Division of Orthopaedic Surgery, Mount Sinai Hospital, University of Toronto, Toronto, ON, Canada.
Orthopedic Department, Rabin Medical Center, Beilinson Hospital, Affiliated to the Sackler Faculty of Medicine, Tel Aviv University, 39 Jabotinsky St., 49100, Petah Tikva, Israel.
Arch Orthop Trauma Surg. 2020 Jun;140(6):777-783. doi: 10.1007/s00402-020-03468-6. Epub 2020 May 5.
Patellar dislocation is a serious complication leading to patient morbidity following total knee arthroplasty (TKA). The cause can be multifactorial. Extensor mechanism imbalance may be present and result from technical errors such as malrotation of the implants. We sought to understand the reasons for post-arthroplasty patellar dislocation and the clinical outcomes of patients in whom it occurs.
This is a retrospective cohort study assessing the outcomes of revision surgery for patellar dislocation in patients with component malrotation in both primary and revision TKAs. Patient demographics, dislocation etiology, presurgical deformity, intraoperation component position, complications, reoperation, and Knee Society Scores (KSS) were collected.
Twenty patients (21 knees) were identified. The average time from primary arthroplasty to onset of dislocation was 33.6 months (SD 44.4), and the average time from dislocation to revision was 3.38 months (SD 2.81). Seventeen knees (80.9%) had internal rotation of the tibial component and seven knees (33.3%) had combined internal rotation of both the femoral and tibial components. Fifteen knees (71.4%) were treated with a condylar constrained implant at the time of revision, and five knees were converted to a hinged prosthesis. The average follow-up time was 56 months. During this time, one patient (4.54%) had a recurrent dislocation episode, requiring further surgery. At final follow up, the mean KSS was 86.2.
Revision TKA following patellar dislocation for patients with malrotated components was associated with high success rates. After revision surgery, patients had a low recurrence of patellar dislocation, low complication rates, and excellent functional outcomes.
髌骨脱位是全膝关节置换术后（TKA）导致患者发病率的严重并发症。其原因可能是多因素的。伸肌机制失衡可能存在，并可能是由于假体旋转不良等技术错误引起的。我们试图了解术后髌骨脱位的原因以及发生脱位的患者的临床结果。
这是一项回顾性队列研究，评估了在初次和翻修 TKA 中存在假体组件旋转不良的患者中，因髌骨脱位而进行翻修手术的结果。收集了患者人口统计学资料、脱位病因、术前畸形、术中组件位置、并发症、再次手术和膝关节学会评分（KSS）。
确定了 20 名患者（21 膝）。从初次关节置换到脱位的平均时间为 33.6 个月（SD 44.4），从脱位到翻修的平均时间为 3.38 个月（SD 2.81）。17 膝（80.9%）有胫骨组件的内旋，7 膝（33.3%）有股骨和胫骨组件的联合内旋。15 膝（71.4%）在翻修时采用了髁限制型假体，5 膝转为铰链假体。平均随访时间为 56 个月。在此期间，1 名患者（4.54%）有复发性脱位发作，需要进一步手术。最终随访时，平均 KSS 为 86.2。
对于有假体组件旋转不良的髌骨脱位患者，翻修 TKA 成功率高。翻修手术后，患者髌骨脱位复发率低、并发症发生率低、功能结果良好。
