Common knee deformities

Definition:

Knee

Deformities

 

Genu Varus; Bow legs; Bandy legs In the coronal plane.

 

Genu Valgus ; Knock knees In the coronal plane.

 

Genu recurvatum ; Hyperextention . (In the saggital plane).

Flexion deformity of knee (In the saggital plane).

*By the end of growth the knees are normally 5°-7° of Valgus.

 

The child standing heels is touching each other the distance between the medial femoral condyles should be less than 6 cm.

For Genu Valgus the distance between medial malleoli should be less than 8cm.

The patellae facing forwards.

*Physiological G. Varus & G.Valgus. 

The child should be seen at 6/12 intervals.

If by the age of 10 years intercondyler distance > 6cm

Or

Intermalleolar distance > 8cm.

For G.Varus & G. Valgus respectively.

Do surgery

Stapeling of active part of epiphyseal plate or temporary epiphysiodesis.

ORHemiepiphysiodesis (fusion of one-half of the growth plate)

on the convex side of the deformity. ORCorrective osteotomy in adult. Commonest causes of Genu Varus : Infantile. 2- Rickets. 3- Traumat to the epiphyseal plate. Juvenile Rheumatoid arthritis. 5- Blount´s disease. 6-

Skeletal dysplasia.7- Paget´s disease. 8- Ligamentous injury.9- Osteo arthitis when the deformity secondary to

arthritis.10- Endocrine disorders.

Genu recurvatum: hyperextension of the knee:Congenital.Lax ligament : a- generalized joint laxity. b- Prolonged traction. c- Chronic recurrent synovitis e.g.

Rheumatoid arthritis.

d- Hypotonia of rickets. e- Flialness of poliomyelitis. f- Insensitivity of Charcot´s disease. Growth plate injuries.Malunited fractures.

LESIONS OF THE MENISCI  MINSCAL TEARS  The menisci have an important role in (1) increasing the

stability of the knee, (2) controlling the complex rolling and gliding actions of the joint and (3) distributing load during movement.

Tears are common in young adults. The meniscus is split in its length by a force grinding it between the femur and the tibia. In the young this usually occurs when weight is being taken on the flexed knee and there is a twisting strain; hence the frequency in footballers. In middle life, when fibrosis has restricted mobility of the meniscus, tears occur with relatively little force.

The medial meniscus is affected far more frequently than the lateral, partly because its attachments to the capsule make it less mobile.

Different patterns of tears are recognized.

Bucket-handle tears are when the split is vertical but runs along part of the circumference of the meniscus, creating a loose sliver still attached anteriorly and posteriorly. The torn sliver sometimes displaces towards the centre of the joint and becomes jammed between femur and tibia, causing a block to extension (‘locking ').

Horizontal tears are usually ' degenerative ' or due to repetitive minor trauma. Some are associated with meniscal cysts.

 Most of the meniscus is avascular, and spontaneous repair does

not occur unless the tear is in the outer third, which is vascularized form the capsule. The loose tag acts as a mechanical irritant, giving rise to recurrent synovial effusion and in some cases, secondary osteoarthritis.

CLINICAL FEAUTERS

The patient is usually a young person who sustains a twisting injury to the knee on the sports field. Pain is often severe and further activity is avoided; occasionally the knee is ' locked' in partial flexion. Almost invariably, swelling appears some hours later or perhaps the following day.

With rest, the initial symptoms subside, only to recur periodically after trivial twists or strains. Sometimes the knee given way spontaneously and this is again followed by pain and swelling.

It is important to remember that in patients aged over 40 the initial injury may be unremarkable and the main complaint is of recurrent ' giving way ' or ' locking’.

'Locking ' – that is, the sudden inability to extend the knee fully –suggests a bucket-handle tear. The patient sometimes learns to ' unlock ' the knee by bending it fully or by twisting it from side to side.

On examination, the joint may be held slightly flexed and there is often an effusion. In late presentations, the quadriceps will be wasted. Tenderness is localized to the joint line in the vast majority of cases on the medial side. Flexion is usually full but extension is often slightly limited.

Between attacks of pain and effusion there is a disconcerting paucity of signs. The history is helpful, and Apley’s grinding test may be positive.

 

INVESTIGATION Imaging Plain x-rays are normal but MRI is a reliable method for confirming the

diagnosis, and may even reveal tears that are missed by arthroscopy.   Arthroscopy Arthroscopy has the advantage that, if a lesion is identified, it can be treated

at the same time. You have to be certain, though, that the lesion which you can see is the one causing the patient's symptoms!  

Treatment  In the past, meniscal tears were treated by open operation. Nowadays

arthroscopic surgery is preferable. For peripheral tears, operative repair is feasible. In other cases, the displaced portion should be cleanly excised. Postoperative physiotherapy is an important part of the treatment.  

LOOSE BODIES  The knee - relatively capacious, with large synovial folds - is a

haven for loose bodies. These may be produced by:(1) injury (a chip of bone or cartilage), (2) osteochondritis dissecans (which may produce one or two fragments (3) osteoarthritis (pieces of cartilage or osteophyte); (4) Charcot's disease (large osteocartilaginous bodies are separated by repeated trauma in a joint that has lost protective sensation) and (5) synovial chondromatosis (cartilage metaplasia in the synovium, sometimes producing hundreds of loose bodies).

Clinical features  The patient may be symptomless, or may complain of sudden

'locking' without injury. The joint gets stuck in a position which varies from one attack to another. Sometimes the 'locking' is only momentary and usually the patient can wriggle the knee until it suddenly unlocks. The patient may be aware of something 'popping’ in and out of the joint'. Sometimes, especially after the first attack, the knee swells up, due to synovitis. In some cases there is evidence of an underlying cause. A pedunculated loose body may be felt; one that is truly loose tends to slip away during palpation (aptly named 'joint mouse').

X-rays  Most loose bodies are radio-opaque. The films may also show

an underlying joint abnormality.  Treatment  A loose body causing symptoms should be removed unless the

joint is severely osteoarthritic. This can usually be done with the aid of arthroscopy.