A jumpers knee is an overuse injury located at the insertion of the patellar tendon being attached on the lower edge of the kneecap (patella). The patellar tendon / ligament joins the kneecap (patella) to the shin bone (tibia). This tendon is extremely strong and allows the quadriceps muscle group to straighten the leg. The quadriceps actively straighten the knee in jumping to propel the individual off the ground as well as functioning in stabilizing their landing. So, it is not surprising that this overload injury has a high incidence in jumping and interval sports like volleyball, handball, korfball, although it has a high frequency in soccer, tennis, field hockey and track-and-field also.
> Etiology
Overuse of the patellar tendon is frequently caused by exercises as jumping and heavy lower extremity weight training in athletes 15-35 years in age. Especially landing on one leg implicates peak loading focused at the insertion of patellar tendon. Furthermore, individuals who actively put extra strain on the knee joint such as those who regularly perform sports that involve direction changing and jumping movements, have an increased risk to sustain a jumpers knee. With repeated strain, micro-tears as well as collagen degeneration may occur as a result in the tendon. Other causal factors mentioned in the scientific literature are shortening of the quadriceps muscle group and overweight. Also insufficient flexibility of the hamstrings and quadriceps muscles and malalignment (knock knees or flat feet) may contribute to undue stress on the patellar tendon and therefore the development of a patellar tendinopathy.
> Symptoms
Athletes suspected of a jumper's knee are complaining of:
- An area of pain and tenderness pinpointed at the affected portion of the tendon.
- Local pain at the bottom and front of the kneecap when pressing in or palpating.
- Aching and stiffness after exertion.
- Pain when contracting the quadriceps muscles.
- Urge to move caused by longlasting situations in the same static position (sitting and standing).
> Diagnosis
Consulting a health care provider (medical doctor or physical therapist) can reveal the following findings: The affected tendon may appear thicker than the unaffected side.
- There may be some minor swelling around the area of pain.
- Sometimes a poor m.vastus medialis obliquus (VMO) function exist.
- Pain provoked by active tests like squatting, lunging and especially during forceful straightening of the knee from bending maximally on the affected leg.
Additional investigations: ultrasonography or MRI can be useful to determine some degeneration or minor lesions of the patellar tendon.
> Severity
Pain after and during physical activity or sports can be classified into 4 grades of seriousness, from minor till severe:
- Grade 1: Pain only after training.
- Grade 2: Pain before and after exercise but pain reduces once warmed up.
- Grade 3: Pain during activity which prevents you from training or performing at your best.
- Grade 4: Pain during every day activities which may or may not be getting worse.
> Therapy
Two modes of treatment may be advised: conservative (non-surgical) treatment and surgical treatment.
A - Conservative treatment
This is normally advocated initially after diagnosis of patellar tendonopathy. Care must be taken so as to not overload the tendon. Treatment depends on the extent or grade of the injury.
Grade 1:
- Continue training but apply ice or cold therapy to the injury after each training or match. Local applying of ice massage (better than the use of ice packs) at the point of pain on the tendon for 10-15 minutes to reduce pain and inflammation.
- Use a patellar tendon taping (semicircular) or patella brace placed half way the patellar tendon.
- See a sports physician or sports physical therapist who can apply transverse (cross) friction techniques and advise on rehabilitation.
- An eccentric strengthening programme is generally recommended.
Grade 2:
- Modify training activities to reduce the load on the tendon. Stop jumping or sprinting activities and replace them with steady running or swimming or aquajogging if necessary.
- Avoid repetitive bending and straightening movements of the knee.
- See a sports physician or sports physical therapist who can apply transverse (cross) friction techniques and advise on rehabilitation.
Grade 3:
- Rest completely from the aggravating activity.
- Replace it with swimming / running in water (if pain allows).
- See a sports physician or sports physical therapist who can apply transverse (cross) friction techniques and advise on rehabilitation.
Grade 4:
- Rest for a long period of time (at least 3 months!).
- See a sports physician or sports physical therapist who can apply transverse (cross) friction techniques for patella tendinopathy and advise on rehabilitation.
- If the knee does not respond to rehabilitation then consult an orthopaedic surgeon as surgery may be required.
Independent of the staging can be stated:
- A quadriceps muscle strengthening program entails in particular eccentric strengthening. These exercises involve working the muscles as they are lengthening and are thought to maximise tendinopathy recovery.
- Muscle strengthening of other weight bearing muscle groups, such as the calf muscles, may decrease the loading on the patellar tendon.
- A medical doctor can prescribe anti-inflammatory medication e.g. Ibuprofen. Local injections with steroids should be avoided.
- Extracorporal shock wave therapy may be a new and effective treatment.
B - Surgical treatment
This is normally advised as a last resort. Untill now, there is little convincing evidence to support the use of surgery over conservative B treatment for patellar tendinopathy. Surgery either includes excision of the affected area of the tendon or a lateral release where small cuts are made at the sides of the tendon which take the pressure off the middle third. An intensive rehabilitative program is normally advised following surgery. In particular the use of eccentric strengthening exercises may help stimulate healing.
> Braces
A patellar tendon brace reduces loading of the tendon at its insertion by giving pressure through the stiffener (pad) to the knee tendon and the lower edge of the kneecap. Place the patella brace just below the kneecap on the patellar tendon. Application with the affected knee unloaded and bended slightly (20 degrees).
> Misunderstandings
- Continue activities like jumping if they are painful. No! Don't ignore this problem, otherwise it will get worse.
- Tape and brace do weaken your active knee stabilisers. No, they are both useful aids in the rehabilitation and also in the prevention of recurrent complaints without negative consequences at your muscular system.
> Prevention
Prevention of this overuse injury include:
- Strength training of hip abductors including abdominal muscles, hamstrings and calf muscles;
- Stretch exercises of m. quadriceps and hamstrings;
- Wearing good quality sport and daily shoes with custom-made arch support;
- Avoiding overweight.
> Conclusions
- A jumper's knee is due to multiple repetitions of high loads on the patellar tendon in running and jumping sports, characterized by explosive quadriceps contractions.
- There will be pain after sports and exercise, and if the problem progresses, during activity.
- Recovery takes long, and goes with ups and downs, because a lot of etiological factors are involved and some of them are difficult to modify.
- Reduction of traction forces at the lower edge of the kneecap can be attained by tape or brace.
Prof. Dr. F.J.G. Backx, member of the medical committee of the KNKV (Royal Netherlands Korfball Federation), sports physician