Home » Quadriceps Tendon Rupture

It is not common for the quadriceps tendon to rupture and when it does it mostly presents in t hose older than 40 years. Certain diseases and previously existing degeneration in the knee extensor apparatus makes this condition more likely to occur. A rupture on one side is the most common occurrence and bilateral ruptures indicate there are very likely to be underlying causative factors. Patellar tendon ruptures are less frequent than ruptures of the quads tendon and present in younger people under 40. It is important to make an early diagnosis of this problem and operate as soon as possible afterwards as delay makes the outcomes poorer.

Quadriceps rupture is likely to occur in particular actions, when the muscle is lengthening under load at some speed and the foot is anchored on the ground. Other causes are lacerations and cuts, direct trauma to the knee and falls. Because relatively trivial force can rupture the tendon of the quadriceps and that tendons which are normal do not rupture within the substance of the tendon, when a rupture does occur it is likely to be through a pathological tendon area. The likelihood of ruptures occurring increases with the presence of particular illnesses or diseases such as obesity, infections, steroid use over a period, immobilisation and arthritic conditions. Some knee operations and intra-articular steroid injections can precipitate rupture.

Just above the upper kneecap pole is the commonest site for rupture of the tendon of the quadriceps, the rupture occurring through abnormal tissues. The structural make up of the tendon or the blood supply can be damaged by a variety of medical diseases. Changes in the blood vessels can be produced by diabetes and high bodyweight can produce fatty changes in the tendon structures and an increased level of forces through the tendon. Ruptured tendons have been investigated and shown microscopically to possess degenerative changes without significant inflammation. Poor supply of oxygen and insufficient nutrition are important precursors to tendon degeneration.

Typical presentation of a patient is for them to complain of acute knee pain, knee swelling and loss of functional knee ability after giving way of the knee, a fall or a stumble. They may not have had knee pain previously and the knee may have gone pop audibly at the time of the incident. Patients will have difficulty walking and examination will show swelling above the kneecap, bruising and tenderness. A gap in the tissues just above the patella may be clearly apparent to touch with the patella lying lower than normal over the knee.

Active extension or straightening of the knee against gravitational force is the important factor to assess in the patient's ability. An extension lag, where the patient cannot completely straighten their knee with their own power, is an indication of a potential rupture. The inability to straighten the knee will vary with the severity of the injury and partial ruptures are more difficult to diagnose. Any delay in assessing and diagnosing the patient is unhelpful and due to the difficulty in diagnosis it is common for this injury to be misdiagnosed with inevitably inappropriate management.

Improvement should occur in the knee swelling and pain with time, with the patient regaining walking ability and some quadriceps function. Walking can be difficult with the knee having the tendency to give way regularly and going up stairs being difficult, the patient hip hitching to bring their leg through in gait and then bracing the knee back to prevent instability. Typical management for complete, acute ruptures is to operate early and surgical repair can be effective also in chronic ruptures. Immobilisation in a plaster cast may be used for partial tears, with 3-6 weeks in the cast followed by extensive physiotherapy to regain function.

Immobilisation in a plaster cylinder for four to six weeks is a typical postoperative management with most patients being allowed to weight bear in the cast with crutches or a frame. Once the plaster cast is removed the patient may be placed in a hinged knee brace, allowing the flexion to be limited by the brace to particular ranges of motion which can be gradually increased as healing proceeds. Physiotherapy is then initiated, continuing with rehabilitation until the ranges of motion and strength of the knee mirror the unaffected knee.

Jonathan Blood Smyth, editor of the Physiotherapy Site, writes articles about Physiotherapy, back pain, orthopaedic conditions, neck pain, injury management and Physiotherapists in Coventry. Jonathan is a superintendant physiotherapist at an NHS hospital in the South-West of the UK.