Year : 2005 | Volume
: 39 | Issue : 2 | Page : 90--92
Clinical and radiological evaluation of hybrid hip replacement in various disorders of hip
BK Dhaon, Vishal Nigam, Anuj Jaiswal, Vineet Jain
Department of Orthopaedics, Maulana Azad Medical College and Lok Nayak Hospital, New Delhi, India
C 401, Jagdambe Apartments, C58/25, Sector 62, NOIDA-201307
Background: High rates of loosening of cemented implants led to change in technique of fixation of the implant.
Methods: Fifty-nine hips were operated in 42 patients with noncemented acetabular and cemented femoral components between January 1999 and July 2003. The average age of the patient was 45.2 years in our study. Preoperative diagnosis was avascular necrosis (28), ankylosing spondylitis (18), fracture neck femur (9), rheumatoid arthritis (2) and osteoarthritis (2).
Results: At an average follow up of 3.6 years (range 1.2-5.8 years) excellent to good results were obtained 92% according to Harris hip criteria. No radiological loosening was noted in any femoral or acetabular component on follow up. One poor result was seen in a case of bilateral ankylosing spondylitis operated on one side.
Conclusion: Hybrid THA provides a viable and highly acceptable method of treatment of diseases of hip in young patients.
|How to cite this article:|
Dhaon B K, Nigam V, Jaiswal A, Jain V. Clinical and radiological evaluation of hybrid hip replacement in various disorders of hip.Indian J Orthop 2005;39:90-92
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Dhaon B K, Nigam V, Jaiswal A, Jain V. Clinical and radiological evaluation of hybrid hip replacement in various disorders of hip. Indian J Orthop [serial online] 2005 [cited 2019 Aug 18 ];39:90-92
Available from: http://www.ijoonline.com/text.asp?2005/39/2/90/36780
The purpose of arthroplasty is to shape the ends of the bones and to hold the surfaces apart, almost always using some material interposed between the fragments. Initially bone cement was used to fix the articulating surfaces of total hip arthroplasty to the bony ends. But high rates of loosening of implants led to change in technique of fixation of the implant.
This technique of cementless THR could be used in younger patients in the hope that it might last longer. However, failures of femoral stem fixation on account of little bone ingrowth, thigh pain and subsidence of cementless femoral component made surgeons to rethink the ideal method of fixation of the femoral stem , . On the other hand, encouraging reports were noted with cementless acetabular component.
Thus the concept of hybrid total hip arthroplasty was evolved ,, , where uncemented acetabular and cemented femoral components were used. We are presenting here our experience of hybrid total hip arthroplasty.
Material and Methods
Between January 1999 to July 2003, 59 hips were operated in 42 patients with a non-cemented acetabular and cemented femoral total hip arthroplasty for various disorders of hip. This procedure was preferred and performed in younger patients (less than 55 years), and a cemented total hip arthroplasty was performed in older patients. There were 25 women and 17 men. Average weight preoperatively was 59 kg (range 48-79 kg). The initial diagnosis was avascular necrosis in 28, ankylosing spondylitis in 18, fracture neck femur in 9, osteoarthritis in 2 and rheumatoid arthritis in 2 hip.
The cemented technique used for femoral stem fixation included the use of distal intramedullary canal cement plug, retrograde filling of the canal with cement gun and cement pressure using the femoral canal compactor. One to three screws were used for the fixation of the acetabular component. Liverpool approach  was used in lateral position with elevation of trochantric sliver for exposure in all patients.
Radiotherapy (700 cG) was given to all patients of ankylosing spondylitis, as they were considered as high-risk candidates for developing heterotopic ossification. Active flexion of the operated hip was allowed from 7 days onwards while maintaining the limbs in abduction. Partial weight bearing progressing to full weight bearing was started from 6 weeks onwards.
The follow up was carried out using interviews and physical examination at 1 ˝ months, 3 months, 6 months, and 1 year and then at yearly intervals. Current sets of radiographs were compared with previous radiographs for any evidence of loosening or heterotopic ossification. Clinical evaluation was based on Harris hip criteria .
Acetabular components were divided into 3 zones  . The acetabular component was assessed on the radiographs of pelvis for initial gaps at the metallic shell-bone interface. The radiographs were also scrutinized for the evidence of bulk migration of the socket in relation to the bone of the pelvis.
For evaluation of the femoral component, the grade of initial cement mantle and the position of the component within the femur were assessed  . The radiolucent line at the bone cement and the cement prosthesis interface were recorded and localized into 7 zones  . Using criteria of Harris et al,  categories of loosening were used to assess roentgenographic stability of the femoral component  . Heterotopic ossification was assessed and graded  .
Preoperatively, the mean Harris hip score was 38 (range 16-58). At an average follow-up of 3.6 years (range 5.8-1.2 years) postoperatively, the mean clinical Harris Hip score had improved to 89 points (range 52 to 97 points).
Fifty eight of the hips had good or excellent rating. Only one hip showed poor results on the clinical criteria. This poor result was in a case of bilateral ankylosing spondylitis. This patient was operated on one side only due to financial constraints. Her other non-operated hip was fused in an unsound position resulting in difficulties in sitting and walking. The operated hip continued to show excellent range of motion without any pain. She gradually adapted herself to this situation, and her Harris hip score improved on follow up.
No postoperative pain was noted in 57 patients. Only two patient reported moderate pain needing analgesic for relief. These were patients of ankylosing spondylitis with Common peroneal nerve palsy post operatively. This CPN palsy was recovering resulting in paresthesias on the affected lower limb. Fifty six patient had no limp or slight limp and only 3 patients had a moderate limp causing use of cane necessary in the opposite hand full time.
The radiographic analysis also demonstrated excellent results. The column of cement distal to the tip of the femoral component was present in all hips. The cement mantle was graded as Grade A (48%), Grade B (28%), Grade C1 (12%) and Grade C2 (12%). No hip had Grade D cement mantle. The femoral component was aligned in neutral position in 48 hips, less than 10 degrees of valgus was present in 6 hips and less than 5 degrees of varus in 5 hips. At the last follow up, no hip showed any evidence of new radiolucency, any shift in the position of the femoral component or any crack in the cement mantle.
Fifteen patients had gaps between bone and the acetabular component on the initial postoperative radiographs. Seven were 1 ˝ mm wide in zone 1 and 2 each. Radiolucency of 1 mm wide was also noticed in five radiographs in Zone 1, two radiographs in zone 2 and one radiograph in zone 3.
Cups were positioned on an average of 46 degrees of abduction (range 28-60 degrees). At the last follow up, no acetabular component showed any evidence of horizontal or vertical migration. No radiolucent lines were seen at the bonecement interface. Heterotopic ossification was present in 14 hips. Ten were graded as Grade 1 and four were Grade 2.
Complications: There were three cases of common peroneal nerve paralysis, all of which recovered on conservative treatment. Four cases had superficial stitch line infection, which subsided on debridement and oral antibiotics. One patient had subluxation of hip on immediate postoperative X-ray. It was a case of avascular necrosis, for which Talwarkar bipolar prosthesis was used in 1978. This hip had become fixed in 80 degree of external rotation deformity. Release of external rotators was done and congruence was restored. One hip had postoperative anterior dislocation, which was reduced under sedation. Limb was kept in internal rotation for 3 weeks, after which patient resumed routine mobilization protocol. Revision for increased anteversion of the femoral stem was not needed in this case, as patient was asymptomatic till last follow up (2.2 years)
Component loosening, one of the major problems with total hip arthroplasty, results in reduced rates of survival of total hip components. Cemented total hip replacement arthroplasty demonstrated excellent survival rates with cemented femoral components , . But the results of acetabular component showed loosening in 5-10 years , .In contrast, results of non-cemented total hip arthroplasty showed favorable result of the acetabular component with high survival rates  , however femoral component was plagued with problems with thigh pain, loosening and subsidence , . Hence non-cemented cup and cemented femoral stem are used using modern cementing techniques.
Preoperative diagnosis in this study had maximum number of cases as avascular necrosis followed by ankylosing spondylitis. Osteoarthritis was responsible for only 2 cases. This is in contrast to many western studies, which show osteoarthritis as the most common diagnosis , .This difference might suggest a predisposition of the Indian population to avascular necrosis and a relative resistance against osteoarthritis.
Rate of infection was very low with no deep infection and only four cases of superficial infection (7%). Chemoprophylaxis was used in all cases (Injection Cephazoline 1 gm 12 hrly, I/v for 5 days) Proper operating room discipline was responsible for this low rate of infection.
Radiological results were excellent in current study. No gaps were found in the follow-up x-rays and no shift in position of the stem was seen. However, due to much shorter follow up as compared to other studies, it would be unfair to compare our results with other studies. Acetabular component also provided us with further support to the hybrid theory. No new radiolucencies were seen in our follow-up. No migration of cup was seen. Radiological results are accepted to show similar good results in further follow-ups as no complication have been seen in our radiographs till date.
Low incidence of heterotopic ossification as compared to other series , is explained by regular administration of high dose of radiation (700 cG) to all high-risk patients (e.g. ankylosing spondylitis) within 48 hours of surgery. However this follow-up up requires to be extended to a longer period for proper evaluation of the incidence of heterotopic ossification.
Thus problems inherent in cemented total hip arthroplasty like high incidence of early loosening of the acetabular component could be avoided by using a noncemented cup allowing bone in growth for fixation. Similarly, a cemented stem using modern methods of cementing, which not only reduced pain but also provided a secure and a long lasting fixation replaced noncemented total hip arthroplasty, which was problematic due to thigh pain and subsidence of the femoral component. This concept of Hybrid THA also provides a viable and highly acceptable method of treatment of diseases of hip in young patients in whom pain free and long lasting method of treatment is needed.
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