![]() We performed a hinged total knee arthroplasty (TKA) which corrected the deformity, ligament laxity, and pain and helped him gain complete range of movements. Since the patient was a farmer and involved in heavy labor activities, we decided to avoid arthrodesis of his knee and help him ambulate immediately without any functional limitations. There is no defined protocol for the treatment of arthritic knees in neglected knee dislocations.Ĭase Report: A 54-year-old male presented with pain and limp over his left knee after sustaining a knee dislocation 25 years back which was unsuccessfully reduced by open methods twice. They present with gross degenerative changes and ligament laxity. Introduction: Neglected knee dislocations are a rare entity. This variance in design could explain why the reported outcomes vary and why there is a probability of tibiofemoral dislocation.Ĭite this article: EFORT Open Rev 2021 6:107-112. The mobile part that allows rotation can have various shapes and lengths. ![]() Open reduction of the dislocation should be performed urgently, and provision should be made for revision (that is, the necessary instrumentation should be available) of the RH-TKA, if it proves necessary. In addition, in patients with dislocation of a RH-TKA, the possibility of component failure or breakage must be considered. A closed reduction should not be attempted, because it is unlikely to be satisfactory. Dislocation of a RH-TKA is often a difficult problem to treat. If the circulatory and neurological systems are not properly assessed or if treatment is delayed, limb ischemia, soft tissue death, and the need for amputation can occur. If it occurs, this complication must be accurately diagnosed and treated quickly due to the high incidence of neurovascular complications. Dislocation of RH-TKAs is rare, with an incidence between 0.7% and 4.4%. If complications occur, the options for revision of these implants are limited. However, these implants also have complication rates that cannot be ignored. RH-TKAs have the theoretical advantage of reducing bone implant stresses and early aseptic loosening. As a result, the number of complications related to these procedures will also increase. The number of rotating-hinge total knee arthroplasties (RH-TKAs) is increasing. Our findings may be valuable for understanding the mechanism of potential instability and malfunction due to VM impairment in knee joints after TKA, and may help to optimize clinical/rehabilitation training plans to improve the prognosis (stability and function) of knee joints undergoing TKA. In conclusion, VM impairment in knee joints undergoing TKA may contribute to posterior dislocation of the tibia by a paradoxical roll-back with enhancements of the anterior joint reaction force and external moment during knee-joint flexion. These results indicate that posterior dislocation of the tibia may be induced if VM impairment occurs after TKA. This tendency was also evident in 9 cases in 12 total test pairs (with and without VM impairment). Furthermore, the vectors of the anterior–posterior reaction forces mostly showed a tendency to increase anteriorly due to VM impairment. This tendency was evident in 9 cases in 12 total test pairs (with and without VM impairment). Nevertheless, the vectors of internal–external moments mostly showed a tendency for alteration from external to internal due to VM impairment. The joint reaction forces and moments on knee joints that underwent total knee arthroplasty (TKA) did not differ significantly according to VM impairment status for all flexion angles (p > 0.05). To simulate vastus medialis (VM) impairment, we set the muscle force for VM in the muscle force distribution of the quadriceps at zero (VM: 0 N RF/VI: 49 N VL: 45 N). The muscle force distribution of the quadriceps for the normal loading condition was applied on the basis of muscle cross-sectional area data, as previously reported (VM: 31 N RF/VI: 49 N VL: 45 N). Four pairs of fresh-frozen cadaver knees (eight knees, four male knees) with a mean age of 72 ± 7 years were used for tests involving a customized simulator capable of controlling quadriceps loading conditions.
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