The modified Song isotherm model: application to multisolute sorption of phenols in organoclays using the ideal adsorbed solution theory.

The three-parameter (K, b, and n) Song isotherm model was slightly modified to make it possible to obtain analytical integration of the spreading pressure integral. The modified Song model (MSM) allows more efficient and accurate calculation of the ideal adsorbed solution theory (IAST). The MSM also satisfies the Henry's law and the Freundlich model at low and high concentrations, respectively, and reverts to the Langmuir and the linear models when n equals zero and one, respectively. Approximate values of each parameter could be estimated from a plot of log (q/c) versus log c; the partition coefficient in the Henry's law region (K) and the Freundlich index (n) can be estimated from the ordinate value of the low-concentration asymptote and the slope of the high-concentration asymptote, respectively, and the parameter (b) can be estimated from the solution-phase concentration of the intersection point of the two asymptotes. The MSM was fitted to the single-solute sorption of 2-chloro-, 3-cyano-, and 4-nitrophenol onto montmorillonites modified with either HDTMA cation or TMA/HDTMA dual cations. The ideal adsorbed solution theory (IAST) combined with either dual-mode model, Khan model or MSM as a single-solute isotherm model was used to predict three bisolute and one trisolute sorption to organoclays. The Sheindorf-Rebhun-Sheintuch (SRS) and Murali-Aylmore (M-A) were also used to predict bisolute sorption to organoclays. The IAST predictions were generally in good agreement with the multisolute sorption data. The advantages of MSM over other three-parameter models were fully discussed.

Status of the contralateral rotator cuff in patients undergoing rotator cuff repair.

BACKGROUND: Although the prevalence of rotator cuff tear (RCT) in the general population has been analyzed, little information is available on the status of the opposite-side rotator cuff in patients who have undergone arthroscopic rotator cuff repair. PURPOSE/HYPOTHESIS: To identify the characteristics of the contralateral shoulder and to identify factors associated with RCT of the contralateral shoulder in patients who underwent surgery for symptomatic RCT. The hypothesis was that the prevalence of RCT in the contralateral shoulder would be higher in patients with increasingly larger cuff tears requiring surgical intervention. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: The study cohort consisted of 140 patients with RCT who underwent arthroscopic rotator cuff repair. Opposite-shoulder rotator cuff tendons of all patients were evaluated by ultrasonography. Demographic information and factors related to contralateral RCT were investigated, and risk factors associated with contralateral RCT were assessed. RESULTS: Of the 140 patients who underwent arthroscopic rotator cuff repair, 54 (38.6%) had an RCT of the contralateral shoulder. Of 51 patients with partial-thickness and small-sized full-thickness tears of the operated shoulder, 35 (68.6%) had no tears; 14 (27.5%) had partial-thickness tears; and 2 (3.9%) had small-sized full-thickness tears of the contralateral shoulder. Of 75 patients with medium-sized full-thickness tears, 43 (57.3%) had no tears; 12 (16%) had partial-thickness tears; and 20 (26.7%) had full-thickness tears of the contralateral shoulder. Of 14 patients with large to massive full-thickness tears, 8 (57.1%) had no tears; 1 (7.1%) had a partial-thickness tear; and 5 (35.7%) had full-thickness tears of the contralateral shoulder. The prevalence of RCT of the contralateral shoulder differed significantly among groups classified by tear size (P=.007). The mean American Shoulder and Elbow Surgeons score was significantly lower in the RCT than in the nontear group (55.8±16.9 vs 61.6±13.3; P=.03). Of 29 subjects with symptomatic tears involving the nondominant arm, 17 (58.6%) had contralateral asymptomatic RCT, compared with 37 of 111 (33.3%) subjects with symptomatic tears involving the dominant arm (P=.007). CONCLUSION: The prevalence of RCT of the contralateral asymptomatic shoulder tends to be higher in patients with more symptomatic RCT on one side, in patients with medium-sized or larger RCT in the operated shoulder, and in patients with symptomatic RCT in the nondominant arm.

Deltoid muscle injury scratched by an osteophyte on the greater tuberosity of the humeral head: an unusual cause of shoulder pain.

Few reports to date have discussed acute deltoid muscle injury, including partial or complete deltoid muscle detachment from its origin. The present report describes a different pathomechanism and clinical manifestations of deltoid muscle injury. A 52-year-old man experienced acute severe pain in the right shoulder as a result of abrupt elevation of the arm. The deltoid muscle had apparently been scratched by an osteophyte on the greater tuberosity. After arthroscopic excision of the osteophyte, the symptoms resolved completely.

Accuracy of soft tissue balancing in TKA: comparison between navigation-assisted gap balancing and conventional measured resection.

Equalized rectangular extension and flexion gaps are considered desirable to ensure proper kinematics in total knee arthroplasty (TKA). We compared soft tissue balancing in TKAs performed using navigation-assisted gap-balancing (60 knees) and conventional measured resection (56 knees). The outlier of soft tissue balancing was defined as a gap difference >3 mm between the medial and lateral sides in 90 degrees flexion and extension. Medial or lateral outliers in extension or flexion were observed in 12% (7 of 60) navigation TKAs and 25% (14 of 56) conventional TKAs (p = 0.028). There were more outliers in flexion-extension gap difference on the medial side in the conventional (23%) than in the navigation-assisted (5%) group (p = 0.025). However, the proportion of flexion gap difference, extension gap difference, and lateral gap difference outliers did not differ significantly between the two groups (n.s.). Additionally, clinicoradiologic outcomes were similar for the two groups except for the postoperative mechanical axis outlier (p = 0.012). Navigation-assisted soft tissue balancing in TKA reduced not only the postoperative alignment outlier, but also the medial gap difference and achieved a more rectangular flexion and extension gap compared with conventional TKA.

Vesicocutaneous fistula presenting groin abscess and chronic osteomyelitis in pubic bone.

The authors report a case of bladder fistula associated with a medial thigh cutaneous fistula and chronic osteomyelitis of the pubic bone 11 years after surgery for a pelvic bone fracture and bladder rupture. In the presenting case, despite the clinical suspicion, none of the diagnostic tools demonstrated the bladder fistula preoperatively. This case suggests that bladder repair should be prepared, even if the bladder fistula cannot be confirmed by imaging studies because the amount of urine leakage can be minimal or the fistula can close spontaneously.

Are portable imaging intraoperative radiographs helpful for assessing adequate acetabular cup positioning in total hip arthroplasty?

Despite advances in surgical techniques and instrumentation, current intra-operative estimations of acetabular version in total hip arthroplasty are of limited accuracy. In the present study, two experienced orthopedic surgeons compared intra-operatively measured (using portable imaging) anteversions and vertical inclinations of acetabular components with those measured using standardized radiographs post-operatively in 40 patients. Of the all vertical inclinations measured from intra-operative radiographs, 72.5% (n=29) were within +/-2 degrees , and 97.5% (n=39) were within +/-5 degrees of those determined using post-operative radiographs, and for anteversion, 52.5% (n=21) were within +/-2 degrees , and 97.5% (n=39) were within +/-5 degrees . Post-operative radiographs demonstrated that 90.0% (n=36) of vertical inclinations and anteversions were within the adequate zone. Obviously, our method has its limitations, but the authors conclude that the method described in this article better allows surgeons to verify acetabular version intra-operatively. In particular, the described method is suitable in cases with a deformed acetabular anatomy and difficult revision surgery.

Three-parameter empirical isotherm model: its application to sorption onto organoclays.

A new three-parameter empirical isotherm model (the Song isotherm model, hereinafter) is proposed. This model satisfies the Henry's law and the Freundlich isotherm model in the low and high concentration ranges, respectively. We applied this model to the single-solute sorption of 2-chloro-, 3-cyano-, and 4-nitrophenol from water to montmorillonites organically modified with either hexadecyltrimethylammonium (HDTMA) cation or both HDTMA and tetramethylammonium (TMA) dual cations. Sorption to organoclays (i.e., organically modified clays) modified with the long-hydrocarbon chain organic cations or the short- and long-hydrocarbon chain dual organic cations usually occurs by a partition mechanism. Sorption of polar organic compounds to organoclays, however, becomes nonlinear when the solution-phase concentration covered is more than 3 orders of magnitude. The three parameters contained in the presently proposed model could be estimated from the plot, log(q/c) versus log c. The partition coefficient in the Henry's law region (K) can be estimated from the ordinate value of the asymptote in the low concentration region, the Freundlich index (n) can be estimated from the slope of the asymptote in the high concentration region, and the parameter (beta) corresponding to the crossover point can be estimated from the intersection point of the two asymptotes. By performing nonlinear curve fitting to the raw data, q versus c, using the initial guesses estimated from the manipulated data, log-(q/c) versus log c, the optimum set of parameters could be determined without worrying much over the annoying local minima. The Song model was compared with other existing two- and three-parameter isotherm models. The Song model fitted our experimental data better than the Langmuir and Freundlich models and showed nearly the same goodness-of-fit as the Redlich-Peterson and dual-mode models. The obvious merit of the Song model is that it provides us with the partition coefficient in the Henry's law region. The organic carbon-normalized partition coefficients in the Henry's law region were found to be about 1 order of magnitude higher than the corresponding octanol-water partition coefficients, at least for the phenolic compounds covered in this study.