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False joint

False joint (pseudoarthrosis) is a persistent bone defect that causes abnormal mobility throughout the diaphysis. There are congenital and acquired false joints . The first are rare and are localized mainly on the legs. Acquired are a complication of bone fracture. Often they are formed after open and gunshot fractures (see).

The formation of a false joint is based on violations of fracture healing processes due to common and local causes. Common causes include depletion of the body, dysfunction of the endocrine glands, vitamin deficiencies, neurotrophic disorders, etc., local - fracture infection, significant defects of soft tissue and bone, impaired blood supply and innervation, interposition (penetration) of soft tissue between fragments, incorrect method treatment with unsatisfactory reposition and fixation of fragments.

Clinically, the pseudarthrosis is manifested by painless mobility at the site of the former fracture, the lack of adhesion of fragments after a considerable time after injury, impaired function of the limb (Fig.). Radiologically visible gap between the fragments and the closure of the bone-marrow channels of the bone substance - the endplate. Typical articular surfaces covered with cartilage are formed in a false joint of a large age; the surrounding fibrotic tissues form a joint capsule.

false joint shoulder
Shoulder joint
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Treatment of a false joint is only operational. The method of operation depends on the location, type and duration of the existence of a false joint. Fibrous-altered soft tissues are removed between the fragments, an economical resection of the ends of the fragments, the opening of the bone-cerebral canal and strong fixation of the fragments using osteosynthesis. Bone autografts or homografts are additionally used to stimulate the processes of osteogenesis (see Bone grafting). Good results in the treatment of a false joint are observed with the use of compression osteosynthesis devices (see).

False joint [synonym for pseudarthrosis (pseudoarthrosis)] is a persistent abnormal mobility of the bone throughout the diaphysis due to a breach of its continuity.

A false joint with a significant bone defect is called “dangling pseudoarthrosis.” A false joint can also form on short bones (patella, navicular bone, etc.). False joints are congenital and acquired.

Congenital false joints are rare, mostly localized on the border of the middle and distal third of the leg, resulting from fetal pathology. Acquired false joints can be formed due to the lack of consolidation after a closed, open or gunshot fracture or after osteotomy operations, osteosynthesis, bloody reposition of fragments as a result of weak reparative processes or significant loss of bone substance. Pathological fractures that occur with minor injuries can also lead to the formation of a false joint due to the reduced ability of the bone tissue to regenerate (with rickets, osteomalacia, scurvy, etc.).

The basis of the pathogenesis of the false joint is general and local causes that hinder consolidation, the latter playing a much larger role. Common causes include dysfunction of the endocrine glands, pregnancy, vitamin deficiency, chronic infectious diseases, wound exhaustion. Local causes may be due to improper treatment (use of too large loads during stretching, imperfect reposition of bone fragments with the lack of sufficient contact, extensive resection of the diaphysis or removal of large bone fragments with open fractured fractures, early use of passive and active gymnastics); anatomical and physiological features of the fracture area - insufficient blood supply to the damaged bone (scaphoid, femoral neck, patella); trauma (multiple fractures, interposition of soft tissues, loss of bone substance, crush of soft tissues surrounding fragments, severe bone wound infection with the development of osteomyelitis).

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Pathological anatomy. At a false joint with close contact of bone fragments, their ends are connected by fibrous tissue. With the continued existence of a false joint, one of the fragments takes the form of an articular cavity, the other head, both are covered with hyaline or fibrous cartilage, and the surrounding fibrous tissue forms a kind of articular bag with a cavity and the like of synovial fluid. In case of a bone defect, the ends of the fragments are pointed, the bone-cerebral canals are overgrown, and the gap between the fragments is made with scar tissue.

The clinical picture (signs and symptoms). With a false joint, there is a more or less severe deformity of the limb, painless mobility of the fragments, atrophy of the surrounding muscles and impaired function of the limb (Fig. 1, 2 and 2). A false joint with a bone defect (dysfunctional pseudarthrosis) is characterized by a complete lack of limb function and looseness throughout the diaphysis of the bone.

Fig. 1. False joint: 1 - left shoulder; 2 - right shin.
Fig. 2. False joints: 1 - tibial bone with a defect of the fibula; 2 - the left femur with a defect in the bone, the end plate is visible; 3 - tibia (with a defect in the bone), the ends of the fragments are pointed, with significant sclerotic changes, in the soft tissues - metal fragments.

The picture of delayed consolidation is characterized by a small swing of fragments, which usually causes pain. Radiographically visible small gap between the fragments and cleft bone marrow channels. If the patient is not operated on time, delayed consolidation develops in the false joint.

The treatment of the false joint aims to restore strong contact between the fragments for normal limb function. As a rule, it is operative (see Osteosynthesis, Bone grafting). The method of extrafocal compression osteosynthesis using the apparatus of O. Gudushauri ensures complete contact of the fragments. It is applicable in cases of delayed consolidation and in false joints complicated by osteomyelitis.

Radiodiagnosis (Fig. 2). Research methods: conventional radiography in at least two mutually perpendicular projections, tomography and functional X-ray examination.

The following radiographic symptoms are characteristic of the false joint. 1. The strength of the band of enlightenment, dividing both the adjacent ends of the fragments, and periosteal osteophytes; Anatomical substrate of this band of enlightenment is X-ray transparent collagen tissue or fibrous cartilage (A. V. Rusakov). The shape of the strip, as well as the angle between the fragments change during functional examination.
2. The appearance of a distinct, gradually thickening and thickening cortical layer on the adjacent surfaces of the ends of the fragments (it arises from the cell-fibrous tissue produced by the endosteum). The increasing smoothness and sharpness of the previously uneven outlines of the ends of the fragments and the closure of the bone-cerebral canals (at the turn of the diaphysis) is a sign of a finally formed false joint. In the bones of this limb, especially more peripheral than the false joint, progressive porosity is noted.

With the continued existence of a false joint, and especially with poor immobilization, the contiguous ends of the fragments are shortened, completely smoothed and modeled like articular ends: one in the form of a head, the other - a depression. In the future, such an articulating false joint may be complicated by typical deformative-arthrotic changes up to sclerosis and growth of the edges of the articulated surfaces. The false joint should be differentiated with a long-flowing osteoid phase of consolidation (especially in flat and spongy bones) with a late fusion, and especially with a zone of bone remodeling and idiopathic post-traumatic osteolysis.