500,000, M(w)/M(n) < 1.20). (13)C NMR spectroscopic analysis of a copolymer, produced under conditions that gave low molecular weight, demonstrated that the copolymerization is initiated by norbornene insertion and that the catalyst mostly exists as a norbornene-last-inserted species under living conditions. Polymerization behavior coupled with DFT calculations suggested that the highly controlled living polymerization stems from the fact that the catalysts possess high affinity and high incorporation ability for norbornene as well as the characteristics of a living ethylene polymerization though under limited conditions (M(n) 225,000, M(w)/M(n) 1.15, 10-s polymerization, 25 degrees C). With the catalyst, unique block copolymers [i.e., poly(ethylene-co-norbornene)(1)-b-poly(ethylene-co-norbornene)(2), PE-b-poly(ethylene-co-norbornene)] were successfully synthesized from ethylene and norbornene. Transmission electron microscopy (TEM) indicated that the PE-b-poly(ethylene-co-norbornene) possesses high potential as a new material consisting of crystalline and amorphous segments which are chemically linked.

Living polymerization of ethylene catalyzed by titanium complexes having fluorine-containing phenoxy-imine chelate ligands.

Seven titanium complexes bearing fluorine-containing phenoxy-imine chelate ligands, TiCl(2)[eta(2)-1-[C(H)=NR]-2-O-3-(t)Bu-C(6)H(3)](2) [R = 2,3,4,5,6-pentafluorophenyl (1), R = 2,4,6-trifluorophenyl (2), R = 2,6-difluorophenyl (3), R = 2-fluorophenyl (4), R = 3,4,5-trifluorophenyl (5), R = 3,5-difluorophenyl (6), R = 4-fluorophenyl (7)], were synthesized from the lithium salt of the requisite ligand and TiCl(4) in good yields (22%-76%). X-ray analysis revealed that the complexes 1 and 3 adopt a distorted octahedral structure in which the two phenoxy oxygens are situated in the trans-position while the two imine nitrogens and the two chlorine atoms are located cis to one another, the same spatial disposition as that for the corresponding nonfluorinated complex. Although the Ti-O, Ti-N, and Ti-Cl bond distances for complexes 1 and 3 are very similar to those for the nonfluorinated complex, the bond angles between the ligands (e.g., O-Ti-O, N-Ti-N, and Cl-Ti-Cl) and the Ti-N-C-C torsion angles involving the phenyl on the imine nitrogen are different from those for the nonfluorinated complex, as a result of the introduction of fluorine atoms. Complex 1/methylalumoxane (MAO) catalyst system promoted living ethylene polymerization to produce high molecular weight polyethylenes (M(n) > 400 000) with extremely narrow polydispersities (M(w)/M(n) < 1.20). Very high activities (TOF > 20 000 min(-1) atm(-1)) were observed that are comparable to those of Cp(2)ZrCl(2)/MAO at high polymerization temperatures (25, 50 degrees C). Complexes 2-4, which have a fluorine atom adjacent to the imine nitrogen, behaved as living ethylene polymerization catalysts at 50 degrees C, whereas complexes 5-7, possessing no fluorine adjacent to the imine nitrogen, produced polyethylenes having M(w)/M(n) values of ca. 2 with beta-hydrogen transfer as the main termination pathway. These results together with DFT calculations suggested that the presence of a fluorine atom adjacent to the imine nitrogen is a requirement for the high-temperature living polymerization, and the fluorine of the active species for ethylene polymerization interacts with a beta-hydrogen of a polymer chain, resulting in the prevention of beta-hydrogen transfer. This catalyst system was used for the synthesis of a number of unique block copolymers such as polyethylene-b-poly(ethylene-co-propylene) diblock copolymer and polyethylene-b-poly(ethylene-co-propylene)-b-syndiotactic polypropylene triblock copolymer from ethylene and propylene.