Lecuire F, Jaffar-Bandjee Z
Service d'Orthopédie traumatologie Centre Hospitalier départemental Felix Guyon, Saint Denis La Réunion.
Rev Chir Orthop Reparatrice Appar Mot. 1994;80(6):525-31.
Posterior dislocation of Total knee arthroplasty is an infrequent but serious complication. Six cases of this complication were treated from 1979 to december 1993, all occurring on primary arthroplasties.
Knee arthroplasty was performed once for rheumatoid arthritis, five times for osteoarthritis. All cases occurred with a semi constrained prosthesis sacrifying posterior cruciate ligament: 2 Total condylar without posterior stabilisation, and 4 posterior stabilised prosthesis. In one case the dislocation occurred on a very severe rheumatoid arthritis: the patient, confined in a wheel chair, was not reoperated. In two patients, the dislocation was due to rotatory malposition of the tibial component. In the last three cases, we did not found any cause to the dislocation, except ligament laxity: 2 of these patients had, pre operatively, a valgus deformity. In 6 cases, we found only 2 problems on extensor system (one patellar dislocation and one patellectomy).
5 patients required a surgical treatment In 2 cases, we used a more constrained prosthesis, with poor results, but the knee was stable. Once, by changing the position of the tibial component, and using a thicker plate. In 2 patients we only put a thicker tibial polyethylene component. These 3 patients had a good stability: 2 have an excellent result with H.S.S. rating system, the third one has a poor result explained by patellar pseudoarthrosis occurring after traumatic patellar fracture.
With our patients and cases published in North American works, we have studied the different mechanisms of such a posterior dislocation: rotatory disorder on tibial component, ligament laxity in flexion, extensor system deficiency, valgus deformity with important postero lateral release.
The causes of posterior dislocation on Total knee arthroplasties must be known: we have to try to prevent such a complication. If it occurs, a precise analysis will permit a logical curative treatment, which must avoid constrained prosthesis.
全膝关节置换术后后脱位是一种少见但严重的并发症。1979年至1993年12月共治疗6例该并发症患者，均发生于初次置换手术。
膝关节置换手术中，类风湿关节炎患者1例，骨关节炎患者5例。所有病例均采用牺牲后交叉韧带的半限制性假体：2例为无后稳定装置的全髁型假体，4例为后稳定型假体。1例脱位发生在严重类风湿关节炎患者，该患者需坐轮椅，未进行再次手术。2例患者脱位是由于胫骨部件旋转错位。在最后3例中，除韧带松弛外未发现其他脱位原因：其中2例患者术前有外翻畸形。6例患者中，伸肌系统仅出现2个问题（1例髌骨脱位和1例髌骨切除术）。
5例患者需要手术治疗。2例使用了限制性更强的假体，效果不佳，但膝关节稳定。1例通过改变胫骨部件位置并使用更厚的钢板。2例患者仅更换了更厚的胫骨聚乙烯部件。这3例患者膝关节稳定性良好：2例根据H.S.S.评分系统效果极佳，第3例效果不佳是由于创伤性髌骨骨折后发生髌骨假关节。
结合我们的患者及北美文献报道的病例，我们研究了这种后脱位的不同机制：胫骨部件旋转紊乱、屈曲时韧带松弛、伸肌系统缺陷、外翻畸形伴重要的后外侧松解。
必须了解全膝关节置换术后后脱位的原因：我们应努力预防这种并发症。如果发生，精确分析将有助于进行合理的治疗，且必须避免使用限制性假体。
