Gavriil Abramovich Ilizarov (russian: Гавриил Абрамович Илизаров; 15 June 1921 – 24 July 1992) was a Soviet
physician
A physician (American English), medical practitioner (Commonwealth English), medical doctor, or simply doctor, is a health professional who practices medicine, which is concerned with promoting, maintaining or restoring health through th ...
, known for inventing the
Ilizarov apparatus
In medicine, the Ilizarov apparatus is a type of external fixation apparatus used in orthopedic surgery to lengthen or to reshape the damaged bones of an arm or a leg; used as a limb-sparing technique for treating complex fractures and open bone ...
for lengthening limb bones and for the method of surgery named after him, the
Ilizarov surgery.
Life and work
Ilizarov was born the eldest of six children to a poor
Jewish
Jews ( he, יְהוּדִים, , ) or Jewish people are an ethnoreligious group and nation originating from the Israelites Israelite origins and kingdom: "The first act in the long drama of Jewish history is the age of the Israelites""The ...
family in
Białowieża
Białowieża ( be, Белавежа, Biełavieža) is a village (population 2,000 as of 2002) in Poland's Podlaskie Voivodeship, Podlasie Province, in the middle of the Białowieża Forest, to which it gave its name. The village is some east of ...
,
Polesie Voivodeship
Polesie Voivodeship ( pl, województwo poleskie) was an administrative unit of interwar Poland (1918–1939), named after the historical region of Polesia. It was created by the Council of Ministers of the Second Polish Republic on February 19, 1 ...
,
Poland
Poland, officially the Republic of Poland, is a country in Central Europe. It is divided into 16 administrative provinces called voivodeships, covering an area of . Poland has a population of over 38 million and is the fifth-most populous ...
. In 1928, the family moved to the parents of his father in the town of
Qusar
Qusar District (; az, Qusar rayonu; lez, КцIар район, script=Latn) is one of the 66 districts of Azerbaijan. It is located in the north-east of the country and belongs to the Guba-Khachmaz Economic Region. The district borders the dis ...
in
Azerbaijan
Azerbaijan (, ; az, Azərbaycan ), officially the Republic of Azerbaijan, , also sometimes officially called the Azerbaijan Republic is a transcontinental country located at the boundary of Eastern Europe and Western Asia. It is a part of th ...
, near
Qırmızı Qəsəbə
Qırmızı Qəsəbə (, ), translated as "Red Town" (russian: Красная Слобода, ; he, , ), is a village and municipality in the Quba District of Azerbaijan. It has a population of approximately 3,598 people. Outside of Israel and th ...
. His father, Abram Ilizarov, was a
Mountain Jew
Mountain Jews or Caucasus Jews also known as Juhuro, Juvuro, Juhuri, Juwuri, Juhurim, Kavkazi Jews or Gorsky Jews ( he, יהודי קווקז ''Yehudey Kavkaz'' or ''Yehudey he-Harim''; russian: Горские евреи, translit=Gorskie Yevrei ...
from Qusar, while his mother, Golda Rosenblum, was of
Ashkenazi Jewish
Ashkenazi Jews ( ; he, יְהוּדֵי אַשְׁכְּנַז, translit=Yehudei Ashkenaz, ; yi, אַשכּנזישע ייִדן, Ashkenazishe Yidn), also known as Ashkenazic Jews or ''Ashkenazim'',, Ashkenazi Hebrew pronunciation: , singu ...
ancestry. In 1939, he graduated from
Buynaksk
Buynaksk (russian: Буйна́кск; kum, Шура / Темирхан-Шура, ''Şura / Temirxan-Şura'') is a town in the Republic of Dagestan, Russia, located at the foothills of the Greater Caucasus on the Shura-Ozen River, southwest of ...
Medical
Rabfak
Rabfak (from russian: рабфак, a syllabic abbreviation of рабочий факультет, ''rabochiy fakultet'', "workers' faculty") was a type of educational institution in the Soviet UnionBerthold Unfried''"Ich bekenne": Katholische Beic ...
, an educational establishment set up to prepare workers and peasants for higher education, and he entered the
Crimea Medical School in
Simferopol
Simferopol () is the second-largest city in the Crimea, Crimean Peninsula. The city, along with the rest of Crimea, is internationally recognised as part of Ukraine, and is considered the capital of the Autonomous Republic of Crimea. However, ...
. After the outbreak of the
Great Patriotic War
The Eastern Front of World War II was a theatre of conflict between the European Axis powers against the Soviet Union (USSR), Poland and other Allies, which encompassed Central Europe, Eastern Europe, Northeast Europe (Baltics), and Sout ...
in 1941, the school was
evacuated to
Kyzylorda
Kyzylorda ( kk, Қызылорда, translit=Qyzylorda, ), formerly known as Kzyl-Orda (russian: Кзыл-Орда), Ak-Mechet (Ак-Мечеть), Perovsk (Перовск), and Fort-Perovsky (Форт-Перовский), is a city in south-cen ...
in
Kazakhstan
Kazakhstan, officially the Republic of Kazakhstan, is a transcontinental country located mainly in Central Asia and partly in Eastern Europe. It borders Russia to the north and west, China to the east, Kyrgyzstan to the southeast, Uzbeki ...
.
After finishing school in 1944, Ilizarov was sent to a rural hospital in Dolgovka, a village in
Kurgan Oblast
Kurgan Oblast (russian: Курга́нская о́бласть, ''Kurganskaya oblast'') is a federal subject of Russia (an oblast). Its administrative center is the city of Kurgan. In June 2014, the population was estimated to be 874,100,Kurgan ...
in
Siberia
Siberia ( ; rus, Сибирь, r=Sibir', p=sʲɪˈbʲirʲ, a=Ru-Сибирь.ogg) is an extensive geographical region, constituting all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has been a part of ...
, 2000 km east of Moscow. In 1950, he obtained a position within a General Surgery Department of the Kurgan Regional Hospital, which included a duty as a surgeon with the
air ambulance
Air medical services is a comprehensive term covering the use of air transportation, aeroplane or helicopter, to move patients to and from healthcare facilities and accident scenes. Personnel provide comprehensive prehospital and emergency and cri ...
. In 1955, he became Chief of the Department of Trauma and Orthopaedics in the Regional Hospital for War Veterans in Kurgan.
[V.I. Shevtsov, I.L. Smirnova, L.G. Saldina. ]
G.A. Ilizarov: many years of efforts, searches and victories. The chronicle of scientific-and-practical and social activities (to the 85 anniversary)
'. Genius of Orthopedics (Гений Ортопедии) 2 (2006), p.5 (in Russian).
Bone experiments
![Ilizarov2](https://upload.wikimedia.org/wikipedia/commons/f/f6/Ilizarov2.jpg)
Ilizarov's residency was carried out in
orthopedic surgery
Orthopedic surgery or orthopedics ( alternatively spelt orthopaedics), is the branch of surgery concerned with conditions involving the musculoskeletal system. Orthopedic surgeons use both surgical and nonsurgical means to treat musculoskeletal ...
, during which he developed an
external fixator
External fixation is a surgical treatment wherein rods are screwed into bone and exit the body to be attached to a stabilizing structure on the outside of the body. It is an alternative to internal fixation, where the components used to provide st ...
system in 1951. He discovered that by carefully severing a
bone
A bone is a Stiffness, rigid Organ (biology), organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red blood cell, red and white blood cells, store minerals, provid ...
without severing the
periosteum
The periosteum is a membrane that covers the outer surface of all bones, except at the articular surfaces (i.e. the parts within a joint space) of long bones. Endosteum lines the inner surface of the medullary cavity of all long bones.
Structure ...
around it, one could separate two halves of a bone slightly and fix them in place, and the bone would grow to fill the gap.
He also discovered that bone regrows at a fairly uniform rate across people and circumstances. These experiments led to the design of what is known as an
Ilizarov apparatus
In medicine, the Ilizarov apparatus is a type of external fixation apparatus used in orthopedic surgery to lengthen or to reshape the damaged bones of an arm or a leg; used as a limb-sparing technique for treating complex fractures and open bone ...
, which holds a bone so severed in place, by virtue of a framework and pins through the bone, and separates halves of the bone by a tiny amount; by repeating this over time, at the rate of the bone's regrowth, it is possible to extend a bone by a desired amount. Originally, bicycle parts were used for the frame. The procedure was inspired by a
shaft bow
A shaft bow is an element of horse harness that is attached to the front of the shafts of a horse-drawn vehicle and joins them by arching high above the neck of the horse. Use of the shaft bow is widespread in the area east of the Baltic Sea (Russ ...
harness on a horse carriage.
For long time, Ilizarov faced skepticism, resistance, and political intrigues from the medical establishment in Moscow, which tried to defame him as a
quack
Quack, The Quack or Quacks may refer to:
People
* Quack Davis, American baseball player
* Hendrick Peter Godfried Quack (1834–1917), Dutch economist and historian
* Joachim Friedrich Quack (born 1966), German Egyptologist
* Johannes Quack (b ...
. The steadily increasing statistics of successful treatments of patients led to a growing fame of Ilizarov throughout the country, and he became known among patients as "the magician from Kurgan". In 1968, Ilizarov defended his doctoral thesis in
Perm
Perm or PERM may refer to:
Places
*Perm, Russia, a city in Russia
** Permsky District, the district
**Perm Krai, a federal subject of Russia since 2005
**Perm Oblast, a former federal subject of Russia 1938–2005
**Perm Governorate, an administra ...
and was awarded the title
Doctor of Sciences
Doctor of Sciences ( rus, доктор наук, p=ˈdoktər nɐˈuk, abbreviated д-р наук or д. н.; uk, доктор наук; bg, доктор на науките; be, доктар навук) is a higher doctoral degree in the Russi ...
bypassing the
Candidate of Sciences
Candidate of Sciences (russian: кандидат наук, translit=kandidat nauk) is the first of two doctoral level scientific degrees in Russia and the Commonwealth of Independent States. It is formally classified as UNESCO's ISCED level 8, "do ...
degree for which the thesis had originally been prepared.
A breakthrough came in 1968, when Ilizarov successfully operated on
Valeriy Brumel
Valeriy Nikolayevich Brumel (russian: Валерий Николаевич Брумель; 14 April 1942 – 26 January 2003)Great Russian Encyclopedia (2006), Moscow: Bol'shaya Rossiyskaya Enciklopediya Publisher, vol. 4, p. 243 was a Russian hi ...
, the 1964 Olympic champion and a long-time world record holder in the men's
high jump
The high jump is a track and field event in which competitors must jump unaided over a horizontal bar placed at measured heights without dislodging it. In its modern, most-practiced format, a bar is placed between two standards with a crash mat f ...
, who injured his right leg in a motorcycle accident. Before coming to Ilizarov, Brumel spent about three years for unsuccessful treatments in various clinics and underwent seven invasive and 25 non-invasive surgeries.
Ilizarov Center
In 1971, the Kurgan Research Institute for Experimental and Clinical Orthopaedics and Traumatology (KNIIEKOT) was established in
Kurgan
A kurgan is a type of tumulus constructed over a grave, often characterized by containing a single human body along with grave vessels, weapons and horses. Originally in use on the Pontic–Caspian steppe, kurgans spread into much of Central Asi ...
. In the center, the Ilizarov method of transosseous osteosynthesis is applied to lengthen or reshape
limb
Limb may refer to:
Science and technology
*Limb (anatomy), an appendage of a human or animal
*Limb, a large or main branch of a tree
*Limb, in astronomy, the curved edge of the apparent disk of a celestial body, e.g. lunar limb
*Limb, in botany, ...
bones. Ilizarov was the head of this center until 1991. With about 1,000 beds, 24 operating rooms, and 168 employed physicians, KNIIEKOT became the largest orthopedic clinic in the world.
[Peter Bizer. ''Kleiner Mann, ganz groß''. Der Stern, 27.10.1983 (in German).][Wolfgang Saxon (25 July 1992]
Dr. Gavril A. Ilizarov Dies at 71; Pioneer Bone Surgeon in Russia
''New York Times''
After his death, KNIIEKOT was renamed the Russian Ilizarov Scientific Center for Restorative Traumatology and Orthopaedics (RISC RTO). The staff includes ten professors, 34
Doctors of Sciences, and 193
Candidates of Sciences. The RISC RTO comprises an out-patient clinic where 250 patients can be consulted daily, a hospital with 800 beds, an experimental department, and animal surgery. Every year, over 9,000 people undergo treatment at the RISC RTO.
International recognition
Scattered reports about the successful treatment of Brumel by Ilizarov appeared in the Western press during the
Cold War
The Cold War is a term commonly used to refer to a period of geopolitical tension between the United States and the Soviet Union and their respective allies, the Western Bloc and the Eastern Bloc. The term '' cold war'' is used because the ...
era.
The first foreign medical visitor was Johannes Hellinger from the former
GDR, Medical Academy of Erfurt in 1970. He made a first publication in a Western medical journal about the Ilizarov Method.
In 1980,
Carlo Mauri
Carlo Mauri (25 March 1930 – 31 May 1982) was an Italian mountaineer and explorer.
Mauri was born in Lecco. Among his early climbs in the Alps two stand out: the first winter ascent of the ''via Comici'' route on the northern face of Cima Gran ...
, an Italian
mountaineer
Mountaineering or alpinism, is a set of outdoor activities that involves ascending tall mountains. Mountaineering-related activities include traditional outdoor climbing, skiing, and traversing via ferratas. Indoor climbing, sport climbing, an ...
,
explorer
Exploration refers to the historical practice of discovering remote lands. It is studied by geographers and historians.
Two major eras of exploration occurred in human history: one of convergence, and one of divergence. The first, covering most ...
, and photojournalist, on the urgings of his Russian colleague
Yuri Senkevich
Yuri Aleksandrovich Senkevich (russian: Юрий Александрович Сенкевич) (March 4, 1937 in Choibalsan, Mongolia – September 25, 2003 in Moscow, Russia) was a Soviet doctor, and scientist. He is a Candidate of Sciences ...
, travelled to Kurgan, in the
Soviet Union
The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen national ...
. He was to be treated by Ilizarov for a tibial fracture that healed incorrectly after a skiing accident ten years earlier. Italian doctors had long given up hope of any surgical improvement to the leg. Ilizarov distracted the stiff non-union in his tibia by 2 cm, healing the pseudarthrosis, corrected an equinus deformity by distraction and lengthened his leg. Mauri dubbed Ilizarov "the Michelangelo of Orthopaedics".
On his return to Italy, the healing of Mauri's leg amazed orthopaedic surgeons. Subsequent to this, Ilizarov was invited by Antonio Bianchi-Maiocchi and Roberto Cattaneo to be a guest speaker at the
AO Italy conference in 1981 in
Bellagio Bellagio may refer to:
* Bellagio, Lombardy, an Italian town
* Bellagio (resort), a luxury resort and casino in Las Vegas
* Bellagio (Hong Kong), a private housing building
* Bellagio declaration, an intellectual copyright resolution
* 79271 Bellag ...
. He gave three lectures at the conferences to more than 200 participants from Italy, France, Switzerland, Austria, and Germany. At the end of the lectures, Ilizarov earned a ten-minute standing ovation. This was the first time Ilizarov spoke outside of the
Iron Curtain
The Iron Curtain was the political boundary dividing Europe into two separate areas from the end of World War II in 1945 until the end of the Cold War in 1991. The term symbolizes the efforts by the Soviet Union (USSR) to block itself and its s ...
.
[Dror Paley]
Historical Vignettes on How the Ilizarov Method Came to the West
. Limb Lengthening.us
In 1982, the Association for the Study and Application of the Methods of Ilizarov (ASAMI) was formed in Italy.
In 1983, Medicalplastic, a company owned by Bianchi-Maiocchi, licensed the technique from the Soviet authorities, registered the ILIZAROV trademark, and started to produce and market the Ilizarov apparatus.
In the following years, the Ilizarov method has spread rapidly through most of Western Europe. ASAMI organised courses in Italy, Portugal, Switzerland, France, Spain, Greece, Brazil, and the United States. ASAMI groups were formed in France, Spain, Belgium, Portugal and Brazil.
In 1986–1987, the technique was brought to North America by Victor Frankel, president of
Hospital for Joint Diseases
NYU Langone Health is an academic medical center located in New York City, New York, United States. The health system consists of NYU Grossman School of Medicine and NYU Long Island School of Medicine, both part of New York University (NYU), and ...
,
Dror Paley,
Alfred D. Grant,
and Stuart Green who, in 1992, edited the first English translation of Ilizarov's book. Over 300 American orthopaedic surgeons attended an international symposium organised in 1987 in New York by the Hospital for Joint Diseases and the Smith & Nephew
Smith & Nephew plc, also known as Smith+Nephew, is a British multinational medical equipment manufacturing company headquartered in Watford, England. It is an international producer of advanced wound management products, arthroscopy products, ...
company to hear the lectures by Ilizarov. Smith & Nephew started the distribution of the Ilizarov external fixator in the USA and worldwide.
In 1989, an Ilizarov conference was organised by Dietmar Wolter in Hamburg
(male), (female) en, Hamburger(s),
Hamburgian(s)
, timezone1 = Central (CET)
, utc_offset1 = +1
, timezone1_DST = Central (CEST)
, utc_offset1_DST = +2
, postal ...
. In 1990, Ilizarov came to the second conference in Hamburg, where he co-founded the German Ilizarov Society (''Deutsche Ilisarow-Gesellschaft''). The hospital of the German Accident Prevention & Insurance Association (''Berufsgenossenschaftliches Unfallkrankenhaus'', BGUK) in Boberg, Hamburg-Lohbrügge
is a quarter in the Bergedorf borough of the Free and Hanseatic city of Hamburg in northern Germany. In 2020, the population was 40,745.
Geography
In 2006, according to the statistical office of Hamburg and Schleswig-Holstein, the Lohbrügge qua ...
, became a major center in Germany applying and promoting the Ilizarov technique. It also became compulsory for all senior physicians of the hospital to visit the Kurgan Center for learning the Ilizarov method.
Later life and death
The opposition by the Moscow medical establishment continued until the last years of Ilizarov's life. As late as 1991, just one year before his death, Ilizarov was elected a full member of the Russian Academy of Sciences
The Russian Academy of Sciences (RAS; russian: Росси́йская акаде́мия нау́к (РАН) ''Rossíyskaya akadémiya naúk'') consists of the national academy of Russia; a network of scientific research institutes from across t ...
.[Илизаров Гавриил Абрамович](_blank)
Russian Academy of Sciences
The Russian Academy of Sciences (RAS; russian: Росси́йская акаде́мия нау́к (РАН) ''Rossíyskaya akadémiya naúk'') consists of the national academy of Russia; a network of scientific research institutes from across t ...
(in Russian) Despite numerous awards and the worldwide recognition, he was not elected to the USSR Academy of Medical Sciences The USSR Academy of Medical Sciences (russian: Акаде́мия медици́нских нау́к СССР) was the highest scientific and medical organization founded in the Soviet Union founded in 1944.
Its successor is the Russian Academy of ...
.
Ilizarov died of heart failure in 1992, at the age of 71.
Family
Ilizarov was survived by his daughters Maria and Svetlana Ilizarov, a practicing physiatrist
Physical medicine and rehabilitation, also known as physiatry, is a branch of medicine that aims to enhance and restore functional ability and quality of life to people with physical impairments or disabilities. This can include conditions su ...
in New York, and son Alexander. His grandson Gavriil is also a physiatrist in training.
Awards and honours (selected)
Soviet and Russian
* Honoured Medical Doctor of RSFSR
The Russian Soviet Federative Socialist Republic, Russian SFSR or RSFSR ( rus, Российская Советская Федеративная Социалистическая Республика, Rossíyskaya Sovétskaya Federatívnaya Soci ...
(1965)
* Order of the Red Banner
The Order of the Red Banner (russian: Орден Красного Знамени, Orden Krasnogo Znameni) was the first Soviet military decoration. The Order was established on 16 September 1918, during the Russian Civil War by decree of th ...
(1966)
* Honorary citizen of Kurgan
A kurgan is a type of tumulus constructed over a grave, often characterized by containing a single human body along with grave vessels, weapons and horses. Originally in use on the Pontic–Caspian steppe, kurgans spread into much of Central Asi ...
(1971)
* Lenin Prize (1978)
* Hero of Socialist Labour
The Hero of Socialist Labour (russian: links=no, Герой Социалистического Труда, Geroy Sotsialisticheskogo Truda) was an honorific title in the Soviet Union and other Warsaw Pact countries from 1938 to 1991. It repre ...
(1981)
* Honoured Inventor of the USSR
The Honorary Title "Honoured Inventor of the USSR" (russian: Заслуженный изобретатель СССР) was a state award of the Soviet Union established on 28 December 1981 by Decree of the Presidium of the Supreme Soviet № 627 ...
(1985)
* Order of Lenin
The Order of Lenin (russian: Орден Ленина, Orden Lenina, ), named after the leader of the Russian October Revolution, was established by the Central Executive Committee on April 6, 1930. The order was the highest civilian decoration b ...
(3 times)
* Full member of the Russian Academy of Sciences
The Russian Academy of Sciences (RAS; russian: Росси́йская акаде́мия нау́к (РАН) ''Rossíyskaya akadémiya naúk'') consists of the national academy of Russia; a network of scientific research institutes from across t ...
(1991)
International
* Order of the Smile
The Order of the Smile (Polish: ''Order Uśmiechu'') is an international award given by children to adults distinguished in their love, care and aid for children.
History
The idea of the Order of the Smile was established in 1968 by the Polis ...
(1978)
* Commander of the Order of Merit of the Italian Republic
The Order of Merit of the Italian Republic ( it, Ordine al Merito della Repubblica Italiana) is the senior Italian order of merit. It was established in 1951 by the second President of the Italian Republic, Luigi Einaudi.
The highest-ranking ...
(1984)
* Order of Independence
Order of Independence or Independence Order ( vi, Huân chương Độc lập) is a Vietnamese decoration.
Criteria
The Vietnamese government states that the decoration "shall be conferred or posthumously conferred on individuals who have re ...
(Jordan, 1985)
* Order of the Polar Star
The Royal Order of the Polar Star (Swedish: ''Kungliga Nordstjärneorden'') is a Swedish order of chivalry created by King Frederick I on 23 February 1748, together with the Order of the Sword and the Order of the Seraphim.
The Order of the ...
(Mongolia, 1985)
* Order of the Yugoslav Flag with Golden Wreath (1987)
* Robert Danis Prize of the International Society of Surgery (1987)
Awardees of the Robert Danis Prize
''
* Honorary citizen of Milan
Milan ( , , Lombard: ; it, Milano ) is a city in northern Italy, capital of Lombardy, and the second-most populous city proper in Italy after Rome. The city proper has a population of about 1.4 million, while its metropolitan city h ...
, Lecco
Lecco (, , ; lmo, label=Lecchese, Lècch ) is a city of 48,131 inhabitants in Lombardy, northern Italy, north of Milan. It lies at the end of the south-eastern branch of Lake Como (the branch is named ''Branch of Lecco'' / ''Ramo di Lecco''). ...
, Rufina
Rufina is a ''comune'' (municipality) in the Metropolitan City of Florence in the Italian region Tuscany, located about east of Florence.
Rufina borders the following municipalities: Dicomano, Londa, Montemignaio, Pelago, Pontassieve, Pratovecc ...
, Florence
Florence ( ; it, Firenze ) is a city in Central Italy and the capital city of the Tuscany region. It is the most populated city in Tuscany, with 383,083 inhabitants in 2016, and over 1,520,000 in its metropolitan area.Bilancio demografico an ...
, and Nancy
* A minor planet 3750 Ilizarov was named after him in 1982
References
External links
Ilizarov.ru
Ilizarov Center, Russia, Kurgan
Ilizarov.com
English-language portal
{{DEFAULTSORT:Ilizarov, Gavril
1921 births
1992 deaths
People from Qusar
Corresponding Members of the USSR Academy of Sciences
Full Members of the Russian Academy of Sciences
Members of the Supreme Soviet of the Russian Soviet Federative Socialist Republic, 1980–1985
Members of the Supreme Soviet of the Russian Soviet Federative Socialist Republic, 1985–1990
Commanders of the Order of Merit of the Italian Republic
Commanders of the Order of Merit of the Republic of Poland
Heroes of Socialist Labour
Lenin Prize winners
Recipients of the Order of Lenin
Recipients of the Order of the Red Banner of Labour
Traumatologists
Jewish physicians
Mountain Jews
Russian orthopaedic surgeons
Soviet Jews
Soviet orthopedic surgeons
Burials in Kurgan, Kurgan Oblast