Background:There is a higher rate of failure of isolated MPFL reconstruction in skeletally immature patients with patellar instability compared to skeletally mature patients. Genu valgum is a known risk factor for patellar instability. There is potential for concomitant surgical correction of genu valgum to achieve better clinical outcomes and to decrease failure rates of MPFL reconstruction.Purpose:To evaluate outcomes of combined medial patellofemoral ligament (MPFL) reconstruction and implant-mediated guided growth (IMGG) in skeletally immature patients with patellar instability and genu valgum.Study Design:Case series; Level of evidence, 4.Methods:In a multicenter study, all skeletally immature patients with recurrent patellar instability and genu valgum who underwent MPFL reconstruction using hamstring graft and IMGG using a transphyseal screw or tension band plate for the distal femur and/or proximal tibia were included. The knee valgus angle and mechanical axis were measured on full-length radiographs and anatomic risk factors were measured on MRI. Patients were followed until correction of their lower limb alignment and implant removal or until skeletal maturity. Clinical outcomes, including complications, were analyzed.Results:A total of 31 patients (37 knees) were included in the study. The mean age and skeletal age of the cohort were 12.4 and 12.9 years, respectively. Simultaneous MPFL reconstruction and IMGG were performed in 26 of 37 knees; 11 underwent staged procedures. Twenty knees had transphyseal screws and 17 knees had tension band plates for IMGG. The knee valgus corrected from a mean of 12.4° to 5.1° in 12.1 months. Implants were removed from 22 of 37 knees once genu valgum was corrected. There was no significant difference ( P = .65) in the correction rate between plates (0.7 deg/month) and screws (0.6 deg/month). Ten complications occurred in 4 patients (7 knees) and included 5 patellar redislocations, 2 rebound valgus, 1 varus overcorrection, 1 knee arthrofibrosis, and 1 implant loosening. For children <10 years of age, 3 of 6 (50%) knees had patellar redislocations and 5 of 6 knees had a complication. This was statistically significant ( P = .003) compared with patients >10 years of age. Similarly, for patients with bilateral knee involvement, 5 of 12 (42%) knees had patellar redislocations and a total of 8 complications occurred in this subset. This was statistically significant ( P < .001) compared with patients with unilateral involvement.Conclusion:IMGG with plates or screws in the setting of combined MPFL reconstruction improves genu valgum. Children <10 years of age and those with bilateral instability with genu valgum remain difficult subsets to treat with higher complication rates.

中文翻译：

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髌骨不稳定和膝外翻的骨骼不成熟患者的 MPFL 重建和植入物介导的生长

背景：与骨骼成熟的患者相比，骨骼不成熟且髌骨不稳定的患者孤立 MPFL 重建的失败率更高。膝外翻是髌骨不稳定的已知危险因素。膝外翻的同步手术矫正有可能获得更好的临床结果并降低 MPFL 重建的失败率。目的：评估骨骼未成熟患者联合内侧髌股韧带 (MPFL) 重建和植入物介导的引导生长 (IMGG) 的结果研究设计：病例系列；证据级别，4。方法：在一项多中心研究中，所有患有复发性髌骨不稳和膝外翻的骨骼不成熟患者均接受了使用腘绳肌移植物进行 MPFL 重建以及使用经骺螺钉或张力带钢板进行股骨远端和/或胫骨近端的 IMGG 重建被包括在内。通过全长 X 光片测量膝关节外翻角和机械轴，并通过 MRI 测量解剖危险因素。对患者进行随访，直至纠正下肢排列并移除植入物或直至骨骼成熟。分析包括并发症在内的临床结果。结果：本研究共纳入 31 名患者（37 膝）。该队列的平均年龄和骨龄分别为 12.4 岁和 12.9 岁。37 个膝关节中的 26 个膝关节同时进行了 MPFL 重建和 IMGG；11 人接受了分阶段程序。对于 IMGG，20 个膝盖有骨骺螺钉，17 个膝盖有张力带板。12.1 个月内，膝关节外翻从平均 12.4° 矫正至 5.1°。膝外翻矫正后，37 个膝盖中的 22 个膝盖中的植入物被移除。板（0.7 度/月）和螺钉（0.6 度/月）之间的矫正率没有显着差异（P = .65）。4 名患者（7 膝）出现 10 项并发症，包括 5 例髌骨再脱位、2 例反弹外翻、1 例内翻过度矫正、1 例膝关节纤维化和 1 例植入物松动。对于 10 岁以下的儿童，6 个膝关节中有 3 个（50%）出现髌骨再脱位，6 个膝关节中有 5 个出现并发症。与 >10 岁的患者相比，这具有统计学意义 (P = .003)。同样，对于双侧膝关节受累的患者，12 个膝关节中有 5 个（42%）出现髌骨再脱位，该亚组中总共出现 8 种并发症。与单侧受累患者相比，这一结果具有统计学意义（P < .001）。结论：在联合 MPFL 重建的情况下，使用钢板或螺钉进行 IMGG 可以改善膝外翻。<10岁的儿童和双侧不稳伴膝外翻的儿童仍然是难以治疗的亚群，并发症发生率较高。