- Ligament injury
- Medial collateral ligament injury
- Lateral collateral ligament injury
- Anterior cruciate ligament injury
- Posterior cruciate ligament rupture
- Knee dislocation
- Meniscal tears
- Discoid meniscus
- Meniscal cyst
- Patello-femoral joint problems
- Anterior knee pain syndrome
- Chondromalacia patellae
- Acute dislocation of the patella
- Recurrent dislocation of the patella
- Recurrent subluxation of the patella
- Patellar tendonitis
- Patellar fracture
- Quadriceps rupture
- Patellar ligament rupture
- Pre-patellar bursitis
- Bipartite patella
- Plica syndrome
- Ilio-tibial band friction syndrome
- Semimembranos tendinitis
- Loose bodies
- Hoffa disease
1 J Sullivan 1997 The Knee in E. Sherry D. Bokor (eds). Sports Medicine Problems and Practical Management. Chapter 14
The size, lack of stability and forward prominence of the knee make it prone to injury.
It is a complex hinge joint which allows free flexion, and some rotation in flexion. With progressive flexion there is roll-back of the femur on the tibial surface, limited by tension in the posterior cruciate ligament.
The articular surfaces of the knee have poor congruity and so little inherent stability (check some dried bones). Articular congruity is improved by the menisci, but stability depends on ligaments, capsule and muscle control.
The knee is injured from high torsional and deceleration forces (in running and contact sports). Diagnosis rests with history and clinical examination. The mechanism of injury often gives a useful clue to diagnosis (a knee which dislocates or slips with pain and a ‘pop’ suggests an isolated rupture of the ACL).
The four main ligaments are the medial and lateral collateral ligaments, the anterior and posterior cruciate ligaments. A useful (and conceptually new way) of looking at the knee is to view the ACL as proving a stable platform for the action of the quadriceps; conversely the PCL for the hamstrings (Fig.1). Integrity of these ligaments is crucial for stability and kinematics. Altered kinematics may lead to OA of the knee in the long term although there’s no convincing evidence that an ACL deficient knee is prone to OA as is a medial or lateral meniscal tear.
Medial Collateral Ligament (MCL)
The MCL extends from the medial femoral epicondyle, widens and inserts onto the tibia 8 to 10 cm below the joint line. Orientated in a posterior to anterior direction it is taut in extension. IT is susceptible to contact and non-contact injuries when a valgus force with external rotation force is applied and is twice the tensile strength of the ACL.
There is swelling over the medial knee, and later bruising. The knee is typically held flexed with a painful soft end point limiting extension (pseudo-locking). There is tenderness along the ligament, most marked at the femoral insertion; the integrity of the MCL is checked at 30° of flexion; apply a valgus force (Fig 2-watch the patient’s face: severe pain means partial tear (grade I, II), mild pain complete tear (Grade III); stay out of range of angry footballer’s left hook!). Grade III injury has >1cm opening of the medial joint line. If knee opens up in extension there is a more complex ligamentous disruption (±ACL/PCL). X-rays are usually normal (an avulsion fragment is rarely seen). Large calcification seen at the site of femoral insertion is the Pellegrini-Stieda lesion.
Treatment: Isolated MCL injuries (Grade I to III) can be treated in a knee brace for 4 to 6 weeks start with RICE and graded quadriceps strengthening. Realize that in normal gait there is a closing force on the medial joint line, and so early weightbearing can be allowed and bracing may not be necessary for Grade I to II MCLs. Brace Grade III injuries and where the patient feels instability on weightbearing. Recovery from a Grade I to II injury takes 3 to 4 weeks; grade III 6 to 8 weeks.
1 D M Daniel, W H Akeson, J J O’Connor. eds. 1990. Knee ligaments: Structure, Function, Injury and Repair. NY Raven Press.
Lateral collateral ligament injury (LCL)
The lateral collateral ligament extends from the lateral femoral epicondyle to the head of the fibula. Isolated tears are rare. More commonly injured with disruption of the postero-lateral corner. Usually requires surgical reconstruction (along with other ruptured ligaments).
Anterior Cruciate Ligament (ACL)
The anterior cruciate ligament is commonest major ligament knee injury in sport. The ACL runs from the postero-superior aspect of the lateral wall of the intercondylar notch in the femur to the tibial spines (average 12 mm thickness with 2 major bundles, the antero-medial and the postero-lateral, is a primary stabilizer to anterior tibial translation and controls the rotational screw-home mechanism in terminal knee extension.) Tensile strength is 2160N.
Mechanism of injury1
80% of ruptures result from non-contact injury. Where there is internal rotation and anterior translation force of the tibia caused by pivoting cutting or landing awkwardly from a jump. (also ruptured by hyper-extension of the knee and will fail with progressive valgus in combination with a medial collateral ligament tear).
In isolated non-contact injuries the patient ‘steps-off’ the knee at speed, feels pain . There is a characteristic ‘POP’ and a fall (giving way). Pivot shift test is accurate but possibly painful and better performed in post-acute phase [for right knee- hold straight leg and with your other hand push postero-lateral corner forward as knee is slowly flexed, when the ACL is ruptured the tibia moves far forward and then clonks back.).Lachman's test is accurate and easy to perform in acute phase(Fig 3-flex knee 30°, if tibia moves forward on lower end of femur with no firm end point then positive; the dynamic Lachman’s test is performed by allowing patient to actively extend knee and the tibia is seen to move (too) far forward).
Swelling is almost immediate, from a haemarthrosis. Note : In the absence of fracture 80% of acute knee haemarthroses are due to rupture of the ACL.
Examination reveals a tight effusion in a flexed knee (increases capsule volume)with tenderness over the antero-lateral joint line from a commonly associated capsular injury. The Lachman test is performed.
X-ray may show an avulsion fracture involving the tibial spine, (especially in younger patients). Note avulsion fracture from the antero-lateral tibia, (Segond fracture). An MRI will accurately show the ruptured ligament. (too expensive and not necessary when carefully examine).
Treatment is determined by associated injuries (meniscal, ligamentous), degree of instability and patient expectation. Initially manage conservatively with RICE range of motion and muscle strengthening programme. Where persistent joint line symptoms or locking may have meniscal tear and need arthroscopy. (Patients who have an associated Grade III rupture of the MCL better served by early ACL reconstruction). Otherwise, ACL reconstruction is for patients who want to return to high demand sports where ongoing instability .
1 E Sherry 1993 Skiing Trauma in Australia MD Thesis. UNSW. Chapter 2 Fall Mode analysis.
Chronic ACL insufficiency
After an isolated rupture of the ACL most knees settle down over 6 to 12 weeks. The ligament does not heal . One third of patients are asymptomatic, some are only symptomatic with jumping or cutting sports (netball, football, skiing);a small group is significantly symptomatic with all activities. Symptoms include giving way (with pain) and recurrent swelling (repeated giving way may injure the menisci and cause osteochondral trauma with the later development of OA).
Examination may show good muscle tone and no effusion (range of motion is preserved). The Lachman, pivot shift, and anterior draw tests(ADT) are positive (ADT: Hyperflex knee, sit on foot, pull tibia forward. Excessive, >1cm, motion indicates ACL tear). McMurray’s test will indicate associated meniscal tear (Put thumb and index finger across joint lines and fully flex knee rotating internally then externally; abnormal click suggests meniscal tear). Occasional instability with high demand sports requires modification of activity and an intensive lateral hamstring strengthening programme. Symptomatic instability will require knee brace(S-Knee) or if that is not good enough then ACL reconstruction (up to 85% of patients will return to their pre-injury level of sports; Laxity of the graft gradually increases but patients remain asymptomatic). No strong evidence exists that reconstruction lessens the development of OA1.
Posterior cruciate ligament rupture (PCL)
The PCL runs from the anterior medial wall of the intercondylar notch of the femur to the central posterior tibia, (1cm below the joint line). Composed of antero-lateral and postero-medial bands. Primary restraint to posterior tibial translation.
Early symptoms may be mild and isolated ruptures. Examination will show a posterior sag with tibial drop back (Hyperflex knee and note posterior sag; Otherwise note posterior sag with push on tibia-Fig. 4). X-rays may show an avulsion fracture involving the tibial insertion (treat operatively). An MRI scan will slow the ligament tear.
Treatment of mid-substance ruptures is non-operative with intensive quadriceps strengthening. A PCL deficient knee will develop (due to the altered kinematics, patello-femoral pain with OA of the patello-femoral and medial compartments.) Early reconstruction is probably better for young patients.
An orthopaedic emergency with injury to the popliteal artery and common peroneal nerve (when lateral) (ACL, PCL, MCL, LCL are torn).
Immediate reduction is mandatory and then immobilize (splint). Check pedal pulses and organize an angiogram. (Delayed occlusion of the popliteal artery may occur due to an intimal flap tear). Later surgical reconstruction is almost always required.
1 D W Jackson 1996. Indications, Contra indications, and Treatment Decision-Making ACL reconstruction. AAOS Summer Institute San Diego.
2 J C Kennedy 1963. Complete dislocation of the knee JBJS 45A 889-904.
The menisci are fibrocartilaginous semi-lunar structures attached to the tibial surface (improve the congruity of the knee, transmit load, act as shock absorbers and improve knee joint stability). Note that after meniscectomy contact area is reduced, contact pressures increase by more than 350%,
hock absorbing capacity reduced, and OA develops. The blood supply is limited to the peripheral one quarter to one third (Tears in the vascular region have potential for healing). Medial tears are 5 times more common than lateral.
The meniscus is torn when trapped between the two bone surfaces as a rotary force is applied to the loaded knee (twisting when rising from a full squat).
Examination: There is pain, delayed effusion, and locked knee with a bucket handle tear). Smaller tears cause recurrent clicking, catching and joint line pain.
There is an effusion, wasting of the quadriceps, pain on forced extension, pain on forced flexion, and a positive McMurray’s test.
MRI will exclude other pathology.
Arthroscopy affords good visualization and partial meniscectomy. Peripheral bucket handle, and incomplete bucket handle tears (in young patients) should be repaired /sutured. Reconstruct an associated anterior cruciate ligament rupture, prevent recurrence of the meniscal tear. (Unhappy ‘Triad’ is medial (some say the LCL) collateral/anterior cruciate ligament/medial meniscal injury combination).
A meniscus, usually the lateral, which is not the usual C-shaped but nearly covers the whole plateau (3 types: incomplete/complete/Wrisberg-type (no posterior attachment). Mechanical symptoms of joint-line pain and ‘clunking’. Partial menisectomy may be required (i.e. reshape) (Fig. 5).
1 P M Aichroth, Dr. Patel, C L Marx. 1991. Congenital discoid lateral meniscus in children. A follow up study and evolution of management. JBJS. 73B, 932-936.
Arises from a horizontal cleavage tear of the lateral meniscus. (Fig. 6)
Patello-femoral joint problems
The patellar is a sesamoid bone in the quadriceps tendon (present at seven and a half weeks gestation). It improves the efficiency of the quadriceps mechanism by lengthening the moment arm, decreasing friction, improving stability, and centralizing the quadriceps muscle pull, also protects the anterior aspect of the joint. Stability of the patella is provided by the anatomy of the trochlear groove and patella, static tension in the soft tissues of the medial and lateral retinaculum, and the dynamic control of the quadriceps. The vastus medialis obliqus muscle is especially important in maintaining patello-femoral balance and normal tracking. Acute injuries to the patello-femoral joint include direct trauma, subluxation or dislocation, patellar fracture, quadriceps tendon or patellar ligament rupture. Many patients present with anterior knee pain with no injury.
Anterior knee pain syndrome
The commonest sports knee complaint. Pain may be well localized (patellar tendinitis), but usually vaguel anterior; aggravated by loading a flexed knee (climbing stairs or inclines) or after sitting for prolonged periods. There is crepitus, catching, weakness giving way and an effusion. Causes are many and physical examination unremarkable apart from retropatellar crepitus.
• Trauma (Osteochondral injury)
- Anatomical pre-disposition
- Muscle imbalance
- Patellar subluxation
- Patellar dysplasia
- Excessive lateral pressure syndrome
- Hamstrung patella
- Patellar tendinitis
- Medial plica syndrome
- Retinacular irritation
- Osgood Schlatter’s disease
- Bipartite patella
- Primary chondromalacia
80% of such patients respond to non-operative measures. Identify precipitating and aggravating activities. A physical programme includes quadriceps strengthening and in particular vastus medialis toning (straight leg raise externally rotated leg) with hamstring stretching. Patellar taping or S-Knee brace will help . If improvement is not seen within 6 to 8 weeks, the diagnosis should be reassessed and further investigation undertaken.
A softening of the patellar cartilage either from a direct blow or mal-alignment (with patellar subluxation). Typically seen in young overweight girls with knock-knees. The cartilage damage is classified.
Acute dislocation of the patella
Occurs from an external rotation with a valgus force with the knee in extension or from a direct blow. The diagnosis is obvious and reduction achieved by gentle extension of the knee (spontaneous reduction usually happens). There is haemarthrosis, tender medial patellar retinaculum, positive patellar apprehension test (push patella laterally as knee is flexed and note pain) and patellar instability. X-ray to exclude a significant osteochondral fracture (arthroscopy and excision of the fragment is required).
Treatment: Drain a tense haemarthrosis for pain relief, immobilize in extension (a removable Zimmer splint). Start isometric quadriceps exercises (no knee bending) and may weightbear as tolerated. As the effusion resolves graduated flexion started and the knee splint discarded (by three weeks). Return to sport when regained normal quadriceps muscle tone/bulk and a negative apprehension test present.
Recurrent dislocation of the patella
Clear from history if no response to an extensive quadriceps strengthening programme, surgery is required (a lateral release and repair or advancement of the medial retinacular tissue and vastus medialis, if intra-operatively this does not achieve stability a distal bony realignment required).
Recurrent subluxation of the patella
There is anterior knee pain and giving way. Examination shows increased Q angle (line of pull of the quadriceps) valgus or rotation factors, out-turned patellae or patellar alta (high). The patella tracks in a J-curve (Fig. 7). The patella may be subluxable or dislocatable. Lateral retinacular tightness present (not able to lift lateral border of patella >1cm). X-rays (skyline views) and CT scan may show patellar dysplasia or subluxation. If there is no improvement with a protracted programme, surgery is required (soft tissue or bony realignment).
Patellar tendinitis (Jumper’s knee)
An over-use injury, (seen in basketball). There is anterior knee pain (with exertion). With point tenderness over the central insertion of the patellar ligament into the patella, with swelling and crepitus. The hamstrings and gastrocnemiae maybe tight. MRI scan altered signal at the site of the degenerative tendon. A bone scan shows creased uptake.
Treatment includes: rest with modification of activities (jumping); A graduated exercise programme to strengthen the quadriceps, and intensive stretches for the hamstrings and gastrocnemiae. The over-lying bursa may be injected with corticosteroid and local anaesthetic (½ amp. celestone with 2mls of 0.5% marcaine with adrenaline). If symptoms persist surgical debridement of the degenerative tendon with a segment of patellar bone may be necessary.
Direct impact on the patella from a fall on a flex knee or a dashboard injury, also following violent resisted contraction of the extensor mechanism. If there is disruption of the extensor mechanism (indicated by a lag or inability to straight leg raise; a significant gap on x-ray) surgical repair is essential. Undisplaced minimally displaced fractures with preservation of the extensor mechanism are treated, by splinting in extension for 6 weeks.
Caused by sudden resistance to a strong quadriceps contraction. Seen in the older patient group (as with other tendon degeneration conditions). President Bill Clinton’s knee injury in 1997. There is pain with loss of quadriceps function, a lag, and a palpable gap. When the diagnosis is unclear (rectus femoris only torn and vastus medialis/lateralis intact) and particularly when presentation is delayed MRI is useful. To restore function operative repair is required.
Patellar ligament rupture
Occurs in younger patients ,at insertion onto tibial tubercle, by the same mechanism as quadriceps tendon rupture (also by penetrating injuries, (dashboard).In older patients may avulse from lower pole of patella. There is pain and loss of quadriceps function with a significant lag. The defect is usually palpable. Surgical repair is indicated.
The bursa over the anterior aspect of the patella is prone to injury and inflammation from repetitive contact (seen in football players and gymnasts). Tendency to become recurrent. Examination shows enlargement of the thickened bursa with crepitus. Acute cases may have secondary infection with cellulitis. The inflammatory bursitis is treated with RICE and NSAIDs. Padding and protecting the area on return to sport is important to minimize the risk of recurrence. Where secondary sepsis use antibiotics and surgical draining of an abscess. Recurrent or chronic bursitis will eventually require excision of the thickened bursa.
Bipartite patella (accessory ossification centre)
Present in <15% of patellae, usually asymptomatic and at the superio-lateral corner. Symptoms may occur after direct contact injury or over-use. Include anterior knee pain and tenderness (over the site of the pseudarthrosis). X-rays show the bipartite patella (a bone scan is helpful following significant trauma). Most settle with a conservative programme as in the Management of Anterior Knee Pain Syndrome. Rarely is excision of the fragment required.
Vestigial synovial plicas are common (either patello femoral, medial or over ligamentum mucosum) and often seen at arthroscopy. They may become symptomatic following a direct injury causing thickening and scarring of the plica, or from over-use. There is anterior knee pain syndrome with clicking, snapping and tenderness over the medial femoral condyle.
Those that do not settle with rest and a conservative programme require arthroscopic resection.
Ilio-tibial band friction syndrome
Seen in joggers and distance runners. There is inflammation over the lateral epicondyle caused by rubbing of the ilio-tibial band. Examination reveals point tenderness over the lateral epicondyle, reproduced as the ilio-tibial band passes back and forth over the lateral epicondyle. There may be tightness of the tensor fascia lata and hamstring muscles.
Treatment involves rest and stretching of the ilio-tibial band and hamstring muscles. A break of three months from distance running is may be necessary.
This is seen in male athletes and my be difficult to diagnose (postero-medial knee joint pain with hamstring spasm). A cyst may occur which is difficult to excise.
1 J M Ray, W G Clancy, R A Lemon 1988. Semimem branosus tendinitis. An overlooked cause of medial knee pain. Am J Sports Med. 16, 347-351.
Loose bodies cause mechanical symptoms of locking and recurrent effusions. Occasionally they can be palpated. They can be due to a meniscal fragment or osteochondral fragment (traumatic, degenerative, osteochondritis dissecans) or synovial chondromatosis. X-rays will demonstrate radio-opaque loose bodies. Treatment is arthroscopic removal.
Old entity, trauma with bleed into anterior fat pad around patellar tendon, common in children or genu recurvatum. Treat with activity modification, NSAIDs, knee pad or arthroscopic minimal resection.