Etiology — what causes it

First-time patellar dislocation usually involves disruption of the medial patellofemoral ligament (MPFL), which provides about 60% of the medial restraint to lateral translation. Predisposing factors include trochlear dysplasia, patella alta, increased TT-TG distance, and generalized hypermobility.

Epidemiology — who gets it

Incidence is roughly 5–7 per 100,000, with peak in adolescent and young adult athletes. Recurrence after first-time dislocation is 30–50%, much higher in those under 18.

Clinical signs

Positive patellar apprehension test, increased patellar mobility, J-sign during active extension, quad atrophy, and sometimes effusion. Imaging assesses TT-TG, trochlear morphology, and patellar height.

Symptoms

History of patellar dislocation or recurrent subluxation. Anterior knee pain, sense of instability with pivoting or kneeling, sometimes effusion after episodes. Apprehension with knee in flexion and lateral force.

Best evidence for chiropractic treatment

First-time dislocation without major osteochondral fragments is typically managed conservatively with progressive quad strengthening, hip control, and neuromuscular work (Magnussen et al., Sports Health). Recurrent dislocators and those with structural risk factors often benefit from MPFL reconstruction. Post-surgical rehab follows criteria-based progression similar to ACL rehab — quad symmetry, hop tests, sport-specific demands.

Subtypes

  • First-time lateral dislocation. Conservative care first in most cases.
  • Recurrent patellar instability. Surgical consultation often appropriate; MPFL reconstruction is common.
  • Post-MPFL reconstruction. Phased rehab to criteria-based RTS.

When to seek emergency care

Some symptoms need urgent medical attention — not a chiropractic visit. Call 911 or go to the nearest emergency department for: progressive limb weakness, loss of bowel or bladder control, saddle anesthesia (numbness in the groin/inner thighs), severe unrelenting pain unrelieved by position, signs of fracture after significant trauma, chest pain, stroke-like symptoms (face drooping, arm weakness, speech changes), or any rapidly worsening or unusual symptom.

Bottom line

Most first-time dislocators recover with conservative care. Recurrent instability often needs surgical reconstruction, followed by criteria-based rehab.