Mechanism of injury

The knee is the most commonly injured part of the body in sport.

Meniscal tears

These usually occur when the flexed knee is externally rotated. The meniscus, usually the less mobile medial, is caught between the bone ends and torn (Fig. 97). Footballers and downhill snow skiers when changing direction are prone to this (Fig. 98).

There is joint line pain, instability, an effusion and locking of the knee. Apley’s grinding test and McMurray’s test may be positive. The tear often has a bucket handle or parrot beak configuration.

This includes rest, ice, compression and elevation. Arthroscopic partial medial meniscectomy is indicated for a large tear which remains symptomatic. The meniscus is repaired when the tear is at the menisco-capular junction, especially in children (Fig. 99).

Mechanism of injury

The cruciate ligaments stabilise the knee. The anterior cruciate (ACL) may rupture when a valgus/external rotating force is applied to the knee as when cutting in football or in the hyperflexed or hyperextended knee.

There is an immediate ‘pop’ sensation with a large effusion (blood) and pain (Fig. 100). The knee is unstable. Lachman’s test, the dynamic self extension test and the pivot shift are positive (Figs 101 & 102).

Treatment includes intensive physiotherapy (hamstring strengthening) and later reconstruction of the ACL (using the middle third of the patellar tendon or part of the hamstrings) when the knee remains unstable in the young athlete.

The posterior cruciate ligament (PCL) is stronger and less commonly injured. Physiotherapy is required (avoid hamstring exercises) and seldom surgery. Osteoarthritis may secondarily develop.

Mechanism of injury

MCL, partial or complete, tears are common. A valgus force produces the injury (Fig. 103).

There is medial knee pain and tenderness with opening of the flexed knee from an abduction load (almost painless with a complete tear).

It may be associated with a medial meniscal tear and ACL rupture (O’Donoghue’s unhappy triad).

Partial and isolated complete tears need a brace and rehabilitation. Otherwise when in combination surgical repair is required.

Lateral collateral ligament tears (LCL) are less common and usually treated with a brace and rehabilitation.

Mechanism of injury

The patello-femoral joint is prone to problems including maltracking (from mal-alignment causing subluxation or dislocation), chondromalacia patellae (CMP) and patellar tendonitis. These present as anterior knee pain.

Mechanism of injury

There is softening of the patellar cartilage from direct contusion or malalignment (increased Q angle) (Fig. 104). Young overweight girls with knock knees are susceptible. There is anterior knee pain with swelling and difficulty with prolonged sitting and using stairs.

Treatment includes symptomatic relief (RICE and analgesia) and quadriceps rehabilitation.

Where there is an increased Q angle (angle between anterior superior iliac spine, patella and tibial tubercle, N < 15^O) and ligamentous laxity, subluxation may result. There is anterior knee pain with instability. If the patella dislocates the patient falls to the ground (Figs 105 & 106).

Treatment includes activity modification, RICE, rebalancing of the extensor mechanism (stretching of tight lateral retinacular structures, strengthening of the vastus medialis: McConnell technique) and a patellar lift-off brace. Rarely, surgery is required to rebalance by releasing the tight lateral retinacular structures and reefing the lax medial.

Iliotibial Band Friction Syndrome

Occurs in runners (downhill) and cyclists from flicking of a tight iliotibial band across the lateral fenioral condyle. Stretching or rarely excision of a posterior portion is required.

Lateral Patellar Compression Syndrome

This is where the Q angle is normal but lateral patellar retinacular structures are tight. Stretching or surgical release is required.

Mechanism of injury

(Jumpers Knee, Sinding-Larsen-Johansson Syndrome, SJR)

Jumping sports put a huge load on the extensor mechanism of the knee, usually at the lower pole of the patella, especially when it is associated with excessive foot pronation. There is pain and crepitus in that area.

Treatment includes activity modification, bracing (where ligamentous laxity), ultrasound and rarely surgical excision of the associated necrotic debris.

Osgood-Schlatters

Osgood-Schlatters is when the lower pole is involved. (See Chapter 11.)

Patella Alta/Baja

The patella may be too high (alta) causing instability or too low (baja) causing stiffness.

These are persistent vestigial folds of the synovium in the supra patellar pouch, medial gutter or in front of the ACL. They may become inflamed, thickened and fibrosed causing pain and hamstring muscle spasm.

Rehabilitation is required and possibly arthroscopic surgical debridement (Fig. 109).