Knee Flashcards
What group of patients are predisposed to knee injuries/pain and why?
Risk factors for developing knee OA include age over 50, female gender, higher body mass index, previous knee injury or surgery, malalignment, joint laxity, occupational or recreational activities that stress the knee, family history
Individuals with hypermobility disorders, such as Ehlers-Danlos syndrome are at risk for chronic patella subluxations
Older adults, particularly females with osteoporosis can sustain intra-articular fractures from low velocity trauma such as awkward step of a fall from standing.
What medications may predispose patients to fractures and why?
Osteoporosis is one of the most serious complications of oral corticosteriod treatment.
What is the importance of determining if there are any associated injuries?
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What are the most common mechanisms for acute knee injuries?
Acute trauma can include collision between players, skiing accident and fall from height. An athlete may experience immediate pain after jumping, landing, cutting, squatting, slipping or sprinting
What is the relevance/importance of establishing the mechanism of injury for acute knee injuries?
Establishing the MOI determines the initial differential diagnosis which guides the subsequent evaluation, ultimately leading to the correct diagnosis and treatment.
Eg: basketball player whose knee buckles while landing after a jump shot, followed by rapid knee swelling, gives a history suggesting ACL injury.
What is the relevance of establishing any sensations felt at the time of injury and timing of onset of swelling?
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What is the relevance of determining the patient’s ability to weight bear at the time of injury
Inability to WB 4 steps both immediately after injury and at presentation to ED warrants investigation with x-ray.
What is the relevance of establishing any other symptoms felt since the initial injury (ie giving way, locking, instability, onset of swelling)?
Many people with PFP experience instability due to reflex inhibition of the quadriceps.
Rapid swelling following an acute injury occurs with bleeding into the knee joint, and occurs with significant tissue damage such as ACL tear.
It is important to distinguish true mechanical instability from pain-mediated instability. True instability occurs when the knee gives way during a routine activity (climbing stairs, walking) without pain preceding the episode. Such instability occurs with ligament tears and patellar instability.
Locking of the knee suggests a mechanical block, as might occur with meniscal tear or loose piece of cartilage.
What is the relevance of determining the type of activity which led to the knee injury?
Acute knee pain may stem directly from trauma or from regular activity or it may be unrelated to trauma or activity. It is important to determine whether the onset of pain was abrupt or insidious.
Acute pain associated with overuse generally refers to pain that develops or increases abruptly after excessive activity.
What is the relevance of determining the neurovascaulr status of the knee or lower leg?
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What key information is important in the setting of atrumatic knee pain?
Is there associated swelling?
What key information is important to assess for red flags?
presence of symptoms such as fevers, chills, night sweats, fatigue, or rash suggests a systemic illness and further investigations of infectious, autoimmune or neoplastic cause is necessary.
What key information is important to determine in the setting of chronic knee pain?
Chronic knee pain associated with overuse is the major diagnostic category to consider. They are typically progressive, becoming more painful with increasingly less intense activity over time.
What key information is important in the setting of a swollen knee without trauma?
Swelling or erythema occurring without trauma may indicate an infectious, rheumatologic or crystal induced condition
Osteochondral defects are usually caused by significant knee trauma but may be secondary to milder trauma or chronic overuse (eg, osteochondritis dissecans). Patients with such defects often describe diffuse knee pain that is worse during and after activity. A knee effusion brought on by activity is an important historical clue, as spontaneous effusions unrelated to activity generally do not occur with osteochondral defects.
OA can present as diffuse or localized knee pain, with or without an effusion. Intermittent effusions occur in persons with OA when they increase their activity
What key information in patient’s past history is important for patients presenting with knee injury/pain?
A past history of knee injury is the most accurate predictive risk factor for future knee injury. Often, a new knee injury is a complication of an old or concurrent injury
What key information in a patient’s medication history is important for patients presenting with knee injury/pain?
There are several reasons for taking an accurate medication history
- a knowledge of the drugs a patient has taken in the past or is currently taking and of the responses to those drugs will help in planning future treatment
- Drug effects should always be on the list of differential diagnoses, since drug can cause illness or disease, either directly or as a result of an interaction
- Drugs can mask clinical signs
- To help avoid preventable errors in prescribing, since an inaccurate history on admission to hospital may lead to unwanted duplication of drugs, drug interactions, discontinuation of long-term medications and failure to detect drug-related problems.
The medication history should not simply be a list of a patient’s drugs and dosages. Other information, such as adherence to therapy, and previous hypersensitivity reactions and adverse effects, should be noted and should be compared with the patient’s GP records or previous prescription history in their hospital case notes.
Herbal remedies are infrequently recorded but may be important causes of morbidity.
what key areas of social history are important for patient’s presenting with knee injury/pain?
Family history of OA
What is the relevance of determining any treatment to date for patients presenting with a knee injury/pain?
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What is the relevance of determining last intake of food or fluids?
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What is the relevance of determining the compensable status or health insurance status of the patient?
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Common causes of knee pain following acute, low energy trauma
Medial or lateral collateral ligament tear Anterior cruciate ligament tear Meniscal tear Patellar dislocation or subluxation Patellar tendon tear Intra-articular fracture Osteochondral defect
Less common cause of knee pain following acute, low-energy trauma
Bone contusion Posterolateral corner injury Posterior cruciate ligament tear Quadriceps tendon tear Fibular head or neck fracture Patella fracture Knee (tibiofemoral) dislocation
Vascular supply of the knee and lower leg
The main artery of the lower limb is the femoral artery. It is a continuation of external iliac artery. In the femoral triangle, the profunda femoris artery arises from the posterolatearl aspect of the femoral artery. It travels posterior and distally, giving off 3 main branches: perforating branches (supply muscles in the medial and posterior thigh), lateral and medial femoral circumflex arteries (supplies muscles on lateral aspect of thigh and femoral neck and head).
After exiting the femoral triangle, the femoral artery continues down the anterior surface of the thigh via adductor canal. The femoral artery exits through adductor hiatus and enters the posterior compartment of the thigh proximal to the knee where it becomes popliteal artery.
In addition to the femoral artery, there are other vessels supplying the lower limb. The obturator artery arises from the internal iliac artery in the pelvic region. It bifurcates into 2 branches: anterior and posterior branches. The gluteal region is largely supplied by the superior and inferior gluteal arteries.
The Popliteal artery descends down the posterior thigh giving rise to branches that supply the knee joint. At the lower border of the popliteus, the popliteal artery terminates by diving into the anterior tibial artery and the tibioperoneal trunk. In turn, the tibioperoneal trunk bifurcates into the posterior tibial and fibular arteries. Posterior tibial artery continues inferiorly, along the surface of the deep posterior leg muscles and enters the sole of the foot via tarsal tunnel. Fibular artery descends posteriorly to the fibula, within the posterior compartment of the leg and gives rise to perforating branches which supplies muscles in the lateral compartment of the leg. The other division of the popliteal artery, the anterior tibial artery, passes anteriorly between the tibia and fibula, moves inferiorly down the leg, into the foot where it becomes doralis pedis artery.
How would you determine the neurovascular status of the knee and lower leg?
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Describe the relevance of any local skin changes/open wounds to the knee and lower leg
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