Knee Dislocation: Comprehensive Guide in Singapore 2024 - Singapore Sports And Orthopaedic Clinic

Q: How serious is a dislocated knee?

Knee dislocations represent a highly distressing injury, posing a significant risk to limb integrity. Due to the potential for neurovascular harm accompanying such trauma, knee dislocations are categorized as among the most severe knee injuries, even though they are quite rare.

Q: Can a dislocated knee cause permanent damage?

This injury may lead to enduring effects, including patella instability, persistent pain, recurrent dislocation, and the development of patellofemoral osteoarthritis.

Q: What happens if you don't fix a dislocated knee?

A knee dislocation can result in harm to nerves or blood vessels, potentially leading to alterations in skin color and temperature. This could disrupt blood circulation and sensation below the knee. In severe instances, the failure to address these complications promptly could necessitate limb amputation.

Basics
Epidemiology
Diagnosis
Treatment
Follow-up
Prognosis
Miscellaneous
FAQ

Basics

Description

Dislocation of the knee is an orthopaedic emergency.
The most common causes are motor vehicle accidents, followed by sports and falls from heights.
Classification:
- Anterior
- Posterior
- Medial
- Lateral
- Rotary: Subclassified as anteromedial, anterolateral, posteromedial, posterolateral

General Prevention

Seat belts and airbags are the best methods of prevention.

Epidemiology

Incidence

Rare

Associated Conditions

Neurovascular injury, particularly to the popliteal artery or peroneal nerve
Fractures of the tibia or femur
Rupture of the collateral and/or cruciate ligaments

Diagnosis

Signs and Symptoms

History

Classically, patients with knee dislocations present with obvious deformity, swelling, pain, and inability to move the knee.
Many knee dislocations are reduced before examination by a physician; thus, deformity may not be present.
It is critical to assess the neurovascular status of all patients with possible knee dislocations because:
- Injury to the popliteal artery occurs in 32-45% of cases.
- Nerve injury (most commonly the peroneal nerve) occurs in 16-40% of all knee dislocations.
Urgent vascular evaluation is required for absent pulses; ecchymosis in the popliteal fossa; a cold, cyanotic extremity; or loss of sensorimotor function.

Physical Exam

Inspect the extremity for obvious deformity, swelling, and ecchymosis.
Perform a thorough neurovascular examination.
- Palpate pulses or assess them by Doppler, note warmth of skin, and examine sensory and motor function.
The presence of pulses does not rule out vascular injury because an intimal flap tear of the vessel may be present.
Any sign of vascular injury necessitates an emergent vascular surgery consultation.
Examination for laxity of the knee should be performed systematically for injury to any of the 4 knee ligaments (ACL, OSD, MCL, or LCL).
Laxity of 2 or more knee ligaments leads to a presumptive diagnosis of knee dislocation.
Patients should be examined carefully at regular intervals to exclude the possibility of compartment syndrome.
- The most reliable signs for compartment syndrome are intractable, unrelenting pain out of proportion to the injury and pain with passive stretch of the ankle and toes.

Tests

Imaging

Radiography:
- AP and lateral views of the knee should be obtained, but doing so should not delay reduction of an obvious dislocation.
MRI:
- May be useful in assessing soft-tissue and ligamentous injury, but it should not be performed acutely.
- Also allows visualization of the vascular system.

Diagnostic Procedures/Surgery

Any patient with a vascular injury should undergo angiography or MRI.

Differential Diagnosis

Dislocation of the patella
Neurovascular injury unrelated to dislocation
Fracture of the tibia or femur

Treatment for Knee Dislocation in Singapore

General Measures

Many knee dislocations are the result of motor vehicle crashes; therefore, all such patients should be assessed by a trauma protocol.
- Initial assessment should include evaluation of airway, breathing, circulation, and vital signs.
Immediate reduction is recommended.
- Anterior dislocations are reduced with longitudinal traction and the lifting of the femur anteriorly.
- Posterior dislocations are reduced with longitudinal traction and the lifting upward of the proximal tibia while extending the knee.
- Medial and lateral dislocations are reduced with longitudinal traction and the appropriate medial or lateral pressure on the tibia and femur.
The neurovascular status should be assessed before and after reduction.
Orthopaedic and vascular surgeons should be notified.
The knee should be immobilized in a splint or spanning external fixator, with careful attention to the neurovascular status and the development of compartment syndrome.
Nonoperative treatment:
- Indicated for patients who are sedentary or elderly or who have substantial comorbidities preventing surgical repair.
- A splint should be followed by 6-8 weeks of protected immobilization.

Activity

Nonoperatively treated patients:
- 6-8 weeks of protected immobilization
- May begin quadriceps setting exercises in the splint, followed by active leg-lifting exercises after the immobilizer is removed
Operatively treated patients:
- Activity is determined by which structures were injured, repaired, and reconstructed.
- After 6 weeks, patients may begin active ROM exercises.
Average return to previous activity for both treatments:
- Sports, 9-12 months
- Sedentary jobs, 2 months
- Heavy labor, 6-9 months

Special Therapy

Physical Therapy

ROM and strengthening exercises should be started after immobilization.
Quadriceps setting exercises can begin in the splint/fixator.

Medication

First Line

Narcotics

Surgery

Emergent surgery is required for patients with vascular injury; saphenous vein grafting often is required.
Fasciotomies may be required for patients with prolonged ischemic time or with compartment syndrome.
Open dislocation requires immediate surgical intervention.
Definitive surgical repair usually is performed 10-14 days after the injury, to allow swelling to diminish and to facilitate arthroscopic procedures.
Methods of repair and reconstruction depend on the extent and nature of the injuries.

Follow-up

Disposition

Patients should be followed at 4-6-week intervals until they achieve maximum recovery.

Issues for Referral

An orthopaedic surgeon should be consulted emergently.
Any vascular injuries require immediate consultation with a vascular surgeon.

Prognosis

Prognosis depends on the associated limb injuries and the interventions for those injuries.
Viability of the limb in the presence of vascular compromise is directly related to the time between injury and revascularization.
The most common residual effects are arthrofibrosis (knee stiffness) and postoperative arthritis.

Complications

Loss of limb:
- Usually secondary to prolonged ischemia
- The amputation rate is 86% when ischemia lasts >8 hours.
Arthrofibrosis (stiff knee):
- In nonoperative treatment, residual stiffness provides stability for injured ligaments.
- Operative treatment may increase the incidence of arthrofibrosis unless reconstruction is strong enough to allow early ROM.
Neurologic deficit:
- Nerve injury, most often the peroneal nerve, is a common sequela of knee dislocation.
- Recovery may take months to years, and prognosis varies.
Knee instability:
- Secondary to injury to the ligamentous structures
- Redislocation is rare.
Posttraumatic arthritis:
- Secondary to cartilage injury during the trauma
- Can lead to long-term disability

Miscellaneous

Codes

ICD9-CM

836.5 Closed knee dislocation
836.6 Open knee dislocation

Patient Teaching

Activity

Emphasize ROM and, later, strengthening exercises.

Knee Dislocation FAQ

Do all patients with a knee dislocation require an arterial study to document the status of the popliteal artery?

No. Although as many as 50% of knee dislocations from high-energy motor vehicle accidents have a popliteal artery injury, <10% of athletic knee dislocations have an arterial injury. Patients with diminished distal pulses before surgical evaluation require urgent vascular consultation.

How serious is a dislocated knee?