Abstract
Background
Total hip replacement is considered the best option for treatment of displaced intracapsular fractures of the femoral neck (FFN). The size of the femoral head is an important factor that influences the outcome of a total hip arthroplasty (THA): implants with a 28mm femoral head are more prone to dislocate than implants with a 32mm head. Obviously, a large head coupled to a polyethylene inlay can lead to more wear, osteolysis and failure of the implant. Ceramic induces less friction and minimal wear even with larger heads.
Methods
A total of 35 THAs were performed for displaced intracapsular FFN, using a 32mm alumina-alumina coupling.
Results
At a mean follow-up of 80 months, 33 have been clinically and radiologically reviewed. None of the implants needed revision for any reason, none of the cups were considered to have failed, no dislocations nor breakage of the ceramic components were recorded. One anatomic cementless stem was radiologically loose.
Conclusions
On the basis of our experience, we suggest that ceramic-on-ceramic coupling offers minimal friction and wear even with large heads.
Background
Fractures of the femoral neck (FFN) are very common in orthopaedic practice. When an intracapsular lesion occurs, it may be treated by either reduction and internal fixation, which preserves the femoral head, or by replacement of the femoral head with an arthroplasty. The aim of both operations is to restore the patient's pre-injury function as quickly as possible.
Garden's classification of proximal femoral fractures is the most widely used, and is useful as it is both simple and predicts the development of AVN1.
- Garden stage I : undisplaced incomplete, including valgus impacted fractures,
- Garden stage II : undisplaced complete fracture,
- Garden stage III : complete fracture, incompletely displaced,
- Garden stage IV : complete fracture, completely displaced.
In view of the much higher failure rate after internal fixation – leading to increased suffering for these patients – primary arthroplasty stands out as the best method for displaced Garden III and IV FFN2.
When a total hip arthroplasty (THA) is performed, the surgeon must take into account dislocation of the implant as a possible complication. This is claimed to be more frequent after a hip fracture treated with the posterior surgical approach, in elderly patients with soft-tissue laxity3.
A report by the Norwegian Arthroplasty Registry underlines the fact that the femoral head size is a risk factor for total hip luxation, and that 28mm heads require revision significantly more often than 32mm, and 26 mm heads more often than 30 mm heads. The preoperative diagnosis, i.e. femoral neck fracture, was also an important factor affecting the revision rate due to luxation4.
We designed a retrospective cohort clinical study to evaluate the results of THAs performed for displaced FFN, using a 32mm alumina-alumina (Al-Al) coupling.
Methods
The study was approved by the Local Ethical Committee and was carried out in compliance with the Helsinki Declaration.
From March 1996 to March 2006, 782 hip arthoplasties were performed at our Institution.
Of these 421 were endoprostheses and 361 arthroprostheses, 244 being elective surgery for coxarthrosis, osteonecrosis etc., and 117 performed for fracture of the femoral neck. Of these 117, 32mm Alumina-Alumina coupling was applied in only 35, while in the remaining 82 different sizes and coupling were adopted. In this study we selected only the 32mm alumina-on-alumina total hip replacements which were performed for femoral neck fractures in patients without co-morbidities nor mental disease and aged <75 years, ensuring a long follow-up.
During this 10-year period, 35 displaced intracapsular fractures of the upper femur (31 females and 4 males) were treated with an alumina-alumina hip replacement. Diagnosis was made on an anteroposterior view of the pelvis and a lateral radiograph of the involved hip (tables 1 and 2). Of these fractures, 17 were classified as Garden III and the remainder as Garden IV (see Table 2).
Median patients age at the time of surgery was 66 years (range 47-75 years). All the operations (involving the right side in 19 cases, the left in 16) were primary procedures (none previously treated with internal fixation), performed in a conventional turbulent flow theatre, via the direct lateral approach described by Hardinge5 to expose the hip joint.
The press-fit cup, hammered into a 2mm under-reamed acetabulum, consisted of a pure titanium core with a titanium alloy mesh: it is grossly hemispherical in shape (with polar flattening and circumferential gutters, and a Triradius-M Cup), with one hole on the apex for the liner, inserted by conical sleeving. This cup was always combined with a 32mm femoral head. Both the inlay and the head were made of dense polycrystalline surgical-grade alumina (Al2O3).
Two additional screw fixations were fitted in 15 cases, in the two further holes of the shell. The mean cup inclination was 44
