Objective The present study is to investigate the characteristic distribution of primary pain points and referred pain areas in patients with knee-joint pain diseases

therefore revealing the correlation between the myofascial trigger point and acupoint sensitization.Methods A total of 483 patients(320 men and 163 women

36 to 72 years in age)with knee-joint pain recruited from 4 clinical centers were observed from July

2017 to April

2019 in the present study.The areas of primary and referred pain in these patients were detected by thumb-pressing and marked on human anatomic atlas.Results Of the 483 enrolled participants

336 had lesion sites or tender points around the injured knee joint

and 147 with myofascial pain syndrome showed referred pain spots(zones)in the knee joint area.In 105 patients with patellar tendonitis

epiphysitis of the tibial tuberosity

or quadriceps tendonitis

the pain area was mainly distributed in the anterior region of the knee.In 76 patients with medial collateral ligament injury

medial meniscal lesion

goose foot bursitis or semimembranosus ending-point inflammation

the pain points mainly occurred in the medial area of the knee.In 127 patients with lateral collateral ligament

lateral meniscus lesion

iliotibial band tendonitis

popliteus or triceps tendinitis

the pain spots were found in the lateral region of the knee.In 28 patients with posterior cruciate ligament injury or popliteal fossa tendonitis

the local pain was found to be at the back of the knee.Referred pain areas were normally detected in the lateral femoral muscles(43 cases)

anterior femoral muscles(39 cases)

adductor group of femur(26 cases)

posterior popliteal fossa muscles group(15 cases)

hamstrings(13 cases)and medial leg(11 cases).Conclusion The primary pain areas or spots of the knee injury mainly distribute around the joint

whereas those of each muscle group lesion are often located in their respective skeletal muscle.Most of the referred pain areas often occur in the distal end of skeletal muscle and around the knee joint.Primary myofascial trigger points may be considered to be an indicator of acupoint sensitization.