作髂前上棘与髌骨中心连线,另作髌骨中心与胫骨结节前方连线,两线成角为Q角。[26]Aglietti P, Insall JN, Cerulli G. Patellar pain and incongruence. I: Measurements of incongruence. Clin Orthop Relat Res. 1983;176:217-224.http://www.ncbi.nlm.nih.gov/pubmed/6851329?tool=bestpractice.com
[Figure caption and citation for the preceding image starts]: Q角由BMJ证据中心提供 [Citation ends].
Q角主要用来评估股四头肌收缩时髌骨向外侧移位的趋势。需要测量Q角以确定是否在正常范围内。
患者仰卧位,伸膝放松小腿。
当膝关节伸直或轻微屈曲时,认为10°-15°为Q角正常范围。[33]Grelsamer RP, McConnell J. The patella: a team approach. Gaithersburg, MD: Aspen Publishers; 1998.Q角越大,髌骨向外侧移位趋势越大。
男性女性Q角的差别主要因为平均身高的差异,[43]Hvid I, Andersen LI. The quadriceps angle and its relation to femoral torsion. Acta Orthop Scand. 1982;53:577-579.http://www.ncbi.nlm.nih.gov/pubmed/7102275?tool=bestpractice.com[44]Livingston LA. The quadriceps angle: a review of the literature. J Orthop Sports Phys Ther. 1998;28:105-109.http://www.ncbi.nlm.nih.gov/pubmed/9699160?tool=bestpractice.com因此可以将身高用作校正因子。[45]Grelsamer RP, Dubey A, Weinstein CH. Men and women have similar Q angles: a clinical and trigonometric evaluation. J Bone Joint Surg Br. 2005;87:1498-1501.http://www.ncbi.nlm.nih.gov/pubmed/16260666?tool=bestpractice.com患者越高,Q角越小。