Knee Pain

Knee, largest joint in our body, is an important weight bearing joint during standing as well as during walking, running, bending and lifting objects. Knee has very strong ligaments for stability and muscles for powerful movement. The joint is formed by thigh bone (femur), two bones of leg (tibia and fibula) and the knee cap (patella). It has three compartments – inner (medial), outer (lateral) and front (patellofemoral). Two ligaments (cruciate) incorporated inside the joint hold the bones together. Two more strong ligaments are placed on either side of the knee. A piece of cartilage (meniscus) intervenes between femur and tibia. The rubbery meniscus acts as a shock absorber and allows free movement of bones over each other. There are a dozen bursas (fluid filled sacs) placed around knee – they allow free sliding of muscles and tendons during movements at knee joint. Quadriceps and hamstrings are powerful muscles placed in front and back of thigh respectively. Quadriceps muscles straighten the knee whereas hamstrings bend the knee and straighten the thigh. Quadriceps narrows down near the knee to form a tendon and ligament which hold knee cap in place and stabilize knee on the front side. The load bearing axis of knee is in a line that runs from hip to ankle. Climbing places 3-4 times body weight stress whereas squatting places about 8 times body weight stress on the knees. Abnormal knee alignments (bow-legs, knock knees) increase risk of osteoarthritis.

Improper use of muscles and overload during movement or exercise leads to knee dysfunction and pain. Hip disease, misalignment of patella and feet abnormalities (e.g. flat feet) can also cause abnormal stress and resultant dysfunction of knee. Knee pain may be associated with other symptoms such as ‘giving way’ or buckling, clicking or crackling sound and locking. Pain originating from structures around knee is generally localized to specific area and does not restrict passive movements.

Injuries of knee ligaments are quite common during sports. Pain starts immediately after the injury but may be difficult to localize. Collateral ligament injuries cause pain on either side of knee whereas cruciate ligament injury is felt deep inside the knee. Pain is present even at rest and worsened by bending of knee, standing and walking. Knee may be swollen and warm. Ligament injuries are initially treated with rest, immobilization and pain killers. An orthopedic consult must be sought at the earliest. Sudden twisting of knee while bearing weight can lead to meniscus injuries. Though a common in sports injuries, meniscal tears have a higher incidence in elderly due to aging cartilage. Mechanical symptoms such as locking, buckling and popping sensation during certain activities are common in meniscal injury. Swelling may or may not be present. Routine X-ray may not be sufficient for diagnosis of ligament of meniscus injury. MRI scan or arthroscopy may be requires in these cases.

Some important conditions causing pain in knee region are as follows:

  1. Baker’s Cyst A swelling on the back of the knee is usually painless and resolves on its own. The bulge is filled with excessive joint fluid. A large cyst may cause some discomfort and restriction of movements. Such cysts can rupture leading to severe pain and swelling in calves. No treatment is usually necessary for small painless cysts except managing the underlying cause such as arthritis. Large cysts may need needle aspiration along with injection of glucocorticoid (steroid). Surgical removal is rarely required.
  2. De Quervain’s Tenosynovitis Pain and swelling of tendon along the base of thumb is known as De Quervain’s tenosynovitis (DQT). Pain may radiate along involved muscles (abductor pollicis longus and extensor pollicis brevis) in the arms. Repetitive occupational injury is the usual cause of DQT. Lifting heavy weights can also strain these muscles. Deviation of closed fist towards little finger will elicit pain in the swollen area. Rest, splintage (especially during work) and pain killers relieve pain to certain extent. Local injection of steroid is useful in most cases. Surgical release is rarely required and may be done in refractory cases.
  3. Prepatellar Bursitis Prepatellar bursa overlies patella. It can swell and be painful due to repeated trauma or strain during occupational overuse (e.g. housemaids, clergymen, roofers, carpet-layers). Warmth and redness may also be associated. Bursitis does not limit joint movements. Prepatellar bursitis can also follow an injury. Treatment consists of rest, ice compresses and pain medications. Needle aspiration and injection of steroid may be required in some cases. Septic bursitis warrants fluid examination and suitable antibiotic. Surgical removal of bursa may be required in septic cases.
  4. Anserine Bursitis This bursitis causes pain on the inner side lower knee (upper end of shin bone). More common in obese middle aged females, this condition leads to pain while climbing or descending stairs. Treatment is similar to prepatellar bursitis.
  5. Infrapatellar Bursitis Infrapatellar bursa is located beneath the patella under the patellar ligament. Bursitis is usually associated with swelling of adjacent patellar tendon due to jumping injury (jumper’s knee). Treatment is similar to that of prepatellar bursitis.
  6. Suprapatellar Bursa  This bursa is located above the patella behind the Quadriceps tendon. Suprapatellar bursa is an extension of knee joint and can swell in knee effusions. Swelling of suprapatellar bursa causes pain and restriction in this region. Puncture wounds in this region can lead to bleeding and sepsis in knee joint. Treatment is similar to that for other bursae.
  7. Chondromalacia patellae This is due to weakening and softening of cartilage beneath patella leading to discomfort and tightness in front of knee. It is more common in women. Knee (knock knees) or foot (flat feet) misalignment predisposes to development of chondromalacia patellae. Pain is aggravated by folding knees and by activities such as running and jumping. Chronic pain restricts activity and leads to weakness of thigh muscles. Initial treatment consists of rest, ice packs and pain killers. Avoid activities that cause knee pain. Supervised physical therapy is essential for recovery. Full recovery is possible although this may require several months or years. Weight reduction hastens recovery from knee pain. Chondromalacia patellae of childhood usually resolves completely in adulthood.
  8. Osgood-Schlatter disease This is swelling of bony attachment of patellar ligament to the upper end of shin bone. This is commonly observed in young enthusiastic athletes involved sports with running or jumping activities (e.g. football). Muscle tendons are stronger than bone in this age group. Pain and swelling at upper end of shin bone is felt during climbing upstairs and worsens with sports. Rest (and sometimes immobilization), ice packs and pain killers is the initial treatment of choice. This should be followed by quadriceps strengthening exercises. Most cases will resolve spontaneously when bone growth stops. A few refractory cases may require surgical treatment.
  9. Iliotibial Band syndrome A thick, strong fibrous band extends from pelvic bone to upper end of shin bone on the outer side of thigh. Iliotibial band syndrome (ITBS) is an overuse friction injury commonly seen in runners, cyclists and military personnel. Pain is localized on the outer and upper side of knee and aggravated by walking (painless to start with) and running downhill. Pain may extend to hip along the fibrous band. Tenderness may be present. Running must be stopped forthwith. Rest, icepacks, painkillers and physiotherapy are successful in most patients. Surgery is rarely indicated and may be contemplated if pain persists for more than 6-9 months despite adequate physical therapy.
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