INTRODUCTION
Total hip replacement (THR) is the routinely performed surgical intervention for the management of pain and disability as a result of diseases of hip joint such as osteoarthritis.[1 2 3 4 rd of dislocation can be treated by conservative methods and 1/3rd requires surgical correction. Majority of the prosthetic dislocations are posterior and nearly 70% of dislocations in hip arthroplasty occur in 1st month. However, the dislocation after 4–5 months is primarily due to the muscular imbalance especially the abductor mechanism and malposition of the components.[5 6
CASE REPORT
We present here a 39 years old male patient who meets with an accident in 2013 April and suffers from head injury and right sided pelvic injury. After primary management at local hospital he was taken to a medical college and then to a Private hospital where he was diagnosed as posterior dislocation of hip with undisplaced acetabular fracture [Figure 1 ]. He was then treated with closed reduction and traction [Figure 2 ]. At the end of 3 weeks patient again suffered from severe pain in the hip joint and they lost their faith here at private hospital and shifted the patient to an another private hospital where they did acetabular fixation. But pain was not reduced and patient was unsatisfied and was unable to walk. Patient’s family member then opted for other hospital for treatment. There patient was offered standard cemented modular bipolar prosthesis as part of his treatment [Figure 3 ]. But on 1st post-operative day dislocation was noticed in the ward [Figure 4 ]. On the next day patient was taken to operation theatre where open reduction was done. Patient was made to walk on third postoperative day following which patient noticed severe pain. After that patient lost his faith in the operating surgeon and they decided to shift to other hospital.
Figure 1: Radiograph of Left hip fracture dislocation
Figure 2: Radiograph of Acetabular fixation
Figure 3: Radiograph of cemented Modular bipolar prosthesis
Figure 4: Radiograph showing the dislocation after cemented modular bipolar prosthesis
The whole process nearly took one month and the surgeon found the cemented bipolar prosthesis to be dislocated [Figure 5 ]. Surgical team this time planned to remove the implant and change into an uncemented long stem total hip replacement and the period was September 2013 [Figure 6 ]
Figure 5: Radiograph confirmation of cemented bipolar prosthesis dislocation
Figure 6: Radiograph of uncemented long stem total hip replacement
Patient was in good condition for 10 months. After that suddenly he noticed pain and difficulty in walking and so he went to the concern hospital for check-up where the basic investigations and X rays were normal. With antibiotics pain subsided and patient was persuaded and sent back to his hometown. But very next day the prosthesis got dislocated [Figure 7 ]. Then the patient was admitted to the same hospital where the implant was removed and was revised to long stem cemented total hip arthroplasty [Figure 8 ] and the period was September 2014. After 2 weeks the patient returned to home and was apparently well for a month and was able to walk without pain.
Figure 7: Radiograph showing the dislocation of uncemented long stem total hip replacement
Figure 8: Radiograph of long stem cemented total hip revision arthroplasty
But in October 2014 the patient had dislocation of the prosthesis [Figure 9 ]. In this condition the patient was admitted to our hospital. Through history was taken and clinically examined. CT scan was done with 3D reconstruction to observe acetabular wall deficiency, version and inclination of acetabular component and the femoral stem. He was thoroughly investigated to overruled t he infection and was planned and prepared for a massive revision total hip arthroplasty. Our plan was to remove the implant with minimum bone loss, to do a distal fit interlocked long stem (DePuy Synthes REEF™), to use a constrained acetabular liner and a larger head.
Figure 9: Radiograph showing dislocation of long stem cemented total hip revision arthroplasty
Patient was operated, extended trochanteric osteotomy was done, implants as well the cement was completely removed [Figures 10 , 11 and 12 ]. Acetabulum was completely checked for any deficiency and tight fit Acetabular shell was applied fixed with 2 screws. Constrained liner was applied. Femoral canal was prepared and Reef stem was applied and distally locked. ETO was repaired with SS wire. Trial reduction was done and to our satisfaction and stability was checked. Larger head of 36 mm was applied.
Figure 10: CT scan showing dislocation of long stem cemented total hip revision arthroplasty
Figure 11: Extended trochanteric osteotomy
Figure 12: Removal of Implants
Post-operative period was uneventful. Patient was discharged on 5th postoperative day, stitches were removed on 14th day. Postoperative X-ray was good [Figures 13 and 14 ]. After 7 years patient is walking normally and regularly performing his daily duties.
Figure 13: Removal of cements
Figure 14: Post-operative radiograph showing the complete fixation
DISCUSSION
Recurrent dislocation of hip prosthesis is a devastating problem for the surgeon as well the patient. So there is a need of customized management strategy which suits the patient. Mounting patient related factors are associated with elevated risk of dislocation such as older age, abnormal BMI, low socioeconomic status, addictive disorders and specific comorbidities. Previous spinal fusion and hip surgeries, THR for avascular necrosis, rheumatoid and inflammatory arthritis were the significant predictors for dislocation.[4
In our case the dislocation of THR was recurrent so surgery was the mainstay of treatment. Further the integrity of acetabulum was checked so posterior approach was preferred in spite of the fact the posterior approach has more chances of dislocation. Per operatively we found loosely fitted long cemented stem and incorrect version of acetabular cup which were the major reasons for dislocation. Based on the above findings we did extended trochanteric osteotomy for complete removal of cement mantle. Removal of the cement is the vital and challenging part of the revision surgery. With the help of ETO, the cement and the restrictor was removed under our direct vision. ETO gives a wide exposure and avoid the iatrogenic fractures and bone loss. Previous study done by Park et al. [7 et al. [8 extended trochanteric osteotomy in high congenital hip dislocation. In this study, ETO of 8 cm to 12 cm yielded marked exposure of acetabulum and the femur, reporting a 100% union rate with excellent clinical outcome. Further, after 6 previous surgeries there was always a chance of proximal femoral bony deficiencies and osteopenia. So, distal fit fully HA coated long stem which can be interlocked to provide initial stability made by Depuy Synthes called Reef stem was chosen. To reduce the chances of dislocation, constrained liner was used, though it has longevity issues but we were comfortable with it. Increasing the femoral head size to 36 also reduces the chance of dislocation.
CONCLUSION
Recurrent dislocation of hip arthroplasty is always challenging and there is no clear cut mandate or any established treatment protocol. Further, the risk factors have to be analysed and it is also essential to check the position of implant in safe zone. The treatment has to be customised after detail study of the patients.
Declaration of patient consent
Written informed consent to participate in the study was collected from the patient. Patient was informed that data concerning the case would be submitted for publication and he agreed.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
Acknowledgements
Nil
REFERENCES
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