Advantages
Why Big Heads?
Dislocation following primary and revision total hip arthroplasty continues to be one of the primary factors of early implant failure. Early dislocation still remains a significant problem despite improvements in surgical technique, joint alignment, and implant design. Reported occurrence ranges from 2% to 10% for primary replacement and 10% to 20% for revision arthroplasty.1-4, 8 The introduction of the large diameter CONSERVE® Total Hip femoral heads increases range of motion. This reduces the chance for impingement and subsequent dislocation. Additionally, the CONSERVE® Total Hip system has no skirts thus creating better range of motion. All of these factors coupled with the low wear metal on metal articulation make CONSERVE® Total Hip a great choice for today's orthopaedic surgeon.
Design Rationale
The CONSERVE® Total Hip System with BFH® Technology is designed to eliminate dislocation. Because the human femoral head is large in nature, it therefore makes sense to implant a large, anatomic replacement. This was not possible in the past due to the necessity for polyethylene liners, which decreased the viability of large, anatomic femoral heads. However, with the introduction of metal-on-metal articulation we can now eliminate liners. This not only eliminates the metal liner/metal cup interface, but it allows surgeons to utilize large femoral heads. In fact, the BFH® system has heads ranging from 36-54mm in diameter.
The largest head (54mm) coupled with a -3.5mm head length actually produces 167° range of motion. Along with this incredible range of motion, the CONSERVE® Total Hip System has a theoretical jumping distance of up to 24mm. This means that the femoral head must travel 24mm before it will dislocate, once it impinges.
The BFH® femoral head design gives surgeons the benefits of both large head sizes and low wear implants.
Anatomic Size Femoral Heads
Forget worrying about reaching the largest acetabular size possible just to reach a 36mm femoral head. With the CONSERVE® Total Hip, anatomically sized femoral heads are available for every acetabular size. Femoral heads range from 36-54mm in the CONSERVE® Total Hip system.
SIZE RANGES
| HEAD Outside Diameter |
CUP Outside Diameter |
% INCREASE IN HEAD SIZE vs. 28MM |
|---|---|---|
| 36mm | 46mm | 28 % |
| 38mm | 48mm | 36 % |
| 40mm | 50mm | 43 % |
| 42mm | 52mm | 50 % |
| 44mm | 54mm | 57 % |
| 46mm | 56mm | 64 % |
| 48mm | 58mm | 72 % |
| 50mm | 60mm | 79 % |
| 52mm | 62mm | 86 % |
| 54mm | 64mm | 92 % |
Jump Distance
The result of this increased femoral head diameter is an anatomically sized femoral head with a significantly larger dislocation height. With BFH® Technology, dislocation "jump height" reaches 24mm as compared to 16mm for more traditional size femoral heads.5
CONSERVE® Total Hip System "Jump Distance" and Range of Motion (ROM)
with PERFECTA® Slim Neck Stem (3904-1050)
| HEAD DIAMETER | JUMP DISTANCE | -3.5mm NECK ROM |
+0mm NECK ROM |
+3.5mm NECK ROM |
|---|---|---|---|---|
| 36mm | 16.0mm | 147 | 151 | 155 |
| 38mm | 17.0mm | 148 | 152 | 156 |
| 40mm | 17.9mm | 150 | 153 | 157 |
| 42mm | 18.8mm | 151 | 154 | 157 |
| 44mm | 19.7mm | 152 | 155 | 155 |
| 46mm | 20.7mm | 154 | 156 | 158 |
| 48mm | 21.6mm | 157 | 156 | 159 |
| 50mm | 22.5mm | 161 | 157 | 159 |
| 52mm | 23.4mm | 164 | 158 | 160 |
| 54mm | 24.4mm | 167 | 159 | 160 |
