Knee Soft Tissue Injury (ACL, LCL, MCL, PCL) Management in the ED Treatment & Management

Updated: Aug 18, 2021
  • Author: David B Levy, DO, FAAEM; Chief Editor: Trevor John Mills, MD, MPH  more...
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Prehospital Care

Basic responsibilities in the prehospital setting, if knee trauma is the primary injury, include stabilizing the lower extremity and monitoring the neurovascular status of the limb.

The deformed knee should be realigned only if associated neurovascular structures are compromised. Always recheck and document pulses after splinting or manipulation of the limb. If initial efforts meet with resistance, prehospital personnel should not force realignment.

Cover open wounds with saline-soaked sterile gauze.

Frequently, the joint reduces spontaneously or is reduced at the scene by trained emergency medical services (EMS) personnel; in such cases, the ED physician must obtain information about the time and mechanism of injury and the original position of the limb.


Emergency Department Care

Adhere to the conventional dictums of emergency and trauma care by first corroborating the absence of life-threatening (primary survey) or limb-threatening (secondary survey) injuries before focusing on soft tissue damage sustained by the knee. A cardinal error occurs when earliest attention is diverted to an obvious extremity injury, such as a knee dislocation, while neglecting possibly lethal trauma.

Always determine the mechanism of injury and verify hemodynamic stability.

Assess vascular perfusion and control any bleeding. Hard signs of vascular injury include absent or diminished pulses, active hemorrhage, and expanding or pulsatile hematoma. Signs of distal ischemia include pain out of proportion to the injury, pallor, paralysis, and paresthesias. For knee dislocations or grossly malaligned fractures with potential vascular compromise, attempt immediate reduction or realignment of the knee if an orthopedic specialist is not immediately available. Popliteal artery injuries must be repaired within 6-8 hours to avoid amputation because of limb ischemia.

Splint all obvious fractures and unstable knee injuries, stabilizing the femur above and the tibia below.

Damage to essential nerves and vessels may be subtle on presentation.

Observe for signs and symptoms of compartment syndrome. Measurement of compartment pressures is often needed to exclude the possibility of compartment syndrome.

Remove any constricting clothes and bandages.

Make sure patients ingest nothing by mouth (NPO) until the need for emergency or urgent surgery is ascertained.

General treatment

General treatment principles include the following:

  • Aside from the particular injury, treatment plans depend on the patient's age and activity level and the presence of additional injuries.
  • Obtain orthopedic consultation when appropriate.
  • Initial nonpharmaceutical treatment includes rest, ice, compression, and elevation (RICE).
  • For the first 1-3 days, use therapeutic measures that minimize incipient damage and reduce pain and inflammation.
  • Consider splinting the injured knee to provide support and to prevent further injury.
  • Serviceable devices include commercially available immobilizers and handcrafted compressive dressings, such as the Robert Jones dressing, which incorporates coaptation plaster.
  • Detrimental effects of immobilization include joint stiffness, degenerative changes in articular cartilage, muscle atrophy and weakness, and decreased vascularity.

Specific-injury treatment

Treatements for specific injuries include the following:

  • For first-degree sprains, provide symptomatic treatment, essentially the RICE regimen. Normal function usually returns quickly.
  • Second-degree sprains require protection by using a cast, cast brace, or a restrictive-movement brace. Arrange for timely follow-up care.
  • Treatment of third-degree sprains depends on the severity and type of instability; some third-degree sprains of ligaments necessitate surgical repair. Factoring into the deliberation for surgery is the patient's age, relative health, associated injuries, activity demands, and individual desires.
  • Treatment for anterior cruciate ligament (ACL) injuries is individualized. Various conditions influence decisions on the optimum management of ACL tears, such as the presence or absence of comorbid pathology, age of the patient, baseline activity level, degree of instability, and associated ligamentous injuries miring the knee.
  • Presence of a meniscal tear does not automatically lead to surgical intervention. If the knee is not locked or unstable, conventional treatment (ie, RICE therapy) ordinarily suffices; however, the meniscus cartilage of the knee generally supports a precarious blood supply, and tears are prone to inadequate mending. Therefore, timely follow-up care is critical.

Emergency consultation with an orthopedic specialist is required for immediate reduction and evaluation of vascular integrity after a knee dislocation. If expedient orthopedic consultation is not obtainable and if signs of vascular compromise are present, the ED physician should undertake maneuvers to restore both integrity of the joint and perfusion. Angiography is imperative.

Knee dislocation

Reduction of knee dislocation includes the following:

  • Most knee dislocations reduce spontaneously before the patient's arrival in the ED. However, when examination findings suggest neurovascular compromise, an attempt to restore circulation with traction and/or reduction and emergency orthopedic consultation are needed.
  • Classify dislocations with respect to the relationship of the tibia on the femur.
  • Anterior dislocations occur most commonly.
  • In the ideal case, perform reductions in the operating room under general anesthesia. However, if circumstances preclude this scenario, an attempt in the ED is warranted.
  • Barring contraindications, administer conscious sedation.
  • With an assistant providing stabilization and countertraction of the thigh, a second person applies longitudinal traction to the leg. This maneuver usually suffices for reduction.
  • Reduction of an anterior knee dislocation may be aided by trying to transpose the femur anteriorly.
  • Avoid affixing pressure over the popliteal space, as it may exacerbate arterial damage.
  • For posterior dislocations (where the tibia lies posterior to the femur), attempt to reinstate the tibia anteriorly by gently lifting the tibia forward.
  • After relocation of the knee, confirm neurovascular status and immobilize the knee in 15° of flexion.
  • Order postreduction images and consultation with the orthopedic surgeon, and obtain an emergency arteriogram.

Patellar dislocation

Reduction of patellar dislocation includes the following:

  • Patellar dislocations typically occur in predisposed individuals and tend to recur.
  • Patellar dislocations are identified with respect to the patella's position on the knee joint, with lateral dislocations being most common.
  • If the joint has not already reduced spontaneously, verify the dislocation radiographically.
  • After administering necessary analgesia, place the hip in a mild amount of flexion, and gently press anteriorly and medially on the patella while extending the knee joint.
  • Postreduction films should include a sunrise view, as osteochondral fractures may result.
  • Other types of patellar dislocations tend to be resistant to closed reduction.
  • Aspiration of a Baker cyst may render temporizing relief. This procedure is best performed electively by a qualified physician.

Consequential soft tissue damage of the knee with concurrent serious disorder, such as vascular compromise, threatening compartment syndrome, or multiple trauma, warrants admission to the appropriate surgical or orthopedic service for monitoring and potential surgical intervention.

Injuries requiring timely surgery, such as knee dislocation, complete quadriceps tendon rupture, open knee joint injuries, and total patellar tendon rupture, may necessitate admission to the general orthopedic service.

Injection therapy

Ensure that the joint is not infected.

Pain secondary to aseptic inflammation of the prepatellar, suprapatellar, and pes anserine bursae may be relieved by instilling 2-4 mL of lidocaine mixed with 15-20 mg of a prednisolone suspension into the affected bursae.

Data have suggested that an intra-articular installation of morphine 1-5 mg confirms a local analgesic effect and possibly prolongs pain relief when compared with systemic opioids.

Reducing the locked knee

Avoid undue manipulation, because it may aggravate internal derangement.

A simple measure to reduce the locked knee involves positioning the patient with the knee dangling over the edge of the examination table in 90° of flexion.

Gravity usually expedites distraction of the tibia from the femur, thereby promoting unlocking.

If this technique fails after a reasonable time period, tempered rotation of the knee along with traction on the leg usually frees the knee joint.



Depending on the degree of knee instability, affected ligaments, and the patient's age and baseline activity level, early surgical intervention may be the best option.

Indications for emergency or urgent orthopedic consultation include the following:

  • Gross knee dislocation or unstable knee
  • All knee injuries with associated neurologic or vascular injury
  • Complete quadriceps tendon rupture or a complete patellar tendon rupture
  • First-time patellar dislocations and patellar displacements accompanied by an osteochondral fracture
  • Open joint injuries of the knee

Medical Care

The type and degree of injury dictate the timing and specifics of follow-up care. Arrange checkups, preferably within 24 hours, for any patient sustaining softtissue injury of the knee in which (1) muscle spasm precludes adequate knee assessment, (2) the mechanism of injury suggests a more serious injury, or (3) the patient perceives a snap or pop at the time of the incident and a hemarthrosis evolves.

Promote RICE therapy for mild to moderately severe strains and/or sprains, as follows:

  • R - Rest (crutch ambulation without weight bearing for initial 24-48 hr)
  • I - Ice (application of ice on injured region for 20 min of each waking hour during the initial 48 hr after injury)
  • C - Compression (with knee brace or splint, if necessary)
  • E - Elevation (above the level of the heart)

After pain and inflammation subside, the goal of the second phase is to regain strength and pain-free range of motion (ROM). Arrangements for physical therapy can be made after reassessment in the next 3-5 days.

When the diagnosis remains in doubt, the orthopedic consultant usually decides on the necessity for arthroscopy or MRI to clarify the diagnoses.



Specific dislocations and fractures predispose the knee to popliteal artery and/or peroneal nerve damage.

Significant soft tissue injuries of the knee and lower leg put the lower leg at risk for compartment syndrome.

Knee joint instability may follow unrecognized ligament damage.

Complications of anterior cruciate ligament (ACL) injuries include abnormal knee motion, which eventually causes major degenerative changes in the knee joint.

Recurrent locking, damage to the articular cartilage, and ensuing arthritis may follow missed meniscal injuries.

Infection may arise from abrasions, lacerations, aspiration, or injection of the knee. If unrecognized, knee joint destruction results.

Spontaneous rupture of tendons may follow use of intra-articular steroids.