R. M. Smith. F. T. Sheehan, Functional and Applied Biomechanics, Department of Rehabilitation Medicine, National Institutes of Health, Bethesda, MD, USA B. P. Boden MD, The Orthopaedic Center, Rockville, MD, USA.
Clin Orthop Relat Res. 2018 Dec;476(12):2334-2343. doi: 10.1097/CORR.0000000000000499.
Patellofemoral pain is one of the most common forms of knee arthralgia in adolescent females. Unlike in adults, in whom the etiology of patellofemoral pain is considered to be multifactorial (eg, altered bone shape and musculoskeletal dynamics), the etiology of adolescent patellofemoral pain has been historically attributed to overuse. Although it is highly plausible that adolescent patellofemoral pain results from excessive maltracking, as suggested by recent research, an increase in patellar, relative to femoral, size could also contribute to patellofemoral pain through altered cartilage stresses/strains, resulting in overloading of the subchondral bone. Because the role of bone morphology in the genesis of patellofemoral pain in adolescent females remains largely unknown, research is needed in this area to improve our understanding of patellofemoral pain and advance diagnosis/treatment.
QUESTIONS/PURPOSES: (1) Are patellar volume and width increased, and femoral trochlear width decreased, in female adolescents with patellofemoral pain compared with asymptomatic females? (2) Are measures of patellofemoral size correlated with patellofemoral tracking?
Twenty adolescent females with patellofemoral pain (age, 13.7 ± 1.3 years) and 20 asymptomatic female control participants (age, 13.6 ± 1.3 years) were enrolled in this case-control institutional review board-approved study. This study focused on a strict definition of patellofemoral pain, peripatellar pain in the absence of other structural pathologic conditions (eg, tendinitis, ligament injury, Osgood-Schlatter disease) or a history of dislocations/trauma. Control participants with no history of patellofemoral pain or other lower extremity pathology were matched for age (within 6 months) and body mass index (within 5 kg/m). Participants self-referred and were recruited through clinicaltrails.gov, printed advertisements, and word of mouth. Three-dimensional (3-D), static, T1-weighted, gradient recalled echo MR images were acquired, from which 3-D patellofemoral models were created. Patellar volume and width, patellar-to-femoral volume and width ratios, and femoral trochlear width were compared across cohorts. In addition, 3-D patellofemoral tracking was quantified from dynamic MR images captured during cyclical flexion-extension volitional movements of the lower extremity. The size measures and ratios were correlated to patellofemoral tracking.
Compared with control participants, the cohort with patellofemoral pain had greater patellar volume (13,792 ± 2256 versus 11,930 ± 1902 mm; 95% confidence interval [CI], 1336 mm; p = 0.004; d = 0.89) and width (38.4 ± 3.0 versus 36.5 ± 2.7 mm; 95% CI, 1.8 mm; p = 0.021; d = 0.67). The femoral trochlear width was smaller (32.0 ± 1.8 versus 32.9 ± 1.8 mm; p = 0.043, d = 0.54). The patellar-to-femoral volume ratio and the patellar-to-trochlear width ratio were greater in adolescents with patellofemoral pain (0.15 ± 0.02 versus 0.13 ± 0.01, p = 0.006, d = 0.83 and 1.20 ± 0.09 versus 1.11 ± 0.09, p = 0.001, d = 1.02). No correlations were found between patellar size and patellofemoral tracking (r < 0.375, p > 0.103).
In adolescent females with patellofemoral pain, the increased patellar volume/width and patellar-to-trochlear width ratio, along with the decreased femoral trochlear width, may initiate a pathway to pain through improper engagement of the patella within the femoral trochlea. Specifically, the mean differences between cohorts in patellar and femoral trochlear width (1.9 mm and 0.9 mm) are 58% and 37% of the mean patellar and femoral cartilage thickness in females, respectively, as reported in the literature. Further studies are needed to fully elucidate the mechanism of pain.
Level III, prognostic study.
髌股疼痛是青少年女性中最常见的膝关节关节炎形式之一。与成年人不同，成年人的髌股疼痛病因被认为是多因素的（例如，骨骼形状和肌肉骨骼动力学改变），青少年髌股疼痛的病因历史上归因于过度使用。尽管最近的研究表明，青少年髌股疼痛很可能是由于髌股过度跟踪引起的，但髌骨相对于股骨的大小增加也可能通过改变软骨的应力/应变导致髌股疼痛，从而导致软骨下骨的超负荷。由于骨骼形态在青少年女性髌股疼痛的发生中的作用在很大程度上仍然未知，因此需要在这一领域进行研究，以提高我们对髌股疼痛的理解，并推进诊断/治疗。
问题/目的：（1）与无症状女性相比，患有髌股疼痛的女性青少年的髌骨体积和宽度增加，而股骨滑车宽度减小吗？（2）髌股大小的测量值与髌股跟踪是否相关？
这项病例对照的机构审查委员会批准的研究纳入了 20 名患有髌股疼痛的青少年女性（年龄 13.7 ± 1.3 岁）和 20 名无症状的女性对照参与者（年龄 13.6 ± 1.3 岁）。本研究集中于严格定义的髌股疼痛，即髌骨周围疼痛，无其他结构性病理状况（例如，肌腱炎、韧带损伤、Osgood-Schlatter 病）或既往脱位/创伤史。无髌股疼痛或其他下肢病理学病史的对照组参与者在年龄（6 个月内）和体重指数（5kg/m 内）方面相匹配。参与者自我推荐并通过 clinicaltrails.gov、印刷广告和口口相传招募。采集了三维（3-D）、静态、T1 加权、梯度回波磁共振图像，并从这些图像中创建了 3-D 髌股模型。比较了两个队列之间的髌骨体积和宽度、髌骨与股骨的体积和宽度比以及股骨滑车的宽度。此外，从下肢周期性屈伸运动的动态磁共振图像中量化了 3-D 髌股跟踪。对髌股大小的测量值和比值与髌股跟踪进行了相关性分析。
与对照组相比，髌股疼痛组的髌骨体积更大（13792 ± 2256 比 11930 ± 1902mm；95%置信区间[CI]，1336mm；p = 0.004；d = 0.89）和宽度（38.4 ± 3.0 比 36.5 ± 2.7mm；95%CI，1.8mm；p = 0.021；d = 0.67）。股骨滑车的宽度更小（32.0 ± 1.8 比 32.9 ± 1.8mm；p = 0.043，d = 0.54）。患有髌股疼痛的青少年的髌骨与股骨的体积比和髌骨与滑车的宽度比更大（0.15 ± 0.02 比 0.13 ± 0.01，p = 0.006，d = 0.83 和 1.20 ± 0.09 比 1.11 ± 0.09，p = 0.001，d = 1.02）。髌股大小与髌股跟踪之间没有相关性（r < 0.375，p > 0.103）。
在患有髌股疼痛的青少年女性中，髌骨体积/宽度增加以及髌骨与滑车的宽度比增加，同时股骨滑车的宽度减小，可能通过髌骨在股骨滑车内的不当结合引发疼痛途径。具体来说，两个队列之间在髌骨和股骨滑车宽度上的平均差异（1.9mm 和 0.9mm）分别为女性髌骨和股骨软骨厚度的 58%和 37%，如文献中报道的那样。需要进一步的研究来充分阐明疼痛的机制。
III 级，预后研究。
