Joint incongruity; articular surfaces of a joint do not fit together properly

Описание: Joint incongruity refers to a condition where the articular surfaces of a joint do not align properly, leading to abnormal contact between bones. This misalignment disrupts the smooth gliding motion of the joint and can cause pain, instability, and progressive degeneration.

🔎 Key Points About Joint Incongruity
Definition
Loss of normal congruence between joint surfaces.

Can be partial (subtle mismatch) or complete (gross malalignment).

Causes
Congenital: Developmental dysplasia of the hip, clubfoot.

Traumatic: Fractures involving the joint surface (intra‑articular fractures), dislocations.

Degenerative: Osteoarthritis, rheumatoid arthritis.

Post‑surgical or post‑traumatic malunion: Improper healing of fractures.

Radiographic Features
Step-off deformity: Irregularity in the articular surface seen on X‑ray/CT.

Loss of parallelism: Joint surfaces no longer match smoothly.

Uneven joint space: Narrowing or widening in certain areas.

Secondary changes: Osteophytes, sclerosis, cyst formation in chronic cases.

Clinical Consequences
Pain and stiffness.

Abnormal joint mechanics → altered load distribution.

Accelerated wear → early osteoarthritis.

Instability and reduced range of motion.

Examples
Hip dysplasia: Acetabulum and femoral head don’t fit properly.

Knee incongruity: Tibial plateau fracture with step deformity.

Elbow incongruity: Malunited radial head fracture.

Management
Early correction: Surgical fixation of intra‑articular fractures to restore congruity.

Reconstructive surgery: Osteotomy, arthroplasty if incongruity is severe.

Conservative care: Pain management, physiotherapy in mild cases

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