Q: One of the young lads I'm training is suffering from what I believe to be Osgood Schlatters, I think from over playing, but I am making sure he is playing less than most. He is still playing more than I'd like and he is growing quite a lot at the moment. But I told him not to play now until he feels absolutely no pain in his knee from doing the full squat. During a session today he said he could feel it slightly, then when he did the squat on a padded mat, not at all. Why is that?
Tennis coach, 24, UK

A: Are you sure it's Osgood-Schlatter's? If it is there will be pain on activities involving bending the knee, tenderness and possibly a warm swelling or lump, all felt over the tibial tubercle at the top of the front of the shin-bone. Obviously, it would be best for the player to see a sports doctor or orthopaedic specialist, to confirm the diagnosis and advise accordingly.

If the problem is confirmed as Osgood-Schlatter’s condition, and there's only slight pain on squatting, and none on the soft surface, then it's probably OK for the youngster to carry on with controlled and limited activities: exercise is good for the condition, provided it causes no pain during or immediately afterwards.

The only reason I can think of for pain being less on squatting on a soft surface would be that the angle is altered, either because his feet varied, causing a slight twist at the knee, or because he didn't squat as fully as on a hard surface. I presume he was on his toes for both versions? (There's more pressure on the front of the knees with the heels flat.)

To explain Osgood-Schlatter’s condition in more detail:
The tibial tubercle is an apophysis, a knob of bone which grows separately from its main bone, as an attachment point for a tendon. The patellar tendon is attached to the tibial tubercle. The knob fuses on to the parent bone at the appropriate age. In the case of the tibial tubercle this is somewhere between 12 and 16. While the fusion process is going on, the knob is very vulnerable to excessive pressure from the pull of the tendon against it. The tibial tubercle is at risk through all activities involving loading the bent knee repetitively or over-forcefully, as in football, squash, tennis, running and so on. This is simply because the join between the apophysis and the main bone is relatively weak, because the "gluing" process is incomplete, whereas the tendon is relatively strong. The tendon exerts enough force against the apophysis to pull the connexion point apart to some degree, causing pain when the area is put under similar pressure, whether through sport or movements such as crouching, kneeling or going down and up stairs.

Apophysitis is the technical name for injuries involving disruption of the union between an apophysis and its main bone. Osgood-Schlatter's condition is the name given to the condition when it affects the tibial tubercle.

Apophysitis is a very similar injury to a stress fracture in the way it happens, the pain it causes and the way it is healed. Adults can cause a stress fracture in the tibial tubercle by overloading the knee repetitively, for instance through high jumping or prolonged sessions of squatting or hopping exercises. Cause and effect are almost identical, and treatment is the same for adults as for children. In children and adults, background factors can include specific inadequacy in vastus medialis obliquus (VMO) function, tightness and weakness in the thigh muscles, imbalance between the thigh muscles, stiff hips, stiff ankles, and previous injuries to the knee.

To cure Osgood-Schlatter's condition:
1. the youngster must rest from any pain-causing activities.
2. painless exercise to promote the circulation through the leg must be carried out daily and frequently, whether general exercises, swimming, possibly cycling, cross-training and so on.
3. VMO strengthening exercises  must be done, within painfree limits.
4. the front-thigh must be stretched gently, as often as possible
5. the hamstrings must be stretched carefully, frequently.
6. the calf muscles, especially soleus, must be strengthened.
7. any obvious imbalance in the muscle groups of the whole leg must be corrected through exercises.
8. knee supports which restrict or enclose the whole knee should not be worn - they're not necessary or helpful, and they can cause further weakening of the VMO through adverse pressure on the circulatory system.
9. to take pressure off the tibial tubercle, a small strap or a band of taping can be applied just under the kneecap.
10. ice, cold compresses and arnica cream or arnica compresses can be used to reduce any swelling and soreness over the tibial tubercle.
11. Shoes should also be checked. In particular, young tennis players with painful knees should be made aware, if they aren't already, of the importance of wearing the right shoes on different court surfaces. A common cause of knee problems is wearing shoes with grip on carpet or certain synthetic surfaces - the shoes should have smooth soles, so that there is minimal traction between the foot and the surface. Otherwise there will be severe jarring at the knee.

Treatment for Osgood-Schlatter’s condition:
So far as treatment goes, I stick to manual therapy and of course electrical muscle stimulation for the VMO. Some electrotherapy modalities, such as ultrasound, are generally considered unhelpful to growth points or stress fractures. There's anyway little to gain from passive treatment methods (including taking painkillers), and there's always a risk that they might cause further harm.

Time and the right kind of exercise are the keys to recovery. it's vital not to stress the knee too soon. On average, it's going to take about 2-3 months for the inflammation to settle down and full function to be regained. The criterion for starting light jogging is the ability to do something more than a half-squat without pain - preferably a full squat. Any exercise involving repetitive jarring of the legs should be spaced out, only 1-2 times a week at first, with a gradual build-up. If the patient does anything painful during the recovery period, the problem can drag on, literally, for years.

Safe practical guidance:
From your point of view as a coach, you should be guided by the youngster’s pain. If there's pain of any kind associated with an exercise or activity, it's the signal to stop. You should, if possible, take note of the main points about the pain (where it is, when it started, what triggers it, and what relieves it ), and any obvious physical imbalances, in order to set out rational alternative training schedules. If the youngster (or parent / responsible adult)  doesn't want that, and chooses to push on with sports regardless of pain, that’s their choice, but you, as a responsible coach, should never allow or encourage a child to do training which actually causes pain. If you are concerned that the youngster is not dealing with the injury safely, you should advise him to stop sport and refer to a medical specialist.