Orthopedic implant design has undergone a remarkable evolution over the last few decades, with one of the most significant innovations being the introduction of the collared femoral implant. At Dearborn & Associates Institute for Joint Restoration, serving Fremont and Menlo Park, CA, Dr. John Dearborn is at the forefront of implementing implant technology that prioritizes long-term stability, patient safety, and improved outcomes. Among the newer advancements in hip replacement surgeries, collared femoral implants have demonstrated a strong safety profile, especially in preventing postoperative complications such as implant subsidence and femoral fractures.
Historically, femoral implants used in total hip arthroplasty (THA) were designed as collarless stems, intended to minimize soft tissue disruption and mimic the natural shape of the femur. However, as surgeons and researchers observed the limitations of these designs—particularly in cases involving weaker bone quality or higher functional demands—the development of a collared version became a pivotal response. These designs offer biomechanical advantages that enhance fixation, reduce stress concentration, and improve the integration between implant and bone.
What Is a Collared Femoral Implant?
A collared femoral implant features a flange-like extension, or “collar,” at the top of the stem where it contacts the calcar region of the femur—the dense bone just below the femoral head. This collar acts as a supportive shelf, distributing load and helping to prevent the implant from migrating further into the femoral canal after placement. By transferring stress more efficiently, collared implants not only improve implant stability but also play a key role in reducing the risk of loosening over time.
This design innovation is especially beneficial for patients with osteoporotic or compromised bone, where early subsidence (downward movement of the implant) can lead to leg length discrepancy, altered gait, or implant failure. The collar essentially works like a mechanical stop, helping the implant stay exactly where the surgeon places it during the procedure. Dr. Dearborn frequently utilizes this design feature in patients undergoing hip replacement at both Fremont and Menlo Park locations, tailoring implant selection to each individual’s anatomy and surgical needs.
Safety First: The Risk Reduction Benefits
One of the most compelling reasons for using collared femoral implants is the added level of safety they provide, especially in high-risk patients. Subsidence is one of the most common early complications of cementless total hip replacements. It can result in leg length discrepancies, impaired function, and the need for revision surgery. Collared implants significantly reduce this risk by stabilizing the stem against the cortical bone, limiting the downward motion that often occurs when early bone ingrowth is insufficient to anchor the implant securely.
Another key safety benefit is the reduced incidence of periprosthetic fractures. These fractures can occur when excessive stress is transmitted unevenly through the femur during or after implantation. By offering a more even stress distribution across the proximal femur, the collar lowers the likelihood of such complications. This is particularly useful in patients undergoing revision surgeries or those with weakened femoral bone due to aging or previous trauma. For surgeons like Dr. Dearborn, who manage complex cases, the added layer of protection provided by a collared implant can make a meaningful difference in recovery and outcomes.
Enhanced Integration and Bone Preservation
In addition to improving mechanical stability, collared implants offer advantages in the biological integration between the implant and surrounding bone. The early postoperative period is critical for bone ingrowth, particularly in cementless systems. When the implant subsides or shifts during this phase, it compromises osseointegration. The collar’s design prevents this micro-motion, facilitating better bone-implant bonding and more predictable healing.
Collared designs also encourage bone preservation by reducing stress shielding. Stress shielding occurs when the implant bears too much of the load, leading to bone resorption around the stem. By engaging the metaphyseal region and calcar, the collar ensures a more physiologic load transfer pattern, preserving more of the femur’s natural structure. This is especially important for younger patients or those likely to require revision surgery in the future. A well-preserved bone stock gives surgeons more options and improves long-term success rates.
Addressing Concerns About Collared Implants
While collared femoral implants provide clear benefits, some concerns have been raised about their use, especially relating to surgical technique. Because the collar must rest securely against the calcar, improper seating during surgery could lead to malalignment or improper fit. However, with modern templating software, refined instrumentation, and the expertise of experienced surgeons like Dr. Dearborn, these issues can be effectively mitigated.
Additionally, some early-generation collared implants were bulkier or required more extensive soft tissue management. Today’s designs are much more refined, often featuring a slimmer collar that integrates seamlessly with surrounding anatomy. This makes them a practical option in both primary and revision hip arthroplasties.
Ultimately, any implant—collared or collarless—must be selected based on patient-specific factors. Dr. Dearborn works closely with each patient to evaluate lifestyle, bone quality, and anatomical considerations before selecting the implant that will deliver the safest and most reliable results.
Why It Matters for Patients in Fremont and Menlo Park
For patients at Dearborn & Associates Institute for Joint Restoration, understanding the role of implant design helps empower informed decisions. Whether you’re an active adult looking to return to hiking trails or someone managing the effects of degenerative joint disease, the type of implant used can significantly influence both short- and long-term outcomes.
The use of collared femoral implants reflects a proactive approach to safety and durability. When combined with advanced surgical techniques, personalized treatment plans, and comprehensive aftercare, patients benefit from fewer complications, faster recovery, and more confident mobility. Dr. John Dearborn’s expertise in modern hip replacement strategies, including the use of collared implants, provides residents of Fremont and Menlo Park with access to leading-edge orthopedic care tailored to individual goals.
Resources
Riviere, C., Grappiolo, G., & Engh, C. A. (2018). Collared versus Collarless Femoral Stems in Primary Total Hip Arthroplasty: A Systematic Review. Journal of Arthroplasty.
Holt, G., Hook, S., & Hubble, M. J. (2011). The Role of Collared Stems in Hip Replacement. Hip International.
Falez, F., Casella, F., & Panegrossi, G. (2015). Bone Remodeling Around Collared Cementless Stems. Clinical Orthopaedics and Related Research.
