Department if Orthopedics, University of Zurich, Zurich, Switzerland.
Foot Ankle Int. 2010 Sep;31(9):807-14. doi: 10.3113/FAI.2010.0807.
Controversy exists about the role of metatarsus primus elevatus (MPE) in the presence of hallux rigidus. Previous studies could neither confirm nor reject a causative relationship. Measurement of the true elevation of the first metatarsal according to current techniques lack either precision or accuracy or both. The purpose of this study was to assess MPE by means of a new radiographic measurement method and to analyze how the MPE-values differed among hallux rigidus, hallux valgus and control groups.
A retrospective study was performed of standing AP and lateral radiographs of 295 feet (221 patients; average age 54 years) randomly selected from our databank. According to general radiographic and clinical criteria, 99 were defined as hallux rigidus. Ninety-nine feet had a hallux valgus deformity without severe arthritis. Ninety-seven radiographs with normal MP-I joints and no other forefoot deformity served as a control group. The elevation of the first metatarsal bone in relation to the second metatarsal (MPE), the first metatarsopahlangeal dorsiflexion angle (DFA), the hallux valgus angle (HVA), the intermetatarsal angle (IMA), the interphalangeal angle (IPA) and the degeneration of the first metatarsophalangeal joint were measured. Three independent raters were involved to assess the inter-rater reliability of a new MPE measurement method. For statistic analyses, ANOVA testing was used.
MPE was significantly greater in patients with hallux rigidus (+5.2 mm; 95% CI: 4.7 to 5.7) when compared with hallux valgus (+2.8 mm; 95% CI: 2.2 to 3.4) or the control group (+2.6; 95% CI: 2.0-3.2; p < 0.0001). The DFA was found to be significantly lower in the hallux rigidus group (9 degrees; 95% CI: 8 to 10) when compared with those measured in the hallux valgus (14 degrees; 95% CI: 13 to 16) and control groups (11 degrees; 95% CI: 10 to 12; p < 0.0001). There was a no correlation found between MPE and osteoarthritis at MP-I joint (r = 0.35; p < 0.0001). A moderate correlation was found between increasing MPE and decreasing DFA (r = 0.5; p < 0.0001). The inter-rater reliability of the MPE measurement method was found to be accurate and reproducible (r = 0.9; p < 0.0001).
Based on the findings in this study, an MPE greater than 5 mm could be considered a predictive factor in the presence of hallux rigidus. However, the mechanism of MPE has yet to be determined.
跖骨一升高（MPE）在僵硬拇趾中的作用存在争议。先前的研究既不能证实也不能否定因果关系。根据当前技术测量第一跖骨的真实升高，要么缺乏精度，要么缺乏准确性，要么两者都缺乏。本研究旨在通过一种新的放射测量方法评估 MPE，并分析僵硬拇趾、拇趾外翻和对照组之间 MPE 值的差异。
对我院数据库中随机选择的 295 足（221 例患者；平均年龄 54 岁）的站立前后位和侧位 X 线片进行回顾性研究。根据一般 X 线和临床标准，99 例被定义为僵硬拇趾。99 足有拇趾外翻畸形但无严重关节炎。97 张 X 线片显示 MP-I 关节正常，无其他前足畸形，作为对照组。第一跖骨相对于第二跖骨的升高（MPE）、第一跖趾背屈角（DFA）、拇趾外翻角（HVA）、跖间角（IMA）、指间角（IPA）和第一跖趾关节退变程度进行了测量。涉及三名独立的评估者来评估新的 MPE 测量方法的组内可靠性。统计分析采用 ANOVA 检验。
僵硬拇趾患者的 MPE 明显大于拇趾外翻患者（+5.2mm；95%CI：4.7-5.7）和对照组（+2.6mm；95%CI：2.0-3.2；p<0.0001）。僵硬拇趾组的 DFA 明显低于拇趾外翻组（9°；95%CI：8-10）和对照组（11°；95%CI：10-12；p<0.0001）。MPE 与 MP-I 关节骨关节炎之间无相关性（r=0.35；p<0.0001）。MPE 增加与 DFA 减少之间存在中度相关性（r=0.5；p<0.0001）。MPE 测量方法的组内可靠性被认为是准确和可重复的（r=0.9；p<0.0001）。
根据本研究的结果，MPE 大于 5mm 可被认为是僵硬拇趾存在的预测因素。然而，MPE 的机制尚待确定。
