Ambient temperature during pregnancy and risk of maternal hypertensive disorders: A time-to-event study in Johannesburg, South Africa

Hypertensive disorders in pregnancy are a leading cause of maternal and perinatal mortality and morbidity. We evaluate the effects of ambient temperature on risk of maternal hypertensive disorders throughout pregnancy. We used birth register data for all singleton births (22-43 weeks' gestation) recorded at a tertiary-level hospital in Johannesburg, South Africa, between July 2017-June 2018. Time-to-event analysis was combined with distributed lag non-linear models to examine the effects of mean weekly temperature, from conception to birth, on risk of (i) high blood pressure, hypertension, or gestational hypertension, and (ii) pre-eclampsia, eclampsia, or HELLP (hemolysis, elevated liver enzymes, low platelets). Low and high temperatures were defined as the 5th and 95th percentiles of daily mean temperature, respectively. Of 7986 women included, 844 (10.6%) had a hypertensive disorder of which 432 (51.2%) had high blood pressure/hypertension/gestational hypertension and 412 (48.8%) had pre-eclampsia/eclampsia/HELLP. High temperature in early pregnancy was associated with an increased risk of pre-eclampsia/eclampsia/HELLP. High temperature (23 °C vs 18 °C) in the third and fourth weeks of pregnancy posed the greatest risk, with hazard ratios of 1.76 (95% CI 1.12-2.78) and 1.79 (95% CI 1.19-2.71), respectively. Whereas, high temperatures in mid-late pregnancy tended to protect against pre-eclampsia/eclampsia/HELLP. Low temperature (11°) during the third trimester (from 29 weeks' gestation) was associated with an increased risk of high blood pressure/hypertension/gestational hypertension, however the strength and statistical significance of low temperature effects were reduced with model adjustments. Our findings support the hypothesis that high temperatures in early pregnancy increase risk of severe hypertensive disorders, likely through an effect on placental development. This highlights the need for greater awareness around the impacts of moderately high temperatures in early pregnancy through targeted advice, and for increased monitoring of pregnant women who conceive during periods of hot weather.

Arthroplastie trapézo-métacarpienne par rotation trapézo-métacarpienne en îlot. Étude anatomique et technique opératoire

INTRODUCTION

To correct trapezium dysplasia we propose a new surgical technique. The operation consists of a double osteotomy of the trapezium and of the first metacarpal base, thereby harvesting the trapezo-metacarpal joint en-bloc. Vascularization is via the radial artery pedicle divided at the first web level. The articular block is then rotated 180 degrees on the longitudinal axis of the thumb.

METHOD

An anatomic study was performed on six fresh cadaveric upper limbs. The radial artery was injected with colored latex, 5 cm above the wrist. The peri-articular vascular network was studied. The feasibility of harvesting and rotating the articular bloc after double osteotomy of the first metacarpal basis and the trapezium was also studied.

RESULTS

In all the cases, the radial artery was present with branches supplying the peri-articular vascular network. After double osteotomy of the metacarpal base and of the trapezium, the articular bloc was harvested and rotated by 180 degrees. We describe the surgical technique.

DISCUSSION AND CONCLUSION

The surgical technique has been confirmed with the first clinical cases. The double oblique osteotomy with rotation of the articular bloc corrects trapezium dysplasia and preserves first metacarpal abduction. This procedure appears to be a solution in cases of trapezium dysplasia associated with instability and early stage osteoarthritis.

[Vascularized bone transfers in the wrist and hand]

More and more vascularised bone transfer (VBT) sites, free or pedicled, in the wrist and hand have been described since the 1980s. In the distal forearm, two main VBT: the fibula and the iliac crest, are used for large bone loss (> 6 cm) or for radio-carpal reconstruction. We report our experience of radio-carpal reconstruction using the distal-radio-ulnar joint transfer. At the carpal level, VBT are essentially used for "difficult" scaphoid pseudarthrosis: osteonecrosis, sclerotic bone or failures of conventional grafts and for lunate necrosis. Two pedicled VBT are frequently used for the scaphoid, a graft harvested from the antero-medial part of the distal radius (Kuhlmann) or a graft harvested from the postero-lateral part of the distal radius (Zaidemberg). For the trapezo-metacarpal joint, two new articular pedicle transfers can be used in some cases of trapezo-metacarpal arthritis. At the hand level, VBT are used for distal bone loss, "en bout de chaîne". Bone vascularisation is indispensable to preserve sub-chondral bone and avoid articular destruction. In children VBT are necessary to preserve the growth cartilage.

[Linburg-Comstock syndrome. Epidemiologic and anatomic study, clinical applications]

The Linburg-Comstock (LC) syndrome is distinguished by the inability to actively flex the interphalangeal (IP) joint of the thumb without simultaneously flexing the distal IP joint of the index finger. Any resistance to this 'parasitic' reaction causes pain on the palmar side of the wrist or in the distal part of the forearm; this is due to an anomalous tendinous connection between the flexor pollicus longus (FPL) and the flexor digitorum profundus (FDP). An epidemiological study was carried out on 264 individuals (a total of 528 hands were examined), and the LC syndrome was found in 98 subjects (37%); women were more frequently affected than men, and bilaterally rather than unilaterally. In addition, we dissected 26 fresh cadaver upper limbs, and in seven cases found an anomalous connection between FPL and FDP. We also examined the case of a young violinist with bilateral LC syndrome, who complained of pain in the distal part of the left forearm after prolonged musical exercises. Surgical investigation determined a complete fusion between FPL and FDP of the index with a common tendon. Treatment consisted of splitting this common tendon to form two separate tendons, thereby permitting a certain degree of independence between the thumb and index finger, and which considerably improved the violinist's musical performance. A review of the literature showed that there was a large quantity of anatomical descriptions available on these types of connection. Certain publications also provide an extremely precise report on the anthropological significance of these anomalies.

[Anatomical study of interosseous flaps and the concept of postero-anterior interosseous flap. Preliminary report]

The postero-anterior interosseous flap uses the distal network of the posterior and anterior interosseous arteries. With this flap the authors would like to point out all the possibilities of reverse fascio-cutaneous flaps offered by the interosseus arteries. An anatomic study has been carried out with both a literature review and a cadaveric study. The authors studied the distal interosseous anatomy on 40 fresh upper arms after colored latex injection of the anterior interosseous artery near its origin. A distal anastomosis between anterior and posterior interosseous arteries was present in 38 cases. This anastomosis was situated at an average of 25 mm from the radio-carpal joint. The authors found the fascio-cutaneous artery branch of the anterior interosseous flap in 40 cases, but its origin is variable. Therefore, the anterior interosseous flap was possible in every case but the pedicle length was variable. The surgical technique must begin by a distal exploration of the vascular network. After this exploration the flap is chosen in function with the anatomic possibilities and the cutaneous defect. The authors have already used several kinds of reverse interosseous flap: anterior (6 cases), posterior (11 cases) and recently, postero-anterior (2 cases). With the postero-anterior flap the authors will show the large range of flap possibilities offered by the interosseous arteries for the cutaneous defects of the dorsum of the hand.

[Transmission of pronation-supination movements in the wrist]

The wrist plays an essential in role the transmission of pronosupination movements. The four main muscles responsible for these movements are situated above the radiocarpal joint. This anatomic configuration allows a passive movement: Radio Metacarpal Rotation or RMR which is analysed here. Radio Metacarpal Rotation varies according to grip and the couple which is applied distally. An apparatus has been designed to simultaneously measure the angle, the force of grip and the couple. Radio Metacarpal Rotation is firstly measured with the wrist relaxed (grip strength < 5 N) and a distally applied rotation couple of 0.2 N.m in the supination direction and 0.5 N.m in the pronation direction. Secondly, the patient is asked to maintain a grip strength between 80 N and 100 N, and a couple of 1 N.m is applied distally in each direction. One hundred wrists were evaluated. We have looked for the rotation centers of active pronosupination and Radio Metacarpal Rotation. A three dimensional motion analysis device was used (ELITE system). Thirty normal wrists were evaluated. An anatomic study of the radiocarpal ligaments stretched by Radio Metacarpal Rotation was carried out on ten cadaver wrists. When the wrist is relaxed: there is an average Radio Metacarpal Rotation of 42 degrees. This Radio Metacarpal Rotation is reduced when grip is tightened. We have defined a locking test based on these two parameters. This clinical test is represented by two curves on a graph. The active pronosupination center and the radio metacarpal center do not coincide. The center of active pronosupination is situated near the center of the ulnar head and the center of radio-metacarpal rotation is always more lateral. On the anatomical preparations, we found a helicoidal configuration of the radiocarpal ligaments: a ligamentous double helix pronosupination. Radio Metacarpal Rotation interferes with transmission of pronosupination movements. When the wrist is not well locked there is a large lateral sweeping between radius and scaphoid. This sliding at the level of the cartilage can head to development of osteoarthritis of the wrist with a horizontal scaphoid and the good cartilage results after proximal row carpectomy. Radio Metacarpal Rotation must be taken into account when a prothesis designing. We propose a wrist locking test. The results of this test are directly related to the capacity of the joint surfaces to transmit pronosupination movements. Radio Metacarpal Rotation shows the importance of the horizontal plane in the wrist and its essential role in the transmission of pronosupination movements.

[Arthroplasty of the wrist by island transfer of the inferior radio-ulnar joint]

In cases of advanced osteoarthritis of the wrist, in which the radiocarpal and midcarpal joint spaces have been destroyed, the authors propose island transfer of the distal radioulnar joint. They studied the blood supply of the distal radioulnar joint from the interosseous arteries on 40 fresh cadaver upper limbs. The anatomical study showed that the dorsal epiphyseal periosteal network was supplied by the lower perforator of the anterior interosseus artery in every case and by the posterior interosseous artery in 38 out of 40 cases. The distal radioulnar joint can be harvested "en bloc" and rotated 90 degrees so that the joint space can be placed in radio-carpal position while preserving its blood supply on the anterior interosseous pedicle. The authors describe their operating technique and present their first clinical case. This new operation represents a non prosthetic alternative to arthrodesis.