Symptoms and Signs:
Arthrofibrosis can occur after total knee replacement or even partial (unicompartmental) knee replacement. In patients who have knee replacement on both sides, arthrofibrosis may affect only one knee or both knees. Patients have reported this irrespective of whether the knee replacements were done simultaneously or at different times. Localized arthrofibrosis may cause symptoms only with certain physical activities in contrast to diffuse arthrofibrosis which may cause severe restriction of motion and pain or even complete immobilization of the knee.
Normally, after knee replacement, the pain, tenderness, swelling, warmth, and redness steadily decline over two to three weeks. Some amount of stiffness is also common after knee replacement which progressively improves with time. However, in arthrofibrosis, they either persist or worsen.
Arthrofibrosis of the knee is characterized by stiffness. There is inability to bring the knee fully straight (lake of extension or flexion contracture) and decreased bending of the knee (decreased range of flexion). Most patients have both with hard end point to terminal extension and terminal flexion. Arthrofibrosis varies in severity from mild stiffness to complete absence of motion (ankylosis). The stiffness is usually present from the time of knee replacement. Patients feel stiffness or tightness around knee. Patients often describe this as strong pressure or pulling sensation, vice grip like pressure, rubber bands getting tighter and tighter and octopus tentacles wrapped around knee.
Pain is a prominent symptom in arthrofibrosis. Most of the patients have severe pain which is constant and progressively increasing. Sometimes pain is fluctuating with some days better than others. Pain severity may depend on weight-bearing activities. Patients are frequently on narcotic pain medications. Rarely patients have little or no pain. The pain is long standing (chronic) and is felt either in the front of the knee (anterior knee pain) or throughout the knee (diffuse knee pain). The pain is usually present since the initial knee replacement without a painless time interval following the knee replacement. The pain is unexplained, disproportionate and does not progressively subside over time as it normally does after knee replacement (persistent knee pain). Many patients use narcotic pain medications but they only get either little or partial pain relief. The pain may affect sleep with waking up frequently. Patients often feel depressed and rarely even have suicidal thoughts. Patients sometimes use antidepressants in addition.
The pain and stiffness may start immediately after knee replacement or after doing well for some time. Sometimes, patients initially progress well for few weeks after the knee replacement and then the pain and stiffness appear. Pain and tightness may involve not only the knee but also the soft tissues from thigh to calf. Few patients have reported increase in their pain and stiffness with cold weather, changes in the barometric pressure and at night. Knee may tighten up with inactivity and sleep.
There is soft tissue swelling with stretched skin, warmth, redness and pain on manual pressure (tenderness) in and around the knee with inflammation. The soft tissues around knee feel firm (woody fibrosis) or even hard if there is bone formation within the soft tissue (heterotopic ossification).
Scarring (fibrosis) and shortening (contracture) of the extensor mechanism [quadriceps, soft tissue sleeves on either side of patella (medial and lateral retinaculum) and patellar tendon] leads to weak and inefficient quadriceps muscle contraction, failure of the patella to move upwards with quadriceps contraction, restricted side to side (medial-lateral) as well as up and down (superior-inferior) mobility of the patella, limited quadriceps tendon excursion, knee cap (patella) situated lower than its normal position (patella baja – infrapatellar contracture syndrome) and severely limited knee range of flexion.
Knee flexion contracture prevents “screw home” mechanism of the knee at terminal extension which is necessary for relaxing the quadriceps muscle while weight bearing with a fully straight knee. Flexion contracture leads to constant firing of quadriceps muscle and increases the quadriceps work for ambulation (strain) causing quadriceps fatigue, weakness and with time quadriceps wasting (atrophy). This can lead to sense of weakness, instability, giving way, buckling and repeated falls. This can also lead to anterior knee pain, limp and in the long run patello-femoral arthritis in patients with native un-resurfaced patella.
The leg may feel shorter (limb length discrepancy) due to the flexion contracture. This can cause flexed-knee gait, hip pain on the same side, knee pain on the opposite side with low back pain and sacro-iliac joint pain. This leads to difficulty in standing, difficulty in walking, altered walking pattern (gait) with hunched over / crouched walking and profound limp. In addition, knee flexion contracture leads to limb length discrepancy which in turn leads to ankle equinus (heal pulled up). This leads to difficulty in putting foot flat on the ground and walking on the ball of foot. This may necessitate orthopedic shoes.
The patients encounter difficulty in working and difficulty with various activities of daily living like difficulty in sitting on a chair, difficulty getting up from chair, difficulty in ascending or descending stairs (patients often negotiate one step at a time using the normal side or even walk sideways), difficulty in bathing, difficulty in tying shoe lace as well as difficulty in entering, driving, travelling and leaving a car. Frequently, patients need a cane, crutch or walker or rollator. In severe cases, patients are disabled, sedentary and are bound to either a wheelchair or a motorized scooter leading to weight gain. Overall, it affects the quality of life significantly.