Year : 2006 | Volume
: 40 | Issue : 3 | Page : 157--159
Charnley-Hasting bipolar modular replacement option for intracapsular fracture neck femur
Sanjay Agarwala, Abhijit Bhagwat
Department of Orthopaedics, PD Hinduja Hospital & Research Center, Mumbai, India
Department of Orthopaedics, PD Hinduja Hospital & Research center, Mumbai
Background : The consensus of treating a transcervical fracture neck femur in elderly is on replacement surgery. A total arthroplasty is not always the answer especially in patients where stability and mobility need to be balanced especially in patients who cannot comprehend the required changes in the life style & restriction in activity. The traditional method would be a hemiarthroplasty with Austin Moore«SQ»s or Thompsons prosthesis. Both are in the long term associated with loosening, acetabular erosion, pain and loss of mobility.
Method : The present study involves 106 patients who underwent 108 surgeries with a hybrid system of Charnley stems and Hastings bipolar shells, for transcervical fracture neck femurs.
Results : Over all 78% had excellent to good results at threeyear follow up.
Conclusion : The advantage of the system is in the modularity obtained from the different sized Charnley stems, Hasting shell which are available in increments of 1mm allow exact matching of the head and the ease with which the system can be converted to Charnleys low friction Arthroplasty without replacing the stems.
|How to cite this article:|
Agarwala S, Bhagwat A. Charnley-Hasting bipolar modular replacement option for intracapsular fracture neck femur.Indian J Orthop 2006;40:157-159
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Agarwala S, Bhagwat A. Charnley-Hasting bipolar modular replacement option for intracapsular fracture neck femur. Indian J Orthop [serial online] 2006 [cited 2020 Jan 21 ];40:157-159
Available from: http://www.ijoonline.com/text.asp?2006/40/3/157/34482
Management of transcervical fracture neck femur in elderly patients has been varied. The consensus in recent years is on replacement surgery. In the developed world a total hip replacement options goes well with the prevalent life styles. In a developing country like India life style requirement are such that the surgeons have to set a balance between stability and mobility. For a long time the answer to the management of transcervical fractures was a Thompson or Austin Moore's hemi-arthroplasty apart from a trial at fixation. These systems are associated with problem such as loosening and acetabular protrusion. One solution to this problem is in the Bipolar system. Over four year we have offered the Charnley femoral stem matched with Hasting Bipolar head unit as a hybrid bipolar system.
Method and material
Between 1998 and 2002, 105 patients underwent 107 surgeries with Charnley- Hastings bipolar system [Figure 1] (2 had bilateral surgeries) for transcervical fracture of the neck of femur. A single patient was operated for non-union subtrochantric fracture bringing the final total to 106 patients. There were 44 males and 62 females with average age of 70.5 years (range 62 to 90 years). All patients were operated within 48 hours of being admitted to the hospital. Decision to replace with a Charnley- Hasting Bipolar system was based upon
Pre-existing morbid condition. Life expectancy of the patients.Reliability of the patient to understand and follow instructions postoperatively in relation to change in life style.
The operative procedure involved a lateral position with a modified Hardinge approach. The head was carefully extracted and sized. The proximal femur was the prepared for the Charnley stem. A reduction was tried with the trial prosthesis. Cementation of the stem was then carried out in the conventional method (CMW 1 with gentamycin). An appropriate size Hastings bipolar system was then snapped on the Charnley head and the assembly was then reduced. Stability was checked and wound closed in layer over drains. Post-operatively patients were mobilized after 48-72 hours (depending upon pain relief) with a walker frame. Patients were encouraged to take full weight on the operated side and graduated to a walking stick by end of 3 rd week. The duration of stay in the hospital was 11 days on average (5 to 22 days). Serial visits were planned on the 2 nd week, 1 st , 3 rd month and yearly with fresh radiographs.
Of the 106 patients 34 had died or were lost to follow-up leaving 72 surviving patients. All 72 patients were reviewed on an average of 32 months. Grading was carried out using a modified Harris hip score. Radiological findings were separately noted as per Lausten et al  . Overall results were excellent in 23 [Figure 2], good in 33, fair in 9 and poor in 7 patients. Medical complications were deep vein thrombosis in 18 (16 distal, 2 proximal), pulmonary embolism in one and cardio vascular accident in 3 patients. Superficial infection occurred in 4 and deep infection in one patient. Stem loosening was seen in one patient.
The aim of replacement surgery in transcervical fracture neck femur is early return to daily activities. This is particularly applicable to the elderly age group where complications need to be prevented. The objective of the Charnley- Hasting bipolar hybrid system was to allow early and full mobilization in the immediate postoperative period and to maintain a balance between mobility and stability. The long-term benefits would be a reduced incidence of acetabular erosion and prevention of stem loosening and subsequent pain. Most of our patients were mobilized with weight bearing within the 72 hours postoperative period. Delay if at all was due to medical reasons. There were two cases of intraprosthetic dislocation. Both required open reduction but went on to have repeat dislocations. One of which was revised to a Charnley's low friction arhtroplasty with a long posterior wall cup design. The other underwent a Girdlestone arthroplasty. Overall the stability obtained was good. Rae and Paton were the first to report 3 cases of dislocation with this system 2 . They attributed it to the lack of a locking mechanism and the ease with which it was possible to lever the head out of the socket with the neck abutting the edge of the cup. In most of the cases the range of motion was good. Whether the prosthesis behaves as a unipolar or bipolar is debatable. Hodgkinson et all showed in 82.6% cases the hybrid behaved as a bipolar  . Gaine et al had a 70 to 80% intraprosthetic motion in flexion extension in weight bearing  . They also found some variation in motion in weight and non-weight bearing modes. Contrary to these findings we could not demonstrate any intraprosthetic (bipolar) movement in the non weight-bearing mode. A few cases showed some motion in the early phase. This may alter if examined in the weight-bearing mode. Hodgkinson et all demonstrated similar findings 3 . In Chen's series the original Hasting system did not demonstrate any bipolar motion  .
We are unable to comment upon long term acetabular erosion due to relative short follow up. None of our cases showed any signs of early erosion. Probable the best method for evaluation would be stereophotogrammetry  . We had an overall 78% excellent to good result. These are similar to Rae  but less than 96% of Benterud et al , . Most of the series including the present have used the hybrid system in the elderly aged patients. The associated medical conditions remained the major cause for poor result. We have had 32% mortality at follow up.
The advantages of the system then are increased intra operative modularity provided by different types of Charnley's stems. The femoral component is time tested and reliable. Larger sized Hasting shells provide added stability. Shells are separately packed and available in increments of 1mm. This allows accurate matching with the femoral head. The smaller neck allows wider range of motion. Cementation of femoral components prevents loosening, shinkage and pain , . The hybrid system may be converted to a Charnleys low friction arthroplasty by just cementing the acetabular cup without revising the femoral stems. Theoretically the bipolar construct reduces the incidence of acetabular erosion  .
The system lacks a locking mechanism hence the higher rates of intra prosthetic dislocation. The design of the head of both the Charnley and Hastings is hemisperical the poly is thicker on the periphery than in the center. This allows a snap fit mechanism  . The present series has shown a very limited bipolar motion. If this is true in the loaded phase also, it may not be a good option in preexisting OA.
The hybrid Charnley-Hasting system is overall a good alternate to a total hip arthroplasty or hemiarthroplasty in indicated cases. It has the theoretical advantage of revision to a Charnley low friction total hip arthroplasty by simply replacing the Hasting bipolar head and cementing a Charnley acetabular socket should acetabular protrusion occur. The Charnley stem unit provides a great deal of modularity with its different sizes.
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