Modular hip designs offer potential for customising the implant to the patient. However, the more features a device has to offer, the potential for misuse increases. This paper will review one modular stem and the pearls learned over the years to make this a simple and reproducible surgical technique.

Over a 1,000 primary THA have been performed since the development of the proximal modular stem in 2000. The two senior surgeons developed the stem design and surgical techniques used and described here. Two additional surgeon co-authors have used the device as described confirming the design and techniques to be simple, reliable and reproducible.

Often the tricks of the trade go unpublished and each new surgeon is left to his own learning curve with new devices. As with any surgical instrumentation there are significant little techniques that often make surgery more reproducible and enjoyable.

Surgical technique should be simple and reproducible. We have found that even simple procedures—such as head resection—can, and do, impact the surgical process and can affect surgical outcome. Canal reaming, flute engagement, conical reaming, broaching, trochanter clearance, proper use of modular trials and implant assembly all play critical roles to a successful outcome.

We have found, and previously reported, that the use of this proximal modular stem design has reduced our leg length inequalities +/− 5 mm and has all but eliminated dislocations and aseptic loosening.

There were some mechanical failure problems (previously reported) on the first generation modular junction design that was identified and corrected (never exported outside the U.S.). There have been no reported failures since introduction of the improved modular junction six years ago.

Independent selection of femoral offset and vertical height is possible and we feel that restoration of joint mechanics is more reproducible with proximal modular devices as compared to monoblock stems. It is the responsibility of surgeons to communicate their understanding and experience with newer devices and not rely on industry to fill this function.

Dislocation continues to be a significant problem in THA. Instability due to improper reconstruction of the abductors can be a contributing factor.

Eight hundred primary THA’s were performed over the past four years utilizing a proximal “Dual Press™” cementless porous coated modular stem. This design allows for a large selection of proximal bodies that enable the restoration of proper soft tissue tension and joint biomechanics after the stem is inserted.

Data on stem, neck and head centers were available for 600 of these cases. Head center locations were tabulated and compared to data from the literature.

The head center location data clearly showed that a wide variety of offsets and lengths are required to properly balance the soft tissues. Further, when the data were sorted by distal stem diameter, there is little correlation between head center location and stem size. All were performed utilizing the posterior approach and used without bone cement. 3 fractured stems, 2 dislocations, 14 intra-op fractures, no significant leg length inequalities (+/− 5mm), and 10% indexed to a position other than neutral.

Restoration of joint mechanics was possible using this proximal modular “Dual Press” stem due to the intra-operative versatility offered in regards to head center location when compared to monoblock stems. The data suggest that hip reconstruction benefits from the availability of many head centers for every stem size. The authors conclude that this proximal modular design provides for a more intra-operative accurate approach for reconstructing the biomechanics of the hip.