Corrective Osteotomy

The corrective osteotomy (also called conversion osteotomy) is an orthopedic-surgical procedure in which a bone is severed ( osteotomized ) in order to restore the normal bone, joint or limb anatomy or to regain it in the case of incorrectly healed bone fractures , or to relieve joint parts (As with a valgus adjustment near the knee joint in the case of osteoarthritis of the inner joint part). In principle, osteotomies are possible on all bones; the majority of them are performed on long tubular bones. The metaphysis is usually chosen there because, in contrast to the shaft, it has a faster build-up. But there are also osteotomies on other bones, such as the pelvis or the hindfoot area.

The first osteotomy was performed by the American IR Barton before anesthesia was introduced in 1826. But only after the introduction of anesthesia and asepsis did the osteotomy flourish in the second half of the nineteenth century, especially through Bernhard Langenbeck and Theodor Billroth , who also introduced the chisel for osteotomy.

The corticotomy or compactotomy refers to the exclusive severing of the bony cortex while protecting the medullary vessels and the periosteum , which is carried out before the use of a callus distraction according to Ilizarov.

execution

The osteotomy can be done with oscillating saws, a Gigli saw (especially on the pelvis), with sharp chisels or (traditionally) with special osteotomes . Particularly in the case of osteotomies close to the hip joint, K-wires are often used before the osteotomy to mark the position and determine the subsequent correction angle. The osteotomy gap can then be widened with a distractor to effect the desired correction. This is followed by an osteosynthesis in order to secure the achieved correction until the bone heals. Often, plate osteosynthesis is used for this, or special angle plates are used on the hip and knee joint. In children, K-wires are often used, or in foot surgery , special screws and Blount clamps that can be completely submerged in the bone are used . If gaps arise as a result of the correction in the area of ​​the osteotomy, a bone chip from the iliac crest or an artificial bone replacement is often inserted. By using a tensioning bone graft or a complex incision (e.g. scarf osteotomy on the first metatarsal bone in hallux valgus ), the osteotomy can be intrinsically stable, so that theoretically no osteosynthesis is necessary.

Correction levels

With an osteotomy, bones can be corrected in all directions, depending on the position and shape of the osteotomy gap:

• Change in length: shortening and lengthening osteotomies
• Rotation: internal or external (derotating) osteotomy
• Displacement: translational osteotomy
• Tilting in the frontal plane: valgus or varicose osteotomy
• Tilting in the sagittal plane: flexing or extending osteotomy

If corrections are required in several directions, this usually requires more complex osteotomies, with appropriate planning in advance (e.g. using X-rays of the entire extremity or computer tomography ). For example, in the case of hip dysplasia , a varicating, flexing, derotating and shortening intertrochanteric corrective osteotomy is performed, or , conversely , in the case of a chronic femoral head loosening with considerable tilting of the femoral head, a valgus extending rotating intertrochanteric corrective osteotomy can be performed.

Classification of osteotomies

There are four basic types, depending on the shape of the osteotomy. In addition to the rarer step and arch osteotomies, the opening wedge and closing wedge osteotomies are the most frequently used. With these last two forms of osteotomy, a transverse (perpendicular to the axis of the bone shaft) can be distinguished from an oblique osteotomy, so that the classification of osteotomies for the correction of post-traumatic misalignments according to Marti and van Heerwaarden comprises six groups, with a seventh group of special forms:

• Closing wedge with a transverse osteotomy gap : there is a shortening that corresponds to half the width of the base of the bone wedge to be removed. Rotation corrections are easy to make. Also used among other things subcapital on the first metatarsal to correct a hallux rigidus .
• Closing wedge with angled osteotomy gap : By moving the bone fragments along the osteotomy, an additional correction in a further level and an extension or shortening is possible, as is a rotation correction. A set screw can be inserted perpendicular to the osteotomy.
• Opening wedge with transverse osteotomy gap : possibility of correction in all three planes. Bone lengthening possible. Most intertrochanteric osteotomies for the correction of acquired and congenital hip misalignments (including hip dysplasia , Perthes disease ) are included.
• Opening wedge with angled osteotomy gap : correction possible in all three planes, extension possible, adjusting screw can be used perpendicular to the osteotomy gap.
• Step and distraction osteotomy : predominantly when there is significant lateral dislocation and angulation. Allows correction in all three planes and bone lengthening or shortening. Often applied intertrochanterically on the thigh bone .
• Arched osteotomy : Allows the correction of angulations, high intrinsic stability. Often used for elbow misalignment after supracondylar humerus fracture and for Blount's disease .
• Special forms : In addition to all pelvic osteotomies , this also includes angled osteotomies such as the scarf osteotomy or the chevron osteotomy on the first metatarsal bone for the correction of hallux valgus

Osteoclasia

Up until the twentieth century, osteoclasias were used to treat gross misalignments of long tubular bones as a result of incorrectly healed fractures or rachitic malpositions. This involves breaking the bones by manual force or by means of apparatus ( osteoclasts ) in which the extremity is clamped and broken through targeted bending. This was followed by a plaster immobilization in the corrected position until the fracture had healed. The counter-breaking of incomplete forearm fractures can also be referred to as osteoclasia, although the term is uncommon today.

Maxillofacial surgery

In osteotomies to change the occlusion in case of mandibular facial deformities or mandibular growth disorders (orthognathic surgery), the lower jaw bone is divided along the external oblique line in the area of ​​the 2nd molar and lingually above the mandibular foramen. The lower jaw nerve (N. alveolaris inferior) running there is spared and the front, drawer-shaped lower jaw fragment is moved forwards or backwards and fixed in the new position with the help of osteosynthesis plates. This surgical method practiced today is the Obwegeser operation modified from Dal-Pont.

Computerized osteotomy

In the case of complex osteotomies, the planning and the intraoperative implementation can be carried out with the aid of the computer. Corrective osteotomies are particularly suitable for the concept of computer-assisted osteotomy, as these interventions are based on quantitative preliminary planning.

Computer-aided osteotomy of the radius: The maloccled bone (red) is shown in comparison to the healthy opposite side, which serves as a template.

Computer-aided preoperative planning

From the underlying three-dimensional (3D) image data a is the 3D model of the prepared bone to be corrected. On the extremities, the healthy opposite side is often included as a template in order to automatically calculate the optimal correction using registration algorithms so that the differences to the template are minimized.

Based on the patient-specific 3D models, the procedure can be analyzed on the computer and carried out virtually, and the displacement and rotation of the bone parts required for correction can be expressed exactly in millimeters and degrees.

Computer-aided osteotomy of the radius: virtual implementation of the procedure. The radius is osteotomized and the part to be corrected (blue) is brought into the anatomically correct position using a reduction template.

Computerized implementation

In order to implement the preoperative planning precisely in the operation, an indirect or direct surgical navigation system is used ( computer-aided positioning ). In corrective osteotomies, patient-specific positioning, cutting or drilling templates are often used, which must be produced in advance using rapid prototyping and can then be used in the preoperative planning together with a true-to-original printout of the bone to be corrected.

In the case of complex osteotomies, rapid prototyping can be used to create a faithful model of the bone so that the procedure can be simulated in a simplified manner in advance.

Depending on the method used, the operating time is increased through the use of computer technology, and more time is usually required for preoperative planning. In addition, there is a need for additional CT images using thin-section technology, with the resulting increased radiation exposure.

An advantage compared to the conventional procedure with fluoroscopic control could only be shown with complex osteotomies in some areas, such as extra- and intra-articular osteotomies of the forearm.

Web links

• Detailed case studies of computer-aided corrective osteotomies with preoperative planning and intraoperative implementation. Balgrist University Hospital Zurich, 2012

Individual evidence

1. ^ ^{A b} R. K. Marti, RJ van Heerwaarden: Osteotomies for posttraumatic deformities . AO Foundation Publishing. Thieme-Verlag Stuttgart 2008 ( ISBN 978-3-13148671-4 )
2. ↑ AM Debrunner: Orthopedics - Orthopedic surgery . Verlag Hans Huber, Bern 1994 (3rd edition; ISBN 3-456-82683-4 )
3. ↑ ^{a b c} F. Hefti: Pediatric orthopedics in practice . Springer-Verlag, Berlin 1997, ISBN 3-540-61480-X
4. ↑ P. Haglund: Principles of Orthopedics . Gustav-Fischer-Verlag Jena 1923
5. ^ B Spiessl: Osteosynthesis in sagittal osteotomy using the Obwegeser-Dal Pont method . In: Fortschr Kiefer face shield. , 1974, 18, pp. 145-148, PMID 4534071 .
6. ↑ ^{a b} P. Fürnstahl: Computer-Assisted Planning for Orthopedic Surgery . Hartung-Gorre Verlag, Konstanz, 2010, ISBN 978-3-86628-352-7 .
7. ↑ Examples of corrective osteotomies performed with templates . Website of the CARD team at the Balgrist University Hospital, Zurich. Retrieved March 29, 2013.
8. ↑ ^{a b} A. Schweizer et al .: Complex Radius Shaft Malunion: Osteotomy with Computer-Assisted Planning . Hand. 2010 June; 5 (2): 171-178.
9. ↑ Miyake J et al .: Computer-assisted corrective osteotomy for malunited diaphyseal forearm fractures . In: J Bone Joint Surg Am . 2012 Oct; 94 (20).
10. ^ Oka K. et al .: Corrective osteotomy for malunited intra-articular fracture of the distal radius using a custom-made surgical guide based on three-dimensional computer simulation: case report . J Hand Surg Am. 2008 Jul-Aug; 33 (6): 835-40.

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