A tropical stratopause precursor for sudden stratospheric warmings.

Dramatic meteorological phenomena in the winter polar stratosphere known as Sudden Stratospheric Warming (SSW) events are well recognized for their impacts felt across the whole atmosphere. Apart from the influence of tropospheric forcing and stratospheric control, many studies have addressed the possible role of external factors on the occurrence of SSW events. Here, with the help of reanalysis datasets, we present a hitherto unexplored connection between the tropical upper stratosphere and the polar vortex. We identify enhanced planetary wave driving around the tropical stratopause and poleward progression of the zero-wind line as early indicators for the occurrence of SSW events. We demonstrate that the poleward progression of the zero wind line results in efficient focusing of planetary waves into the polar vortex which culminates in its disruption. Statistically, nearly 70% of the SSW events that took place so far have been preceded by enhanced tropical stratopause wave driving which points towards identifying this as a potential precursor for the occurrence of SSW events. After the year 2000, significantly a greater number of SSW events have been found to be preceded by enhanced tropical stratopause wave driving.

Management of severe congenital flexion deformity of the knee using Ilizarov method.

The aim of this study was to examine the effectiveness of Ilizarov method in severe congenital flexion deformity of the knee. This was a retrospective study of eight consecutive bilateral cases (five girls and three boys, with mean age of 4 years, involving 16 knees) with minimum 2-year follow-up. Four patients had multiple congenital contractures and two patients each had popliteal pterygium syndrome and complete tibial hemimelia. All patients were treated with Ilizarov fixator and gradual correction (additional soft tissue releases in three knees). Six patients had bilateral foot and ankle deformity treated with the same fixator, and cases with tibial hemimelia had centralization of fibula and quadriceps reconstruction. Flexion deformity could be corrected in all cases. Mean duration of dynamic phase was 78.5 (55-108) days, that of static phase was 42.4 (7-100) days, and total duration of external fixation was 120.9 (87-186) days. At mean follow-up of 34.5 (23-60) months, flexion deformity improved from the preoperative value of 74.9° (50°-130°) to 13.7° (10°-16°), and passive arc of motion of knee improved from the preoperative value of 38.8° (20°-55°) to 83.6° (55°-110°). Both were statistically significant (P < 0.0001). All patients (previously nonambulatory) were ambulatory with brace and support. All patients faced pin-tract and skin complications that were successfully managed. Ilizarov method is effective in severe congenital flexion deformity of the knee in improving ambulatory status. Realignment of quadriceps mechanism and limb mechanical axis (including ankle and foot deformities) must be given due importance. Minor recurrences of deformity must be expected in all cases.

Reconstruction by bone transport after resection of benign tumors of tibia: A retrospective study of 38 patients.

BACKGROUND: The commonly used reconstructive options after post resection defects in bone tumors like megaprosthesis, autograft, allograft, bone graft substitutes and recycled bone have their own demerits on a long term. Bone transport that regenerates patient's own bone is a less explored option of reconstruction after resection of benign bone tumors and reports on this are limited. This technique is very much relevant in tibia where Ilizarov fixator is surgeon and patient friendly. We report our experience. MATERIALS AND METHODS: This is a retrospective series of resection and bone transport in 38 patients with benign tumor of tibia. There were 14 males and 24 females with mean age of 23.40 years (range 9-40 years). Lesion was located in proximal third tibia in 27, middle third in two and distal third in nine patients. The diagnosis was giant cell tumor in 32, chondroblastoma in three, chondromyxoid fibroma, enchondroma and desmoplasic fibroma in one patient each. The resection was intercalary in 28 and transarticular in 10 patients. Osteosynthesis was monofocal in three, bifocal in 31 and polyfocal in four cases. RESULTS: Mean followup was 7.22 years (range 1.5-15 years). Mean resection length was 10.21 cm (range 3-22 cm). The mean duration of external fixator was 308.03 days (range 89-677 days) and mean external fixator index was 36.14 days/cm (range 16.84-97.43 days/cm). Twelve patients had difficulties in the form of 11 problems and five obstacles that were successfully managed. None of the patients had local recurrence of tumor or any long term complication. Mean Musculo-skeletal Tumour Society score at final followup was 27.18 (90.60%). CONCLUSIONS: Bone transport is an excellent option after resection of benign tumors of tibia with good local control and functional outcome, despite minor difficulties that need timely management.

Cosmetic lower limb lengthening by Ilizarov apparatus: what are the risks?

BACKGROUND: Compelled by the psychosocial implications of short stature, patients with short stature are increasingly undergoing distraction osteogenesis for cosmetic limb lengthening. To the degree that this is true, evaluation of the risks and benefits of this treatment are very important, but to date, there are few studies reporting on using distraction osteogenesis for this indication. QUESTIONS/PURPOSES: We reviewed a group of patients undergoing cosmetic lower-extremity lengthening in terms of (1) soft tissue challenges, (2) bone-related complications, and (3) functional and subjective clinical outcomes. METHODS: The study was retrospective by reviewing data from medical records and radiographs. Between 1983 and 2006, we treated 138 somatically normal patients with bilateral lower-limb distraction osteogenesis for cosmetic purposes at our center using an Ilizarov external fixator, of whom 131 (95%; 65 males, 66 females) had complete clinical and radiographic data a minimum of 1 year after treatment (mean, 6 years; range, 1-14 years) and were reviewed for this report. The mean age of these patients was 25 years (range, 14-68 years) and their mean preoperative height was 159 cm (range, 130-174 cm). One hundred twenty-four (95%) patients had lengthening of the tibia alone, of which 66 (53%) were monofocal and 58 (47%) were bifocal. Six patients (4.58%) had crossed contralateral lengthening of the femur and tibia and one patient (0.76%) had bilateral lengthening of the femur. The mean height gained was 6.9 cm (range, 2-13 cm), 7.3 cm (range, 3.5-13 cm) in males and 6.5 cm (range, 2-13 cm) in females. The mean lengthening, maturation, and external fixator indexes were 12 days/cm (range, 4.3-24 days/cm), 19 days/cm (range, 5.2-63 days/cm), and 31 days/cm (range, 12-78 days/cm), respectively. RESULTS: Forty-eight patients (37%) had 59 complications related to treatment. Thirty-seven were soft tissue related (28%), of which 17 (46%) needed reinterventions, and 22 were bone related (17%), of which 16 (73%) needed reinterventions. At final followup, the outcome was excellent for 72 patients (55%), good for 52 (40%), satisfactory for six (4.58%), and poor for one (0.77%). One hundred thirty of 131 patients subjectively felt satisfied and had improved self-esteem. CONCLUSIONS: Distraction osteogenesis using the Ilizarov external fixator is an option for carefully selected motivated patients with awareness of this technique. Soft tissue and bone-related complications including those that necessitate reinterventions should be expected during the course of treatment, although most can be managed without permanent sequelae or disability. Future studies with more robust methods will need to determine whether the risks and benefits of this procedure are well balanced. Preoperative counseling, considering the ethical questions this procedure can raise, is of paramount importance for the patient to weigh the risk versus anticipated benefits. Studies from other centers will be important as we move forward. LEVEL OF EVIDENCE: Level IV, therapeutic study. See the Instructions for Authors for a complete description of levels of evidence.