BACKGROUND It has been speculated that the patellar J sign may have a negative effect on the clinical outcomes of patients with recurrent patellar dislocation (RPD). PURPOSE To (1) evaluate clinical outcomes, postoperative patellar stability, and patellar maltracking correction in patients with RPD treated with derotational distal femoral osteotomy (DDFO) and combined procedures and (2) investigate the influence of J sign severity on the clinical outcomes. STUDY DESIGN Cohort study; Level of evidence, 3. METHODS Between January 2015 and December 2016, a total of 78 patients (81 knees) with RPD, a positive J sign, and an excessive femoral anteversion angle (FAA; ≥30°) were surgically treated with DDFO and combined procedures. J sign severity was graded according to a previously described classification system (grades 1-3). Routine radiography and computed tomography were performed on every patient to evaluate the patellar height, trochlear dysplasia, genu valgum, tibial tuberosity-trochlear groove distance, patellar lateral tilt angle, and patella-trochlear groove distance. The patellar lateral shift distance during stress radiography was measured preoperatively and postoperatively to quantify medial patellofemoral ligament (MPFL) graft laxity under anesthesia, and "MPFL residual graft laxity" was defined as the patellar ridge surpassing the apex of the lateral femoral trochlea. Patients were evaluated using the Kujala, International Knee Documentation Committee (IKDC), and Lysholm scores preoperatively and postoperatively. Patients were allocated into 3 subgroups in terms of the severity of the J sign: low-grade group 1 (grade 1; n = 19), low-grade group 2 (grade 2; n = 16), and high-grade group (grade 3; n = 12). Subgroup analyses were performed to investigate the influence of a high-grade J sign on the clinical outcomes. RESULTS Among the 78 patients (81 knees), 47 patients (47 knees) met the inclusion criteria. The mean follow-up time was 26.1 ± 1.7 months. The mean preoperative and postoperative FAAs were 36.2°± 5.3° and 10.0°± 2.1°, respectively, with a mean correction angle of 26.2°± 5.9°. At the final follow-up, all patient-reported outcomes improved significantly, and subgroup analyses showed that the high-grade group had significantly lower Kujala scores (75.6 vs 85.3 for low-grade group 1 [P < .001] and 83.4 for low-grade group 2 [P = .001]), Lysholm scores (77.6 vs 84.6 for low-grade group 1 [P = .003]), and IKDC scores (78.6 vs 87.3 for low-grade group 1 [P = .001] and 84.3 for low-grade group 2 [P = .033]) than the low-grade groups. The total rate of MPFL residual graft laxity was 8.5% (4/47), and the prevalence of the postoperative residual J sign was 38.3% (18/47). Subgroup analyses showed significant differences between the high-grade group and the 2 low-grade groups with regard to the MPFL residual graft laxity rate (33.3% vs 0.0% for low-grade group 1 [P = .016] and 0.0% for low-grade group 2 [P = .024]), residual J sign rate (91.7% vs 15.8% for low-grade group 1 [P < .001] and 25.0% for low-grade group 2 [P < .001]), and patellar lateral shift distance (14.2 vs 8.1 mm for low-grade group 1 [P = .002] and 8.7 mm for low-grade group 2 [P = .007]). CONCLUSION In a group of patients treated for RPD with a positive preoperative J sign and increased FAA (≥30°), patients with a preoperative high-grade J sign had inferior clinical outcomes, more MPFL residual graft laxity, and greater residual patellar maltracking.

中文翻译：

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高度J征更可能在经De骨远端股骨截骨术治疗的复发性Pat骨脱位患者中产生更高的术后Pat骨松弛度和残余失调。

背景技术已经推测the骨J征对复发性pa骨脱位（RPD）患者的临床结果可能具有负面影响。目的（1）评价经旋转远端股骨截骨术（DDFO）和联合手术治疗的RPD患者的临床结局，术后pa骨稳定性和pa骨错位矫正，以及（2）研究J征的严重程度对临床结局的影响。研究设计队列研究；证据级别，第3级。方法在2015年1月至2016年12月之间，共对78例RPD，J征阳性和股前倾角过大（FAA；≥30°）的患者（81膝）进行了DDFO手术治疗。组合程序。根据先前描述的分类系统（1-3级）对J号严重程度进行分级。对每位患者进行常规放射线照相和计算机断层扫描，以评估height骨高度，滑车发育不良，膝外翻，胫骨结节-滑车凹槽距离，pa骨侧倾角和tilt骨-滑车凹槽距离。术前和术后测量stress骨X线片在lateral骨外侧移位的距离，以量化麻醉下pa股内侧韧带（MPFL）的松驰度，“ MPFL残留移植物松驰度”定义为股脊超过股骨外侧滑车道顶点。术前和术后使用Kujala，国际膝关节文献委员会（IKDC）和Lysholm评分对患者进行评估。根据J征的严重程度，将患者分为3个亚组：低度1组（1级； n = 19），低年级组2（年级2； n = 16）和高年级组（3年级； n = 12）。进行亚组分析以调查高级J征对临床结局的影响。结果在78例患者（81膝）中，有47例患者（47膝）符合纳入标准。平均随访时间为26.1±1.7个月。术前和术后的平均FAA分别为36.2°±5.3°和10.0°±2.1°，平均矫正角为26.2°±5.9°。在最后的随访中，所有患者报告的结局均明显改善，亚组分析表明，高等级组的Kujala评分显着降低（低等级组1的评分分别为75.6和85.3 [P <.001]，低等级组为83.4 [P <.001]等级2组[P = .001]，Lysholm得分（低等级1组为77.6 vs 84.6 [P = .003]）和IKDC得分（低等级1组为78.6 vs 87.3）[P =。001]和84.3（低等级组2 [P = .033]）低于低等级组。MPFL残余移植物松弛的总发生率为8.5％（4/47），术后残余J征的患病率为38.3％（18/47）。亚组分析显示，高级别组和2个低级别组之间在MPFL残留移植物松驰率方面存在显着差异（低级别1组分别为33.3％和0.0％[P = .016]，低级别1组为0.0％等级2组[P = .024]），剩余J符号率（91.7％对比低等级1组[15.8％[P <.001]和低等级2组25.0％[P <.001]） ，以及lateral骨横向移位距离（低级别组1 [P = .002]为14.2 vs. 8.1 mm；低级别组2 [P = .007]为8.7 mm）。结论在接受RPD治疗的一组患者中，术前J征阳性，FAA升高（≥30°），