Trigger points and pressure pain hypersensitivity in people with postmeniscectomy pain

The objectives of this study are (1) to assess the presence of myofascial trigger points (TrPs) and widespread pressure hyperalgesia; and (2) to assess the relationship between the presence of active TrPs, pain intensity, and widespread pressure hypersensitivity in individuals with postmeniscectomy pain.

Thirty-three patients with postmeniscectomy pain, 46 to 60 years of age, and 33 matched controls participated. TrPs were explored bilaterally within the tensor fasciae latae, rectus femoris, vastus lateralis, vastus medialis, adductor magnus, adductor longus, semitendinosus, biceps femoris, and gastrocnemius muscles in a blinded manner. TrPs were considered active if the referred pain reproduced knee symptoms. Pressure pain thresholds (PPT) were also assessed bilaterally over the vastus medialis, vastus lateralis, patellar tendon, second metacarpal, and tibialis anterior. Pain was collected with a numerical pain rate scale (0 to 10).

Patients with postmeniscectomy pain showed a greater (P<0.001) number of active TrPs (mean: 2±1) and a similar number (P=0.611) of latent TrPs (mean: 4±4) than pain-free controls (mean latent TrP: 4±1). A greater number of active TrPs was associated with higher pain intensity (r=0.352; P=0.045). Patients also exhibited reduced PPT over the affected vastus medialis and patellar tendon (P<0.05) and bilaterally over the tibialis anterior muscle (P=0.001). A greater the number of active muscle TrPs was also associated with widespread pressure pain hyperalgesia.

The referred pain elicited by active TrPs reproduced knee symptoms in patients with postmeniscectomy pain. Patients also showed localized reduction of PPT. The number of TrPs was associated with the intensity of pain and pressure hyperalgesia. Our findings suggest the presence of peripheral sensitization in patients with postmeniscectomy pain could be associated with the presence of active TrPs.