| BackgroundThe patients with adult high dislocation of the development dysplasia hip (DDH),can be easy to the length discrepancy of limb,be limited of hip abduction, tilt pelvics,scoliosis, accelerate the degeneration of knee because of abnormal alignment, emerging seriously complications of affecting the patients life. Adult high dislocation DDH display pathological complex of anatomy. So that result to the treatment very is intractable, which is a better way with total arthroplasty hip(THA).However,because of high dislocation,especially,the patients whose the rotatal center of femal head move up more than 4cm from the rotatal center of ture acetabulum,the THA is more challenge.Because the rotatal center of the femoral head is moved up much,and is far from the rotatal center of ture acetabulum. There are difficult to reduce and much the possibility of damage nerve and vessel,especially the sciatic nerve injury. Consequently, there appear a lot of methods be used to strive to solve the problem of reduce and to avoid nerve damaged. It include that to construct the acetabulum at false acetabulum place,to shorten the femur with osteotomy,to release the hip and move down the rotation center of femoral head at the stage,and to achieve the THA at tow stage, et al.However,these methods can decrease the difficulty of reduce and avoid the possibility of nerve injury,meanwhile,and increase the other complication.To treat high dislocation DDH with reconstruction true acetabulum and non-shorten femur osteotomy for THA. Flexin hip can decrease the tension of femal nerve and increase the tension of the sciatic.Adduction hip and flexion knee can decrease the tension of the sciatic.But it need study furtherly the position can change the tension with adduction hip flexion hip and flexion knee.Therefor,for exploring the objective clinical basis,we investage the biomechanics basal experiment of sciatic and reseach at clinics work furtherly.Methods:1. Technique and neural safety management of THA for High dislocation DDH by no shortening osteotomy and the true acetabular reconstructionFrom December 2004 to September 2012,18cases witth high dislocation DDH,include Crowe’s type III or IV, were moved up the rotation center of femoral head,were not the bending deformity in proximal femur,were not the neuromuscular disease.All agreed and were willing to bear all kinds of operation risk,and constituted a good compliance.All of patients were fixed firmly to the operational bed with perineum rung by design ourself,were injected rocuronium with 3 times(E95)to loose the muscle at one minute preoperation,were reduced by strongly,and were managed the sciatic nerve with special position that was hip abduction at30°, hip flexion at 60°, and knee flexion at 90°. All were recorded the distance between the rotation center of ture acetabulum and the rotation center of the femoral head,Harris’hip score preoperation and the end follow-up.All data was processed by SPSS 15.0 software with F-test.2. Impact of the length of the sciatic nerve by.the lower limb position changes with 3D motion model simulatingWe achieved the experiment by computer as following, acguired the human body raw data with spiral CT,constructed three dimensional sport model with Mimics 16.0 software, processed data with geomagic 2013 software,computed the length of imitated sciatic never with UG9.0 software.We computed the length of inimated sciatic at the status of limb,respectively,limb extension;hip abduction at 0°, hip flexion at 60°, and knee flexion at 90°; hip abduction at 30°, hip flexion at 60°, and knee flexion at 90°.3. The biomechanics analysis of tension and displacement of the sciatic nerve by changing position of dog legFour Xiasi dong from Guizhou,were suffered removal of pelvic cavity viscera, were cut off the nerve at the transitional point the sacral plexus and sciatic nerve.were connected the proximal end of sciatic nerve and the tension sensor with no tension thread,were measured the tension and displacement of the proximal end of sciatic at the follow statues,respectively,limb extension;hip abduction at30°, hip flexion at 120°, and knee flexion at 135°; hip abduction at 30°, hip flexion at 60°, and knee flexion at 120°; hip abduction at30°, hip flexion at 60°, and knee flexion at 90°; hip abduction at 30°, hip flexion at 60°, and knee flexion at 60°; hip abduction at 30°, hip flexion at 60°, and knee flexion at 30°.These data were dealed with F-test by SPSS15.0 software.Results1. It can avoid the injury of sciatic neve by hip abduction at 30°, hip flexion at 60°, and knee flexion at 90°,when THA for high dislocation DDH with no shortening osteotomy and ture acetabulum.All patients were got the follow-up,average 76months,from 12months to 108months,that the rotation center of femoral head overlapped with the rotation center of ture acetabulum, that limb extended from 40mm to 68mm (48.65±7.28mm),that the discrepance of limb was 0-16mm(5±4mm) postoperation.The Harris’scores was 87.3± 10.6,that was statistical significance diffcrence between preoperation and postoperation.4 hips suffered from the cleavage fracture at the prosthesis implanting,result to pull out the prosthesis,and then implant again,after binding wire in the proximal femur and small tuberosity, at last,received strong initial stability.3 hips suffered from the sciatic injury incompletely,recovered fully after 4 weeks.2 hips suffered from the disfunction of calf and foot,that the feeling restored after 4 weeks,but that the knee and ankle appeared the pain and MRI no abnormalities,and then restored by treatment afer 2 months.None suffered form femoral injury and other serious complications.2. In the dog’s experiments, hip abduction at30°, hip flexion at 60°, and knee flexion at 90°, sciatic nerve tension is small, can be larger displacement.The tension and displacement of sciatic is smaller with hip abduction at30°, hip flexion at 60°, and knee flexion at 120°.It is larger than hip abduction at30°, hip flexion at 60°, and knee flexion at 90°.But the discrepancy is slightly and no statistical significance between the two groups, P>0.05.Other discrepancy is statistical significance between other two groups,P<0.05. With hip abduction at30°, hip flexion at 60°, and knee flexion at 120°,it result to the sciatic tension smaller and displacement larger.3. In 3D motion model experiments, the mobilizable distance of sciatic nerve is the largest hip abduction at30°, hip flexion at 60°, and knee flexion at 90°.3D motion model can successfully be used to calculate the length of sciatic nerve by three limb position that, limb extension;hip abduction at0°, hip flexion at 60°, and knee flexion at 90°;hip abduction at30°, hip flexion at 60°, and knee flexion at 90°.It manifest that the length of sciatic nerve was the shortest at limb extension,and that the discrepancy was about 27 mm.Conclusions1.We can achieve THA treatment for the adult high dislocation DDH with ture acetabulum reconstruction and no shortening femur osteotomy. It can realize the reducation by firmly fixed position on operational bed,loosed muscle with rocuronium,and appropriately released the soft tissue.It can realize to avoid to injury of the sciatic nerve by hip adduction at 20°, hip flexion at 60°, and knee flexion at 90° meanwhile reducation and by hip abduction at 30°, hip flexion at 60°, and knee flexion at 90° after reducation.2.The 3D motion model can successfully be used to calculate the length of sciatic nerve at different position of hip and knee.With hip abduction at 30°, hip flexion at 60°, and knee flexion at 90°,it is testified that this position can enlarge the length of sciatic nerve,be accompanied with the limb be lengthed,and can decreased the possibility of nerve injury.3.In the motional process of hip and knee,the tension of the sciatic nerve is directly proportional to the tension of limb soft tissue and the range of the hip, and to inversely proportional to the motion of the knee range from 0° to 120°.The displacement of proximal sciatic is inversely proportional to the tension of limb soft tissue and the range of the hip,and to directly proportional to the motion of the knee range from 0° to 120°.With hip abduction at 30°, hip flexion at 60°, and knee flexion at 90°,this position is benefited to decrease the tension of lower limb,and can avoid to sciatic injury better. |
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