Department of Rehabilitation Center, Kochi Medical School Hospital, Nankoku, Kochi, Japan.
Department of Orthopedic Surgery, Kochi University, Nankoku, Kochi, Japan.
Eur J Pain. 2018 Nov;22(10):1757-1766. doi: 10.1002/ejp.1271. Epub 2018 Jul 19.
Accumulating evidence indicates that knee pain gives rise to sensory and motor alterations, however, whether different profile of knee pain causes different alterations has not been investigated. The purpose of this experimental study is to clarify characteristics of medial and lateral knee pain and its potential for modulating sensory and motor function in humans.
Fourteen healthy men were included. Medial knee pain (MP) was induced by injection of hypertonic saline (0.5 mL) into the tibial insertion of the medial collateral ligament. For comparison, lateral knee pain (LP) was induced by injection of hypertonic saline identically into the iliotibial tract. Isotonic saline was injected contralaterally as control. Pain intensity was assessed on a continuous electronic visual analogue scale (VAS). Before, during and after the painful state, pressure pain thresholds from the knee (PPTs), maximal isometric muscle strength of the quadriceps and grip power were assessed bilaterally.
MP demonstrated significantly higher VAS scores than LP and compared with control. PPTs decreased on medial and lateral knee in MP but only on the lateral knee in LP. Quadriceps muscle strength and grip power reduced bilaterally in both models, however, MP caused significantly greater reduction of ipsilateral quadriceps strength compared with LP.
Medial knee pain has a greater impact on deep tissue hyperalgesia and reduction of the muscle strength compared with lateral knee pain. This is a novel finding that should be taken into consideration in a treatment strategy for painful knee patients.
The experimental medial knee pain model demonstrated higher pain intensity, more localized pain distribution, widespread deep tissue hyperalgesia and more severe inhibition of muscle strength compared with the lateral knee pain model.
越来越多的证据表明膝关节疼痛会引起感觉和运动改变，然而，不同类型的膝关节疼痛是否会导致不同的改变尚未得到研究。本实验研究的目的是阐明内侧和外侧膝关节疼痛的特征及其对人类感觉和运动功能的潜在调节作用。
纳入 14 名健康男性。内侧膝关节疼痛（MP）通过向内侧副韧带胫骨止点注射高渗盐水（0.5 mL）诱发。为了比较，外侧膝关节疼痛（LP）通过向阔筋膜张肌同样注射高渗盐水诱发。对侧注射等渗盐水作为对照。疼痛强度通过连续电子视觉模拟评分（VAS）评估。在疼痛状态前后，评估双侧膝关节的压力疼痛阈值（PPTs）、股四头肌最大等长肌肉力量和握力。
MP 的 VAS 评分明显高于 LP 和对照组。MP 时内侧和外侧膝关节的 PPTs 降低，但 LP 时仅外侧膝关节的 PPTs 降低。两种模型均双侧股四头肌力量和握力下降，但 MP 导致同侧股四头肌力量的下降明显大于 LP。
与外侧膝关节疼痛相比，内侧膝关节疼痛对深部组织痛觉过敏和肌肉力量的降低影响更大。这是一个新的发现，在治疗膝关节疼痛患者的治疗策略中应考虑这一点。
与外侧膝关节疼痛模型相比，实验性内侧膝关节疼痛模型表现出更高的疼痛强度、更局限的疼痛分布、广泛的深部组织痛觉过敏和更严重的肌肉力量抑制。
