Session 8 Flashcards
What is a common complication of a hamstring strain?
Rupture to the surrounding blood vessels leading to a haemotoma contained within the fascia lata
How does an avulsion fracture to the ischial tuberosity commonly occur?
In sports that require rapid contraction and relaxation
What are the articulations of the knee joint?
Tibiofemoral - between femoral and tibial condyles (main weight bearing)
Patellofemoral
What are the functions of the menisci of the knee?
Deepens the articular surface of the tibia, increasing stability
Acts as a shock absorber
What are the connections of the medial and lateral menisci of the knee?
Both C shaped and connect to Intercondylar area. Anteriorly connected by transverse ligament of the knee. Medial meniscus is connected to the tibial collateral ligament
What is the function and attachments of the cruciates?
Posterior cruciate ligament - passes Anteriorly from posterior tibia and inserts Medially on the femur (PAMs). Prevents posterior dislocation of the tibia. Main stabiliser of a weight bearing flexed knee.
Anterior cruciate ligament - passes Posteriorly from anterior tibia and inserts onto Lateral femur (APpLes). Prevents anterior dislocation of tibia.
Describe the distribution of the joint capsule of the knee
Absent anteriorly the allow synovial membrane to extend up beneath patella. Strengthened laterally by inferior fibres of vastus medialis and lateralis. Strengthened posteriorly by the oblique popliteal ligament.
What are the Extracapsular ligaments of the knee and where do they insert?
Tibial (medial) collateral ligament - medial femoral epicondyle to tibia
Fibular (lateral) collateral ligament - lateral femoral epicondyle to lateral surface of fibular head
What causes rotation of the flexed knee?
Medial - Semitendinosus, Semimembranous
Lateral - biceps femoris
What does the knee do to reduce energy expenditure when standing?
Femur rotates internally over tibia to lock knee in place and hold it in position. The popliteus contracts to rotate the femur externally and unlock the knee.
What are the 3 bursa in the knee prone to bursitis?
Supra-patellar
Pre-patellar (housemaids knee)
Superficial infra-patellar (clergymans knee)
What is an “unhappy triad”?
Damage to the medial collateral ligament can affect the medial meniscus, such as a lateral force to the extended knee. The ACL is also affected, completing the unhappy triad.
How is the ACL injured and tested?
Hyperextension of the knee or by a large force to the back of the knee whilst flexed. Tested with an anterior draw test where the tibia is attempted to be pulled forwards.
How is the PCL injured and tested?
“Dashboard injury” - force on shins when knee is flexed. Tested by the posterior draw test - knee flexed and shin pushed posteriorly
What are the 3 bursa in the knee prone to bursitis?
Supra-patellar
Pre-patellar (housemaids knee)
Superficial infra-patellar (clergymans knee)
What is an “unhappy triad”?
Damage to the medial collateral ligament can affect the medial meniscus, such as a lateral force to the extended knee. The ACL is also affected, completing the unhappy triad.
How is the ACL injured and tested?
Hyperextension of the knee or by a large force to the back of the knee whilst flexed. Tested with an anterior draw test where the tibia is attempted to be pulled forwards.
How is the PCL injured and tested?
“Dashboard injury” - force on shins when knee is flexed. Tested by the posterior draw test - knee flexed and shin pushed posteriorly
How are medial meniscus tears tested and why is the lateral meniscus not normally torn?
Pain on medial rotation of the tibia. Lateral meniscus is usually too mobile to tear.
What are the borders of the popliteal fossa?
Superiomedial - Semimembranous
Superiolateral - biceps femoris
Inferiomedial - medial head of gastrocnemius
Inferiolateral - lateral head of gastrocnemius and plantaris
Floor - posterior surface of the knee joint capsule
Roof - popliteal fascia and skin
What are the contents of the popliteal fossa medial to lateral?
Popliteal artery
Popliteal vein (with small saphenous vein draining into it)
Tibial nerve
Common fibular nerve
What are the causes of a mass in the popliteal fossa?
Bakers cyst - inflammation of the Semimembranous bursa, usual arising in conjunction with arthritis. The cyst can rupture and cause symptoms similar to DVT.
Popliteal aneurysm - causes compression of the tibial nerve, leading to leg anaesthesia or loss of motor function because popliteal fascia is strong.
Rarer causes are DVT and various neoplasms.
